Needle thread control device for optimized corner sewing of double-needle sewing machine, and sewing control method

Abstract

The present invention relates to a needle thread control device for optimized corner sewing of a double-needle sewing machine, and a sewing control method. The needle thread control device comprises a middle thread guide hook, a thread take-up lever, two needle thread tensioners and a thread take-up spring mechanism, wherein two thread guide hook central holes are provided in the middle thread guide hook, two thread take-up holes are provided in the thread take-up lever, the thread take-up spring mechanism comprises two guide assemblies and two thread take-up springs, each guide assembly comprises a guide groove and a guide thread hook, each thread take-up spring comprises a thread hooking lever portion, and the thread hooking lever portions can rotate up and down about a rotation axis; and one of the guide assemblies, one of the thread take-up springs, one of the needle thread tensioners, one of the thread guide hook central holes and one of the thread take-up holes form one needle thread control unit, and the other of the guide assemblies, the other of the thread take-up springs, the other of the needle thread tensioners, the other of the thread guide hook central holes and the other of the thread take-up holes form the other needle thread control unit. Each needle thread control unit is configured to control a needle thread of one needle, and the needle thread passes through the needle thread tensioners, the guide grooves, the guide thread hooks, the bottom side of the thread hooking lever portions, the thread take-up holes and the thread guide hook central holes in sequence and then passes through the needle. When the thread take-up lever moves upwards, the needle thread drives the thread hooking lever portions to rotate upwards.

Description

Optimized thread control device and sewing control method for corner sewing on double-needle sewing machines Technical Field

[0001] This invention relates to the field of sewing technology, and more specifically to a top thread control device and sewing control method for optimizing corner sewing on a double-needle sewing machine. Background Technology

[0002] In certain applications of double-needle sewing machines, corner stitching is widely used, especially when sewing collars or pockets. However, when the fabric is thin or the bobbin thread is thin while the top thread is thick, poor corner stitches often occur. Specifically, the bobbin thread is pulled to the surface of the fabric by the top thread, resulting in a long, raised thread. This is not just a simple bobbin thread drop; the bobbin thread is pulled upwards by the top thread, causing a noticeable long raised thread. This problem is particularly prominent in corner stitching because corner stitches are usually visible, meaning the stitches are directly exposed after sewing and are readily visible to the user. Therefore, poor corner stitches significantly impact the appearance of the finished product, directly affecting the sewing quality and aesthetics.

[0003] Therefore, ensuring that corner stitches remain stable and aesthetically pleasing under different combinations of materials and threads is a problem that urgently needs to be solved. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the technical problem to be solved by the present invention is to provide a top thread control device and sewing control method for optimizing corner sewing on a double-needle sewing machine, which can flexibly control the supply and demand of top thread and tension corresponding to the separated needle bar, and ensure stable and beautiful stitches when sewing at corners.

[0005] To achieve the above objectives, the present invention provides a top thread control device for optimizing corner sewing on a double-needle sewing machine. The double-needle sewing machine includes two needle bars, each with a needle at its lower end. The top thread control device includes a center thread hook, a take-up lever, two top thread clamps, and a take-up spring mechanism. The center thread hook has two center holes, the take-up lever has two take-up holes, the top thread clamps can clamp or release the top thread, and the take-up spring mechanism includes a take-up spring and two guide components. The guide components are fixedly installed in the double-needle sewing machine and include guide grooves and guide hooks. There are two take-up springs, each including a hook for contacting the top thread. The hook rod is capable of rotating up and down around its axis of rotation. When the hook rod moves upward, the take-up spring is in an elastic energy storage state and provides a spring force to drive the hook rod to return to its original position. One guide assembly, take-up spring, top thread clamp, thread hook center hole, and take-up hole constitute a top thread control unit. Another guide assembly, take-up spring, top thread clamp, thread hook center hole, and take-up hole constitute another top thread control unit. Each top thread control unit controls the top thread of one needle. The top thread passes through the top thread clamp, guide groove, guide hook, bottom side of the hook rod, take-up hole, and thread hook center hole in the corresponding top thread control unit before passing through the needle. When the take-up rod moves upward, the top thread will drive the hook rod to rotate upward.

[0006] Furthermore, the thread take-up spring mechanism also includes a thread take-up spring adjustment assembly, which is connected to the two thread take-up springs and can adjust and lock the rotation angle of the two thread take-up springs respectively.

[0007] Furthermore, the thread take-up spring adjustment assembly includes a rotatable adjustment short shaft, a short shaft locking structure for locking the adjustment short shaft, an adjustment knob rotatably mounted on the rotatable short shaft, and a knob locking structure for locking the adjustment knob. Both thread take-up springs are rotatably mounted on the adjustment short shaft, with one end of one thread take-up spring connected to the adjustment short shaft and one end of the other thread take-up spring connected to the adjustment knob.

[0008] Furthermore, the thread take-up spring mechanism also includes two thread take-up spring sensors, which are used to measure the rotation angle position of the hook rod of the two thread take-up springs respectively, and the thread take-up spring sensors are used to communicate with the electronic control system of the double-needle sewing machine.

[0009] This invention also provides a sewing control method for optimizing corner sewing on a double-needle sewing machine, using the aforementioned top thread control device. The sewing control method includes the following steps:

[0010] S1. Determine the absolute value of the theoretical thread quantity for each of the two thread control units: Represent the center of the thread hook center hole in the thread control unit as point A, the thread take-up hole as point B, the contact point between the hook rod of the take-up spring and the thread as point C, the contact point between the guide hook of the guide assembly and the thread as point D, the contact point between the guide groove and the thread as point E, and the center of the guide groove as point F. Using the initial position of the take-up spring when it is not under upward tension from the thread as the calculation benchmark, and with point C stationary, record the absolute value of the theoretical thread quantity as L = L AB +L BC +L CD +L DE When the spindle rotates, it will drive the take-up lever to move up and down to different positions. The relationship between the absolute value of the theoretical line quantity L and the spindle angle θ is calculated and denoted as L=f(θ).

[0011] S2. Determine the spindle angle θ1 for the thread release timing and the spindle angle θ2 for the thread release reset timing corresponding to the two thread control units respectively:

[0012] S21. When the line-flying lever actually reaches its highest point, the hook part of the line-flying spring will move upward. Calculate L at this time. AB +L BE The length of the line is taken as the absolute value of the theoretical line quantity L1 when the line is loosened. Then, the principal axis angle at this time is determined according to L=f(θ), and it is recorded as the principal axis angle θ1 when the line is loosened.

[0013] S22. Set the optimized reset position of the thread take-up spring. When the thread take-up spring is in the optimized reset position, the upward rotation angle of the hook rod relative to the initial position is α. Obtain the L value corresponding to the actual operation of the double-needle sewing machine up to the time when the thread take-up spring is in the optimized reset position. AB +L BC +L CD +L DE The length of the line is denoted as the absolute value of the theoretical line quantity at the time of line slack reset, L2. The corresponding spindle angle is determined according to L=f(θ), and denoted as the spindle angle θ2 at the time of line slack reset.

[0014] S3. When sewing at corners, determine which needle bar does not move and record it as the separated needle bar. The top thread control unit corresponding to the top thread on it is recorded as the separated top thread control unit.

[0015] S4. When sewing the second stitch after the fabric has rotated, the separated top thread control unit shall operate as follows:

[0016] S41. When the spindle angle is less than or equal to θ1, control the face wire clamp to release the face wire;

[0017] S42. When the spindle angle is θ2, control the surface wire clamp to reset and clamp the surface wire.

[0018] Furthermore, in step S1, the principal axis angle θ is a discrete array with equal intervals, and the interval angle Δθ is 2° to 7°.

[0019] Furthermore, in step S22, the angle α is 5 to 10°.

[0020] Further, in step S3, the method for determining the separated needle bar includes: the take-up spring mechanism also includes two take-up spring sensors, which are used to measure the rotational position of the hook rod of the two take-up springs respectively, and the take-up spring sensors are communicatively connected to the electronic control system of the double-needle sewing machine; the main shaft angle range θ3~θ4 corresponding to the take-up springs of the two top thread control units when they are separated and not rotating is determined respectively: when the fabric is rotated, the needle is in the lower stop position. During the subsequent movement of the take-up bar to the lowest point position, if the needle bar has separated, there is a main shaft angle range θ3~θ4. Within this range, the hook rod of the take-up spring will not rotate; the movement of the hook rod of the take-up spring is measured in real time by the take-up spring sensor, and the electronic control system is used to determine whether the hook rod rotates when the main shaft is within the angle range θ3~θ4. If it does not rotate, the top thread control unit to which the take-up spring belongs is a separated top thread control unit, and the corresponding needle bar is a separated needle bar.

[0021] Furthermore, in step S3, the method for determining the separated needle bar includes: the separation action of the two needle bars is controlled by a separation positioning wrench, and a separation detection component is provided in the double needle sewing machine for detecting the separation positioning wrench, and the separated needle bar is determined by the separation detection component.

[0022] Furthermore, in step S42, during the process of the spindle rotating to θ2, the thread take-up spring sensor measures whether the thread take-up spring stops resetting to optimize the position.

[0023] As described above, the thread control device and sewing control method of the present invention have the following beneficial effects:

[0024] 1. Improved corner sewing quality: When sewing at corners, the timing and amount of thread feeding of the needle bar and needle corresponding to the separated needle bar can be controlled. This solves the problem of long, loose threads being pulled to the fabric surface when sewing at corners with thin materials and mismatched thread combinations. This greatly improves the aesthetics and stability of the sewn stitches. In addition, the return position of the take-up spring can be controlled to optimize the position, avoiding the problem of thread slippage caused by the take-up spring fully returning to its original position due to insufficient thread tension.

[0025] 2. Intelligent thread supply adjustment: Through electronic thread loosening and sensor detection, the supply and demand of thread for face-to-face sewing is automatically adjusted, making the amount of thread for corner sewing more accurate and avoiding thread slippage at the bottom.

[0026] 3. Precise control system: By detecting the position of the take-up spring through sensors and combining it with the electronic control of the spindle angle, the system can efficiently adjust the thread release and re-clamping of the separating needle bar, ensuring the accuracy of the thread supply and making the system more responsive. Attached Figure Description

[0027] Figure 1 is a schematic diagram of the installation of the surface line control device of the present invention.

[0028] Figure 2 is a schematic diagram of the surface line control device of the present invention.

[0029] Figure 3 is a side view of the face line control device of the present invention.

[0030] Figure 4 is an exploded view of the surface line control device of the present invention.

[0031] Figure 5 is a schematic diagram of the structure of the guide component in this invention.

[0032] Figure 6 is a schematic diagram of the structure of the thread-taking spring in this invention.

[0033] Figure 7 is a half-sectional view of the face wire clamp of the present invention.

[0034] Figure 8 is a schematic diagram of the surface line arrangement in the surface line control unit of the present invention.

[0035] Figure 9 is a simplified diagram of the face line arrangement of the face line control unit in this invention when the take-up spring is in the initial position.

[0036] Figure 10 is a simplified diagram of the face line arrangement of the face line control unit in this invention when the line take-up lever is at its highest position.

[0037] Figure 11 is a simplified diagram of the surface line arrangement of the surface line control unit in this invention when the thread picker spring returns to the reset optimized position.

[0038] Figure 12 is a schematic diagram of the corner trace in this invention.

[0039] Figure 13 is a schematic diagram of the separation and detection component in this invention.

[0040] Figure 14 is a schematic flowchart of the sewing control method of the present invention.

[0041] Attached Icon Descriptions: 1. Wire Clamping Mounting Plate; 2. Wire Take-Up Rod; 201. Wire Take-Up Hole; 3. Center Wire Hook; 301. Center Hole of Wire Hook; 4. Top Wire Clamp; 401. Wire Clamping Bolt; 402. Wire Clamping Plate; 403. Wire Clamping Pressure Plate; 404. Wire Clamping Spring; 405. Adjusting Spring Washer; 406. Adjusting Nut; 407. Wire Loosening Electromagnet; 408. Wire Loosening Shaft; 5. Wire Take-Up Spring Mechanism; 501. Guide Assembly; 5011. Guide Groove; 5012. Guide Wire Hook; 502. Wire Take-Up Spring; 5021. Wire Hook Rod Part; 5022. Insertion Part; 5023. Collar; 503. Adjusting Short Shaft; 504. Adjusting Turtle; 505. Short Shaft Locking Nut; 506. Cover; 507. Bushing; 508. Spring Limiting Part; 509. Spring Limiting Nut; 510. Positioning Ring; 511. Locking Screw; 512. Fixing Bolt; 513. Washer; 514. Wire Take-Up Spring Sensor; 6. 7 Needle bar; 8 Needle; 801 Corner stitch; 802 First stitch segment; 9 Second stitch segment; 901 Separation detection assembly; 902 Hall sensor.Magnet assembly Detailed Implementation

[0042] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0043] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0044] Referring to Figures 1 to 13, this invention provides a top thread control device for optimizing corner sewing on a double-needle sewing machine. The double-needle sewing machine includes two needle bars 6, each with a needle 7 at its lower end. The top thread control device includes a center thread hook 3, a thread take-up lever 2, two top thread clamps 4, and a thread take-up spring mechanism 5. The center thread hook 3 has two thread hook center holes 301, and the thread take-up lever 2 has two thread take-up holes 201. The top thread clamps 4 can clamp or release the top thread. The thread take-up spring mechanism 5 includes a thread take-up spring 502. In this invention, the thread take-up spring mechanism 5 also includes two guide components 501. The guide components 501 are fixedly installed in the double-needle sewing machine. The guide components 501 include guide grooves 5011 and guide hooks 5012. There are two thread take-up springs 502, each including a hook rod portion 5021 for contacting the top thread. The hook rod portion 5021 can rotate around... When the rotating axis rotates up and down, and the hook rod 5021 moves upward, the take-up spring 502 is in an elastic energy storage state and provides elastic force to drive the hook rod 5021 to return downward. One guide component 501, the take-up spring 502, the top thread clamp 4, the thread hook center hole 301 and the take-up hole 201 form a top thread control unit. Another guide component 501, the take-up spring 502, the top thread clamp 4, the thread hook center hole 301 and the take-up hole 201 form another top thread control unit. Each top thread control unit is used to control the top thread of one needle 7. The top thread passes through the top thread clamp 4, the guide groove 5011, the guide hook 5012, the bottom side of the hook rod 5021, the take-up hole 201 and the thread hook center hole 301 in the corresponding top thread control unit and then passes through the needle 7. When the take-up rod 2 moves upward, the top thread will drive the hook rod 5021 to rotate upward.

[0045] The basic working principle of the thread control device of the present invention is as follows: two thread control units are used to control the thread supply of the two needles 7 respectively. The thread passes through the thread clamp 4 and can be clamped or released by the thread clamp 4. The thread clamp 4 can specifically adopt the existing structure. After the top thread comes out of the top thread holder 4, it is guided and turned by the guide groove 5011 of the guide assembly 501. The guide groove 5011 is preferably annular, and its axis is coaxial with the rotation axis of the hook rod 5021 of the take-up spring 502. The top thread goes around the bottom of the annular guide groove 5011 and goes upward, and then passes through the guide hook 5012. Then the top thread passes through the bottom side of the hook rod 5021 of the take-up spring 502, extends upward and passes through the take-up hole 201 of the take-up rod 2. When the top thread is pulled upward, it can pull the hook rod 5021 to rotate upward. Correspondingly, the take-up spring 502 can apply a downward pulling force to the top thread through the hook rod 5021. After the top thread comes out of the take-up hole 201, it extends downward and passes through the center hole 301 of the thread hook 3, and finally enters the needle 7.

[0046] The thread control device of the present invention can control the supply of thread during the sewing process through the thread clamp 4, and can control the tension of the thread by combining the action of the guide component 501 and the take-up spring 502. It can be used for corner sewing on a double needle sewing machine. The shape of the corner stitch 8 is shown in Figure 12. The part of the corner stitch 8 before the corner is called the first stitch 801, and the part after the corner is called the second stitch. When performing corner sewing, one of the needle bars 6 is stationary when the fabric rotates. It is called the separated needle bar 6. The stitch formed is located on the inside of the corner. The other needle bar 6 and the needle 7 work normally. The stitch formed is located on the outside of the corner. Analysis revealed that the corner stitching issue occurs after the first stitch 801 is completed. When the fabric is rotated to sew the second stitch 802, the bobbin thread is pulled out by the top thread, resulting in an unsightly bobbin thread protrusion at the corner. The apparent cause is that the tension of the top thread is greater than that of the bobbin thread, causing the bobbin thread to be pulled out. The underlying cause is that after the fabric is rotated to the corner, the bobbin thread tension is reduced to the locking force of the interlacing top and bottom threads in the fabric. The separated needle bar 6 exerts a much greater force on the top thread than the bobbin thread tension due to the periodic force applied by the take-up spring 502 and the take-up lever 2. Therefore, the bobbin thread is pulled out. Specifically, during normal sewing, the bobbin thread tension is mainly held in place by the spring on the shuttle. However, when the double needles are sewing the first stitch 801, taking the left needle bar 6 as an example, the left needle bar 6 does not move. But because the machine is still feeding, the bobbin thread is continuously pulled out from the shuttle under the pull of the fabric. At this time, the bobbin thread is still taut and is subjected to the force of the shuttle spring. Once the first stitch 801 is sewn and the fabric is rotated, the bobbin thread will be in a relaxed state. At this time, the only force on the bobbin thread is the locking force of the interlacing of the top and bottom threads, which is relatively small and easily pulled out by external forces. During normal sewing, when the take-up lever 2 rises to its highest point, the tension of the top thread is very high because it needs to tighten the top thread and pull out the amount of thread from the top thread clamp 4. Therefore, the hook part 5021 of the take-up spring 502 will be in an upward pulling state, and the take-up spring 502 will be in an elastic energy storage state. See Figure 8. One take-up spring 502 (the take-up spring 502 in the top thread control unit corresponding to the top thread separated from the needle bar 6) is under force, and the other is not under force. The needle bar 6 is mechanically separated at its highest point. After the needle bar 6 is separated, the take-up lever 2 moves to its highest point within this cycle, and the take-up lever 2 completes the take-up and take-up actions. Therefore, the amount of thread taken up by the separated part of the needle bar 6 will not change, which is the amount of thread in the tensioned state of the take-up spring 502.However, when sewing the first stitch 801, the take-up lever 2 descends, increasing the thread supply. The take-up spring 502 returns to its relaxed state, and the hook part 5021 of the take-up spring 502 has no elasticity against the top thread. But once the take-up lever 2 rises, the take-up spring 502 continuously applies elasticity to the top thread. The rising of the take-up lever 2 also exerts a pulling force on the top thread. This is because the take-up spring 502 and the take-up lever 2 periodically apply force to the top thread. The bobbin thread is pulled out by the top thread. This phenomenon often occurs when sewing the second stitch, because at this time the bobbin thread only has the locking force of the interlacing bottom and top threads. When sewing the first stitch 801, on the one hand, the bobbin thread still has the force of the bobbin case spring, and on the other hand, the top thread on the fabric is held down by the presser foot. The pulling force applied to the top thread by the take-up spring 502 and the take-up lever 2 will not pull the bobbin thread out.

[0047] This invention, by setting up two thread control units, with their take-up springs 502 and thread clamps 4 operating independently, allows for control of the thread tension corresponding to the separated needle bar 6 during the second stitch sewing process through the coordinated timing of the clamping and releasing actions of the take-up lever 2 and the thread clamp 4. This ensures sufficient thread supply, preventing both excessive thread tension that could pull out the bobbin and cause thread slippage at corners, and insufficient thread tension that could lead to the take-up spring 502 fully resetting and causing thread slippage.

[0048] Referring to Figures 1 to 7, the surface line control device of the present invention will be further described below with reference to a specific embodiment:

[0049] In this embodiment, referring to Figures 2, 3, and 4, as a preferred design, the thread control device includes a thread clamping mounting plate 1 fixedly mounted on the housing of a double-needle sewing machine. The thread take-up spring mechanism 5 and the thread clamp 4 are both mounted on the thread clamping mounting plate 1. The thread take-up spring mechanism 5 also includes a thread take-up spring adjustment assembly, which is connected to two thread take-up springs 502. This assembly can adjust the angle position of the two thread take-up springs 502 respectively, specifically adjusting and locking the position of the hook rod 5021. This allows adjustment of the position of the two thread take-up springs 502 during operation, i.e., adjustment of their elasticity.

[0050] In this embodiment, referring to Figures 2, 3, and 4, the line take-up spring adjustment assembly includes a rotatable adjustment short shaft 503, a short shaft locking structure for locking the adjustment short shaft 503, an adjustment knob 504 rotatably mounted on the rotatable short shaft, and a knob locking structure for locking the adjustment knob 504. The adjustment short shaft 503 is installed in the line clamping mounting plate 1 and can rotate around its axis. A spacer is fitted on the adjustment short shaft 503. The guide assembly 501 and the line take-up spring 502 are both fitted on the spacer. The line take-up spring 502 can rotate around the adjustment short shaft 503, that is, the central axis of the adjustment short shaft 503 serves as the rotation axis of the hook rod 5021. A gasket 513 fitted on the spacer is also provided between the two guide assemblies 501 to separate them. One end of one of the thread take-up springs 502 is connected to the adjusting short shaft 503. Specifically, one end of the thread take-up spring 502 has a plug portion 5022, which is inserted into the adjusting short shaft 503 and covered by a cover 506 installed at the end of the adjusting short shaft 503 to prevent the plug portion 5022 from coming out of the adjusting short shaft 503. By rotating the adjusting short shaft 503, the thread take-up spring 502 can be rotated. After the adjusting short shaft 503 is fixed by the short shaft locking structure, the angle position of the thread take-up spring 502 can be locked. Another thread take-up spring 502 has one end connected to the adjusting knob 504. Specifically, the adjusting knob 504 has an inner hole, through which the thread take-up spring 502 is fitted onto the outside. One end of the thread take-up spring 502 has a plug part 5022, which passes through the adjusting knob 504. By rotating the adjusting knob 504, the thread take-up spring 502 connected to it can be driven to rotate on the adjusting short shaft 503. After locking the adjusting knob 504 by the knob locking structure, the angle position of the thread take-up spring 502 can be locked.

[0051] In this embodiment, referring to Figures 2, 3, and 4, as a preferred design, the torsion locking structure in the thread take-up spring mechanism 5 includes a positioning ring 510, a locking screw 511, and a fixing bolt 512. The positioning ring 510 has an inner hole and fits onto the outer circle of the adjusting knob 504 through the inner hole. The positioning ring 510 is fixedly connected to the wire clamping mounting plate 1 by the fixing bolt 512. The locking screw 511 is screwed into the positioning ring 510 and pressed against the outer circle of the adjusting knob 504, thereby locking the adjusting knob 504. When the locking screw 511 is loosened, the adjusting knob 504 can rotate smoothly. The fixing bolt 512 also passes through two guide components 501 and a washer 513, thereby fixing the guide components 501 and preventing them from rotating circumferentially on the adjusting short shaft 503. The short shaft locking structure includes a short shaft locking nut 505 screwed to the other end of the adjusting short shaft 503. The short shaft locking nut 505 presses against the end face of the positioning ring 510, thereby locking the adjusting short shaft 503 so that it cannot rotate.

[0052] In this embodiment, referring to Figures 2, 3, and 4, as a preferred design, the thread-taking spring mechanism 5 further includes two spring-limiting members 508 for limiting the initial position of the thread-taking spring 502. These spring-limiting members 508 are respectively used to limit the position of the two thread-taking springs 502. The two spring-limiting members 508 are fixed to the wire clamping mounting plate 1 and the positioning ring 510, respectively. When the hook portion 5021 of the thread-taking spring 502 is not subjected to an upward pulling force from the thread, the thread-taking spring 502 is in its initial position. At this time, the lower side of the hook portion 5021 indirectly abuts against the spring-limiting member 508, thereby ensuring that the thread-taking spring 502 is stable in its initial position. Preferably, the spring-limiting member 508 is provided with a strip groove, through which the position of the spring-limiting member 508 can be adjusted to cooperate in adjusting the initial position of the thread-taking spring 502.

[0053] In this embodiment, referring to Figures 2, 4 and 6, as a preferred design, the take-up spring 502 is a multi-turn torsion spring structure, which is convenient to be fitted onto the adjusting short shaft 503. One end of the take-up spring 502 is a plug part 5022, which is used to insert into the positioning ring 510 or the adjusting short shaft 503. The other end is bent to form a hook rod part 5021, and a collar 5023 is obtained at the end. The collar 5023 is used to fit onto the adjusting short shaft 503, thereby improving the installation stability of the take-up spring 502.

[0054] In this embodiment, referring to Figure 4, as a preferred design, the take-up spring mechanism 5 further includes two take-up spring sensors 514. The two take-up spring sensors 514 are mounted on the adjusting short shaft 503 and are used to measure the rotation angle position of the two take-up springs 502 respectively. The take-up spring sensors 514 are used to communicate with the electronic control system of the double-needle sewing machine and transmit the detection information to the electronic control system.

[0055] In this embodiment, referring to Figures 2 and 7, as a preferred design, the thread clamp 4 includes a clamping bolt 401, clamping plates 402, a clamping pressure plate 403, a clamping spring 404, an adjusting spring washer 405, an adjusting nut 406, a loosening electromagnet 407, and a loosening shaft 408. The clamping bolt 401 is fixed to the clamping mounting plate 1. Two clamping plates 402 are fitted onto the clamping bolt 401 and can move along the clamping bolt 401. The two clamping plates 402 are arranged opposite to each other, and the thread passes between the two clamping plates 402. The clamping pressure plate 403 is mounted on the clamping bolt 401 and can move along the clamping bolt 401. One side of the two clamping plates 402 is limited, and the clamping plates 402 are displaced to the other side, which can apply pressure to one clamping plate 402, causing the two clamping plates 402 to approach and abut against each other. The adjusting nut 406 is screwed onto the wire clamping bolt 401. The wire clamping spring 404 is fitted onto the wire clamping bolt 401, with one end abutting against the wire clamping pressure plate 403, and the other end abutting against the adjusting nut 406 via the adjusting spring washer 405. The wire loosening electromagnet 407 is fixed on the wire clamping mounting plate 1. The wire loosening shaft 408 is installed in the inner hole opened in the wire clamping bolt 401 and can move axially along the wire clamping bolt 401. One end of the wire loosening shaft 408 abuts against or connects to the wire clamping pressure plate 403. When the wire-releasing electromagnet 407 is energized, the magnetic force pushes the wire-releasing shaft 408 towards the side of the wire-clamping plate 403. The wire-releasing shaft 408 pushes the wire-clamping plate 403 to separate from the wire-clamping plates 402, and the two wire-clamping plates 402 loosen the wire between them. At the same time, the wire-clamping spring 404 is compressed. When the wire-releasing electromagnet 407 is de-energized, it loses its magnetic force, and the wire-clamping spring 404 pushes the wire-releasing shaft 408 to return to its original position. The wire-releasing shaft 408 pushes the wire-clamping plates 402 and applies appropriate pressure, causing the two wire-clamping plates 402 to abut against each other and clamp the wire again. The adjusting nut 406 is used to adjust the compression degree of the wire-clamping spring 404, thereby adjusting the clamping force of the two wire-clamping plates 402 on the wire. In other embodiments, the wire clamp 4 can also adopt other suitable designs that can achieve the function of loosening or clamping the wire.

[0056] This invention also provides a sewing control method for optimizing corner sewing on a double-needle sewing machine, using the aforementioned top thread control device. The movement of the top thread clamp 4 is controlled by the electronic control system of the double-needle sewing machine, and the movement of the needle bar 6 and the thread take-up lever 2 is driven by the main shaft. Referring to Figure 14, the sewing control method includes the following steps:

[0057] S1. Determine the absolute values ​​of the theoretical linear quantities corresponding to the two surface control units respectively:

[0058] The two thread control units have the same structure and principle, and are determined in the same way. Taking one as an example, refer to Figure 8. Point A represents the center of the thread hook center hole 301 in the thread control unit, point B represents the center of the thread take-up hole 201, point C represents the contact point between the hook rod 5021 of the thread take-up spring 502 and the thread, point D represents the contact point between the guide hook 5012 of the guide assembly 501 and the thread, point E represents the contact point between the bottom of the guide groove 5011 and the thread, and point F represents the center of the guide groove 5011. Taking the initial position of the thread take-up spring 502 when it is not under the upward pulling force of the thread as the calculation reference, with point C stationary, the absolute value of the theoretical thread quantity L = L AB +L BC +L CD +L DE When the main shaft rotates, it drives the thread take-up lever 2 to move up and down to different positions. The relationship between the theoretical thread quantity absolute value L and the main shaft angle θ is calculated and denoted as L = f(θ). When calculating the relationship between the theoretical thread quantity absolute value L and the main shaft angle θ, although the contact positions of the top thread with the center hole 301 of the thread hook, the thread take-up hole 201, the thread hook 5021, the guide hook 5012, the bottom of the guide groove 5011, and the thread hook 5021 may have a small range of variation during the sewing process, the influence of this range of variation on L is very small and can be ignored. Therefore, each contact point is simplified to a single point in the calculation.

[0059] During one spindle rotation cycle, the take-up lever 2 moves up and down, so the position of point B changes continuously. The positions of points A, D, and E remain relatively constant, while the position of point C changes according to the amount of thread, caused by the tension in the thread. Assuming sufficient thread, the take-up spring 502 remains in its initial position, and the thread remains stretched and does not bend. At this point, the formula L... AB +L BC +L CD +L DE To calculate the absolute value of the required thread amount at each angle of the spindle, if the actual thread amount between points A and E is less than the theoretical absolute value L, it means the take-up spring 502 must be pulled, causing the position of point C to change and move upwards relative to its initial position. Conversely, if it is greater, it means the thread between points A and E is bent and loose. When calculating the theoretical absolute value L, it is not necessary to calculate the thread amount below point A, because the needle bar 6 does not move, and the thread amount below point A remains constant.

[0060] In this embodiment, the spindle angle θ is a discrete array with equal intervals, and the interval angle Δθ is 2° to 7°. Preferably, Δθ is 5°. The spindle angle is 0° at the highest point of the line-lifting rod 2, and the spindle rotates clockwise. As shown in Figure 9, when calculating the absolute value L of the theoretical line quantity, points A, C, D, E, and F remain stationary, while only point B moves up and down. Every 5° rotation of the spindle, point B reaches a new position. At this time, L is measured and calculated. AB +L BC +L CD +L DE The absolute value of the theoretical linear quantity L corresponding to this principal axis angle is shown in Table 1 below.

[0061] Table 1: Relationship between the absolute value of theoretical linear quantity L and the principal axis angle θ

[0062] The purpose of calculating the relationship between the absolute value of the theoretical thread quantity L and the spindle angle θ is to confirm at what spindle angle the separated needle bar 6 will be pulled and moved by the take-up spring 502 due to the rise of the take-up lever 2 and insufficient thread quantity.

[0063] S2. Determine the spindle angle θ1 for the thread release timing and θ2 for the thread release reset timing corresponding to the two thread control units. The two thread control units have the same structure and principle, so the determination method is also the same. Taking one of them as an example, the specific steps include:

[0064] S21. When the line-lifting lever 2 actually reaches its highest point, the guide hook 5012 of the line-lifting spring 502 will move upward, as shown in Figure 10. At this time, points B, C, D, and E are collinear. Calculate L at this point. AB +L BE Let L1 be the absolute value of the theoretical line quantity at the time of line slack, and determine the principal axis angle at this time according to L=f(θ), which is denoted as the principal axis angle θ1 at the time of line slack.

[0065] In this embodiment, specifically, when L is measured and calculated... AB +L BE When the thread amount is 239.5mm, referring to Table 1 above, the closest to 239.5mm is 239.2mm when the spindle angle is 330°. Therefore, when the thread is released, the spindle angle θ1 is 330°. This means that when the spindle angle is 330°, the part that was originally separated from the needle bar 6 will continue to rise due to insufficient thread amount when the spindle angle is 330°. The take-up lever 2 will continue to rise, the take-up spring 502 will be pulled and rotated, and the thread will generate a large pulling force.

[0066] S22. Set the reset optimization position of the thread take-up spring 502. When the thread take-up spring 502 is in the reset optimization position, the hook rod rotates upward by an angle α relative to the initial position, as shown in Figure 11. Obtain the L value corresponding to when the thread take-up spring 502 is in the reset optimization position during the actual operation of the double-needle sewing machine.AB +L BC +L CD +L DE The length of the line is denoted as the absolute value of the theoretical line quantity at the time of line slack reset, L2. The corresponding spindle angle is determined according to L=f(θ), and denoted as the spindle angle θ2 at the time of line slack reset.

[0067] When the double-needle sewing machine is in actual operation, as the take-up lever 2 moves downward from its highest point, the hook part 5021 of the take-up spring 502 also moves downward. That is, point C will rotate downward around point F. If there is enough thread, the hook part 5021 of the take-up spring 502 can return to its initial position. However, in order to prevent the take-up spring 502 from completely returning to its initial position and causing the thread to slip, a reset optimization position and its corresponding angle α are set according to actual needs. During subsequent normal sewing, the take-up spring 502 is controlled to reset to the reset optimization position, rather than to reset to the initial position, as shown in Figure 11. Here, C and C' represent the point positions of the hook part 5021 when it is in the initial position and the reset optimization position, respectively, thus avoiding the problem of thread slippage. The size of the angle α is set according to actual needs, preferably 5 to 10°, with 7° being preferred. In this embodiment, specifically, when the take-up spring 502 resets to the reset optimization position, L is measured and calculated. AB +L BC +L CD +L DE The value is 253.2mm. Referring to Table 1 above, the closest value to 253.2mm is 253.1mm when the spindle angle is 350°. Therefore, the spindle angle θ2 is 350° when the wire is released and reset.

[0068] S3. When sewing at corners, identify which needle bar 6 is not moving; this is recorded as the separated needle bar 6, and the top thread control unit corresponding to it is recorded as the separated top thread control unit. The separated needle bar 6 can be identified using one of the following two methods:

[0069] Method 1: The take-up spring mechanism 5 includes two take-up spring sensors 514. These sensors measure the rotational position of the hook rod 5021 of each of the two take-up springs 502. The sensors 514 are connected to the electronic control system of the double-needle sewing machine. The spindle angle range θ3~θ4 corresponding to the take-up springs 502 of the two thread control units when they are separated and not rotating is determined: When the fabric is rotated, the needle 7 is in the lower stop position. During the subsequent movement of the take-up rod 2 to its lowest position, if the needle bar 6 has separated, there exists a spindle angle range θ3~θ4. Within this range, the hook rod 5021 of the take-up spring 502 will not rotate. The movement of the take-up spring 502 is measured in real time by the take-up spring sensor 514, and the electronic control system determines whether the hook rod 5021 rotates when the spindle is within the angle range of θ3 to θ4. If no rotation occurs, the take-up spring 502 belongs to the surface thread control unit that has been separated, and the corresponding needle bar 6 is the needle bar that has been separated.

[0070] Specifically, the take-up spring sensor 514 detects the fabric after the presser foot has rotated. During fabric rotation, the needle 7 is in the lower stop position, and the spindle angle is typically 90°. When the needle bar 6 is not disengaged, the take-up lever 2 reaches its lowest point, at which point the spindle angle is typically 240°. Because the hook loop of the rotary hook expands to its maximum, the rotary hook requires a large amount of thread. At this time, the rotary hook pulls on the opposite thread, causing the take-up spring 502 to rotate. However, since the disengaged needle bar 6 does not move up and down, the amount of thread is sufficient within the 90° to -250° range, and the hook part 5021 of the take-up spring 502 will not rotate. Therefore, the take-up spring sensor 514 determines whether the take-up spring 502 is moving within the spindle angle range of 90° to 250°. When the take-up spring 502 moves, the detected signal is lost. This allows us to determine which needle bar 6 is working normally and which needle bar 6 is disengaged.

[0071] Method 2: The separation of the two needle bars 6 is controlled by a separation positioning wrench. The double-needle sewing machine is equipped with a separation detection component 9 to detect the movement of the separation positioning wrench. By detecting the movement of the separation positioning wrench through the separation detection component 9, it can be confirmed which needle bar 6 has been separated. Referring to Figure 13, the separation detection component 9 can adopt a suitable existing structure, for example, including a Hall sensor 901 and a magnet assembly 902. The magnet assembly 902 is installed on the separation positioning wrench, and it has two magnets. The Hall sensor 901 is fixed to the machine housing. When the separation positioning wrench is turned, the magnet approaches the Hall sensor 901, generating a signal. Thus, before the first stitch 801 is finished sewing, the electronic control system can know in advance which needle bar 6 has separated. Using this method, the thread can be loosened when the second stitch 802 starts sewing, which is earlier than the logic in Method 1. It also eliminates the need to set up a take-up spring sensor 514 to detect the angle position of the take-up spring 502, and directly uses the spindle electronically controlled angle position as the judgment reference for thread loosening.

[0072] S4. When sewing the second stitch after the fabric has rotated, the separated top thread control unit shall operate as follows:

[0073] S41. When the spindle angle is less than or equal to θ1, control the face wire clamp 4 to release the face wire.

[0074] Specifically, when using method one in step S3 to determine which needle bar 6 has been separated, the signal from the take-up spring sensor 514, combined with the spindle angle, determines which needle bar 6 has been separated. Then, before the spindle angle reaches θ1, the corresponding top thread clamp 4 can be controlled by the electronic control system to release the top thread. When using method two in step S3 to determine which needle bar 6 has been separated, the electronic control system can control the corresponding top thread clamp 4 to release the thread at the beginning of the second stitch 802. At this time, the spindle angle is before θ1, allowing for early thread feeding.

[0075] During sewing, the top thread clamp 4 releases the top thread when the main axis angle reaches θ1 or earlier. When the take-up lever 2 moves upward, the top thread can be smoothly pulled out from the top thread clamp 4 without the problem of insufficient top thread. Therefore, the top thread tension will not be much greater than the bottom thread tension due to the periodic pulling force of the take-up lever 2 and the take-up spring 502, thus preventing the bottom thread from being pulled out and avoiding the problem of thread slippage at corners.

[0076] The actual increase in thread allowance only begins at θ1. Below this angle, even if the thread is loosened, the sufficient thread allowance prevents the thread from being pulled out of the thread holder 4 when the take-up lever 2 rises. The only time to loosen the thread is after the fabric has rotated and the user begins sewing the second stitch 802. The first stitch 801 cannot be chosen because there's a possibility that only one stitch of the first stitch 801 is sewn at a corner; if the thread is loosened at that stitch, the bobbin thread won't be able to be retrieved. The later stitches of the second stitch 802 also cannot be chosen because if the thread allowance is given too late, the bobbin thread will have already been pulled out.

[0077] S42. When the spindle angle is θ2, the thread clamp 4 is reset, clamping the thread. As the take-up lever 2 descends, the thread becomes slack. The take-up spring 502 will reset under its elastic force. However, since the thread is already clamped by the thread clamp 4, the amount of thread is limited, and the take-up spring 502 will not completely reset to its initial position. Instead, when it resets to the optimized reset position, the hook lever 5021 re-tightens the thread. This tension overcomes the restoring elasticity of the take-up spring 502, causing it to stop at the optimized reset position. Preferably, the take-up spring sensor 514 can also measure in real time whether the take-up spring 502 stops at the optimized reset position. The take-up spring 502 can be detected by the take-up spring sensor 514 when it is in the optimized reset position. If the signal from the take-up spring sensor 514 is lost, and the spindle angle is compared with θ2 at this time, the actual slack reset angle can be determined, ensuring the accuracy of the amount of thread.

[0078] As can be seen from the above, the thread control device and sewing control method of the present invention have the following beneficial effects:

[0079] 1. Improved corner sewing quality: During corner sewing, the timing and amount of thread feeding of the needle bar 6 and needle 7 corresponding to the separated needle bar 6 can be controlled. This solves the problem of the bottom thread being pulled to the fabric surface and causing long, loose threads when sewing corners with thin materials and mismatched thread combinations. This greatly improves the aesthetics and stability of the sewn stitches. In addition, the optimized reset position of the take-up spring 502 can be controlled to avoid the problem of the top thread being loose due to the take-up spring 502 being fully reset because the top thread tension is too low.

[0080] 2. Intelligent thread supply adjustment: Through electronic thread loosening and sensor detection, the supply and demand of thread for face-to-face sewing is automatically adjusted, making the amount of thread for corner sewing more accurate and avoiding thread slippage at the bottom.

[0081] 3. Precise control system: By detecting the position of the take-up spring 502 through sensors and combining it with the electronic control spindle angle, the system can efficiently adjust the thread release and re-clamping of the separating needle bar 6, ensuring the accuracy of the thread supply and making the system more responsive.

[0082] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0083] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A top thread control device for optimizing corner sewing on a double-needle sewing machine, the double-needle sewing machine comprising two needle bars (6), each needle bar having a needle (7) at its lower end, the top thread control device comprising a center thread hook (3), a thread take-up lever (2), two top thread clamps (4), and a thread take-up spring mechanism (5), the center thread hook (3) having two thread hook center holes (301), the thread take-up lever (2) having two thread take-up holes (201), the top thread clamps (4) capable of clamping or releasing the top thread, and the thread take-up spring mechanism (5) comprising a thread take-up spring (502), characterized in that: The thread take-up spring mechanism (5) further includes two guide components (501), which are fixedly installed in the double-needle sewing machine. The guide component (501) includes a guide groove (5011) and a guide hook (5012). There are two thread take-up springs (502), each including a hook rod (5021) for contacting the top thread. The hook rod (5021) can rotate up and down around the rotation axis, and when the hook rod (5021) moves upward, the thread take-up spring (502) is in an elastic energy storage state and provides an elastic force to drive the hook rod (5021) to return downward. The mechanism also includes one guide component (501), one thread take-up spring (502), and one top thread clamp (4). The thread hook center hole (301) and the thread take-up hole (201) form a thread control unit. Another guide component (501), the thread take-up spring (502), the thread clamp (4), the thread hook center hole (301) and the thread take-up hole (201) form another thread control unit. Each thread control unit is used to control the thread of a needle (7). The thread passes through the thread clamp (4), guide groove (5011), guide hook (5012), bottom side of hook rod (5021), thread take-up hole (201) and thread hook center hole (301) in the corresponding thread control unit and then passes through the needle (7). When the thread take-up rod (2) moves upward, the thread will drive the hook rod (5021) to rotate upward.

2. The surface line control device according to claim 1, characterized in that: The thread-taking spring mechanism (5) also includes a thread-taking spring adjustment assembly, which is connected to two thread-taking springs (502) and can adjust and lock the rotation angle of the two thread-taking springs (502) respectively.

3. The surface line control device according to claim 2, characterized in that: The thread take-up spring adjustment assembly includes a rotatable adjustment short shaft (503), a short shaft locking structure for locking the adjustment short shaft (503), an adjustment knob (504) rotatably mounted on the adjustment short shaft (503), and a knob locking structure for locking the adjustment knob (504). Two thread take-up springs (502) are rotatably mounted on the adjustment short shaft (503), with one end of one thread take-up spring (502) connected to the adjustment short shaft (503) and one end of the other thread take-up spring (502) connected to the adjustment knob (504).

4. The surface line control device according to claim 1, characterized in that: The thread take-up spring mechanism (5) also includes two thread take-up spring sensors (514). The two thread take-up spring sensors (514) are used to measure the rotation angle position of the hook rod (5021) of the two thread take-up springs (502) respectively, and the thread take-up spring sensors (514) are used to communicate with the electronic control system of the double needle sewing machine.

5. A sewing control method for optimizing corner sewing on a double-needle sewing machine, characterized in that: The sewing control method, performed using the thread control device as described in claim 1, includes the following steps: S1. Determine the absolute value of the theoretical line quantity for each of the two line control units: Represent the center of the hook center hole (301) in the line control unit as point A, the center of the take-up hole (201) as point B, the contact point between the hook rod (5021) of the take-up spring (502) and the line as point C, the contact point between the guide hook (5012) of the guide assembly (501) and the line as point D, the contact point between the guide groove (5011) and the line as point E, and the center of the guide groove (5011) as point F. Using the initial position of the take-up spring (502) when it is not under upward tension from the line as the calculation benchmark, and with point C stationary, record the absolute value of the theoretical line quantity as L = L. AB +L BC +L CD +L DE When the main shaft rotates, it will drive the line take-up lever (2) to move up and down to different positions. The relationship between the absolute value of the theoretical line quantity L and the angle θ of the main shaft is calculated and denoted as L=f(θ). S2. Determine the spindle angle θ1 for the thread release timing and the spindle angle θ2 for the thread release reset timing corresponding to the two thread control units respectively: S21. When the line-lifting lever (2) actually reaches its highest point, the hook rod part (5021) of the line-lifting spring (502) will move upward. Calculate L at this time. AB +L BE The length of the line is taken as the absolute value of the theoretical line quantity L1 when the line is loosened. Then, the principal axis angle at this time is determined according to L=f(θ), and it is recorded as the principal axis angle θ1 when the line is loosened. S22. Set the reset optimization position of the thread take-up spring (502). When the thread take-up spring (502) is in the reset optimization position, the upward rotation angle of the thread hook (5021) relative to the initial position is α. Obtain the L corresponding to the actual operation of the double needle sewing machine until the thread take-up spring (502) is in the reset optimization position. AB +L BC +L CD +L DE The length of the line is denoted as the absolute value of the theoretical line quantity at the time of line slack reset, L2. The corresponding spindle angle is determined according to L=f(θ), and denoted as the spindle angle θ2 at the time of line slack reset. S3. When sewing at a corner, determine which needle bar (6) does not move and record it as the separated needle bar (6). The face thread control unit corresponding to the face thread on it is recorded as the separated face thread control unit. S4. When sewing the second stitch after the fabric has rotated, the separated top thread control unit shall operate as follows: S41. When the spindle angle is less than or equal to θ1, control the face wire clamp (4) to release the face wire; S42. When the spindle angle is θ2, control the face wire clamp (4) to reset and clamp the face wire.

6. The sewing control method according to claim 5, characterized in that: In step S1, the principal axis angle θ is a discrete array with equal intervals, and the interval angle Δθ is 2° to 7°.

7. The sewing control method according to claim 5, characterized in that: In step S22, the angle α is 5 to 10°.

8. The sewing control method according to claim 5, characterized in that: In step S3, the method for determining the separated needle bar (6) includes: the take-up spring mechanism (5) further includes two take-up spring sensors (514), the two take-up spring sensors (514) are used to measure the rotation position of the hook rod part (5021) of the two take-up springs (502) respectively, and the take-up spring sensors (514) are connected to the electronic control system of the double needle sewing machine. The spindle angle range θ3~θ4 corresponding to the take-up spring (502) of the two thread control units when they are separated and not rotating is determined respectively: When the fabric is rotated, the needle (7) is in the lower stop position. During the process of the take-up bar (2) running to the lowest point, if the needle bar (6) has separated, there is a spindle angle range θ3~θ4. Within this range, the hook part (5021) of the take-up spring (502) will not rotate. The movement of the hook rod (5021) of the take-up spring (502) is measured in real time by the take-up spring sensor (514), and the electronic control system determines whether the hook rod (5021) rotates when the spindle is in the angle range of θ3 to θ4. If it does not rotate, the take-up spring (502) belongs to the surface thread control unit that has been separated, and the corresponding needle bar (6) is the needle bar (6) that has been separated.

9. The sewing control method according to claim 5, characterized in that: In step S3, the method for determining the separated needle bar (6) includes: the separation action of the two needle bars (6) is controlled by a separation positioning wrench. The double needle sewing machine is equipped with a separation detection component (9) for detecting the separation positioning wrench. The separated needle bar (6) is determined by the separation detection component (9).

10. The sewing control method according to claim 8, characterized in that: In step S42, during the rotation of the spindle to θ2, the thread take-up spring sensor (514) measures whether the thread take-up spring (502) stops resetting to the optimized position.

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