GB1215540A - Apparatus for measuring the thickness of dielectric members - Google Patents

Abstract

1,215,540. Measuring thickness. OWENSILLINOIS Inc. April 19, 1968, No. 18605/68. Heading G1N. A sensing head for measuring the thickness of glass comprises a cylindrical electrode 46 energized from a high frequency generator (60) and a rod-shaped pick-up electrode (49) disposed centrally of the cylindrical electrode. The electrodes are mounted as shown with plastics insulation 47, 48 within an aluminium block 35 supported on rails 39 and urged towards the glass by a spring 55. A wheel 43 contacts the glass to ensure an accurate spacing between the electrodes and the glass. The sensing head may be used to measure the wall thickness of glass bottles or the thickness of glass sheets. For testing a succession of glass bottles, brought one at a time to a testing station, a plurality of sensing heads may be spaced vertically with their electrode axes horizontal so that as a bottle is rotated about a vertical axis its entire circumference is scanned by the electrodes, which in practice would be positioned where experience shows thin wall sections are most likely to appear. To overcome inertia, the bottles may be given some initial rotational movement by frictional contact with a rail (21), Fig. 1 (not shown), prior to arriving at the testing station. The voltage picked up by the pickup electrode is compared with a reference voltage obtained from the generator (60) and if the bottle is too thin a rejection mechanism is operated.