DEVICE AND METHOD OF SHIM ADJUSTING OF DIE-CUSHION DEVICE

Abstract

A plurality of hydraulic cylinders capable of adjusting height direction positions of a plurality of die-cushion pins that are inserted into a plurality of die-cushion pin holes formed in a bolster, respectively, are arranged in a lattice state on a cushion pad, and the hydraulic cylinder faced with a die-cushion pin located below a projection surface of a blank holder in the plurality of hydraulic cylinders is selected. Then, by independently adjusting a height direction position of a piston rod of each of the selected hydraulic cylinders, respectively, the shim adjustment of substantially each of the die-cushion pins is realized.

Claims

1. A shim adjusting device of a die-cushion device having a cushion pad configured to support a blank holder through a plurality of die-cushion pins and a cushion-pad elevating mechanism configured to support the cushion pad and generate a die-cushion force when a slide of a press machine is lowered, the shim adjusting device comprising: a plurality of fluid pressure cylinders disposed on the cushion pad and disposed at positions faced with a plurality of die-cushion pin holes formed in a bolster of the press machine, a lower end of each of the plurality of die-cushion pins inserted into the plurality of die-cushion pin holes being in contact with a piston rod; a fluid pressure device configured to supply an operating fluid independently to each of rise-side pressurizing chambers of the plurality of fluid pressure cylinders, respectively, or discharge the operating fluid from the rise-side pressurizing chamber; and a shim adjustment control device configured to cause the operating fluid to be supplied independently from the fluid pressure device to rise-side pressurizing chambers of fluid pressure cylinders respectively corresponding to die-cushion pins to be used in the plurality of die-cushion pins inserted into the plurality of die-cushion pin holes, the die-cushion pins to be used transmitting a die-cushion force to the blank holder, and independently adjust a height direction position of the piston rod of each of the fluid pressure cylinders respectively corresponding to the die-cushion pins to be used, respectively.

2. The shim adjusting device of a die-cushion device according to claim 1, wherein the shim adjustment control device includes a shim thickness setting device, the shim thickness setting device includes: a die-cushion pin selector configured to select the die-cushion pins to be used in the plurality of die-cushion pins to be inserted into the plurality of die-cushion pin holes; and a shim thickness setter configured to set a plurality of shim thickness set values corresponding to the plurality of die-cushion pins to be used selected by the due-cushion pin selector, the shim thickness setter setting an arbitrary shim thickness set value to each of the die-cushion pins to be used, and the shim adjustment control device causes the operating fluid to be supplied independently from the fluid pressure device to the rise-side pressurizing chambers of the fluid pressure cylinders corresponding to the die-cushion pins to be used, respectively, and independently adjust the height direction position of the piston rod of each of the fluid pressure cylinders respectively corresponding to the die-cushion pins to be used, based on the shim thickness set value of each of the die-cushion pins to be used set by the shim thickness setting device.

3. The shim adjusting control device of a die-cushion device according to claim 2, further comprising: a storage operation unit configured to output a storage instruction for storing at least a shim thickness set value of each of the die-cushion pins to be used in a storage unit in association with a die to be used in the press machine or output a read-out instruction for reading out the shim thickness set value of each of the die-cushion pins to be used from the storage unit in association with the die to be used in the press machine; and a storage control unit configured to, when the storage instruction is input from the storage operation unit, store at least the shim thickness set value of each of the die-cushion pins to be used set by the shim thickness setting device in the storage unit in association with the die to be used in the press machine and when the read-out instruction is input from the storage operation unit, read out the shim thickness set value of each of the die-cushion pins to be used stored in association with the die to be used in the press machine from the storage unit, wherein the shim adjustment control device causes the operating fluid to be independently supplied from the fluid pressure device to the rise-side pressurizing chambers of the fluid pressure cylinders respectively corresponding to the die-cushion pins to be used and independently adjusts the height direction position of the piston rod of each of the fluid pressure cylinders respectively corresponding to the die-cushion pins to be used based on the shim thickness set value of each of the read-out die-cushion pins to be used when the shim thickness set value of each of the die-cushion pins to be used stored in association with the die to be used in the press machine is read out by the storage control unit from the storage unit based on an operation in the storage operation unit.

4. The shim adjusting device of a die-cushion device according to claim 1, wherein the fluid pressure cylinder is a single-rod type fluid pressure cylinder.

5. The shim adjusting device of a die-cushion device according to claim 1, wherein the fluid pressure device includes: a fluid pressure source; a pressurization line through which the operating fluid is supplied from the fluid pressure source; a tank line connected to a tank; a plurality of first solenoid valves disposed in a plurality of lines connecting the rise-side pressurizing chambers of the plurality of fluid pressure cylinders and the pressurization line, respectively; and a plurality of second solenoid valves disposed in each of a plurality of lines connecting the rise-side pressurizing chambers of the plurality of fluid pressure cylinders and the tank line.

6. The shim adjusting device of a die-cushion device according to claim 5, wherein the plurality of first solenoid valves and the plurality of second solenoid valves are non-leak type solenoid valves, respectively.

7. The shim adjusting device of a die-cushion device according to claim 5, wherein the shim adjustment control device controls the first solenoid valve, the second solenoid valve, and the fluid pressure source based on identification information of the plurality of die-cushion pin holes or identification information of the die-cushion pins to be inserted into the plurality of die-cushion pin holes and at least the shim thickness set value of each of the die-cushion pins to be used, independently supplies the operating fluid from the fluid pressure source to the rise-side pressurizing chambers of the fluid pressure cylinders respectively corresponding to the die-cushion pins to be used and independently adjusts the height direction position of the piston rod of each of the fluid pressure cylinders respectively corresponding to the die-cushion pins to be used.

8. The shim adjusting device of a die-cushion device according to claim 7, wherein the shim adjustment control device selects any one die-cushion pin to be used in the die-cushion pins to be used as an adjustment target based on the identification information, adjusts the height direction position of the piston rod of the fluid pressure cylinder corresponding to the die-cushion pin to be used as the adjustment target based on the shim thickness set value set correspondingly to the selected die-cushion pin to be used as the adjustment target and adjusts height-direction positions of piston rods of all the fluid pressure cylinders corresponding to the die-cushion pins to be used by sequentially switching the die-cushion pin to be used as the adjustment target.

9. The shim adjusting device of a die-cushion device according to claim 5, wherein the fluid pressure cylinder includes a spring configured to urge the piston rod in a lowering direction, and the shim adjustment control device adjusts the height direction position of the piston rod of the fluid pressure cylinder by controlling a pressure of the operating fluid supplied to the rise-side pressurizing chamber of the fluid pressure cylinder from the fluid pressure device.

10. The shim adjusting device of a die-cushion device according to claim 9, wherein K.sub.P/X=0.3 MPa/mm to 30 MPa/mm, where a displacement constant of a height position of the piston rod with respect to the pressure of the operating fluid made to act on the rise-side pressurizing chamber of the fluid pressure cylinder is K.sub.P/X.

11. The shim adjusting device of a die-cushion device according to claim 9, wherein the spring is a disk spring disposed in a lowering-side pressurizing chamber of the fluid pressure cylinder.

12. The shim adjusting device of a die-cushion device according to claim 9, wherein the shim adjustment control device controls the operating fluid to be supplied to the rise-side pressurizing chamber of the fluid pressure cylinder from the fluid pressure device based on a pressure instruction of the rise-side pressurizing chamber of the fluid pressure cylinder calculated based on the shim set value set for each of the die-cushion pins to be used and the pressure of the rise-side pressurizing chamber of the fluid pressure cylinder.

13. The shim adjusting device of a die-cushion device according to claim 12, further comprising a pressure detector configured to detect a pressure generated in the pressurization line, wherein the shim adjustment control device controls the pressure of the operating fluid supplied to the pressurization line from the fluid pressure source based on the pressure instruction of the rise-side pressurizing chamber of the fluid pressure cylinder calculated based on the shim set value set for each of the die-cushion pins to be used and a pressure detected by the pressure detector and brings the pressure of the rise-side pressurizing chamber of the fluid pressure cylinder corresponding to a first solenoid valve subjected to ON control in the plurality of first solenoid valves to a pressure corresponding to the pressure instruction.

14. The shim adjusting device of a die-cushion device according to claim 1, further comprising a plurality of position detectors configured to detect height direction positions of piston rods of the plurality of fluid pressure cylinders, respectively, wherein the shim adjustment control device controls the operating fluid supplied to the rise-side pressurizing chamber of the fluid pressure cylinder from the fluid pressure device based on the shim thickness set value and the height direction position of the piston rod detected by the position detector.

15. The shim adjusting device of a die-cushion device according to claim 2, wherein the die-cushion pin selector includes: a display; a first display control unit configured to display at least a first layout and a second layout on a screen of the display, the first layout illustrating a layout of the plurality of die-cushion pin holes or a plurality of die-cushion pins inserted into the plurality of die-cushion pin holes, the second layout illustrating a layout of the die-cushion pin holes into which the die-cushion pins to be used are inserted or the die-cushion pins to be used; and a first operation unit configured to edit the second layout in a dialogue manner while checking the first layout and the second layout displayed on the screen of the display, the first display control unit displays the second layout on the screen of the display in accordance with an operation input from the first operation unit, and the die-cushion pin selector selects the die-cushion pin to be used based on the second layout displayed on the screen of the display.

16. The shim adjusting device of a die-cushion device according to claim 15, wherein the shim thickness setter includes: the display; a second display control unit configured to display a shim thickness set value of each of the die-cushion pins to be used in association with the second layout displayed on the screen of the display, respectively; and a second operation unit configured to edit the shim thickness set value of each of the die-cushion pins to be used to an arbitrary shim thickness set value in dialogue manner, respectively, while checking the shim thickness set value displayed on the screen of the display, the second display control unit displays the arbitrary shim thickness set value edited in accordance with an operation input from the second operation unit on the screen of the display, and the shim thickness setter sets the shim thickness set value displayed on the screen of the display as the shim thickness set value of each of the die-cushion pins to be used.

17. The shim adjusting device of a die-cushion device according to claim 16, wherein the second operation unit has a function of selecting the plurality of die-cushion pins to be used at the same time and editing each of the shim thickness set values of the die-cushion pins to be used selected at the same time into the same shim thickness set value.

18. A shim adjusting method of a die-cushion device using a shim adjusting device of the die-cushion device according to claim 1, comprising: a first step of selecting die-cushion pins to be used in a plurality of die-cushion pins to be inserted into a plurality of die-cushion pin holes; a second step of setting a plurality of shim thickness set values corresponding to the plurality of die-cushion pins to be used selected by the first step to set an arbitrary shim thickness set values to each of the die-cushion pins to be used; a third step of independently adjusting a height direction position of a piston rod of each of fluid pressure cylinders respectively corresponding to the die-cushion pins to be used by causing an operating fluid to be supplied independently from the fluid pressure device to rise-side pressurizing chambers of the fluid pressure cylinders corresponding to the plurality of die-cushion pins to be used based on a shim thickness set value of each of the die-cushion pins to be used set by the second step; and a fourth step of performing a trial by driving a slide of a press machine after adjustment by the third step, wherein processing from the second step to the fourth step is repeated until a quality product is formed by the trial at the fourth step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG. 1 is an outline configuration diagram illustrating an essential part of a press machine 10 and a die-cushion device including a shim adjusting device of the die-cushion device;

[0041] FIG. 2 is a plan view of an essential part of the die-cushion device 100 seen from a direction of an arrow 2 in FIG. 1;

[0042] FIG. 3 is a block diagram of an essential part illustrating a first embodiment of the shim adjusting device of the die-cushion device according to the present invention;

[0043] FIG. 4 is a longitudinal sectional view illustrating constitution of a hydraulic cylinder 210;

[0044] FIG. 5 is a block diagram illustrating constitution of a shim thickness setting device 240;

[0045] FIG. 6 is a plan view of an essential part of the die-cushion device 100 seen from a direction of an arrow 6 in FIG. 1;

[0046] FIG. 7A and FIG. 7B are respectively a sectional view and a plan view of a formed product 22 when the shim adjusting device 200 is not made to function;

[0047] FIG. 8 is a diagram illustrating the shim thickness setting device 240 and particularly is a diagram illustrating an operation screen when a die-cushion pin to be used for actual wrinkle pressing in 55 die-cushion pins is to be selected;

[0048] FIG. 9 is a diagram illustrating the shim thickness setting device 240 and particularly is a diagram illustrating the operation screen in which a shim thickness is set for the selected die-cushion pin to be used;

[0049] FIG. 10 is a diagram illustrating the shim thickness setting device 240 and particularly is a diagram illustrating the operation screen in which a shim thickness set value is checked and the shim thickness set value of the die-cushion pin is partially changed in all the selected die-cushion pins to be used;

[0050] FIG. 11 is a diagram illustrating the shim thickness setting device 240 and particularly is a diagram illustrating the operation screen when shim thickness setting is performed to the selected die-cushion pin to be used;

[0051] FIGS. 12A and 12B are respectively a sectional view and a plan view of a formed product 24 by a first forming trial in which the shim adjusting device 200 is made to function, respectively;

[0052] FIGS. 13A and 13B are respectively diagrams illustrating the hydraulic cylinder 210 when an oil film thickness X of a rise-side pressurizing chamber 210a of the hydraulic cylinder 210 is 0 mm and 0.5 mm, respectively;

[0053] FIG. 14 is a diagram illustrating the shim thickness setting device 240 and particularly is a diagram illustrating a changed state of the shim thickness set value;

[0054] FIG. 15 is a diagram illustrating the shim thickness setting device 240 and particularly is a diagram illustrating a check screen of the shim thickness set value after a second shim thickness adjustment;

[0055] FIGS. 16A and 16B are respectively a sectional view and a plan view of a formed product 26 by a second forming trial in which the shim adjusting device 200 is made to function, respectively;

[0056] FIG. 17 is a table indicating selection information of use/non-use of each of the die-cushion pins stored in a storage unit 249 in association with a die No.;

[0057] FIG. 18 is a table indicating the shim thickness set value of each of the die-cushion pins stored in a storage unit 249 in association with a die No.;

[0058] FIG. 19 is a flowchart illustrating a flow of the entire shim adjusting method;

[0059] FIG. 20 is a flowchart illustrating an example of processing contents of Step S14 illustrated in FIG. 19;

[0060] FIG. 21 is a block diagram of an essential part illustrating a second embodiment of a shim adjusting device of a die-cushion device according to the present invention; and

[0061] FIG. 22 is a longitudinal sectional view illustrating constitution of a hydraulic cylinder 210′ and particularly is a diagram illustrating constitution of a position detector.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0062] Preferred embodiments of a device and a method of shim adjusting of a die-cushion device according to the present invention will be described below in detail by referring to the attached drawings.

Outline Configuration of Press Machine and Die-Cushion Device

[0063] FIG. 1 is an outline configuration diagram illustrating an essential part of a press machine 10 and a die-cushion device including a shim adjusting device of the die-cushion device according to the present invention. FIG. 2 is a plan view of an essential part of the die-cushion device 100 seen from a direction of an arrow 2 in FIG. 1.

[0064] In FIGS. 1 and 2, reference numeral 11 designates a slide of the press machine 10 and reference numeral 12 designates a bed of the press machine 10.

[0065] The slide 11 is guided by a frame (not shown) of the press machine 10 movably in a vertical direction and is moved in an up-and-down direction in FIG. 1 by a crank mechanism (not shown) including a crank shaft to which a rotary driving force is transmitted by a servomotor or a fly wheel.

[0066] On the bed 12 of the press machine 10, a bolster 13 having a plurality of die-cushion pin holes (hereinafter referred to as a “C-hole”) is disposed. In the bolster 13 in this embodiment, 55 (11×5) C-holes arrayed in a lattice state are formed.

[0067] On a lower surface of the slide 11, an upper die 14 is disposed, while on an upper surface of the bolster 13, a lower die 15 is disposed. The upper die 14 in this embodiment is of a die type having a recess portion, while the lower die 15 is of a punch type having a projecting portion corresponding to the recess portion of the upper die 14.

[0068] Between the upper die 14 and the lower die 15, a blank holder (wrinkle pressing plate) 16 is arranged, a lower side of the blank holder 16 is supported by a plurality of die-cushion pins 102 inserted into the C holes in the bolster 13, and a material 20 is set on (in contact with) the upper side of the blank holder 16.

[0069] The press machine 10 performs press-forming of the material 20 between the upper die 14 and the lower die 15 by lowering the slide 11. Moreover, the die-cushion device 100 presses a peripheral edge of the material 20 from the lower side during the press-forming.

[0070] The number of die-cushion pins 102 is 55 which is the same number as the C-holes formed in the bolster 13, and the die-cushion pin 102 located below a projection surface of the blank holder 16 in the 55 die-cushion pins 102 becomes the die-cushion pin 102 transmitting a die-cushion force to the blank holder 16 (hereinafter referred to as a “die-cushion pin to be used”). Moreover, the die-cushion pins other than the die-cushion pin to be used in the 55 die-cushion pins 102 remain in a state inserted into the blank holder 16 in this embodiment and do not function as the die-cushion pin (wrinkle pressing) transmitting the die-cushion force to the blank holder 16.

[0071] The die-cushion device 100 includes a cushion pad 110, right and left two pneumatic cylinders 120L and 120R which function as cushion pad elevating mechanisms for generating a die-cushion force and a shim adjusting device 200 (FIG. 3) having a plurality of fluid pressure cylinders (hydraulic cylinders) 210 which functions as shim thickness generating devices.

[0072] The cushion pad 110 is supported by the pneumatic cylinders 120L and 120R, and a known pressure control circuit, not shown, is connected to cushion-pressure generation-side pressurizing chambers 120a of the pneumatic cylinders 120L and 120R.

[0073] The pressure control circuit controls the die-cushion force by adjusting a pressure generated in the cushion-pressure generation-side pressurizing chambers 120a of the pneumatic cylinders 120L and 120R (pressure of an air tank communicating with the cushion-pressure generation-side pressurizing chamber 120a) during an action of the die-cushion to a desired pressure.

[0074] The cushion-pad elevating mechanism for generating the die-cushion force is not limited to that using the pneumatic cylinders 120L and 120R, and various mechanisms including the one constituted by a hydraulic cylinder, a hydraulic motor for driving this hydraulic cylinder, and a servomotor, a mechanism using a screw-nut mechanism for elevating the cushion pad, a servomotor for driving this screw-nut mechanism, and a hydraulic damper and the like can be applied.

[0075] The plurality of hydraulic cylinders 210 functions as the shim thickness generating devices and is disposed on the cushion pad 110. That is, the plurality of hydraulic cylinders 210 is disposed at positions (under the projection surface of the C-hole) faced with the plurality of C-holes formed in the bolster 13 and disposed so that lower ends of the die-cushion pins 102 to be inserted into the C-holes are brought into contact with the piston rods of the hydraulic cylinders 210.

[0076] FIG. 2 illustrates 55 (11×5) hydraulic cylinders 210 (55 hydraulic cylinders 210.sub.1 to 210.sub.55 indicated by No. 1 to No. 55) arrayed in the lattice state on the cushion pad 110. FIG. 1 illustrates 11 pieces of the hydraulic cylinders 210 in one row in the 55 hydraulic cylinders 210, and in the 11 hydraulic cylinders 210 and 11 die-cushion pins 102 in contact with the piston rods of the 11 hydraulic cylinders 210, the hydraulic cylinders 210 and the die-cushion pins 102 marked with circles are the hydraulic cylinders 210 to be used for the shim thickness adjustment and the die-cushion pins 102 to be used, respectively.

First Embodiment of Shim Adjusting Device of Die-Cushion Device

[0077] FIG. 3 is a block diagram of an essential part illustrating the first embodiment of the shim adjusting device of the die-cushion device according to the present invention.

[0078] The shim adjusting device 200 of the first embodiment illustrated in FIG. 3 includes a plurality (55 pieces) of the hydraulic cylinders 210 (210.sub.1, 210.sub.2, . . . 210.sub.N=55) functioning as shim thickness generating devices, the hydraulic device 220 functioning as a fluid pressure device, and a shim adjustment control device 230.

[0079] FIG. 4 is a longitudinal sectional view illustrating constitution of the hydraulic cylinder 210.

[0080] As illustrated in FIG. 4, the hydraulic cylinder 210 is a single-rod type hydraulic cylinder (single-rod type fluid pressure cylinder) having a single piston rod 212 and includes a spring 214 for urging the piston rod 212 in a lowering direction.

[0081] The spring 214 is preferably a disk spring disposed on a lowering-side pressurizing chamber 210b of the hydraulic cylinder 210. That is because the disk spring can be adjusted to a desired spring constant k by a method of combining (serial and/or parallel stacking of a plurality of) commercial disk springs.

[0082] To the rise-side pressurizing chamber 210a of each of the hydraulic cylinders 210, the operating oil (operating fluid) whose pressure is controlled can be supplied from the hydraulic device 220, respectively.

[0083] Here, a height direction position of the piston rod 212 of the hydraulic cylinder 210 can be adjusted by controlling the pressure of the operating oil to be supplied to the rise-side pressurizing chamber 210a of the hydraulic cylinder 210.

[0084] Here, assuming that a spring constant of the spring 214, a sectional area of the rise-side pressurizing chamber 210a of the hydraulic cylinder, an oil film thickness (shim thickness), a hydraulic pressure (pressure), and a preload are expressed by symbols below, the oil film thickness X can be expressed by [Equation 1]:

[0085] k: spring constant [kN/mm]

[0086] S: sectional area (cm.sup.2) of rise-side pressurizing chamber 210a of hydraulic cylinder

[0087] X: oil film thickness (shim thickness) [mm]

[0088] P.sub.a: hydraulic pressure (MPa)

[0089] F.sub.o: preload (kN)

X=(P.sub.a×S/10−F.sub.o)/k   [Equation 1]

[0090] where in the case of X<0, X=0 in [Equation 1].

[0091] Subsequently, the hydraulic device 220 will be described.

[0092] The hydraulic device 220 includes a hydraulic pump 222 driven by a servomotor 221 functioning as a hydraulic source (fluid pressure source), an encoder 223 which detects an angular velocity of the servomotor 221, a pressurization line 224 through which the operating oil is supplied from the hydraulic pump 222, a tank line 226 connected to a tank 225, a plurality of first solenoid valves VP (VP.sub.1, VP.sub.2, . . . VP.sub.N=55) provided correspondingly to each of the hydraulic cylinders 210, a plurality of second solenoid valves VT (VT.sub.1, VT.sub.2, . . . VT.sub.N=55), a relief valve 227, and a pressure detector 228 which detects the pressure of the pressurization line 224.

[0093] The plurality of first solenoid valves VP is disposed in each of lines connecting the rise-side pressurizing chamber 210a of each of the hydraulic cylinders 210 and the pressurization line 224, while the plurality of second solenoid valves VT is disposed in each of lines connecting the rise-side pressurizing chamber 210a of each of the hydraulic cylinders 210 and the tank line 226.

[0094] Moreover, the plurality of first solenoid valves VP and the plurality of second solenoid valves VT are non-leak type solenoid valves opened when a solenoid is excited (ON) and closed when the solenoid is demagnetized (OFF), respectively.

[0095] The plurality of first solenoid valves VP and the plurality of second solenoid valves VT are normally OFF but either one of the first solenoid valves VP and the second solenoid valves VT in the plurality of first solenoid valves VP and the plurality of second solenoid valves VT is turned ON/OFF by the shim adjustment control device 230 (oil film thickness control device 250) which will be described later. Then, one of the hydraulic cylinders 210 corresponding to the first solenoid valve VP and the second solenoid valve subjected to ON/OFF control becomes (is selected as) the hydraulic cylinder 210 as an adjustment target in the plurality of hydraulic cylinders 210.

[0096] The hydraulic device 220 supplies the operating oil with a required pressure to the rise-side pressurizing chamber 210a of the selected hydraulic cylinder 210 as the adjustment target and adjusts the height direction position (oil film thickness) of the piston rod 212 of the hydraulic cylinder 210.

[0097] When the oil film thickness of the hydraulic cylinder 210.sub.1 is to be adjusted, for example, only the second solenoid valve VT1 corresponding to the hydraulic cylinder 210.sub.1 is turned ON by an ON/OFF control signal from the oil film thickness control device 250 to the first solenoid valve VP and the second solenoid valve VT, while the other first solenoid valves VP and second solenoid valves VT are turned OFF. In this case, the operating oil in the rise-side pressurizing chamber 210a of the hydraulic cylinder 210.sub.1 is discharged to the tank 225 through the second solenoid valve VT1 and the tank line 226 by the preload (1 kN, for example) by the spring 214, whereby the oil film thickness becomes 0 mm.

[0098] Subsequently, after the second solenoid valve VT.sub.1 is turned OFF by the oil film thickness control device 250, the first solenoid valve VP.sub.1 is turned ON. As a result, a pressure oil subjected to the pressure control is supplied from the hydraulic pump 222 only to the hydraulic cylinder 2101 through the pressurization line 224 and the first solenoid valve VP.sub.1.

[0099] Here, the oil film thickness X of the operating oil supplied to the rise-side pressurizing chamber 210a of the hydraulic cylinder 210.sub.1 can be adjusted by controlling the hydraulic pressure P.sub.a as indicated in [Equation 1].

[0100] The pressure detector 228 is to detect the pressure of the pressurization line 224 and outputs a pressure signal indicating the detected pressure to the oil film thickness control device 250 (a pressure control calculator 256 of the pressure control device 252) as a pressure feedback signal when the hydraulic pressure P.sub.a is controlled. Moreover, the encoder 223 outputs an angular velocity signal indicating an angular velocity of a drive shaft of the servomotor 221 to the pressure control calculator 256 as an angular velocity feedback signal for ensuring dynamic stability when the hydraulic pressure P.sub.a is controlled. Moreover, the relief valve 227 is provided as a device which operates at occurrence of an abnormal pressure (at occurrence of accidental abnormal pressure) so as to prevent breakage of the hydraulic equipment.

[0101] Subsequently, the shim adjustment control device 230 will be described.

[0102] The shim adjustment control device 230 includes the shim thickness setting device 240 and the oil film thickness control device 250.

[0103] FIG. 5 is a block diagram illustrating constitution of the shim thickness setting device 240.

[0104] As illustrated in FIG. 5, the shim thickness setting device 240 includes a display 242 such as a liquid crystal display with a touch panel or the like, a display control unit 244 functioning as a first display control unit and a second display control unit, an operation unit 246 functioning as a first operation unit and a second operation unit, a storage control unit 248, and a storage unit 249.

[0105] The operation unit 246 includes various icon buttons (a set button 242c, a confirm button 242d, and an execute button 242e and the like illustrated in FIG. 8) of the touch panel provided on a display screen of the display 242, receives an input by a touch operation by the user, and outputs input information to the display control unit 244.

[0106] Here, the input information input by the operation unit 246 includes selection information of selecting the die-cushion pin 102 to be used for actual wrinkle pressing in the plurality of die-cushion pins 102, the shim thickness set value indicating the oil film thickness (shim thickness) of each of the selected die-cushion pins 102 to be used, information for editing the shim thickness set value, identification information (die No.) of the die indicating the die (the upper die 14, the lower die 15) set on the press machine 10 and the like.

[0107] The display control unit 244 generates an image for display corresponding to the input information based on various types of the input information input from the operation unit 246, outputs the generated image for display to the display 242 and temporarily holds the input information (selection information of use/non-use of each of the die-cushion pins and the shim thickness set value of each of the die-cushion pins to be used) in a buffer memory 244a.

[0108] On the display 242, a screen 242a illustrating a layout (pin layout) illustrating a layout of the 55 (=11×5) die-cushion pins 102 and the like as illustrated in FIGS. 8 to 11, 14, and 15 and the like which will be described later, a select button 242b, the set button 242c, the confirm button 242d, and the execute button 242e which are icon buttons functioning as a part of the operation unit 246, and a screen 242f displaying a message supporting a shim thickness setting operation are displayed based on an image for display input from the display control unit 244.

[0109] The selection information of use/non-use of each of the die-cushion pins and the shim thickness set value of each of the die-cushion pins to be used set by the shim thickness setting device 240 and temporarily stored in the buffer memory 244a are output to the oil film thickness control device 250.

[0110] As described above, the shim thickness setting device 240 includes a function as a die-cushion pin selector which selects the die-cushion pin to be used in the plurality of die-cushion pins 102 inserted into the plurality of C-holes formed in the bolster 13 and a function as a shim thickness setter which sets a plurality of shim thickness set values corresponding to the plurality of die-cushion pins to be used selected by the die-cushion pin selector which are arbitrary shim thickness set values for the die-cushion pins to be used, respectively.

[0111] The storage unit 249 is to store at least the shim thickness set value of each of the die-cushion pins to be used in association with the die (die No.) to be used in the press machine 10 and in this embodiment, information (that is, the selection information of use/non-use of each of the die-cushion pins) indicating the die-cushion pin to be used for the shim adjustment (use “1”) and the die-cushion pin not to be used (non-use “0”) in the plurality of die-cushion pins to be inserted into the plurality of C-holes (C1 to C55: identification information of the C-hole) formed in the bolster 13 for each of the die No. as illustrated in FIG. 17 and the shim thickness set value of each of the plurality of die-cushion pins to be inserted into the plurality of C-holes (C1 to C55) formed in the bolster 13 for each of the die No. as illustrated in FIG. 18 are stored.

[0112] The oil film thickness (shim thickness) is adjusted for each of the die-cushion pins to be used at least by the shim thickness set value of each of the die-cushion pins to be used set as appropriate by the shim thickness setting device 240 and then, by referring to the forming result of the formed product by trial (forming trial), the shim thickness set value of each of the die-cushion pins to be used is re-set (modified). Then, when a storage instruction is input from the operation unit 246 functioning as a storage operation unit, the storage control unit 248 obtains the shim thickness set value of each of the die-cushion pins to be used which is used when a quality product was formed from the buffer memory 244a and has it stored in association with the die used for the forming trial in the storage unit 249.

[0113] On the other hand, if the shim thickness set value of each of the die-cushion pins to be used corresponding to the die (die No.) set on the press machine 10 is stored in the storage unit 249, when the read-out instruction is input from the operation unit 246 functioning as the storage operation unit, the storage control unit 248 reads out the shim thickness set value of each of the die-cushion pins to be used stored in association with the die set on the press machine 10 from the storage unit 249 and outputs it to the display control unit 244 (temporarily stored in the buffer memory 244a).

[0114] As a result, when the die having experienced the shim adjustment by the shim adjusting device 200 is set on the press machine 10, the shim adjustment can be automatically performed. Moreover, though replacement of the die in the press machine 10 can be performed by an automatic die replacing device, as a part of automatic die replacement sequence control of the automatic die replacing device by obtaining the die No. of the die when (after) the die is carried in during automatic die replacement, the shim adjustment can be automatically performed for the die after the replacement as a part of automatic die replacement sequence control by obtaining the die No. of the die when (after) the die is carried in during automatic die replacement.

[0115] The storage unit 249 can store the shim thickness set values corresponding to 100 to 400 dies. Moreover, the storage unit 249 is not limited to that provided in the shim adjusting device 200 (shim thickness setting device 240), but a storage unit (data bank) provided in a PLC (Programmable Logic Controller) in the press machine 10 or the die-cushion device 100, for example, can be used.

[0116] Returning to FIG. 3, the oil film thickness control device 250 is to control the oil film thickness (shim thickness) by controlling the pressure of the rise-side pressurizing chamber 210a of each of the hydraulic cylinders 210 and includes the pressure control device 252.

[0117] The oil film thickness control device 250 inputs the selection information of use/non-use of each of the die-cushion pins and the shim thickness set value of each of the die-cushion pins to be used from the shim thickness setting device 240 as described above and performs the adjustment of the oil film thickness (shim adjustment) sequentially one by one for all the die-cushion pins 102 based on the input information. The oil film thickness control device 250 enables adjustment of the oil film thickness X of the operating oil in the rise-side pressurizing chamber 210a of the hydraulic cylinder 210 corresponding to the one die-cushion pin 102 as an adjustment target by controlling ON/OFF of the first solenoid valve VP and the second solenoid valve VT as described above and calculates the pressure instruction corresponding to the oil film thickness X based on [Equation 1] from the oil film thickness X (that is, the shim thickness set value) to be adjusted.

[0118] The pressure control device 252 includes the pressure instructor 254 and the pressure control calculator 256. In the pressure instructor 254, a pressure instruction calculated for each of the die-cushion pins as adjustment targets is set by the oil film thickness control device 250, and the pressure instructor 254 outputs the set pressure instruction to the pressure control calculator 256.

[0119] To the other inputs of the pressure control calculator 256, a pressure signal indicating the pressure of the pressurization line 224 detected by the pressure detector 228 and an angular velocity signal indicating an angular velocity of the drive shaft of the servomotor 221 detected by the encoder 223 are added, and the pressure control calculator 256 calculates a torque instruction signal for controlling a torque of the servomotor 221 based on the pressure instruction input from the pressure instructor 254 and the pressure signal input from the pressure detector 228. This calculated torque instruction signal is output to the servomotor 221 through a servo amplifier 229, and the drive torque of the servomotor 221 is controlled so that the pressure of the operating oil ejected from the hydraulic pump 222 driven by the servomotor 221 (that is, the pressure detected by the pressure detector 228) becomes a pressure corresponding to the pressure instruction. The angular velocity signal input from the encoder 223 which detects the angular velocities of the drive shaft of the servomotor 221, respectively, is used for compensation for stably controlling the pressure of the operating oil.

[0120] When the pressure of the operating oil ejected from the hydraulic pump 222 is controlled by the pressure control device 252 as above, the hydraulic pressure P.sub.a of the operation oil supplied from the hydraulic pump 222 to the rise-side pressurizing chamber 210a of the hydraulic cylinder 210 as an adjustment target through the pressurization line 224 and the first solenoid valve VP becomes the pressure corresponding to the pressure instruction, and the oil film thickness X (shim thickness) of the rise-side pressurizing chamber 210a of the hydraulic cylinder is adjusted to the shim thickness set value.

[0121] When the oil film thickness control of the hydraulic cylinder 210 as an adjustment target is finished, the first solenoid valve VP corresponding to the hydraulic cylinder 210 as an adjustment target is turned OFF, and the height direction position (oil film thickness) of the piston rod 212 of the hydraulic cylinder 210 is held.

[0122] The adjustment of the oil film thickness (shim adjustment) is performed by performing the oil film thickness control described above by sequentially switching the hydraulic cylinder 210 as an adjustment target.

Shim Adjustment

[0123] Subsequently, the shim adjustment using the shim adjusting device 200 with the constitution above will be described.

[0124] The die used in this embodiment (the upper die 14 and the lower die 15 illustrated in FIG. 1) is to draw a square tube product having a rectangular section from a laterally long material (blank) 20. In this embodiment, initial setting of a die to be used for the first time is assumed.

[0125] FIG. 6 is a plan view of an essential part of the die-cushion device 100 seen from the direction of the arrow 6 illustrated in FIG. 1.

[0126] In FIG. 6, the C-holes are formed at 55 spots indicated by No. 1 to No. 55 in the bolster 13, and the die-cushion pin (55 die-cushion pins in total) is inserted usably in each of the C-holes.

[0127] When this die is to be used, the 24 die-cushion pins No. 2 to No. 10, No. 13, No. 21, No. 24, No. 32, No. 35, No. 43, No. 46 to No. 54 indicated by two-dot chain line circles painted in gray and located at portions pressing the blank holder 16 (functioning as wrinkle presser) in the 55 die-cushion pins are the die-cushion pins to be used for transmitting the die-cushion force to the blank holder 16, and the die-cushion pins indicated by solid-line circles and the other die-cushion pins indicated by outlined two-dot chain-line circles are in a state inserted in the blank holder 16 and do not function as the wrinkle pressers.

[0128] FIGS. 7A and 7B are a sectional view and a plan view of the formed product 22 when the shim adjusting device 200 is not made to function.

[0129] When the shim adjusting device 200 is not made to function, the hydraulic pressure does not act on the rise-side pressurizing chamber of the hydraulic cylinder 210 as illustrated in FIG. 13A, and the piston rod 212 is pressed by the spring 214 and is located at a lowermost limit. Therefore, each of the hydraulic cylinders 210 is in a state where the oil film thickness is not formed (a state of oil film thickness X=0).

[0130] When the shim adjusting device 200 is not made to function (or in the case where the shim adjusting device 200 is not attached to the die-cushion device and when the shim adjustment of each of the die-cushion pins is not performed), the acting die-cushion force basically uniformly (in a distributed manner) acts between each of the die-cushion pins in such square-tube drawing. As a result, the wrinkle pressing function acts more strongly on a corner part of the formed product 22 at which the material basically flows not easily (originally), and a crack 22a is generated (more easily). The wrinkle pressing function acts more weakly on a center part between the corner parts at front and rear as well as right and left (particularly having a longer distance)of the formed product 22 at which the material flows easily (originally and) basically, a drawing wrinkle 22b is generated (more easily).

[0131] Thus, the shim adjusting device 200 is made to function so as to individually control the oil film thickness of each of the hydraulic cylinders 210 and to perform the shim adjustment.

[0132] FIGS. 8 to 11 are diagrams illustrating the shim thickness setting device 240, respectively, and are particularly transition diagrams of the screen (operation screen and the like) of the shim thickness setting device 240 (display 242) when the shim thickness is set.

[0133] FIG. 8 illustrates an operation screen when the die-cushion pin to be used for actual wrinkle pressing in the 55 die-cushion pins is to be selected. As illustrated in FIG. 8, on the screen 242a of the shim thickness setting device 240, a pin layout (first layout) illustrating a layout of the 55 die-cushion pins, the die Nos. and the like are displayed, and on the screen 242f of the shim thickness setting device 240, a message that “Select die-cushion pin to be used” is displayed.

[0134] The user presses (touches) the select button 242b receiving the operation of selecting the die-cushion pin on the operation screen of the shim thickness setting device 240 and then, touches a position number of the die-cushion pin to be used in the first layout of the 55 die-cushion pins displayed on the screen 242a and selects the die-cushion pin to be used. In the first layout displayed on the screen 242a, a pin layout (second layout) illustrating a layout of the die-cushion pin to be used selected by the touch is displayed capable of being discriminated from the first layout including the die-cushion pins not in use.

[0135] FIG. 9 illustrates the operation screen for setting the shim thickness for the selected die-cushion pin to be used. As illustrated in FIG. 9, on the screen 242a of the shim thickness setting device 240, the second layout of the 24 selected die-cushion pins to be used is displayed, and on the screen 242f of the shim thickness setting device 240, a message that “Set shim thickness of No. 35=” “ ” and a ten key 242g are displayed.

[0136] The user presses the set button 242c for setting the shim thickness on the operation screen of the shim thickness setting device 240 and sequentially (in the order of the die-cushion pin position numbers) inputs (sets) the shim thickness for the selected die-cushion to be used by the ten key 242g.

[0137] In this embodiment, the shim thickness set values at the die-cushion pin positions at four corner parts are set to 0 mm and the other shim thickness set values to 0.5 mm.

[0138] FIG. 9 illustrates a state where the setting of the shim thicknesses of 13 die-cushion pins to be used in the 24 die-cushion pins to be used has been completed. Moreover, if the same shim thickness is to be set, a collective cushion pin position number range can be specified so that the shim thickness is set collectively (at once).

[0139] FIG. 10 illustrates the operation screen in which the shim thickness set value is confirmed and the shim thickness set value of the die-cushion pin is partially changed in all the selected die-cushion pins to be used.

[0140] As illustrated in FIG. 10, on the screen 242a of the shim thickness setting device 240, a pin layout of the 24 die-cushion pins to be used are displayed, and the shim thickness set value is displayed on a pin display portion of each of the die-cushion pins. Moreover, on the screen 242f of the shim thickness setting device 240, a message that “Select die-cushion pin whose shim thickness is to be changed” is displayed.

[0141] The user presses the confirm button 242d for confirming the shim thickness set value on the operation screen of the shim thickness setting device 240 and causes the set shim thickness set value to be listed/displayed with respect to all the selected die-cushion pins to be used.

[0142] Then, when the set shim thickness set value is to be partially changed, the user touches the pin display portion to be changed on the operation screen and changes the shim thickness set value by re-input. In this embodiment, since the confirm button 242d also functions as a change button for changing the shim thickness set value, the change button is not provided, but the change button may be provided separately.

[0143] FIG. 11 illustrates the operation screen when the shim thickness setting is being executed for the selected die-cushion pin to be used.

[0144] The user presses the execute button 242e of the shim adjustment on the operation screen of the shim thickness setting device 240 and executes the shim thickness adjustment based on the set shim thickness set value for all the selected die-cushion pins to be used.

[0145] In this case, on the screen 242f of the shim thickness setting device 240, a message that “Shim thickness is being adjusted” is displayed. Moreover, the shim thickness setting device 240 outputs the selection information of use/non-use of the each of the die-cushion pins and the shim thickness set value of each of the set die-cushion pins to be used to the oil film thickness control device 250.

[0146] According to the shim thickness setting device 240 of this embodiment, by operating the operation unit 246 (by touching the touch panel) in a dialogue manner while checking the operation screen of the shim thickness setting device 240, the shim thickness set value of each of the die-cushion pins to be used can be set.

[0147] The oil film thickness control device 250 executes adjustment of the oil film thickness (shim adjustment) one by one in the order for all the die-cushion pins 102 as described above based on the shim thickness set value of each of the die-cushion pins to be used set by the shim thickness setting device 240.

[0148] The spring 214 disposed in the lowering-side pressurizing chamber of the hydraulic cylinder 210 in this embodiment has the (relatively weak) spring constant k (=3.66 [kN/mm]) by combining a plurality of the disk springs, and a sectional area S of the rise-side pressurizing chamber 210a of the hydraulic cylinder 210 is 28.27 [cm.sup.2].

[0149] As illustrated in FIG. 13A, when the oil film thickness X of the rise-side pressurizing chamber 210a of the hydraulic cylinder 210 is 0 mm, the preload of 1 kN is made to act by compressing the spring 214 by approximately 0.27 mm so that a stable shim thickness amount “0” is ensured. The hydraulic pressure P.sub.a at this time is a pressure when it is open to the tank 225 through the tank line 226 and it is 0 Pa (atmospheric pressure).

[0150] On the other hand, as illustrated in FIG. 13B, when the shim thickness set value (oil film thickness X) is 0.5 mm, the hydraulic pressure P.sub.a made to act on the rise-side pressurizing chamber 210a of the hydraulic cylinder 210 before the die-cushion action is I MPa. This hydraulic pressure P.sub.a (=1 MPa) can be calculated by substituting the oil film thickness X (=0.5 mm), the sectional area S (=28.27 cm.sup.2), the preload Fo (=1 kN), and the spring constant (=3.66 [kN/mm]) in [Equation 1].

[0151] Then, by executing control by the oil film thickness control device 250 and the hydraulic device 220 so that the hydraulic pressure of the rise-side pressurizing chamber 210a of the hydraulic cylinder 210 becomes 1 MPa, the piston rod 212 of the hydraulic cylinder 210 rises to a position where the preload is offset and moreover, the spring 214 is compressed by 0.5 mm (that is, a position where the force for raising the piston rod 212 by the hydraulic pressure at 1 MPa and the urging force by the spring 214 compressed with the rise of the piston rod 212 are balanced) and stops.

[0152] Here, the reason why the spring 214 is constituted relatively weakly is to improve sensitivity of adjustment of the oil film thickness generated in the rise-side pressurizing chamber 210a with respect to the pressure of the operating oil made to act on the rise-side pressurizing chamber 210a of the hydraulic cylinder 210.

[0153] When the displacement constant Km indicated in the following equation is defined by the displacement amount X [mm] of the height position of the piston rod 212 with respect to the pressure P (MPa) of the operating oil acting on the rise-side pressurizing chamber 210a of the hydraulic cylinder 210, the displacement constant K.sub.P/X is preferably within a range of K.sub.P/X=0.3 [MPa/mm] to 30 [MPa/mm]:

K.sub.P/X=10×k/S   [Equation 2]

[0154] In this embodiment, the displacement constant K.sub.P/X is a value obtained by multiplying 10 in order to match a unit with that of a value obtained by dividing the spring constant k (3.66 [kN/mm]) by the rise-side pressurizing chamber sectional area S of the hydraulic cylinder (28.27 [mm]) and it is approximately 1.295 [MPa/mm] from [Equation 1].

[0155] When the shim adjusting device 200 is operated as above, and the shim adjustment for all the die-cushion pins 102 is finished, the user allows the press machine 10 to function and performs a first forming trial (trial).

[0156] In the first forming trial, the shim thickness of the die-cushion pin to be used at the four corner parts is adjusted to 0 mm as illustrated in FIG. 10 and the like, and the shim thicknesses of the other die-cushion pins to be used are adjusted to 0.5 mm.

[0157] FIGS. 12A and 12B are respectively a sectional view and a plan view of the formed product 24 by the first forming trial when the shim adjusting device 200 is made to function.

[0158] As illustrated in FIG. 12B, a shape of the formed product 24 still shows a tendency of similarity to a shape of the formed product 22 (FIG. 7) when the shim adjusting device 200 is not made to function, but a dimension of the crack 24a at the corner part of the formed product 24 in which the material does not flow easily is contracted, and drawing wrinkles 24b at the center part between the corner parts of the front and rear as well as right and left (particularly having a longer distance) in the formed product 24 at which the material can flow easily are reduced.

[0159] <Verification of Shim Thickness Maintaining Performance of Shim Thickness Generating Device>

[0160] Subsequently, shim thickness maintaining performances of the hydraulic cylinder 210 functioning as the shim thickness generating device when the die-cushion is acting will be described.

[0161] In this embodiment, the die-cushion force when the die-cushion is acting is 1200 kN. Since the number of the die-cushion pins 102 to be used is 24, approximately 50 kN acts on a single die-cushion pin. On the 20 die-cushion pins whose shim thicknesses are adjusted to 0.5 mm, a die-cushion force larger than that on the four die-cushion pins whose shim thicknesses are adjusted to 0 mm acts, but for facilitation of the explanation, it is assumed below that 50 kN acts on a single die-cushion pin whose shim thickness is adjusted to 0.5 mm.

[0162] Therefore, assuming that a pressure generated in the rise-side pressurizing chamber 210a of the hydraulic cylinder 210 in press forming is P.sub.a′, it is 17.69 MPa (=(50/28.7)×10).

[0163] On the other hand, since the hydraulic pressure (1 MPa in this embodiment) corresponding to the shim thickness has acted in advance on the hydraulic cylinder 210 whose shim thickness was adjusted to 0.5 mm as described above, assuming that a pressure change of the rise-side pressurizing chamber 210a of the hydraulic cylinder 210 before and after the press forming is ΔP.sub.a, the pressure change ΔP.sub.a is ΔP.sub.a=P.sub.a′−P.sub.a=17.69−1=16.69 MPa.

[0164] At this time, a capacity of the rise-side pressurizing chamber 210a of the hydraulic cylinder 210 in proportion to the oil film thickness (shim thickness) is compressed by the portion of the pressure change ΔP.sub.a (boost) and is contracted. Here, assuming that a modulus of elasticity K of volume of the operating oil is 1200 (MPa) and a contraction amount is ΔX [mm], the contraction amount ΔX is approximately 0.007 mm as indicated in the following equation:

ΔX=(ΔP.sub.a/K)×X=(16.69/1200)×0.5≈0.007 [mm]  [Equation 3]

[0165] In the end, the oil film thickness (shim thickness) during forming (after contraction) is 0.493 (=0.5−0.007) mm, and 0.5 mm set at the beginning is substantially maintained.

[0166] From the result of the formed product 24 by the first forming trial illustrated in FIG. 12, the shim thickness set value set in the first forming trial is partially changed (modified) in order to further improve the formed product (suppressing a crack and a drawing wrinkle of the formed product).

[0167] FIG. 14 is a diagram illustrating the operation screen of the shim thickness setting device 240 and particularly illustrates a state where the shim thickness set value is changed.

[0168] The user presses the confirm button 242d for confirming the shim thickness set value on the operation screen of the shim thickness setting device 240 and causes the shim thickness set values set at present to be listed/displayed for all the selected die-cushion pins to be used.

[0169] Subsequently, the user touches the pin display portions of the die-cushion pins to be used whose shim thicknesses are to be changed (collectively for those to be changed to the same shim thickness) in the 24 die-cushion pins to be used. On the screen 242a of the shim thickness setting device 240 illustrated in FIG. 14, the pin display portions of the touched four die-cushion pins to be used are displayed capable of being discriminated from the pin display portions of the other die-cushion pins to be used. Moreover, on the screen 242f of the shim thickness setting device 240, a message that “Set shim thickness of selected pin (group)” and the ten key 242g are displayed.

[0170] The user inputs the shim thickness set value again by the ten key 242g in order to change the shim thickness set value of the die-cushion pin to be used corresponding to the touched pin display portion. In this embodiment, since the crack 24a is generated at the corner part of the formed product 24 in the first forming trial as illustrated in FIG. 12B, the shim thickness set value in the vicinity of the corner part is changed from 0.5 mm to 0.3 mm. That is for the purpose of preventing a crack from being generated by lowering the wrinkle suppressing force (pressure) in the vicinity of the corner part.

[0171] FIG. 15 illustrates a confirmation screen of the shim thickness set value after a second shim thickness adjustment. Finally, as illustrated on the screen 242a of the shim thickness setting device 240, the shim thickness set values in the vicinity of the four corner parts of the formed product are lowered for preventing a crack with respect to the first shim thickness set values and are (continuously) increased in order to suppress drawing wrinkles at the center part between the right and left as well as front and rear corner parts.

[0172] Then, similarly to the first shim adjustment, the user presses the execute button 242e so as to execute the second shim adjustment. In this case, it is preferable that the shim adjusting device 200 applies only the shim adjustment to the die-cushion pin to be used whose shim thickness set value was changed.

[0173] When the second shim adjustment is finished by the shim adjusting device 200, the user operates the press machine 10 and performs the second forming trial.

[0174] FIGS. 16A and 16B are respectively a sectional view and a plan view of a formed product 26 by the second forming trial in which the shim adjusting device 200 is made to function.

[0175] The formed product 26 illustrated in FIG. 16B becomes a quality product in which a crack at the corner part of the formed product disappears and drawing wrinkles at the center part between the front and rear as well as right and left corner parts of the formed product disappear as the result of proper shim adjustment.

[0176] As described above, when a quality product is formed, the user operates the operation unit 246 functioning as the storage operation unit and causes a storage instruction for storing the selection information of use/non-use of each of the die-cushion pins set by the shim thickness setting device 240 and the shim thickness set value of each of the die-cushion pins when the quality product is formed in association with the die (die No.) in the storage unit 249 to be output from the operation unit 246 to the storage control unit 248.

[0177] When the storage instruction is input from the operation unit 246, the storage control unit 248 obtains the selection information of use/non-use of each of the die-cushion pins held in the buffer memory 244a and the shim thickness set value of each of the die-cushion pins from the buffer memory 244a and has them stored in association with the die No. subjected to the forming trial in the storage unit 249.

[0178] FIGS. 17 and 18 are lists illustrating the selection information of use/non-use of each of the die-cushion pins and the shim thickness set values stored in association with the die No. in the storage unit 249, respectively.

[0179] The selection information of use/non-use of each of the die-cushion pins illustrated in FIG. 17 is information corresponding to position information (C1 to C55) of the C-holes of each of the dies and formed in the bolster 13 into which the 55 die-cushion pins are inserted, and this information uses “1” for the die-cushion pin to be used for actual wrinkle pressing and “0” for the die-cushion pins not to be used for the wrinkle pressing in the 55 die-cushion pins.

[0180] According to this selection information of use/non-use of each of the die-cushion pins, whether each of the die-cushion pins is a die-cushion pin to be used or a die-cushion pin not to be used can be discriminated for all the die-cushion pins. For the die-cushion pin not to be used, the shim adjustment can be set to unnecessary (shim thickness=0).

[0181] The shim thickness set value of each of the die-cushion pins illustrated in FIG. 18 is information corresponding to position information (C1 to C55) of the C-holes of each of the dies and formed in the bolster 13 into which the 55 die-cushion pins are inserted and is a shim thickness set value of each of the die-cushion pins set for each of the die-cushion pins.

[0182] In the example illustrated in FIG. 18, the shim thickness set value (including the shim thickness set value=0) is set for all the die-cushion pins, but when there is the selection information of use/non-use of each of the die-cushion pins as illustrated in FIG. 17, it is only necessary that the shim thickness set value is set at least to the die-cushion pin to be used.

[0183] Moreover, in FIGS. 17 and 18, the selection information of use/non-use of each of the die-cushion pins corresponding to the 55 dies (dies No. 1 to No. 55) and the shim thickness set values are illustrated, but the shim thickness set values corresponding to several hundred dies can be stored in the storage unit 249.

[0184] As described above, since the shim thickness set value is stored in association with the die in the storage unit 249, when the die having experienced the shim adjustment by the shim adjusting device 200 is set on the press machine 10, the shim adjusting device 200 can automatically perform the shim adjustment by reading out the shim thickness set value stored in association with the set die from the storage unit 249 and by performing the shim thickness adjustment for each of the die-cushion pins based on the read-out shim thickness set value.

Shim Adjusting Method

[0185] FIGS. 19 and 20 are flowcharts illustrating an embodiment of a shim adjusting method using the shim adjusting device 200 according to the present invention.

[0186] FIG. 19 is a flowchart illustrating a flow of the entire shim adjusting method.

[0187] In FIG. 19, reference character m designates a parameter indicating the number of times of the shim adjustment, and the first shim adjustment is m=1 (Step S10).

[0188] The user operates the shim thickness setting device 240 of the shim adjusting device 200 and performs the m-th (the first time is m=1) setting of the shim thickness (Step S12).

[0189] When the m-th shim thickness setting is performed, the oil film thickness control device 250 controls the oil film thickness (cylinder internal pressure) of the rise-side pressurizing chamber 210a of each of the hydraulic cylinders 210 based on the shim thickness set value of each of the die-cushion pins for which the shim thickness was set.

[0190] FIG. 20 is a flowchart illustrating an example of processing contents of Step S14 illustrated in FIG. 19 and particularly is a flowchart illustrating an operation of the oil film thickness control device 250 of the shim adjusting device 200.

[0191] In FIG. 20, a parameter n is set to n=1 (Step S100). Here, the parameter n indicates a position number of any one die-cushion pin in the 55 die-cushion pins from No. 1 to No. 55, and n=1 indicates the No. 1 die-cushion pin.

[0192] The oil film thickness control device 250 determines whether or not the n-th die-cushion pin is a die-cushion pin to be used for wrinkle pressing based on the selection information (see FIG. 17) of use/non-use of each of the die-cushion pins input from the shim thickness setting device 240 (Step S102). If it is determined that the n-th die-cushion pin is a die-cushion pin not to be used (in the case of “No”), the routine proceeds to Step S104.

[0193] At Step S104, the second solenoid valve VTn provided correspondingly to hydraulic cylinder 210.sub.n for controlling the height direction position of the n-th die-cushion pin 102.sub.n is ON/OFF controlled. That is, the second solenoid valve VTn is turned ON, and the pressure of the rise-side pressurizing chamber 210a of the hydraulic cylinder 210.sub.n is depressurized. As a result, the oil film thickness of the rise-side pressurizing chamber 210a of the hydraulic cylinder 210.sub.n becomes 0. After the depressurization, the second solenoid valve VTn is turned OFF, and an OFF delay timer is counted (Step S106). The OFF delay timer is used for reliable depressurization by the second solenoid valve VTn.

[0194] Subsequently, in order that the subsequent die-cushion pin in the order is to be made an adjustment target, the parameter n indicating the position number of the die-cushion pin is incremented by only 1 (Step S108), and the routine proceeds to Step S102.

[0195] On the other hand, at Step S102, if it is determined that the n-th die-cushion pin is a die-cushion pin to be used (in the case of “Yes”), the routine proceeds to Step S 1 10. The hydraulic cylinder 210.sub.n faced with the n-th die-cushion pin 102.sub.n in this case is the hydraulic cylinder 210 as an adjustment target.

[0196] At Step S110, a shim thickness set value MRn set correspondingly to the n-th die-cushion pin 102.sub.n is obtained from the shim thickness set value (see FIG. 18) of each of the die-cushion pins input from the shim thickness setting device 240 and calculates a pressure instruction PRn from the obtained shim thickness set value MRn. This pressure instruction PRn can be calculated by substituting the shim thickness set value MRn for the oil film thickness X in [Equation 1] described above.

[0197] Subsequently, the second solenoid valve VTn provided correspondingly to the hydraulic cylinder 210.sub.n and controlling the height direction position of the n-th die-cushion pin 102.sub.n is ON/OFF controlled (Step S112), the second solenoid valve VTn is turned OFF after depressurization of the hydraulic cylinder 210.sub.n, and the OFF delay timer is counted (Step S114). The OFF delay timer reliably turns OFF the second solenoid valve VTn and the routine proceeds to the subsequent processing (ON control of the first solenoid valve VPn which will be described later).

[0198] Subsequently, the first solenoid valve VPn provided correspondingly to the hydraulic cylinder 210.sub.n as an adjustment target depressurized at Steps S112 and S114 and whose oil film thickness is made 0 is turned ON (Step S116), and an ON delay timer is counted (Step S118). The ON delay timer is used for proceeding to the subsequent processing (pressure control) after the first solenoid valve VPn is reliably turned ON.

[0199] After the ON delay timer has elapsed, the pressure instruction PRn calculated at Step S110 is set to the pressure instructor 254 of the pressure control device 252 (Step S120).

[0200] The pressure control device 252 controls the hydraulic device 220 so that the pressure of the rise-side pressurizing chamber 210a of the hydraulic cylinder 210.sub.n as an adjustment target through the hydraulic device 220 based on the pressure instruction PRn set to the pressure instructor 254 becomes a pressure corresponding to the pressure instruction PRn (Steps S122 to S130), whereby the oil film thickness of the rise-side pressurizing chamber 210a of the hydraulic cylinder 210.sub.n as an adjustment target is adjusted.

[0201] That is, the pressure control device 252 calculates a torque instruction signal for controlling a torque of the servomotor 221 based on the pressure instruction PRn set to the pressure instructor 254 and the pressure signal input from the pressure detector 228 and outputs the calculated torque instruction signal to the servomotor 221 through the servo amplifier 229, and when the pressure detected by the pressure detector 228 reaches a pressure corresponding to the pressure instruction PRn (Step S126), the first solenoid valve VPn which was turned ON at Step S116 is turned OFF, and the pressure control (oil film thickness control) to the hydraulic cylinder 210.sub.n as an adjustment target is finished (Step S130).

[0202] When the pressure control to the hydraulic cylinder 210.sub.n as the adjustment target is finished, it is determined whether or not the parameter n has reached N (=55) (that is, whether or not the pressure control (including depressurization control) to all the 55 die-cushion pins has been finished) (Step S132), and in the case of n=N (in the case of “No”), the parameter n is incremented only by 1 at Step S108 and then, the routine proceeds to Step S102.

[0203] On the other hand, if it is determined to be n=N at Step S132 (in the case of “Yes”), it means that the pressure control (oil film thickness control) to all the die-cushion pins has been finished, and the m-th oil film thickness control is finished.

[0204] Returning to FIG. 19, when the m-th oil film thickness control is finished, the user operates the press machine 10 and performs the m-th forming trial (in the case of m=1, the first forming trial) (Step S16).

[0205] The user tests the formed product which was press-formed in the m-th forming trial (Step S18). The test of the formed product is a test which examines occurrence and a degree of a crack at what spot in the formed product or occurrence and a degree of a drawing wrinkle at what spot in the formed product and the like.

[0206] The user determines whether or not the formed product press-formed in the forming trial is a formed product having a desired quality by a forming result (test result) of the formed product (Step S20) and if it is determined that the formed product is not a formed product having a desired quality (fails the test) (in the case of “No”), m is incremented only by 1 (Step S22), and the routine returns to Step S12 and the “m-th shim thickness setting” in which m is incremented and the like are performed by referring to the forming result of the formed product.

[0207] As described above, the shim adjustment and the forming trial are repeatedly executed until the formed product having a desired quality is press-formed.

[0208] According to the present invention, the conventional manual shim adjustment (manual work) which took approximately 5 minutes of shim adjustment work time at one spot in one session can be reduced to approximately 30 seconds, whereby a series of the shim adjustment works which required a half day in total can be completed in approximately 30 minutes or reduction of the shim adjustment work time can be utilized for checking of formability or fine adjustment (an increase of the number of adjustment times), whereby product accuracy can be improved.

[0209] Moreover, regarding the shim thickness, the conventional stepped adjustment type using a plank (fragment) (if a 0.2-mm plank is not sufficient, a 0.4-mm plank is used or the like, for example) becomes the non-stage type in the shim adjusting device 200, whereby adjustment accuracy is improved.

[0210] Moreover, since the device is simple (the hydraulic device 220 is simple and only one unit of the pressure detector 228 is used), the shim adjusting device 200 can be constituted inexpensively.

[0211] Furthermore, in the conventional manual shim adjustment (by a manual work), it is difficult to check the set shim thickness. Even if a shim falls off, for example, it can be found only after a check with a lot of labors. Such a situation can often occur that an operator assumes that the shim is attached and tries to evaluate the subsequent result, but actually, the shim is not located at a predetermined position. According to the shim adjusting device 200, such a problem does not occur.

Second Embodiment of Shim Adjusting Device of Die-Cushion Device

[0212] FIG. 21 is a block diagram of an essential part illustrating a second embodiment of a shim adjusting device of a die-cushion device according to the present invention. The same reference numerals are given to portions in common with the shim adjusting device 200 in the first embodiment illustrated in FIG. 3, and its detailed description will be omitted.

[0213] In a shim adjusting device 200′ of the second embodiment illustrated in FIG. 21, a plurality of (55) hydraulic cylinders 210′ (210.sub.1′, 210.sub.2′, . . . 210.sub.N=55′) functioning as shim thickness generating devices is different from the hydraulic cylinders 210 used in the first embodiment, and an oil film thickness control device 250′ is different.

[0214] As illustrated in FIG. 22, the hydraulic cylinder 210′ used in the shim adjusting device 200′ of the second embodiment is different from the hydraulic cylinder 210 used in the shim adjusting device 200 of the first embodiment illustrated in FIG. 4 in a point that a position detector 211 which detects a height direction position of a piston rod 212′ is incorporated.

[0215] The position detector 211 of this embodiment is a magnetostriction type displacement sensor which detects relative displacement between the piston rod 212′ and the cylinder body of the hydraulic cylinder 210′ and includes a sensor body 211a having a sensor rod portion and a ring-shaped magnet 211b.

[0216] The sensor body 211a is disposed on a bottom part of the hydraulic cylinder body and a rod portion is inserted into the hydraulic cylinder body. A seal member (O-ring) 213 is disposed between the hydraulic cylinder body and the rod portion so that the operating oil of the hydraulic cylinder 210′ does not leak.

[0217] The magnet 211b is arranged in a hollow part formed on a lower part of the piston rod 212′ in a state where the rod portion is inserted.

[0218] The position detector 211 which is a magnetostriction type displacement sensor is to detect a position of the piston rod 212′ of the hydraulic cylinder 210′ and sends out an excitation pulse to a magnetostriction line of the rod portion from the sensor body 211a and calculates a distance between the sensor body 211a and the magnet 211b based on time until a distortion pulse generated by action of an external magnetic field of the magnet 211b on the excitation pulse returns. That is, the position detector 211 detects the oil film thickness X of the rise-side pressurizing chamber of the hydraulic cylinder 210′.

[0219] Returning to FIG. 21, a position detection signal indicating the oil film thickness X of the rise-side pressurizing chamber of the hydraulic cylinder 210′ detected by the 55 position detectors 211 (211.sub.1′, 211.sub.2′, . . . 211.sub.N′) disposed on the 55 hydraulic cylinders 210′ (210.sub.1′, 210.sub.2′, . . . 210.sub.N′) is added to the position control device 251 (position signal selector 257) of the oil film thickness control device 250′.

[0220] The oil film thickness control device 250 of the first embodiment controls the oil film thickness (shim thickness) of the rise-side pressurizing chamber 210a by controlling the pressure of the rise-side pressurizing chamber 210a of each of the hydraulic cylinders 210, while the oil film thickness control device 250′ of the second embodiment controls the oil film thickness (shim thickness) of the rise-side pressurizing chamber by controlling the cylinder position (piston rod position) of each of the hydraulic cylinders 210′, which is different from the oil film thickness control device 250 of the first embodiment.

[0221] Therefore, the oil film thickness control device 250′ of the second embodiment includes the position control device 251.

[0222] The position control device 251 includes a position instructor 253, a position control calculator 255, and a position signal selector 257.

[0223] In the position instructor 253, the shim thickness set value corresponding to the die-cushion pin as an adjustment target in the shim thickness set value of each of the die-cushion pins input from the shim thickness setting device 240 is set as a position instruction, and the position instructor 253 outputs the set position instruction to the position control calculator 255.

[0224] To the other inputs of the position control calculator 255, a position detection signal selected by the position signal selector 257 and an angular velocity signal indicating an angular velocity of the drive shaft of the servomotor 221 detected by the encoder 223 are added.

[0225] The position signal selector 257 selects a position detection signal input from the position detector 211 disposed on the hydraulic cylinder 210′ faced with the die-cushion pin as an adjustment target in the position detection signals input from the 55 position detectors 211 and outputs the selected position detection signal to the position control calculator 255.

[0226] The position control calculator 255 calculates a torque instruction signal for controlling the torque of the servomotor 221 based on the position instruction input from the position instructor 253 and the position detection signal input from the position signal selector 257. By outputting this calculated torque instruction signal to the servomotor 221 through the servo amplifier 229 so as to control the operating oil ejected from the hydraulic pump 222 driven by the servomotor 221, position control is executed so that the position of the piston rod 212′ of the hydraulic cylinder 210′ as an adjustment target comes to a position corresponding to the position instruction. The angular velocity signal input from the encoder 223 is used for compensation for stable control of the operating oil.

[0227] Since the shim adjusting device 200′ of the second embodiment performs the shim adjustment by individually controlling the positions of the plurality of (55) hydraulic cylinders 210′ one by one as described above, the pressure detector is not needed, but the position detector 211 needs to be provided at each of the hydraulic cylinders 210′.

[0228] Moreover, the shim adjusting device 200′ of the second embodiment is of a position control type in which the shim thickness (oil film thickness) as an adjustment target is directly controlled and has control accuracy of the oil film thickness improved as compared with the shim adjusting device 200 of the first embodiment of the pressure control type.

[0229] On the other hand, a large number of the position detectors are needed, which increases the number of signal lines (they need to be made movable) and also increases the number of channels input into the position control device 251 and thus, the device is made complicated and a cost is raised.

Others

[0230] In this embodiment, the case where the 55 hydraulic cylinders are provided on the cushion pad is described, but the number of the hydraulic cylinders is not limited to this embodiment.

[0231] Moreover, in this embodiment, the case where oil is used as the operating fluid of the shim adjusting device is described, but this is not limiting, and water or other fluids may be used.

[0232] Furthermore, the present invention is not limited to constitution of the die-cushion device but can be applied to the shim adjusting device of any type of the die-cushion devices.

[0233] Moreover, it is needless to say that the present invention is not limited to the aforementioned embodiments but is capable of various improvements and variations within a range not departing from the gist of the present invention.