A sewing thread trimming control method

Abstract

The application provides a sewing thread trimming control method, which is configured with a double-action knife thread trimming mechanism and a control system in a sewing machine. When starting the thread trimming, the main thread trimming knife and the auxiliary thread trimming knife are controlled to move towards the needle in a first direction to trim the thread end captured by the main thread trimming knife right below the needle. The main thread trimming knife is first controlled to move in the first direction to a position where the main blade edge on the main thread trimming knife is above the position right below the needle, and then the main thread trimming knife is immediately controlled to retreat in a second direction to a position where the main blade edge on the main thread trimming knife is right below the needle, thus completing the thread trimming. Then, the main thread trimming knife continues to retreat in the second direction to reset, thereby avoiding the situation that the main thread trimming knife stays at a certain position and the main blade edge remains right below the needle, and the time consumed by the main thread trimming driving source in driving the main thread trimming knife to move in the first direction and then retreat in the second direction to the initial position to complete the trimming of the thread end is shortened, and the thread trimming during the starting of the sewing machine is completed at the normal sewing speed of the sewing machine.

Description

Technical Field

[0001] This invention relates to the field of sewing machine technology, and in particular to a sewing thread cutting control method. Background Technology

[0002] After each sewing session, a section of thread remains on one side of the needle, forming the starting thread for the next stitch. This starting thread creates a bird's nest-like pattern on the garment during subsequent sewing, affecting the overall quality of the garment. To ensure garment quality, this starting thread must be manually trimmed, increasing labor intensity and reducing production efficiency.

[0003] To address the aforementioned issues, most sewing machines on the market are equipped with a thread-cutting mechanism. This mechanism cuts off the remaining thread end on the needle side when starting to sew, and cuts off the bobbin thread and top thread at the end of the sewing process. This prevents bird nests during the initial stitch and automatically cuts the thread after sewing, improving the automation level of the machine, enhancing sewing efficiency, and ensuring the quality of the garments.

[0004] For example, Chinese invention patent application No. 202311289444.7 discloses a single-acting knife anti-bird nest thread-cutting mechanism, which is equipped with a fixed blade and a rotatable movable blade. The movable blade has different strokes at the beginning and end of sewing, so as to cut the starting thread at the beginning of sewing and cut the top and bottom threads at the end of sewing. However, this thread-cutting mechanism is a single-acting knife structure, which cannot cut the thread directly below the needle. The thread-cutting position where the fixed blade and the movable blade engage is on one side below the needle, that is, the thread drawn from the sewing machine needle plate has an angle, resulting in a longer residual thread on the fabric after cutting.

[0005] For example, the double-acting thread-cutting mechanism disclosed in Chinese invention patent application number 202411329869.0 is equipped with two rotatable thread-cutting blades, namely thread-cutting blade one and thread-cutting blade two. During thread cutting at the start of sewing (to prevent nesting) and automatic thread cutting after sewing, thread-cutting blade one and thread-cutting blade two can engage and cut the thread directly below the needle, achieving the effect of cutting short thread ends. The control method for thread cutting at the start of sewing is usually as follows: first, thread-cutting blade one is driven to capture the starting thread end of the top thread; then, thread-cutting blade one retracts and stops on one side of the needle, and thread-cutting blade two also stops on the same side of the needle, waiting for the sewing machine to complete the set number of stitches N; then, thread-cutting blade one extends first, its cutting edge stopping directly below the needle, and then waits for thread-cutting blade two to extend, and the two engage and cut the thread directly below the needle; finally, thread-cutting blade two and thread-cutting blade one retract sequentially. However, after the set number of stitches N is completed, the thread-cutting blade needs to remain in the position where its upper edge is directly below the needle after cutting the thread, and then rotate back. This causes the motor that drives the thread-cutting blade to stop and restart. Since it takes time for the motor to stop and restart, the thread-cutting blade rotates slowly and takes a long time after cutting the thread. Therefore, it is necessary to control the sewing machine speed to reduce the needle's downward movement speed when sewing the N+1th stitch. Otherwise, it is easy for the needle to pierce the thread-cutting blade when sewing the N+1th stitch due to the needle moving down too quickly and the thread-cutting blade not retracting completely, resulting in needle breakage and damage to the thread-cutting blade. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a sewing thread cutting control method to increase the rotation speed of the main thread cutter when cutting the thread to prevent bird nests at the start of the sewing process, so as to complete the thread cutting at the start of the sewing process at the normal sewing speed of the sewing machine.

[0007] To achieve the above objectives, the present invention provides a sewing thread cutting control method, comprising a double-acting thread cutting mechanism and a control system in a sewing machine. The double-acting thread cutting mechanism includes a main thread cutting blade and an auxiliary thread cutting blade, both movably disposed on the outer periphery of the rotary hook in the sewing machine; a main thread cutting drive source driven by the main thread cutting blade; and an auxiliary thread cutting drive source driven by the auxiliary thread cutting blade. Both the main and auxiliary thread cutting drive sources are communicatively connected to the control system. The main thread cutting blade has a main blade edge and a through-hole starting stitch hook groove, and the auxiliary thread cutting blade has an auxiliary blade edge. The sewing thread cutting control method includes a starting stitch anti-bird's nest thread cutting control method.

[0008] The method for controlling thread cutting during seam opening to prevent bird nests includes the following steps:

[0009] S1. Before the sewing machine starts the first stitch, or during the process of the sewing machine starting the first stitch and the needle moving down, the control system controls the main blade thread cutting drive source to move, causing the main thread cutting blade to move along the first direction, so that the starting stitch hook groove moves to directly below the needle.

[0010] S2. When the sewing machine starts the first stitch, the needle moves down and the needle, carrying the top thread, passes through the starting stitch hook groove. Under the action of the rotary hook, the starting thread end on one side of the needle is brought to the bottom of the main thread cutter.

[0011] S3. When the sewing machine starts the first stitch, the needle moves upward. After the needle moves upward from the main thread cutter, the control system controls the main thread cutter drive source to reverse the action, driving the main thread cutter to retract to the outer periphery of the needle in a second direction opposite to the first direction. The main blade edge and the auxiliary blade edge are not engaged, and the starting thread end is kept in the starting stitch hook groove.

[0012] S4. The sewing machine continues sewing until the set number of stitches is reached.

[0013] S5. The control system controls the main blade thread-cutting drive source to move, causing the main blade to move in the first direction, so that the blade edge passes directly below the needle. Then, the control system controls the main blade thread-cutting drive source to move in the opposite direction, causing the main blade to retract in the second direction, so that the blade edge moves to a position directly below or near the needle. At the same time, the control system controls the auxiliary blade thread-cutting drive source to move, causing the auxiliary blade to move in the first direction, so that the blade edge moves to a position directly below or near the needle. Then, the blade edges of the main blade and the auxiliary blade engage and cut the starting thread at a position directly below or near the needle.

[0014] S6. The control system controls the main cutter wire cutting drive source and the auxiliary cutter wire cutting drive source to move in opposite directions. The main cutter wire cutting drive source drives the main cutter wire cutting blade to retract along the second direction to the outer periphery of the needle, and the auxiliary cutter wire cutting drive source drives the auxiliary cutter wire cutting blade to retract along the second direction to the outer periphery of the needle.

[0015] Furthermore, the double-acting wire cutting mechanism also includes a fixed suction pipe and an air suction device connected to the suction pipe. The suction pipe and the auxiliary wire cutting knife are arranged on the same side of the needle. The suction pipe is aligned with the outer surface of the main wire cutting knife facing away from the rotary hook. The air suction device is communicatively connected to the control system.

[0016] In step S5, the control system controls the suction device to create a negative pressure at the inlet of the suction pipe. At the same time, when the main blade passes directly below the needle in the first direction, the end of the starting thread comes out of the starting stitch hook groove and is sucked into the suction pipe. The suction of the suction pipe keeps the starting thread taut.

[0017] Furthermore, the dual-action wire cutting mechanism also includes a fixedly installed wire pressing plate, which is distributed on the outer side of the auxiliary wire cutting blade facing away from the main wire cutting blade; the wire pressing plate is fixedly provided with a plate pressing part, and the surface of the main wire cutting blade is provided with a blade pressing part;

[0018] In step S3, when the main cutter thread-cutting drive source drives the main cutter thread-cutting blade to retract in the second direction, a thread-clamping seam is formed between the plate thread-pressing part and the blade thread-pressing part, and the starting thread end is clamped in the thread-clamping seam.

[0019] Furthermore, the plate pressing part is distributed on the outer side of the back of the main cutting blade facing the rotary hook, and the blade pressing part protrudes outward from the outer surface of the back of the main cutting blade facing the rotary hook.

[0020] Furthermore, the plate pressing part is distributed on the inner side of the main cutting blade facing the rotary hook, and the blade pressing part is provided on the inner surface of the main cutting blade facing the rotary hook.

[0021] Furthermore, the pressing plate includes a plate fixing part and a plate body part integrally bent and extended from the plate fixing part. The plate fixing part is fixed to the sewing machine base plate. The plate body part is distributed on the inner side of the main thread cutter facing the rotary hook. The pressing plate part extends integrally from the edge of the plate body part along the rotary hook axis and is distributed on the same side of the plate body part as the starting stitch hook groove.

[0022] Furthermore, the pressure plate also includes a wire-blocking part, which is located on the inner side of the main wire cutter facing the rotary hook;

[0023] In step S6, when the control system controls the main cutter wire-cutting drive source to reverse and cause the main cutter wire-cutting blade to retract along the second direction to the outer periphery of the needle, the thread-separating groove is distributed on the side directly above the thread-blocking part and is blocked by the thread-blocking part.

[0024] Furthermore, in step S4, the sewing machine is in a small stitch distance sewing mode.

[0025] Furthermore, the dual-action thread-cutting mechanism also includes a main-blade thread-cutting transmission assembly connected between the main-blade thread-cutting drive source and the main-blade thread-cutting blade. The main-blade thread-cutting transmission assembly includes a first thread-cutting crank, a first thread-cutting connecting rod, a first thread-cutting shaft rotatably supported in the sewing machine base plate, a second thread-cutting crank and a third thread-cutting crank both fixed on the first thread-cutting shaft, a second thread-cutting connecting rod, and a main-blade holder rotatably mounted in the sewing machine base plate. The first thread-cutting crank is connected to and driven to rotate by the main-blade thread-cutting drive source. The two ends of the first thread-cutting connecting rod are respectively hinged to the first thread-cutting crank and the second thread-cutting crank, and the two ends of the second thread-cutting connecting rod are respectively hinged to the third thread-cutting crank and the main-blade holder.

[0026] Furthermore, the double-acting thread-cutting mechanism also includes an auxiliary thread-cutting transmission assembly connected between the auxiliary thread-cutting drive source and the auxiliary thread-cutting blade. The auxiliary thread-cutting transmission assembly includes a fourth thread-cutting crank, a third thread-cutting connecting rod, a second thread-cutting shaft rotatably supported in the sewing machine base plate, a fifth thread-cutting crank and a sixth thread-cutting crank both fixed on the second thread-cutting shaft, the fourth thread-cutting connecting rod, and an auxiliary blade holder rotatably mounted in the sewing machine base plate. The fourth thread-cutting crank is connected to and driven to rotate by the auxiliary thread-cutting drive source. The two ends of the third thread-cutting connecting rod are respectively hinged to the fourth thread-cutting crank and the fifth thread-cutting crank, and the two ends of the fourth thread-cutting connecting rod are respectively hinged to the sixth thread-cutting crank and the auxiliary blade holder.

[0027] Furthermore, the end of the main thread cutter is provided with a blade tip, and the main thread cutter is provided with a thread-separating hook groove and a surface thread-separating groove on both sides along the axis of the rotary hook. The outer peripheral edge of the main thread cutter has a surface thread sliding surface connected between the blade tip and the groove of the thread-separating hook groove, and a surface thread sliding surface connected between the blade tip and the groove of the surface thread-separating groove.

[0028] The sewing thread cutting control method further includes a post-sewing automatic thread cutting control method, which includes the following steps:

[0029] A1. After the last stitch of the sewing machine needle moves upward from the sewing machine needle plate, the control system controls the main blade thread cutting drive source to move, causing the main thread cutting blade to move in the first direction, so that the tip of the blade is inserted into the top thread loop. Then, part of the top thread and the bottom thread slide into the thread separating groove along the top and bottom thread sliding surface, and the other part of the top thread slides into the top thread separating groove along the top thread sliding surface.

[0030] A2. The control system controls the main blade cutting drive source to reverse, causing the main blade to retract along the second direction, so that the main blade edge moves to a position directly below or near the needle. At the same time, the control system controls the auxiliary blade cutting drive source to move along the first direction, so that the auxiliary blade edge moves to a position directly below or near the needle. Then, the main blade edge and the auxiliary blade edge engage and cut the top and bottom threads at a position directly below or near the needle.

[0031] A3. The control system controls the main cutter's thread-cutting drive source to continue its reverse action, driving the main cutter to retract along the second direction to the outer periphery of the needle; at the same time, the control system controls the auxiliary cutter's thread-cutting drive source to reverse its action, driving the auxiliary cutter to retract along the second direction to the outer periphery of the needle.

[0032] Furthermore, in steps S5 and A2, during the process of the feed dog rising in the sewing machine, the control system controls the auxiliary cutter thread drive source to move, causing the auxiliary cutter thread to move along the first direction.

[0033] As described above, the sewing thread cutting control method of the present invention has the following beneficial effects:

[0034] In this application, when cutting the thread at the start of a stitch to prevent bird nests, the main thread cutter and the auxiliary thread cutter are controlled to move towards the needle in a first direction to cut the starting thread captured by the main thread cutter at a position directly below or adjacent to the needle. First, the main thread cutter is controlled to move in the first direction until its main blade passes directly below the needle. Then, immediately, the main thread cutter is controlled to retract in a second direction until its main blade is directly below or adjacent to the needle, completing the thread cutting. Afterward, the main thread cutter... The thread cutter continues to retract and reset along the second direction, thus avoiding the main thread cutter from remaining in a certain position with its blade directly below the needle. This shortens the time required for the main thread cutter to move along the first direction and then retract to its initial position to cut the starting thread, achieving rapid reset of the main thread cutter after the initial thread cut. This reduces the impact on the sewing machine's starting speed, allowing the initial thread cut to be completed at normal sewing speeds. Therefore, this application achieves the effect of cutting short thread ends during the initial thread cut without significantly affecting the sewing machine's starting speed. It reliably completes the initial thread cut at high sewing speeds, preventing the needle from hitting the main thread cutter during the initial thread cut, effectively preventing needle breakage, blade damage, and other adverse phenomena, thus improving the initial sewing experience and sewing quality. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the sewing machine in Embodiment 1 of this application, which is equipped with a double-acting thread-cutting mechanism.

[0036] Figure 2 This is a schematic diagram of the structure of Embodiment 1 of the double-acting wire-cutting mechanism in this application.

[0037] Figure 3 for Figure 2 A schematic diagram showing the connection between the main wire cutting drive source and the main wire cutting blade.

[0038] Figure 4 for Figure 2 A schematic diagram showing the connection between the auxiliary wire cutting drive source and the auxiliary wire cutting blade.

[0039] Figure 5 for Figure 2 A schematic diagram of the main wire shearing blade.

[0040] Figure 6 for Figure 2 A schematic diagram of the structure of the medium-voltage line plate.

[0041] Figures 7a to 7c This is a schematic diagram illustrating the process of cutting the thread to prevent the bird's nest from being sewn, as described in the embodiment of the double-acting knife thread-cutting mechanism of this application.

[0042] Figure 8 This is a schematic diagram of the main thread-cutting blade during automatic thread cutting after sewing, as shown in Embodiment 1 of the dual-action thread-cutting mechanism of this application.

[0043] Figure 9a This is a schematic diagram of the double-acting knife thread-cutting mechanism of this application cutting the bottom and top threads directly below the needle.

[0044] Figure 9b This is a schematic diagram of the double-acting knife thread cutting mechanism of this application cutting the bottom thread and the top thread at a position directly below the needle.

[0045] Figure 10 This is a schematic diagram of the main thread cutter retracting to the anti-snagging position along the second direction during automatic thread cutting in Embodiment 1 of the double-action thread cutting mechanism of this application.

[0046] Figure 11 This is a schematic diagram of the first embodiment of the double-acting wire-cutting mechanism of this application in its initial position.

[0047] Figure 12 for Figure 11 A schematic diagram showing the connection between the main wire cutter and the wire pressing plate.

[0048] Figure 13 for Figure 12 A structural diagram from another perspective.

[0049] Figure 14 This is a schematic diagram of the structure of Embodiment 2 of the double-acting knife thread cutting mechanism in this application when clamping the starting thread end.

[0050] Figure 15 This is a schematic diagram of the structure of Embodiment 2 of the double-acting knife thread cutting mechanism in this application when cutting the starting thread.

[0051] Figure 16 This is a control block diagram in this application.

[0052] Figure 17 This is a flowchart of the thread-cutting control method for preventing bird nests during the seam-starting process in this application.

[0053] Component labeling: Control system 10, main thread cutter 20, main blade edge 21, seam starter groove 22, blade tip 23, thread separating groove 24, top thread separating groove 25, top and bottom thread sliding surface 26, top thread sliding surface 27, post-seam thread cutter receiving part 28, seam starter thread cutter receiving part 29, auxiliary thread cutter 30, auxiliary blade edge 31, main thread cutter drive source 40, auxiliary thread cutter drive source 50, first thread cutter crank 61, first thread cutter connecting rod 62, first thread cutter shaft 63, second thread cutter crank Handle 64, third thread cutting crank 65, second thread cutting connecting rod 66, main blade holder 67, fourth thread cutting crank 71, third thread cutting connecting rod 72, second thread cutting shaft 73, fifth thread cutting crank 74, sixth thread cutting crank 75, fourth thread cutting connecting rod 76, auxiliary blade holder 77, suction pipe 80, pressure plate 90, plate pressure part 91, plate fixing part 92, plate main body part 93, thread blocking part 94, rotary hook 110, sewing machine base plate 120, lower shaft 130, needle bar 140, needle 150. Detailed Implementation

[0054] 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.

[0055] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and objectives of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and 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.

[0056] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0057] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0058] This application relates to the field of sewing machine technology, and in particular to a sewing thread cutting control method for such sewing machine.

[0059] The sewing machine is a flatbed sewing machine. For example... Figure 1 and Figure 16 As shown, the sewing machine mainly includes a control system 10, a sewing machine housing and a sewing machine base plate 120, both fixedly mounted, a main shaft rotatably supported in the sewing machine housing, a main motor installed in the sewing machine housing and driving the main shaft, a lower shaft 130 rotatably supported in the sewing machine base plate 120 and connected to the main shaft, a rotary hook 110 installed at the end of the lower shaft 130, a needle bar 140 movably supported in the sewing machine housing and connected to the main shaft, and a needle 150 installed at the lower end of the needle bar 140. The main motor, pedals, control panel, sensors, and other components in the sewing machine are all communicatively connected to the control system 10. During normal sewing, the needle bar 140 drives the needle 150 to move up and down reciprocally, and the lower shaft 130 drives the rotary hook 110 to rotate. The needle 150 and the rotary hook 110 work together to interweave the top and bottom threads to form a stitch, completing the sewing.

[0060] For ease of description, in the following embodiments, the directions are defined as follows: the axial direction of the rotary hook 110 in the sewing machine is defined as the left-right direction; the horizontal radial direction of the rotary hook 110 in the sewing machine is defined as the front-back direction; and the vertical diameter of the rotary hook 110 in the sewing machine is defined as the up-down direction. Simultaneously, the front direction is the direction in which the fabric moves when the sewing machine is in operation. Based on this, the rotary hook 110 is fixed to the left end of the lower shaft 130, and the upper end of the needle bar 140 is connected to the left end of the main shaft via a transmission connection.

[0061] Furthermore, to achieve the sewing thread cutting control method involved in this application, such as Figure 1 and Figure 16 As shown, the sewing machine is also equipped with a double-action thread-cutting mechanism. For example... Figure 1 and Figure 2As shown, Embodiment 1 of the double-acting thread-cutting mechanism includes a main thread-cutting blade 20 and an auxiliary thread-cutting blade 30, both movably arranged on the outer periphery of the rotary hook 110 in the sewing machine; a main thread-cutting drive source 40 connected to the main thread-cutting blade 20; and an auxiliary thread-cutting drive source 50 connected to the auxiliary thread-cutting blade 30. The movement of the main thread-cutting blade 20 and the auxiliary thread-cutting blade 30 can both be rotation around the rotary hook 110 or translation. In this embodiment, both the main thread-cutting blade 20 and the auxiliary thread-cutting blade 30... The main thread cutter 20 and the auxiliary thread cutter 30 are rotatably arranged on the outer periphery of the rotary hook 110. They are positioned sequentially in a direction away from the rotary hook 110 in the sewing machine; that is, the main thread cutter 20 is on the outer side of the rotary hook 110, and the auxiliary thread cutter 30 is on the outer side of the main thread cutter 20. The main thread cutter 20 is driven to rotate by the main thread cutter drive source 40, and the auxiliary thread cutter 30 is driven to rotate by the auxiliary thread cutter drive source 50. Both the main thread cutter drive source 40 and the auxiliary thread cutter drive source 50 are communicatively connected to the control system 10. In the initial state of the double-acting thread cutting mechanism embodiment one, the main thread cutter 20 and the auxiliary thread cutter 30 are each in their initial positions. At this time, as... Figure 11 As shown, the main thread cutter 20 and the auxiliary thread cutter 30 are both located on the rear side of the needle 150.

[0062] Furthermore, such as Figure 2 and Figure 5 As shown, the main thread cutter 20 is provided with a main blade edge 21 and a starting thread hook groove 22 distributed on the rear side of the main blade edge 21. The starting thread hook groove 22 penetrates the main thread cutter 20 along the thickness direction of the main thread cutter 20 and allows the needle 150 to pass through. In addition, the front end of the main thread cutter 20 is provided with a blade tip 23, the left side of the main thread cutter 20 is provided with a thread separating hook groove 24, and the right side of the main thread cutter 20 is provided with a top thread separating groove 25. The opening of the hook groove extends to the left edge of the blade body to allow the bottom thread and top thread to enter the hook groove from the left side of the blade body. The opening of the top thread separating groove 25 extends to the right edge of the blade body to allow the top thread to enter the top thread separating groove 25 from the right side of the blade body. Furthermore, the outer peripheral edge of the main wire cutter 20 has a bottom surface sliding surface 26 connecting the groove between the blade tip 23 and the wire parting groove 24, and a top surface sliding surface 27 connecting the groove between the blade tip 23 and the top surface parting groove 25. The bottom surface sliding surface 26 is part of the left edge of the main body of the blade, and the top surface sliding surface 27 is part of the right edge of the main body of the blade. The auxiliary wire cutter 30 has an auxiliary blade edge 31 at its front end.

[0063] This application relates to sewing thread cutting control methods, including a method for controlling thread cutting at the start of a sewing process to prevent bird nests and a method for automatic thread cutting after sewing. For example... Figure 17 As shown, the method for controlling thread cutting to prevent bird nests during seam preparation includes the following steps.

[0064] S1. Before the sewing machine begins its first stitch, or during the downward movement of the needle 150 during the first stitch, the control system 10 controls the main thread-cutting drive source 40 to operate, driving the main thread-cutting blade 20 to rotate counterclockwise forward in the first direction, causing the thread-cutting groove 22 to rotate forward to directly below the needle 150. Figure 7a As shown.

[0065] S2, the sewing machine moves the needle down 150 degrees for the first stitch, as shown. Figure 7a As shown, the needle 150, carrying the top thread, passes downward through the starting stitch hook groove 22. Under the action of the rotary hook 110, the starting thread end on one side of the needle 150 is brought to the bottom of the main thread cutter 20. The starting thread end on one side of the needle 150 is a section of top thread formed on one side of the needle 150 after the previous sewing was finished and the thread was cut.

[0066] S3. The sewing machine begins its first stitch with the needle 150 moving upwards. After the needle 150 moves upwards from the main thread cutter 20, the control system 10 controls the main thread cutter drive source 40 to reverse its movement, driving the main thread cutter 20 to rotate clockwise backwards in a second direction, which is the opposite of the first direction. The main thread cutter 20 retracts to the rear of the needle 150, but the main blade edge 21 and the auxiliary blade edge 31 do not engage. This process causes a portion of the starting thread to be pulled upwards, but the starting thread remains in the starting stitch hook groove 22. This portion of the starting thread pulled upwards rests on the upper surface of the main thread cutter 20, such as... Figure 7b As shown.

[0067] S4. The sewing machine continues sewing until the set number of stitches is reached, such as continuing to sew 2 stitches, 3 stitches, or other numbers of stitches, so that the top thread and bottom thread interweave to form a stitch on the fabric; during this process, the main blade 21 and the auxiliary blade 31 always remain in the non-interlocking state as in step S3 above, so that the starting thread end is not cut off.

[0068] S5. After the set number of stitches is reached, the control system 10 controls the main thread-cutting drive source 40 to operate, causing the main thread-cutting blade 20 to rotate counterclockwise forward in the first direction. Specifically, the forward rotation of the main thread-cutting blade 20 causes its main blade edge 21 to move forward in the first direction past directly below the needle 150, i.e., the main blade edge 21 is positioned in front of the needle 150. Subsequently, the control system 10 controls the main thread-cutting drive source 40 to immediately reverse its operation, causing the main thread-cutting blade 20 to rotate clockwise backward in the second direction, so that the main blade edge 21 rotates backward to directly below the needle 150. At the same time, the control system 10 controls the auxiliary thread-cutting drive source 50 to operate, causing the auxiliary thread-cutting blade 30 to rotate counterclockwise forward in the first direction, so that the auxiliary blade edge 31 rotates forward to directly below the needle 150. Thus, as... Figure 7cAs shown, the main cutting edge 21 and the auxiliary cutting edge 31 engage directly below the needle 150 and cut the starting thread. Alternatively, after the main cutting edge 21 moves forward past directly below the needle 150, the control system 10 controls the main cutting edge drive 40 to immediately reverse its movement. The retracted position of the main cutting edge 20 causes the main cutting edge 21 to rotate backward to a position behind the needle 150 but close to directly below it. At the same time, when the control system 10 controls the auxiliary cutting edge drive 50 to move, the forward position of the auxiliary cutting edge 30 causes the auxiliary cutting edge 31 to rotate forward to a position behind the needle 150 but close to directly below it. Thus, the main cutting edge 21 and the auxiliary cutting edge 31 engage at a position behind the needle 150 but close to directly below it and cut the starting thread.

[0069] S6. Subsequently, the control system 10 controls the main thread-cutting drive source 40 and the auxiliary thread-cutting drive source 50 to move in opposite directions. The main thread-cutting drive source 40 drives the main thread-cutting blade 20 to rotate clockwise in the second direction and retract to the outer periphery of the needle 150, returning the main thread-cutting blade 20 to its initial position. The auxiliary thread-cutting drive source 50 drives the auxiliary thread-cutting blade 30 to rotate clockwise in the second direction and retract to the outer periphery of the needle 150, returning the auxiliary thread-cutting blade 30 to its initial position. In this way, neither the main thread-cutting blade 20 nor the auxiliary thread-cutting blade 30 has any solid parts distributed directly below the needle 150, and neither will interfere with the up-and-down movement of the needle 150, allowing the sewing machine to sew normally afterwards.

[0070] Obviously, firstly, this application automatically cuts off the starting thread when sewing, preventing bird's nests from forming on the fabric and improving sewing quality. Secondly, by cutting the starting thread directly below or near the needle 150, the remaining thread on the fabric is very short, reliably achieving the effect of cutting short thread ends and avoiding subsequent manual trimming of residual thread on the fabric. In particular, when cutting the thread at the start of the stitch to prevent bird nests, this application controls the main thread cutter 20 and the auxiliary thread cutter 30 to rotate counterclockwise forward toward the needle 150 in the first direction to cut the starting thread captured by the main thread cutter 20 at a position directly below or adjacent to the needle 150. First, the main thread cutter 20 is controlled to rotate counterclockwise forward in the first direction until its main blade edge 21 passes directly below or adjacent to the needle 150. Then, immediately, the main thread cutter 20 is controlled to rotate clockwise backward in the second direction until its main blade edge 21 is positioned at or adjacent to the needle 150. The thread cutter 20 is positioned directly below the needle 150, completing the initial stitch cutting. Afterward, the main thread cutter 20 continues to rotate clockwise in the second direction to return to its original position. This avoids the main thread cutter 20 remaining in a certain position, keeping the main blade edge 21 directly below the needle 150. This shortens the time required for the main thread cutter drive source 40 to drive the main thread cutter 20 to rotate forward and then backward to return to its initial position to cut the starting thread. This achieves rapid reset of the main thread cutter 20 after the initial stitch cutting, reducing the impact on the sewing machine's starting speed and enabling the initial stitch cutting to be completed at the normal sewing speed of the sewing machine. Therefore, this application can achieve the effect of cutting short thread ends to prevent bird nests during the start-up stitching process, without significantly affecting the start-up speed of the sewing machine. It can reliably complete the start-up stitching to prevent bird nests during the high-speed start-up stitching process, and avoid the needle 150 from hitting the main thread cutter 20 during the start-up stitching to prevent bird nests. This effectively prevents defects such as broken needles and damaged blades, and improves the start-up stitching experience and sewing quality.

[0071] Furthermore, the automatic thread trimming control method after sewing includes the following steps.

[0072] A1. After the last stitch is sewn, the needle 150 moves upward from the sewing machine needle plate, the control system 10 controls the main thread-cutting drive source 40 to operate, driving the main thread-cutting blade 20 to rotate counterclockwise forward in the first direction, such as... Figure 8 As shown, when the tip 23 of the main thread cutter 20 is inserted into the top thread loop, the left half of the top thread loop and the bottom thread slide along the bottom thread sliding surface 26 into the thread splitting groove 24, and the right half of the top thread loop slides along the top thread sliding surface 27 into the top thread splitting groove 25.

[0073] A2. The control system 10 controls the main wire-cutting drive source 40 to reverse its movement, driving the main wire-cutting blade 20 to rotate clockwise backward along the second direction, causing the main blade edge 21 to rotate backward to directly below the needle 150; simultaneously, the control system 10 controls the auxiliary wire-cutting drive source 50 to move, driving the auxiliary wire-cutting blade 30 to rotate counterclockwise forward along the first direction, causing the auxiliary blade edge 31 to rotate forward to directly below the needle 150; thus, as... Figure 9a As shown, the main cutting edge 21 and the auxiliary cutting edge 31 engage directly below the needle 150 and cut the starting thread. Alternatively, the control system 10 controls the main cutting edge drive source 40 to reverse, driving the main cutting edge 20 to rotate clockwise backward in the second direction, causing the main cutting edge 21 to rotate backward to a position behind the needle 150, but close to the needle 150 and directly below it; simultaneously, the control system 10 controls the auxiliary cutting edge drive source 50 to rotate forward to a position behind the needle 150, but close to the needle 150 and directly below it; thus, as... Figure 9b As shown, the main cutting edge 21 and the auxiliary cutting edge 31 engage at a position behind the needle 150 but directly below the needle 150, and cut off the starting thread.

[0074] A3. The control system 10 controls the main thread-cutting drive source 40 to continue its reverse action, driving the main thread-cutting blade 20 to rotate clockwise backward along the second direction and retract to the outer periphery of the needle 150 until the main thread-cutting blade 20 retracts to its initial position. Simultaneously, the control system 10 controls the auxiliary thread-cutting drive source 50 to reverse its action, driving the auxiliary thread-cutting blade 30 to rotate clockwise backward along the second direction and retract to the outer periphery of the needle 150 until the auxiliary thread-cutting blade 30 retracts to its initial position. Finally, both the main thread-cutting blade 20 and the auxiliary thread-cutting blade 30 reset to their initial positions. Figure 11 The initial position is shown.

[0075] Furthermore, such as Figure 2 and Figure 3As shown, Embodiment 1 of the dual-action wire cutting mechanism further includes a main blade wire cutting transmission assembly connected between the main blade wire cutting drive source 40 and the main wire cutting blade 20. The main blade wire cutting drive source 40 is a motor, preferably a stepper motor. The main blade thread-cutting drive assembly includes a first thread-cutting crank 61, a first thread-cutting connecting rod 62, a first thread-cutting shaft 63 rotatably supported in the sewing machine base plate 120 and extending laterally, a second thread-cutting crank 64 and a third thread-cutting crank 65 both fixed to the first thread-cutting shaft 63, a second thread-cutting connecting rod 66, and a main blade holder 67 rotatably mounted in the sewing machine base plate 120. The first thread-cutting crank 61 is fixed to the motor shaft of the main blade thread-cutting drive source 40 and is driven to rotate by the main blade thread-cutting drive source 40. The two ends of the first thread-cutting connecting rod 62 are hinged to the first thread-cutting crank 61 and the second thread-cutting crank 64, respectively. The two ends of the second thread-cutting connecting rod 66 are hinged to the third thread-cutting crank 65 and the main blade holder 67, respectively. Thus, the main blade thread-cutting drive source 40 drives the main thread-cutting blade 20 to rotate counterclockwise forward and clockwise backward through the main blade thread-cutting drive assembly.

[0076] Furthermore, such as Figure 2 and Figure 4 As shown, Embodiment 1 of the double-acting thread-cutting mechanism further includes an auxiliary thread-cutting transmission assembly connected between the auxiliary thread-cutting drive source 50 and the auxiliary thread-cutting blade 30. The auxiliary thread-cutting drive source 50 is a motor, preferably a stepper motor. The auxiliary thread-cutting transmission assembly includes a fourth thread-cutting crank 71, a third thread-cutting connecting rod 72, a second thread-cutting shaft 73 rotatably supported in the sewing machine base plate 120 and extending laterally, a fifth thread-cutting crank 74 and a sixth thread-cutting crank 75 both fixed on the second thread-cutting shaft 73, a fourth thread-cutting connecting rod 76, and an auxiliary blade holder 77 rotatably mounted in the sewing machine base plate 120. The fourth thread-cutting crank 71 is connected to and driven to rotate by the auxiliary thread-cutting drive source 50. The two ends of the third thread-cutting connecting rod 72 are hinged to the fourth thread-cutting crank 71 and the fifth thread-cutting crank 74, respectively. The two ends of the fourth thread-cutting connecting rod 76 are hinged to the sixth thread-cutting crank 75 and the auxiliary blade holder 77, respectively. Thus, the auxiliary wire cutting drive source 50 drives the auxiliary wire cutting blade 30 to rotate counterclockwise forward and clockwise backward through the auxiliary wire cutting transmission assembly.

[0077] Furthermore, the main thread cutter 20 is located on the outer periphery of the rotary hook 110, and the auxiliary thread cutter 30 is located on the outer periphery of the main thread cutter 20; thus, the upper surface of the main thread cutter 20 is its outer surface, facing away from the rotary hook 110 and towards the auxiliary thread cutter 30; the lower surface of the main thread cutter 20 is its inner surface, facing towards the rotary hook 110 and away from the auxiliary thread cutter 30. Figure 5As shown, the outer surface of the main thread cutter 20 is also provided with a post-sewing thread-cutting receiving part 28 and a starting-sewing thread-cutting receiving part 29. The post-sewing thread-cutting receiving part 28 is connected between the main blade edge 21 and the parting thread hook groove 24, and the starting-sewing thread-cutting receiving part 29 is connected between the main blade edge 21 and the starting-sewing thread hook groove 22. Both the post-sewing thread-cutting receiving part 28 and the starting-sewing thread-cutting receiving part 29 are recessed structures on the outer surface of the blade body. When cutting the thread at the start of the sewing, the starting thread end led out from the starting-sewing thread hook groove 22 is received in the starting-sewing thread-cutting receiving part 29 and cut at the main blade edge 21. When cutting the thread at the end of sewing, the left half of the top thread and the bottom thread led out from the parting thread hook groove 24 are received in the post-sewing thread-cutting receiving part 28 and cut at the main blade edge 21. In addition, the bottom thread sliding surface 26 extends at an angle as it moves further away from the blade tip 23 and further away from the top thread sliding surface 27, while the top thread sliding surface 27 extends at an angle as it moves further away from the blade tip 23 and further away from the bottom thread sliding surface 26. That is, the bottom thread sliding surface 26 extends at an angle to the left rearward, and the top thread sliding surface 27 extends at an angle to the right rearward, which allows for better thread separation after sewing is completed.

[0078] Furthermore, in step S4, which involves cutting the thread at the start of the stitch to prevent bird nests, the sewing machine is in a small stitch pitch sewing mode, shortening the distance the fabric is moved forward during this process, thus shortening the length of the thread remaining on the fabric after the starting thread is cut. Of course, in other embodiments, in step S4, which involves cutting the thread at the start of the stitch to prevent bird nests, the sewing machine can also be in a regular sewing mode. In addition, in step S5, which involves cutting the thread at the start of the stitch to prevent bird nests, and in step A2, which involves automatic thread cutting after sewing, when the control system 10 detects that the feed dog in the sewing machine is rising, the control system 10 sends a command to the auxiliary thread cutting drive source 50 to drive the auxiliary thread cutting blade 30 to rotate forward in the first direction, thereby avoiding collision between the auxiliary thread cutting blade 30 and the feed dog.

[0079] Furthermore, such as Figure 2 and Figure 16 As shown, the first embodiment of the double-acting thread-cutting mechanism also includes a fixedly installed suction pipe 80 and a suction device connected to the suction pipe 80. The suction pipe 80 and the auxiliary thread-cutting blade 30 are both located behind the needle 150. The suction pipe 80 is aligned with the outer surface of the main thread-cutting blade 20. The suction device is communicatively connected to the control system 10. In step S5, which involves cutting the thread at the start of the stitch to prevent bird nests from falling, the control system 10 controls the suction device to create a negative pressure at the opening of the suction pipe 80. Simultaneously, when the main blade 21 rotates counterclockwise in the first direction and passes directly below the needle 150, the starting thread end is continuously pulled upwards from the starting thread hook groove 22 until the end of the starting thread end is completely pulled upwards from the starting thread hook groove 22. Under the action of the suction pipe 80, the end of the starting thread end is sucked into the suction pipe 80, as... Figure 7cAs shown, the suction of the suction pipe 80 keeps the starting thread taut, achieving a more stable effect of preventing bird nests from cutting the thread when starting to sew short threads.

[0080] Furthermore, such as Figure 2 As shown, Embodiment 1 of the double-acting wire cutting mechanism also includes a fixedly installed wire pressing plate 90, which engages with the main wire cutting blade 20 from below to press the wire. Based on this, as... Figure 6 and Figure 7b As shown, the presser plate 90 includes a plate fixing part 92 and a plate body part 93 integrally bent and extended from the plate fixing part 92. The rear end of the plate fixing part 92 is fixed to the bottom of the sewing machine base plate 120 by screws, thereby fixing the presser plate 90 as a whole to the bottom of the sewing machine base plate 120. The plate body part 93 is distributed on the lower side of the main thread cutter 20 facing the rotary hook 110. The plate presser part 91 extends integrally to the left from the left edge of the plate body part 93 along the axial direction of the rotary hook 110, so the plate presser part 91 is distributed on the inner side of the main thread cutter 20. At the same time, the plate presser part 91 and the starting stitch hook groove 22 are both distributed on the left side of the plate body part 93. The inner surface of the main thread cutter 20 is provided with a blade presser part, which is part of the smooth inner surface of the main thread cutter 20 and does not protrude downward. In step S3, which involves cutting the thread during the start-up stitch to prevent bird nests from being cut, when the main thread-cutting drive source 40 drives the main thread-cutting blade 20 to rotate and retract clockwise in the second direction, although the main thread-cutting blade 20 and the auxiliary thread-cutting blade 30 are not engaged, a thread-clamping seam is formed between the plate-pressing part 91 of the pressing plate 90 and the blade-pressing part of the main thread-cutting blade 20. The starting thread end is clamped in the thread-clamping seam, preventing the starting thread end from accidentally coming off during the start-up stitch setting process.

[0081] In addition, such as Figure 6 As shown, the thread-blocking plate 90 involved in Embodiment 1 of the double-acting knife thread-cutting mechanism is also provided with a thread-blocking part 94. The thread-blocking part 94 is integrally provided at the front end of the plate body part 93, and the plate body part 93 is distributed inside the main thread-cutting knife 20. In step S6 involved in the thread-cutting process of starting the stitch to prevent bird nests, after the starting thread end is cut off, the main knife thread-cutting drive source 40 drives the main thread-cutting knife 20 to retract and reset in the second direction, as shown in the figure. Figures 11 to 13As shown, the thread divider 25 is located directly above the thread stop 94 and is blocked by the thread stop 94. During subsequent normal sewing, the position of the main thread cutter 20 ensures that the thread divider 25 is positioned directly above the thread stop 94 and blocked by it. At this time, the pressure plate 90 acts as a preventative measure against thread snagging: the thread stop 94 on the pressure plate 90 blocks the bottom of the thread divider 25 of the main thread cutter 20, obscuring the thread divider 25 from below. This prevents the thread loop from entering the thread divider 25, thus eliminating the problem of the thread loop getting caught in the thread divider 25 during normal sewing. This prevents the thread from breaking due to snagging and avoids fabric shrinkage, effectively improving sewing performance.

[0082] The difference between Embodiment 2 and Embodiment 1 of the double-acting wire cutting mechanism lies only in that, in Embodiment 2, the pressure plate 90 engages with the main wire cutting blade 20 from above to pressure the wire. Based on this, as... Figure 14 and Figure 15 As shown, in Embodiment 2 of the double-action thread cutting mechanism, the thread pressing plate 90 is only provided with a plate thread pressing part 91, and does not have the function of preventing thread snagging during normal sewing; in the thread pressing plate 90, the plate thread pressing part 91 is distributed on the outside of the main thread cutting knife 20 and is provided at the front end of the thread pressing plate 90; the outer surface of the main thread cutting knife 20 is provided with a knife thread pressing part that protrudes outward (i.e. upward) toward the plate thread pressing part 91.

[0083] In summary, taking the first embodiment of the double-acting knife thread-cutting mechanism as an example, its working principle when cutting the thread to prevent bird nests during the start of the seam is as follows.

[0084] First, after the previous sewing session ends and before the sewing machine starts sewing again, the needle 150 is positioned above the needle plate. The control system 10 can then control the main thread cutter drive source 40 to operate again, ensuring that the thread hook groove 22 on the main thread cutter 20 has already rotated forward to directly below the needle 150 before the sewing machine starts sewing the first stitch. Figure 7a As shown. Alternatively, after the previous sewing session ends and before the sewing machine starts sewing again, the main thread cutter 20 remains behind the needle 150; during the start of sewing, as the needle 150 moves down during the first stitch, the control system 10 controls the main thread cutter drive source 40 to rotate, causing the thread hook groove 22 on the main thread cutter 20 to rotate forward to directly below the needle 150, as shown. Figure 7a As shown. Thus, when the sewing machine begins to sew the first stitch, the needle 150, carrying the top thread, passes downward through the starting stitch hook groove 22.

[0085] Second, as the needle 150 rises, the main thread cutter 20, carrying the thread tip, rotates backward toward the suction pipe 80 until the tip 23 of the main thread cutter 20 passes directly below the needle 150; at this time, if Figure 7b As shown, the end of the starting thread is held between the pressing part 91 of the pressing plate 90 and the pressing part of the main thread cutter 20 on the lower side of the main thread cutter 20, and the starting thread is accommodated in the starting thread receiving part 29 on the upper side of the main thread cutter 20. The main blade edge 21 and the auxiliary blade edge 31 are not engaged.

[0086] Third, the sewing machine continues sewing the set number of stitches in the small stitch distance sewing mode. Then, during the return of the needle 150 and the feed dog, the control system 10 controls the main thread cutter drive 40 to operate, first causing the main thread cutter 20 to rotate counterclockwise forward until the main cutting edge 21 on the main thread cutter 20 passes directly below the needle 150. During this process, the control system 10 controls the suction device to operate, causing the suction pipe 80 to suck up the thread. As the main thread cutter 20 rotates counterclockwise forward, the end of the starting thread, which is clamped between the pressure plate 91 of the pressure plate 90 and the blade pressure plate of the main thread cutter 20, is released and sucked into the suction pipe 80. Figure 7c As shown, the thread from the needle 150 to the end of the starting thread is kept taut and stretched.

[0087] Fourth, subsequently, the control system 10 controls the main thread-cutting drive source 40 to reverse its movement and controls the auxiliary thread-cutting drive source 50 to move, causing the main thread-cutting blade 20 to rotate backward and the auxiliary thread-cutting blade 30 to rotate forward. The main blade edge 21 and the auxiliary blade edge 31 engage and cut the starting thread end at a position directly below or adjacent to the needle 150, ensuring that the thread end remaining on the sewing fabric after the starting thread cut is in the shortest possible state.

[0088] Fifth, and finally, the control system 10 controls the main wire-cutting drive source 40 to continue its reverse operation and controls the auxiliary wire-cutting drive source 50 to reverse its operation, so that the main wire-cutting blade 20 and the auxiliary wire-cutting blade 30 are each reset to their respective positions. Figure 11 The initial position is shown.

[0089] When starting to cut the thread, the main thread cutter 20 is rotated forward in advance through the above control, the pressed starting thread end is quickly released, and the suction pipe 80 straightens the starting thread end; after starting to cut the thread, the main thread cutter 20 can move away from the center of the needle 150 at the fastest speed to prevent the needle 150 from moving downward quickly and piercing the main blade edge 21 and the tip 23 of the main thread cutter 20, which would cause needle breakage and damage to the main thread cutter 20.

[0090] Afterwards, the sewing machine sews normally. During normal sewing, the main thread cutter 20 and the auxiliary thread cutter 30 are both located behind the needle 150. The thread stop 94 on the pressure plate 90 blocks the bottom of the top thread dividing groove 25 of the main thread cutter 20, thus sealing the bottom of the top thread dividing groove 25 and preventing the top thread loop from entering the top thread dividing groove 25 during normal sewing, greatly reducing the problem of the top thread getting caught.

[0091] After sewing is completed, the working principle of the automatic thread cutting mechanism in Embodiment 1 is as follows.

[0092] First, the control system 10 controls the main cutter thread-cutting drive source 40 to operate, driving the main cutter 20 to rotate counterclockwise forward in the first direction, so that the thread-separating groove 24 and the top thread-separating groove 25 are both located directly below the needle 150, or both move forward past the position directly below the needle 150, so that the top thread and bottom thread are hooked into the thread-separating groove 24 and the top thread-separating groove 25, such as... Figure 8 As shown. The control system 10 controls the main thread-cutting drive source 40 to reverse and the auxiliary thread-cutting drive source 50 to move, driving the main thread-cutting blade 20 to rotate backward and the auxiliary thread-cutting blade 30 to rotate forward. The main blade edge 21 and the auxiliary blade edge 31 engage and cut the starting thread end at a position directly below or adjacent to the needle 150, ensuring that the thread end remaining on the fabric after the starting thread cut is at its shortest possible state. Figure 9a The thread is cut directly below needle 150 as shown, resulting in the shortest thread end; however, Figure 9b The back thread cut shown, located directly below the needle 150, ensures a better bottom thread length for greater sewing stability.

[0093] Second, after cutting the bottom and top threads, the control system 10 controls the main blade cutting drive source 40 to continue its reverse action and controls the auxiliary blade cutting drive source 50 to reverse its action, causing the main cutting blade 20 to rotate backward to a position where the top thread separating groove 25 is a certain distance X from the thread blocking part 94 of the pressure plate 90. Figure 10 As shown, the main thread cutter 20 forms an opening between the top thread separating groove 25 and the thread-blocking part 94 of the pressure plate 90, ensuring that the top thread on the needle 150 side passes smoothly through this opening after thread cutting, and that the thread will not get stuck due to the thread-blocking part 94 when the sewing material is subsequently removed. After the sewing material is removed, the main thread cutter 20 completely resets, as shown. Figure 11 As shown.

[0094] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0095] 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 sewing thread cutting control method, comprising a double-acting knife thread cutting mechanism and a control system (10) configured in a sewing machine, the double-acting knife thread cutting mechanism comprising a main thread cutting knife (20) and an auxiliary thread cutting knife (30) both movably configured on the outer periphery of a rotary hook (110) in the sewing machine, a main knife thread cutting drive source (40) connected to the main thread cutting knife (20) in transmission, and an auxiliary knife thread cutting drive source (50) connected to the auxiliary thread cutting knife (30) in transmission, the main knife thread cutting drive source (40) and the auxiliary knife thread cutting drive source (50) both being communicatively connected to the control system (10), the main thread cutting knife (20) having a main blade edge (21) and a through-hole starting stitch hook groove (22), and the auxiliary thread cutting knife (30) having an auxiliary blade edge (31); the sewing thread cutting control method comprises a starting stitch anti-bird nest thread cutting control method; Its features are: The method for controlling thread cutting during seam opening to prevent bird nests includes the following steps: S1. Before the sewing machine starts the first stitch, or during the process of the sewing machine needle (150) moving down during the first stitch, the control system (10) controls the main blade thread cutting drive source (40) to move, driving the main thread cutting blade (20) to move along the first direction, so that the starting stitch hook groove (22) moves to directly below the needle (150). S2. When the sewing machine starts the first stitch, the needle (150) moves down and the needle (150) carries the top thread down through the starting stitch hook groove (22). Under the action of the rotary hook (110), the starting thread end on one side of the needle (150) is moved to the bottom of the main thread cutter (20). S3. The sewing machine needle (150) moves upward when starting the first stitch. After the needle (150) moves upward from the main thread cutter (20), the control system (10) controls the main thread cutter drive source (40) to reverse the action, causing the main thread cutter (20) to retract to the outer periphery of the needle (150) in a second direction opposite to the first direction, and the main blade edge (21) and the auxiliary blade edge (31) do not engage, and the starting thread end is kept in the starting stitch hook groove (22). S4. The sewing machine continues sewing until the set number of stitches is reached. S5. The control system (10) controls the main blade thread cutting drive source (40) to move, causing the main thread cutting blade (20) to move in the first direction, so that the main blade edge (21) passes directly below the needle (150) in the first direction; then the control system (10) controls the main blade thread cutting drive source (40) to move in the opposite direction, causing the main thread cutting blade (20) to retract in the second direction, so that the main blade edge (21) moves to directly below or near the needle (150). 0) The position directly below; at the same time, the control system (10) controls the auxiliary knife cutting drive source (50) to move, driving the auxiliary knife (30) to move along the first direction, so that the auxiliary knife edge (31) moves to the position directly below or near the needle (150), then the main knife edge (21) and the auxiliary knife edge (31) bite and cut the starting thread at the position directly below or near the needle (150); S6. The control system (10) controls the main cutter wire cutting drive source (40) and the auxiliary cutter wire cutting drive source (50) to move in opposite directions. The main cutter wire cutting drive source (40) drives the main cutter (20) to retract along the second direction to the outer periphery of the needle (150), and the auxiliary cutter wire cutting drive source (50) drives the auxiliary cutter (30) to retract along the second direction to the outer periphery of the needle (150).

2. The sewing thread cutting control method according to claim 1, characterized in that: The double-acting wire cutting mechanism also includes a fixed suction pipe (80) and a suction device connected to the suction pipe (80). The suction pipe (80) and the auxiliary wire cutting knife (30) are arranged on the same side of the needle (150). The suction pipe (80) is aligned with the outer surface of the main wire cutting knife (20) facing away from the rotary hook (110). The suction device is communicatively connected to the control system (10). In step S5, the control system (10) controls the suction device to operate, so that the inlet of the suction pipe (80) forms a negative pressure; at the same time, when the main blade (21) passes directly below the needle (150) in the first direction, the end of the starting thread comes out from the starting stitch hook groove (22) and is sucked into the suction pipe (80), and the suction of the suction pipe (80) keeps the starting thread in a taut state.

3. The sewing thread cutting control method according to claim 1, characterized in that: The double-acting wire cutting mechanism also includes a fixedly installed wire pressing plate (90), which is distributed on the outside of the auxiliary wire cutting blade (30) facing away from the main wire cutting blade (20); a plate pressing part (91) is fixedly provided on the wire pressing plate (90), and a blade pressing part is provided on the surface of the main wire cutting blade (20); In step S3, when the main cutter thread drive source (40) drives the main cutter thread cutter (20) to retract in the second direction, a thread clamping seam is formed between the plate pressing part (91) and the cutter pressing part, and the starting thread end is clamped in the thread clamping seam.

4. The sewing thread cutting control method according to claim 3, characterized in that: The plate pressing part (91) is distributed on the outside of the main cutting knife (20) facing away from the rotary hook (110), and the knife pressing part protrudes outward from the outer surface of the main cutting knife (20) facing away from the rotary hook (110).

5. The sewing thread cutting control method according to claim 3, characterized in that: The plate pressing part (91) is distributed on the inner side of the main cutting blade (20) facing the rotary hook (110), and the blade pressing part is provided on the inner surface of the main cutting blade (20) facing the rotary hook (110).

6. The sewing thread cutting control method according to claim 5, characterized in that: The presser plate (90) includes a plate fixing part (92) and a plate body part (93) integrally bent and extended from the plate fixing part (92). The plate fixing part (92) is fixed to the sewing machine base plate (120). The plate body part (93) is distributed on the inner side of the main thread cutter (20) facing the rotary hook (110). The plate presser part (91) extends integrally from the edge of the plate body part (93) along the axial direction of the rotary hook (110) and is distributed on the same side of the plate body part (93) as the starting stitch hook groove (22).

7. The sewing thread cutting control method according to claim 5, characterized in that: The pressure plate (90) also includes a wire-blocking part (94), which is distributed on the inner side of the main wire cutter (20) facing the rotary hook (110); In step S6, when the control system (10) controls the main cutter wire cutting drive source (40) to reverse and cause the main cutter wire cutting blade (20) to retract along the second direction to the outer periphery of the needle (150), the surface thread dividing groove (25) on the main cutter wire cutting blade (20) is distributed on the side directly above the wire blocking part (94) and is blocked by the wire blocking part (94).

8. The sewing thread cutting control method according to claim 1, characterized in that: In step S4, the sewing machine is in small stitch distance sewing mode.

9. The sewing thread cutting control method according to claim 1, characterized in that: The double-acting thread-cutting mechanism further includes a main blade thread-cutting transmission assembly connected between the main blade thread-cutting drive source (40) and the main thread-cutting blade (20). The main blade thread-cutting transmission assembly includes a first thread-cutting crank (61), a first thread-cutting connecting rod (62), a first thread-cutting shaft (63) rotatably supported in the sewing machine base plate (120), a second thread-cutting crank (64) and a third thread-cutting crank (65) both fixed on the first thread-cutting shaft (63), and a second thread-cutting connecting rod (66). The machine includes a main blade holder (67) rotatably mounted in the sewing machine base plate (120), the first thread cutting crank (61) being connected to the main blade thread cutting drive source (40) and driven to rotate by the main blade thread cutting drive source (40), the two ends of the first thread cutting connecting rod (62) being hinged to the first thread cutting crank (61) and the second thread cutting crank (64) respectively, and the two ends of the second thread cutting connecting rod (66) being hinged to the third thread cutting crank (65) and the main blade holder (67) respectively.

10. The sewing thread cutting control method according to claim 1, characterized in that: The double-acting thread-cutting mechanism also includes an auxiliary thread-cutting transmission assembly connected between the auxiliary thread-cutting drive source (50) and the auxiliary thread-cutting blade (30). The auxiliary thread-cutting transmission assembly includes a fourth thread-cutting crank (71), a third thread-cutting connecting rod (72), a second thread-cutting shaft (73) rotatably supported in the sewing machine base plate (120), a fifth thread-cutting crank (74) and a sixth thread-cutting crank (75) both fixed on the second thread-cutting shaft (73), and a fourth thread-cutting connecting rod (76). The machine includes a fourth thread-cutting crank (71) connected to and driven by an auxiliary thread-cutting drive source (50), and an auxiliary blade holder (77) rotatably mounted in the sewing machine base plate (120). The second ends of the third thread-cutting connecting rod (72) are respectively hinged to the fourth thread-cutting crank (71) and the fifth thread-cutting crank (74). The second ends of the fourth thread-cutting connecting rod (76) are respectively hinged to the sixth thread-cutting crank (75) and the auxiliary blade holder (77).

11. The sewing thread cutting control method according to claim 1, characterized in that: The main thread cutter (20) has a tip (23) at its end. The main thread cutter (20) has a thread hook groove (24) and a surface thread groove (25) on both sides along the axis of the rotary hook (110). The outer peripheral edge of the main thread cutter (20) has a surface thread sliding surface (26) connecting the opening of the tip (23) and the thread hook groove (24), and a surface thread sliding surface (27) connecting the opening of the tip (23) and the surface thread groove (25). The sewing thread cutting control method further includes a post-sewing automatic thread cutting control method, which includes the following steps: A1. After the last stitch of the sewing machine needle (150) moves upward from the sewing machine needle plate, the control system (10) controls the main blade thread cutting drive source (40) to move, causing the main thread cutting blade (20) to move in the first direction, so that the tip of the blade (23) is inserted into the top thread loop. Then, part of the top thread and the bottom thread slide into the thread separating groove (24) along the top and bottom thread sliding surface (26), and the other part of the top thread slides into the top thread separating groove (25) along the top thread sliding surface (27). A2. The control system (10) controls the main blade cutting drive source (40) to reverse the action, causing the main blade (20) to retract along the second direction, so that the main blade edge (21) moves to a position directly below or near the needle (150); at the same time, the control system (10) controls the auxiliary blade cutting drive source (50) to move, causing the auxiliary blade (30) to move along the first direction, so that the auxiliary blade edge (31) moves to a position directly below or near the needle (150), then the main blade edge (21) and the auxiliary blade edge (31) bite and cut the surface line and the bottom line at the position directly below or near the needle (150); A3. The control system (10) controls the main cutter wire cutting drive source (40) to continue to reverse, and continues to drive the main cutter wire cutting blade (20) to retract along the second direction to the outer periphery of the needle (150); at the same time, the control system (10) controls the auxiliary cutter wire cutting drive source (50) to reverse, and drives the auxiliary cutter wire cutting blade (30) to retract along the second direction to the outer periphery of the needle (150).

12. The sewing thread cutting control method according to claim 11, characterized in that: In steps S5 and A2, during the process of the feed teeth rising in the sewing machine, the control system (10) controls the auxiliary cutter thread drive source (50) to move, causing the auxiliary cutter thread (30) to move along the first direction.

Images