An Investigation of the Rolling of Cylindrical Tube by Grooved Roll

Abstract

The objective of this work has been the investigation of the processes in which tubes are rolled in the longitudinal mode through two driven, grooved rolls. These processes may be categorised as follows:- (i) Sinking, which is the simplest procedure, and in which the tube is passed through the rolls unconstrained and without internal support. (ii) Stretch-reducing, which is similar to sinking, but with the addition of axial tensions to the tube during rolling. (iii) Mandrel Rolling, in which the tube is supported internally by a bar which is free to move with the tube. (iv) Plug Rolling; this process, of rolling on a fixed mandrel, is the least used and has not been reproduced here. Knowledge is required of the way in which the roll separating force, rolling torque, and load distribution round the groove, vary for different conditions of rolling, e.g. the amount of deformation carried out in a roll stand, the magnitude of axial tensions, and whether the bore of the tube is unsupported or on a mandrel. Particular emphasis has been placed on the measurement of the load variation in the are of contact and round the groove, by the use of novel pin loadcells, A wide-ranging review of the development and application of this technique is presented. The almost entirely foreign publications concerned with these rolling processes are also reviewed at length. The setting up of an experimental mill for the rolling of lead tube as an analogue material for hot steel, with the measurement of all the parameters, is described. Results are presented of rolling trials in the three configurations enumerated above, and considerations are made of theoretical treatments of the processes, using equilibrium approaches, emanating from Russian sources. The complexities of the processes and the difficulties of analytical treatment are demonstrated, and further investigations are proposed.