US282879A

US282879A - Gakrett

Info

Publication number: US282879A
Authority: US
Publication date: 1883-08-07
Anticipated expiration: 1900-08-07

Description

(No Model.)

A D. GARRETT. PROCESS OF MANUFACTURING HEAD LIGHT REFLEGTORS.

Patented Aug. 7, 1888.

N. PETERS, Pho'vL'flhagnpMr, war-m m". D. c,

iDAvIs GARRETT, or PITTSBURG, PENNSYLVANIA, ASSIGNOR or oNEHAnE TO ALEXANDER coRnouo sAME PLACE.

PROCESS OF MANUFACTURING HEAD-LIGHT REFLECTORS.

SPECIFICATION forming part of Letters Patent No. 282,879, dated. August 7, 1583,

Application filed Junef), 1882. (No model.)

To aZZ whom it may cncern.-.,

Be it known that I, DAVIS GARRETT, of

;Io the art to which it appertains to make and use the same, reference being had to the accompanying drawings, which form a part of this specification, in which- Figure 1 is a sectional view of my mold. Fig. 2 shows the same with the copper blank formed thereon, and Fig. 3a section of the blank after melting out the mold.

This invention has for its obj ect a cheap and economical method of producing the blanks or shells for open-ended articles by electrodepositionthat is, large articles, which hitherto have been found impossible to produce commercially by the galvanic process, such as the large parabolic reflectors used for headlights. The well-known wax-matrix process cannot be adopted because of the impossibility of obtaining a uniform coating by reason of the tendency to most energetic deposition at the points where the circuit-wires join the sur- 0 face of the matrix. It has been attempted to make large surface deposits on a metal mold, and afterward separate the mold from the deposited shell by mechanical manipulation but it is found that such separation cannot be effected so reliably as to enable a commercial success to be accomplished. Hence it is found in the manufacture of such articles as headlight refiectors that success can be" reached only by hammering or spinning the copper blank to an approximately perfect shape, and

then smoothing out the hammer-marks or spinning-tool lines, which inevitably mar the inner surface of the blank.

My improvement consists in first making a mold or matrix of a metal or alloy fusible at a lower temperature than the metal to be deposited, such mold having its outer surface as true and smooth as the reflector is desired to be, then coating the end of the mold corresponding to the mouth of the reflector with a non-conductor of electricity-such as waxthen electrically depositing the copper or other metal on the uncoated surface to the required thickness, and finally melting out the fusible mold by heat and, further, inthe article so produced, as hereinafter described and claimed.

More particularly, my invention is as follows I make a mold, A, of type-metal or other metallic alloy fusible at a lower temperature than the metal to be depositedpreferably fusi 6o ble at the temperature of live steam, or thereaboutand having its outer surface exactly conforming to the reflecting-surface-desired. I make the mold A hollow for purposes of lightness, and have its outer surface highly finished. This fusible mold or negative A is formed by casting it in a metal flask or positive whose melting point is higher than that of the metal used for the negative, and whose surface is first turned to true lines, and then finished by grinding and polishing, or such other method as will reduce the positive mold or flask to the same condition of smoothness and perfect uniformity of surface as is required in the reflector or shell to be produced. From such a flask I can cast a large number of the fusible matrices; I then coat theend of the matrix or mold A at the part corresponding to the mouth of the desired reflector-blank with wax, asphaltum, or other conveniently applied non-conductor of electricity, after which I place the mold A in the platingsolution, connect it to the generator in the usual manner, and deposit the metal I) to the usual thickness. The mold A, being of solid metal, becomes an electrode of uniform conductivity, and hence the metal deposits uniformly and regularly over its surface, none, however, depositing on its coated portion. 'When the desired thickness has been attained, the mold andadherent deposit are removed from the plating-bath, and the fusible mold is melted out, leaving a reflector-blank of perfect form with a finished inner surface, which is at once ready for buffing, if it is to be used without silvering, or for silver-plating.

I use no grease, plumbago, or other substance to prevent adhesion of the deposit in order to facilitate the subsequent separation, but, on the contrary, use a clean surface, free' 100 from grease orplumbago, so that the resulting positive is perfect in all respects.

By the above process I can make the deposit heaviest when strength is neededi. e., at the eye of the reflector. This I effect by placing the mold with the small end downward in the bath, and by setting the anode nearer the mold at that end, so that the electrolytic action will be more energetic at that 'end and the deposit thicker.

I claim as my invention- The process of manufacturing head light reflectors consisting in preparing a positive flask or mold having its concave surface reduced to the condition of smoothness and uniformity required for the reflectors, then casting therein a negative mold of a metal or al- 10y fusible at alower temperature than the reflector metal, whereby the'surface of the negative obtains its finishwithont further manipulation, then coating the month end of the negative with a non-conductor of electricity,

then electro-depositing the reflector metal di-