Patent GB-386013-A (GB)
Title: Process and apparatus for testing forces
IPC: G01L1/04
Filed: 1931-07-17
Abstract: 386,013. Dynamometers ; testing physical qualities of materials. ERICHSEN, A. M., 5, Elbestrasse, Teltow, Berlin. July 17, 1931, No. 20571. Convention date, July 18, 1930. [Class 106 (ii).] Comprises a method of measuring or indicating forces, pressures, and movements and for producing large forces and pressures by utilizing the changes in form of a highly elastic non-metallic, non-fluid pressure medium such as rubber, the changes in form of which are utilized to actuate mechanical transmission means directly in contact with the medium. A chamber formed between a base 1 and pressure member 2 bolted to it is filled with rubber 3. When a pressure P is applied, the material 3 extrudes through an opening 5, the height of the bulge 6 being measured by a dial gauge 8. A set-screw 9 provides means for giving a preparatory pressure to avoid formation of vacuum spaces. The bulge may be pressed back by means of a plunger 10 on the gauge 8. In another form the material is extruded laterally through a mouthpiece. In Fig. 3, the portion of the material to be extruded is formed as a special renewable plug 14 pressed partly into the mouthpiece 13. The mass 13 and plug 14 may be formed of the same or of different elastic substances. In a modification of this form two mouthpieces in series are provided, the plug being located between them. In Fig. 5 is shown apparatus for testing sheet metal. The upper member 15 is movably arranged in the lower member 16 and forms the die. The metal blank is received in a holder 17 and the force applied to a punch 18. The device may also be used for testing fabrics, paper, &c. In a second form of this device a separate plug and mouthpiece are used. Instead of the bulge acting directly on the gauge, a rigid movable intermediate member may be used, and this may be pressed into the material by a spring placed under compression by a micrometer head instead of using a dial gauge. Figs. 8, 9, and 10 show apparatus for producing high pressures, say for adjusting the rollers in rolling mills. A pressure piston 36 moves in a recess containing elastic material in a base 35. The base is provided with two slots 41, 42 at right-angles to one another communicating at the bottom with two bores 37, 38. Soft rubber plugs 39, 40 are inserted in the bores and may fill the slots as well or these may be filled with separate pieces 43 of rubber. A soft rubber plate 44 covers the whole of the bottom of the recess and a hard rubber plate 45 is laid on top of this. The stroke of the piston is limited by the sleeve 46. A screw-threaded opening 47 affords connection to the part to be adjusted. The pressure applying device comprises a hand-wheel 52, the spindle 51 of which has an enlarged threaded end 53 screwed on to a member 54 which in turn screws on to the member 49 secured to the base 35. A piston 50 is forced forward upon rotation of the wheel to apply force to the plug 39. The member 54 is provided with a scale co-operating with a fixed pointer 55. The pressure is transmitted through the plugs &c. to the piston 36 which carries a dial indicator 58, the plunger 61 of which engages a fixed abutment. A second gauge 62 indicates the pressure in the elastic material, the plate 44 extruding through a hole 63 against a piston 64 pressing against a rubber mass 66 which extrudes through an opening 67 and actuates a member (not shown) in the passage 69 communicating with the gauge 62. In a final form, the base has three chambers arranged in an equilateral triangle and a fourth one separately. The pressure plate is provided with four pistons acting on rubber plugs in the chambers, the fourth chamber communicating with a gauge.