US1759099A - Process of manufacturing reflectors - Google Patents

Description

Patented May 20, 1930 UNITED STATES PATENT OFFICE" CHARLES W. DAKE, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE PYLE-NATIONAL COM PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF NEW JERSEY" PROCESS OF MANUFACTURING REFLECTORS No Drawing.

My invention relates to improvements in process of manufacturing reflectors for head lights and the like and has for one object to provide a new and improved process whereby by a combination of chemical-deposition andv ble with silver is'that it is soft, tarnishes and must be carefully protected against the weather, dust, dirt and the like and is exceedingly diflicult to clean without scratching and destroying its brilliancy. Chromium on the other hand, while it is less eflicient than silver, its initial efliciency being only sixty-five percent ascompared with silver at eighty per-- cent, is an exceedingly hard metal. Rubbing it and cleaning it does not scratch the surface, it does not tarnish, it does not become dull and lose its lustre. Therefore, while chromium at the start may not be as eflicient as silver, inside of a very few days silver will have lost its efliciency to the point where it is much less satisfactory than chromium. Chromium when deposited by electroplating is not a strong metal, in fact it is not strong enough to support its own weight and it is necessary to provide some means for supporting it. This generally takes the form of a backing of copper and the like and in view of the softness of copper and the hardness of chromium it is necessaryto interpose between them such other material as nickel as the nickel gives the chromium such support as avoids the danger of scratching or cutting through the chromium into the copper.

In carrying out my process I first cut a mandrel of glass or other non-condu :ting ma-' terial, the working surface of which is properly ground so as to form a reflecting surface with a conducting material. This material is deposited chemically as for instance by pouring silvernitrate over the form or bowlwith I metallic silver which coats the form.

a reducing agent to cause the deposition of Then I immerse the form in a bath and deposit by electroplating a thin layer of chromium.

Application filed March 19, 1926. Serial No. 96,078.

Since the metallic silver or other conducting layer completely covers the bowl or form the chromium layer will also cover the form com-' pletely. The form with its coating or layer of chromium is then immersed in a different bath and a thin layer of nickel is deposited on the back of the chromium layer. After that is done the entire assembly is deposited in a third bath and a layer of copper is built up to any suitable thickness, perhaps one sixteenth of an inch backing up the nickel and supporting it and'the chromium.

The outer edges of the layers or sheets are then cut off around the form so as to give a shape conforming to the desired shape of the reflector. This tends to release the entire metallic reflector bowl from the form and permit air to enter in between to break the vacuum. The reflector is then removed from the'form and the initial chemically deposited conducting coating or layer is removed from the chromium, thus leaving a chromium reflecting surface .conforming in every respect to the surface of the form and backed up by a reinforcing layer of nickel and a supporting body of copper.

The same general process can be made use of in connection with the depositing of other metals, and the formation of metallic selfsupporting reflector bowls from such metals. For instance instead of depositing chromium on the chemically deposited conducting layer I might deposit a layer of silver and back it up by copper. The advantage of this would be that experience shows that silver, chemically deposited is always porous, no matter how much silver you try to put on by chemical deposit you cannot get a completely opaque sheet of silver. It must be-backed up by an additional silver deposit put in place other than by chemical means and this can be done by electroplating. Another modification of my process may take the form of first depositing a silver coating by chemical means on the outside of a glass reflector bowl, then electroplating a further silver coating on the chemically deposited sheet, then backing this with a thin layer of copper, and relying on the glass of the bowl to support and protect the silver and keep it from tarnishing and lOO scratching. This is satisfactory in that it gives a permanent reflecting surface but the efliciency of the chromium reflector is greater because of the absor tion of the light rays in the glass of the light owl.

I claim:

1. The process of making reflectors which consists in chemically depositing a coating of conducting material on a non-conducting form, electroplating thereon a layer of chromium, then electroplating on the chromium a reinforcing layer of nickel, then electroplating on the nickel a thick supporting layer of copper, then cutting away all said layers about the edge of the form to free them, removing the assembled reflector from the form and then removing the conducting ayer.

2'. The process of making reflectors which consists in depositing a coating of conducting material on a non-conducting form, electroplating thereon a layer of chromium, then electroplating on the chromium a reinforcing layer of nickel, then electroplating on the nickel a thick supporting layer of copper.

Signed at Chicago, county of Cook and State of Illinois, this 10th day of March, 1926.

CHARLES W. DAKE.