Bar material transfer method and conveyor

Abstract

A chuck device in a robot hand is used when receiving a primary formed workpiece from electrode chucks. After receiving the primary formed workpiece, and before inserting the primary formed workpiece from its shaft stem part into an insertion hole in a forging press main body, a portion held by the electrode chucks of the primary formed workpiece is gripped by a chuck device different from the chuck device, to release the gripping of the primary formed workpiece by the chuck device. Therefore, it is possible to insert the holding portion held by the electrode chucks from the side of the shaft stem part of the primary formed workpiece into the insertion hole. Thereby providing a bar material transfer method capable of accurately inserting the bar material from its one end into a predetermined positioning hole even if a bar material serving as a workpiece is short.

Claims

1. A bar material transfer method, comprising: providing a conveyor having a first pair of grippers and a second pair of grippers, the first pair of grippers and the second pair of grippers both being moved by the conveyor in accordance with conveyance movement of the conveyor; the first pair of grippers receiving an elongated bar material from a holder by gripping a part that is closer to a positioning hole insertion end of the bar material with respect to a distal portion that is held by the holder of the bar material; the second pair of grippers gripping the same distal portion held by the holder of the bar material after the first pair of grippers receiving the bar material and after the holder releasing the distal portion of the bar material held by the holder; the conveyor conveying the received bar material to a predetermined positioning hole and inserting the bar material into the predetermined positioning hole by inserting the positioning hole insertion end of the bar material lengthwise into the predetermined positioning hole, wherein the first pair of grippers releases the bar material after starting of the conveyor conveying the received bar material to the predetermined positioning hole but before the inserting of the bar material into the predetermined positioning hole such as to expose the part that is closer to the positioning hole insertion end to increase an insertion margin of the elongated bar material for improved insertion into the predetermined insertion hole.

2. The bar material transfer method according to claim 1, wherein the gripping of the bar material by the second pair of grippers, and the releasing of the gripping of the bar material by the first pair of grippers are performed during conveyance of the bar material by the conveyor.

3. The bar material transfer method according to claim 2, wherein a hole extending downward is prepared as the predetermined positioning hole, and during inserting of the positioning hole insertion end of the bar material into the predetermined positioning hole, when the part that is closer to the positioning hole insertion end, which was gripped by the first pair of grippers, of the bar material is inserted into the predetermined positioning hole, the gripping of the bar material by the second pair of grippers is released.

4. The bar material transfer method according to claim 3, wherein a pair of electrodes which grip the bar material, to apply electric current between the electrodes and the bar material ends are used as the holder, and a holding hole in the forging press main body which holds the insertion margin of the bar material, to form a head portion of a valve, is used as the predetermined positioning hole.

5. The bar material transfer method according to any one of claims 1 to 4, wherein the first pair of grippers and the second pair of grippers are installed adjacent to each other in the conveyor, and the first pair of grippers and the second pair of grippers each includes a pair of gripper claws which are capable of expanding and contracting, and the both pairs of gripper claws are disposed so as to be the same in expanding and contracting direction of the both pairs of gripper claws, and face one another.

6. A bar material transfer method, comprising: providing a first conveyor and a second conveyor, the first conveyor having a first pair of grippers and the second conveyor having a second pair of grippers, the first pair of grippers being moved by the first conveyor in accordance with conveyance movement of the first conveyor, the second pair of grippers being moved by the second conveyor in accordance with conveyance movement of the second conveyor; the first gripper receiving a bar material from a holder by gripping a part closer to one end part with respect to a portion held by the holder of the bar material and the holder releasing the portion held by the holder, of the bar material; after the holder releasing the bar material, the first conveyor conveying the received bar material toward a predetermined positioning hole to insert the bar material into the predetermined positioning hole form the one end part of the bar material, the second gripper gripping the portion held by the holder of the bar material and being moved by the second conveyor in accordance with conveyance movement of the first conveyor; and the first gripper releasing the bar material before the inserting of the bar material into the predetermined positioning hole.

7. The bar material transfer method according to any one of claims 1 to 4, wherein a robot hand or a robot having a robot hand is used as the conveyor.

8. The bar material transfer method according to claim 6, wherein the gripping of the bar material by the second pair of grippers, and the releasing of the gripping of the bar material by the first pair of grippers are performed during conveyance of the bar material by the conveyor.

9. The bar material transfer method according to claim 8, wherein a hole extending downward is prepared as the predetermined positioning hole, and at the time of inserting the bar material from the one end part of the bar material into the predetermined positioning hole, when the part, which has been gripped by the first pair of grippers, of the bar material is inserted into the predetermined positioning hole, the gripping of the bar material by the second pair of grippers is released.

10. The bar material transfer method according to claim 9, wherein a pair of electrodes which grip the bar material, to apply electric current between the electrodes and the bar material ends are used as the holder, and a holding hole in the forging press main body which holds one end part side of the bar material, to form the other end part of the bar material as a head portion of a valve, is used as the predetermined positioning hole.

11. The bar material transfer method according to any one of claims 6, 8, 9, and 10, wherein a robot hand or a robot having a robot hand is used as the first and second conveyor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a plan view showing an entire configuration of a valve forging automation line according to an embodiment.

(2) FIG. 2 is a perspective view showing an upsetter used for the valve forging automation line according to the embodiment.

(3) FIG. 3 is a diagram (a diagram viewed from the right side in FIG. 1) showing a high speed multi-jointed robot which conveys a primary formed workpiece to a forging press main body.

(4) FIG. 4 is an explanatory diagram for explanation of the manufacturing processes of the valve forging automation line according to the embodiment.

(5) FIG. 5 is an enlarged front view showing around a robot hand of the high speed multi-jointed robot according to the embodiment.

(6) FIG. 6 is an enlarged front view showing around the robot hand of the high speed multi-jointed robot according to the embodiment.

(7) FIG. 7 is an explanatory diagram for explanation of a transfer method according to an embodiment.

(8) FIG. 8 is an explanatory diagram for explanation following FIG. 7.

(9) FIG. 9 is an explanatory diagram for explanation following FIG. 8.

(10) FIG. 10 is an explanatory diagram for explanation following FIG. 9.

(11) FIG. 11 is an explanatory diagram for explanation following FIG. 10.

(12) FIG. 12 is an explanatory diagram for explanation following FIG. 11.

(13) FIG. 13 is an explanatory diagram for explanation of a transfer method according to a conventional technology.

(14) FIG. 14 is an explanatory diagram for explanation following FIG. 13.

(15) FIG. 15 is an explanatory diagram for explanation following FIG. 14.

(16) FIG. 16 is an explanatory diagram for explanation following FIG. 15.

(17) FIG. 17 is an explanatory diagram for explanation following FIG. 16.

(18) FIG. 18 is a time chart used for the transfer method according to the embodiment.

(19) FIG. 19 is a flowchart showing an example of control by a controller unit according to the embodiment.

(20) FIG. 20 is a flowchart following FIG. 19.

BEST MODE FOR CARRYING OUT THE INVENTION

(21) Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(22) FIG. 1 shows a valve forging automation line 1 in which respective devices for forging valves are arranged linearly. In this valve forging automation line 1, a forging press main body 10 is disposed in the center of the linearly-arranged line, and bar material charging devices 40A (40B) and upsetters 20A (20B) are respectively disposed in sequence toward the forging press main body 10 on the both sides of the forging press main body 10. Then, in order to appropriately perform transfer of a workpiece W between the respective devices 10, 20A (20B), and 40A (40B), bar material feeding devices 30A (30B) are respectively disposed on the front face sides of the respective bar material charging devices 40A (40B) and upsetters 20A (20B), and high speed multi-jointed robots (conveyors) 60A (60B) are respectively disposed between the respective upsetters 20A (20B) and the forging press main body 10.

(23) The aforementioned bar material charging device 40A (40B) includes a bar material feeding route 42 as shown in FIG. 1. This bar material feeding route 42 is to feed round bar materials W (bar materials) serving as workpieces sequentially toward the bar material feeding devices 30A (30B) (refer to FIG. 4 as well).

(24) The aforementioned bar material feeding device 30A (30B) includes a chuck 36 for bar material feeding as shown in FIG. 1. This chuck 36 is configured to be slidable in a horizontal direction (the horizontal direction in FIG. 1) and a front-back direction (the vertical direction in FIG. 1) on the front side of the upsetter 20A (20B) and the bar material charging device 40A (40B). This chuck 36 is to grasp the round bar material W on the bar material feeding route 42 in the bar material charging device 40, and feed the round bar material W to vacant forming stages 20A1 and 20A2 (20B1 and 20B2) of the upsetter 20A (20B) (refer to FIG. 4 as well).

(25) The aforementioned upsetter 20A (20B) has a role of forming the round bar material W into a primary formed workpiece W1 (bar material) formed into a shape that one end part side is a stem part W11 and the other end part side is bulging (the bulging portion is denoted by symbol W12) as shown in FIG. 4. Therefore, as shown in FIGS. 1 to 3, the forming stages 20A1 and 20A2 (20B1 and 20B2) are provided so as to be installed adjacent to one another in the horizontal direction on the front face side of the upsetter 20A (20B), and the respective forming stages 20A1 and 20A2 (20B1 and 20B2) are equipped with right and left pairs of electrode chucks 22 and 22 which receive the round bar material W from the chuck 36, to grip the round bar material W so as to vertically extend, anvil electrodes 23 which are disposed above the right and left pairs of electrode chucks 22 and 22, and pressurizing devices 24 which are disposed under the right and left pairs of electrode chucks 22 and 22, to press one end part side of the round bar material W upward, thereby pressing the other end part of the round bar material W against the anvil electrodes 23. In this upsetter 20A (20B), the anvil electrode 23 side of the round bar material W (the other end part side of the round bar material W) is heated to be melted by applying electric current, to be formed into a primary formed workpiece W1 formed into a shape that the heat-melted portion is bulging (having the bulging portion W12), and when the forming is completed, the application of electric current is stopped, to stop heating of the primary formed workpiece W1.

(26) In addition, symbol 24a denotes an elevator rod of the pressurizing device 24 which supports the workpiece W from the lower side.

(27) The aforementioned forging press main body 10 has a role of secondarily forming the primary formed workpiece W1 formed in the upsetter 20A (20B) as shown in FIG. 4. Therefore, the forging press main body 10 is equipped with a pair of upper and lower forging dies 11 for secondary formation as shown in FIG. 1. An insertion hole 12 (a predetermined positioning hole) for inserting and holding the stem part of the primary formed workpiece W1 (the portion on the one end part side of the round bar material W) in order to position the bulging portion W12 of the primary formed workpiece W1 on the upper side of the lower mold 11, so as to appropriately perform secondary formation is opened into the top face of the lower mold (hereinafter, the symbol for the forging die 11 is used) in the forging press main body 10 (refer to FIG. 11 which will be described later).

(28) The aforementioned high speed multi-jointed robot 60A (60B) has a role of conveying the primary formed workpiece W1 formed in the upsetter 20A (20B) to the forging press main body 10, to insert the primary formed workpiece W1 into the through hole 12 in the lower mold 11 as shown in FIGS. 1 and 3. Therefore, the high speed multi-jointed robot 60A (60B) is equipped with a robot main body 61, a rear end side arm 62a, a front end side arm 62b, and a robot hand (conveyor) 62c, and the structure which is capable of turning around six axes (L1 to L6) is composed of those respective components 61, and 62a to 62c. Specifically, the robot main body 61 is capable of circling around a vertical spindle L1, and the rear end side arm 62a is capable of turning around a horizontal spindle L2 with respect to the robot main body 61. Further, the front end side arm 62b is capable of turning around a horizontal spindle L3 in the front end portion of the rear end side arm 62a and a spindle L4 along the central shaft of the arm 62b respectively, and the robot hand 62c is capable of turning around a horizontal spindle L5 on the front end side of the arm 62b and a vertical spindle L6 on the front end side of the arm 62b.

(29) As shown in FIGS. 1, 3, 5, and 6, first and second chuck devices 64A and 65A (64B and 65B) are respectively mounted as one gripping means (the first gripping means) and the other gripping means (the second gripping means) to the robot hand 62c in the aforementioned high speed multi-jointed robot 60A (60B). The first chuck device 64A (64B) includes a first pair of claw parts (a first pair of grippers) 64A1 (64B1) which expands and contracts (opens and closes) to grip and release gripping the stem part W11 of the primary formed workpiece W1, an air-driven cylinder device (the interior of the cylinder is partitioned into two chambers with a piston, and the piston is displaced by supply adjustment of compressed air to the two chambers, to cause the drive rod to make a telescopic motion due to its displacement motion) 64A2 (64B2) which has a drive rod (not shown), and causes the first pair of claw parts 64A1 (64B1) to expand and contract (open and close) on the basis of a telescopic motion of the drive rod, a compressor 66A (66B) serving as an air-driving source which supplies compressed air to the air-driven cylinder 64A2 (64B2), to cause the drive rod of the air-driven cylinder device 64A2 to make a telescopic motion on the basis of the compressed air, and a first adjusting valve (electromagnetic) 64A3 (64B3) serving as first gripper adjusting means which performs supply adjustment of compressed air from the compressor 66A to the air-driven cylinder device 64A2 (64B2). The second chuck device 65A, which is premised on that the compressor 66A is provided as a common component, includes a second pair of claw parts (a second pair of grippers) 65A1 (65B1), an air-driven cylinder device 65A2 (65B2), and a second adjusting valve (a second pair of grippers) 65A3 (65B3) as components which are the same as those of the first chuck device 64A.

(30) In this case, the first and second pairs of claw parts 64A1 and 65A1 (64B1 and 65B1) in the first and second chuck devices 64A and 65A (64B and 65B) are, as shown in FIG. 6, both capable of opening up to 180 degrees, and close so as to be capable of reliably gripping the stem part W11 of the thin primary formed workpiece W1 serving as a workpiece.

(31) With respect to the first and second pairs of claw parts 64A1 and 65A1 (64B1 and 65B1), in a standard position state (in the state of FIG. 5), the first pair of claw parts 64A1 (64B1) is disposed on the lower side of the second pair of claw parts 65A1 (65B1). The first pair of claw parts 64A1 (64B1) and the second pair of claw parts 65A1 (65B1) are disposed so as to be installed adjacent to one another, and the first and second respective pairs of claw parts 64A1 and 65A1 (64B1 and 65B1) are brought into a layout state so as to be the same in expanding and contracting direction and face one another. In addition, in the present embodiment, a space between the first pair of claw parts 64A1 (64B1) and the second pair of claw parts 65A1 (65B1) is, as shown in FIG. 5, brought into a state in which a front end side space Lf between the both first and second pairs of claw parts 64A1 and 65A1 (64B1 and 65B1) is made as close as possible, so as to respond to gripping of a short round bar material W. On the other hand, a rear end side space Lb is widened as compared with the front end side space Lf in consideration of the facts that the thicknesses of the respective air-driven cylinder devices 64A2 and 65A2 (64B2 and 65B2) must be thicker than the thicknesses of the respective pairs of claw parts 64A1 and 65A1 (64B1 and 65B1), and further, it is intended to improve the degree of freedom of attachment of the respective pairs of claw parts 64A1 and 65A1 (64B1 and 65B1).

(32) Moreover, in the present embodiment, as shown in FIG. 1, a secondary formed workpiece collecting unit 74 is provided on the opposite side of the aforementioned upsetter 20A (20B) over the aforementioned bar material feeding device 30A (30B). This secondary formed workpiece collecting unit 74 has a role of receiving a secondary formed workpiece W2 formed by the forging press main body 10 with the high speed multi-jointed robot 60A (60B) described above, to collect it during a time until the thermal treatment which is the following process is performed.

(33) The high speed multi jointed robot 60A (60B) described above is, as shown in FIG. 5, equipped with a controller unit U (control means) which controls the first adjusting valve 64A3 (64B3), the second adjusting valve 65A3 (65B3), a drive adjusting unit 80 for the electrode chucks 22 and 22, and a robot drive adjusting unit 81. A receiving timing signal from a receiving timing detecting mechanism 82 that detects that heating in the upsetter 20A (20B) is terminated (the completion of formation), an elapsed time T.sub.C1 signal from a first elapsed time detecting mechanism 83 that detects an elapsed time T.sub.C1 of a first timer, an elapsed time T.sub.C2 signal from a second elapsed time detecting mechanism 84 that detects an elapsed time T.sub.C2 of a second timer, gripping and gripping-release signals from a first claw part state detecting sensor 85 that detects gripping and gripping-released states of the first pair of claw parts 64A1 (64B1), gripping and gripping-release signals from a second claw part state detecting sensor 86 that detects gripping and gripping-released states of the second pair of claw parts 65A1 (65B1), a positional information signal from a positional information detecting sensor 87 that detects positional information on the first and second pairs of claw parts 64A1 and 65A1 (64B1 and 65B1), a moving state signal from a movement detecting sensor 88 that detects the presence or absence of a movement of the robot hand, and holding and holding-release signals from an electrode chuck state detecting sensor 89 that detects holding and holding-released states of the electrode chucks 22 and 22 are input to the controller unit U. On the other hand, control signals are output to the first and second adjusting valves 64A3 and 65A3 (64B3 and 65B3), the drive adjusting unit 80 for the electrode chucks 22 and 22, and the robot drive adjusting unit 81 from the controller unit U.

(34) In this valve forging automation line 1, as shown in FIG. 4, the bar material feeding device 30A (30B) feeds the round bar material W serving as a workpiece fed by the bar material charging device 40A (40B), to the upsetter 20A (20B), and the upsetter 20A (20B) forms the round bar material W into a primary formed workpiece W1 formed into a shape that the other end part side (the upper side in the present embodiment) of the round bar material W is bulging. The primary formed workpiece W1 is conveyed to the forging press main body 10 by the high speed multi-jointed robot 60A (60B), and the primary formed workpiece W1 is formed into a valve as a secondary formed workpiece W2 in the forging press main body 10. This secondary formed workpiece W2 is conveyed to the secondary formed workpiece collecting unit 74 by use of the high speed multi-jointed robot 60A (60B) again, and the secondary formed workpiece W2 collected in the secondary formed workpiece collecting unit 74 is conveyed to a batch-type heating treatment furnace (not shown) by a worker, for example, at the stage at which the secondary formed workpiece W2 is cooled down after a predetermined time elapsed.

(35) In this valve forging automation line 1, at the time of conveying the primary formed workpiece W1 to the forging press main body 10 from the upsetter 20A (20B), a transfer method according to the present embodiment is used. That transfer method will be described on the basis of FIGS. 7 to 12 along with the outline of the aforementioned controller unit U.

(36) In the upsetter 20A (20B), at the time of forming a relatively short round bar material W serving as a workpiece into a primary formed workpiece W1, as shown in FIG. 7, the round bar material W is held so as to be positioned vertically extending by the electrode chucks 22 and 22, and its gripping position is on the other end part side of the round bar material W to the utmost extent (the upper side in FIG. 6). On the other hand, the both first and second pairs of claw parts 64A1 and 65A1 (64B1 and 65B1) of the robot hand 62c reach the waiting positions before the completion of formation of the primary formed workpiece W1 in the upsetter 20A (20B), and are waiting in a state in which the respective pairs of claw parts 64A1 and 65A1 (64B1 and 65B1) are open (refer to FIG. 7).

(37) In this presupposed state, when application of electric current (heating) is stopped by considering that the round bar material W serving as a workpiece is formed into the primary formed workpiece W1, and the formation is completed in the upsetter 20A (20B), the first pair of claw parts 64A1 (64B1) grips a stem part lower portion W11b on the side lower than the holding portion W11a of the stem part W11 of the primary formed workpiece W1 held by the electrode chucks 22 and 22 (the portion on the one end part side of the round bar material W).

(38) As described above, when the first pair of claw parts 64A1 (64B1) grips the stem part lower portion 11b of the stem part W11 of the primary formed workpiece W1, the electrode chucks 22 and 22 release the gripping of the primary formed workpiece W1, and according to this, the high speed multi jointed robot 60A (60B) starts to convey the primary formed workpiece W1 toward the forging press main body 10 through the motions of the robot main body 61, the arms 62a and 62b, and the robot hand 62c on the basis of information that the teaching has been undertaken in advance. When this conveyance of the primary formed workpiece W1 is performed, during that conveyance, as shown in FIG. 9, the second pair of claw parts 65A1 (65B1) grips the holding portion W11a which has been held until now by the electrode chucks 22 of the stem part W11 of the primary formed workpiece W1, and next, as shown in FIG. 10, the first pair of claw parts 64A1 (64B1) releases the gripping of the stem part lower portion W11b of the primary formed workpiece W1. In accordance with this, an insertion margin for the insertion hole 12 in the forging press main body 10 is newly secured with the lower portion W11b in the primary formed workpiece W1.

(39) When the first pair of claw parts 64A1 (64B1) releases the gripping of the stem part lower portion W11b of the primary formed workpiece W1, as shown in FIG. 11, the primary formed workpiece W1 is conveyed to the insertion hole 12 in the forging press main body 10 by gripping by the second pair of claw parts 65A1 (65B1) (the movement of the robot hand 62c), and the lower portion W11b of the stem part W11 in the primary formed workpiece W1 is inserted into the insertion hole 12 from the upper side. Then, when the stem part lower portion W11b in the primary formed workpiece W1 is inserted into the insertion hole 12, the robot hand 62c stops moving, and releases the gripping by the second pair of claw parts 65A1 (65B1). In accordance with this, the primary formed workpiece W1 drops down so as to be guided by the inner wall of the insertion hole 12 due to its own weight, and eventually, as shown in FIG. 12, the bulging portion W12 of the primary formed workpiece W1 is received by the lower mold 11, and the primary formed workpiece W1 is accurately set (inserted to be held) in the forging press main body 10 even if its entire length is short.

(40) On the other hand, in an existing single hand type composed of only the first pair of claw parts 64A1 (64B1), in the case where the round bar material W serving as a workpiece is short, after the round bar material W is formed into the primary formed workpiece W1 by the upsetter 20A (20B), the single hand type grips the stem part lower portion W11b on the side lower than the holding portion W11a held by the electrode chucks 22, of the primary formed workpiece W1 with the pair of claw parts 64A1 (64B1), thereby it is possible to convey the primary formed workpiece W1 (refer to FIGS. 13 to 15). However, because there is no insertion margin in the stem part W11 of the primary formed workpiece W1 because of that gripping, as shown in FIGS. 16 and 17, even if it is intended to insert the stem part W11 of the primary formed workpiece W1 into the insertion hole 12 in the forging press main body 10, it is impossible to insert the stem part W11 of the primary formed workpiece W1.

(41) An example of control by the controller unit U at the time of transferring a workpiece from the upsetter 20A (20B) to the forging press main body 10 will be described in detail on the basis of a time chart shown in FIG. 18, and flowcharts shown in FIGS. 19 and 20. In addition, in FIGS. 19 and 20, S denotes a step. Further, a presupposed state for the start at the time of transferring a workpiece from the upsetter 20A (20B) to the forging press main body 10 is the same as described above (refer to FIG. 6).

(42) First, in S1, it is judged whether or not the heating in the upsetter 20A (20B) is terminated because of the completion of primary formation of the round bar material W. As long as the heating in the upsetter 20A (20B) is not terminated, the judgment is repeated. On the other hand, when it is YES in S1, in S2, a control signal for causing the first pair of claw parts 64A1 (64B1) to perform gripping is output to the first adjusting valve 64A3 (64B3). In accordance with this, the first pair of claw parts 64A1 (64B1) grips the stem part lower portion W11b (one end part side portion of the round bar material W) on the side lower than the stem part holding portion W11a of the primary formed workpiece W1 (bar material) which is held by the electrode chucks 22 and 22 in the upsetter 20A (20B) (refer to FIG. 8).

(43) Next, in S3, the first timer is set (time TC1=0), and in the following S4, 1 is added to the time TC1, to start counting the time TC1. Then, in the following S5, it is judged whether or not the time TC1 has reached a predetermined time TC10, and when it is judged as NO, the process is returned to S4, to continue counting the time. On the other hand, when it is judged as YES in S5, it is considered that the time TC1 has reached the predetermined time TC10, and in S6, a holding release signal is output to the drive adjusting unit 80 for the electrode chucks 22. In accordance with this, the electrode chucks 22 and 22 release the holding of the primary formed workpiece W1. At this time, because the first pair of claw parts 64A1 (64B1) has already gripped the round bar material W as described above, even if the electrode chucks 22 release the holding of the primary formed workpiece W1, the primary formed workpiece W1 does not drop in any case.

(44) When a holding release signal is output to the drive adjusting unit 80 for the electrode chucks 22 and 22, in S7, it is judged whether or not the electrode chucks 22 and 22 have actually released the holding of the primary formed workpiece W1. When it is judged as No in S7, the process is returned to S6, the processing in S6 and the judgment in S7 are repeated. On the other hand, when it is judged as YES in S7, in S8, driving of the robot main body 61, the arms 62a and 62b, and the robot hand 62c of the high speed multi-jointed robot 60A (60B) is started, and the high speed multi-jointed robot 60A (60B) performs a recorded moving operation that the teaching has been undertaken for the high speed multi-jointed robot 60A (60B). In accordance with this, a movement such as transfer of the primary formed workpiece W1 (a movement of the robot hand 62c) is started. In this case, the movement of the primary formed workpiece W1 is performed on the basis of the moving operation of the robot hand 62c which holds the primary formed workpiece W1. Meanwhile, the moving operation of the robot hand 62c includes not only the moving operation of the robot hand 62c itself, but also the moving operation of the robot hand 62c on the basis of motions of the robot main body 61 and the arms.

(45) When a movement of the robot hand 62c is started to start moving the primary formed workpiece W1, in S9, it is judged whether or not the robot hand 62c (the first and second pairs of claw parts 64A1 and 65A1 (64B1 and 65B1) passes through a first predetermined position on the recorded moving operation route. This first predetermined position is spaced at a predetermined distance from the upsetter 20A (20B), and is set as the limit of a position at which, even if the first and second pairs of claw parts 64A1 and 65A1 (64B1 and 65B1) make opening and closing motions, those do not interfere with the upsetter 20A (20B) and the other devices. When it is judged as NO in S9, the judgment is repeated. On the other hand, when it is judged as YES in S9, in S10, a control signal for causing the second pair of claw parts 65A1 (65B1) to perform gripping is output to the second adjusting valve 65A3 (65B3). In accordance with this, the second pair of claw parts 65A1 (65B1) grips the holding portion W11a which has been held until now by the electrode chucks 22 and 22 in the upsetter 20A (20B), of the stem part W11 of the primary formed workpiece W1 (refer to FIG. 9).

(46) When the control signal for causing the second pair of claw parts 65A1 (65B1) to perform gripping is output to the second adjusting valve 65A3 (65B3) in S10, the second timer is set (time TC2=0) in S11, and in S12, it is judged whether or not the robot hand 62c (the first and second pairs of claw parts 64A1 and 65A1 (64B1 and 65B1)) has not yet reached a second predetermined position on the recorded moving operation route. This second predetermined position is spaced at a predetermined distance from the forging press main body 10, and is set as the limit of a position at which, even if the first and second pairs of claw parts 64A1 and 65A1 (64B1 and 65B1) make opening and closing motions, those (including the primary formed workpiece W1 as well) do not interfere with the forging press main body 10 and the other devices. When it is judged as YES in S12, it is considered that an interference problem is not caused with respect to the first and second pairs of claw parts 64A1 and 65A1 (64B1 and 65B1), after the time TC2 is counted in the state in which the robot hand 62c moves (S13), the process proceeds to the following S14. On the other hand, when it is judged as NO in S12, that is, when it is judged that the robot hand 62c has reached the second predetermined position, it is considered that an interference problem is caused with respect to the first and second pairs of claw parts 65A1 and the like due to the following movement, and in S15, the movement of the robot hand 62c (the robot main body 61, the arms 62a and 62b) is stopped, and in S13, the time TC2 is counted in the state in which the robot hand 62c is stopped.

(47) In the following S14, it is judged whether or not the time T.sub.C2 has reached a predetermined time T.sub.C20. When it is judged as NO in S14, the process is returned to S12, and a series of processings (S12 to S14, and S15) is repeated. On the other hand, when it is judged as YES in S14, in S16, a control signal for causing the first pair of claw parts 64A1 (64B1) to release the gripping is output to the first adjusting valve 64A3 (64B3). In accordance with this, the first pair of claw parts 64A1 (64B1) releases the gripping of the primary formed workpiece W1. At this time, because the second pair of claw parts 65A1 (65B1) is gripping the stem part W11 of the primary formed workpiece W1, the primary formed workpiece W1 does not drop in any case, and further, because of the release of the gripping by the first pair of claw parts 64A1 (64B1), the stem part lower portion W11b of the primary formed workpiece W1 is released, so as to secure an insertion margin.

(48) In S16, when the control signal for causing the first pair of claw parts 64A1 (64B1) to release the gripping is output to the first adjusting valve 64A3 (64B3), in S17, it is judged whether or not the robot hand 62c (the first and second pairs of claw parts 64A1 and 65A1, and the primary formed work W1) has not yet reached the second predetermined position. When it is judged as YES in S17, it is considered that an interference problem is not caused with respect to the first and second pairs of claw parts 64A1 and 65A1, etc., and in the state in which the robot hand 62c moves, in the following S18, it is judged whether or not the first pair of claw parts 64A1 (64B1) has released the gripping. On the other hand, when it is judged as NO in S17, in S19, it is judged whether or not the movement of the robot hand 62c is stopped. When the robot hand 62c has not yet been stopped, in S20, the process proceeds to S18 after the movement of the robot hand 62c is stopped, and in the case where it is judged by the judgment in S19 that the robot hand 62c has been already stopped, the process directly proceeds to S17.

(49) In S18, when it is judged that the first pair of claw parts 64A1 (64B1) has not released the gripping, the process is returned to S16, and a series of processings (S16 to S20) is repeated. On the other hand, when it is judged as YES in S18, it is judged that the first pair of claw parts 64A1 (64B1) has released the gripping, and in S21, it is judged whether or not the robot hand 62c has been stopped. When it is judged as YES in S21, because the robot hand 62c has been stopped, in S22, the robot hand 62c again starts moving. In the following S23, it is judged whether or not the stem part W11 of the primary formed workpiece W1 is inserted from the upper side into the insertion hole 12 of the lower mold 11 in the forging press main body 10 on the basis of the movement of the robot hand 62c. On the other hand, when it is judged as NO in S21, the process directly proceeds to S23.

(50) In S23, when it is judged as NO, its judgment processing is repeated. On the other hand, when it is judged as YES in S23, in S24, the movement of the robot hand 62c is stopped, and in the following S25, a control signal for causing the second pair of claw parts 65A1 (65B1) to release the gripping is output to the second adjusting valve 65A3 (65B3), and the second pair of claw parts 65A1 (65B1) releases the gripping of the primary formed workpiece W1. In accordance with this, the primary formed workpiece W1 drops due to its own weight, and the stem part W11 of the primary formed workpiece W1 is inserted into the insertion hole 12 so as to be guided by the inner wall of the insertion hole 12 in the forging press main body 10.

(51) In the following S26, it is judged whether the second pair of claw parts 65A1 (65B1) has actually released the gripping. When it is judged as NO in S26, the process is returned to S25, to wait for that the second pair of claw parts 65A1 (65B1) releases the gripping. On the other hand, when it is judged as YES in S26, in S27, it is considered that the transfer of the primary formed workpiece W1 to the forging press main body 10 is terminated, and the robot hand 62c proceeds to the following process.

(52) The embodiment has been described above. Meanwhile, the present invention includes the following modes.

(53) (I) The present invention is used for, not only transfer in valve forging, but also other uses.

(54) (II) The both first and second pairs of claw parts 64A1 and 65A1 (64B1 and 65B1) are not provided for one robot hand, and a pair of claw parts is provided for each of two robots, and transfer of a primary formed workpiece serving as a workpiece (conveyance from the upsetter 20A (20B) to the forging press main body 10) is performed by use of the two robots.

REFERENCE SIGNS LIST

(55) 10 . . . Forging press main body 11 . . . Forging die for forging press main body 12 . . . Insertion hole (Predetermined positioning hole, holding hole) 20A, 20B . . . Upsetter 22 . . . Electrode chuck (Holding means) 60A, 60B . . . High speed multi jointed robot (conveyor) 62c . . . Robot hand (conveyor) 64A, 64B . . . Chuck devices (One and another gripping means, First and second gripping means) 64A1, 64B1 . . . First pair of claw parts (A pair of grippers of the first gripping means) 65A1, 65B1 . . . Second pair of claw parts (A pair of grippers of the second gripping means) 64A3, 64B3 . . . First adjusting valve (First gripper adjusting means) 65A3, 65B3 . . . Second adjusting valve (Second gripper adjusting means) 81 . . . Robot drive adjusting unit 82 . . . Receiving timing detecting mechanism (Receiving timing detection means) 83 . . . First elapsed time detecting mechanism 84 . . . Second elapsed time detecting mechanism 85 . . . First claw part state detecting sensor (First gripping detection means) 86 . . . Second claw part state detecting sensor (Second gripping detection means) 87 . . . Positional information detecting sensor (Positional information detection means) 88 . . . Movement detecting sensor Lf . . . Front end side space between the first pair of claw parts and the second pair of claw parts Lb . . . Rear end side space between the first pair of claw parts and the second pair of claw parts W . . . Round bar material (Bar material) W1 . . . Primary formed workpiece (Bar material) W11 . . . Stem part of primary formed workpiece W11a . . . Holding portion held by electrode chucks of the stem part of the primary formed workpiece W11b . . . Stem part lower portion of the primary formed workpiece W2 . . . Secondary formed workpiece (Bar material) U . . . Controller unit (Control means)