Patent GB-867832-A (GB)
Title: Tube rolling machine and method
IPC: B21B21/00
Filed: 1959-05-19
Abstract: 867,832. Making seamless tubes; rolling. BLAW-KNOX CO. May 19, 1959 [June 6, 1958], No. 16944/59. Classes 83 (2) and 83 (4). In a method of rolling tubular blanks a pair of working rolls 15, 16 having opposed tapered die grooves 17, 18 for reducing tubular work "T" disposed between them are reciprocated, the working rolls engaging the work for the working stroke and then separating to disengage them from the work, the rolls being held apart during the entire return stroke of the rolls and being closed together to engage the work again at the beginning of another working stroke. The work is rotated and advanced during the return stroke of the rolls. The working rolls 15, 16 have bearing blocks 91, 92 mounted in a saddle 11 which is reciprocable on tracks 14 by cranks 28 and connecting-rods 29 driven by a motor 51, Fig. 1b (not shown), through gearing in housings 47, 48, Fig. 1a (not shown). During the working stroke of the saddle 11, which comprises 120 degrees of movement of the cranks 28 (see Fig. 17, not shown), the working pressure is applied to the rolls 15, 16 by stationary thrust-plates 22, 23 through backing rolls 20, 21 which are mounted on the saddle 11, the backing rolls 20, 21 being geared to the working rolls 15, 16, respectively and to racks 96, 99 on the thrust-plates for positive drive of the rolls. The thrust-plates 22, 23 are in turn supported during the working stroke of the saddle 11 by wedges 24, 25 which comprise several components linked together by cross-members 117, 127. The wedges 24, 25 are withdrawn just prior to the end of the working stroke of the saddle 11 and 8 degrees of crank after the rolls 15, 16 have ceased to work on the tubes " T " due to the relieving of the diesurfaces of the rolls at 230, 231, Fig. 18 (not shown), the wedge operation being effected by linkages driven by cams 67 attached to crankshafts 62 of the main drive (see Fig. 6, not shown). On withdrawal of the wedges the rolls move away from the work, the upper rolls 15, 20 sliding upwards in the saddle 11 under the influence of springs 102 while the lower rolls slide downwards under the influence of gravity, thus the rolls maintain contact with the thrustplates 22, 23 which in turn are maintained in contact with the wedges 24, 25 by springs 109, 112. The rolls 15, 16 continue out of contact with the work on the whole return stroke of the saddle and are riot again fully engaged with the thrust-plates until the saddle has moved through 20 degrees of its next working stroke. The rollers 15, 16 do not engage the work until 2 degrees of crank after the wedges are again fully in position due to the relieving of the diesurfaces already mentioned. During the movement of the saddle corresponding to 240 degrees of crank movement in which the rolls are disengaged from the work tubes " T " are advanced by approx. “-inch and also rotated through 75 degrees about their own axes by crossheads 32, 33 and 37. Gearing 184 rotates a shaft 38 intermittently through 60 degrees during the disengagement of the rolls, the shaft 38 driving a reversing gear operated by limit switches 211, 212, Fig. 7 (not shown), which reversing gear is used to operate feed-screws 34, 35 first in one direction and then in the opposite direction. The feed-screws which have opposite threads move the crossheads 3.3 and 32 in opposite directions toward and away from the roll-stand so that tubes are first gripped by the crosshead 33 and advanced towards the stand and then, on the crosshead 33 reaching the limit of its movement, the advance of the tubes is continued using the crosshead 32 while the crosshead 33 releases its grip and retires. At the point of transfer the crossheads 33, 32 are at their limit of approach towards each other. In addition to advancing the tubes in small steps, i.e. one step for each reciprocation of the saddle fluidoperated chucks in the crossheads also intermittently rotate the work through 75 degrees at a time. The machine may be kept in continuous operation by the use of fluid-operated mandrel locks 40, 41, the mandrels " M " normally being held in position during working by locks 41 during which time tubes may be fed on to the mandrels through an open lock 40, after which the locks 40 are closed while the locks 41 open to permit tubes to be fed forward by rolls 43, 44 to the crosshead 33. The locks for one mandrel may be operated independently of those for the other mandrels. Guides 45, 46 are provided before and after the rolls 15, 16 and a stationary crosshead 37 is provided to rotate the work after it has left the crosshead 32. The mandrels " M " are tapered and the die-grooves of the rolls 15, 16 shaped so that a constant percentage reduction is obtained along the length of the mandrel.