GB1115106A - Measurement of internal hardness of materials - Google Patents

Abstract

1,115,106. Measuring hardness. BRITISH CAST IRON RESEARCH ASSOCIATION. March 15, 1967 [March 17, 1966], No. 11655/66. Heading G1S. A gauge for testing the internal hardness or strength of a solid material comprises a probe 39 screwed on to an impact rod 24 which extends through a barrel 11 and is movable against a compression spring 27 situated between a seat 26 and collar 28, and further comprises compression springs 17, 21 situated between a hammer 18 and rotatable seating member 14, 14a. The end 24a of the impact rod 24 abuts the surface 36 of a plug 30 having an aperture which is axially offset with respect to the rod 24. A leaf spring 33 prevents rotation of the plug 33 and presses the nose 35 of the plug 33 against a cam surface 34, 37 on the inside of the barrell 11. In use, the gauge is pressed against the material to be tested, compressing the spring 27 to withdraw the barrel 11 and hammer 18 into the barrel until the nose 35 is forced inwardly by cam surface 37 to align bore 31 with the rod 24, whereupon the hammer 18 is free to move under the influence of spring 17 and deliver a blow of predetermined impact to the rod 24. The strength of the blow may be varied by rotating cap 12 to alter the compression strength of spring 17.