| 摘要 |
1,121,310. Measuring internal friction electrically. DUNLOP CO. Ltd. Dec. 1, 1965 [Dec. 10, 1964], No. 50244/64. Heading G1N An annular specimen 24, Fig. 1 of a material of which the internal friction is to be measured, is attached to a plate 23 fixed to a shaft 21 which is constrained to rotate against the resisting torque of a coil spring 40, by a plurality of balls 15 sandwiched between the specimen and a further annular member 14, which is rotated at a constant speed by an electric motor. The angular displacement of the plate 23 is measured by a fixed pointer 39 and a graduated disc 38 attached to the shaft 21; or else by a potentiometer 47 having a moving tap 45 connected to the shaft 21, this displacement representing the internal friction. The contact 45 is normally out of engagement with the potentiometer track 47 and is biased into engagement by solenoids 51 which act via a member 48 to depress the potentiometer arm and produce an output signal at regular intervals thus enabling a series of points on a chart to be plotted. Values of internal friction are plotted during a continuous change in temperature of the specimen produced by filling a reservoir 25 attached to the specimen carrying plate 23, with liquid nitrogen and allowing this to evaporate. Elevated temperatures are achieved by a heating coil 32, or by blowing hot air into the glass chamber 36 enclosing the plates. The temperature of the specimen is measured with a thermocouple 34. A paddle wheel 42 in an annular oil bath 43 damps the rotational movements of the shaft, 21; and a weight 52 at the bottom of the shaft 21, which is mounted in needle point bearings 26, 53, provides the required axial force between the sample plate 23 and the driver plate 14. |
