GB673760A

GB673760A -

Info

Publication number: GB673760A
Authority: GB

Abstract

673,760. Electric indicating system. BRITISH IRON & STEEL RESEARCH ASSOCIATION. Oct. 6, 1950. [July 12, 1949] No. 1.8383/49. Class 40 (i). [Also in Groups XIX and XL (b)] The profile or contour of a surface is determined by means of a carriage movable along a reference axis and a feeler movably mounted on the carriage so as to be pivoted in a plane by the contour, this pivoted movement being detected and the feeler restored to its angular position with respect to the axis either manually or automatically. As described, the apparatus is applied to measuring the internal diameter of a wire drawing die mounted in a chuck (not shown). The feeler 4a is mounted on the carriage 9 which is advanced along parallel rods by a micrometer 10, the carriage being held against the micrometer tam 11 by a spring 12. The feeler may be raised vertically by a further micrometer 19 which lifts a rod 13 on the end of a bell crank lever 18. The rod slides on four polished balls against which it is held by a leaf spring 16. The rod may be rotated about its own axis for adjustment purposes. The feeler itself is mounted in a head 32 so as to be capable of pivoting in the vertical plane. The feeler end is slightly heavy and rests against the bottom of the profile under examination, or alternatively a counter weight 30 will make it rest against the top of the profile. Light from a source at the end of a container 55 is reflected from a mirror 6 mounted at the rear of the feeler and is split to two photo-cells by a stainless steel prism 34. These photo-cells are incorporated in an A.C. bridge circuit, unbalance of which in one direction or the other is used to control a phase sensitive servo-motor 36 which through gearing 25, 26 raises rod 13 to rebalance the circuit. Initially the feeler rests on a. part of the profile. The carriage is then advanced by a motor driving through a micrometer 10. If the profile is other than parallel to the axis the photo-cell will be unbalanced and servo-motor 36 will run to rebalance the illumination on each cell and at the same time to move through gearing a marker parallel to the axis of a drum. The drum is rotated by the same motor which advances the carriage.