Patent GB-353549-A (GB)
Title: Apparatus for measuring the hardness of materials
IPC: G01N3/42
Filed: 1930-05-05
Abstract: 353,549. Testing hardness of materials. SHORE, A. F., 50, West 86th Street, New York, U.S.A. May 5, 1930, No. 13797. [Class 106 (ii).] Comprises in combination, a specimen support, pressure applying means for an indentor, means for indicating the depth of penetration, means for compensating for contraction of the penetrator under load, and a gauge operative from the pressure-applying means to indicate the pressure to effect the indicated depth. The movement of a handwheel 4 is conveyed through gearing 5, 7 to a rack 9 sliding in the overhanging arm of a frame 2. The rack 9 supports a casing 11 in a boss 121 of which slides a specimen clamping and depth measuring sleeve 13 in which is a pressure bar 14. The sleeve 13 is guided vertically in the slide bar 9 an adjustable stop 16 being provided at the lower end of the bar 9. The pressure bar 14 slides without turning in the casing 11 and encloses an auxiliary pressure bar 21 adapted to contact at the upper end with a leaf spring 22 which is supported on end springs and which bears against hardened rollers 23, 23<1> carried in the casing 11. Blocks with knife-edges may be substituted for the rollers. The effective length of the leaf spring may be altered by adding or taking away shim pieces 26 from between roller carrying blocks and the casing. A small rack bar 28 actuates a pointer 32 and is kept in contact with the spring 22 by a gear including a hair spring. The rack bar 28 is hollow and has a stem 34 threaded therein adapted to be moved to adjust the zero of the scale by a detachable key 35. Inside the bore of the pressure bar 14 is inserted an anvil plug 47 on which rests a compensator pin 55 on which in turn rests the auxiliary pressure rod 21. The casing 36 of the depth gauge is carried by a pivoted member 41 pressed by an adjustable spring 43 so that a knife-edge on the end 42 engages the end of the pin 55 and follows its movements. The pin 55 is of reduced diameter so that when the rod 21 is under stress the pin shortens to the same extent as the penetrator 45 and tilts the lever 41 upwardly correspondingly. The feeler of the gauge 36 rests against a spring. pressed stem 51 carried by the sleeve 13 so the gauge reading is compensated for contraction of the penetrator. A zero adjustment is provided by a conical pin 52. Slots are made in the sleeve 13 to permit assembly of the parts and to allow actuation. The impression point 45 is carried on a stem secured in a socket in the bar 14. A perforated cap member 18 is secured to the sleeve 13 by a ring nut in any angular position. The base 75 is secured in a socket 77. Figs. 13 and 17 show an alternative construction of compensated pressure bar. Instead of using the lever 41 and pin 55, a small disc or diaphragm spring 84 is used adapted to bear on a circular knife-edge 85 at the bottom of the base in the bar 14. Resting on the disc 84 also by a circular knife-edge 87 is a tubular member 86 which carries the gauge 86<11>. Inside the member 86 is the auxiliary pressure bar 92 mounted at the top to engage the leaf spring 22<1> and contacting at the bottom with the centre of the disc 84. As pressure comes on the disc the outer ends turn up and lift the tube 86 and gauge 86<11>. The upper end of the tube 86 is slotted to form a spring. In use the slide bar 9 and gauge casing 11 with sleeve and pressure bars are moved down. The cap 18 contacts with and clamps the specimen 45<11> under pressure of a spring 17. As the movement continues, the gauge 36 will have an indication until the impression point 45 engages the specimen. The zero of scale 36 is now adjusted. The load and the depth of the impression are then simultaneously indicated. For standard hardness, the depth of penetration is kept constant. In some cases, the load is kept constant.