US3733946A - Support assembly for punches and piston rods - Google Patents

Abstract

A support assembly for punches or piston rods of small diameter relative to their required travel. A number of spaced rings or plates are mounted around the punch or rod, and laterally restrained, for example, by the stripper plate of a punching die. The spacing of the rings or plates is controlled and is less than the unsupported length relative to its diameter which the punch or rod will withstand without buckling. On the downstroke of the press, or working stroke of the piston, the rings or plates move together to allow the necessary travel, the sum of the lengths of the initial gaps between the rings or plates being at least equal to the required travel of the punch or rod.

Description

United States Patent [191 Davis 1 3,733,946 [451 May 22, 1973 [54] SUPPORT ASSEMBLY FOR PUNCHES AND PISTON RODS Primary Examiner-Andrew R. Juhasz [76] Inventor: Richard P. Davis, Sanbornton, N.l-l. gg Bray [22] Filed: Feb. 16, 1971 [21] Appl. No.: 115,409 [57] ABSTRACT A support assembly for punches or piston rods of small diameter relative to their required travel. A [52] US. Cl. ..83/129, 83/143, 8833/61832, number of Spaced rings or plates are mounted around 2 Is the punch or rod, and laterally restrained, for exam- Illt- Cl- ..B p h pp plate of a p hi g dieh spac- Ot Search 531, of the rings or plates controlled and i less than 83/582 653 the unsupported length relative to its diameter which the punch or rod will withstand without buckling. On [56] References Cited the downstroke of the press, or working stroke of the piston, the rings or plates move together to allow the UNITED STATES PATENTS necessary travel, the sum of the lengths of the initial 2,323,431 7/1943 Wa1es.,... 83/143 gaps between the rings or plates being at least equal to 2,365,452 12/1958 Porter 83/613 the required travel of the punch or rod. 2,379,003 6/1945 Hedberg... ..83/143 2,362,032 11/1944 Smith, ..83/613 X 10 Claims, 11 Drawing Figures 0 7 5 596a as a PATENTEU 22 5 SHEET 3 OF 4 SUPPORT ASSEMBLY FOR PUNCIIES AND PISTON RODS This invention relates to devices for supporting a punch used to punch small holes in stock of a thickness considerably greater than the diameter of the punch, or a piston rod required to sustain considerable force and have a long travel relative to its diameter.

BACKEROUND OF THE INVENTION The thickness of stock which can be punched with a punch of given diameter is limited by the buckling strength of the unsupported portion of the punch. This portion must be long enough to allow the punch to pass through the stripper plate of the die, penetrate the stock, and enter the holes of the die on which the stock is supported. An unsupported length to diameter ratio of one and a half to two, depending on the type of stock, is normally considered the limit which can be tolerated, and the thickness of stock which can be punched with a punch of given diameter is correspondingly limited to less than twice the diameter of the punch. Consequently, the smallest hole which can be punched in stock of a given thickness is a hole of a diameter of not less than two thirds to one half the thickness of the stock. Similar considerations enter into the travel to diameter ratio which can be tolerated in a piston rod, for example in applications where quick build up of very high pressure is required.

The principal object of this invention is to provide a support assembly which prevents buckling or runout of a punch, while allowing the punch to travel a distance considerably greater than its diameter, so that small holes can be punched in relatively thick stock. Another object is to provide a support assembly which can be used 'on conventional presses and for which the usual types of punching dies can be readily adapted. Still another object is to provide a support assembly which prevents buckling of a piston rod used to create quick build up of high pressure. Other objects, advantages, and novel features will be apparent from the following description.

SUMMARY The support assembly here described consists, in general, of a number of rings or plates surrounding the punch or rod. The rings are laterally restrained, and

spaced apart in the longitudinal direction of the punch when the punch is in idle position. The spacing of the rings or plates is controlled so that the length of the gaps between them is not much greater than, and preferably about equal to, the diameter of the punch. On the downstroke of the press, or operating stroke of the piston as the case may be, the rings are brought together to allow the punch to travel the necessary distance. The spacing of the rings or plates is controlled alternatively by springs, a mechanical linkage, or bydraulic means.

DESCRIPTION OF THE DRAWINGS In the drawings illustrating the invention;

FIG. 1 is a vertical cross-section of a support assembly constructed according to the invention, shown in typical relation to a press head and punching die, the sizes of some of the parts being exaggerated for clarity;

FIG. 2 is a cross-section similar to FIG. 1 showing the positions of the punch and support assembly at the end of the punching stroke;

FIG. 3 is a cross-section taken along line 3 3 of FIG. 1;

FIG. 4 is a vertical cross-section of a variation of the support assembly designed for multiple punching operations;

FIG. 5 is a cross-section taken along line 5-- 5 of FIG. 4;

FIG. 6 is a vertical cross-section illustrating a modified form of spacing control. for the plates of the support assembly;

FIG. 7 is a view taken along line 7 7 of FIG. 6;

FIG. 8 is a vertical cross-section illustrating a form of hydraulic spacing control for the support plates;

FIG. 9 is a fragmentary cross-section illustrating a modification of the hydraulic spacing control;

FIG. 10 is a vertical cross-section illustrating another modification of the hydraulic spacing control; and

FIG. 11 is a cross section of a support assembly applied to a piston rod in a high pressure application.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, the punch 10 is mounted in a holder 11, which may be secured to the head of a press (not shown) or secured ina die which is clamped in the press in any customary manner. Holder 11 has a downwardly projecting boss 11a, which is slidably engaged in a hole 12 running through the stripper plate 13. The stripper plate overlies a sheet of stock 14 which rests on a punching die 15. It is understood that the stock is fed and indexed in any customary manner, and the usual provisions are made for maintaining lateral alignment of the stripper plate, die, and stock.

Surrounding the punch are rings 16, '17 and 18, which are slidable in hole 12. The punch is slidable in the rings. When the punch is in raised, or idle, position, there are gaps I9, 20, and 21 between boss 11a and the upper ring, and between the respective rings. The rings are restrained in the downward direction by a shoulder 13a on the stripper plate, and in the lateral direction by their engagement with the stripper plate.

The spacing of the rings, in the idle position, is determined by screws 22 and 23, which are threaded into rings 16 and 17, respectively, and the heads of which are slidably received in recesses 24 and 25 in rings 17 and 18, respectively. The rings are urged apart by coil springs 26 and 26a, the springs being engaged, respectively, in recesses 27 and 28 in rings 16 and 17, and recesses 24 and 29 in rings 17 and 18.

At the end of the downstroke of the press, as illustrated in FIG. 2, gaps 19, 20, and 21 are closed. The punch has passed through the stock and entered a hole in the die below, completing the punching operation. The combined vertical length of gaps '19, 20, and 21 is somewhat greater than the thickness of the stock 15, to allow for the necessary travel of the punch.

The vertical dimension of any of gaps 19, 20, and 21 is preferably about equal to the diameter of the punch, or, in any case, no greater than the unsupportedlength to diameter ratio which can be tolerated by the punch without danger of buckling or runout, which is normally about one and a half to two. For example, in punching stock of 0.1 inch thickness, gaps 19, 20, and 21 would each have to be about 0.034 inches to allow for the travel. A punch of 0.03 to 0.035 inches diameter could be used. By adding more rings, with similar spacing provisions, the thickness of stock to be punched can be increased, or the size of hole which can be punched in stock of the same diameter can be reduced. A ratio of stock thickness to punch, or hole, diameter of six to'one can be readily attained, and even higher ratios are possible. There is no buckling problem with respect to the portion of the punch which has en tered the stock on the downstroke, because this portion is laterally supported by the wall of the punched hole.

FIG. 4 illustrates a holder for multiple punches. A plate 30 with a boss 30a is mounted in the press and carries tow punches 31 and 32. The boss extends into a rectangular hole in the stripper plate 33. Three rectangular plates 34, 35, and 36, through which the punches pass with a sliding fit, are slidably received in hole 37 in the stripper plate, and restrained in the downward direction by a shoulder 33a. The stripper plate overlies the sheet of stock 38, which in turn is supported on die 39. In this case, the boss 30a is shown as engaging the upper plate 34, but it is understood that there may be a gap between the two, as in the example previously described. Sets of leaf springs 35a and 36a are struck out of plates 35 and 36, respectively, to yieldingly maintain the spacing of the places in the idle position of the punch.

As in the assembly of FIG. 1, the vertical dimension of each of the gaps between the plates 34, 35, and 36 is no greater than the tolerable unsupported length with respect to diameter of the punch, preferably about equal to the diameter of the punch. The sum of the vertical dimensions of the gaps is at least equal to the required travel of the punch. Additional plates, similarly arranged, can be used to obtain any desired stock thickness to punch diameter ratio.

In FIGS. 6 and 7 an alternative arrangement for suspending and spacing the punch support rings or plates is illustrated. The punch 45 is mounted in a holder 46 which is shown secured to the head 47 of a press. A plate 48 overlies holder 46, and, in the idle position, engages a fixed plate 49, which may be the knockout bar of the press. Surrounding the punch are supporting plates 50 and 51, through which the punch passes with a sliding fit. A set of screws 52 passes slidably through plate 48 and holder 46, and is secured to plate 50. The heads of the screws are freely recessed into plate 48. A similar set of screws 54 hasits heads recessed into plate 48 and passes slidably through the intervening members to plate 51 to which the screws are secured.

Plate 51 overlies the sheet of stock 56 which rests on the die 57. In the idle position, gaps 58 and 59 are of a vertical dimension about equal to the diameter of the punch, as previously explained. When the press closes, the heads of screws 52 and 54 ride out of plate 48, allowing members 46, 50, and 51 to come together. When the punch returns to idle position, the heads of screws 52 and 54 bear on fixed plate 49, and gaps 58 and 59 are again established. The spacing screws themselves maintain lateral alignment of the supporting plates. However, the entire supporting plate assembly may be slidable in a stripper plate.

FIG. 8 illustrates a hydraulic spacing arrangement for the supporting plates or rings. The punch 60 is mounted in a holder 61. Slidably mounted in a stripper plate 62, and slidably surrounding the punch, are plates 63, 64, and 65. A tube 66 passes through and is fixed to plate 64, and passes slidably through the O-ring in plate 63. Tube 66 is connected to a flexible tube 68 which leads to the interior of a cylinder 69, having a piston 70. A second tube 71, passing through and fixed to plate 63, is connected to a flexible tube 72 which leads to the interior of a second cylinder 73, having a piston 74. In the idle position of the punch, there are gaps 75 and 76 between the supporting plates. Each of these gaps is filled with a predetermined quantity of hydraulic fluid so that the vertical dimension of each gap is established as about equal to the diameter of the punch, or within the permissible range. As the punch moves down, pistons and 74, which may be linked to or otherwise synchronized with the ram of the press,

move down, drawing the fluid out of the gaps between the supporting plates. On the return stroke of the press, pistons 70 and 74 move up, forcing the predetermined quantity of fluid back between the supporting plates to reestablish the gaps.

An alternative hydraulic spacing arrangement, especially suitable for supporting plates of large area because it allows a small amount of hydraulic fluid to perform the spacing function, is shown in FIG. 9. One of the supporting plates 75a has a recess 78 in which a tube 77, attached to the other supporting plate 76a, is slidably received and sealed by a O-ring 78a. Tube 77 is connected to a flexible tube 79 which leads to a cylinder for alternately introducing into and withdrawing from the volume defined by tube 77 and recess 78 a controlled amount of fluid. The cylinder is controlled by or synchronized with the motion of the press ram, as in the hydraulic spacing arrangement shown in FIG. 8. Several of the spacing devices illustrated in FIG. 9 may be used between each'pair of supporting plates.

Another hydraulic spacing arrangement is shown in FIG. 10. A punch is mounted in a holder 101 which is slidable in a hole 102 in a stripper plate 103. Surrounding the punch are supporting plates 104, 105, and 105. The punch passes slidably through the plates and the plates are slidable in the stripper plate 103. Plate 106 has a cutout 107 which communicates with a port 108 in the wall of hole 102. The port communicates with a duct 109. Plate 105, likewise, has a cutout 110 communicating with a port 111 in the wall of hole 102. Port 111 communicates with a duct 112. Plate 104 also has a cutout 113 communicating with a port 114 which in turn communicates with a duct 115.

In the idle position of the punch, there are gaps 116, 117, and 108 between the successive support plates and the punch holder. Ducts 109, 112, and 115 are connected to suitable means, such as the pistons illustrated in FIG. 8, for injecting and withdrawing a controlled amount of hydraulic fluid into each of the gaps to create the correct spacing in the idle position. Ports 111 and 114 are elongated so as to remain in communication with cutouts 110 and l13,respectively, when the plates come together on the downstroke of the punch. Plates 105 and 104 are of successively greater thickness, so that their cutouts do not overlap ports 108 and 111, respectively, when the punch is a the end of v the downstroke.-

FIG. 1 1 illustrates a support assembly for a piston rod used in a high pressure application. A casing 80 encloses a pressure chamber 81, which may be used for test purposes or connected by suitable ducts to a pressure operated device, such as, for example, the drive for a press ram. A piston rod 82 is slidable in and out of the pressure chamber and is mounted on a driving head 83, which is slidable in a recess 87 in the casing. Supporting rings 84, 85, and 86 are slidably received in recess 87, and slidably surround the piston rod. In the idle position of the piston rod, rings 84, 85, and 86 are spaced from each other and from head 83 and the base of recess 87 by sets of leaf springs 88, 89, 90, and 91, which create gaps 92, 93, 94, and 95. These gaps are of a dimension, in the longitudinal direction of the rod, about equal to the diameter of the rod, or within the tolerable unsupported length with respect to diameter of the rod for the pressure load on the rod in any particular application.

On the working stroke of the piston, the leaf springs yield to permit the supporting plates to come together and allow the piston rod to advance to the position indicated by the dotted line 96, thus quickly building up a high pressure in chamber 81. This device has a advantage over other devices, such as pumps, for building up pressure, because the pressure can be built up very rap idly, and also reduced to normal very rapidly by withdrawing the piston rod.

It is understood that the spacing linkages and hydraulic means described in the previous examples can be used to space the plates or rings in FIG. 11. Also the number of rings and gaps can be varied to permit any desired travel of the rod, without exposing any unsupported portion longer than the length to diameter relationship which will withstand buckling.

The holder has been here described in relation to a circular punch or rod. However, such a holder, with appropriately shaped holes in the supporting rings or plates, may be used to support a punch or rod of crosssectional shape other than round, for example, rectangular, hexagonal, T-shaped, I-shaped, or of irregular shape. It is understood that the term diameter as used herein and in the following claims is intended to include transverse dimensions having similar significance with respect to columnar or buckling strength.

I claim:

1. A support assembly, for a punch or the like of predetermined diameter, comprising: a first, a second, and a third supporting member surrounding said punch, said members being slidable in the longitudinal direction of the punch toward and away from each other; means for laterally aligning said members; and control means for creating a first gap between said first and second supporting members and a second gap between said second and third supporting members, said control means being adapted to limit the maximum dimension of each of said gaps in the longitudinal direction of the punch to a dimension no greater in proportion to said diameter than the unsupported punch length todiameter ration which can be tolerated by the punch without buckling, and the combined longitudinal dimensions of both gaps being at least equal to the travel of the punch.

2. A support assembly as described in claim 1, said members comprising rings.

3. A support assembly as described in claim 1, said members comprising polygonal plates.

' 4. A support assembly as described in claim 1, said control means comprising a screw secured to one of said first and second members and having a head slidably received in the other, and a second screw secured to one of said second and third members and having a head slidably received in the other, and spring means urging all said members apart.

5. A support assembly as described in claim 1, said control means comprising a leaf spring struck out of one of said first and second members and engaging the other, and a second leaf spring struck out of one of said second and third members and engaging the other.

6. A support assembly as described in claim 1, said control means comprising a first screw passing slidably through one of said first and second members and secured to the other, a second screw passing slidably through one of said second and third members and secured to the other, and a fixed member engageable with said screws to create said gaps.

7. A support assembly as described in claim 1, said control means comprising means for admitting to and withdrawing from said gaps a controlled amount of hydraulic fluid.

8. A support assembly as described in claim 1, said control means comprising a first tube passing through said first member and communicating with at least a portion of said first gap, a second tube passing through said first and second members and communicating with at least a portion of said second gap, flexible conduits connected to each of said tubes, and means for'injecting and withdrawing controlled amounts of fluid connected to said conduits.

9. A support assembly as described in claim 1, said control means comprising a casing surrounding said members, a first orifice in said casing communicating with said first gap, a second orifice in said casing communicating with said second gap, and means for introducing a controlled amount of hydraulic fluid into said gaps through said orifices.

10. A support assembly as described in claim 1, said control means comprising a cylinder mounted on one of said members, another of said members having a recess in which said cylinder is slidably received, and means for introducing a controlled amount of hydraulic fluid into said cylinder and said recess.

a: a e a a:

Claims (10)

1. A support assembly, for a punch or the like of predetermined diameter, comprising: a first, a second, and a third supporting member surrounding said punch, said members being slidable in the longitudinal direction of the punch toward and away from each other; means for laterally aligning said members; and control means for creating a first gap between said first and second supporting members and a second gap between said second and third supporting members, said control means being adapted to limit the maximum dimension of each of said gaps in the longitudinal direction of the punch to a dimension no greater in proportion to said diameter than the unsupported punch length to diameter ration which can be tolerated by the punch without buckling, and the combined longitudinal dimensions of both gaps being at least equal to the travel of the punch.

2. A support assembly as described in claim 1, said members comprising rings.

3. A support assembly as described in claim 1, said members comprising polygonal plates.

4. A support assembly as described in claim 1, said control means comprising a screw secured to one of said first and second members and having a head slidably received in the other, and a second screw secured to one of said second and third members and having a head slidably received in the other, and spring means urging all said members apart.

5. A support assembly as described in claim 1, said control means comprising a leaf spring struck out of one of said first and second members and engaging the other, and a second leaf spring struck out of one of said second and third members and engaging the other.

6. A support assembly as described in claim 1, said control means comprising a first screw passing slidably through one of said first and second members and secured to the other, a second screw passing slidably through one of said second and third members and secured to the other, and a fixed member engageable with said screws to create said gaps.

7. A support assembly as described in claim 1, said control means comprising means for admitting to and withdrawing from said gaps a controlled amount of hydraulic fluid.

8. A support assembly as described in claim 1, said control means comprising a first tube passing through said first member and communicating with at least a portion of said first gap, a second tube passing through said first and second members and communicating with at least a portion of said second gap, flexible conduits connected to each of said tubes, and means for injecting and withdrawing controlled amounts of fluid connected to said conduits.

9. A support assembly as described in claim 1, said control means comprising a casing surrounding said members, a first orifice in said casing communicating with said first gap, a second orifice in said casing communicating with said second gap, and means for introducing a controlled amount of hydraulic fluid into said gaps through said orifices.

10. A support assembly as described in claim 1, said control means comprising a cylinder mounted on one of said members, another of said members having a recess in which said cylinder is slidably received, and means for introducing a controlled amount of hydraulic fluid into said cylinder and said recess.

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