US 2354480 A
Description (OCR text may contain errors)
l July V25, 1944.
P. F. ROS
FASTENER lFiled April so, 1942 2 Sheets-Sheet l July 2.5, 1944- 1 P. F. RossKMANN 2,354,486
FASTENER Filed April 30, 1942 2 Sheets-Sheet 2 INVENTOR. qerygkqossfrnarny BY Q ATTORNEY the manufacture of airplanes K as temporary rivets for assembling or clamping substantially vibration-proof grip.
i Patented July 25, l1944 Peter F. Rossmann, Snyder, N. Y., assignor to Irving Bossi, West OrangaN.` J. ,A
Application April so, lua-sensi No. 441,153
y s claims. (C1. ssa-5l The present invention relates to improvements in clamping devices and methods of making such devices, more particularly to devices of this type also known as skin fasteners as used, e. g..-in and which serve together perforated metal sheets and other structures-preparatory to and to facilitate the riveting y thereof. Y y
f In my copending application, Serial No. 384,- l0
461,'filed December 21, 1941, entitled Clamping device,and my U. S. `Patent No. 2,339,881 of January 25, 1944, entitled Skin fastener, I-have described devices of this character comprising :essentially a body member or support provided 16 with a circular opening', equal in diameter tothe perforations in the sheets'to be clamped, and a retaining or clamping elementv arranged in relatively movable relation with respect to said and re-assembled to speed production and Vfor the quick interchange of repair parts.'l
,Still a further object is the provision :ofa lfastener whichf'can be safely and readily ,installed in andrrernoved from the sheets to 'be clamped "with thev 'aid of a suitable skin fastener plier orequivalent device.
Another Objectis to provldeavskin fastener for use in riveting operations, especially in they fabrication of airplanes Av which will t. cause the perforations oftwo or moresuperposed platesy or sheets to become readilyr aligned duringy the insertionof the fastener andwhich will cause the fastener `to` be firmly'locked against the. edges oi. the perforationsfinthe insertedgor clamping position to'in'sure a firm connection and vibration-free grip of the sheets or plates capableof i withstandingthe forces of a riveting operation. t
support, .said retaining element having apair'of $0 resilient` legs or prongs provided with shoulders and projecting through said opening. A spreader interposed between said prongs and arranged in relatively fixed relation u o projects'through said opening withtlhe combined g5' to said support also' cross-sectional 'area'of said prongs and inter'- posed spreader being-'equal toa'nd filling saidHV opening. Normally, the spreader holds said prongs and shoulders in retracted spaced-apart l Anotherobiect is `to provide a fastener of improved construction anda special plier for in stalling and removing the samefrom the aligned holes to increasefthe operatingsafety and efficiency.
'The above and further' objects and aaivaniv tages of the invention will become more apparent from" the following l detailed description t taken with reference to the accompanying ldrawings formingj part of this specificationv and wherein:
- 'f rFigui-ieri' is a vertical cross-,sectionalview of position against their natural bias by the provia0 sion of suitable spring means interposed between said spreader and retaining element and urging said prongs and shoulders towards said si'ipport to clampr a, pair of sheets therebetween, while allowing said prongs and shoulders to pass be# yond said spreader and be` operated towards each otheragainst the action of said spring means in such a manner as to permit of ready insertionin and withdrawal of said prongs from the aligned perforations in the sheets or other struc- 0 tures. y f
An :objectof the present invention is to pro-ff vide a device ofthe above typev embodying fea'r tures of improvement to increase its efficiency and reliability Ain operation. i g
Ae'further'object is the provision of a skin fastener constructed in such a manner as to enable nuick and readyk application to and removal from v the -perforations in the sheetsvto be clamped or ff assembled. l
l, Another obiect is to provide a` fastener `of the; above type which while small in size will permit of vapplying considerable clamping pressure betweena pair of perforated skin sheets sufficient to withstand the forces of a riveting operation.
Another object is to provide a fastener aclanted to hold two ormore perforated sheets or other` structures in perfect alignment in a tight and askin fastener embodying'the principles of the invention; Figure 211s a partial cross-sectional yview taken on lined-12 of Figurel.;v Figure ,3l is a horizontal cross-section taken` on line- Sie-lof Figure 2; Figure 4 isan isometric view ofthe spreader element forming Aan essential partA of ,the fastener; Figure 5f is 'a' partial view similar to Figure 2 showing a modification o f a skin fastener according to thelinvention; Figure '6 isa. `horizontal cross-section taken on line 6 6 of Figure 5'; Figure 'l is lan isometric view showing the additional element provided according to Figures 5 and 6,; Figure 8 is an elevational view of a fastener and improved operating'plier showing theposition at the endr ofthe first stage 45 duringfthe insertion cycle; Figure 9,-i's a partial stma further object is to provide a fastener 60 which can be quickly and easily' disassembled proved skin fastener which, `in the example isometric view of they improved plier shownv in Figure 8 Figures' 10 and 11 arepartial views:
of the'up'per and lower parts, respectively, of theV fastener. illustrating the cooperation with 0 the improved plier;v Figures 12'` and 13 are partial cross-sectional views showing modifiedhousings for fasteners suitable for usewith flush rivets and counter-sunk sheets as/shown'inFigure 14; andFigure 15 shows Aanother improved housing for askin fastener in accordance with the invention.
Y Like reference characters identify like.l parts throughout "the different views of the. drawings;-
"Referring to Figuresi, to 4, the numeral in' indicates. the bodyfmember or support' of lmy imsubstantially vibration free grip. For
shown, takes the shape of a cup or shell of circular cross-section provided with a flange Il at its upper open end and having a curved or outwardlyvvaultedbqtbm l2. "Ihef'latterhas a central circularopening I3 having a 'diameter equal to the diameter of the aligned holes or perforations in a number of superposed perforated structures such as a. pair of sheets A and B shown in the drawings to be temporarily assembled or clamped together.
I have further shown a clamping or retaining element Il constituted, according to the present improvement, by a unitary resilient wire member of semi-circular or segmental cross-section Abent into a U or hairpin shape to form a pair of ysurfaces facing.
legs or prongs with their flat l each other as shown in Figure 3. 'I'he prongs in the example illustrated are'so shaped as to comtions Ila adjacent to the bent portion Hd followed by intermediate sections Hb spaced at a lesser distance than sections Ila and a pair'of lower or outer sections llc havingoutward protuberances or' shoulders I5 and being bent inwardly at an angle to an extent normally to leave a slight'opening or spacing between the opposite faces of said shoulders as shown at I' in Figure 8. This spacing is so chosen as to enable an easy insertion of the prongs and shoulders I5 through the perforations in the sheets A and B in the manner described hereinafter whileproviding a sufficient resiliency to cause members with slightly mis-aligned peri'orations to slide s'uiciently to become readily aligned during the insertion of shoulders hi.l j y The retainerv I4 in the operative position of the fastener as "shown in Figure 1 projects through the perforations in the bottom l2 and tions vI 4a so vprise a pair of substantially paralleleupper sec- 4 Hb and Mc is holes in the members A and B to be clamped, and
`ii a smaller spring of lesser `diameter "points y on upward without jamming and interference with the easy application and Withdrawal of the fastener.
Since the distance between the prong sections predetermined by the size of the since furthermore the size of the spring 20 is the clamping pressure to beobmembers A and B, that is requiring in most cases a spring having a diameter substantially exceeding the spacing distance between sections IIb and Mc, it is advantageous to increase the spacing between the upper prong secas to conform to the inner diameter ofthe spring as shown in the drawings in order to balance the entire assemblyV in a mannerreadily understood. On the other hand,
thelegs of prong l5 may be'straight from the and all the remaining elements like cup I0 and cap 2| may be reduced in size accordingly. f
The aforementioned feature of the, invention together with the employment of a sufficient clamping force provided by a coiled tension spring of `adequate strength and theconcentration of the pressure to a narrow edge zone near the perforations in` the sheets A and B to be described presently make it possible to temporarily connect of the sheets. In the case of very thin sheets as in the sheets A and B and the'sections lHc are l.
forced into a more or less straight shape in such inner edges of the sheetperlthe provision of a TA-shaped portion or extension I6 intercammlng with the forations through spreader having a posed between said prongs and a cross arm Il beang against the inner surface of the bottom I2, This camming or wedging effect in a lateral direction against the edges rof Athe perforations forms an important feature of the present invention in that it insures the perforations in the sheets to be closed tightly, thereby holding the sheets in perfect alignment and in atight and this purpose the length of sections llc is so designed and related to the spreader portion I'S; that is, that points y at the beginning of the inward bend of sections Hb are at a predetermined distance from the upper edge of the spreader in the retracted position as shown in Figure 1 as to obtain a desired alignment and camming of the sheets without damage to or permanently. deforming lthe In practice, this effect is obtained if the length of the lower bent sections llc is of the order or somewhat less than the combined thickness of the spreader-arm Il, the bottom l! and the sheets A and B to be clamped, or, as pointed out,
upper surface of thespreader or is positioned adjacent to the inner surface of the end wall I2 position of said retainer as shown with the inner edges of the sheet perforations upper end of a used in airplane construction,A this results-inl a taut skin surface. free from the slightest bulge or buckling effects asheretofore experienced when 1 usingifasteners of inferior construction.
I'he undersurface of the spreader cross arm I1 is Shaped' to Conform to the insidev of bottom-|2 to normally. allow the spreader to be rotated relative to cup or at least follow accidental twist exerted thereon through the prongsfby the spring 20 or due to inaccuracies in the plier or other ap" plicator and other causes. In this manner `jamming or breakage of any part is avoided, while the bottom I2 cooperates with the spreader at all times in maintaining itfin a predetermined relation to the cup and the holes in the member A and B, respectively.
I have furthermore shown means Atovrelieve both the spreader and cup of excess stress ex,-l erted by the spring 20, consisting in the example shown of an inverted cupped or dished washer Il placed over the spreader portion or cross arm I1, said washer being provided with a pair of diametrical recesses in the cylindrical part thereof adapted to receive the outer ends of said cross arm (see Figure 3). The upper or flat part of washer lai's provided with a suitable opening or perforation for passing and guiding the prongs I 4b of the retainer Il. I i
The upper sections Ma of the retainer I4 prof ject beyond the shell I0 and have secured thereto a head-piece or cap 2i by the aid cfa crosspin 24 passed through diametrical bores in said cap and embracing the upper bent portion Hd of the retainer. Cap 2| is slightly tapered outwardly and provided with a curved top 22 and a lower annular recess 23 formed by a, depending flange, said recess adapted to receive the coiled tension spring tobe described presently. Pin 24 is locked in position by a slit resilient ring 25 placed in a circumferential groove ofthe cap 2| to enable easy as- Sembly and dis-assembly of the fastener during manufacture and for the interchangejof repair Iparts'The' locking ringv v25 is :advantageously made of. resilient steel wire and slit with the open ends biased awa-y from each other to insure a tight nt and to allow of "easyapplication 1 to'and removal from the groove inthe cap A coiled tension springv 20 of suitable size enlcircling the retainer I 4 has its upper end arranged toengage lrecess 23 as pointed out and has its lower end bearingagainstvv the upper vsur-` A lface of the washer I8 thereby .resilientl'y` restraining `both the :washer I8 and spreader jll,
Il against axial or longitudinal movement. 'Spring' 20v is designedto provide a suflicient force to urge the projectingpart of retainervll in a direction inwardly of the bodyfor shell I0 Ato rmly lock shoulders Vlagainst the under surcondition of ythe The dished washer I8, besidesgtaking. the
thrust out ofthe spring 28 and relieving the shell IILhas the further advantage that the springv .pressurel is applied over a complete 360 circle 'comparedl with thesubstantially limited pressure area 'or-bearing surface of the cross arm f l1 if,
the washer were omittedQfThis: not- Y. only v-increases the totaleilective pressure at'theJconi tact or. pressure zone near the edge of the sheet rperforatlons but results in a stiffening up Vand balancing of the entire assembly andy improve'- yment Vof the locking eilect and `vibration ffree connection of the sheets, Furthermore, lthe :washer will relieve the :shell I0 of excessive wear resulting in increased efficiency and Aprolonged byucombiningthe spreader and washer into. a
.singleunitsuch as by giving the crossarm I1 the shape of a flange or disc provided with suit- :ablev recesses or openings'for passing and-guiding the vprongsections IIb. *Such a spreader having a disc shaped Ilangeas shown ingreater detailin my above mentioned copending appli- .eatlonfj-.Serial-No 384,461,v is 4ditllcult andexpenlsive in manufacture in that it involves ama- 'Aas the'sgifireader portionV I'I. wherebythev spreader may follow the lrotation of the retainer` Ilprol,vided the'iorce applied is vsuch as to overcome v; or pressure areav between the shoulders IS-and theadjacent edge zonefnear the perforation in .the Vlower skin sheet B. In this manner, 1unlnecessary,.pressureiareasoutside the effective or clamping zones' are avoided, resulting in a smaller clamping spring and a cor-responding reducr'tion` of theuall-over sizeof a fastener designed rforjholes of a4 given diameter anda predetermined` clamping force. The latterA is determined i by vthe fact foundfrom experience, that for =1/8" holes lit should havejsucha value *thatl no less than'l'j, lbs.v are required toseparate. a combinationsheet thicknessof 11,", vor no less thanabout `35 r lbs.r to separaten combination sheet, thickness ofjg'f* tomaintain a perfect and vibration f freefconnectionupf the sheets or other-members iduring. a riveting operation.yThis minimum life of the fastener. A similar eect is obtainedA Y chining operation comparedv with the simple `stamping of a T-shaped spreader shown in Eigure 4.of the present application. On the other* hand, the latter hasy the disadvantage asrpointed rout, especially in a clamp embodying a heavy compression spring, thaty only a small portion of the spring bears against the narrow spreader cross. arm Il; resulting infrequent canting and vunbalancing .Y of both. the spreader and theen'- tire clampl structure and other drawbacksfwell v understood.
By the use of a simplewasher llhaving at least one recess adapted to receive `the spreaderv cross armas shown and rdescribed and' which mayalso bevmanufactured by a simple stamping operation, there is obtained the equivalent of a flangedspreader with all the attendant advantages thereof as pointed out.
If desired, the lower edge of the washer l8 may be formed with a, sharpv corner as shown in the drawings 'at-,points :c in which case the latter l will, dig in orf pressagainst the inner-surface of vshell I0 thereby preventing rotation of *spreader-' -Ii-I] by accidental rotation of retainer Il against the friction between the spring 20 and washer I8. Alternatively, the lower edge .of
.washer I8 maybe rounded `'so-as to more nearly Vconform to the bottom I2 in the same mannerl `clamping force and lthe necessary;` sizev ofl the Spring lbeing therefore a givenquantityy-it vhas been;` the object and purpose of the invention fto `provide .a construction-,oa skin fastener which, while .complying with the abovevrequiremen'ts. results in a. device of' smallest possible- -sizeffand ,bulk, and which, nevertheless,4 is 'most ,felllcient and :durable even after extendeduse :and tcan be applied to and withdrawn@,fromthel perforations inty the sheets or otherfmemberto be clamped in a quick vand simple manner ."in'addi- -tionito other advantageous features-described .landkzapparent from the remaining* partsifof' the specification. v y l y c Y f An alternative construction for providing 4a concentrated* pressure area near the perforations .isfshowni-nA Figures 5. 6 and 7.1. :According to the a latter. I.y providey anv4 additional -ilange'd sleeve l"element having a cylindrical portion'z21 `,and 'a flange vor annular portion 28v (see-Figure 6);' saidc'y-lin'- drical portion being inserted inf'theJper-fora'tlo'n I3-` in the bottom I2 which latter linithis casema'y kbe'ilat vinstead'- of c'urvedffand'said flange 281re`sting against the inner wall of1 bottom lIZand-beking in turn Aengaged by the-spreader portionfIT rand ,invertedlcupped washer I8 in substantially thev same manner as'shown infligure l.. It will be understood lthat in-this case they innerI diameter of thesleeve 2'I should besubstantially equal 'to the-diameter of the holes in the sheets Av and VB: ori'l in .other jcwords. vthat it shouldl "conform substantially tot the diameter of the combined cross-section/iof' the spreader :portion 'I6v and prong sections |40. Prong Il, cap 2|, washer I8, andI spreader 11,6; yI1 form a complete self-con'- tainedsubassembly land inrorder to hold this subas'sembly in thebody `orshell III,depress`ions orindentations 30 ,fsee'Ffigure 6)- are appliedto fthe.,outerpart of the shell close to thek upper edge of thewasher-k I8. These .depressions which may take' the.form ofa continuous groove *servev to retain y.the washerflt andspreader I6, I1 in the Shelly( andnmaytbegapplied after the r'washer'has beenplacedin-position or previously in which f case the washer is. placed. in position by pressure scribedhereinabove is the fact that it can be readily and easily assembled and dis-assembled by unskilled labor. Thus, for assembly, the retainer I4 is passed through the opening in the washer Il and the spreader It, I1 is then inserted between the prongs of the retainer'so that spreader portion Il equally projects from the opposite sides of the prongs and engages ,the recesses in the cylindrical portion of thewasher Il. `'I'his sub-assembly is then dropped. in the shell I so that the washer and spreader will rest against the inner surface of the bottom I2 oi' the shell. Spring20 isthen placed around the retainer I4 to engage washer IB and cap 2I applied to the outer bend Idd of the spring which is then compressed in a suitable jig or by means of a suitable skin fastener plier soV that the upper bent portion Ild` aligns with the diametrical perforation in the vcap to enable" cross-pin 24 and locking ring 25 to be placed in position.
' Upon subsequent release of spring 20, the retainer I4 will be moved in an upward direction 32 of the plier is provided with an annular recess 35 adapted to receive the flange II of shell I0, thus insuring a perfect alignment and balance .counter-sunk sheetsA' and B' compared with the standard rivet perfcrations of sheets A and B as shown in Figure 14. These designs comprise a spherical or conical projection 8l and 31 (Figures 12 and 13, respectively) from the bottom'I2,
adapted to engage the counter-sunk rivet holes to properly align and centralize the fastener in the inserted position. This typeof design furthermore reduces the amount of over-hang proj'ection of the prongs of the retainer VI4 and the spreader portion Il, thus making the fastener more rigid and safe for counter-sunk rivet applications.
shell construction having a depending' cylinbottoxn I2 adjacent to the opening .Il thereby.:
' holding the fastener in assembled condition.
In order to apply the Vfastener to the holesof two ormore skin sheets or other structures, such as sheets A and B shown in the drawings, the
Finally, `I have shown in Figure 15 a modified drical flange 38 extending from the opening in the bottom I 2, said flange being integral with vthe shell III` and taking the place of the separate same is compressed by the aid of asuitableapplicator or plier which may be of standardQor preferably of the improvedconstruction according to the invention and described in the following with reference to Figures 8` and l1.V In the compressed position theprong sections llc and. shoulders Il passing beyond the spreader are' operated towards each other as shown in Figure 8 so as vto enable their insertion through the holes in the sheets A and B until the bottom I2 of shell Il rests against the upperfskin sheet A the shoulders I5 in substantially, the same way.
as during the assembly of the fastener. Y
For disassembly, cap 2I is again compressed towards cup I0 by means of a plier or in a special jig. In this position ring 25 and' pin 24 may be removed, enabling awithdrawal of cap 2l and resulting in expansion of spring 20 to its uncompressed condition. Spreader portion I6 is then pushed into the cup so as to4 cause shoulders I5 to approach each other and. allow of withdrawal of prong Il through the opening Il. The plier shown in Figure 8 has. an upper jaw II adapted t'o engage the top of cap 2| and a. lower bifurcated jaw 32 engaging the underside of flange II of the shell III, said jaws being pivoted at 33 in a manner `well understood. Anisometric view of the plier is shown in Figure 9. The improvement according to the invention resides in the provision of a recess 34 in the Upper jaw 3| adapted to engage the tapering cap 2| of the fastener, said recesshaving a tapersornewhat less than said cap to secure a slight wedg- `V ing effect and spacing of the curved upper surface 22 of cap 2l from the inner surface of said recess Il as shown more clearly in Figure 10. In
this manner, the fastener is prevented from slip'- j flanged sleeve 21, 2l of Figures 5 and 7 to obtain a pressure concentration near the holes or perfo- Arations of sheets A and B in the manner de- ,scribed. The design ofv the fastener may otherwise be similar to that shown in Figures' 5A to `'I This modification has the advantage of eliminating the indentations or depressions I0 in the shell I0 thereby facilitating they assembly and disassembly of the fastener. f
A As will be evident from the foregoing, there is providedby the invention a temporary rivet or skin fastener especially, although not limita- Vtively, suited to hold superposed sheets and other structures securely in position for riveting and in such a manner that the vibrations caused by the riveting operations will not loosen the fasrepairs when after long use interchange of parts may be required. This results in a substantial saving of vboth time and material. With a standard or special skin fastener plier for compressing the tension spring the fasteners can be Veasily disassembled and reassembled withoutv special tools.
According to a further feature of the invention, the parts of the shell I0 mostly liable to wear out, such as the flange I I and bottom I2, are subjected to a localized hardening process by heating the same by means of an electric induction heating coil and subsequent cooling or Y, quenching in oil or the equivalent. In this manner, these parts, i. e., the perforation I3 subject to friction with the prongs and flange II which has to withstand the pressure of the plier or other tool, will have the required strength the substitution of equivalent metal alloy than the hardened parts.
While I have shown and described a few desirable embodiments of the invention, it is understood that this disclosure is for the purpose of illustration and that various changes in shape, proportion and arrangement of parts as well as elements for those herein shown and described may be made without departing from the spirit and scope of the invention as set forth in the'appen'ded claims. l
able through said opening having a pair of resilient legs, said legs having inner parallel portions and free end portions provided with shoulders and .each bent angularly towards the other to normally leave a predetermined spacing therebetween, a spreader having a cross arm bearing against the inner surfaceof said end` wall and a depending portion projecting through said opening and interposed between said legs to form therewith a cross-sectional area of, a diameter equal to the diameter of the perforations in the members to be clamped, and a coil spring encircling .said retainer having one end engaging the inner end of said retainer and having its vother end arranged to resiliently maintain said spreader in bearing engagement with said end wall, whereby to draw said legs inwardly of said 1. A clamp for temporarily assembling perfo-l l rated members comprising a body having'v an end wall provided with an opening, a retainer having va pair of resilient legs slidable through said opening and provided with shoulders at the outer ends thereof, a T-shaped spreader having a cross arm and a depending portion, said cross arm bearing against the inner 'surface of said end wall and said depending portion projecting through 'said Opening and being interposed between said legs to form therewith a cross-sectional areal of a diameter substantially 'equal to the 'diameter of theperforations in the members to be clamped,
" an inverted cupped washer having a flat portion overlying said cross arm and .a cylindrical nsnge provided with diametrical recesses, the ends of said cross arm engaging said recesses, and a coil encircling said retainer having one end im n engaging the inner end of said retainer and having its other end engaging said washer.' whereby v to draw said legs inwardly of said body and to clamp the perforated members between said shoulders and the outer surface of said end wall', said legs upon `compression of said spring to force said retainer outwardly of said body projecting beyond said depending portion and being operable towards each other to enable insertion through and removal from the perforations in said membe f 2. A clamp for temporarily assembling perforated members comprising a body having an end wall provided with an opening, a retainer comprising a pair of resilient legs, said legs having f' inner parallel portions and free end portions provided with shoulders and each bent angularly towards theother, a spreader in relative nxed relation to'said body having a depending portion projecting through said opening and interposed between said legs to form therewith a cross-sectional area of a diameter equal to the diameter of the perforations in the membersI to be clamped, and spring means interposed between the inner end of said retainer and said body to draw said legs inwardly of said body and to clamp the perforated members between said shoulders and said end wall, the angularLv bent end portion of each of said legs having a length approximately of the order wherebythe apex of said angle of bend is positioned near the inner surface of said end wall in the retracted position of vsaid retainer.
3. A clamp for temporarily assembling perforated members comprising a body having an end yall provided with an opening. s retainer slidbody and to clamp the perforated members between said shoulders and outer surface of said end wall, the angularlybent end portion of each of said legs having a length substantially of the order, whereby the apex of'said angle of bend vis positioned near the inner surfacel of said end wall in the retracted position of said retainer.
4. A clamp for temporarily assembling superposed Vperforated members comprising a sleeve having an inner diameter equal to the diameter of the perforations in the members to be clamped ders at the outer ends thereof, a T-siiaped e spreader having across arm bearing against the ,inner surface of said' flange and a depending portion projecting through said sleeve and interposed between said legs to vform therewith a f cross-sectional area oi a diameter equal to the inner sleeve diameter, a cupped .washer having diametrical recesses overlying said cross arm, the ends ol' said cross arm engaging said recesses, and a coil spring encircling said retainer having `one end engaging the inner end or said retainer and having its other end engaging said washer. to ldraw said legs inwardly of said sleeve and to clampv the perforated members between said shoulders and the outer edge oi' said sleeve.
5. A. clamp for temporarily assembling perforated members comprising a body having an end wall provided with an opening, a retainer having a pair of resilient legs slidable through said opening and provided with shoulders at the outer ends thereof, a T-shaped spreader having a cross arm and a dependingr portion, said cross arm bearingl against the` inner surface of said end wall and said ldepending portion projecting through said opening and interposed between said legs to form therewith a cross-sectional area of a diameter substantially equal to the diameter of the perforations inthe members to be clamped. a washer overlying said cross arm, said washer having at least one recess adapted to receive and to lock said cross arm with respect to said washer, anda coil springenclrcling saiduretainer and having its other end engaging saidwasher, whereby to draw said legs inwardly of said body and to clamp the perforated mempending portion and being operable towardseach other to enable insertion through and removal from the perforations in said members.
' rma r. Rossmann.