IL30641A - Knitting machines and method for feeding them with thread - Google Patents

Description

machines and method for thread 28868 This invention relates to knitting particularly but not exclusively to circular ribbed knitting machines having a plurality of yarn For supplying yarn to the knitting stations of ing particularly but not exclusively to circular ribbed knitting machines having a plurality of yarn For supplying yarn to the knitting stations of knitting thread delivery arrangements with positive delivery rollers transporting yarn without and delivery transportin the yarn with are The yarns are wrapped one or more times round the delivery rollers which rotate at a constant speed suoh that with positive feed the peripheral speed of the roller is equal to or somewhat above the yarn delivery speed and with yarn feed it is substantially higher than the yarn delivery With positive delivery thread feeding arrangements it is known to use conical delivery rollers for varying the speed of the yarn on which the loops of yarn wrapped round the roller can be displaced parallel to the axis of the or to use delivery rollers with differing In the case of knitting machines with several yarn delivery rollers it is also known already to surface materials with different efficients of friction on the rollers with the object of ing yarns of the same kind a little more slowly or because of the different friction conditions and the insignificant slip associated In surfaces of these rollers consist of rabber or thread in which delivery rollers with surfaces are has the advantage by comparison with positive thread that with changing for in patterns with a change in the type of a constant yarn tension is maintained automatically between the delivery roller and the knitting Here the rollers are rotated at a speed for 3000 to 5000 so that fluctuations in yarn tension are compensated for very A particular problem and one which had not been previously solved in the case of thread arises in the processing of yarns with different istics in the same knitting since the sliding friction between the hard surface of the customary delivery and varyin types of yarns such as wool or cotton or twisted or textured yarns varies considerably and leads to different tensions between the delivery rollers and the associated knitting The result of is an uneven and useless stitch It is the purpose of the in order to avoid producing of different size during the knitting to match the delivery characteristic of the yam delivery roller to the surface nature of the yam to be by so that different types of are fed to their respective knitting stations at the same According to the present invention there is provided a method of thread with slip in a knitting machine having a plurality of thread said thread bein fed to a knitting station only when a stitch to be said method comprising providing a thread delivery for thread rotating said roller continuously at a peripheral speed which is substantially higher than the speed of the thread during stitch formation and providing each said roller with a detachable sleeve having a predetermined coefficient of the surface of the sleeve being selected such that it feeds thread only in response to tension in the thread during the period of stitch formation and whioh permite total slip the thread remains substantially stationary when said tension ceases between The invention also provides a knitting machine having a plurality of thread feeds comprising means for feeding thread with slip to a knitting station only while a stitch is being said means for feeding thread comprising a thread delivery roller for each thread feed and for continuously rotating each said roller at a peripheral speed substantially higher than the linear speed at whioh the thread is fed during the period of stitch each said thread delivery roller comprising a detachable sleeve having a predetermined coefficient of friction so that the surface of the sleeve entrains said thread in response to tension generated in the thread only during stitch formation and permits total slip when said tension ceases between The expression should be understood in this in a broad that is depending on requirements it is possible to use smooth surfaces or surfaces with fine to oughening or equivalent Interruptions to the otherwise smooth The different surface characteristic the intended to impart speeds to yarns of same type but to adjust the yarn tensions of dissimilar yarns the same the types of thread used differ only slightly from One another it is possible that an increase in the diameter of the delivery rollers and consequently an increase contact surface the yarns would be sinoe this increases the sliding friction between the yarns and surface of the When there is a very big difference between the nature of the on the other it may be advisable to modify both the nature of the roller surface and also the diameter of the When the ya s are changed the delivery rollers must also be This can be performed in accordance with a further feature of the by constructing the thread delivery rollers with central mandrels or all of which have the same diameter and sleeves having di ferent chosen surface characteristics external diameters are rotatably engaged ith each The different surface characteristic the different diameters the delivery rollers is thus not intended to impart different speeds to yarns of the same type but to the yam tensions of dissimilar ya s to the same When the types of thread used differ only slightly from one another it is possible that increase in the diameter of the delivery rollers and consequently an increase contact surface for the would be since this increases the sliding friction between the yarns difference between the nature of the yams on the other it may be advisable to modify both the nature of the roller surface and also the diameter of the When the yarns are changed the delivery rollers must also be This can be performed in accordance with a further feature of the by constructing the thread delivery rollers with central mandrels or all of which have the same diameter and sleeves having different chosen surface characteristics different external diameters are rotatably engaged with each Whether the different types of should be transported by delivery rollers with a smooth surface or with a rough surface or with a greater or lesser diameter cannot be reduced to a in view of the many factors which have to be taken into It can be stated in general that yarns of lower adhesive character must be transported by relatively smoother rollers and those of greater adhesive character by rollers with a relatively rougher smooth and textured yarns tend to be more On the other hand twisted cotton and yarns tend to be less adhesive and thus slip more limits as to whether a yarn is to be assumed as adhesive or with respect to the of the feedwheel are not fixed by the designation of the various types of yarn because the oiliness and waxiness of the yarns are also By a combination of delivery rollers with different possible for yarns to be fed to all the knitting stations of a knitting machine at very nearly the same eve knitting machines with a plurality of knitting such as circular rib knitting machines with 24 or 48 and using a plurality of yams of different types The accompanying drawing illustrates by of example one embodiment of the invention now to be arranged in four thread delivery rollers of a circular knitting machine equipped with four or more of which each delivery roller feeds a different type of to a knittin The thread delivery rollers consist of the elements or mandrels 7 and which have equal diameters and are rotated by toothed bear wheels or direct electric motor drive On each of the four thread delivery roller sleeves 11 and are firmly mounted for rotation Sleeve 9 and sleeve 10 have equal diameter of the sleeve 11 is greater than that of the sleeves 9 and and diameter of the sleeve 12 is greater than that of the sleeve The sleeve has a smooth a hard The sleeve 10 has a rough surface the surface has relatively small which have been generated example by a sand blaster or also by mechanical The sleeve 11 has a smooth which is equivalent to that of the bushing The sleeve 12 has a h surface which is equivalent for example to that of the bushing Prom each thread delivery roller a different type of ya and 4 is fed in 1 a worsted yarn 2 is a textured yarn 3 is fancy yarn and yarn 4 is a smooth synthetic The yarn distribution is to be understood purely as an example of the fact that the surface characteristic of each of the delivery rollers is adapted to the characteristic of yarn fed thereby so the case of uniform yarn tension before the feed a sliding friction is produced by the choice of thread delivery roller characteristic and the diameter of the delivery which generates a uniform yarn tension between the thread delivery rollers and the itting insufficientOCRQuality

Claims (6)

1. A method of feeding thread with slip in a knitting machine having a pluralit of thread feeds, said thread being fed to a knitting station only when a stitch is to he formed, said method comprising providing a thread delivery roller for eadh thread feed around which said thread is laid at least partially and rotating said roller ' continuously at a peripheral speed which is substantially higher than the linear speed of the thread during stitch formation and providing each said roller with a detachable sleeve having a predetermined coefficient of friction, the surface of the sleeve being selected such that it feeds thread only in response to tension in the thread during the period of stitch formation and which permits total slip while the thread remains substantially stationary when said tension ceases between stitches.

2. , A knitting machine having a plurality of thread feeds comprising means for feeding thread with slip to .a knitting station only while a stitch is being formed, said means for feeding thread comprising a thread delivery roller for each thread feed and means for continuously rotating each said roller at a peripheral speed substantially higher than the linear speed at which the thread is fed during the period of stitch formation, each said thread delivery roller comprising a detachable sleeve having a predetermined coefficient of friction, so that the surface of the sleeve entrains said thread in response to tension generated in the thread only during stitch formation and permits total slip when said tension ceases between stitches* 30641/2 i - 10

3. A knitting machine according to Claim 2, wherein each sleeve provided on a roller has a predetermined diameter selected in dependence on the surfacecharacteriBtic of the yarn, said sleeve being rotatably mounted on a mandrel.

4. A knitting machine according to any one of Claims 2 to 3 wherein the coefficient of friction of each roller surface is determined in accordance with the characteristics of the thread with which the roller is adapted to be used.

5. A method of feeding thread substantially as hereinbefore described with reference to the accompanying drawings.

6. A knitting machine substantially as hereinbefore described with reference to the accompanying drawings. For the Applicants DR. PARTNERS