GB376726A - Improvements to machines for testing metals by shock - Google Patents

Abstract

376,726. Testing physical qualities of materials. PLANA, A., 2, Fabrica de Altos Hornos y Henao, Bilbao, Spain. Jan. 10, 1931, No. 941. Convention date, Jan. 21, 1930. Void [Published under Sect. 91 of the Acts]. [Class 106 (ii).] In a machine of the pendulum type for testing metals by shock, the pendulum is raised by lever operated pawls engaging toothed wheels on the shaft of the pendulum. The pendulum comprises a frame 1 and hammer 2 fixed to a shaft 3 mounted in bearings on uprights 6 rising from a bed 5. Bearings 7 are provided for the test piece. A dial 8 graduated on both sides of a zero is connected to one upright. Two pointers 9, 10 are provided of which the latter may be clamped to the shaft 3 while the pointer 9 is held frictionally. Two toothed wheels 12 fixed on the shaft 3 are engaged by pawls 13 pivoting on a shaft 14 carried by rods 20<1> pivotally mounted on the shaft 3 and pivotally connected to links 28 pivoted to discs 27 driven by worm and belt gear from an electric motor. For a single fall, the lever 15 is rocked by hand and through links 17 rocks a releaser engaging under the levers 20 which turn on the axis 14 and disengage the pawls. For repeated blows, the motor is used, and as the discs 27 turn the rods 28 lift the levers 20, 20<1> the pawls sliding over the teeth. Upon reversal, the pawls engage the wheels 12 and lift the pendulum. On downward movement of rods 28, the levers 20 contact with screws. 30 and the pendulum is released. The eccentricity of the axis 29 can be varied by moving the slides 33 by means of their adjusting screws 34. The screws 30 may be screwed more or less into the nut 31 to alter the time of fall. The position of the axis 14<1> may be varied by turning the screw 35. In use, the pendulum is raised to a given angle, and released by hand the angle reached on the right-hand of the dial after the specimen is broken being read, and the energy expended being calculated from tables according to the various adjustments made. To test the limit of elasticity, the bar is placed and centred in the bearings 7 and rods 6, Fig. 5, screwed in until they connect with the ends of the bar. The rests are able to turn about their axes 8. A mirror 9 is clamped to the bar and inclined so that as division on a scale 37 is seen in the telescope 36. The fall of the pendulum is progressively increased and the division coinciding with the mirror read before and after the fall until a permanent deformation is obtained. For fatigue upon bending, repeated blows are given the number being registered on a counter 43. To test tensile strength by shock, the test bar is cylindrical and one end is secured to a crosshead 2, Fig. 6, and the other to the hammer of the pendulum. In the place where the specimen is usually secured, two anvils 4 are secured by bolts 5. On the fall of the pendulum, the crosshead is arrested by the anvil at the plumb line of the pendulum and the specimen is under tension. Rods 9, 10 connected to each end of the specimen are connected by a crosspiece 12 to which a mirror is secured. Means are provided to prevent damage to the mirror in breakage of the specimen. For fatigue tests, the specimen is placed under repeated blows and is secured at the ends so that even with deformation, the crosshead hits the anvils squarely and when the pendulum is at the plumb line. For testing by inverted flexure, the specimen is so held that it may be automatically rotated through 180‹ about its axis between the blows.