GB1237371A - Improvements in or relating to a process and apparatus for twisting yarn, and to yarn twisted according to the process and apparatus - Google Patents

Abstract

1,237,371. Spinning yarns. ALGEMENE KUNSTZIJDE UNIE N.V. 17 March, 1967 [18 March, 1966], No. 12600/67. Headings DID and D1F. [Also in Divisions G2 and G3] In a process for twisting e.g. drawtwisting, yarn by means of a device having at least one winding spindle around which a twisting member e.g. a traveller, rotates and on which twisted yarn is wound to form a package, during the winding a programming unit continuously imparts a value to the speed of the winding spindle as a function of a progress variable, such as yarn package diameter, representing the progress of the package buildup, such that the speed of the twisting member satisfies the equation n t (v)/n t (v b ) = f(v), where nt(v) is the desired speed of the twisting member corresponding to the value v, n t (v b ) is the desired speed of the twisting member at the beginning of the build (the variable v having the initial value v b ) and f(v) is a programmed function value, dependant on the variable v, defined by the object to be attained by means of the values of the speed n t (v). In the embodiment shown, feed roller 1 (one of several corresponding to the number of stations of a drawtwisting machine) draft roller 4 and a winding spindle (not shown but receiving yarn which has passed through a traveller) are driven respectively by electric motors 3, 6 and 7 the speeds and relative speeds of which are controlled, by a system incorporating control units 10 and 27, programming unit 18 and automatic controller 22, forming parts of interconnected automatic control loops, in accordance with predetermined size and form of package. Thus, electric pulses having a repetition frequency proportional to the speed of roller 1 and emitted by source 8 are applied through unit 10, which also receives signal pulses from a pulse divider 11 (in turn receiving signal pulses through line 12 from a source 13 the emission of which is proportional to the speed of roller 4) and exercises control over the speed of motor 3. The latter pulses are applied to pulse dividers 15 and 16 which apply an adjustable proportion of the input pulses to a slipping motor 17 coupled to and operating the unit 18 which so sets the frequency division of the pulse divider 16 that the repetition frequency of its outgoing pulses is proportional to v/#d (where d is the prevailing yarn package diameter, V is the draw' rate). A pulse generator 30 develops a train of frequency-adjustable pulses applied to a pulse divider 20 so set by an additional control programmer in unit 18 that the repetition frequency of its emitted pulses is proportional to traveller speed or twist. The pulses emitted by dividers 16, 20, are applied to securing device 21 the output of which is compared at 25 with the pulses emitted from source 24 mechanically coupled to motor 7 and control is effected by element 26 through correcting element 23.