GB240902A - Improved process and apparatus for ensuring the straightness of metal tubes, and strips of angle or other form, during heat treatment - Google Patents

Abstract

240,902. Armstrong Siddeley Motors, Ltd., and Wylie, H. N. July 3, 1924. Annealing, tempering, and otherwise modifying physical characteristics of metals.-In a process for ensuring the straightness of metal tubes and strips during heat treatment, a pair of tubes &c. are arranged in spaced relationship side by side, one pair of their adjacent ends are anchored and connected respectively to electric leads, and the other pair of adjacent ends are electrically connected together and attached to adjustable loading means for tensioning the tubes &c. during heating and cooling, or the electrical connections may be transposed and the current led in at the loaded ends. Two strips &c. 1, 2 in a muffle 7 are clamped at one end to insulated brackets 4 connected by metal strips 8 to electric conductors 9, 10, the other ends being gripped by clamps 12 connected electrically by a bridge 13 and attached by yokes 14 and insulators 16 to weighted cables 15 passing over pulleys 19. Pivoted levers 22 in pin-and-slot connection with the rods 20 carrying the weights 21 may be provided for taking the load off the strips 1, 2. Cooling fluid may be admitted to service pipes 33 arranged round a channel 32, or cooling may be accelerated by flooding with water or passing non-oxidizing gas such as hydrogen through the muffle. The loading device, levers 22, or other moving part may be arranged to contact with a current breaking switch when the straightening of the barsunder treatment has taken place. One of the strips may be replaced by a low-resistance conductor when a very heavy current is to be applied or one strip only is to be treated. In another arrangement the strips may be suspended at one end and loaded to hang vertically. The earlier Provisional Specification also describes an apparatus wherein a metal strip to be treated is attached to the lower ends of a fixed cross-piece and a pivoted adjustable cross-piece on a compression bar or strut, tensioning means being provided between the upper ends of the cross pieces, and such apparatus may be suspended from a trolly movable on rails into and out of a muffle.