EP3798340B1 - Thread drawing-in method for warp beam replacement in a knitting machine and knitting machine with a thread drawing-in function for warp beam replacement - Google Patents

Description

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

Warp knitting machines have knitting tools that process the warp threads in a knitting process into a textile material, a so-called knitted fabric. Warp knitting machines also have a plurality of bars, a plurality of knitting tools being arranged on each bar. Since a large number of knitting tools can be moved simultaneously by means of a bar, a large number of loops are formed at the same time during the knitting process. This is the reason for the particularly high production output of warp knitting machines. A knitted fabric produced by the warp knitting machine is withdrawn from a knitting area of the warp knitting machine by a fabric take-off. In the knitting area, the knitted fabric is produced by the knitting tools with loop formation.

The warp threads are usually stored on so-called warp beams. A multiplicity of warp threads are arranged parallel to one another on a warp beam. As soon as the warp threads have been used up, the warp beam must be changed to provide new thread material. The warp knitting machine is stopped and the warp threads are cut so that the warp beam can be removed from the warp knitting machine. The separated warp threads are made by punching needles The guide bar of the warp knitting machine is pulled through in the direction of the knitting point and the guide bar is unhooked.

A new warp beam is substituted. The warp threads of the new warp beam are now pulled through the perforated needles in groups of 20 to 40 threads by means of a pull-in tool. This process is done manually. Meanwhile, the warp beam is also set in rotation by hand in order to provide a suitable amount of thread for pulling the warp threads through. This is comparatively cumbersome and time-consuming.

Knotting devices that connect warp threads to one another are also known from the prior art.

Knotting devices of this type are for example from DE 195 04 573 C2 famous. In principle, it is possible to knot the warp threads of a newly replaced warp beam to the old warp threads in the machine so that the old warp threads can pull the new warp threads through the eyes of the perforated needles. A connection of the warp threads in another way is also conceivable in principle.

The pamphlet CH 153 172 A describes a method and a device for connecting warp threads. A knotting device is used to automatically knot pairs of warp threads. The knotting device is driven by means of a hand crank and knots successively adjacent pairs of threads.

The pamphlet DE 200 02 925 U1 describes an automatic feeding device for a warp knitting machine. This is used to connect pairs of warp threads with one another. The draw-in device comprises a front body and a rear body, the grooves for receiving warp threads exhibit. The pull-in device allows pairs of threads to be connected to one another by gluing.

A connection point between the newly exchanged warp thread and the old warp thread changes the properties of the warp thread, which are important from a technical point of view. Depending on the type of connection, for example the strength and / or the tensile and flexural rigidity at the connection point change in an unfavorable manner. Such changes are, for example, the effective local strength at a connection point or an overlap area of the warp threads in the case of a material or force-locking connection. The changes can make it more difficult or even prevent the thickened connection point from passing through the eyes of the perforated needles.

In the worst case, the connection point can fail if it does not fit through the perforated needle or another knitting tool or if it cannot withstand the forces occurring when it passes through the perforated needle. Furthermore, the knitting tools can be damaged in the process. This can lead to considerable economic damage if, for example, the knitting tools of one or more bars have to be replaced.

The invention is therefore based on the object of providing a process-reliable and quick method for threading in after changing the warp beam, which method avoids the disadvantages described above.

The object is achieved by a method for threading in after changing the warp beam in a warp knitting machine, with the following steps: connection of old warp threads, which by eyelets from on hole needles attached to a guide bar of the warp knitting machine are passed through and form a knitted fabric pulled into a fabric take-off device of the warp knitting machine, with interchangeable warp threads belonging to a warp beam that has been newly replaced in the warp knitting machine, threading in of the interchangeable warp threads by the fabric take-off device pulling off the knitted fabric so that the Old warp threads pull the exchangeable warp threads through the eyelets of the needles, while the thread is being drawn in, the warp beam is set in rotation by means of a warp beam drive of the warp knitting machine so that the warp warp threads are actively released by the warp beam, and, before the take-off the knitted fabric for pulling the interchangeable warp threads through the eyelets, knocking off all stitches from knitting needles of the warp knitting machine.

As it turned out, new warp threads can be drawn in quickly and reliably in this way. After a warp beam that led the old warp threads from the The warp knitting machine has been removed and a new warp beam has been mounted on the warp knitting machine, the method according to the invention begins. The old warp threads are connected to the exchangeable warp threads of the newly exchanged warp beam, the type of the connecting method used being irrelevant. The warp threads can be connected by means of an external connecting device or a special connecting tool, but it can also be done by means of a device belonging to the warp knitting machine. The fabric take-off device pulls the knitted fabric from a knitting area of the warp knitting machine. This pulls the interchangeable warp threads through the eyes of the perforated needles.

So that the warp threads are not overloaded in the area of the eyelets, according to the invention the warp beam is simultaneously set in rotation by a warp beam drive. According to the invention, the warp beam drive can be a motor that is coupled to the warp beam. According to the invention, the method described above can be controlled by a control device of the warp knitting machine.

The method according to the invention has the advantage that downtimes of the warp knitting machine are greatly reduced compared to the manual drawing in of warp threads through the perforated needles. The need for personnel when changing warp beams and yarn consumption are reduced. In addition, according to the invention for the first time the use of a connecting device in a warp knitting machine with an extremely low error rate when threading is made possible.

According to embodiments of the invention, each old warp thread has a first section, which is part of the finished knitted fabric, and also a second section in which the old warp thread is present as a single thread that has not been knitted. When the knitted fabric is pulled off, the second section of each individual thread is also pulled off. The old warp threads are preferably connected to the replaceable warp threads in the region of their second sections.

The withdrawal of the knitted fabric is preferably synchronized with the operation of the warp beam drive, so that a thread retraction speed of the old warp threads through the eyelets of the perforated needles, caused by the withdrawal of the warp beam, coincides with a thread delivery speed at which the warp beam releases the exchangeable warp threads. This is to be understood as meaning that regulation takes place in such a way that the thread draw-in speed and the thread delivery speed coincide at least approximately and / or in terms of time average. If the thread delivery speed and the thread draw-in speed match at least approximately, then a sufficient amount of thread is always replenished through the warp beam. In order to enable a corresponding regulation, the thread delivery speed can be determined according to the invention as a function of a state of the warp beam and its speed of rotation. To determine the state of the warp beam, a thickness of a roll of goods on the warp beam can be measured according to the invention. According to the invention, the thread draw-in speed can be determined in a similar manner. According to the invention, it is also possible for previously known warping data, for example relating to a thickness of the roll of goods, to be used for the calculation.

The method according to the invention is preferably carried out in such a way that the fabric take-off device and / or the warp beam drive is operated temporarily in reverse operation while the interchangeable warp threads are being drawn in. With regard to the fabric take-off device, this means that it is temporarily not operated in the forward mode in which the knitted fabric is withdrawn from the knitted area. In the reverse operation of the fabric take-off device, the knitted fabric is delivered from the fabric take-off direction in the direction of the knitting area. This makes it easier for a connecting area of old warp threads and exchangeable warp threads to pass through the eyes of the perforated needles. Analogously to this, the warp beam can temporarily be operated in reverse mode so that the interchangeable warp threads are pulled in the direction of the warp beam.

The method according to the invention is preferably designed such that the fabric take-off device and / or the warp beam drive is operated alternately in the forward mode and in the reverse mode with a frequency of at least 1 Hz. This facilitates the passage of the connection points of the old warp threads with the replaceable warp threads through the eyes of the perforated needles. The mode of operation is such that the connection points are, so to speak, shaken through the eyelets with reduced resistance, comparable to the mode of operation of a vibrating vibrating screen.

The method according to the invention is very particularly preferably designed such that the guide bar is displaced at a frequency of at least 1 Hz along a longitudinal axis of the guide bar while the interchangeable warp threads are being drawn in. The interconnected warp threads are thus excited that their connection points can pass the needles more easily.

It is advantageous if, when carrying out the method according to the invention, the guide bar is displaced by less than one needle division along its longitudinal axis. An amplitude of the generated oscillation of the guide bar is thus limited to a relatively short offset length. This is particularly useful if only one guide bar of the warp knitting machine is to be excited, but not others, since this prevents collisions between adjacent warp threads.

According to a possible variant, the method according to the invention can furthermore be designed in such a way that a thread tension and / or an appearance of a connection point between the old warp threads and the exchangeable warp threads is monitored during the threading of the exchangeable warp threads and, if a deviation from the standard is detected, operation of the The goods take-off and / or the warp beam drive is initiated with a frequency of at least 1 Hz and / or a displacement of the guide bar along its longitudinal axis with a frequency of at least 1 Hz. A deviation from the norm is a deviation from one or more expected warp thread parameters. According to the invention, the expected warp thread parameter can be a thickness of the connection point. For example, a thickening or a thinning of the connection point can be interpreted as a deviation from the norm.

According to the invention, the connection point can also be monitored to determine whether thread splicing occurs. The deviation from the norm can also be an unexpectedly low one or increased thread tension. The thread tension is preferably measured separately on each thread pair of old warp thread and exchangeable warp thread. The monitoring of other deviations from the norm is also possible according to the invention.

According to the invention, it can be provided that the old warp threads are connected to one another with the exchangeable warp threads along a thread path between the perforated needles and the warp beam. When the knitted fabric is withdrawn, the connection points between the old warp threads and the exchangeable warp threads are then pulled through the eyes of the perforated needles. The thread path describes a path that the old warp threads and the exchangeable warp threads take. The thread path leads from the warp beam to the perforated needles.

Before the knitted fabric is drawn off, all stitches from knitting needles of the warp knitting machine are knocked off to pull the interchangeable warp threads through the eyes of the perforated needles. The knitting needles of the warp knitting machine, which can be compound needles, latch needles, point needles or knitting needles of any other type, are thus made thread-free before the method according to the invention is carried out. The connection point therefore does not have to be pulled through the hooks of the knitting needles when carrying out the method according to the invention, which could offer an additional potential for error.

A knitting bar of the warp knitting machine is particularly preferably brought into a defined position before the knitted fabric is drawn off and the knitted bar is held in the defined position while the knitted fabric is drawn off. According to the invention, the defined position can be assumed by the knitting bar when the knitting needles are knocked off.

According to the invention, the knitting bar can be a bar of the warp knitting machine that carries knitting needles. Due to the constant position of the knitting bar, the knitting needles do not catch any warp threads. The knitting needles consequently remain thread-free even while the thread is being drawn in. According to the invention, the defined position can be a knock-off position of the knitting bar. The knock-off position is a position in which the knitting bar is in the knitting process when stitches are knocked off from the knitting needles.

It is advantageous if the warp threads are connected to one another by ultrasonic welding. The old warp threads and the exchangeable warp threads are excited by vibrations in the ultrasonic range. Due to the resulting internal friction, the warp threads heat up and can fuse with one another. As it turned out, ultrasonic welding is very suitable for the quick connection of warp threads made of thermoplastic materials. The resulting connection point is not necessarily always uniform and can occasionally have a reduced resistance. As has been found, the probability of errors when pulling such a connection point through an eyelet of a perforated needle can be considerably reduced by means of the method according to the invention.

During the threading of the interchangeable warp threads, a thread speed of the warp threads is preferably limited at least temporarily to a maximum of 1 mm / s. According to the invention, this can be done by operating the fabric take-off device and / or the warp beam drive at a suitable speed. It is according to the invention possible that the thread speed of the warp threads is limited at least or precisely to a maximum of 1 mm / s when the connection point of an old warp thread and an exchangeable warp thread passes through an eyelet of a perforated needle. According to the invention, the corresponding point in time can be determined by means of a machine visual monitoring of the warp thread. According to the invention, however, the point in time can also be determined in some other way. For example, the point in time can be calculated on the basis of a thread speed and a distance between a connection point at which the warp threads are connected to one another and the eyes of the perforated needles.

The invention also relates to a warp knitting machine with a function for threading in after the warp beam change, with a fabric take-off device, with a warp beam, with a warp beam drive coupled to the warp beam and with a control device, the control device being set up to carry out the following steps: Receipt of a command for thread pull-in, after receiving the command for thread pull-in, control of the fabric take-off device for thread pull-in, so that the warp knitting machine pulls the knitted fabric off by means of the fabric take-off device, whereby the warp threads connected to the knitted fabric are pulled in, while the goods take-off device is controlled for thread pull-in, control of the warp beam drive so that the warp beam in Rotation is set and actively releases interchangeable warp threads wound on the warp beam, and, before the knitted fabric is withdrawn, control of the warp knitting machine so that all stitches from knitting needles of the warp knitting machine be knocked off. The warp threads can be the exchangeable warp threads or the old warp threads described above.

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

According to the invention, it is also possible for the warp knitting machine to have a warp thread connecting device. The warp thread connecting device is a device which is suitable for connecting warp threads to one another. According to the invention, this can be a knotting device, an ultrasonic welding device or a warp thread connecting device of any other type.

The control device is preferably set up to control the warp beam drive and the fabric take-off device in a synchronized manner in such a way that a thread draw-in speed of the warp threads from a knitting area of the warp knitting machine, which is caused by the withdrawal of the knitted fabric by the fabric take-off device, with a thread delivery speed at which the warp beam opens releases exchangeable warp threads held in front of the warp beam, agrees.

It is preferred if the control device is set up to control the goods take-off device and / or the warp beam drive during the control of the goods take-off device for threading in such a way that the goods take-off device and / or the warp beam drive alternately in forward mode and in Reverse operation is operated. This makes it possible, so to speak, to shake connecting points of the warp threads through the eyes of perforated needles of the warp knitting machine.

It is particularly preferred if the warp knitting machine has a servomotor for offsetting a guide bar of the warp knitting machine along a longitudinal axis of the guide bar, the control device being set up to control the servomotor during the activation of the fabric take-off device in such a way that the guide bar operates at a frequency of at least 1 Hz is displaced along the longitudinal axis of the guide bar. Hole needles of the warp knitting machine are preferably attached to the guide bar. The movement of the guide bar facilitates the passage of connecting points of the warp threads through the eyes of the perforated needles.

It is also advantageous if the control device is set up to receive monitoring signals relating to a thread tension and / or an appearance of a connection point between the old warp threads and the exchangeable warp threads during the threading of the exchangeable warp threads and to operate the To cause the goods take-off and / or the warp beam drive with a frequency of at least 1 Hz and / or a displacement of the guide bar along its longitudinal axis with 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 point.

• Fig. 1 eine schematische Darstellung einer erfindungsgemäßen Kettenwirkmaschine vor dem Austausch eines Kettbaums der Kettenwirkmaschine,
• Fig. 2 eine schematische Darstellung der erfindungsgemäßen Kettenwirkmaschine nach dem Austausch des Kettbaums,
• Fig. 3 eine schematische Darstellung einer Lochnadel der erfindungsgemäßen Kettenwirkmaschine beim Fadeneinzug in einer Detailansicht und
• Fig. 4 eine schematische Darstellung der Kettenwirkmaschine beim Fadeneinzug.

A preferred embodiment of the invention is illustrated in the drawings. It shows:

• Fig. 1 a schematic representation of a warp knitting machine according to the invention before the exchange of a warp beam of the warp knitting machine,
• Fig. 2 a schematic representation of the warp knitting machine according to the invention after replacing the warp beam,
• Fig. 3 a schematic representation of a perforated needle of the warp knitting machine according to the invention when threading in a detailed view and
• Fig. 4 a schematic representation of the warp knitting machine during threading.

Fig. 1 shows a schematic representation of a warp knitting machine 1 according to the invention before a warp beam 2 of the warp knitting machine 1 is replaced. only one warp thread 7 is shown as an example. Perforated needles 8 are attached to the guide bars 4. The warp threads 7 are passed through eyes 9 of the perforated needles 8.

The warp beam 2 has run empty and should now be changed. For this purpose, all of the warp threads 7 are knocked off by knitting needles 10 which are attached to the knitting bar 5. The knitting bar 5 is brought into a teeing position and then held in the teeing position. The warp threads 7 are then severed.

Fig. 2 shows a schematic representation of the warp knitting machine 1 according to the invention after the exchange of the warp beam 2. Ends of the warp threads previously located in the warp knitting machine 1 now form old warp threads 11, while warp threads running off the newly replaced warp beam 2 are referred to as exchangeable warp threads 12. An old warp thread 11 and an exchangeable warp thread 12 are shown by way of example. The warp thread connecting device 6 is brought into a thread path between the guide bars 4 and the warp beam 2. The old warp threads 11 and the exchangeable warp threads 12 are inserted into the warp thread connecting device 6 and connected to one another by this.

Fig. 3 shows a schematic representation of a perforated needle 8 of the warp knitting machine according to the invention when threading in a detailed view. According to the method according to the invention, a knitted fabric produced by the warp knitting machine is withdrawn from a knitting area of the warp knitting machine by the fabric take-off device. At the same time, a warp beam drive of the warp knitting machine sets the warp beam in rotation. The old warp threads 11 and the replaceable warp threads 12 are connected to one another in the area of an ultrasound-welded connection point 13. When the knitted fabric is withdrawn, the connection point 13 is pulled through an eyelet 9 of the perforated needle 10. In the meantime, the warp beam actively replenishes the replaceable warp thread 12. This supports the passage of the connection point 13 through the eyelet 9.

Fig. 4 shows a schematic representation of the warp knitting machine 1 during threading. The warp thread connecting device 6 is now no longer in the thread path. Likewise, the knitting needle 10 does not hold any warp threads. In order to ensure a safe passage of the connection point 13 through the eyelets 9 To enable the perforated needles 8, the fabric take-off device 3 and the warp beam drive are operated temporarily in reverse operation. This takes place precisely when a control device, not shown, of the warp knitting machine 1 detects a standard deviation with regard to a thread tension of the warp threads. For this purpose, the warp knitting machine 1 is equipped with thread tension sensors (not shown). The reverse operation is also activated when the control device detects an impermissible thickening or thinning of the connection point 13. For this purpose, the warp knitting machine 1 is equipped with a camera (not shown) for visual detection of the connection point 13.

REFERENCE LIST

1.

Warp knitting machine

2.

Warp beam

3.

Goods take-off device

4th

Guide bar

5.

Effective bar

6th

Warp thread connecting device

7th

Warp thread

8th.

Punch needle

9.

eyelet

10.

Knitting needle

11.

Old warp thread

12th

Change warp thread

13th

Junction

Claims (16)

1. Method for drawing in thread after the warp beam replacement in a warp knitting machine (1), comprising the steps:

   - connecting old warp threads (11), which are passed through eyelets (9) of guide needles (8) fastened to a guide bar (4) of the warp knitting machine (1) and form a knitted product drawn into a product draw-off device (3) of the warp knitting machine (1), to replacement warp threads (12) which belong to a warp beam (2) newly inserted into the warp knitting machine (1),

   - drawing in the replacement warp threads (12), with the knitted product being drawn off by the product draw-off device (3), so that the old warp threads (11) draw the replacement warp threads (12) though the eyelets (9) of the guide needles (8),

   characterised in that

   - during the drawing in of the replacement warp threads (12) the warp beam (2) is set into rotation by means of a warp beam drive of the warp knitting machine (1), so that the replacement warp threads (12) are actively released by the warp beam (2), and in that

   - before the knitted product is drawn off, for the replacement warp threads (12) to be drawn through the eyelets (9), all the stitches are knocked off by knitting needles (10) of the warp knitting machine (1).
2. Method according to claim 1, characterised in that the drawing off of the knitted product is synchronised with the operation of the warp beam drive, so that a thread draw-in speed of the old warp threads (11) through the eyelets (9) of the guide needles (8), effected by drawing off of the knitted product, matches a thread supply speed at which the warp beam (2) releases the replacement warp threads (12).
3. Method according to any of the preceding claims, characterised in that during the drawing in of the replacement warp threads (12) the product draw-off device (3) and/or the warp beam drive is/are operated intermittently in reverse mode.
4. Method according to claim 3, characterised in that the product draw-off device (3) and/or the warp beam drive is/are operated at a frequency of at least 1 Hz alternately in forwards mode and in reverse mode.
5. Method according to any of the preceding claims, characterised in that during the drawing in of the replacement warp threads (12) the guide bar (4) is displaced at a frequency of at least 1 Hz along a longitudinal axis of the guide bar (4).
6. Method according to claim 5, characterised in that the guide bar (4) is displaced along its longitudinal axis by less than a needle pitch.
7. Method according to any of the preceding claims, characterised in that during the drawing in of the replacement warp threads (12)

   - a thread tension and/or a visual appearance of a connection between the old warp threads (11) and the replacement warp threads (12) is monitored, and

   - if an abnormality is identified, an operation of the product draw-off and/or of the warp beam drive is initiated at a frequency of at least 1 Hz and/or a displacement of the guide bar (4) along its longitudinal axis at a frequency of at least 1 Hz.
8. Method according to any of the preceding claims, characterised in that the old warp threads (11) and the replacement warp threads (12) are joined to one another along a thread path between the guide needles (8) and the warp beam (2).
9. Method according to any of the preceding claims, characterised in that, before the knitted product is drawn off, a knit bar (5) of the warp knitting machine (1) is brought into a defined position and is kept in the defined position during the drawing off of the knitted product.
10. Method according to any of the preceding claims, characterised in that the warp threads are connected to one another by ultrasonic welding.
11. Method according to any of the preceding claims, characterised in that during the drawing in of the replacement warp threads (12) a thread speed of the knitting point is limited at least temporarily to at most 1 mm/s.
12. Warp knitting machine (1) with a function for drawing in thread after the warp beam replacement, with a product draw-off device (3), with a warp beam (2), with a warp beam drive coupled to the warp beam (2) and with a control device, whereby the control device is designed to carry out the following steps:

    - receiving a command for drawing in thread,

    - after receiving the command for drawing in thread, controlling the product draw-off device (3) for drawing in thread, so that the warp knitting machine (1) draws off the knitted product by means of the product draw-off device (3), so that warp threads connected to the knitted product are drawn in,

    characterised in that the control device is also designed to carry out the following steps:

    - during the control of the product draw-off device (3) for drawing in thread, controlling the warp beam drive, so that the warp beam (2) is set into rotation and actively releases replacement warp threads (12) wound onto the warp beam (2), and

    - before the knitted product is drawn off, controlling the warp knitting machine so that all the stitches are knocked over by knitting needles (10) of the warp knitting machine (1).
13. Warp knitting machine (1) according to claim 12, characterised in that the control device is designed to control the warp beam drive and the product draw-off device (3) in a synchronised manner, so that a thread draw-in speed of the warp threads from a knitting area of the warp knitting machine (1), which is effected by the drawing off of the knitted product by the product draw-off device (3), matches a thread supply speed at which the warp beam (2) releases the replacement warp threads (12) wound onto the warp beam (2).
14. Method according to claim 12 or 13, characterised in that the control device is designed to control the product draw-off device (3) and/or the warp beam drive during the control of the product draw-off device (3) for drawing in thread so that the product draw-off device (3) and/or the warp beam drive is/are operated at a frequency of at least 1 Hz alternately in forwards mode and in reverse mode.
15. Method according to any of claims 12 to 14, characterised in that the warp knitting machine (1) has a servomotor for offsetting a guide bar (4) of the warp knitting machine (1) along a longitudinal axis of the guide bar (4), whereby the control device is designed to control the servomotor during the control of the product draw-off device (3) so that the guide bar (4) is displaced along the longitudinal axis of the guide bar (4) at a frequency of at least 1 Hz.
16. Warp knitting machine (1) according to any of claims 12 to 15, characterised in that the control device is designed, while the replacement warp threads (12) are being drawn in,

    - to receive monitoring signals concerning a thread tension and/or a visual appearance of a connection between the old warp threads (11) and the replacement warp threads (12), and

    - if an abnormality is identified, to initiate an operation of the product draw-off and/or of the warp beam drive at a frequency of at least 1 Hz and/or a displacement of the guide bar (4) along its longitudinal axis at a frequency of at least 1 Hz.

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