GB503059A - Electrically controlled device for obtaining varying pressure in a cylinder with an operating period - Google Patents

Abstract

503,059. Pneumatic pressure apparatus ; welding. KNORR-BREMSE AKT.- GES., and SPRINGER, O. July 15, 1938, No. 21013. Addition to 487,530. [Class 8 (ii)] [Also in Group XXII] Electrically - controlled pressure - producing apparatus according to the parent Specification is modified in that the pressure cylinder contains two pistons having a portion of the stroke in common, the piston having the larger stroke carrying out the work of placing. the electrode into position and the other piston having the shorter stroke carrying out the exertion of, the variable pressure required during the working process of a welding machine. The cylinder 11 is equipped with a large piston 21 which itself forms a hollow cylinder and contains a small piston 23 limited in respect of the piston 21 by a flange 30 and is secured to a rod 22 which holds the electrode. The piston 21 has a hollow trunk rod 24 which is coupled by flexible pipe 27 with a pipe 26 passing to the main air supply which moves the piston 23: The supply to the piston 21 is by a pipe 28 from the controlling valve 29 and the return of the piston away from the work is effected by pressure through the pipe 17. The general apparatus according to the parent Specification is modified in that a second reducing valve is fitted between the cylinder and the step-by-step control member. In a further modification the second pressure stage is arranged to be independent of the first and is led to the cylinder on the inner side of the first stage reducing valve, and may then be set to work at a higher pressure.