GB887002A - Improvements in or relating to the manufacture of circumferentially corrugated pipes - Google Patents

Abstract

887,002. Making corrugated pipes; stamping. PALMER AERO PRODUCTS Ltd., COOPER, T. H., and GOWARD, S. H. Sept. 9, 1959 [Oct. 27, 1958], No. 34333/58. Classes 83 (2) and 83 (4). A machine for corrugating pipes and tubes in which the pipe or tube is supported on a mandrel and a disc or ring of rubber or like resilient material is compressed and expanded by a pusher to expand the pipe into an annular die cavity surrounding the pipe is characterized by the provision of means for moving the die axially by a distance equal to the pitch of the corrugations and means for applying, during the expansion operation, an endwise force on to the pipe to tend to feed the pipe into the die from the unworked end of the pipe so that the tendency to draw material from a previously formed corrugation during the expansion of the pipe is reduced. The machine comprises a bed 10 supporting at one end a mandrel 12 on a pillar 11 and one or more steadies 14. At the other end of the bed is secured a cylinder block 16 providing two double-acting hydraulic cylinders 17, 18 having their rams 19, 20 in alignment along the bed. The ram 19 is in the form of a sleeve surrounding the ram 20 which constitutes a pusher for compressing and expanding a rubber disc 22 against the end of the mandrel 12. The outer ram 19 engages the free end of the pipe 23 to be corrugated to push the pipe towards the mandrel to prevent the tendency to draw material from a previously formed corrugation during the expansion of the pipe. Clamped to the centre of the bed 10 is a slidable bracket 26 carrying the split die 27, 28 formed internally with two and one-half annular grooves 29. The die is opened and closed by a double-acting hydraulic cylinder 30. An adjustable stop 37 limits the movement of the bracket 26, such movement being effected by a double-acting hydraulic cylinder 36. The end of the pipe projecting from the die is gripped in an hydraulically-operated split clamp. A guide 14 is provided for the pusher ram 20. In operation, the pipe is fitted over the mandrel 12 and the projecting end of the pipe passes through the die and over the pusher, there being a rubber disc 22 located between the pusher and mandrel. The die is closed on to the pipe and the tube is expanded into the innermost groove 29a of the die by compression of the rubber disc to form the first corrugation 41. The pressure on the rubber disc is released and the clamp 40 is closed on the pipe. The die is opened and moved one corrugation along the pipe, whereupon the clamp 40 is released and the die closed, to engage the formed corrugation in the second groove 29b. The die is advanced to the stop 37 carrying the pipe with it after which the next corrugation is formed as hitherto. An hydraulic pump supplies pressure fluid to the ram cylinders via control valves to effect automatic operation of the machine in the proper sequence. A trip device (not shown) may be pre-set to stop the machine after a predetermined number of corrugations have been formed.