US2684855A

US2684855A - Work holding device

Info

Publication number: US2684855A
Application number: US112134A
Authority: US
Inventors: George F Wales; Paul H Taylor
Original assignee: WALES STRIPPIT CORP
Current assignee: WALES STRIPPIT CORP; WALES-STRIPPIT Corp
Priority date: 1949-08-24
Filing date: 1949-08-24
Publication date: 1954-07-27
Anticipated expiration: 1971-07-27
Also published as: DE917114C; FR1018457A; CH296741A; GB672413A

Description

July 27, 1954 Filed Aug. 24, 1949 G. F. WALES ETAL WORK HOLDING DEVICE 2 Sheets-Sheet l INVENTORS GEORGE/T144459 "#0 PAUL 720201? fm y A TTOE/YE'Y y 7, 1954 G. F. WALES ET AL 2,684,355

WORK HOLDING DEVICE Filed Aug. 24, 1949 2 Sheets-Sheet 2 mum: 47 Q :22 I; \EIKQE/ J g I W /72 mm. V 4

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Patented July 27, 1954 WORK HOLDING DEVICE George F. Wales, Kenmore, and Paul H. Taylor, North Tonawanda, N. Y., assignors, by direct and mesne assignments, to Wales-Strippit Corporation, North Tonawanda, N. Y., a corporation of New York Application August 24, 1949, Serial No. 112,134

3 Claims. 1

This invention relates to improvements in work holding devices, being concerned more particularly with a device characterized by features which adapt it particularly, but which do not necessarily so limit it, to the support of workpieces in such a manner that they may be turned about a center which bears a predetermined relation with respect to a work-performing tool or other instrumentality. The device, therefore, is available, among other purposes, for rotatably supporting work-pieces in such a relation with respect to a nibbler or other punching element that the work-pieces may be formed into circular or other shapes having curved exteriors or may be punched or perforated in any desired manner at points equidistant from a predetermined center.

One object of the invention is to provide a device which is so designed that it may be availed of to hold work-pieces in various ways, thereby enabling any particular work-piece to be held in the manner best adapted to its physical characteristics, those of the machine with which it is associated and the nature of the operation to be performed.

Another object is to provide a device which is readily adjustable to accommodate work-pieces of various sizes and to support them in various positions with relation to the work-performing tool.

Yet another object of the invention is to provide a device by which the center of rotation of the work-piece may be positioned tangentially or in other than tangential relation with respect to a shaped punch, whereby a circular work-piece may be formed with either an essentially smooth edge or a contoured edge such as possessed, for

example, by a circular saw of the disc type.

A still further object is to provide a device which may be availed of to hold work-pieces securely, yet so that they may be readily attached and released, without in any way imparing or marring the surfaces of the work-pieces or necessitating the formation of center punch holes or the use of screw fastening means, although the device may be employed in connection with center holes and carries screw fastening means which may be utilized, if desired.

A still further object is to provide a device which is unitary in character and which possesses features enabling it to be employed as an attachment, being available tion with existing machines without structural changes thereof.

Yet another object is to provide a device which may be attached to the machine with which it is to be associated in such a manner that the workas such for use in connec- I 2 pieces held thereby will be in the desired relation with performing instrumentality.

A still further object is to provide a device having a novel design and arrangement of parts, whereby to attain simplicity in construction and, when the device is employed as an accessory, to facilitate its attachment to and its detachment from the machine with which it is associated.

The invention is illustrated in the accompanying drawings, in which:

Figure 1 is a fragmentary perspective view of a punch press showing associated therewith, as an attachment, a device embodying the features of the invention;

Figure 2 is an enlarged vertical sectional view taken along line 22 of Figure 1;

Figure 3 is a fragmentary view taken along the same section line showing the center pin of the holder extended to an operative position;

Figure 4 is an enlarged elevational View, partially in section, of the mounting post end of the device as it appears along line 4-4 of Figure 1;

Figure 5 is a vertical section taken along line 5-5 of Figure 4;

Figure 6 is a detail section taken along line 66 of Figure 4; and

Figure 7 is a similar section taken along line !1 of the same figure.

The device, indicated generally at It in Figure 1, is illustrated by way of example in connection with a punch press which is sufiiciently illustrated for the purpose in view by a showing of the head H in which the ram (not shown) operates and the bed I?! which carries a removable punch holder l3 in accordance with the teaching of Figures 13, 14 or 15 of patent 2,364,011, assigned to our interests.

The punch holder [3, as illustrated herein, has a forwardly-extending arm 14 which carries a work-performing tool l5 (punch) at its outer end with which the press ram cooperates and which in turn cooperates with a suitable die (not shown) carried by the punch holder under the workperforming tool. A T-slot 13a is formed in the holder 13 to enable various attachments to be removably and adjustably secured to the press bed, the said slot extending lengthwise of the holder and being open at its forward end.

It is contemplated that the device may, if desired, be employed as an attachment for a machine tool of the type generally described; and when so employed the T-slot l3a may be availed of for attaching it to the press. For this purpose, the head it of the device is carried by an supported accurately respect to the workarm ll, the inner end of which is carried by a post l8. The latter, as best shown in Figures 4, 5, 6 and '7, includes a central bolt l9 which, at its lower end, extends into the T-slot l3a and carries in the wide base portion thereof, an elongated bar 20 which, when loose, may move lengthwise of the T-slot. The bolt i9 extends upwardly through a cone-shaped element 2! which seats upon the holder !3 and which in turn provides a seat for a sleeve 22, the latter having a conical recess at its lower end which in taper conforms to that of the seat portion of the element 2 At its upper end, the sleeve 22 is cut away at one side of the opening which accommodates the bolt is to provide a shoulder 23 on which the inner end of the arm ll is supported, the latter being held on the said shoulder by a cap-piece 24 which on opposite sides has depending

flanges

25 and 26.

The former engages the outer side of the arm ll while the latter has a beveled inner wall which engages a correspondingly inclined flattened area at the top of the sleeve 22. A nut 2'! on the threaded upper end of the bolt it may be turned in one direction to loosen the parts of the post assembly and thereby enable it to be adjusted along the T-slot so that the device as an entirety may be adjusted with respect to the press bed and so that the arm ll may be adjusted lengthwise on the shoulder 23, the device being secured in the desired position of adjustment and the arm I! being clamped thereto by tightening the nut 21. To facilitate adjustment of the device and arm in the manner described, the post assembly may, as illustrated, include a wrench 21a. So that it may be readily available, the latter may be removably secured to the post assembly by a nut 28, the nut 2? having a round neck portion 29 so that the wrench may be moved either to the position shown or to a position in which it is located between the top of the nut 21 and the under side of the nut 28. In the latter position, the wrench is inoperative and may rest upon the corner shoulders of the nut 21.

It will be apparent that upon tightening of the nut 21, the bar 29 by engaging the under sides of the overhanging walls of the T-slot will result in all of the parts of the post assembly being urged downwardly toward the press bed. Thereby the cone-shaped element 21 will be forced tightly against the upper surface of the punch holder !3 while the cooperating inclined surfaces on the element 2 sleeve 22 and cap-piece 2% will cause all of the parts of the post assembly and the arm H to be wedged together and rigidly secured to the punch holder and to one another.

In order to insure against any relative movement between the post assembly l8 and the punch holder 13, the cone-shaped element 2! carries downwardly tapering pins 39 which enter the neck of the T-slot lie at opposite sides of the bolt l9, the degree of taper of the pins being exaggerated for purposes of clarity. The pins 36 are engageable with the side walls of the neck portion of the T-slot liia as the parts of the post assembly are tightened in the manner described. By their engagement with the walls of the T-slot the pins 36 are operative, therefore, to lock the post assembly to the punch holder it, or press bed, against any angular or lateral movements which would be transmitted to the head it.

The head N of the device includes a slide 3i which is adjustable along the arm I1 and which carries a set-screw 32 for locking the slide in any desired position of adjustment along the arm.

At one side of the arm ll, the slide 3| is formed with a threaded bore for accommodating a threaded sleeve 33. The latter is flanged at its upper end to provide a wheel 34 and surrounds a cylinder 35, the upper end of which carries a split ring 36 which engages the hub portion of sleeve 35 at the juncture of the latter and the wheel as. Hence, the wheel 34 may be grasped and manually turned in one direction to lower the sleeve 35 and the head [6 carried thereby and may be turned in the opposite direction to elevate the sleeve and head.

At its lower end, the cylinder 35 carries a disclike member 31 which, although illustrated as circular in shape, need not necessarily be so.

On its under side, the member 3? is formed with a marginal channel 38 for accommodating an O-ring 39 or other suitable sealing element, one of the side walls of the channel 38 preferably being undercut, as illustrated, to restrict the entrance to the channel so that the sealing element may be forced into the channel and will thereafter remain there. It will be noted that the depth of the channel 38 is slightly less than the diameter of the O-ring. Consequently the O-ring projects from the channel 38 only far enough to insure firm sealing engagement between it and the work-piece 40. Preferably the marginal edge of the member 31, that is the rim portion located exteriorly of the O-ring 39, terminates short of the plane of that portion of the under face of the member 3'1 which is located within the confines of the ring 39, whereby to assure atmospheric pressure forcing the O-ring 39 against the side wall of the channel 38 to provide a tight seal.

The member 3! is secured to the lower end of the cylinder 35 by a threaded plug 4| which screws into a threaded recess in the under side of the member 31 and against the flanged lower end of the cylinder, there being a suitable packing 42 between the flange on the cylinder and the marginal portion of the member 31 which surrounds the opening through which the cylinder extends. Preferably the parts are so designed that when the threaded plug 4! is screwed into place its under side will be co-planar with the under side of the member 31. The area of the under side of the member 3'! which is delimited by the O-ring communicates with the interior of the cylinder 35 through a passage 13.

The cylinder 35 accommodates a plunger 54 which is reciprocable therein but which is normally held at the upper limit of its range of movement by a spring 45. The latter surrounds the shank 46 of the plunger, being under slight compression between the upper end of the cylinder 35 and the under side of a head 41. The plunger is formed with an annular channel G9 which accommodates a combined valve and sealing element 50, the latter being in the form of a ring of rubber or other sealing material and, owing to its engagement with the wall of the cylinder 35, offering some resistance to movement with the plunger 44. The width of the channel 49 is such that some axial movement of the element 50 in one direction in the channel 49 is permitted when the plunger M is depressed and some axial movement in the opposite direction in the channel is permitted when the plunger is released and moves in the direction of its normal position. Such movements of the ring 58 aer utilized to control the port of a slot 5|, the said port communicating with the channel 49 at the upper side thereof, being closed by the ring 50 when the latter is located at the lower side of the channel 49, as shown in Figure 2, and being open when the ring is located at the upper side of the channel 49. It will be apparent from the foregoing that the plunger 44 may be moved downwardly against the action of the spring 45, during which operation any air in the cylinder below the plunger will be permitted to escape past the ring 50 and through slot there being suitable clearance between the plunger and the walls of the cylinder 35 at the opposite sides of the ring 50 to permit the passage of air in the amounts involved.

Upon release of the head 41 of the plunger, the spring 45 will automatically act against the head and tend to restore the plunger to its normal position. Such movement of the plunger 44 is accompanied by seating of the sealing ring and valve, whereby as the plunger moves upwardly air will be drawn from the under side of the member 37 into the cylinder 35. If at such time, therefore, the member 37 is pressed against a workpiece so that the O-ring 39 seals off an area thereof, then a vacuum will be created under the said member so that atmospheric pressure will force the work-piece tightly against the member. In this connection it will be noted that the volumetric capacity of the vacuum chamber provided at the under side of the member 3! is very small with respect to that of the cylinder occupied by the plunger 44, the said vacuum chamber being of the order of .005 of an inch high. By this means the mechanical advantage of the spring 45 is greatly multiplied, since it can operate a comparatively small plunger 44 to rapidly exhaust the minute volume of air under the member 3! to produce a high degree of vacuum from a very small force from the spring 45. Fatigue of the operator in high production work is thereby avoided. As a consequence of the high vacuum produced in the chamber at the under side of the member 31, firm engagement of the workpiece with the said member is insured. In this connection it will also be noted that in Figure 2 device is illustrated resting upon a work-piece which in turn is resting upon the punch holder, or press bed l3, and that the plunger 44 is shown at the upper limit of its range of movement. It will be understood when the plunger is forced downwardly and released in the manner described (assuming the head of the device is pressed against a work-piece) it will not return to the upper limit of its range of movement. It will move upwardly only until the atmospheric pressure acting against the plunger 44 balances the force exerted by the spring 45. As the upward movement of the plunger 44 creates the vacuum behind the work-piece and as such movement is efiected by the spring 45, the latter may be made of the desired strength and compressed to any desired degree between the top of the cylinder 35 and the head 41 to produce the desired degree of vacuum. The plunger may be operated a number of times if the desired degree of vacuum is not produced the first time. To relieve the vacuum under the head it, it is only necessary to force the plunger 44 downwardly. By doing this, the work-piece may be readily released by sliding it out from underneath the member 31. In high production operations, a sudden blow on one side of the work-piece, to cause the entry of air, will generally effect its release.

The O-ring 39 seals the vacuum chamber behind the work-piece and also provides a fricthe head of the iii) tional surface which, in response to the pressure of the work-piece against it, will prevent any relative movement between the work-piece and member 31.

The cylinder 35 is journalled in the sleeve 33 for free rotary movement. When the work-piece, therefore, has been secured to the head IS in the manner described, it may be turned freely with respect to the axis about which the head turns. If, therefore, the work-piece is located in the desired relation with respect to the punch IS, the work-piece may be turned so that, assuming a. nibbling operation is contemplated, the work-piece will be formed with a circular edge, or perforations may be formed along a circular path.

It will be understood that in adjusting the head IS in the desired relation with respect to the work-performing tool, the post assembly 43 may be adjusted lengthwise of the T-slot Ita the arm ll may be adjusted longitudinally with respect to the post assembly, and the head !6 may be adjusted lengthwise of the arm. The post assembly 18 also provides for angular adjustment of the head 16 about the axis of the bolt 19 of the post assembly. It will also be obvious that arm Il may be replaced by a longer or shorter arm for certain operations.

As shown in Figure 1, a line 60 is scribed on the machine table l2. When a shaped punch is used such as illustrated in the drawings of application Serial No. 69,954, assigned to our interests, the center screw 55 and its point 56 are extended and the device is adjusted radially with the point 56 following the scribed line 60. This assures that a fore and aft keyed straight sided punch will always out a tangent to the center of rotation of the head, thereby providing a finished edge work-piece. offsetting the center will provide a contoured edge such as characterizes a circular saw disc.

To facilitate positioning of the work-piece so that the center thereof will be located in alignment with the axis about which the member 3? turns, the work-piece may be initially scribed or otherwise marked with an outline conforming to the marginal edge of the member 3'! in such a manner that such marking will be visible and serve as a guide to indicate when the head and work-piece are properly located with respect to one another.

The member 31 may be elevated and lowered, at will, with respect to the plane of the top surface of the press bed by turning the sleeve 33.

' Thereby th initial engagement of the member 31 with the work-piece is insured while at the same time provision is made for supporting the latter at any desired elevation with respect to the work-performing tool. Preferably the sleeve 33 is elevated slightly with respect to the member 31 so that the axial play which is thereby provided between it and the member 35 permits pressing member 37 against the work-piece and raising it to force the work-piece off in the previously described production manner. In other words the work-piece during the operation of the tool may lightly contact the press bed or it may be supported wholly above the press bed. When desired, the sleeve 33 may be secured in its adjusted position by a set screw 33a. If, as in some cases, the die with which the work-performing tool cooperates projects a short distance above the press bed, a shim may be located below the work-piece during the operation in which the work-piece is positioned under the head l6 and 7 the plunger 44 operated to produce the desired vacuum, the shim being operative to support the work-piece in the plane of the top of the die during this operation.

The vacuum arrangement for supporting workpieces has the advantage that the drilling of center holes and the like therein is avoided. it is available in any instance in which the upper surface of the work-piece is not porous, oily or pitted in such a manner as to prevent the creation of the desired vacuum under the member 3?, or to release such vacuum by leakage when once produced.

The device, however, is so designed that it may be availed of, if desired, to hold work-pieces by center pin and screw methods.

To this end the plug 41 of the member 31 carries a combination center and pickup screw 53. The shank portion of the latter occupies a threaded bore 54 in the plug ll and has a head 55 which occupies the enlarged entrance of the bore, the head 55 being formed, or provided, with a point 56 which may be extended, by unscrewing the screw 53, to a position beyond the plane of the lower surface of the O-ring 39, as best shown in Figure 3. As so extended, the point 55 may be caused to enter a center punch mark in the work-piece. This may be accomplished first by extending the point 56 in the manner described and then turning the sleeve 33 to cause the point 56 to enter the center punch mark, it being apparent that this will occur before engagement of the work-piece by the O- ring 39. Thereafter the work-piece may be turned about the point 56 without interference from the O-ring 39 or any other part of the head 16,

In such instances in which the work-piece extends substantially beyond the top of the press bed when in the desired relation with respect to the work-performing tool and when it, therefore, may be desirable to attach the work-piece to the head by screw means, the work-piece may be drilled or otherwise formed with a hole of a diameter slightly larger than that of the shank of the pickup screw 53. Th latter may then be removed and the shank thereof inserted through the hole in the work-piece after the work-piece is properly located against the head. The pickup screw may then be screwed in place and tightened so that its head engages the workpiece.

It will be apparent that the device described has the advantage that work-pieces may be supported by it in various ways, in each of which the workpiece will be firmly attached to the head and in each of which the head will be supported in such a manner that while it may be turned freely, any appreciable deflection of the head with respect to the work-performing tool will be prevented.

The embodiment of the invention which is illustrated is intended by way of example only as various of the advantages noted may be attained in connection with various modifications coming within the purview of the invention.

W e claim as our invention:

1. A device of the character described com prising a head which is recessed on one side to provide a closed channel therein, an elastic gasket positioned in said channel, the depth of said channel being less than the thickness of said gasket, whereby said gasket projects beyond said one side of said head so as to be engageable with a workpiece and seal off a predetermined area thereof, the portion of said one side of said head within said gasket being plane, and the portion of said one side of said head exterior or" said gasket being disposed back of said plane portion so that atmospheric pressure may act against the exposed outside of said gasket when said gasket is engaged with a workpiece, to seat said gasket against the inside wall of said channel, a cylinder, a duct connecting said cylinder with said one side of said head within the area enclosed by said gasket, a plunger reciprocable in said cylinder and manually movable therein in one direction, resilient means for automatically moving said plunger in the opposite direction when released to suck air from the space which is enclosed by said gasket, and a valve movably mounted in said plunger and movable to open position to permit escape of air from said cyiinder ahead of said plunger when said plunger is moved in said one direction, said valve being closed on movement of said plunger in said opposite direction, the area enclosed by said gasket being much greater than the area of said plunger.

2. A device of the character described comprising a head which is recessed on one side to provide a closed channel therein, an elastic O- ring positioned in said channel, the depth of said channel being less than the thickness of said O-ring, whereby said O-ring projects beyond one side of said head so as to be engageable with a workpiece and seal off a predetermined area thereof, the portion or said one side of said head within said O-ring being plane, and the portion of said one side of said head exterior of said O- ring being disposed hack of said plane portion so that atmospheric pressure may act against the exposed outside of said O-ring when said O-ring is engaged with a workpiece, to seat said O-ring against the inside wall of said channel, a cylinder, a duct connecting said cylinder with said one side of said head within the area enclosed by said G-ring, a plunger reciprocable in said cylinder and manually movable therein in one direction, resilient means for automaticaily moving said plunger in the opposite direction when released to suck air from the space which is enclosed by said O-ring, said plunger having a peripheral recess, a sealing ring mounted in said recess, the thickness of said ring having less than the axial length of said recess, and said plunger having a passage therein connected with the upper end of said recess through which air may escape when said plunger is moved in said one direction.

3. A device of the character described comprising a head which is recessed on one face thereof to provide a closed channel spaced from the periphery of said head but extending around the head adjacent its periphery, an elastic O- ring positioned in said channel, the depth of said channel being slightly less than the thickness of said O-ring whereby said O-ring projects slightly beyond said one side face of said head so as to be engageable with a workpiece and seal off a predetermined area thereof to provide a chamber, the portion of said one face of said head, which is exterior of said O-ring, being disposed back of the remaining portion of said head which lies within the perimeter of said O-ring, so that atmospheric pressure may act against the exposed outside portion of the O-ring to seat said O-ring against the inside wall of said recess, when said O-ring is engaged with a workpiece, a cylinder, a duct connecting said cylinder with said one face of said head within the area enclosed by the perimeter of said O-ring, a plunger reciprocable in said cylinder, said plunger being manually movable in on direction in said cylinder, resilient means for automatically moving said plunger in the opposite direction when the plunger is released to suck air from the area enclosed by said O-ring, said chamber having a volumetric capacity which is small with relation to that of said cylinder and an area which is large with relation to that of said plunger.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Number 15 204,484

Name Date Cuthbert Feb. 12, 1889 Robinson Mar. 19, 1901 Church Oct. 15, 1912 Young Feb. 8, 1916 Becker Sept. 26, 1922 Parker July 19, 1938 Legassey June 30, 1942 Forsman Nov. 15, 1949 Ward Sept. 26, 1950 Lewis et a1 Jan. 20, 1951 FOREIGN PATENTS Country Date Canada Oct. 5, 1920