Synchronous lockstitch sewing machine chain stitch mechanism and synchronous lockstitch sewing machine having the same

Abstract

The present invention belongs to the technical field of lockstitch sewing machines, and in particular, relates to a synchronous lockstitch sewing machine chain stitch mechanism and a synchronous lockstitch sewing machine having the mechanism. In view of the problem that the lockstitch sewing machine capable of chain stitch sewing in the prior art is relatively complex in structure and high in cost, the present invention provides a synchronous lockstitch sewing machine chain stitch mechanism and a synchronous lockstitch sewing machine having the mechanism, comprising a driving mechanism and a piercing mechanism connected to the driving mechanism, and also comprising a thread hooking mechanism capable of driving a thread hooking curved needle to move closer to or away from the axis of the piercing needle, and a synchronous driving assembly is further provided between the thread hooking mechanism and the piercing mechanism, one end of the synchronous driving assembly is connected to the piercing mechanism, and the other end is connected to the thread hooking mechanism. The present invention utilizes a thread hooking curved needle arranged below the piercing needle to hook the thread to form a thread loop, and at the same time utilizes the synchronous driving assembly to synchronize the rotation speeds of the piercing mechanism and the thread hooking mechanism, thereby ensuring the formation of a relatively complete and continuous chain stitch.

Description

Technical Field

[0001] The invention belongs to the technical field of lockstitch sewing machines, and in particular relates to a synchronous lockstitch sewing machine chain stitch mechanism and a synchronous lockstitch sewing machine with the mechanism. Background Art

[0002] In today's technologically advanced world, sewing machines have long been a familiar product in people's production and life. Sewing machines can be divided into lockstitch, single-thread chainstitch and double-thread chainstitch sewing machines according to the different stitches. The so-called stitch refers to the unit composed of stitches at the intervals between the two times the sewing needle passes through the sewing material during the sewing process. Different demands for stitches are the decisive factors in choosing a sewing machine. Chain stitches have good stitch fastness and anti-unraveling ability, so they are often used in fabric sewing. However, the flat-bed sewing machines that can sew chain stitches in the prior art are relatively complex in structure and have a high cost.

[0003] For example, a Chinese utility model patent discloses a lockstitch sewing machine [application number: 201520445262.9], which includes a workbench, a feeding device, a clamping device, a positioning device and a sewing device, wherein the feeding device, the clamping device and the sewing device are arranged on the workbench; the feeding device has a fixed base, a cloth feeding roller, a first driving element and a second driving element, the cloth feeding roller shaft is connected to the fixed base, the first driving element is connected to the fixed base for driving the fixed base to move, and the second driving element is connected to the cloth feeding roller and is driven by the cloth feeding roller. The cloth feeding roller is driven to rotate by receiving the sewing signal of the sewing device; the clamping device has a plurality of clamping plates, at least two of which are overlapped, and the cut piece is placed between the two overlapping clamping plates, and the corresponding positions of the two clamping plates have sewing channels; the sewing needle of the sewing device faces the sewing channel; the positioning device has a detection element and a plurality of reflective elements, the reflective element is located on the uppermost clamping plate of the clamping device, and the detection element is arranged on the sewing device for sensing the reflective element and giving a needle distance change signal to the sewing device.

[0004] The utility model has the advantage of being able to automatically sew cut pieces with different stitch lengths at designated positions, but it still does not solve the above-mentioned problem. Summary of the invention

[0005] The object of the present invention is to provide a chain stitch mechanism for a synchronous lockstitch sewing machine which can sew chain stitches simply, conveniently, stably and reliably in order to solve the above problems.

[0006] Another object of the present invention is to provide a synchronous lockstitch sewing machine that can sew chain stitches simply, conveniently, stably and reliably in order to solve the above-mentioned problems.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A chain stitch mechanism of a synchronous flat-bed sewing machine comprises a driving mechanism and a puncture mechanism driven and connected to the driving mechanism, the puncture needle is connected to one end of the puncture mechanism, the driving mechanism can drive the puncture needle to reciprocate in the vertical direction through the puncture mechanism, and also comprises a thread hooking mechanism that can drive a thread hooking curved needle to move closer to or away from the axis line of the puncture needle, the thread hooking curved needle is connected to one end of the thread hooking mechanism and is located below the puncture needle, the thread hooking mechanism is located below the puncture mechanism, and a synchronous driving component that can make the thread hooking mechanism and the puncture mechanism rotate at the same angular velocity is also provided between the thread hooking mechanism and the puncture mechanism, one end of the synchronous driving component is connected to the puncture mechanism, and the other end is connected to the thread hooking mechanism.

[0009] In the above-mentioned chain stitch mechanism of the synchronous flat-bed sewing machine, the synchronous drive assembly includes a first transmission gear fixedly connected to the piercing mechanism and a second transmission gear fixedly connected to the thread hooking mechanism. The synchronous drive assembly also includes a synchronous transmission rod located between the first transmission gear and the second transmission gear and having two ends respectively meshed with the first transmission gear and the second transmission gear.

[0010] In the above-mentioned chain stitch mechanism of the synchronous lockstitch sewing machine, the first transmission gear and the second transmission gear are both bevel gears, and a bevel gear meshing with the bevel gear is provided at each end of the synchronous transmission rod.

[0011] In the above-mentioned synchronous flat-bed sewing machine chain stitch mechanism, the puncture mechanism includes a puncture drive rod that is drive-connected to the drive mechanism, the synchronous drive assembly is connected to the puncture drive rod, the puncture drive rod is fixedly connected to a transmission wheel at one end away from the drive mechanism, one end of the transmission connecting rod is rotatably connected to the transmission wheel and the axis of the transmission wheel does not pass through the rotation connection point between the transmission connecting rod and the transmission wheel, the other end of the transmission connecting rod is rotatably connected to a mounting sleeve, and the puncture needle is connected to the mounting sleeve.

[0012] In the above-mentioned synchronous flat-bed sewing machine chain stitch mechanism, the thread hooking mechanism includes a thread hooking drive rod, the synchronous drive assembly is connected to the thread hooking drive rod, and the end of the puncture drive rod close to the puncture needle is fixedly connected to a bending needle swinging assembly that can make the thread hooking needle swing close to or away from the axial line of the puncture needle, and the thread hooking needle is fixedly connected to the bending needle swinging assembly.

[0013] In the above-mentioned chain stitch mechanism of the synchronous flat-bed sewing machine, the curved needle swing assembly includes an eccentric wheel and a swing fork connected to the thread hooking drive rod. The bottom end of the swing fork is rotatably connected to a positioning rod, and the upper end of the swing fork extends to both sides of the eccentric wheel. Rotating the eccentric wheel can press the eccentric wheel on the swing fork and cause the swing fork to rotate around the positioning rod, and the thread hooking curved needle is fixedly connected to the swing fork.

[0014] In the above-mentioned chain stitch mechanism of the synchronous flat-bed sewing machine, a bending needle mounting seat is also provided between the thread hook bending needle and the swing fork. The bending needle mounting seat is fixedly connected to the swing fork through a transmission sleeve. The transmission sleeve is sleeved outside the positioning rod and is rotatably connected to the positioning rod.

[0015] In the above-mentioned chain stitch mechanism of the synchronous flat-bed sewing machine, the transmission sleeve coincides with the axial center line of the positioning rod, and a plurality of support bars protrude from the inner surface of the transmission sleeve. The support bars extend radially along the transmission sleeve, and a support gap is provided between two adjacent support bars. The outer surface of the positioning rod is pressed onto the support bar.

[0016] In the above-mentioned chain stitch mechanism of the synchronous lockstitch sewing machine, a needle guard frame which can move synchronously with the thread hooking needle is also provided below the thread hooking needle, and one end of the needle guard frame extends to the outside of the thread hooking needle in the horizontal direction.

[0017] A synchronous lockstitch sewing machine comprises a casing, wherein the above-mentioned synchronous lockstitch sewing machine chain stitch mechanism is arranged in the casing.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] 1. The present invention utilizes a thread hooking curved needle arranged below the puncture needle to hook the thread to form a thread loop, and simultaneously utilizes a synchronous drive assembly to synchronize the rotation speeds of the puncture mechanism and the thread hooking mechanism, that is, synchronizes the puncture frequency of the puncture needle and the thread hooking frequency of the thread hooking curved needle, thereby ensuring the formation of a relatively complete and continuous chain stitch.

[0020] 2. The present invention further provides a bending needle mounting seat and a transmission sleeve for transmission between the swing fork and the thread hooking bending needle, so that the swing amplitude of the thread hooking bending needle can be different from the swing amplitude of the swing fork, that is, the swing amplitude of the thread hooking bending needle can be enlarged by extending the length of the bending needle mounting seat, so that during the fabric sewing process, the swing fork only needs a smaller swing amplitude, thereby reducing the vibration generated when the swing fork swings back and forth at a high frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a stereogram of the present invention;

[0022] Figure 2 is a cross-sectional view of the present invention;

[0023] Figure 3 It is a schematic diagram of the internal structure of the present invention;

[0024] Figure 4 It is a structural schematic diagram of a part of the structure of the present invention;

[0025] Figure 5 It is an exploded view of a part of the structure of the present invention;

[0026] In the figure: driving mechanism 1, puncture mechanism 2, puncture needle 3, thread hooking mechanism 4, thread hooking bending needle 5, synchronous driving assembly 6, needle guard frame 7, puncture drive rod 21, transmission wheel 22, transmission connecting rod 23, mounting sleeve 24, thread hooking drive rod 41, bending needle swinging assembly 42, eccentric wheel 43, swing fork 44, positioning rod 45, bending needle mounting seat 46, transmission sleeve 47, support bar 48, support gap 49, first transmission gear 61, second transmission gear 62, synchronous transmission rod 63, casing 100. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] This embodiment provides a chain stitch mechanism for a synchronous lockstitch sewing machine, combined with Figure 1-3 As shown, it includes a driving mechanism 1 and a puncture mechanism 2 connected to the driving mechanism 1. The driving mechanism 1 can be a driving motor or other specific structures that can realize driving in the prior art. The puncture needle 3 is connected to one end of the puncture mechanism 2. The driving mechanism 1 can drive the puncture needle 3 to reciprocate in the vertical direction through the puncture mechanism 2. It also includes a hooking mechanism 4 that can drive the hooking curved needle 5 to move closer to or away from the axis of the puncture needle 3. The hooking curved needle 5 is connected to one end of the hooking mechanism 4 and is located below the puncture needle 3. The hooking mechanism 4 is located below the puncture mechanism 2. A synchronous driving component 6 is also provided between the hooking mechanism 4 and the puncture mechanism 2, which can make the hooking mechanism 4 rotate at the same angular speed as the puncture mechanism 2. In this way, it can be ensured that the puncture mechanism 2 also rotates one circle correspondingly for every rotation of the hooking mechanism 4, that is, the puncture frequency of the puncture needle 3 is ensured to be consistent with the hooking frequency of the hooking curved needle 5. One end of the synchronous driving component 6 is connected to the puncture mechanism 2, and the other end is connected to the hooking mechanism 4. Among them, the driving connection between the driving mechanism 1 and the puncture mechanism 2 can be a direct driving connection or an indirect driving connection. The indirect driving connection can, for example, be a driving connection between the driving mechanism 1 and the hooking mechanism 4, and then transmitted through the synchronous driving component 6, so that the driving mechanism 1 and the puncture mechanism 2 are indirectly driven.

[0030] The present invention, when in use, starts the driving mechanism 1, the driving mechanism 1 makes the puncture needle 3 with suture puncture the fabric, the puncture needle 3 moves to the lowest position and then rises to form a thread loop, at this time the thread loop is hooked by the thread hooking curved needle 5 moved to the bottom of the puncture needle 3, the puncture needle 3 continues to rise until it exits the fabric, the thread hooking curved needle 5 continues to move to expand the thread loop, at this time the fabric is pushed to move a needle distance, the puncture needle 3 punctures the fabric for the second time to form a new thread loop, at this time the thread hooking curved needle 5 has escaped from the old thread loop, so the old thread loop is tightened when the puncture needle 3 punctures for the second time, the puncture needle 3 moves to the lowest position and then rises, the thread hooking curved needle 5 rotates to hook the new thread loop, and this is repeated to obtain a chain stitch. The driving mechanism 1 drives the puncture mechanism 2 and the thread hooking mechanism 4 to rotate at the same angular velocity under the transmission of the synchronous driving component 6, thereby ensuring that the puncture frequency of the puncture needle 3 is consistent with the thread hooking frequency of the thread hooking curved needle 5, that is, each time the puncture needle 3 completes a lifting and puncturing, the thread hooking curved needle 5 completes a reciprocating movement. Therefore, the present invention utilizes the thread hooking curved needle 5 arranged below the puncture needle 3 to hook the thread to form a thread loop, and at the same time utilizes the synchronous driving component 6 to synchronize the rotation speed of the puncture mechanism 2 and the thread hooking mechanism 4, that is, synchronizes the puncture frequency of the puncture needle 3 and the thread hooking frequency of the thread hooking curved needle 5, thereby ensuring the formation of a relatively complete and continuous chain stitch.

[0031] like Figure 3 As shown, the synchronous drive assembly 6 includes a first transmission gear 61 fixedly connected to the puncture mechanism 2 and a second transmission gear 62 fixedly connected to the line hooking mechanism 4. The synchronous drive assembly 6 also includes a synchronous transmission rod 63 located between the first transmission gear 61 and the second transmission gear 62 and having two ends respectively meshed with the first transmission gear 61 and the second transmission gear 62.

[0032] The first transmission gear 61 and the second transmission gear 62 can also be rotated synchronously by gear rack meshing, but preferably, the first transmission gear 61 and the second transmission gear 62 are both bevel gears, and a bevel gear meshing with the bevel gear is provided at each end of the synchronous transmission rod 63. That is, the first transmission gear 61 and the second transmission gear 62 rotate at the same angular speed through the mutual meshing of the bevel gears, thereby realizing the same angular speed rotation of the thread hooking mechanism 4 and the puncture mechanism 2. In this way, the synchronous transmission rod 63 only rotates during the transmission process, which saves more space and makes the overall structure more compact compared to the gear rack transmission process in which the rack needs to be displaced.

[0033] like Figure 3As shown, the puncture mechanism 2 includes a puncture drive rod 21 that is drivably connected to the drive mechanism 1, the synchronous drive assembly 6 is connected to the puncture drive rod 21, the end of the puncture drive rod 21 away from the drive mechanism 1 is fixedly connected to the transmission wheel 22, one end of the transmission connecting rod 23 is rotatably connected to the transmission wheel 22, and the axis of the transmission wheel 22 does not pass through the rotation connection point between the transmission connecting rod 23 and the transmission wheel 22, that is, the transmission connecting rod 23 is eccentrically connected to the transmission wheel 22. The other end of the transmission connecting rod 23 is rotatably connected to the installation sleeve 24, and the puncture needle 3 is connected to the installation sleeve 24. In this way, the puncture needle 3 completes a descending and ascending puncture action every time the transmission wheel 22 rotates one circle.

[0034] Combination Figure 3-5 As shown, the thread hooking mechanism 4 includes a thread hooking driving rod 41, the synchronous driving assembly 6 is connected to the thread hooking driving rod 41, and the end of the puncture driving rod 41 close to the puncture needle 3 is fixedly connected with a bending needle swinging assembly 42 that can make the thread hooking curved needle 5 swing close to or away from the axis of the puncture needle 3, and the thread hooking curved needle 5 is fixedly connected to the bending needle swinging assembly 42. When in use, the synchronous driving assembly 6 drives the thread hooking driving rod 41 to rotate so that the bending needle swinging assembly 42 at the end swings back and forth, thereby making the thread hooking curved needle 5 swing back and forth close to or away from the axis of the puncture needle 3, so as to achieve the effect of hooking the thread loop and disengaging the thread loop.

[0035] Specifically, the bending needle swing assembly 42 includes an eccentric wheel 43 and a swing fork 44 connected to the thread hooking driving rod 41. The bottom end of the swing fork 44 is rotatably connected to a positioning rod 45. The upper end of the swing fork 44 extends to both sides of the eccentric wheel 43. The eccentric wheel 43 can be rotated to press the eccentric wheel 43 on the swing fork 44 and make the swing fork 44 rotate around the positioning rod 45. The thread hooking bending needle 5 is fixedly connected to the swing fork 44. When the eccentric wheel 43 is driven to rotate, the eccentric wheel 43 will repeatedly apply pressure to both sides of the swing fork 44 alternately, so that the swing fork 44 swings. Every time the eccentric wheel 43 rotates one circle, the swing fork 44 completes a reciprocating swing. A bending needle mounting seat 46 is also provided between the thread hooking bending needle 5 and the swing fork 44. The bending needle mounting seat 46 is fixedly connected to the swing fork 44 through a transmission sleeve 47. The transmission sleeve 47 is sleeved outside the positioning rod 45 and is rotatably connected to the positioning rod 45.

[0036] The present invention further provides a bending needle mounting seat 46 and a transmission sleeve 47 for transmission between the swing fork 44 and the thread hooking bending needle 5, so that the swing amplitude of the thread hooking bending needle 5 can be different from the swing amplitude of the swing fork 44, that is, the swing amplitude of the thread hooking bending needle 5 can be enlarged by extending the length of the bending needle mounting seat 46, so that during the fabric sewing process, the swing fork 44 only needs a smaller swing amplitude, thereby reducing the vibration generated when the swing fork 44 swings back and forth at a high frequency.

[0037] like Figure 5As shown, the transmission sleeve 47 coincides with the axis of the positioning rod 45, the positioning rod 45 is fixedly arranged, for example, it can be fixedly connected to the housing 100, a plurality of support bars 48 protrude from the inner surface of the transmission sleeve 47, the support bars 48 extend along the radial direction of the transmission sleeve 47, and there is a support gap 49 between two adjacent support bars 48, and the outer surface of the positioning rod 45 is pressed on the support bars 48. In this way, the contact area between the transmission sleeve 47 and the positioning rod 45 can be reduced, so that the positioning rod 45 provides radial support to the transmission sleeve 47, while reducing the friction between the transmission sleeve 47 and the positioning rod 45 when the transmission sleeve 47 swings relative to the positioning rod 45.

[0038] like Figure 4 As shown, a needle guard frame 7 is provided below the thread hooking curved needle 5 and can move synchronously with the thread hooking curved needle 5, and one end of the needle guard frame 7 extends horizontally to the outside of the thread hooking curved needle 5. In this way, during use, if an obstacle appears on the swinging path, the needle guard frame 7 can contact the obstacle before the thread hooking curved needle 5, thereby preventing the thread hooking curved needle 5 from being damaged during use.

[0039] The working principle of the present invention is: when in use, the driving mechanism 1 is started, the driving mechanism 1 drives the puncture drive rod 21 to rotate, the transmission wheel 22 and the puncture drive rod 21 rotate synchronously, the transmission wheel 22 causes the puncture needle 3 to reciprocate in the vertical direction through the transmission connecting rod 23, and the thread hooking drive rod 41 rotates at the same angular velocity as the puncture drive rod 21 under the transmission action of the synchronous transmission rod 63, thereby driving the eccentric wheel 43 to rotate, and the eccentric wheel 43 pushes the swing fork 44 to swing with the positioning rod 45 as the axis, thereby driving the thread hooking curved needle 5 to swing back and forth through the curved needle mounting seat 46 and the transmission sleeve 47. The puncture needle 3 carries a suture. After puncturing the fabric, the puncture needle 3 moves to the lowest position and then rises to form a thread loop. At this time, the thread loop is hooked by the thread hooking needle 5 that swings to the bottom of the puncture needle 3. The puncture needle 3 continues to rise until it exits the fabric. The thread hooking needle 5 continues to swing to expand the thread loop. At this time, the fabric is pushed to move a needle distance. The puncture needle 3 punctures the fabric for the second time to form a new thread loop. At this time, the thread hooking needle 5 has escaped from the old thread loop. Therefore, the old thread loop is tightened when the puncture needle 3 punctures for the second time. The puncture needle 3 moves to the lowest position and then rises, and the thread hooking needle 5 swings to hook the new thread loop. This is repeated to obtain a chain stitch. The driving mechanism 1 drives the puncture mechanism 2 and the thread hooking mechanism 4 to rotate at the same angular velocity under the transmission of the synchronous driving component 6, thereby ensuring that the puncture frequency of the puncture needle 3 is consistent with the thread hooking frequency of the thread hooking curved needle 5, that is, each time the puncture needle 3 completes a lifting and puncturing, the thread hooking curved needle 5 completes a reciprocating movement. Therefore, the present invention utilizes the thread hooking curved needle 5 arranged below the puncture needle 3 to hook the thread to form a thread loop, and at the same time utilizes the synchronous driving component 6 to synchronize the rotation speed of the puncture mechanism 2 and the thread hooking mechanism 4, that is, synchronizes the puncture frequency of the puncture needle 3 and the thread hooking frequency of the thread hooking curved needle 5, thereby ensuring the formation of a relatively complete and continuous chain stitch.

[0040] Example 2

[0041] This embodiment provides a synchronous lockstitch sewing machine, combined with Figure 1-5 As shown, it includes a housing 100, and the housing 100 is provided with the chain stitch mechanism of the synchronous flat-bed sewing machine described in Example 1.

[0042] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0043] Although the present invention uses more terms such as driving mechanism 1, puncture mechanism 2, puncture needle 3, thread hooking mechanism 4, thread hooking curved needle 5, synchronous driving assembly 6, needle guard 7, puncture driving rod 21, transmission wheel 22, transmission connecting rod 23, mounting sleeve 24, thread hooking driving rod 41, curved needle swing assembly 42, eccentric wheel 43, swing fork 44, positioning rod 45, curved needle mounting seat 46, transmission sleeve 47, support bar 48, support gap 49, first transmission gear 61, second transmission gear 62, synchronous transmission rod 63, housing 100, etc., it does not exclude the possibility of using other terms. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. A chain stitch mechanism for a synchronous lockstitch sewing machine, comprising a driving mechanism (1) and a puncture mechanism (2) drivingly connected to the driving mechanism (1), wherein a puncture needle (3) is connected to one end of the puncture mechanism (2), and the driving mechanism (1) can drive the puncture needle (3) to reciprocate in a vertical direction through the puncture mechanism (2), characterized in that: It also includes a thread hooking mechanism (4) capable of driving the thread hooking curved needle (5) to move toward or away from the axis of the puncture needle (3); the thread hooking curved needle (5) is connected to one end of the thread hooking mechanism (4) and is located below the puncture needle (3); the thread hooking mechanism (4) is located below the puncture mechanism (2); a synchronous drive component (6) capable of causing the thread hooking mechanism (4) and the puncture mechanism (2) to rotate at the same angular velocity is provided between the thread hooking mechanism (4) and the puncture mechanism (2); one end of the synchronous drive component (6) is connected to the puncture mechanism (2), and the other end is connected to the thread hooking mechanism (4); The thread hooking mechanism (4) comprises a thread hooking driving rod (41), the synchronous driving assembly (6) is connected to the thread hooking driving rod (41), and the end of the thread hooking driving rod (41) close to the puncture needle (3) is fixedly connected to a bending needle swinging assembly (42) capable of causing the thread hooking bending needle (5) to swing close to or away from the axis of the puncture needle (3), and the thread hooking bending needle (5) is fixedly connected to the bending needle swinging assembly (42); The bending needle swing assembly (42) comprises an eccentric wheel (43) and a swing fork (44) connected to the thread hooking driving rod (41); the bottom end of the swing fork (44) is rotatably connected to a positioning rod (45); the upper end of the swing fork (44) extends to both sides of the eccentric wheel (43); the eccentric wheel (43) is rotated so that the eccentric wheel (43) is pressed against the swing fork (44) and the swing fork (44) is rotated around the positioning rod (45); the thread hooking bending needle (5) is fixedly connected to the swing fork (44); A bending needle mounting seat (46) is further provided between the thread hooking bending needle (5) and the swing fork (44); the bending needle mounting seat (46) is fixedly connected to the swing fork (44) via a transmission sleeve (47); the transmission sleeve (47) is sleeved outside the positioning rod (45) and is rotationally connected to the positioning rod (45); The transmission sleeve (47) and the axial center line of the positioning rod (45) coincide with each other, a plurality of support bars (48) protrude from the inner surface of the transmission sleeve (47), the support bars (48) extend in the radial direction of the transmission sleeve (47), a support gap (49) is provided between two adjacent support bars (48), and the outer surface of the positioning rod (45) is pressed onto the support bars (48); A needle guard frame (7) is also provided below the thread hooking curved needle (5) and can move synchronously with the thread hooking curved needle (5), and one end of the needle guard frame (7) extends in the horizontal direction to the outside of the thread hooking curved needle (5).

2. The chain stitch mechanism of a synchronous lockstitch sewing machine according to claim 1, characterized in that: The synchronous drive assembly (6) comprises a first transmission gear (61) fixedly connected to the puncture mechanism (2) and a second transmission gear (62) fixedly connected to the thread hooking mechanism (4). The synchronous drive assembly (6) further comprises a synchronous transmission rod (63) located between the first transmission gear (61) and the second transmission gear (62) and having two ends respectively meshing with the first transmission gear (61) and the second transmission gear (62).

3. The chain stitch mechanism of a synchronous lockstitch sewing machine as claimed in claim 2, characterized in that: The first transmission gear (61) and the second transmission gear (62) are both bevel gears, and a bevel gear meshing with the bevel gear is provided at each end of the synchronous transmission rod (63).

4. The chain stitch mechanism of a synchronous lockstitch sewing machine as claimed in claim 1, characterized in that: The puncture mechanism (2) comprises a puncture drive rod (21) drivingly connected to the drive mechanism (1), the synchronous drive assembly (6) being connected to the puncture drive rod (21), one end of the puncture drive rod (21) away from the drive mechanism (1) being fixedly connected to a transmission wheel (22), one end of a transmission connecting rod (23) being rotatably connected to the transmission wheel (22) and the axis of the transmission wheel (22) not passing through a rotational connection point between the transmission connecting rod (23) and the transmission wheel (22), the other end of the transmission connecting rod (23) being rotatably connected to a mounting sleeve (24), and the puncture needle (3) being connected to the mounting sleeve (24).

5. A synchronous lockstitch sewing machine, comprising a housing (100), characterized in that: The housing (100) is provided with a chain stitch mechanism for a synchronous lockstitch sewing machine as claimed in any one of claims 1 to 4.

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