US1150081A - Method of making electrical apparatus. - Google Patents

Description

S. TROOD.

- METHOD OF MAKING ELECTRICAL APPARATUS.

APPLICATION FILED JAN. 1, 1914.

1,150,081 I Patented Aug. 17, 1915.

. ATTORNEY Unrrnn srnrns SAMUEL TROOD, 0F WILKINSBUBG, PENNSYLVANIA, ASSIGNOR TU VJESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION (3F EENNSYLVANIA.

IMETHGI) OF IVZAKIHG ELECTRICAL APPARATUS.

Specification. of Letters Patent.

Fatented Aug. 1%, $915..

Application filed January 7, 1914. Serial Ito. 810,776.

new and useful Improvement in Methods of Making Electrical Apparatus, of which the following is a specification.

My invention relates to methods of making electrical apparatus, and it has special reference to electric heating devices.

The obj oct of my invention is to provide a method of making devices of the aboveindicated class which shall be simple and in expensive and which shall secure new an highly desirable features in the completed apparatus.

More specifically, the object of my invention is to provide a method whereby, when an incasing member is cast around a conductor, the conductor will contract at the same 'rat'e as the incasin; member during cooling thereof, and thus the mutual thermal contact of the parts will remain as intimate as at first, and no undue stresses will occur.

Heretofore, in devices of the general class in question, the electrical conductor has not been adapted to contact with the cooling incasinp; member and. consequently, undue strains have been caused, and various parts have undergone cracking or other weakening conditions, which also militated against the maintenance of intimate thermal contact between the parts.

According to my invention I embed a, suitable electrical conductor or heating element in a relatively plastic cement or other suitable material of good heat-conducting and electrically insulating properties, I then preferably bake the cement, and next use the combined body as a core around which a copper or other suitable metallic incasing member is cast. Prior to and during the casting operation, I pass through the con ductor a current of such value that it is caused to expand an amount that corre sponds to the expansion present in the initially solidified incasing' member. As the member cools and contracts, the current through the incloscd conductor is either cut oil or is gradually reduced in accordance with the temperature reduction of the ineasmg member, as hereinafter described. In this manner, the conductor, the inclosing material and the incasing member all cool and contract at substantially the same rate, thereby maintaining intimate mutual thermal contact between the parts, while obviating the above-mentioned difliculties cracking and the like.

In the accompanyingdrawing, the single figure is a view, partially in longitudinal section, and partially diagrammatic, illuscrating the method constituting my invention.

Referring; to the drawing, the apparatus here shown comprises an electrical conductor or heating; element 1 which is preferably wound on an insulating spool 1; an envelop 2 therefor of relatively plastic cement or other suitable material of good heat-com ductin and clectrically-insulatin ro Jerties; an incasing member 3 of copper or other suitable metallic matenal, here shown as a soldering iron tip; a suitable mold 4:

for casting the incasing member 3 around the envelop 2; supply conductors 5 for con necting the heating element 1 to a source of electrical energy (not shown); a switch. 6,

and a rheostat 7 for varying the current supplied to the element 1.

Considering now the various steps of my process, the electrical conductor 1 and its spool 1* are first embedded in the relatively plastic cement 2, which is fashioned in the 35 desired shape and size. The combined body is then baked. as is customary in the production of cores in the molding art, and the combined body is employed as a core for a casting; or" copper or other suitable material. 99

The core may be held in position during the casting: process in any suitable manner, suc'i as by the threaded collar device 8 shown in the drawing.

A predetermined time prior to the casting process. the switch 6 is closed to send a current through the heating element 1 and the rheostat 7. of such value that the element is heated and caused to expand an amount corresponding to the expansion present in 0 the initially solidified tip 3. An intimate thermal contact thus obtains between the and contracts the current is As the element 1 and the tip 3.

prei oli' immediately after solidification, i. conductor and the cast member are same material, and the rheostat is preferably actuated to gradually include more sistance in the circuit if the two members are of dissimilar materials, thereby in the latter case, reducing); the current traversing the heating element in such ratio that the change of temperature of the element and its contraction correspond to the temperature variation and shrinkage of the tip 3.

Thus it will be noted that in either case, the

tip. the cement and the heating element all cool and contract together at substantially the same rate, thereby permanently in 'n raining intimate thermal contact between the parts.

1 do not wish to be restricted to the specilic arrangement of parts and the struc laral details herein set forth, as modifications till-erect may be made within the spirit and scope of my invention. It, therefore, de-

sire that only such limitations shall be imposed as are indicated in the appended claims.

.l claim my invention:

1 The method of making an electrical device that comprises applying an electric current to a conductor during the casting oi material around said conductor and thereafter cooling the said conductor and the said cast material in such manner that they contract at substantially the same rate.

2. The method of making an electrical device that comprises applying an electric current to insulated conducti'ir during the disposal of heated i aterial around said conductor, and tlurrealter cooling the said conductor and the said material in such .anner that they contract at substantially the same rate.

. 3. The method of making an electrical de vice that connirises the application of an electric currimt to a conductor provided with insulating material during the casting of an incasing member around said material and during" a predetermined period of cooling after completion of the casting operation.

4. The method of" making an electrical device that comprises the application of an electric current to a condi'ictor during the casting: of material around said conductor. and the variation of said current while said material is cooling.

5. The method of making, an electrical de-' vice that comprises the application of an electric current to a. conductor provided with insulating material dining the casting cl an incasing' member around said material. and a reduction of the current in ac cordance with the temperature reduction of said nien'iber as it cools.

The method of making; an electrical device that comprises applying an electric current to conductor during the disposal of metallic material around said conductor and in good thermal contact therewith, and thereafter cooling the said conductor and the said material in such manner that they contract at substantially the same rate.

7. The method of making an electrical device that consists in disposing heated material around. a conductor simultaneously passing an electric current thercthrough, and thereafter cooling the said conductor and the said material in such manner that they contract at substantially the same rate.

8. The method of making an electricaldevice that consists in disposing molten material around an insulated conductor simultaneously passing an electric current therethrough, and thereafter cooling the said conductor and the said material in such manner that they contract at substantially the same rate,

9. The method of making an electrical device that consists in casting an incasing member around a conductor, simultaneously passing an electric current thercthrough, and varying the current as the member cools.

3.0. The method of making an electrical device that consists in casting an incasing member around a conductor and in good thermal contact therewith. simultaneously passing an electric current through said conductor, and reducing the current in accordance with the temperature reduction of aid member as it cools,

11. The method of making an electrical device that consists in embedding a conductor in insulating material, casting: an incasing member around said material, supplying an electric current to the conductor during the casting operation, and varying the current as said member cools to cause the con ductor to contract at substantially the same rate as the incasing member.

12. The method of making an electrical device that consists in surroumlinc,- a conductor with relativclv plastic material of good hea t-cond noting: properties. baking said. n'iaterial. casting; an incasi on member around the combined body as a core. supplying a electric current to said conductor during the casting operation and gradually reducinf); the current value as the member cools W iercby said coni'luctor. material and member contract at substantially the same rate and remain in mutual intimate thermal relation.

13. The method of making an electrical device that comprises heating an electric conductor. surrounding the said conductor with heated material. and causin l the said conductor and the said material to cool sidevice that comprises surrounding with In testimony whereof, I have hereunto heated mziteyial a conductor that has been subscribed my name this 27th day of Dec. heated sufiielently to expand it to subst mn- .1913.

tially the same degree as the said matenal, A SAMUEL TRQOD. 5 and eausing the said conductor and the said Witnesses:

material to cool simultaneously and to con- B. B. Hume,

vact at sl'lbstantially the same rate. M. C. MERZ.

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