GB638560A - Improvements in or relating to high-speed tensile testing machines - Google Patents

Abstract

638,560. Testing physical qualities of materials. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. June 6, 1947, No. 15013. Convention date, July 12, 1940. [Class 106 (ii)] [Also in Group XL (b)] A variable speed impact tensile testing machine comprises a rotatable element, retractable impact means carried by said element, releasable means for holding the impact means retracted, a rigid metallic body having a high elastic modulus and having integrally formed longitudinal shanks, means for rigidly supporting said body adjacent one end of said shanks adjacent the rotatable element, means for securing an assembly, including a test-specimen to be deformed to a relatively high velocity, to said body adjacent the other end of said shanks, and means for indicating the force applied to elongate the test-specimen, said indicating means being responsive to the elongation of said shanks due to impact by said impact means. The specimen 8 is secured to the load-measuring support 9 which has a high natural frequency of vibration and is screwed at its lower end to an anvil 12 which is adapted to be struck by hammers 3, 4 pivoted at their centres of gravity to a flywheel 1 driven by a motor 2. Until the required speed of operation has been attained, the hammmers are held in inoperative positions by a sprung lever 20. On operation of a solenoid 22, however, a pin releases a trigger 15 which rocks the lever 20 and allows the hammers to move, under the action of a spring 16, to an operative position. The load applied is measured by the minute extension of the support 9 to the lower end of which is secured a rod 18 which controls the width of a narrow slot 17 on which is focused a beam of light received by a photo-electric cell P connected through an amplifier 19 to the vertical plates of a cathode-ray oscilloscope 41. The anvil 12, the movement of which corresponds with the strain, intercepts a rectangular parallel beam of light which is focused on to a second photo-electric cell P<SP>1</SP> connected to the horizontal plates of the C.R.O. Thus, as the hammers strike the anvil, a load-strain curve is traced on the screen of the C.R.O. which may be photographed by a camera C. The load- and strain-measuring devices are calibrated by means of dead weights and a shutter respectively. In order to carry out tests at high temperatures, an induction heater 13 mounted on a pivoted frame 51 may be positioned round the specimen, a plug 11, through which flows a cooling liquid, being introduced between the specimen and the load-measuring support 9.