GB393892A - Improvements in devices for examining the diameter of bores - Google Patents

Abstract

393,892. Linear-dimension gauges. ZEISS, C., [Firm of], Carl-Zeiss-Strasse, Jena, Germany. Jan. 16, 1933, No. 1373. Convention date, Jan. 21, 1932. [Class 106 (ii).] Apparatus for examining the diameter of a bore comprises a telescope having an illuminated mark in its image plane and a reflector holder consisting of two parts which are elastic so as to be inclined relatively to each other, each part carrying a plane reflector. An autocollimation telescope 14, the bore 1 to be examined, and a scale 3 are given a known position in which the axes of the telescope and bore and the edge of the scale approximately coincide. The reflector carrier placed in the bore comprises parts 5, 6 elastically connected by a piece 4, the part 5 having supporting feet 7 while the part 6 has a supporting foot 8. A spring 13 presses the parts out against the bore and a rod 10 extends so that the position of the holder longitudinally of the bore may be read on the scale 3. The part 7 has a polished surface 9 square to the line of the feet 7 and the part 6 a polished surface 12 inclined to the surface 9 at an angle slightly less than 180‹. The telescope contains an objective 15 and an occular 16 in the common focal plane of which is a field of view diaphragm 17. Light from a source 23 is reflected by a prism 20 the light exit surface 21 of the prism being in the plane of the diaphragm and being provided with a scale and index. The light from the illuminated scale and index after passing through the objective 15 emerges as parallel rays which are reflected from the surfaces 9, 12 back through the objective on to the diaphragm on which is projected two images displaced from one another the more, the less the angle between the surfaces 9, 12. The arrangement is such that with a normal bore the images 251, 2411 lie outside the field of view and the image 25<11> appears in the middle of the scale image 241. As the holder moves along the bore deviations are noted by relative movement of images 25<11>, 241. A group of concentric circles may be provided instead of the scale and index and the number of rings which cover each other in the image provide a measure of the diameter of the bore.