GB627745A - Improvements in or relating to apparatus for examining the hardness of materials - Google Patents

Abstract

627,745. Testing hardness of materials. ERNST, A. Feb. 6, 1947, No. 3567. Convention date, Feb. 6, 1946. [Class 106 (ii)] Hardness-testing apparatus comprises a spring-pressed feeler, which has a small hard point and is slidably fitted in a reference member so that when the reference member is applied to the surface under test the point is caused to penetrate the surface, and an indicator operated hydraulically by relative movement between the feeler and reference member to indicate the depth of penetration which is a measure of the hardness. The indentor 29 of hard metal or diamond is carried by the feeler 20 guided in a sleeve 25 and intermediate plate 16, both screwed into a casing 1, and is loaded by a spring 21. At its upper end, the feeler 20 engages a plate 19 associated with a diaphragm 14 on one side of a liquid chamber to which is connected a circular capillary tube 6 visible through a glass disc 4. A sprung sleeve 33, whose movement is limited by a screw 35 which slides in a slot formed in the sleeve 25, normally protects the indentor 29 and V-shaped slots 37 formed in the sleeve 33 prevent slipping when a curved surface is under test. In use, the casing is pressed towards the test surface until the latter is contacted by the plane end of the sleeve 25, when the depth of penetration is indicated by the liquid level in the tube 6. This level may be adjusted by means of a screw 12 threaded into the side of the liquid chamber.