US2394041A

US2394041A - Insulated carbon body

Info

Publication number: US2394041A
Application number: US344455A
Authority: US
Inventors: Conradty Ottmar
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-06-30
Filing date: 1940-07-08
Publication date: 1946-02-05
Anticipated expiration: 1963-02-05

Description

Feb. 5, 1946. O coN 2,394,041

INSULATED CARBON BODY Filed July 8, 1940 INVENTOR OTTMAR Com/M071 ATTORNEY.

ing drawing in which:

Patented Feb. 5, 1942;

INSULATED CARBON BODY Ottmar Conradty,

Germany; vested dian Rothenbach on the Pegnitl, in the Alien Property Custo- Application July 8, 1940, Serial No. 344,455 In Germany June 30, 1939 1 Claim.

This invention relates to artificial carbon bodies including an insulating support for mounting.

In variou branches of the electrotechnical industry, carbon bodies are required which either have to be insulated from each other or from another part of a machine or apparatus, such articles being, for example, carbon collectors and carbon slip rings as well as other carbon contacts operating under high electrical load and reaching high working temperature. The conventional insulating materials, such as, cement, are destroyed and decomposed at the high temperatures in question, more particularly by function of electric sparks, and converted into electric conductors, whereby they become useless as electric insulators and mechanical supports for the carbon bodies.

It is an important object of the present invention to provide a carbon body and insulator unit the insulation of which is capable of resisting extreme electric and heat stresses.

with this and further objects in view, as may become apparent from the within disclosures, the invention consists not only in the structures herein pointed out and illustrated by the drawings, but includes further structures coming within the scope of what hereinafter may be claimed.

The character of the invention, however, may be best understood b reference to certain of its structural forms, as illustrated by the accompany- Fig. 1 is a side elevation of a carbon and insulator unit having theinvention applied thereto.

Fig. 2 is an end view of Fig. 1.

Fig. 3 is an axial section of Fig. 1. a

Similar referencenumerals denote similar parts inthe difl'erent figures. y 1

Referring now to the drawing in greater-detail.

An annular carbon body 5 is mounted on a tubular insulating body 6. Buffer materials I, consisting, for instance, of asbestos or slag wool, may be provided between the carbon body and the collars B of the insulating body adjacent thereto, in order that mechanical shrinking tensions caused by the cooling down of theinsulating body may not be transferred upon the carbon material.

The manufacturing process will now be described.

I apply the insulating material on the carbon body under action of heat (l000-l400 C.) in a burning, baking or casting operation, using gas as a fuel. I have found that an insulating material which can be subjected to a treatment of this kind will resist also the stresses occurring in working order by sparking and hea Various insulating materials may be used which can be applied by heat. Depending on the kind oi! insulating material the same is applied on the carbon before the same has been burnt, or after the preliminary baking or firing or after the hardening or final baking.

It is then hardened and solidified by heat. Where the insulating material is applied on the carbon before the burning or before the hardening-on, the carbon will be hardened-on during the heat treatment of the insulating material; On the other hand, where the carbon has been full annealed already, it will undergo a second annealing process with the insulating material applied thereon. This is by no means objectionable, but on the contrary the properties of the carbon may be modified by the second baking processin any desired manner.

In the practice of my invention, I may for instance roduce a carbon body in known manner by compression, then I press a ceramic insulating material, for instance, steatite (magnesium and aluminum silicate), around the carbon body, using a suitable mold and finally the composite body obtained by pressing together the two parts is subjected to a common burning or' baking process. It will be appreciated that the shrinking characteristics of the two substances which are being used have to be matched with each other in a suitable manner. Where large differences are existing in the shrinkage of the two materials, namely, carbon and insulator, the compressed carbon may be pre-baked to sucha degree, that in the common final annealingprocess (hardening-on) it does not shrink more than the insulating material pressed around it after the prebaking or first annealing. Again, the ceramic insulating body may be first shaped and pre-annealed, then united with the hardened-on carbon and then the whole unit may be annealed once more up to the temperature causing maximum shrinkage of the insulating body.

According to a further feature of the invention, the insulating body may consist of vitreous substances, more particularly, glass, which is cast or die-cast upon or around the suitably formed carbon body in a molten and liquid condition. In the same manner, any smelting fiux of the glass or enamel type or smeltable blast furnace slag may be applied.

According to another feature of the invention, I may use a ceramic material which contains suitable flux or frit admixtures and therefore does not require a real burning process but is pressed around the carbon body in powdered form and then subjected merely to a sintering process which may consist in the simultaneous applies-- tion or pressure and heat Substances which may be slntered in this manner, are, for instance, glass dust, and slag meal. The solidification of the insulating material by a sintering operation without pressure or with simultaneous application of pressure oilers the advantage that the difi'erences of expansion or shrinkage oi the two materials are less than with a conventional ce ramic process. In most instances, it will be ad vantageous to provide bolsters, as at I mm. 3, between the carbon and insulating material, to compensate the considerable pressures due to shrinkage of the insulating material.

The method of the present invention has been described in detail with reference to specific embodiments. It is to be understood, however, that the invention is not limited by such specific reierence but is broader in scope and capable of scribed and illustrated in the drawing.

other embodiments than those specifically dem It is also to be understood that the following claim is intended to cover all of the generic and specific ieatures oi the invention herein described, and all statements or the scope oi the invention which, as a matter of language, might be said to fall therebetween.

I claim:

A composite body comprising a substantially cylindrical portion oi insulating material having an annular peripheral recess therein on its outer surface, an annular carbon body fitting in said recess and contacting the bottom of the latter, the thickness of said body being less than the width 01 the recess, and a bolster oi refractory insulating material disposed between at least one 01 the recess sidewalls and the proximate side of the body.

OT'I'MAR CONRAUI'Y.