GB655572A - Optical gauging apparatus - Google Patents

Abstract

655,572. Optical gauging-apparatus. PRECISION METHODS CO., Inc. Dec. 17, 1947, No. 33309. Convention date, March 23, 1946. [Class 106 (ii)] In an optical device for comparing the surface of an object with a standard surface, the object 6 is mounted on a support 5, a follower 24, mounted for movement over the surface in a plane normal thereto, is carried by a member having an index which is given a corresponding movement at a distance from the surface, and a magnified image of the index is projected by a light beam on to a screen 48 having a comparison line representing at the same magnification the profile of the desired surface. As shown, the device is mounted on a movable table 1, Fig. 1, the support 5 being movable across the table on bearings 3 to bring different portions of the surface 7, e.g. of a turbine vane, under the follower 24 which comprises a roller on an arm 23 fixed to a sleeve 22 vertically movable on a horizontally-movable hollow post 19. The post is secured to a rail 11, Fig. 5, mounted by ball-bearings 13 for movement along a horizontal channel 9 having adjustable sides to compensate for wear. The sleeve is similarly mounted on the post and is partially counterbalanced by a weight 40 attached to it by a cord passing over a pulley 38. The arm 23 has two index apertures 41, 42 of which the magnified images 51, 52 are projected by an optical system (Fig. 3, not shown) on to the translucent screen 48, Fig. 2. Each image is associated with a part of the standard profile represented by a pair of lines 49 or 50. If the lower edge of the image lies between the lines throughout its movement across the screen the surface lies within the desired dimension limits. Different index apertures may be used also for different transverse sections of the surface. The follower may be a pointed member and the index of corresponding form. Specifications 586,071 and 616,970 are referred to.