US1331091A - Method of making spark-plugs - Google Patents

Description

J. H. BECKER.

METHOD. OF MAKING SPARK PLUGS. APPLICATIONEILED JUNE 11. 1919.

1i, 331,091. Patented Feb. 17,1920.

" great during the manufacturing operation.

UNITED STATES rATEnroFFroE.

JOHN H. BECKER, or nu'r-IinYf-nnw JERSEY.

summon or Magritte srnax-rnues.

Application 4 a ,1 To all whom it may concern:

Be it known that 1, JOHN H. BECKER, a

citizen of the United States, and a resident of Nutley, Essex county, New Jersey, have invented, a new and useful Improvement in Methods. Of Making Spark-Plugs, of which the folldwing is a full, clear, and exact description.

Myinvention relates to improvements in the :method of making spark plugs, and more particularly in the method of securing the core or porcelain in the outer or metallic shell. Owing to the different co-expansions of spark plug cores and their shells, there is a good deal of difiiculty in making a perfectly tight union between the parts es pecially Where attempts to do this are made without using gaskets, nuts, or the like. These extraneous fastenings are objectionable because in actual use when the plug becomes highly heated it often happens that the core breaks because of the stress upon it (between its fastening devices, and Where the core is fastened by simply shrinking the metal upon it the loss by breakage is very It is generally recognized that it is desirable to have the core secured in its shell Without any extraneous fastenings, but simply by having the shell shrunk upon the core. My

invention provides a means for doing this so that the loss during manufacture is negligible, and therefore my method is such that after the plug is made it is not liable to break, because the core is; subjected to more strain during the process of manufacture than it ever is in actual use. My method, therefore, is intended to provide asimple and efiicient means of securing the core in the shell sothat it will stand up under use, and so that a perfect union between the two parts will be had.

Reference is to be had to the accompany- I ing drawing forming a part of this specification, in which similar reference characters indicate corresponding parts in the vi w.

The drawing is a vertical section of a spark plug shell and core.

The shell 10 can be of any approved constrhction but it should have a slightly tapering? section 11,- "and the core 12 can likewise be offan usual or preferred construction,

- except t at it should have a section-'13 shaped to fit tight against the correspond ing part ,11 of the shell. -In my early at-' tempts to shrink ashell of this character Specification of Letters Patent. .Patented Feb, 1'1. 1 920.

filed June 11, 1919. Serial No 303,372. I

upon a'somewhat similar core, I found that the breakage of thecorefranas high as 95%; but by carrying out my method'as I have evolved it by repeated experiments, the breakage is practically nothing, and the union between the shell and core is perfect so that no other fastening means is necessary. .To accomplish this result I practically annealthe core, that is to say, I expel all the moisture practicable, and toughen it by subjecting it for a comparatively long time to a heating but relatively low temperature. I have got the best results baking the core in an oven for about fifty hours at a temperature of about 150 degrees F. The heating process may be made longer or shorter, but the time given gives the best results. Likewise the temperature can-be varied somewhat, but should not be varied much from the temperature given. In any event the temperature should not be less "than 140 degrees or more than 170 degrees.

' After the core has been toughened by the long preliminary treatment as specified, and

.it is to be united permanently to the shell,

the latter is heated to a cherry red heat, that is to say, to a temperature of approximately shell so that the part 13 Will seat itself firmly in the part 11 of the shell, and then the shell is permitted to shrink by cooling so as to become absolutely fixed upon the core.

If this method is carried out as stated there will be comparatively no loss of cores by breakage, and the two parts Will'be so firmly united'that they will never separate under use, and moreover, the joint will be so tight that there will be no leakage of gas or current.

I claim 1. The herein described method of securing spark plug cores in their shells, which consists in first toughening the core by subjecting it for a comparatively long time to a low temperature ,'then heating the shell and core to approxlmately the same temperature, and finalljyngyhile both shell and core are hot, pressing the core into its seat in the shell. 1

l {2. The herein described method of securing spark plug cores in thei shells, which oonsists in first tonghening the core by a long preliminary heating at a relatively low temperature, then heating the core and shell to a high temperature, and finally pressing the hot core to its seat in the hot shell. 3. The herein described method of securing spark plug shells and cores, Whicheonsists in first toughening the core by heating it for a long period to a temperature of not less than 140 degrees F. nor more than. 170 degrees, next heating the shell and core to a high temperature, and finally pressing the hot core into the hot shell. 7

4:. The herein described method of: secur-i ing spark plug cores and shells, Which consists in. first toughening the core by a long pre-l1eati11g at a ow temperature, next heating both core and shell to a temperature of :not less than 1200 degrees nor more than 1600 degrees Ft, then pressing the hot core to its seat in the hot shell, and finally cooling the united parts so that the shell shrinks tipon the core.

$3 5. A herein described method of uniting the hot core to its seat in the hot shell.

JoHNii, BECKER.

Witnesses:

WARREN B. HU'roHmsoN, M. G. ODONNELL.

shell to a high temperature, Y

spark plug shells and cores, Which consists in providing the shell With a tapering-seat,

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