CN109518352B

CN109518352B - Method for preparing a warp knitting machine and warp knitting machine

Info

Publication number: CN109518352B
Application number: CN201811101110.1A
Authority: CN
Inventors: K.布兰德尔
Original assignee: Karl Mayer R&D GmbH
Current assignee: Carlmeyerstol R & D Co.,Ltd.
Priority date: 2017-09-20
Filing date: 2018-09-20
Publication date: 2021-03-23
Anticipated expiration: 2038-09-20
Also published as: KR20190033019A; TWI801408B; CN109518352A; KR102072812B1; EP3460113A1; TW201915249A; EP3460113B1

Abstract

The invention relates to a method for preparing a warp knitting machine and a warp knitting machine, in particular to a method for preparing a warp knitting machine (1) in a new pattern mode, wherein yarns (4) of warp yarns penetrate into a yarn guide needle (2) and at least one stitch row is formed through the combined action of the yarn guide needle (2) and a knitting needle (3). It is desirable to simplify the preparation of warp knitting machines. The tension of the fed yarn (4) is measured and limited to a preset maximum value.

Description

Method for preparing a warp knitting machine and warp knitting machine

Technical Field

The invention relates to a method for preparing (Einarbeiten) new designs (Muster) for warp knitting machines, in which method the yarns of the warp threads are threaded into a guide needle (Legeneradel) and at least one stitch row (Mascheneihe) is formed by the interaction of the guide needle with a knitting needle (Wirknadel).

The invention further relates to a warp knitting machine having at least one main shaft, at least one thread guide bar (Legebarre), at least one needle bar, a thread balancing device, at least one thread feed drive and at least one fabric drawing device (Warenabzug).

Background

The data which are usually necessary are available for known knitted fabrics (Wirkware) which may also be referred to as "patterns" for short. In particular, the yarn laying movement (Legung), the amount of warp let-off for the yarn and the amount of fabric draw-off belong to the data. Thus, when the warp knitting machine has to be prepared because, for example, the warp beam is completely worn out (abgearbeitet) or the machine should be changed to another pattern, the operator passes the yarn into the guide needles, produces one or more courses in which the yarn is pulled manually taut after each course of formation, then activates the yarn delivery drive at the set yarn let-off value, the machine can produce further courses of the course until the produced knitted fabric can be extracted with the fabric-pulling device, then activates the fabric-pulling device and can start production.

However, when a new pattern is to be created, not all necessary data is or is not necessarily available. In general, the inlay movement, that is to say the movement direction of the guide needle relative to the knitting needle, is set. The yarn let-off must however be determined, for example, empirically. For this, a certain experience and a corresponding feeling of the operator are required. In each work step, there is a risk associated therewith caused by operational errors and lack of expertise. As a result, damage occurs at the woven element (wirkement) and/or also at the process material, for example the yarn. Preparation is correspondingly time-consuming and costly.

Disclosure of Invention

The aim of the invention is to simplify the preparation of a warp knitting machine in the case of a new pattern.

This object is achieved in a method of the type mentioned at the outset in that the tension of the fed-in yarn is measured and limited to a predetermined maximum value.

The limitation of the yarn tension avoids excessively high yarn tensions. Damage to the knitting tool (sometimes referred to as a looping tool) or to the yarn material is therefore considerably reduced. Furthermore, the limitation of the tension of the fed yarn allows a limitation in freely selectable parameters, so that the operator can work only in a limited working area. This further simplifies the preparation, since the possibility of modification and therefore also the possibility of failure can be kept small. The tension of the looped yarn is preferably measured here at components which do not directly guide the yarn. This likewise does not relate to the tension of the individual yarns, but rather to the tension present in the entirety of the yarns transported by the beam.

Preferably, the courses are formed during the operation of the warp knitting machine at slow speed (kriechging). Therefore, the warp knitting machine can be operated at a very low speed during the preparation period when the new pattern is adopted. The yarn tension is virtually independent of the operating speed of the warp knitting machine.

Preferably, the tension of the thread is measured at the point in time at which the thread guide reaches its reversal point behind the knitting needle. In this case, the maximum deflection of the thread guide is performed. At this point, the spacing between the various knit elements is at a maximum. Accordingly, the tension of the same yarn is at its maximum here. It is sufficient here to measure the tension and to base it on a different process.

Preferably, the tension is adjusted by adjusting the yarn feed drive. The yarn feed drive actively drives a warp beam from which the yarn of the warp threads is drawn off. In a later production run, in which the knitted fabric is produced continuously, the yarn feed drive is operated at a constant yarn feed value. The yarn let-off value is usually stated in mm/R, i.e. millimeters per kilogram. One of the preparatory tasks when applying the new pattern to warp knitting machines consists in measuring the relevant yarn let-off value. The thread let-off value can be determined by setting the tension and operating the thread delivery drive in a closed-loop control loop in such a way that the tension is also reached, but not exceeded. When the yarn delivery drive outputs too much yarn length per loop formation process, the tension is too low. The tension is too high when the yarn delivery drive outputs too little yarn length per loop forming process. Accordingly, the "feed speed" can be adjusted to the appropriate yarn feed value by means of a relatively simple adjustment for the yarn feed drive. It is not necessarily essential here that the thread delivery drive already runs continuously in the preparation phase. The thread delivery drive can also be operated in a repeat manner, i.e. a short time during which some thread is delivered and then stopped again. So that only excessive tension peaks should be avoided. Furthermore, very low tensions or no tensions at all can be present completely temporarily also in the yarn during the loop forming process. The thread delivery drive in any case operates only in the positive drive direction, i.e. in the direction in which it delivers the thread.

Preferably, the fabric draw-off device is started and the adjustment of the thread delivery drive is continued for a predetermined time after the start of the fabric draw-off device. The change in the appearance of the knitted fabric is obtained by activating the fabric-pulling device. In the case of no fabric extraction, the respective coil rows are produced in a manner of speaking "auf Block". The stitches of each row are actually placed against each other in the direction of production of the knitted fabric. A slightly different appearance is then obtained by activating the fabric-pulling device. Depending on at which speed the fabric-pulling device is run, a looser or tighter knit structure is obtained. The adjustment of the thread feed drive then also has an effect on the structure of the knitted fabric, since, when the thread feed drive feeds a larger thread length per stitch forming process, a looser knitted fabric can be achieved than with a smaller thread length per stitch forming process. After the activation of the fabric pull-off device, the operator can then check whether the knitted fabric corresponds to the need or desire. If this is not possible, the operator may change the setting for the tension.

Preferably, the yarn let-off value of the yarn delivery drive is indicated. The yarn let-off value, for example mm/R, i.e. millimeters per kilogram, is generated from the yarn tension. The yarn let-off value can be indicated when the knitted fabric has a desired appearance and a desired tactile feel, so that it can be used again later in the production process in the same pattern. The indication can take place optically via a display. But the indication may also consist in printing or otherwise storing the yarn let-off value. It is only important that the yarn let-off value is available later, that is to say in the reproduction of the same pattern, and can be fed into the knitting machine.

The predetermined maximum value is preferably set as a percentage of a base value (Bruchteil). The base value is known for each machine and can be set by the manufacturer. The maximum value is derived, for example, from measurements at the respective warp knitting machine, wherein fluctuations can also be taken into account here. A certain percentage of the base value can then be set as tension, for example. And therefore no absolute value needs to be set.

This object is achieved for a warp knitting machine of the type mentioned at the outset in that the thread tension measuring device is connected to a control device which regulates the thread feed drive in a learning phase.

As explained above in connection with the method, the thread tension of the thread of the warp threads can thus be determined by means of the thread tension measuring device and can be used as a basis for setting the thread let-off value of the thread transport drive. Thus, on the one hand, overloading of the knitting element and the yarn material is avoided. On the other hand, the operator has the simple possibility of changing the appearance and the feel of the produced knitted fabric. The operator only has to change the setpoint value, which the control device uses to adjust the thread delivery drive.

Preferably, the yarn tension measuring device is arranged at the yarn balancing device. The yarn balancing assembly is necessary in the production of knitted fabrics in warp knitting machines because of the fluctuating yarn consumption during the loop formation. The fluctuations within the yarn consumption can be compensated via a yarn balancing device. The yarn balancing device can now also be used in a simple manner for measuring the yarn tension. Often "measuring" in the sense of a numerically expressed result is not required. The yarn tensioning device can also be arranged at the fixing part of the yarn balancing device.

Preferably, the yarn tension measuring device measures the total tension of the plurality of yarns. This results in a certain balance over the width of the warp knitting machine. The influence of the individual yarns and their tensions is thus kept small, while the total tension of a plurality or even all of the yarns yields meaningful quantities.

The thread tension measuring device preferably detects the tension at the thread guiding and tensioning element (Fadenkreuz). The thread guiding and tensioning element is in the simplest case an elastically mounted lever via which the thread of the warp thread is guided before it passes into the thread guiding indentation of the thread guide needle. When the guide needle is at its reversal point behind the knitting needle, the yarn guiding and tensioning assembly has its maximum deflection. At this point, the maximum yarn tension can be measured. The thread tension is preferably measured here at a stationary (lastheld) component, for example in the region between an elastic assembly carrying the thread guide and tension assembly and a support of the warp knitting machine.

Preferably, the yarn tension measuring device is synchronized with the main shaft. The yarn tension measuring device can then take the corresponding tension exactly at the moment described above, at which the guide needle has its maximum distance from the knitting needle.

Drawings

The invention is described below with reference to a preferred embodiment in conjunction with the accompanying drawings. Wherein:

fig. 1 shows a very schematic view of a part of a warp knitting machine, and

fig. 2 shows a schematic representation of the tension profile.

Detailed Description

The warp knitting machine 1 (a part of which is represented) has guide needles 2 which are arranged at a guide bar which is not further represented. The warp knitting machine furthermore has knitting needles 3 which are arranged on knitting needle bars which are not further represented. During operation of the warp knitting machine, the guide needle 2 and the knitting needle 3 are moved relative to each other to form a loop of the knitted fabric. The relative movement has a section in which the thread guide 2 is moved through the gap between the knitting needles 3 and a section in which the thread guide is moved parallel to the longitudinal extent of the knitting needle bar.

In such a movement, the yarn 4 drawn out by the warp beam 5 is processed into a stitch of the knitted fabric.

The yarn 4 is guided to a yarn guiding and tensioning assembly configured as a rod 6. The rod is supported at the elastic assembly 7. The elastic element 7 allows a certain mobility of the rod 6 when the tension of the yarn 4 changes. Such a change in tension occurs at least once per coil forming cycle, as can be gathered from fig. 2.

Fig. 2 shows a first curve 8 (which reflects the tension of the individual yarns 4) and a second curve 9 (which reflects the corresponding tension profile of the entire warp yarn). The course of the tension force represented in curve 9 can be determined from the movement of the rod 6. For this purpose, a sensor 10 is arranged on the spring arrangement 7, which sensor detects the tension of the spring arrangement 7 and thus the force exerted by the lever 6 on the spring arrangement 7. It is of course also possible to use another sensor in order to measure the tension of the warp thread formed by the yarn 4. The sensor 10 can be formed, for example, by a strain gauge strip which is arranged between a support 18 of the warp knitting machine and a holder 19 of the spring assembly 7 which is fixed at the support 19. The sensor is thus located at the immovable part and the sensor is located outside the elements of the warp knitting machine that directly guide the yarn.

The sensor 10 is connected to a control device 11. The control device 11 is connected to the thread delivery drive 12 of the warp beam 5.

The warp knitting machine 1 has a main shaft 13. The main shaft 13 is responsible for most of the movement of the knitting tool. The main shaft controls in particular the movements of the thread-guide needles 2 and the knitting needles 3. In short, one revolution of spindle 13 causes the coil forming process in most cases, thereby generating a coil array for each revolution of spindle 13.

The rotational angle sensor 14 detects the rotational position of the spindle 13 and likewise informs the control device 11 of this rotational position.

No further fabric-drawing device is present, with which the formed knitted fabric can be drawn out of the working area formed by the guide needle 2 and the knitting needle 3.

When the warp knitting machine is put into operation, the yarn 4 is threaded into the guide needle 2. This is usually done in the case of guide bar removal, where the guide needles 2 are better accessible. After the yarn has been threaded in, the guide bar is brought to its normal operating position and assembled there. The operator then slowly puts the machine in motion and first checks whether the thread guide needle 2 can travel through the gap between the knitting needles 3 without collision. If correction is possible.

The operator then first performs the first coil forming process. Thereafter, the yarn 4 is manually tightened. This is followed by one or more further stitch forming processes until at least one row of stitches is formed which is continuous over the working width of the warp knitting machine 1. Between each loop forming process, the yarn 4 is manually tensioned.

When continuous loop formation is performed, the yarn feeding driver 12 of the warp beam 5 is put into operation. The warp beam 5 then transports the yarn 4. The coils are then first formed in blocks, i.e. the coils lie closely against one another. After this, the fabric-pulling device not presented further is put into operation and the production of the fabric can begin.

However, this presupposes that certain parameters of the production of the knitted fabric are known, in particular values for what is known as the yarn let-off, which are typically specified in mm/R, i.e. millimeters per kilogram. In addition to the actual laying movement and stitch density (which can be influenced by the fabric draw-off device), the yarn let-off is an important value in the production of knitted fabrics.

When a new pattern is to be created, the value of the yarn let-off is not available. The yarn let-off is adjusted with the experience and feel of the operator. Here, risks arise in each work step due to handling errors and lack of expertise. Damage can thereby occur to the knitting elements, i.e. the thread guide 2 and the knitting needle 3. In addition, the yarn 4 may also be damaged.

To alleviate this problem, the tension of the fed yarn 4 is measured by the sensor 10 and the actual tension is transmitted to the control device 11. The control device 11 compares the actual tension with a settable setpoint tension and now adjusts the thread feed drive 12 in such a way that the setpoint tension, which is a maximum value that can be set in advance, is not exceeded.

If the thread feed drive 12 is actuated in such a way that it feeds more threads 4 per kilogram, i.e. a greater thread length, then the tension drops. The tension increases when the thread feed drive 12 is driven in such a way that it feeds less thread per kilogram, i.e. a smaller thread length. This automated processing makes it possible for the warp knitting machine to find out to some extent the correct value of the approach to the yarn let-off.

This "learning process" continues as the fabric pulling device starts and the loop becomes larger. This also results in a greater length of thread 4 for each loop. Correspondingly, the thread delivery drive must rotate the warp beam 5 slightly faster in order to deliver a greater length of thread 4 per loop forming process. The tension is also detected here and the thread feed drive 12 is adjusted in such a way that the maximum tension is not exceeded.

The tension need not be input as an absolute value. Each warp knitting machine 1 usually has a basic value which is set by the manufacturer or which can be measured when the warp knitting machine is first put into operation. The operator can then set, for example, a percentage share, i.e. a percentage, of the basic value via the input device 15 in order to adjust the maximum tension. The operator can then visually or by feel check whether this tension value has produced the desired quality of the knitted fabric. If this is not possible, the percentile value may be changed via the input means 15.

Once the knitted fabric is produced with satisfactory quality, the value of the yarn let-off is indicated via the display device 16. The display device is here presented schematically. It is not necessary here to use a display or a printer. It is also possible to store only the value of the yarn let-off, so that the stored value is then available for later production processes.

The yarn let-off value is then used to produce a later knitted fabric containing the same pattern.

The described process is preferably carried out during the operation of the warp knitting machine at slow speed, so that the operator can continuously check, in the case of slow speed, whether the knitted fabric is actually produced with the desired appearance and the desired feel.

The yarn guiding and tensioning assembly with the rod 6 and the elastic means 7 forms a yarn balancing device which is required during operation in order to balance the yarn consumption which fluctuates during loop formation. The yarn balancing device can now additionally be used in order to continuously measure the tension of the yarn.

As can be gathered from the curve of fig. 2, the tension of the yarn 4 fluctuates considerably during the loop formation. This is because the yarn consumption also fluctuates during the loop forming process. The tension is greatest when the guide needle 2 is at the reversal point behind the knitting needle 3, more precisely on the side of the hook 17 of the knitting needle 3. The guide needle 2 has a maximum deflection relative to the knitting needle 3. By means of the rotation angle sensor 14, which detects the rotation angle position of the spindle 3, it is now possible to detect this position of the thread guide needle 2, so that the control device 11 likewise detects the corresponding tension value only at this point in time. The control device 11 can therefore be said to form a snapshot of the tension at a point in time at which the spindle 13 is in the predetermined rotational angle position and at which the tension is only compared with a predetermined or predeterminable maximum value.

Claims

1. A method for preparing a warp knitting machine (1) for a new pattern, in which method a yarn (4) of a warp thread is threaded into a guide needle (2) and at least one stitch row is formed by the interaction of the guide needle (2) with a knitting needle (3), characterized in that the tension of the fed yarn (4) is measured and limited to a predeterminable maximum value, wherein the tension of the yarn is measured at the point in time at which the guide needle (2) reaches its reversal point after the knitting needle (3).

2. The method of claim 1 wherein the stitch lines are formed during operation of the warp knitting machine at a slow speed.

3. Method according to claim 1 or 2, characterized in that the tension is adjusted by adjustment of a yarn feed drive (12).

4. Method according to claim 3, characterized in that the fabric draw-off device is activated and the adjustment of the yarn delivery drive (12) is continued for a preset time after activation of the fabric draw-off device.

5. Method according to claim 3, characterized in that the yarn let-off value of the yarn delivery drive (12) is indicated.

6. Method according to claim 1 or 2, characterized in that the predetermined maximum value is set as a percentage of a base value.

7. Warp knitting machine (1) with a main shaft (13), at least one guide bar, a knitting needle bar, at least one yarn balancing device (6,7), at least one yarn feeding drive (12) and at least one fabric draw-off device, characterized in that a yarn tension measuring device (10) is connected to a control device (11) which regulates the yarn feeding drive (12) in a learning phase by means of the method according to claim 1.

8. Warp knitting machine according to claim 7, characterized in that the yarn tension measuring device (10) is arranged at the yarn balancing device (6, 7).

9. Warp knitting machine according to claim 8, characterized in that the yarn tension measuring device (10) measures the total tension of a plurality of yarns (4).

10. Warp knitting machine according to claim 9, characterized in that the yarn tension measuring device (10) measures the tension acting on the yarn guiding and tensioning assembly (6).

11. Warp knitting machine according to one of claims 7 to 10, characterized in that the yarn tension measuring device (10) is synchronized with the main shaft (13).