A sewing method for a sewing machine

Abstract

The present invention provides a sewing method for a sewing machine, belonging to the technical field of sewing equipment. The method solves the problem of reverse stitching during the sewing process in existing sewing machines, which affects the sewing quality. The sewing method comprises the following steps: S1, dividing the moving plane of the feeder into a trigger area, a needle bar reverse rotation area, and a needle bar forward rotation area; S2, a controller generates a needle point trajectory and a motion trajectory of the feeder according to the sewing pattern; S3, the sewing machine starts working and sews the first stitch; S4, the feeder drives the sewing material to the next stitch sewing position according to the motion trajectory; S5, repeating step S4 and performing subsequent sewing according to the needle point trajectory obtained from the sewing pattern. The present invention has the advantages of high sewing efficiency and good sewing quality.

Description

Technical Field

[0001] This invention belongs to the field of sewing equipment technology and relates to a sewing method for a sewing machine. Background Technology

[0002] A sewing machine is a device that uses one or more threads to create stitches on fabric, allowing two or more layers of fabric to be sewn together. When traditional sewing machines sew patterns, the fabric moves horizontally in different directions with the feed mechanism, resulting in some stitches being forward stitches (301 stitch) and others being reverse stitches (319 stitch). Since forward stitches generally ensure aesthetics and consistency, they are used exclusively for sewing high-end garments and leather goods where high quality is required. Therefore, to maintain the product's appearance, reverse stitches must be avoided.

[0003] To address this technical problem, the applicant previously used a thread-shifting lever to switch the thread thread between the rotary hook and the needle plate, thus preventing reverse stitches during sewing. For example, a sewing machine and sewing method disclosed in patent literature (application number: 202510475452.3) includes a base, a needle plate, a bottom shuttle, a transmission rod, and a thread-shifting lever. The transmission rod is located on the side of the bottom shuttle and movably connected to the base. One end of the transmission rod near the bottom shuttle is fixedly connected to one end of the thread-shifting lever, and the other end of the transmission rod is connected to a thread-shifting drive component. Driven by the thread-shifting drive component, the transmission rod can reciprocate axially and oscillate simultaneously, causing the other end of the thread-shifting lever to perform a circumferential cyclical motion and be positioned between the needle hole and the bottom shuttle. In this sewing machine, the plane where the centerline of the bobbin and the sewing machine needle lie is the critical surface A. The vertical plane where the line connecting the bobbin's thread outlet and the needle hole is inclined is the critical surface B. The area between the side of critical surface A facing away from the thread outlet and the side of critical surface B facing away from the bobbin tip is the reverse stitch area. When the feed direction is towards the reverse stitch area, the thread lever performs a thread-pulling action, thereby converting the reverse stitch into a forward stitch, improving the sewing aesthetics and quality. However, the following shortcomings still exist:

[0004] like Figure 10As shown, in this sewing machine, the needle bar can only move up and down and cannot adjust its circumferential angle. Therefore, the needle groove on the needle bar always faces directly behind the sewing machine, and the center line of the needle hole on the needle coincides with the critical surface A. During actual sewing, when the feeding device moves forward along the center line of the needle hole (i.e., critical surface A), the position of the thread relative to the needle is uncertain due to factors such as thread drift, needle bar movement error, and equipment vibration. That is, the thread sometimes passes around the left side of the needle and sometimes around the right side. This change in the thread's position directly affects the type of stitch. If we want all stitches to be positive when the feeding device moves forward along the center line of the needle hole (i.e., critical surface A), we must control the thread guide lever to selectively guide the thread. However, because the position of the thread relative to the needle is uncertain, the controller cannot determine whether the thread guide lever needs to guide the thread, resulting in some reverse stitches still appearing on the fabric, affecting the sewing quality and aesthetics. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a sewing method for a sewing machine. This invention solves the problem that reverse stitches occur during the sewing process in existing sewing machines, which affects the sewing quality, while simultaneously enabling the sewing machine to have higher sewing efficiency.

[0006] The objective of this invention can be achieved through the following technical solution: a sewing method for a sewing machine, the sewing machine comprising a rotary hook, a thread guide, a needle bar with a needle connected to its lower end, a needle plate with a needle drop hole, and a feeding device for fixing and moving the sewing fabric. The rotary hook has a thread outlet for the thread thread to pass through. The vertical plane where the axis of the rotary hook is located is a critical plane A. The line connecting the thread outlet and the needle drop hole is inclined, and the vertical plane where this line is located is a critical plane B. The area between the left side of critical plane A and the front side of critical plane B is region a, and the area between the right side of critical plane A and the front side of critical plane B is region b. The sewing machine also includes a needle bar rotation structure for driving the needle bar to reciprocate around its axis. The sewing method comprises the following steps:

[0007] S1. Divide the moving plane of the feeding device into a trigger area, a needle bar reverse rotation area, and a needle bar forward rotation area:

[0008] The triggering region is the region other than region a, but includes at least region b;

[0009] The needle bar reversal area is the area within area a swept by the critical surface A when it rotates clockwise around the needle hole by a preset angle from a top-view angle, and is smaller than area a;

[0010] The clockwise rotation region of the needle bar is located within the triggering region, and it is the symmetrical region of the counterclockwise rotation region of the needle bar with respect to the critical surface A.

[0011] S2. The controller generates the needle point trajectory and the motion trajectory of the feeding device according to the sewing pattern;

[0012] S3. The sewing machine starts working and sews the first stitch;

[0013] S4. The feeding device moves the fabric to the next stitch position according to the motion trajectory. If the feeding device moves towards the trigger area, the following actions are performed:

[0014] S4-1. The controller controls the thread-picking lever to perform the thread-picking action, causing the end of the thread-picking lever to move from the lower front of the needle hole to the lower rear. Furthermore, the controller adjusts the angle position of the needle bar according to whether the moving direction of the feeding device is towards the clockwise rotation area of ​​the needle bar. If so, the needle bar is adjusted to the preset target angle value 1 through the needle bar rotation structure, so that the center line C of the needle hole on the needle passes through the counterclockwise rotation area of ​​the needle bar. If not, the needle bar rotation structure does not move, and the needle bar maintains the current angle position.

[0015] S4-2, The needle bar moves the needle downward, bringing the top thread to the bottom of the needle plate, and the rotary hook interweaves the top thread and the bottom thread to form a stitch;

[0016] If the feeding device does not move towards the trigger area, the following actions are performed:

[0017] S4-3. The controller controls the thread-picking lever to pause the thread-picking action and adjusts the angle position of the needle bar according to whether the movement direction is towards the needle bar reversal area. If so, the needle bar is adjusted to the preset target angle value two through the needle bar rotation structure so that the center line C of the needle hole on the needle passes through the needle bar clockwise rotation area. If not, the needle bar rotation structure does not move and the needle bar maintains the current angle position.

[0018] S4-4. The needle bar moves the needle downward, bringing the top thread to the bottom of the needle plate. The rotary hook interweaves the top thread and the bottom thread to form a stitch.

[0019] S5. Repeat step S4 and continue sewing according to the needle point trajectory obtained from the sewing pattern.

[0020] This sewing method makes the following improvements based on existing technology:

[0021] Regarding the control logic of the thread-pulling lever, whether it performs the thread-pulling action depends on whether the feeding device moves towards the trigger area. When the feeding device moves towards the trigger area, the thread-pulling lever performs the thread-pulling action; otherwise, it pauses. Furthermore, area b is the reverse stitch area requiring thread pulling (i.e., the area where direct sewing would create a reverse stitch if the thread-pulling lever does not pull the thread). Since the trigger area includes at least area b, this ensures that the thread-pulling lever pulls the thread whenever the feeding device moves towards the trigger area, thereby converting the reverse stitch into a forward stitch.

[0022] Specifically, during the sewing process, if the feeding device moves towards the trigger area, there are two possibilities:

[0023] In one scenario, the movement direction is towards the clockwise rotation area of ​​the needle bar. In this case, due to the needle bar rotation structure, the needle bar is adjusted to the preset target angle value, and the center line C of the needle hole passes through the counter-clockwise rotation area of ​​the needle bar. This prevents the feeding device from moving forward along the center line C of the needle hole, thus avoiding the problem of the top thread sometimes going around the left side of the needle and sometimes around the right side during sewing. In this situation, as long as the thread guide lever is controlled to guide the thread normally, it can be ensured that the sewing process consists entirely of forward stitches.

[0024] The second scenario is when the direction of movement is not towards the clockwise rotation area of ​​the needle bar. In this case, regardless of whether the needle bar is at target angle value one or target angle value two, the feeding device will not move forward along the center line C of the needle hole. In this case, simply keep the needle bar at its current angle position and control the thread-pulling lever to pull the thread normally to ensure that the sewing process is all positive stitches.

[0025] If the feeding device does not move towards the trigger area, there are two possibilities:

[0026] In one scenario, the movement direction is towards the needle bar's reverse rotation area. In this case, due to the needle bar's rotating structure, the needle bar adjusts to the preset target angle value two, and the center line C of the needle hole passes through the needle bar's clockwise rotation area. This prevents the feeding device from moving forward along the center line C of the needle hole. In this situation, the sewing process does not require the thread guide lever to change the position of the bobbin thread relative to the needle, and a positive stitch can still be formed. Therefore, simply controlling the thread guide lever to pause thread feeding ensures that the sewing process consists entirely of positive stitches.

[0027] The second scenario is when the direction of movement is not towards the reverse area of ​​the needle bar. In this case, regardless of whether the needle bar is at target angle value one or target angle value two, the feeding device will not move forward along the center line C of the needle hole. In this case, it is only necessary to control the thread-pulling lever to pause thread pulling to ensure that the sewing process is all positive stitches.

[0028] In summary, this sewing method, through the rotation of the needle bar in conjunction with the thread-pulling action of the thread-pulling lever, can avoid reverse stitches during sewing, thereby improving sewing quality. Furthermore, by dividing the moving plane of the feeding device into a reverse-rotation zone and a forward-rotation zone for the needle bar, both smaller than zone 'a', the needle bar rotation structure only performs the action of driving the needle bar to rotate when the moving direction of the feeding device is within these two zones. This design means that during sewing, the needle bar rotation structure does not need to move in most situations; it only needs to maintain the current angle position for needle insertion. Therefore, the stability of the needle bar is greatly improved, resulting in precise needle insertion and enhanced sewing quality.

[0029] Furthermore, when the needle bar is adjusted to the preset target angle value one, the angle of deflection of the needle bar is small, ensuring that the center line C of the needle hole passes through the clockwise rotation area of ​​the needle bar. The same applies when the needle bar is adjusted to the preset target angle value two. This design ensures that the needle bar remains at either target angle value one or target angle value two throughout the entire cycle of each needle insertion action, eliminating the need for needle bar angle adjustment during insertion. This avoids situations where excessive needle deflection prevents the shuttle tip from entering the needle groove for thread hooking, while also allowing the needle bar to insert the needle quickly, thus significantly improving sewing efficiency while ensuring sewing quality.

[0030] In the sewing method of the sewing machine described above, the sewing machine also includes a base, a drive source, and a thread guide seat movably disposed on the base. The thread guide rod is disposed on the thread guide seat. In step S4-3, the controller controls the thread guide rod to pause the thread guiding action specifically by controlling the drive source to rotate or translate the thread guide seat horizontally, so that the thread guide rod moves away from the rotary hook.

[0031] During sewing, when thread cutting is required, such as cutting the starting thread, the tail thread, or the bobbin thread, the thread-cutting blade needs to move between the needle hole and the rotary hook to perform the cutting operation. In this thread-picking mechanism, the thread-picking seat is movably mounted on the base, rather than being fixedly connected as in traditional methods. This means that when the sewing machine needs to cut the thread, the drive mechanism simply rotates or translates the thread-picking seat horizontally, causing the thread-picking lever on the seat to move away from the rotary hook and avoid the movement path of the thread-cutting blade, thus preventing interference between the cutting blade and the lever. This method only requires simple rotation control of the previously stationary thread-picking seat by the drive mechanism to ensure the thread-picking lever stably and accurately reaches the predetermined avoidance position. During this process, the motor driving the thread-picking lever continues to run, ensuring continuous movement of the lever. This reduces the frequency of motor starts and stops, greatly simplifying control and effectively preventing collisions between the thread-picking lever and the cutting blade, significantly improving the reliability of the sewing process and further enhancing sewing quality.

[0032] In the sewing method of the sewing machine described above, step S4-1, adjusting the needle bar to the preset target angle value one by means of the needle bar rotation structure, specifically: if the needle bar is already at the target angle value one, the needle bar rotation structure does not move; if the needle bar is not at the target angle value one, the needle bar rotation structure drives the needle bar to rotate to the target angle value one.

[0033] In the needle bar rotation structure, the driving method can be either cylinder drive or servo motor drive. Cylinder drive is preferred, where the extension and retraction of the cylinder piston rod drives the needle bar to rotate back and forth, switching between target angle value one and target angle value two. The specific implementation of how the cylinder drives the needle bar rotation can be achieved by those skilled in the art using common knowledge, and will not be described in detail here. When the needle bar is already at target angle value one, the needle bar rotation structure remains stationary, avoiding unnecessary movement; only when the needle bar is not at target angle value one does the needle bar rotation structure adjust it into position. This design simplifies control complexity and reduces the operating frequency of the cylinder or servo motor, thereby improving its operational reliability and service life, ensuring the accuracy of the needle bar angle during sewing, ensuring that all sewn stitches are positive stitches, and effectively improving sewing quality.

[0034] In the sewing method of the sewing machine described above, step S4-3, adjusting the needle bar to the preset target angle value two by means of the needle bar rotation structure, specifically: if the needle bar is already at the target angle value two, the needle bar rotation structure does not move; if the needle bar is not at the target angle value two, the needle bar rotation structure drives the needle bar to rotate to the target angle value two.

[0035] In this design, the needle bar rotation structure remains stationary when the needle bar is at the target angle value two; only when the needle bar is not at the target angle value two does the rotation structure adjust it into position. Similarly, this design further simplifies control, reduces the operating frequency of the cylinder or servo motor, thereby improving its operational reliability and service life, ensuring the accuracy of the needle bar angle during sewing, and ensuring that all sewn stitches are positive stitches.

[0036] In the sewing method of the above-mentioned sewing machine, the rear side of the needle has a needle groove for the tip of the rotary hook to pass through for hooking the thread. In step S4-1, when the needle bar is located at a preset target angle value one, the orientation of the needle groove on the needle is deflected clockwise by 6-12 degrees relative to the critical surface A from a top-view angle. In step S4-3, when the needle bar is located at a preset target angle value two, the orientation of the needle groove on the needle is deflected counterclockwise by 6-12 degrees relative to the critical surface A from a top-view angle. The deflection angle of the needle is controlled within 12 degrees, avoiding the situation where the tip of the rotary hook cannot enter the needle groove of the needle for hooking the thread due to excessive needle deflection. This ensures that the rotary hook can accurately and stably hook the top thread on the needle and expand the thread loop, so that it can stably interweave with the bottom thread, avoiding hooking failure, failure to form a stitch, and skipped stitches, thereby significantly improving the sewing quality and ensuring the uniformity and stability of the sewing stitch.

[0037] In the sewing method of the sewing machine described above, the triggering area refers to all areas other than area a. This design features a relatively large triggering area, ensuring that the thread guide lever remains in a normal thread-pulling state most of the time during sewing. It only switches to a paused thread-pulling state when the feeding device enters area a, which has a relatively small angle range. This design significantly reduces the number of times the thread guide lever switches between states, avoiding the problem of increased mechanical errors caused by frequent state switching. This results in a more stable sewing process, more uniform stitches, and ultimately improved sewing quality.

[0038] In the sewing method of the sewing machine described above, the triggering area is area b, or the area to the right of the critical surface A. When the triggering area is area b, it ensures that when the feeding device moves towards area b, the thread guide lever engages to guide the thread, thereby converting the reverse stitch into a forward stitch. When the triggering area is the area to the right of the critical surface A, which also includes area b, it ensures that when the feeding device moves towards area b, the thread guide lever engages to guide the thread, thereby converting the reverse stitch into a forward stitch.

[0039] In the sewing method of the sewing machine described above, in step S4-1, while the needle bar rotating structure drives the needle bar to rotate to the target angle value, the feeding device moves the fabric to the next stitch position. In this design, the step of rotating the needle bar to adjust the needle bar angle is synchronized with the movement of the feeding device, which can improve sewing efficiency.

[0040] In the sewing method of the sewing machine described above, in step S4-3, while the needle bar rotating structure drives the needle bar to rotate to the target angle value two, the feeding device moves the fabric to the next stitch position. In this design, the step of rotating the needle bar to adjust the needle bar angle is synchronized with the movement of the feeding device, which can improve sewing efficiency.

[0041] In the sewing method described above, the needle bar reversal zone is the area within region a swept by the critical surface A, which rotates clockwise by 16-25 degrees around the needle hole from a top-view angle. This design ensures that when the feeding device moves forward near the critical surface A, the rotation of the needle bar prevents the center line C of the needle hole from coinciding with the critical surface A, thus preventing the feeding device from moving forward along the center line C of the needle hole and avoiding reverse stitches. Simultaneously, this design also results in a smaller proportion of the needle bar reversal zone and its symmetrical clockwise rotation zone, meaning that the needle bar rotation structure does not require movement in most cases, significantly improving needle bar stability and thus enhancing sewing quality.

[0042] Compared with existing technologies, the sewing method of this sewing machine has the following advantages:

[0043] 1. This sewing method, through the rotation of the needle bar and the thread-pulling action of the thread-pulling lever, can avoid the occurrence of reverse stitches during the sewing process, thereby improving the sewing quality.

[0044] 2. In this sewing method, the needle bar rotation structure does not need to move in most cases. It only needs to keep the needle bar at a fixed angle position. Therefore, the stability of the needle bar is greatly improved, which makes the needle insertion position more accurate and thus improves the sewing quality.

[0045] 3. In this sewing method, the needle bar remains at target angle value one or target angle value two throughout the entire cycle of each needle insertion action, reducing unnecessary angle adjustment actions. This not only avoids the situation where the shuttle tip cannot enter the needle groove to hook the thread due to excessive needle deflection, but also allows the needle bar to insert the needle quickly, thereby significantly improving sewing efficiency. Attached Figure Description

[0046] Figure 1 This is a partial structural diagram of the sewing machine.

[0047] Figure 2 This is a top view of the rotary shuttle.

[0048] Figure 3 This is a flowchart of the sewing method.

[0049] Figure 4 This is a schematic diagram of the needle bar at a preset target angle value.

[0050] Figure 5 This is a schematic diagram of the needle bar at a preset target angle value of 2.

[0051] Figure 6 This is a structural diagram of the drive source, dial holder, and dial lever.

[0052] Figure 7 This is a schematic diagram of the machine needle.

[0053] Figure 8 This is a schematic diagram of the needle bar being at a preset target angle value in Example 5.

[0054] Figure 9 This is a schematic diagram of the needle bar being at a preset target angle value in Embodiment Six.

[0055] Figure 10 This is a schematic diagram showing the needle groove of a machine needle facing directly backward in the prior art.

[0056] In the diagram, 1 is the base; 2 is the rotary hook; 21 is the thread outlet; 22 is the hook tip; 3 is the thread guide lever; 4 is the drive source; 5 is the thread guide seat; 6 is the needle; 61 is the needle groove; 62 is the needle hole; 7 is the needle bar; 8 is the needle plate; and 81 is the needle drop hole. Detailed Implementation

[0057] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0058] Example 1

[0059] like Figure 1 and Figure 2 As shown, the sewing machine includes a base 1, a rotary hook 2, a drive source 4, a needle bar 7 with a needle 6 connected to its lower end, a needle plate 8 with a needle drop hole 81, a thread guide 5 movably mounted on the base 1, a needle bar rotation structure for driving the needle bar 7 to rotate around its axis, and a feeding device for fixing and moving the sewing fabric. A thread guide 3 is mounted on the thread guide 5. The feeding device is prior art and is not shown in the figure. Figure 7 As shown, the rear side of the needle 6 has a needle groove 61 through which the tip 22 of the rotary hook 2 passes for thread hooking. In the needle bar rotation structure, the driving method can be either cylinder drive or servo motor drive. Cylinder drive is preferred, where the extension and retraction of the cylinder piston rod drives the needle bar 7 to rotate back and forth, switching between target angle value one and target angle value two. As to how the cylinder specifically drives the needle bar 7 to rotate, those skilled in the art can implement it using common knowledge, and this article will not elaborate further.

[0060] like Figure 2 As shown, the rotary hook 2 has an outlet 21 for the bottom thread to pass through. The vertical plane where the axis of the rotary hook 2 is located is the critical plane A. The line connecting the outlet 21 and the needle hole 81 is inclined and the vertical plane where the line is located is the critical plane B. The area between the left side of the critical plane A and the front side of the critical plane B is the area a, and the area between the right side of the critical plane A and the front side of the critical plane B is the area b.

[0061] like Figure 3 As shown, this sewing method includes the following steps:

[0062] S1. Divide the moving plane of the feeding device into a trigger area, a needle bar reverse rotation area, and a needle bar forward rotation area:

[0063] The triggering region is the region other than region a, but includes at least region b. Specifically, in this embodiment, as follows... Figure 4 As shown, the triggering area is all areas other than area a.

[0064] like Figure 4 As shown, the needle bar reversal region is the area within region a swept by the critical surface A when it is deflected 20 degrees clockwise around the needle hole 81 from a top-view angle, and it is smaller than region a. Of course, in actual situations, the deflection angle can be appropriately increased or decreased, and it is usually controlled between 16 and 25 degrees.

[0065] The clockwise rotation region of the needle bar is located within the trigger region, and it is the symmetrical region of the counterclockwise rotation region of the needle bar with respect to the critical surface A.

[0066] S2. The controller generates the needle point trajectory and the motion trajectory of the feeding device according to the sewing pattern;

[0067] S3. The sewing machine starts working and sews the first stitch;

[0068] S4. The feeding device moves the fabric to the next stitch position according to the motion trajectory. If the feeding device moves towards the trigger area, the following actions are performed:

[0069] S4-1, The controller controls the wire-picking lever 3 to perform a wire-picking action, causing the end of the wire-picking lever 3 to move from the lower front to the lower rear of the needle drop hole 81. Furthermore, the controller adjusts the angle position of the needle bar 7 according to whether the feeding device's movement direction is towards the needle bar's clockwise rotation area. If so, then... Figure 4 As shown, the needle bar 7 is adjusted to the preset target angle value by the needle bar rotation structure. At this time, the orientation of the needle groove 61 on the needle 6 is deflected 8 degrees clockwise relative to the critical surface A in the top view, and the center line C of the needle hole 62 on the needle 6 passes through the needle bar reversal area; otherwise, the needle bar rotation structure does not move, and the needle bar 7 maintains the current angle position.

[0070] S4-2, the needle bar 7 drives the needle 6 to move down, bringing the top thread to the bottom of the needle plate 8, and the rotary hook 2 interweaves the top thread and the bottom thread to form a stitch;

[0071] If the feeding device does not move towards the trigger area, the following actions are performed:

[0072] S4-3, The controller stops the thread-picking action of the thread-picking lever 3, and adjusts the angle position of the needle bar 7 according to whether the moving direction of the feeding device is towards the needle bar reversal area. If so, ... Figure 5 As shown, the needle bar 7 is adjusted to the preset target angle value 2 by the needle bar rotation structure. At this time, the orientation of the needle groove 61 on the needle 6 is deflected counterclockwise by 8 degrees relative to the critical surface A in the top view angle, and the center line C of the needle hole 62 on the needle 6 passes through the needle bar clockwise rotation area. Otherwise, the needle bar rotation structure does not move, and the needle bar 7 maintains the current angle position.

[0073] S4-4, the needle bar 7 drives the needle 6 to move down, bringing the top thread to the bottom of the needle plate 8, and the rotary hook 2 interweaves the top thread and the bottom thread to form a stitch;

[0074] S5. Repeat step S4 and continue sewing according to the needle point trajectory obtained from the sewing pattern.

[0075] Among them, such as Figure 6 As shown, the drive source 4 is a cylinder, and the piston rod of the cylinder is connected to the cable-picking seat 5. In step S4-3, the controller controls the cable-picking lever 3 to pause the cable-picking action, specifically as follows: Figure 1 As shown, the controller controls the piston rod of the cylinder to extend, causing the thread take-up seat 5 to rotate horizontally, making the front end of the thread take-up lever 3 swing forward and away from the rotary hook 2. After moving away from the rotary hook 2, even if the thread take-up lever 3 is still in motion, it will not come into contact with the bottom thread between the needle plate 8 and the rotary hook 2.

[0076] Further, in step S4-1, adjusting the needle bar 7 to the preset target angle value one via the needle bar rotation structure specifically involves: if the needle bar 7 is already at the target angle value one, the needle bar rotation structure does not operate; if the needle bar 7 is not at the target angle value one, the needle bar rotation structure drives the needle bar 7 to rotate to the target angle value one. In step S4-3, adjusting the needle bar 7 to the preset target angle value two via the needle bar rotation structure specifically involves: if the needle bar 7 is already at the target angle value two, the needle bar rotation structure does not operate; if the needle bar 7 is not at the target angle value two, the needle bar rotation structure drives the needle bar 7 to rotate to the target angle value two. In step S4-1, while the needle bar rotation structure drives the needle bar 7 to rotate to the target angle value one, the feeding device moves the sewing material to the next stitching position. In step S4-3, while the needle bar rotation structure drives the needle bar 7 to rotate to the target angle value two, the feeding device moves the sewing material to the next stitching position. In this design, the step of rotating the needle bar 7 to adjust its angle is synchronized with the movement of the feeding device, which can improve sewing efficiency.

[0077] The following is a brief explanation of the principle behind this sewing method to avoid reverse stitches:

[0078] In this sewing machine, the control logic for the thread guide lever 3 determines whether it performs the thread-pulling action based on whether the feeding device moves towards the trigger area. When the feeding device moves towards the trigger area, the thread guide lever 3 performs the thread-pulling action; otherwise, it pauses thread pulling. In this implementation, the trigger area is all areas except area a, including area b. Area b is the area requiring thread pulling for reverse stitches (i.e., the area where direct sewing would create a reverse stitch if the thread guide lever 3 does not pull the thread). When the feeding device moves towards area b, before the needle 6 drops, the end of the thread guide lever 3 moves from the lower front to the lower rear of the needle hole 81, thereby actuating the bobbin thread between the rotary hook 2 and the needle plate 8, causing the bobbin thread to cross the axis of the needle 6, thus changing the position of the bobbin thread relative to the needle 6 and converting the reverse stitch into a forward stitch. When the feeding device moves in a region other than area a and not in area b, although the thread guide lever 3 still performs the thread-pulling action, the bobbin thread is already behind the axis of the needle 6. Therefore, the backward movement of the thread guide lever 3 will not cause the bobbin thread to cross the axis of the needle 6, and thus the stitch will not change. The sewing process will still form a positive stitch. In this design, the trigger area accounts for a large proportion, so that during the sewing process, the thread guide lever 3 only needs to maintain the normal thread-pulling state most of the time. It only switches to the paused thread-pulling state when the feeding device enters area a, which has a relatively small angle range. This design greatly reduces the number of state switching times of the thread guide lever 3, avoiding the problem of increased mechanical error caused by frequent state switching, thereby making the sewing process more stable, the stitches more uniform, and thus improving the sewing quality.

[0079] Specifically, during the sewing process, if the feeding device moves towards the trigger area, there are two possibilities:

[0080] One scenario is that the movement direction is towards the clockwise rotation area of ​​the needle bar. In this case, such as... Figure 4 As shown, due to the needle bar rotation structure, the needle bar 7 is adjusted to the preset target angle value 1. The center line C of the needle hole 62 on the needle 6 passes through the needle bar reversal area, thus preventing the feeding device from moving forward along the center line C of the needle hole 62. This avoids the problem that the top thread sometimes goes around the left side of the needle 6 and sometimes around the right side during the sewing process. At this time, as long as the thread guide lever 3 is controlled to guide the thread normally, it can be ensured that the sewing process is all positive stitches.

[0081] The second scenario is when the direction of movement is not towards the clockwise rotation area of ​​the needle bar. In this case, regardless of whether the needle bar 7 is at target angle value one or target angle value two, the feeding device will not move forward along the center line C of the needle hole 62 of the needle 6. At this time, it is only necessary to keep the needle bar 7 at its current angle position and control the thread-pulling lever 3 to pull the thread normally to ensure that the sewing process is all positive stitches.

[0082] If the feeding device does not move towards the trigger area, there are two possibilities:

[0083] One scenario is that the movement direction is towards the area where the needle bar reverses direction; in this case, such as... Figure 5 As shown, due to the needle bar rotation structure, the needle bar 7 is adjusted to the preset target angle value 2, and the center line C of the needle hole 62 on the needle 6 passes through the clockwise rotation area of ​​the needle bar. Therefore, the feeding device is prevented from moving forward along the center line C of the needle hole 62 of the needle 6. At this time, the sewing process does not require the thread guide lever 3 to change the position of the bobbin thread relative to the needle 6, and a positive stitch can still be formed. Therefore, as long as the thread guide lever 3 is controlled to pause thread feeding, it can be ensured that the sewing process is always a positive stitch.

[0084] The second scenario is when the direction of movement is not towards the reverse area of ​​the needle bar. In this case, regardless of whether the needle bar 7 is at target angle value one or target angle value two, the feeding device will not move forward along the center line C of the needle hole 62 of the needle 6. At this time, it is only necessary to control the thread-pulling lever 3 to pause thread pulling to ensure that the sewing process is all positive stitches.

[0085] Example 2

[0086] This embodiment is basically the same as the first embodiment in terms of structure and principle. The difference is that when the needle bar 7 is located at the first preset target angle, the orientation of the needle groove 61 on the needle 6 is deflected 6 degrees clockwise relative to the critical surface A from the top view angle. When the needle bar 7 is located at the second preset target angle, the orientation of the needle groove 61 on the needle 6 is deflected 6 degrees counterclockwise relative to the critical surface A from the top view angle.

[0087] Example 3

[0088] This embodiment is basically the same as the first embodiment in structure and principle, except that: when the needle bar 7 is at the first preset target angle, the orientation of the needle groove 61 on the needle 6 is deflected 12 degrees clockwise relative to the critical surface A from a top-down angle; when the needle bar 7 is at the second preset target angle, the orientation of the needle groove 61 on the needle 6 is deflected 12 degrees counterclockwise relative to the critical surface A from a top-down angle. The deflection angle of the needle 6 is controlled within 12 degrees, avoiding the situation where the tip 22 of the rotary hook 2 cannot enter the needle groove 61 of the needle 6 to hook the thread due to excessive deflection of the needle 6. This ensures that the rotary hook 2 can accurately and stably hook the top thread on the needle 6 and expand the thread loop, so that it can stably interweave with the bottom thread, thereby avoiding the occurrence of hooking failure, failure to form a stitch, and skipped stitches.

[0089] Example 4

[0090] This embodiment is basically the same as the first embodiment in terms of structure and principle. The difference is that in step S4-3, the controller controls the wire-picking lever 3 to stop the wire-picking action. Specifically, the controller controls the piston rod of the cylinder to extend, which drives the wire-picking seat 5 to move horizontally, so that the wire-picking lever 3 moves away from the rotary hook 2.

[0091] Example 5

[0092] This embodiment is basically the same as embodiment one in structure and principle, except that: Figure 8 As shown, the triggering region is the area to the right of the critical surface A.

[0093] Example 6

[0094] This embodiment is basically the same as embodiment one in structure and principle, except that: Figure 9 As shown, the triggering area is area b.

[0095] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0096] Although this document frequently uses terms such as 1. base; 2. rotary hook; 21. thread outlet; 22. hook tip; 3. thread guide lever; 4. drive source; 5. thread guide base; 6. needle; 61. needle groove; 62. needle hole; 7. needle bar; 8. needle plate; 81. needle drop hole, etc., the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A sewing method for a sewing machine, the sewing machine comprising a rotary hook (2), a thread guide (3), a needle bar (7) with a needle (6) connected at its lower end, a needle plate (8) having a needle drop hole (81), and a feeding device for fixing the fabric and moving the fabric, wherein the rotary hook (2) has a thread outlet (21) through which the bobbin thread passes, the vertical plane in which the axis of the rotary hook (2) is located is a critical plane A, the line connecting the thread outlet (21) and the needle drop hole (81) is inclined and the vertical plane in which the line is located is a critical plane B, the area between the left side of the critical plane A and the front side of the critical plane B is a region a, the area between the right side of the critical plane A and the front side of the critical plane B is a region b, the sewing machine further comprising a needle bar rotation structure for driving the needle bar (7) to reciprocate around its axis, characterized in that, This sewing method includes the following steps: S1. Divide the moving plane of the feeding device into a trigger area, a needle bar reverse rotation area, and a needle bar forward rotation area: The triggering region is the region other than region a, but includes at least region b; The needle bar reversal area is the area within region a swept by the critical surface A, which is rotated 16-25 degrees clockwise around the needle hole (81) from a top-view angle, and is smaller than region a; The clockwise rotation region of the needle bar is located within the triggering region, and it is the symmetrical region of the counterclockwise rotation region of the needle bar with respect to the critical surface A. S2. The controller generates the needle point trajectory and the motion trajectory of the feeding device according to the sewing pattern; S3. The sewing machine starts working and sews the first stitch; S4. The feeding device moves the fabric to the next stitch position according to the motion trajectory. If the feeding device moves towards the trigger area, the following actions are performed: S4-1. The controller controls the wire-pulling lever (3) to perform the wire-pulling action, so that the end of the wire-pulling lever (3) moves from the lower front to the lower rear of the needle hole (81). The controller adjusts the angle position of the needle bar (7) according to whether the moving direction of the feeding device is towards the needle bar clockwise rotation area. If so, the needle bar (7) is adjusted to the preset target angle value one by the needle bar rotation structure, so that the center line C of the needle hole (62) on the needle (6) passes through the needle bar counterclockwise rotation area. If not, the needle bar rotation structure does not move, and the needle bar (7) maintains the current angle position. S4-2, The needle bar (7) drives the needle (6) to move down and does not adjust the angle of the needle bar during the downward movement, bringing the top thread to the bottom of the needle plate (8), and the rotary hook (2) interweaves the top thread and the bottom thread to form a stitch; If the feeding device does not move towards the trigger area, the following actions are performed: S4-3, The controller controls the wire-pulling lever (3) to pause the wire-pulling action, and adjusts the angle position of the needle bar (7) according to whether the moving direction of the feeding device is toward the needle bar reversal area. If so, the needle bar (7) is adjusted to the preset target angle value two through the needle bar rotation structure, so that the center line C of the needle hole (62) on the needle (6) passes through the needle bar clockwise area. If not, the needle bar rotation structure does not move, and the needle bar (7) maintains the current angle position. S4-4, The needle bar (7) drives the needle (6) to move down and does not adjust the angle of the needle bar during the downward movement, bringing the top thread to the bottom of the needle plate (8), and the rotary hook (2) interweaves the top thread and the bottom thread to form a stitch; S5. Repeat step S4 and continue sewing according to the needle point trajectory obtained from the sewing pattern.

2. The sewing method of the sewing machine according to claim 1, characterized in that, The sewing machine also includes a base (1), a drive source (4), and a thread guide seat (5) movably mounted on the base (1). The thread guide rod (3) is mounted on the thread guide seat (5). In step S4-3, the controller controls the thread guide rod (3) to pause the thread guiding action specifically by controlling the drive source (4) to rotate or move the thread guide seat (5) horizontally, so that the thread guide rod (3) moves away from the rotary hook (2).

3. The sewing method of the sewing machine according to claim 1, characterized in that, In step S4-1, adjusting the needle bar (7) to the preset target angle value one by the needle bar rotation structure is specifically as follows: if the needle bar (7) is already at the target angle value one, the needle bar rotation structure does not move; if the needle bar (7) is not at the target angle value one, the needle bar rotation structure drives the needle bar (7) to rotate to the target angle value one.

4. The sewing method of the sewing machine according to claim 3, characterized in that, In step S4-3, adjusting the needle bar (7) to the preset target angle value two through the needle bar rotation structure is specifically as follows: if the needle bar (7) is already at the target angle value two, the needle bar rotation structure does not move; if the needle bar (7) is not at the target angle value two, the needle bar rotation structure drives the needle bar (7) to rotate to the target angle value two.

5. The sewing method of the sewing machine according to claim 4, characterized in that, The rear side of the needle (6) has a needle groove (61) through which the tip (22) of the rotary hook (2) passes to hook the thread. In step S4-1, when the needle bar (7) is located at a preset target angle value one, the orientation of the needle groove (61) on the needle (6) is deflected clockwise by 6-12 degrees relative to the critical surface A in the top view angle. In step S4-3, when the needle bar (7) is located at a preset target angle value two, the orientation of the needle groove (61) on the needle (6) is deflected counterclockwise by 6-12 degrees relative to the critical surface A in the top view angle.

6. The sewing method of the sewing machine according to any one of claims 1 to 5, characterized in that, The triggering region is all regions other than region a.

7. The sewing method of the sewing machine according to any one of claims 1 to 5, characterized in that, The triggering region is region b, or the region to the right of the critical surface A.

8. The sewing method of the sewing machine according to any one of claims 1 to 5, characterized in that, In step S4-1, while the needle bar rotating structure drives the needle bar (7) to rotate to the target angle value, the feeding device drives the sewing material to move to the next stitching position.

9. The sewing method of the sewing machine according to any one of claims 1 to 5, characterized in that, In step S4-3, while the needle bar rotating structure drives the needle bar (7) to rotate to the target angle value two, the feeding device drives the sewing material to move to the next stitching position.

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