GB295015A - Improvements in or relating to automatic lathes - Google Patents

Abstract

295,015. Halloy, A. d'. Aug. 5, 1927, [Convention date]. Lathes; tools. - In an automatic turning-lathe for producing profiled articles, the tool-holder is moved by means of continuously-variaable change-speed mechanism both in the direction of the lathe axis and perpendicularly thereto, this mechanism being controlled by a diagram or other templet based on the profile required for the finished work-piece. The displacements x and y which must be imported to the tool parallel to tie lathe axis and perpendicularly thereto in order to produce a particular work-piece are both functions of the time. Thus, assuming that x=u (t) and y=v (t) two diagrams are first prepared, one representing the function u (t) and the other the function v (t), and these diagrams are then employed to control the movements of a compound tool slide through the intermediary of continuously-variable geering. The diagrams may be traced on one or more drums or they may consist of cam grooves. The work-piece 2 is mounted between a headstock 4 and tailstock 3 and is shaped by a disc cutter 7 mounted on the tool carriage 6. The cutter is secured to a conical portion of a spindle 9 bv means of a sleeve 10 and nut 11. The sleeve 10 also carries a threaded sleeve 13 coacting with a nut 17 which is rotated through worm gearing from a handwheel 19 for longitudinal adjustment of the toolspindle. The tool-sp.ndle is rotated by a wormgearing 20 driven through a shaft 22 and further worm-fearing 25 from a shaft 26 driven from the headstock. The bearings of the tool-spindle are carried in an upper slide 29 which moves in vertical guides 30, 31 on the lower slide 32 and is operated to give the movement perpendicular to the lathe axis by means of screw and nut gearing 39 driven from a shaft 46 through worm-gearing 44, 42. The lower slide moves longitudinally on guides 33, 35 on the bed and is traversed by means of a screw 38 coacting with a split nut 97 and driven through worm-gearing from a shaft 59. In order to obtain constant speed of the tool over a profile such as that shown in Fig. 5, the longitudinal and transverse tool movements must be respectively proportional to Vcos t and Vsin t, Curves va and vP indicating the required speed diagrams in the longitudinal and transverse directions respectively are then traced on a drum 49, driven from the headstock and coacting with levers connected to rods 57, 58 which control the variable speed gearing. The gearing controlling the longitudinal screw 38 comprises a differential gear of which the outer member 61 is driven from a motor 64, while the planet carriers may be driven from braking dynamos or motors 71, 72. A clutch 73 is provided between the shaft 66 and shaft 59. The vertical movements of the slide 29 are controlled by a similar speed-changing device which drives the shaft 46 through bevel gearing 83. A clutch 90, interconnected with the clutch 73, is provided in this gearing. Both clutches are actuated either automatically or by hand by means of a rod 93. In order to return the tool slide longitudinally to its starting point, the half-nuts 97 are disengaged and the carriage is returned by rack and pinion gearing 95 actuated from a hand-wheel 96. The tool itself may be rotated back to its starting point by engaging a sliding pinion 100 with a fixed rack 101, a clutch 102 on the shaft 26 being disengaged. When profiles having acute angles are to be produced, a tool of the form shown in Fig. 8 may be employed. In the case of non-circular tools, the diagrams are obtained from the curve described by the axis of the tool when the section of the tool is rolled along the profile to be machined. Non-rotary tools may also be employed. In some cases the speed of rotation of the workpiece may itself be varied by means of a third change-speed mechanism acting on the headstock drive. Specification 293,390, [Class 38 (iii), Electric motor control systems &c.], is referred to.