GB700923A - Improvements in or relating to gauging devices for checking dimensions and investigating the contour or profile of surfaces - Google Patents

Abstract

700,923. Linear-dimension and surface and outline gauges. WILLS, S. A., GATHERCOLE, E. F. J., and TOLIMIT GAUGES, Ltd. March 14, 1952 [March 16, 1951], No. 6403/51. Class 106 (2) A gauge for checking dimensions or for gauging the contour or profile of a surface comprises a reference member and a rotatable gauging member provided with a rib formed and arranged to make substantially only a single point or area of contact with the surface of an article under investigation so that, as the rotatable gauging member is rotated, the point or area of contact between the rib and the surface of an article under investigation sweeps across the surface. the distance between the reference member and the rotatable gauging member being either fixed and predetermined or variable and means being provided for determining changes in this distance. A gauge, Fig. 1, suitable for gauging an article 10, comprises a roller 11 mounted on a base 12 on which is mounted an adjustable stop 13 to determine the position of the article 10 on the roller 11. Mounted on a pivot 14 on the base 12 is a frame 15 which carries the rotatable gauging member 16 fixed to a pivot 17. The member 16, Fig. 3, is in the form of a drum built up of plates 18 clamped together, each plate having a radially projecting lug with a machined surface 19, the lugs being angularly displaced but slightly overlapping. The pivot 17 of the member 16 carries a knob having marks for indicating which surface 19 is engaging the article 10. Variations in diameter of the article 10 cause movement of the frame 15 about the pivot 14 which is indicated on a dial gauge 22 whose pin bears on the top surface 21 of the frame 15. In a modification the member 16 may be formed in one piece with a continuous helical rib. The reference member 11 may be similar to the member 16 and these two members 11 and 16 may be rotated step by step conveniently being interconnected by gearing. The gauge may be used for gauging the contour of irregularly shaped parts such as turbine blades by adapting the reference member 11 to support the blade with the surface to be gauged exposed. The rotatable member 16 lies above the blade with its axis parallel with the length of the blade. By periodically turning the reference member 11 through small angles and rotating the member 16 so that the rib sweeps the whole length of the blade in each angular position, a complete set of readings can be compiled for comparison with a master set. A similar gauge can be used for gauging flat surfaces. For gauging curved surfaces the rib could, if preferred, be given a predetermined contour conforming to the required curvature so that for an article of correct shape there would be no relative movement between the members 11, 16 but any inaccuracies would be indicated. In a modified gauge for screw threads, Fig. 4, the screw will be mounted on the reference member 11 and may be capable of relative rotation thereto while the rotatable gauging member comprises a shaft 24 having at one end a disc 25 with a spiral rib 26 formed thereon arranged to sweep the flank of the thread from the point 28 to the point 29. In a modification, Fig. 6, the axis of the rotatable member 16 is parallel to the axis of the screw and the disc at the end of the shaft is conical with a spiral rib thereon relieved at intervals by notches 33 to eliminate interference due to the helix angle of the thread.