Patent GB-930711-A (GB)
Title: Improvements relating to corrugated tubes
IPC: B21D15/10
Filed: 1960-11-09
Abstract: 930,711. Making corrugated tubes; stamping. C. B. STANTON. Jan. 22, 1962 [Nov. 9, 1960], No. 38493/60. Classes 83 (2) and 83 (4). A method of making corrugated tubing comprises distending a discrete length of tube by hydraulic pressure applied directly to the tube wall and inside the tube, said discrete length being limited by dies surrounding the tube and by axially spaced seals inside the tube subsequently moving the dies relative to one another to crimp the distention into a corrugation, and feeding the tube relative to the dies and relatively stationary seals. Apparatus for carrying out the method comprises a hollow mandrel 10 provided with a head 11 and having spaced flexible seals 12 and 13 between which ports 15 communicate with the exterior of the mandrel from the central bore. An internally corrugated two-part holding die 17 and a sleeve-like crimping die 16 surround the mandrel. The crimping die is slidable into a counterbore in the holding die. In operation, the mandrel is located inside a tube 18 which is to be corrugated and the dies are arranged as in Fig. 1. Fluid pressure is supplied to the mandrel and the tube is distended at zone 19 as shown on Fig. 2. The distension is deformed by axial movement of the crimping die 16 towards the holding die 17 to produce the required corrugation, Fig. 3. In a modification, the seal 12 is replaced by a seal 71 of reduced diameter, Fig. 10, so that at high speeds of operation the seal does not foul the corrugation. When the hydraulic pressure is applied the seal is engaged by a sleeve 73 which expands the seal into engagementwith the tube before fluid pressure is supplied to the zone 82, through passages 80 in the sleeve. After the forming operation the resilience of the seal 71 returns the sleeve to its initial position or the sleeve may be spring- loaded. The holding die may act as a coining die to finally shape each corrugation. For installing the apparatus between the bed and ram of a high speed press the ram is provided with a cross-head 20 which carries a pair of holding die-loading members 21 and a pair of hydraulic fluid pumping rams 22. The rams and loading members are slidable in bores on a cylinder block 23 which is itself slidable relative to the cross-head and the bed 24 of the press. The pumping rams 22 are counter-bored to accommodate counter rams 22b secured to the press bed. The bores of the counter rams communicate through a passage 27 in a valve block 25 with the mandrel bore 28. The cylinder block 23 carries the upper half of the holding die and the lower half of the holding die is supported by the valve block. The die loading members 21 act to cushion the apparatus during rapid reciprocation of the cross-head. During operation the mandrel head adjacent the dies is required to be lifted and this is effected by a roller 58, Fig. 7, which is journalled on the crimping die below the mandrel and is engaged by a cam 57 which on rotation of a shaft 56 lifts the roller and hence the crimping die, mandrel and the tube. The shaft 56 is rotated by linkages attached to the links 47, 48 attached to the cross-head and which actuate the spring- loaded crimping die 41 for effecting the crimping and tube feeding operations. Downward movement of the cross-head closes the holding dies, pumps fluid into the mandrel to distend the tube, operates a rock-shaft 50, to actuate the links 47, 48 to crimp the distension, and on upward movement of the cross-head to open the holding dies, lift the mandrel and feed the tube forward.