US2986057A - High pressure hydraulic piercing cylinder with integral booster and stripping means - Google Patents

Description

May 30, 1961 T. F. NOVAK 2,986,057

HIGH PRESSURE HYDRAULIC PIERCING CYLINDER WITH INTEGRAL BOOSTER AND STRIPPING MEANS Filed Sept. 11, 1957 2 Sheets-Sheet 1 FE E K 1 J 4 H v /7/ :A 52

IN V EN TOR. 77/5090/25 F. A/o 144k MLQQw/V #7 77'ORNEY May 30, 1961 T. F. .NOVAK 2,986,057

HIGH PRESSURE HYDRAULIC PIERCING CYLINDER WITH INTEGRAL BOOSTER AND ST-RIPPING MEANS Filed Sept. 11, 1957 2 Sheets-Sheet 2 ENO Y9 ML RNEY INVENTOR N h WV. m w v w w i w 2 m6 w w w ...M am

I! 14 NIIIII'III rd u 5"! United States Patent HIGH PRESSURE HYDRAULIC PIER'CING CYLIN- DER WITH INTEGRAL BOOSTER AND STRIP- PING MEANS Theodore F. Novak, La Grange Park, Ill., assignor to Danly Machine Specialties, Inc., Chicago, Ill., a cor poration of Illinois Filed Sept. 11, 1957, Ser. No. 683,312

8 Claims. (Cl. 83-133) My invention relates to a high-pressure, hydraulic, piercing cylinder and more particularly to an improved, high-pressure, hydraulic, piercing cylinder having an integral booster and stripping means.

Hydraulic power cylinders for pushing a punch or the like through a workpiece are known in the prior art. These assemblies are provided with an automatic means for holding a stripper plate against the work while the punches are being withdrawn or stripped from the work. One form of such an assembly is disclosed in the patent to C. E. Novinger et al., No. 2,758,652, issued August 14, 1956, for a hydraulic punch and stripper. In these punch and stripper assemblies fluid under pressure moves a power piston and cylinder relative to each other to move the punch holder toward the work. At the same time the fluid under pressure moves a stripper plate into engagement with the work to hold the work firmly in position during the punching operation. After the stripper plate engages the work and before the punches enter the work, it is necessary to boost the pressure within the cylinder in order to drive the punches through the work. To accomplish this in systems of the prior art a separate booster external to the piston and cylinder assembly is employed. It will be appreciated that high-pressure pipes are required to carry fluid from the booster to the piston and cylinder assembly. This system of the prior art is expensive and the possibility exists that leaks will develop under the action of the high-pressure fluid.

I have invented an improved hydraulic punch and stripper assembly which is provided with an integral booster for raising the fluid pressure by an amount necessary to drive the punches through the work. My assembly 'does not require the external booster employed in systems of the prior art. My system does not require that fluid under high pressure he conducted through any pipes external to the punch and stripper assembly. For this readevelop leaks than are the systems of the prior art.

One object of my invention is to provide a high-pressure,

hydraulic, piercing cylinder having an integral booster and stripping means.

Another object of my invention isto provide a high pressure, hydraulic, piercing cylinder which does not require the external booster of systems of the prior art.

A further object of my invention is to provide a highpressure, hydraulic, piercing cylinder which does not require fluid under a high pressure to flow through any pipe external to the cylinder.

A still further object of my invention is to providela high-pressure, hydraulic, piercing cylinder which is less a'power chamber and with a stripper chamber. I a stationarypower piston within the power chamber andj a movable stripper piston within the stripper chamben;

My stripper piston has a head, on which fluid admitted into the stripper chamber may act, and an end extending into a bore in the wall separating the cylinder chambers. Fluid under pressure admitted to the power chamber on one side of the power piston head moves the cylinder assembly toward the work. This fluid also acts on the small face of the piston to move the piston into engagement with the stripper pins which hold a stripper plate against the work; After the stripper plate contacts the work the increased resistance moves the stripper piston relative to-the cylinder to build up a back pressure in the power chamber and supply line to actuate a sequence valve to admit fluid under pressure to the stripper chamher on the side of the stripper piston head in engagement with the stripper pins. This fluid acts on the relatively large areaof the stripper piston head to cause a buildup or boosting of the pressure in the power chamber through the medium of the smaller area face of the shipper piston son my assembly is less expensive and is less likely to i to provide the pressure required to drive the punches through the work. At the .same time, this fluid under pressure maintains the stripper plate in engagement with' the work; A check valve in the supply lines prevents this boosted pressurefrom backing up into the supply lines.

' When the punching operation is complete, direction of the fluid flow in the. supply lineis reversed, the punch is stripped from the work and the assembly is returned to its initial position.

.In the accompanying drawings, to which reference is made in the. instant specification and which are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views Figure 1 is a schematic view of my high-pressure, piercing cylinder and its associated fluid system.

Figure 2 is a sectional view of my high-pressure, piercing cylinder showing therelative positions of the parts before a punching operation is begun.

Figure 3 is a sectional view of my high-pressure, pierc-li .ing cylinder showing the relative positions of the parts as the cylinder moves toward the work.

Figure 4 is a sectional .view of my high-pressure, pierc ingcylinder showing the relative positions of the,

during the course of a punching operation.

Figure 5 is 'a sectional view of my high-pressure, piercing the return stroke of the cylinder.

body It}.

An end cap 18,

her 12. p

' Thepress A punch-carrier tool head whichextends 'intoa' bore 42 formed in separator. '16,

Patented May 30, 1961..

ing cylinder showing the relative position of the parts dursecured to an' end of the body 10 by any convenient means such as bolting or the like,- 1. closes the end of the power chamber 12. A'power piston rod 20 passes through a bore 22 in cap 18. Cap 18 houses a power piston head 24 formed on rod 20 within chain-1' with which our cylinder is used includes a frame, indicated generally by the reference character 26, having an upright heel block 28 on which we mount the i power piston rod 20 by any convenient means (not shown). We provide frame 26 with a 'guideway 32 on which the cylinder 10 rides inits movement toward and ;away from the work. i i 34, secured to theend of body- 10 remote from cap '18 by any. convenient means' 2 such as bolts 36, closes the stripper chamber 14 to house." a booster and stripperpiston 38 formed with a rod r 3 From the foregoing it will be seen that a fluid under pressure admitted into chamber 12 on that side of head 24 which will cause body to move to the right as viewed in Figure 1, also will act on the end face 44 of rod 40 to movi head 38 t h i t, as vi we 't fie e C i v'e'rsely; fluid pressure admitted tochamber14"betvveen headot stripper and booster piston38 and tool head 34 istran'sinittejd by rod 40 to chamber 12 th'r'ou'ghthe medi urn ofthe face 44. Owing to the relatively largearea o f'head of stripper and booster piston38 with "respect to this face; a multiplication of pressure results in the course of transmissionof pressure by rod 40.

Bolts 46 screwedinto to'ol head 34 have smooth shanks 4s whichslidably support as trfipper plate 50foimovenient along shanks 481 Stripper pins 52 extending through theto'ol head 34' and through the punch holder, to be described hereinafter, are adapted 'to transmit pressure ffomjstrjipper and booster pis'ton38 to stripper plate 50.

A' screw54'secures thepun'ch holder 56t o the tool head 34. purichholder '56 supports the tools such as punchesSS which are requiredto perform the necessary' operations on a'work piece 60 supported on the frame byany convenient means (not shown) known to the art. I form the stripper plate 50 with bores 62 through which punches 58 pass in the course of a punching operation.

Frame 26 also carries a guide 64 having bores 66 into which punches 58 push slugs or piece parts 68 formed in the'course of a punching operation. Bores 66 are open to permit the slugs 68 to fall out of the die to a scrap collector or the like (not shown).

'1 form rod20 and heel block 28 with a first passage 70 through which fluid under pressure may be admitted tochamber 12 between head 24 and separatingwali 16. A second passage 72 formed in rod 20 and in heel block 28 provides a path for the flow of fluid to chamber 12 between head 24am plate 18.

My fluidsupply system includes a motor 74, which drives a pump 76 through the linkage 78 to draw fluid from a tank 80 through a pipe 82. Pump 76 supplies fluid under pressure to a pipe 84 to which I connect a relief valve 86 which permits the fluid to flow back intothe tank when the pressure within pipe 84 exceeds a predetermined pressure. A control valve, indicated generally by th e reference character 88.has a housing 90 provided with a port 92 communicating with pipe 84. The valve spool 94 includes respective heads 96 and 98 which, the central position of spool 94 shown in Figure 1, close respective outlet port-s .100 and 102 connected to pipes 104 and. 10 6. Spool 94 is adapted to be actuated in any convenient manner known to the art to moveto theleft or to the right of the intermediate position shown in Figure 1. In the left position of spool 94 a communication ,is established between supply pipe 84 and pipe 104. At the sametirne fluid from pipe 106 is permitted to flow through housing 90 and thrpugh an outlet pipe 108 to the tank.

In the position of spool 94 to the right a communication is established between pipe 106 and supply pipe 84 while fluid in pipe 104 is permitted to flowthrough the valve body and through a pipe 110to the tank. I connect pipe 104 to one inlet port 112 of a pilot-operated check valve indicated generally by the reference character 114, having a housing 116 formed with a chamber 118 provided with a seat 120. A spring 122 normally seats the piston 124 of valve 114 on seat 120. A port 126 formed in .housing 116 is adapted to admit fluid under pressure to the housing to act on a piston 5128 which contacts piston 124 to lift thelbo'dy ofl seat 120. The pipe 127 connects port 126 to pipe 106. Thefluid acting on piston 128 moves the piston 124 upwardly, as viewed in Figure 1, to permit fluid in the chamber 12 to flow outwardly' through passage .70,' through a port 130 formed in'housing116 and past seat 120 to pipe 104.

JI'hehydraulic system of my piercing cylinder includes a sequence valve indicated generally by the rererence character 132'having a housing 134 formed with a port 136 for conducting fluid from a pipe 138, connected to pipe 104, the chamber 140 formed by housing 134. A spring 142 disposed in housing 134 normally positions the valve spool 144 to close 'a' port 146 formed in the wall of the housing 134. A pipe 148 connects port 146 to passage I'forrned bythe' cylirr'derbody '10. Passage" 1 50"atfords a communication between pipe 148 and chamber 14 be tween the stripper and booster piston 38 and tool head 34. A passage 152 formed in the wall of housing 134 is adapted to connect port 136 with port 146 to by-pass the chamber 140. A spring 154 normally positions a ball 156 against a seat 158 formed in passage 152 to close the passage. Spring 154, ball 156 and seat 158 form a check valve for preventingthe flow of fluid from port 136 to port 146 while permitting fluid to flow in the reverse direction from port 146 to port 136.

Apassage 160 formed in the wall of body 10 connects a passage l62 leading into chamber 12 between head 24 and cap l8 with a bore 164 leading into chamber 14 between dividing wall 16 and stripper and booster piston 38.

Referring now'to Figures 1 and 2 to S, which latter figures illustrate the relative position of the parts at various poin ts in a punching operation, before an operation body 10 and power piston head 24 occupy the relative position shown in Figure 2. When a punching operation the spool 94 of valve 88 is shifted, by any convenient means known to the art, to the left as viewed Figure 1 to connect pipe 104 with supply pipe 84. Atthe same time pipe 106 is connected to the tank through pipe 108. The direction of flow of fluid in this condition of valve 88 is indicated by the arrows in Figure 2. under pressure in pipe 104 urges piston 124 upwardly as viewed in Figure 1 against the action of spring i ilqwsthrough port 130 and passage 70 into chamher 1 2. This fluid advances the stripper piston 40 to the right asviewed in Figures 1 and 2. At the same time it moves cylinder body 10 to the right as viewed in the figures to advance the stripper plate 50 and the punch assembly toward the work 60. As is known in the art, the stripper plate 50 engages the Work 60 before the punches 58. The increased resistance as the stripper plate engages the work is transmitted through pins 52 and through the stripper piston to the fluid in chamber 12 between wall 16 and piston head 24. As a result of this increased resistance the pressure of the fluid in pipe 104 builds up toicause a similar build-up in the chamber 140 ofthie valve 132. The relative position of the parts as the stripper plate engages the work is shown in Figure 3.

As the pressure within chamber 140 builds up spool 144 moves upwardly as viewed in Figure 1 to open port 146 to permit fluid to flow from pipe 104 through pipe 138 and through chamber 140 to pipe 148. It will be seen that fluid from the supply pipe now flows into chamber 14betweenthe head ofstripper and booster piston 38 and the tool head 34. ,fThisflow of fluid produces two results.

, ;First, it acts on the face of stripper and booster piston 38 to shift the stripper and booster piston to the left as viewed in Figure 4 to,b oost the pressure within the chamber 12 between; wall 16'andhead 24. The amount by which the pressure of the fluid within chamber 12 increases is proportional to the relative areas of the face of stripper and tion when the pressure in chamber 12 between wall 16 head 24' is built up is shown in Figure 4. "Atthe end of the punching operation in order to return ment of the stripper piston under the action of this fluid relieves the built-up pressure on the fluid between wall 16 and head 24. The piston head 38 continues its movement tothe right to engage the stripper pins 52 to maintain stripping pressure on plate 50. At this point in the return operation the punches in the work cause a resistance to movement of cylinder body which results in a build up of pressure within pipe 106. This pressure build up is transmitted through the fluid in pipe 127 to piston 128 to move piston 124. upwardly as viewed in Figure 1 to open port 130 to permit fluid to flow out of chamber 12 through passage70 and port 130 to the tank through pipe 104. It will be remembered that spring 122 returned piston 124 to seat 120 when spool 94. of valve 88 was moved tothe right to initiate a return operation. The direction of flow of fluid during the beginning of a return operation is shown by the arrows in Figure 5. After this connection of passage 70 to the tank, body 10 moves away from the Work with tool head 56 to strip the punches from the work. When piston head 38 bottoms on tool head 34 the punches are fully stripped and oil continuing to flow into chamber 12 from passage 72 moves the entire assembly away from the work to its .fullyretracted position. The assembly is then ready for the next punching operation.

It will. be seen that I have accomplished the objects of my invention. I have provided a high pressure bydraulic .piercing cylinder with an integral booster and stripping means. Myv cylinder does not require the external boosters required by assemblies of the prior art. My cylinder accomplishes the punching operation without the flow ofhigh pressure fluid in any pipe external to the cylinder, My hydraulic piercing cylinder is less expensive to 7 construct than systems of the prior art. Further, it is less likely to develop leaks than are systems of the prior art.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to otherfeatures and subcombinations. This is contemplated by and is Within the scope of our claims. It is z'furth'er obvious that various changes may be made in details within the scope of our claims without departing'from'the spirit of our invention. It is therefore to be understood that our invention is not to be limited to the specific details shown and described.

Having thus described my invention, what I claim is: 1;. 'A (hydraulic working cylinder for performing an operation on a workpiece including in combination a cylinder body formed with a power chamber and stripper chamber, apower piston having a head mounted for reciprocation within said power chamber, a tool, a die, means connecting said tool to one of said power piston and cylinder body for movement therewith, means connecting said die to the other of said power piston and cylinder body for movement therewith relative to said tool, a stripper plate, means mounting said stripper plate for movement relative to said tool, a stripper piston disposed in said stripper chamber and having a head and a plunger formed with a face, means providing communication between said face and said power chamber, means for transmitting force from said stripper piston to said stripper plate, a source of fluid under pressure, means for admitting fluid to said power chamber from said source to move said power piston and cylinder body away from each other to move said stripper plate and said tool and said die toward each other, said fluid being adapted to act on said plunger face to move said stripper plate into engagement with said work before said tool engages the work, means responsive to the engagement of said stripper plate with the work for admitting fluid from said source to said stripper chamber to move said plunger face toward said power chamber to boost the pressure within'said power chamber to drive said tool into engagement with the work.

2. A hydraulic working cylinder as in claim 1 includingmeans for admitting fluid into said power chamber to cause said tool and die to move away from each afte a forming operation is complete.

3.'A hydraulic working cylinder for driving a tool to perform an operation on a workpiece including in combination a cylinder body, means dividing said body into a first chamber and a second chamber, said dividing means being formed with an opening providing communication between said chambers, a power piston disposed within; said first chamber, means mounting said power piston' and said cylinder body for movement relative to each other,-a booster piston disposed in said second chamber,

and'having a portion of reduced cross-sectional area extending into said opening, a source of fluid under pressure,

means for admitting fluid-from said source into said first chamber to move said piston and cylinder relative to each other, a sequence valve adapted to be actuated to admit fluid from said source to said second chamber, a stripper plate carried by said cylinder body and adapted to be moved into engagement with said workpiece as said cylinder and power piston move relative to each other and means responsive to the engagement of said stripper plate with said workpiece for actuating said sequence valve to :admit fluid from-said source to actuate said booster piston to boost the pressure within said first chamber. a

4. A hydraulic working cylinder as in claim 3 in which said means responsive to the engagement of said stripper plate with said workpiece includes means providing a .driving connection between said stripper plate and said booster piston.

5. A hydraulic working cylinder for driving a tool toward adie toperform an operation on a workpiece including in combination aframe, acylinder body means dividing-said body into a first chamber and a second chamber, said dividing means being formed with an opening providing communication between said chambers, a'powe'r piston disposed within said first chamber, means mounting said piston for movement on said frame, means mounting said cylinder for movement with respect to said frame and with respect to said piston, means connecting said tool to-one of said power piston and cylinder body,-me,ans I connecting said die to the other of said power piston and cylinder body, a booster piston disposed: in said'se'condl chamberand having aportion of reduced cross-sectional area extending into said opening, a source of fluid under pressure, means for admitting fluid fromsaid source into said first chamber tomove said piston and cylinder relative to each other to cause, said tool to move towardsaid fdie and means responsive to a predetermined amount of said relativemovement of said piston and cylinder body for admitting fluid from said source to said second chain v ber to actuate said "booster piston to boostthepressure Within said first chamber.

6. A hydraulic working cylinder for performing an operation on a workpiece including in combination a cylinder body formed with a power chamber and stripper chamber, a power piston having a head mounted for reciprocation within said power chamber, a tool, a die, means connecting said tool to one of said power piston and cylinder body for movement therewith, means connecting said die to the other of said power piston and cylinder body for movement therewith relative to said tool, a stripper plate, means mounting said stripper plate for movement relative to said tool, a stripper piston disposed in said stripper chamber and having a head and a plunger formed with a face, means providing communication between said face and said power chamber, means for transmitting force from said stripper piston to said stripper plate, a source of fluid under pressure, means for admitting fluid from said source to said power chamber on one side of said-power piston head to move said powerp'iston and cylinder body away from each other to move said stripper plate and tool and said die toward each other, said fluid acting on said plunger face to move said stripper plate intoenga'gement with said work before said tool engages the work, means responsive to the engagement of said stripper "plate with said work for admitting fluid from said source to said stripper chamber on one side of said stripper pistonto move said plunger face toward said power chamber to boost the pressure within said power chamber to drive said tool into engagement with the work, meansfor-admitting fluid from said source into said power chamberon the other side of said piston'to cause said tool and die to move away from each other after a forming'operation is complete and means for admitting fluid from said power chamber onsaid other side of said power piston to said stripper chamber on the other side of said stripper piston head. i

7. A hydraulic working cylinder for driving a tool to perform an operation on a workpiece including in combination a cylinder body having a power chamber, a power piston disposed in said power chamber, a tool; a die, means connecting said tool to one of said piston and cylinder for movement therewith, means connectingsaid die to the other of said piston and cylinder for movement therewith relative to said tool, said workpiece being disposed between said tool and said die, a source of fluid under pressure, a reservoir, a control valve having a pair of outlet ports and adapted to be operated'to connectone of said ports to said supply and the other of said ports to said reservoir and to connect said one portto said reservoir and saidotherport to said supply, a pilot operated check valve for connecting said one port to said chamberon one side of said piston when 'said one port is connected to said supply to move said piston and cylinder body relative to each other to move said tool and die toward each other, said-check valve being'adapted to be operated to connect said chamber on said one side of said piston to said one port when said one port is connected tosaid reservoir, means connecting said'other port to said chamber on the other side of said piston, means responsive to an increase of pressure in said chamber on said"otherside of the piston for operating said check said cylinder body having a second chamber and an opening providing communication between said second chamher and said powerchamber, a booster piston disposed in'said second chamber, said booster piston having a portion of reduced cross-sectional area disposed in said openeach other for causing an increase in pressure in said power chamber on said one side of said power piston for operating said sequence valveto connect said one port to said second chamber.

valve when said other port is connected tosaid supply, 4

8. A hydraulic working cylinder for driving a tool to perform an operation on a workpiece including in combination a cylinder body having a power chamber, a power piston disposedin said power chamber, "a tool, a die, means connecting said tool mom of said piston and cylinder for movement therewith, means connecting said die to the other of said piston and cylinder for movement therewith relative to said tool, said workpiece being disp'osed between said tool and said die, a source of fluid under pressure, a reservoir, a control valve having a pair of outlet ports and adapted to be operated to connect one of said ports to said supply and the other of said ports to said reservoir and to connect said one port to said reservoir and said other port to said supply, a pilot operated check valve for connecting said one port to said chamber on one side of saidpiston when saidone port is connected to said supply to move said piston and cylinder body relative to each other to move said tool and die toward each other, said check valve being adapted to be operated to connect said chamber on said one side of said piston to said one port when said one port is connected to said reservoir, means connecting said other porttosaid chamber on the other side of said piston, means responsive to an increase of pressure in said chamber onsaid other side of the piston for operating said check valve when said other port is connected to said supply, said cylin'der body having a second chamber and an opening providing communication between said second chamber and said power chamber, a booster piston disposed in said second chamber, said booster piston having a portionof reduced cross-sectional area disposed in said opening, a sequence valve adapted to be operated to connect said one port to said second chamber, means responsive to a predetermined movement of said power piston and said cylinder body in moving said tool and die toward each other for causing a pressure increase in said power chamher on said one side of said power piston for operating saidsequence valve to connect said one port to said second chamber, and a check valve for by-passing said sequencevalve when said other port is connected to'said supply.

References Cited in the file of this patent UNITED STATES PATENTS 2,324,149 Gray July 13, 1943 2,351,872 Parker June 20, 1944 2,403,912 Doll; July 16, 1946 2,534,292 Mueller Dec. 19, 1950 2,576,584 Ernst Nov. 27, 1951 2,758,652 Novingeret al 'Aug. '14, 1956 2,765,036 Harper Oct. 2, 1956 2,776,540 Kraujalis Jan. 8, 1957 FOREIGN PATENTS 551,059 Belgian; Sept. 29, 1956

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