GB708171A - Improvements in or relating to the determination of the hardness of materials - Google Patents

Abstract

708,171. Testing hardness of materials. TSCHIRF, L., and MITSCHIE, R. March 10, 1950 [March 10, 1949], No. 6029/50. Class 106 (2) A method of determining the hardness of a material consists in employing a hardnesstesting apparatus in which a penetrating body is pre-loaded and, after contact with the test piece is given a main load and which, during the application of said main load (or during its continuance after application) is subjected to controlled vibrations to an extent where further vibrations do not affect the indicated hardness value the hardness value being read after removal of the main load and before removal of the pre-set load. The indentor a, Fig. 1, is housed in a bore of a pressure die b in which a spiral spring c exerts a force of 10 kg. (" minor " load). The " major " load is produced by 'a set of springs F fitted in a bush d in a casing k and is transmitted via a spring dish T, a ball-bearing f, and a collar b<SP>1</SP> to the die b. The tops of the springs F abut a die b. The tops of the springs F abut a screwed plate P by which their tension may be adjusted. The dish T has a ramp which cooperates with a ramp on a ring h which can be rotated by oscillation of a lever H to allow application of the " major " load to the test piece. The depth of penetration is indicated by a dial indicator n. An indentor protecting cap g is pressed outwards by a spring j in a ring i. Surrounding the casing k is a ring q, Fig. 4, which is rotated during the test to compress a spring t the subsequent expansion of which causes a pair of pawls N carried by a lever B to ride over the teeth of a fixed ratchet s so that a pair of clappers r strike the casing k and produce vibrations of the appliance and test piece.