Patent GB-952358-A (GB)
Title: Improvements relating to methods of an apparatus for flow-working of metals
IPC: B21D22/16
Filed: 1959-09-08
Abstract: 952,358. Spinning. J. A. GRAINGER. Sept. 8, 1960 [Sept. 8, 1959], No. 30549/59. Heading B3J. A method of flow working is characterized in that penetration of the workpiece by the roller, wheel or ball element is determined by applying to the roller element a yieldable inward thrust, limiting the extent of inward penetration of the roller element relative to the workpiece without reliance upon the counter thrust of the workpiece, and limiting the extent of outward displacement of the roller element in consequence of any increase in counter thrust by backing up the roller element with positively acting stopmeans which are normally relieved partly or wholly of load by the existence of the yieldable inward thrust. Apparatus for carrying out the method comprises a mounting 10 for a tool support 11, the mounting having a guideway 14 for receiving a slide 15 movable parallel to the axis of rotation of a mandrel 12 to which the workpiece is secured. The slide 15 also has a guideway 17 for receiving a further slide 19 movable towards and away from the mandrel. At its forward end, the slide 19 carries a roller 13 in an adjustable forked element 20. At the rearward end of the slide 19 is a thrust roller 26 journalled in anti-friction bearings 27 in a mounting block 28. The slide 19 is formed in two parts 30 and 31, the forward part 30 being movable towards and away from the mandrel thereby adjusting the effective length of the slide 19. This adjustment is effected by means of a screw-threaded sleeve 32 and a nut 35 provided with a worm-wheel 38 co-operating with a worm 39 driven from a hand wheel 40. The slide 19 is urged towards the mandrel by a yieldable thrust produced by a pair of hydraulic rams 44 (Fig. 2) which produce a working pressure of 400 tons/square inch suitable for working stainless steel. The ram cylinders are mounted on the slide 15 and hydraulic fluid to the rams is controlled by valve means 46 operated by a sensing element 47 which on rearward movement reduces the fluid pressure and on forward movement increases the fluid pressure so that the slide 19 remains in a constant position determined by a template 49 which conforms to the profile of the mandrel. Since the counter-thrust from the workpiece is not constant, there is a tendency for the clearance 51 to vary and to prevent this, a stop-member 52 having a control surface 53 conforming to the profile of the mandrel is provided. The control surface 53 engages the thrust roller 26. Feed movement in the direction of traverse is effected by a motor-driven lead-screw 55 engaging a threaded block on the underside of the slide 15. The output element of the servo means thus exerts a yieldable thrust which can be overcome  by temporarily increased counter thrust afforded by the material of the workpiece to traversing movement of the roller element but which is then immediately resisted by the lead-screw 55 acting as a positive stop means in a manner similar to the stop member 52. The apparatus may be used to form a thickened rim on a sheet metal disc-like workpiece.