US2455903A - Dimpling mandrel - Google Patents

Description

DGC- 7, 1948 H. R. FISCHER DIMPLINGl MANDREL A Filed 4.April 4, 1944 y TLV ff m lik xNvENToR Aww/P0 /a//' Efo/[42 Q4 ATTORNEY Nw wfg s Q ATHFI Patented Dec. 7, 1948 UNITED rSTATES PATENT vOFFICE l v 4` Il l' 2455Q9o3 ,i

t {DIMPLING MANDREL Howard R. Fischen` Detroit, Mich., assigner Ato Chicago Pneumatic v Tool .-Company, yNew York,

N. Y., a corporationof New Jersey Application April4, 1944, Serial No. 529,479

y 1 l :A This invention relates to the dimpling'of metal sheets aroundv rivet holes therein in order to adapt the latter for receiving a oountersunk vorA flush type rivet by utilizing a draw pin or mandrel when connected to a powered dimpling tool for drawing a pair of dimpling dies together upon said sheets to dimple them. The invention refers particularly to a rotatable mandrel to be used withmeans for speedily inserting the mandrel vinto one of the two dimpling dies preparatory to dimpling the metal sheets by said dimpling tooland'also;4 for quickly removing said mandrehfollowing the dimpling operation and lreinserting the mandrel in the die through another rivet hole.

Flush rivets are used extensively in aircraft construction on the exposed surfaces of thefmetal skin which forms a cover for the fuselagefwing sections and other structural `elements` `The metal sheets, usually made-,of aluminum alloy,v are mounted in place and the overlappingportions thereof are provided with registering perforations formed by drilling or punching.- `The sheets are dimpled around-the holes to provide recesses for receiving the heads of the rivets. The resulting structure has the advantages. lof in. creased strength of the rivet joint and decreased wind resistance. v Y,

According to one method of dimpling, which is considered to be the most effective for certain typesof Work, a draw pin is rinserted from one side 4of the sheets through the rivet hole and the projecting end on the other side is grasped with a power tool which applies pressure toopposed dimpling dies through the application, of. tensile force to the draw pin, "Assoon a'slthe dimple is formed, the draw" pin or mandrel'r is withdrawn and moved to the next hole.` The cycle voi" operation must necessarily be repeated in krapid succession because of the thousands of holes required to be dimpled in a single airplane. j l y Thus it is a main 'object of thisfinventionto provide facilities `for speeding up.v the dimpling cycle as alwhole by facilitating'l speedyj initial insertion of the mandrel into the one 'dimpling die and alsoy final Withdrawal ofsaid' mandrel from the latter in such leiiicient manner'v as to save time during each cycle'of the operation.` l It is also an object to minimize any loss of vtime resulting from occasional breakage of the mandrel and to allow rapid removal of the broken mandrel parts from the die and replacement byvfa new mandrel. n A special feature of the invention is the use f l a screw type mandrel with a correspending'screw type dimpling die and a handle'to allowinsertion y' of the mandrel with simultaneous placing'ofthe@ 6 claims.' (el. 153-41) die preparatory to subsequent dimpling of metal sheets in very close quarters where but narrow working space is available.

1 Other objects and features of the invention will lappear more fully in detail from the following driving -tool in condition to receive the mandrel;

,-Fig; 2 is a similar yview kof the tool with the mandrel in placeand fully inserted into a dimpling die bymeansof said tool;A

Fig. 3 is an end ,elevation of the tool of Figs..

1 and2 as seen fromthe left or chuck end;

Fig. 4 is a side elevation of the shank a threaded portion,... integral i therewith and an associated plungenthe view`- showing the parts turned degrees about the longitudinal axis of the shank from the position of said parts in Figs. 1 to 3;

Fig 5 is anend elevation of the same parts shownV in liig. 4 as seen from the left end in the latter view; and

Fig. 6` is aside elevation of. the mandrel alone ofFigs. 1 and 2 when turned or rotated 90 degrees aboutits` longitudinal axis from the position of said views.

When kthe mandrel is yto be inserted into a rivet hole in oneor more metal sheets to be dimpled, it is vusuallyiirst screwed into a holder and then passedthrough a dimpling die, etc., as disclosed in thePatent No. 2,333,418, granted to the present applicant November 2, 1943, and thereafter individually into each of a plurality of such holes in the sheets and each time engaged by a power operated dimpling tool provided with a second dimpling die to eiect dimpling about each hole. During such operation the mandrel remains in the vholder whichk is used to shift said mandrel from4 one hole to the next, being a convenient means for handling the mandrel and facilitating dimpling they sheets at high eciency.

However, frequently certain narrow spaces are encountered in or between the metal sheets in which no adequate room is found for placing the mentioned holder, and in which not even the full length of the mandrel alone can be accommodated, sothat the latter must obviously be inserted into the rivet holes from the working side, that is', from the same side upon which the dimpling to'oloperates. As the dimpling tool forms no part of this'inve'ntion, it is superfluous to describe for the above mentioned patent discloses it in detail,

butin any case, the mandrel has a series of serraby said dimpling tool and a thread upon the other end.

With the foregoing objects in View and in order to make it feasible to dimple metal sheets rapidly, even in narrow portions of structures including them, it is proposed to insert the mandrel through the metal sheets from the dimpling side directly into a dimpling 'dieibyf-sorewing"itiintlo: the latter when it'is'locatedon'the other side ofsaid sheets,

while using a holder or handle to shift said die from one rivet hole to the next and render the entire operation speedy and practical, as-willnzoiw be specically set forth.

Referring again to the drawings,=amarnirel` inserting tool, generally indieatedfat-f rihas -a shank l l adapted for insertion into the chuck f2' of a hand drill or preferably ofgafgfiankeettype screw driver by which to rotate the tool under control and at will. The shank Il isfintegral with the threaded portion or member I3 which is of greater diameterthan that Vof the'shankand which -,has an 'internal Ibore Mii-nto ,which al'hol low shank portion l5 ofamandreldriying plunger I6 :extends .An interior Veimansion spring l1 occupies fthebore Miin member Isand also Va bore lil insaid plungerandactivelytends .to urge said :plunger out of-said 'jeoire M. "The driving plunger IS has a cylindrical head IB with opposite i depending portions lor along-ations 2l iFig. E5, on two si-desextendingiinto-fthe open slots v'Z2 in the threadedA m-ernber'llbwhich virtually forms a chuck coreforbase, fin/ ordertozprevent relative rotationlof the -fplungerwith respect` to the rest of the tool and especiallyitofthesshank tLwhile allowing free axial movementfof said plunger into and out of member 'I3 fthe action of spring I'I. Y

The front end 42:?,I of thenplungerheadis of coni-r cal formy and diametrically acrossthesam-elis -cut awedge shaped slot -llladapted to receivefone end of the mandreL-to'be described,-`said-endeengaging against agronp ofchuckv jaw-s 2f5iwhosegrear ends 26 are correspondingly'inclined toftlagainst'the conical end 23 ofsaid head. 'Ihevjawsare-,retained in mutual associationby means cfa chuck casing 321, internally threaded at 28 andscrcwed in upon the th1eads'29 ofm'ember Hi' againstgthe ring 3.o seated against the rear ,flange 3| onsai'd core A:member i3, the @casing 4Zljhaving a pair .of Qphosite lflat portions V32 .adapting the `casing 'for engagement by ,a wrench to screw the same von said member 13. flThe chuck.'casin g at the 'forward end hasra forwardly tapered internal yyi/)all 33 engaging against ,inclined portionsrl 'Upon the exterior forward endsof `the ,chuckpjaws in order to bring thelattertogetherbymeans of the drivingplunger Vit .under theforward .bias ordmF pulse4 of .the jawclosingspring ,IJ when thedatter isallowed toact freelyupon fsaid ljaws through said -plunger. l

vIn order y,to fopen .thechuok .jaws endallow .i11- sertion into the chuckof a .drawpinorimandreL generally indicated -at3,5, a.;manually Asl'iiftable sleeved@ is slidably mounted externally -on the chuck casing -and rearwardly provided .with -an inwardly turnedange 3J 'servingas a-forward stop against the -rearend of the chuck casingtitlr to imitforward moyementfof `said sleeve. AThe latterhas an internal thread `33 iwith-n theiforwardiend into which the-chuck ca p. 39.is screwed, while being preferably 4rknurled l,upon the exterior thereof to z improve the grip ,thereon v:(-not `shown) and-providedwith-apair of-.sidegapsfor openings 4l Lto-allow access tofthejlat sidesif32 of ,thefchuck Y casing ifor Igripping :the-latter ,fby :a Wrench when assembling or disassembling the tool. The cap 39, while having a substantially flat outer face 42 is provided with a rearwardly directed frustoconical portion 43 occupying the center area of the interior of said cap around a central aperture 44 in the latter and abutting the outer ends [l5 of the chuck jaws which are inclined toward ,thetdhuckrcasingto correspon'dto the inclination 'of -said frustocni-cal portion.

Obviously, if the sleeve 36 is seized by the hand hof the operator as indicated at 46 in Fig. 1 and `drawn:rearwardly while the tool is held against rearward movement (the shank l l being clamped ytl'n'ersfeeve willrbec'aused to occupy the retracted 4position'shown-in said Fig. l in contrast with the Y normal ,positionindicated at 4l in broken lines, andthe interior central portion 43 will force the jaws 125 "rearwardly, and thereby the driving plunger i6 rearwardly against spring il. Due to the simultaiieous release -of .the .jaws from intimatefcontactawith fthe :converging internal wall 33of the Achuck-casing `consequent upon the Aseparating'or :wedgingraction of the conical portion 4B :against 'sthe yinclined forward ends 45 of the. jaws 1in fcooperati-on Kwith the simultaneousV separating -orwredgingfaction ,of the conicalfaceor end e213.' ofi-'the plunger Aagainst thecorrespondingly inclined rearrends =2l'of'these jaws, the latter will be-separatedtoa maximumlimitposition wherein they-fengageagainstthe interior cylindrical wall: 4810i the-casi-ng,1which provides adequate spacing apart of the 'jaws for release or ,insertion of a mandrel.

'The-mentionedmandrel is'provided at one end with'aregularly spaced'series of circumferential serrations "HB (Fig. `6) adapting said end to be effectivelygrippedV and pulled stronglyby alpower operated fd'imp'ling tool,-the-extreme end having two inclined Lside :portions 5I converging :suiciently to vform-a wedge shaped end adapted to t into the transverseslot '241m the -end of the plunger head so that rotation of the tool as a whole 'byimeans vof 'the screw driver or hand drill connected to'theshankll will also cause'positive rotation of vthe mandrel. vThe other endiof the mandrel is provided with a thread BZfadapting-the lattertobe'screwed into ya-di'mpling'die 53 having a concave Jportioniil'into which the metal will be projected during dimpling while the sides of said die have opposite at portions or slots y55 cut ltherein to adaptthe die for engagement by a bifurcated holderor handle 56 having an open slot51 upon ".the'end of `its longer limb' while the shorter limb 59 on'said handle has Va similar slot 6L IThe handle may thus be tted to the diefatteither end., the die fitting into the slot in the end concerned so that v.it may be shifted from hole 'to hole as thedimpling proceeds and the mandrel is released therefrom. The .chuck jaws are `provided .with .rows of teeth 1 6'2 corresponding 4to .the serrations 49 upon theemandrel. When.,the latter is inserted by first forward vwhich rthereby also .forces rthe vjaws f or-4 Ward and together ,upon the serrations of the mandrel, with the result that the latter is firmly...

gripped ,in the tool ready for positive -rotation therewith `upon rotation .of the tool .itself by attached. 4 Y

means .of thefscreew 'driveror Adrill to which itis,

A Ii then the metal about'the-rivet hole '631m a sheet metal-structure 64 is to be dimpled, thelatterfhaving'garather restrictedv or narrow space 65,',5'thf-die'li53 may be introduced into said space aridfsupported by holder 56 with a threaded hole 66in said diey registering with the hole 63 in the sheet metal, -when the mandrel inserting tool above-described and with the mandrel projecting therefrom may begplacedy opposite the rivet hole with thev threaded end 52 of said mandrel initially inserted into said hole. When the screw driver or hand' drilly is operated`l to rotate the chuck and consequently the mandrel, the threaded end 52 of said mandrel will engage in the hole 66 in said die and be quickly screwed into the latter until the slotted end 61 of the mandrel projects beyond the die. If at this stage the outer sleeve 36 is manually withdrawn again as indicated in Fig. l, opening the chuck, the tool may be withdrawn While the mandrel remains in place in the rivet hole with the die supported thereby on the other side of the sheet metal within space 65. If a power operated dimpling tool (not shown) having a concave or frusto-conical dimpling die complementary to the die 53 is then thrust in upon the mandrel and caused to engage the same and the dimpling tool operated to dimple the sheets, the latter tool may then be released and the tool embodying the present invention again engaged upon the mandrel for removal thereof from the dimpled rivet hole and the die within. In order to effect this result, the screw driver or hand drill etc., is of course operated to rotate in the opposite direction from that first used to insert the mandrel into the die, and with the mandrel thus released from the die but yet held in said tool, the die is shifted within space 65 to the next hole and the mandrel again caused to engage in the die by means of the present manually rotated tool which is then again released for the dimpling operation by the power -operated tool.

Upon occasional breakage of the mandrel, which is likely to occur somewhere along the threaded end 52 thereof, the slotted end 61 is readily engaged by a common screw driver and the broken part removed by unscrewing the same from the die which is obiviously then immediately ready for receiving a new mandrel.

As it is well known among those skilled in the art that a mechanical screw driver of the Yankee type can instantly be adjusted for righthand rotation when the handle thereof is depressed toward the work and as easily adjusted for rotation in the opposite direction under the same conditions, the adjustment for the right hand rotation will obviously be used during the screwing of the mandrel into the dimpling die before each dimpling cycle and the adjustment for the opposite direction when unscrewing said mandrel therefrom after each dimpling operation is completed.

While the mandrel inserting tool has thus far been described as a device or attachment to be inserted into the chuck of a hand drill or a mechanical screw driver to replace the screw driver bit of the latter, it is self-evident that the tool can readily be combined with, and be built in as part of, the mechanism of said mechanical screw driver, if so desired. It is equally evident that the tool may be made wholly or ln part of steel, bronze or of any other materials as conditions may suggest.

In a divisional application, led March 15, 1945, Serial No. 582,955, there are claims to a mandrel inserting tool for screwing and unscrewing a 6. threaded mandrel into a correspondingly threaded dimpling die as illustrated and described in this parent application.

What is claimed is:

1. In combination, a mandrel having a shank, a threaded. end portion, and a serrated end portion including a series of annular anges, the outside diameter of the shank, of the crests of the threads, and of the annular flanges being substantially equal so that the mandrel may be passed through an aperture of substantially suchv diameter in a work sheet, and a die having a threaded bore to receive the threaded end voithe mandrel, said die being slotted for the reception of a handle to hold the die in position for the threading of the mandrel therelnto.

2. In combination, a mandrel having a shank and a threaded end portion, the outside diameter of the crests of whose threads is no greater than the outside diameter of the shank, a die having a slot and a threaded bore, the bore being adapted to threadably receive the threaded end portion of the mandrel, and a holder insertable into the die slot to hold the die on one side of a sheet for threadably receiving the mandrel upon insertion of the latter from the other side of the sheet through a perforation in such sheet.

3. A combination, according to claim 2, in which the holder has an extension handle adapted to move the die through a space substantially equal to that dimension of the die which is in the direction in which the mandrel is inserted and to hold said die in position for threadably receiving the mandrel upon the insertion of the latter through a perforation in a work sheet.

4. A combination, according to claim 3, in which the mandrel is formed with a portion including a series of annular flanges adapted to be gripped by a pulling tool.

5. In dimpling lapparatus for sheet metal, a mandrel for holding a threaded dimpling die in operative position against a work sheet, said mandrel comprising a shank portion, a threaded end portion having a kerf at the extremity thereof, a serrated end portion including a series of annular ilanges, and a tapered extension to the serrated end portion adapted to transmit to the mandrel rotary motion imparted by a slotted tool for the screwing of the threaded end portion of the mandrel into the threaded dimpling die, said threaded portion, shank portion and serrated portion all having equal diameters, said serrated portion being adapted to cooperate with a correspondingly serrated tool to pull the die member into position for dimpling after the mandrel has lbeen threadably connected thereto.

6. In dimpling apparatus for sheet metal, a threaded dimpling die; and a mandrel for holding said die in operative position against a work sheet, said mandrel comprising a shank portion, a threaded end portion having a kerf at the extremity thereof, a serrated end portion including a series of annular flanges, and a tapered extension to the serrated end portion adapted to transmit to the mandrel rotary motion imparted by a slotted tool for the screwing of the threaded end portion of the mandrel into the threaded dimpling die, said threaded portion, shank portion and serrated portion all having equal diameters, said serrated portion being adapted to c0- operate with a correspondingly serrated tool to pull the die member into position for dimpling after the mandrel has been threadably connected thereto; said dimplingdie having means associated therewith for the positioning of said die for :amamos FJEEESE Feb. 19, '19.01

-Name Date tLcxzen `Aug. 15, :1941 .Caminez QSeptO, Fischer .;Nov.2, :1943; Nordgren :Dem .-21, 184:3 Hurst Mar-.4.28, 1944, Tuttle ,-Dec. 26, -Amtsberg :July `l5, .1194? FOREGN PATENTS Country Date GreatBrtain June-26, .1941

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