GB2193977A - Cam arrangement for flat knitting-machine - Google Patents

Description

GB2193977A 1 SPECIFICATION ticularly in the case of multifeed flat

knitting machines.

Cam drive arrangement for a V-type flat In another known device, three lobes are bed knitting machine provided on the delivery cam element at a 70 distinct lateral spacing from one another, one This invention relates to a cam drive arrange- of them, preferably the central one, being ment for V-type flat bed knitting machines h1gher than the others. Although this guaran with symmetrically arranged knitting and trans- tees a reliable transfer operation in both car fer cam elements for both carriage and trans- riage directions, its disadvantage lies in the fer directions. 75 fact that the dimensions of a combined knitt- it is known to provide so-called transfer ing-transfer cam of this kind are increased, cams with a symmetrical delivery cam which which in turn means an increase in the mass comprises two lobes of the same height. Be- and the dimensions of the carriage.

low these lobes there are symmetrically ar- On the other hand, it is advisable to slightly ranged receiving cam elements which can be 80 increase the size of the loop which is to be switched in accordance with the carriage di- transferred, particularly in the case of close rection and which advance the receiving knit fabrics, so as to obtain a more reliable needles by their hooks in the area of the re- transfer operation.

cess in the delivery cam as far as the back of The variant with the three lobes is unsuit- the delivering needles and bring these needles 85 able for this, as the receiving needle must be into the loop receiving position in the area of quite a distance from the back of the deliver the respective trailing lobe. ing needle in the area of the highest lobe, The cams of the rear and front needle beds which means that this loop cannot be en- are formed in the same way, yet are switched larged. The needles were therefore fitted with so that a simultaneous transfer of loops from 90 an additional butt, and additional, separately the rear to the front and from the front to the adjustable loop-forming elements were associ rear is possible in both carriage directions. ated with this row of butts. This enabled This transfer device can be arranged in a loops of different sizes, according to the pat- manner which is known per se between two tern, to be produced and the larger loops to loop-forming elements, which are operative in 95 be transferred, also according to the pattern.

different directions and can include knitting However the necessary expense was unaccep and tucking clearing elements. The result is a tably high and a loss in output was an inevita combined knitting-transfer cam system which, ble consequence.

in addition to knitting in a typical three-way The aim of the invention is to further im- tehcnique, also permits the simultaneous 100 prove the quality of the knitted fabric, without transfer of loops in both transfer directions. increasing the cost of the machine or having However, it has become apparent that the to accept losses in output.

transfer operation may not always be carried One object of the invention is to enable a out with the required reliability with this de- reliable transfer operation to be carried out in vice. The height of both lobes is technologi- 105 each carriage direction and in each transfer cally determined by the transfer operation and direction-even when producing close-knit is subject to very limited tolerances. fabrics-on empty needles, while retaining the It may happen, particularly in the production double-lobed delivery cam, which is not of transfer patterns, when the draw-off switched in accordance with the direction, and mechanism does not sufficiently tension the 110 the small distance over which it extends in the loop which is to be transferred, that the lead- longitudinal direction of the needle beds.

ing lobe is not able to pull this loop into the According to the invention, there is provided shoulder of the delivering needle and thus po- a drive arrangement for a V-type flat bed sition it accurately. As a result, the head of knitting machine comprising symmetrically ar the loop which is to be transferred is either 115 ranged knitting and transfer cam elements for split by the latch or laid on the latch. Both both carriage and transfer directions, the cases give rise, in a known manner, to faults transfer cams consisting of a double-lobed de which make the knitted fabric unusable. livery cam, which can be switched indepen- Attempts have already been made to coun- dently of the carriage direction and two symter this disadvantage by using two lobes of a 120 metrically arranged receiving cams which can different height. However this restricted the activate a respective trailing receiving cam ele transfer for each cam to only one carriage ment, at least one pattern device per cam direction. This defect was remedied by con- arranged approximately in the area of the lead structing the delivery cam such that it could ing loop-forming element, each lobe on the be switched in accordance with the direction, 125 delivery cam having two steps thereon, the so that the leading lobe was always higher first step being arranged at the delivery level and could therefore ensure that the loop lay and the second step or peak being arranged securely in the shoulder. However this entails at the height required to spread the loop.

additional control measures, which result in This construction guarantees that the loop complicated and heavy knitting carriages, par- 130 which is on the delivering needle will be laid 2 GB2193977A 2 in the shoulder by the leading lobe. The re- for transfer vertically to the needle bed, is ceiving needle, which at this point is still re- provided above the knitting clearing element tracted, allows the knitted fabric to move up9. This delivery cam 12 is of symmetrical wards. The receiving needle is brought up to construction and has two lobes which have an the back of the delivering needle between the 70 externally stepped shape and are provided on lobes by the first step, which is known per both sides of a central gap 12a (see Figure 3).

se, of the receiving cam and thus holds down The outermost steps 12b and 12c are dis the knitted fabric. posed at the most favourable level for the Once the delivering needle has reached the transfer function. The peaks 12d, 12e, which trailing lobe, the width of the loop which is to 75 are adjacent the steps 12b, 12c on the inside be transferred is firstly effectively increased, thereof only extend over a small distance in thus decreasing the size of the adjacent, non the direction of movement of the cams, but tensioned loop. The delivering needle is sub- are high enough to draw threads out of the sequently returned to the lower step at the adjacent loops and increase the size of the delivery level. The loop which is to be deliv- 80 loop which is to be delivered accordingly. This ered is accurately positioned at that point and height of the peaks 12d, 12e also enables the presented to the receiving needle in a widened loop which is to be delivered to be safely and slack state, so that the latter can easily drawn into the shoulder 13a of the needle 13 receive it. It is ensured that the latches are with a rigid spreading spring. Receiving cams opened during transfer to empty needles. 85 14, 15 are arranged below the delivery cam There is also no possibility of the loops being 12 so that they can be switched. For instance laid on the latches. the trailing receiving cam 15 in Figure 1 is in A preferred embodiment of the invention engagement with the needle butts 13b which will now be described, by way of example reach the level of the crest- whereas the only, with reference to the accompanying 90 leading receiving cam 14 is retracted, so that drawings, in which: in this area the needle butts 13b, which until Figure 1 shows the needle cam of the front then were sunk in the needle bed, can be needle bed, raised out of the latter and brought into the Figure 2 shows the needles of both needle area of the cam elements.

beds in the spreading position directly before 95 Each of the receiving cam 14, 15 has a the receiving position, and stepped structure. The leading edge first lifts Figure 3 is a diagrammatic view of co-oper- the receiving needle out of the "crest level" ating delivery and receiving cams. position and into a position in which the nee- As can be seen from Figure 1, there is dle head of this needle begins to penetrate shown a V-type flat bed knitting machine pro- 100 the space between the shank and the spread vided with one or more needle cams per nee- ing spring of the delivering needle. The receiv dle bed which are arranged in a row parallel ing needle remains in this position. The sec to the needle bed and mounted on the car- ond rise of the receiving cam 14, 15 is in the riage. In principle, the needle cams of the rear area of the trailing step 12c, 12b of the deliv and front needle beds are identical. Each pair 105 ery cam 12. The receiving needle 13' is raised has a common axis of symmetry 1. at this rise to an extent such that its hook The rear needle cam, in relation to the loop- picks up the loop which is to be transferred forming zone, is formed and arranged in mir- and receives it when the two needles 13, 13' ror-inverted fashion. Pattern devices at 2, 3, 4 are subsequently taken into the knock-over are associated with each needle cam, pattern 110 position (see Figure 2).

devices 2 and 4 being disposed in the area of The operation of the illustrated device is as the leading loop-forming elements 5, 6 and follows:

pattern device 3 being disposed in the area of When the carriage shown in Figure 1 moves the axis of symmetry 1. from the left to the right the needles are se- The pattern devices 2, 3, 4 are formed so 115 lected by the pattern device 2 such that the that they lower the respective inactive needles butts 13b of the delivering needles 13 remain with their butts in the needle bed. The cam in the raceway; the needles are raised by the for the needle butts comprises the loop-form- tucking clearing element 7, the cam element ing elements 5, 6, which are arranged sym- 10 and the knitting clearing element 9 to such metrically in relation to the axis of symmetry 120 an extent that the delivery cam 12 can engage 1 and can be brought alternately into the op- and control these needles 13. The receiving erating position, two -fixed tucking clearing e le- needles 13' are initially sunk in the rear needle ments 7, 8, a symmetrical, rigid knitting clear- bed, eg by the pattern device 2'. They are ing element 9 and two cam elements 10, 11, moved out of the needle bed again by their which can alternately be switched in accor- 125 butts 13b under the action of a spring (not dance with the direction, for bridging the nee- shown) in the area of the retracted receiving dle track between the tucking clearing ele- cam 14' (see Figure 2). The following then ments 7, 8 and the knitting clearing element takes place in relation to the transfer of a 9. loop from the needle 13 to the needle 13'.

A delivery cam 12, which can be switched 130 The delivering needle 13 is raised by the 3 GB2193977A 3 delivery cam 12 far above the knitting level, carriage direction-even when producing firstly to the delivery level at the step 12b loose-knit fabrics-on empty needles, while and then by the peak 12d to the spreading maintaining the doubled-lobed delivery cam, level. The loop which is to be dleivered is which is not switched in accordance with the brought safely into the shoulder 13a of the 70 direction, and the small distance over which it delivering needle 13. The receiving needle 13' extends in the longitudinal direction of the is still level with the crest. Once it has needle beds.

crossed the peak 12d, the delivering needle

Claims (3)

13 is retracted slightly, so that the loop which CLAIMS was previously

formed by the needle 13 and 75 1. A drive arrangement for a V-type flat bed which has already been cast off is brought out knitting machine comprising symmetrically ar of the area of movement of the receiving neeranged knitting and transfer cam elements for dle 13'. both carriage and transfer directions, the As can be seen from Figure 2, the receiving transfer cams consisting of a double-lobed de- cam 15' of the rear needle bed now becomes 80 livery cam, which can be switched indepen- operative in the vicinity of the axis of symme- dently of the carriage direction and two sym- try 1 of the cam and in the area of the gap metrically arranged receiving cams which can 12a. It moves the needle 13' upwards until its activate a respective trailing receiving cam ele head projects slightly into the space between ment, at least one pattern device per cam the needle shank and the spreading spring. 85 arranged approximately in the area of the lead- The receiving needle 13' remains in this posi- ing loop-forming element, each lobe on the tion, even when the delivering needle 13 is delivery cam having two steps thereon, the raised by the peak 12e of the trailing lobe of first step being arranged at the delivery level the delivery cam 12. The delivering needle 13 and the second step or peak being arranged is thus able to expand the loop which is to be 90 at the height required to spread the loop.

delivered by a precisely defined amount, while

2. A drive arrangement for a V-type flat bed decreasing the size of the adjacent loop (see knitting machine substantially as herein de Figure 2). A device for widening these loops scribed with reference to the accompanying in accordance with the pattern need not be drawings.

used when transferring individual loops in ac- 95

3. A delivery cam substantially as herein de- cordance with the pattern. If all the loops of scribed with reference to Figures 1 and 3 of one needle bed are simultaneously transferred, the accompanying drawings and for use with as is necessary when transferring from a rib a drive arrangement as claimed in claim 1.

top to a plain fabric, a longer row must gener ally be knitted first. Published 1988 at The Patent Office, State House, 66/71 High Holborn, London WC 1 R 4TP. Further copies may be obtained from Once the loop which is to be delivered has The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD.

been spread, it is slackened by drawing the Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.

needle 13 back to the delivery level of the step 12c and is accurately positioned in front of the receiving needle 13'. The receiving nee dle 13' is then pushed by the second rise of the receiving cam 15' through the presented loop, so that its hook is disposed above the latter. A subsequent ' further rise as far as the tucking level does not change this situation in any way. Once the delivering and the receiving needles 13, 13' have been taken into the knock-over position at ' the loop-forming ele ment 6, the transfer operation is concluded in a manner which is known per se.

In the case of flat bed knitting machines, which have pattern devices at the rear and at the front needle bed in the area of the leading loop-forming element, a simultaneous transfer from the front to the rear and from the rear to the front is possible with a carriage movement in one direction. However in this case it is not possible to simultaneously select the opposite needles 13 and 13' in the rear and front nee dle beds as the delivering needles.

The described arrangement improves the quality of the knitted fabric, without increasing costs as the cam for the V-type flat bed knitt ing machine is formed whereby a reliable transfer operation can be carried out in each