Patent GB-135482-A (GB)
IPC: B23K11/10
Abstract: 135,482. Schroder, E. June 12, 1918, [Convention date]. Welding.--In an electric seam-welding machine, for welding the longitudinal seams of tubes which are presented open to the machine, of the type in which the work is fed' by a step-by-step motion between a fixed mandrel electrode and a co-operating roll electrode, the roll electrode is simultaneouslv traversed in the same direction as the work when the current is off and the pressure released and the current is then switched on and the elec. trode then traversed under pressure in the oppo site direction to perform the welding, the work being stationary. The lower electrode consists of a fixed mandrel 20, Fig. 1, and the upper electrode a travelling roll 3. The tube is fed forward step by step by a moving rack 26 operated by a cam on the main shaft 12 and pawl lever 24. The supporting-roller 22 in this motion is moved by a cam 23 engaging the roller 37 close up to the mandrel so as to free the tube. The seam behind the mandrel is open and is closed by side rollers in front of the carrier 21. The roll 3 moves simultaneously with the tube in the forward movement by the action of an eccentric, being preferably raised out of contact therewith. The current is then switched on by an adjustable segmental switch on the main shaft and the roll is traversed rearwards over the stationary tube to perform the welding operation, pressure being put on by the cam 23 engaging the roller 27. The Specification as open to inspection under Sect. 91 (3) (a) states also that the roll 3 may be operated by a ratchet gear, crank, and cam, and that an eccentric may be used to operate the feed of the crank. It also states that the switch may be an oil switch. Further forms are also described. In one form a fixed roll electrode is oscillated forward and rearward different amounts so as to traverse the work, such as sheets, a greater distance, e.g. 10 mm. in the forward direction than in the rearward direction, e.g. 8 mm., the current being automatically switched on and welding performed in the rearward motion. In the latter form, Fig. 1, (Cancelled), the electrode 3 is oscillated by a toothed wheel 7 and pawls 9, 10 carried by a lever 11 fixed to a connecting-rod 8 which is operated by a cam or crank on the main shaft. The rod 8 may be fixed to various points on the lever to vary the arc of oscillation. The pawl 9 for a portion of its motion is held out of contact with the wheel by a segment 13 so as to reduce the rearward motion of the electrode. The segment is ajustably pivoted on the shaft 6 and secured in position by a screw. The connecting-rod has lost motion so that the switches 15, 16 are in contact only during the rearward motion. The electrode is carried by a lever pivoted at 2 and the pressure is put on by a cam 17 which depresses a roller 18 on a rod provided with an adjustable spring 19. To prevent the rolling forward of the excess metal towards the end of the seam, the pressure of the electrode may be less during the forward then the rearward motion. In the case of thick material, however, the method may be reversed so that the sheets may be pressed together. The mandrel may be rotatable about a longitudinal axis so as to bring fresh portions into line with the seam. In welding tubes, the seams of which are presented closed to the machine, the tube is filled by a mandrel 40 not forming an electrode, Fig. 6, (Cancelled), and supported by a roller 39. One electrode 32 runs along the seam and the other 31 along the side of the tube. In a modification, both electrodes may run along the sides of the tube, and a separate roll along the seams. In a further modification, the side rolls may be connected to one pole and the seam roll to the other pole. During the feed motion of the tube the mandrel moves with it, and, during the welding, the mandrel is withdrawn through the tube. This subject-matter does not appear in the Specification as accepted.