GB571850A - Improvements in and relating to a machine for testing hardness of materials - Google Patents

Abstract

571,850. Testing physical qualities. HEIDE, H. C. (Gillette Safety Razor Co.). Aug. 26, 1943, No. 13959. [Class 106 (ii)] A hardness-testing machine, particularly for use in testing abrasive wheels, ceramic products, artificial stone, cement and the like, comprises a rotary drill or testing tool for penetrating into the workpiece, a weight mounted on the tool spindle preferably so as to rotate relatively to the spindle, and a gauge or indicating means responsive to the axial movement of the spindle. The drive to the spindle may be made through a flexible coupling, and provision is made for imparting a predetermined number of revolutions to the tool. The machine shown in Fig. 1 comprises a standard 10 with an overhanging head casting 11 and removable cover 12. The standard 10 has guideways 13 upon which slides a work table 14 operated by a hand wheel 21. The head casting 11 encloses a self-contained spindle unit with upper and lower flanged bushings 30, 31 in which is journalled a tool-carrying spindle 25. The spindle is shouldered to receive a sleeve 26 that is secured to the spindle and carries ball-bearings for a cylindrical weight 29. The spindle is mounted for limited vertical movement and at its upper end has a flexible coupling with a hollow driving shaft 38 by means of pins 35 on a dish 34 engaging pianowire arms 36 extending from a collar 37 on the shaft 38, see Figs. 1 and 3. The shaft 38 is surrounded by a bushing 39 journalled in a bracket 40 secured to the head casting 11. A rod 41 extends through, the shaft 38 and rests at its lower end on the spindle 25 and engages at its upper end the plunger 42 of an indicator or gauge 43. A guard plate 45 (not shown) is provided to hold the plunger out of contact with the rod 41 when not in use ; a setting handle 48 is also provided for adjusting the pointer to zero or other initial setting. An electric motor 50 with an automatic stop mechanism 55 and gearing 56, 57 and 58 is arranged to drive the hollow shaft 38, the supply of energy to the motor being cut off after a predetermined number of revolutions have been made. A friction brake 59 is provided about the hub of the gear 57 to prevent overthrow of the driving gear train. Instead of measuring the depth of penetration resulting from a predetermined number of revolutions the number of revolutions required to penetrate the work to a predetermined depth may be the basis of measurement.