GB567745A - Improvements in the machining of irregular surfaces - Google Patents

Abstract

567,745. Lathes. BAUMANN, K., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. May 7, 1941, No. 5946. [Class 83 (iii)] Irregular surfaces extending mainly transversely to the axis are machined by copying mechanism, wherein a rotating cam or former imparts radial movement to a follower linked to or co-ordinated with a second follower to impart substantially axial movement to a tool or workpiece co-operating with rotating work or tool respectively. In a simple form, the work 2, Fig. 1, having an irregular surface 2b to be machined is carried by a holder 1a on a mandrel driven by the lathe and carrying a cam or former 10. A bell-crank 14 having a fixed pivot 15 has one roller 12 engaging the cam 10 and a second roller 13 engaging a surface 11 on the top slide 7 carrying the tool 3. The slide 7 is carried by a surfacing slide 8 biassed towards the roller 13, on ways carried by the saddle 4, by a spring 9. To enable a series of cuts to be taken, the bell-crank may have the inclination between its arms raised and the pivot 15 is carried by the saddle 4. The cam 10, Fig. 8, has a cylindrical portion leading into an arcuate portion and a tangential portion 10a and is so shaped that in the position where the maximum throw is under the roller 12, movement of the pivot 15 to the left in Fig. 7 causes a displacement of the roller 13 to the right sufficient to move the slide 8 to cancel out the movement of the saddle so that the tool 3 has no movement parallel to the axis. This enables a series of cuts to be taken as indicated by the dotted lines in Fig. 9, all terminating at the point 101. In a modification, the lever 14, Fig. 10, is fitted with a stop surface engaging an abutment 17 under the control of a biassing spring 16. The abutment for the roller 13 is also of cam formation. In further modifications, the cam 10 has its operative surface in a groove on one side instead of on the periphery; the bell-crank carried by the saddle is linked to the top slide 7 ; the spring-biassed slide 8 is omitted and the bell crank is inturned so that the roller 13 bears against a collar on the mandrel which is spring-biassed with respect to the cam 10. In a further modification, the lever has a fixed fulcrum 15 and the cam 10 and work 2 move axially together with the mandrel which is spring biassed at 1a with respect to the chuck. The tool slide 7 carries a cam abutment 11. In further modifications, the work is carried on the slide 7 and the tool by the mandrel ; a second bell-crank and cam 10 are arranged on the other side of the work and tool, and the tool slide is biassed so that first the surface 2b, Fig. 10, may be turned, then the surface 2a, and finally the surface 2c. During turning of the surface 2a, both cams and bell-crank are inoperative. Specifications 567,744, 567,746, 567,747 and 567,748 are referred to.