GB884075A - Improvements in or relating to tensioning devices - Google Patents

Abstract

884,075. Knitting machines. MACQUEEN CYBERNETICS Ltd., EVERSHED & VIGNOLES Ltd., and BROOKE, E. R. April 23, 1959 [April 23, 1958]. No. 12926/58. Class 74 (2). [Also in Groups IX and XXXIV] A device for controlling the tension of a yarn &c. passing e.g. to a circular knitting machine, comprises a cylinder rotatable about its axis with an aperture extending axially from one of its ends and opening into the periphery of the cylinder to permit the filament to be fed from the apertured end on to the periphery around which it passes and is frictionally engaged therewith and electromagnetic means biasing the member to rotate in a direction opposed to that in which the filament is fed. In Fig. 1, the yarn passes via a guide 8 to an aperture 4 in the flange of a rotatable member 1 and thence via a guide 9 to the using apparatus; the member is secured to the shaft of a constant torque electric motor at 2, so that when the motor is started, the member is rotated in a direction contrary to that in which the yarn is being fed and a number of turns are wound on the member until the frictional load on the yarn brings the member to rest. The member 1 may comprise a hollow drum or an apertured barrel or spider; in Fig. 5 it comprises a drum 41 with a yarn-aperture 43 mounted to rotate on a shaft 39 and carried by a rotor 37 in a gap between a core 36 and a stator with a threephase winding 35. The torque exerted by the rotor can be varied by a resistance in the circuit of the winding or by moving the core 36, and the rotation of the drum is limited should the yarn break, by lugs on discs on the shaft 39 co-operating with a fixed lug. In Fig. 7 the member comprises a flanged spindle with an axial duct and an aperture 101; it is supported by the flanges of three bobbin-shaped wheels 83 supported in a plate 84 which has a slot, of which the width can be adjusted by a screw to vary the setting of the wheels. The spindle is driven by a metal cup 93 lying as shown between the poles of a core 95 energized by a single-phase winding 96, a copper shading ring 97 being provided. A washer 98 vibrates sufficiently to minimize friction between the spindle and bearing wheels. The drive may alternatively be effected from a continuously driven motor through a magnet co-operating with the cup 93. A stop motion may be provided to prevent the motor racing if an end breaks; this consists of a spring-urged arm resting against the yarn adapted to operate a switch when the yarn breaks. To prevent building up of the diameter of the yarn during re-winding periods, which would interfere with the working tension, the output guide, e.g. 9 in Fig. 1, may then be oscillated.