GB2199341A

GB2199341A - A circular knitting machine

Info

Publication number: GB2199341A
Application number: GB08730268A
Authority: GB
Inventors: Dieter Rothe; Jurgen Hunger; Bernd Biedermann; Siegfried Bottger
Original assignee: Kombinat Textima VEB
Current assignee: Kombinat Textima VEB
Priority date: 1986-12-29
Filing date: 1987-12-29
Publication date: 1988-07-06
Anticipated expiration: 2007-12-29
Also published as: DD256337A1; ES2006254A6; DE3735561A1; GB2199341B; GB8730268D0

Description

2199341 v A Circular Knitting Machine The present invention relates to

machine.

a circular knitting In conventional sinker top circular knitting machines, the loop-forming sinkers move in a horizontal direction and operation thereof is adapt6d predominatly to the -knocking over and holding down of the stitches (Offermann: Tausch-Marton, Grundlagen der Maschenwarentechnologie, page 33-36, VEB Fachbuchverlag Leipzig, 1978).

One shortcoming of these circular knitting machines is that, on account. of the yarn which is kinked by means of the loop-forming sinkers and knitting needles, it is necessary to select a relatively large angle of inclination on a loop-sinking cam by means of which the movement of the knitting needles is controlled, so that the number of knitting needles having a simultaneous loop-sinking motion does not exceed the limit at which s; 4_ is - 2 the yarn tension increases so much due to high friction that the yarn tears. However, if the loop-sinking member has a large angle of inclination, it limits the possibilities for increasing the operating speed of the machine and causes high susceptance to failure and considerable wear on knitting neeldes.

To avoid this disadvantage, it is already known that the loop-forming sinkers can initially be driven out in an oblique direction and then in a horizontal direction. The stitches are therefore formed, in part, by the loop-sinking motion of the knitting needles and, in part, by the oblique motion of the loop-forming sinkers (DE-OS 2.554.119: D 04 B: 9/00).

As the transition of the loop-forming sinkers from an oblique motion into a horizontal motion can only be effected with technical difficulty and, in any case, without closed cam curves, this solution cannot help to increase in the operating speed and reduce needle wear, as closed cam curves are essential for this purpose.

-i 3 It is also known to design the loop-forming sinkers, provided with a holding down throat, between the needles in the needle cylinder so as to be movable in the longitudinal direction of the needles and also to be pivotal transversely to the needles, by mounting them on pivoting levers resting on the base of the ne,edle cylinder so that they are movable in the direction of needle ejection by a sinker cam (DD-PS 235 891, D 04 B: 9/00: DD-PS 237 857, D - 04 B.- 15/86).

This solution necessitates reiati-v61y large dimensioned design of the loop-forming sinkers and therefore inevitably increases the size thereof. Furthermore, the mounting of the loop-forming sinkers on a respective pivoting lever is disadvantageous because the loop-forming sinkers tend to tip in the circumferential direction of the needle cylinder and therefore necessitate high lateral guide webs or deep cylinder grooves which complicate and increase the cost of needle cylinder production, In addition, exact guidance of the sinker feet in the sinker ejection cam is not assured owing to the pivoting motion of the loop-forming sinker transversely to the motion of the needles. Finally, the plurality of moving parts 4 arranged in the restricted space in the needle cylinder leads to marked heating of the needle cylinder during operation of the machine and this in turn limits the knitting speed and increases wear of the needles and sinkers.

Accordingly, the object of the present invention is to allow an increase in the operating speed of the circular knitting machine and a r-eduction in the wear of needles and sinkers.

According to the present invention there is provided a circular knitting machine comprising a needle cylinder, a plurality of needles movable longitudinally on the cylinder to perform knitting, a pluality of knockingover and loop-forming sinkers mounted on the needle cylinder between the needles, said sinkers being movable solely in the direction of movement of the a ring around the needle cylinder for being driven therewith, and a plurality of holding-down sinkers mounted on the ring, said holding-down sinkers being movable radially with respect to the needle cylinder.

needles - r t By means of the invention it is possible to allow precise guidance of the stitch forming elements at all moments of the stitch forming cycle and furthermore closed cam curves can be used to provide a compact design of stitch-forming element. In addition it is possible to prevent excessive heating of the needle cylinder and to simplify production of the needle cylinder.

In a preferred embodiment of the invention, the knocking-over and loopforming sinkers are guided in a separate upper part of the needle cylinder, their cam being arranged above the needle cam on a special stationary holding ring of the machine.

Preferably, the ring which is provided for mounting of the holding-down sinkers and can be driven synchronously with the needle cylinder is mounted by means of sliding bearings on a further statinary holding ring arranged above the sinker cam.

The invention will now be explained in more detail below with reference to an embodiment illustrated in the drawings:

6 - Figure 1 shows a partial axial section through the needle cylinder of the sinker top ciruclar knitting machine of large diameter according to the invention; Figure 2 shows schematically the needle cam and the sinker cams of the sinker top circular knitting machine shown in Figure 1; Figure 3 shows the position of the holding-down sinkers during ejection of the needles for laying the thread; and Figure 4 shows the position of the holding-down sinkers when doffing the needles for loop-sinking and knocking over.

Latch needles 1 of the circular knitting machine are mounted in longitudinally movable manner in the grooves 2 of the needle cylinder 3. A knocking-over and loop-forming sinker 5 provided with a knocking-over edge 4 is arranged between each two latch needles 1, reaches over the edge of the needle cylinder 6 and is provided with a foot 7 which engages in the sinker carp, 8 mounted on a stationary holding ring 16a of the machine.

f 7 The knocking-over and loop-forming sinkers 5 are advantageously arranged in the grooves 9 of a separate upper par-t 3a of the needle cylinder 3 so that the grooves 9 of the upper part of the needle cylinder 3a are staggered relative to the grooves 2.

Holding-down sinkers 11 which are movable exclusively radially relative to the needle cylinder 3 or the upper part 3a thereof are arranged at right angles to the knocking-over and 16op-forming sinkers 5 but also staggered with respect to the latch needles 1 in the grooves of a ring 10 surrounding the needle cylinder 3 or the upper part 3a thereof by means of a cam web 14 engaging between their feet 12; 13. The ring 10 holding the holding-down sinkers 11 is rotationally engage-d with a toothed crown 15 which is mounted on a further stationary holding ring l6b of the machine by means of sliding bearings and can be driven synchronously with the needle cylinder 3 (Figure I).- Each latch needle 1 of the circular knitting machine according to the invention is provided in the conventional manner, for example, with a central foot 17 and a respective pattern foot 18a; 18b; or 18c and 8 18d, which are each provided at the needle shaft (Figure 1).

differing heights on Only one cam member, for example a knitting cam member 19 is provided for guiding the central feet inside a knitting system, whereas a knitting cam member 19, a tuck cam member 20 and two true-run cam members 21 are mounted on an immediately adjacent knitting system, according to the pattern to be knitted (Figure 2).

The mode of operation of thecircular knitting machine according to the invention will be explained briefly below.

As they enter the knitting system shown on the right of Figure 2, the latch needles are driven out, depending on the arrangement of the feet 18a; 18b; 18c; 18d on the needle shaft (i.e. according to use of the needles) and the use of the cam members 19; 20; 21 either for catching or knitting (for example the needles 1 which comprise pattern feet 18a or 18c) or continue running true (for example those needles 1 which comprise pattern feet 18b or 18d). On the other hand, all latch needles 1 on the immediately adjacent knitting systerr.

1 1 - 9 are driven out into the knitting position by member 15 by means of their central foot 17.

the cam The motion of the knocking-over and sinkers 5 in the direction of needle identical in each system.

loop-forming ejection is More specifically, the sinkers 5 are moved at each' knitting position, after the holding-down operation, against the doffing motion of the associated needles 1 and against the needle ejection direction by their cam 8.. Similarly, the motion of the holding-down sinkers-11 remains the same in each knitting machine. As the needles 1 begin to be driven out for laying the thread, the holding-down sinkers 11 are moved above the knocking-over and loopforming sinkers 5 between the latch needles 1 by the cam web 14 (Figure 3) and then return to their ineffective position after the needles 1 have been driven ut (Figure 4).

By allocating the knocking-over and- loop-forming function, according to the invention, to a first sinker which- is movable in the needle ejection direction and is mounted in the needle cylinder and allocating the holding-down function, according to the invention, to a second sinker which is movable at right angles to the needle and is mounted in a separate ring, according to the invention, it is possible to control the stitch forming elements in a functional manner using exact, closed cam curves.

is The division of the sinkers 5, 11 into the needle cylinder and into a ring 10 surrounding thhe needle cylinder 3 also effectively prevents excessive heating of the needle cylinder 3, reduces wear of the needle and sinker and allows an increase in the knitting speed. It goes without saying that the stitch size can be adjusted in known manner, for example by relative motion of the sinker cam 8 relative to the needle cam in the vertical direction and in the circumferential direction of the needle cylinder, whereby individual parts of these cams can be designed to be movable relative to one another and the cams in their entirety can be designed to be adjustable relative to one another.

1 1 p

Claims

- 11 CLAIMS

1. A circular knitting machine comprising a needle cylinder, a plurality of needles movable longitudinally on the cylinder to perform knitting, a plu.ality of knocking-over and loop-forming sinkers mounted on the needle cylinder between the needles, said sinkers being movable solely in the direction of movement of the needles, a ring around the needle cylinder for being driven therewith, and a--plura-1--ity of holding-down sinkers mounted on the ring, said holding-down sinkers being movable radially with respect to the needle cylinder.

2. A circular knitting machine according to claim 1, wherein the knockingover and loop-forming sinkers are guided in a separate upper part of the needle cylinder and are driven by a sinker cam arranged on a stationary holding ring.

3. A circular knitting machine according to claim 1 or 2, wherein the ring which is provided for mounting the holdi,ng-down sinkers is mounted by means of sliding - 12 bearings on a further stationary holding ring arranged above the sinker cam.

4. A circular knitting machine according to any preceding claim wherein the holding-down sinkers are each provided with two feet between which is provided a groove-shaped recess for co-operation with a cam web.

is

5. A circular knitting machine substantially as hereinbefore described with reference to the accompanying drawings.

6. A circular knitting machine, in particular a sinker top circular knitting machine of large diameter, with needles which are longitudinally movable in the grooves of the needle cylinder and means which are present at least intermittently between the needles for holdingdown, loop sinking or and knocking-over the stitches, characterised in that knocking-over and loopforming sinkers which are mounted in the needle cylinder and are movable only in the needle ejection direction are provided between the needles, and holding-down sinkers are arranged in the grooves provided on the periphery of a ring which surrounds the vp 13 needle cylinder at the level of its upper end and can be driven synchronously with the needle cylinder, the holding-down sinkers being movable radially with respect to the needle cylinder and only during ejection of the needle above the knocking-over and loop-formning sinkers between the needles.

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