GB561727A - Improvements in or relating to carriages for lathes - Google Patents

Abstract

561,727. Cam mechanism. TAREX, S. A. Feb. 15, 1943, No. 2479. Convention date, March 14, 1942. [Class 80 (iii)] [Also in Group XXII] An automatic lathe having a lower crossslide 6 and an upper longitudinal slide 11 actuated by cams 5, 8 respectively has means for adjusting the effective length of the cam 8 so that different longitudinal traverses may be effected without changing cams. The cam 5 which is mounted on a shaft 4 acts through a toothed sector engaging a rack 26 on the slide 6. The cam shaft 4 is connected by bevel gearing 10 to the shaft 9 of the cam 8 which acts through a slotted bell-crank lever 22 carrying a screw-adjusted pin 20 engaging a slot 19 in a head 18 secured to a sliding rod 14 which through an adjustable abutment screw 17 engaging a rib 17b imparts positive movement to the slide 11, return being effected by a spring 12. The return is limited by an abutment screw 25 so that by adjustment of this screw, which alters the starting position of slide 11, the effective length of cam 8 is altered and different longitudinal traverses may be effected by the same cam. The screw 17' provides a second adjustment for the feed of the slide 11 since for any set position of the screw 25 the length of rod 14 may be increased or decreased to deterinine the extent of the feed movement to the right. The cam 5 consists of two parts 5a, 5b having inter-engaging serations so that the parts may be adjusted on each other to vary the length of the peripheral arcuate surface 33b, Fig. 4, the cam as a whole being adjusted on the shaft by a serrated ring 43 coacting with serrations on a fixed ring 41. The pin 20 is adjusted along its slot to vary the speed of the feed movement in accordance with the material being macliined. The length of the circular part of the cam 5 is adjusted to vary the time of the dwell of the cross-slide in its forward position and this is set in accordance with the time required for the effective part of cam 8 to impart the longitudinal feed. The cam 8 may also be adjustable on its shaft. By the above-described adjustments the machining operations are effected during the maximum fraction of the revolution of cam-shafts 4 and 9 and both cam-shafts may be speeded up during the non-operative part of their rotation thus minimising production time. In a modification, in order to avoid variations in the speed of feed rod 14 due to the angularity of lever arm 22 to the cam 8, Fig. 7, acts through a sector 50 on a slide 53 carrying a head. 56 provided with a slot 57 engaging a pin on the rod 14 so that by angular adjustment of the head the speed of the rod 14 may be varied. In this case the abutment 17 is arranged to effect the working feed of the slide 11 to the left, Fig. 7.