KR102387218B1 - Warp knitting machine - Google Patents

Abstract

The present invention relates to the method of the warp knitting machine (1) before the warp yarns are subjected to the knitting process in the knitting area (5), wherein the warp knitting machine (1) has a knitting area (5) which produces the knitted fabric (2) during the knitting process. A warp knitting machine (1) having a yarn supply area (3) in which the warp yarns (4) extend during operation and having a system for monitoring the article quality of the made knitted fabric (2), the warp knitting machine (2) ), the system for monitoring the article quality of the knitted fabric (2) comprises an optical scanning device (7) and a data processing unit, the data processing unit being set up to generate an evaluation signal relating to the article quality of the knitted fabric (2) . According to the invention the optical scanning device (7) is arranged to capture a moving image of the at least one warp yarn (4) in the yarn supply area (3), the data processing unit being able to capture at least one image from the moving image It is set up to find out the actual traveling speed of the warp yarn 4 of , to evaluate the actual traveling speed in the evaluation step, and to generate an evaluation signal depending on the evaluation result of the evaluation step.

Description

Warp knitting machine {WARP KNITTING MACHINE}

The present invention relates to a knitting area in which a warp knitting machine produces a knitted fabric during a knitting process, wherein the warp threads are removed during operation of the warp knitting machine before going through the knitting process in the knitting area. A warp knitting machine having an extending thread supply area and a system for monitoring the article quality of a made knitted fabric, the system for monitoring the article quality of a made knitted fabric, the system comprising an optical scanning device and a data processing unit a data processing unit, the data processing unit being set up to generate an evaluation signal relating to the quality of the article of the knitted fabric.

The warp knitting machine is equipped with knitting tools, which process the warp yarns into a fibrous material, ie, a so-called knitted fabric during the knitting process. This is done in the knitting area of the warp knitting machine. The warp yarns are passed through the yarn feeding area beforehand. Knitting is made through a nose forming process. The warp knitting machine has a plurality of bars, each of which is arranged with a plurality of knitting tools. Since multiple knitting tools can be moved simultaneously using one bar, multiple noses are formed simultaneously during the knitting process. That is the reason for the very high production performance of the warp knitting machine.

Systems for monitoring the quality of articles of knitted fabrics made are known from the prior art. DE 37 33 791 C2 thus describes a system for monitoring the quality of knitted fabrics using an optical scanning device. The optical scanning device faces the fabric made. In this way article errors can be recognized. However, in the edge region of the knitted fabric, it is very difficult to reliably recognize errors in nose formation using an image processing method. The reason is, among other things, that the edge regions of knitted fabrics often have an irregular, loose structure and tend to curl. The knitted fabric made also has an inward bending behavior, ie it tapers more and more in the direction of the article winding device of the warp knitting machine. This also makes it difficult to recognize errors. Therefore, in particular, thread breakage cannot be recognized reliably.

A chopper bar is sometimes used in warp knitting machines to reliably detect yarn breakage even in the edge region of knitting. Each chopper bar seals against one individual yarn in the yarn feed area during operation. If the yarn breaks, the chopper bar assigned to the yarn can tilt, thereby triggering an error signal. Since each warp has to be assigned its own chopper bar, this approach is structurally very expensive.

It is also known to arrange a light barrier in front of the knitted area. A system with a light barrier is known from DE 34 01 582 A1. If the yarn breaks during the knitting process, the yarn is generally thrown out of the knitting area and passed through the monitoring area of the light barrier. However, not all yarn break errors can be caught with a light barrier, since each broken warp yarn does not forcibly pass through the light barrier's monitoring area. Also, in order to blow the warp yarns out of the yarn feeding area in the direction of the light barrier, a blower must be provided during operation of the light barrier.

All systems described above are often used in combination. Nevertheless, some kinds of knitting errors cannot be recognized. If, for example, the warp yarns are interlooped in the edge region of the knitting, this is inconspicuous, since no yarn breakage occurs here. In an interlooping error the warp yarn is caught in the nose where the warp yarn is not assigned according to the lapping plan.

Therefore, it is an object of the present invention to provide a warp knitting machine that reliably recognizes knitting errors such as yarn breakage and looping errors, and other quality deficiencies of the knitted fabrics made.

The object is arranged so that the optical scanning device is capable of capturing a moving image of at least one warp yarn in the yarn feeding area, and the data processing unit determines from the moving image a yarn running speed of at least one warp yarn ( thread running speed), to evaluate the actual running speed in an evaluation step, and to generate an evaluation signal in dependence on the evaluation result of the evaluation step.

According to the present invention, the actual running speed is evaluated. The actual running speed is sometimes referred to as the actual feeding speed. It indicates the speed at which the warp yarn is moved in the direction of the knitting area. Actual travel speed may be negative in the short term in special cases. Through the evaluation of the yarn running speed of the warp yarns, it is also made to reveal types of errors such as yarn breakage, twisting errors and other quality limitations such as, for example, reduction in tension in the knitted fabric produced. Errors can be recognized early, so that the machine can be stopped quickly in case of an error. The evaluation becomes possible only when the optical scanning device is directed towards the warp yarns in the yarn supply area instead of towards the fabric produced. Alternative means for error recognition, for example chopper bars or light barriers, can be omitted entirely. A number of errors that could be found only through observation of the fabricated knitted fabric in the prior art can be recognized through the evaluation of the yarn running speed of the warp yarns.

If, for example, the yarn running speed of the warp yarn drops a lot, it can be estimated from this that yarn breakage exists. If the yarn running speed of the warp yarn drops slightly, the reason may be that the warp yarn is twisted incorrectly. Incorrect connection can also lead to an unexpected increase in the actual driving speed.

Frequently, the loop, once erroneously executed, continues over multiple rows of noses, so that the warp yarn run speed continuously deviates from the expected yarn run speed. According to a possible embodiment of the present invention, if the yarn running speed of one warp yarn deviates from the previously measured average yarn running speed of the warp yarn, it is possible for the data processing unit to grade the knitting quality as erroneous. According to the present invention, it is also possible to evaluate the yarn running speed of a plurality of warp yarns.

The optical scanning device preferably captures the warp yarns in the area of the warp knitting machine arranged immediately upstream of the knitting area. The optical scanning device is preferably a camera, more precisely a moving image camera. A camera according to a possible embodiment of the invention may be a line scan camera. Alternatively, a laser scanning system may be provided for optical scanning of the warp yarns.

The data processing unit is responsible for judging the quality of knitting. The determination may be performed in a number of ways according to an embodiment of the present invention. In this way, according to the present invention, it is possible to output the quality factor together with the evaluation signal. Based on the quality factor, the operator can determine whether it is necessary to stop the warp knitting machine to perform calibration. The quality factor may be output at regular intervals according to the present invention. Alternatively, it may be provided that an evaluation signal is output only when a predefined quality threshold is exceeded. According to the invention, it is also possible for the warp knitting machine to be set up to stop the knitting process when a predefined quality threshold is exceeded.

Preferably, the data processing unit is set up to compare the temporal progression of the yarn running speed of the at least one warp yarn in the yarn feeding area with a motion profile stored in the data processing unit during the evaluation step. The temporal progression of the actual running speed reproduces the measured real running speed of the warp yarn at different time points during operation.

The motion profile reproduces the desired temporal progression of the yarn running speed of the warp yarn. The desired temporal progression of the actual running speed may be determined through measurement or may be calculated. Too large a deviation in the temporal progression of the actual running speed from the motion profile indicates poor quality of the knitting or article error. The data processing unit, according to the present invention, is configured to reduce the reduced article quality of the knitted fabric when the difference between the temporal progression of the actual running speed and the stored motion profile exceeds a predefined limit value at one or more time points. or configured to generate an evaluation signal indicating an article error.

According to the invention, one own movement profile can be stored for each of the different warp yarns.

It is advantageous if the data processing unit uses a synchronization signal of the warp knitting machine in order to reconcile the movement profile with the actually measured temporal progression of the movement speed of the warp yarn. The nose formation process is a cyclic process. Thus, for example, the synchronization signal can always be generated when this process is started anew. The synchronization signal can be revealed using measurements at different parts of the warp knitting machine, but preferably the measurements are performed on the main shaft. The main shaft is a drive shaft arranged in a machine bed of the warp knitting machine, which drives the bars of the warp knitting machine.

When the data processing unit is set up to obtain pattern setting information via a data interface or via input means of the warp knitting machine, to calculate the movement profile from the pattern setting information and to store the movement profile in the data processing unit It is advantageous. In this way, the desired pattern setting may be input through an input means such as a keyboard or a touch screen according to the present invention. The pattern setting information may also be transmitted to the data processing unit via a data interface, for example a network interface, or a reading device for a data carrier. Through the pattern setting information, it is defined how the guide bars of the warp knitting machine should be moved during operation.

The movement of the guide bars determines the wrapping pattern in the knitted fabric made during the knitting process. From the pattern setting information, the data processing unit calculates a time-dependent warp yarn consumption, and therefore also calculates a time-dependent yarn running speed of the warp yarns. From this, an ideal movement profile, which is stored in the data processing unit, arises.

The data processing unit is preferably set up to acquire a movement profile of the at least one warp yarn through analysis of a moving image of the at least one warp yarn and to store the movement profile in the data processing unit. This is preferably done in such a way that the yarn running speed of at least one of said warp yarns is found during one complete pattern setting cycle. From this the motion profile arises. According to the invention, measurements can be performed over a number of pattern setting cycles and averaged to obtain the motion profile.

According to a particular embodiment of the invention, the data processing unit is set up to evaluate the speed difference between the two warp yarns in the evaluation step. For this purpose, the speed of the first warp yarn and the speed of the second warp yarn in the yarn feeding area are measured. From this the speed difference is formed. According to embodiments of the present invention, it may occur as follows: if the speed difference exceeds a predefined threshold, it indicates a quality decrease or quality error, indicating a reduced quality of knitting or an article error. An evaluation signal is generated.

According to another embodiment of the present invention, the speed difference of a plurality of pairs of warp yarns is revealed via the data processing unit. The resulting speed differences may be averaged or added according to the invention. In a next step, the data processing unit determines, according to the present invention, whether the result of the averaging or the addition exceeds a predefined limit value.

Preferably, the data processing unit is configured to filter out a disturbance spectrum from the temporal progression of the actual running speed of the at least one warp yarn in the evaluating step, isolate at least one frequency peak from the disturbance spectrum, and It is set up to compare the frequency and/or amplitude of one frequency peak with reference data. It was found upon measurement that the temporal progression of the yarn running speed of the warp yarns did not depend solely on the pattern setting of the knitted fabric. The vibration of the components of the warp knitting machine can greatly affect the yarn running speed of the warp yarns. Also through the action of the knitting tools on the warp yarns—the knitting tools themselves undergo vibrations—the temporal progression of the yarn running speed is affected.

The quality of the knitting can be determined using the analysis of the frequencies that appear. According to the present invention, the interference spectrum can be filtered out in the temporal progression of the actual running speed. This can be done, for example, using Fourier analysis or in another suitable manner. The interference spectrum typically includes frequencies that cause article errors. The disturbance spectrum varies from machine to machine and can be determined by measurement. Individual frequency peaks are isolated from the disturbance spectrum and subsequently compared to reference data. The reference data characterizes at least one frequency peak typical for the occurrence of a particular article error. When a sufficient match between the reference data and the isolated frequency peaks occurs, the data processing unit generates an evaluation signal indicative of an article error in the knitting or a reduced quality of the knitting.

The invention also relates to a method for inspecting the quality of a knitted fabric in a warp knitting machine. The method has the following steps: capturing a moving image of at least one warp yarn in a yarn feeding area of a warp knitting machine, determining a yarn running speed of at least one warp yarn in the yarn feeding area, evaluating In the step of evaluating the actual running speed, and generating an evaluation signal related to the quality of the knitted fabric depending on the evaluation result of the evaluation step. This method can be applied in the warp knitting machine described above.

Preferably, the temporal progression of the yarn running speed of the at least one warp yarn in the yarn feeding region during the evaluation step is compared with a motion profile. It is advantageous if the motion profile is calculated from the pattern setting information before the evaluation step. Alternatively, however, the motion profile may also be acquired through analysis of a moving image of the at least one warp yarn before the evaluation step.

According to the present invention, the speed difference between the two warp yarns can be evaluated during the evaluation step. However, in the evaluation step, a disturbance spectrum is filtered out in the temporal progression of the movement speed of the at least one warp yarn, at least one frequency peak is isolated from the disturbance spectrum, and the frequency and/or amplitude of the at least one frequency peak is It is advantageous when compared with reference data.

The present invention also relates to a system for monitoring the article quality of a knitted fabric made by a warp knitting machine, the system for monitoring the article quality of the knitted fabric comprising an optical scanning device and a data processing unit, the data processing unit comprising: and to generate an evaluation signal related to the article quality of the knitted fabric. This system can be used in the warp knitting machine according to the present invention. According to the present invention, in this system, the optical scanning device is provided for capturing a moving image of at least one warp yarn in the yarn feeding area of the warp knitting machine, and the data processing unit is configured to capture the at least one warp yarn from the moving image. It is set up to determine the actual traveling speed of , to evaluate the actual traveling speed in the evaluation step, and to generate an evaluation signal depending on the evaluation result of the evaluation step. The data processing unit of the system for monitoring article quality is preferably set up to evaluate the speed difference between the two warp yarns in the evaluation step to reveal an evaluation result. In addition, in the evaluation step, the data processing unit isolates at least one frequency peak from the disturbance spectrum to filter out the disturbance spectrum from the temporal progression of the actual running speed of the at least one warp yarn, and It is advantageous if it is set up to compare frequency and/or amplitude with reference data.

The drawings represent preferred embodiments of the present invention.

1 shows a warp knitting machine having a system for monitoring the article quality of a knitted fabric;
2 shows a time-velocity graph with a measured temporal progression of the yarn running speed of the warp and with a predefined motion profile, FIG.
3 shows a frequency graph having a frequency peak measured during temporal progression of a warp yarn running speed and a reference peak.

1 shows a warp knitting machine 1 having a system for monitoring the article quality of a knitted fabric 2 . The warp knitting machine 1 has a yarn feeding area 3, in which the warp yarns 4 extend in the yarn feeding area during operation of the warp knitting machine before the warp yarns are subjected to a knitting process. In the knitting area 5 of the warp knitting machine 1 , the knitting fabric 2 is made by knitting tools fixed to the bars 6 . The warp knitting machine 1 has three optical scanning devices 7 , which are moving image cameras. The optical scanning devices 7 face the warp yarns 4 . During operation of the warp knitting machine 1, the warp yarns 4 have a variable yarn running speed. The optical scanning device 7 takes a moving image of the warp yarns 4 and transmits the moving image to a data processing unit (not shown). The data processing unit analyzes the moving image and derives an evaluation result related to the quality of the knitted fabric 2 from the yarn running speeds of the warp yarns 4 . Subsequently, the data processing unit outputs the evaluation result through an evaluation signal.

2 shows a time-velocity graph (8) with a motion progression curve (9) of a warp yarn and with a motion profile curve (10). The time-velocity graph (8) has a time axis (11) and a velocity axis (12). The motion progression curve 9 reproduces the measured yarn running speed of the warp yarn at different time points. The exercise progress curve 9 is indicated by a dotted line. The motion profile curve 10 reproduces the temporal progression of the yarn running speed that would be expected in the warp yarn during error-free operation of the warp knitting machine. The motion profile curve 10 is indicated by a broken line. The data processing unit of the warp knitting machine reveals the difference between the motion progression curve (9) and the motion profile curve (10). When the difference is too large, the data processing unit outputs an evaluation signal informing the warp knitting machine that an erroneous knitted fabric is produced. This causes the warp knitting machine to stop the knitting process.

3 shows a frequency graph 13 with a frequency peak 14 and with a reference peak 15 . The frequency graph 13 has a frequency axis 16 and an amplitude axis 17 . A frequency peak (14) was found from the measured temporal progression of the yarn running speed of the warp yarn. The frequency peak 14 is indicated by a dotted line. The reference peak 15 is expected if there is a certain kind of error in the warp knitting machine. The reference peak 15 is indicated by a broken line. The frequency peak 14 is compared with the reference peak 15 by the data processing unit of the warp knitting machine. When the frequency and amplitude of the frequency peak 14 and of the reference peak 15 have only a slight deviation, the data processing unit outputs an evaluation signal informing the warp knitting machine that an erroneous knitted fabric is being produced. This causes the warp knitting machine to stop the knitting process.

1: Warp knitting machine
2: knitting
3: thread supply area
4: Warp
5: Knitting area
6: bar
7: optical scanning device
8: Time-Speed Graph
9: Exercise progress curve
10: motion profile curve
11: time base
12: speed axis
13: frequency graph
14: frequency peak
15: reference peak
16: frequency axis
17: amplitude axis

Claims (15)

A warp knitting machine (1) comprising:
a knitting area (5) in which the warp knitting machine (1) produces a knitted fabric (2) during the knitting process;
a thread supply area 3 in which the warp threads 4 extend during operation of the warp knitting machine 1 before the warp threads undergo the knitting process in the knitting area 5; and
having a system for monitoring the article quality of the made knitted fabric (2);
Said system for monitoring said article quality of said fabricated knitted fabric (2) comprises an optical scanning device (7) and a data processing unit, said data processing unit receiving an evaluation signal related to said article quality of said knitted fabric (2) set up to generate
The optical scanning device 7 is arranged so as to be able to capture a moving image of the at least one warp yarn 4 in the yarn feeding area 3 , the data processing unit being able to capture at least one from the moving image set up to find out the thread running speed of the warp yarn (4) of
The data processing unit is configured to isolate at least one frequency peak ( 14 ) from the disturbance spectrum, and to filter out a disturbance spectrum in the temporal progression of the yarn running speed of the at least one warp yarn ( 4 ) in the evaluation step; A warp knitting machine (1), characterized in that it is set up to compare the frequency and/or amplitude of the frequency peak (14) of , with reference data. The method of claim 1,
The data processing unit is set up to compare the temporal progression of the yarn running speed of the at least one warp yarn 4 in the yarn feeding area 3 with a motion profile stored in the data processing unit during the evaluation step. Warp knitting machine (1), characterized in that it becomes. 3. The method of claim 2,
The data processing unit is configured to obtain the pattern setting information through a data interface or through an input means of the warp knitting machine 1, calculate the movement profile from the pattern setting information, and store the movement profile in the data processing unit A warp knitting machine (1), characterized in that it is set up to do so. 3. The method of claim 2,
wherein the data processing unit is set up to acquire the movement profile of at least one warp yarn (4) through analysis of the moving image of the at least one warp yarn (4) and to store the movement profile in the data processing unit A warp knitting machine characterized by (1). The method of claim 1,
A warp knitting machine (1), characterized in that the data processing unit is set up to evaluate the speed difference between the two warp yarns (4) in the evaluation step. delete A method for inspecting the quality of a knitted fabric (2) in a warp knitting machine (1), comprising:
The method is
- capturing a moving image of at least one warp yarn (4) in the yarn feeding area (3) of the warp knitting machine (1);
- finding the thread running speed of the at least one warp thread (4);
- evaluating the actual running speed in the evaluation step;
- generating an evaluation signal related to the quality of the knitted fabric (2) depending on the evaluation result of the evaluation step;
In the evaluation step, a disturbance spectrum is filtered out from the temporal progression of the yarn running speed of at least one of the warp yarns (4), at least one frequency peak (14) is isolated from the disturbance spectrum, and the at least one frequency peak (14) ), the frequency and/or amplitude of are compared with reference data. 8. The method of claim 7,
A method for inspecting the quality of a knitted fabric, characterized in that during the evaluation step the temporal progression of the yarn running speed of the at least one warp yarn in the yarn feeding area (3) is compared with a motion profile. 9. The method of claim 8,
A method for checking the quality of a knitted fabric, characterized in that before the evaluating step the motion profile is calculated from pattern setting information. 9. The method of claim 8,
Method (1) for inspecting the quality of a knitted fabric, characterized in that before the evaluation step the movement profile is acquired through analysis of the moving image of at least one of the warp threads (4). 8. The method of claim 7,
A method (1) for inspecting the quality of a knitted fabric, characterized in that during the evaluation step the speed difference between the two warp yarns (4) is evaluated. delete A system for monitoring article quality of a knitted fabric (2) made by a warp knitting machine (1), comprising:
The system for monitoring the article quality of the knitted fabric (2) comprises an optical scanning device (7) and a data processing unit, the data processing unit generating an evaluation signal relating to the article quality of the knitted fabric (2) set up to do
The optical scanning device (7) is provided for capturing a moving image of at least one warp yarn (4) in the yarn supply region (3) of the warp knitting machine (1), and the data processing unit is configured to capture at least from the moving image set up to reveal the actual traveling speed of one of the warp yarns (4), to evaluate the actual traveling speed in an evaluation step, and to generate an evaluation signal depending on the evaluation result of the evaluation step;
The data processing unit is configured to isolate at least one frequency peak ( 14 ) from the disturbance spectrum, and to filter out a disturbance spectrum in the temporal progression of the yarn running speed of the at least one warp yarn ( 4 ) in the evaluation step; A system for monitoring article quality of a knitted fabric, characterized in that it is set up to compare the frequency and/or amplitude of the frequency peak (14) of 14. The method of claim 13,
A system for monitoring article quality of knitted fabrics, characterized in that the data processing unit is set up to evaluate the speed difference between the two warp yarns (4) in the evaluation step. delete

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