US3385697A - Key blank - Google Patents

Description

United States Patent 3,385,697 KEY BLANK Peter Ii. Kabeika, Torrington, Conn, assignor to Anaconda American Brass Company, a corporation of Connecticut No Drawing. Filed Nov. 9, 1964, Ser. No. 410,008 3 Claims. (Cl. 75-1575) ABSTRACT OF THE DISCLOSURE A key blank having the color, tarnish resistance, machinability and strength for good key formation having an alloy composition consisting of about the following percentages by weight: 58-61 percent copper, -15 percent manganese, 0.51.5 percent lead and the remainder zinc.

This invention relates to key blanks, and more particularly it relates to a key blank having a leaded coppermanganese-zinc alloy composition.

In the manufacture of key blanks careful consideration must be given to the alloy composition for it is not only important that the key blank possesses the desired properties for final formation into key form and subsequent lasting use, but it also must be economically competitive. This determination of whether the alloy is economically competitive involves an evaluation of the cost of production and the availability of the metals used in the alloy.

I have developed an alloy composition which is ideally suited for the manufacture of key blanks. The key blanks of the invention can be formed in a continuous series of operations from an initial continuous casting operation and is formed of Only metals which are readily available and relatively low in cost; and once formed into the key blank the alloy retains the necessary properties for ease of machining into the specific key shape and the good edge retention properties to hold the characteristic irregular key edge formations.

Broadly stated the key blank is formed for machining into specific key form and has an alloy composition consisting of about the following percentages by weight, about 58 to 61 percent copper, about 10-15 percent mangnese, about 0.5 to 1.5 percent lead and the remainder zinc. It was specifically found that a key blank having essentially the following percentages by weight, 59.5 percent copper, 12.5 percent manganese, 1.0 percent lead and the remainder zinc, gives all the required properties for good key formation and offers the economical advantages of being easy to mill and comprised of metals which are readily available.

In one example, an alloy composition having 59.5 percent copper, 12.5 percent manganese, 1.0 percent lead and the remainder zinc in percentages by weight was melt- 3,385,097 Patented May 28, 1968 ed and continuously cast into bar form by one of the known continuous casting techniques. The bar was successively hot and cold rolled with intermediate annealing to form a strip of about /2 inch thickness. The strip was finally reduced by cold reduction to a final strip size of about inch, which is one of many standard sized key blanks. The strip was characterized by relatively fine grain size in the order of about 0.065 mm. After final strip size was reached the strip was annealed at a temperature of 700 to 1500 F., it being found that at the higher an nealing temperatures the tensile strength and hardness of the resulting key blank was decreased and the percent elongation was correspondingly increased. Thus, this key blank alloy was found to be easily hot rolled and cold rolled and welded readily to give long coils for continuous strip rolling. Moreover when ultimately stamped into key blank form the key blank had the color, tarnish resistance, machinability and strength required for good key formation.

It is to be noted that the copper-manganese-zinc alloys heretofore developed, have never been used commercially because of the difliculty in casting high manganese alloys which resulted in the formation of a tough heavy skin of oxides which formed whenever the liquid alloy is exposed to air, as in pouring. By using a continuous casting technique so as to control the oxide skin formation, and varying the alloy composition so as to provide good machinability of the resulting key blank, the key blank formed is substantially free of oxide skin to the extent it is harmful and the key blank is easily machinable by known key making processes, usually filing.

I claim:

1. A key blank for machining into specific key form having an alloy composition consisting of about the following percentages by weight, 58 to 61 percent copper, 10 to 15 percent manganese, 0.5 to 1.5 percent lead and the remainder zinc.

2. A key blank for machining into specific key form having an alloy composition consisting of about the following percentages by weight, 59.5 percent copper, 12.5 percent manganese, 1.0 percent lead and the remainder zinc.

3. A key blank according to claim 2 having a grain size in the order of about 0.065 mm.

References Cited UNITED STATES PATENTS 2,347,706 5/1944 Moss -157.5 2,322,703 6/1947 Rodda 75157.5 2,479,596 8/1949 Anderson et al. 75157.5 2,772,962 12/1956 Reichenecker 75-157.5

DAVID L. RECK, Primary Examiner.

RICHARD O. DEAN, HYLAND BIZOT, Examiners.