GB190718241A - Improvements in and relating to Testing Machines - Google Patents

Abstract

18,241. Cillard, A. D. Aug. 12. Testing strength and elasticity of materials and the like dynamometers.-Testing-machines, in addition to having means for testing by compression, tension, bending, and percussion, are provided with means for testing tissues, caoutchouc, paper, leather, belts or straps, metal sheets, wires, threads, and the like, and also for determining durability, coefficient of friction, and viscosity of specimens. The bed of the machine carries the dynamometer head, which is detachable for calibration and has an eye h for suspending it ; the spring a is threaded on the rod carrying one of the testing clamps which has an arm b on the rod for operating the pointer through a rack and pinion, the other clamp being attached to the screwed rod n with bevel and worm gearing for quick or slow travel. The bed also carries a vertically-sliding block, bearing in which is the wheel d, the edge 8 of which is adapted for testing wear and which has an adjustable crank-pin, as shown, for facilitating repeated bending, tension, percussion, or like tests ; the wheel is provided with worm and change-speed drive as shown. For repeated bending, the roller grip 13, 14, Fig. 7, is employed in the reciprocating block driven from the wheel d, and pivoted clamps are employed to prevent breakage at the end of the specimen. For testing wear, durability, friction, &c., the specimen 9, Fig. 5, under tension is pressed by means of the plunger and counterweighted lever as shown. The same apparatus is employed with a point or blade to test by perforating or shearing a tissue, fabric, or metal or gutta-percha sheet, which may be supported or not by the wheel d. For paper, leather, and like fabrics, the plunger is fitted with a rod having a small spherical tip of 3 to 5 mm. diameter, as shown in Fig. 10, and the fabric is tensioned. For testing viscosity and plasticity of substances such as wax, caoutchouc, and the like, the ordinary apparatus of reversion is employed with a steel plunger D, Fig. 11, working in the steel cylinder C, in which a perforated plug E is screwed. For testing at different temperatures, the ordinary clamps are replaced by bent jaws which enter a receptacle containing a heated or cooled liquid. For testing wires and cords, pulleys on which they are wound are mounted in the clamps ; collars, keys, or wedges may also be employed. A stress-strain diagram of the test is obtained, as shown in Fig. 9, by driving a drum carrying a recording-sheet by a cord attached to one end of the test piece and led over a pulley at the other end, the tracing-point being moved by a lever from the dynamometer spring. A series of interchangeable springs a gives a wide range of sensibility.