GB214130A - Improvements in and relating to electric tube welding machines - Google Patents

Abstract

214,130. Schr÷der, E. June 27, 1923. Welding.-In an electric tube welding machine of the type having several electrical rollers working on the same seam, the pairs of pressure rollers are connected bv a short circuit contact so that the greater portion of the current passes over this contact instead of through the tube and thus excessive heating of the tube is prevented. The electrode rollers c<1>, c<2>, c<3>. Fig. 1, are connected to the free poles of a three-phase transformer in star fashion and the upper rollers a of the pairs of pressure rollers a, b, which are preferably made of bronze or other non-magnetic metal, are connected by a short circuit contact k consisting preferably of a series of strips k<1> of copper, so that each roller may be independently adjustable. The short circuit contact may consist of a bearing-block m, Fig 4, in the form of a water trough m for cooling the pressure rollers b, the front wall of which has open bearings and the rear wall bushes d to receive the spindles of the pressure rollers b. The upper portion of the bushes and of the rear wall mav be detachable so as to facilitate removal of the rollers. Two or four electrode rollers may be used in conjunction with one or two single phase transformers, or six electrode rollers may be carried by a transformer with six free poles. The tube may be advanced uniformly and the current interrupted at regular intervals, or welding may be effected step by step, the welding points being separated so that the welding points of the following rollers fall between the welding points of the first roller.