Patent GB-847288-A (GB)
Title: Apparatus for testing rubber
IPC: G01N3/18
Filed: 1958-02-04
Abstract: 847,288. Testing physical qualities of materials. FIRESTONE TIRE & RUBBER CO. Feb. 4, 1958 [Feb. 11, 1957], No. 3596/58. Class 106 (2). Apparatus for testing samples of rubber and similar articles comprises a testing region 135 in which the temperature is controlled, and guide rails 120, 122 for delivering samples to and collecting them from that region, the samples being gripped by opposing clamps 160, 161 (Fig. 8) to which a force is applied in the testing region in order to stretch the samples, the force exerted being indicated on a dial 212 (Fig. 1). The testing chamber 20 is provided with thick insulated walls and three insulated doors 40, 60, 76. The main door 40 is provided with a glass panel 47 consisting of five sheets of glass separated by air gaps and remains closed during a test. Two vertically spaced L-shaped guide rails 120 run from the loading bay 56 to a testing point 135, and a further pair of similar rails 122 run from the point 135 to an exit bay 75. Rubber test-pieces of dumb-bell shape are gripped by clamps 140, 141, Fig. 8, which are then manually placed (through the door 60) on to rails 120. A conveyer chain 155, Fig. 3, is then operated by an external hand wheel 161, arms 166 moving the clamps and associated test pieces to the point 135. At this point, keystone members 152 on the clamps 140, 141 enter similarly tapered slots 173 in blocks 170 connected to the load-applying apparatus, the clamps moving off the ends of the rails 120. A test is then made, the load being applied by a motor 193 operating through a variable-speed gear-box 192, and being indicated by the angular position to which a weight 214 is raised. The extension of the test piece is indicated on a fixed vertical scale which can be viewed through the window 47, a balance weight 240 being manually operated to keep the upper end of the test length at a fixed level. The operator can record the load required for certain extensions by operating a spark recorder 229 when the lower end of the test length passes desired points. The weight 214 is maintained in any position by a rack and pawl 217, which can be released by cable 218. After a test, the clamps 140, 141 are moved on to further rails 122 by the conveyer chain 155 and removed from the chamber 20 through the door 76, the operator using a long-handled lever to pull them along the rails 122. A bank of electric heaters controlled by switches 112 is installed on either side of the chamber 20, which is divided into three sections by two vertical sheets of insulating material (not shown), and fans driven by motors 101 circulate the heat through the testing area. The clamps 140, 141 grip the test pieces by spring- controlled eccentrically mounted rollers 143, but in another embodiment, Fig. 9, for testing the adhesion between a layer of fabric 260 and a layer or rubber 261, the layers are gripped between serrated edges on clamping plates 253, 255. In a further embodiment, Fig. 11, for testing 0-rings 282, a plate 270, carrying a vertical chain 271, is mounted on the rails 120. The chain is turned by hand, and the 0-rings are carried to the test point 135 by projections 281. Here each 0-ring is placed over two rollers 288, 291, by the use of the lever referred to above, the rollers being supported in the blocks 170 in the same manner as the clamps 140, 141. As the ring stretches, the tensions in the arms are equalized, since the roller 291 carries a pinion 293 which meshes with a rack 294.