Patent GB-469137-A (GB)
Title: Improvements in thread testing device
IPC: G01N3/08
Filed: 1936-02-24
Abstract: 469,137. Testing strength of thread. CLARK THREAD CO. Feb. 24, 1936, No. 5480. Convention date, March 5, 1935. [Class 106 (ii)] Relates to machines in which a length of thread is drawn between an indicator clamp and a breaking clamp, the clamps being closed and the thread broken by moving the breaking clamp away from the indicating clamp ; and consists in providing feed clamps which automatically seize the thread and place a fresh length between the test clamps after each, breakage. The frame 4 comprising four arms 17, 18, 19, 20 is intermittently in the direction of the arrow by means of reduction gearing and a Geneva mechanism from a motor. At each movement the arm moves through a quarter turn. In the position shown, a spring clamp at the end of arm 18 is held from gripping the thread by a fixed tooth. On moving away from this position the thread 2 is gripped and a fresh length drawn from a supply 1 through a tensioning device 3 over arm 19 and is laid over clamps 5, 14 which are in the released condition. When the arm 18 has taken 'the position of the arm 17, a length of thread for test is positioned between clamps 5. 14 and is under slight tension. The clamps 5, 14 are operated by solenoids 63 against the influence of springs. The clamp 5 is carried by an arm 6 attached to a weighing machine 8 of standard construction. The clamp 14 is carried at the end of an arm 13 pivoted about an axis 12. At this stage a cam 41 in the drive from the motor to the shaft 9, engages the lever 13 which carries a clamp 14 and the thread is subjected to a pull until it breaks. This moves the arm 6 and the pointer 66 of the weighing machine which is held in the position reached by a pawl 67 engaging a toothed rack 68 pivoted about the shaft 69 and held in the position shown by a spring 72. The rack is pulled down at the appropriate time by a solenoid 70 to release the lever which returns to zero. The breaking test occurs when the frame 4 is stationary. When again the frame is advanced the arm in the position 18 grips the thread and another length is drawn out, positioned over clamps 5, 14 and broken during the next stationary period of the part 4. The Specification as open to inspection under Sect. 91 comprises a " breaks-required " switch which is set to a selected number of breaks. The main switches are then made and the device started. A length of thread is drawn out, clamped, and broken, the pointer of the weighing machine moving a perforated arcuate shutter across a photo-electric cell to send a number of impulses corresponding to the number of ounces of pull on the thread to step around a switch so as to select one or more solenoids of a key-actuating mechanism used with a calculating machine and partly close their circuits. On breakage of the thread, the reading is held while another rotary switch sweeps over its contacts and closes the circuit of the selected solenoid or solenoids and causes the recorder to print the amount of load and to feed the paper on one step. A third switch is stepped around once for each break. After the record is made, the ratchet rack is pulled down and the weighing pointer and selector switch returns to zero. Another length of thread is pulled out, broken, recorded and'so on until the third switch has moved to correspond with the number of breaks selected when the machine is automatically stopped. In a modification, where the holes in the selector would be unusually close together, the holes are given a wide pitch and two cells used spaced apart one-and-a-half times the pitch of the holes so that only one cell sends an impulse at each passing of a hole. This subject-matter does not appear in the Specification as accepted.