TWI793428B - Method for threading yarn after changing warp beam in warp knitting machine and warp knitting machine with corresponding functions - Google Patents

Abstract

The invention relates to a method for threading a warp beam after changing a warp beam in a warp knitting machine (1), comprising the following steps: passing through the eyelets of eyelets fixed on the guide bar of the warp knitting machine (1) 9) and form the old warp yarns of the knitted fabric that are pulled into the fabric drawing device (3) of the warp knitting machine (1) and the replacement warp yarns (12) that belong to the warp beams that are newly changed into the warp knitting machine (1) Connect; thread the replacement warp yarn, the method is that the fabric pulling device (3) pulls the knitted fabric, so that the old warp yarn pulls the replacement warp yarn through the eyelet (9) of the eye needle (8); during the yarn threading process of the replacement warp yarn , the warp beam is rotated by means of the warp beam driving device of the warp knitting machine (1), so that the replacement warp thread is actively released through the warp beam. The invention also relates to a warp knitting machine (1) with threading function after warp beam change for carrying out the method described above.

Description

Method for threading yarn after changing warp beam in warp knitting machine and warp knitting machine with corresponding functions

The invention relates to a method for threading after a warp beam change in a warp knitting machine.

Warp knitting machines have knitting tools which process warp threads into a textile material, the so-called knitted fabric, during the knitting process. The warp knitting machine also has a plurality of bars, wherein a plurality of knitting tools are respectively arranged on each bar. Since many knitting tools can be moved simultaneously by means of one bar, many loops are simultaneously formed during the knitting process. Here, this is the reason for the high production capacity of warp knitting machines. The knitted fabric produced by the warp knitting machine is drawn from the knitting zone of the warp knitting machine by fabric drawing. In the knitting zone, the knitted fabric is processed into loops by means of knitting tools.

The warp threads are generally placed on so-called warp beams. Many warp threads are arranged parallel to each other on the warp beam. Once the warp thread has been used up, the warp beam must be replaced in order to provide new yarn material. The warp knitting machine is stopped and the warp threads are cut so that the warp beams can be removed from the warp knitting machine. The warp thread that cuts through the eye pin of the yarn guide bar of warp knitting machine is passed to the knitting position and the yarn guide bar is pulled down. A new warp beam is swapped in. The warp threads of the new warp beam are now pulled through the eyelets in groups of 20 to 40 yarns by means of the threading tool. This process is done manually. During this time, the warp beam is also manually turned in order to provide the proper amount of yarn to pass through the warp. This is tedious and time-consuming.

Knotting devices are also known from the prior art, which interconnect warp threads. Such a knotting device is disclosed, for example, by DE19504573C2. It is possible in principle that the warp threads of the newly inserted warp beam be tied Knotted to the old warp thread located in the machine so that the old warp thread can pull the new warp thread through the eyelet of the eyelet needle. In principle, it is also conceivable for the warp threads to be connected in other ways. The connection points between the newly inserted warp threads and the old warp threads cause changes in the properties of the warp threads which are important for knitting technology. Depending on the type of connection, for example the thickness and/or the tensile and flexural strength at the connection point change in a disadvantageous manner. Such changes are, for example, effective local thickening at a connection point or overlapping regions of the warp threads in the case of material-fit or force-fit connections. Said changes may directly make it difficult or hinder the passage of the thickened connection point through the eyelet of the eye pin.

In the worst case, the connection point may fail when it cannot pass through the eye needle or other knitting implement or cannot withstand the forces that occur when passing the eye needle. Also, the knitting tools may be damaged at this time. This can lead to significant economic losses when, for example, the knitting tools of one or more bars have to be replaced.

The present invention is therefore based on the task of providing a process-reliable and rapid method for threading after a warp beam change which avoids the disadvantages mentioned above.

This task is accomplished by a method of threading after warp beam replacement in a warp knitting machine, which method has the following steps: old warp yarns are connected with replacement warp yarns belonging to newly changed warp beams in the warp knitting machine, the old The warp yarns pass through the eyelets of eyelets fixed on the guide bars of a warp knitting machine and form a knitted fabric that is drawn into the fabric pulling device of the warp knitting machine; threading of replacement warp yarns is done by fabric pulling The device pulls the knitted fabric so that the old warp yarn pulls the replacement warp yarn through the eyelet of the eye needle, and the warp beam is rotated by the warp beam driving device of the warp knitting machine during the threading process of the replacement warp yarn, so that the replacement warp yarn passes through the warp beam was released voluntarily.

As has been proven, new warp threads can be threaded in quickly and process reliably in this way. The warp beam guiding the old warp thread has been removed from the warp knitting machine and a new warp beam is installed on the warp knitting machine After that, start to execute the method of the present invention. The old warp thread is connected with the replacement warp thread of the newly inserted warp beam, wherein the form of the connection method used at this time is unimportant. The warp thread joining can be carried out by means of external joining devices or special joining tools, but it can also be carried out by means of devices belonging to the warp knitting machine. The fabric pulling device pulls the knitted fabric from the knitting zone of the warp knitting machine. Thereby, the replacement warp thread is pulled through the eyelet of the eyelet needle.

In order that no excessive warp thread loading occurs in the region of the eyelets, according to the invention, the warp beam is simultaneously rotated by the warp beam drive. According to the invention, the warp beam drive means may be an electric motor connected to the warp beam. According to the invention, the aforementioned method can be controlled by the control device of the warp knitting machine.

The method of the invention has the advantage that the downtime of the warp knitting machine is significantly shortened compared to manual threading of warp threads through the eyelets. The personnel requirements and yarn consumption during warp beam changes are reduced. Furthermore, according to the invention, for the first time it is possible to use connecting devices in warp knitting machines, where a minimum error rate is obtained when threading the yarn.

According to an embodiment of the invention, each old warp thread has a first section, the first section being part of the finished knitted fabric, and a second section, in which the old warp thread is present as an unknitted individual thread. When the knitted fabric is pulled, the second section of each individual yarn is also pulled simultaneously. Preferably, the old warp threads are respectively connected with replacement warp threads in the region of their second section.

Knitted fabric pulling is preferably carried out synchronously with the running of warp beam driving device, thereby the threading speed of the old warp thread that passes eyelet eyelet hole by pulling knitted fabric is consistent with the yarn feeding speed of warp beam releasing replacement warp yarn. This means that the adjustment is made such that the threading speed and the yarn supply speed are at least approximately identical and/or identical with respect to the time mean. When the yarn feeding speed and the threading speed are at least approximately the same, a sufficient amount of yarn is always supplemented by the warp beam. In order to achieve a corresponding adjustment, the yarn feed speed can be determined according to the invention as a function of the state of the warp beam and its rotational speed. In order to determine the state of the warp beam, according to the invention, the thickness of the fabric roll on the warp beam can be measured. The threading speed can be determined in a similar manner according to the invention. According to the invention, it is also possible that known warp thread data, for example concerning the thickness of the fabric roll, are used for the calculation.

Preferably carry out method of the present invention like this, in the threading process of changing warp yarn, described weaving Object take-off device and/or warp beam drive device (zeitweise) sometimes (zeitweise) run with reverse mode of operation. This means with regard to the fabric pulling device that it sometimes does not operate in the forward mode in which the knitted fabric is now pulled from the knitting zone. In the reverse operation of the fabric drawing device, the knitted fabric is supplied to the knitting zone from the fabric drawing direction. This makes it easier to pass the connecting region of the old warp thread and the replacement warp thread through the eyelet of the eyelet needle. Similarly, the warp beam can sometimes run in reverse, so that a replacement warp thread is pulled towards the warp beam.

The method according to the invention is preferably designed in such a way that the fabric drawing device and/or the warp beam drive are operated alternately in forward operation and reverse operation at a frequency of at least 1 Hz. This makes it easy to pass the connection point of the old warp yarn to the replacement warp yarn through the eyelet of the eyelet needle. The mode of operation is such that the connection point is to some extent swayed through the eyelet with reduced resistance, just like the mode of operation of an excited vibrating screen.

More particularly preferably, the method according to the invention is designed in such a way that during the threading process of changing the warp threads, the thread guide bar is displaced along the longitudinal axis of the thread guide bar with a frequency of at least 1 Hz. The warp threads connected to each other are thus excited, and their connection points can easily pass through the eye needles.

Advantageously, in an embodiment of the method according to the invention, the thread guide bar is displaced along its longitudinal axis by less than one gauge. The amplitude of the resulting vibrations of the thread guide bar is thus limited to relatively short displacement lengths. This is especially meaningful when only one thread guide bar of a warp knitting machine is to be vibrated, but not in other cases, because collisions of adjacent warp threads do not occur.

According to a possible variant, the method of the invention can be designed in such a way that during the threading of the replacement warp thread, the yarn tension and/or the profile of the connection point between the old warp thread and the replacement warp thread are monitored and the standard deviation is determined While causing the fabric pulling and/or warp beam drive to operate at a frequency of at least 1 Hz and/or the guide bar to displace elements at a frequency of at least 1 Hz along its longitudinal axis. The standard deviation is the deviation from one or more expected warp parameters. According to the invention, the desired warp parameter may be the thickness of the connection point. Thus, for example, the thickening or thinning of the connection points can be regarded as the standard deviation.

According to the invention, this connection point can also be monitored for the occurrence of yarn splicing. A standard deviation can also be an unexpectedly low or increased yarn tension. Best made in old warp and The yarn tension is measured individually on each yarn pair formed by changing warp yarns. According to the invention, other standard deviations can also be monitored.

The present invention can stipulate that the old warp thread is connected with the replacement warp thread along the yarn path between the eye needle and the warp beam. By pulling the knitted fabric, the connection point between the old warp thread and the replacement warp thread is then pulled through the eyelet of the eyelet needle. The yarn path traces the path where the old and replacement warp yarns are located. The yarn path extends from the warp beam to the eye needle.

Preferably, before the knitted fabric is drawn, the needles of the warp knitting machine de-loop all loops in order to pull the replacement warp thread through the eyelet of the eyelet needle. The knitting needles of the warp knitting machine, which may be compound needles, latch needles, pogo pins or other types of knitting needles, are therefore in a yarn-free state before carrying out the method of the invention. This connection point therefore does not have to be pulled through the hook of the knitting needle when carrying out the method according to the invention, which would entail additional error potential.

Particularly preferably, the needle bar of the warp knitting machine is placed in a predetermined position before drawing the knitted fabric, and the needle bar is held in a predetermined position during the drawing of the knitted fabric. According to the invention, the defined position can be occupied by the needle bar during the needle knockout.

According to the invention, the needle bar may be a needle-carrying bar of a warp knitting machine. The needles do not catch the warp yarn because the position of the needle bar remains unchanged during threading. Thus, the needles also remain free of yarn during threading. According to the present invention, the predetermined position may be the knock-over position of the knitting needle bar. The knock-off position is the position in which the needle bar is located during the knitting process when the knitting needles are knock-off.

Advantageously, said warp threads are connected to each other by ultrasonic welding. At this point, the old warp thread and the replacement warp thread are excited by vibrations in the ultrasonic range. Because of the internal friction that occurs at this point, the warp threads heat up and can fuse to each other. As has been proven, ultrasonic welding is well suited for the rapid joining of warp threads made of thermoplastic material. The connection points that arise are not always uniform and may occasionally have reduced resistance. As has been proven, the probability of error when such a connection point passes through the eyelet of the eye pin can be significantly reduced by means of the method according to the invention.

During the threading process of changing the warp thread, the yarn speed of the warp thread is preferably at least sometimes limited to a maximum of 1 mm/s. According to the invention, this can be done in such a way that the fabric drawing device and/or the warp beam drive run at a suitable speed. It is possible according to the invention that the thread speed of the warp thread is at least or just limited to a maximum of 1 mm/sec when the connection point of the old warp thread and the replacement warp thread passes through the eyelet of the eyelet needle. According to the invention, said corresponding instants can be determined on the basis of machine visual monitoring of the warp threads. According to the invention, however, this instant can also be determined in other ways. For example, this moment can be calculated based on the yarn speed and the distance between the connection point at which the warp threads are connected and the eyelet of the eye needle.

The invention also relates to a warp knitting machine with threading function after warp beam replacement, comprising a fabric pulling device, a warp beam, a warp beam drive device connected to the warp beam, and a control device, wherein the control device is set up for performing The following steps: accept the threading instruction; after accepting the threading instruction, control the fabric pulling device for threading, so that the fabric pulling device pulls the knitted fabric by means of the fabric pulling device, thus the warp yarn connected with the knitted fabric is threaded and control the warp shaft driving device in the process of controlling the fabric pulling device so that threading, so that the warp shaft is placed in rotation and actively pays out the replacement warp yarn that is wound onto the warp shaft. The warp thread can be a replacement warp thread, but alternatively it can also be an old warp thread as described in the introduction.

According to the invention, the control device can be a machine computer, a microcontroller, a computer located remotely from the warp knitting machine and connected to it via a network, or another type of data processing device.

It is also possible according to the invention that the warp knitting machine has a warp thread connecting device. A warp thread joining device is a device which is suitable for joining warp threads to each other. Here, according to the invention, it can be a knotting device, an ultrasonic welding device or another type of warp thread joining device.

The control device is preferably set up for synchronously controlling the warp beam driving device and the fabric pulling device so that the threading speed of the warp yarn from the knitting zone of the warp knitting machine is caused by pulling the knitted fabric with the fabric crimping device. It is consistent with the yarn feeding speed of the replacement warp yarn temporarily provided on the warp beam by the warp beam.

Preferably, the control device is set up for controlling the fabric pulling device and/or the warp beam drive during the control of the fabric pulling device for threading such that the fabric pulling device and/or the warp beam The drive is operated alternately in forward and reverse operation at a frequency of at least 1 Hz. this It can be said that the eyelets of the eye needles that allow the warp connection point to dangle through the warp knitting machine.

It is especially preferred that the warp knitting machine has a servo motor for displacing the guide bar of the warp knitting machine along the longitudinal axis of the guide bar, wherein the control device is set up for controlling the process of the fabric drawing device The servomotor is controlled in such a way that the yarn guide bar is displaced along the longitudinal axis of the yarn guide bar at a frequency of at least 1 Hz. The eye needle of this warp knitting machine is preferably fixed on the guide bar. Through the movement of the guide bar, the connection point of the warp thread passes through the eyelet of the eye needle easily.

It is also advantageous that the control device is set up to receive a monitoring signal relating to the yarn tension and/or the appearance image of the connection point between the old warp thread and the replacement warp thread during threading of the warp thread change and to cause the fabric to The drawing and/or warp beam drive operates at a frequency of at least 1 Hz and/or the guide bar is displaced along its longitudinal axis at a frequency of at least 1 Hz. According to the invention, the warp knitting machine can have at least one thread tension sensor for determining the thread tension. According to the invention, the warp knitting machine can also have a camera for monitoring the appearance of the connection points.

1: warp knitting machine

2: warp beam

3: Fabric pulling device

4: Guide bar

5: knitting needle bar

6: Warp connecting device

7: warp

8: eye needle

9: Eyelets

10: knitting needle

11: old warp

12: Replace the warp

13: Connection point

A preferred embodiment of the present invention is shown in the drawings, wherein: [Fig. 1] shows a schematic diagram of the warp knitting machine of the present invention before the warp beam of the warp knitting machine is replaced, and [Fig. Schematic diagram of the warp knitting machine of the present invention after replacement, [Fig. 3] shows a detailed schematic diagram of the eye needle of the warp knitting machine of the present invention when threading, and [Fig. 4] shows the warp when threading Schematic diagram of the machine.

FIG. 1 shows a schematic view of the warp knitting machine 1 according to the invention before the warp beam 2 of the warp knitting machine 1 is changed. The warp knitting machine 1 has a fabric pulling device 3, a plurality of guide bars 4, knitting needle bars 5 and a warp thread connecting device 6, which is provided for ultrasonic welding of warp threads 7, of which only one is shown by way of example. Warp 7. in the yarn guide A plurality of eye pins 8 are fixed on the comb bar 4 . The warp thread 7 is guided through the eyelet 9 of the eye needle 8 .

Warp beam 2 is free and should now be replaced. To this end, first all warp threads 7 are stripped by knitting needles 10 fixed on the needle bar 5 . The needle bar 5 is now placed in the knock-off position and then held in the knock-off position. Next, warp yarn 7 is cut.

FIG. 2 shows a schematic view of the warp knitting machine 1 according to the invention after the warp beam 2 has been changed. The end of the warp thread that was originally positioned in the warp knitting machine 1 now forms the old warp thread 11 , and the warp thread that exits from the warp beam 2 that is newly changed in is called a replacement warp thread 12 . An old warp thread 11 and a replacement warp thread 12 are each shown by way of example. The warp thread connecting device 6 is inserted in the thread path between the thread guide bar 4 and the warp beam 2 . The old warp thread 11 and the replacement warp thread 12 are inserted into the warp thread connecting device 6 and thereby connected to each other.

FIG. 3 shows a detailed schematic view of the eye needle 8 of the warp knitting machine of the present invention during yarn threading. According to the method of the invention, the knitted fabric produced by the warp knitting machine is drawn from the knitting zone of the warp knitting machine by means of a fabric drawing device. At the same time, the warp beam driving device of the warp knitting machine makes the warp beam in rotation. The old warp thread 11 and the replacement warp thread 12 are connected to one another in the region of the ultrasonically welded connection point 13 . By pulling the knitted fabric, the connection point 13 is pulled through the eye 9 of the eye needle 8 . During this period, the warp beam actively replenishes the supply of replacement warp threads 12 . This facilitates the passage of the connection point 13 through the eyelet 9 .

FIG. 4 shows a schematic view of the warp knitting machine 1 during threading. The warp thread connecting device 6 is now no longer in the thread path. Likewise, the needles 10 do not hold warp yarns. In order to allow the connection point 13 to pass reliably through the eyelet 9 of the eye needle 8, the fabric drawing device 3 and the warp beam drive are sometimes run in reverse. This happens precisely when the not shown control device of the warp knitting machine 1 determines the standard deviation associated with the warp thread tension. For this purpose, the warp knitting machine 1 is equipped with a not shown yarn tension sensor. Reverse travel is also initiated when the control device detects an impermissible thickening or narrowing of the connection point 13 . For this purpose, the warp knitting machine 1 is equipped with a camera, not shown, in order to visually grasp the connection points 13 .

1: warp knitting machine

2: warp beam

3: Fabric pulling device

4: Guide bar

5: knitting needle bar

6: Warp connecting device

7: warp

8: eye needle

9: Eyelets

10: knitting needle

Claims (16)

A method for threading after a warp beam change in a warp knitting machine (1), the method having the following steps: connecting an old warp thread (11) with a replacement warp thread (12), said old warp thread passing through a fixed The eyelet (9) of the eye needle (8) on the guide bar (4) of the warp knitting machine (1) and forms the fabric pulling device (3) that is pulled into the warp knitting machine (1) ), the replacement warp yarn belongs to the warp beam (2) that is newly replaced in the warp knitting machine (1), and the replacement warp yarn (12) is threaded through the fabric pulling device ( 3) pull the knitted fabric, so that the old warp yarn (11) pulls the replacement warp yarn (12) through the eyelet (9) of the eye needle (8), and the replacement warp yarn (12) ) during the threading process, the warp beam (2) is rotated by means of the warp beam driving device of the warp knitting machine (1), so that the replacement warp yarn (12) is passed through the warp beam (2) active pay-out, wherein the needles (10) of the warp knitting machine (1) release all loops in order to pull the replacement warp thread (12) through the eyelet (9) before the knitted fabric is drawn . The method according to claim 1, wherein the pulling of the knitted fabric is performed synchronously with the operation of the warp beam driving device, so that the old warp yarn (11) caused by pulling the knitted fabric The threading speed of the eyelet (9) passing through the eyelet needle (8) is consistent with the yarn feeding speed of the warp beam (2) for releasing the replacement warp yarn (12). The method as claimed in claim 1 or 2, wherein in the threading process of the changing warp yarn (12), the fabric pulling device (3) and/or the warp beam driving device are sometimes reversed Run as run. The method according to claim 3, wherein the fabric drawing device (3) and/or the warp beam driving device are operated alternately in forward operation and reverse operation at a frequency of at least 1 Hz. The method according to claim 1 or 2, wherein during the threading process of the changing warp yarn (12), the guide bar (4) moves along the guide bar at a frequency of at least 1 Hz (4) The longitudinal axis is shifted. A method as claimed in claim 5, wherein said guide bar (4) is displaced along its longitudinal axis by less than one gauge. The method according to claim 5, wherein during said threading process of said replacement warp yarn (12), the yarn at the connection point between said old warp yarn (11) and said replacement warp yarn (12) is monitored tension and/or profile, and when determining the standard deviation, cause the fabric to pull and/or the warp beam drive to operate at a frequency of at least 1 Hz and/or the guide bar (4) to rotate along its longitudinal axis A frequency shift element of at least 1 Hz. The method as claimed in item 1 or 2, wherein the old warp yarn (11) is connected with the replacement warp yarn (12) along the yarn path between the eye needle (8) and the warp beam (2) ) connected. The method according to claim 1 or 2, wherein the knitting needle bar (5) of the warp knitting machine (1) is placed in a prescribed position before pulling the knitted fabric and during pulling the knitted fabric held in the specified position. The method as claimed in claim 1 or 2, wherein said warp yarns are connected to each other by ultrasonic welding. Method according to claim 1 or 2, wherein during said threading of said changing warp yarn (12), the yarn speed at the knitting station is at least sometimes limited to a maximum of 1 mm/s. A warp knitting machine (1) with a threading function after the warp beam is replaced, the warp knitting machine comprises a fabric pulling device (3), a warp beam (2), and a warp beam connected to the warp beam (2) A driving device and a control device, wherein the control device is set up to perform the following steps: accepting a threading instruction; controlling the fabric pulling device (3) to perform threading after receiving the threading instruction, so that the fabric The pulling device (3) pulls the knitted fabric by means of the fabric pulling device (3), whereby the warp yarn connected to the knitted fabric is penetrated; and During the process of controlling the fabric pulling device (3) for threading, the warp shaft driving device is controlled so that the warp shaft (2) is rotated and the warp shaft (2) is actively released to be wound onto the warp shaft (2) In order to pull the replacement warp yarn (12) through the eyelet (9) before the knitted fabric is drawn, the knitting needles (10) of the warp knitting machine (1) will all Coil off. The warp knitting machine (1) according to claim 12, wherein said control device is set up to synchronously control said warp beam driving device and said fabric pulling device (3), so that The threading speed of the warp yarn in the knitting area of (1) caused by pulling the knitted fabric with the help of the fabric pulling device (3) and the warp beam (2) are released and wound on the warp The yarn feeding speeds of the replacement warp yarns (12) on the shaft (2) are consistent. Warp knitting machine (1) as claimed in claim 12 or 13, wherein said control device is set up for controlling said fabric drawing device in the process of controlling said fabric drawing device (3) so as to carry out threading (3) and/or said warp beam driving device, so that said fabric drawing device (3) and/or said warp beam driving device are operated alternately in forward operation and reverse operation at a frequency of at least 1 Hz. The warp knitting machine (1) as claimed in claim 12 or 13, wherein the warp knitting machine (1) has a function for making the guide bar (4) of the warp knitting machine (1) along the guide yarn Servomotor for the displacement of the longitudinal axis of the bar (4), wherein the control device is set up for controlling the servomotor during the control of the fabric drawing device (3) such that the guide comb A bar (4) is displaced along said longitudinal axis of said guide bar (4) at a frequency of at least 1 Hz. The warp knitting machine (1) as claimed in claim 15, wherein the control device is set up to receive the information related to the old warp yarn (11) and the replacement warp yarn (12) during the threading process of the replacement warp yarn (12). ) of the monitoring signal of the yarn tension and/or profile at the connection point, and when determining the standard deviation causes the fabric pull and/or the warp beam driving device to operate at a frequency of at least 1 Hz The running and/or displacement of the thread guide bar (4) along its longitudinal axis has a frequency of at least 1 Hz.

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