Sewing device and method for sewing perforated material to be sewn

Abstract

A sewing device (1) for sewing material to be sewn (6), in particular perforated material to be sewn, has a holding frame (9) for receiving the material to be sewn (6) and a sewing head (2) for receiving a driven needle (4) as a stitch-forming tool. At least one drive device is used to move the holding frame (9) relative to the sewing head (2), and an open-loop and closed-loop control device (13) is used to control the at least one drive device. At least one optical detection device (15) on the sewing head (2) is used to detect position markings on the material (6) to be sewn. The result is a sewing device by means of which, during a sewing operation, the course of a seam can be monitored and corrected relative to structures on the material to be sewn, in particular relative to perforations in the material to be sewn. The invention also relates to a sewing method using such a sewing device.

Description

[0001] Sewing device and method for sewing perforated fabric

[0002] The content of the German patent application DE 10 2024 203 628.5 is incorporated herein by reference.

[0003] The invention relates to a sewing device and a method for sewing perforated sewing material.

[0004] DE 10 2018 207 931 A1 discloses a method for controlling the position of a seam relative to the structures of a sewing material. CN 112 779 679 B discloses an image processing device, a sewing machine, and an image processing method. DE 10 2018 112 933 A1 discloses a method and a device for carrying out the method for machining a workpiece.

[0005] It is an object of the present invention to provide a sewing device by means of which a seam path can be monitored and corrected during a sewing process relative to structures on the sewing material, in particular relative to sewing material perforations.

[0006] This problem is solved by the features of claim 1.

[0007] According to the invention, it was recognized that a sewing device having at least one optical detection device for detecting position markings on the sewing material, wherein the detection device is arranged on the sewing head, enables monitoring of the seam path during the creation of the seam path in a simple and efficient manner. The sewing device has at least one detection device, in particular at least two detection devices, in particular at least three detection devices, in particular at least four detection devices, in particular at least five detection devices, in particular more than five detection devices.

[0008] The at least one detection device is preferably arranged in a position-secured manner on the sewing head. The at least one detection device can therefore preferably not be rotated or moved linearly relative to the sewing head. The at least one detection device preferably has no degree of freedom relative to the sewing head. The at least one detection device is preferably in signal communication with the control and regulating device of the sewing device. The signal connection can be established via an electrical conductor or via a wireless transmission protocol, such as Bluetooth or WLAN.

[0009] By means of the at least one detection device, position markings in partial areas of the fabric can be detected. Position markings can be, for example, perforations in the fabric. Alternatively, position markings can be temporarily or permanently applied markings on the fabric, for example, in the form of prints or stickers.

[0010] The sewing device according to the invention can be a sewing machine, an industrial sewing system, or an industrial sewing robot. The sewing device can, in particular, be any device for sewing perforated material. The sewing device has a holding frame for receiving the material. The holding frame preferably secures the material to be sewn in a slip-proof manner. The material can, in particular, be released from the holding frame simply by opening it. The holding frame can be operated manually or automatically. The sewing device can have more than one holding frame. Several holding frames are preferably arranged adjacent to one another.

[0011] Furthermore, the sewing device has at least one drive device for moving the holding frame relative to the sewing head. The at least one drive device can, for example, move the holding frame while the sewing head is rigidly arranged. Alternatively, the holding frame can be rigidly arranged and the sewing head can be moved with the aid of the at least one drive device. Alternatively, the sewing device can have more than one drive device, wherein the holding frame is arranged, for example, to be movable in the X direction and the sewing head in the Y direction. Alternatively, the sewing head can be movable in the X direction and the holding frame in the Y direction. Alternatively, a single drive unit can move both the sewing head and the holding frame via corresponding drive trains. The drive device can, for example, be a stepper motor. Preferably, the at least one drive device is a positionally accurate drive device.Preferably, the at least one drive device comprises sensor elements with which the path covered by the sewing head and / or the holding frame can be monitored.

[0012] The sewing device also has a control and regulating device for controlling the at least one drive device. The control and regulating device is designed such that it can read and store data from at least one data set. The control and regulating device has the usual components of a control and regulating device, such as a processing unit and volatile and / or non-volatile memory, such as RAM or SSD memory.

[0013] The control and regulation system is capable of reading various file formats and extracting information from them. For example, the control and regulation system can read the XY coordinates of position markings, such as perforations, of a material to be sewn from .DXF files. Furthermore, the control and regulation system can read the XY coordinates of stitch positions from DIN programs and / or DACAD programs. DACAD is a CAD-based seam program editor from the manufacturers Dürkopp Adler and KSL that creates seam programs for CNC-based sewing machines and systems. The control and regulation system can, in particular, combine data from various imported data sets.

[0014] The control and regulating device can receive information from the at least one detection device and process it. In particular, the control and regulating device can extract XY coordinates of position markers detected by the at least one detection device from the information.

[0015] The control and regulation device is capable of performing arithmetic operations and comparisons and, based on these comparisons, sending control signals to the at least one drive device. In particular, the control and regulation device can compare the XY coordinates of position markers from the read-in data with the XY coordinates of the position markers from the information acquired by the at least one acquisition device and control the at least one drive device to compensate for possible deviations between the coordinates.

[0016] A seam pattern achievable with the sewing device does not necessarily require a constant stitch length. The sewing device can compensate for fabric characteristics during sewing that would otherwise lead to an undesirable preferred sewing direction. Undesirable distortion of the fabric during a sewing process can be avoided. The undesirable accumulation of small stitch-by-stitch sewing errors, which would otherwise accumulate into intolerable defects, can be prevented.

[0017] The detection device can be arranged on the sewing head in such a way that position markings on the fabric, especially structures or perforations, can be monitored even during sewing. This can then result in rapid correction of the seam path.

[0018] The sewing device not only allows precise sewing in spaces, e.g. between groups of perforations, but also allows sewing in perforations, preferably in such a way that one stitch is placed in each perforation.

[0019] A sewing device according to claim 2 enables the detection of several partial areas of the sewing material, whereby a larger overall partial area can be detected. By detecting a larger partial area of ​​the sewing material, more information is available to the control and regulating device for controlling the seam position. In particular, by using several partial detection areas, it can be achieved that a sufficient amount of information is detected without having to take optical interference factors into account. Preferably, the sewing device has exactly three detection devices. The use of exactly three detection devices has proven sufficient for each seam path, whereby the computing power required to utilize the three detected partial areas is easily manageable.

[0020] A sewing device according to claim 3 has proven particularly efficient. The detection areas can be arranged on a semicircle. Particularly preferably, the centers of the detection areas of the three detection devices are arranged on a partial circle, and in particular on a semicircle. Such a distribution on a partial circle allows the data to be linked reliably and with relatively little computing power. In particular, the data can simply be placed next to one another and does not require any computationally intensive conversion or adjustment. After a one-time calibration, the process is particularly computationally efficient.

[0021] It is also conceivable for more than three detection zones to be arranged on a partial circle, provided the sewing device has more than three detection zones. Fewer than three detection zones can also be arranged on a partial circle, provided the sewing device has fewer than three detection zones. Preferably, the centers of the detection zones are each arranged on a partial circle. The number of detection zones and / or detection zones can be in the range between two and ten, in particular in the range between three and seven. Exactly two, exactly three, exactly four, or even exactly five detection zones can be provided.

[0022] A sewing device according to claim 4 makes it possible to easily relate the data acquired by the detection devices to the needle of the sewing device. This allows the actual position of the needle of the sewing device to be easily determined and utilized. Due to this arrangement, each detection device has the same spatial distance from the needle's movement axis.

[0023] A sewing device according to claim 5 specifies a preferred distribution of the detection devices. A circumferential angle of 30° < a < 90°, in particular 45° < a < 90°, between two detection devices, in particular between the centers of the partial detection areas, can ensure the smallest possible overlap of the areas detected by the detection devices. This allows the largest possible overall detection area to be achieved. Furthermore, the detected partial areas can be easily combined, thus requiring as little computing power as possible.

[0024] A sewing device according to claim 6 enables time-efficient pickup of the entire sewing material, which can occur, for example, after the sewing material has been placed in the holding frame but before the start of a sewing process. The additional optical detection device can be designed, for example, such that it can detect the entire sewing material at once. Alternatively, the additional detection device can be configured such that it can detect the entire sewing material in several partial steps. For this purpose, the additional detection device can be arranged so as to be movable, for example. If the additional detection device can detect the entire sewing material in one detection process, the additional detection device can be arranged in a fixed location.

[0025] By visually scanning the entire fabric in advance, it is possible to check, for example, whether a fabric is correctly inserted into the holding frame, whether it is a correct fabric, or whether the fabric contains defects. This type of inspection can prevent wasted machine movement time when a faulty fabric is inserted into the holding frame and sewn. Furthermore, it can prevent a fabric from being sewn even though it is simply twisted or distorted when inserted into the holding frame and can be easily corrected. This can also reduce potential material waste due to faulty sewing.

[0026] A sewing device according to claim 7 enables the acquisition of easy-to-process camera image data. In such image data, for example, markings or perforations can be detected using color recognition or object recognition, i.e., generally, machine vision. The detection of position markings can also be supported by deep learning, neural networks, or artificial intelligence.

[0027] The camera may be a CCD camera.

[0028] Any two-dimensional seam pattern can be created by means of a sewing device according to claim 8. The sewing head is arranged, in particular, to rotate about a needle movement axis extending in the Z direction, perpendicular to an xy arrangement plane of the sewing material. A further object of the present invention is to provide a sewing method for sewing structured, particularly perforated, sewing material.

[0029] The object is achieved by a method according to claim 9.

[0030] The following steps are required to carry out the procedure:

[0031] Providing a sewing device according to one of claims 1 to 8,

[0032] Clamping the material to be sewn into the holding frame, reading data from at least one data set into the control and regulation device, whereby the data includes the XY coordinates of each material structure or material perforation and the XY coordinates of each seam stitch target position of the material,

[0033] Approaching the seam start target position,

[0034] Detecting a partial area of ​​the sewing material by means of at least one detection device,

[0035] Determining the position of at least two perforations in the detected partial area by the at least one detection device of the sewing head in reaction to the sewing head,

[0036] Comparison of the actual position of the sewing head with the seam start target position of the sewing head based on a comparison of the determined position of the at least two perforations in the detected partial area with the X-Y coordinates of the same at least two perforations from the at least one data set, Correction of the actual position of the sewing head based on the comparison carried out by controlling the at least one drive device,

[0037] Start of the sewing process, whereby during the sewing process after at most ten seam stitches the actual position of the sewing head is compared with the seam stitch target position of the sewing head based on a comparison of the detected position of the at least two perforations with the XY coordinates of the same at least two perforations from the read-in data and corrected by controlling the at least one drive device.

[0038] According to the invention, it was recognized that by comparing the actual position of the sewing head with the desired seam stitch position of the sewing head based on a comparison of the detected position of at least two sewing material structures or at least two sewing material perforations with the XY coordinates of the same at least two perforations from the data after at most ten seam stitches, the course of the seam can be easily and relatively inexpensively monitored during the sewing process and corrected by appropriately controlling the drive device. This allows distortions of the sewing material, which also occur during the sewing process due to stitch formation, to be compensated, thus achieving a particularly good and reproducible sewing result.

[0039] This method achieves a corrected course of the stitching points, rather than a uniform length between two stitching points, as in the prior art. Furthermore, this method allows not only seams between structures containing perforations, but also seams within structures containing perforations. In particular, the stitches can be placed in such a way that they are formed within perforations.

[0040] The at least one data set read into the control and regulation device can, for example, be the XY coordinates of the perforations, which can be provided, for example, as a .DXF file. Furthermore, the at least one data set can be the XY coordinates of the stitch positions, which can be provided, for example, via a DIN program or a DACAD program. The data can generally be provided in any format that can be processed by the control and regulation device.

[0041] When comparing the actual position of the sewing head with the target seam start position of the sewing head, a deviation in the X direction and a deviation in the Y direction are determined. The deviation is then corrected by controlling at least one drive device. In particular, the deviation is corrected by a movement in the X direction and / or in the Y direction.

[0042] To compare the determined position of the at least two perforations with the XY coordinates of the same at least two perforations, only the required partial areas from the read-in data can be loaded and processed. This minimizes the computing power required for the comparison and, if necessary, also optimizes the process time. Alternatively, the data for the entire sewing material can be loaded, resulting in a more computationally intensive process. A method according to claim 10 enables a better sewing result. By reducing the comparison interval from at most ten stitches to at most five stitches, an accumulating error can be reduced to a lower maximum. This results in an improved seam profile.

[0043] A sewing method according to claim 11 enables the best possible sewing result. By comparing the position of the sewing head after each stitch, each seam stitch position is corrected, preventing errors from accumulating. Such a method therefore delivers the best possible sewing result.

[0044] A method according to claim 12 enables the detection of larger partial areas. This ensures that sufficient perforations can always be detected to compensate for the actual position of the sewing head.

[0045] A method according to claim 13 enables the detection of material defects, the detection of incorrectly inserted sewing material due to twisting or distortion of the sewing material, or the detection of sewing material that does not match the sewing material to be sewn. This can prevent sewing material from being sewn incorrectly, thus saving material. Furthermore, machine utilization time due to incorrectly sewing faulty or incorrect sewing material can be saved. Such a method ensures more efficient machine utilization. Preferably, the entire sewing material is detected by the additional detection device. For this purpose, the sewing material can be picked up with a single detection area. Alternatively, the entire sewing material is detected by the at least one detection device of the sewing head. For this purpose, the sewing head can be moved in steps over the entire sewing material and can detect a plurality of partial areas.The sub-areas can then be combined into one overall area in the control system.

[0046] A method according to claim 14 enables the acquisition of data that is easy to process. The recognition of position markings and / or perforations from image files requires relatively little computing power and is also reliable. Furthermore, the acquisition of image data does not require a contact detection device, thus eliminating damage to the sewing material due to contact.

[0047] A method according to claim 15 enables the automatic identification of perforations. In particular, the data does not need to be viewed or processed by a user.

[0048] Machine vision can be supported by deep learning, neural networks and artificial intelligence.

[0049] Embodiments of the invention will be explained in more detail with reference to the figures, which show:

[0050] Fig. 1 shows a sewing device with individual components omitted, Fig. 2 shows an exemplary structure of a sewing head,

[0051] Fig. 3 a first snapshot of a sewing method according to the invention,

[0052] Fig. 4 a second snapshot of a sewing method according to the invention,

[0053] Fig. 5 a third snapshot of a sewing method according to the invention,

[0054] Fig. 6 a fourth snapshot of a sewing method according to the invention,

[0055] Fig. 7 a fifth snapshot of a sewing method according to the invention,

[0056] Fig. 8 a sixth snapshot of a sewing method according to the invention,

[0057] Fig. 9 a seventh snapshot of a sewing method according to the invention,

[0058] Fig. 10 a first exemplary sewing process of a seam between perforations and

[0059] Fig. 11 shows a second exemplary seam path of a seam in perforations. Fig. 1 schematically shows a sewing device 1. Such a sewing device 1 can be, for example, a CNC sewing machine.

[0060] To facilitate positional designations, a Cartesian XYZ coordinate system is shown in Figs. 1 and 3 to 11. The X-axis is perpendicular to the drawing plane of Fig. 1 and extends into it. The Y-axis runs to the left in Fig. 1, and the Z-axis runs upward in Fig. 1.

[0061] As shown in Fig. 1, the sewing device 1 has a sewing head 2. The sewing head 2 includes, among other components, a needle bar 3 and a needle 4. The sewing head 2 is mounted for rotation about the Z-axis by at least 180°. A schematically indicated looper 5 is arranged coaxially and counter to the Z-direction. The needle 4 and the looper 5 represent driven stitch-forming tools of the sewing device 1.

[0062] Between the needle 4 and the looper 5 is a sewing material 6 with a structure 7 in the form of perforations 8. The sewing material 6 is clamped in a holding frame 9. The holding frame 9 can be moved in the XY plane relative to the sewing head 2 by a drive device (not shown). Due to the rotatability of the sewing head 2 and the mobility of the holding frame 9 relative to the sewing head 2 in the XY plane, three degrees of freedom result, so that a seam can be realized in all sewing directions on the XY plane.

[0063] The sewing device 1 comprises an additional detection device 10 in

[0064] Form of a camera. The detection area 11 of the additional detection device 10 is shown schematically in Fig. 1. The additional detection device 10 can either be positioned such that it can statically cover the entire sewing area of ​​a sewing material 6 through the detection area 11, or the additional detection device 10 can be mounted via a drive system such that the additional detection device 10 can move its detection area 11 such that the entire sewing area of ​​the sewing material 6 can be detected by several partial recordings. Alternatively, the holding frame 9 can be moved such that the additional detection device 10 can detect the entire sewing material 6 in several partial areas.

[0065] The additional detection device 10 is connected to a control and regulation device 13 via a signal connection 12. The control and regulation device 13 naturally comprises the components of a standard control and regulation device, for example, a computing unit as well as volatile and non-volatile storage elements, for example, RAM memory and a non-volatile memory such as SSD memory.

[0066] The control and regulation device 13 can have evaluation software for evaluating the images from the additional acquisition device 10 and other acquisition devices. For this purpose, the evaluation software can use, for example, machine vision. Machine vision can be supported by deep learning, neural networks, or artificial intelligence.

[0067] Communication between the additional detection device 10 and the control and regulation device 13 can be established, for example, via a USB (Universal Serial Bus) standard by reading and writing files on a data storage device or via a TCP (Transmission Control Protocol) connection. Communication can also be established via wireless standards such as Bluetooth or WLAN.

[0068] Fig. 2 shows an exemplary structure of a sewing head 2. In addition to the needle bar 3, the sewing head 2 comprises a presser foot 14, by means of which a sewing material 6 can be held. The presser foot 14 prevents, in particular, the sewing material 6 from lifting in the Z direction. Three optical detection devices 15, each in the form of a camera, are arranged on the sewing head 2. Each of the detection devices 15 has a detection area 16 (field of view). The detection devices 15 are rigidly connected to the sewing head 2. The detection areas 16 of the detection devices 15 are thus fixedly defined. The detection devices 15 are CCD cameras.

[0069] The respective camera can be equipped with an autofocus unit. Alternatively, the respective camera can have a fixed focal length, adjusted to the distance of the respective detection device from a sewing material arrangement plane.

[0070] The detection areas 16 are selected such that they cover an area around the movement axis of the needle 4. The detection area 16 of the detection devices 15 can also encompass the movement axis of the needle 4 and can be digitally shortened subsequently by the evaluation software. The detection areas 16 of the detection devices 15 are deliberately selected to be small in order to avoid disturbances, such as those caused by the moving needle 4, as well as optical distortions of structures 7 to be detected in the form of perforations 8. An example seam sequence is shown in Figs. 3 to 9. To use such a method, data from at least one data set is first loaded into the control and regulation device 13. The data comprise the XY coordinates of perforations 8 and preferably originate from a .DXF file. In addition, the data comprise the XY coordinates of stitch positions and preferably originate from a DIN file or a DAC AD program.Collectively, the data contains the XY coordinates of all perforations 8 of a sewing material 6 as well as all XY coordinates of the seam stitch target position 21 of a seam path.

[0071] After reading in the files, the additional detection device 10 can first be used to check whether the sewing material 6 placed in the holding frame 9 is the sewing material 6 to be sewn. All perforations 8 of the sewing material 6 can be detected and compared with the perforations 8 stored in the data. This can be used to determine, for example, whether a defective sewing material 6 has been inserted, in which, for example, perforations 8 are missing. It can also be detected whether a sewing material 6 has been twisted or distorted when placed in the holding frame 9. Furthermore, it can be checked whether a sewing material 6 has been placed in the holding frame 9 that does not match the selected sewing program. This check can prevent the sewing of a defective sewing material 6, thereby saving material and machine utilization time.

[0072] After checking whether the sewing material 6 has been correctly and correctly inserted and is free of defects, the sewing process begins. For this purpose, as shown in Fig. 3, the actual position 17 of the needle head 2, which is arranged in the movement axis of the needle 4, is moved in the direction of the target seam start position 18. The area around the actual position 17 is monitored by the three detection areas 16. The detection areas 16 have overlapping areas 19. A common image is generated across the three detection areas 16. The three detection areas can be combined, for example, using one or more evaluations of specific features. The features can be detected in particular in the overlapping areas 19. By detecting the features in the overlapping areas 19, it can be ensured that the three detection areas 16 are combined in the correct position and alignment to form a common image.

[0073] After a rough approach to the seam start target position 18, the actual position 17 of the sewing head 2 is compared with the seam start target position 18 as shown in Fig. 4. For this purpose, a selection 20 of perforations 8 is detected by the detection devices 15. The detected position of the perforations 8 of the selection 20 is then compared with the XY coordinates of the same perforations 8 in the control and regulating device 13. Based on the comparison carried out, a deviation in the X direction and in the Y direction between the actual position 17 of the sewing head 2 and the seam start target position 18 is determined. The deviations in the X directions and in the Y directions are then corrected by moving the holding frame 9 relative to the sewing head 2 by controlling the drive device (not shown).

[0074] By correcting the deviations in the X and Y directions between the actual position 17 of the sewing head 2 and the seam start target position 18, the position shown in Fig. 5 is achieved, in which the actual position 17 of the sewing head 2 corresponds to the seam start target position 18. The comparison performed in Fig. 4 also ensures that the orientation around the Z axis of the sewing head 2 is correct. As soon as the state shown in Fig. 5 is reached, the sewing process can be started.

[0075] During the sewing process, an error can build up in the form of a deviation in the X-direction and / or Y-direction between a seam stitch target position 21 and the actual position 17 of the sewing head 2. Such an error is shown in Fig. 6, which occurs during the fourth stitch of the seam path. Such an error can occur, for example, due to distortion of the sewing material 6 caused by previous seam stitches 22. On the other hand, such an error can occur due to inaccuracies in the drive device of the sewing device 1. To compensate for such errors, the position of a selection 20 of perforations 8 is compared with the XY coordinates of the same perforations 8 in the control and regulating device 13 during the execution of the fourth stitch. From this, a deviation in the X- and / or Y-direction is determined.

[0076] The deviation in the X and / or Y directions between the target seam stitch position 21 and the actual position 17 of the sewing head 2 is compensated with the next stitch, as shown in Fig. 7. Due to the compensation, the actual position 17 of the sewing head 2 and the target seam stitch position 21 coincide in the next, i.e., fifth, stitch. This correction prevents an error from accumulating.

[0077] By correcting the stitch positions in this way, an error due to distortion of the sewing material 6 during the sewing process can be actively counteracted. This allows the length of the thread 23 between the seam stitches 22 to vary, but actively corrects the seam so that it permanently runs centrally between the structures 7. Preferably, the deviation in the X and / or Y directions between the seam stitch target position 21 and the actual position 17 of the sewing head 2 can be monitored and corrected for each stitch, preventing any errors from accumulating.

[0078] Figs. 8 and 9 show the further course of the seam, with structures 7 exhibiting a change of direction in the form of a right angle. The seam must therefore also be rotated 90° to the right. To do this, the actual position 17 of the sewing head 2 can first be compared with the desired seam stitch position 21 at the penultimate stitch before the change of direction of the seam to ensure that the last seam stitch 22, in which the change of direction occurs, is optimally positioned. This ensures that the seam course has a 90° angle. It also ensures that the change of direction occurs exactly in the seam stitch 22.

[0079] As shown in Fig. 8, the sewing head 2 is rotated by 90° when the seam changes direction. This is evident from the detection areas 16. The position and alignment of the sewing head 2 can be checked and, if necessary, corrected by comparing a selection 20 of perforations 8 by comparing the detected positions of the perforations 8 with the XY coordinates of the perforations 8 in the control and regulating device 13. This results in a seam path at a right angle, as shown in Fig. 9.

[0080] Figs. 10 and 11 show exemplary seam paths that can be sewn using the method according to the invention, which is illustrated in Figs. 3 to 9. The seam path can, as shown in Fig. 10, run between structures 7 with perforations 8. Alternatively, the seam path can, as shown in Fig. 11, run in a structure 7 made up of perforations 8. In this case, the desired seam start positions 18 can, in particular, correspond to the XY coordinates of the perforations 8.

[0081] The method according to the invention therefore enables the sewing of a seam between structures 7 made of perforations 8 and in structures 7 made of perforations 8.

Claims

Patent claims 1. Sewing device (1) for sewing, in particular, perforated sewing material (6), comprising a holding frame (9) for receiving the sewing material (6), a sewing head (2) for receiving a driven needle (4) as a stitch formation tool, at least one drive device for moving the holding frame (9) relative to the sewing head (2), a control and regulating device (13) for controlling the at least one drive device, characterized in that at least one detection device (15) for optically detecting position markings on the sewing material (6) is arranged on the sewing head (2).

2. Sewing device (1) according to claim 1, characterized in that at least three detection devices (15) are arranged on the sewing head (2).

3. Sewing device (1) according to claim 2, characterized in that detection areas (16) of the at least three detection devices (15) are arranged on a partial circle in an arrangement plane of the sewing material (6).

4. Sewing device (1) according to claim 3, characterized in that the center of the partial circle lies on the axis of movement of the needle (4).

5. Sewing device (1) according to one of claims 3 or 4, characterized in that a circumferential angle a between two detection devices (15) on the pitch circle is in the range between 30° and 90°.

6. Sewing device (1) according to one of the preceding claims, characterized by an additional detection device (10) for optically detecting the entire sewing material (6) in the holding frame (9).

7. Sewing device (1) according to one of the preceding claims, characterized in that the at least one detection device (15) is a camera.

8. Sewing device (1) according to one of the preceding claims, characterized in that the sewing head (2) is arranged on the sewing device (1) so as to be rotatable by at least 180°.

9. Method for sewing, in particular, perforated sewing material (6), comprising the steps: Providing a sewing device (1) according to one of claims 1 to 8, Clamping the material to be sewn (6) into the holding frame (9), reading data of at least one data set into the control and regulating device (13), wherein the data includes the XY coordinates of each perforation (8) and the XY coordinates of each seam stitch target position (21) of the material (6), Approaching the desired seam start position (18), detecting a partial area of ​​the sewing material (6) by means of the at least one detection device (15), Determining the position of at least two perforations (8) in the detected partial area by the at least one detection device (15) of the sewing head (2) in response to the sewing head (2), comparing the actual position (17) of the sewing head (2) with the seam start target position (18) of the sewing head (2) based on a comparison of the determined position of the at least two perforations (8) in the detected partial area with the XY coordinates of the same at least two perforations (8) from the at least one data set, correcting the actual position (17) of the sewing head (2) based on the comparison carried out by controlling the at least one drive device, starting the sewing process,wherein during the sewing process, after at most ten seam stitches (22), the actual position (17) of the sewing head (2) is compared with the seam stitch target position (21) of the sewing head (2) by comparing the detected position of the at least two perforations (8) with the XY coordinates of the same at least two perforations (8) from the read-in data and is corrected by controlling the at least one drive device.

10. The method according to claim 9, characterized in that the actual position (17) of the sewing head (2) is compared with the desired seam stitch position (21) of the sewing head (2) based on a comparison of the detected position of the at least two perforations (8) with the XY coordinates of the same at least two perforations (8) from the read-in data after at most five seam stitches and is corrected by controlling the at least one drive device.

11. Method according to claims 9 or 10, characterized in that the actual position (17) of the sewing head (2) is compared with the desired seam stitch position (21) of the sewing head (2) based on a comparison of the detected position of the at least two perforations (8) with the XY coordinates of the same at least two perforations (8) from the read-in data after each seam stitch and is corrected by controlling the at least one drive device.

12. Method according to one of claims 9 to 11, with a device according to claim 2, characterized in that the position of the at least two perforations (8) is detected by the at least three detection devices (15) of the sewing head (2) in relation to the sewing head (2).

13. Method according to one of claims 9 to 12, characterized in that after determining the XY coordinates of each perforation (8) and each seam start target position (18) in the control and regulating device (13), the following steps are carried out: detecting the entire sewing material (6) by a detecting device (10; 15), Determining all perforations (8) in the detected sewing material (6), comparing the detected perforations (8) with the perforations (8) stored in the control and regulating device (13), determining possible defects in the sewing material (6) and / or a twisting of the sewing material (6) and / or an incorrect sewing material (6) based on the comparison carried out.

14. The method according to any one of claims 9 to 13, characterized in that the at least one detection device (15) detects image data.

15. The method according to claim 14, characterized in that the Perforations (8) can be determined using machine vision.

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