GB634215A - Improvements in or relating to material testing machines - Google Patents

Abstract

634,215. Testing physical qualities of material WESTINGHOUSE ELECTRIC INTERNATIONAL CO. April 30, 1947, No. 11531. Convention date, May 27, 1944. [Class 106 (ii)] [Also in Group XXXVIII] The deformation of a test specimen 34 (Figs. 1 and 3) under load is measured by the relative movement of two parallel comparison rods 55, 57 connecting spaced points of the specimen to comparison plates 59, 60 respectively, the plates being connected by flat springs 85, 86 which allow only relative axial movement of the rods during testing. In the machine shown in Fig. 1, the specimen 34 is screwed into upper and lower grips 35, 36 which are screwed into a loading bar 29 and anchor bar 37 respectively. The bar 29 is supported by a knife-edge 27 on one end of a pivoted lever 21 having weights suspended from its other end. The bar 37 passes between cross-channel irons 14 of the supporting framework into a seat 38, and is prevented from falling when the specimen breaks by a collar 40a. The specimen may be heated in a cylindrical electric furnace 41 slidably mounted on a square rod 45. Strain-measuring ; extensometers. Upper and lower pairs of rods 55, 57 (Fig. 3) are connected to the specimen 34 by plates 67, 72 fixed by pins 69, 74. The lower comparison plate 60 is connected by a stiff wire 83 to the grip 36 to prevent swinging. An electric contact on the plate 59 normally engages a contact on a micrometer 62 on plate 60. Relative movement of the plates due to extension of the specimen, breaks the contacts which are reengaged by an electric follow-up device (see Group XXXVIII) including a motor 50 which moves up the micrometer through reduction gears, the number of revolutions of the motor being registered on a counter 52. A normally open shut-off switch (not shown) is closed by the weighted end of the lever 21 (Fig. 1) if the specimen breaks, so as to prevent any further operation of the motor. In a modification (Fig. 11), the relative movement between plates 59, 60 is magnified by a frictionless leverage device. The plate 59 carries a block 136 which extends through a hob in a plate 125 mounted on and spaced from the plate 60 (not shown). A block 132 fixed to the plate 125 is connected to the block 136 by a leaf-spring 138 bolted at its centre to a leverage block 133 fixed to a magnifying arm 124 providing the upper electric contact at its other end. The blocks 132, 136 are also connected to the block 133 by pairs of leaf-springs 131, 135. A handoperated micrometer may be substituted for the motor 50 and counter 52; and a signal device, e.g. a lamp, may indicate when the contacts are separated. A modified means for securing the comparison rods to the specimen, comprises a pair of blocks 116, 117 (Fig. 10), bolted around the specimen, from which the plate 67 or 72 (Fig. 3) is suspended by rods 114, 115. U.S.A. Specification 2,077,598 is referred to. '