GB833510A - Improvements in or relating to devices for testing metal specimens under bending stress - Google Patents

Abstract

833,510. Testing bending of materials. PHILIPS' GLOEILAMPENFABRIEKEN N.V. Sept. 19, 1956 [Sept. 22, 1955], No. 28641/56. Class 106 (2). A device for testing metal specimens 11 under bending stress comprises a mandrel 8 having a circular cylindrical surface 10 around which the specimen 11 is bent, and bending means comprising a roller 18 such that, at any angle of bending, bending stress is exerted on the specimen only at the instantaneous point of contact between the specimen and the mandrel 8 (the point on the specimen which has just come into contact with the mandrel) and bending occurs only at that point. The mandrel 8 lies between a supporting member 4, resting on springs 5, and the specimen 11 to be tested, the latter being held against the mandrel 8 by a member 12 engaged by an interchangeable thrust member 13 acted upon by an eccentric 14. Three rollers 18 on a second thrust member 17 act against the specimen 11, the lowest roller having its axis in the same horizontal plane as the centre line of the circular surface 10 before starting the test. A lever 22, to which the member 17 is adjustably secured pivots about the centre line of the circular surface 10 and is used for applying the bending thrust. When the specimen 11 has been bent through 90 degrees, cams 23, comprising circles with their centres above the pivots of lever 22, act on pins 6 protruding from the supporting member 4 and lower it against the action of the springs 5, thus allowing bending through 180 degrees to take place. One of the cams 23 is graduated in degrees and together with a pointer on the side of the apparatus permits the angle of bending at which fracture or cracking may occur to be read. The mandrel 8 may be interchangeable with other mandrels, and so may the thrust member 12.