GB353693A - Improvements in or relating to methods and apparatus for determining the plasticity of substances - Google Patents

Abstract

353,693. Testing physical qualities. WHITE, A. E., 5, Quality Court, Chancery Lane, London.-(Goodrich Co., B. F.; 37, West 60th Street, New York, U.S.A.) July 24, 1930, No. 22368. [Class 106 (ii).] The plasticity of a substance such as unvulcanized rubber is determined by applying a deforming force for a predetermined time, and measuring the deformation and the amount of recovery after removal of the force. A test piece 26 is supported on a cap carried by a tube 22 of porcelain or glass which is supported in a socket pressed downward by a spring 32. The tube 22 is adjusted vertically by means of a bevelled block 36 having a threaded portion 40, which is moved horizontally by operating a handle 45, which is associated with a revolution counter 49. The load is applied to the specimen by a porcelain or glass tube 53 having caps 54, 56, the latter being pressed upward by a spring 58. Another spring 60 is interposed between the cap 56 and a hollow slider 59, and the latter is pivoted to one of a pair of toggle links 61, 62. The downward force exerted on the specimen by means of the spring 60 is measured, under different conditions of compression, by substituting a weighing device for the specimen. The toggles are operated to apply the load by the horizontal movement of a rod 74 carrying a guide 77 in which slides a block 78 carried by a pin 79 projecting from a rotating disc 80. The shaft 81 carries a sleeve 81a with clutch member 84, the other member of the clutch being carried by a shaft 85 which is driven at a uniform speed, through gearing, by a synchronous motor 88. The sleeve 81a carries also one member of a clutch 81b. The clutch 84 is engaged by means of a collar 102 adapted for limited sliding movement on the sleeve 81a and for rotary movement with the sleeve. The collar 102 has a cam groove 103 engaging a pin 104 which is adapted to be retracted from the groove by downward pressure on a hand-operated lever 112. The clutch 113 has two recesses 114, Fig. 4, one of which is normally engaged by a pin 116, which may be retracted by downward pressure on another hand-operated lever 123. The deformation of the test piece is measured by means of a rod 127 extending upward through the loading mechanism to a dashpot 129 where it is connected to a horizontal rod 131. The other end of the rod 131 extends into a slot 134 in an indicating pointer 133 operating over a chart or dial 135, which is driven at twice the rate of the shaft 81 through gearing 140. The test piece is contained in a vessel 154 within a vessel 153, the space between the two vessels containing an electric heater. The vessel 153 is arranged within an outer vessel, the intervening space containing heat insulating material. In using the apparatus, the rod 127 is raised by a lever 149 and the test piece placed in position and moved upward by operating the handle 45 until the indicator is at zero. The motor 88 is started, and the levers 112, 123 momentarily depressed to withdraw the pins 104, 116 from the recesses 103, 114, so that the clutches 113, 84 are engaged and the shaft 81 is rotated. The shaft 81 acts through block 78, guide 77 and rod 74 upon the toggles 61, 62 and a load is applied to the test piece during a predetermined period, e.g. 1 second. At the same time the indicator dial 135 is set in motion and the deformation of the test piece recorded. The deformation in conjunction with the known compression of the spring 60 is a measure of the load applied. The release of the lever 123 allows the pin 116 to engage one of the recesses 114, the end of which is curved so that continued rotation forces the clutch 113 along the shaft to disengage it. The pin 116 locks the shaft 81 and the force-applying mechanism against further movement. Release of the lever 112 allows the pin 104 to engage the recess 103 and the collar 102 is forced along the sleeve 81a to disengage the clutch 84, whereby the dial 135 is stopped, the movement of the collar also engaging the clutch 113 which is locked against rotation by the pin 116. The first half revolution of the dial 135 records the deforming load and deformation, and the second half revolution records the recovery of the test piece. If the recovery occupies a longer period, the lever 112 is held depressed to cause continued rotation of the dial 135.