GB1203644A - Improvements in or relating to a stop motion device for a machine carrying a thread supply - Google Patents

Abstract

1,203,644. Weft stop-motions. S. A. O. RYDBORN. 6 Sept., 1967 [7 Sept., 1966], No. 40639/67. Heading DIE. A stop motion for a machine such as a shuttleless loom in which a weft thread is drawn intermittently from a supply is operated on cessation of an electric signal produced by the running of the thread over a sensing element during a thread detection period. The senser is preferably of the piezeoelectric type, Fig. 8, in which the thread runs in a slot 21 on a rod 23 of piezeoelectric ceramic material held between springs 24, 25. A high frequency electric signal of the order of 30 kilocycles is produced in the cable 32. This signal is applied to the circuit of Fig. 1, first passing through three amplifier stages TR1, TR2, TR3 to give a signal in the form B. This amplied signal then passes to a circuit TR4-TR7 which controls a relay 20 in the machine circuit to stop the machine on cessation of the signal at A on breakage of the thread. To ensure that the relay 20 is not operated during the periods between weft insertions when the thread is not being withdrawn a mechanical switch 30 driven by the machine controls the circuit TR4-TR7. In addition a parallel photoelectric circuit 40, operated by a member 50 attached to the weft inserter, also controls the relay 20 to ensure that, on release of the thread at the selvedge, the relay 20 is not operated. Other forms of senser may be used such as a piezoelectric generator of the crystal type, a photoelectric signal generator, a resistance signal generator or a capacitor signal generator.