GB2188650A - Flat weft knitting machines with improved thread guide control - Google Patents

Abstract

A flat weft knitting machine includes a thread guide bar (1), a thread guide carrier (4) held by frictional resistance on the thread guide bar, means for moving the thread guide bar longitudinally, and adjustable stops for abutting the carrier (4) to define limits of travel thereof upon longitudinal movement of the bar, the thread guide carrier including inclined guide surfaces (44, 45) first and second coupling keys (46, 47) having surfaces frictionally engaging the thread guide bar, and inclined surfaces slidably received on said inclined guide surfaces respectively and means resiliently biassing the keys (46, 47) into engagement with the bar. The biassing means may comprise a further key (48) urged by a compression spring (49) against the coupling keys. <IMAGE>

Description

SPECIFICATION Flat weft knitting machines with improved thread guide control The invention relates to thread guide control in a flat weft knitting machine. It is known to provide aflat weft knitting machine, comprising thread guide bars which can be driven in alternating directions, and at leastonethread guide perthread guide bar and knitting head, which is held byfrictional resistance on thethread guide bar by means ofthread guidecarrier and the length of traverse of which can be altered in both directions by adjustable limiting stops.

DE 854986 discloses a device in which the th read guide carriers are alternately held on the thread guide bar in a form-locking manner and, during the change in advance movement, by frictional resistance. The change-over in the type and method of drive is carried out by a control bar which bears cams and is controlled bythe limiting stops.

On account ofthe numerous components,these thread guide carriers have a substantial mass which limits the operating speed.

Afurther disadvantage lies in the fact that each thread guide carrier must execute a certain relative movementwith respect to the limiting stops in order to bring aboutthe change-over function. Small thread guide traverse lengths of two needle spacings, as required for intarsia and placing patterning, are not therefore possible.

It is also already known to secure the thread guide to a very light thread guide carrierwhich is held on the thread guide bar and carried along by "friction pads". The length of traverse is limited by limiting stops in each knitting head,- see DE 2027571.

The "friction pads" which are used in the latter generally consist of friction linings which are directly pressed against the thread guide bars in a resilient manner by leaf springs mounted in metallic housings.

This device enables the traverse of the thread guides to be of any length by adjusting the limiting stops in each knitting head. However, in orderto guarantee preise contact between the thread guides and the limiting stops - even in the case of widening in the row - each limiting stop has to provide with a catch which must be released again when move mentcommences. This necessitates the use of control devices which are very complex and take up a lot of space, particularly in the case of intarsia devices.

Attempts have been made to remedythisshortcoming bycouplingthethreadguidestothethread guide bar via a spring. However the result of this was thatthe length oftraverse ofthethread guide bar could only differfrom that of thethread guideto a very limited degree. This would lead to an unwarrantable expenditure for the thread guide bar drive, particularly in the case of intarsia thread guide systems.

An aim of the invention is to produce any desired kind offullyfashioned knitted pieces, provided with plating or intarsia designs, while keeping equipment costs to a minimum and without reducing the output ofthe flat weft knitting machine.

According to the present invention there is prov idedaflatweftknitting machineincludingathread guide bar, a thread guide carrier held by frictional resistance on the th read guide bar, means for moving the thread guide bar longitudinally, and adjustable stops for abutting the thread guide carrier to define limits of travel thereof upon longitudinal movementofthethread guide bar,thethreadguide carrier including guide surfaces inclined at respect ive obtuse and actute anglestothe longitudinal direction ofthe thread guide bar,first and second coupling keys having frictionally engaging the thread guide bar, and said keys having inclined surfaces slidably received on said inclined guide surfaces respectively, and means resiliently urging the keys to- wards the guide bar.

By means of the invention it is possible to provide a thread guide carrier for a stop-limiting control system which has a small mass, can be stopped without rebounding at each limiting stop and which can move over any desired distance relative to the thread guide bars without this giving rise to a harmful rise in temperature, a high degree of wear or unjustifiably high maintenance costs.

Conveniently, the thread guide carrier includes a base of plastics material and the guide surfaces subtend an angle of 15"to 25" with said guide bar direction.

According to an advantageous embodiment, the inclined surface are arranged in an inverted V-shape above the thread guide barandthecoupling keys disposed underneath are supported on either side of a compression spring.

A high degree of operational reliability when the thread guide starts to move is obtained in that the compression spring is arranged normal to the thread guide bar and is supported at the top at the thread guide carrier and at the bottom art a keywhosesur- faces project between the coupling keys.

In the case of intarsia thread guides it is part icularly advisable forthe thread guide carrierto com- prise a plurality of stop surfaces, disposed in a stag geredmannerata right angle to the direction of movement,forco-operating with the adjustable limiting stops.

If a plurality of th read guides are provided per knitting head and thread guide bar, as is required bythe nature of intarsia patterns, it is advisable to secure the limiting stopsforthis group ofthread guides to one carrier per limiting direction and to mountthe carrier on its control bar in such a way that it can be removed.

This carrier may also be provided with limiting stops for the thread guide carriers of a second thread guide bar, the thread guides ofwhich,togetherwith those of the first thread guide bar, produce a split structure.

The invention will now be explained byway of example with reference to drawings, in which: Figure lisa view of a thread guide carrierwith a partially cut away cover plate, Figure2 is a sectional view of a thread guide system viewed from the left, Figure 3 is a schematic view of a knitted piece with three knitted areas, Figure4is a plan view ofthe thread guide system of a knitting head with the upper control bars shown partially in section, and Figure 5is a view ofthe carrierforforthe limiting stops on the control bars.

The flatweft knitting machine is provided with thread guide bars 1,2, 3which, either individually or jointly, are driven to-and4ro by a gear unit which changes the stroke. The traverse of the thread guide bars 1,2,3 is only slightly longer than the respective actual operating width. Their law of motion is determined by cam plates and can be optimised such that the force of inertia are reduced to a minimum.

Thread guide carriers 4,5,6 are arranged so as to be displaceable on the thread guide bars 1,2,3. They are in each case provided with at least two stops 41, 42; 51,52; 61,62 which are disposed in a staggered mannerata rightangletothedirection of movement.

The thread guide carriers 4,5,6, which are preferably made of a plastic material, are provided with a guideway 43 for accommodating one of the thread guide bars 1.

Surfaces 44 and 45, which are inclined by approximately 15 - 20 , are disposed above this guideway 43 and in the opposite direction to the later. Surfaces 44 and 45 are arranged respectively obliquely and obtusely to the bar 1. Plastic coupling keys 46,47 are inserted between the surfaces 44,45 and the uppersurfaceofthethreadguidebar1.Afurtherkey 48, which is loaded bya compression spring 49, projects from above between the coupling keys 46,47.

The initial tension in the compression spring 49, which is supported at the base of the thread guide carrier, can be adjusted. The thread guide bars 1,2,3, the coupling keys46,47 and the key 48 are held and guided by a cover platewhich is detachablysecured to the base of the thread guide carrier 4.

This thread guide carrier 4, which is formed as described above, operates as follows: If the thread guide bar 1 is moved from the left to the right, the cou piing key 46 is pressed againstthe inclined surface 44 and the upper surface of the thread guide bar 1. Thethread guide carrier 4 is moved without any play to the right together with the thread guide bar 1.

If the stop 41 then comes into contact with a limiting stop 15, the coupling key 46 slides along the thread guide bar 1 while maintaining the frictional force. If the rebound from the limiting stop is greater than the frictional force of the coupling key 46, the key 48 immediately acts on the coupling key 47; the latter immediateiy acts as an additional brake.

This coupling key 47 functions until the thread guide carrier4 comes to rest against the limiting stop 15.

If thread guide bar 1 moves in the opposite direction,the coupling key 47 forms a frictional connection with the thread guide bar 1. On the other hand, the coupling key 46 acts as an additional brake upon the rebound from the limiting stop 11.

The advantage ofthis arrangement lies in the fact thatthe braking force between thethread guide bar 1 and the thread guide carrier4 need only be adapted to the required minimum accelrativeforces and the effects of the thread tension. For the special case absorbing the rebound - no special means are required.

Until now these special means took the form of a constantly operating higher brake force. This results in a considerable rise in temperature and a high de gree of wear. Or catch systems which engage in a resilient manner when the limiting stop is reached and have to be mechanically raised when movement commences in the opposite direction.

Figures 2 and 4 show an assembly of th read guide carriers, thread guide bars and control bars with limiting stops for a knitted piece with three different types of knitted areas A, B, C (Figure 3).

Pairs of control bars 7,9 and 8, 10 are arranged between the thread guide bars 1,2,3. Each ofthese can be individually adjusted by steps along the thread guide bars by spindles which are not shown.

The limiting stops 11 and 12forexternal contours ofthe knitted piece are arranged at the respective lower control bars9and 10.

The upper control bars7 and 8 are in each case arranged between the knitted aread A and B or B and Cforaspling knit edge.

These control bars 7,8 bear U-shaped carriers 13, 16 on which the limiting stops 14, l5forthethread guide carriers 4and 5 and the limiting stops 17, 18for the thread guide carriers 5 and 6, respectively are arranged.

Figure 5 shows the carrier 13 in detail on an enlar- ged scale. Grooves are precision milled in the carrier 13, and the limiting stops 14 and 15 are inserted in these grooves from above and screwed in place.

An adjusting element 20 is provided on a bearing 19, which is screwed and pinned to the control bar 7.

This adjusting element determines the exact position of the carrier in relation to the stitch forming elements. The carrier 13 is held in the vertical position by a kind of bayonet catch 21 on the control bar 7.

This construction makes it possible for the carrier to be prepared outside of the machine, mounted on the control bar and adjusted and secured with few manipulations. It is even possible for the carrier, togetherwith its two limiting stops, to be formed asa precision moulded part. The only safety measure required lies in making provision for adequately stable adjustment and guidance on the control bar.

The device shown in Figure 4for producing a knitted fabric according to Figure 3 operates as follows: The stroke of all the thread guide bars is from left to right. They carry along their thread guide carriers 4,5,6 without any play. Once they reach the stops 15, 18 or 11 and come to rest in the positions 4', 5,6', the thread guide bars 1,2,3 move a little further. As soon as these thread guide bars have also reached their end position, the control bars 7,8 are moved by one needle spacing in the opposite direction to form a split structure. The stitches are then formed. Once this operation has been completed, the thread guide bars 1,2,3 start to move in the opposite direction.

From the structural point ofviewthis device is simple. It also permits a high operating speed, while wear and maintenance costs are kept to a minimum.

It is even possible to increase its output if the length of traverse ofthethread guide bars is generallyadap- ted to the absolutly necessary maximum length of the thread guide traverse.

If multicoloured patterns are not desired, it is also possible to work with knitted sections of the same colour, and achieve high outputs with the flat weft knitting machine if the length ofthethread guide traverse is greatly reduced.

In the case of intarsia fabrics, where patterns are repeated several times side-by-side, limiting stops can be provided on one or all carriers 13, 16fora plurality of split knit edges extending parallel to one another. In this case the corresponding number of thread guide carriers must of course be mounted on the thread guide bars.

Claims (9)

1. Aflatweftknitting machine including athread guide bar, athread guide carrier held by frictional resistance on the thread guide bar, means for movingthethread guide bar longitudinally, and adjustable stops for abutting the thread guide carrier to define limits oftravel thereof upon longitudinal movement of the thread guide bar,thethread guide carrier including guide surfaces inclined at respective obtuse and acute anglestothe longitudinal direc tionofthethread guide bar, first and second coupling keys having surfaces frictionally engaging the thread guide bar, and said keys having inclined surfaces slidably received on said inclined guide surfaces respectively, and means resiliently urging the keystowardsthe guide bar.

2. A knitting machine according to claim 1 wherein said thread guide carrier includes a base made of plastics material.

3. A knitting machine according to claim 1 or2 wherein said inclined guide surfaces each subtend an angle of between 15"to 250with said guide bar direction.

4. A knitting machine according to any preceding claim wherein the guide surfaces in the thread guide carrier are arranged in an inverted V-shape above the thread guide bar, the coupling keys are mounted underneath the surfaces and said resilient means comprises a compression spring arranged between the keys.

5. Aknitting machine according to claim 4, wherein the compression spring is arranged normal to the thread guide bar and is supported at the top by the thread guide carrier and at the bottom by a key whose surfaces project between the coupling keys.

6. A knitting machine according to any preceding claim wherein thethread guide carrier includes a plurality of stop surfaces disposed transversely of the thread barfor co-operating with the adjustable stops.

7. Thread guide control forflatweft knitting machine, comprising thread guide bars which can be driven in opposite directions and at least one thread guide per thread guide bar and knitting head which is held by frictional resistance onthethread guide bars by means of thread guide carriers and the length of traverse of which can be altered in both directions by adjustable limiting stops, wherein the thread guide carrier consists of a plastic base which, at a distance from the thread guide bar, comprises two surfaces facing threthread guide bar and inclined by 15to 25 , and in that two coupling keys which extend in opposite directions of movement, are arranged be tweenthesesurfacesandthethread guide barand are held in such a way asto be resilient in the direction of the key tips.

8. Athread guide control according to claim 8 wherein a plurality of thread guide carriers are provided in each knitting head per thread guide bar, that the limiting stopsforthisgroupofthread guidecarriers are secured per limiting direction and that the carrier is mounted on its control bar in such a way that it can be removed.

9. Aflatweftknitting machine substantially as hereinbefore described with reference to the accompanying drawings.