GB493405A - Method and apparatus for reducing tubular blanks - Google Patents

Abstract

493,405. Rolling tubes. KRAUSE, F. R. Dec. 2, 1937, No. 33405. Convention date, Dec. 2, 1936. [Class 83 (iv)] A tube 26 on a mandrel 24 is reduced, hot or cold, by one or two pairs of grooved rolls 14 and 18 which are rolled along and pressed on the tube by hardened shaped platens 7, 8, mounted in a housing 1 reciprocated by a crank disc 5, the tube being freed from roll pressure on the return stroke so that it can be given an increment of feed along the fixed mandrel. A hydraulic piston-rod 33 fixed on the roll housings 9 cause the roll to lag behind the return of the platens, so freeing the rolls from pressure after which fluid pressure is reversed to the right end of the cylinder 32, to bring the roll surfaces in contact with the platens for the next working stroke. The housings of each pair of rolls are held together by a spring 36 to allow relative movement. A fluid pressure tube clamp 69 is actuated, e.g. from the reciprocated housing 1 to hold the tube during working and to unclamp it for an increment of feed by a hydraulic cylinder 56 that pushes along the carriage 51 of the chuck 54 so moving the tube along until the carriage comes against a stop 58. This stop has been travelling along its screw 61 during the working and return strokes, the screw being rotated by belt 62, variable speed drive 63, and shaft 64 coupled, e.g. to the main shaft. At intervals the mandrel is pulled back through the tube by hydraulic cylinder 99 which also serves to strip the mandrel from the finished tube. The chuck 54 and tube and mandrel is rotated step-by-step during the release of the clamp 69, through gears 71, 72, shafts 73 and 74 by ratchet pawl 79, Fig. 6, the housing 81 of which is oscillated by a connecting rod 84 moved up and down by lever 86 by a cam 87 driven by a chain wheel from the main drive shaft 64. A safety device is provided by the stronger spring 98 which in case of jamming is depressed instead of the spring 94. When the chuck 54 has travelled as far as the clamp 69, it may be released and backed off and reclamped further back on the tube or on mandrel rod itself. The pointed mandrel gives a thicker and stronger end to the tube so preventing splitting. Alternatively, the carriage 1 may be stationary and the tube may be reciprocated through the mill. If three pairs of rolls are used, the tube turning mechanism may be omitted. The roll necks of each pair are geared together to maintain accurate registering. The rolls 14 have outwardlyflaring grooves to allow spread of the tube during reduction while the rolls 18 have semicircular grooves to finish the tube surface.