GB2038376A

GB2038376A - Sinker for Forming Knitted Terry Fabric on Single Cylinder Circular Knitting Machines

Info

Publication number: GB2038376A
Application number: GB7939956A
Authority: GB
Original assignee: IRMAC SpA
Current assignee: IRMAC SpA
Priority date: 1978-12-27
Filing date: 1979-11-19
Publication date: 1980-07-23
Also published as: FR2445404A3; ES246861U; IT7823645V0; GB2038376B; CH636914A5; FR2445404B3; ES246861Y; DE7932166U1

Abstract

Sinkers (2) for use in forming terry fabric are each mounted associated with a depressing sinker (1) in a single cylinder circular knitting machine e.g. a cylinder and dial machine. In order to make the formation of the terry fabric more reliable, regular and uniform the sinker (2) is provided, at the rear of its hook (6), with a support indentation (7) for the yarn which is to form the elongated loop of the terry fabric and below the hook (6) there is provided a substantially vertical surface (8) for separating the yarn which forms normal loops from the yarn which forms elongated loops. The said vertical surface (8) is followed by a surface (9) which is at a lower level then the depressing surface (13) of the depressing sinker (1). <IMAGE>

Description

SPECIFICATION Special Sinker for Forming Knitted Terry Fabric on Single Cylinder Circular Knitting Machines This invention relates to a special sinker for forming knitted terry fabric on single cylinder circular machines for knitwear in general, and for hose in particular.

Terry fabric is obtained by interlacing two yarns, one of which forms normal loops and the other forms much longer loops than normal.

When the old fabric is pressed down on to the new loops in the formation of the knitted fabric, it becomes interlaced both with the normal loops and with the long loops, and these latter form projecting ringlets on the reverse side of the fabric, to give it a terry appearance.

To obtain these loops which are longer than normal loops, special sinkers of two types can be used, namely sinkers which besides forming the long loops also act as normal depressing sinkers, or special sinkers which are used coupled with the depressing sinkers, and serve only for forming the long loops.

The invention relates to this latter type of special sinker, the purpose of which is only to form the long loops for the terry fabric.

One of the problems encountered in forming terry fabric is to keep separate the two yarns which are used for forming the normal loops and the long loops respectively. In this respect, if this separation is not ensured during each new loop formation, irregularities occur in the terry fabric, which disturb the appearance of the fabric produced. A further drawback which arises particularly when using two coupled sinkers (i.e.

separate sinkers for pressing down and for forming the long loops for the terry fabric) is that each pair of sinkers inserted between consecutive cylinder needles has a rather large width, with consequent extensive contact with the yarn, the sliding of which becomes hindered during loop withdrawal.

The object of the invention is to obviate the aforesaid drawbacks and to make the formations of the terry fabric more reliable, regular and uniform, so substantially improving the appearance of the fabric obtained.

This object is attained, according to the invention, by a special sinker for forming terry fabric, to be mounted coupled with a depressing sinker in a radial slot of an outer and inner ring rigid with the needle cylinder of a single cylinder circular knitting machine, said special sinker being constituted by a profiled laminar member comprising a base for resting on the bottom of said slot, a seat bounded by a butt for receiving the control cams which act on said butt for providing the radial centripetal and centrifugal movements in said slot, a lower appendix, a recess overlying said appendix and with its upper edge resting on the inner ring, and an upper hook projecting in the same direction as said appendix, wherein to the rear of said projecting hook there is provided a support indentation for the yarn which is to form the elongated loop of the terry fabric, below the hook there is provided a substantially vertical surface for separating the yarn which forms the normal loops from the yarn which forms the long loops, and said substantially vertical surface is followed by a surface which bounds that pat of the member overlying said recess, said surface being at a lower level than the depressing surface of the depressing sinker.

In one particular embodiment, the surface bounding that part of the sinker member overlying the recess for guiding and support on the inner ring can be slightly inclined in an upward direction towards the front end while remaining lower than the depressing surface.

Furthermore, the distance between the rear edge of the butt and the point of the sinker hook, in relation to the control cams acting on the butt, is such that when the sinker is in its position of maximum radial displacement in the centripetal direction, the upper hook is at a distance from the centre of the needle cylinder which is less than the radius of the circumference on which the cylinder needles are situated, and greater than the maximum radius of any possible horizontal needle support plate provided on the machine.

The invention is described in greater detail hereinafter with reference to the accompanying drawings, in which: Figure 1 shows the profile of a special sinker embodying to the invention, Figure 2 is a section through the upper part of the needle cylinder of a circular knitting machine, showing the rings in which the sinkers are mounted, Figure 3 is a plan view of the rings, in the slots of which are mounted the sinkers (partial view), Figures 4 to 7 are diagrammatic illustrations of some stages in the formation of terry fabric using the special sinkers according to the invention, and Figure 8 is a diagrammatic view, in the direction of the arrow X of Figure 5, of one stage in the formation of the terry fabric.

As can be clearly seen from Figure 1, the special sinker 2 embodying the invention, for forming long loops, is constituted by a profiled laminar member with a lower support and slide base 3, a butt 5 which bounds a seat 4 for receiving the control cams which act on the butt 5, an upper projecting hook 6 behind which is an indentation 7, a substantially vertical surface 8 below the hook 6, and a surface 9 which bounds a front part of the member 2 overlying a recess 10 which in its turn overlies a projection 11.

Figure 1 also shows, with dashed lines, the profile of a depressing sinker 1 in order to indicate the difference in the profiles of the two sinkers which are to be coupled.

As can be seen, the hook 12 of the depressing sinker 1 is at a lower level than the hook 6 of the special sinker 2, while the depressing surface 13 of the sinker 1 is higher than the surface 9 of the sinker 2, and is inclined downwards towards the front end. In addition, the sinker 1 comprises a butt 14 which enables it to be controlled and moved, as necessary, separately from the special sinker 2.

With reference to Figures 2 and 3, it can be seen that the sinkers 1 and 2 are mounted in pairs in radial slots 1 5 provided in the outer ring 16 and inner ring 1 7 rigid with the top of the needle cylinder 18 which in known manner carries the latch needles 1 9. Fixed strips 20 (see Figure 3) are mounted in the slots 1 5 of the outer ring 16 in order to keep the two coupled sinkers 1 and 2 inserted into each slot separate, and thus prevent their mutual contact.

A plate 22 carrying horizontal needles 21 can if required be mounted on the cylinder 1 8 coaxially therewith, for the reasons well known to the art.

The dimensions of the special sinker 2 must obey the following requirements.

Figure 1 shows the distance A between the rear edge of the butt 5 and the point of the hook 6.

Taking account of the arrangement of the cams acting on the butt 5, the distance determines the radial distance of the hook 6 from the centre of the cylinder 1 8 during the various stages in the manufacture of the terry fabric. In its position of maximum advancement in the centripetal direction (towards the centre), the sinker 2 for forming the long loops must have its hook 6 at a distance from the centre of the cylinder 1 8 which is less than the radius of the circumference on which the needles 1 9 lie (see Figure 1).On the other hand, if the machine is provided with a plate 22 for horizontal needles 21, the height of which from the depressing surface is determined by the dimensional characteristics of the fabric to be manufactured, it is not possible to operate the sinker below this plate, as the height of its hook 6 (due to the height of the plate) from the depressing surface (the distance on which the length of the terry loops depends) would be insufficient for forming a dimensionally correct terry fabcic, and thus in order to make the height of the hook 6 independent of the height of the plate 22, the minimum radial distance from the centre to which the hook 6 of the plate 2 can move during manufacture must be greater than the maximum radius of the plate 22.With reference to Figures 4 to 8, a description is given hereinafter of the various successive stages in the formation of a long loop for terry fabric, in order to better understand the operation of the special sinkers 2 according to the invention. It has already been stated that the terry fabric is formed by interlacing two yarns, namely those indicated by 24 and 25 respectively, which are fed by a thread guide 25, and of which the yarn 24 serves for forming normal loops, whereas the higher yarn 25 serves for forming the long loops of the terry fabric.

Figure 4 shows the rest position in which both the sinkers 1 and 2 are advanced in the centripetal direction, the needle 1 9 having its latch open, with the last loops constructed by the yarns 24 and 1 5 passing on to the latch and being held taut by the sinkers 1 and 2.

The needle 19 then rises (Figure 5) and the old fabric is unloaded, to fall from the latch. After reaching its maximum height, the needle descends and takes up the two threads 24 and 25. At the same time, the two sinkers are moved in a centrifugal radial direction (outwards), the depressing sinker 1 in order to present a free depressing surface 13, and the sinker 2 so as to disengage from the trajectory of the yarn 24 so as not to take both the yarns 24 and 25 with its hook 6. The sinker 2 is then moved forward alone in the centrifugal direction (Figures 6 and 8) so that its hook 6 penetrates between the two yarns 24 and 25, and so that the yarn 25 can rest in its indentation 7.

It should be noted that during this stage the specific function of the substantially vertical front surface 8 of the sinker 2 is to keep the yarn 24 properly separate from the yarn 25 by thrusting the former forwards. This allows reliable and regular formation of the long loop for the terry fabric, so improving the appearance of the fabric produced.

It should also be noted that the depressing surface where the yarn 24 stops so as not to follow the needle 19 in its descent for loop withdrawal is formed only by the surface 1 3 of the sinker 1, as the corresponding surface 9 of the special sinker 2 is lower than the surface 13. This allows threads which wind about the sinkers and needles to rub against smaller surface areas, and thus slide more easily.

Finally, Figure 7 shows how the depressing sinker 1 is moved forward in the centripetal direction, and the needle 1 9 after reaching its lowest position for loop withdrawal begins to rise in order to return to the position of Figure 4.

Provided the particular characteristics of the special sinker 2 are retained with regard to the hook 6 with the indentation 7 for supporting the yarn in order to form the long loop, the front surface 8 for keeping the two fed yarns properly separated, and the surface 9 lower than the depressing surface, the remaining profile of the sinker can be modified according to the requirements of the machine on which the sinker is mounted.

Finaliy, it should be noted that the surface 9 of the sinker 2, which is shown parallel to the support base 3, can also be inclined upwards towards the front end, i.e. in the opposite direction to the inclination of the depressing surface 13 of the depressing sinker 1. In this manner, the difference between the two surfaces can be further accentuated, so as not to allow any possibility of the yarn 24 also sliding on the surface 9 of the special sinker 2.

Claims

1. A special sinker for forming terry fabric, to be mounted coupled with a depressing sinker in a radial slot of an outer and inner ring rigid with the needle cylinder of a single cylinder circular knitting machine, said special sinker being constituted by a flat profiled member comprising a base for resting on the bottom of said slot, a seat bounded by a butt for receiving control cams, which act on said butt for providing the radial centripetal and centrifugal movements in said slot, a lower projection, a recess overlying said projection with its upper edge resting on the inner ring, and an upper hook projecting in the same direction as said projection, wherein to the rear of said hook there is a support indentation for the yarn which is to form the elongated loop of the terry fabric, below the hook there is provided a substantially vertical surface for separating the yarn which forms the normal loops from the yarn which forms the long loops, and said substantially vertical surface is followed by a surface which bounds that part of the member overlying said recess, said being in use at a lower level than the depressing surface of the associated depressing sinker.

2. A special sinker as claim in claim 1, wherein the surface bounding that part of the member overlying the recess for guiding and support on the inner ring is inclined in an upward direction towards the front end.

3. A special sinker as claimed in claim 1, wherein the distance between the rear edge of the butt and the point of the hook, in relation to the control cams acting on the butt, is such that when the sinker is in its position of maximum radial displacement in the centripetal direction, its hook is at a distance from the centre of the needle cylinder which is a less than the radius of the circumference on which the cylinder needles are situated, and greater than the maximum radius of any possible horizontal needle support plate of the circular machine.

4. A special sinker substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.