GB509168A - Improvements in hardness testing machines - Google Patents

Abstract

509,168. Testing hardness of materials. SMITH, R. L. H. March 14, 1938, Nos. 7926 and 20053. [Class 106 (ii)] The machine accommodates at least two specimens simultaneously but independently, and has one set of indenting mechanism, one set of observing mechanism and a duplicate set of at least a part of one of these mechanism so that an indented specimen may be observed while the other is being indented.' Two anvils 2, 3 are mounted in a substantial base 1 and are screwed to engage nuts 5 by which they are raised and lowered. A gear 7 turned by a hand wheel 6 has gearing with it a pinion 9 which may be swung by a handle 8 to engage either of the gear-wheels 5. The indenting and observing mechanisms are mounted on a swinging arm or carriage 10 journalled at a collar 11 on the base 1 and guided between stops at the other end on a flange 12 of the base. The arm 10 has indenting mechanism on its centre line comprising a lever 13 pivoted at 14 with a balance weight 15 at the short arm and a rod 16 at the end of the long arm to receive weights, this rod passing through the collar 11 with ample clearance. The indentor is shown conventionally as a detached point 17 and is mounted in the usual manner and comprises a diamond cut to the standard square pyramid shape. The lever 13 has an elbow adapted to be supported on a sliding plunger 18 resting on a spiral cam 19 which when turned clockwise gradually withdraws the support and allows the indentor to make an impression and after a time is reversed to take the load off the indentor smoothly. The arm carries two identical microscopes 20, 21, of which one 21 is described. Although the impression may be viewed through an eyepiece 22 it is preferred to throw an image of the impression on to a screen. Opposite facets of the impression are illuminated by two sources of light 27 and the image reflected by a prism 24 through a lens 25 on to a mirror 26 and hence to screen 23. The arm 10 is swung laterally so that an impression is made while the immediately preceding impression is viewed and measured.