A method for controlling the operation of a sewing machine to sew a small bird's nest.

Abstract

This invention relates to a method for controlling the operation of a sewing machine to sew a small bird's nest, comprising the following working processes: Thread cutting process: The main shaft rotates; when the rotation angle is β1, the moving blade extends; when it is β2, the moving blade reaches the thread cutting extension position. The main shaft rotates again, the moving blade stops at the thread cutting extension position, the take-up lever rises, and when the main shaft rotates at an angle β3, the moving blade begins to reset, hooking the bottom thread and top thread. When the main shaft rotates at an angle β4, the take-up lever rises to position Z1, the moving blade returns to its initial position, the top and bottom threads are cut, and the bottom thread is clamped. Sewing start process: The main shaft rotates, the suction port generates a suction effect, and the moving blade extends. The moving blade reaches the sewing start extension position. The moving blade remains stationary, the needle descends, passes through the through hole in the blade section, and rises, the take-up lever rises. When the take-up lever rises to position Z2, the moving blade retracts. The moving blade reaches its initial position and remains stationary, cutting the top thread, which is clamped. The main shaft continues to rotate for two cycles, forming two stitches. The suction assembly stops.

Description

Technical Field

[0001] This invention relates to the field of sewing machinery technology, specifically to a method for controlling the operation of a sewing machine to sew a small bird's nest. Background Technology

[0002] In conventional double-needle sewing machines, the thread-cutting mechanism uses an electromagnet in conjunction with a thread-cutting cam to drive the moving blade back and forth, achieving the thread-cutting function. In this design, the stroke of the moving blade is fixed, and the trajectory of the thread-cutting cam directly determines the stroke of the moving blade's extension and retraction. See the appendix for the structure of a conventional thread-cutting mechanism in a double-needle sewing machine. Figure 1 As shown, the wire-cutting electromagnet is fixed on the base plate. When the wire-cutting electromagnet is energized and attracted, the ball bearings of the main rod assembly will be engaged in the groove of the wire-cutting cam. As the wire-cutting cam rotates, the moving blade drive slider is driven to slide back and forth through the main rod assembly and the intermediate transmission mechanism composed of multiple transmission components. The moving blade drive slider drives the moving blade fixed on it to move back and forth. Therefore, the moving blade moves back and forth under the drive of the wire-cutting cam. After engaging with the fixed blade, it can cut the thread.

[0003] The principle of existing wire-cutting mechanisms is as follows: (See Appendix) Figure 1 and attached Figure 4 As shown, the moving cutter has a hook and a moving blade. When the moving cutter begins to retract in preparation to cut the thread, the top thread and the bottom thread are already hooked by the hook on the moving cutter. At this time, the top thread and the bottom thread are still a complete thread. When the thread above the moving blade of the moving cutter comes into contact with the fixed blade of the stationary cutter, the thread will be cut. After the thread is cut, the top thread on the outer side of the stationary blade connects to the fabric, the top thread on the inner side connects to the needle, and the bottom thread connects to the bobbin. The bottom thread is also held by the bottom thread clamp under the moving cutter to prevent it from falling off.

[0004] After trimming, existing double-needle sewing machines often leave long thread ends on the top thread. When starting a new stitch, these long ends tend to tangle and become intertwined with the bottom thread or the sewing material itself, forming a raised clump of thread, commonly known as a "bird's nest." This clump is not only unsightly, but if it's in close contact with the skin, it can cause itching and discomfort. Therefore, removing these "bird's nests" is a persistent challenge in the garment industry, especially with double-needle sewing machines. These machines have two rotary hooks, one on each side, and the existing bird's nest removal mechanisms of single-needle flatbed sewing machines cannot be used on double-needle machines. Furthermore, the limited space on double-needle sewing machines restricts installation space. Summary of the Invention

[0005] 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 method for controlling the operation of sewing a small bird's nest in a sewing machine. Through the effective cooperation of the thread cutting mechanism, the jumper bar and the needle, a small bird's nest can be formed when sewing begins.

[0006] To achieve the above objectives, this invention provides a method for controlling the operation of a sewing machine to sew a small bird's nest. The sewing machine's needle and thread take-up lever are driven by a main shaft. Each rotation of the main shaft completes one up-and-down reciprocating motion. When the thread take-up lever is at its highest position, the shaft rotation angle is 0°, and the needle is positioned on the needle plate and descending. The sewing machine has a thread-cutting mechanism and an electronic control system. The thread-cutting mechanism includes a fixed blade, a moving blade, and a moving blade drive unit. The electronic control system is connected to the moving blade drive unit. The moving blade is equipped with... The device includes a hook portion and a through hole on the moving blade. One edge of the upper opening of the through hole forms the blade edge. The thread-cutting mechanism also includes a bottom thread retaining spring, a thread clamping plate, and an adsorption assembly. The bottom thread retaining spring is located below the moving blade, and the lower side of the moving blade has a bottom thread retaining portion. The adsorption assembly has an adsorption port and can generate a suction effect at the adsorption port. The thread clamping plate is located on the upper side of the moving blade, and the moving blade has a top thread clamping portion. The electronic control system is connected to the adsorption assembly. The operation control method includes the following working process:

[0007] A. The thread trimming process after normal sewing includes the following steps:

[0008] A1. Start cutting the thread. The main shaft rotates. When the main shaft rotates at an angle of β1, the moving blade begins to extend. β1 is 145° to 166°. The needle is below the needle plate of the sewing machine and rises. The thread take-up lever rises. When the main shaft rotates at an angle of β2, the moving blade reaches the thread-cutting extension position and stops. β2 is 195° to 216°. During the extension process, the moving blade passes through the loop formed when the sewing machine's rotary hook catches the thread. The through hole of the blade and the hook pass over the needle axis one after the other.

[0009] A2. The main shaft continues to rotate, the moving blade stops at the thread cutting extension position, the take-up lever rises, and the bottom thread and top thread enter the hook of the moving blade. When the main shaft rotates at an angle of β3, β3 is 285°~306°, the moving blade begins to return to its initial position, the hook catches the bottom thread and top thread, and the needle is on the needle plate and rises.

[0010] A3. When the spindle rotation angle is β4, β4 is 339°~360°. When the thread take-up lever rises to position Z1, position Z1 is close to or at the highest position of the thread take-up lever. The moving knife returns to the initial position and stops. The moving knife blade meshes with the fixed knife blade on the fixed knife. The top thread and bottom thread are cut off. The bottom thread end is clamped between the bottom thread holding part of the moving knife and the bottom thread holding spring.

[0011] B. The seam-starting process includes the following steps:

[0012] B1. Start the seam opening, the main shaft rotates, the adsorption component starts to suck air, and a suction effect is generated at the adsorption port. The moving knife moves from the initial position to the seam opening extension position.

[0013] B2. Move the knife to the starting and extending position and stop, with the through hole of the knife directly below the needle;

[0014] B3. The main shaft keeps rotating, the moving knife is kept in the starting and extending position, the needle descends until it passes through the through hole of the knife, the top thread on both sides of the needle hole enters the through hole of the knife to form an incomplete thread loop, the sewing machine's shuttle moves, the shuttle tip passes through and hooks the top thread loop; then the needle rises above the needle plate, the take-up lever rises and pulls the top thread to disengage it from the shuttle, the top thread passes through the through hole of the knife;

[0015] B4. When the line-lifting lever rises to position Z2, position Z2 is close to or at the highest position of the line-lifting lever, and the moving blade begins to retract to the initial position.

[0016] B5. During the retraction process, the moving knife pulls the thread through the through hole. The moving knife reaches the initial position and remains stationary. The moving knife blade engages with the fixed knife blade to cut the thread. The cut thread is sucked away by the suction port. The thread connected to the needle is clamped by the thread clamping part and the thread clamping plate. The bottom thread is sucked by the suction port or clamped by the bottom thread holding spring and the bottom thread holding part.

[0017] B6. The spindle continues to rotate for two cycles, forming two stitches;

[0018] B7. The adsorption component stops working.

[0019] Furthermore, in step A1, when the moving blade starts to move, the adsorption component starts to work by drawing air, generating a suction effect at the adsorption port for a duration of S seconds.

[0020] Furthermore, in step A1, S = 2.

[0021] Further, in step A1, β1 is 145° and β2 is 195°; in step A2, β3 is 285°; and in step A3, β4 is 340°.

[0022] Furthermore, in step A3, position Z1 is located at the highest position of the line-lifting rod.

[0023] Furthermore, in step B1, before the main shaft rotates, the stitch length is first adjusted to A, which is smaller than the stitch length when the sewing machine is sewing normally; in step B4, two stitches are formed according to the stitch length A, and then the stitch length is adjusted to the stitch length required for normal sewing.

[0024] Furthermore, in step B1, the needle spacing A ranges from 0.5 to 1 mm.

[0025] Furthermore, in step B1, when the spindle rotation angle is 0°, the moving cutter begins to move from the initial position to the starting seam extension position.

[0026] Furthermore, in step B2, when the spindle rotates at an angle of θ1, the moving cutter reaches the starting and extending position of the seam and stops. The value of θ1 ranges from 15° to 25°.

[0027] Preferably, in step B5, the moving tool reaches its initial position and stops when the spindle rotation angle is θ2, and the value of θ2 ranges from 335° to 345°.

[0028] As described above, the operation control method of the present invention has the following beneficial effects:

[0029] 1. By incorporating a thread-cutting mechanism consisting of a bottom thread retaining spring, a thread clamping plate, an adsorption assembly, and a moving blade with a through-hole, the movement of the moving blade is controllable. Through the proper coordination of the thread-cutting mechanism, main shaft, needle, and needle bar, thread cutting after normal sewing can be smoothly achieved. Simultaneously, thread cutting prepares for subsequent starting stitches. Through the coordinated operation of the thread-cutting mechanism, main shaft, needle, and thread take-up lever, a small bird's nest function can be achieved during starting stitches. The resulting bird's nest on the fabric is small and more aesthetically pleasing, solving the problem of discomfort caused by the previously large bird's nest upon contact with the skin, thus meeting user needs.

[0030] 2. It can effectively improve the sewing thread rate. Since the thread is held by the thread clamp after the sewing, the thread will not be pulled out of the fabric due to the movement of the thread take-up lever or the needle, which will cause the sewing thread to come loose. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of an existing wire-cutting mechanism.

[0032] Figure 2 This is a schematic diagram of the wire-cutting mechanism in this invention.

[0033] Figure 3 for Figure 2 Enlarged view of circle A in the image.

[0034] Figure 4 This is a schematic diagram of the moving blade in this invention.

[0035] Figure 5 This is a flowchart illustrating the wire-cutting process in this invention.

[0036] Figure 6 This is a schematic diagram showing the correspondence between the spindle rotation angle and the moving blade action during the wire cutting process in this invention.

[0037] Figure 7 This is a schematic diagram showing the working state of the moving blade in the wire-cutting operation of the present invention when it is in the wire-cutting extension position.

[0038] Figure 8This is a flowchart illustrating the seam-starting process in this invention.

[0039] Figure 9 This is a schematic diagram showing the correspondence between the spindle rotation angle and the moving knife action during the seam-starting process in this invention.

[0040] Figure 10 This is a schematic diagram of the first state of the sewing machine during the thread-cutting process in this invention.

[0041] Figure 11 This is a schematic diagram of the second state of the sewing machine during the thread-cutting process in this invention.

[0042] Figure 12 This is a schematic diagram of the third state of the sewing machine during the thread-cutting process in this invention.

[0043] Figure 13 This is a schematic diagram of the fourth state of the sewing machine during the thread-cutting process in this invention.

[0044] Figure 14 This is a schematic diagram of the fifth state of the sewing machine during the thread-cutting process in this invention.

[0045] Figure 15 This is a schematic diagram of the sixth state of the sewing machine during the thread-cutting process in this invention.

[0046] Figure 16 This is a schematic diagram illustrating the process of cutting the surface thread during the thread-cutting operation in this invention.

[0047] Figure 17 This is a schematic diagram of the starting stitch of the seam head in this invention.

[0048] Explanation of icon numbers

[0049] 1. Rotary shuttle

[0050] 2. Fixed tool

[0051] 2a Fixed blade edge

[0052] 3. Cutting

[0053] 3a Hook

[0054] 3b Through hole in the cutting edge

[0055] 3C moving blade

[0056] 3D facet clamping part

[0057] 3e guide slot

[0058] 4. Wire-cutting cam

[0059] 5. Wire-cutting electromagnet

[0060] 6. Bottom-line holding spring

[0061] 7. Straws

[0062] 7a Adsorption port

[0063] 8. Wire clips

[0064] 9 Support spring sheet

[0065] 10 needle plate

[0066] 10a Adjusting Bolt

[0067] 11. Delivery of cloth teeth

[0068] 12 needles

[0069] 13. Side dish

[0070] 14 Bottom Line

[0071] 15. Moving blade drive slider

[0072] 16 Moving tool guide bracket

[0073] 17 Wire cutting motor

[0074] B. Start stitch head Detailed Implementation

[0075] 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.

[0076] 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.

[0077] See Figures 1 to 17This invention provides a method for controlling the operation of a sewing machine to sew a small bird's nest. The sewing machine's needle 12 and thread take-up lever are driven by a main shaft, which can be driven by a main shaft motor. When the main shaft rotates one revolution, the needle 12 and thread take-up lever complete one up-and-down reciprocating motion. When the thread take-up lever is at its highest position, the rotation angle of the shaft is recorded as 0°. At this time, the needle 12 is located above the needle plate 10 of the sewing machine and moves downwards. The sewing machine has a thread-cutting mechanism and an electronic control system, and the rotation of the main shaft is controlled by the electronic control system.

[0078] See Figure 2 , Figure 3 and Figure 4 The thread cutting mechanism includes a fixed blade 2, a movable blade 3, and a movable blade drive unit. The movable blade 3 has a hook 3a for hooking the top thread 13 and the bottom thread 14 to cut the thread. The electrical control system is connected to the movable blade drive unit and drives the movable blade 3 to move. In this invention, the movable blade 3 also has a blade through hole 3b, and one edge of the upper end of the blade through hole 3b forms the movable blade blade 3c. The thread cutting mechanism also includes a bottom thread retaining spring 6, a thread clamping piece 8, and an adsorption assembly. The bottom thread retaining spring 6 is located below the movable blade 3, and the lower side of the movable blade 3 has a bottom thread retaining part. The adsorption assembly has an adsorption port 7a and can generate a suction effect at the adsorption port 7a. The thread clamping piece 8 is located on the upper side of the movable blade 3, and the movable blade 3 has a top thread clamping part 3d. The electrical control system is connected to the adsorption assembly.

[0079] The operation control method of the present invention includes the following working process:

[0080] A. Thread trimming after normal sewing work (see...) Figure 5 and Figure 6 This includes the following steps A1 to A3:

[0081] A1. The thread cutting begins. The main shaft rotates. When the main shaft rotates at an angle β1, the moving blade 3 extends. β1 is between 145° and 166°, preferably 145°. At this time, the needle 12 is below the needle plate 10 of the sewing machine and rises, and the thread take-up lever rises. When the main shaft rotates at an angle β2, the moving blade 3 reaches the thread-cutting extension position and stops. β2 is between 195° and 216°, preferably 195°. See [reference needed]. Figure 6That is, when the main shaft rotates at an angle of β1 to β2, it is the extension section of the moving blade 3. During the extension of the moving blade 3, it passes through the loop formed by the top thread 13 when hooking the shuttle 1 of the sewing machine. Only after the moving blade 3 passes through the loop of the top thread 13 can the subsequent return cut of the moving blade 3 cut the top thread 13. The loop formed when the shuttle 1 hooks the top thread 13 is a conventional step. During the extension of the moving blade 3, the through hole 3b and the hook 3a of the blade part will successively cross the axis of the needle 12. This is so that after the top thread 13 wraps around the bobbin case of the shuttle 1 and crosses the bobbin thread 14, as the take-up lever rises, the bobbin thread 14 and the top thread 13 can enter the hook 3a of the moving blade 3. When the main shaft rotates at an angle of approximately 200°, the needle 12 reaches above the needle plate 10.

[0082] In this step, preferably, when the moving blade 3 starts moving, the adsorption component also starts to suck in air, generating a suction effect at the adsorption port 7a for a duration of S seconds. S can be set to a reasonable value according to the actual situation; preferably, S = 2. The main function of activating the adsorption component at this time is that, in the previous bird's nest stitching stage, the adsorption port 7a may not have sucked up the cut thread ends 13. When the moving blade 3 moves, the cut thread ends are easily carried out. By activating the adsorption component, it can be ensured that the thread ends are sucked up and prevented from being carried out by the moving blade 3.

[0083] A2. The spindle continues to rotate, and moving blade 3 stops at the wire-cutting extension position. See below. Figure 7 As shown, at this time, the take-up lever rises, and the bobbin thread 14 and the top thread 13 enter the hook 3a of the moving blade 3. When the main shaft rotates at an angle β3 (285°–306°, preferably 285°), the moving blade 3 begins to return to its initial position, and the hook 3a catches the bobbin thread 14 and the top thread 13. At this time, the needle 12 is above the needle plate 10 and rises. When the main shaft is between β2 and β3, the moving blade 3 remains stationary. See [reference needed]. Figure 6 That is, when the main shaft rotates at an angle of β2 to β3, it is the holding section of the moving cutter 3. Wait for the face line 13 to complete a series of actions such as passing around the shuttle case, until the bottom line 14 also enters the hook part 3a of the moving cutter 3.

[0084] A3. When the spindle rotation angle is β4, β4 is 339°~360°, preferably 340°. The take-up lever rises to position Z1, which is close to or at the highest position of the take-up lever. The moving blade 3 returns to its initial position and stops. Since the take-up lever rises, it will pull the top thread 13. At this time, the length change of the top thread 13 is not significant. The needle 12 is above the needle plate 10. At this time, the top thread 13 and the bottom thread 14 can be cut. The top thread 13 and the bottom thread 14 will be pulled to the position of the moving blade edge 3c. The moving blade edge 3c engages with the fixed blade edge 2a on the fixed blade 2. The top thread 13 and the bottom thread 14 are cut. The bottom thread end of the bottom thread 14 connected to the bobbin is clamped between the bottom thread holding part of the moving blade 3 and the bottom thread holding spring 6, and remains stable. The top thread 13 connected to the needle 12 may be clamped by the top thread clamping part 3d and the thread clamping piece 8 of the moving blade 3, or it may not be clamped. See the description for the state at this time. Figure 11 As shown. When the top thread 13 is clamped, the user pulls the fabric out and it is released from the clamp, leaving only the bottom thread 14 clamped. The height difference H1 between position Z1 and the lowest point of the thread take-up lever is 0.95H to H, where H is the height difference between the highest and lowest points of the thread take-up lever.

[0085] The thread trimming is now complete, and the sewing machine awaits its next sewing session.

[0086] B. Seam opening work, see Figure 8 and Figure 9 This includes the following steps:

[0087] B1. See the condition before seam opening. Figure 11 As shown, the seam begins to open, the main shaft rotates, and the adsorption assembly starts to draw air, creating a negative pressure suction at the adsorption port 7a, generating a suction effect. The moving blade 3 moves from its initial position to the seam opening extension position. Preferably, the moving blade 3 begins its extension movement when the main shaft rotation angle is 0°.

[0088] In this embodiment, preferably, before the main shaft rotates, the electronic control system controls the needle pitch adjustment stepper motor to adjust the needle pitch to A, which is smaller than the needle pitch during normal sewing. The preferred range for needle pitch A is 0.5 to 1 mm. Reducing the needle pitch serves two purposes: First, in a double-needle sewing machine, the needle 12 oscillates back and forth during needle feeding. If the oscillation amplitude is too large and exceeds the size of the through hole 3b on the moving blade 3, it will collide with the moving blade 3, creating a hazard. Therefore, reducing the needle pitch ensures safety. Second, it prevents the stitches from easily unraveling during subsequent stitching, thus effectively preventing the bottom thread 13 from unraveling when the first few stitches are denser.

[0089] B2. When the spindle rotates at an angle of θ1, the moving cutter 3 reaches the starting and extending position and stops. At this time, the through hole 3b of the cutter is directly below the needle 12. See [link / reference]. Figure 11As shown, the needle 12 is located on the needle plate 10, where θ1 ranges from 15° to 25°, preferably 20°. That is, the spindle rotation angle range of 0° to θ1 corresponds to the cutting stage of the moving blade 3. (See [reference]). Figure 9 .

[0090] B3. The main shaft continues to rotate, the moving blade 3 remains in the starting and extending position, the needle 12 descends until it passes through the through hole 3b in the blade section, and the top thread 13 on both sides of the hole of the needle 12 enters the through hole 3b in the blade section to form an incomplete loop of thread. The rotary shuttle 1 of the sewing machine moves, and the shuttle tip passes through and hooks the loop of top thread 13. See below. Figure 12 As shown; then the needle 12 rises above the needle plate 10 and above the feed dog 11, the take-up lever rises and pulls the thread 13 to disengage it from the rotary hook 1, the thread end of the thread 13 passes through the through hole 3b of the cutter and remains below the moving cutter 3, see Figure 13 As shown, during the upward movement of the thread take-up lever, a portion of the top thread 1313 will be pulled out from below the feed dog 11.

[0091] B4. When the take-up lever rises to position Z2, which is close to the highest position, the moving blade 3 begins to retract towards its initial position. At this time, the take-up lever requires the maximum amount of thread, and the pulling force on the top thread 13 has disappeared. The excess thread end of the top thread 13 remains in the through hole 3b of the moving blade 3. At this time, the needle 12 is located above the needle plate 10. Preferably, when the take-up lever rises to position Z2, the spindle rotation angle is θ2, and θ2 ranges from 335° to 345°, preferably 340°. See also Figure 9 That is, the rotation angles θ1 to θ2 of the main shaft correspond to the holding section of the moving blade 3 in the starting and extending position. Among them, the height difference H2 between position Z2 and the lowest position of the thread take-up rod is 0.95H to H, where H is the height difference between the highest and lowest positions of the thread take-up rod.

[0092] B5. During the retraction process, the through hole 3b of the moving blade 3 pulls the thread 13 within it. The moving blade 3 reaches its initial position and remains stationary. The moving blade edge 3c engages with the fixed blade edge 2a, cutting the thread 13, or shortening a portion of the thread 13. The cut-off segment of thread 13 is sucked away by the suction port 7a. The thread 13 connected to the needle 12 is clamped by the thread clamping part 3d and the thread clamping piece 8. (See below) Figure 14 and Figure 15 As shown. At this point, the end of the top thread 13 is effectively shortened, and the portion of the top thread 13 connected to the needle 12 is still held in place and will not fall off. At the same time, the bottom thread 14 is either sucked in by the suction port 7a or held by the bottom thread holding spring 6 and the bottom thread holding part of the moving blade 3, maintaining stability.

[0093] During the retraction of the moving tool 3, the spindle continues to rotate. Preferably, when the moving tool 3 reaches the initial position, the spindle rotation angle is 360° (i.e., 0°). See [link / reference]. Figure 9As shown, the return phase of the moving tool 3 corresponds to the spindle rotation angle θ2~360°.

[0094] B6. The main shaft continues to rotate for two cycles, forming two stitches. In this embodiment, the stitch length of these two stitches is A. Since the length of the top thread 13 has been shortened, the possibility of the bottom thread 14 and the top thread 13 intertwining is reduced. If the large stitch length of normal sewing continues, the stitch at the beginning of the seam will easily come undone. The denser stitches in the first few stitches of the beginning of the seam effectively prevent the bottom and top threads 13 from coming undone. Since the bottom thread 14 and the top thread 13 have definite positions, and the top thread 13 is clamped, the hook 1 will form a complete loop when the second stitch is made. Thus, the top thread 13 can cross the bottom thread 14 when the second stitch is made, forming a lockstitch. This effectively prevents the problem of the stitch coming undone at the beginning of the seam. The small stitch length of the two stitches also prevents the stitch from coming undone. After completing the above actions, the bird's nest function is basically completed. For the starting stitch of the bird's nest, see [link to example]. Figure 17 As shown, at this time the main shaft rotates another cycle, the needle 12 moves downward and then upward until the take-up lever is at its highest point.

[0095] B5. The adsorption component stops sucking air. At this point, the process of creating the bird's nest function is complete.

[0096] The above-mentioned steps in the operation control method of the present invention can be implemented by a logic control program set in the electronic control system of the sewing machine. The electronic control system controls the automatic operation of the moving blade drive unit and the suction component of the thread cutting mechanism, as well as the main shaft motor that drives the main shaft to rotate, to achieve fully automatic thread cutting and sewing.

[0097] The operation control method of the present invention can be used in a double-needle sewing machine, in which a thread-cutting mechanism works in conjunction with a needle 12 and a rotary hook 1, and of course it can also be used in a single-needle sewing machine.

[0098] In the thread-cutting mechanism of this embodiment, the power source for the moving blade drive unit is a thread-cutting motor 17, preferably a stepper motor, which drives the moving blade 3 through a suitable intermediate transmission component. When using the thread-cutting motor 17, the precise operation of the thread-cutting motor 17 can be easily controlled by the electronic control system, facilitating the coordination between the moving blade 3 and the needle 12 and the thread take-up lever to achieve the aforementioned thread-cutting and sewing operations.

[0099] See Figure 1 , Figure 2 and Figure 3In the thread-cutting mechanism of this embodiment, as a preferred design, the moving blade 3 moves linearly along the front-back direction of the sewing machine, and the blade through-hole 3b is a strip-shaped hole extending along the front-back direction. When used in a double-needle sewing machine, since the needle bar of the double-needle sewing machine swings back and forth during sewing, the length of the blade through-hole 3b along the front-back direction is determined according to the working stitch length of the sewing machine and the size of the back-back swing range of the needle 12, so as to ensure that when the first stitch is started, the needle 12 can smoothly enter the blade through-hole 3b, and the needle 12 will not hit the moving blade 3 when swinging back and forth.

[0100] See Figure 2 In the thread-cutting mechanism of this embodiment, as a preferred design, it also includes a moving knife guide frame 16 and a moving knife drive slider 15. The moving knife guide frame 16 is fixed on the shuttle frame of the sewing machine. The moving knife guide frame 16 is provided with a guide groove extending in the front-back direction. The moving knife drive slider 15 is installed in the guide groove. The moving knife 3 is fixed on the moving knife drive slider 15. The moving knife drive part is connected to the moving knife drive slider 15 and can drive the moving knife drive slider 15 to move linearly back and forth in the guide groove to realize the knife extension and retraction.

[0101] See Figure 4 In the wire cutting mechanism of this embodiment, as a preferred design, the moving blade 3 is also provided with a guide groove 3e connecting the hook part 3a and the through hole 3b of the blade part. When the moving blade 3 retracts from the wire cutting extension position to the initial position, the hook part 3a can hook the top wire 13 and the bottom wire 14 and move towards the fixed blade 2. The top wire 13 and the bottom wire 14 enter the guide groove 3e, which plays a role in stabilizing the position of the top wire 13 and the bottom wire 14, so that the top wire 13 and the bottom wire 14 can be smoothly cut at the blade edge 3c of the moving blade.

[0102] See Figure 2 and Figure 4 In the wire cutting mechanism of this embodiment, as a preferred design, the bottom thread retaining spring 6 is an elastic clamping piece. When the moving blade 3 moves, the bottom thread retaining spring 6 can make good contact with the lower side of the moving blade 3, ensuring that the bottom thread 14 can be stably clamped. The wire cutting mechanism also includes a fixedly installed support spring plate 9, which is supported on the lower side of the bottom thread retaining spring 6 and can provide an upward elastic force to the bottom thread retaining spring 6, further ensuring that the bottom thread retaining spring 6 and the moving blade 3 can stably clamp the bottom thread 14.

[0103] See Figure 2 and Figure 4 In the wire-cutting mechanism of this embodiment, as a preferred design, the adsorption assembly includes a straw 7 and a suction component (not shown in the drawings). The end of the straw 7 forms an adsorption port 7a. The straw 7 is located below the supporting spring plate 9 and is inclined, while the adsorption port 7a is horizontal. The straw 7 is connected to the suction component. By suctioning air through the suction component, a negative pressure is generated at the adsorption port 7a, thereby achieving the adsorption effect.

[0104] See Figure 2 , Figure 3 and Figure 16 In the thread cutting mechanism of this embodiment, the thread clamping plate 8 is a thin sheet structure with elasticity, located below the needle plate 10 and fixed to the needle plate 10 by screws. An adjusting bolt 10a is screwed onto the needle plate 10. The adjusting bolt 10a is located above the thread clamping plate 8, and its lower end is used to abut against the thread clamping plate 8. The degree of deformation of the thread clamping plate 8 can be adjusted by adjusting the adjusting bolt 10a, that is, adjusting the contact pressure between the thread clamping plate 8 and the face thread clamping part 3d of the moving blade 3, thereby adjusting the clamping force on the face thread 13.

[0105] The operation control method of the present invention has the following beneficial effects:

[0106] 1. By setting up a thread-cutting mechanism consisting of a bottom thread retaining spring 6, a thread clamping plate 8, an adsorption assembly, and a moving blade 3 with a through hole 3b, the movement of the moving blade 3 is controllable. Through the reasonable cooperation of the thread-cutting mechanism, the main shaft, the needle 12, and the needle bar, the thread-cutting work after normal sewing can be smoothly realized. The thread-cutting work prepares for the subsequent starting of sewing. Through the reasonable cooperation of the thread-cutting mechanism, the main shaft, the needle 12, and the thread take-up lever, a small bird's nest function can be achieved during the starting of sewing. The bird's nest on the sewing fabric after starting is small in size and more aesthetically pleasing, solving the problem that the original large bird's nest would cause discomfort upon contact with the human body, thus meeting the user's needs.

[0107] 2. It can effectively improve the sewing thread rate. Since the thread 13 after the sewing is held by the thread clamping plate 8, the thread 13 will not be pulled out of the sewing material due to the movement of the thread take-up lever or the needle 12, which will cause the sewing thread to come loose.

[0108] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0109] 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 method for controlling the operation of a sewing machine to sew a small bird's nest, wherein the sewing machine needle (12) and thread take-up lever are driven by a main shaft, and the needle (12) and thread take-up lever complete a reciprocating motion when the main shaft rotates one revolution. When the thread take-up lever is at its highest position, the shaft rotation angle is 0°, and the needle (12) is located above the needle plate (10) of the sewing machine and moves downward. The sewing machine has a thread cutting mechanism and an electronic control system. The thread cutting mechanism includes a fixed blade (2), a moving blade (3), and a moving blade drive unit. The electronic control system is connected to the moving blade drive unit. The moving blade (3) is provided with a hook (3a). The method is characterized in that: The moving blade (3) is also provided with a blade through hole (3b), and one side edge of the upper end of the blade through hole (3b) forms the blade edge (3c) of the moving blade. The wire cutting mechanism also includes a bottom thread retaining spring (6), a wire clamping plate (8), and an adsorption assembly. The bottom thread retaining spring (6) is located below the moving blade (3), and the lower side of the moving blade (3) is provided with a bottom thread retaining part. The adsorption assembly is provided with an adsorption port (7a) and can generate a suction effect at the adsorption port (7a). The wire clamping plate (8) is located on the upper side of the moving blade (3), and the moving blade (3) is provided with a top thread clamping part (3d). The electronic control system is connected to the adsorption assembly for control. The operation control method includes the following working process: A. The thread trimming process after normal sewing includes the following steps: A1. Start cutting the thread. The main shaft rotates. When the rotation angle of the main shaft is β1, the moving knife (3) starts to extend. β1 is 145°~166°. The needle (12) is located below the needle plate (10) of the sewing machine and rises. The thread take-up lever rises. When the rotation angle of the main shaft is β2, the moving knife (3) reaches the thread cutting extension position and stops. β2 is 195°~216°. During the extension process, the moving knife (3) passes through the loop formed when the shuttle (1) of the sewing machine hooks the thread (13). The through hole (3b) of the knife part and the hook part (3a) pass over the axis of the needle (12) one after the other. A2. The main shaft continues to rotate, the moving blade (3) stops at the thread cutting extension position, the take-up lever rises, the bottom thread (14) and the top thread (13) enter the hook (3a) of the moving blade (3), when the rotation angle of the main shaft is β3, β3 is 285°~306°, the moving blade (3) begins to return to the initial position, the hook (3a) hooks the bottom thread (14) and the top thread (13), the needle (12) is above the needle plate (10) and rises; A3. When the spindle rotation angle is β4, β4 is 339°~360°. When the thread take-up lever rises to position Z1, position Z1 is close to or at the highest position of the thread take-up lever. The moving knife (3) returns to the initial position and stops. The needle (12) is above the needle plate (10). The moving knife blade (3c) meshes with the fixed knife blade (2a) on the fixed knife (2). The top thread (13) and bottom thread (14) are cut off. The bottom thread (14) end is clamped between the bottom thread holding part of the moving knife (3) and the bottom thread holding spring (6). B. The seam-starting process includes the following steps: B1. Start the seam, the main shaft rotates, the adsorption component starts to suck air, and a suction effect is generated at the adsorption port (7a). The moving knife (3) moves from the initial position to the seam extension position. B2. The moving knife (3) reaches the starting and extending position and stops. The through hole (3b) of the knife is located directly below the needle (12), and the needle (12) is located above the needle plate (10). B3. The main shaft continues to rotate, the moving knife (3) remains in the starting and extending position, the needle (12) descends to pass through the through hole (3b) of the knife part, the thread (13) on both sides of the hole of the needle (12) enters the through hole (3b) of the knife part to form an incomplete loop, the rotary hook (1) of the sewing machine moves, the shuttle tip passes through and hooks the loop of thread (13); then the needle (12) rises above the needle plate (10), the take-up lever rises and pulls the thread (13) to disengage it from the rotary hook (1), the thread (13) passes through the through hole (3b) of the knife part. B4. When the thread take-up lever rises to position Z2, position Z2 is close to or at the highest position of the thread take-up lever. The excess thread end of the top thread (13) remains in the through hole (3b) of the blade part of the moving knife (3). The needle (12) is located above the needle plate (10). The moving knife (3) begins to retract to the initial position. B5. During the retraction process, the through hole (3b) of the moving knife (3) pulls the face thread (13) inside. The moving knife (3) reaches the initial position and remains stationary. The moving knife blade (3c) engages with the fixed knife blade (2a) to cut the face thread (13). The cut-off small section of face thread (13) is sucked away by the suction port (7a). The face thread (13) connected to the needle (12) is clamped by the face thread clamping part (3d) and the clamping piece (8). The bottom thread is sucked by the suction port (7a) or clamped by the bottom thread holding spring (6) and the bottom thread holding part. B6. The spindle continues to rotate for two cycles, forming two stitches; B7. The adsorption component stops working.

2. The operation control method according to claim 1, characterized in that: In step A1, when the moving blade (3) starts to move, the adsorption component starts to work to draw air, and a suction effect is generated at the adsorption port (7a) for a duration of S seconds.

3. The operation control method according to claim 2, characterized in that: In step A1, S=2.

4. The operation control method according to claim 1, characterized in that: In step A1, β1 is 145° and β2 is 195°; in step A2, β3 is 285°; and in step A3, β4 is 340°.

5. The operation control method according to claim 1, characterized in that: In step A3, position Z1 is located at the highest position of the line-lifting rod.

6. The operation control method according to claim 1, characterized in that: In step B1, before the main shaft rotates, the stitch length is first adjusted to A, which is smaller than the stitch length when the sewing machine is sewing normally. In step B4, two stitches are formed according to the stitch length A, and then the stitch length is adjusted to the stitch length required for normal sewing.

7. The operation control method according to claim 6, characterized in that: In step B1, the needle spacing A ranges from 0.5 to 1 mm.

8. The operation control method according to claim 1, characterized in that: In step B1, when the spindle rotation angle is 0°, the moving cutter (3) begins to move from the initial position to the starting position.

9. The operation control method according to claim 1, characterized in that: In step B2, when the spindle rotates at an angle of θ1, the moving cutter (3) reaches the starting and extending position of the seam and stops. The value of θ1 is in the range of 15°~25°.

10. The operation control method according to claim 1, characterized in that: In step B5, when the spindle rotation angle is θ2, the moving tool (3) reaches the initial position and stops. The value of θ2 is in the range of 335°~345°.

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