PRESS-MOLDING DEVICE

Abstract

A press-molding device works on a workpiece and includes a punch, a die provided with a hollow portion into which the punch is inserted, a material presser disposed on an outer periphery of the punch and facing the die, a pad disposed in a hollow portion of the die, a pressing unit configured to press the pad toward the punch, and a load sensor disposed between the pad and the pressing unit.

Claims

1. A press-molding device that works on a workpiece, the press-molding device comprising: a punch; a die provided with a hollow portion into which the punch is inserted; a material presser disposed on an outer periphery of the punch and facing the die; a pad disposed in a hollow portion of the die; a pressing unit configured to press the pad toward the punch; and a load sensor disposed between the pad and the pressing unit.

2. The press-molding device according to claim 1, further comprising a position sensor configured to acquire information for detecting a position of the punch.

3. The press-molding device according to claim 1, further comprising: a driver configured to drive the punch, and a control unit configured to control the driver, the pressing unit, and the load sensor.

4. The press-molding device according to claim 3, wherein the control unit calculates a molding load for molding the workpiece based on a load detected by the load sensor and a reaction force of the punch, and controls the driver based on the molding load.

5. The press-molding device according to claim 1, further comprising: a die plate configured to hold the die, and a gap sensor configured to detect an amount of a gap between the material presser and the die plate.

6. The press-molding device according to claim 1, wherein the pressing unit includes a cylinder having a piston movable in a moving direction of the punch.

7. The press-molding device according to claim 6, wherein the cylinder is an air cylinder, and the press-molding device further includes a regulator configured to control an internal pressure of the air cylinder to a constant pressure.

8. The press-molding device according to claim 1, wherein a height of the pad is larger than a depth of the hollow portion of the die.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a schematic diagram illustrating an example of a press-molding working device according to a first exemplary embodiment of the present disclosure.

[0018] FIG. 2 is an overview illustrating a process of performing molding work on a workpiece with a press-molding device.

[0019] FIG. 3 is a flowchart illustrating an example of processing of the press-molding device according to the first exemplary embodiment of the present disclosure.

[0020] FIG. 4 is a graph illustrating an example of a relationship between a load applied to a load sensor and a position of a punch in a case where a workpiece is mold-processed by the press-molding device.

BACKGROUND TO PRESENT DISCLOSURE

[0021] Press working is generally used in a wide variety of fields such as home appliances, precision machines, and automobile parts. For example, in punching, bending, drawing, and the like in which press working is performed on a plate-shaped workpiece, a workpiece loaded on a die is pressed by a material presser, and a part of the workpiece is pushed into a hollow portion of the die by a punch to be punched or molded. Thus, the workpiece is worked into a predetermined shape.

[0022] In a press-molding device that performs press working, there is known a device that controls a working state while monitoring a load (working resistance) during the work applied to a tool by a load sensor attached to a die tool such as a punch.

[0023] The present inventors have newly found that there is a problem that a load applied to a workpiece cannot be accurately detected when a load sensor is attached to a punch. For example, in a case where pressure of a material presser or the like cannot be sufficiently secured, sliding resistance between the material presser and the punch may increase due to external influences or the like in which a force of the material presser is applied in a direction of a side surface of the punch. When the load sensor is attached to the punch, a working reaction force (working resistance) transmitted to the load sensor via the punch increases due to an increase in sliding resistance. Therefore, the load detected by the load sensor is measured at a value larger than a molding load for actually molding the workpiece.

[0024] The present inventors have studied a press-molding device capable of stably performing load sensing on a workpiece so that a load applied to the workpiece can be accurately detected in press-molding working, and have reached the present disclosure.

[0025] One exemplary embodiment of the present disclosure will now be described with reference to the accompanying drawings. Note that, description below is merely exemplary in nature, and is not intended to limit the present disclosure, its application, or its use. Furthermore, the drawings are schematic representations, and the ratios between dimensions or the like do not necessarily match the actual dimensions.

FIRST EXEMPLARY EMBODIMENT

[Overall Configuration]

[0026] FIG. 1 is a schematic diagram illustrating press-molding device 100 according to a first exemplary embodiment of the present disclosure. The X-Y-Z coordinate system illustrated in the drawings is provided to facilitate the understanding of the exemplary embodiment, and is not intended to limit the scope of the exemplary embodiment in any way. In the drawing, an X direction is a width direction of press-molding device 100, a Y direction is a depth direction of press-molding device 100, and a Z direction is a height direction of press-molding device 100.

[0027] With reference to FIG. 1, press-molding device 100 according to the present exemplary embodiment will be described.

[0028] As illustrated in FIG. 1, press-molding device 100 is a device that performs press-molding work on workpiece 5, and the device is, for example, a servo screw press machine that can be controlled with high accuracy. Workpiece 5 is a plate-shaped metal plate, for example.

[0029] Press-molding device 100 includes press device body 26 and control unit 20. In the present exemplary embodiment, press-molding device 100 includes electromagnetic valve 9, pressure gauge 10, and regulator 11.

[0030] Press device body 26, control unit 20, electromagnetic valve 9, pressure gauge 10, and regulator 11 may be accommodated in one housing. For example, control unit 20 may be accommodated in a housing of press device body 26. Alternatively, press device body 26, control unit 20, electromagnetic valve 9, pressure gauge 10, and regulator 11 may be separately provided at distant places instead of being accommodated in one housing. In the present disclosure, an aspect including press device body 26, control unit 20, electromagnetic valve 9, pressure gauge 10, and regulator 11 separately provided as described above may also be referred to as press-molding device 100. Such an aspect may be referred to as a press-molding work system.

<Press Device Body>

[0031] The press device body 26 includes an upper mold 30 and a lower mold 31. In lower mold 31, pad 6, load sensor 12, position sensor 13, gap sensor 14, and pressing unit 33 are disposed. Press device body 26 includes slide 21 to which upper mold 30 is attached, bolster 22 to which lower mold 31 is attached, and driver 32 that moves upper mold 30 in a vertical direction (Z direction).

[0032] Upper mold 30 includes punch 1 and material presser 3. Upper mold 30 includes a punch holder that holds punch 1 and material presser 3 and is attached to slide 21.

[0033] Punch 1 is a tool for press-molding workpiece 5 by moving in a pressing direction (Z direction). Punch 1 is attached to slide 21 together with material presser 3.

[0034] A tip of punch 1 has, for example, a spherical shape. In the present exemplary embodiment, the tip of punch 1 has a spherical shape having a diameter of 6.0 mm, and punch 1 press-molds workpiece 5 into a spherical shape.

[0035] Punch 1 includes, for example, a cemented carbide material. An example of the cemented carbide material is a generic term of a metal (alloy) in which at least one of carbides of tungsten (W), chromium (Cr), molybdenum (Mo), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), and tantalum (Ta) is bonded with an Fe-group metal (Fe, Co, or Ni). As the cemented carbide material, for example, an alloy corresponding to VM-40 of the cemented carbide tool standard (CIS) can be adopted.

[0036] Material presser 3 is disposed on an outer periphery of punch 1. Material presser 3 has a pressing surface that comes into contact with workpiece 5. Material presser 3 has a plate shape, and is provided with a through hole through which punch 1 can move. The through hole is provided at a center of material presser 3. Material presser 3 faces die 2 of lower mold 31 described later.

[0037] Punch 1 and material presser 3 are attached to slide 21 via the punch holder, for example. Slide 21 is a component movable along shaft 25 extending in the vertical direction (Z direction). Slide 21 is connected to driver 32. Slide 21 is moved in the vertical direction along shaft 25 by driver 32. As a result, punch 1 attached to slide 21 moves up and down together with material presser 3.

[0038] Lower mold 31 includes die 2 and die plate 4. Lower mold 31 includes a die holder that holds die 2 and die plate 4 and attaches die 2 and die plate 4 to bolster 22.

[0039] Die 2 is provided with hollow portion 2a into which punch 1 is inserted, and is a component on which workpiece 5 is placed. Hollow portion 2a is a through hole penetrating die 2 in the vertical direction (Z direction). In the present exemplary embodiment, hollow portion 2a is formed by a circular through hole. When viewed from upper mold 30, a vicinity of an inlet of hollow portion 2a of die 2 has an R shape.

[0040] Similarly to punch 1, die 2 includes, for example, a cemented carbide material.

[0041] Die plate 4 is a member that holds die 2. Die plate 4 may be configured separately from die 2, or may be configured integrally with die 2.

[0042] Die 2 and die plate 4 are attached to bolster 22 via, for example, a die holder. Bolster 22 is a table for attaching lower mold 31. Die 2 and die plate 4 are attached and fixed to bolster 22.

[0043] Pad 6 is disposed in hollow portion 2a of die 2. Pad 6 is disposed so as to be movable in the vertical direction (Z direction) in hollow portion 2a of die 2. Pad 6 is configured by, for example, a quenching member such as SKD11, SKH51, or powdered high-speed steel.

[0044] Pad 6 has, for example, a cylindrical columnar shape. An upper surface of pad 6 is in contact with workpiece 5. A lower surface of pad 6 is in contact with load sensor 12.

[0045] The height of pad 6 is larger than the depth of hollow portion 2a of die 2. In the present exemplary embodiment, the die holder is provided with a hollow portion which is a through hole communicating with hollow portion 2a of die 2. Therefore, pad 6 is disposed in hollow portion 2a of die 2 and the hollow portion of the die holder.

[0046] Load sensor 12 detects a force when punch 1 pushes pad 6 downward via workpiece 5. That is, load sensor 12 detects a load applied in the pressing direction (Z direction) of punch 1.

[0047] Load sensor 12 is disposed between pad 6 and pressing unit 33. An upper surface of load sensor 12 is in contact with pad 6, and a lower surface of load sensor 12 is in contact with pressing unit 33. Information detected by load sensor 12 is transmitted to control unit 20.

[0048] Position sensor 13 acquires information for detecting the position of punch 1. For example, position sensor 13 can be configured by, for example, a displacement sensor that measures a minute distance interval from a measurement object in a non-contact manner.

[0049] Position sensor 13 can be attached to any position where information for detecting the position of punch 1 can be acquired. In the present exemplary embodiment, position sensor 13 is attached to lower mold 31 and detects a distance between position sensor 13 and upper mold 30. The position of punch 1 can be detected on the basis of the distance between upper mold 30 and position sensor 13.

[0050] Press device body 26 may be provided with a plurality of position sensors 13. For example, four position sensors 13 may be disposed near the four corners of an upper surface of lower mold 31. It is possible to detect whether upper mold 30 and lower mold 31 are arranged in parallel on the basis of information detected by four position sensors 13.

[0051] Gap sensor 14 detects an amount of a gap between die plate 4 and material presser 3. For example, the gap sensor 14 can be configured by a displacement sensor. Information detected by gap sensor 14 is transmitted to control unit 20.

[0052] Gap sensor 14 can be attached to any place where the amount of the gap between die plate 4 and material presser 3 can be measured. In the present exemplary embodiment, press device body 26 includes four gap sensors 14, and four gap sensors 14 are attached to the four corners of an upper surface of die plate 4. In this case, the inclination or the like of material presser 3 to die plate 4 can be detected on the basis of the information of the gap amount detected by four gap sensors 14.

[0053] Pressing unit 33 presses pad 6 toward punch 1. Pressing unit 33 presses pad 6 toward punch 1 together with load sensor 12. That is, pressing unit 33 applies an upward pressing force to load sensor 12 and pad 6. Pressing unit 33 applies a constant pressing force to load sensor 12 and pad 6.

[0054] In the present exemplary embodiment, pressing unit 33 is configured by cylinder 8 having piston 7. Piston 7 is movable in a moving direction (Z direction) of punch 1, and is disposed, for example, in the hollow portion of the die holder. An upper surface of piston 7 is in contact with the lower surface of load sensor 12.

[0055] Cylinder 8 is an air cylinder that pushes up piston 7 toward punch 1 by air pressure. As a result, piston 7 presses load sensor 12 and pad 6 toward punch 1. For example, cylinder 8 may be a low sliding resistance type cylinder that suppresses sliding resistance when piston 7 moves up and down.

[0056] Pad 6, load sensor 12, and piston 7 may be integrated with a fixing bolt or the like.

[0057] Cylinder 8 of pressing unit 33 is controlled by electromagnetic valve 9, pressure gauge 10, and regulator 11. Specifically, an internal pressure (air pressure) of cylinder 8 is controlled by electromagnetic valve 9, pressure gauge 10, and regulator 11.

[0058] Electromagnetic valve 9 controls supply and/or exhaust of air from regulator 11 to cylinder 8.

[0059] Pressure gauge 10 detects the internal pressure (air pressure) of cylinder 8.

[0060] Regulator 11 adjusts the pressure of air supplied to cylinder 8 via electromagnetic valve 9. Regulator 11 may be a precision regulator or the like.

[0061] Electromagnetic valve 9, pressure gauge 10, and regulator 11 are controlled by control unit 20.

[0062] Driver 32 is a component that drives slide 21 in the vertical direction. In the present exemplary embodiment, driver 32 includes servomotor 23 and ball screw 24 driven by servomotor 23.

[0063] Servomotor 23 is controlled by control unit 20. Ball screw 24 is connected to slide 21 and is rotationally driven by servomotor 23. As a result, slide 21 is moved in the vertical direction.

[0064] Driver 32 is controlled by control unit 20.

[0065] Note that workpiece 5 according to the present exemplary embodiment is a plate-shaped material to be worked by press-molding device 100. Workpieces 5 are conveyed in the X direction or the Y direction by a conveyor (not illustrated) in accordance with a pressing operation of press device body 26, and is sequentially subjected to press working.

[0066] In the present exemplary embodiment, workpiece 5 includes SUS301-EH material which is a steel type classified as austenitic stainless steel. The SUS301-EH material is, for example, a material used as a mainspring or a spring of an automobile component. In the present exemplary embodiment, the thickness of workpiece 5 is 0.03 mm, the hardness is 529 HV, and the tensile strength is 1,679 N/mm.sup.2.

[0067] In the present exemplary embodiment, the tip of punch 1 has a spherical shape as described above, but punch 1 may have a V-shaped or U-shaped bent shape or a cylindrical or box-shaped drawn shape. The shape of material presser 3 and the shape of die 2 are also planar shapes facing each other, but the shapes are not limited.

[0068] In the present exemplary embodiment, an example in which driver 32 is configured by servomotor 23 and ball screw 24 has been described, but the present disclosure is not limited to this example. Driver 32 only needs to have a configuration capable of driving upper mold 30.

<Control Unit>

[0069] Control unit 20 controls press device body 26. Specifically, control unit 20 controls load sensor 12, position sensor 13, gap sensor 14, driver 32, and pressing unit 33.

[0070] Control unit 20 includes a processor and a storage. Control unit 20 implements a predetermined function by the processor executing a command stored in a storage device. The functions of control unit 20 may be implemented only by hardware, or may be implemented by a combination of the hardware and software. Control unit 20 may include one or more processors.

[0071] The processor can include, for example, a microcomputer, a CPU, an MPU, a GPU, a DSU, an FPGA, an ASIC, and the like. The processor may be configured by a dedicated electronic circuit designed to implement a predetermined function.

[0072] The storage is a storage medium that stores a program and data for implementing the function of control unit 20. The storage can be implemented by a hard disk (HDD), an SSD, a RAM, a DRAM, a ferroelectric memory, a flash memory, a magnetic disk, or a combination of the above, for example.

[0073] In the present exemplary embodiment, control unit 20 includes press controller 15, sensor controller 16, pressure controller 17, calculator 18, and determiner 19. These constituent elements are implemented by the processor and the storage described above.

[0074] Press controller 15 controls driver 32. Specifically, press controller 15 is electrically connected to servomotor 23, and drives servomotor 23 by transmitting a drive signal. When servomotor 23 is driven, ball screw 24 rotates, and slide 21 connected to ball screw 24 can be vertically driven at a predetermined speed in the pressing direction (Z direction).

[0075] Sensor controller 16 controls load sensor 12, position sensor 13, and gap sensor 14. Specifically, sensor controller 16 is electrically connected to load sensor 12, position sensor 13, and gap sensor 14, and outputs information detected by each of load sensor 12, position sensor 13, and gap sensor 14 to calculator 18.

[0076] Pressure controller 17 controls the internal pressure (air pressure) of cylinder 8 of pressing unit 33. Specifically, pressure controller 17 is electrically connected to electromagnetic valve 9, pressure gauge 10, and regulator 11. Pressure controller 17 controls opening and closing of electromagnetic valve 9 and controls supply of air from regulator 11 to cylinder 8. Pressure controller 17 controls regulator 11 on the basis of the internal pressure of cylinder 8 detected by pressure gauge 10. Specifically, pressure controller 17 controls regulator 11 so that the internal pressure of cylinder 8 is maintained constant at an arbitrary pressure on the basis of a pressure value detected by pressure gauge 10.

[0077] Pressure controller 17 opens and closes electromagnetic valve 9 on the basis of the pressure value detected by pressure gauge 10. For example, pressure controller 17 may close electromagnetic valve 9 in an abnormal state in which the pressure value detected by pressure gauge 10 exceeds a predetermined threshold value.

[0078] Calculator 18 calculates a molding load of workpiece 5 on the basis of the information detected by load sensor 12 and position sensor 13.

[0079] Calculator 18 calculates the position of punch 1 on the basis of the information detected by position sensor 13. Calculator 18 calculates the position of punch 1 from a bottom dead center on the basis of the information detected by position sensor 13. In other words, calculator 18 calculates how much punch 1 is positioned above the bottom dead center. The bottom dead center of punch 1 is the lowest position that punch 1 can take.

[0080] For example, in a case where upper mold 30 descends and position sensor 13 and upper mold 30 come into contact with each other, a detection value detected by position sensor 13 is 0. Calculator 18 can detect that punch 1 is at the bottom dead center in a case where the detection value of position sensor 13 is less than or equal to 0. Calculator 18 can detect that punch 1 is positioned higher above the bottom dead center as the detection value is larger, and punch 1 is closer to the bottom dead center as the detection value is smaller.

[0081] Calculator 18 can determine a detection timing of a load by load sensor 12 on the basis of the information detected by position sensor 13, that is, the information of the position of punch 1. Specifically, a detection start timing of load sensor 12 can be determined on the basis of the information detected by position sensor 13 so that the detection of the load applied to punch 1 in the pressing direction (Z direction) can be started at the same timing for each shot in the press-molding work. In this manner, the information detected by position sensor 13 can be used as a trigger for detecting a load applied in the pressing direction (Z direction) of punch 1.

[0082] In a case where four position sensors 13 are arranged at the four corners of the upper surface of lower mold 31, calculator 18 can detect whether upper mold 30 and lower mold 31 are arranged in parallel on the basis of the detection values of four position sensors 13.

[0083] Calculator 18 generates a load waveform indicating a relationship between the load detected by load sensor 12 and the position of punch 1, and calculates the molding load of workpiece 5 on the basis of the generated load waveform. For example, calculator 18 calculates the molding load of workpiece 5 on the basis of the load obtained by load sensor 12 and a reaction force of punch 1.

[0084] Calculator 18 detects a gap between material presser 3 and die plate 4 and an inclination state of material presser 3 on the basis of the information detected by gap sensor 14. For example, calculator 18 detects an abnormal state such as inclination of the pressing surface of material presser 3 with respect to the upper surface of die plate 4 on the basis of the information detected by four gap sensors 14 arranged at the four corners of the upper surface of die plate 4.

[0085] Determiner 19 determines a pushing amount of punch 1 on the basis of the molding load of workpiece 5 calculated by calculator 18. For example, when the molding load of workpiece 5 is small, the pushing amount of punch 1 is insufficient, and thus determiner 19 outputs a signal for increasing the pushing amount of punch 1 to press controller 15. Press controller 15 having received the signal increases the pushing amount of punch 1 from servomotor 23 via ball screw 24. On the other hand, when the molding load of workpiece 5 is large, the pushing amount of punch 1 is excessive, and thus determiner 19 outputs a signal for decreasing the pushing amount of punch 1 to press controller 15. Press controller 15 having received the signal decreases the pushing amount of punch 1 from servomotor 23 via ball screw 24.

[Operation]

[0086] One example of an operation of press-molding device 100 will be described with reference to FIG. 2.

[0087] FIG. 2 is a schematic diagram illustrating an example of a process of molding workpiece 5 by press-molding device 100 according to the first exemplary embodiment of the present disclosure. In FIG. 2, some constituent elements are not illustrated. Note that the reference sign DH in FIG. 2 indicates a die height, and the reference sign H indicates the pushing amount of punch 1.

[0088] As illustrated in processes A0 to A3 in FIG. 2, punch 1 is attached to slide 21 together with material presser 3 that presses workpiece 5 against die 2 during the press-molding work. With the movement of slide 21, punch 1 is pressed against workpiece 5, and the press-molding work is executed.

[0089] Pad 6 is disposed in hollow portion 2a of die 2 facing punch 1, and the press-molding is performed while performing positioning so that workpiece 5 is not displaced by cylinder 8 including piston 7 movable up and down via pad 6 and load sensor 12 provided between pad 6 and piston 7 along the movement in which punch 1 is pressed against workpiece 5 and descends in the pressing direction (Z direction).

[0090] Next, processes A0 to A3 illustrated in FIG. 2 will be described in detail.

[0091] Process A0 is a state in which punch 1 is located at a top dead center (before work). The top dead center is the highest position that punch 1 can take. Workpiece 5 is placed on die 2 with punch 1 positioned at the top dead center. When the press-molding work is started, upper mold 30 including punch 1 descends from the top dead center in the pressing direction (Z direction) together with slide 21.

[0092] In process A1, upper mold 30 has descended and material presser 3 is in contact with workpiece 5. When material presser 3 comes into contact with workpiece 5, the tip of punch 1 comes into contact with workpiece 5.

[0093] In process A2, punch 1 has descended in a state where material presser 3 is in contact with workpiece 5. Punch 1 sandwiches workpiece 5 with pad 6 positioned on the lower surface of workpiece 5. As a result, punch 1, workpiece 5, and pad 6 descend together. At this time, material presser 3 maintains a state of pressing workpiece 5, and performs a function of preventing workpiece 5 from being drawn into hollow portion 2a of die 2 by the load of a spring disposed in upper mold 30.

[0094] In process A3, punch 1 further has descended and reached the bottom dead center. The operations of punch 1, pad 6, and material presser 3 are similar to those in process A2.

[Determination Processing of Press-Molding Work]

[0095] An example of determination processing of press-molding work by press-molding device 100 will be described with reference to FIG. 3.

[0096] FIG. 3 is a flowchart illustrating an example of processing of the press-molding device according to the first exemplary embodiment of the present disclosure.

[0097] As illustrated in FIG. 3, in step S1, press-molding device 100 starts molding. When press-molding device 100 starts molding, as illustrated in FIG. 2, upper mold 30 including punch 1 descends together with slide 21 in the pressing direction (Z direction) from the top dead center (process A0), and material presser 3 comes into contact with workpiece 5. When material presser 3 comes into contact with workpiece 5, upper mold 30 (including the punch 1) fixed to slide 21 gradually starts to descend, and the tip of punch 1 comes into contact with workpiece 5 (process A1). Thereafter, while punch 1 sandwiches workpiece 5 with pad 6 on the lower surface of workpiece 5, punch 1, workpiece 5, and pad 6 start to descend. Punch 1 is pushed halfway (process A2). Furthermore, descending of upper mold 30 (including punch 1) fixed to slide 21 progresses, and punch 1 reaches the bottom dead center (process A3).

[0098] In step S2, press-molding device 100 detects the load and the position of punch 1. Press-molding device 100 detects the position of punch 1 on the basis of the information detected by position sensor 13. For example, press-molding device 100 detects the position of punch 1 indicated in processes A0 to A3 in FIG. 2 on the basis of the detection value of position sensor 13. Press-molding device 100 detects a load applied in the pressing direction (Z direction) of punch 1 by load sensor 12.

[0099] The load is detected by load sensor 12 in association with the detection of the position of punch 1 by position sensor 13. For example, press-molding device 100 detects a position (process A1 in FIG. 2) at which punch 1 starts to contact workpiece 5 and a position (process A3 in FIG. 2) at which punch 1 reaches the bottom dead center by position sensor 13. Press-molding device 100 starts detection by load sensor 12 when punch 1 reaches a position at which punch 1 starts to contact workpiece 5, and ends the detection by load sensor 12 when punch 1 reaches the bottom dead center. As a result, load sensor 12 detects a positional relationship of punch 1 and the load applied to punch 1. That is, load sensor 12 detects the positional relationship of punch 1 and the force when punch 1 presses pad 6 and piston 7 via workpiece 5.

[0100] In step S3, press-molding device 100 detects the amount of the gap between material presser 3 and die plate 4. For example, press-molding device 100 detects the amount of the gap between the pressing surface (lower surface) of material presser 3 and the upper surface of die plate 4 by four gap sensors 14 arranged at the four corners of the upper surface of die plate 4. Press-molding device 100 detects the amount of the gap by gap sensor 14 until punch 1 descends from the top dead center in the pressing direction (Z direction) and material presser 3 comes into contact with workpiece 5.

[0101] In step S4, press-molding device 100 detects the pressing force of pressing unit 33. In the present exemplary embodiment, pressing unit 33 is constituted by cylinder 8 having piston 7, and cylinder 8 is an air cylinder. Therefore, press-molding device 100 detects the internal pressure of cylinder 8 by pressure gauge 10.

[0102] In step S5, press-molding device 100 determines whether there is an abnormality. For example, press-molding device 100 determines whether the amount of the gap between material presser 3 and die plate 4 detected by gap sensor 14 in step S3 is an abnormal value. For example, the abnormal value is determined by calculating a difference between the amounts of the gap detected by four gap sensors 14 and determining whether or not the difference exceeds a predetermined threshold value. For example, in a case where the difference in amount of the gap is more than or equal to 5 m, press-molding device 100 determines that the difference is an abnormal value. The abnormal value or the threshold value may be changed depending on the size of the mold, the size of die plate 4, or the arrangement place of gap sensor 14.

[0103] Press-molding device 100 determines whether the internal pressure of cylinder 8 detected by pressure gauge 10 in step S4 is an abnormal value. For example, the abnormal value is determined on the basis of whether the pressure detected by pressure gauge 10 exceeds a predetermined threshold value. For example, in a case where the pressure value detected by pressure gauge 10 is not within a range of 0.450.02 MPa, press-molding device 100 determines the value as an abnormal value. The abnormal value or the threshold value may be changed depending on the molding load of workpiece 5.

[0104] In step S5, in a case where it is determined that the detection value detected in step S3 or S4 is an abnormal value, the processing ends even during molding. In a case where it is determined in step S3 or S4 that the detection value is not an abnormal value, the processing proceeds to step S6.

[0105] In step S6, press-molding device 100 determines whether molding has ended. For example, press-molding device 100 determines whether punch 1 has reached the bottom dead center on the basis of the information detected by position sensor 13. In a case where it is determined that punch 1 has reached the bottom dead center, the processing proceeds to step S7. In a case where it is determined that punch 1 has not reached the bottom dead center, the processing returns to step S2.

[0106] In step S7, press-molding device 100 calculates the molding load of workpiece 5. For example, calculator 18 of control unit 20 generates a load waveform indicating the relationship between the load detected by load sensor 12 and the position of punch 1, and calculates the molding load of workpiece 5 on the basis of the generated load waveform.

[0107] Here, the calculation of the molding load of workpiece 5 will be described with reference to FIG. 4.

[0108] FIG. 4 is a graph illustrating an example of the relationship between the load applied to load sensor 12 and the position of punch 1 in a case where workpiece 5 is subjected to molding work by press-molding device 100. Processes A1 to A3 illustrated in FIG. 4 correspond to processes A1 to A3 illustrated in FIG. 2, and the reference sign H illustrated in FIG. 4 corresponds to pushing amount H illustrated in FIG. 2. FIG. 4 illustrates a load waveform indicating a load detected by load sensor 12 from process A1 in which punch 1 comes into contact with workpiece 5 to process A3 in which punch 1 reaches the bottom dead center.

[0109] The left end of the graph illustrated in FIG. 4 shows the load when the tip of punch 1 starts to contact workpiece 5 as shown in process A1 in FIG. 2. When the tip of punch 1 starts to contact workpiece 5, a relationship of the force among punch 1, workpiece 5, and pad 6 is balanced between punch 1 and pad 6.

[0110] That is, in process A1 at the left end of the graph illustrated in FIG. 4, the following relational expression (1) holds.

[00001]$\begin{array}{cc}\left(\mathrm{Equation}1\right)& \\ \mathrm{Force}\mathrm{on}\mathrm{punch}1\left(\mathrm{force}\mathrm{for}\mathrm{descending}\mathrm{pad}6\right)=\mathrm{force}\mathrm{on}\mathrm{pad}6\left(\mathrm{reaction}\mathrm{force}\mathrm{for}\mathrm{descending}\mathrm{pad}6\right)& \left(1\right)\end{array}$

[0111] This is because a reaction force against the force from punch 1 is generated in pad 6 since the pressure in cylinder 8 is controlled to be constant.

[0112] From a state in which the force on punch 1 and the force on pad 6 are balanced, punch 1 is further descended and pushed into hollow portion 2a of die 2 as illustrated in process A2 in FIG. 2, and thus, a force is further applied to punch 1. Specifically, a force a that overcomes the force of pad 6 and descends punch 1 in the pressing direction (Z direction) and a molding load for performing molding work on workpiece 5 are applied to punch 1. Therefore, the force on punch 1 becomes larger than the reaction force on pad 6 during a period from when punch 1 starts to contact workpiece 5 to when punch 1 reaches the bottom dead center.

[0113] That is, the following relational expression (2) holds for the force applied to load sensor 12 in process A2 in the graph illustrated in FIG. 4.

[00002]$\begin{array}{cc}\left(\mathrm{Equation}2\right)& \\ \mathrm{Force}\mathrm{applied}\mathrm{to}\mathrm{load}\mathrm{sensor}12=\mathrm{force}\mathrm{on}\mathrm{pad}6\left(\mathrm{reaction}\mathrm{force}\mathrm{for}\mathrm{descending}\mathrm{pad}6\right)++\mathrm{molding}\mathrm{load}& \left(2\right)\end{array}$

[0114] The force is maintained at a predetermined value except at the start and end of the application of the force . Immediately after the application of the force is started, the force gradually increases to a predetermined value. Since the application of the force is completed immediately before the bottom dead center of punch 1, the force gradually decreases from immediately before the bottom dead center of punch 1 and becomes 0 at the bottom dead center of punch 1.

[0115] Since the molding load is a force for performing molding work on workpiece 5, the molding load gradually increases while the force is maintained at a predetermined value. While the force is maintained at a predetermined value, punch 1 is pushed into workpiece 5 pressed by material presser 3, and the pushing amount of punch 1 increases. Therefore, the molding load for molding workpiece 5 gradually increases. Then, the molding load is maximized immediately before the bottom dead center of punch 1. The molding load decreases as the force decreases, and becomes zero at the bottom dead center of punch 1.

[0116] When punch 1 reaches the bottom dead center in process A3 of the graph illustrated in FIG. 4, the force and the molding load are eliminated, and the relationship of the forces of punch 1, workpiece 5, and pad 6 is balanced again between punch 1 and pad 6.

[0117] Here, the following relational expression (3) holds for a maximum value Pmax of the load detected by load sensor 12 before the bottom dead center of punch 1.

[00003]$\begin{array}{cc}\left(\mathrm{Equation}3\right)& \\ \mathrm{Maximum}\mathrm{value}P\max \mathrm{of}\mathrm{force}\mathrm{applied}\mathrm{to}\mathrm{load}\mathrm{sensor}12=\mathrm{force}\mathrm{on}\mathrm{pad}6\left(\mathrm{reaction}\mathrm{force}\mathrm{for}\mathrm{descending}\mathrm{pad}6\right)++\mathrm{molding}\mathrm{load}P\max & \left(3\right)\end{array}$

[0118] This is because since load sensor 12 is disposed between pad 6 and piston 7, load sensor 12 can sense the load without being affected by a sliding resistance between material presser 3 and punch 1.

[0119] Therefore, the following relational expression (4) holds for molding load Pmax.

[00004]$\begin{array}{cc}\left(\mathrm{Equation}4\right)& \\ \mathrm{Molding}\mathrm{load}P\max =\mathrm{Maximum}\mathrm{value}P\max \mathrm{of}\mathrm{force}\mathrm{applied}\mathrm{to}\mathrm{load}\mathrm{sensor}12-\mathrm{force}\mathrm{on}\mathrm{pad}6\left(\mathrm{reaction}\mathrm{force}\mathrm{for}\mathrm{descending}\mathrm{pad}6\right)-& \left(4\right)\end{array}$

[0120] Here, the force on pad 6 (reaction force for descending pad 6) can be expressed by the following relational expression (5).

[00005]$\begin{array}{cc}\left(\mathrm{Equation}5\right)& \\ \mathrm{Force}\mathrm{on}\mathrm{pad}6\left(\mathrm{reaction}\mathrm{force}\mathrm{for}\mathrm{descending}\mathrm{pad}6\right)=\mathrm{thrust}\mathrm{of}\mathrm{cylinder}8& \left(5\right)\end{array}$

[0121] The thrust of cylinder 8 can be obtained by the following equation (6) from the Pascal principle.

[00006]$\begin{array}{cc}\left(\mathrm{Equation}6\right)& \\ \mathrm{Cylinder}\mathrm{thrust}\left(F\right)=\mathrm{pressure}\mathrm{receiving}\mathrm{area}\left(A\right)\mathrm{of}\mathrm{piston}7\mathrm{cylinder}\mathrm{internal}\mathrm{pressure}\left(P\right)\mathrm{cylinder}\mathrm{thrust}\mathrm{efficiency}\left(\right)& \left(6\right)\end{array}$ [0122] where [0123] F: cylinder thrust (N), [0124] A: pressure receiving area of piston (mm.sup.2), and [0125] P: cylinder internal pressure (MPa).

[0126] As described above, molding load Pmax for molding workpiece 5 is calculated by performing processing of subtracting the force on pad 6 (reaction force for descending pad 6), which is a constant value, and the force for punch 1 to descend pad 6 with a force stronger than the force of pad 6 from maximum value Pmax of the force applied to load sensor 12.

[0127] The force on pad 6 (reaction force for descending pad 6) and the force for punch 1 to descend pad 6 with a force stronger than the force of pad 6 are forces generated in punch 1 when punch 1 is descended, and are also referred to as reaction force of punch 1. Therefore, molding load Pmax can be calculated by subtracting the reaction force of punch 1 from maximum value Pmax of the force applied to load sensor 12.

[0128] Returning to FIG. 3, in step S8, press-molding device 100 determines whether to change pushing amount H of punch 1 on the basis of molding load Pmax of workpiece 5 calculated in step S7. Molding load Pmax can be used to determine whether workpiece 5 is subjected to molding work into a predetermined shape. For example, determiner 19 of control unit 20 determines whether to change pushing amount H on the basis of whether molding load Pmax is included in a predetermined numerical range.

[0129] In a case where it is determined in step S8 that pushing amount H is to be changed, the processing proceeds to step S9. In a case where it is determined that pushing amount H is not to be changed, the processing proceeds to step S10.

[0130] In step S9, the press-molding device 100 changes die height DH (see FIG. 2). For example, determiner 19 of control unit 20 determines die height DH from pushing amount H of punch 1. Determiner 19 transmits a set value of die height DH to press controller 15 and changes die height DH. Thus, driver 32 is controlled with changed die height DH.

[0131] In step S10, press-molding device 100 determines whether to continue the molding work. In a case where the molding work is to be continued, the processing returns to step S1. In a case where the molding work is not to be continued, the processing ends.

Effects

[0132] Press-molding device 100 according to the present exemplary embodiment is a press-molding device for working on workpiece 5, and includes punch 1, die 2, material presser 3, pad 6, pressing unit 33, and load sensor 12. Die 2 is provided with hollow portion 2a into which punch 1 is inserted. Material presser 3 is disposed on the outer periphery of punch 1 and faces die 2. Pad 6 is disposed in hollow portion 2a of die 2. Pressing unit 33 presses pad 6 toward punch 1. Load sensor 12 is disposed between pad 6 and pressing unit 33.

[0133] With such a configuration, the load applied to workpiece 5 can be detected with high accuracy. In press-molding device 100, load sensor 12 is disposed between pad 6 and pressing unit 33 on the side of die 2. Therefore, for example, even if the sliding resistance between material presser 3 and punch 1 increases due to external influences or the like, the influence on the detection of the load of load sensor 12 can be reduced, and the load sensing on workpiece 5 can be stably performed.

[0134] Press-molding device 100 acquires information for detecting the position of punch 1. With such a configuration, the position of punch 1 can be detected, and the load applied to workpiece 5 can be detected with higher accuracy.

[0135] Press-molding device 100 includes driver 32 that drives punch 1, and control unit 20 that controls driver 32, pressing unit 33, and load sensor 12. With such a configuration, the load applied to workpiece 5 can be detected with higher accuracy.

[0136] Control unit 20 calculates molding load Pmax for molding workpiece 5 on the basis of load Pmax detected by load sensor 12 and the reaction force of punch 1, and controls driver 32 on the basis of molding load Pmax. With such a configuration, a load (molding load) applied to workpiece 5 can be accurately detected, and driver 32 can be accurately controlled on the basis of the molding load. Accordingly, stabler molding work can be performed.

[0137] Press-molding device 100 includes die plate 4 that holds die 2, and gap sensor 14 that detects the amount of the gap between material presser 3 and die plate 4. With such a configuration, the amount of the gap between material presser 3 and die plate 4 can be detected. As a result, for example, an abnormality such as inclination of material presser 3 can be detected.

[0138] Pressing unit 33 includes cylinder 8 having piston 7 movable in the moving direction of punch 1. With such a configuration, pad 6 can be pressed toward punch 1.

[0139] Cylinder 8 is an air cylinder, and press-molding device 100 further includes regulator 11 that controls the internal pressure of the air cylinder to a constant pressure. With such a configuration, pad 6 can be pressed at a constant pressure, and the load applied to workpiece 5 can be detected with higher accuracy.

[0140] The height of pad 6 is larger than the depth of hollow portion 2a of die 2. With such a configuration, the load applied to workpiece 5 can be detected with higher accuracy.

[0141] In the exemplary embodiment described above, an example in which the material of workpiece 5 is the SUS301-EH material has been described, but the present disclosure is not limited to this example. Furthermore, the thickness of workpiece 5 is not limited thereto. Workpiece 5 can include various metal materials.

[0142] Furthermore, in the structure of lower mold 31, a clearance between die 2 and pad 6 may have a mold structure in which the clearance is stabilized by a positioning pin or the like so that the sliding resistance does not affect load sensor 12 and an axis of pad 6 is not inclined instead of being in a perpendicular state.

[0143] In the above exemplary embodiment, an example has been described in which position sensors 13 are provided at the four corners of lower mold 31 in press-molding device 100, but the number and arrangement positions of position sensors 13 are not limited.

[0144] In the exemplary embodiment, an example has been described in which gap sensors 14 are provided at the four corners of die plate 4 in press-molding device 100, but the number and arrangement positions of gap sensors 14 are not limited.

[0145] In the exemplary embodiment, an example has been described in which the press-molding device 100 includes position sensor 13 and gap sensor 14, but the present disclosure is not limited to this example. Position sensor 13 and gap sensor 14 are not essential components.

[0146] In the flowchart illustrated in FIG. 3, each step may be added, deleted, or integrated. For example, steps S3 to S5 are not essential processing and may be deleted.

[0147] In the exemplary embodiment, an example has been described in which pressing unit 33 is cylinder 8 having piston 7, but the present disclosure is not limited to this example. Pressing unit 33 is only required to be configured to press pad 6 toward punch 1. For example, pressing unit 33 may be a spring, rubber, or the like.

[0148] Cylinder 8 is not limited to an air cylinder, and may be, for example, a hydraulic cylinder or the like.

[0149] In the exemplary embodiment, an example has been described in which the press-molding device 100 includes electromagnetic valve 9, pressure gauge 10, and regulator 11, but the present disclosure is not limited to this example. In press-molding device 100, electromagnetic valve 9, pressure gauge 10, and regulator 11 are not essential components.

[0150] The exemplary embodiment is described above to exemplify the technique disclosed in the present application. However, the technique in the present disclosure is not limited thereto, and may also be applied to exemplary embodiment in which changes, replacements, additions, omissions, or the like are made as appropriate.

[0151] Although the present disclosure is fully described with reference to preferred exemplary embodiment and with reference to the accompanying drawings, various variations and modifications are clear to those skilled in the art. Such variations and modifications are to be understood as being included within the scope of the present disclosure as set forth in the appended claims, unless departing from the scope of the present disclosure.

[0152] A general and specific aspect of the present disclosure may be implemented by a system, a method, a computer program, a computer-readable recording medium, and a combination of the above.

Overview of Exemplary Embodiment

[0153] (1) A press-molding device according to an aspect of the present disclosure works on a workpiece and includes a punch, a die provided with a hollow portion into which the punch is inserted, a material presser disposed on an outer periphery of the punch and facing the die, a pad disposed in a hollow portion of the die, a pressing unit configured to press the pad toward the punch, and a load sensor disposed between the pad and the pressing unit. [0154] (2) The press-molding device according to (1) may further include a position sensor configured to acquire information for detecting a position of the punch. [0155] (3) The press-molding device according to (1) or (2) may further include a driver configured to drive the punch, and a control unit configured to control the driver, the pressing unit, and the load sensor. [0156] (4) In the press-molding device according to (3), the control unit may calculate a molding load for molding the workpiece on the basis of a load detected by the load sensor and a reaction force of the punch, and may control the driver on the basis of the molding load. [0157] (5) The press-molding device according to any one of (1) to (4) may further include a die plate configured to hold the die, and a gap sensor configured to detect an amount of a gap between the material presser and the die plate. [0158] (6) In the press-molding device according to any one of (1) to (5), the pressing unit may include a cylinder having a piston movable in a moving direction of the punch. [0159] (7) In the press-molding device according to (6), the cylinder may be an air cylinder, and the press-molding device may further include a regulator configured to control an internal pressure of the air cylinder to a constant pressure. [0160] (8) In the press-molding device according to any one of (1) to (7), a height of the pad may be larger than a depth of the hollow portion of the die.

INDUSTRIAL APPLICABILITY

[0161] The press-molding device of the present disclosure is useful, for example, as a device that performs punching, bending, drawing, or the like on an arbitrary workpiece used for home electric appliances, medical devices, or the like.

REFERENCE MARKS IN THE DRAWINGS

[0162] 1 punch [0163] 2 die [0164] 2a hollow portion [0165] 3 material presser [0166] 4 die plate [0167] 5 workpiece [0168] 6 pad [0169] 7 piston [0170] 8 cylinder (pressing unit) [0171] 9 electromagnetic valve [0172] 10 pressure gauge [0173] 11 regulator [0174] 12 load sensor [0175] 13 position sensor [0176] 14 gap sensor [0177] 15 press controller [0178] 16 sensor controller [0179] 17 pressure controller [0180] 18 calculator [0181] 19 determiner [0182] 20 control unit [0183] 21 slide [0184] 22 bolster [0185] 23 servomotor [0186] 24 ball screw [0187] 25 shaft [0188] 26 press device body [0189] 30 upper mold [0190] 31 lower mold [0191] 32 driver [0192] 33 pressing unit [0193] 100 press-molding device