Operation control method for sewing machine to sew small bird nests

Abstract

The invention relates to an operation control method for sewing a small nest by a sewing machine, which comprises the following working processes: a thread trimming working process: a main shaft rotates, a movable cutter extends out when the rotation angle is beta1, and the movable cutter reaches a thread trimming extending position when the rotation angle is beta2; when the main shaft rotates, the movable cutter stops at the trimming extension position, the take-up lever ascends, and the rotating angle of the main shaft is beta 3, the movable cutter begins to reset to hook the bottom thread and the upper thread; when the rotation angle of the main shaft is beta 4, the take-up lever ascends to the position Z1, the movable cutter returns to the initial position, the upper thread and the bottom thread are cut off, and the bottom thread is clamped; in the seam starting working process, the main shaft rotates, the suction opening generates a suction effect, and the movable cutter extends out; the movable cutter reaches a seam starting extending position; the movable cutter is fixed, the machine needle descends to penetrate through the cutter part through hole and then ascends, and the take-up lever ascends; when the take-up lever ascends to the position Z2, the movable cutter retreats; the movable cutter reaches the initial position and keeps still, the upper thread is cut off, and the upper thread is clamped; continuously rotating the main shaft for two cycles to form two stitches; and the adsorption assembly stops.

Description

Technical Field

[0001] The invention relates to the technical field of sewing machines, and in particular to an operation control method for a sewing machine to realize sewing a small bird's nest. Background Art

[0002] The conventional thread trimming mechanism in a double-needle sewing machine is driven by an electromagnet in cooperation with a thread trimming cam to drive the moving knife to move forward and backward to achieve the thread trimming function. In this design, the movement stroke of the moving knife is fixed, and the trajectory of the thread trimming cam directly determines the movement stroke of the moving knife. Figure 1 As shown, the thread trimming electromagnet is fixed on the bottom plate. When the thread trimming electromagnet is energized and attracted, the ball of the main rod assembly will be stuck in the groove of the thread trimming cam. As the thread trimming cam rotates, the main rod assembly and the intermediate transmission mechanism composed of multiple transmission parts will drive the movable knife driving slider to slide back and forth. The movable knife driving slider drives the movable knife fixed thereon to move back and forth. Therefore, the movable knife also moves back and forth under the drive of the thread trimming cam. After engaging with the fixed knife, the suture thread can be cut.

[0003] The principle of the existing thread cutting mechanism cutting the thread is as follows: Figure 1 and attached Figure 4 As shown, the movable knife has a hook and a movable knife blade. When the movable knife starts to return and prepare to cut the thread, the upper thread and the lower thread have been hooked by the hook on the movable knife. At this time, the upper thread and the lower thread are still a complete thread. When the thread above the movable knife blade of the movable knife contacts and engages with the fixed knife blade on the fixed knife, the sewing thread will be cut. After the thread is cut, the upper thread and the lower thread on the outside of the fixed knife blade are connected to the sewing material, the upper thread on the inside is connected to the needle, the lower thread is connected to the bobbin, and the lower thread is also clamped by the lower thread clamp under the passive knife to prevent it from falling off.

[0004] After the existing double-needle sewing machine cuts the thread, the upper thread ends are relatively long. Therefore, when sewing next time, the longer upper thread ends are easy to intertwine and entangle with the bottom thread or itself on the back of the sewing material, forming a raised thread ball, which is commonly known as a "bird's nest". The bird's nest is not only ugly in appearance, but if this part of the bird's nest is located close to the human body, it will cause skin itching and discomfort. Therefore, how to remove the bird's nest is often a pain point and difficulty in the clothing industry, especially in double-needle sewing machines, which have a rotary shuttle on the left and right. The existing single-needle flat sewing machine can not be used on double needles. At the same time, due to the narrow left and right space in the double-needle sewing machine, the installation space is also extremely limited. Summary of the invention

[0005] In view of the shortcomings of the prior art mentioned above, the technical problem to be solved by the present invention is to provide an operation control method for a small bird's nest at the start of sewing on a sewing machine, by effectively cooperating among a thread cutting mechanism, a thread jumper rod and a machine needle, a small bird's nest can be realized at the start of sewing.

[0006] To achieve the above-mentioned purpose, the present invention provides an operation control method for a sewing machine to realize a small bird's nest sewing, wherein the needle and the thread take-up lever of the sewing machine are driven by a main shaft, and when the main shaft rotates one circle, the needle and the thread take-up lever complete an up and down reciprocating motion, when the thread take-up lever is at the highest position, the shaft rotation angle is 0°, and the needle is located above the needle plate of the sewing machine and moves downward, the sewing machine has a thread trimming mechanism and an electric control system, the thread trimming mechanism includes a fixed knife, a moving knife and a moving knife driving part, the electric control system is connected to the moving knife driving part for control, and the moving knife is provided with a thread trimming mechanism. The movable knife has a hook portion, and a knife through hole is also provided on the movable knife. The edge of one side of the upper end opening of the knife through hole constitutes the movable knife blade. The thread trimming mechanism also includes a bottom line holding spring, a thread clamping piece and an adsorption component. The bottom line holding spring is arranged below the movable knife, and a bottom line holding part is arranged on the lower side of the movable knife. The adsorption component is provided with an adsorption port and can generate a suction effect at the adsorption port. The thread clamping piece is arranged on the upper side of the movable knife, and a surface thread clamping part is arranged on the movable knife. The electric control system is connected to the adsorption component control; the operation control method includes the following working process:

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

[0008] A1. Start trimming the thread, the spindle rotates, and when the spindle rotates at an angle of β1, the movable knife begins to extend, β1 is 145° to 166°, the needle is located under the needle plate of the sewing machine and rises, and the thread take-up lever rises; when the spindle rotates at an angle of β2, the movable knife reaches the thread trimming extension position and stops, β2 is 195° to 216°, and during the extension process of the movable knife, a thread loop is formed when the surface thread is hooked by the rotary hook of the sewing machine, and the through hole of the knife and the hook successively cross the axis of the needle;

[0009] A2. The main shaft continues to rotate, the movable knife stops at the thread trimming extension position, the thread take-up lever rises, the bottom thread and the surface thread enter the hook of the movable knife, when the main shaft rotates to β3, β3 is 285°~306°, the movable knife starts to reset to the initial position, the hook hooks the bottom thread and the surface thread, and the needle is located above the needle plate and rises;

[0010] A3. When the main shaft rotates at an angle of β4, β4 is 339° to 360°, and the thread take-up lever rises to position Z1, position Z1 is close to or located at the highest position of the thread take-up lever, the movable knife returns to the initial position and stops, the movable knife blade engages with the fixed knife blade on the fixed knife, the upper thread and the lower thread are cut, and the lower thread end is clamped between the lower thread holding part of the movable knife and the lower thread holding spring;

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

[0012] B1. When the seam starts to be formed, the main shaft rotates, the suction component starts to suck air, a suction effect is generated at the suction port, and the movable knife moves from the initial position to the seam starting position;

[0013] B2, the moving knife reaches the sewing start extension position and stops, and the knife through hole is located directly below the needle;

[0014] B3. The main shaft keeps rotating, the movable knife keeps in the extended position for sewing, the needle goes down to pass through the through hole of the knife, the upper threads on both sides of the needle hole enter the through hole of the knife to form an incomplete thread loop, the rotary shuttle of the sewing machine moves, the shuttle tip passes through and hooks the upper thread loop; then the needle rises above the needle plate, the thread take-up lever rises and pulls the upper thread to separate it from the rotary shuttle, and the upper thread passes through the through hole of the knife;

[0015] B4. When the thread take-up lever rises to position Z2, position Z2 is close to or located at the highest position of the thread take-up lever, and the movable knife begins to retreat to the initial position;

[0016] B5. During the retraction process of the movable knife, the through hole of the knife part pulls the upper thread therein, the movable knife reaches the initial position and remains stationary, the blade of the movable knife engages with the blade of the fixed knife to cut the upper thread, the small segment of upper thread cut away is sucked away by the suction port, the upper thread connected to the needle is clamped by the upper thread clamping part and the thread clamping piece, and 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 main shaft continues to rotate for two cycles to form two stitches;

[0018] B7. The adsorption component stops suctioning.

[0019] Furthermore, in the step A1, when the movable knife starts to move, the adsorption component starts to suck air, generating a suction effect at the adsorption port, which lasts for S seconds.

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

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

[0022] Further, in step A3, position Z1 is located at the highest position of the thread take-up lever.

[0023] Furthermore, in the step B1, before the main shaft rotates, the stitch length is first adjusted to A, where A is smaller than the stitch length of the sewing machine during normal sewing; in the 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 distance A has a numerical range of 0.5 to 1 mm.

[0025] Furthermore, in the step B1, when the main shaft rotation angle is 0°, the movable knife starts to move from the initial position to the seam start extension position.

[0026] Furthermore, in step B2, when the main shaft rotates at an angle of θ1, the movable knife reaches the seam start extension position and stops, and the value range of θ1 is 15° to 25°.

[0027] Preferably, in step B5, the movable knife reaches the initial position and stops when the spindle rotates at an angle of θ2, and the value range of θ2 is 335° to 345°.

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

[0029] 1. By setting up a thread trimming mechanism composed of a bottom thread holding spring, a thread clamp, an adsorption component and a moving knife with a knife through hole, the moving knife movement is controllable. Through the reasonable coordination of the thread trimming mechanism, the main shaft, the machine needle and the needle bar, the thread trimming work after normal sewing can be smoothly realized. The thread trimming work also prepares for the subsequent sewing. Through the reasonable coordination of the thread trimming mechanism, the main shaft, the machine needle and the thread take-up rod, the bird's nest function can be realized when sewing. The bird's nest on the sewing material after sewing is small in size and more beautiful in appearance, which solves the problem that the original bird's nest is large in size and causes discomfort after contact with the human body, and meets the user's use needs. ,

[0030] 2. It can effectively improve the thread rate at the start of sewing. Since the thread is clamped by the thread clamp before sewing, the surface thread will not be pulled out of the sewing material due to the movement of the thread take-up rod or the needle, causing the thread to come off at the start of sewing. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of an existing thread trimming mechanism.

[0032] Figure 2 It is a structural schematic diagram of the thread cutting mechanism in the present invention.

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

[0034] Figure 4 It is a structural schematic diagram of the movable knife in the present invention.

[0035] Figure 5 It is a schematic flow chart of the thread cutting working process in the present invention.

[0036] Figure 6 It is a schematic diagram of the correspondence between the main shaft rotation angle and the moving knife action during the thread trimming process of the present invention.

[0037] Figure 7 It is a working schematic diagram when the movable knife is located at the thread cutting extending position during the thread cutting working process of the present invention.

[0038] Figure 8It is a schematic flow chart of the seam starting process in the present invention.

[0039] Fig. 9 It is a schematic diagram of the correspondence between the main shaft rotation angle and the moving knife action during the seam starting process of the present invention.

[0040] Fig.10 It is a schematic diagram of a first state of the sewing machine during the thread trimming process of the present invention.

[0041] Fig.11 It is a schematic diagram of the second state of the sewing machine during the thread trimming process of the present invention.

[0042] Fig.12 It is a schematic diagram of the third state of the sewing machine during the thread trimming process of the present invention.

[0043] Fig.13 It is a schematic diagram of the fourth state of the sewing machine during the thread trimming operation in the present invention.

[0044] Fig.14 It is a schematic diagram of the fifth state of the sewing machine during the thread trimming process of the present invention.

[0045] Fig.15 It is a schematic diagram of the sixth state of the sewing machine during the thread trimming operation in the present invention.

[0046] Fig.16 It is a working schematic diagram when the upper thread is cut during the thread trimming process of the present invention.

[0047] Fig.17 It is a schematic diagram of the seam starter stitch in the present invention.

[0048] Description of Figure Numbers

[0049] 1 Hook

[0050] 2 Fixed knife

[0051] 2a Fixed blade

[0052] 3. Cutting

[0053] 3a Hook

[0054] 3b Knife through hole

[0055] 3c Moving knife blade

[0056] 3d upper thread clamping part

[0057] 3e Boot Slot

[0058] 4 Thread trimming cam

[0059] 5. Thread trimming electromagnet

[0060] 6 Bottom thread holding spring

[0061] 7. Straw

[0062] 7a Adsorption port

[0063] 8 Wire clamp

[0064] 9 Support spring

[0065] 10 Needle plate

[0066] 10a Adjusting bolt

[0067] 11 Feed dog

[0068] 12 Needle

[0069] 13 Noodles

[0070] 14 Bottom Line

[0071] 15 Moving knife drive slide

[0072] 16 Moving knife guide frame

[0073] 17 Thread trimmer motor

[0074] B Head seam DETAILED DESCRIPTION

[0075] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0076] It should be noted that the structures, proportions, sizes, etc. drawn in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and so on quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0077] See also Figures 1 to 17The present invention provides an operation control method for a sewing machine to realize a small bird's nest. The sewing machine needle 12 and the thread take-up lever are driven by a main shaft, and the main shaft can be driven by a main shaft motor. When the main shaft rotates one circle, the needle 12 and the thread take-up lever complete an up and down reciprocating motion. When the thread take-up lever is at the 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 downward. The sewing machine has a thread trimming mechanism and an electric control system, and the rotation of the main shaft is controlled by the electric control system.

[0078] See also Figure 2 , Figure 3 and Figure 4 The thread trimming mechanism includes a fixed knife 2, a movable knife 3 and a movable knife driving part. The movable knife 3 is provided with a hook part 3a for hooking the upper thread 13 and the lower thread 14 for thread trimming. The electric control system is connected to the movable knife driving part for control, and the movement of the movable knife 3 is driven by the movable knife driving part. In the present invention, the movable knife 3 is also provided with a knife through hole 3b, and one side edge of the upper end opening of the knife through hole 3b constitutes a movable knife blade 3c. The thread trimming mechanism also includes a lower thread holding spring 6, a thread clamping piece 8 and an adsorption component. The lower thread holding spring 6 is arranged below the movable knife 3, and a lower thread holding part is arranged on the lower side of the movable knife 3. The adsorption component is provided with an adsorption port 7a and can generate a suction effect at the adsorption port 7a. The thread clamping piece 8 is arranged on the upper side of the movable knife 3, and a surface thread clamping part 3d is arranged on the movable knife 3. The electric control system is connected to the adsorption component for control.

[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 , including the following steps A1 to A3:

[0081] A1. Start thread trimming, the spindle rotates, and the movable knife 3 starts to extend when the spindle rotates at an angle of β1, β1 is 145° to 166°, and preferably 145°. At this time, the needle 12 is located under the needle plate 10 of the sewing machine and rises, and the thread take-up lever rises; when the spindle rotates at an angle of β2, the movable knife 3 reaches the thread trimming extension position and stops, β2 is 195° to 216°, and preferably 195°, see Figure 6, that is, when the main shaft rotation angle is β1~β2, it is the knife exit section of the movable knife 3. When the movable knife 3 extends, it passes through the hook 1 of the sewing machine to hook the surface thread 13, and the thread loop is formed. Only when the movable knife 3 passes through the thread loop of the surface thread 13, the movable knife 3 can cut the surface thread 13 when it returns. The thread loop formed when the hook 1 hooks the surface thread 13 is an existing conventional step. When the movable knife 3 extends, the knife through hole 3b and the hook 3a will successively cross the axis of the needle 12. This is to ensure that the surface thread 13 will go around the shuttle case of the hook 1 and cross the bottom line 14. After that, as the thread take-up rod rises, the bottom line 14 and the surface thread 13 can enter the hook 3a of the movable knife 3. When the main shaft rotation angle is about 200°, the needle 12 reaches above the needle plate 10.

[0082] In this step, preferably, when the movable knife 3 starts to move, the suction component also starts to suck air, and a suction effect is generated at the suction port 7a, which lasts for S seconds, and S can be set to a reasonable value according to actual conditions, preferably, S = 2. The main function of starting the suction component at this time is: in the previous bird's nest sewing stage, it is possible that the suction port 7a did not suck away the cut surface thread 13 thread ends, and the cut thread ends are easily brought out when the movable knife 3 moves. By turning on the suction component, it can be ensured that the thread ends are sucked away to prevent the passive knife 3 from bringing them out.

[0083] A2. The spindle continues to rotate, and the moving knife 3 stops at the thread trimming extension position. Figure 7 As shown, at this time, the thread take-up lever rises, the bottom thread 14 and the surface thread 13 enter the hook 3a of the movable knife 3, when the main shaft rotates to an angle of β3, β3 is 285° to 306°, preferably 285°, the movable knife 3 begins to reset to the initial position, the hook 3a hooks the bottom thread 14 and the surface thread 13, and the needle 12 is located above the needle plate 10 and rises. When the main shaft is between β2 and β3, the movable knife 3 remains stationary, see Figure 6 , that is, when the main shaft rotation angle is β2-β3, it is the holding section of the movable knife 3. A series of actions such as waiting for the upper thread 13 to bypass the bobbin case are completed until the lower thread 14 also enters the hook portion 3a of the movable knife 3.

[0084] A3. When the main shaft rotates at an angle of β4, β4 is 339° to 360°, and preferably 340°. The thread take-up rod rises to position Z1, which is close to or located at the highest position of the thread take-up rod. The movable knife 3 returns to its initial position and stops. As the thread take-up rod rises, the surface thread 13 is pulled. At this time, the length of the surface thread 13 does not change much, and the needle 12 is located above the needle plate 10. At this time, the surface thread 13 and the bottom thread 14 can be cut. At this time, the surface thread 13 and the bottom thread 14 will be pulled to the position of the movable knife blade 3c. The movable knife blade 3c engages with the fixed knife blade 2a on the fixed knife 2, and the surface thread 13 and the bottom thread 14 are cut. The thread head of the bottom thread 14 connected to the bobbin is clamped between the bottom thread holding part of the movable knife 3 and the bottom thread holding spring 6 to keep it stable. The surface thread 13 connected to the needle 12 may be clamped by the surface thread clamping part 3d and the thread clamping piece 8 of the movable knife 3, or it may not be clamped. See the state at this time. Fig.11 As shown. When the upper thread 13 is clamped, the user takes out the fabric and it is out of the clamp, leaving only the lower thread 14. The height difference H1 between the position Z1 and the lowest position of the thread take-up rod is 0.95H~H, where H is the height difference between the highest position and the lowest position of the thread take-up rod.

[0085] At this point, the thread trimming work is completed and the sewing machine is waiting for the next sewing work.

[0086] B. Seam starting work, see Figure 8 and Fig. 9 , including the following steps:

[0087] B1, the state before seaming, see Fig.11 As shown, the seam starts to start, the main shaft rotates, the suction component starts to suck air, a negative pressure suction force is formed at the suction port 7a, a suction effect is generated, and the movable knife 3 moves from the initial position to the seam start extension position. Preferably, the movable knife 3 starts to move out when the main shaft rotation angle is 0°.

[0088] In this embodiment, preferably, before the spindle rotates, the electronic control system will control the stitch length adjustment stepper motor to first adjust the stitch length to A, which is smaller than the stitch length of the sewing machine during normal sewing. The value range of stitch length A is preferably 0.5 to 1 mm. When the stitch length is reduced, on the one hand, in a double-needle sewing machine, the needle 12 of the needle feed will swing back and forth. If the swing amplitude is too large and exceeds the size of the knife through hole 3b on the movable knife 3, it will collide with the movable knife 3 and cause danger. Therefore, reducing the stitch length can ensure safety. On the other hand, it is to avoid the problem of loosening of the stitches during the subsequent sewing, and to ensure that the stitches of the bottom thread 13 can be effectively prevented from loosening when the first few stitches are encrypted.

[0089] B2. When the main shaft rotates at an angle of θ1, the movable knife 3 reaches the sewing start extension position and stops. At this time, the knife through hole 3b is located directly below the needle 12. Fig.11As shown, the needle 12 is located on the needle plate 10, wherein the value range of θ1 is 15° to 25°, preferably 20°, that is, the spindle rotation angle interval of 0° to θ1 corresponds to the knife-out stage of the moving knife 3, see Fig. 9 .

[0090] B3. The main shaft keeps rotating, the movable knife 3 keeps in the sewing start extended position, the needle 12 descends to pass through the knife through hole 3b, the upper thread 13 on both sides of the hole of the needle 12 enters the knife through hole 3b to form an incomplete thread loop, the rotary shuttle 1 of the sewing machine moves, the shuttle tip passes through and hooks the thread loop of the upper thread 13, see Fig.12 As shown; then the needle 12 rises above the needle plate 10 and above the feed dog 11, the thread take-up lever rises and pulls the upper thread 13 to separate it from the rotary hook 1, and the upper thread 13 passes through the knife through hole 3b and remains below the movable knife 3, see Fig.13 As the thread take-up lever rises, a portion of the upper thread 1313 is brought out from under the feed dog 11.

[0091] B4. When the thread take-up lever rises to position Z2, position Z2 is close to the highest position, and the movable knife 3 begins to retreat to the initial position. At this time, the thread amount required by the thread take-up lever reaches the maximum, and the pulling force on the surface thread 13 has disappeared. The excess thread ends of the surface thread 13 remain in the knife hole 3b of the movable knife 3. At this time, the needle 12 is located above the needle plate 10. Preferably, when the thread take-up lever rises to position Z2, the main shaft rotation angle is θ2, and the value range of θ2 is 335°~345°, and preferably 340°. See Fig. 9 , that is, the main shaft rotation angle θ1~θ2 corresponds to the holding section of the movable knife 3 at the seam start extension position. Among them, the height difference H2 between the position Z2 and the lowest position point of the thread take-up rod is 0.95H~H, and H is the height difference between the highest position point and the lowest position point of the thread take-up rod.

[0092] B5. During the retreat of the movable knife 3, the knife through hole 3b pulls the surface thread 13 therein, and the movable knife 3 reaches the initial position and remains stationary. The movable knife blade 3c engages with the fixed knife blade 2a to cut the surface thread 13, that is, the surface thread 13 is shortened by a part. The cut small section of the surface thread 13 is sucked away by the suction port 7a, and the surface thread 13 connected to the needle 12 is clamped by the surface thread clamping portion 3d and the clamping piece 8, see Fig.14 and Fig.15 As shown. At this point, the thread end of the upper thread 13 is effectively shortened, and the part of the upper thread 13 connected to the needle 12 is still clamped and will not fall off. At the same time, the bottom thread 14 is either sucked by the suction port 7a or clamped by the bottom thread holding spring 6 and the bottom thread holding part of the movable knife 3 to maintain stability.

[0093] The spindle keeps rotating during the retraction of the movable knife 3. Preferably, when the movable knife 3 reaches the initial position, the spindle rotation angle is 360° (ie 0°). Fig. 9As shown, the return stage of the movable knife 3 corresponds to the spindle rotation angle θ2 to 360°.

[0094] B6. The main shaft continues to rotate for two cycles to form two stitches. In the present embodiment, the stitch length of the two stitches is A. Since the length of the upper thread 13 has been shortened, the possibility of the bottom thread 14 and the upper thread 13 being intertwined and entangled with each other is small. If the normal sewing stitch length is continued, the stitches at the beginning of the seam will be easy to loosen. The density of the first few stitches can effectively prevent the stitches of the bottom and upper threads 13 from loosening. Since the bottom thread 14 and the upper thread 13 both have a fixed position, and the upper thread 13 is still clamped, the second stitch will form a complete thread loop when the rotary shuttle 1 is hooked, so that the upper thread 13 can cross the bottom thread 14 during the second stitch, thereby forming a lock stitch, which effectively prevents the problem of unraveling at the beginning of the seam. The small stitch length of the two stitches can also prevent the stitches from loosening. After completing the above actions, the bird's nest function is basically completed. For the stitches at the beginning of the seam when sewing the bird's nest, refer to Fig.17 As shown, at this time, the spindle rotates one more cycle, and the needle 12 moves downward and then rises until the thread take-up lever is at the highest point.

[0095] B5. The adsorption component stops suctioning. Here, the seam-forming process of realizing the bird's nest function is completed.

[0096] The above-mentioned steps in the operation control method of the present invention can be realized by setting a logic control program in the electronic control system of the sewing machine. The electronic control system controls the automatic operation of the moving knife drive part and the adsorption component of the thread trimming mechanism, as well as the spindle motor that drives the spindle to rotate, so as to realize fully automatic thread trimming and sewing.

[0097] The operation control method of the present invention can be used for a double-needle sewing machine, where a thread trimming mechanism cooperates with a needle 12 and a rotary hook 1 to work, and of course it can also be used for a single-needle sewing machine.

[0098] In the thread trimming mechanism of this embodiment, the power source of the movable knife driving part is a thread trimming motor 17, which is preferably a stepping motor, and drives the movable knife 3 to move through a suitable intermediate transmission component. When the thread trimming motor 17 is used, the electronic control system can conveniently control the precise movement of the thread trimming motor 17, and conveniently control the cooperation between the movable knife 3 and the needle 12 and the thread take-up rod to achieve the above-mentioned thread trimming and sewing work.

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

[0100] See also Figure 2 In the thread trimming mechanism of the present embodiment, as a preferred design, it also includes a movable knife guide frame 16 and a movable knife driving slider 15. The movable knife guide frame 16 is fixed on the shuttle frame of the sewing machine. The movable knife guide frame 16 is provided with a guide groove extending in the front-to-back direction. The movable knife driving slider 15 is installed in the guide groove. The movable knife 3 is fixed on the movable knife driving slider 15. The movable knife driving part is connected to the movable knife driving slider 15, and can drive the movable knife driving slider 15 to move linearly forward and backward in the guide groove to realize the knife out and retract.

[0101] See also Figure 4 In the thread trimming mechanism of the present embodiment, as a preferred design, a guide groove 3e connecting the hook portion 3a and the knife portion through hole 3b is further provided on the movable knife 3. When the movable knife 3 retreats from the thread trimming extended position to the initial position, the hook portion 3a can hook the upper thread 13 and the lower thread 14 and move toward the fixed knife 2. The upper thread 13 and the lower thread 14 enter the guide groove 3e, which plays a role in stabilizing the position of the upper thread 13 and the lower thread 14, so that the upper thread 13 and the lower thread 14 can be smoothly cut at the movable knife blade 3c.

[0102] See also Figure 2 and Figure 4 In the thread trimming mechanism of this embodiment, as a preferred design, the bottom line holding spring 6 is an elastic clip. When the movable knife 3 moves, the bottom line holding spring 6 can be well in contact with the lower side of the movable knife 3 to ensure that the bottom line 14 can be stably clamped. The thread trimming mechanism also includes a fixedly installed support spring sheet 9, which is supported on the lower side of the bottom line holding spring 6 and can provide an upward elastic force to the bottom line holding spring 6, further ensuring that the bottom line holding spring 6 and the movable knife 3 can stably clamp the bottom line 14.

[0103] See also Figure 2 and Figure 4 In the thread trimming mechanism of this embodiment, as a preferred design, the adsorption assembly includes a suction pipe 7 and a suction component (not shown in the drawings), the end of the suction pipe 7 constitutes a suction port 7a, the suction pipe 7 is located below the support spring sheet 9, and is tilted, and the suction port 7a is in a horizontal state. The suction pipe 7 is connected to the suction component, and the suction port 7a generates negative pressure through the suction of the suction component, thereby achieving adsorption.

[0104] See also Figure 2 , Figure 3 and Fig.16 In the thread trimming mechanism of the present embodiment, the thread clamping piece 8 is an elastic thin sheet structure, which is located below the needle plate 10 and fixed to the needle plate 10 by screws. An adjusting bolt 10a is screwed on the needle plate 10. The adjusting bolt 10a is located above the thread clamping piece 8, and its lower end is used to abut against the thread clamping piece 8. The deformation degree of the thread clamping piece 8 can be adjusted by adjusting the bolt 10a, that is, the contact pressure between the thread clamping piece 8 and the surface thread clamping portion 3d of the movable knife 3 can be adjusted, thereby adjusting the thread clamping force on the surface thread 13.

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

[0106] 1. By setting a thread trimming mechanism composed of a bottom thread holding spring 6, a thread clamping piece 8, an adsorption component and a movable knife 3 with a knife through hole 3b, the movement of the movable knife 3 is controllable. Through the reasonable coordination of the thread trimming mechanism, the main shaft, the machine needle 12 and the needle bar, the thread trimming work after normal sewing can be smoothly realized. The thread trimming work is also ready for the subsequent seaming. Through the reasonable coordination of the thread trimming mechanism, the main shaft, the machine needle 12 and the thread take-up rod, the bird's nest function can be realized when sewing. The bird's nest on the sewing material after sewing is small in size and more beautiful in appearance, which solves the problem that the original bird's nest is large in size and causes discomfort after contact with the human body, and meets the user's use needs. ,

[0107] 2. It can effectively improve the thread rate at the start of sewing. Since the surface thread 13 is clamped by the thread clamping piece 8 at the start of sewing, the surface thread 13 will not be pulled out from the sewing material due to the movement of the thread take-up rod or the needle 12, causing the thread to come off at the start of sewing.

[0108] In summary, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0109] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for controlling the operation of a sewing machine to realize the sewing of a bird's nest, wherein the needle (12) and the thread take-up lever of the sewing machine are driven by a main shaft, and when the main shaft rotates one circle, the needle (12) and the thread take-up lever complete an up and down reciprocating motion, when the thread take-up lever is at the 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 trimming mechanism and an electric control system, the thread trimming mechanism comprises a fixed knife (2), a movable knife (3) and a movable knife driving part, the electric control system is connected to the movable knife driving part, and the movable knife (3) is provided with a hook part (3a), characterized in that: The movable knife (3) is also provided with a knife through hole (3b), and one side edge of the upper end opening of the knife through hole (3b) constitutes a movable knife blade (3c). The thread trimming mechanism also includes a bottom line holding spring (6), a thread clamping piece (8) and an adsorption assembly. The bottom line holding spring (6) is arranged below the movable knife (3), and a bottom line holding portion is arranged on the lower side of the movable knife (3). The adsorption assembly is provided with an adsorption port (7a) and can generate a suction effect at the adsorption port (7a). The thread clamping piece (8) is arranged on the upper side of the movable knife (3), and a surface thread clamping portion (3d) is provided on the movable knife (3). The electric 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 work includes the following steps: A1. Thread trimming begins, the main shaft rotates, and when the main shaft rotates at an angle of β1, the movable knife (3) begins to extend, β1 being 145° to 166°, the machine needle (12) is located 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 of β2, the movable knife (3) reaches the thread trimming extension position and stops, β2 being 195° to 216°, and during the extension process, the movable knife (3) passes through the hook (13) of the sewing machine's rotary shuttle (1) to form a thread loop, and the knife portion through hole (3b) and the hook portion (3a) successively cross the axis of the machine needle (12); A2. The main shaft continues to rotate, the movable knife (3) stops at the thread trimming extension position, the thread take-up lever rises, the bottom thread (14) and the top thread (13) enter the hook portion (3a) of the movable knife (3), and when the main shaft rotates at an angle of β3, β3 is 285° to 306°, the movable knife (3) begins to return to the initial position, the hook portion (3a) hooks the bottom thread (14) and the top thread (13), and the needle (12) is located above the needle plate (10) and rises; A3, when the main shaft rotates at an angle of β4, β4 is 339° to 360°, when the thread take-up lever rises to position Z1, position Z1 is close to or located at the highest position of the thread take-up lever, the movable knife (3) returns to the initial position and stops, the movable knife blade (3c) engages with the fixed knife blade (2a) on the fixed knife (2), the upper thread (13) and the lower thread (14) are cut, and the thread end of the lower thread (14) is clamped between the lower thread holding portion of the movable knife (3) and the lower thread holding spring (6); B. The seam starting process includes the following steps: B1, the seam starts to be formed, the main shaft rotates, the suction component starts to suck air, a suction effect is generated at the suction port (7a), and the movable knife (3) moves from the initial position to the seam starting extension position; B2, the movable knife (3) reaches the seam start extension position and stops, and the knife through hole (3b) is located directly below the needle (12); B3, the main shaft keeps rotating, the movable knife (3) keeps in the sewing start extended position, the needle (12) descends to pass through the knife through hole (3b), the upper thread (13) on both sides of the hole of the needle (12) enters into the knife through hole (3b) to form an incomplete thread loop, the rotary shuttle (1) of the sewing machine moves, the shuttle tip passes through and hooks the thread loop of the upper thread (13); then the needle (12) rises to above the needle plate (10), the thread take-up lever rises and pulls the upper thread (13) to make it detach from the rotary shuttle (1), and the upper thread (13) passes through the knife through hole (3b); B4, when the thread take-up lever rises to position Z2, position Z2 is close to or located at the highest position of the thread take-up lever, and the movable knife (3) starts to retreat to the initial position; B5. When the movable knife (3) is retreating, the knife through hole (3b) pulls the surface thread (13) therein, the movable knife (3) reaches the initial position and remains stationary, the movable knife blade (3c) engages with the fixed knife blade (2a), and the surface thread (13) is cut off. The small section of surface thread (13) cut off is sucked away by the suction port (7a), the surface thread (13) connected to the needle (12) is clamped by the surface thread clamping portion (3d) and the thread clamping piece (8), and the bottom thread is sucked by the suction port (7a) or clamped by the bottom thread holding spring (6) and the bottom thread holding portion; B6, the main shaft continues to rotate for two cycles to form two stitches; B7. The adsorption component stops suctioning.

2. The operation control method according to claim 1, characterized in that: In the step A1, when the movable knife (3) starts to move, the adsorption component starts to suck air, generating a suction effect at the adsorption port (7a) for a duration of S seconds.

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

4. The operation control method according to claim 1, characterized in that: In the step A1, β1 is 145° and β2 is 195°; in the step A2, β3 is 285°; in the 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 thread take-up lever.

6. The operation control method according to claim 1, characterized in that: In the step B1, before the main shaft rotates, the stitch length is first adjusted to A, where A is smaller than the stitch length of the sewing machine during normal sewing; in the 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 the step B1, the needle distance A has a value ranging from 0.5 to 1 mm.

8. The operation control method according to claim 1, characterized in that: In the step B1, when the main shaft rotation angle is 0°, the movable knife (3) starts to move from the initial position to the seam start extension position.

9. The operation control method according to claim 1, characterized in that: In the step B2, when the main shaft rotates at an angle of θ1, the movable knife (3) reaches the seam start extension position and stops, and the value range of θ1 is 15° to 25°.

10. The operation control method according to claim 1, characterized in that: In the step B5, when the main shaft rotates at an angle of θ2, the movable knife (3) reaches the initial position and stops, and the value range of θ2 is 335° to 345°.

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