GB970714A - Improvements in measuring and gauging devices - Google Patents

Abstract

970,714. Measuring length electrically, linear dimension gauges. WATTON ENGINEERING CO. Ltd. Jan. 24, 1961, No. 2757/61. Addition to 887,565. Headings G1M and G1N. A feeler gauge for measuring linear dimensions comprises a cross spring mounting for the tip of the feeler which is attached to a metallic member altering the coupling between the balanced secondary windings of a transformer, enabling the deflections of the feeler tip to be measured. As shown (Fig. 1), the feeler mounting comprises a body 5, housing a transducer coil assembly 8, and carrying a detachable, ball-pointed feeler probe 19 attached via a cross spring mounting to a non-magnetic lever 13, varying the coupling between the windings of coil 8. The lever 13 has a forked extension 15, embracing a longitudinal member 26 which has an H-shaped cross-section at the ends, joined by a blade portion which is a continuation of the cross member of the H section. The ends of the fork 15, and the end of the member 26 are cemented together and to the bore of the tip 16 of the feeler body 5, forming one part of the cross spring mounting, the other part being provided by slots 22 in the body 5, a transverse aperture 24 (Fig. 2) and parallel slots 25, leaving blade portions 23. The coil assembly 8 consists of an A. C.-energized primary winding 31 (Fig. 3) and opposed secondary windings 32, 33, normally balanced. Movement of the lever 13 produces an output signal from the secondary windings whose magnitude and phase sense indicate the magnitude and direction of the movement of probe 19, and is shown on meter 39. Quadrature components of the signal voltage are eliminated by potentiometer 40, the zero of meter 39 is adjusted by calibrated potentiometer 41 or uncalibrated capacitor 43, and the sensitivity of the unit is controlled by potentiometer 36. The gauge may be used to determine the difference in height between a gauge 59 (Fig. 4) and a workpiece 50, the difference being indicated on meter 39, or by determining the readjustment required on a micrometer screw 55 bearing on a slotted support 51 for the feeler body 5 to bring the reading on meter 39 back to zero. Specifications 887,564 and 970 713 also are referred to.