Sewing method of sewing machine

Abstract

The invention provides a sewing method of a sewing machine, and belongs to the technical field of sewing equipment. The problem that the sewing quality is affected due to the fact that reverse stitches appear in the sewing process of an existing sewing machine is solved. The sewing method comprises the following steps: S1, dividing a trigger area, a needle bar reverse rotation area and a needle bar forward rotation area on a moving plane of a feeding device; s2, the controller generates a needle point track and a motion track of a feeding device according to the sewing pattern; s3, the sewing machine starts to work and sews a first needle; s4, the feeding device drives the sewing material to move to a next-needle sewing position according to the motion trail; and S5, repeating the step S4, and performing subsequent sewing according to the needle point track obtained by sewing the pattern. The sewing machine has the advantages of being high in sewing efficiency and good in sewing quality.

Description

Technical Field

[0001] The invention belongs to the technical field of sewing equipment and relates to a sewing method of a sewing machine. Background Art

[0002] A sewing machine uses one or more threads to create seams on the material, joining two or more layers of fabric together. When sewing patterns on a traditional sewing machine, the material moves horizontally in different directions along the feed mechanism, resulting in some forward seams (301 seams) and some reverse seams (319 seams). While forward seams generally ensure aesthetic and consistent seam quality, they are used exclusively in applications requiring high-quality sewing, such as high-end clothing and leather goods. Therefore, to maintain product aesthetics, it is important to avoid reverse seams.

[0003] In order to solve this technical problem, the applicant previously used a thread shifting rod to shift the bottom line between the rotary shuttle and the needle plate to switch the stitches, thereby avoiding the occurrence of reverse stitches during sewing. For example, a sewing machine and a sewing method thereof disclosed in the patent document (application number: 202510475452.3) include a base, a needle plate, a bottom shuttle, a transmission rod and a thread shifting rod. The transmission rod is located on the side of the bottom shuttle and is movably connected to the base. The end of the transmission rod close to the bottom shuttle is fixedly connected to one end of the thread shifting rod, and the other end of the transmission rod is connected to a thread shifting drive member. Under the drive of the thread shifting drive member, the transmission rod can move back and forth in the axial direction and swing at the same time, so that the other end of the thread shifting rod can perform circumferential circulation motion and can be located between the needle drop hole and the bottom shuttle. In this sewing machine, the plane where the axis of the bottom shuttle and the sewing machine needle share a common position is called critical plane A. The line connecting the bottom shuttle's thread outlet and the needle drop hole is arranged at an angle, and the vertical plane on which this line lies is called critical plane B. The area between the side of critical plane A facing away from the thread outlet and the side of critical plane B facing away from the shuttle tip is the reverse stitch area. When the feeding direction is toward the reverse stitch area, the thread shifting action is performed by the thread shifting lever, thereby converting the reverse stitch into the forward stitch. This improves the sewing aesthetics and sewing quality, but still has the following shortcomings:

[0004] like Figure 10As shown, in this sewing machine, the needle bar can only move up and down but cannot adjust its circumferential angle. Therefore, the needle groove on the needle bar always faces the rear of the sewing machine, and the centerline of the needle hole coincides with critical plane A. During the actual sewing process, when the feed mechanism moves forward along the centerline of the needle hole (i.e., critical plane A), the position of the upper thread relative to the needle is uncertain due to factors such as upper thread drift, needle bar motion errors, and equipment vibration. In other words, the upper thread sometimes passes around the left side of the needle and sometimes around the right side. This change in the position of the upper thread relative to the needle directly affects the type of stitch. To ensure that all forward stitches are formed when the feed mechanism moves forward along the centerline of the needle hole (i.e., critical plane A), the thread shifting lever must be controlled to selectively shift the thread. However, since the position of the upper thread relative to the needle cannot be determined, the controller cannot determine whether the thread shifting lever needs to shift the thread. As a result, some reverse stitches may still appear on the sewing material, affecting the sewing quality and aesthetics. Summary of the Invention

[0005] The purpose of the present invention is to address the above-mentioned problems in the existing technology and propose a sewing method for a sewing machine. The present invention solves the problem that reverse stitches will appear in the existing sewing machine during the sewing process, resulting in affected sewing quality, while at the same time enabling the sewing machine to have higher sewing efficiency.

[0006] The object of the present invention can be achieved through the following technical solutions: A sewing method of a sewing machine, the sewing machine includes a rotary hook, a thread shifting rod, a needle bar with a needle connected to the lower end, a needle plate with a needle drop hole and a feeding device for fixing the sewing material and driving the sewing material to move, the rotary hook has a thread outlet for the bottom thread to pass through, the vertical plane on which the axis of the rotary hook is located is the critical plane A, the line connecting the thread outlet and the needle drop hole is inclined and the vertical plane on which 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 area a, and the area between the right side of the critical plane A and the front side of the critical plane B is area b, the sewing machine also includes a needle bar rotating structure for driving the needle bar to rotate back and forth around its axis, and is characterized in that the sewing method includes 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 trigger area is an area outside area a and includes at least area b;

[0009] The needle bar reversal area is the area within area a that is swept by the critical surface A when deflected clockwise around the needle drop hole by a preset angle when viewed from above, and is smaller than area a.

[0010] The needle bar forward rotation area is located in the trigger area, which is a symmetrical area of ​​the needle bar reverse rotation area relative 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 drives the sewing material to the next stitch position according to the motion trajectory. If the feeding device moves to the trigger area, the following actions are performed:

[0014] S4-1. The controller controls the thread-moving rod to perform the thread-moving action, so that the end of the thread-moving rod moves from the front lower part to the rear lower part of the needle drop hole, and the controller adjusts the angular position of the needle bar according to whether the moving direction of the feeding device is toward the needle bar forward rotation area. If so, the needle bar is adjusted to a preset target angle value of one through the needle bar rotation structure, so that the center line C of the needle hole on the needle passes through the needle bar reverse rotation area; if not, the needle bar rotation structure does not move, and the needle bar maintains the current angular position;

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

[0016] If the feeding device does not move toward the trigger area, perform the following actions:

[0017] S4-3, the controller controls the thread-drilling lever to pause the thread-drilling action, and adjusts the angular position of the needle bar according to whether the moving direction is toward the needle bar reversal area. If so, the needle bar rotation mechanism adjusts the needle bar to the preset target angle value 2 so that the center line C of the needle hole on the needle passes through the needle bar forward rotation area. If not, the needle bar rotation mechanism does not move, and the needle bar maintains the current angular position.

[0018] S4-4, the needle bar drives the needle downward, bringing the upper thread to the bottom of the needle plate, and the rotary hook interweaves the upper thread and the lower thread to form a stitch;

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

[0020] This sewing method has made the following improvements on the basis of the existing technology:

[0021] Regarding the control logic of the thread lever, whether the thread lever performs the thread diversion action depends on whether the feeder moves toward the trigger area. When the feeder moves toward the trigger area, the thread lever performs the thread diversion action; otherwise, the thread lever pauses the thread diversion action. Furthermore, area b is the reverse stitch area where thread diversion is required (i.e., the area where direct sewing would result in reverse stitching if the thread lever does not divert the thread). Since the trigger area includes at least area b, the thread lever ensures that the thread diversion action is performed whenever the feeder moves toward the trigger area, thereby converting the reverse stitching into the forward stitching.

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

[0023] One scenario is when the movement direction is toward the needle bar forward rotation area. At this time, due to the needle bar rotation structure, the needle bar is adjusted to the preset target angle value of 1. The center line C of the needle hole passes through the needle bar reverse rotation area, thus eliminating the situation where the feed device moves forward along the center line C of the needle hole, thereby avoiding the problem of the upper thread sometimes bypassing the left side of the needle and sometimes bypassing the right side of the needle during sewing. In this case, as long as the thread guide lever is controlled to guide the thread normally, the sewing process can be guaranteed to be a forward stitch.

[0024] The second situation is that the moving direction is not towards the forward rotation area of ​​the needle bar. At this time, no matter whether the needle bar is at the target angle value one or the target angle value two, the feeding device will not move forward along the center line C of the needle hole. At this time, you only need to keep the needle bar at the current angle position and control the thread shifting lever to perform normal thread shifting to ensure that the sewing process is all forward stitches.

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

[0026] In one case, the movement direction is toward the needle bar reversal area. In this case, the needle bar rotation mechanism adjusts the needle bar to the preset target angle value 2, and the centerline C of the needle hole passes through the needle bar forward rotation area, thus preventing the feed device from moving forward along the centerline C of the needle hole. In this case, the sewing process does not require the thread guide lever to change the position of the bottom thread relative to the needle, and a positive stitch can be formed. Therefore, simply controlling the thread guide lever to pause the thread guide can ensure that the sewing process always produces a positive stitch.

[0027] The second situation is that the moving direction is not toward the needle bar reversal area. At this time, no matter whether the needle bar is at the target angle value one or the target angle value two, the feeding device will not move forward along the center line C of the needle hole. At this time, you only need to control the thread shifting lever to pause the thread shifting to ensure that the sewing process is all forward stitches.

[0028] In summary, this sewing method can avoid the appearance of reverse stitches during the sewing process by coordinating the rotation of the needle bar with the thread-moving action of the thread-moving lever, thereby improving the sewing quality. At the same time, by dividing the moving plane of the feeding device into a needle bar reverse rotation area and a needle bar forward rotation area, both of which are smaller than area a, the needle bar rotation structure will only drive the needle bar to rotate when the moving direction of the feeding device is within these two areas. This design means that during the sewing process, the needle bar rotation structure does not need to move in most cases, and only needs to keep the needle bar at the current angle position for needle insertion. Therefore, the stability of the needle bar is greatly improved, so that the needle insertion position is accurate and the sewing quality is improved.

[0029] In addition, when the needle bar is adjusted to the preset target angle value 1, the deflection angle of the needle bar is small, so that the center line C of the needle hole passes through the forward rotation area of ​​the needle bar. The same is true when the needle bar is adjusted to the preset target angle value 2. This design ensures that the needle bar remains at the target angle value 1 or the target angle value 2 during the entire cycle of each needle insertion action, and there is no need to adjust the angle of the needle bar when inserting the needle. This can avoid the situation where the shuttle tip cannot enter the needle groove of the needle to hook the thread due to excessive deflection of the needle, and it can also enable the needle bar to insert the needle quickly, thereby significantly improving sewing efficiency while ensuring sewing quality.

[0030] In the sewing method of the above-mentioned sewing machine, the sewing machine also includes a base, a driving source, and a thread diverter seat movably arranged on the base, and the thread diverter rod is arranged on the thread diverter seat. In the step S4-3, the controller controls the thread diverter rod to suspend the thread diverting action as follows: the controller controls the driving source to drive the thread diverter seat to rotate horizontally or translate horizontally, so that the thread diverter rod is away from the rotary hook.

[0031] During the sewing process of a sewing machine, when it is necessary to trim the thread, such as cutting the needle thread and the tail needle thread and bottom thread, the thread trimming knife needs to move to the position between the needle hole and the rotary shuttle to perform the thread trimming operation. In this thread diverting mechanism, the thread diverting seat is movably arranged on the base, rather than being fixedly connected in a traditional manner. In this way, when the sewing machine needs to trim the thread, it is only necessary to control the driving member to drive the thread diverting seat to rotate or translate horizontally, so that the thread diverting rod set on the thread diverting seat also moves away from the rotary shuttle, avoiding the movement path of the thread trimming knife outside the rotary shuttle, thereby avoiding interference between the thread trimming knife and the thread diverting rod. This method only relies on the driving member to simply rotate the thread diverting seat, which is originally in a stationary state, to ensure that the thread diverting rod reaches the predetermined avoidance position stably and accurately. During this process, the motor that drives the thread diverting rod to move can keep running, so that the thread diverting rod continues to move, thereby reducing the frequent start and stop of the motor, greatly reducing the control difficulty, and effectively avoiding the collision between the thread diverting rod and the thread trimming knife, so that the reliability of the sewing work is significantly improved, and the sewing quality is further improved.

[0032] In the sewing method of the above-mentioned sewing machine, in the step S4-1, the needle bar is adjusted to a preset target angle value one through the needle bar rotating structure. Specifically, if the needle bar is already at the target angle value one, the needle bar rotating structure does not move; if the needle bar is not at the target angle value one, the needle bar rotating structure drives the needle bar to rotate to the target angle value one.

[0033] In the needle bar rotation structure, the driving mode can be selected as cylinder drive or servo motor drive. It is preferably cylinder drive, which drives the needle bar to rotate back and forth through the extension and retraction of the cylinder piston rod to switch between the target angle value one and the target angle value two. As for how the cylinder specifically drives the needle bar to rotate, those skilled in the art can implement it in combination with common knowledge, and this article will not provide a cumbersome description. When the needle bar is already at the target angle value one, the needle bar rotation structure remains stationary, avoiding unnecessary movement; and when the needle bar is not at the target angle value one, the needle bar rotation structure adjusts it into place. This design can simplify the control difficulty and reduce the operating frequency of the cylinder or servo motor, thereby improving its working reliability and service life, ensuring the accuracy of the needle bar angle during sewing, and ensuring that the sewn stitches are all positive stitches, effectively improving the sewing quality.

[0034] In the sewing method of the above-mentioned sewing machine, in the step S4-3, the needle bar is adjusted to the preset target angle value two through the needle bar rotating structure. Specifically: if the needle bar is already at the target angle value two, the needle bar rotating structure does not move; if the needle bar is not at the target angle value two, the needle bar rotating structure drives the needle bar to rotate to the target angle value two.

[0035] In this design, the needle bar rotation mechanism remains stationary when the needle bar is at target angle value 2; it adjusts the needle bar into position only when it is not. Similarly, this design can further simplify control and reduce the operating frequency of the cylinder or servo motor, thereby improving its reliability and service life, ensuring the accuracy of the needle bar angle during sewing and ensuring that all sewn stitches are in the correct direction.

[0036] In the sewing method of the sewing machine described above, the rear side surface of the needle has a needle groove for the shuttle tip to pass through for thread hooking. In step S4-1, when the needle bar is at a preset target angle value of one, the direction of the needle groove on the needle is deflected 6-12 degrees clockwise relative to the critical surface A when viewed from above. In step S4-3, when the needle bar is at a preset target angle value of two, the direction of the needle groove on the needle is deflected 6-12 degrees counterclockwise relative to the critical surface A when viewed from above. The deflection angle of the needle is controlled within 12 degrees, which avoids the situation where the shuttle tip cannot enter the needle groove of the needle to hook the thread due to excessive needle deflection, thereby ensuring that the shuttle can accurately and stably hook the upper thread on the needle and expand the thread loop so that it is stably interwoven with the lower thread, avoiding thread hooking failure, the inability to form stitches, and the occurrence of skipped stitches, thereby significantly improving the sewing quality and ensuring the uniformity and stability of the sewing stitches.

[0037] In the sewing method of the above-mentioned sewing machine, the trigger area is all areas outside area a. In this design, the trigger area accounts for a large proportion, so that during the sewing process, the thread lever only needs to maintain the normal thread-drilling state most of the time, and only switches to the paused thread-drilling state when the feeding device enters area a with a relatively small angle range. This design greatly reduces the number of state switches of the thread lever, avoiding the problem of increased mechanical errors caused by frequent state switching, thereby making the sewing process more stable and the stitches more uniform, thereby improving the sewing quality.

[0038] In the sewing method for the sewing machine described above, the trigger area is area b, or the area to the right of critical surface A. The trigger area is area b, ensuring that when the feed device moves toward area b, the thread shifting lever shifts the thread, thereby converting the reverse stitch into the forward stitch. The trigger area is the area to the right of critical surface A, which also includes area b. This ensures that when the feed device moves toward area b, the thread shifting lever shifts the thread, thereby converting the reverse stitch into the forward stitch.

[0039] In the aforementioned sewing method for a sewing machine, in step S4-1, the needle bar rotation mechanism simultaneously rotates the needle bar to a target angle of 1, while the feeder moves the sewing material to the next stitch position. This design synchronizes the needle bar angle adjustment step with the feeder's movement, improving sewing efficiency.

[0040] In the aforementioned sewing method for a sewing machine, in step S4-3, while the needle bar rotation mechanism drives the needle bar to rotate to the target angle value 2, the feeder device simultaneously drives the sewing material to the next stitching position. In this design, the step of rotating the needle bar to adjust the needle bar angle is synchronized with the movement of the feeder device, which can improve sewing efficiency.

[0041] In the sewing method of the above-mentioned sewing machine, the needle bar reversal area is the area within area a swept by the critical surface A deflected 16-25 degrees clockwise around the needle hole when viewed from above. This design can ensure that when the feeding device moves forward near the critical surface A, the center line C of the needle hole can be rotated by the needle bar so that it does not coincide with the critical surface A, thereby preventing the feeding device from moving forward along the center line C of the needle hole and avoiding the appearance of reverse stitches. At the same time, this design also reduces the proportion of the needle bar reversal area and the symmetrical needle bar forward rotation area, so that the needle bar rotation structure does not need to move in most cases, greatly improving the stability of the needle bar and thus improving the sewing quality.

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

[0043] 1. This sewing method can avoid the occurrence of reverse stitches during the sewing process by coordinating the thread-moving action of the thread-moving lever with the rotation of the needle bar, 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. Therefore, the stability of the needle bar is greatly improved, so that the needle position is accurate, thereby improving the sewing quality.

[0045] 3. In this sewing method, the needle bar remains at target angle value 1 or target angle value 2 during the entire cycle of each needle insertion action, reducing unnecessary angle adjustment actions. This can avoid the situation where the shuttle tip cannot enter the needle groove of the needle to hook the thread due to excessive needle deflection, and at the same time, it can enable the needle bar to insert the needle quickly, thereby significantly improving sewing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0047] Figure 2 It is a top view of the hook.

[0048] Figure 3 It is a flow chart of this sewing method.

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

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

[0051] Figure 6 It is a structural diagram of the driving source, the wire-dipping seat and the wire-dipping rod.

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

[0053] Figure 8 This is a schematic diagram of the needle bar at the preset target angle value one in the fifth embodiment.

[0054] Figure 9 This is a schematic diagram of the needle bar in Example 6 when it is at a preset target angle value one.

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

[0056] In the figure, 1. base; 2. rotary hook; 21. thread outlet; 22. hook tip; 3. thread shifting rod; 4. driving source; 5. thread shifting seat; 6. needle; 61. needle groove; 62. needle hole; 7. needle bar; 8. needle plate; 81. needle drop hole. DETAILED DESCRIPTION

[0057] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but 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 seat 5 movably arranged on the base 1, a needle bar rotating structure for driving the needle bar 7 to rotate around its axis, and a feeding device for fixing the sewing material and driving the sewing material to move. The thread guide rod 3 is arranged on the thread guide seat 5. The feeding device is a 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 for the hook tip 22 of the rotary hook 2 to pass through to hook the thread. In the needle bar rotation structure, the driving mode can be selected from cylinder drive or servo motor drive. It is preferably a cylinder drive, which drives the needle bar 7 to rotate back and forth through the extension and contraction of the cylinder piston rod to switch between the target angle value 1 and the target angle value 2. As for how the cylinder drives the needle bar 7 to rotate, those skilled in the art can implement it in combination with common knowledge, and this article will not provide a cumbersome description.

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

[0061] like Figure 3 As shown, this sewing method comprises 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 trigger area is the area outside area a and includes at least area b. Figure 4 As shown, the trigger area is all areas except area a.

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

[0065] The needle bar forward rotation area is located in the trigger area, which is the symmetrical area of ​​the needle bar reverse rotation area relative 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 drives the sewing material to the next stitch position according to the motion trajectory. If the feeding device moves to the trigger area, the following actions are performed:

[0069] S4-1, the controller controls the thread-drilling rod 3 to perform the thread-drilling action, so that the end of the thread-drilling rod 3 moves from the front lower part to the rear lower part of the needle drop hole 81, and the controller adjusts the angle position of the needle bar 7 according to whether the moving direction of the feeding device is toward the needle bar forward rotation area. If so, then Figure 4 As shown, the needle bar 7 is adjusted to the preset target angle value 1 by the needle bar rotating mechanism. At this time, the direction of the needle groove 61 on the needle 6 is deflected 8 degrees clockwise relative to the critical surface A when viewed from above, and the center line C of the needle hole 62 on the needle 6 passes through the needle bar reversal area; if not, the needle bar rotating mechanism does not operate, and the needle bar 7 maintains the current angle position;

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

[0071] If the feeding device does not move toward the trigger area, perform the following actions:

[0072] S4-3, the controller controls the thread-drilling rod 3 to suspend the thread-drilling 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, Figure 5 As shown, the needle bar 7 is adjusted to the preset target angle value 2 by the needle bar rotating structure. At this time, the direction of the needle groove 61 on the needle 6 is deflected 8 degrees counterclockwise relative to the critical surface A when viewed from above, and the center line C of the needle hole 62 on the needle 6 passes through the needle bar forward rotation area. If not, the needle bar rotating 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 downward, bringing the upper thread to the bottom of the needle plate 8, and the rotary hook 2 interweaves the upper thread and the lower thread to form a stitch;

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

[0075] Among them, such as Figure 6 As shown, the driving source 4 is a cylinder, and the piston rod of the cylinder is connected to the wire-drying seat 5. In step S4-3, the controller controls the wire-drying rod 3 to pause the wire-drying action as follows: Figure 1 As shown, the controller controls the piston rod of the air cylinder to extend, driving the thread-drilling seat 5 to rotate horizontally, so that the front end of the thread-drilling rod 3 swings forward and away from the rotary hook 2. After moving away from the rotary hook 2, even if the thread-drilling rod 3 is still in motion, it will not contact the bottom line between the needle plate 8 and the rotary hook 2.

[0076] Furthermore, in step S4-1, the needle bar 7 is adjusted to the preset target angle value one by the needle bar rotating structure as follows: if the needle bar 7 is already at the target angle value one, the needle bar rotating structure does not move; if the needle bar 7 is not at the target angle value one, the needle bar rotating structure drives the needle bar 7 to rotate to the target angle value one. In step S4-3, the needle bar 7 is adjusted to the preset target angle value two by the needle bar rotating structure as follows: if the needle bar 7 is already at the target angle value two, the needle bar rotating structure does not move; if the needle bar 7 is not at the target angle value two, the needle bar rotating structure drives the needle bar 7 to rotate to the target angle value two. In step S4-1, while the needle bar rotating structure drives the needle bar 7 to rotate to the target angle value one, the feeding device drives the sewing material to move to the next stitch sewing position. 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 stitch sewing position. In this design, the step of rotating the needle bar 7 to adjust the angle of the needle bar 7 is synchronized with the movement of the feeding device, which can improve sewing efficiency.

[0077] The following is a brief introduction to the principle of avoiding reverse stitching in this sewing method:

[0078] In this sewing machine, for the control logic of the thread shifting lever 3, whether the thread shifting lever 3 performs the thread shifting action depends on whether the feeding device moves toward the trigger area. When the feeding device moves toward the trigger area, the thread shifting lever 3 performs the thread shifting action, otherwise, the thread shifting lever 3 pauses thread shifting. In this embodiment, the trigger area is all areas other than area a, which includes area b. Area b is the reverse stitch area where the thread needs to be shifted (that is, if the thread shifting lever 3 does not shift the thread, direct sewing will form a reverse stitch area). When the feeding device moves toward area b, before the needle 6 is lowered, the end of the thread shifting lever 3 moves from the front and bottom of the needle hole 81 to the back and bottom, thereby shifting the bottom line between the rotary hook 2 and the needle plate 8, so that the bottom line crosses the axis of the needle 6, thereby changing the position of the bottom line relative to the needle 6, and converting the reverse stitch into a forward stitch. When the moving direction of the feeding device is outside area a and not in area b, although the thread shifting lever 3 is still performing the thread shifting action, since the bottom line itself is already on the rear side of the axis of the needle 6, the backward movement of the thread shifting lever 3 will not cause the bottom line to cross the axis of the needle 6, so the stitches will not be switched, and the final sewing process will still form a forward stitch. The trigger area accounts for a large proportion in this design, so that during the sewing process, the thread shifting lever 3 only needs to maintain a normal thread shifting state most of the time, and only switches to a paused thread shifting state when the feeding device enters area a with a relatively small angle range. This design greatly reduces the number of state switching times of the thread shifting lever 3, avoids the problem of increased mechanical errors due to frequent state switching, thereby making the sewing process more stable and the stitches more uniform, thereby improving the sewing quality.

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

[0080] One case is that the moving direction is toward the needle bar forward rotation area. Figure 4 As shown, due to the needle bar rotation structure, the needle bar 7 is adjusted to the preset target angle value 1, and the center line C of the needle hole 62 on the needle 6 passes through the needle bar reversal area. This prevents the feed device from moving forward along the center line C of the needle hole 62 of the needle 6, thereby avoiding the problem of the upper thread sometimes passing around the left side of the needle 6 and sometimes passing around the right side of the needle 6 during sewing. At this time, as long as the thread shifting lever 3 is controlled to shift the thread normally, it can be guaranteed that the sewing process is always in the forward direction.

[0081] The second situation is that the moving direction is not towards the forward rotation area of ​​the needle bar. At this time, no matter whether the needle bar 7 is located at the target angle value one or the 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 the current angle position and control the thread shifting rod 3 to perform normal thread shifting to ensure that the sewing process is all forward stitches.

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

[0083] One situation is that the moving direction is toward the needle bar reversal area. 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 needle bar forward rotation area, thus preventing the feed device 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 shifting lever 3 to change the position of the bottom line relative to the needle 6, and a positive stitch can be formed. Therefore, as long as the thread shifting lever 3 is controlled to pause the thread shifting, the sewing process can ensure that the positive stitch is formed.

[0084] The second situation is that the moving direction is not toward the needle bar reversal area. At this time, no matter whether the needle bar 7 is located at the target angle value one or the 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, you only need to control the thread shifting rod 3 to pause the thread shifting to ensure that the sewing process is all forward stitches.

[0085] Example 2

[0086] The structure and principle of this embodiment are basically the same as those of the first embodiment, except that: when the needle bar 7 is located at the preset target angle value one, the direction of the needle groove 61 on the needle 6 is deflected 6 degrees clockwise relative to the critical surface A at a top-down angle; when the needle bar 7 is located at the preset target angle value two, the direction of the needle groove 61 on the needle 6 is deflected 6 degrees counterclockwise relative to the critical surface A at a top-down angle.

[0087] Example 3

[0088] The structure and principle of this embodiment are basically the same as those of the first embodiment, except that: when the needle bar 7 is at the preset target angle value one, the direction of the needle groove 61 on the needle 6 is deflected 12 degrees clockwise relative to the critical surface A when viewed from above; when the needle bar 7 is at the preset target angle value two, the direction of the needle groove 61 on the needle 6 is deflected 12 degrees counterclockwise relative to the critical surface A when viewed from above. The deflection angle of the needle 6 is controlled within 12 degrees, which prevents the shuttle tip 22 of the rotary hook 2 from being unable to enter the needle groove 61 of the needle 6 to hook the thread due to excessive deflection of the needle 6, thereby ensuring that the rotary hook 2 can accurately and stably hook the surface thread on the needle 6 and expand the thread loop so that it is stably interwoven with the bottom thread, thereby avoiding thread hooking failure, the inability to form a stitch, and the occurrence of stitch skipping.

[0089] Example 4

[0090] The structure and principle of this embodiment are basically the same as those of the first embodiment, except that: in step S4-3, the controller controls the thread-driving rod 3 to suspend the thread-driving action. Specifically, the controller controls the piston rod of the cylinder to extend, driving the thread-driving seat 5 to move horizontally, so that the thread-driving rod 3 is away from the rotary hook 2.

[0091] Example 5

[0092] The structure and principle of this embodiment are basically the same as those of the first embodiment, except that: Figure 8 As shown, the trigger area is the area to the right of the critical surface A.

[0093] Example 6

[0094] The structure and principle of this embodiment are basically the same as those of the first embodiment, except that: Figure 9 As shown, the trigger area is area b.

[0095] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of 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. driving source; 5. thread guide seat; 6. needle; 61. needle groove; 62. needle hole; 7. needle bar; 8. needle plate; 81. needle drop hole, the use of other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitations is contrary to the spirit of the present invention.

Claims

1. A sewing method for a sewing machine, the sewing machine comprising a rotary hook (2), a thread shifting rod (3), a needle bar (7) having a needle (6) connected to its lower end, a needle plate (8) having a needle drop hole (81), and a feeding device for fixing the sewing material and driving the sewing material to move, the rotary hook (2) having a thread outlet (21) for the bottom thread to pass through, the vertical plane on 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 on 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 area a, and the area between the right side of the critical plane A and the front side of the critical plane B is area b, the sewing machine further comprises a needle bar rotating structure for driving the needle bar (7) to rotate back and forth around its axis, characterized in that This sewing method comprises 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 trigger area is an area outside area a and includes at least area b; The needle bar reversal area is an area within area a that is swept by the critical surface A around the needle hole (81) in a clockwise deflection at a preset angle when viewed from above, and is smaller than area a; The needle bar forward rotation area is located in the trigger area, which is a symmetrical area of ​​the needle bar reverse rotation area relative 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 drives the sewing material to the next stitch position according to the motion trajectory. If the feeding device moves to the trigger area, the following actions are performed: S4-1, the controller controls the thread-moving rod (3) to perform the thread-moving action, so that the end of the thread-moving rod (3) moves from the front lower part of the needle hole (81) to the rear lower part, and the controller adjusts the angle position of the needle bar (7) according to whether the moving direction of the feeding device is toward the needle bar forward rotation area. If so, the needle bar rotating structure adjusts the needle bar (7) to a preset target angle value of one, so that the center line C of the needle hole (62) on the machine needle (6) passes through the needle bar reverse rotation area; if not, the needle bar rotating 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 downward, bringing the upper thread to the bottom of the needle plate (8), and the rotary shuttle (2) interweaves the upper thread and the lower thread to form a stitch; If the feeding device does not move toward the trigger area, perform the following actions: S4-3, the controller controls the thread-drilling lever (3) to pause the thread-drilling 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 rotating structure adjusts the needle bar (7) to the preset target angle value 2 so that the center line C of the needle hole (62) on the needle (6) passes through the needle bar forward rotation area. If not, the needle bar rotating 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 downward, bringing the upper thread to the bottom of the needle plate (8), and the rotary shuttle (2) interweaves the upper thread and the lower thread to form a stitch; S5. Repeat step S4 and perform subsequent sewing according to the needle point trajectory obtained from the sewing pattern.

2. The sewing method of a sewing machine according to claim 1, characterized in that: The sewing machine further comprises a base (1), a driving source (4), and a thread-diverting seat (5) movably arranged on the base (1); the thread-diverting rod (3) is arranged on the thread-diverting seat (5); and in step S4-3, the controller controls the thread-diverting rod (3) to suspend the thread-diverting action, specifically: the controller controls the driving source (4) to move, driving the thread-diverting seat (5) to rotate horizontally or translate horizontally, so that the thread-diverting rod (3) is away from the rotary hook (2).

3. The sewing method for a sewing machine according to claim 1, wherein: In step S4-1, the needle bar (7) is adjusted to a preset target angle value one by the needle bar rotating structure. Specifically, if the needle bar (7) is already at the target angle value one, the needle bar rotating structure does not operate; if the needle bar (7) is not at the target angle value one, the needle bar rotating structure drives the needle bar (7) to rotate to the target angle value one.

4. The sewing method for a sewing machine according to claim 3, wherein: In step S4-3, the needle bar (7) is adjusted to the preset target angle value 2 by the needle bar rotating structure. Specifically, if the needle bar (7) is already at the target angle value 2, the needle bar rotating structure does not move; if the needle bar (7) is not at the target angle value 2, the needle bar rotating structure drives the needle bar (7) to rotate to the target angle value 2.

5. The sewing method for a sewing machine according to claim 4, characterized in that: The rear side surface of the needle (6) has a needle groove (61) for the shuttle tip (22) of the rotary shuttle (2) to pass through for hooking the thread. In the step S4-1, when the needle bar (7) is located at the preset target angle value of one, the direction of the needle groove (61) on the needle (6) is deflected 6-12 degrees clockwise relative to the critical surface A when viewed from above; in the step S4-3, when the needle bar (7) is located at the preset target angle value of two, the direction of the needle groove (61) on the needle (6) is deflected 6-12 degrees counterclockwise relative to the critical surface A when viewed from above.

6. The sewing method for a sewing machine according to any one of claims 1 to 5, characterized in that: The trigger area is all areas except area a.

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

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

9. The sewing method for a sewing machine according to any one of claims 1 to 5, characterized in that: In step S4-3, the needle bar rotating structure drives the needle bar (7) to rotate to the target angle value 2, while the feeding device drives the sewing material to move to the next needle sewing position.

10. The sewing method for a sewing machine according to any one of claims 1 to 5, characterized in that: In step S1, the needle bar reversal area is the area within area a swept by the critical surface A deflected 16-25 degrees clockwise around the needle hole (81) at a top view angle.

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