GB347723A - Improvements relating to the manufacture of copper welded tubing- welded with copper - Google Patents

Abstract

347,723. Coating with metals. BUNDY, H. W., 4815, Bellevue Avenue, Detroit, Michigan, U.S.A. Nov. 2, 1929, No. 33371. Convention date, Nov. 21, 1928. [Class 82 (ii).] In a method of making copper-brazed tubing of steel &c. the tube, together with a supply of copper or brazing alloy having a copper base such as copper-silver, is subjected to a brazing temperature in a reducing atmosphere for a sufficient time to melt the copper and cause it to flow or creep between adjacent surfaces of the tube to braze them together and also to cover the walls of the tube both externally and internally with the copper &c. The tube is made from strip stock which may have been copper-coated on one or both sides or may be plain. The tube may be a double-walled tube, Fig. 1, a butt or lap-jointed tube or a lockseamed tube. The copper 10 may be fed in wire form to the interior of the tube or to the exterior or may be supported from a valve-controlled hopper in the form of a powder made into a paste with a binder. The copper when melted fills the joint and the spaces 11 and flows to the exterior of the tubes by capillary action. Strip metal may be fed from a drum 5a through sectioning rolls 6 and the copper supplied from a spool. The tube passes through an electric furnace 7 to heat the tube to 1100‹ C., the length and temperature of the furnace, and the speed of travel being such that the tube attains its requisite temperature when it reaches the outlet end of the furnace. The furnace is supplied through the tube 9 with a non-oxidizing gas such as hydrogen. The copper is set as the tube leaves the furnace, by passing the tube through a cooling chamber in the form of a water-cooled tank 20 with an inlet controlled bv a valve 22 and an exit 23. The tube is finally cooled by a spray 24 controlled by a valve 27. In an example, for forming a tube having a double wall of stock, a furnace approximately six feet long is used, the temperature therein being maintained at about 2000‹ F. and the tube being passed therethrough at a speed of about two feet per minute. The tube has a diameter of three-eighths of an inch, is made from stock approximately 0À015 inches thick and weighs about one pound per eight-foot length.