GB703461A - Improvements relating to methods of and machines for making tubes - Google Patents

Abstract

703,461. Making tubes; uniting by fusion; coiling helices. MOND NICKEL CO., Ltd. Jan. 17, 1952 [Feb. 2, 1951], No. 1398/52. Classes 83 (2) and 83 (4) A process of making a tube by helically winding metal strip and welding the abutting edges of adjacent turns is characterized in that the welding is effected partly externally and partly internally, the depth of the penetration of the weld from the surface of the tube in each case being such that the two welds melt without any substantial interdiffusion between them, and one or both of the welds is or are autogenous to make one or both of the tube surfaces smooth. In tubes requiring a smooth internal surface the outside weld may be reinforced by a filler wire or electrode metal. Alternatively a filler wire or the like may be used on the inner weld to leave a smooth outer surface. The tube may be made from composite metal strip such as steel clad with nickel or nickel alloy, and the welding conditions are controlled so that the two welds meet at the junction of the base and cladding metals. Strip, graphite lubricated if desired, is fed by rollers 32 into a forming cylinder 11 through a slot 13 at an angle to the cylinder axis determined by the strip width and the outside diameter of the tube to be made. The abutting edges are welded internally by a welding head 15 mounted on a tube 27 and comprising a water cooled block 35 and rolls 19 geared together by wheels 22 and rotatable by a handle on a shaft 24. The tube 27 may be adjusted in position vertically and horizontally. The rolls 19 are pressed together by a screw 21 to grip a tungsten or like electrode 16, an inert gas, e.g. argon or helium, being fed to the electrode tip through a pipe 38 and passages 23, 34. On leaving the cylinder 11 the abutting edges of the strip are welded externally by a head similar to the head 15. In making tubes of small inside diameter, e.g. # inch, the electrode is introduced through the open end of the forming cylinder and is supported and controlled from outside. Examples of the application of the invention are given.