GB643962A - Engine lathe - Google Patents

Abstract

643,962. Lathes. MACKINTOSH-HEMPHILL CO. Sept. 4, 1944, No. 16875. [Class 83 (iii)] A lathe comprises parallel power and lead screws extending longitudinally of the lathe bed and interconnected by gearing, a first actuating means on the carriage engageable directly with the power screw for moving the carriage longitudinally, a second actuating means on the carriage engageable directly with the lead screw and constituting an alternative carriage drive, and means driven from the lead screw for effecting transverse movement of a cross slide or tool rest on the carriage. The drive connections are shown diagrammatically in Fig. 1, where an electric motor 5 drives headstock gearing for the spindle 4 and drives a feed gear-box 9 through pick-off gears 8. The shaft 10 from the feed gear-box drives the lead-screw A through reverse gearing 11. The two carriages F and G, Figs. Va, Vb, may be fed longitudinally from the lead-screw A for screwing operations through split nuts a, a<SP>1</SP>, and transverse feed of the tool slides is effected through reversible clutches 38 and gearing 18, 19. The clutch parts 38 slide along the screw A and engage a groove in the shaft to transmit the drive. The carriages may also be fed longitudinally by power screws B and C driven from the screw A through disengageable gears 12, 13 and a reversing drive 15, or the gears 12, 13 may be disconnected and the power screws driven independently by an electric motor 16, Fig. Vb. This arrangement enables predetermined tapers to be cut which are independent of the speed of the spindle drive. The power screws B and C, Fig. VI are arranged in a well in the bed and a splitnut 40a, 40b controlled by a rod 49 with right and left-hand threads is provided on each carriage. The rod is rotated from a handle 42 through a toothed segment and pinion and is interlocked, Fig. VIII, with the handle 43 for controlling the split-nut 41, Fig. XI, connecting the carriage to the lead screw A. The interlocking discs 47, 48 ensure that only one power screw is engaged at a time. An interlock is also provided for the control handles (not shown), of the feed-box 9 to prevent more than one gear train being engaged at one time. The reverse gears enable the carriages to be driven in the same direction either towards or away from the headstock and in opposite directions, Further gear trains are provided to give automatic feed to the actual tool slides. The main drive motor 5 cannot be operated until oil pressure in the headatook has been built up to a safe value and the motor 16, which is used also for rapid traverses, cannot be engaged while the gears 12, 13 are in mesh or when the screws B, C are connected through pinions on the tumbler of the reversing device 15.