US2037375A - Method of tempering electric heater shells made of phenol-formaldehyde condensation product - Google Patents

Description

S. FREEMAN April 114%, 193$.

METHOD OF TEMPERING ELECTRIC HEATER SHELLS MADE OF PHENOL FORMALDEHYDE CONDENSATION PRODUCT Filed May 19, 1930 HNVEN l O ATTORN E15 Patented Apr. 14, 1936 UNITED STATES PATENT OFFICE Samuel Freeman, New York, N. Y.

Application May 19, 1930, Serial No. 453,595

1 Claim.

v My invention relates broadly to a method of tempering molded articles of phenol-formaldehyde condensation resin, which are subject to high temperatures during usage, as for instance 5 when they are used as shells for electric heaters, and in particular as a new and improved socket for an electric curling device.

One of the objects of my invention is to provide a new and improved socket for a device of this character, this socket being made of a resinous condensation product such as the phenol-formaldehyde synthetic resins.

Another object of my invention is to provide a new and improved method of making such a socket.

Another object of my invention is to produce an improved socket which can be subjected to the relatively high temperature produced by the electric heating coil commonly used in connection with hair curling devices, without blistering.

Other objects of my invention will be set forth in the following description and drawing which v illustrate a preferred embodiment thereof, it being understood that the above general statement of the objects of my invention is intended to merely generally explain the same and not to limit it in any manner.

Fig. 1 is a rear elevation. Fig. 2 is a top view.

Fig. 3 is a side elevation.

Fig. 4 is a sectional view on the line 44 of Fig. 2.

Fig. 5 is a sectional view on the line 55 of Fig. 4.

Fig. 6 is a sectional View showing the parts separated.

Fig. '7 is a modified form.

The shell or socket I is preferably made of a phenol-formaldehyde condensation product which 4.0 is a well known synthetic resin. The shell or socket I is provided with an insert or cap 2, having a lateral projection 3a which is provided with two longitudinal perforations through which line wires W can extend. The cap 2 has a metal shell 3 connected thereto by a drive fit or other suitable means and the cap 2 is also provided with an enlargement 2a at its lower or inner portion. This enlargement or flange 2a rests upon a shoulder which is provided in the member I.

The metal shell 3 is provided with an outer covering 4 which is made of mica or other suitable insulating materials, and an electric heating coil H is wound upon said insulating cover or sleeve 4.

Another covering 5 made of mica or like material surrounds the heating coil H, and the outer cover 5 is provided with a tightly wound layer A of asbestos. The asbestos covering retains the coil H in position. Additional covering sheets 6 of mica or other insulating material can also be 5 utilized.

The heating coil H is provided with terminals T to which the wires W are connected.

In the modification shown in Fig. 7, the inner metal sleeve 3 is replaced. by a metal sleeve 35 10 which projects above the cap 2.

As shown in Fig. 4, the metal sleeve 3 extends through the cap 2 and it rests upon a shoulder which is provided therefor in the member I.

The shell I and the cap 2 can be held together 15 by means of cement C or by any other suitable means.

Experience has shown that in using devices of this character, the shell especially if made by the usual hot molding process, will blister. This 20 renders the device unsightly and in addition the blister is often accompanied with a noise which frightens the person whose hair is being curled.

I have discovered that it is possible to temper said resin after it has been completely molded by 25 the usual process. For this purpose, the molded piece (or pieces) of resin is subjected to a suitable heating treatment.

For example, the members I and 2 may be placed in a furnace where they can be subjected 0 to a first heat treatment at C. for a period of sixteen hours, and to a second heat treatment at C. for two hours. The pieces of resinous material are subjected to the action of the hot air in the furnace in a uniform manner during 5 the tempering treatment.

A temperature higher than 130 C. may be utilized in the last heating period of two hours. For example, temperatures of 0., 0., C. and C. may be utilized. 40

The length of the shell and of the heating. coil should. be preferably such as to permit the tempered shell to radiate heat sufiiciently to prevent the temperature of the metal shell 3 from exceding 455 F. when the device is in use. 45

The insulation exterior to the asbestos can be eliminated if this is desired. The device should be designed so that when it is in use its temperature does not exceed the maximum temperature in the tempering treatment. 50

The length and/or width of the shell can be suitably increased so as to prevent its temperature from exceeding the desired limit, when the device is in use.

While my invention has particular applica- 55 tion for use in connection with an electric hair curler, it is not necessarily to be restricted thereto as it can be applied for other purposes where said resinous material is subjected to a relative- 1y high temperature.

It is assumed in connection with this tempering process, that the synthetic resin which is used for making the shell I and the cap 2 consists substantially of the ordinary particles which are formed into the desired shape, under suitable heat and pressure.

Attention is called to the fact, that this supplementary heat-treatment of substantially pure phenol-formaldehyde condensation resin, pressed in hot molds, for the purpose of tempering the cooled and finished products, is not identical with the so-called baking process, used in the cold molding process to dehydrate the cold-pressed products and to facilitate the setting or polymerization of the constituents. It also has nothing to do with the heat treatment of so-called cured phenolic mixtures, mostly in laminated form, in which the liquid resin is only used as a resinous binder for asbestos, wood pulp, silica magnesite,

etc., and forms a minor portion of the mixture, said heat treatment after molding being employed to improve the dielectric strength of the mixture and generally being of longer duration and higher initial temperature than applicant's tempering process.

I have shown a preferred embodiment of my invention, but it is clear that numerous changes and omissions could be made without departing from its spirit.

I claim:-

A method of tempering the shell of a heater which has an electric heating coil therein, in order to prevent said shell from blistering when said shell is heated, said shell having been made by a hot-molding process from a phenol-formaldehyde condensation product, which consists in subjecting the finished shell to a supplemental heat treatment for about sixteen hours at a temperature of about 85 (3., and then heating said 20 shell for an additional period of about two hours at a temperature which is not less than about 130 C.

SAMUEL FREEMAN.

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