WORK PIECE TRANSFER MECHANISM FOR A TRANSFER PRESS

Abstract: The mechanism comprises a pair of feed bars (7.7) performing clamping and unclamping, lifting and lowering movements. The horizontal movements are exerted via a screw rod (14) with left hand and right hand portions (14a, 14b). For the vertical movements is provided a spline rod (15).

Description: Detailed Description of the Invention (Field of Industrial Application The present invention relates to a feed bar driving apparatus for a transfer press, and more particularly to an apparatus for clamping and unclamping the feed bars. (Prior Art) A device for clamping and unclamping the feed bars by means of a screw mechanism such as a ball thread, etc. is known as disclosed in the Japanese Utility Model Laid-Open No. 60-136828. In the device as disclosed therein, a rod is adapted toto reciprocate in association with a press slide and connected via a ball joint to a screw rod consisting of a helical gear, and a ball thread is rotated in association with the screw rod and threadedly fitted with feed bar receptacles, whereby up-and-down movement of the rod causes the feed bar receptacles to move toward and away from each other and the feed bars to perform clamping and unclamping movement. The ball thread is formed with left-handed and right-handed screws so that the feed bar receptacles move in the opposite directions to each other when the screw rod rotates. In the above-described device, the internal width between the feed bars is adjusted by rotating the screw rod and the ball thread, with the press in non-operating condition. Further, in the above-described device, a servomotor as a driving unit for the internal width adjustment is pro­ vided below a clamp cylinder and disposed in a hole formed at the lower end of the press machine. Thus, this device has a problem that a deep hole must be formed. Still further, the above-described device has gears and motors mounted to vertically moving parts, resulting in excessive inertia acting upon a cam lever and disadvantage for high-speed stability. In addition, wiring becomes dif­ ficult because of mounting the motors to the moving parts. There are two kinds of prior art apparatuses, one which cannot adjust the lengths of feed bar clamp and lift strokes while the other that can make such adjustment. Generally, the prior art apparatus includes a rod moving up and down in association with a cam provided on a slide, and a clamp unit having therein a feed bar driving apparatus, wherein the up-and-down movement of the rod causes the feed bars to perform clamping and unclamping as well as lifting and lowering movements in the clamp unit. In the former type apparatus, the height of the rod-­ driving cam provided on the slide must be changed or the clamp drive mechanism must be changed, in order to change the feed bar clamp and/or lift stroke length. Actually, the apparatus cannot change its stroke length once it is manu­ factured. The latter type apparatus adopts a mechanism of changing a fulcrum position of the lever, but with change in said position, both swinging ends of the lever will be changed. Consequently, the internal width between the feed bars needs to be adjusted every time the clamp stroke is changed. Thus, there are problems that adjusting operation becomes compli­ cated in case that the transfer device is independently and manually operated and that programming becomes also compli­ cated in case of automatic adjustment. (Objects of the Invention) It is one of the present invention to solve the prior art problems and to provide an apparatus which can enlarge the range available for the feed bar internal width by using a ball thread as feed bar clamping mechanism and adjusting the internal width means of a worm and rack mechanism. It is another object of the present invention to provide an apparatus which can change only the clamp stroke without changing clamp end (the internal width of the feed bars) and also change the lift stroke without changing down end (the feed line of the feed bars). The present invention is characterized in that feed bar receptacles for supporting feed bars are driven by a feed screw rod consisting of a ball thread and a screw rod is connected via a ball joint to a rod reciprocating in association with press drive system, which screw rod is connected at one end thereof to a piston housed in a clamp cylinder and is formed at one portion thereof as a spline engaged with a worm wheel that is provided in the clamp cylinder and engaged with a worm rod connected to a drive shaft of a motor on the side of the clamp cylinder, said feed screw rod being connected to said screw rod via a trans­ mission mechanism so that it may be driven by reciprocation and rotation of said screw rod. Further, the present invention comprises a lever having a cam follower at one end thereof and connected to the rod at the other end, said lever being formed with a longitudinal opening in the central portion thereof, a fulcrum member slidably housed in the opening of the lever, and a link having an axis for rotation at one end thereof with the other end facing the fulcrum member, said facing portion being connected with a pin provided at the center of the fulcrum member, said opening of the lever being formed in an arc corresponding to the locus of the pin when the link rotates with the lever at either limit of its swinging motion, said rod being connected at the lower end thereof to the clamp unit, and said cam follower of the lever being in contact with a cam rotated in association with a crankshaft, wherein the present apparatus is selectively used when the clamp and/or lift stroke is adjusted. (Description of the Drawings) Fig. 1 is a schematic front view of the press; Fig. 2A is a side view of a feed bar clamping and unclamping mechanism and a stroke adjusting mechanism incor­ porated in the press, and Fig. 2B is a detailed view thereof; Fig. 3 is a sectional view of a clamp cylinder; Fig. 4 is a sectional view taken on line IV - IV of Fig. 3; Fig. 5 is a sectional view taken on line V - V of Fig. 2B; Fig. 6A is a side view of an adjusting mechanism of the feed bar clamp and lift strokes, Fig. 6B is a detailed view thereof; Fig. 7 is a sectional view of an adjustment unit; Fig . 8 to 11 show other embodiments of the feed bar clamping and unclamping apparatus, and Fig. 8 is a sectional view of one apparatus thereof; Fig. 9 is a sectional view taken on line IX - IX of Fig. 8; Fig. 10 is a view explaining the engagement of gears which provide a device for reversing rotation; Fig. 11 is a sectional view of another reversion device comprising helical gears. (Embodiments) Fig. 1 is a schematic front view of a press 1 having a crown 2 and a bed 3 joined together by columns 4 and 4, inside which a press slide 5 is provided and is lifted and lowered with relative to a bolster 6 provided on the bed 3. A pair of feed bars 7 and 7 are provided on both sides of plural dies, not shown, placed on the bolster 6, and the feed bar is connected at one end to a drive unit casing 8 where it receives advancing and returning movement and at the other end to a drive unit casing 9 where it receives clamping and unclamping and lifting and lowering movements. Referring to Figs. 2 to 5, the pair of feed bars 7 and 7 are respectively disposed on feed bar receptacles 10 and 10 so that they may slide in the longitudinal direction, and the feed bar receptacles 10 and 10 are respectively mounted on carts 11 and 11. A guide 12 is provided perpendicularly to the longitudinal direction of the feed bars, and the carts 11 and 11 are movably provided on the guide 12 by means of rollers 13 and 13. The guide 12 is secured to the unit casing 9 and the feed bar receptacles 10 and 10 are protruding upward therefrom. A feed screw rod 14 comprising a ball thread parallel to the guide 12 (or perpendicular to the feed bars) is thread­ edly fitted with the carts 11 and 11 and is mounted in the unit casing 9 with one end protruding therefrom. The feed screw rod 14 is formed with left-hand and right-hand screw portions, 14a and 14b, which are engaged with the carts 11 and 11 respectively and are threaded in different directions from each other. With rotation of the feed screw rod 14, the cart 11 and 11 with the feed bars 7 and 7 thereon move toward and away from each other, thereby causing the feed bars to perform clamping and unclamping movement. Further, the carts 11 and 11 are provided with a spline rod 15 parallel to the feed screw rod 14, and when this spline rod 15 rotates, the feed bar receptacles 10 and 10 move up and down causing the feed bars to perform lifting and lowering movement. Press machine wherein the feed bars perform only two-dimensional clamping and unclamping movement will not need the spline rod and attachments therefor which serve to lift and lower the feed bars. The feed screw rod 14 and the spline rod 15 are respectively provided with helical or worm gears 30 and 31 at one end protruding from the unit casing 9. The worm gears 30 and 31 are respectively engaged with worms 32a and 32b of vertical screw rods 32 and 33. The upper ends of the vertical screw rods 32 and 33 are respectively connected via ball joints 34 and 35 to vertical rods 36 and 37. The vertical rods 36 and 37 are adapted to move up and down in association with the press drive system. The lower ends of the vertical screw rods 32 and 33 are respectively provided with clamp cylinders 38 and 39 which allow adjustment of the internal width between the feed bars. The internal construction of the clamp cylinders 38 and 39 is identical and therefore it will be described with reference to only one clamp cylinder. The vertical screw rod 32 is connected to a piston 40 housed in the clamp cylinder 38 and is formed with a spline 32b at a portion above said piston 40. The clamp cylinder 38 has therein a worm wheel 41 which is engaged with the spline 32b. The worm wheel 41 is also engaged with a worm rod 42 connected to a drive shaft of an adjustment motor 43 protruding from the clamp cylinder. Referring particularly to Fig. 2B, the feed screw rod 14 is threadedly fitted with ball-filled nut members 16 and 16 and these nut members are united with and held by the carts 11 and 11, respectively. The feed bars 7 and 7 are respectively slidably supported by the feed bar receptacles 10 and 10, each united with vertically extending rack member 17 and plunger member 18, and these members 17 and 18 are inserted in the cart 11 and 11 in a vertically slidable manner, respectively. Air is supplied to cylinders 19 and 19 of the carts 11 and 11 where the plungers 18 and 18 are inserted, and this air pressure acts upon the plungers 18 and 18 so as to balance the weights of the feed bars 7 and 7 and the feed bar receptacles 10 and 10. The spline rod 15 is inserted in and slidably engaged with pinions 20 and 20 mounted rotatable in the carts 11 and 11. The pinions 20 and 20 are respectively engaged with the rack members 17 and 17, and these rack members 17 and 17 are so constructed to move up and down when the pinions 20 and 20 rotate back and forward, or in the alternatingly different directions, through the back-and-forward rotation of the spline rod 15. As the vertical rod 36 is moved up and down by the press operation, the feed screw rod 14 rotates together with the worm mechanism 32a and 30 actuated in association with the vertical rod 36. Accompanied therewith, the carts 11 and 11 each equipped with the nut member 16 move in the opposite directions to each other and the feed bars 7 and 7 clamp and unclamp while being supported by the feed bar receptacles 10 and 10 each moving in the horizontal direction together with the cart 11. The vertical rod 37 for driving the spline rod 15 serves to cause the feed bars to perform three-dimensional movement, and therefore it is rotated together with the press only when such three-dimensional movement is desired. The rotation of the spline rod 15 causes the pinions 20 and 20 to rotate and the rack members 17 and 17 to move up and down, whereby the feed bar receptacles 10 and 10 move up and down and the feed bars 7 and 7 perform lifting and lowering move­ ment. Next, adjustment of the feed bar clamp and lift strokes will be described with reference to Figs. 6 and 7. If the press has fixed clamp and lift strokes, this adjustment mechanism will be unnecessary. The upper ends of the vertical rods 36 and 37 for driving the feed screw rod and the spline rod reach the crown 2, and levers 50 and 50 are respectively mounted by axes 51 and 51 in proximity of the upper ends of the vertical rods 36 and 37. A crankshaft 52 is mounted to the crown 2 and provided with gear 53, which is engaged with gears 55 and 55 on cam shafts 54 and 54. Each of the cam shafts 54 is pro­ vided with a cam 56 that is in contact with a cam follower 57 of said lever 50. The right-hand cam 56 is for clamping and unclamping the feed bars and the left-hand cam 56 is for lifting and lowering them. As these cams have an identical stroke-adjusting mechanism, although different in shape, the adjusting mechanism is illustrated in detail with reference to only one cam. Fulcrum members 58 and 58 are respectively provided in a mid portion of the levers 50 and 50 and connected to links 59 and 59 by pins 60 and 60. The links 59 and 59 are mounted rotatable to the crown by supporting axes 61 and 61, respectively. The levers 50 and 50 are respectively formed with arcuate longitudinal openings 62 and 62 defined around the supporting axes of the links 59 and 59. The levers 50 and 50 and the links 59 and 59 are connected together by the fulcrum members 58 and 58 slidable in the longitudinal openings 62 and 62, respectively. Further, the links 59 and 59 respectively have the lower end protruding from the levers 50 and 50 and are connected to adjusting rods 64 and 64 of adjusting units 63 and 63 at the free end thereof. The adjusting unit 63 is secured to the crown 2 by means of a mounting member 65 and is provided with a motor 66 having a drive shaft. This drive shaft is provided with a pinion 67 and a drive gear 68 engaged therewith and prevented from its axial movement. The end of the adjusting rod 64 is formed as a screw rod 64a, which is threadedly fitted with the drive gear 68. When the pinion 67 is rotated by the drive from the motor 66, the pinion 67 rotates the drive gear 68 and then the adjusting rod 64 reciprocates in the axial direction, thereby allowing the link 59 to swing about the supporting axis 61 with the fulcrum member 58 sliding along the longi­ tudinal opening 62. The clamp cylinders 38 and 39 are respectively pro­ vided at the lower ends of the vertical rods 36 and 37, as shown in Fig. 2A, ensuring contact between the corresponding cam follower 57 and the cam 56. On the other hand, the upper ends of the vertical rods are respectively connected to adjustment cylinders 70 and 70 each for separating the cam 56 from the lever 50 and moving only the vertical rod up and down. With rotation of the cams 56 and 56, the levers 50 and 50 respectively swing about the fulcrum members 58 and 58 together with the cam followers 57 and 57, moving the vertical rods 36 and 37 up and down, whereby the feed bars 7 and 7 perform both clamping and unclamping movement and lifting and lowering movement. The feed bar lift and clamp strokes can be changed by changing the length of the up-and-down stroke of the vertical rods 36 and 37, which length is changeable by changing the positions of the fulcrum members 58 and 58 of the levers 50 and 50. In order to change the positions of the fulcrum members 58 and 58, the motors 66 and 66 of the adjusting units 63 and 63 are driven to reciprocate the adjusting rods 64 and 64 and rotate the links 59 and 59, respectively. The longitudinal openings 62 and 62, each in the lever 50, correspond to the locuses of the pins when the links 59 and 59 rotate, respectively, so that there will be no change in the position which the end of the lever 50 at connection with the rod takes when the lever 50 is located at either limit of the swinging motion. Namely, the length of the feed bar stroke can be adjusted with a fixed down end for lift stroke adjustment and with a fixed clamp end for clamp stroke adjustment. Figs. 8 to 11 show other embodiments of the feed bar clamping and unclamping apparatus. In the casing 9 for the unit for clamping and unclamp­ ing the feed bars 7 and 7, there are provided two horizontal feed screw rods 100 and 101, the feed screw rod 101 protruding from the casing 9 and connected to a drive unit, not shown. The casing 9 has therein a spline rod 102 parallel to the feed screw rods 100 and 101, and this spline rod 102 is protruding from the casing 9 in the opposite direction to the feed screw rod 101 and connected to a drive unit, not shown. Each of the feed screw rods 100 and 101 mounted to the unit casing 9 is a right-handed screw comprising ball thread. The feed screw rods 100 and 101 are respectively threadedly fitted with ball-filled nut members 103 and 103, and these nut members are respectively united with and held by carts 104 and 104. On the inner wall surface of the unit casing 9, are mounted guide rails 105 and 105 each extending in the axial direction of the feed screw rod (or perpendicularly to the longitudinal direction of the feed bars) and the carts 104 and 104, each provided with rollers 106 in rotatable engagement with the guide rail 105, are adapted to move along on said guide rails. The feed bars 7 and 7 are respectively supported by the feed bar receptacles 110 and 110 on the carts 104 and 104 in a slidable manner. The carts 104 and 104 are respectively united with vertically extending rack members 107 and 107 and plunger members 108 and 108, and these members 107, 107, 108 and 108 are respectively inserted in the carts 104 and 104 in a vertically slidable manner. Air is supplied to cylinders 109 and 109 of the carts 104 and 104 where the plungers 108 and 108 are inserted, and this air pressure acts upon the plungers 108 and 108 so as to balance the weights of the feed bars 7 and 7 and the feed bar receptacles 110 and 110. The spline rod 102 is inserted in and slidably engaged with pinions 111 and 111 mounted rotatable in the carts 104 and 104. As shown in Fig. 9, the pinions 111 and 111 are respectively engaged with the rack members 107 and 107, and these members are so constructed to move up and down when the pinions 111 and 111 rotate back and forward via the back-and-forward rotation of the spline rod 102. The two feed screw rods 100 and 101 are supported by the unit casing 9 and interconnected,on a support 112 provided at the center of the casing 9, by a reversion device 113 for reversing the rotational direction. This reversion device 113 transmits drive from the feed screw rod 101 to the other 100 and at the same time reverses the rotation of these feed screw rods. Fig. 10 is a view explaining the construction of the reversion device 113 comprising a group of gears. The feed screw rods 100 and 101 respectively have spur gears 114 and 115 at the end thereof. These spur gears 114 and 115 are interconnected by spur gears 118, 119, 120 and 121 provided on intermediate rods 114 and 115, whereby the rota­ tion of the feed screw rod 101 is reversed and tranmitted to the other feed screw rod 100. When the feed screw rod 100 rotates in association with the press operation, the feed screw rods 100 and 101 with the reversion device therebetween rotates in the opposite directions. Accompanied therewith, the carts 104 and 104 each with the nut member 103 move in the opposite directions and the feed bars 7 and 7 clamp and unclamp while respectively supported by the feed bar receptacle 110 moving integrally with the cart 104 in the horizontal direction. The spline rod 102 is used to cause the feed bars to perform three-dimensional movement, and therefore it may be rotated with the press when such movement is desired. With rotation of the spline rod 102, the pinions 111 and 111 rotate and the rack members 107 and 107 and the feed bar receptacles 110 and 110 move up and down, thereby lifting and lowering the feed bars 7 and 7. Fig. 11 shows another embodiment of the reversion device 130 for rotating the feed screw rods in the opposite direction to each other. The feed screw rods 100 and 101 are respectively provided at the face-to-face end thereof with a first bevel gear 131 and a second bevel gear 132, and a third bevel gear 133 is interposed therebetween. The third bevel gear 133 is mounted at the end of a drive shaft 134 adapted to rotate in association with the press crankshaft. Accordingly, when the drive shaft 134 rotates back and forward and transmits its rotation through the third bevel gear 133 and then the first and second bevel gears 131 and 132 to the feed screw rods 100 and 101, these feed screw rods rotate in the opposite direction to each other in the similar manner with Fig. 8 embodiment. It is to be noted that in Fig. 11 embodiment the member 134 need not be a drive shaft but it may be just an intermediate rod, in which case the same effect is obtainable by transmitting drive to either of the feed screw rods in the same manner with Fig. 8 embodiment. Further, it is also to be noted that the rotational reversion of the feed screw rods is attainable if either of the intermediate rods 116 and 117 is adapted to work as a drive shaft in the same manner with Fig. 11 embodiment.

Claims: 1. A feed bar driving apparatus for a transfer press comprising: two screw rods each connected via a ball joint to a vertical rod reciprocating in association with press drive system; a feed screw means connected to said screw rods and adapted to rotate by rotation and reciprocation thereof; a drive means for rotating said screw rods; a pair of feed bar receptacles slidably supporting feed bars and connected to said feed screw means, said feed bar receptacles clamping and unclamping the feed bars with rotation of said feed screw means; a cam adapted to rotate in association with the press drive system; a lever connected to the vertical rod and disposed in contact with said cam, for reciprocating said vertical rod; and a stroke adjusting mechanism having a means for changing the fulcrum position of said lever, wherein said adjusting mechanism is selectively used when the change of the feed bar stroke is desired. 2. A driving apparatus as claimed in claim 1 wherein said feed bar receptacles have a spline rod mounted thereto in parallel with said feed screw means so that the feed bars may perform three-dimensional lifting and lowering movement. 3. A driving apparatus as claimed in claim 1 wherein said feed screw means comprises one rod having left and right screw portions which are engaged with said pair of feed bar receptacles and threaded in different directions to each other. 4. A driving apparatus as claimed in claim 1 wherein said feed screw means comprises two rods each in engagement with said feed bar of the pair, said feed screw means being threaded in the same direction and interconnected by a reversion device for reversing the rotation of said feed screw means. 5. A driving apparatus as claimed in claim 4 wherein said reversion device comprises a plurality of spur gears. 6. A driving apparatus as claimed in claim 4 wherein said reversion device comprises a first and second bevel gears respectively provided at the face-to-face end of the two feed screw means, and a third bevel gear interposed between the first and second bevel bears. 7. A driving apparatus as claimed in claim 1 wherein said feed screw means is mounted to a unit casing and provided with a helical or worm gear at the portion thereof protruding from the unit casing, said helical or worm gear being engaged with a worm provided on said screw rod. 8. A driving apparatus as claimed in claim 1 wherein said feed screw means consists of a ball thread and is engaged with nut members of the feed bar receptacles. 9. A driving apparatus as claimed in claim wherein each of said screw rods is received in a clamp cylinder and formed with a spline, said spline being in engagement with a worm wheel adapted to rotate by a motor. 10. A driving apparatus as claimed in claim 1 wherein each of said feed bar receptacles slidably holds the feed bar and has vertically extending rack member and plunger, said plunger being housed in an air cylinder and said rack member being engaged with a pinion in engagement with said spline rod. 11. A driving apparatus as claimed in claim 1 wherein a fulcrum member is provided in a mid portion of said lever and connected to a link that is mounted to the press by a supporting axis, said lever being slidably mounted in an arcuate longitudinal opening defined around said supporting axis of the link so that the fulcrum position of the lever can be changed by moving the free end of said link. 12. A driving apparatus as claimed in claim 1 wherein said stroke adjusting mechanism has an adjusting rod and a motor having a drive shaft, said drive shaft being provided with a pinion and a drive gear engaged therewith and prevented from its axial movement, and said adjusting rod being formed as a screw rod at one end thereof and connected to the free end of said link. 13. A driving apparatus as claimed in claim 1 wherein said cam, lever and adjusting mechanism for adjusting the feed bar stroke are provided in a pair on the left and right of the press so that both advance-and-return stroke and up-and-down stroke are adjustable.

Inventors: ARAI, TOSHIHIKO, HASHIMOTO, MASAKAZU, HASHIMOTO, YOSHIYUKI, IMANISHI, SHOZO, KATO, YOSHINORI, KUSUNOKI, MASAHURU, ODAKA, TADAO
Applicants: AIDA ENGINEERING, LTD.
Application year: 1986
Main classification: B21D43
IPC codes: B21D43, B30B1, B30B15