GB176336A - Improvements in hole and like internal gauges - Google Patents

Abstract

176,336. Krupp Akt.-Ges., F. Feb. 26, 1921, [Convention date]. Surface and outline gauges.-Relates to internal three-point gauges having feeling-bolts movable at an angle to an adjustable member pressed out by intervening balls acting against a conical part of the adjustable member, and consists in providing means whereby wear on the gauge parts may be corrected and play due to wear eliminated. This is attained by making the feeler-carrying member adjustable relatively to the body of the gauge, and by providing V-grooves for the balls. The invention is described applied to a micrometer screw internal gauge fitted with a pointer to indicate when the feeling-bolts are exerting the correct pressure. The hollow cylindrical body A of the gauge is split longitudinally at one end and has at that end a conical screw-thread a<2> fitted with a nut B so that it can be clamped rigidly to a feeler-carrying member A'. At the other end the body portion has an internal micrometer thread a<3> into which a bush C is screwed,. the bush having a graduated thimble D which surrounds the body and registers with a scale a<4> on it, and being rotatable around a second bush G, to the right-hand end of which is screwed the casing H of a dial indicator. Upon the bush G is slidable in the casing A a collar g<1> prevented from rotating by a groove g<2> taking a key a<5> fixed to the casing. The enlarged end k<1> of a central bolt K is held against the bottom of the casing H by a spring P within the bush G, and a spring plunger M connected to the pointer N of the dial indicator bears against this end of the bolt, the other end carrying cone k<3> bearing against three balls Q which in turn bear against the feeling- bolts T. The balls are pressed by the spring P against V-grooves a<6>, Fig. 5, the other side a<8> of the guides being semicylindrical. In use, the feeling bolts are inserted into a hole and the thimble D rotated, causing the bolt K to move forward and force out the feeling-bolts. As soon as contact is made with the sides of the hole further rotation of the thimble causes the casing H to move relatively to the bolt, compressing the spring P and displacing the bolt M and pointer N of the dial indicator; when this indicates zero the proper pressure is being exerted by the feeling-bolts and the reading is taken. Wear that occurs on the faces a' of the V-grooves a<6> does not cause slackness, and error due to this wear may be corrected by setting the thimble to the dimensions of a calibrating ring while the gauge is inserted in the ring, loosening the nut B, and screwing the part A<1> further into the part A until the pointer indicates zero, then tightening the nut B.