GB1137890A - Improvements relating to compensating yarn brakes - Google Patents

Abstract

1137890 Yarn-tensioning apparatus GLANZSTOFF A G 29 Dec 1965 [29 Dec 1964] 55084/65 Heading DID [Also in Divisions F2 and H2] Means for keeping the tension constant in a yarn by producing a braking-pressure which is continuously variable in dependance on the position of a yarn feeler arm comprises a yarn guide roller associated with a reversing roller and braking means operating on the guide roller and actuated by the movement of a yarn feeler arm. In Fig.4, a yarn roller 3 is rotatably mounted on a shaft and has at one end an annular braking- surface 10 against which a pair of pivoted, spring- urged, brake shoes 14, 15 can be made to bear as a cam 17 is rotated. Also mounted rotatably on the shaft is a feeler arm 24; this has a yarn-guide 38 at one end and is connected at the other end by a spring 23 to a lever 19 connected to the cam and, by an adjustable spring 21, to a fixed part. When the yarn tension is at its lowest value, the arm is in its uppermost position, and spring 23 allows spring 21 to exert its maximum effect on lever 19 so that the cam is rotated fully to engage the brake. When the arm is pulled down by increased yarntension, the effect of spring 21 on the brake shoes is gradually weakened, until, with the arm in its lowermost position, the brake is fully released. In Fig.5, the roller has at one end a housing for a ring 27 of magnetic or electrically-conducting material and the arm is connected to a housing containing permanent of electromagnets 29 working on a thread 32 of steep pitch on the shaft. As the arm rotates, the magnets are moved correspondingly towards or away from the housing on the roller. The other end of the feeler arm is, in this case, anchored to a fixed part by an adjustable spring. The working tension is set by adjusting the gap between the roller housing and the magnets where these are permanent, or, in the case of electromagnets, by changing the magnetizing current. In another form, the width of the gap between the roller housing and the electromagnets is constant, and the exciting current of the electromagnets is varied according to the position of the arm. The roller may have a non-slip surface or may be used in conjunction with a reversing-roller. The apparatus is described in an arrangement where the roller is used in conjunction with a reversing roller the yarn being repeatedly looped around the two, and reaching the rollers via a fixed yarnguide. The reversing roller may be replaced by a second guide roller, in which case the yarn is prevented from slipping by providing a roughened surface on both rollers.