GB257066A - Improved apparatus for testing sheet metal - Google Patents

Abstract

257,066. Haas, A. L. July 14, 1925. Testing physical qualities of materials; dynamometers. - Apparatus for testing sheet metal by the distension to fracture of a tightly-clamped test specimen by direct central pressure of a ball or other circular solid geometrical shape, comprises a rotatable vertical concentric assemblage of three members interconnected by screw threads whereby the test specimen is clamped, distended or released by rotation of said assemblage when the inner component members are held stationary in succession. A tubular internallythreaded member 1 is provided with opposite slots 2 and is adapted to receive an externallythreaded lower clamping member 3 which is internally threaded to receive a central pressure screw 4. An upper clamping member 5 is inserted through the. slots 2, the circular boss 6 being a loose fit in the outer member 1. The member 5 is provided with handles 7 and a central hole 8 flared outwardly. A washer 9 having an annular projection 10 is a press fit in a groove in the member 5. The lower member 3 is provided with a washer 13 having an annular groove 14 corresponding with the projection 10, and houses a ball-thrust bearing 17 on the upper surface of which is seated a ball 18. In use, the sheet-metal plate to be tested is placed between the projection 10 and groove 14, the squared part 19 is gripped-as in a vice-and the outer member 1 rotated by means of the handles 7 until the plate touches the ball 18. The grip is then released and the squared part 20 gripped, the parts 1 and 3 being rotated together until the plate is distended to fracture. The thickness of the specimen may be read off by the graduations 21, 22 on a flat formed on the screwed part 3 cooperating with the graduated rim 23. The distention may be read off on similar graduations 25, 26, 27 in connection with the part 4, a collar on the part 4 engaging a shoulder 12 in the zero position. Instead of the ball 18 a line profile tool of the construction shown in Fig. III. may be used. The tool is of cruciform section the bottoms of the flanges 30 fitting into slots 16 in the top of the member 4. A solid tool of the same general shape could be used. In a modification shown in Fig. VII., the member 1 enters a housing having a base 37 and a locking ring 34. The member 1 may be rotated by worm gear 44, 36, and a throw-over dog 39 may fix the lower member 3 or the pressure screw 4 by engagement with notches in flanges at the lower end thereof. The thickness of the sheet is indicated by an index point 21 and graduations 22 on the edges of the slots 2 in co-operation with the graduated top edge 23 of the lower clamping member 3. The distension of the specimen is indexed by a pointer 25 on a friction band surrounding the member 1 in conjunction with a graduated bevel edge 27 of the locking ring 34. The resistance to distension may be indicated by measuring the end thrust of the worm shaft 45 which moves a pendulum 56 which through gears 59, 61, 64 rotates a graduated ring co-operating with an index 65.