US2180992A - Process for spinning together a metal and a ceramic article - Google Patents

Description

Nov. 21, 1939. a. J. MEYERS, JR

PROCESS FOR SPINNING TOGETHER A METAL AND A CERAMIC ARTICLE Filed Aug. 24, 1937 Inventor: George J. MegePs-Jn,

His Attorneg.

Patented Nov. 21, 1939 UNITED STATES George J. Meyers, Jn, Lynn, Mass assignor to General Electric Company, a corporation of New York Application August 24, 1937, Serial No. 160,639

3 Claims.

My invention relates to a process for spinning together metal and ceramic articles, and more particularly to a process for spinning aluminum reflectors on to glass globes of street lighting luminaires.

In the manufacture of street fighting luminaires, it is necessary to provide a tight joint between the metal reflector and the glass globe which encloses the open end thereof. The reflectors are generally made of a comparatively soft metal, such as aluminum, and the globes are made of a glass which may, or may not, be prismatic. The line of contact between these two members is circular, and is anywhere from 8 to 18 inches in diameter. The spinning of: these large units under ordinary circumstances and methods has resulted in a costly breakage of globes which made it impractical to unite the reflector and globe in this desirable manner.

I have discovered that this disadvantage is overcome by heating the reflectors up to a certain temperature range before spinning them on to the glass globes. By including this step in the process, a satisfactory dustproof and waterproof joint is obtained with only a small breakage of the glass globes which is substantially negligible.

One object of my invention is to provide a process whereby the breakage of glass globes during the spinning process is substantially ellm inated.

For a better understanding of my invention, together with other and further objects thereof, reference is had to the following description, taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the accompanying drawing, Fig. l illustrates a heating device for reflectors used in the manufacture of street lighting luminaires; Fig. 2 illustrates, partly in section, the assembled reflector and globe supported in a lathe ready for spinning the two together; and Fig. 3 illustrates an enlarged fragmentary cross-sectional view of the completed joint between the reflector and globe.

Referring to the drawing in detail, Fig. 1 discloses a sectional front elevation of a heater 5 which is a sheet metal cylinder open at the top and closed at its bottom by a heating unit 6. This heating unit is preferably an electric resistance unit supplied with current through the lead "I. The upper end of the heater is provided with supporting ears 8 bent inwardly to engage the edge of a metal reflector 9. This reflector is provided with a flange l0 and deflectors II, which project below the edge of the flange into the heater. The diameter of the flange I0 is such that it substantially closes the upper end of the heater 5, whereby practically all of the heat rising from the heater 6 is absorbed by the reflector. The reflector 9 is in the form of a conoid open at both ends, the upper end being provided with a flange l2, by means of which it is supported, and through which opening the lamp projects into the reflector, and is made of aluminum which is treated in accordance with a process known under the trade name Alzak. This process provides the aluminum with a hard specular surface having high reflectivity.

The reflector is heated to a temperature of the order of 88? C. which has been found to be. most suitable for this purpose. The reflector is then assembled with a globe l3, and is supported between the head stock I l and the tail stock l5 of a lathe by means of cupped supporting members l6 and 11. This step in the process is performed quickly so that the reflector temperature is not substantially reduced before the spinning operation. The assembled unit is then slowly turned and the flange ID of the reflector is slowly, crimped, or spun, to conform to the surface of ridges near the edge of the globe 83, by means of a tool l8 resting on a tool rest l9.

In Fig. 3, I have illustrated an enlarged sectional view of the joint formed, as above described, between the reflector 9 and the globe H3. The globe i3 is provided with a pair of parallel ridges 20 and 2! between which a groove 22 is formed. The flange I0 is first slowly formed around the first ridge 2|], then slowly turned into the groove 22, and finally the end thereof is formed about the second ridge 2 I. In this manner, a wide contact surface is obtained between the reflector metal and the surface of the glass globe l3.

The process, as above described, has substantially eliminated glass breakage during the spinning process, and has made practicable the spinning together of aluminum reflectors and globes of luminaires in large quantities. I am not certain at present of the exact theory upon which the success of my'above-described process rests, but I believe it to be due to the high coeflicient of expansion of aluminum. When the flange of the reflector is cold spun on to the glass globe, considerable pressure must be exerted by the operator in an attempt to obtain a joint which is sufilciently tight to prevent water getting into the luminaire. Furthermore, due to the resiliency of the metal, the metal springs away from the glass flange and it is almost impossible to get awatertight flt between the metal and the glass. In attempting to make such joint sufliciently tight to pass inspection,,the operator exerts a greater pressure than is permissible, with the result of excessive breakage of globes.

By preheating the reflector, as above described, the reflector is expanded, and simultaneously, the oxide coating in the aluminum is softened so that the aluminum becomes more pliable and responds to the tool of the operator more readily than when it is cold. As a result thereof, the force required to spin the metal into the ridges to form the joint is minimized, and after the reflector is cooled to the temperature of the globe, the metal contracts and the joint becomes tighter than was possible to obtain with the cold spinning of the reflector.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The process of spinning an aluminum reflector on to a glass globe which comprises heating said reflector to substantially expand said reflector without injuring its reflecting surface, assembling said reflector and globe, and turning the assembled unit while spinning the flange of the reflector over a cooperating flange on the glass globe.

2. A process of joining an aluminum reflector and a glass globe to form a dust tight unit comprising heating the reflector to -a temperature of the order of 88 C., and thereafter spinning the edge of said reflector over a cooperating flange on the edge of the globe.

3. The process of spinning an aluminum reflector on to a glass globe which comprises heating said reflector to a temperature of the order of 88 C., and thereafter spinning the edge thereof over the edge of a glass globe before the reflector has had time to cool.

GEORGE J. MEYERS, JR.

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