Patent Publication Number: US-6216523-B1

Title: Servo-drive for press transfer

Description:
BACKGROUND OF THE INVENTION 
     1) Technical Field 
     This invention relates generally to assemblies used to transfer workpieces through a machine having a reciprocating member. More specifically the invention is related to an assembly which engages the workpieces to move them progressively from one die station to another so that a plurality of sequential operations may be performed on them. 
     2) Description of the Prior Art 
     Workpiece transfer assemblies for use in progressive die type punch presses are well known in the art. Transfer assemblies typically derive motion from a ram press which interacts with a combination of cams for moving rotating members in a desired pattern. An example of such a transfer assembly is U.S. Pat. No. 4,833,908 to Sofy, the named inventor of the subject invention. 
     Increasingly, manufacturing quality standards have required more precise manufacturing processes. To achieve more precision, electronic and computer process control systems have been introduced into the manufacturing environment. A need for this type of control exists in transfer press operations. More specifically, electronic control over a transfer assembly would enhance the die forming process and improve quality by providing improved process control and fault notification. 
     SUMMARY OF THE INVENTION AND ADVANTAGES 
     A workpiece transfer assembly for a press of the type including a reciprocating member and a series of in-line stations wherein each station is a further progression of the workpiece forming process includes a workpiece engaging jaw having clasps attached thereto for clasping the workpieces. A lateral motion mechanism moves the jaw in a horizontal direction and laterally relative to the work stations into and out of workpiece engagement position. A vertical motion mechanism moves the jaw in a vertical direction relative to the workstations. A linear motion mechanism moves the jaw in a horizontal direction and linearly relative to the work stations. The assembly includes a reciprocal horizontal motor for actuating the lateral motion mechanism, a reciprocal vertical motor for actuating the vertical motion mechanism, a linear motor for actuating the linear motion mechanism, and a controller for programming the motors through a programmed actuation process. 
     The subject invention provides the precise workpiece transfer motions and the electronic control over the transfer operation that is essential to meet contemporary process control standards. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
     FIG. 1 is a perspective view of the subject invention; 
     FIG. 2 is a perspective view of one of the reciprocating members of the subject invention; 
     FIG. 3 is a front sectional view of the subject invention showing a horizontal motion mechanism in an upper work piece engagement position; 
     FIG. 4 is a front sectional view of the subject invention showing a horizontal motion mechanism in a lower workpiece engagement position; 
     FIG. 5 is a rear sectional view of the subject invention showing a vertical motion mechanism in a lower workpiece engagement position; 
     FIG. 6 is a rear sectional view of the subject invention showing a vertical motion mechanism in an upper workpiece engagement position; 
     FIG. 7 is a top sectional view of the subject invention showing a lateral motion mechanism; 
     FIG. 8 is a top sectional view showing a horizontal motion mechanism; and 
     FIG. 9 is a side sectional view of the subject invention showing a lateral motion mechanism. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a workpiece transfer assembly for a press is generally shown at  10  including a reciprocating member and a series of in-line stations wherein each station is a further progression of the workpiece forming process. For convenience, a plurality of workpieces W are shown in FIG.  1 . 
     The assembly  10  includes a workpiece engaging jaw  12  having clasps  14  attached thereto for clasping the workpieces W. A plurality of clasps  14 , each corresponding to a workpiece W in a die station, are mounted on the jaw  12  and engage the workpieces W when the jaw  12  is in workpiece W engagement position as will be described further hereinbelow. 
     A lateral motion mechanism  16  moves the jaw  12  in a horizontal direction and laterally relative to the work stations into and out of workpiece W engagement position. The lateral motion mechanism  16  includes lateral motion arms  18  affixed at distal ends to a lateral motion bar  20  for transferring lateral motion to the lateral motion bar  20 . The assembly  10  includes opposed lateral motion bars  20  for moving the jaw  12  laterally into and out of workpiece engagement position as a motion cycle may dictate. 
     A vertical motion mechanism  22  moves the jaw  12  in a vertical direction relative to the workstations. The vertical motion mechanism  22  includes vertical motion arms  24  affixed at distal ends to a vertical motion bar  26  for transferring motion to the vertical motion bar  26 . The assembly  10  includes opposed vertical motion bars  26  for moving the jaw  12  in a vertical direction once the jaw  12  is in workpiece engagement position. 
     A motion transmitting mechanism  28  is disposed between the jaw  12  and the lateral motion mechanism  16  for providing positive horizontal motion transmission to the jaw  12  and for providing lost motion transmission in the vertical direction. The motion transmitting mechanism  28  allows the jaw  12  to be raised and lowered relative to the work stations while the lateral motion mechanism  16  remains in the workpiece engaging position. 
     For example, the motion transmitting mechanism  28  includes an horizontal linkage  30  extending between the jaw  12  and the lateral motion bar  20  for transferring lateral motion to the jaw  12  from the lateral motion bar  20 . The horizontal linkage  30  preferably comprises an elongated tubular member having a constant circular cross section therealong. 
     The motion transmitting mechanism  28  also includes a vertical linkage  32  which extends between the vertical motion bar  26  and the horizontal linkage  30 . The vertical linkage  32  transfers vertical motion to the jaw  12  from the vertical motion bar  26 . That is to say, as the vertical motion bar  26  actuates, it moves the vertical linkage  32  between a raised and a lowered position which in turn moves the horizontal linkage  30  translating horizontal motion to the jaw  12 . This is best represented in FIGS. 2 through 6. Preferably, the vertical linkage  32  comprises an elongated tubular member having a constant circular cross section therealong. 
     The motion transmitting mechanism  28  includes a plate  34  having a vertically elongated slot  36  disposed therein for transmitting positive horizontal motion in response to force applied horizontally to the slot  36  from the lateral motion bar  20 , and for providing lost vertical motion within the slot  36  to the lateral motion bar  20  in response to force applied vertically from the vertical motion bar  26 . The plate  34  is disposed on the outermost end to the horizontal linkage  30 . The lateral motion bar  20  extends through the slot  36  so that during oscillation, the lateral motion bar  20  moves the horizontal linkage  30  in response to force applied to the inside surfaces of the slot  36 , thereby providing positive motion transmission. 
     The motion transmitting mechanism  28  includes a linear type bearing  38  interconnecting the horizontal linkage  30  and the vertical linkage  32  for allowing the horizontal linkage  30  to be moved relative to the vertical linkage  32 . The linear type bearing  38  is fixedly disposed on the vertical linkage  32 . The horizontal linkage  30  extends through the bearing  38  for providing guided horizontal motion to the horizontal linkage  30 . The linear type bearing  38  is rigidly positioned on the uppermost end of the vertical linkage  32 , and the tubular horizontal linkage  30  extends through the bearing  38  for allowing the horizontal linkage  30  to move into and out of the workpiece W engagement position relative to the vertical linkage  32 . 
     A linear motion mechanism  40  moves the jaw  12  in a horizontal direction and linearly relative to the work stations. The linear motion mechanism  40  includes a linear motion bar  42  affixed to a vertical type bearing  44  having the vertical linkage  32  slidably retained therein. As a result, the linear motion bar  42  translates linear motion to the jaw  12  independently of the vertical movement of the jaw  12  and does not move in a vertical direction. In operation, the linear motion bar  42  allows the motion transmitting mechanism  28  and the attached jaw  12  to move longitudinally relative to the work stations for indexing the workpieces to their respective next work stations. 
     The linear type bearing  38  includes at least one upper roller element  46  and at least one lower roller element  48  having the vertical motion bar  26  disposed therebetween for allowing unrestricted longitudinal movement of the vertical linkage  32  along the vertical motion bar  26 . The rollers  46 , 48  are oriented to roll in a linear direction along the vertical motion bar  26  and to translate vertical motion from the vertical motion bar  26  to the vertical linkage  32  and subsequently to the jaw  12 . 
     The assembly  10  is characterized by a reciprocal horizontal motor  50  for actuating the lateral motion mechanism  16 , a reciprocal vertical motor  52  for actuating the vertical motion mechanism  22 , and a linear motor  54  for actuating the linear motion mechanism  40 . A controller (not shown) communicates with the motors  50 , 52 , 54  for cycling the motors through a programmed actuation process. A computer terminal (not shown) is used to program the controller with an operation cycle corresponding to a desired work station operation. The controller relays the operation cycle to the motors  50 , 52 , 54  for the motors  50 , 52 , 54  to execute an articulating movement. The motors may comprise any suitable type such as mechanical, electric servo, pneumatic, or hydraulic. 
     The motors  50 , 52 , 54  each include a motor encoder  56  for signaling the controller with an actuation location of the motors  50 , 52 , 54 . The motor encoders  56  are affixed in a linear orientation to the motor&#39;s axle (not shown) for determining the rotation of motors&#39;s axle and relaying the rotation status to the controller. The vertical and the lateral motion mechanisms  16 , 22  each include a mechanism encoder  58  for signaling the controller with an actuation location of the mechanisms  16 , 22 . The mechanism encoders  58  are positioned at the pivot point of the vertical motion arm  24  and the lateral motion arm  18 . Thus, the mechanism encoders  58  determine the actuation position of the jaw  12  from the actuation position of the arms  18 , 24 . The controller includes a comparator (not shown) for comparing the output of the motor encoders  56  with the output of the mechanisms  16 , 22  from the mechanism encoders  58  for correcting any operation errors between the motors  50 , 52 , 54  and the mechanisms  16 , 22 . In addition, if the controller determines the motors  50 , 52 , 54  are out of alignment with the orientation of the motion arms  18 , 24 , the controller will relay an error signal to the terminal and terminate the assembly  10  operation. 
     The lateral reciprocal motors  54  includes a lateral drive shaft  60 , and the lateral motion mechanism  16  includes lateral input shafts  62 . The lateral drive shafts  60  can take the form of a gear or a wheel and are affixed to the motor axle for transmitting articulating motion. The lateral drive shafts  60  transfer articulating motion to the lateral input shafts  62 . The lateral input shafts  62  are affixed to the pivot point of the lateral motion arms  18  for translating articulating motion from the to the lateral motion arms  18 . 
     The reciprocal lateral motors  54  include belts  64  for transferring articulating motion from the lateral drive shafts  60  to the lateral input shafts  62 . The lateral shafts  60 , 62  include shaft teeth  66  and the belts  64  include belt teeth  68 , the shaft teeth  66  and the belt teeth  68  are in running engagement. The teeth  66 , 68  provide a non-slip engagement between the shafts  60 , 62  and the belts  64 . Other methods for achieving running engagement between the drive shafts and the input shafts are contemplated including chains and gears. 
     The reciprocal vertical motor  52  includes a vertical drive shaft  70 , and the vertical motion mechanism  22  includes vertical input shafts  72 . The vertical drive shafts  70  can take the form of a gear or a wheel and are affixed to the motor axle for transmitting articulating motion. The vertical drive shafts  70  transfer articulating motion to the vertical input shafts  72 . The vertical input shafts  72  are affixed to the pivot point of the vertical motion arms  24  for translating articulating motion from the vertical drive shafts  70  to the vertical motion arms  24 . 
     The reciprocal vertical motors  52  include belts  64  for transferring articulating motion from the vertical drive shafts  70  to the vertical input shafts  72 . The vertical shafts  70  include shaft teeth  66  and the belts  64  include belt teeth  68 , the shaft teeth  66  and the belt teeth  68  are in running engagement. The teeth  66  provide a non-slip engagement between the shafts  70 , 72  and the belt  64 . Other methods for achieving running engagement between the drive shafts and the input shafts are contemplated including chains and gears. 
     The linear motor  54  includes a pinion  74  and the linear motion mechanism  40  includes a rack  76 . The pinion  74  is in running engagement with the rack  76  for actuating the linear motion mechanism  40 . The linear motor  54  is affixed to a linear motion frame  78 . The linear motor  54  and the frame  78  move in a linear direction along the rack  76  as driven by the pinion  74 . The actuation of the linear motor  54  is regulated by the controller. Different work station configurations require different lengths of travel for the pinion  74  along the rack  76  and can be programmed into the controller. 
     The linear motion mechanism  40  includes a clutch  80 . The clutch  80  is in communication with the controller for disengaging the clutch  80  when an operation error in the linear direction is detected. The clutch  80  is affixed to the frame  78  and moves with the frame  78  along the rack  76 . The clutch  80  grasps the linear motion bar  42  for transferring linear motion to the jaw  12 . The clutch  80  signals the controller with faults in linear travel of the linear motion bar  42 . The controller will respond by disengaging the clutch  80  from the linear motion bar  42  for preventing damage to the assembly  10  from forcing linear movement during a fault condition. 
     It is frequently desirable to interconnect two motion transmitting mechanisms  16 , 22  on each flank of the assembly  10  for use in tandem during the workpiece W transfer operation. Therefore, in the preferred embodiment, the assembly  10  includes a horizontal coupling bar  82  and a vertical coupling bar  84  for connecting one motion transmitting mechanism  28  to another for allowing the two to operate in tandem during the workpiece transferring operation. The vertical coupling bar  84  attaches between the vertical linear type bearings  38 , and the horizontal coupling bar  82  attaches between the plates  34 . As will be appreciated, the jaw  12  also serves to interconnect two tandemly operating motion transmitting mechanisms  28 . 
     The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, wherein reference numerals are merely for convenience and are not to be in any way limiting, the invention may be practiced otherwise than as specifically described.