Thread trimming control method, thread trimming control system and sewing machine

Abstract

The invention relates to a thread trimming control method, a thread trimming control system and a sewing machine, the thread trimming control method comprises the following steps: arranging a first sensor, a second sensor and a third sensor which are arranged in sequence, the distance between the first sensor, the second sensor and the third sensor is L1, and the distance between the second sensor and the third sensor is L2; when the fabric reaches the second sensor from the first sensor, the controller calculates that the current stitch length of the sewing machine is O1 = L1 / N, and N is the number of turns of rotation of the sewing machine; the controller calculates the number of turns of rotation required by the sewing machine within the distance of L2, M = L2 / O1 = m + n, and m is an integer, 0 lt; nlt; 1; when ngt; k, when the fabric passes through the second sensor, the controller adjusts the stitch length of the sewing machine through the execution motor and the stitch length adjusting mechanism, so that the adjusted stitch length O2 meets the condition that L2 / O2 = x + y, and x is an integer, 0 lt; yt; Yt; 1, y < = k, 0.4 < = k < = 0.6; when n is smaller than or equal to k, the sewing machine continues sewing according to the stitch length of O1. According to the thread trimming control method, the thread trimming control system and the sewing machine, the problem that under the existing large-stitch-length sewing working condition, cloth and thread residues are very prone to being scattered is solved.

Description

Technical Field

[0001] This application relates to the technical field of sewing machines, and particularly to a thread trimming control method, a thread trimming control system and a sewing machine. Background Art

[0002] When a sewing machine sews a fabric, a front thread loop is formed at the front edge of the fabric, and a rear thread loop is formed at the rear edge of the fabric. Therefore, the sewing machine needs to trim the front thread loop at the start of sewing and trim the rear thread loop at the end of sewing to improve the sewing quality. Moreover, some sewing processes require short thread trimming for the thread trimming to improve the sewing quality and efficiency.

[0003] In the existing sewing machine under the condition of large stitch pitch, as Figure 1 shown, at the front and rear edges of the fabric, if the needle dropping point of the first or the last needle is not on the fabric, when the thread trimming knife cuts the front and rear thread ends, the arrow-indicated parts at both ends are very likely to be scattered because there is no thread loop to fix the fabric and the thread ends. Summary of the Invention

[0004] Based on this, it is necessary to provide a thread trimming control method, a thread trimming control system and a sewing machine to solve the problem that when the needle dropping point of the first or the last needle is not on the fabric under the existing large stitch pitch sewing condition, when the thread trimming knife cuts the front and rear thread ends, the arrow-indicated parts at both ends are very likely to be scattered because there is no thread loop to fix the fabric and the thread ends.

[0005] The thread trimming control method provided by this application includes the following steps: Set three sequentially arranged position sensors to detect the moving position of the fabric, which are respectively defined as the first sensor, the second sensor and the third sensor. Define the distance between the first sensor and the second sensor as L1, and the distance between the second sensor and the third sensor as L2; Set a revolution sensor to record the number of revolutions of the sewing machine. When the fabric passes through the first sensor, the controller controls the revolution sensor to start counting. When the fabric reaches the second sensor, the controller calculates the current stitch pitch of the sewing machine according to the number of revolutions N of the sewing machine recorded by the revolution sensor as: O1 = L1 / N; The controller calculates the number of revolutions M = L2 / O1 = m + n that the sewing machine needs to rotate within the distance that the fabric moves from the second sensor to the third sensor, where m is an integer and 0 < n < 1; When n > k, when the fabric passes through the second sensor, the controller adjusts the stitch pitch of the sewing machine through the execution motor and the stitch pitch adjustment mechanism so that the adjusted stitch pitch O2 satisfies L2 / O2 = x + y, where x is an integer, 0 < y < 1, y ≤ k, and 0.4 ≤ k ≤ 0.6; When n ≤ k, the controller controls the execution motor not to act, and the sewing machine continues to sew at the stitch pitch of O1.

[0006] In one of the embodiments, k is equal to 0.5.

[0007] In one of the embodiments, the thread trimming control method further comprises the following steps: after the last needle is completed, the controller controls the thread trimming mechanism to trigger thread trimming after a preset time.

[0008] In one of the embodiments, the preset time t satisfies 0.3s≤t≤0.8s.

[0009] In one of the embodiments, when n>k, the controller controls the adjusted stitch length O2 to satisfy O2

[0010] In one of the embodiments, when the controller calculates n>k for three times in succession, the controller controls the alarm to issue an abnormal alarm and controls the sewing machine to stop running.

[0011] In one of the embodiments, the position sensor is a Hall sensor or a photoelectric sensor.

[0012] In one of the embodiments, the number of turns sensor is a rotary encoder or a Hall sensor.

[0013] The application also provides a thread trimming control system, which adopts the thread trimming control method of any one of the above embodiments, so that the drop point of the first needle or the last needle of the sewing machine can fall on the set position of the fabric when the fabric is sewn to the front edge or the back edge. The thread trimming control system comprises a first sensor, a second sensor, a third sensor, a number of turns sensor, a controller, an execution motor and a stitch length adjusting mechanism. The first sensor, the second sensor, the third sensor, the number of turns sensor and the execution motor are electrically connected to the controller. The first sensor, the second sensor and the third sensor are sequentially arranged and are respectively used to detect the moving position of the fabric. The number of turns sensor is used to record the number of turns of the sewing machine. The controller can adjust the stitch length of the sewing machine through the execution motor and the stitch length adjusting mechanism.

[0014] The application also provides a sewing machine, which comprises the thread trimming control system of the above embodiments.

[0015] Compared with the prior art, the thread trimming control method, the thread trimming control system and the sewing machine provided by the application break through the traditional fixed stitch length control mode, realize closed-loop adjustment of the sewing parameters by establishing a dynamic correlation model of the fabric displacement and the sewing action, compared with a single-point detection system, a three-level detection architecture can accurately capture the change of the fabric movement speed, and eliminate the control error caused by the false triggering of the position sensor. The real-time stitch length compensation mechanism effectively solves the cumulative error problem under the large stitch length working condition, and avoids the efficiency loss caused by manual intervention adjustment. Through the above technical solutions, the application can ensure that the sewing machine accurately falls on the fabric setting area at the first and last needle positions under any stitch length setting, effectively prevents the thread loose phenomenon. The dynamic stitch length adjustment function meets the sewing requirements of different material fabrics, maintains the original sewing efficiency, improves the thread trimming quality, and meets the strict requirements of high-end sewing process on short thread control. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0017] Figure 1 A schematic diagram of the first needle or the last needle not falling into the fabric edge area under the large stitch length working condition of the existing sewing machine;

[0018] Figure 2 A partial structure schematic of the sewing machine provided by an embodiment of the application Figure 1 ;

[0019] Figure 3 A partial structure schematic of the sewing machine provided by an embodiment of the application Figure 2 .

[0020] Reference signs: 100, first sensor; 200, second sensor; 300, third sensor; 400, execution motor; 500, stitch length adjustment mechanism; 510, eccentric wheel; 520, connecting rod; 530, stitch length adjustment crank; 600, fabric. DETAILED DESCRIPTION

[0021] Please refer to Figure 3 and Figure 3The application provides a thread trimming control method, so that the falling point of the first needle or the last needle of the fabric 600 can be located at the edge of the fabric 600 when the fabric 600 is sewn to the front edge or the back edge, so as to ensure that the fabric 600 and the thread end will not be scattered in the case that the thread end is very short when the thread is trimmed, and the length of the thread end can be effectively controlled to be short. It should be noted that the first needle here is not the first needle of the sewing machine, but the first needle of the finished fabric 600. The finished fabric 600 refers to the fabric 600 after the sewing is completed and the excess edge fabric 600 is trimmed.

[0022] Specifically, the thread trimming control method comprises the following steps:

[0023] Three position sensors arranged in sequence are arranged to detect the moving position of the fabric. Specifically, the arrangement distance of the position sensors can be positively correlated with the maximum needle spacing of the sewing machine. The position sensors can be implemented by using an array of photoelectric sensors or an array of Hall sensors. The accuracy of the position signal of the fabric 600 is ensured by non-contact detection. The Hall sensor refers to a device for detecting the position of the fabric by using the Hall effect principle. Specifically, the Hall sensor can be implemented by using a magnetic sensitive element combined with a magnetic field change. The Hall sensor can generate a signal by sensing the magnetic mark or mechanical structure attached to the fabric when the fabric moves. The photoelectric sensor refers to a device for detecting the position of the fabric based on a photosensitive element. Specifically, the photoelectric sensor can be implemented by using an infrared emitter and receiver combination. The photoelectric sensor can generate an electrical signal by blocking or reflecting light. The two types of sensors can adapt to fabrics 600 of different materials and colors, and can avoid false triggering caused by environmental light or the light reflection characteristics of the fabric 600, so as to ensure that the sewing machine accurately obtains the timing when the edge of the fabric 600 reaches the position sensor.

[0024] The plurality of position sensors are defined as a first sensor 100, a second sensor 200 and a third sensor 300. It should be noted that the first sensor 100, the second sensor 200 and the third sensor 300 can be arranged on the same straight line or can be located at the three vertices of a triangle. It is only required that the three position sensors are arranged in sequence along the advancing direction of the fabric 600. Furthermore, the first sensor 100, the second sensor 200 and the third sensor 300 are electrically connected to a controller. The controller refers to a control unit for receiving sensor signals and performing logical operations. The controller can be implemented by using an embedded microprocessor or a programmable logic controller, and is used to monitor the running state of the sewing machine in real time and execute control instructions. The distance between the first sensor 100 and the second sensor 200 is defined as L1, and the distance between the second sensor 200 and the third sensor 300 is defined as L2. L1 and L2 are both determined as fixed values by the installation positions.

[0025] A number of turns sensor (not shown in the figure) is arranged to record the number of turns of the sewing machine, and the number of turns sensor is electrically connected to the controller, and the number of sewing turns is counted by a rotary encoder or a Hall sensor, wherein the rotary encoder can be divided into an absolute encoder and an incremental encoder. Among them, the rotary encoder refers to a device for recording the number of turns of the sewing machine by detecting the rotary displacement, which can be realized by using an optical or magnetic encoder, which accurately reflects the change of the rotary angle through the output pulse signal. The Hall sensor refers to a device for detecting the change of the magnetic field based on the Hall effect, which can realize the number of turns by detecting the position change of the magnet on the rotating shaft of the sewing machine, and reflects the rotating state of the rotating shaft through the output level signal.

[0026] When the fabric passes through the first sensor 100, the controller controls the number of turns sensor to start counting, and when the fabric reaches the second sensor 200, the controller calculates the current stitch length of the sewing machine according to the number of turns N recorded by the number of turns sensor: O1=L1 / N;

[0027] Further, the controller calculates the number of turns M=L2 / O1=m+n of the sewing machine required for the fabric 600 to move from the second sensor 200 to the third sensor 300, wherein m is an integer, 0<n<1, that is, n is a decimal number;

[0028] When n>k, the fabric passes through the second sensor 200, and the controller adjusts the stitch length of the sewing machine by executing the motor 400 and the stitch length adjusting mechanism 500 to make the adjusted stitch length O2 satisfy L2 / O2=x+y, wherein x is an integer, 0<y<1, that is, y is a decimal number, and y≤k, 0.4≤k≤0.6. Wherein k is a preset threshold value for stitch length adjustment, which can be realized by using a numerical comparator or a logic judgment module, for judging whether the decimal part of the number of turns of the sewing machine corresponding to the moving distance of the fabric 600 needs to trigger the stitch length adjustment.

[0029] It should be noted that the stitch length adjusting mechanism 500 of the sewing machine is a delicate system, and the automatic adjustment of the stitch length of the sewing machine is usually completed by the execution motor 400 (step motor or servo motor) driven by the controller to drive the eccentric wheel 510 to rotate and drive the connecting rod 520 and the stitch length adjusting crank 530 to move.

[0030] When n≤k, the controller controls the execution motor 400 to be inaction, and the sewing machine continues to sew at the stitch length of O1.

[0031] Specifically, the stitch count is started when the cloth 600 triggers the first sensor 100, and the actual stitch length parameter is calculated when the second sensor 200 is reached. According to the ratio of the interval between the second sensor 200 and the third sensor 300 to the current stitch length, the integer stitch count and the decimal remainder are resolved. When the remainder exceeds the preset threshold k, the decimal remainder of the subsequent sewing stitch count is reduced to below the preset threshold k by fine-tuning the stitch length parameter, and the adjustment process is completed in real time during the movement of the cloth 600.

[0032] Compared with the prior art, the method breaks through the traditional fixed stitch length control mode, realizes closed-loop adjustment of the sewing parameters by establishing a dynamic correlation model of the displacement of the cloth 600 and the sewing action. Compared with a single-point detection system, the three-level detection architecture can accurately capture the change in the movement speed of the cloth 600 and eliminate the control error caused by false triggering of the position sensor. The real-time stitch length compensation mechanism effectively solves the problem of accumulated error in the large stitch length working condition and avoids the efficiency loss caused by manual intervention adjustment.

[0033] Through the above technical solution, the sewing machine can ensure that the first and last needle positions are accurately located in the set area of the cloth 600 under any stitch length setting, effectively preventing the phenomenon of loose thread ends. The dynamic stitch length adjustment function meets the sewing requirements of different material cloths 600, improves the thread cutting quality while maintaining the original sewing efficiency, and meets the strict requirements of high-end sewing processes for short thread control.

[0034] In an embodiment, k is 0.5. Setting k to 0.5 can balance the stitch length adjustment frequency and the sewing stability, and avoid the fluctuation of the sewing trajectory caused by frequent adjustment. Specifically, when the cloth 600 moves to the second sensor 200, the controller calculates the stitch length by the number of rotations of the sewing machine recorded by the stitch count sensor and predicts the number of rotations required to reach the third sensor 300. If the decimal part of the calculated number of rotations exceeds 0.5, the stitch length adjustment mechanism 500 is started to reduce the stitch length, so that the decimal part of the subsequent number of rotations is reduced to below 0.5.

[0035] The present scheme sets k to 0.5, which avoids both the frequent action of the mechanism caused by too high adjustment sensitivity and the thread position deviation caused by adjustment lag. Moreover, through the above technical solution, the present application can accurately control the needle drop position of the last needle to be always within the edge range of the cloth 600, and ensure that the length of the thread after cutting meets the process requirements.

[0036] But not limited to this, in other embodiments, k can also be 0.4 or 0.6.

[0037] Further, in an embodiment, the thread trimming control method further comprises the following steps: after the last needle is completed, the controller controls a thread trimming mechanism (not shown in the figure) to trigger thread trimming after a preset time delay. The preset time refers to the time delay for triggering the thread trimming action, which can be realized by a timer or a pulse counter, and is used to ensure that the thread trimming operation is performed after the last needle completes the thread take-up action. The delay trimming mechanism effectively avoids the phenomenon of thread end scattering due to incomplete thread take-up action, especially significantly improves the quality stability of thread trimming under large needle spacing conditions.

[0038] Specifically, in an embodiment, the preset time t satisfies 0.3s≤t≤0.8s, and preferably t is 0.5s. That is, after the last needle is sewn, the controller starts the delay timing module to trigger the thread trimming mechanism to cut off the thread end within a time window of 0.3s to 0.8s. For example, after the main shaft of the sewing machine completes the needle lifting action of the last needle, the thread trimming knife is controlled to close after a delay of 0.5s, ensuring that the thread bundle is formed stably before being cut.

[0039] Specifically, when the last needle is completed, the controller starts the timing module and enters a waiting state, and sends a driving signal to the thread trimming mechanism after the preset time is reached. If t is less than 0.3s, it may cause the needle to not be fully lifted when trimming the thread; if t exceeds 0.8s, the position of the thread end may be offset due to the movement of the fabric 600.

[0040] In an embodiment, when n>k, the controller controls the adjusted needle spacing O2 to satisfy O2

[0041] Wherein, n refers to the decimal part of the number of revolutions required for the sewing machine to move from the second sensor 200 to the third sensor 300, which can be calculated by the number of revolutions recorded by the revolution sensor, and is used to determine whether needle spacing adjustment is needed. k refers to a preset threshold, which can be 0.5, and is used to trigger the condition judgment of needle spacing adjustment. O1 refers to the current needle spacing of the sewing machine, which can be calculated by the moving distance of the fabric between the first sensor 100 and the second sensor 200 divided by the number of revolutions of the sewing machine. O2 refers to the adjusted needle spacing, which can be realized by executing the motor 400 to drive the needle spacing adjustment mechanism 500 to change the movement amplitude of the feed dog or the presser foot. When n exceeds k, the needle spacing O2 is reduced, so that the number of revolutions required for the sewing machine to move to the third sensor 300 is closer to an integer, thereby avoiding the last needle landing point exceeding the edge of the fabric 600.

[0042] Specifically, when the number of revolutions sensor detects that the decimal part n of the number of revolutions of the sewing machine exceeds the threshold k, the controller sends an instruction to the execution motor 400 to drive the needle pitch adjustment mechanism 500 to reduce the needle pitch to O2. At this time, the corresponding fabric movement distance of the sewing machine is reduced during subsequent sewing process, so that the number of revolutions required from the second sensor 200 to the third sensor 300 is adjusted to the integer part x and a smaller y value, thereby ensuring that the landing point of the last needle is accurately located at the set position of the edge of the fabric 600. For example, if the original needle pitch O1 is 5 mm, the adjusted needle pitch O2 can be reduced to 4.8 mm, so that the decimal part y of the number of revolutions of the sewing machine when the fabric 600 moves to the third sensor 300 does not exceed k, avoiding the needle falling outside the fabric 600.

[0043] Moreover, the present scheme actively reduces the needle pitch by calculating the decimal part of the number of revolutions in real time, which not only forces the decimal part of the number of revolutions of the sewing machine to be controlled within the threshold range, ensuring that the needle landing point is always located at the set position of the edge of the fabric 600, but also improves the stitch density of the edge region of the fabric 600, thereby improving the sewing strength of the fabric 600.

[0044] But not limited to this, in other embodiments, by setting a needle pitch greater than O1, y≤k can also be achieved.

[0045] In an embodiment, when the controller calculates n>k for three consecutive times, the controller controls the alarm to issue an abnormal alarm and controls the sewing machine to stop running.

[0046] The alarm refers to a device for issuing an abnormal signal, which can be implemented by a buzzer or an LED indicator light, for prompting the operator that the device has an abnormality. The abnormal alarm refers to a state of indicating that the device is running abnormally through an audible and visual signal, which can be implemented by a combination of intermittent beeping and flashing red light, for quickly attracting the attention of the operator. The sewing machine stopping running refers to cutting off the power output to make the device enter a stopped state, which can be implemented by the controller sending a stop instruction to the drive motor, for preventing abnormal working conditions from causing defective products.

[0047] Specifically, when the controller finds that the n value exceeds the preset threshold k for three consecutive times when calculating the needle pitch adjustment parameter, it indicates that the sewing machine needle pitch adjustment system has a persistent abnormality. At this time, the controller first activates the alarm device to issue an audible and visual warning signal, and then sends a stop instruction to the sewing machine drive system to immediately stop the device. This process effectively eliminates accidental error interference by detecting abnormal parameters multiple times in a row, ensuring accurate judgment of the device abnormal state.

[0048] Compared with the prior art, the scheme significantly improves the reliability of fault judgment by setting a continuous three-time abnormality detection mechanism, avoiding unnecessary downtime losses in the production process. At the same time, the scheme realizes rapid response and safety protection of the abnormal state of the equipment through linkage control of the controller and the actuator.

[0049] The application also provides a thread trimming control system that adopts the thread trimming control method of any one of the above embodiments, so that the drop point of the first needle or the last needle of the fabric 600 can fall on the set position of the fabric 600 when sewing to the front edge or the back edge. The thread trimming control system comprises a first sensor 100, a second sensor 200, a third sensor 300, a number of turns sensor, a controller, an execution motor 400 and a stitch length adjusting mechanism 500. The first sensor 100, the second sensor 200, the third sensor 300, the number of turns sensor and the execution motor 400 are respectively electrically connected to the controller. The first sensor 100, the second sensor 200 and the third sensor 300 are sequentially arranged and respectively used to detect the moving position of the fabric. The number of turns sensor is used to record the number of turns of the sewing machine. In addition, the controller can adjust the stitch length of the sewing machine through the execution motor 400 and the stitch length adjusting mechanism 500.

[0050] In some specific embodiments, the position sensors can be arranged at intervals along the conveying direction of the fabric 600, and the interval can be, for example, 10-30 cm. The number of turns sensor can be installed on the main shaft of the sewing machine, and a pulse signal is generated by detecting the number of gear teeth or the polarity change of the magnet. After the controller determines that the remainder exceeds the threshold value, it can send a pulse width modulation signal to the execution motor 400 to drive the stitch length adjusting mechanism 500 to complete the stitch length adjustment within 0.1 seconds.

[0051] The application also provides a sewing machine comprising the thread trimming control system described in the above embodiments.

[0052] The technical features of the above embodiments can be combined in any way. To make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the description.

[0053] The above embodiments only express several implementation manners of the application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the application. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the application, a number of modifications and improvements can be made, which are all within the protection scope of the application. Therefore, the application protection scope should be subject to the appended claims.

[0054] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0055] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0056] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0057] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0058] It is to be understood that the terms "fixedly mounted" and "fixedly attached" should be interpreted broadly to include a direct attachment as well as an indirect attachment via one or more intermediary members. It is also to be understood that the terms "connected" and "coupled" broadly refer to both direct connections and indirect connections via one or more intermediary members. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and the like as used herein are made only for purposes of illustration and are not intended to be limiting.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

Claims

1. A wire-cutting control method, characterized in that, Includes the following steps: Three sequentially arranged position sensors are set to detect the movement of the fabric, which are defined as the first sensor (100), the second sensor (200) and the third sensor (300), respectively. The distance between the first sensor (100) and the second sensor (200) is defined as L1, and the distance between the second sensor (200) and the third sensor (300) is defined as L2. A rotation sensor is set to record the number of rotations of the sewing machine. When the fabric passes the first sensor (100), the controller controls the rotation sensor to start counting. When the fabric reaches the second sensor (200), the controller calculates the current stitch length of the sewing machine based on the number of rotations N recorded by the rotation sensor: O1=L1 / N. The controller calculates the number of rotations required for the sewing machine to move the fabric (600) from the second sensor (200) to the third sensor (300) based on the stitch length of the sewing machine. The result is M = L2 / O1 = m + n, where m is an integer. <n<1; When n>k, when the fabric passes the second sensor (200), the controller adjusts the stitch length of the sewing machine by executing the motor (400) and the stitch length adjustment mechanism (500) so that the adjusted stitch length O2 satisfies L2 / O2=x+y, where x is an integer, 0 ≤ n ≤ k ≤ y. <y<1, y≤k,0.4≤k≤0.6; When n≤k, the controller controls the actuator motor (400) to not operate, and the sewing machine continues to sew according to the stitch length O1.

2. The wire-cutting control method according to claim 1, characterized in that, k equals 0.

5.

3. The wire-cutting control method according to claim 1, characterized in that, It also includes the following steps: After the last stitch is completed, the controller controls the thread-cutting mechanism to trigger thread cutting after a preset time delay.

4. The wire-cutting control method according to claim 3, characterized in that, The preset time t satisfies 0.3s≤t≤0.8s.

5. The wire-cutting control method according to claim 1, characterized in that, When n>k, the adjusted needle pitch O2 controlled by the controller satisfies the following condition: O2 <O1。 6. The wire-cutting control method according to claim 1, characterized in that, When the controller calculates n>k three times consecutively, the controller controls the alarm to issue an abnormal alarm and controls the sewing machine to stop running.

7. The wire-cutting control method according to claim 1, characterized in that, The position sensor is a Hall sensor or a photoelectric sensor.

8. The wire-cutting control method according to claim 1, characterized in that, The revolutions sensor is a rotary encoder or a Hall sensor.

9. A wire-cutting control system, characterized in that, The thread-cutting control system employs the thread-cutting control method described in any one of claims 1-8, ensuring that when the fabric (600) is sewn to the front or back edge, the needle landing point of the first or last stitch falls on a set position on the fabric (600). The thread-cutting control system includes a first sensor (100), a second sensor (200), a third sensor (300), a loop sensor, a controller, an actuator motor (400), and a stitch length adjustment mechanism (500). The first sensor (100), the second sensor (200), the third sensor (300), the loop sensor, and the actuator motor (400) are electrically connected to the controller. The first sensor (100), the second sensor (200), and the third sensor (300) are arranged sequentially and used to detect the movement position of the fabric. The loop sensor is used to record the number of rotations of the sewing machine. The controller can adjust the stitch length of the sewing machine through the actuator motor (400) and the stitch length adjustment mechanism (500).

10. A sewing machine, characterized in that, The sewing machine includes the thread-cutting control system as described in claim 9.

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