US1311261A - Spark-pltjg and process for making the same - Google Patents

Description

C. H. BRASELTON. SPARK PLUG AND PROCESS FOR MAKING THE SAME.

APPLICATION FILED MAR. 5.1915- Patented July 29, 1919.

3 SHEETSSHEET 1 INVENTOR m a Q/WM' y f C. H BRASELTON.

SPARK PLUG AND PROCESS FOR MAKING THE'S'AME.

' APPLICATION FILED MAR. 5. 1915. 1,31 1,261.

w// /M/ 7///A1 Patent-ed July 29, 1919.

3 SHEETS-SHEET 2 llVI/ENTOR WITNESSES. P 5

C. H. BRASELTON.

SPARK PLUG AND PROCESS FOR MAKING THE SAME.

APPLICATION FILED MAR- 5.1915.

Patented July 29, 1919.

3 SHEETS-SHEET 3.

lll'llllll INVENTOH UNITED STATES PATENT OFFICE.

cnns'nm n. BimsEL'roN, or DAYTON, omo.

SPARK-PLUG; AND FOB. MAKING" THE SAME.

To all whom it may concern":

Be it known that I, CHESTER H. BRAsEL- TON, a citizen of the United States, residing at Dayton, in .the county of Montgomery and State of Ohio, have invented certain new and useful Improvements in Spark-Plugs and Processes for Making, ,the Same, of which I declare the following to be a full,-

clear, and exact description.

. This invention relates to spark plugs and the processes for making the-same. The inventions herein disclosed are specifically applied to spark plugs but some are capable of a broader application.

The spark plugs in this application are based upon an entirely new idea in spark plugs and processes of making the same.

and process of making it, which in its broad- -est aspect is capable of application to other articles other than spark plugs; a novel Being basic in this respect the disclosure in. this application extends to Various points of advantage in the construction of spark plugs and in the processes of manufacturingithem. These include a novel gasket construction process and construction in regard to secur-.

ing the central electrode of-a spark. plug in placein the insulator in a gas tight'manner;

- a novel-construction and process as regards fastening a terminal cap on the upper end A of the insulator in place on the same or in fact, if desired, eliminating the separate cap completely; a novel construction and process in regard to mounting a second. electrode onthe insulator so that when the insulator is assembled inplace in the shell an electrical connection will exist between the second electrode on the insulator so that when the insulator is assembled in place in the'shell an electrical connection will exist between the second electrode and the engine casing;

' a construction and process for providing an 'insulator with one or more electrodes with a metallic shell provided'with threads for securing it into an engine cylinder; and a novel construction and rocess for practically providing-.a brit'fie substance with durable threads.

The above obf'ects are accomplished;

loy'ment of an idea of fying the material and breaking up the liquid into infinitesimal portions and deposit 'ing such. portions upon the surface to be. coated by blowing theliquid material by a specification of Letters Patent.

- spark plug.

of a ribbon.

PatentedJuly 29, 1919.

Application filed March 5-, 1915. serial No. 12,359.

blast of gas under pressure against the surface to be coated to which it adheres so that a film of the material of any desired thickness placed upon the material to be coated.

With the above and other incidental objects in view, my invention consists further in various details of processes and construe tions more fully hereinafter described and pointed out in the appended claims.

In the drawings which accompany and form part of this specification Figure his a view pf one form of spark plug'made in accordance with this invention.

Fig. 2. 1s a view showing my novel method of making-this spark plug.

F g. 3. is aview of a. different form of. spark plug which may be made by my process, a metal shell being sprayed upon an in v sulator ofany desired shape, the'threads in theext'erior" of the lower end being ent in the metal after it is sprayed'upon the insulat0r.. u I

Fig. 4. shows a. diflerent form of spark plug in which theinsulator is attached to a she1 1- through the medium ofsprayed mate ria Fig. 5. is a vertical section through the pllig of Fig. 4. 1 v 1g. .6.v is a View of the insulators of Figs. 4 and 5. v 1 Fig. 7. is still another view in which the insulator isjatta'chedto the shell through the .medium' of'sprayed material; the. insulator being of a different-form.

Fig. 8.'is a View of a different form of Flg. 9.- 's a yertical section through the plug of Fig. 8. 1

- F1g.:l0. is a view of the insulatoruof Fig. 9, showing gasket materialsprayed upon the seating shoulder of the insulator and conducting material may in the form of a ribbon or completely surrounding the insulator,

be sprayed uponthe lower end of the insulator. This View"; also s oyvs an electrode wire sprayed"fast: -.to';the lower end of the porcelain" -at' its two ends,one end. at least ducting material leading to the sprayed gasket. I.

Fig. 11 shows Ian elevationof the insu lator of Figpl0 at right angles, as it'would appear with the-condilcting material on the lower'end of the insulator'being inthe form beingpreferably connected with the conducting ribbon to form a spark gap at the side.

,Fig. 14. is a cross section of the lower end of the insulator below the shoulder, of a case in which the conducting ribbon completely surrounds the insulator.

Fig. 15. shows the lower end of an insulato with a second electrode, in the form of a-ring or band, sprayed thereon.

Fig. 16. shows amanner of attachi-n a fibrous gasket to the shoulder in the inside of the spark plug shell.

Fig. 17. shows a similar form of fibrous gasket attached to the insulator.

Fig. 18. shows a thread detail which may be used in connection with spark plug shells in which threads cut in harder metal are sprayed with a softer metal so as to obtain a better gas tight threaded connection.

My inventions are based upon the idea of spraying one materialwith another by heating the material to be sprayed with -to liquefy it and then blowing the same into the form of a spray and against the surface to be coated It is necessary that the substance to be covered be clean and preferably to an extent porous. I find it very easy to spray clean earthenware or-glass which has a rough surface, and very well unglazed porcelain ware such as iscommonly used in spark plug construction forinsulators. The surfaces tobe sprayed must of coursebe free from oil or grease. Such materials as well as metals can be readily sprayed with metal by heating the metal into the form .ofliquid drops and blowing-same in the form of a spray against the clean surface to be sprayed. A coating thick as desired may be thus made on the material being sprayed threadedpart, with any desired metal, such as copper or brass, soas to form a metal 7 sheath of any vdesired thickness over the by continuing the process for the required length of time. In this spraying operation the minute particles of materialwith which the substance is being-coated seem to pene-j trate into all the tiny pores of thejmaterial being coated and; to adhere to the dame permanently and very firmly so'that there is no --air or gas passage between the surface" sprayed upon and the layer of sprayed ma terial. @This operation is not limited- 'ito spraygng non-metals with metals but enemeta may be sprayed" with another metal; or a metal may be sprayed with a non-metal which may ,be reduced to a liquidform and blown upon the material to be sprayed. Or

a non-metal may be sprayed with another n onsmetal. The spraying o peration maybe confined to: small areas are surface to be sprayed by coating or coveringthe-area's ex t posed that are not desired to' besprayed the that which is to be sprayed may be protected from the spray by wool to which sprayed. meta-l does not adhere owing probably to the inability to completely free the wool 1 from oil or grease.- In spraying or coating spark plug insulators on certain area onl I first glaze the areas not to be coated, having J5 the areas to be coated unglazed. Holding the insulator in the spray of material then will result in the unglazed areas beingpermanently and 'endurably coated while-the spraying material will not adhere to the glazed surfaces and is readily removed.

I make use of the just described process in various ways of advantage in'the designingand constructing of spark plugs for in- 'ternal combustion engines so as toimprove their service and design, as well as cheapen their cost of manufacture In Fig. l, 1 is aninsul'ator adapted foruse in spark plugs which may be made of the'usual porcelain or any other desired insulating material. This is made with any-form of exterior desired and with threads-2 cut in'the insulator at the lower end. It'was not a very practical proposition to provide, before my invention, insulators suitable for spark plug use with threads on their exterior for screwing into a threaded opening in an engine cylinder because the t reads in the brittle insulator, while capable of being cut or molded, will not stand b'ut will be broken and chipped so as to ,be unserviceable. It was also not very practical heretofore to engage the insulator directly with a wrench for screwing it in place owing to the brittle 1 nature of the insulating material. I find it very practical, however, to do both of these by constructing the'insulator with any dc sired exterior and with threads, by spray- 1n lia le to be readily broken including the surfaces to be protected. The contour of the threads in the insulating material before very satisfactory results are secured anda very cheap construction as well, by thisrocess. If desired the threaded part may e. sprayedwith a softer'metal such as copor coating the surface of the insulator .per, the other part, which may be any harder'inetal in order to'provide a better gas tight connection at the threads. In I spraying threaded or'ot'her areas where relatively accurate thickness should be pre ably have the spray being blown upom the rotate, preferably with a certain deterserved throgighout the periphery,'I prefersurface at 'a relatively constantspeed afid- I mined speed by machinery, the threaded the spray in the manner In Fig. 2 the member to be sprayed so that an ,even coating will be placed upon the threads or any rotating object throughout the periphery.

In Figs. 1 and 2 the metal sheath is indicated by the character 3, this being in the exterior form of a non-circle atthe upper end to receive a wrench for use in screwing theplug into place in the threaded'opening.

This sheath will take. the form of the insu1a-.

tor inside if its surfaces are fed equally to above described. operation of sprayingwnthe threaded insulator is shown. In tlns view 4 isa holding block for a rod 5 of copper or brass or in fact any material with which the insulator is to be sprayed. The lower end of the rod is adapted to be heated so that the material will form in drops at the lower end, by a torch T, such as an oxy-hydrogen torch, adapted to give suflicient heat to melt the rod 5 at its lower end. As the drops are formed at the lower end of rod 5 they are broken up into the form of sprays and blown in tiny particles against the surface to be sprayed by means of a blast of gas, such as nitrogen. or air, issuing from the nozzle '6 under pressure with a speed depending upon the gas used and the material ,with which the object is to be coated. 7 When the spray hits the object to be coated it .isdriven into the the insulator so as toform a spark gap 8 bevlously sprayed upon to which the tiny parpores thereof or the pores ofv the layer pre ticlesstrongly adhere and in a way weld to .thefsilrface and to the adjacent particles in a firmbond. Continuingthe operation'increases the thickness of the sheath sprayed. In Fig.2 I show an electrode- 7 fastened at its ends to the lower'end of the insulator and electrically to the lower end of the sprayed sheath 3 by a spraying operation. This electrode passes acros'sthe lower end of tween its intermediate portion-and the lower end of center electrode 9. I The center elec- 1 trode 9 runslongitudinally through the insulatorand electrically connects, through a.

terminal cap and stud l0,'and binding nut 11, to alwire leading to one side of the battery. The other electrode 7 on the lower end of the insulator, through the metallic sheath 3, electrically connects with the engine casing and the ground back to the ot-her'side of the batteryor magneto. The spark plugs in Figs. l'zand 2 are similar with the exception of the electrode arrangements on the lower end i'," regard a.) which Fig. 1 differs from I Fig-..

just described by the substitution of' a straight electrode wire 12for the second electrode instead of the electrode terminal 7 ofFig. 2. In this Fig.1 the electrode 12 is of course merely a piece of wire attached to'themetal sheath 3 of 1 by spraying.

In Fig. '3 I, show a different way of perma nently providing threads for insulating. ma-j menting operation.

, the insulator.

the electrode 16 and the bottom teriaL-this being done by having the insulat ing material unthreaded and provided with a sheath of metal, by spraying, after which threads may be cut in the sprayed sheath by any usual thread cutting operation. In this form I preferably extend the sprayed sheath 13 around the lower endof the insulator at 14 at which point it will form one spark terminal between which and the opposingend 15 of a center electrodelfi a spark will pass when the plug is in use. 1

In this form of Fig. 3, I further illustrate the center electrode 16 as being permanently secured in the insulator through the medium of sprayed material instead of the usual ce- Thus I have .shown a film'17 of sprayed material connecting the surfaces of the electrode 16 and the adjacent surface of the insulator at the lower end of This permanently attaches the electrode 16 to the insulator and in away preventing any possibility of leakage of compression from the engine through the in sulator around the axial electrode 16. I have shown the upper end of this electrode 16 extending into a counterbored opening 17 in the lipper end of the insulator- I have also shown a coating of metal sprayed upon the adjacent surfaces of the upper end of.

of the counterboredv opening. This further insures a gas tight connection of the center electrode withthe insulator. I provide a terminal stud 19 with a recess 20 at its lower end adapted to fit o er the upper end of the center. electrode 16 and the exterior of the lower end of this stud 19 I preferably have noncircular to fit the preferred non-circular 1nterior of thecounterbore 17. This construction serves to prevent rotation-of the terminal stud 19 when in place on the insulator. l fasten the terminal stud 1,9 firmly the upper end' of the insulator and connectin place by spraying" a cap 21 of metal over This cap I make of sufiicient thickness. as to Y firmly support and hold the terminal stud'19- in place. A nut 11 similar to the one in-Figs. 1 and 2 is of course used in'connection with the terminal stud 19 to receive one end of the battery or magneto wire.

In Fig. 4 I show a spark plug of a little different design made up of two main pieces; an outer metallic shell 22 threaded at 23 for attachment into an engine cylinder; and an insulator These two parts may be of any desired-designandl permanently connectthem. together by spraying their adja-- cent surfaces at one-point by a layer of spray25. which securelyfastens the two main pieces-together in a gas tight manner. In thisform of Figs. 4, 5 and 6 I have shown" the insulator carrying both electrode wires which it mayor may not do, one,running completely through the insulator and the other only part way terminating at the sur face of the insulator to be sprayed upon in fastening the insulator in the shell. In this form. I have shown the upper end of the longer electrode inelectrical connection with a terminal cap 26 of the usual construction adapted for receiving connection with a battery or magneto .wire in the usual manner This'termlnal cap arrangement may be of the usual type *or may be different and placed upon the u'pper end of the insulator by means of a spraying operation in a manner similar to that I have illustrated and described in connection with Fig. 3. In these figures I have shownthe' lower end of the insulator connected with the lower end of the shell by ring 27 of sprayed material and both a peripheral groove 31 in the insulator where the spray is to be applied so as-to'form a stronger connection between the insulator and the shell as regards longitudinal displacement. In this figure, 32 is a second electrode running longitudinally through the insulator. I preferablyhave this electrode of a larger diameter at Its upper end to fill a counterbore 3a in the insulator. The'extreme end of the electrode being threaded'to receive a nut 35, I fasten the electrode in I place and to the. insulator by spraying a coating 36 of metal on the upper surface of the insulator and against the periphery of the largaportion of the electrode.

' In Figs@ 9, 10, l1, l2, and 13 I show a different type of spark plug, generally of the design well known on the market in whlch an insulator 37 is adapted to be secured in a shell 38 by means of 'a screw bushing 39 screwing into threads in the inslde of the shell so as-to carry the insulator down and bring its downwardly facing shoulder 40 against the upwardly facing shoulder 41 on the inside of the shell. "Usually a gasket of separate construction is provided between these two contacting surfaces to eliminate or reduce leakage of compression from the engine. I eliminate this separate gasket by spraying the shoulder on the insulator with a soft metal such as copper so as to, in effect,

' make the soft copper gasket a part of the insulator. I leave this seating shoulder on the "insulator, which is to'be sprayed with soft copper, u-nglazed so as'to better receiveiand hold the soft copper which thus being perma'nently attached to the insulator still efiec tivelyserves as a soft copper gasket between the two surfaces in that there is but one passage for gas fromthe cylinder between the trode to the lower 'endof the insulator.

insulator and the shell, whereas there would be two if a separate gasket were placed be tween the insulator and the shell seats, a passage on the upper surface of the gasket and a passage on the 'lowersurface. This considerably reduces the possibilityof leakage of compression at the seat between the informed of steel and I still further may improve the joint at their seat by spraying on top of the shoulder in the shell and the cop 'sulator'iand the shell. The shells are usually per on the insulator expanding equally with" the heat, reduces considerably any danger of coating of spray 43 around it where it pro-- trudes from the lower end of the insulator and a similar coating at around the upper end of the electrode and filling a counterbore +5 in the upper end of the insulator. A

. terminal cap 46'is placed upon the upper end of the insulator this being provided with the usual terminal stud and nut for receiving one end of a battery or magneto wire. I permanently fasten the cap 46 in place on the insulator by spraying a layer 47 of brass or copperon the surfaces of the insulator and the metal cap where they meet so as to permanently connect the peripheries of the insulator and cap in an absolutely gas tight manner. Of course the cap 46 may be dispensed with as a separate piece the terminal stud being a part of the central electrode or projecting into the insulator to touch the central electrode, thisterminal stud being fastened in place by a layer of copper or brass sprayed upon the upper end of the iny sulator and in contact with the periphery of the terminal stud as shown'in Fig. 11.

In order to provide the insulator with both sparking points so that if the invention isapplied to a quick detachable spark plug that the insulator when removed will carry both points for cleaning and adjustment I ma fasten the second electrode on thelower en of the insulator by placing the electrode 48 in place against -the lower end of the in-.'

'sulator and spraying'over its exposed surface and the adjacent surface of the insulator. This firmly secures the second .elecprefer to connect this so attached second electrode to the sprayed shoulder by coating t e outer surface of the v insulator between the second electrode and the sp raye d{shoulder' with a conductor. -This need not extend completely around the periphery ofthe insulator but may take the form of a-.ribbon 49 shown most clearly in asket on the insulator outer periphery wall inside surface of the Fig. 11. Thisbein of sufficient current capacity to connect the secondelectrode with the sprayed copper gask which, when the insulator is in place, is in engagement with the shell which is grounded through the engine to the other side of the battery or magneto. shown a section of the lower end of the insulator as it would appear ifinstead of a ribbon 49 only, the conducting material was sprayed so as to cover the-whole lower surface of the insulator exterior. This would prevent any oil-soaking of the insulator from I passage of oil from the outside of the insulator into the insulating material throughthe of the insulator.

In Fig. 15, 50 is a band of sprayed metal on the lower end of the insulator'and in this form I have, eliminated the electrical connection between this second electrode and the sprayed gasket on theinsulator and propose that this second electrode will make an electrical connection with the inside of the spark plug shell wall by jumping across the small gap between theexterior of this electrode ring or band and the inside of 'the shell. The main spark occurs between the bent end of the central electrode and the lower surface of this second electrode ring. y interposing this second sparking gap between the second electrode and the inside of the shell it is claimed by many that a sharper and better igniting spark results at the main sparking point.

In Fig. 16, I show a manner of attaching an asbestos or other non-metallic gasket to the shoulder on the inside of the shell. This is accomplished by merely placing'a ring 51 of asbestos or other packing in place on the inside shoulder of the shell and covering the packing by a coating 52 of soft copper which extends to, at its edges, and connects with, the shell. This form of gasket construction is very effective in that none of the fibrous packing is exposed but is confined and kept completely surrounded with metal so that it cannot become oil soaked or easily damaged in use. This construction provides a yielding gasket which,

in some ways and for some uses, is preferable to an entirely metal gasket such as of soft cop-per.

In Fig. 17, I show a similar form of gasket construction. with the exception that the fibrous gasket. is secured to and confined against the shoulder on the insulator by a spray or coating of soft copper or other de-.

sired metal. Of course similar provisions of gaskets may be made on both the contacting seats of the insulator and the shell if desired. These forms of gasket constructions are of course not limited to spark plug,

use but are equally of value-elsewhere as regards their broader aspect, yet being particularly advantageous in spark plug use owing et on the insulator,

In Fig. 14 I have be coated be clean an insulator the area effective shield from spark plug shell are coated with a soft copper, brass, or similar material, so as to for a more eflicient gas tight connection between the threaded members.

While I'have described various details of processes and construction I- do not mean to confine my protection to the same as various changes may occur to those skilled in the art coming Within the principle of my inven tion. I have shown and described applications of my invention as applied to spark plugs for internal combustion engines but I do not mean to limit my protection to this application wherever the inventions in a broader aspect are new For example, the details of gasket construction and manufacture which I have herein'shown and described .and which are particularly advantaeous and patentable in a spark plug sense, I Eelieve to be new in a broader sense and patentable in this broader aspect as well. The same is true as regards the effective threading of an insulating body which it has been impractical to thread before my invention of protecting the threads by sprayed metal, and of the spraying of metal upon an insulator or other brittle substances and cutting the threads thereafter.

In the above description wherever I have spoken or referred to spraying portions of my plug it is necessary that the surfaces to for example by sand blasting or any other effective way of cleaning the surfaces. Furthermore, when spraying the'insulating material such as porcelain in carrying out my invention the surfaces to be sprayed should be left unglazed. If these precautions are taken a durable effective bond will be provided between the surface sprayed upon and the material with which it is sprayed so that they will adhere to any ordinary usage and in such a way as to prevent any passage of as or air between them at their points of engagement. In order to prevent an area from being sprayed adjacent one desired to be sprayed if it be not desired to be sprayed if glazed will not retain the sprayed material. Or interposing some other collecting medium to shield'the area not to -be sprayed serves thesame purpose. Covering an area not to be coated with wool is a very the spray for it, as stated above, will not retain the material sprayed upon it. Rapidly rotating an object to be sprayed on its periphery whilerexposed to the spray will insure a relatively even coating of the material over the periphery of the objectl Wherever in the carrying out of these course I may use steel orother metallic conducting material. Furthermore I may .use a separate 'piece for the electrode and merely attach it by spraying to the insulator.

- I Obtain very desirable results from spraying the surface of the lower end of the insulator, which projects into the engine for exposure to oil or heat with glass which gives me a very good 'oil resisting coating for the insulator. I may as well coat any other portion of the insulator with glass as well where an electrical insulating materialv is desired for the protective covering. By doing this the insulator can be left wholly unglazed and a coating of glass sprayed on for a glaze wherever desired by the spraying operation.

'Particularly is this desirable for that portionof the lower end of the insulator be-' tween the two electrodes such as the inside 'surfaces, coated with a she th of relatively of the reess' in the lower end of the insulator.

' upon those portions of a body formed out of insulat ng material which are adapted to contact with metallic surfaces,'by liquefying Having described my invention what I claim as new and desire to secure by Letters- 1. The process of making spark plugs comprising depositing a metallic sheath upon a body formed out ofinsulating' material by liquefying a-relatively soft metal,-

atomizing saidliquefied metal and projectmg said atomized metal upon said body by a blast of gas and forming screw threads in aportion of said metallic'sheath.

2. The process of making spark plugs comprising forming screw threads on a. portion of a body formed out ofinsulating material, and depositing a metallic sheath upon said body, including the threaded portions thereof, by liquefying a relatively soft metal, atomizing said liquefied metal and projecting sa'id atomized metal upon said body by a blast of gas. V

3. The processof .makingspark plugs comprismg depositing a metallic sheath arelatively soft metal, atomizing said liquefied metal and projecting said atomized metal upon said bodyby a blast of gas.

v 4. The process of threading amember of relatively brittle material comprising the depositin of a metallic sheath upon said member y liquefying a relatively soft rhetaL-atomizing said liquefied metal and projecting'said atomized metal on the memher by a blast of gas and cutting-screw threads in said metallicsheath.

The process of threading a member of relatively brittlev material comprising the forming of screw threads on said member and the depositing of a metallic sheathnpon said threaded portion by liquefying a relatively soft metal, atomizing said liquefied metal andprojecting said atomized metal on the member by a blast of gas.

6. In a spark plug, the combination of a body of insulating material, a sheath of relabody being provided with screw threads,

and a sheath of relatively soft metal deposited on said body, including the threaded portion, by liquefying said metal, atomizing said liquefiedmetaland projecting said atomized metal on said body by a blast of gas.

8. In a spark plug, the combination of a body of insulating material having portions,

which are adapted to contact with metallic soft metal by liquefying said metal, atomizthreads.

10. A threaded member comprisin a body of relatively brittle material, provi ed with screw threads, and a sheath of relatively soft'm'etal deposited on the'threaded portion of said body by liquefying the metal, atomizing said liquefied metal and projecting said atomizedmetalon the body by a blast of gas. I

11. The process of making spark plugs comprising the forming-of a body of insulating material'provided with a longitudinal passage, insert-in an electrode in said passage, and depositing a sealingmaterial against the surface of the electrode and the adjacent surface'of the-body by liquefying said material, atomizing said liquefied material and projecting said atomized material on said surfaces by a blast of i a 12. The process of lnaklng spark plugs comprising the positioning of an electrode in the desired relation to a body of insulating material and depositing sealing material upon the adjacent surfaces of the a body and'the electrode by liquefying said materlal, atomizing said liquefied material a deposit on said body extending and'projecting said atomized material upon said surfaces by a blast of gas. j

, 13. In a spark plug, the combination of a body of insulating material provided with a longitudinal passage therein, an electrode disposed in said passage and sealing material deposlted on the adjacent surfaces of said body and said electrode by liquefying said material, atomizing said liquefied material and pro ectlng said atomized materialupon said "surfaces by a blast of gas.

14. In a spark plug, the comb nation of a body of insulating material and an electrode secured to said. body by sealing material deposited on the adjacent surfaces of said body and said electrode by liquefying said material, atomizing said liquefied material and projectin said atomized material upon said surfaces Toy a blast of gas.

' 15. The process of making spark plugs comprising securing a central electrode in a body formed out of insulating material and provided with a shoulder, depositing arelatively soft metal on said-shoulder, deposit ing electrically conductive material on said body from a point adjacent the end of said.

electrode to said shoulder by li'quefying said material, atomizing said liquefied material and projecting said atomized material on saidbody by a blast of gas, and inserting said body in a metal shell provided with an internal seat with said said internal seat.

16. The process of making spark plugs comprising securing a central electrode in a body formed out of insulating material, depositing electrically conductive material on said body at a point adjacent the end of said electrode by liquefying said material, atomizing said liquefied material, and projecting said atomized material on said body by a blast of gas, and inserting said body in a metal shell With said electrically conductive material in proximity to said metal shell.

17. The process of making-spark plugs comprising securing a central electrode in a body of insulating material and depositing electrically conductive material on said body at a point adjacent the end of said electrode by liquefying said material, atomizing said liquefied material and projecting said atomized material on said body by a blast of gas.

18.v In a spark plug, the combination of a body of insulating material provided with a shoulder, a layer of metal on said shoulder, a central electrode secured in said body, a of electrically conductive material from a point adjacent. the end of said electrode to said shoulder and deposited thereon by liquefying said material, atomizing said liquefied material and projecting said atomized material on said body by a blast of gas, and a metallic shoulder engaging shell having an internal seat in which saidbody is inserted with said'shoulder engaging said seat. v t

V 19. In a spark plug, the combination of a body of insulating material. a central electrode secured in saidbody, a metallic shell in which said body is inserted and a deposit of electrically conductive material on said body-extending from a to the end of said electrode to a point adjacent said shell and deposited thereon; by liquefying said material, atomizing said liquefied material and projecting said atomized'materialon said body by a blast of gas.

20. In a spark plug, the combination of a body of insulating material, a central elec-' trode secured therein, and a deposit of electrically conductive material on said body, at a point adjacent the end ofsaid electrode, deposited thereon by liquefying said material, atomizing said liquefied material and projecting said atomized material on said body by a blast of gas.

21. The process of making spark plugs comprising the securing of a central electrode in abody formed of insulating material and the depositing of a sheath of electrically conductive material over the top of said'body and in contact with said electrode by liquefying said material, atomizing said liquefied material and projecting said atomized material on said body by a blast of gas.

22. The process of making spark plugs comprising the fitting of a metallic cap over the top ofabody of insulating material and securing said cap to said body by depositin sealing material on the adjacent surfaces or said cap and body by liquefying said material, atomizing said liquefied material and projecting said atomized material on said surfaces by a blast of gas.

28; In a spark plug, the combination of a body of insulating material, a central elec trode secured therein, and a terminal cap comprising a coating of electrically conductive material deposited on the top of said body and in contact with said electrode by liquefying said material, atomizing said llquefied material and projecting said atomized material on said body by a blast of gas.

24. In a spark plug, the combination of a body of insulating material, a metal terminal cap fitting over the top of said body and a deposit of sealing material on the adjacent surfaces of said cap and body deposited thereon by liquefying said material, atomiz ing said liquefied "material and projecting said atomized material on said surfaces by a blast of gas.

25. The process of making spark plugs comprising the positioning of a body of insulating material in a metal shell and securing said body in position by sealing material deposited on the adjacent surfaces of said point in proximity ing said atomized metal on said shoulder by a blast of gas, and inserting said .body in shell and body by liquefying said material,-

atomizing said-liquefied material and pro- .jocting said atomized material on said surfaces b a blast of ga s.

26. na spark plug, the combination of a inetal shell,' a body of insulating material disposed within said shell and sealing mate- 'rial deposited on the adjacent surfaces of said shell and body by'liquefyingsaid material, at'o'mizing said liquefied material and projecting said atomized material on said surfaces by a blast of gas.

27. The process ofmaking spark plugs. comprising depositing a layer of relatively", soft metal on, the shoulder of a body of insulating material by liquefying said metal, atomizing said liquefied metal and projecta metal shell provided with an internal seat with said shoulder engaging said seat. 4

- 28. The process of making spark plugs comprising the forming of a body of insulating material. rov'ided with a shoulder, placing a layer 0 gasket material on the internal 1 seat of a metal shell, fixing said gasket mate rial-in place by depositing a layer of sealin material on the surface of the gasket material and the. adjacent surface of the metal shell by liquefying said material, atomizing .said liquefied material and projecting said atomize'dmaterial on said surfaces by a blast of gas, and inserting said body in said shell with the shoulder engaging said; gasket material to make a as tight joint.

29. In a sparkpl g, the combination of a bodyof insulating material provided with a shoulder, a layer of relatively soft metal deposited on said shoulder by liquef ying said metal, atomizing said liquefied metal and projecting said atomized metal on said shoulder by a blast of gas, and a metal shell provided With an internal seat cooperating with said shoulder. v

' 30. In a spark plug, the combination of a body of insulating material provided with a shoulder, a metal shell provided with an internal seat, a layer of gasket material disposed on said seat and a layer, of sealingmaterial deposited onthe surface of said gasket material and the adjacent surface of said shell by liquefying said material, atomizing said liquefied material and projecting said atomized material'on said surfacesby a blast of gas, said shoulder cooperatmg with said gasket to form a gas tight joint.

31. The process of making sparkplugs comprising the coating of a portion of the In testimony whereof I afiix my'signature I in the presence of two witnesses. I

v CHESTER H. BRASELTON. Witnesses:

G. T. HEINz,

R. B. MUNDAY.

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