GB865056A - Improvements in or relating to apparatus for gauging linear dimensions - Google Patents

Abstract

865,056. Electrical measuring systems. POWER JETS (RESEARCH & DEVELOPMENT) Ltd. Feb. 20, 1958 [Feb. 20, 1957], No. 5785/57. Class 40 (1). [Also in Group XIX] A linear-dimension gauging apparatus includes a structure (not shown) capable of supporting a rigid rotatable workpiece 1 having a plurality of discrete sets of serrations 24, measuring equipment (Fig. 3) to measure the distance between a datum flank 22A of one set of serrations and each remaining flank of that set and indexing mechanism (Fig. 5) to rotate the workpiece 1 from one measuring position to a position for measuring another set by the same measuring equipment. In checking the pressure flanks of the serrations 22-25 of a turbine disc 1, the gauging apparatus is mounted on a turret 9. An electric or pneumatic gauge 29 is mounted on the base 41 of the apparatus by spring strips 32, 33 and carries a " datum " stylus 26. The gauge 29 may be of a type depending on variable inductance. A second stylus 27, attached to the turret 9 by spring strips 45, 46 acts, through a contact 59, on the movable anvil 60 of the gauge 29. The stylus 27 may be adjusted longitudinally by a pin-and-slot 51, 52 and an adjustable bolt 49 which pulls two further spring strips 47, 48 together. A separate stylus 27 for each serration 23, 24, 25 is mounted on each flank of the turret 9, and the turbine disc is mounted so that each pressure flank is vertical when being gauged. A setting fixture (not shown) is provided which simulates standard serrations and allows the apparatus to be adjusted before measurement. In use, with the apparatus in the position shown in Fig. 3, a reading is taken and the turret 9 rotated automatically to bring the next stylus 27 into place, a reduction in the speed of rotation being effected as the stylus moves over the pressure flank. After each flank of one set of serrations has been gauged, the disc 1 makes a small anti-clockwise movement to disengage the datum stylus 26, which is pulled clear by a cord 81. The disc 1 is then rotated clockwise and the cord 81 released to allow the stylus 26 to lie above the next set of serrations. The disc 1 then rotates further under the influence of a spring, thus engaging the stylus 26 with the serration 22 and a further gauging operation takes place. After one set of flanks has been gauged, the disc 1 is reversed so that the opposite flanks may also be gauged. The apparatus may also be used for gauging a large number of blade roots by arranging a series of blades on a rotatable fixture. The indexing mechanism is shown in Fig. 5 and consists of an indexing arm 93 operated through a cam and follower arrangement by a motor 21 to position a disc 17 to which the turbine disc is secured. A second arm 104 serves to lock the disc 17 in its adjusted position and is also controlled by the motor 21.