INDEXABLE PUNCH AND DIE HOLDER FOR TURRET PUNCHES

Abstract: A punch press having multiple punch tool rotatable turrets wherein at least one of the punch tools l6 on each of upper l4 and lower 24 turrets is indexable to different angular orientations. Rotation of the indexable punch tools is accomplished by a slidably mounted motor l8 for engagement with a timing pulley 32 which, through a timing belt 30 and a harmonic gear drive 92, acts to rotate the punch tools. Position sensors l04 and a brake l58 are also provided.

Description: The present invention relates generally to a turret punch press having a pair of upper and lower turrets rotatably mounted to automatically bring respective punch and dies into alignment for punching a variety of holes in sheet materials and, more particularly, to an apparatus for rotating the punch and die in the respective upper and lower turrets for punching holes in a variety of orientations. It is known to provide rotatable punching tools in a turret punch press wherein the upper and lower punching tools are rotated synchronously for different orientations of the punch tools. Hirata et al, us-A-4,412,469 discloses an indexable punch press apparatus according to the pre-characterising part of claim 1 having upper and lower turrets for selective rotation on a punch press housing and including a plurality of corresponding punch tools. The apparatus comprises an indexable punch mounted for rotation in the upper turret, a first motor, first linkage means for transmitting rotation of the first motor to the punch, an indexable die mounted for rotation in the lower turret, a second motor and second linkage means for transmitting rotation of the second motor to the die. The rotation of the tools is provided by servo motors mounted on brackets on the respective upper and lower portions of the punch press. The linkage means comprise an extensive series of transmitting elements for transmitting the rotational motion of the motor to the punch tool, including a gear pair linking the drive shaft of the motor to a pulley, which operates through a belt to drive a pulley on a clutch and brake mechanism, which in turn operates through another pulley and a second belt to drive an idler pulley mounted on the turret, which through yet another pulley and a third belt drives a pulley encircling a holding member in which the punch tool is mounted. The clutch and brake mechanism provides a connectable linkage between the servo motors and the tools and includes a pneumatic or hydraulic motor to move a plurality of push rods in an upper portion of the clutch and brake mechanism which engage a respective plurality of bores in a lower portion of the clutch and brake mechanism. An annular friction plate restricts rotation of the lower portion when the push rods are disengaged. Magnets and sensing means are provided to detect the position of the idler pulley. It would be an improvement over the prior art to reduce the number of linkages between an indexable punch tool and a motor thereby increasing the accuracy and efficiency of the punch indexing mechanism. It would also be an improvement to provide a simpler, more reliable brake mechanism. It is an object of the present invention to provide a highly accurate and reliable indexable punch and die on a rotatable turret punch press. This and other objects of the present invention are embodied in indexable punch press apparatus according to the pre-characterising part of claim 1 with said first motor being slidably mounted on said punch press housing and selectively slidable between a first and a second position, said first linkage means being provided for transmitting rotation of said first motor to said indexable punch when said first motor is in said second position, said first linkage means, being disconnected to prevent the transmission of rotation by said first motor to said indexable punch when said first motor is in said first position, said second motor being slidably mounted on said punch press housing and being selectively slidable between a first and second position, said second linkage means being provided for transmitting rotation of said second motor to said indexable die when said second motor is in said second position, said second linkage means being disconnected to prevent the transmission of rotation by said second motor to said indexable die when said second motor is in said first position, and the upper and lower turrets being rotatable when said respective first and second motors are in said respective first positions. Since an improperly oriented punch tool can severely damage punch pressing equipment, it is of critical importance that an indexable punch press be extremely accurate with little room for error. The present device has this accuracy. A resolver monitors the rotation of the motor, while a toothed timing belt provides a positive drive from the motor to a harmonic drive unit. The harmonic drive provides an efficient yet accurate speed reduction for higher torque and better rotational accuracy. The output of the harmonic drive is geared directly to a rotatable hushing of a punch tool in a manner to prevent backlash. Sensors are provided to establish the turret position with respect to the indexable punch stations, as well as to establish home positions for the indexable punch tools. ON THE DRAWINGS Fig. 1 is a perspective view of an upper turret portion of a device according to a preferred embodiment of the present invention. Fig. 2 is an enlarged side elevational view of the device shown partially cut away. Fig. 3 is a plan view of the device shown in Fig. 2 generally at lines III-III. Fig. 4 is a plan view of the device shown in Fig. 2 along lines IV-IV. Fig. 5 is a cross-section of the device shown in Figs. 3 and 4 along lines V-V. Fig. 6 is an enlarged side elevational view of the device of the present invention. Fig. 7 is a top plan view of the device as shown in Fig. 6 along lines VII-VII. Referring to Fig. l, an embodiment of the device of the present invention is shown generally at l0 and includes a punch press housing l2, a rotatable turret l4, at least one indexable punching tool l6, and a punching tool drive motor l8. More specifically, a ram 20 is disposed in the punch press housing l2 for driving a punch P through a piece of sheet material M into a die D. A plurality of punches P and dies D are mounted adjacent the perimeter of respective upper and lower turrets l4 and 24 which are rotatable to bring corresponding punches P and dies D under the ram 20. At least one indexable punch tool l6 is mounted within the rotatable upper turret l4 and a corresponding indexable die 22 is mounted in the lower turret 24 so that the indexable punch l6 and die 22 may be brought into registration under the ram 20. The indexable punch l6 is provided with a geared bushing 26 that is rotatably driven by a harmonic drive gear box 28 which in turn is driven by timing belt 30 connecting a pair of pulleys 32 and 34. The servo motor l8 is mounted on the punch press housing l2 by a vertical slide 36 and is selectively engagable to the drive pulley 32. Vertical movement of the servo motor l8 in the slide 36 is provided by an actuator 38 such as a pneumatic actuator, connected between the motor slide 36 and the punch press housing l2. The servo motor l8 may be locked into its respective upper and lower positions by a slide lock mechanism 40. A resolver 4l provides feedback from the motor l8 to a programmed controller (not shown) to monitor the angular rotation of the motor l8. Fig. 2 shows the motor l8 slideably mounted on the housing l2. The pneumatic actuator 38 is connected at an upper end thereof to the punch press housing l2 by a bracket 42. An extendable arm 44 of the actuator 38 is connected by a clevis 45 to a slide plate 46 on which the motor l8 is mounted. The slide plate 46 slides vertically within slide rails 48 and 50 so that the motor l8 may be selectively engaged with the driver pulley 32. Coupling between the motor l8 and the driver pulley 32 is accomplished by a coupling 52, such as a helical single flex coupling. The helical coupling is connected at one end thereof to a shaft 54 of the motor l8 and at the other end thereof to a shaft and tang arrangement 56 which engages a shaped opening 58 in the drive pulley 32, as will be described more fully in conjunction with Figs. 6 and 7. The helical coupling 52, such as a coupling made by Helical Company, includes a helical spring (not shown) that provides relatively rigid torsional connection between the shaft 54 and the tang and shaft assembly 56, yet which gives relatively easily in a vertical direction so that misalignment of the motor l8 with the drive pulley 32 is accommodated while still transmitting the torque of the motor l8. The slide plate 46, and the motor l8 mounted thereto, may be locked in either the coupled and uncoupled positions by a motor slide lock 40 mounted on the punch press housing l2. The motor slide lock 40 includes a shot pin 60 which is selectively insertable into a bracket 62 mounted on the slide plate 46. The bracket 62 includes first and second openings 64 and 66 through which the shot pin 60 is inserted to lock the slide plate 46 and motor l8 into the respective coupled and uncoupled positions. Movement of the shot pin 60 is controlled by an actuator 67, such as a pneumatic actuator. An adjustable mechanical stop 68 is provided on the slide 36 in the form of a vertically disposed bolt 70 extending through an arm 72 on the slide plate 46. The bolt 70 abuts a flange 74 extending from the punch press housing l2 when the motor l8 and slide plate 46 are in the engaged position. A lock nut 76 is provided on the bolt 70 to lock the bolt 70 into position. The stop 68 prevents excessive vertical loading on the coupling 52. When the motor l8 is in the coupled position, the helical coupling 52 provides torsional coupling between the motor shaft 54 and the drive pulley 32. The drive pulley 32 is fixed to a pulley shaft 78 which is mounted for rotation about a vertical axis by bearings 80 within a bearing housing 82. The bearing housing 82 is fastened to the turret l4. The toothed timing belt 30 extends between the drive pulley 32 and the second pulley 34. Each of the pulleys 32 and 34 are toothed, corresponding to the teeth on the inner surface of the timing belt 30, thereby providing positive rotational drive between the pulleys 32 and 34. The second pulley 34 drives the harmonic gear drive 28, which will be described in more detail in conjuction with Fig. 5. The harmonic gear drive 28 drives a geared bushing 26 on the indexable punch l6 to provide rotation thereof. The indexable punch l6 is provided with an annular lifter ring 88 extending therearound which is connected to lifter springs 90 extending from the turret l4 to the lifter ring 88. The ram 20 is shown above the punch l6 and during operation will drive the punch l6 through a piece of sheet material M and into the die 22. The lifter ring 88, in conjunction with the springs 90, then returns the punch l6 to its original position, removing it from the sheet material M. A portion of the lower turret 24 is also shown in Fig. 2. It includes an indexable die 22 which is rotated by a harmonic gear drive 92 which in turn is driven by a timing belt 99 that is driven by a vertically slideable motor (not shown) slideably mounted on the punch press housing l2 below the lower turret 24. The motor is coupled to a drive pulley 96 by a helical coupling 98. The harmonic drive 92 extends into the lower turret 24 and includes an output gear l00 engaging a geared bushing l02 encircling the die 22. An anvil portion of the punch press 10 can be seen engaging the lower portion of the die 22 to resist the downward force of the ram 20 as it pushes the punch l6 through the sheet material M and into the die 22. A proximity switch l04, such as a magnetic reed switch, is mounted to the housing l2 and senses a target l06 on the turret l4 to indicate that an indexable station is positioned below the ram 20. Once the turret is positioned under the ram 20, a home position of the indexable punch l6 is established by a second proximity switch (not shown) mounted on the housing l2. A vane (not shown) extends from the punch bushing 26 to contact the proximity switch when the bushing 26 and the punch l6 are rotated to home position. A similar target and switch (not shown) indicate when the lower turret 24 is at an indexable station. A target on the bushing of the die 22 is selectively sensed by a frame mounted switch (not shown). To prevent damage to the frame mounted switch it is preferably mounted on a pneumatic cylinder so that it may be moved toward the die 22 to sense the target and then move away before operation of the ram 20. Fig. 3 shows the upper turret l4 from above including a plurality of punches P. The slide plate 46 is mounted between the V-shaped slide rails 48 and 50. The pneumatic actuator 38 is seen suspended from the bracket 42 and the slide lock 40 and the arm 72 of the mechanical stop 68 can be seen more clearly. The timing belt 30 extends from the drive pulley 32 to the second pulley 34 under the housing l2. The harmonic gear drive 28 is enclosed by a housing l08 having a shaped opening ll0 through which extends the geared bushing 26 of the indexable punch l6. The indexable punch l6 includes a T-shpaed punch portion ll2 for punching like shaped openings in sheet material M and is keyed to the geared bushing 26 by a key ll4. The turret l4 is rotatable about a turret axis ll6 to bring other punch tools P under the ram 20. Fig. 4 shows the lower turret 24 from above including the harmonic gear drive 92 and timing belt 94 in dotted outline. The indexable die 22 includes a T-shaped opening ll8 for registration with the T-shaped punch portion ll2 of the punch tool l6. Other die tool stations D are likewise shown at the periphery of the lower turret 24. Fig. 5 shows the harmonic gear drives 28 and 92 of the upper and lower turrets l4 and 24, respectively, in more detail. In the upper harmonic drive 28, the pulley 34 is secured to a shaft l20 extending through the harmonic drive housing l08 and mounted therein by bearings l22. A key l24 in the shaft l20 fixedly connects an oldham coupling l26 to a wave generator portion l28 of the harmonic drive 28. The wave generator portion l28 is geared to a flex spline l30 which is clamped to the housing l08 by a bolt l32 extending through an annular ring l34. The flex spline l30 is also geared to a circular spline l36 to which is bolted an output gear l38. The harmonic drive 28 provides a 6l to l gear reduction between the pulley 34 and the output gear l38 so that the rotational orientation of the output gear l38, and thus the punch l6, can be precisely determined while increasing the torque. The harmonic drive 28 can be repositioned somewhat to insure snug engagement of the output gear l38 with the geared bushing 26, thereby avoiding backlash. The lower turret 24 includes the harmonic drive 92 which provides a similar gear reduction. The lower harmonic drive 92 includes a shaft l40 secured to a pulley l42 which is connected by a key l44 to an oldham coupling l46, which in turn is linked to a wave generator l48. The wave generator l48 is geared to a flex spline l50 which in turn is geared to a circular spline l52. The circular spine l52 is bolted to a coupling l54 which connects it to the lower output gear l00. The lower output gear l00 drives the geared bushing l02 which rotates the indexable die 22. Since the lower harmonic drive 92 is partially within the lower turret 24, it is not adjustable as the upper harmonic drive 28 is. Therefore a split gear arrangement l56 is included on the lower output gear l00 to prevent backlash between the output gear l00 and the geared bushing l02. Fig. 6 shows a friction brake l58 for retaining the indexable punch l6 during rotation of the turret l4. The friction break l58 includes a pivotally mounted arm l60 connected to the bearing housing 82 by a pivot pin l62. It is held against the timing belt 30 by a compression spring l64 encircling a rod l66 extending from the bearing housing 82. The compression spring l64 is held on the rod l66 by a washer l68 and lock nuts l70 threadably received on the rod l66. The arm l60 of the friction brake l58 is released from the belt 30 (as shown in dotted outline) by an adjustable abutting member l72 extending downward from the motor slide 46. The adjustable member l72 includes a bolt l74 and a lock nut l76 by which it may be adjusted. Fig. 7 shows the arm l60 of the brake l58 and the shaped opening 58 which receives the tang and shaft assembly 56 of the helical coupling 52 when the motor slide 36 is moved to the engaged position. The present device operates as follows: Both the upper and lower turrets l4 and 24 are rotated until the indexable punch and die l6 and 22 are beneath the ram 20. The actuator 38 moves the motor slide 36 downward until the tang and shaft assembly 56 engages the shaped opening 58 in the drive pulley 34. The shot pin 60 locks the slide plate 46 in place by engaging the opening 64 in the bracket 62. The lowering of the motor slide 36 has released the brake l58 from the drive pulley 32 which enables the motor l8 to rotate the pulley 32. The timing belt 30 and harmonic drive 28 enable the motor l8 to rotate the punch l6 to a desired angular orientation as measured by the resolver 4l. During this time, a lower motor and slide is coupling with the lower drive pulley l42 and rotating the die 22 to an identical angular orientation. A piece of sheet material M is inserted between the punch and die l6 and 22 and the ram 22 forces the punch l6 therethrough the material M and into the die 22, after which the lifter ring 88 removes the punch l6 from the material M and the punched material is removed from the device l0. The motors then operate to return the punch and die l6 and 22 to a predetermined home position, as established by the proximity sensors, the motor slide 36 is raised to a disengged position and locked into place, and the turrets l4 and 24 are rotated to another punch tool position which may be either an indexable or a non-indexable position. Thus there has been shown and described an indexable turret punch press having a reduced number of linkage steps between the motor and the indexable punch tool, providing an exact correspondence between motor rotation and punch tool rotation. A simpler and more reliable brake mechanism is provided to maintain a known punch tool orientation when the motor is disengaged.

Claims: An indexable punch press apparatus having upper and lower turrets (14, 24) for selective rotation on a punch press housing (12) and including a plurality of corresponding punch tools and an indexable punch (16) mounted for rotation in the upper turret (14), the apparatus comprising a first motor (18), first linkage means (26, 28, 30, 32, 34) for transmitting rotation of said first motor (18) to said indexable punch (16), an indexable die (22) mounted for rotation in said lower turret (24), a second motor, second linkage means (92, 94, 96, 100, 102) for transmitting rotation of said second motor to said indexable die, characterised by said first motor (18) being slidably mounted on said punch press housing (12) and selectively slidable between a first and a second position, said first linkage means (26, 28, 30, 32, 34) being provided for transmitting rotation of said first motor (18) to said indexable punch (16) when said first motor (18) is in said second position, said first linkage (26, 28, 30, 32, 34) means, being disconnected to prevent the transmission of rotation by said first motor (18) to said indexable punch (16) when said first motor (18) is in said first position, said second motor being slidably mounted on said punch press housing (12) and being selectively slidable between a first and second position, said second linkage means (92, 94, 96, 100, 102) being provided for transmitting rotation of said second motor to said indexable die (22) when said second motor is in said second position, said second linkage means (92, 94, 96, 100, 102) being disconnected to prevent the transmission of rotation by said second motor to said indexable die when said second motor is in said first position, and the upper and lower turrets (14, 24) being rotatable when said respective first and second motors are in said respective first positions. An apparatus as claimed in claim 1, wherein said first linkage means (26, 28, 30, 32, 34) includes a first harmonic gear drive (28) and a first timing belt (30) and a first pulley pair (32, 34) mounted on the upper turret (14), and said second linkage means (92, 94, 96, 100, 102) includes a second harmonic gear drive (92) and a second timing belt (94) and a second pulley pair (96) mounted on the lower turret (24). An apparatus as claimed in claim 2, including first coupling means (56, 58) for selectively linking said first motor (18) to one of said first pulley pair (32, 34), and second coupling means for selectively linking said second motor to one of said second pulley pair (96). An apparatus as claimed in claim 2 or 3, including a first geared bushing (26) encircling said indexable punch (16) and engaging said first harmonic gear drive (28), and a second geared bushing (102) encircling said indexable die (22) and engaging said second harmonic gear drive (92). An apparatus as claimed in any preceding claim, including first and second locking means (40), for selectively locking said respective first and second motors (18) in at least one of said first and second positions. An apparatus as claimed in any preceding claim, including first and second sensing means (104) for detecting home positions of respective ones of said indexable punch (16) and said indexable die (22). An apparatus as claimed in any preceding claim, including first and second actuators (38) extending between the punch press housing (12) and respective ones of said first and second motors (18) and being operable to slide said first and second motors (18) between first and second positions respectively. An apparatus as claimed in any receding claim, including first and second brake means (158) for selectively rendering said first and second linkage means immovable.

Inventors: HILL, RONALD C., LUX, ARTHUR J., SHAH, HARSHAD M.
Applicants: STRIPPIT, INC.
Application year: 1986
Main classification: B21D37
IPC codes: B21D28