Apparatus for testing plastic materials

摘要

431,456. Testing physical qualities of materials. BURMAH OIL CO., Ltd., 175, West George Street, Glasgow, and JACKSON, D. H., Britannic House, Finsbury Circus, London. March 21, 1935, No. 8828. [Class 106 (ii)] Apparatus for carrying out hardness and/or bending tests on plastic materials comprises a pendulum member suspended in a frame to contact without pressure against an indenting element, the frame being rotated through an angle to apply the test. The material is moulded on the serrated face 2 of a carrier member 1 within a mould 5 and when set is expelled together with the carrier by rotating a nut 4. For bending tests the specimen is clamped across a hollow in a carrier having a similar screwed shank 3 and nut 4. A pendulum 10 suspended within a frame 11 upon pivot pins 10 carries a steel ball 12 and may be loaded with exchangeable weights 13. One side of the frame has a hinged bridge piece 14 slotted to receive the shank of the carrier which is secured by the nut 4 and a washer 17, the latter and the slot being graduated so that any part of the surface of the specimen may be presented to the ball 12. The frame 11 is provided with a hollow hub 18 journalled in a bearing 19 at one side of a casing 20, a graduated disc 22 on the limb moving over a scale 22 on the frame. Relative movement between frame 11 and pendulum is transmitted by rack and pinion gear 24, 25, to a pointer 28 provided with a vernier scale. Pipes 36 serve for supplying heating or cooling fluid to the casing which is insulated. In use, the cover 34 of the casing is opened and the specimen inserted when the bridge 14 has been turned uppermost adjustment being made so that the specimen just fails to touch the ball 12. After return of the frame 11 to vertical position the nut 15 is adjusted against the influence of the spring 16 until the specimen just touches the ball which point is indicated by a slight movement of pointer 18. The frame 11 is now rotated to bring it to the zero point with the medium line horizontal and the bridge piece undermost when the full weight of the pendulum acts on the specimen. The depth of the indentation may be read off on a scale associated with the disc 22. As the longitudinal axis of pendulum 10 is no longer in line with the medium line of the frame, a correction indicated by the pointer 28 must be made. The bending test is made similarly by substituting the corresponding carrier. In this case it is usually not necessary to rotate the frame 11 through 90‹, and a detachable rack bar is used with a rear gear to give a reduced motion of the disc 22.