GB2027063A

GB2027063A - Take-down and Tension Device for a Circular Knitting Machine

Info

Publication number: GB2027063A
Application number: GB7914010A
Authority: GB
Original assignee: Elitex Zavody Textilniho; Elitex
Current assignee: Elitex Zavody Textilniho; Elitex
Priority date: 1978-04-24
Filing date: 1979-04-23
Publication date: 1980-02-13
Also published as: IT7922100A0; CS197852B1; DE2916414C2; GB2027063B; IT1166763B; DE2916414A1

Abstract

A circular knitting machine, particularly a double-cylinder knitting machine for the manufacture of sock goods, has a take-down and tension device comprising vertically and independently displaceable rod- shaped take-down elements (6) arranged in a circle, the lower ends of which co-operate with a conical flare of an inner withdrawing tube (10) and the upper ends follow a horizontally arranged cam track (12) provided with a single actuating drive-on lobe. The actuating drive-on lobe is formed by a short ascending portion and an immediately following long slowly descending portion and is located in an area between knitting sections where the needles pass in their raised positions, with old stitches under the needle latches. The cam ensures a continuous tensioning effect along almost the entire circumference of the needle cylinder, as it is the case when using a pneumatic take-down device, and they simultaneously ensure identical conditions for stitch formation. The device in accordance with the invention can be used in single- cylinder circular knitting machines for the manufacture of sock goods too. <IMAGE>

Description

SPECIFICATION Take-down and Tension Device for a Circular Knitting Machine The invention relates to a take-down and tension device for a circular knitting machine, particularly a double-cylinder knitting machine for the manufacture of sock goods and the like.

There are known many types of mechanical take-down and tension devices for double cylinder knitting machines. The most known devices are of the type wherein relatively wide take-down segments act upon the knitted fabric and are arranged into one or two circles. The control is effected in such a way that there are one or more raising drive-on lobes on the cam track, which cause a short-time or quick raising of a take-down segment and, thereby, its putting out of operation, as well as a quick lowering thereof into its operative position and, thereby, withdrawal of the knitted fabric, the adjacent take-down segments remaining in their lower positions and holding and/or tensioning the fabric.

Further, there is known a take-down device which has narrow take-down segments controlled by two cams in such a way that one of the cams controls the odd and the other the even takedown elements, the actuating raising drive-on lobes being offset with respect to each other. The operation of the device is also such that one takedown segment between two adjacent ones is raised and re-lowered.

From the operation of knitting machines it has been known that when using any one of the aforesaid take-down and tension devices, irrespective of the location of the raising drive-on lobe, lengthwise stripes (marks) are produced in the knitted fabric, always at points corresponding to boundaries between neighbouring take-down segments. These lengthwise stripes are, as a matter of fact, distorted wales of stitches which ensue due to releasing and re-tensioning of the fabric, which manifests itself most apparently at the very boundary points of neighbouring takedown elements. These lengthwise stripes in the knitted fabric manifest themselves particularly when knitting jacquard patterns; lengthwise stripes in underside patterns are substantially invisible.

It is an object of the invention to provide a take-down and tension device which would substantially eliminate the lengthwise stripiness.

According to the invention there is provided a take-down and tension device for a circular knitting machine, particularly a doublecylinder knitting machine for the manufacture of sock goods and the like, which comprises vertically and independently displaceable rod-shaped takedown elements arranged in circle, the lower ends of which co-operate with a conical flare of an inner withdrawing tube of a needle cylinder and the upper ends follow a horizontally disposed cam track having a single actuating drive-on lobe, the actuating drive-on lobe being formed by a short ascending portion and an immediately following long, slowly descending portion, the lobe being located within the area between knitting sections, wherein needles pass in their raised positions with old stitches under the latches of the needles.

By way of example, one embodiment of the device in accordance with the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is an axial section through needle cylinders of a double-cylinder machine and showing a take-down and tension device in the upper needle cylinder; and Fig. 2 is a view of a developed form of an embodiment of an actuating drive-on cam lobe, with an illustration of an associated needle controlling cam system.

A known double-cylinder knitting machine for the manufacture of sock goods and the like is provided with a lower needle cylinder 1 and an upper needle cylinder 2 which accommodate needles 3, the latter co-operating with knock over sinkers 4 and press-off sinkers 5. In the upper needle cylinder 2 driven by a mechanical transmission, not shown, from the lower needle cylinder 1 via a toothed wheel 2', is mounted a take-down and tension device.

The take-down and tension device consists of vertically and independently displaceable rodshaped take-down elements 6 which are arranged in a circle in a carrier 7 and spring-loaded by means of tension springs 8. On the lower ends of the take-down elements 6 are mounted, on resilient members, take-down fingers 9 which cooperate with a conical flare of a with-drawing tube 10 of the lower needle cylinder 1. Attached to the upper ends of the take-down elements 6 are follower prisms 11 which abut against an annular cam 12 disposed horizontally on a plate 13. The plate 13 is fixed on columns 14 fixed in an upper flange 1 5. The upper needle cylinder 2 is mounted in a bearing in the upper flange 1 5.On the carrier 7 is further displaceably mounted a sleeve 1 6 the lower shoulder of which serves for lifting the follower prisms 11 and thus for putting the take-down elements 6 out of operation.

Against the underside of an upper shoulder of the sleeve 1 6 abut rollers 1 7 of a forked lever 1 8 which is controlled by a transmission, not shown, from the control drum of the machine. The carrier 7 is fixed on an inner liner 19 of the upper needle cylinder 2.

The circular cam 12 has a single actuating drive-on lobe 120 (Fig. 2) which is formed by a short ascending portion 121 and an immediately following long, slow descending portion 122. The actuating drive-on lobe 120 (Fig. 2) is located between knitting sections, i.e. in the present case between a right hand draw cam 20 of the main knitting section and a draw cam 21 of a subsidiary knitting section; during rotary knitting the needle cylinders 1 and 2 rotate in the direction S. Within this area the needles 3 are raised by a cam 22 by means of needle jacks, not shown, into their raised or clearing positions wherein the old stitches drawn by the draw cam 21 come under the latches of the needles 3.

The operation of the above described device is as follows: During knitting the needle cylinders 1 and 2 rotate in the direction S and the follower prisms 11 of the take-down elements 6 follow, due to the tension of the springs 8, the surface of the circular cam 12. Apart from the actuating drive-on lobe 120 the surface of the circular cam 12 is horizontal so that the take-down elements 6 pass in their lowermost positions and hold the knitted fabric under tension through all knitting sections of the machine and the newly formed stitches of the fabric are withdrawn under the tension of the tensioned fabric. In the course of rotation the follower prisms 11 drive on to the short ascending portion 121 of the actuating drive-on lobe 120 whereby they are raised and the take-down elements 6 thus cease to act upon the fabric within the corresponding angle arch.

However, at the beginning of raising of a takedown element 6, as indicated by the line A, the corresponding needles find themselves, under the effect of the cam 22, already in their clearing positions so that no new stitches are formed nor is a new yarn lapped and the knitted fabric is not subjected to the action of the needles. Thereafter the follower prisms 11 follow the slowly descending portion 122 of the actuating drive-on lobe 120 and, under the action of the springs 8 the take-down elements again gradually and successively tension the released knitted fabric, the stitches of the fabric laying always under the latches of the needles which still assume their raised positions as far as the point indicated by the line B where, with the drawing of the takedown elements 6 completed, the needles start to be drawn and new stitches are formed on the draw cam 20.

Thus, apart from the area between the lines A and B, the knitted fabric is permanently under tension during one revolution of the machine and starting from the top of the actuating drive-on lobe 120 as far as the line B, the fabric is gradually tensioned so that, as a matter of fact, apart from the short ascending portion 121 of the actuating drive-on lobe 120, the fabric is subjected to the action of the take-down elements 6.This great arch of the fabric under tension, including the portion thereof corresponding to the slowly descending portion 122 of the actuating drive-on lobe 120, cause that the stitches on the needles or the newly formed stitches are subjected to a substantially constant tensioning or draw-off force, so that the dimensions of the stitches are identical, the forces in the knitted fabric being uniformly distributed, so that no lengthwise stripes occur in the fabric.

During reciprocatory movement of the needle cylinders 1 and 2 the main knitting section is situated in such a way that the take-down elements 6 in its vicinity always tension the fabric, so that the take-down effects in the portion of the fabric formed by reciprocatory knitting are constant.

The main advantage of the invention, i.e.

location and design of the cam, resides in that it substantially provides for a continuous tensioning and/or take-down effect on almost the entire circumference of the needle cylinders as it is the case when using pneumatic or roller take-down devices, whereby identical conditions for stitch formation are ensured. The present device may be used in single-cylinder sock knitting machines too.

Claims

1. A take-down and tension device for a circular knitting machine, particularly a doublecylinder knitting machine for the manufacture of sock goods and the like, which comprises vertically and independently displaceable rodshaped take-down elements arranged in circle, the lower ends of which co-operate with a conical flare of an inner withdrawing tube of a needle cylinder and the upper ends follow a horizontally disposed cam track having a single actuating drive-on lobe, the actuating drive-on lobe being formed by a short ascending portion and an immediately following long, slowly descending portion, the lobe being located within the area between knitting sections, wherein needles pass in their raised positions with old stitches under the latches of the needles.

2. A take-down and tension device for a circular knitting machine, substantially as hereinbefore described with reference to the accompanying drawings.