GB170627A - Improvements in and relating to the apparatus and methods for testing and comparing the hardness of materials - Google Patents

Abstract

170,627. Turner, E. A. June 25, 1920. Testing hardness of materials.-The hardness of materials, for instance lead pencil, is compared by maintaining one or more of a range of abrading materials, of measurable length, for instance, emery cloth, on an axially moving and rotating drum, helical markings being traced on the abrading-material by deposit of the test materials, while both test and abrading 'materials are weighed before and after the test, and the length of abrading-material required to effect the attrition of the test piece may be measured. A balance arm a mounted by knife-edges on an agate block a<3> mounted on a column b is provided at one end with a scale pan a<1> and at the other with a split screw grip holder c for the specimen. Immediately above the. holder c is a drum or carriage e, which itself constitutes the abrading surface or over which the abrading surface passes. Mounted on a cross-piece on a standard b<4> is a micrometer screw d with a graduated wheel d<2> co-operating with a scale d'. The screw d forms an adjustable stop which limits the movement of the beam and consequently the amount abraded from the specimen. In use, the specimen is placed in the holder and the beam balanced. The drum e is brought so near to the surface of the specimen as just not to touch it. A known weight is added to the scale pan to constitute a pressure force, and the drum e rotated until the lever engages the screw stop, which has been previously set. The drum e is fast on a screwed spindle so that the drum may be moved axially to bring constantly a fresh abrading-surface to bear on the specimen.