GB2139251A

GB2139251A - A thread feed mechanism for a hosiery knitting machine

Info

Publication number: GB2139251A
Application number: GB08406510A
Authority: GB
Inventors: Siegfried Nurk
Original assignee: Sipra Patententwicklungs und Beteiligungs GmbH
Current assignee: Sipra Patententwicklungs und Beteiligungs GmbH
Priority date: 1983-05-03
Filing date: 1984-03-13
Publication date: 1984-11-07
Also published as: CH662833A5; JPS6329025B2; DE3316078A1; JPS59204952A; GB2139251B; GB8406510D0

Abstract

Thread compensating mechanisms 21 include thread guide eyelets 31 which are movable vertically to form thread loops 37. Each eyelet 31 is mounted on a sliding body 32 which is freely movable on a vertical guideway 34. Each eyelet 31 cooperates with a thread brake 25, the braking force of which is controlled as a function of the vertical position of the respective eyelet 31. The thread brakes 25 may consist of electromagnetically controllable ball brakes in which case control of the braking force of each is effected by way of electrical sensors 35 arranged on the respective guideways 34. The mechanisms are of use, for example, on carriage reversal in a flat machine. <IMAGE>

Description

SPECIFICATION A thread feed mechanism for a knitting and hosiery machine This invention relates to a thread feed mechanism for a knitting and hosiery machine which serves to guide thread from a thread store to a stitch formation area by way of a thread guide eyelet which is adjustable so as to permit formation of a thread loop, and by way of a thread brake.

In flat knitting machines, in circular knitting machines with pendulum operation, and also in other stitch-forming machines, when there is a reversal of the working direction, there is a corresponding restoring movement of thread guides. Also when there is a knitting width transition or a reversal of the direction of rotation of the machine, the resulting thread tension changes are usually compensated for by spring-loaded swingable thread guide eyelet carriers so as to maintain a uniform thread tension. In the case of flat knitting machines, mechanisms for controlling the thread guide paths as a function of the working width are known. Such mechanisms are constructionally complex and expensive and require a complicated control.In flat knitting machines it is also known (Swiss Patent No. 535 309) to provide a thread loop for thread tension compensation by means of a thread guide eyelet which is driven in a straight line. The control of such a driven eyelet is, however, complex and expensive and this mechanism is not well suited for sensitive and rapid thread tension compensation.

An object of the invention is provision of a thread feed mechanism of the kind mentioned at the beginning hereof in which even relatively long portions of thread can be drawn back for the purposes of thread tension regulation without disturbance of the mechanism and without requiring a complicated control.

With this object in view, the present invention provides a thread feed mechanism having the features mentioned at the beginning hereof, but characterised in that the adjustable thread guide eyelet is arranged on a sliding body which is freely movable on a vertical guideway and exerts a thread tensile stress, and the thread brake,which is connected in front of the eyelet in the thread draw-off direction, is controlled as a function of the position of the sliding body on the guideway.

The control of the thread brake can be effected by means of an electrical sensor which is arranged on the guideway of the sliding body and can be actuated by the sliding body.

In the feed mechanism in accordance with the invention, positive drive of the adjustable thread guide eyelet is abolished. The thread feed mechanism with the thread compensation area is, in the case of a flat knitting machine, preferably arranged fairly compactly (so as to save space) at both ends of the machine. The guideways for several adjustable thread guide eyelets can be situated at both ends of the machine in the region between the needle bed and the floor. If necessary, a thread compensation loop can be formed here which is longer than double the distance between the needle beds and the floor, by the thread being guided by way of several vertically adjustable guide eyelets. A mechanism for controlling the thread guide paths as a function of the knitting width is superfluous.When the thread feed mechanism of the invention is located as just mentioned there is the further advantage that the thread monitors, which are normally arranged above the needle beds such that dust and bits of fluff therefrom can drop down into the stitch formation region, can be coupled with the thread compensation area which is arranged underneath the stitch formation region. Preferably the guideway for the sliding body of the adjustable thread guide eyelet has a sensor at its lower end which controls the machine drive and which, in the event of a thread break, is influenced by the sliding body falling down.

Advantageously the thread brake consists of a ball brake having a brake ball which can be influenced electro-magnetically. In the absence of a thread loop, i.e. when the adjustable thread guide eyelet is in its upper position, energisation of the thread brake is interrupted or reduced by way of the sensor which is influenced by the thread guide eyelet or the sliding body thereof respectively, so that thread can be drawn through the thread brake in an unhindered manner. However, as soon as a thread pull from the stitch formation location is not forthcoming, the adjustable thread guide eyelet will drop down, so that by way of the sensor the associated thread brake is energised and the drawing of further thread through the thread brake is prevented.In order to initiate immediate formation of a thread compensating loop upon an interruption of the tensile loading of the thread, a spring is preferably arranged at the upper end of the guideway to bias the sliding body (and thus the respective eyelet) in the downward direction. The spring triggers the downwards falling movement of the sliding body and, when the sliding body ascends once more, it acts in a damping manner. The sliding body may be loaded with exchangeable weights but this is not essential. Thus, no heavy sliding body needs to be provided. Indeed the thread feed mechanism in accordance with the invention will work with relatively slight thread tension. Moreover, the braking force of the ball brake can be coordinated with the falling force of the sliding body.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows a schematic front elevation of a flat knitting machine provided with one embodiment of the thread feed mechanism of the invention; Fig. 2 shows a front view of the same flat knitting machine in the direction of the arrow II in Fig. 1; and Fig. 3 is an enlarged partial representation of the thread guide elements shown in Fig. 2.

Figs.1 and 2 show a flat knitting machine have a thread feed mechanism in accordance with the invention. This flat knitting machine comprises support feed 10, needle beds 11 and 12, and a machine carriage 14 which is movable on guide rods 1 3. A bobbin table 1 5 with yarn bobbins 1 6 placed thereon is mounted on the rear of the machine, and a carrier 1 7 for thread guide eyelets 1 8 and for supply devices 1 9 is arranged above the bobbin table 15.

Fig. 1 additionally shows a shaped piece of knitting 20 which is being produced on the machine. In Fig. 1 thread compensating mechanisms 21 are also clearly shown on both end faces of the flat knitting machine.

Threads 22 drawn off from the yarn bobbins 1 6 are supplied to these mechanisms 21 and these threads are fed therefrom, from the ends of the needle beds to the thread guides 40 which are, in customary manner, moved back and forth by the machine carriage 14.

Lateral thred guide elements 23 limit the maximum working stroke of the thread guides 40. The thread section between the respective thread guide elements 23 and the start of the working region (the knitting edge) is, upon reversal of the working direction of the thread guides 40, compensated for by the thread compensating mechanism 21 until the thread guides 40 have again reached the working region of the needles.

Figs. 2 and 3 show in greater detail the construction of one of the two thread compensating mechanisms 21. The thread compensating mechanism 21 is designed, for example, for six threads 22/1 to 22/6 which are all shown in Fig. 3. The threads 22/l to 22/6 all pass by way of a thread guide eyelet 24 of the supply device 19, which includes a storage drum as shown in Fig. 2, to respective ball brakes 25, one of which is shown in section in Fig. 3. The brake balls 26 of all six ball brakes 25 are each under the influence of a respective electro-magnet coil 28 which is supplied by way of current leads 27 and by means of which the braking force and braking time of each ball brake 25 is controlled. In the thread draw-off direction behind each ball brake 25, each thread is initially passed through a rigid thread guide eyelet 29.Arranged between this eyelet 29 and a second rigid thread guide eyelet 30 is an adjustable thread guide eyelet 31. The adjustable thread guide eyelet 31 is connected to a sliding body 32, shown in Fig. 3, which is mounted so as to be freely displaceable in a vertical guideway in the form of a guide tube 34. The guide tube 34 is provided with an exit slit 33 for the thread guide eyelet 31. Each thread compensating mechanism 21 thus has six such guide tubes 34, each for one adjustable thread guide eyelet 31. The tubes 34 are divided into two groups of three and they extend downwards as far as the level of the floor. The number of guide tubes, their arrangement and their height above the floor, is, of course arbitrary.

As indicated in Fig, 3, an electrical sensor 32 is arranged in the upper end region of each guide tube 34. Each sensor 35 is connected, by way of a connection cable 36, to an electrical control mechanism (not shown in more detail), to which the adjustable ball brakes 22 are also connected. The sensors 35 are influenced by the sliding bodies 32 of the adjustable thread guide eyelets 31 when these eyelets 31 approved their upper end position between the stationary neighbouring thread guide eyelets 29 and 30. In Fig. 3, on the right-hand side, the adjustable thread guide eyelet 31 is shown in its upper end position.In this position, the associated thread brake 25 is released, by way of the electrical control mechanism, in other words the respective electro-magnet coil 28 is switched off or is switched to a braking extent which is adjustable by means of a regulator 41, shown in Figs. 2 and 3.

Upon reversal of the carriage 14 or threadguide restoring motion, as soon as the thread draw-off tension decreases and the thread 22 becomes slack, the adjustable thread guide eyelet 31 drops downwards under the weight of its sliding body 32 and forms a thread loop 37 between the eyelets 29, 30. A helical compression spring 38 is arranged in the guide tube 34. In the upper end position of the thread guide eyelet 31, this spring 38 exerts a bias on the sliding body 32 and thus, upon a decrease in thread tensile stress, immediately triggers downwards motion of the adjustable thread guide eyelet 31. The spring also acts as a damping member when the loop is used up and the thread guide eyelet 31 moves upwards.

As soon as the sliding body 32 drops downwards out of the upper end position, the ball brake 25 is energised by way of the sensor 35 and the brake ball 26 is pressed by the electromagnet coil 28 against the ball seat, so that no further thread 22 can be drawn off and the thread loop 37 is formed exclusively from thread fetched back from the thread guide 40.

If a thread break occurs, the adjustable thread guide eyelet 31 drops down to the lower end of the guide tube 34. At the lower end of each guide tube there is a further electrical sensor 39, as indicated in Fig. 1, which replaced the thread monitors usuaily arranged above the needle beds and switchesoff the machine.

The thread compensating mechanism 21 designed in accordance with the invention allows the formation of large thread loops 37 by operation of low-weight adjustable thread guide eyelets 31, so that work can be carried out with only slight thread tensions.

If necessary, a thread 22 can also be guided by way of two adjustable thread guide eyelets 31, so that it can be placed into two compensating thread loops 37. The guide tubes 34 can also be arranged in a separate frame beside the machine.

Claims

1. A thread feed mechanism for a knitting and hosiery machine which serves to guide thread from a thread store to a stitch formation area by way of a thread guide eyelet, which is adjustable so as to permit formation of a thread loop, and by way of a thread brake, characterised in that the adjustable thread guide eyelet is arranged on a sliding body which is freely movable on a vertical guideway and exerts a thread tensile stress, and the thread brake, which is connected in front of the eyelet in the thread draw-off direction, is controlled as a function of the position of the sliding body on the guideway.

2. A thread feed mechanism as claimed in claim 1, characterised in that an electrical sensor which is capable of being actuated by the sliding body is arranged on the guideway.

3. A thread feed mechanism as claimed in claim 1 or 2 characterised in that a sensor which controls the thread brake is disposed in the upper region of the guideway.

4. A thread feed mechanism as claimed in claim 1, 2 or 3, characterised in that a sensor which controls the machine drive is disposed at the lower end of the guideway.

5. A thread feed mechanism as claimed in any preceding claim, characterised in that a spring is arranged at the upper end of the guideway, which spring biasses the sliding body of the adjustable thread guide eyelet in a downward direction and damp the sliding body in an upward direction.

6. A thread feed mechanism as claimed in any preceding claim, characterised in that the thread brake comprises a ball brake having a brake ball which can be influenced electromagnetically.

7. A thread feed mechanism as claimed in any preceding claim and adapted for flat knitting machines. characterised in that respective vertical guideways of adjustable thread guide eyelets for several threads are arranged on a machine frame at the ends of needle beds in the region between the needle beds and the floor.

8. A thread feed mechanism for a knitting and hosiery machine substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.