Apparatus for producing a tube with successive corrugations of different radial extensions and spacings

摘要

Apparatus for producing a tube with successive corrugations of different configuration from a tubular blank of uniform diameter mainly comprises a central pin having a shaft portion fixed only at one end to a stationary support and having at the other end a radially enlarged head portion cooperating with radially inwardly movable clamping and forming jaws to clamp a portion of a tubular blank therebetween. The apparatus includes further a tubular member guided on the shaft portion of the central pin and movable in axial direction by hydraulically operated members cooperating therewith. The tubular member supports the blank on the inner surface of the latter and cooperates with a plurality of clamping fingers arranged axially spaced from the head portion about the outer periphery of the blank and being movable by a hydraulically operated clamping piston between a clamping and a releasing position, whereby between the head portion, one end of the tubular member and the clamped portion of the blank an annular expansion space is formed into which fluid under pressure is fed, to cause outward bulging of the blank between the clamped portion thereof. The above-mentioned hydraulically operated members comprise an upsetting cylinder connected at one end to the other end of the tubular member and including a radially enlarged portion in which the clamping piston is housed, and a corrugation cylinder cooperating with the upsetting cylinder for moving the latter between a rest position and an advanced position. In order to adjust the upsetting stroke and therewith the radial extension of the corrugations to be formed, a pair of annular discs are turnably, but axially immovably mounted on opposite ends of the corrugation cylinder and having a plurality of circumferentially displaced axial projections of different axial lengths which can be respectively brought into alignment with abutment members provided on the enlarged portion of the upsetting cylinder and the support.