US3472741A

US3472741A - Method of manufacturing metal articles by electroforming

Info

Publication number: US3472741A
Application number: US603780A
Authority: US
Inventors: Jan Leendert Melse
Original assignee: US Philips Corp
Current assignee: US Philips Corp
Priority date: 1965-12-29
Filing date: 1966-12-22
Publication date: 1969-10-14
Anticipated expiration: 1986-10-14
Also published as: NL6517056A; CH482027A; FR1506213A; DE1496945A1; BE691820A; GB1118150A

Description

United States Patent U.S. o1. 204-9 3 Claims ABSTRACT OF THE DISCLOSURE Method of making small diameter'thin walled tubing by electroplating on a metal wire mold having a high value of permanent elongation and then removing the mold by stretching the mold to reduce its diameter/An example of such a'wire mold is soft annealed coppenT his abstract is in no way intended to be a description of the invention defined by the claims.

The invention in this case relates to a method of manufacturing metal objects having channels of small diameter such as thin walled tubing having inner diameters of 1 mm. or less.

According to one method known in the art, such a metal object may be produced by electrodepositing metal on a wax mould having a conductive surface and then removing the wax mold by melting. However, this method has not proved too useful when employed for objects having small diameter channels since in such cases not only does the low rigidity of the mould constitute a problem but also the melting of the wax presents a problem due to the capillary action of the deposited metal.

In another proposed method, the metal is deposited on a metal mould of a chemically dissimilar metal which mold is removed by dissolving with a selectively acting reagent. However, this method has not proved too successful because the small surface area of the mold presented to the reagent results in a low rate of dissolving and therefore a slow procedure.

According to still another known method, metal is electrodeposited on a mould formed of a material which when heated to a high temperature has a rubber-like consistency and can be pulled out of the resultant outer metal shell. However, this method, which is described in German Patent 1,090,481, suffers from the fact that the mould material is easily broken thus causing broken pieces of mould material to remain in the channel and tends to adhere to the metal because of its adhesive character.

In the method of my invention, the above-noted difficulties of the prior art are eliminated or greatly reduced. According to my method, in order to produce a metal object having a very narrow channel, metal is electrodeposited on a thin metal wire mould formed of a metal having a high value of permanent elongation preferably of more than 20%, then loading the wire mold above its tensile limit until it decreases in diameter and finally fractures and then pulling out the two pieces of wire mould from the electrodeposited metal.

Soft-annealed metals such as soft annealed copper and aluminum wire having permanent elongations of about 30 to 40% are particularly useful for the wire moulds. Particular examples of such metals are disclosed in Colin 1. Smithells Metals Reference Book, vol. 11, published 1955 by Interscience Publishers, Inc., New York. Aluminum and aluminum alloys that may be employed are described in pages 714716. For example aluminum metals 3,472,741 Patented Oct. 14, 1969 ice and alloys (as designated in parentheses) of the following B.S./GE. specifications may be employed, S AO, E AM, S B-O, E B-M, SiCO, EiCM, NS O (Al-Mn), NS M (Al-Mg-Mn). Copper and copper alloy products that may be employed for the mould are described on pages 727-732. Some examples identified by the B.S. specifications or otherwise are: O.F.M. copper strip-annealed, H.C. copper B.S. 1432 strip-annealed, silver bearing copper strip annealed, tellurium copper rodextruded, cap copper B.S. ST A. 17-strip-annealed, brass 70/30 B.S. 267-strip-annealed, nickel silver 10% B.S. 709 strip annealed. Other suitable materials such as nickel and nickel alloys, zinc and zinc alloys and steels are disclosed on pages 754, 755, 760, 766, 767, 768 and 770 of this book.

Any metal that may be deposited by electrodeposition may be employed to form the metal object through which the channel is formed. Examples of such metal are nickel, copper, silver, tin, gold, chromium, cadmium and zinc.

My invention will now be described in greater detail with reference to the following example for the manufacture of nickel pipes having an inside diameter of 0.55 mm., an outside diameter of 1.1 mm. and a length of at least 15 mm.

Soft-annealed copper wire having a diameter of 0.55 mm. is stretched on a frame having a side of 300 mm. and then decreased cathodically for 30 seconds at room temperature in an aqueous electrolyte solution which contains per litre:

30 g. of sodium carbonate, calculated as anhydrous,

30 g. of sodium cyanide,

30 g. of sodium silicate, and

30 g. of tertiary sodium phosphate (with a current density of 4 A./dm.

Then the cathode frame with the stretched wire is rinsed in water, dipped for a moment in an aqueous solution of hydrochloric acid (1:10) at room temperature, again rinsed in water, dipped in a solution of 20 g. of potassium dichromate in water at room temperature for 5 seconds, again rinsed and then transferred to a nickel plating bath.

This bath has the following composition:

200 g. NiSO -7H O 2 g. sodium benzene disulphonic acid and water to 1 litre.

The bath was heated to 50-55 C. and the copper wires nickel plated at a current density of 10 A./ sq. dm. for 2 /2 hours. The wires were then rinsed in water and dried. The grown wires were cut off the sides of the frame and the nickel layer Was removed at the two extremities of the resulting pieces of wire. The copper wires were then elongated until they fractured. The pieces of copper wire were then pulled out leaving a resultant nickel pipe.

While I have described my invention in connection with specific embodiments and applications, other modifications thereof will be readily apparent to those skilled in this art without departing from the spirit and scope of the invention as defined in the appended claims.

What I claim is:

1. A method of manufacturing metal objects containing channels or holes of small diameters comprising electrodepositing a desired metal on a wire mould, said wire mould being formed of a metal having a high value of permanent elongation of more than about 20%, loading said wire mould beyond its tensile limit to thereby reduce the diameter of said wire mould and cause it to fracture and then separating said wire mould from the electrodeposited metal.

2. The method of claim? wherein the wire mould is OTHER RIg ERENCES 2x 53 25 5' d 2533 f fi s ggg i 2 3 331 2 i of Safranek, W. H., DOIlt Overlook Electroforming, June 3. Metal objects having holes or channels srnall di- 1961 Product Engmeenng 609414) ameter formed by the method of claim 1. 5 JOHN M ACK, primary Examiner R f es Cit d T. TUFARIELLO, Assistant Examiner FOREIGN PATENTS CL 153,231 10/1920 Great Britain. 204-4