GB1456834A - Weft straightening - Google Patents

Abstract

1456834 Correcting weft distortion; woven fabric WIRA 19 Feb 1974 [9 Dec 1972] 56937/72 Headings D1K and D1S For detecting the distortion of weft threads in a length of woven fabric 1, one of the weft threads 6 at each end of the fabric 1 is or is rendered sufficiently different from the other weft threads in a particular characteristic or adaption so as to be detectable by a suitable sensing device. The fabric 1, Fig. 1, has warp threads 2a, 2b, 2c,...., pattern weft threads 3a, 3b, 3c,...., and a "heading" comprising weft threads 4, 5, 6, 7 of which the thread 6 has a high light reflectance. As shown, the weft threads are .skewed. Sensing devices 9, 10 are located to lie on a line at right angles to the warp. The fabric moves in the direction of an arrow 8 and weft (pick) counting devices are switched on by the passage of the thread 6 past each device 9, 10 individually. After a predetermined time, the difference in the number of weft threads counted is a measure of the skew of the weft and a signal is emitted to control a weft straightening machine. The devices 9, 10 each comprise a photocell 12, Fig. 2, illuminated by a light source 11. Light from a separate source 13 illuminates the upper face of the fabric 1. When the thread 6 passes the photocell 12, light from the source 13, is reflected by the thread 6 to illuminate strongly the photocell 12 to start Ithe respective counting device. In modifications (not shown), (a) each device 9, 10 includes a separate sensing means working on different principles and a photocell producing a peak signal on the passage of a highly reflective thread is still used to actuate the counting device; (to) the light source 13 is omitted and each device 9, 10 is provided with an auxiliary photocell, on the same side of the fabric as the source 11, which actuates the counting device when it receives a pulse of light by reflection from the thread 6; and (c) the light reflective thread 6 is replaced by a thread having connected thereto enlargements or tapes or coated with magnetic or electrically conductive material and is detected by electrical, electro-mechanical, inductive, capacitive or magnetic means.