GB276776A - Improvements in or relating to apparatus for testing the physical properties of materials - Google Patents

Abstract

276,776. Pelterie, R. Esnault-. June 30, 1926. Testing hardness of materials; testing friction. -The hardness is determined from the contact area between the specimens under a definite butting pressure. The balls 1, 2 to be tested are located the one 1 in a recess 3 in a rotatable member 4, and the other 2 in a recess 5 in one end of a plunger 6 guided on balls, the other end of the plunger being recessed to receive a thrust rod 8 receiving the pressure of a knife edge 10 formed in one with two aligned knife edges 11 and two flanges 12 housed in the head 14 of a beam 15 positioned between jaws on a cover plate 17 connected by bolts and nuts to a casing 18. Inside the casing is a sleeve 20 having a flange 20<1> between which and the cover plate 17 is a spring 22 which is strong enough to hold the cover plate against the nuts 19 in spite of the force exerted on the knife edges so that the cover plate can be set with its axis in coincidence with the axis of the casing and with the correct distance between the knife edges 11 and the ball 1 so that when the balls 1 and 2 are pressed together, the beam is horizontal. The forward part of the cover plate carries a bracket 23 supporting a pillar 24 on which pivots a weighted lever 25 connected by links 27 and knife edges to the beam 15 at the centre of gravity of the latter. The weight 26 exactly balances the dead weight of the beam. Channels 39 are provided through which a wire may be pushed to release the balls 1, 2, the pressure between which may be released by operating the lever 61 which presses against the flange 63 and also moves a rod 64 against an abutment 65 to ease the load on the lever. A microscope, adjustable in three directions at right angles by means of screws 32, 33, 34 is provided at the left hand for viewing the area of contact on the ball 1 after the carrier 4 has been turned through 180‹, light, tangentially to the ball, being admitted through a channel 38. The balls may be coated with silver sulphide for the test. A sliding rod 44 located half in the part 4 and half in the casing 18 is adapted to receive a film carrier 47 carrying at its lower edge a film on which is projected a shadow of the area of contact by X-rays projected through the channel 43 from a Rontgen ray apparatus located in the base of the hollow pillar 29. The rod 44 and film carrier 47 may be moved at right angles to the paper in order to make several exposures. To test friction three balls are used the carrier 4 being cut away to admit a ball between balls arranged as in Fig. 2, the third ball being supported by friction between the other two and carrying a light beam from the ends of which are hung scale pans in which weights are placed. The Hertz test mav be carried out by providing the plunger 6 with an extension so that the ball 2 may engage a quartz plate the Newton rings formed at the contact area being viewed through the microscope.