GB665582A - Improvements relating to the production of precision screws - Google Patents

Abstract

665,582. Lathes. CRAVEN BROS. (MANCHESTER), Ltd., and OWEN, W. Nov. 1, 1950 [Nov. 12, 1949], No. 29043/49. Class 83 (iii). [Also in Group XIX] A machine for cutting and measuring precision screws comprises a headstock a and a tailstock b, a slide i carrying a clasp nut h engaging a main guide-screw e journalled in the machine-bed, a main-spindle c geared to the screw e, means f, g for ensuring accurate rotation of the spindle, a tool-slide k, and a corrector bar r having a face contour adjustable to correct for inaccuracies in the main guide screw by imparting longitudinal movement to the tool-slide. The slide i carries the toolslide k which is moved against a spring k<SP>1</SP> during cutting by face-cams o, p. The cam p is attached to a lever g carrying a follower which bears against the corrector bar r. The tool is adjusted to-and-from the work by a precision screw n, as also is a feeler y co-operating with dial gauges x. Initially, the contour of the corrector bar is set by checking the accuracy of the guide-screw e by an optical square f and an autocollimator g used in conjunction with a microscope u on the slide k and a line standard on the machine bed. The screw z is then cut, the corrections due to the bar r modifying the movement of the slide k due to the screw e. With the lever q then disengaged from the bar r and the nut h from the screw e, the work is checked by means of the gauges x and the feeler y. If necessary, the bar r is then re-adjusted and a final cut taken.