JP2020081888A - Device, method and sewing machine for monitoring yarn releasing - Google Patents

Abstract

To provide a method capable of measuring a bobbin thread consumption amount during sewing and finding out errors of a seam pattern.SOLUTION: A device monitors releasing of a bobbin 30 thread wound around a lower thread bobbin 20 in a sewing machine 1. In order to provide a device that can reliably measure a rotation movement and a rotation direction of the bobbin and reliably measure a thread consumption amount in the sewing machine, the device has a field generating means to generate a field that can be fitted to the bobbin so as not to rotate and allows non-contact scanning.SELECTED DRAWING: Figure 4

Description

The present invention relates to a device for monitoring the yarn wound on a bobbin.

Furthermore, the present invention relates to a sewing machine provided with a device for monitoring the unwinding of the thread wound around the bobbin.

In addition, the invention also relates to a method for monitoring the unwinding of a thread wound on a bobbin.

In the sewing machine, a device that monitors the amount of thread wound around the bobbin or the remaining amount of thread, and a device that measures the amount of thread consumed during sewing are used to detect defects (misses) in the stitch pattern. used. Generally, in a sewing machine, an upper thread and a lower thread wound around a bobbin are used to form a seam.

Influencing factors such as material, machine settings, machine tolerances and wear can cause, for example, thread breaks, missed seams, or apparently missed seams (hereinafter referred to as "apparent seams"). there is a possibility. A seam mistake refers to a seam with a missing seam pattern caused by improper winding of the upper thread and the lower thread. If there are too many seam mistakes in the seam pattern, the tensile strength of the seam can be significantly reduced. Apparent seam refers to the partial or complete absence of bobbin threads in the finished seam. Here, the upper thread is held by the material in the form of a stitch pattern. The apparent seam has almost no tensile strength of the correct seam. In particular, regarding seams that are important for safety or seams that support a load, mistakes in seams and apparent seams are not allowed, so it is necessary to reliably identify them. Since post-quality control by optical system is not reliable, post-quality control must be done manually. This is a considerable effort and it is especially necessary to monitor the seams or threads in the sewing machine while sewing.

Sewing machine gripper systems have little available space, and due to the pendulum motion of the bobbin holding the thread in various gripper systems, such monitoring is extremely difficult. Prior art monitoring systems are only able to detect the rotation and direction of rotation of the bobbin during unthreading during the sewing process. If the thread breaks or the winding of the upper thread and the lower thread does not end correctly, the bobbin may stop or bobbin oscillating motion/pendulum motion may occur. The bobbin swaying motion/pendulum motion can be reliably detected partially by the existing system based on the rotation and the direction of rotation of the bobbin. No thread is consumed in accordance with the sewing process, but the bobbin will continue to rotate if there is a missed seam or any apparent seam due to the bobbin's own weight and the thread wrapped around the bobbin. In this case, existing systems cannot reliably detect such mistakes and, in some cases, do not classify them as defects.

Residual yarn monitoring using optical sensors is also known from the prior art. From DE 2007 021 300A1 there is known a device for monitoring the amount of yarn remaining on a bobbin. In this device, an optical sensor is used to detect that a particular area of the monitored bobbin is not covered by yarn. The yarn must be properly wound on the bobbin beforehand so that the desired amount of residual yarn is present on the bobbin after the monitoring area is exposed. A problem with this device is the use of optical sensors, in particular light and dark sensors, in addition to the inevitable predetermined winding of the thread on the bobbin. They are dirty and have to be cleaned regularly because of the sewing dust, gripper lubrication, and possibly compressed air that is contaminated with water or oil, which is generated during the sewing process.

Therefore, an object of the present invention is to provide a device that enables reliable measurement of the rotational movement and rotational direction of a bobbin in a sewing machine, and enables measurement of yarn consumption. A further object of the present invention is to propose such a sewing machine and a method by which an accurate thread consumption can be reliably measured in the sewing machine and a mistake in the stitch pattern can be found.

The object of the device of the invention for monitoring the unraveling of the thread wound on the bobbin in a sewing machine is to provide a field generating means for generating a non-contact scannable field which can be non-rotatably mounted on the bobbin. It is solved by providing to. This allows reliable bobbin and yarn monitoring without the need for error-prone optical measurements.

According to one embodiment of the present invention, the present invention comprises detection means for detecting the non-contact scannable field, wherein the detection means is capable of the non-contact scannable according to a rotation angle of the bobbin. It is configured to detect changes in the field. The detection means can reliably determine (detect) the rotation and the rotation direction of the bobbin. This makes it possible to reliably measure the amount of yarn consumed.

Furthermore, in an advantageous embodiment of the invention, said field generating means comprises a magnet, in particular a permanent magnet, and said detecting means comprises a magnetic field sensor. The use of magnetic fields has advantageously replaced conventional optical systems. Measuring magnetic fields with magnetic field sensors has also become much easier than with optical systems. Due to the small space in the gripper system area, it is difficult to have an unobstructed space between the sensor and the bobbin, but in one embodiment of the invention, there need not be an unobstructed space between the sensor and the bobbin. .. Also, no special optical marks, coloring or the like are required. External stray light is also negligible compared to optical systems. The advantage is that no permanent magnet field needs to be generated, which leads to further error reduction.

Furthermore, according to the present invention, since the magnetic field strength sharply decreases when the bobbin is inserted in the wrong direction, the bobbin inserted in the opposite direction can be detected by the magnetic field strength determined by the magnetic field sensor. Is. According to the invention, the insertion of a new bobbin is confirmed with a magnetic field sensor.

In a further embodiment, the NS axis of the magnet is arranged perpendicular to the axis of symmetry of the bobbin. As a result, when the magnet rotates about the axis of symmetry of the bobbin, a relatively large magnetic field change corresponding to a small rotation angle change occurs in the magnetic field. This makes it possible to detect even small rotation angle changes. Therefore, within the scope of the invention, the rotation angle of the bobbin by the magnetic field sensor can be clearly determined in the north direction of the magnetic field. Further, in the embodiment of the present invention, the upside-down winding direction of the lower thread can be similarly detected based on the rotation direction.

According to a further preferred embodiment of the invention, said magnet is formed as a bar magnet or a diametrically magnetized magnet, in particular as a diametrically magnetized hollow cylinder, said magnet being especially internal to said bobbin. It is located in. The diametrically magnetized hollow cylinder in the bobbin can be arranged such that the bobbin and the hollow cylinder have the same axis of symmetry and rotate about this axis during rotation of the bobbin. Thereby, the change in the rotation angle of the bobbin can be calculated particularly easily from the change in the magnetic field, with the advantage that there is no change in the field caused by the different rotation axes.

In an advantageous embodiment, if a bar magnet is used, it is embedded in one of the two end faces of the bobbin.

In another embodiment of the present invention, an evaluation unit for evaluating the magnetic field signal detectable by the detection unit is provided, and the evaluation unit affects (controls) the rotation of the bobbin. The evaluation means calculates the rotation or the rotation direction of the bobbin by a certain logic. As a great advantage, they allow the bobbin to stop rotating without intermediate steps depending on the measured values and control the bobbin rotation so that the sewing process can be interrupted.

The problem of the sewing machine according to the invention with a bobbin for threads is solved by the machine comprising a device according to the invention, which device is preferably non-rotatably mounted on said bobbin. This proposes a sewing machine with which it is possible to reliably monitor the bobbin and thus the thread consumption, without the use of an optical system.

In an advantageous embodiment of the sewing machine according to the invention, the sewing machine comprises a further bobbin for further threads and a further device, which further device is preferably non-rotatably mounted on said further bobbin. This enables more suitable monitoring of the sewing pattern of the sewing machine. This is because typically two threads are used in one seam and a seam mistake only partially affects one thread.

According to a further embodiment of the sewing machine of the present invention, the bobbin is configured as a bobbin bobbin for winding a bobbin thread, and the further bobbin is configured as a measuring wheel for feeding an upper thread. There is. Here, the upper thread travels from the outside of the cone winding of the thread to the sewing machine as if it were an endless thread. To measure the upper thread consumption, the upper thread runs on the measuring wheel. This makes it possible within the scope of the invention to monitor the sewing process of a typical stitch pattern with upper and lower threads, such as double lock stitches or lock stitches. This is particularly advantageous in the case of a sewing machine that is not equipped with a CNC controlled device. In a particular embodiment of the invention, it is possible here to detect the upper thread consumption.

Furthermore, it is possible in an embodiment of the invention that the sewing machine is designed such that the evaluation means is configured for measuring the length of the residual thread. Therefore, the logic of the evaluation means is designed such that the consumption of the yarn wound on the bobbin can be calculated by the rotation, the rotation direction and the rotation angle of the bobbin. Due to the accurate measurement of the consumption and the maximum length of the thread that can be wound based on the limited dimensions of the bobbin, the length of the available residual thread on the bobbin is dependent on the consumption of the bobbin thread. Can be calculated at any time.

Properly wound bobbins must be used to reliably detect yarn consumption. The thread must be wound parallel to the bobbin. Here, one complete layer of yarn is always wound parallel to each other over the full width of the bobbin before the next layer is started. This results in bobbin unwinding radius changes that can be predicted according to the Archimedes spiral.

In the case of a non-CNC-controlled sewing machine, according to the invention, according to the invention, at the earliest after each stitch and via the logic of the evaluation means for evaluating (analyzing) the results of monitoring the upper and lower threads. Thread breaks and apparent seams are clearly visible at the latest after seams are completed. This is because the consumption amount of the upper thread is different from that of the lower thread.

In the case of a CNC-controlled automatic sewing machine, the logic of the evaluation means according to the embodiment of the present invention calculates and evaluates the theoretical consumption amount of the thread, particularly the upper thread and the lower thread, based on the pitch between the stitches. Is further designed to be used with. As a result, the use of the present invention has the great advantage that the user can also recognize stitch mistakes. This is because there is a difference between the theoretical thread consumption and the measured thread consumption of the upper and lower threads.

In a further embodiment of the sewing machine according to the invention the sewing machine comprises output means for outputting the signal of the evaluation means. This has the great advantage that the output means can output an error message to the user if the evaluation means detects a thread break, a stitch defect or an apparent seam. This, within the scope of the invention, makes it possible to safely remove the sewn product from the manufacturing process and to classify it as a wound.

Further, the output means enables a timely reference instruction of the evaluation means regarding necessary bobbin exchange. This prevents, for example, the start of a sewing process in which there are too few bobbin threads, which inevitably lead to seam mistakes.

The subject of the method in the case of the method of the invention for monitoring the unwinding of a thread wound on a bobbin in a sewing machine is that the field generating means for generating a non-contact scannable field, in particular a magnetic field, is applied to said bobbin. It is mounted non-rotatably and is solved by continuously measuring the magnetic field. This makes it possible to directly and continuously determine the rotation of the bobbin, in particular the rotation angle and the direction of rotation, without having to determine the rotation of the bobbin on the basis of optical marks or the like.

In a particularly advantageous embodiment of the method according to the invention, the rotation angle and the rotation speed of the bobbin are continuously measured and evaluated to generate an evaluation signal and a user output signal which influence the rotation of the bobbin. This allows the user of the method to take any necessary precautions such as changing the bobbin or stopping the sewing process in order to obtain the correct stitch pattern.

Further, according to another embodiment, the consumption amount and/or the residual yarn amount of the yarn wound around the bobbin is calculated. Thereby a comparison can be made on the basis of the calculated and measured yarn length or on the basis of the two measured yarn lengths, with which the seam pattern can be reliably confirmed.

According to the present invention, the logic of the evaluation means can calculate the rotation, the rotation direction, and the yarn consumption amount based on the measured rotation angle. In order to measure the yarn consumption, the logic, after bobbin exchange, first starts with the assumption of the largest possible unwinding radius of the bobbin. During the first sewing process, according to the invention, the logic detects the bobbin by relying on the maximum possible unwinding radius to verify that the bobbin was completely filled when the bobbin was inserted. The changed rotation angle is compared with the expected rotation angle change. According to the invention, the logic can calculate the yarn consumed using a correction factor for unwinding radius change by starting from a fully filled bobbin and emptying the bobbin.

According to a further embodiment, at least one further field generating means for generating an additional non-contact scannable field comprises monitoring an additional bobbin wound with an additional thread on the sewing machine. The non-rotatably mounted bobbin measures the further field continuously to measure the consumption of the further thread wound on the further bobbin, and the consumption of the thread wound on the bobbin. Compare with quantity. With this, in particular, the upper thread consumption amount and the lower thread consumption amount can be compared with each other, and a mistake in the stitch can be directly determined, whereby the sewing target can be used at the latest after completion of the stitch. , Can be removed from the manufacturing process. Within the scope of the invention, the further bobbin can also be designed only as a measuring wheel for feeding the upper thread. According to the present embodiment, the upper thread travels from the outside of the thread cone winding to the sewing machine as if it were an endless thread. To measure the upper thread consumption, the upper thread runs over the measuring wheel.

The invention enables monitoring of the thread wound on the bobbin of the sewing machine, in particular by means of a magnet embedded in the bobbin. According to the invention, the magnetic field of the magnet is detected by a magnetic field sensor connected to the logic and evaluated. This allows the logic to calculate the rotation, rotation direction and rotation angle of the bobbin during the sewing process, in addition to calculating the consumption of the thread wound on the bobbin based on the rotation angle of the bobbin. it can. By monitoring the lower thread wound on the bobbin and the upper thread wound on a further bobbin, the upper thread consumption and the lower thread consumption can be determined at any time. Within the scope of the invention, the upper thread can alternatively or additionally be fed as a never-ending thread from outside the thread cone winding to the sewing machine. In this case, the measurement of the upper thread consumption is performed within the scope of the invention via a measuring wheel on which the upper thread runs. By comparing the bobbin's consumed bobbin thread with the needle thread consumption and/or the pitch between the stitches of an automatic CNC sewing machine, Logic can help the sewing process with respect to thread breaks, missed seams, or apparent seams. Can be monitored. In addition to that, the size of the bobbin, and thus the maximum wrappable thread length, makes it possible to calculate the available remaining thread length of the bobbin thread on the bobbin at any time, based on the thread consumption of the bobbin thread. ..

The invention is explained by way of example by means of preferred embodiments with reference to the drawings, further advantageous details being shown in the figures of the drawing.

Functionally identical parts are designated by the same reference numerals.

Details in the figures of the drawing are as follows.

FIG. 6 is a diagram including magnetic field lines of a bobbin of the present invention with a circular diametrical magnet in a cut bobbin case. FIG. 6 is a view of a bobbin of the present invention cut with a circular diametrical magnet. FIG. 7 is a diagram including the magnetic field lines of a measuring wheel with a circular diametrical magnet, for monitoring needle thread consumption. FIG. 4 is a schematic diagram of how the device of the present invention operates based on a diagram of yarn flow through a consumption monitoring device.

FIG. 1 shows a bobbin 2 of the invention with a circular diametrical magnet 7 in a cut bobbin case 15, including the magnetic field lines 14. Here, the diametrical magnet 7 serves as a field generating means 5 for generating a non-contact scannable field 4. The diametrical magnet 7 is formed as a ring and is embedded in the end face 16 of the bobbin 2 such that the NS axis 11 of the magnetic field 14 generated by the diametrical magnet 7 is arranged perpendicular to the axis of symmetry 10 of the bobbin 2. ing.

FIG. 2 shows another bobbin 2 of the invention cut with a circular diametrical magnet 7. Here, the magnet 7 is formed as a rotationally symmetric hollow body 9 and is embedded in the end surface 16 of the bobbin 2. Therefore, the magnet 7 and the axis of symmetry 10 of the bobbin 2 coincide, and when the bobbin 2 rotates, the two components 2, 7 rotate about the same axis, ie the axis of symmetry 10. Thereby, the change in the rotation angle of the bobbin 2 can be easily determined from the measurement of the change in the field of the magnetic field 14.

FIG. 3 shows a measuring wheel 17 with a circular diametrical magnet 7 together with the magnetic field lines of the magnetic field 14. Here, according to the invention, the measuring wheel 17 is referred to as a (further) bobbin 2'or a needle thread bobbin 20'. On one end face of the measuring wheel 17, which is used in particular for the monitoring of the further thread 3 ′ or the upper thread 30 ′, a further magnetic field generating means 5 ′ for generating a further non-contact scannable field 4 ′ is circular. It is embedded as a magnet 7. In addition to other aspects of the surface condition of the bobbin, the operation of the rotation monitoring of the measuring wheel 17 for determining the consumption of the length of the upper thread 30' is consistent with the operation of the device shown in FIGS. ..

FIG. 4 shows a schematic representation of how the device of the invention operates, based on a diagram of the yarn flow through the consumption monitoring device. The seams made by the sewing machine 1, which are only partially shown in FIG. 4, are shown here in the form of double lock stitches 18. The material 19 placed on the needle plate 22 is sewn by the needle 24 of the sewing machine 1. To that end, the upper thread 30 ′, which is arranged in the thread cone winding 21 above the material 19 in the direction in which the needle passes, ties the lower thread 30 wound on the lower thread bobbin 20 into a knot in a seam. Can be matched. Due to the connection of the two threads 30, 30', the gripper 23 arranged on the bobbin bobbin 20 receives the upper thread 30' and around the lower thread 30 so that both threads 30, 30' are entangled. To send. In order to detect double lock stitch defects in a timely manner or to enable monitoring of the rotation of the bobbin bobbin 20 or the bobbin bobbin 20', the magnets 7 are arranged as each bobbin 20, 20' rotates. Are arranged in each bobbin 20, 20' so as to rotate similarly. As a result, the magnetic fields 14 (not shown) generated by the respective magnets 7 are moved together and change according to their respective rotation angles. The magnetic field 14 of the magnet 7 embedded in each bobbin 20, 20' is detected according to the invention by a magnetic field sensor 8, wherein the magnetic field sensor 8 comprises a lower thread bobbin 20 and an upper thread bobbin 20'. It is located in both. The two magnetic field sensors 8 are connected to a logic, not shown here, which evaluates the measured values of the magnetic field sensors 8 so as to determine the angle of rotation and the direction of rotation of the bobbins 20, 20'. To do. Based on this, the logic determines, according to the invention, the yarn consumption.

The use of the device according to the invention for monitoring the illustrated upper thread 30' is carried out in particular in such a way that the upper thread bobbin 20' is formed by a cylinder coated with plastic, said upper thread bobbin 20 being The magnet 7 is embedded in the cylinder as in the case of the lower thread bobbin 20. The cylinder, according to the invention, is rotatably supported and mounted in the upper thread 30' supply device at the top of the sewing machine. The cylinder is orbited by the upper thread 30' and rotated by the upper thread 30' during the sewing process. This rotation is likewise detected by the magnetic field sensor 8 attached thereto. Based on the fixed radius of the cylinder and the detected rotation angle, the logic, according to the invention, can directly determine the consumption of the upper thread 30'. The consumption amount of the lower thread 30 is determined based on the measurement value of the magnetic field sensor 8 on the lower thread bobbin 20. This measurement is calculated in logic using the largest unwinding radius of bobbin 20 and a correction factor for this radius. Thereby, the consumption amount of the lower thread 30 can be calculated. By comparing the consumption amount of the upper thread and the consumption amount of the lower thread, it is possible to reliably detect a mistake in the stitch in the sewing process of the illustrated sewing machine 1.

1 sewing machine 2 bobbin 2'further bobbin 3 yarn 3'further yarn 4 further field generating means 4'further field generating means 5 field 5'further field 6 detecting means 7 magnet 8 magnetic field sensor 9 hollow cylinder 10 symmetry axis 11 NS axis 12 evaluation Means 13 Output means 14 Magnetic force lines 15 Bobbin case 16 End surface 17 Measuring wheel 18 Double lock stitch 19 Material 20 Bobbin thread 20' Upper thread bobbin 21 Thread cone winding 22 Needle plate 23 Gripper 24 Needle 30 Lower thread 30' Upper thread

Claims (15)

A device for monitoring the unraveling of the thread (3) wound around the bobbin (2) in the sewing machine (1),
Device comprising field generating means (4) for generating a non-contact scannable field (5) non-rotatably attachable to the bobbin (2). A detection means (6) for detecting the non-contact scannable field (5) is provided, and the non-contact scannable field (5) according to the rotation angle of the bobbin (2). The device according to claim 1, wherein the device is configured to detect a change in Device according to claim 1 or 2, characterized in that the field generating means (4) comprises a magnet (7), in particular a permanent magnet, and the detecting means (6) comprises a magnetic field sensor (8). .. Device according to claim 3, characterized in that the NS axis (11) of the magnet (7) is arranged perpendicular to the axis of symmetry (10) of the bobbin (2). The magnet (7) is formed as a bar magnet or a diametrically magnetized magnet, in particular as a diametrically magnetized hollow cylinder (9), in particular the magnet (7) of the bobbin (2). Device according to claim 3 or 4, characterized in that it is arranged internally. An evaluation means (12) for evaluating a magnetic field signal detectable by the detection means (6), the evaluation means (12) affecting the rotation of the bobbin (2); The device according to any one of claims 2 to 5. Bobbin (2) for yarn (3), characterized in that it comprises a device according to any one of claims 1 to 6, characterized in that it is preferably non-rotatably mounted on the bobbin (2). ) Having a sewing machine (1). A further bobbin (2') for a further thread (3') and a further device according to claims 1 to 6, said further device preferably being non-rotatably mounted on said further bobbin (2). Sewing machine (1) according to claim 7, characterized in that The bobbin (2) is configured as a bobbin bobbin (20) for winding a bobbin thread (30), and the further bobbin (2') is an upper bobbin (2') for winding an upper thread (30'). Sewing machine (1) according to claim 8, characterized in that it is configured as a thread bobbin (20'). Sewing machine according to claim 7, 8 or 9, characterized in that the evaluation means (12) are arranged to measure the length of the residual thread. Sewing machine according to any one of claims 7 to 10, characterized in that it comprises an output means (13) for outputting the signal of the evaluation means (12). A method for monitoring the unraveling of a thread (3) wound around a bobbin (2) in a sewing machine (1), comprising:
A field-generating means (4) for generating a non-contact scannable field, in particular a magnetic field (5), is non-rotatably mounted on the bobbin (2) and continuously measures the magnetic field (5). A method characterized by. The rotation angle and the rotation speed of the bobbin (2) are continuously measured and evaluated to generate an evaluation signal and a user output signal that affect the rotation of the bobbin (2). The method described in. 14. Method according to claim 12 or 13, characterized in that the consumption and/or the residual thread amount of the thread (3) wound on the bobbin (2) is calculated. Monitoring at least one further bobbin (2′) wound with further thread (3′) in said sewing machine (1), at least one further for generating a further non-contact scannable field (5′) A field generating means (4') is non-rotatably mounted on the further bobbin (2') and is wound on the further bobbin (2') by continuously measuring the further field (5'). 15. Method according to claim 14, characterized in that the consumption of the further thread (3') applied is measured and compared with the consumption of the thread (3) wound on the bobbin (2). ..

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