阅读说明：本技术 一种链双针合缝机 (Chain double-needle linking machine ) 是由 李娟� 徐建林 刘瑞宁 张蕾 张素辉 杜雨洁 柳志超 于 2021-07-29 设计创作，主要内容包括：本发明提供了一种链双针合缝机,包括缝纫机本体和机针组件；缝纫机本体具有水平旋梭和带刀压脚；机针组件竖直连接于缝纫机本体的机头上,动力输入端与缝纫机本体的动力轴杆连接,机针组件具有沿缝纫机本体的前后方向间隔分布的两个针杆；其中,水平旋梭的旋转挂线频率为动力轴杆的上下升降频率的两倍,两个针杆具有一并停止于带刀压脚上方的收针状态,还具有交替上下运动的缝合状态,在缝合状态时,水平旋梭依次挂取两个针杆上的面线。本发明提供的一种链双针合缝机,两个针杆能够分别与水平旋梭配合形成独立成链的两条重合的缝合线,从而提高缝合强度,且两条缝合线能够高度重合,缝合外观质量好。(The invention provides a chain double-needle linking machine, which comprises a sewing machine body and a needle assembly; the sewing machine body is provided with a horizontal rotating shuttle and a band knife presser foot; the needle assembly is vertically connected to a machine head of the sewing machine body, a power input end is connected with a power shaft lever of the sewing machine body, and the needle assembly is provided with two needle rods which are distributed at intervals along the front and back directions of the sewing machine body; the horizontal rotating shuttle is used for sequentially hanging the upper threads on the two needle rods in a sewing state. According to the chain double-needle linking machine provided by the invention, the two needle rods can be respectively matched with the horizontal rotating shuttle to form two overlapped suture lines which are independently chained, so that the linking strength is improved, the two suture lines can be highly overlapped, and the appearance quality of the linking is good.)

1. A chain double needle linking machine, comprising:

a sewing machine body having a horizontal rotating shuttle and a knife presser foot;

the needle assembly is vertically connected to a machine head of the sewing machine body, a power input end is connected with a power shaft lever of the sewing machine body, and the needle assembly is provided with two needle rods which are distributed at intervals along the front and back directions of the sewing machine body;

the rotating and thread hanging frequency of the horizontal rotating shuttle is twice of the up-down lifting frequency of the power shaft lever, the two needle bars have a narrowing state of stopping above the band knife presser foot together, and also have a sewing state of moving up and down alternately, and the horizontal rotating shuttle sequentially hangs the upper threads on the two needle bars in the sewing state.

2. The chain twin-needle stitching machine of claim 1, wherein the needle assembly comprises:

the connecting seat is provided with a sliding hole vertically extending upwards from the bottom end, and the top end of the connecting seat is fixedly connected with the machine head;

the two sliding rods are respectively connected in the sliding holes in a sliding mode in the vertical direction, the bottom ends of the two sliding rods are respectively detachably connected with the needle bar, a connecting shaft is arranged at the top end of one of the sliding rods, and one end of the connecting shaft vertically penetrates through the top wall of the connecting seat upwards and is connected with the power shaft lever;

and the transmission part is arranged in the sliding hole, is respectively connected with the two sliding rods and is used for transmitting reverse driving force between the two sliding rods.

3. The chain double-needle linking machine according to claim 2, wherein two of said slide bars are disposed opposite to each other, and the side walls of two of said slide bars which are close to each other slide against each other, and the other side walls slide against the wall of said slide hole; two all be equipped with the storage tank on the mutual lateral wall that is close to of slide bar, two be equipped with the rack structure that extends along vertical direction on the cell wall of storage tank all, the driving medium level is worn to locate two between the storage tank, and both ends respectively with the both sides pore wall of sliding hole rotates and is connected, gear structure has on the driving medium, gear structure respectively with two rack structure meshes.

4. A chain twin-needle stitching machine according to claim 3, wherein the two rack structures are staggered horizontally; the transmission member includes:

the first rotating shaft is rotatably connected with the connecting seat, one end of the first rotating shaft penetrates into the sliding hole and horizontally extends to a position between the two accommodating grooves, the extending end is sleeved with a first gear, and the first gear is meshed with one of the rack structures;

the second rotating shaft is rotatably connected with the connecting seat, one end of the second rotating shaft penetrates into the sliding hole along the axial direction of the first rotating shaft and is rotatably connected with the extending end of the first rotating shaft, a second gear is sleeved on the penetrating end, and the second gear is meshed with the other rack structure;

the extension end of the first rotating shaft is provided with a first polygonal hole extending along the axial direction of the first rotating shaft, the penetrating end of the second rotating shaft is provided with a second polygonal hole extending along the axial direction of the second rotating shaft, a polygonal sliding pin is arranged in the second polygonal hole, the polygonal sliding pin has a separation state that the polygonal sliding pin is integrally retracted into the second polygonal hole, and the polygonal sliding pin also has a tabling state that one end of the polygonal sliding pin extends into the first polygonal hole.

5. The chain double-needle linking machine according to claim 4, wherein the extending end of the first rotating shaft is provided with a shaft hole, the bottom of the shaft hole is provided with the first polygonal hole, and the first rotating shaft is provided with a first through hole which is communicated with the first polygonal hole along the axial direction of the first rotating shaft; the extending end of the second rotating shaft is provided with a shaft sleeve, the center of the shaft sleeve is provided with the second polygonal hole, the shaft sleeve extends into the shaft hole and is rotatably connected with the shaft hole, and the second rotating shaft is provided with a second through hole which is communicated with the second polygonal hole along the axial direction of the second rotating shaft.

6. The chain double-needle linking machine according to claim 5, wherein a first push rod is screwed into the first through hole, one end of the first push rod abuts against one end of the polygonal sliding pin, a second push rod is screwed into the second through hole, and one end of the second push rod abuts against the other end of the polygonal sliding pin.

7. The chain double-needle linking machine according to any one of claims 1 to 6, wherein said sewing machine body is further provided with a bird-nesting prevention mechanism having a hook extending in a direction toward said presser foot, and in said narrowing state, said hook extends above said presser foot and swings from below one of said needle bars to below the other needle bar, thereby collectively hooking and pulling the upper threads on both said needle bars.

8. The chain twin-needle linking machine of claim 7 wherein said anti-bird nest mechanism comprises:

the fixing seat is fixedly connected to the sewing machine body, and an electromagnetic telescopic rod is arranged at one end, far away from the band knife presser foot, of the fixing seat;

the line hooking device is connected to the fixed seat in a sliding mode and is connected with the output end of the electromagnetic telescopic rod, and the line hooking device is provided with the line hook;

and one end of the thread clamping elastic plate is connected with the fixed seat, and the other end of the thread clamping elastic plate elastically butts against the side wall of the thread hook and is used for clamping the upper thread when the thread hook retracts.

9. The chain double-needle sewing machine according to claim 8, wherein the fixing base is provided with a slide way, and one end of the slide way facing the presser foot with the knife is provided with a guide groove; the thread hooking device comprises a sliding seat connected to the sliding rail in a sliding manner, a thread hook hinged to the sliding seat and an elastic element, one end of the elastic element is connected with the sliding seat, and the other end of the elastic element is connected with the thread hook;

wherein, the line colludes and deviates from elastic element's lateral wall is equipped with sunken guide surface when the line colludes and stretches out, sunken guide surface with the guide way is kept away from elastic element's cell wall elasticity is contradicted when the line colludes the withdrawal, sunken guide surface roll-off the guide way, thereby drive the line colludes the swing.

10. The chain double-needle linking machine as claimed in claim 8, wherein an absorption head is further provided at an end of the fixing base facing the presser foot with the knife, the absorption head is provided with a negative pressure air hole, and the thread hook passes through an opening of the negative pressure air hole when the thread hooking device hooks the thread in a telescopic manner.

Technical Field

The invention belongs to the technical field of sewing machines, and particularly relates to a chain double-needle sewing machine.

Background

At present, when clothes are processed, the use frequency of a double-needle sewing machine is higher and higher, the double-needle sewing machine simultaneously performs sewing operation through two needle bars which are arranged in parallel, so that two parallel or coincident suture line structures are processed at one time, along with the increasing diversification of the customer requirements, the requirement of coincident sewing of two suture lines is provided for some clothes products in order to improve the sewing reliability, however, because the current double-needle sewing machine mostly adopts a double-needle single-shuttle sewing form, the suture line formed by single needle walking is in a form that two upper threads and a bottom thread are simultaneously hooked and linked through the synchronous action of the double needles, although two suture lines with better decorative effect can be formed, the mode can not form the reliability effect of secondary sewing, so the double-needle sewing machine is not suitable for coincident sewing process aiming at improving the sewing firm strength, and the current mode that the single-needle sewing machine can only perform two times of sewing operation repeatedly, however, the absolute overlapping of the positions of the two sewing threads cannot be ensured, which results in poor appearance of the sewing and low working efficiency due to the need of performing the second sewing.

Disclosure of Invention

The embodiment of the invention provides a chain double-needle sewing machine, aiming at improving the sewing reliability of a double-needle sewing machine for carrying out overlapped sewing processing and improving the processing efficiency of clothes with secondary overlapped sewing process requirements.

In order to achieve the purpose, the invention adopts the technical scheme that: there is provided a chain double needle linking machine comprising:

the sewing machine body is provided with a horizontal rotating shuttle or a swinging shuttle and a band knife presser foot;

the needle assembly is vertically connected to a machine head of the sewing machine body, a power input end is connected with a power shaft lever of the sewing machine body, and the needle assembly is provided with two needle rods which are distributed at intervals along the front and back directions of the sewing machine body;

the horizontal rotating shuttle is used for sequentially hanging the upper threads on the two needle rods in a sewing state.

In one possible implementation, the needle assembly includes:

the connecting seat is provided with a sliding hole vertically extending upwards from the bottom end, and the top end of the connecting seat is fixedly connected with the machine head;

the two sliding rods are respectively connected in the sliding holes in a sliding mode in the vertical direction, the bottom ends of the two sliding rods are respectively detachably connected with a needle rod, a connecting shaft is arranged at the top end of one sliding rod, and one end of the connecting shaft vertically penetrates through the top wall of the connecting seat upwards and is connected with the power shaft lever;

and the transmission part is arranged in the sliding hole, is respectively connected with the two sliding rods and is used for transmitting the reverse driving force between the two sliding rods.

In some embodiments, the two sliding rods are oppositely arranged, the side walls of the two sliding rods which are close to each other are in sliding collision, and the other side walls are in sliding collision with the wall of the sliding hole; all be equipped with the storage tank on the lateral wall that two slide bars are close to each other, be equipped with the rack structure that extends along vertical direction on the cell wall of two storage tanks all, the driving medium level is worn to locate between two storage tanks, and both ends rotate with the both sides pore wall of slide opening respectively and are connected, has gear structure on the driving medium, gear structure respectively with two rack structure meshes.

Illustratively, two rack structures are distributed in a staggered manner in the horizontal direction; the driving medium includes:

the first rotating shaft is rotatably connected with the connecting seat, one end of the first rotating shaft penetrates into the sliding hole and horizontally extends to the position between the two accommodating grooves, the extending end is sleeved with a first gear, and the first gear is meshed with one of the rack structures;

the second rotating shaft is rotatably connected with the connecting seat, one end of the second rotating shaft penetrates into the sliding hole along the axial direction of the first rotating shaft and is rotatably connected with the extending end of the first rotating shaft, a second gear is sleeved on the penetrating end, and the second gear is meshed with the other rack structure;

the extension end of the first rotating shaft is provided with a first polygonal hole extending along the axial direction of the first rotating shaft, the penetrating end of the second rotating shaft is provided with a second polygonal hole extending along the axial direction of the second rotating shaft, a polygonal sliding pin is arranged in the second polygonal hole and has a separation state that the polygonal sliding pin integrally retracts into the second polygonal hole, and the polygonal sliding pin also has a tabling state that one end of the polygonal sliding pin extends into the first polygonal hole.

For example, an extending end of the first rotating shaft is provided with a shaft hole, a first polygonal hole is arranged at the bottom of the shaft hole, and a first through hole communicated with the first polygonal hole along the axial direction of the first rotating shaft is arranged on the first rotating shaft; the extending end of the second rotating shaft is provided with a shaft sleeve, the center of the shaft sleeve is provided with a second polygonal hole, the shaft sleeve extends into the shaft hole and is rotatably connected with the shaft hole, and the second rotating shaft is provided with a second through hole communicated with the second polygonal hole along the axial direction of the second rotating shaft.

Furthermore, a first ejector rod is screwed in the first through hole, one end of the first ejector rod is abutted with one end of the polygonal sliding pin, a second ejector rod is screwed in the second through hole, and one end of the second ejector rod is abutted with the other end of the polygonal sliding pin.

In a possible implementation mode, the sewing machine body is further provided with a bird nest prevention mechanism, the bird nest prevention mechanism is provided with a line hook which stretches towards the direction of the band knife presser foot, and in the narrowing state, the line hook extends to the upper side of the band knife presser foot and swings to the lower side of the other needle rod from the lower side of one needle rod, so that the upper lines on the two needle rods are hooked and pulled together.

In some embodiments, the anti-nest mechanism comprises:

the fixing seat is fixedly connected to the sewing machine body, and an electromagnetic telescopic rod is arranged at one end, far away from the band knife presser foot, of the fixing seat;

the wire hooking device is connected to the fixed seat in a sliding mode and connected with the output end of the electromagnetic telescopic rod, and a wire hook is arranged on the wire hooking device;

one end of the thread clamping elastic plate is connected with the fixed seat, and the other end of the thread clamping elastic plate elastically abuts against the side wall of the thread hook and is used for clamping the upper thread when the thread hook retracts.

Illustratively, a slideway is arranged on the fixed seat, and a guide groove is arranged at one end of the slideway, which faces the presser foot with the knife; the thread hooking device comprises a sliding seat connected to the sliding rail in a sliding manner, a thread hook hinged to the sliding seat and an elastic element, wherein one end of the elastic element is connected with the sliding seat, and the other end of the elastic element is connected with the thread hook;

wherein, the lateral wall that the line colluded and deviates from elastic element is equipped with sunken guide face, and when the line colluded and stretches out, sunken guide face and guide way are backed from elastic element's cell wall elasticity and are contradicted, and when the line colluded the withdrawal, sunken guide face roll-off guide way to drive the line and collude the swing.

In some embodiments, an adsorption head is further arranged at one end of the fixing seat facing the presser foot with the knife, a negative pressure air hole is formed in the adsorption head, and when the thread hooking device hooks a thread in a telescopic mode, the thread hook passes through the opening of the negative pressure air hole.

The chain double-needle linking machine provided by the invention has the beneficial effects that: compared with the prior art, the chain double-needle linking machine has the advantages that when the needle assembly is in the narrowing state, the two needle rods are all positioned above the presser foot with the cutter, so that cloth pieces can be placed and replaced conveniently; when sewing up the operation, two needle bars on the drive machine needle subassembly alternate motion about going up and down through the power axostylus axostyle, because the rotatory string line frequency of horizontal rotating shuttle is the twice of power axostylus axostyle lifting frequency, consequently, horizontal rotating shuttle just can hang the facial line that gets on one of them needle bar that drops at every turn and form a chain, thereby make two needle bars can form two coincidence stylolite of independent chaining with the cooperation of horizontal rotating shuttle respectively, compare in the mode of two needle bars simultaneous motions and bottom line of hanging simultaneously, be close to twice repetition stitching and the coincidence seam that forms more, the seam intensity is high, it is firm reliable to sew up, and because two high coincidences of stylolite can be ensured to the front and back mode that sets up of two needle bars, thereby improve and sew up outward appearance quality.

Drawings

FIG. 1 is a schematic front view of a chain double-needle sewing machine according to an embodiment of the present invention;

FIGS. 2 and 3 are schematic views showing the alternate engagement structure of two needle bars and a horizontal rotary hook in a sewing state of a chain double-needle sewing machine according to an embodiment of the present invention;

FIG. 4 is a schematic structural view of a needle assembly in a retracted state according to an embodiment of the present invention;

FIG. 5 is a schematic perspective view of two sliding bars according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of an exploded construction of a transmission member used in an embodiment of the present invention;

FIG. 7 is a schematic cross-sectional view of a transmission member used in an embodiment of the present invention;

FIG. 8 is a schematic perspective view of an anti-nest mechanism used in an embodiment of the present invention;

FIG. 9 is a schematic bottom view (partially) illustrating an anti-nest mechanism according to an embodiment of the present invention;

FIG. 10 is a schematic top view (partially) of the bird nest prevention mechanism used in the embodiment of the present invention with the wire hooks extended;

fig. 11 is a schematic perspective view of a presser foot with a knife according to an embodiment of the present invention.

In the figure: 1. a sewing machine body; 11. a horizontal rotating shuttle; 12. a presser foot with a knife; 121. a blade; 13. a power shaft lever; 2. a needle assembly; 20. a needle bar; 21. a connecting seat; 210. a slide hole; 22. a slide bar; 220. a containing groove; 2201. a rack structure; 221. a connecting shaft; 23. a transmission member; 230. a gear structure; 231. a first rotating shaft; 2311. a first gear; 2312. a first polygonal hole; 2313. a shaft hole; 2314. a first through hole; 2315. a first ejector rod; 2316. a reset hole; 232. a second rotating shaft; 2321. a second gear; 2322. a second polygonal hole; 2323. a shaft sleeve; 2324. a second through hole; 2325. a second ejector rod; 233. a polygonal sliding pin; 234. a return spring; 3. an anti-bird nest mechanism; 31. a fixed seat; 311. an electromagnetic telescopic rod; 312. a slideway; 313. a guide groove; 32. a wire hooking device; 321. a slide base; 322. a wire hook; 3221. a recessed guide surface; 323. an elastic element; 33. a wire clamping spring plate; 34. an adsorption head; 341. and (5) negative pressure air holes.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

It should be noted that the rotating hook is a core component of the sewing machine, hooks the loop of the upper thread by the hook tip, enlarges the loop, and guides the thread to form a lock stitch by surrounding the bobbin, the horizontally rotating hook is called a horizontal rotating hook, and the vertically rotating hook is called a vertical rotating hook; the band knife presser foot 12 is provided with the blade 121 (see fig. 11) at the fork position of the sewing machine presser foot, and the thread end generated in the previous sewing and narrowing process during the sewing and routing process is cut off by the blade 121, so that the thread end or thread group generated at the starting point of the sewing position can be avoided, which is a common structure of some sewing machines with bird nest (thread group) prevention function, and the detailed description is omitted.

Referring to fig. 1 to 4 and fig. 11 together, a chain double-needle sewing machine according to the present invention will now be described. The chain double-needle sewing machine comprises a sewing machine body 1 and a needle assembly 2; the sewing machine body 1 is provided with a horizontal rotating shuttle 11 or a swinging shuttle and a band knife presser foot 12; the needle assembly 2 is vertically connected to the head of the sewing machine body 1, the power input end is connected with the power shaft lever 13 of the sewing machine body 1, and the needle assembly 2 is provided with two needle rods 20 which are distributed at intervals along the front and back directions of the sewing machine body 1; the thread-hanging frequency of the horizontal rotating shuttle 11 is twice the vertical lifting frequency of the power shaft lever 13, the two needle bars 20 have a narrowing state in which they are stopped above the presser foot 12 with the knife and a sewing state in which they are alternately moved up and down, and the horizontal rotating shuttle 11 sequentially hangs the upper threads on the two needle bars 20 in the sewing state.

It should be noted that the power input end of the needle assembly 2 may be directly connected to one of the needle bars 20 and indirectly connected to the other needle bar 20 through a member having a reverse transmission function (e.g., a reverse power generated by gear engagement, and a reverse motion generated at both ends of a centrally hinged swing link), so as to realize the up-and-down alternate motion of the two needle bars 20.

The working principle of the chain double-needle linking machine provided by the embodiment is as follows: it should be understood at first that, because the two needle bars 20 are positioned differently, the horizontal rotating shuttle 11 is selected here, so that the upper threads (thread loops) on the two needle bars 20 can be ensured to be hooked by the locking tip of the horizontal rotating shuttle 11 by positioning the rotation center axis of the rotating shuttle on the perpendicular bisector of the two needle bars 20, when one needle bar 20 is lowered to the low position, the locking tip of the horizontal rotating shuttle 11 is rotated to the position aligned with the needle bar 20 to hook the upper thread on the needle bar 20, and when the horizontal rotating shuttle 11 is rotated more than half a circle, the locking tip of the horizontal rotating shuttle 11 is rotated again to be aligned with the needle bar 20 and hook the upper thread to form the next sewing chain ring, and this is repeated, although the same ground thread (thread wound on the lock cylinder of the horizontal rotating shuttle 11) is used, the upper threads on the two needle bars 20 can be respectively formed into two independent sewing threads (chains), thereby forming a double seam having the same effect as that of the single-needle sewing machine repeatedly sewing twice along the same path.

Compared with the prior art, the chain double-needle linking machine provided by the embodiment has the advantages that when the needle assembly 2 is in a narrowing state, the two needle rods 20 are all positioned above the knife presser foot 12, so that cloth pieces can be conveniently placed and replaced; during sewing operation, the two needle bars 20 on the needle assembly 2 are alternately moved up and down by the up-and-down lifting and moving of the power shaft lever 13, and the thread hanging frequency of the horizontal rotating shuttle 11 is twice of the lifting frequency of the power shaft lever 13, so that the upper thread on one of the lowered needle bars 20 can be hung to form a chain by each rotation of the horizontal rotating shuttle 11, and the two needle bars 20 can be respectively matched with the horizontal rotating shuttle 11 to form two overlapped sewing threads which are independently chained, compared with the mode that the two needle bars 20 synchronously move and simultaneously hang the bottom thread, the sewing machine is closer to the overlapped seam formed by two repeated sewing, the sewing strength is high, the sewing is firm and reliable, and the front-and-back arrangement mode of the two needle bars 20 can ensure that the two sewing threads are highly overlapped, so that the sewing appearance quality is improved.

In some embodiments, referring to fig. 4, needle assembly 2 comprises a connecting seat 21, two slide bars 22, and a transmission 23; wherein, a sliding hole 210 vertically extending upwards from the bottom end is arranged on the connecting seat 21, and the top end of the connecting seat 21 is fixedly connected with the machine head; the two sliding rods 22 are respectively connected in the sliding holes 210 in a sliding manner along the vertical direction, the bottom ends of the two sliding rods are respectively detachably connected with the needle bar 20, the top end of one sliding rod 22 is provided with a connecting shaft 221, and one end of the connecting shaft 221 vertically penetrates through the top wall of the connecting seat 21 upwards and is connected with the power shaft lever 13; the transmission piece 23 is arranged in the slide hole 210, is respectively connected with the two slide bars 22, and is used for transmitting reverse driving force between the two slide bars 22;

the two sliding rods 22 are oppositely arranged, the side walls of the two sliding rods 22 close to each other are in sliding contact with each other, and the other side walls are in sliding contact with the wall of the sliding hole 210; the side walls of the two sliding rods 22 close to each other are provided with accommodating grooves 220, the groove walls of the two accommodating grooves 220 are provided with rack structures 2201 extending in the vertical direction, the transmission member 23 horizontally penetrates between the two accommodating grooves 220, two ends of the transmission member are respectively rotatably connected with the hole walls on two sides of the sliding hole 210, the transmission member 23 is provided with a gear structure 230, and the gear structure 230 is respectively engaged with the two rack structures 2201.

The sliding hole 210 can be a rectangular hole, a circular hole or an elliptical hole, and the two sliding rods 22 are attached to each other to form an appearance with the same shape as the cross section of the sliding hole 210, so that the two sliding rods 22 can be simultaneously slidably connected in the sliding hole 210, and the two sliding rods 22 can slide relatively by relative sliding of the attachment surfaces; when the power shaft 13 drives the connecting shaft 221 to descend, the corresponding slide rod 22 descends together, and the gear structure 230 is driven to rotate by the tooth-shaped structure on the slide rod 22, so that the other slide rod 22 is driven to ascend together by the other tooth-shaped structure, thereby realizing the up-and-down alternate motion of the two needle rods 20, and the transmission is stable and reliable.

In the present embodiment, please refer to fig. 4 to fig. 7, the two rack structures 2201 are distributed along the horizontal direction in a staggered manner; the transmission member 23 includes a first rotating shaft 231 and a second rotating shaft 232 rotatably connected to the connecting socket 21; one end of the first rotating shaft 231 penetrates into the sliding hole 210 and horizontally extends to between the two accommodating grooves 220, the extending end is sleeved with a first gear 2311, and the first gear 2311 is meshed with one of the rack structures 2201; one end of the second rotating shaft 232 penetrates into the sliding hole 210 along the axial direction of the first rotating shaft 231 and is rotatably connected with the extending end of the first rotating shaft 231, a second gear 2321 is sleeved on the penetrating end, and the second gear 2321 is meshed with the other rack structure 2201; the extending end of the first rotating shaft 231 is provided with a first polygonal hole 2312 extending along the axial direction thereof, the penetrating end of the second rotating shaft 232 is provided with a second polygonal hole 2322 extending along the axial direction thereof, the second polygonal hole 2322 is internally provided with a polygonal sliding pin 233, the polygonal sliding pin 233 has a separated state that the whole body is retracted into the second polygonal hole 2322, and also has an embedded state that one end extends into the first polygonal hole 2312.

When the polygonal sliding pin 233 is in the separated state, because the polygonal sliding pin 233 is entirely located in the second polygonal hole 2322, the first rotating shaft 231 and the second rotating shaft 232 lose the constraint of the relative rotational freedom, so that when the polygonal sliding pin 233 is in the separated state, the connecting shaft 221 drives one of the sliding rods 22 to move up and down, the rack structure 2201 arranged thereon drives the second gear 2321 to drive the second rotating shaft 232 to rotate, but the second rotating shaft 232 does not drive the first rotating shaft 231 to rotate, so that the first gear 2311 cannot drive the other rack structure 2201 and the sliding rod 22 to move, that is, in the separated state, only one needle rod 20 is lifted and lowered to perform the sewing operation, which is suitable for the conventional single-needle sewing operation, and when one end of the polygonal sliding pin 233 slides into the first polygonal hole 2312, the second rotating shaft 232 can drive the first rotating shaft 231 to rotate together, so that the two needle bars 20 can perform alternate up-and-down movement to perform overlapped sewing operation, and the conventional sewing and overlapped sewing operation modes can be flexibly switched, so that the equipment utilization rate is improved, and the practicability is high.

Specifically, referring to fig. 6 and 7, the extending end of the first rotating shaft 231 is provided with a shaft hole 2313, a first polygonal hole 2312 is formed at the bottom of the shaft hole 2313, and the first rotating shaft 231 is provided with a first through hole 2314 axially communicated with the first polygonal hole 2312; a shaft sleeve 2323 is arranged at the extending end of the second rotating shaft 232, a second polygonal hole 2322 is arranged at the center of the shaft sleeve 2323, the shaft sleeve 2323 extends into the shaft hole 2313 and is rotatably connected with the shaft hole 2313, and a second through hole 2324 which is communicated with the second polygonal hole 2322 along the axial direction of the second rotating shaft 232 is arranged on the second rotating shaft 232. The shaft sleeve 2323 penetrates into the shaft hole 2313 to form a rotating connection relationship, the structure is simple and reliable, and when the polygonal sliding pin 233 needs to be switched between a separation state and an embedding state, a rod-shaped tool stretches into the first through hole 2314 or the second through hole 2324 to push the sliding pin to move.

Further, referring to fig. 6 and 7, the first through hole 2314 is screwed with the first push rod 2315, one end of the first push rod 2315 abuts against one end of the polygonal sliding pin 233, the second through hole 2324 is screwed with the second push rod 2325, and one end of the second push rod 2325 abuts against the other end of the polygonal sliding pin 233. When the double-needle operation is required, the first mandril 2315 is screwed out, and then the second mandril 2325 is screwed inwards, so that the polygonal sliding pin 233 is pushed to slide into the first polygonal hole 2312 to be in the embedded state, on the contrary, the second mandril 2325 is screwed out, and the first mandril 2315 is screwed inwards, so that the polygonal sliding pin 233 can be integrally pushed into the second polygonal hole 2322 to be completely separated from the first polygonal hole 2312, and the double-needle operation is suitable for single-needle sewing operation and is simple and convenient to operate.

In addition, referring to fig. 7, a reset hole 2316 is formed in the bottom wall of the first polygonal hole 2312, a reset spring 234 is disposed in the reset hole 2316, and one end of the reset spring 234 extends out of the reset hole 2316 and abuts against the end wall of the polygonal sliding pin 233. The return spring 234 can apply an elastic force to the polygonal sliding pin 233 to retract into the second polygonal hole 2322, so that the polygonal sliding pin 233 can be conveniently changed from the engaged state to the disengaged state, and the operation is simple and convenient.

In some possible implementations, referring to fig. 1, 8 to 10, the sewing machine body 1 is further provided with a bird's nest prevention mechanism 3, the bird's nest prevention mechanism 3 has a thread hook 322 extending toward the direction of the presser foot 12, and in the narrowing state, the thread hook 322 extends above the presser foot 12 and swings from the position right below one of the needle bars 20 to the position right below the other needle bar 20, so as to hook and pull the upper threads on the two needle bars 20 together. Because two needle bars 20 are front and back interval distribution, and the preceding, back, left side position of sewing machine are the position that needs occupy in the sewing operation, consequently prevent bird's nest mechanism 3 and need set up the right side position in the aircraft nose in order to avoid influencing the operation, from sewing machine back of narrowing, the line colludes 322 and stretches out to the needle bar 20 in the place ahead and catches on corresponding facial suture after, carry out horizontal swing when following the withdrawal of line colluding 322, thereby reach the below of another needle bar 20 and catch on another facial suture, thereby realize colluding away the facial suture on two needle bars 20 in the lump, the initial position of stylolite produces the bird's nest when avoiding next rise to sew up, thereby improve and sew up the quality.

In some embodiments, referring to fig. 8 and 9, the bird's nest prevention mechanism 3 includes a fixing seat 31, a thread hooking device 32, and a thread clamping spring plate 33; wherein, the fixed seat 31 is fixedly connected on the sewing machine body 1, and one end far away from the presser foot 12 of the band knife is provided with an electromagnetic telescopic rod 311; the thread hooking device 32 is slidably connected to the fixed seat 31 and connected to the output end of the electromagnetic telescopic rod 311, and a thread hook 322 is arranged on the thread hooking device 32; one end of the thread clamping elastic plate 33 is connected with the fixed seat 31, and the other end elastically abuts against the side wall of the thread hook 322 and is used for clamping the upper thread when the thread hook 322 retracts. After the thread hooking device 32 returns the upper thread hooks 322 on the two needle rods 20, because the elastic clamping force exists between the thread hooks 322 and the thread clamping elastic sheet, when the thread hooks 322 retract to be aligned with the elastic pressing end of the thread clamping elastic sheet 33, the upper thread is immediately clamped between the thread hooks 322 and the thread clamping elastic sheet 33, so that the phenomenon that the sewing appearance is influenced because the upper thread falls on the sewing position to form a thread group when the upper thread is cut off by the presser foot 12 with the knife in the next sewing and routing process is avoided.

For example, referring to fig. 10, a slide 312 is disposed on the fixing base 31, and a guide groove 313 is disposed at one end of the slide 312 facing the presser foot 12; the thread hooking device 32 comprises a sliding seat 321 connected to the sliding rail 312 in a sliding manner, a thread hook 322 hinged to the sliding seat 321, and an elastic element 323, wherein one end of the elastic element 323 is connected with the sliding seat 321, and the other end is connected with the thread hook 322; wherein, the side wall of the wire hook 322 departing from the elastic element 323 is provided with a concave guide surface 3221, when the wire hook 322 extends, the concave guide surface 3221 elastically interferes with the groove wall of the guide groove 313 departing from the elastic element 323, and when the wire hook 322 retracts, the concave guide surface 3221 slides out of the guide groove 313, so as to drive the wire hook 322 to swing. It should be understood that the width of the hook 322 is smaller than the width of the guide groove 313, and the width of the position provided with the concave guide surface 3221 is smaller, because the hook 322 is located inside the guide groove 313, when the hook 322 extends until the concave guide surface 3221 is aligned with the groove wall of the guide groove 313, the hook 322 has a larger swing amplitude under the elastic action of the elastic element 323, and when the hook 322 retracts, the hook 322 gradually swings back under the guide action of the concave guide surface 3221 because the concave guide surface 3221 slides out of the guide groove 313, so that the hook position of the hook 322 swings from under one needle rod 20 to under the other needle rod 20, the hooking process is stable and reliable, and the hooking success rate is high.

In some embodiments, referring to fig. 8 and 9, an absorption head 34 is further disposed at an end of the fixing base 31 facing the presser foot 12, a negative pressure air hole 341 is disposed on the absorption head 34, and when the thread hooking device 32 hooks a thread, the thread hook 322 passes through an opening of the negative pressure air hole 341. When the thread clamping spring plate 33 and the thread hook 322 are matched with each other to clamp the upper thread, when the thread is sewn up and laid next time, the upper thread is cut off by the presser foot 12 with the knife, and simultaneously when the needle is closed next time, the thread hook 32 extends out to hook the thread next time, when the thread hook 322 passes through the position of the negative pressure air hole 341 in the thread hooking process, the clamping force of the thread clamping spring plate 33 is lost at the moment because the upper thread (thread end), so that the thread end can be sucked away by the negative pressure air hole 341, and the thread end is prevented from falling randomly.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.