Patent GB-408387-A (GB)
Title: Improvements in testing extensible material
IPC: G01N3/08
Filed: 1932-11-30
Abstract: 408,387. Testing extensibility of thread &c. DUNLOP RUBBER CO., Ltd., 32, Osnaburgh Street, London, and SIMPSON, E., Fort Dunlop, Birmingham. Nov. 30, 1932, No. 33870. [Class 106 (ii).] A long length of thread &c. is tested by intermittently actuated means which causes portions to be held clamped at successive intervals such portions being extended under a predetermined load. A cruciform framework carries a pair of sprocket wheels 1, 2 at its upper and lower ends respectively over which passes an endless chain 3 driven bv the wheel 1 keyed to a shaft driven by belt and pulley 4, 5 from one 6b of three pulleys 6<a>, 6<b>, 6<c> keyed to a countershaft C<d> driven from a motor 7. Spindles 8, 9 are supported in the crosspiece and carry interchangeable drums or spider frames 10, 11. The spindles are driven from a belt, not shown, but which passes over pulleys 12, 13. The pulley 6<c> drives one 14<a> of a set of pulleys 14<a>, 14<b>, 14<c> of which the pulley 14<a> rotates independently of the other two except when a cone clutch operated by the lever 15 clutches it to the other two 14b, 14<c> which are keyed to the shaft. The double-grooved pulley 14<c> drives a smaller double-grooved pulley 16, the front grooves carrying the thread 8<a> to be tested. Fixed on the framework below the pulleys 14<a> is a block 18 carrying parallel moving jaw clamps 18<a> closed by springs 18<b>. The thread is wound on a drum 10 and is paid out and upward through a pigtail wire guide 33, over pulley 14<c>, down through the open clamps 18<a> and around a pulley 24<c> on a lower sliding block 24, upwards again over the pulley 16, and diagonally through guides 33 to the take-up spider. The chain is provided with one cam link 22, and at this stage the link 22 is just above the upper block. The test length is constant and is the length between the lower edge of the left clamp and around the lower block pulley in raised position, to the lower edge of the right hand clamp. A standard load weight 26 is now placed on the hook attached to the frame of the pulley and the motor is started, the chain moving and the left hand span travelling upwards in Fig. 1. The clutch operated by the lever 15 is in and the thread drive is operative, a loop being formed at the paying off drum. The upper block 21 has a limited movement up and down relatively to the frame. The block is provided with two spring pressed gates 21<a>, each provided with a cam surface 21d which normally the links of the chain can clear. When, however, the cam link 22 passing down the right hand span engages the right hand gate it cannot pass and moves the block 21 downwards. A rod 15b attached to the lever 15 causes the clutch to be disengaged. At the same time cams 21<a> attached to the block and engaging pins 18<c> on the back of the clamps 18<a> moved down and allow the clamps to grip the thread. The gates move between guides 23<a>, 23b which are provided with cut-away portions. That on the right hand side now allows the right hand gate to open and the cam link 22 to pass. The cam link next engages the right hand gate 24<a> on the lower block and carries the latter downward and stretching the test loop to about the position shown in Fig. 1, that is until the tension in the test loop balances the load when the pulley lifts from its seating and electric contact 24 engages a contact 24@ to close an electric circuit containing a relay (not shown) and an electromagnet 27 which lifts a recording pin 30f from a drum 31. This also energizes a magnet 29 fixed behind the lower block which causes the block to become locked to the guide bar 19. This allows the cam link to open the gate against the influence of the spring and on passing the gate the cam link engages a switch lever 24j which operates to open the circuit of the relay and to de-energize both magnets. The cam link passes around the lower sprocket to the left hand span and engages the left hand gate to raise the lower block. As the lower block reaches the upper position it contacts with the crosspiece 20 and as the guide members 28<a>, 28b stop short below the upper block, the gates 24<a> can open, the cam link passing through. Contact between the small contact switch lever and the right hand side member is made, setting the switch back to its original position and breaking the electromagnet circuit. The continued upward movement of the cam link engages the left gate of the upper block, carries it upward, then opens it and afterwards engages the clutch ready for the next cycle of operations. During each cycle, when the upper block is moved to the lower position, it depresses the ratchet lever 32 to rotate the chart drum one step through the medium of gears 32, 32b, 32<c>. The upward movement releases the ratchet lever which is spring loaded and allows the drum to rotate through a small distance to have the successive records at small intervals. A chain attached at one end to the lever block passes over pulleys to a balance weight 30b. One pulley 30<a> has on the same axle a toothed wheel 30<c> gearing with a wheel 30d on a screwed shaft 30<e> which traverses the pen. The pen once lifted is kept lifted by the residual magnetism of the electromagnet until on return to starting point the armature 30' engages a small projection 30h which allows the pen to contact with the chart again.