Automatic adjustment and anti-collision control method and system for buttonhole machine

Abstract

The present application discloses a method and system for automatically adjusting and anti-collision control of a buttonhole machine, which can detect the thickness of the current sewing material through a thickness detection sensor; and determine whether the thickness of the sewing material exceeds a preset thickness threshold; if the thickness of the sewing material and the thickness of the sewing material when sewing the last buttonhole both exceed the preset thickness threshold or do not exceed the preset thickness threshold, no adjustment is required; if the thickness of the current pressed sewing material exceeds, and the thickness of the sewing material last time did not exceed the preset thickness threshold, it is necessary to adjust the origin position of the feed motor to stagger the position of the presser foot relative to the needle bar screw, so as to avoid collision between the needle bar screw and the presser foot, thereby reducing after-sales costs and reducing the maximum allowable safety value when sewing the last buttonhole; if the thickness of the current pressed sewing material does not exceed, and the thickness of the sewing material last time exceeded the preset thickness threshold, it is necessary to adjust the feed motor back to the origin position, and at the same time, it is necessary to increase the maximum allowable safety value to avoid wasting the maximum sewing range of the buttonhole.

Description

Technical Field

[0001] The present application relates to the field of sewing machines, and in particular to a method and system for automatically adjusting and preventing collisions in buttonhole machines. Background Art

[0002] Due to the structure of traditional buttonholing machines, when the material thickness exceeds the preset value, the screw fastening the needle on the needle bar may collide with the presser foot during sewing, causing abnormal noise or screw breakage, affecting normal user operation and increasing subsequent maintenance costs. In addition, increasing the default distance to avoid collisions will reduce the maximum sewing range, resulting in unnecessary waste. Summary of the Invention

[0003] The purpose of this application is to provide a buttonhole machine automatic adjustment anti-collision control method and system, which can effectively improve the adaptability of the buttonhole machine to the thickness of the sewing material.

[0004] To solve the above technical problems, this application provides the following technical solutions:

[0005] A method for automatically adjusting and preventing collisions of a buttonhole machine, comprising:

[0006] The thickness of the seam material currently being pressed by the presser foot assembly is detected by a thickness detection sensor;

[0007] Determine whether the thickness of the pressed seam material exceeds a preset thickness threshold;

[0008] If the thickness of the pressed sewing material exceeds the preset thickness threshold, and the electronic control system determines that the thickness of the sewing material also exceeded the preset thickness threshold when sewing the previous buttonhole by detecting the position state of the cloth feed motor, then the origin position of the cloth feed motor has been adjusted for anti-collision during the previous sewing, and therefore no adjustment is required when sewing the buttonhole this time, then the current maximum safe allowable value for the buttonhole is the maximum safe allowable value when sewing the previous buttonhole;

[0009] If the thickness of the material being pressed exceeds a preset thickness threshold, and the electronic control system determines that the thickness of the material sewn last time does not exceed the preset thickness threshold by detecting the position state of the cloth feed motor, it is determined that there is a risk of collision between the needle bar screw and the presser foot when sewing the buttonhole this time. Therefore, when sewing the buttonhole this time, the cloth feed motor needs to adjust the origin position to stagger the relative positions of the needle bar screw and the presser foot to avoid collision, and the maximum allowable safety value is reduced according to the adjustment amount of the origin position of the cloth feed motor;

[0010] If the thickness of the sewing material does not exceed the preset thickness threshold, and the electronic control system determines that the thickness of the sewing material last sewn has exceeded the preset thickness threshold by detecting the position state of the cloth feed motor, the cloth feed motor is adjusted back to the initial origin position, and the maximum allowable safety value is increased according to the adjustment amount of the origin position of the cloth feed motor;

[0011] If the thickness of the pressed material does not exceed the preset thickness threshold, and the electronic control system determines that the thickness of the material sewn last time did not exceed the preset thickness threshold by detecting the position state of the cloth feed motor, there is no risk of the needle bar screw colliding with the presser foot in this sewing, and the origin position of the cloth feed motor does not need to be adjusted, then the current maximum allowable safety value of the buttonhole is the maximum allowable safety value when sewing the previous buttonhole.

[0012] In some embodiments, the feed motor controls the presser foot assembly and the feed plate to move toward the needle bar screw to avoid collision between the needle bar screw and the presser foot, and the electronic control system reduces the maximum allowable safety value of the buttonhole; the feed motor controls the presser foot assembly and the feed plate to move away from the needle bar screw, and the electronic control system increases the maximum allowable safety value when sewing the previous buttonhole.

[0013] In some embodiments, after determining the current maximum allowable safety value of the keyhole,

[0014] Determine whether the keyhole length value set by the user exceeds the current maximum allowable safety value of the keyhole;

[0015] If so, stop sewing the buttonhole;

[0016] If not, start sewing the buttonholes.

[0017] In some embodiments, when the keyhole length value set by the user exceeds the current maximum safe allowable keyhole length value, an alarm signal is issued.

[0018] A buttonhole machine automatic adjustment anti-collision control system, comprising:

[0019] Thickness detection sensor, used to detect the thickness of the seam material currently pressed by the presser foot assembly;

[0020] A sewing material thickness determination module, connected to the thickness detection sensor, for determining whether the thickness of the pressed sewing material exceeds a preset thickness threshold;

[0021] an anti-collision adjustment module, connected to the processor;

[0022] If the thickness of the pressed sewing material exceeds the preset thickness threshold, and the electronic control system determines that the thickness of the sewing material also exceeded the preset thickness threshold when sewing the previous buttonhole by detecting the position state of the cloth feed motor, then the origin position of the cloth feed motor has been adjusted for anti-collision during the previous sewing, and therefore no adjustment is required when sewing the buttonhole this time, then the current maximum safe allowable value for the buttonhole is the maximum safe allowable value when sewing the previous buttonhole;

[0023] If the thickness of the material being pressed exceeds a preset thickness threshold, and the electronic control system determines that the thickness of the material sewn last time does not exceed the preset thickness threshold by detecting the position state of the cloth feed motor, it is determined that there is a risk of collision between the needle bar screw and the presser foot when sewing the buttonhole this time. Therefore, when sewing the buttonhole this time, the anti-collision adjustment module needs to adjust the origin position of the cloth feed motor to stagger the relative positions of the needle bar screw and the presser foot to avoid collision, and reduce the maximum allowable safety value according to the adjustment amount of the origin position of the cloth feed motor;

[0024] If the thickness of the pressed sewing material does not exceed the preset thickness threshold, and the electronic control system determines that the thickness of the sewing material last sewn has exceeded the preset thickness threshold by detecting the position state of the cloth feed motor, the anti-collision adjustment module needs to adjust the cloth feed motor back to the initial origin position and increase the maximum allowable safety value according to the adjustment amount of the origin position of the cloth feed motor;

[0025] If the thickness of the pressed material does not exceed the preset thickness threshold, and the electronic control system determines that the thickness of the material sewn last time did not exceed the preset thickness threshold by detecting the position state of the cloth feed motor, there is no risk of the needle bar screw colliding with the presser foot in this sewing, and the origin position of the cloth feed motor does not need to be adjusted, then the current maximum allowable safety value of the buttonhole is the maximum allowable safety value when sewing the previous buttonhole.

[0026] In some embodiments, the anti-collision adjustment module is used to control the presser foot assembly and the feed plate to move toward the needle bar screw through the feed motor to reduce the current maximum allowable safety value of the buttonhole; and control the presser foot assembly and the feed plate to move away from the needle bar screw through the feed motor to increase the current maximum allowable safety value of the buttonhole.

[0027] In some embodiments, a safety start-stop module is also included, which is used to stop sewing the buttonhole when the buttonhole length value set by the user exceeds the current maximum allowable safety value of the buttonhole; and start sewing the buttonhole when the buttonhole length value set by the user does not exceed the current maximum allowable safety value of the buttonhole.

[0028] In some embodiments, an alarm module is further included, which is used to issue an alarm signal when the keyhole length value set by the user exceeds the current maximum allowable safety value of the keyhole.

[0029] Compared with the existing technology, the above technical solution has the following advantages:

[0030] The present application provides an automatic adjustment and anti-collision control method and system for a buttonhole machine, which can detect the thickness of the sewing material currently pressed by the presser foot assembly through a thickness detection sensor; and determine whether the thickness of the sewing material pressed exceeds a preset thickness threshold; and determine whether the thickness of the sewing material exceeds the preset thickness threshold when sewing the previous buttonhole; if the thickness of the sewing material pressed and the thickness of the sewing material when sewing the previous buttonhole both exceed the preset thickness threshold or do not exceed the preset thickness threshold, no adjustment is required; if the thickness of the sewing material pressed exceeds the preset thickness threshold, and the thickness of the sewing material when sewing the previous buttonhole does not exceed the preset thickness threshold, it is necessary to adjust the origin position of the feed motor to stagger the position of the presser foot relative to the needle bar screw, so as to avoid collision between the needle bar screw and the presser foot, thereby reducing after-sales costs and reducing the maximum allowable safety value of the current buttonhole; if the thickness of the sewing material pressed does not exceed the preset thickness threshold, and the thickness of the sewing material exceeds the preset thickness threshold when sewing the previous buttonhole, it is necessary to adjust the feed motor back to the origin position, and at the same time, it is necessary to increase the maximum allowable safety value to avoid wasting the maximum sewing range of the buttonhole. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 A schematic diagram of the partial structure of a buttonholer provided in a specific embodiment of the present application;

[0033] Figure 2 This is a schematic diagram of the partial main structure of a buttonhole machine;

[0034] Figure 3 The present invention provides a flowchart of a method for automatically adjusting and preventing collisions in a buttonhole machine according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0036] The following description sets forth specific details to facilitate a thorough understanding of the present application. However, the present application can be implemented in a variety of other ways than those described herein, and those skilled in the art may make similar generalizations without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0037] Please refer to Figures 1 to 3 , Figure 1 A schematic diagram of the partial structure of a buttonholer provided in a specific embodiment of the present application; Figure 2 This is a schematic diagram of the partial main structure of a buttonhole machine; Figure 3 The present invention provides a flowchart of a method for automatically adjusting and preventing collisions in a buttonhole machine according to a specific embodiment of the present invention.

[0038] A specific embodiment of the present application provides a method for automatically adjusting and preventing collisions of a buttonhole machine, comprising the following steps:

[0039] The thickness of the seam material currently pressed by the presser foot assembly 3 is detected by the thickness detection sensor.

[0040] The system determines whether the thickness of the material being pressed exceeds a preset thickness threshold. Simultaneously, the electronic control system detects the position of the feed motor and determines whether the material thickness exceeded the preset thickness threshold during the previous buttonhole. Based on these two determinations, the following four situations may occur.

[0041] If the thickness of the pressed material exceeds the preset thickness threshold, and the material thickness also exceeded the preset thickness threshold when sewing the previous buttonhole, it means that the feed motor has been adjusted for collision avoidance during the last sewing. Therefore, no adjustment is required when sewing the buttonhole this time. The current maximum allowable safety value L for the buttonhole is the allowable safety value L1 when sewing the previous buttonhole, that is, L=L1.

[0042] If the thickness of the sewing material exceeds the preset thickness threshold, and the thickness of the sewing material did not exceed the preset thickness threshold when sewing the previous buttonhole, it means that the feed motor has not been adjusted for avoidance, and there is a risk of collision between the needle bar screw and the presser foot when sewing the buttonhole this time. Therefore, when sewing the buttonhole this time, the feed motor needs to adjust the origin position to stagger the relative positions of the needle bar screw and the presser foot to avoid collision, and reduce the maximum safety length value according to the adjustment amount of the origin position of the feed motor. The feed motor can be used to control the presser foot assembly 3 and the feed plate 4 to move toward the needle bar screw 2 to stagger the relative positions of the needle bar screw 2 and the presser foot. Figure 1 As shown, the presser foot assembly 3 is installed on the presser foot bracket 5, and the cloth feed plate 4 is installed on the cloth feed bracket 6. Specifically, the cloth feed motor can control the cloth feed bracket 6, the cloth feed plate 4, the presser foot bracket 5, and the presser foot assembly 3 to adjust the distance α in the Y direction. Therefore, the maximum allowable safety value L of the current buttonhole is the allowable safety value L1 when sewing the previous buttonhole minus the adjusted distance α, that is, L=L1-α.

[0043] If the thickness of the sewing material does not exceed the preset thickness threshold, and the thickness of the sewing material exceeded the preset thickness threshold when sewing the previous buttonhole, the feed motor is adjusted back to the initial origin position, and the maximum allowable safety value is increased according to the adjustment amount of the origin position of the feed motor, wherein the feed motor can be used to control the presser foot assembly 3 and the feed plate 4 to move away from the needle bar screw 2 to increase the maximum allowable safety value. Specifically, the feed motor can be used to control the feed bracket 6, the feed plate 4, the presser foot bracket 5, and the presser foot assembly 3 to adjust the distance α in the Y+ direction. Therefore, the maximum allowable safety value L of the current buttonhole is the allowable safety value L1 when sewing the previous buttonhole plus the adjusted distance α, that is, L=L1+α.

[0044] If the thickness of the pressed material does not exceed the preset thickness threshold, and the thickness of the sewing material did not exceed the preset thickness threshold when sewing the previous buttonhole, there is no risk of the needle bar screw colliding with the presser foot during this sewing, and the feed motor origin position does not need to be adjusted. The current maximum allowable safety value L for the buttonhole is the allowable safety value L1 when sewing the previous buttonhole, that is, L=L1.

[0045] By identifying the thickness of the sewing material currently pressed by the presser foot assembly 3 and based on the allowable safety value when sewing the previous buttonhole, it is determined whether anti-collision adjustment is needed. When the thickness of the sewing material exceeds the preset thickness threshold and the thickness of the sewing material for sewing the previous buttonhole does not exceed the preset thickness threshold, it is determined that there is a risk of collision when sewing the buttonhole this time, so it is necessary to adjust the origin position of the feed motor to stagger the relative positions of the needle bar screw and the presser foot to avoid collision and reduce the maximum allowable safety value of the current buttonhole; when the thickness of the sewing material does not exceed the preset thickness threshold, the default distance can be automatically adjusted back to avoid limiting the maximum sewing range of the presser foot assembly 3.

[0046] In some embodiments, after determining the maximum allowable safety value for sewing the current buttonhole:

[0047] The process determines whether the user-set buttonhole length L0 exceeds the current maximum allowable safety value L for the buttonhole. If so, buttonhole sewing is stopped. An alarm may also be issued, such as by displaying a buttonhole size out-of-range sewing alarm screen on a display or emitting an audible alarm. If not, buttonhole sewing is resumed.

[0048] The embodiment of the present application also provides a buttonhole machine automatic adjustment anti-collision control system, such as Figure 1 As shown, the buttonhole machine includes a needle bar 1, a needle bar screw 2, a presser foot assembly 3, a feed plate 4, a presser foot bracket 5, and a feed bracket 6. The needle bar screw 2 is connected to the needle bar 1, the presser foot assembly 3 is installed on the presser foot bracket 5, and the feed plate 4 is installed on the feed bracket 6. The maximum thickness of the sewing material A is shown in FIG. Figure 2As shown, the control system includes: a thickness detection sensor for detecting the thickness δ of the seam material currently pressed by the presser foot assembly 3; a seam material thickness judgment module connected to the thickness detection sensor for judging whether the thickness of the seam material pressed exceeds a preset thickness threshold; and an anti-collision adjustment module connected to the processor.

[0049] If the thickness of the material being pressed exceeds the preset thickness threshold, and the electronic control system detects the position state of the cloth feed motor and determines that the thickness of the material exceeded the preset thickness threshold when sewing the previous buttonhole, then the cloth feed motor origin position has been adjusted for anti-collision during the previous sewing, so no adjustment is required when sewing the buttonhole this time. The current maximum safe allowable value for the buttonhole is the maximum safe allowable value when sewing the previous buttonhole;

[0050] If the thickness of the material being pressed exceeds the preset thickness threshold, and the electronic control system determines that the thickness of the material sewn last time does not exceed the preset thickness threshold by detecting the position state of the cloth feed motor, then it is determined that there is a risk of collision between the needle bar screw and the presser foot when sewing the buttonhole this time. Therefore, when sewing the buttonhole this time, the anti-collision adjustment module needs to adjust the origin position of the cloth feed motor to stagger the relative positions of the needle bar screw and the presser foot to avoid collision, and reduce the maximum allowable safety value according to the adjustment amount of the origin position of the cloth feed motor;

[0051] If the thickness of the pressed sewing material does not exceed the preset thickness threshold, and the electronic control system determines that the thickness of the sewing material last sewn has exceeded the preset thickness threshold by detecting the position state of the feed motor, the anti-collision adjustment module needs to adjust the feed motor back to the initial origin position and increase the maximum allowable safety value according to the adjustment amount of the feed motor's origin position;

[0052] If the thickness of the material being pressed does not exceed the preset thickness threshold, and the electronic control system determines that the thickness of the material sewn last time did not exceed the preset thickness threshold by detecting the position status of the feed motor, there is no risk of the needle bar screw colliding with the presser foot during this sewing, and the feed motor origin position does not need to be adjusted. In this case, the current maximum allowable safety value for the buttonhole is the maximum allowable safety value when sewing the previous buttonhole.

[0053] In some embodiments, as Figure 1 and Figure 2 As shown in FIG, when the maximum safety length value of the buttonhole needs to be reduced, the cloth feed motor can be used to control the cloth feed bracket 6, cloth feed plate 4, presser foot bracket 5, and presser foot assembly 3 to adjust the distance α in the Y-direction. Therefore, the maximum safety allowable length L of the current buttonhole is the allowable safety value L1 when sewing the previous buttonhole minus the adjusted distance α, that is, L = L1-α; similarly, Figure 1 and Figure 2As shown, when the maximum safety length value needs to be increased, the cloth feed motor can be used to control the cloth feed bracket 6, cloth feed plate 4, presser foot bracket 5, and presser foot assembly 3 to adjust the distance α in the Y+ direction. Therefore, the maximum allowable safety value L is the allowable safety value L1 when sewing the previous buttonhole plus the adjusted distance α, that is, L=L1+α.

[0054] In some embodiments, a safety start-stop module is also included, which is used to stop sewing the buttonhole when the buttonhole length value set by the user exceeds the current maximum allowable safety value of the buttonhole, so as to prevent collision damage and thereby reduce after-sales costs; when the buttonhole length value set by the user does not exceed the current maximum allowable safety value of the buttonhole, the buttonhole is started to be sewn.

[0055] In some embodiments, an alarm module is also included for issuing an alarm signal when the buttonhole length value set by the user exceeds the current maximum allowable safety value of the buttonhole. For example, a buttonhole size out-of-range sewing alarm interface can be displayed on a display, or a sound alarm signal can be issued.

[0056] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for automatically adjusting and preventing collisions in a buttonhole machine, characterized in that: include: The thickness of the seam material currently being pressed by the presser foot assembly is detected by a thickness detection sensor; Determine whether the thickness of the pressed seam material exceeds a preset thickness threshold; If the thickness of the pressed sewing material exceeds the preset thickness threshold, and the electronic control system determines that the thickness of the sewing material also exceeded the preset thickness threshold when sewing the previous buttonhole by detecting the position state of the cloth feed motor, then the origin position of the cloth feed motor has been adjusted for anti-collision during the previous sewing, and therefore no adjustment is required when sewing the buttonhole this time, then the maximum safe allowable value of the current buttonhole is the maximum safe allowable value when sewing the previous buttonhole; If the thickness of the material being pressed exceeds a preset thickness threshold, and the electronic control system determines that the thickness of the material sewn last time does not exceed the preset thickness threshold by detecting the position state of the cloth feed motor, it is determined that there is a risk of collision between the needle bar screw and the presser foot when sewing the buttonhole this time. Therefore, when sewing the buttonhole this time, the cloth feed motor needs to adjust the origin position to stagger the relative positions of the needle bar screw and the presser foot to avoid collision, and the maximum allowable safety value is reduced according to the adjustment amount of the origin position of the cloth feed motor; If the thickness of the sewing material does not exceed the preset thickness threshold, and the electronic control system determines that the thickness of the sewing material last sewn has exceeded the preset thickness threshold by detecting the position state of the cloth feed motor, the cloth feed motor is adjusted back to the initial origin position, and the maximum allowable safety value is increased according to the adjustment amount of the origin position of the cloth feed motor; If the thickness of the pressed material does not exceed the preset thickness threshold, and the electronic control system determines that the thickness of the material sewn last time did not exceed the preset thickness threshold by detecting the position state of the cloth feed motor, there is no risk of the needle bar screw colliding with the presser foot in this sewing, and the origin position of the cloth feed motor does not need to be adjusted, then the current maximum allowable safety value of the buttonhole is the maximum allowable safety value when sewing the previous buttonhole.

2. The control method according to claim 1, characterized in that: The feed motor controls the presser foot assembly and the feed plate to move toward the needle bar screw to avoid collision between the needle bar screw and the presser foot, and the electronic control system reduces the maximum allowable safety value of the buttonhole; the feed motor controls the presser foot assembly and the feed plate to move away from the needle bar screw, and the electronic control system increases the maximum allowable safety value when sewing the previous buttonhole.

3. The control method according to claim 1, wherein: After determining the maximum safe allowable length of the current keyhole, Determine whether the keyhole length value set by the user exceeds the current maximum safe allowable keyhole length value; If so, stop sewing the buttonhole; If not, start sewing the buttonholes.

4. The control method according to claim 3, characterized in that: When the keyhole length value set by the user exceeds the current maximum safe allowable keyhole length value, an alarm signal is issued.

5. A buttonhole machine automatic adjustment anti-collision control system, characterized in that: include: Thickness detection sensor, used to detect the thickness of the seam material currently pressed by the presser foot assembly; A sewing material thickness determination module, connected to the thickness detection sensor, for determining whether the thickness of the pressed sewing material exceeds a preset thickness threshold; an anti-collision adjustment module connected to the processor; If the thickness of the pressed sewing material exceeds the preset thickness threshold, and the electronic control system determines that the thickness of the sewing material also exceeded the preset thickness threshold when sewing the previous buttonhole by detecting the position state of the cloth feed motor, then the origin position of the cloth feed motor has been adjusted for anti-collision during the previous sewing, and therefore no adjustment is required when sewing the buttonhole this time, then the current maximum safe allowable value for the buttonhole is the maximum safe allowable value when sewing the previous buttonhole; If the thickness of the material being pressed exceeds a preset thickness threshold, and the electronic control system determines that the thickness of the material sewn last time does not exceed the preset thickness threshold by detecting the position state of the cloth feed motor, it is determined that there is a risk of collision between the needle bar screw and the presser foot when sewing the buttonhole this time. Therefore, when sewing the buttonhole this time, the anti-collision adjustment module needs to adjust the origin position of the cloth feed motor to avoid collision, and reduce the maximum allowable safety value according to the adjustment amount of the origin position of the cloth feed motor; If the thickness of the pressed sewing material does not exceed the preset thickness threshold, and the electronic control system determines that the thickness of the sewing material last sewn has exceeded the preset thickness threshold by detecting the position state of the cloth feed motor, the anti-collision adjustment module needs to adjust the cloth feed motor back to the initial origin position and increase the maximum allowable safety value according to the adjustment amount of the origin position of the cloth feed motor; If the thickness of the pressed material does not exceed the preset thickness threshold, and the electronic control system determines that the thickness of the material sewn last time did not exceed the preset thickness threshold by detecting the position state of the cloth feed motor, there is no risk of the needle bar screw colliding with the presser foot in this sewing, and the origin position of the cloth feed motor does not need to be adjusted, then the current maximum allowable safety value of the buttonhole is the maximum allowable safety value when sewing the previous buttonhole.

6. The control method according to claim 5, characterized in that: The anti-collision adjustment module is used to control the presser foot assembly and the feed plate to move toward the needle bar screw through the feed motor to reduce the maximum allowable safety value of the current buttonhole; and control the presser foot assembly and the feed plate to move away from the needle bar screw through the feed motor to increase the maximum allowable safety value of the current buttonhole.

7. The control method according to claim 5, characterized in that: It also includes a safety start-stop module, which is used to stop sewing the buttonhole when the buttonhole length value set by the user exceeds the current maximum allowable safety value of the buttonhole; and start sewing the buttonhole when the buttonhole length value set by the user does not exceed the current maximum allowable safety value of the buttonhole.

8. The control method according to claim 7, characterized in that: It also includes an alarm module for sending an alarm signal when the keyhole length value set by the user exceeds the current maximum allowable safety value of the keyhole.

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