Patent GB-188690-A (GB)
Title: An improved method of electrically butt-welding apparatus for and tubing produced thereby
IPC: B23K11/06
Filed: 1921-05-18
Abstract: 188,690. White, A. E., (Elyria Iron & Stecl Co.). May 18, 1921. Tubes.-In a process for electrically butt-welding thin walled tubes the pressure closed seam cleft is traversed by impulsive welding current while the tube is fed continuously forward so that the metal at successive parts along the seam is subjected to different and regularly recurring temperatures according to the variations of the current flow. The highest temperature attained may be just sufficient to cause fusion while the lower temperatures do not reach the fusing point of the metal. A variable speed motor 26 drives a main power shaft 28 through a chain 27 and clutch 29 the latter being connected through lever mechanism to a rock shaft having a number of auxiliary hand levers 36 so that the machine may be readily stopped by the operator from any position. A flat strip 21 is first shaped to circular form 22 by a series of top and bottom rolls 40 - - 44 and two pairs of idler side rolls 50, 51. The sets of rolls are carried on a base plate 54 transversely movable from a shaft 57 driven through bevel gearing, shaft 62 and spur reduction gearing from the main shaft. In certain cases some of the upper rolls may be driven from the lower rolls by gearing comprising spur gears 77 and universal couplings 81 Fig. 3. Any tendency of the tube to twist during its passage through the forming-rolls is corrected by a guiding- device comprising a lower roll and an upper roll 115, the latter being provided with a fin 120 which fits the gap between the seam edges, of the tube. Vertical and horizontal transverse adjustments of the guiding-rolls are effected by means of hand wheels 101, 96 respectively while rotational adjustment is effected from a hand-wheel 111 through worm gearing 109. The welding- apparatus is mounted on a vertically adjustable box-shaped casting 121 supporting slides 131, 134 transversely adjustable from a screw 132 and fitted with pedestals bored to receive the ends of a supporting roll 137. The upper ends of the pedestals carry skeleton uprights 138 on which the journal ends 141 of the idler welding-rolls are adjustably mounted. The welding-rolls together with the supporting-roll form a throat completely surrounding the tube and of such size that the necessary seam closing pressure is applied during the operation. Axial alignment of the rolls is secured by a fibre ring 156 of mica or other incombustible material. The welding-rolls are cooled by a water circulation as shown in Fig. 7. The current is obtained from a suspended transformer 24 connected to a pair of annular brush holders 180 carrying brushes 182 contacting with the hub 181 of the welding rolls. The supporting-roll 137 is positively driven at the correct speed from a shaft 162 driven from the main shaft 62 through bevel gearing 177 and change gears 172. The shaft 162 further drives a pair of adjustable finishing-rolls 166 and a final idle roll 169 may be provided to bend the finished tube slightly to counteract the curving tendency due to the contractile effect of the hot metal on one side of the tube. In an example given tubes of one inch diameter are produced from .025 in. gauge stock at a rate of 10 feet per minute using a 60 cycle alternating current of 12,000 amps at 1.5 volts.