US2928451A

US2928451A - Self contained perforating and countersinking unit

Info

Publication number: US2928451A
Application number: US486440A
Authority: US
Inventors: Paul H Taylor
Original assignee: WALES STRIPPIT CORP
Current assignee: WALES STRIPPIT CORP; WALES-STRIPPIT Corp
Priority date: 1955-02-07
Filing date: 1955-02-07
Publication date: 1960-03-15
Anticipated expiration: 1977-03-15

Description

March 1960 P. H. TAYLOR 2,928,451

SELF CONTAINED PERFORATING AND COUNTERSINKING UNIT Filed Feb. '7, 1955 2 Sheets-Sheet l IN VEN TOR. RmZJZT T 207 SELF CONTAINED PERFORATING AND COUNTERSINKING UNIT Filed Feb. 7, 1955 March 15, 1960 P. H. TAYLOR 2 Sheets-Sheet 2 G E" W 3/ INVENTOR.

Paul H United States Patent O 2,928,451 SELF CONTAINED PERFORATING AND COUNTERSINKING UNIT Paul H. Taylor, Grand Island, N.Y., assignor to Wales- Strippit Corporation, North Tonawanda, N.Y., a colporation of New York Application February 7, 1955, Serial No. 486,440

6 Claims. (Cl. 153-21) The present invention relates generally to self-contained perforating units, and more particularly to a selfcontained perforating unit adapted to punch and counter sink a hole simultaneously.

Devices of the type disclosed herein have been needed for some time by the sheet metal industry where' it is often desirable to punch a hole and countersink simultaneously; for with a self-contained perforating unit that will punch and countersink a hole simultaneously need for composite or progressive dies will be avoided. With these dies the holes must first be punched and then these holes must be accurately registered with the countersinking unit in order to countersink the holes. 'Heretofore, however, where attempts have been made to use a self-contained unit for simultaneously punching and countersinking a sheet metal piece, the punch has had to be solid enough to perforate the workpiece, which has meant a substantial column. This, in turn, has meant that when the countersinking portion of the punch is bottomed, the punch itself seats against solid metal; and the pressure of the press ram on the punch is transmitted directly through the punch to the die of the unit and to the bed of the press. As a result, extremely high stress levels are produced in the punch, with consequent failure of the mechanism, and in particular of the punch. Generally, the life of conventional self-contained perforating units for punching and countersinking a hole simultaneously, has been extremely short.

In some instances, stop-blocks have been used on the press to prevent overloading the punch members. When stop-blocks are used, however, the high forces developed are usually transmitted to the press itself because a press by nature is a piece of heavy equipment and cannot be accurately set to stop on its downward stroke within precise limits.

Despite their short life and other disadvantages the use of these conventional units has been justified because of the reduction in overall cost as compared with the cost of the complex dies required Where punching and countersinking are efiected progressively.

One manner in which overloading of the punch member can be prevented in a perforating-countersinking unit is through the use of resiliency somewhere in the system.

In the Wales US. Patent No. 1,955,866, granted August 24, 1934, for instance, there is shown a self-contained unit which is intended primarily for perforating workpieces. On occasion, however, this type unit has been used for perforating in a countersinking application, for in many instances it is possible to do the countersinking without failure of the unit because the springstripper provides the unit with the required compensating resiliency. In many cases, however, it is essential that the countersinking be done with a punch member which is also the perforating implement. Since this particular tool is difficult to maintain very accurate in length, however, it is extremely difiicult to adjust the sheet height of the press close enough so that simultaneous perforating and countersinking can be done without a high rate of failure of the punches. Thus, the problem is presented of achieving resiliency in such way that sufiicient force can be transmitted to the punch member to enable it to perforate and countersink a workpiece, while preventing a buildup in stress levels to a point where, because of overtravel of the press ram, inaccuracy in the length of the punch, or the like, the punch will be fractured. However, in the past, all attempts to use, for this purpose, rubber or other resilient devices have failed. This is becausesuch high forces must be transmitted through the resilient medium, that the resilient member had to be so large that it rendered the unit itself impractical. Moreover, none of the resilient mediums heretofore available were suitable for the purpose. As a result, in most instances it has been preferred to overload the punch or the stop blocks, and to replace these parts when they failed. I

.When stop blocks are used, however, extreme accuracy in manufacture of the punching units is still required to control the distance from the head to the countersink very accurately, as well as the height of the die member, and of theholder to which the unit is attached. Tolerances in the neighborhood of .0002" are necessary on these parts of the unit to prevent excessive buildup in stress levels with resultant early failure of the units. Even when such close tolerances are maintained, poor countersinking by some of the units, where a multiple unit set-up is used, sometimes occurs because of this .0002" tolerance.

An alternative, when a number of perforating and countersinking units are to be used for simultaneous operation on a workpiece, is to take the units after they have all been assembled and to grind the punches to the same identical lengths, when closed. This is time-consuming and costly, and prevents the interchangeability of punches and other parts, normally associated with a mass production operation.

One object of this invention is to provide a non-bottoming perforating-countersinking unit.

Another object of this invention is to provide in a countersink type of perforating unit means for compensating for buildup in tolerances in the several parts of the unit. 7

Another object of this invention is to provide perforat ing-countersinking apparatus in which commercial parts may be used to provide a non-bottoming perforating unit.

Another object of the invention is to provide a countersink type of perforating unit, which will eliminate failure of punches when a plurality of them are used simultaneously for multiple punching-countersinking operations on a workpiece. 1 h

Another object of this inventionis to provide perforating-countersinking apparatus of the character described which has incorporated therein resilient means for venting excessive buildup in stress levels.

Another object of this invention is to provide perforating-countersinking apparatus which will have a vastly longer life than similar units of prior design, but whic at the same time will be reasonable in cost.

Other objects of this invention will be apparent hereinafter from the specification and from the recital of the appended claims.

In the drawings: I

Fig. 1 is a side elevation of a perforating unit constructed according to one embodiment of this invention, and employing a bottoming countersinking punch, the unit being shown with the punch in withdrawn, nonworking position;

Fig. 2 is a fragmentary section taken on line '22 of Fig. 1 looking in the direction of the arrows, illustrating on an enlarged scale the structure of the punching, countersinking assembly and showing a workpiece dis,-

posed on the die in position to be punched and counterpre . "on the stripper50. V

sleeve 50 and is interposed. between the lower face. 54

Fig. 4 is a. section taken on line, 4-4 of Fig. 2 looking in the direction ofthe arrows; e e Fig. 5 is'a side elevation of a perforatlng umt constructed according to another embodiment of this invenr g- A ihh'viiiibh'in'iiiil height as high at 005" 'o'cuir 2;... with themost accurate manufacture.

Where there are a plurality of holes to be punched and countersunk simultaneously in a workpiece by a plurality tion, the unit being shownwith thepunch in withdrawn, V

nonworking position; i a r 'Fig. 6 is a section-taken on the line 6-6 of F 5,1 k.

ing in the direction of the arrows and illustrating the structure of the diemember of the ;unit; and

Fig. 7 is a fragmentary section taken on the line 77 of Fig. 6, looking in thedirection of the arrows, and showing the unit at the end of a working stroke of, the punch, and showing how the punch simultaneously punches and countersinks the work. a V v p ,7 Referring now to the drawings by numerals of reference, and particularly to Figs. 1-4 inclusive,"20 denotes generally a self-contained -perforating-countersinking 'unit constructed according to one embodiment of this invention. The unit comprises, generally, a O-frame 21, a'die member 22 and a punch-countersink-stripper assembly 23. .The C-frame 21 has an upper arm 25, in which the punch-countersink-stripper assembly is mounted, anda lower arm 26'on which the'die is mounted. The lower J arm26 has a pilot -pin 28 projecting downwardly from its underside. Pin 28 is adapted to engage a hole in the bed 30 of the press, on which the unit is used, to thereby properly locate the uniton the beds 1 Diemember 22 has a central-bore formed with a conicalportion 33, at its upper end, "and communicating with a idischarge chute 34 "throughriwhich slugs punched fromaworkpiece Wmay be discharged. V Thepunch countersink-stripper assembly 23-comprise's the tool 40,.the combined stripper and guide member 50,

a coil spring 55;and a secondary lifter spring :60. l Coil spring 55 surrounds the tool 40 andthe upper, neck por tion 52 of'strip'per 50, andis interposed between the head a 41 of the tool and the upper face 51 of a collan53 formed Lifter spring 60 surrounds the stripper of this collar and the upper surface of arm 25.; Lifter spring 60 ,acts to hold the assembly 23 in raised position (Figs. 1 and 2) to provide clearance for .the 'insertion'of workpiece W between the tool and die.

ReferringnoWFtO Fig. 3 it will be noted that the tool or punch rnember 40, instead of having just a1 punch tip thereonab'ove punch tip 42. Countersink portion 43 is complementary to the matin countersinkjportion 33 formedinthe die member 22. Countersink portion 43 connects the tip 42 of the 'tool with the shank '4 4'of the $0 1- The shank is mounted to reciprocate in and to be guided by. the bore of stripper sleeve S O which, in turn, is reciprocable in bore 37 of arm.2 5.' Above the-stripper sleeve the tool shank is of increased diameter as denoted the tapered countersink portion 43 of the tool, in coopera- -tion with the conical recess 33in the die, to :form' acountersink C in workpiece W. This is the operation thathas caused the difficulties heretofore in achieving a practical tool for simultaneously punching andcountersinking a workpiece. It will be obvious that, if'the'ram R of the ipressengages directly with the head 41 of the fpunoh, the

lieightof the 'arm26, the height of the die above its seat .on arm 26, the height or'length ofthetool, and 'the heig ht offthe stripper 50 mustbe heldtofabsolute accuracy to avoid a buildup jntolerance from one part to the other e underth'e rarn. iobv ously thisisfa physical impossibility 75 beabsolutely and1perfectly"made. Formerly, if apunch I or setting so that the pressneed not be set accurately.

of. perforating units, it .may become necessary even to heavy stop blocks inlthe press to prevent the ram from overloading the perforating units.

However, as also stated, thissimply transfers the stress from the punch memberto the bed and rain of the press, often causing failure offthe'press.

The difiiculties 'andjdis'advanta'ges of previousapparatus may be avoided in the: perforator countersinker of the present invention by providing punch-stripper assembly 23w'ith acap jr'ne'mber 65 which is adapted to be engaged byIramQR (Fig. 2 and '3 oftheipress. This cap member is fin the formof ahollow steelshell closed at one end and formed with a counterbore 66 of substantial depth.

Cap member 65'jnests overpunch head 41 and over strip per spring 55. ,;Because of the difliculties in providing anaccurate'outs ide Idimension on spring 55 and because of the change ofsizeofthespring from operation, the

shell is slotted axially infour ormore'places as denote'd at 67 to give thecap some resiliency with respect to spring-55. Slots 67 "extend from the lower end of cap to a point below where counterbore 66 be'gins.

The cap'member 65 Has a tight slidingfiton the punch head 41. .Its counterbore66forms a chamber in which is positioned a iplastiomernber 70, preferably made of nylon. The slug 70 has 'a diameter lessthan the diameter of 'counterbore 66, but its length is heldsomewhat, accurately. Accuracies of .010" and .012 are, however, quite sufficient for the reasons given below.

Onp'unching and 'countersinking operations, where the metal W to be perforated is .020" to .025" or less, the elastic member 70 serves .to transmit the force of the ram R to the punch head 41 from the cap 65; and at the same time'it provides resiliencybetween the ram and the punch. Underimpact of the punching" load it will deflect approximately 7, distorting elastically and filling the counter- ;b'orelor cylinder 66 between the punch head 41 and cap 65. The {plastic member 70 will therefore transmit the pressure required to press the countersink 43 of the tool "into the work piece "while at the same time providing suflicient elasticityto insure that a safelimit "stress on the machine tool eleirients will "not be exceeded. In other words, the :pla'sticslug 7 0 is, in effect, a safety valve preventing-overload of'the tool 40 or 'of the press from the perforating forces. i I

When the workpiece is more than .025", the nylon in compression, so that the'necessaryperforating force will be transmittedtothe tool without overloading the tool or the press. The compressibility. of the nylon pmvides easily.v aIlOth6I%2" of free travel of the tool over and above the ,5, inch or so of nee travel offthe tool provided by through the initial distortion of the nylon. What is,provided, therefore, is over of free travel Atthe samejime, member 70, transmitsa forcewell in excess ofjthat'requ redto"perforate and countersink the work, (w eh, m tnrn,rn eans that every; countersink will was a little short in length it would not make a proper countersink; and, if the punch was a little too long the punch would be placed under great stress and, at times, even the material would be cold extruded out of the countersink. This, of course, resulted in early failure of the implement.

The apparatus described will perforate and countersink a workpiece, simultaneously, with a degree of accuracy and efficiency heretofore unattainable. The resilient member 70 in the implement transmits the working force and-at the same time positively prevents excessive build up in stress levels in the punch-countersink member. This means that the implement will have a long life.

The use of stop-blocks on the press is no longer required.

Also, any necessity for grinding individual punches in an assembly operation is likewise eliminated, thus permitting interchangeability of parts. Further, the cost of manu-- facturing the implements is greatlyreduced because extremely close tolerances need not be maintained; Nylon member 70 need not be precision made. A commercial part constructed with approximately the desired length and diameter is sufficient, as is apparent from the foregoing description.

Referring now to Figs. 5-7, there is shown a selfcontained perforating-countersinking implement 120 constructed according to another embodiment of this invention. In this implement the resilient medium, to prevent excessive build-up in stress levels in the punch-countersink member, is mounted in the die instead of being incorpo rated in the punch-countersink-stripper assembly.

Implement 120 comprises a C-frame, such as previously described, having upper and lowerarms- 125 and 126. Upper'arm 125 has a bore 37, as before, in which a stripper sleeve 50 is reciprocable. The stripper sleeve is of the same construction as previously described. It has a lifter spring 60 interposed between it and the upper face of arm 125. It carries the punch-countersink 40 which may be of the same construction as previously described. ,In the present instance, however, no cap member and n0 resilient member are interposed between the head 41 of the tool and the ram. The head 41 of the tool is adapted to receive, directly, the force of the press ram.

Here, however, the die member 122 is slidably mounted in a bore 90 in the lower arm 126 of the C-frame or holder 121 being mounted on a nylon or other plastic sleeve 92. This plastic sleeve surrounds the reduced 92 also expands restoring die 122 to its starting position. During the above operation, variations in the length of punches or in the setting of the ram are compensated ,application is intended to cover any variations, uses or. adaptations of the invention following, in general, the

diameter shank portion 94 of the die member but in position of restisof less diameter than the diameter of bore 90. Under punching load thenylon sleeve first distorts to fill bore 90, and then is compressed to take the load. Thus, the perforating and countersinking operations can be performed accurately, as shown in Fig. 7, regardless of tolerances in the ram structure or length of the punch, etc, S hank portion 94 of the die member is guided in the reduced diameter bore portion 95 of arm 126 on the punching-countersinking stroke. Like die member 122, however, it has a protrusion 128 which engages in a hole 31 in the bed 30 of the press to hold the O-frame in position on the press. I

Die member 122, like die member 22 has a bore 32, which has a conical recess or mouth 33 at its upper end and which communicates with slug discharge port 34 at one side.

In the operation of the implement of Figs. 5 to 7, the nylon sleeve 92 operates essentially the same as the nylon .slug 70 of Figs. 1 to 4 to cushion and impart the punching and'countersinking force. When a downward force is applied to head 41 of tool 40, the tool, stripper-guide and stripper spring first travel downwardly in unison. When' stripper 50 strikes the workpiece W, the workpiece and the die 122 are carried downwardly with them, first distorting the nylon 92. As the nylon'distorts,

punch .40.moves relative tostripper 44 and spring 55 ing a slug therefrom. Continued downward movement of the punch causes the conical surface 43 of the tool to come into operaiton and form, with mating conical portion 33 of the die, a countersink C in the work. If the workpiece is thin, the whole operation of punching and countersinking will be completed during distortion of the plastic ring 92. If the workpiece is relatively thick the nylon 92 will be first distorted then compressed; and countersinking will be effected while the nylon is being compressed.

Upon completion of the working stroke and retraction of the press ram, stripper spring 55, which has been compressed between stripper 50 and the head 41 of the punch, expands to strip the punch from the workpiece. Lifter spring 60, also compressed during the perforating operation, then raises punch-stripper assembly back to its original position. When the load is relieved, nylon sleeve by nylon member 92.

Although member 92 distorts elastically and com presses on actuation of tool 40, it supplies sufiicient force resistance to permit the punch bit 42 to pass through the workpiece and for

conical portions

43 and 33 on the tool and die, respectively, to form a perfect countersink.

While the invention has been described in connection with twodifierent embodiments thereof, it will be understood that it is capable of further modification, and this principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention'pertains and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

'I-Iaving thus described my invention what I claim is:

1. The combination with a punch press comprising a ram and a bed, of a plurality of self-contained punching and countersinking units for punching andcountersinking a plurality of holes in a workpiece in one operation, each unit comprising a holder, a die mounted in said holder, a punch-countersink assembly reciprocably mounted in said holder in axial alignment with said die, said assembly comprising a too-l having an enlarged head 'at its upper end, and a punch bit and a countersinking portion on its lower end, a stripper guide member surrounding said tool and slidable in a bore in said holder, a stripperspring surrounding said tool and interposed between the top of said stripper-guide member and said enlarged head, a cap disposed over the head of said tool, said cap having a closed upper end and having a skirt portion depending from said closedupper end and surrounding said head and said spring, and said skirt portion having a bore and a counterbore, a resilient, compressible, plastic member positioned in .said counterbore and interposed between said enlarged head and the closed upper end of said cap, and said plastic member having a normal diameter less than the diameter of said counterbore, whereby upon application of a working force to said assembly said force will be transmitted from said cap to said tool through said plastic member, said plastic member first distorting to fill said counterbore and then being compressed, the

dam and a bed, of a plurality of self-contained punching and countersinking units for punching and countersinking a plurality of holes in a workpiece in one operation, each unit comprising a holder, a-die mounted in said holder,

a punch-countersink assembly reciprocably mounted in said holder in axial alignment with said die, said assembly comprisi'nga tool having a'n enlarged' head at its upperl' end,..and a punch andcou'ntersinking. portion nits lower end, a st ipper-wise iner'nber surrounding saidltoo and slidableiin more in; said, harden. a"; stripper-spring surrounding said tooland interposed between thetop, of said stripper-guide member and said enlarged head, a;

, cap disposed over said head andsurrounding saidr head,

said cap having a closed upper end and-having askirt portion dependingfrom said closed upper endland-said spring, and said skirt portion having. a bore and-a counter bore, and a plastic member positioned in said counterbore and interposed between the upper face of said enlarged head and said capytheportionof said cap surrounding andcountersinking units for punching and countersinking,

a'pluralityiof holes inn-workpiece in one operation, said,

units being, mounted on' said bed between said, ram and said bed, and eachunit comprisingaframe havingupper and lowerarms, a pair, of cooperating-members, ,one of said cooperating members being a 'dieand the other of said cooperating members being, a combined punch and oountersinking tool, said die being mountedin one armof said frame, a stripper member reciprocable on-theothei' arm of saidframe, said combined punchf'ancl' countr$iilkirig-to'olbeing reciprocable insaid stripper, membe r'in axial alignment With'QsaidCdie, resilient stripping'ineaiis interposedbetweeri said tool and-said stripper member,

said stripper sprin'g havinga pluralityqf slots extending a in the direction of said tool to makesaid cap resilient to aocomrnodatesaid spring, said plastic; member having a normal diameter less than the diameter of said counter bore, whereby :upon application of a working force to; said msemblysaid force;willpass from said cap to said'punph through said plastic member, said plastic member-first distortingto fill said counterbore', and thenbeing cor-r1 V pressed, the plastic members of the several unitsjper mit ting saidrarn: to actuate all said units simultaneously without over-stressing the tools of the several'unitsw A 3.- The combination with a punch press comprising a ram and a bed, of'a plurality of self-containedppnching' andcountersinking units for punching and countersinking a plurality of holes in a workpiece in one operation,psaid units being mounted on said bed between said'ram and said bed, and each unit comprising a C-framehaving compressible plasticelement surrounding said extension and mounted in said bore between said lower arm and and resilient meansforpreventing,over-stressing of said tool in a punching-countersinking operation, the last named means comprising-a resilient, distortable, compr'es:

under the punching load said plastic member is firstdi'storted to fill said recess and is then compressedto take ting said press to-actuajte 'all said units simultaneously said load, the plastic members of' the several units permitwithout over stressing the tool of any unit.

upper and lower arms, 'a-to-ol reciprocable'in-theupper arm of said frame, the lower'arm of said frame-having 1 a bore and a counterbo-re, a die reciprocable in said-lower arm in axial alignmentwith said tool, said ,die having an, axial extension of reduced diameter, an annular, resi1ient,

said die,,saidbore, die and axial extensionfdefininga chamber in which said element is positioned,'s'aid element engaging the periphery of said'extension but having a diameter substantially less thanthe diameter of said bore, a

said element being adapted to be elastically distortedby 6, The combination with a punch presstcomprising fa ram and raised, of a plurality of self-contained punching 3 and countersinking'units for punching and counter-sinking aplurality of holes in aworkpiecein one operation, said units being mounted on said bed between said ram and said bed, and each unit comprising a framehaving upper and lower arms spaced, from one another a pair of cobeing a die and the other of said cooperatingmembers being a combined punch and countersinlring tool, said die being mountedin one arm of said -frame, a stripper:

member reciprocable on the other armof said frame, said combined punch and countersinking tool being reciprocable in said stripper member in axial alignment with said die, resilient stripping means interposed between said; tool said die, when said unit is actuated, to fill said chamber and'thereafter to be compressed, thus providing aires'ilient cushion for preventing over-stressing of said tool, the

plastic elements of theaseveral units permitting said press H to actuate all said units simultaneously, without overstressing the too-1 of any unit. a V 4. The combination with, a punch press comprising,

ram and a bed, of a plurality of self-contained punching and countersinking units for punching andcountersinking a plurality of holes in a workpiecein oneoperation, said units being mounted on said bed between saidram and said bed, and each unit comprising a support, 'a stripper sleeve reciprocable axially in said support, a'tool reciprocable axially in said sleeve, said tool having an enlarged head at one, end and being shaped at its opposite end to perforate and'count'ersink, resilient strippingifneansfinterposed. between said head and said sleeveja die member reciprocably mounted in said support in axial alignment with said tool, said die member having 'abore formed wlth a recess to cooperate withthe'countersinking and perforating portions of said tool, said support being formed with a chamber in which saiddie 'member is i reciproeable, and a resilient, compressible plasticmemb'e'r mounted in said chamber and interposed'between said die member and said support, said plastic member normally being of smaller area than said chamber but being adapted to be distorted to fill said chamber and thereafter to be compressed on a working stroke of saidtooljthe,

plastic members of the several-units permitting. said press to actuate all said units simultaneously without over stressing the tool of any unit.

5. The combination with a punch press comprising 'a rain and a bed ,."of-a plurality (itself-contained punching 1 59,823 Crate Nov. 20, 1866 393,014

2,122,316 Ganio 1111x128, 1938 2,134,815 Elliott Nov. 1, 1938 2,189,208 Holland Feb.6, 1940 2,355,765 Wales f 1 Aug, 15, 1944 2,364,011 Wales Nov, 28, 1 944 2,374,436 Kennedy et -a1. Apr; 24, 1 945 2,380,485 Wales-"i2. July 31', 1945 2,602,360 Berninger- July 8, 1952 5 2,685,928 Bergh Aug 10, 1954 2,715,440 Havican et a1. Aug. 16, 1955 v FOREIGN PATENTS r 511,806 Great Britain .2 -Aug. 24, 1939 "979,961 France -Dec. 20, 1950 and said stripper member, and a resilient, compressible rl iefereiices Cited the file of this pat ent )7 UNITED STATES PATENTS operating members, one of said cooperating members 1