claim: 1. In a spark plug: an electrode; a compressible insulating sleeve disposed thereon; and a so-called ruIT-nech bushinlr surroundino, said sleeve elemeiit and prov'@ding a plu3o rality of spaced deformation zones which coiiipress the sleeve against said electrode. 2. In a spark plug, an electrode, an insulating sleeve disposed thereon, &-nd a so-called ruff - neck bushing surrounding said sleeve ele35 ment and providing a plurality of spaced deformatioii zones spaced apart by collars -",Iiieh exceed said zones in cross-sectional area. 3. In a sparlii plug: an electrode; an insu40 lating sleeve disposed thereon; and a socalled ruff-neck bushing surrounding said sleeve element and providi.ng a plurality of spaced deforili,,ition zones, the terminal faces of said busliing being respectively adapted 45 to engage an inner insulating assembly and ,in oiiter insul,,tting assembly. 4. In a spark plug: an electrode; an insulatin(r sleeve disposed@thereon, and a so-ca-Iled called ruff-neck bushing surrounding said -50 sletve element and providing a plurality of sl)aced deformation zonp-s, said electrode beiiiff pi@ovided witl-i a head and with an insut, lica(l'-"and said bush'ng. 1 55 5. In a spark plug: an electrode; an insulating sleeve disposed there6n; and a soc@illed ruff-neck bushing surrounding said sleeve element and providing a plurality of spaced deformation zones, said electrode be60 in(,r provided -with a head and with an insulating assembly interposed between said head and said bushing, and said insulating sleeve beiii(y surrounded in part by said insulation assembly. 65 6. For use in a spark plug comprising an insulation sleeve element disposed on an-inner electrode and within a conductive shell, a bushing comprising: a head; and a neck which is provided with a series of spaced inward-deformation zones. TO 7. For use in a spar-k plug comprising @n insulation sleeve element disposed on an -inner electrode and within a conductive shell, a bushing comprising: a head; and a neck which rovided with a series of spaced in- 7a ls TC ward d ormat-ion zones differing in crosssectional area. 8. For u% in a spstrk plug comprising an insulation sleeve element disposed on an inner electrode and within a c.onductive shell, a 80 bushinly- comprising: a head; and a neck which is provided with a series of spaced inward def ormation zones differino, in crossis n@ sectional area, the zone that ost remote f rom said head being easiest deformed. 85 9. For use in a st@arlc plug compnslnff an insulation sleeve element disposed on an"' inner electrode and within a conductive, shell, a bushing comprising: a head; and a neck which is provided with a series of spaced in- go ward deforination zones, said head beino, provided with shoulder which is shaped suitably for an interlocking enlyagement with a shell. 10. For use in secur-@ing parts tinder pressure in substantially concentric relationship: 95 a tubular element providing a series of annular zones of weakness spaced apart by pressure-transmitting collars. 11. For use in securing parts under pressure in substantially concentric relationship: loo a tube providin a. series of annular zones of weakness spacef apart by pressure-transmitting zones@-said zones of wealcness beina so graduated in.cr(>Ssse'ctional areas as to predetermine a sequence of collapse. 105 12. A spark plug comprisinig, withiii a shell, a so-called electrode spindle including: an interior mica, washer assembly and an exterior mica washer assembly, an electrode, ii mica sleeve; and a bushing so interposed be- 110 tween said assemblies as to serve as a retaining stop@-said bushing includin(f a neck which surrounds said slep_ve and which lias been collapsed at a plurality of levels, in leakpreventing relationship to said electrode and 115 said sleeve. 13. A spark plug as define d in claim 12 in posed between said bushing and said sleeve. 120 14. A spark plug as defined in cl,,tim 12 in which said shell includes a zone wliieh is so collapsed as to retain said busliing under an . increased compression upon cooling. 15. A spark plug as defined in claim 12 in I25 which a plurality of compressible elenients, additional to said spindle, are compressed between an element of said spindle aiid cooper@tinparts of aid shell, said shell coiiiprising a zone so coflapsed as to retain said bush- 130 l,itin(r assembly interposed. between said which a deformable protecting tube is inter-

1,8@6,404 ing ancl said compressible elements under increasing pi-esstire iipon cooling. 16. In the securing of parts under axial pi-essure and in concentric relationships, a nietliod which comprises: dispos@ng an cleryiciit wliieh is I)rovided with a series of zon@s favorable to radial deformation under a pi-edeter,-nined axial pressure in concentric relationsliip ivitli in element extendin(, theret, 10 through,. intei-posin- an insulating sleeve Ltween said ele,jiieiits,, and pi-oduciii,,), such axialpi-cssui-c, ul)oii 'Llhe foi-iiier element as to first 1)ositioii aiid theii deforin the same relatively to thc, eleiyieilt extendidg therethrougli. 15 17. In the securing of pai-ts under axial pressure an(I in conceiitric relationships, a riiethod m,hich coiiipi-ises: disposing an element i@,liiel-i is pro-v,lded with a series of zones favorable to radial deforniation under a pre20 determined axial pi-essure in concentric relationsliij) witli an elemeiit extendiiig therethrough, interposing an insulatiiig sleeve betweeii said elemeixts, inteiposing a deformable protectiiig tube bet-,veen the first mentioned 2r) eleniezit and sai(i insulating sleeve, and prodticing such axial pressure upon the former elemer.t as to first position and tlieii deform the same relatively to the clemezit extCDdiiig tlierethrough. I n testimony whereof I affix my sicmature. 30 HECTOR RABEZZIINA. 35 40 45 bo r)5 60

Patented Oct. 6, 1931 l p 8 2 6 , 4 0 4 UNITE.D STATES PATENT OFFICE HE, CTOR RABEZ7.ANA, OF FLINT, MICHIGAN, ASSIGNOR TO A C SPA3tK PLUG COMPANY, OF FLINT, MICHIGAN, A COMPANY OF MICHIGAN SPAR3K PLUG WITH A BUFF NECX 33UfJHING Application lued December The preseiit inveiition alms particularly at iiiil) l-oN,eiiic,iits in sl)ark pliigs of those types in wllieli some use is macie of so-called "eig,ii@ettes" or sleeves f rm d of mica or the ? e lil@e,-s,,iid sleeves being typie'ally disposed ill C(litact, with the inner electrodes of the sp,irk pltigs referred to; and typical embodiiiie.iits of th.is invention may involve solne iist, of a so-called "multiple-collar" or "ruffIt' 110,Ck" stop or bushing adapted to surround stich insiil-@ition and to be collapsed thereon at n-iore than one level,-to serve as a retainin'- stop, to prevent leakage, and to carry a shell. This invention aiins, in p@eferred embodinients thereof, at the provision and the utiliz,ition of I)ushinLs comprising coilcave or flat-topped and r@'unded lieads which ada@t them for interposition between inner insulation assembli'es and outer insulation assemblies@-- one. o'r both of said assemblies being preferably formed of mi'ca washers and a, deformable protective tube being p-referably so interposed, externally of the mentioned @@eigarette", as to apply a radially constrictive pressiire therethroii(rh, for a leakprei,enting ettect; and con@trictions or deforiiiation zones, spaced apart by rings or coll,ir, oii -,aid btishings, preferably differ in croqs-sectioiial are,,t in such a inanner as to ,icl- cutivel, i@pt fhe sanie to be conse y and tliei-ii-iol)lastically collapsed, to produce a series of annular and inwardl@-extending 'beads suitable to the purpose above referred t@). This invention should be understood to reI:ite iiot on@y to parts and prodiiets me]nti - on ed, I)iit to me,,i-ns and methods adapted thereto stigge,@-,t the use of collapsible "nuts" in the r6.tentioii of an exterior insulation assembly; ,iiid the iiqe of si-ich a thermoplastic collapse or consoliclation of parts of an outer shell as to liol(I nientioned inner parts permanently tlierein ; but it shoiild be understood that the i.il(,,iiti-oned zone-provided biishinos or tubul,ir,el(l.-@nent.s may be variously used; that the meiitioned shells are not necessari@y of oneI)ie" construction; and that the objects of this invention, including valrious alternati-ve to. Tlieilltistritionsherewithwillbefoun(I to suggest varioiis alternative aiid optional 7,1928. BerieLl No. 324,510. and oRtionRl features, may be best appreciated in connection with the following description, the apppladed claims and the, accompanying drawings. In the drawings: 55' Fig. 1 is a vertical or longitudinal section through one type of spark plug made in accordance with the principles of this invention. Fig. 2 is a view taken similarly to Fig. 1, 6o but showin- only an interior mica wa-sher assembly a@"'ru#-neek" bushing, and parts extending therethrough in readiness for an axial (lonlitudinal) compression@-to produce succe@@ivedeformatiorls or leali:- prevent- c, G ing co Ilapses of the weakened zones of said bushing. Figs. 3 to 5, inclusive, are vertical sections suggesting adva,utageous means and methods for use in subjecting @tbe weali:ened zones 7( of the mentioned @ushing successively to thermoplastic collapse. Figs. 6, 7 and 8 are vertical sections showing some of the various types of collapsible nuts arnong which a selection may be made 75 in the securing of, for example, an exterior ins . ulation assembly in engagement with the mentioned bushing. , Fig. 9 is a similar view, illustrating the result of a deformation of one of the men- so tioned nuts by an application of pressure therethrough,-as may be done subsequently to the steps shown inpigs. 3, 4, 5. Fig. 10 is a similar view-, intended primarily to show a step (which May follow r,5 steps illu@strated'in previous figures) whereby a special shell bas been secured to the mentioned bushing; but this view is utilized also features hereinafter referred to. I)c An electrode spindle (whose parts are shown in elevation in,Fig. 10) is illustrated in Fig. 1 as cornprising, in addition to a tensionable central electrode element 11, having an integral head, a so-called "ruff -neck" bush- i)5 ing, adapted to serve as a, stop for both an interior insulation assembly and an exterior insulation assembly,-the former comprising a small-aperture sheaf 13 of mica washers and a larger-aperture sheaf 14 thereof, and: loo

2 1,826,404 -the latter comprising comlparable sheaves 15 and 16,of similar laihinated insulation. The respective small-aperture sheaves 13 -and 15 being adapted snugly to fit the electrode element 11, the larger apertures provided in sheaves 14 and 16 are intended similarly to receive a so-called "cigarette" 17, of mica or the like; and the present invention is to be understood to relate more particularly to the 10 construction and mode of use of a "ruff-neck" bushing 18 coniprising, in addition to a, flatpped head 19, a somewhat elon(rated neck ovided with a series of rings or collars 20, 21, 221 which s6rve to space apart weakened 11) zones 23, 24, 25@--adapted to be inwardly collapsed by axial pressure applic(l through said head. A protecting tube 26, shown as approximately equal to the bushing 18 in lenoth, is 20 adapted to respond to constrictive pressure produced by thermoplastic or other deformation of the zones 23-25; a special."nut" 27, adapted to transmit a predetermined pressure before undergoing collapse upon the electrode 25 11 , may be permanently secured, as by welding; ,tnd the entire spindle so frovid'@d may be secured ivithin any suitab e spark plug shell. The shell S is shown as comprising aii ex30 ternally threaded lower or cylinder-enga(ring seciion S' and upper or wrenchreceiving section S"@-the latter including an inwardI.y deformed flange 28, engaging a roun(Ted shoulder 29 of the busbiiig head 19; similar 35 shell sections Se' and Se" are shown in Fig. 10; and a presuinably final compressive action may be obtained by a, thermoplastic collapse of intermedi ' Ate zones 30 and 30c of said shells. In advance of the deformation 40 of flan(,e 28 or 28c and/or the collapse of ,i wea]Kened zone 30, 30c, an additional compressible eleineiit such as a -gasket 31 (or gaskets 31c, 31c'), and/or a slieaf of auxiliary insulat . ion, of the general character su(,- 45 gested at 32c, Fig. 10, mav be so interposed as to under(ro a final compression incidentally to a coolin- of zone 30 or 306, siibsequently to the collai@se of the shell S of Fig. 1, or incidentally to any similar steps, as dia(rram50 matically su(-r(rested in connection with Fig. 10. Referring to Fig. 2, it will be seen tbit the respective colltpsible or deformable zones 23, 24, 25 ire so formed, by varying the cross55 sectional areas tbereof, tliaf'tbe lowernio,@t and innermost of these zones is the easiest to subject to an inward cleformation by an a:pplication pf pressiire, or of pre-sure -.ind electric heating. after ,in interior iiisiilttion 60 assembly, such as that comprisin- mica tsheaves 13 and 14, bas been diily coinpresse(l. As su,-(Yosted in Fi(,. 3, tlio electro(le be,,id 12 n Z, may be s itiii- element 33, rted die, 65 during a clatively to a lower die 35,-as may be effecte-d I)y hydraulic or other means symbolized by tL cylinder 36 from which projects a piston rod 37 whose mo'vements may be controllable by rnanipulation of a valve lever 38; and, 70 upon the attainment of the desired conipressive effect, an electric current. conti-olled by a switch 39, may be so passed throtigli the bushin- 18 as to assure, in view of the nientioned compression, a collal)se of the lowel-most weakened zone 23. As also sit,-,,(reste(i . in Fig. 3, taken in donnection with Figs. 4 aii(I 5, the valve lever 38 and the switch 39 iiity be so connected as to assure a suitable tiliiin(, of successive advances -of the die 34 ,tnd I 81) coordiiiation of such advances with app@opriate movement of switch 39; and it will b(,, understood that, upon a proiiil)t cooling of the collapsed zone 23, a repetition of described movements (the zone 24 boin(r then 8,-) of less cro--s-sectional ai-@a than the zone 23) may be effective to collapse the zone 24,-a third depression of the die 34, followed by a closing of the switch 39, bein(' effective to collapse the uppermost zone 25 of the bu@bing 90 18. The weakened zones need iiot differ by more than (say) twenty thousan(Iths of ali inch; and sufficient coolin(y ocetirs very quickl@. Pre@-sures of about 2000 pofinds are sufficient, in this connection. 9 An inner electrode assembly completed iii the general manner illustrate@i in Fig. 5 i-nay obviously, be employed in any one of a variety of ways, its permeabil ' ity to oils, aci(is rtn('I/or gases being practically zero; biititis sugceste(I 100 in Fi(,rs. 6-9 that, the in,iil',Ition slie@tves 16 and 15 and a collapsible "ntit" 27 beinff sticcessively slid.on an upwardly extencling an(] threaded or roiigheneld part 40 of th(@-,Olectrode 11, a siiitable depression of any upp@r 10r) die 34, followed by a moment,,ii-y passaye of etirrent tbroiigh a redli'ced zone 41 of rn said "ntit". may so secure sai(i "nut", pref6ritbly by welding the ,;ame in place, as to complef@ a spindle s-Liitable for conipt@ession in a col- 110 lapsible shell substantially as suagested in Figs. 1 and 10. Initially slidable "nuts" shown in.Fig- 6 and 7, an4 shells such is are shown in P ig-9. 1 and 10 bein@r rospectivoly eltimed in com- 115 panion appli6ations S. N. 324,513 filed December 7,1928, a-nd S. N. 324,511 filed Deceinber 7, 1928, attention may be'hereiii called to cert,,tin a(lvantqges thit may.-be ol)t,,tizie(I by providin@_, (eitli@r throu-Ii a special con- I'@o figtiration of the iipper end of ,I.tensionable electrode elemeiit 11. lla or llb, or - throti(Y]i a special distribution of metal in a "iillt!l having a weake'ned zone, as su(,Ygested in Fi,,,. 8) fo@ an initial and tl)read-strippin(y or 125 el similar contact, between the nqt and minor leetioiis upon a tensional)le element, pro n n-ia@ @y or oiily in a region opl)osite a lower or inner flan(ye 42 (or 42a or 42b) of the "niit" Sucli a cons@ruction may be f avoted, for ex'- 130

1,626,404 3 ample, in case an electric etirrent is to be passed, by wav of a collapsible zone 41'(or 41a or 41b) from an upper flange 43 (or 43a or 43b) thereof to and through such tensionable element; but this detail of construction, to predetermine a path of initial flow , as also the technique that may be employed in securing the resultant spin --le within a shell of any preferred character, is ob70 viotisly of sub@rdinate importance as compared With the described improvements relating to the @orm and use of bushing 18. Primarily for the purpose of emphasizing the breadth of the field within which ihe uiore iniportaiit features of the present inveiition are suitable for employment, an electrode spiii(Ile or assembled imit of the general character above described is shown in @ig. 10 as disposed within a shell that is po20 sitioned between dies 100c, 101c, these and associated elements being adapted to cooperate in producing an inward collaps-e of said shell at 30c aiid/or a deforination of an upstanding flange 28c, if the latter is provided, 25 for a, lockin- engagement with a roun(led shoulder 29c tn or atiy suitable part of "ruffneck" or other bushing 18c. Assuming that inner and/or outer assernblies have been previously sliaped and pol30 ished to any desired degree, final thernioplastic operations involving dies 100c, 101c inay result in the desired final product; but Fi(r. 10 is incidentally employed to illustrate additional and optional featu'res. r4 or exam35 ple, this fl(rure su(y ests the use of an iipper in 119 shell section So" initially distinct from a lower section So' that is receptacular in form,--to provide a seat for the auxiliary sh(,af 32c of mica washers, or the like. This 40 sheaf 32c, if used, may be placed and retained undercoinpression through an inder insulation assei-nbly which snugly fits within a cylindrical surface 103c; and walls adjacent said auxiliary sheaf are shown (with 45 exaggeration) as respectively providing a slight inward i,nd a slight outward tap6r toward the line of their intersection,-these ?ptional features tedding to assiire a wedging fit at the otiter edges of the auxiliary 50 asseml)ly ai-id to f acilitate an excepti6nally Iiiah compression at the inner edlyes tl@ereol, f avorably to heat coiiduction froi@i' the reujon opposite the electrode head 12c. m It may be of iiiterest to note that (whether 55 or not the mentioned auxiliary assembly or any a-Lixiliary assembly is disposed in the bottom of a shell section, and whether or not the lower portion S' or Se' of any shell is employed, durin ' !,y asseiiibly, as if it were a part 60 of the stationary die 101c) an inner eleetrode assembly, a "cigarette", a protecting tube and a bushing 18c being disposed in any preferred way upon t tensionable electrode element Ile, and an outer insulation assenibly being added at any suitable time, pressures appropriate not oiily to the comi)acting'of one or both the mentioned insulaelon assemblies but to the co apse of aid bushing, or itsequivalent,may . appliedeitherthrough die 100c or th'roii a die 34c, assumed to be 70 separately mova e. The comp@itcting of the auxiliary insulation 32c, if used, and/or the collapse of any gasket 31c, 31o' may preferably occur, if the pressure-limiting die 330 it. used, after the complete compacting of the 75 mentioned inner asseinbly and the collapse of some or all of the weakened zones 23c, 24c, 25c; and the provision of alny vertically movable and yieldably supported guide element 104c, having limited play relatively to so die 101c, may ordinarily be disposed with. Pressures such as 4200 pounds may be employed in the collapse of nuts and shell flanges or weakened zones, as described; but the anges28,28.cm'aybecollapsedcold;and s5 collapse of any nut @7, 270, although it may ordinarily occur as a final step in prefornia,ion of a complete inner electrode spindle, may obvio'usly be effected, subsequently to a use of insulation-compacting pressures ap- go plied theretlirough, at any time when the bushiiig 18 or 18c is suitably supported or-advanced, and either by means of a current returned through an inner insulation-contactill,- flan(re as suggested in Figs. 6 and 9, or by conduction through the main electrode and its head, as su(,,gested in Figs. 8 and 10; and it.inay also be noted as theoretically possible, in case opposing siirfaces are suitably forn-ied (and whether or not a plurality Of gasket,.4 are interposed as su,-gested at 31c and 31c', Fig. 10) to let inward deformation of an upstanding flange 28c, for an interlocking effect, precede mentioned collapsing operations; but, whether or not gaskets such as are lo5 suggested at 31, 31c and 31c' and/or any auxiliary sheaves of insulation are to be silbjected to an especially high compression, a collapse such as that suggested at 30 and at 30c may advantageously be a final therino- iio plastic step,- to instire a maximum sealing and compressing effect, due to contraction upon cooling, as well as to pressure applied while hot. As suzlested in Fig. 10, this final thermo- 115 plastic @i@p mav be so executed (whether or not the shell sectioiis So' a'nd So" are initially so distinct, as suggested by dotted lines 105c and 106c, as to preveilt premature conduction therebetween) that the intermedi- 120 ate deformation of the shell results in an additional interlockin- and/or an actual weldino, of the sliell to ifie bushing therein; but it will be understood that, as in the siml)le and practical forin shown in Fig. 1, the col- 12a lapse at 30 may be so executed as to avoid any risk in re,,ard to the seating and proper functioning of gasket 31, incidentally compressed; and, whether or not the lower die 35 of Figs. 3-6 inclusive is, in practice, a 95 100

4 1,826,404 lower section of a shell element adapted preseiitly to undergo deformation as described (ol)tionally in the same operation but subseqiie,ntly to collapse of a bushing and/or a r, iiiit) it will be iinderstood that especial imI)ortance is herein attached to the form of the described "ruff-neck" bushing and to the described constructions and methods whereby the seqiience of series of collapses of weakio oned zones (whether provided in bushings or other tubular elements) may be predeterinined. Althougli the foregoing disclosures include complete details of but a limited numi ber of practical embodiments of the present invention, alternative constructions and modes of assembly beinr incidentally sugt' ,-ested, it should be understood not only that various features of the present invention may 2o I)e separately emploved but also that numerous modifications, additional to those sug gestpd therei@, may easi.ly be devised,--all -within the spirit and scope, of the present invention. 25 I