EP0078720B2 - Method of knitting stripes or repeating crossbands on a multisystem circular knitting machine, apparatus therefor and products obtained - Google Patents

Abstract

1. A process for the production of stripes or repeating crossbands on a circular knitting machine comprising at least two knitting heads fed with yarns having different appearances, characterized in that, by means of a respective device for selection of the needles associated with each knitting head, each band is started by changing the yarn in use by controlling, on the one hand, the selection device associated with the knitting head whose yarn is already in use in such a way that the needles cease from then on to gather the yarn at this knitting head and by controlling, on the other hand, the selection device associated with the other knitting head whose yarn is not yet in use in such a way that the needles from then on gather the yarn at this knitting head ; the complementary operations being effected at the end of a subsequent band after a whole multiple of revolutions of the cylinders of the machine.

Description

The invention relates to a hosiery article having repetitive transverse stripes or bands and to a method of knitting such an article on a circular knitting machine.

It is known from document US-A-618 017 to knit such an article having transverse stripes obtained by changing threads by a combined and synchronized maneuver of presentation of a thrower bringing the new knitting yarn and withdrawal of the thrower from the old thread.

With such a method, there is necessarily an overlap of the two different threads on a few needles, on which the two threads are knitted. This results in increased stresses and a risk of breakage of these wires at the location of the overlap, and special measures must be taken to avoid such breakage. In addition, the appearance of knitting is unsightly because the change of thread leads to an increase in thickness on a few needles and to an irregular mixture of threads of different aspects on the few needles on which the overlap takes place.

Such a process can only be implemented on looms with a single cylinder because the thread throwers must be able to retract radially towards the inside of the cylinder in order to selectively put the threads of different aspects in and out of the vertical path of the needles.

On circular looms with two needle beds, namely a lower needle cylinder and an upper needle bed which can be either a cylinder or a tray, it is common to use the striping system comprising throwers of threads radially retractable towards the outside of the lower cylinder, and appropriate scissors which are activated at very precise times, one to drop the end of the new thread which must be knitted, the other to cut and pinch the end of the thread which is withdrawn.

This technique also necessarily leads to the formation of double stitches by simultaneous knitting of the two different threads on a few needles, but in addition the free ends of these two threads are then uncontrolled and are placed in the needles in any positions, thus risking to emerge from knitting in an unsightly way.

On the other hand, this somewhat delicate yarn change operation requires constant control and maintenance of the yarn cutter scissors and requires a slowing down of the knitting speed during the changes.

The invention aims to solve the problem of knitting on circular knitting machines with single or double needle bed articles with repetitive stripes or stripes, the aesthetic appearance of which is improved by the absence of double stitches and of cutting of the yarns. each change of thread.

According to the invention, this problem is solved by means of the method defined in claims 1 to 3, which makes it possible to obtain strips having any height in the direction of the mesh columns and has the advantage that, despite the absence of double mesh, there is a continuous mesh of threads at the transition points. In addition, the yarn put out of work is not cut and simply extends on the wrong side of the knit to the next area of the knit where it is taken up to work again.

By generalizing the definition of the process, it can be said that with a loom comprising a number of scraps equal to k.n., the invention makes it possible to knit n strips of different appearance, with for each strip, k scraps working at the same time.

We can also provide a change of the thread thrower associated with the same drop to increase the capacity of this drop in the use of threads of different appearance.

The invention also extends to a hosiery article as defined in claims 4 and 5.

The description which follows with reference to the appended drawing, given by way of nonlimiting example, will make it clear how the invention can be implemented, the particular features which emerge both from the drawing and from the text of course forming part of said invention.

Figure 1 is a diagram showing a few rows of meshes on a large scale and intended to explain the principle of the invention. Figure 2 illustrates a variant. FIG. 3 represents the evolution of the yarn (s) of the scraps canceled while knitting takes place on another scribe. Figure 4 is a schematic view of an embodiment of the control of needle selection cams, adaptable for example on circular double cylinder loom without Jacquard system. The assembly of FIGS. 5a to 5d shows the lining of the needle plates on the lower cylinder of the loom for controlling the selection cams according to the arrangement illustrated in FIG. 4. These figures bear legends which facilitate their understanding. . Figure 6 is a schematic perspective view of a circular loom equipped with a thread thrower change device.

• - un fil "f1" d'une certaine couleur réalisant la rayure ou le bandeau "R1" est alimenté à la première chute du métier ;
• - un fil "f2" d'une autre couleur réalisant la rayure ou le bandeau "R2" est alimenté à la deuxième chute.

Figure 1 shows, in jersey context, in terms of principle, a succession of rows of stitches, at the precise location where the thread changes take place:

• - a wire "f1" of a certain color producing the stripe or the strip "R1" is supplied at the first fall of the loom;
• - a "f2" thread of another color producing the stripe or the "R2" strip is supplied at the second fall.

We can, of course, imagine a third wire again, making another stripe and supplied with the third fall, etc.

At the first fall where knitting of the strip or stripe "R1" begins, the device for selecting needles associated with this first fall starts the rise of all the needles starting with the needle of the column of meshes "M", then brings them in complete ascent so that all the needles pick the wire "F1", the picking being followed normal slaughter. (To fully understand the design, it must be remembered that knitting descends in the loom, as the ferret is made, so that the rows of stitches made first are at the bottom of Figure 1).

During the entire knitting of the stripe "R1" (with any number of rows) the other following falls are canceled, so that the needles appear at these falls in the fully slaughtered position, so that they do not do not pick the respective threads, the corresponding throwers of which always remain in the working position.

To stop the scratch "R1" after a whole number of cylinder turns, the device for selecting the first fall prevents the ascent, towards the wire picking position, of all the needles which follow the last needle to be picked in the column of meshes "N". Consequently, the following needles will pass to the first fall in the low position of complete slaughter, without further picking the thread "f1", the thrower of which however remains fixed in position and ready for work.

To continue with the knitting of the stripe "R2", the needles, which all come to stop the picking at the first fall, are now presented to the device for selecting the second fall, including the cam, which has just been placed. in working position, begins their ascent, always starting with the needle of the column of meshes "M", then the needles are brought in full ascent to pick the wire "f2" there, culling followed by a normal felling.

During all the knitting of the strip or stripe "R2", all the other falls are canceled, so that all the needles are there in the low position of complete felling, without picking the thread there.

The stripe "R2" is stopped on the needle of the mesh column "N", as described above for the stripe "R1".

We can chain in the same way with any other wire supplied at the third fall if there is one, and so on until the n ^th fall.

As the threads are not cut when changing from one stripe to another, a float thread "ff 'exists on the reverse side of the knitted fabric, connecting two stripes or bands of the same color in the longitudinal direction.

The last needle having meshed (on the column of meshes "N") drives this thread in its displacement on the circumference of the cylinder, without there meeting any obstacle since all the needles knit in jersey and are in low position d complete slaughter.

The wire, thus entrained, (f2, figure 3), therefore sweeps the surface above the lower cylinder (or the free space between upper and lower cylinders, if it is a double cylinder loom) by forming a secant of increasing length from the eyelet of the j2 j2 to the point diametrically opposite to the fall which has just been canceled. For the second half of the cylinder rotation, the secant of the wire decreasing, it is necessary to absorb the excess wire at each revolution of the cylinder by recalling it in the opposite direction through the thrower. An additional "fisherman" device P (see figure 3) can be used for this, installed at each fall. This device, similar to that which manufacturers build on knitting machines for footwear, for knitting heels and toes in reciprocating motion, or on straight knitters to absorb excess yarn after each end of travel of the carriage, comprises a wire guide P1 mounted on a lever P pivoting about an axis P2 and returned by a spring P3. The lever P pulled by the spring compensates for the slack that occurs in the wire and keeps it taut.

The selection of the needles to knit at one or the other fall is effected by the action of a movable cam disposed at each of the falls and acting on the knitting heels of the plates.

The placing in the operating position and the withdrawal of these cams can be controlled by a set of levers receiving their movements from eccentrics or from cams rotating in synchronism with the movement of the loom, or by an electro-mechanical control.

On a Jacquard circular knitting loom, the selection of needles to pick the thread at one or the other fall is made from drawing drums and appropriate selectors.

On a double cylinder circular loom without the Jacquard system, the needle selection device is composed of two cams, movable in the radial direction and able to approach or move away from the needle cylinder.

One of the cams (which will be called "picking lock V1"), when it is brought closer to the cylinder, initiates the ascent of the needles to allow picking of the wire; the entry into function of this cam is done on the medium knitting heels "Tt".

The other cam (which will be called "cancellation lock V2"), when it is brought closer to the cylinder, initiates the cancellation of the fall by lowering all the needles to the non-picking position; the entry into function of this cam is on the large transfer heels "Tf".

By way of indication and without limitation, FIG. 4 schematically shows an embodiment of such a device for controlling the selection of needles, adaptable for example to a circular double cylinder loom, devoid of the Jacquard system.

In this figure, Z1 and Z2 respectively represent the lower and upper cylinders of the loom.

The picking lock "V1", when advanced towards the needle cylinder, has its inclined ramp facing the path of the knitting heels "Tt" of the plates 1 which cooperate, as known, with the needles 2 of the double hook type.

The function of this cam is to initiate and continue knitting a stripe on the fall of the loom with which it is associated. It is shown in Figure 4 in the radially depressed position, that is to say in the working position where the knitting heels "Tt" of the plates are forced to climb the ramp inclined relative to the horizontal.

As for the cancellation lock V2, when this is advanced towards the needle cylinder, it has its inclined ramp facing the path of the transfer heels "Tf" of the plates 1. This ramp, inverted with respect to that of the cam selection V1, aims to cancel the drop considered, always from the same needle, by lowering the needles, at this fall, in the low position of no picking of the wire.

In FIG. 4, this cam V2 is shown in its position of maximum radial spacing, so that it has no action.

The control of the cams is programmed by discs 3 driven in rotation in a continuous manner, in synchronism with the rotation of the cylinders Z1 and Z2, and on which are arranged bosses or cams 4 with which the feeler levers 5 cooperate.

When a feeler lever is in a hollow between two bosses, the corresponding selection cam is moved away from the cylinder, therefore out of action.

On the contrary, the passage of a boss under a feeler lever 5 lifts this lever which, in turn, actuates the vertical control rod 6.

Via a connecting rod 7, the movement is transmitted to the box 8 located at the end of the radial support rod 9 of the cam V1 or of the cam V2.

A spring 10, placed in the box 8, makes the elastic connection to allow the cam to come into action in two stages. Firstly, the cam rubs on the smallest heels of the plates, as seen for example in FIG. 5a for the cam V1, and secondly the cam is in the fully depressed position after the passage of the heels knitting means (cam V1 in Figure 5a) or large transfer heels (cam V2 in Figure 5b).

Springs 11 and 12, acting respectively on the rods 9 and 6, serve to bring all the members back to the starting position as soon as the action of a boss 4 on a feeler lever 5 ceases.

Figures 5a and 5b provide a better description of the sequence of successive operations for controlling the selection cams, assuming that the loom, comprising two falls each provided with a cam V1 and a cam V2, is used for knitting a sock.

FIG. 5a represents a section of the lower cylinder Z1, at the level of the knitting heels Tt of the plates 1.

In order for the change of the knitted yarn to take place on the rear side of the sock, the selection of needles must be made in the middle of the area of the small knitting heels. The location of the needles "M" and "N", which has been discussed with reference to Figure 1, is shown in Figures 5a and 5b. The cylinder rotating in the opposite direction to that of the hands of a watch, the needle "M" and the few needles which follow are provided with plates with medium knitting heel to allow entry into work of the selection cam V1 .

To start the stripe "R1" at the first fall, the cam "V1" is pushed into the working position. After having rubbed on a few small knitting heels, it attacks the few medium knitting heels from the needle "M" to initiate the ascent of the needles which will pick the thread at the first fall. The passage of the few heel means after the needle "M" allows the cam V1 to enter completely against the cylinder Z1 and thus all the needles around the entire periphery of the cylinder will initiate the ascent for the picking of the wire for a whole number cylinder turns.

Of course, all the other falls bringing different wires are canceled, as seen for example for the cam V1 of the second fall.

FIG. 5b represents a section of the lower cylinder Z1, at the level of the transfer heels Tf of the needle plates.

To stop the scratch "R1" at the first fall on the needle "N" after an integer number of revolutions of the cylinders Z1 and Z2, as we said with reference to FIG. 1, the needle "M" and the next few needles are fitted with plates with large transfer heels.

During the last knitting turn of the stripe "R1", the cam V2 of the first fall is pushed towards the cylinder (FIG. 5b) and it rubs on the means of transfer heels which fill almost the entire periphery of the cylinder. As soon as the large heels appear from the needle "M" they are taken by the cam V2 and are lowered towards the cancellation position to prevent the needles from picking up the thread at the thrower. In addition, the passage of the few large heels after the needle "M" allows said cam "V2" of the first fall to come completely against the cylinder and thus all the needles are gradually brought into the cancellation position. The needle "N" is therefore the last one which picked the thread at the first fall.

As soon as the knitting heel of the needle N has reached at least the highest point of the cam V1, and the cam V2 is in the fully pressed position against the cylinder, the cam V1 can be moved away from the first fall for the put out of action.

Immediately after the complete cancellation of the cam V1, the cam V2 can be removed, which completely cancels the first fall.

Of course, during this process, all the other cams "V2" on the other falls which bring different wires remain in the position separated from the cylinder.

The invention has various advantages.

In particular, when repetitive transverse stripes are produced on a tubular knitted fabric in jersey or fancy stitches derived from jersey, for example charged or Jacquard stitches, the invention makes it possible to no longer cut the threads at each change of stripes.

On the other hand, as the change of stripes is done without overlapping of the new thread which starts and the old thread which withdraws, there is no longer any excess thickness of the knitting on some needles, nor irregular and unsightly mixing of these two sons. This results in a very clear and frank delimitation between two successive stripes.

As the respective threads of the different stripes are no longer cut, no free end of thread emerges on the right side of the knit at the location of the changes, hence a marked improvement in the aesthetic appearance of the knit.

In addition, the changes of stripes take place without any slowing down of the speed of the knitting machine.

Since the wire cutter scissors of the scratching devices are no longer used for these repetitive scratch changes, there is less wear and reduction in the frequency of possible incidents with these devices.

As a variant, instead of starting a scratch on the needle of a certain column of cells "M" and of stopping this scratch on the needle of the column of cells "N" above (FIG. 1), it is also possible to operate start and stop on the same needle of the column of meshes M ', as shown in FIG. 2.

The texture shown in Figure 1 shows that each change of scratches there is no intermediate flange, at the places designated by "T". Therefore, depending on the quality and fineness of the knitted threads, the interlining tends to deviate somewhat at these locations.

The fact of stopping and starting the scratches on the same column of meshes M ′, according to the method represented in FIG. 2, has the effect of tightening the mesh between changes of scratches and thus improving the appearance aesthetics of knitting.

In such an embodiment of the process on a double cylinder loom, the lining of the lower cylinder "Z1" at the knitting heels remains unchanged (see FIG. 5c).

On the other hand, the few large transfer heels that initiate the cancellation of the fall start from the needle L '(see Figure 5d).

In the embodiments of the method which have just been described, the basic principle consists in making the transverse stripes without overlapping of wires, or unsightly connections by permanently feeding a well determined wire at each of the different falls. But this has the consequence of theoretically limiting the possible number of different scratches to the number of falls with which the loom is equipped.

However, it is known practice to provide knitting looms with scratching devices which make it possible to change the thread thrower during work, which makes it possible to increase the possible number of different stripes.

The invention takes advantage of such a device by suitably adapting it, so that it multiplies the number of different stripes or transverse bands which can be carried out at the same fall in the loom, while retaining the advantage of not having neither overlapping, nor cutting of the threads at the changes of stripes, while ensuring the connection of the threads by a normal mesh.

Figure 6 shows the principle of operation with change of throwers at one of the falls.

The thrower "J1", bringing the thread "f11", is in the working position at this fall and the needles pick this thread under the conditions already described.

The thrower J22, bringing the wire f ₂₂ to this same fall, is in the retracted position (out of work), but a vertical guide "G" prevents the section of wire connecting the last stitch to the thrower J22 from entering the chisel "S ". The lower end of this guide has a notch in the direction of travel to prevent the section of wire from escaping from the lower part of the guide.

When it is necessary to change the appearance of the stripe on the fall considered, the permutation of the throwers is carried out while this fall is not working, that is to say while one is knitting a scratch on another fall. The swapping of the throwers can be carried out without slowing down the progress of the loom, because the needles pass without picking at this canceled fall.

When it is necessary to start a new stripe at the fall considered, the thrower with its corresponding thread is already in the working position when the selection cam V1 comes into action to initiate the ascent of the needles.

Note that the guide "G" is preferably retractable to allow the normal function of the scraper device to be temporarily resumed, for example on knitting machines for footwear for the introduction and removal of the elastic yarn at the ribbing, or reinforcing wire in heels and toes.

On certain types of looms the retractable guide "G" can be replaced by a selective command of the operation of the scissors; thus, when a thrower goes out of work, the thread is placed normally in the chisel, but the latter remains open so as not to cut the thread.

It goes without saying that the embodiments described are only examples and that it would be possible to modify them, in particular by substitution of technical equivalents, within the framework defined by the claims.

Claims (5)

1. A process for the production of stripes or repeating crossbands on a circular knitting machine with rotative needle cylinder, wherein yarns having different appearances are alternatively knitted, the yarn(s) which is (are) not used during the knitting of one band streaming longitudinally on the reverse side of the knitting/characterised in that using a knitting machine of known type comprising at least two knitting heads fed with different yarns and a respective device for selection of the needles associated with each knitting head, each band is started by controlling, on the one hand, the selection device associated with the knitting head whose yarn is already in use in such a way that the needles cease from then on to gather the yarn at this knitting head and by controlling, on the other hand, the selection device associated with another knitting head whose yarn is not yet in use in such a way that the needles from then on gather the yarn at this knitting head, the complementary operations being effected at the end of a subsequent band after a whole multiple of revolutions of cylinders of the machine, and the times of selection of the needles being chosen in such a way that the knitting operations of the different yarns at two different knitting heads start in the same column of stitches and stops in the same column of stitches, which column precedes the column where the knitting operations started, or is the same.

2. A process according to claim 1, characterised in that at least one of the knitting heads, fed with a yarn different from that of the other knitting heads, is associated with at least two different yam feeders, and in that the feeder is changed, without cutting the yarn, during a period when the needles are not gathering the yarn at this knitting head.

3. A process according to one of the preceding claims, characterised in that the yarns are maintained under spring tension in such a way that the yarn which is not in use sweeps across the whole section of the cylinder of the machine during each revolution.

4. By way of a new product, an article of knitwear knitted on a circular machine and exhibiting one or several stripes or circular bands in yarns of different appearances, each extending all the way round the article, and streaming yarns running from one band to another on the reverse side of the product, characterised in that the connection of the yarn of one band to the different yarn of the adjacent band of the article is one continuous stitching in which the loops of one of the yarns which interlace with the loops of the other yarn are each constituted by a single yarn.

5. A product according to claim 4, characterised in that on the reverse side of the knitting the yarn runs along a line (ff, Figs 1 and 2) slightly at an angle to the columns of stitches.

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