GB216680A - An improved apparatus for effecting a test of the hardness of materials - Google Patents

Abstract

216,680. Benton Scale Co., Ltd., and Benton, W. A. May 12, 1923. Testing hardness of materials.-The specimen is arranged to take the greater part of the weight and to provide a pivotal support for a suspended pendulous mass adapted to oscillate under torsional moments set up in its suspension, an observation of the angle of decrement of the oscillations of the mass or of the period of time taken to reach a given decrement affording a measure of the hardness. The frame of the apparatus comprises a vertical member 4, a base member 5, and a bridging member 7 disposed in a plane at right angles to the plane of the member 4. The pendulous mass 9 provided with a hardened point 10 is suspended by an elastic wire or strip 14 from the lower end of a slotted link 13 guided in the bridge piece 4f, the link being suspended by a spring 12 from a screwed stem 11 adjustably mounted in the upper end of the frame member 4. Passing through the link 13 is a pivoted lever 18, - the free end of which bears a hardened strip engaged by the point of a screw 20 operated by a hand wheel. Mounted on the lower end of the bush 29 in the cross piece 4e is an annular collar 30, from which project diametrically two aligned arms 30<a>, one of which is provided with a. handle 32, while each arm at points equidistant from the axis of the machine carries projections 33 with adjustable contact screws 33<a>. These are adapted to engage simultaneously two stops 28 on. a diametrically arranged strip 27 attached to the mass 9. The mass 9 is provided with a graduated drum 25, which moves relatively to a fixed index 26, and with two adjustable masses 23 to vary its moment of inertia. The lower section. of the mass 9 is provided with a hole 34 axially aligned with the axis of rotation of the mass. A needle carried by a slotted pin 35 carried in turn upon a pivoted lever 36 is adapted to engage the hole 34 to centralize the mass. In use, the specimen is placed on the table 8, and the latter and the lever 18 adjusted so that the point 10 does not quite contact with the specimen while the spring 12 is given a predetermined slight tension. The handle 32 is moved and the mass 9 moved through a predetermined angle defined by a stop, not shown, on the member 4. The lever 18 is then towered until quite free from the end of the slot in the link 13 and the weight of the mass is taken by the specimen with the exception of the small predetermined amount taken by the spring 12 which may be adjusted by the nut 15 to secure an exact amount. The finger 38 is now pressed down against the spring 41 and the needle lowered out of the hole 34 in the mass, the handle 32 being moved back to its original position allowing the mass to oscillate. A stop-watch may be embodied in the apparatus adapted to start on the commencement of the oscillation of the mass 9.