GB473871A - Improvements in material testing machines - Google Patents

Abstract

473,871. Testing physical qualities of materials. SANDBERG, C. P., SANDBERG, O. F. A., and HUMFREY, J. C. W. March 12, 1937, No. 7320. [Class 106 (ii)] Relates to the type of machine in which a load applied to a test piece is also applied to a resilient member, usually a spring beam, and the resulting deflections are employed to produce a graphical record, and consists in arranging the transmission means from the load applying means to the recording device so that no recording movement takes place when the length of the specimen remains constant. An L-shaped piece 1 is adapted to pivot on a base 2. Rigidly fixed to the piece 1 are knife edges 3, 4, the member 1 pivoting about knife edge 3 on a seating 5 and being supported by a ball 6 immediately below. The knife-edge 4 bears on a seating 7 carried by a shackle 8, the opposite shackle 11 being pivotally attached to a screw 12 carried non-rotatably in an upright 13. A nut 15 engages the screw and abuts against the part 13. The nut 15 is formed as a worm wheel and is extended to carry a small drum 16. Fixed to the part 1 is a spring beam 17 and a hollow bar 20. The other end beam 17 is slotted to engage a fixed pin 18. Sliding on the beam 20 is a pen carriage 21 while carried on the beam is a chart plate 19. A cord 22 attached to the carriage passes over a pulley 23 to a spring 24 fixed inside the hollow bar. A cord 29 is passed over a pulley 30 on the bar, around a fixed pulley 30a, across the bar and over a pulley 31 and is attached to the drum 16. The dumbell specimen 40 is carried in half grips 36 as in Figs. 5a, 5c, these being slipped into sockets in the shackles. The arrangement is such that when the handle 35 is turned to stress the specimen, the beam is turned about its pivot and the slack of cord 29 is wound on drum 16, the proportions being such as to do this without movement of the pen carriage. When specimens extends the pen moves proportionally the chart moving according to load. The pen is weighted to be jerked upward when breakage occurs.