JP2023518323A - 2-needle chainstitch machine - Google Patents

Abstract

The present application provides a two-needle chainstitch sewing machine, including a sewing machine body and a needle assembly, the sewing machine body having a horizontal rotary hook and a presser foot with a knife, and the needle assembly comprising the sewing machine body. and a power input end connected to the power shaft of the sewing machine body, the needle assembly having two needle bars spaced apart in the front-to-rear direction of the sewing machine body, , the frequency of threading by the rotation of the horizontal rotary hook is twice the frequency of vertical movement of the power shaft, and the two needle bars have a needle-stopped state in which both are stopped above the presser foot with the knife. Furthermore, it has a sewing state in which it moves up and down alternately, and in the sewing state, the horizontal rotary hook sequentially hooks the needle threads of the two needle bars. The two-needle chainstitch sewing machine provided in the present application is capable of forming two superimposed suture threads that form an independent chain by matching two needle bars to horizontal rotary hooks, respectively. As a result, the suture strength can be improved, and the two suture threads can be reliably overlapped, resulting in a good appearance quality of the suture. [Selection drawing] Fig. 1

Description

CROSS REFERENCE TO RELATED APPLICATIONS This patent application claims priority from Chinese patent application number “CN202110866206.2” filed on Jul. 29, 2021. The entire disclosure of the prior application is incorporated herein by reference.

The present application belongs to the technical field of sewing machines, and specifically relates to a two-needle chainstitch sewing machine.

At present, two-needle sewing machines are being used more and more frequently when fabricating clothes. A two-needle sewing machine is capable of processing two parallel or overlapping suture structures at once by simultaneously performing a sewing operation with two needle bars arranged side by side. As the needs of customers become more and more diversified, some apparel products are required to be sewn by overlapping two suture threads in order to improve the certainty of stitching. By the way, the conventional two-needle sewing machine has a sewing method using a two-needle single hook, that is, a suture thread formed by one needle movement by synchronous operation of two needles, and two needle threads are sewn simultaneously. A form in which the lower thread is tied in a chain shape is often adopted. Although this method can form two sutures with a good decorative effect, it cannot achieve the reliable effect of two stitches, so the overlap stitching process, which aims to increase the strength of the stitch, is used. not suitable for At present, only the method of repeating the sewing operation twice with a single-needle sewing machine can be adopted. However, since it cannot be guaranteed that the positions of the two sutures are completely overlapped, the appearance quality of the stitching is poor, and the work efficiency is reduced because two stitches are required.

The embodiment of the present application is a two-needle ring for the purpose of improving the reliability of overlapping stitching by a two-needle sewing machine and improving the processing efficiency of clothing and accessories using two overlapping stitching processes. To provide a sewing machine.

To achieve the above objectives, the technical solutions adopted in this application are:
a sewing machine body having a horizontal rotary hook or a half-rotary hook and a presser foot with a knife;
A needle assembly vertically connected to the head of a sewing machine body and having a power input end connected to a power shaft of the sewing machine body, comprising two needle bars spaced apart in the front-rear direction of the sewing machine body. a needle assembly having
Among them, the frequency of threading by the rotation of the horizontal rotary hook is twice the frequency of the vertical movement of the power shaft, and the two needle bars have a needle clamping state in which both are stopped above the presser foot with the knife. To provide a two-needle chainstitch sewing machine which further has a sewing state in which it moves alternately up and down, and in which a horizontal rotary hook sequentially hooks upper threads of two needle bars in the sewing state.

In one possible implementation, the needle assembly
a connecting base provided with a slide hole extending vertically upward from the bottom end, the connecting base being fixedly connected to the head at the top end;
Two slide bars each slidably connected in a slide hole along a vertical direction and having a needle bar detachably connected to each bottom end, one of which is connected to the top end of the slide bar. two slide rods provided with shafts, one end of the connecting shaft passing vertically upward through the top wall of the connecting base and connected to the power shaft;
a transmission member provided in the slide hole and respectively connected to the two slide rods for transmitting reverse driving force between the two slide rods.

In some embodiments, two slide bars are installed facing each other, and the side walls of the two slide bars adjacent to each other resist slidability, and the other side walls are slidable with the hole wall of the slide hole. The side walls of the two slide rods adjacent to each other are both provided with accommodation grooves, and the groove walls of the two accommodation grooves are both provided with a rack structure extending in the vertical direction, and the transmission member is , is horizontally drilled between the two receiving grooves, and both ends are rotatably connected to the hole walls on both sides of the slide hole, respectively, and the transmission member is provided with a gear structure that meshes with the two rack structures, respectively.

Exemplarily, two rack structures are staggered along the horizontal direction, and the transmission member is
A first gear is rotatably connected to the connection base, one end of which is inserted through the slide hole, an extension end extending horizontally between the two receiving grooves, and a first gear meshing with one of the rack structures at the extension end. a fitted first rotating shaft;
It is rotatably connected to the connection base, one end is inserted into the slide hole along the axial direction of the first rotation shaft to form an insertion end, and the insertion end is rotatable to the extension end of the first rotation shaft. and a second rotating shaft having a second gear that meshes with the other rack structure at the insertion end,
Among them, the extension end of the first rotating shaft is provided with a first polygonal hole extending along its axial direction, and the insertion end of the second rotating shaft is provided with a second hole extending along its axial direction. A polygonal hole is provided, a polygonal slide pin is provided in the second polygonal hole, and the polygonal slide pin has a separated state in which the entire polygonal slide pin is recessed inside the second polygonal hole. and a fitted state in which one end extends into the first polygonal hole.

For example, a shaft hole is provided in the extension end of the first rotating shaft, and a first polygonal hole is provided in the hole bottom of the shaft hole. A first through hole communicating with the first polygonal hole is provided along, a shaft sleeve is provided at the insertion end of the second rotating shaft, a second polygonal hole is provided at the center of the shaft sleeve, The shaft sleeve extends into the shaft hole and is rotatably connected to the shaft hole, and the second rotary shaft has a second through hole communicating with the second polygonal hole along its axial direction. be provided.

Further, a first push rod is screwed into the first through hole, one end of the first push rod abuts one end of the polygonal slide pin, and a second push rod is inserted into the second through hole. A rod is threaded and one end of the second push rod abuts the other end of the polygonal slide pin.

In one possible realization, the sewing machine body is further provided with an anti-bird's-nest mechanism having a thread puller hook extending and retracting in the direction of the presser foot with knife, and in the needle clamped state, the thread puller hook is attached to the presser foot with knife. and swings from directly under one of the needle bars to directly under the other needle bar, thereby hooking the needle threads of the two needle bars together.

In some embodiments, the bird's nest prevention mechanism comprises:
a fixed base fixedly connected to the sewing machine body and provided with an electromagnetic telescopic rod at one end away from the presser foot with knife;
a stringing device slidably connected to the fixed base, connected to the output end of the electromagnetic telescopic rod, and having a stringing hook provided thereon;
a thread clamping elastic plate connected to the fixed base at one end and elastically resisting the side wall of the threading hook at the other end for clamping the upper thread when the threading hook is retracted.

Exemplarily, a chute is provided on the fixed base, a guide groove is provided at one end of the chute toward the presser plate with the knife, and the thread pulling device is composed of a slide base slidably connected to the chute, and a hinge to the slide base. A connected stringing hook and an elastic member having one end connected to the slide base and the other end connected to the stringing hook.

The side wall where the stringing hook separates from the elastic member is provided with a concave guide surface. is withdrawn, the concave guide surface slides out of the guide groove, causing the stringing hook to swing.

In some embodiments, a suction head is further provided at one end of the fixing base facing the presser plate with knife, and the suction head is provided with a negative pressure air hole, so that when the string pulling device stretches to pull the string, the string pulling hook passes through the mouth of the negative pressure vent.

Compared with the prior art, the two-needle chainstitch sewing machine of the present application, when the needle assembly is in the needle-locked state, has two needle bars positioned above the presser foot with the knife. In the case of sewing work, the two needle bars of the needle assembly are alternately moved up and down by moving the power shaft up and down. Since this is twice the frequency of the lifting and lowering of the rod, every time the horizontal rotary hook rotates once, the upper thread of one of the descending needle rods is hooked to form a suture chain-like ring. Each of the needle bars can be aligned with the horizontal rotary hook to independently form two superimposed suture threads that form a chain. Compared to the method of simultaneously hooking the two needles, the present application is closer to the overlapped seams by two repeated stitches, the stitching strength is high, the stitching is firm and secure, and the two needle bars are installed back and forth. , it is possible to ensure reliable superimposition of the two sutures, so that the appearance quality of the suturing can be improved.

1 is a schematic front view of a two-needle chain stitch sewing machine provided in an embodiment of the present application; FIG. FIG. 4 is a schematic diagram of the structure of the two needle chain stitch sewing machine provided in the embodiment of the present application, in which the two needle bars are alternately aligned with the horizontal rotary shuttle in the sewing state; FIG. 4 is a schematic diagram of the structure of the two needle chain stitch sewing machine provided in the embodiment of the present application, in which the two needle bars are alternately aligned with the horizontal rotary shuttle in the sewing state; FIG. 4 is a structural schematic view of the needle assembly used in the embodiment of the present application in a needle-stopped state; It is a schematic diagram of the three-dimensional structure of two slide bars used in the embodiments of the present application. It is a schematic diagram of an exploded structure of a transmission member used in the embodiments of the present application. It is the schematic of the cross-sectional structure of the transmission member used in the Example of this application. FIG. 3 is a schematic diagram of the three-dimensional structure of the bird's nest prevention mechanism used in the embodiments of the present application; It is the schematic of the bottom structure (part) of the bird's nest prevention mechanism used in the Example of this application. FIG. 4 is a schematic diagram of a planar structure (partial) when the stringing hook of the bird's nest prevention mechanism used in the embodiments of the present application is pulled out; It is a schematic diagram of a three-dimensional structure of a presser metal with a knife used in the examples of the present application.

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be described in more detail below in conjunction with the drawings and examples. It should be understood that the specific examples described herein are used only for the purpose of interpreting the present application and are not intended to limit the present application.

Note that the rotary hook is a core member of the sewing machine, and hooks the thread loop of the upper thread with the tip of the hook, widens the thread loop, and guides the thread loop around the bobbin to form a chain stitch. A rotary hook that rotates horizontally is called a horizontal rotary hook, and a rotary hook that rotates vertically is called a vertical rotary hook. ) is provided. When moving the thread in suturing, the end of the thread that was generated when the needle was fastened in the previous suture is cut by the scalpel 121, so that the end of the thread and the entanglement of the thread at the starting point of the suturing position can be avoided. . These structures are often provided in sewing machines having a bird's nest (thread entanglement) prevention function, and will not be described in detail here.

1 to 4 and 11 together, the two-needle chainstitch sewing machine provided in the present application will be described below. The two-needle chainstitch sewing machine includes a sewing machine body 1 and a needle assembly 2 . A sewing machine body 1 has a horizontal rotary hook 11 or a half-rotary hook and a presser foot 12 with a knife. The needle assembly 2 is vertically connected to the head of the sewing machine body 1 and its power input end is connected to the power shaft rod 13 of the sewing machine body 1 . The needle assembly 2 has two needle bars 20 spaced apart in the front-rear direction of the sewing machine body 1 . Of these, the frequency of threading by rotation of the horizontal rotary hook 11 is twice the frequency of vertical movement of the power shaft rod 13 . The two needle bars 20 have a needle-fastened state in which both are stopped above the presser foot 12 with a knife, and further have a sewing state in which they alternately move up and down. In the sewing state, the horizontal rotary hook 11 sequentially hooks the upper threads of the two needle bars 20. - 特許庁

The power input end of the needle assembly 2 is directly connected to one of the needle bars 20, and is also a member having a reverse transmission function (reverse power due to meshing of gears, rocking movement whose center is connected by a hinge). Alternating movement of the two needle bars 20 up and down can be achieved by indirectly connecting the needle bar 20 to the other needle bar 20 via the opposite movement occurring at both ends of the bar.

The operating principle of the two-needle chainstitch sewing machine provided in this embodiment is as follows. By setting the central axis of rotation of the rotary hook on the vertical bisector of the two needle bars 20, the upper threads (thread loops) of the two needle bars 20 are both at the blade point of the horizontal rotary hook 11. It should be understood that hooking can be ensured. When one needle bar 20 descends to a lower position, the blade point of the horizontal rotary hook 11 rotates to a position where it is aligned with the needle bar 20, thereby hooking the upper thread of the needle bar 20 and causing the horizontal rotary hook 11 to move halfway. Releases the upper thread to form a suture chain loop when rotated more than one turn. When the other needle bar 20 descends to the lower position, the blade point of the horizontal rotary hook 11 rotates again to the position where it is aligned with the other needle bar 20, and the upper thread of the other needle bar 20 is hooked for the next sewing chain. form a ring and repeat like this. Although the same bobbin thread (thread wound around the bobbin of the horizontal rotary hook 11) is used, the needle thread of the two needle bars 20 can be formed into two independent suture threads (chain-like), respectively, so that a single needle thread is used. To form overlapping stitches that have the same effect as repeating sewing twice along the same path with a sewing machine.

In the two-needle chain stitch sewing machine provided in this embodiment, when the needle assembly 2 is in the needle-locked state, all the two needle bars 20 are positioned above the presser foot 12 with the knife. Therefore, it is possible to easily put and replace the piece of cloth. In the case of suturing work, the two needle bars 20 of the needle assembly 2 are alternately moved up and down by moving the power shaft 13 up and down. Since the frequency of threading by the rotation of the horizontal rotary hook 11 is twice the frequency of the lifting and lowering of the power shaft rod 13, one needle bar 20 is lowered each time the horizontal rotary hook 11 rotates once. By hooking the needle thread to form a suture chain-like ring, the two needle bars 20 are aligned with the horizontal rotary hook 11 and form two superimposed suture threads forming an independent chain. be able to. Compared to the method in which the two needle bars 20 operate synchronously and the bobbin thread is threaded at the same time, the method of the present invention is closer to the overlapped stitches by two repeated stitches, and the stitching strength is high, and the stitching is firm and reliable. is. Since the two needle bars 20 are installed one behind the other, it is possible to ensure that the two suture threads are reliably overlapped, thereby improving the appearance quality of the stitching.

In some embodiments, referring to FIG. 4, the needle assembly 2 includes a connecting base 21, two slide rods 22 and a transmission member 23. As shown in FIG. Wherein, the connection base 21 is provided with a slide hole 210 extending vertically upward from the bottom end, and the top end of the connection base 21 is fixedly connected to the head. The two slide bars 22 are slidably connected in the slide holes along the vertical direction, and the needle bars 20 are detachably connected to the bottom ends thereof. A connection shaft 221 is provided at the top end of one of the slide rods 22 , and one end of the connection shaft 221 extends vertically upward through the top wall of the connection base 21 and is connected to the power shaft rod 13 . The transmission member 23 is installed in the slide hole 210 and connected to the two slide rods 22 respectively, and is used to transmit reverse driving force between the two slide rods 22 .

Here, the two slide bars 22 are installed facing each other, and the side walls of the two slide bars 22 close to each other are slidably resisted, and the other side walls are slidable with the hole wall of the slide hole 210. resist. Adjacent sidewalls of the two slide rods 22 are both provided with housing grooves 220 , and groove walls of the two housing grooves 220 are both provided with rack structures 2201 extending in the vertical direction. The transmission member 23 is horizontally inserted between the two receiving grooves 220 and both ends thereof are rotatably connected to both side walls of the slide hole 210 . The transmission member 23 is provided with a gear structure 230 that meshes with the two rack structures 2201 respectively.

The slide hole 210 may be a rectangular hole, a round hole, or an elliptical hole. The slide rods 22 are slidably connected in the slide holes 210 at the same time, and the two slide rods 22 are relatively slid by the relative sliding of the bonding surfaces. When the power shaft 13 drives the connecting shaft 221 to descend, the corresponding slide rod 22 descends together. The other slide bar 22 is lifted together to achieve the two needle bars 20 moving alternately up and down, and the transmission is smooth and reliable.

In this embodiment, referring to FIGS. 4-7, the two rack structures 2201 are staggered along the horizontal direction. The transmission member 23 includes a first rotating shaft 231 and a second rotating shaft 232 rotatably connected to the connection base 21 . One end of the first rotary shaft 231 is inserted through the slide hole 219 and extends horizontally between the two accommodation grooves 220 to form an extension end. A first gear 2311 that meshes with one of the rack structures 2201 is fitted to the extension end. One end of the second rotating shaft 232 is inserted into the slide hole 210 along the axial direction of the first rotating shaft 231 to form an insertion end. The insertion end is rotatably connected to the extension end of the first rotating shaft 231 , and a second gear 2321 meshing with the other rack structure 2201 is fitted to the insertion end. Among them, the extension end of the first rotating shaft 231 is provided with a first polygonal hole 2312 extending along its axial direction, and the insertion end of the second rotating shaft 232 is provided along its axial direction. A second polygonal hole 2322 is provided extending therethrough. A polygonal slide pin 233 is provided in the second polygonal hole 2322. The polygonal slide pin 233 has a separated state in which the entire polygonal slide pin 233 is recessed inside the second polygonal hole 2322, and one end is It has a mating state that extends into the first polygonal hole 2312 .

The polygonal slide pin 233 synchronously rotates the first rotating shaft 231 and the second rotating shaft 232 in accordance with the polygonal holes (the first polygonal hole 2312 and the second polygonal hole 2322). be able to. When the polygonal slide pin 233 is in the separated state, the polygonal slide pin 233 is wholly inside the second polygonal hole 2322 , so that there is a gap between the first rotating shaft 231 and the second rotating shaft 232 . Constraints on relative rotational degrees of freedom are lost. At this time, in the process of lifting and lowering one of the slide rods 22 by the connecting shaft 221, the second gear 2321 can be driven by the rack mechanism 2201 provided thereon to rotate the second rotating shaft 232. can. However, since the second rotating shaft 232 does not rotate the first rotating shaft 231 , the first gear 2311 cannot move the other rack structure 2201 and the other slide rod 22 . That is, in the separated state, only one needle bar 20 moves up and down to perform the sewing work. The separated state is suitable for normal single-needle suturing operations. And when one end of the polygonal slide pin 233 slides into the first polygonal hole 2312 , the second rotating shaft 232 can rotate the first rotating shaft 231 together, thus the two needle bars 20 can alternately move up and down to perform overlapping stitching operations. With the structure provided in this embodiment, the sewing machine can flexibly switch between normal stitching and overlapping stitching work modes, thereby improving the utilization rate of equipment and having high practicability.

Specifically, referring to FIGS. 6 and 7, a shaft hole 2313 is provided at the extension end of the first rotating shaft 231, and a first polygonal hole 2312 is provided at the bottom of the shaft hole 2313, The first rotating shaft 231 is provided with a first through hole 2314 that communicates with the first polygonal hole 2312 along its axial direction. A shaft sleeve 2323 is provided at the insertion end of the second rotating shaft 232, a second polygonal hole 2322 is provided in the center of the shaft sleeve 2323, the shaft sleeve 2323 extends into the shaft hole 2313, and the shaft hole 2313 is rotatably connected. The second rotating shaft 232 is provided with a second through hole 2324 that communicates with the second polygonal hole 2322 along its axial direction. A rotational connection is formed by inserting the shaft sleeve 2323 into the shaft hole 2313, and the structure is simple and reliable. When it is necessary to switch the polygonal slide pin 233 between the separated state and the mated state, a rod-shaped tool extends into the first through hole 2314 or the second through hole 2324 to move the polygonal slide pin 233. Let it be.

6 and 7, a first push rod 2315 is screwed into the first through hole 2314, and one end of the first push rod 2315 abuts one end of the polygonal slide pin 233. . A second push rod 2325 is screwed into the second through hole 2324 , and one end of the second push rod 2325 contacts the other end of the polygonal slide pin 233 . If it is necessary to work with a twin needle, the first pushrod 2315 is unscrewed and then the second pushrod 2325 is screwed inward to open the first polygonal hole 2312 until mated. Push the polygonal slide pin 233 so that it slides inward. Conversely, when it is necessary to perform a single-needle operation, the second push rod 2325 is unscrewed and the first push rod 2315 is screwed inward, so that the entire polygonal slide pin 233 is pulled into the second polygonal shape. By pushing it into the hole 2322 and completely separating it from the first polygonal hole 2312, it is suitable for suture work with a single needle, and the operation is simple and convenient.

7, a return hole 2316 is provided in the bottom wall of the first polygonal hole 2312, a return spring 234 is provided in the return hole 2316, and one end of the return spring 234 extends from the return hole 2316. It extends and abuts the end walls of the polygonal slide pin 233 . The return spring 234 can apply an elastic force to the polygonal slide pin 233 to retract toward the inside of the second polygonal hole 2322, thereby converting the polygonal slide pin 233 from the fitted state to the separated state. , easy and convenient to operate.

In some possible implementations, see FIGS. 1 and 8-10, the sewing machine body 1 is provided with a bird's nest prevention mechanism 3 having a stringing hook 322 extending and retracting in the direction of the presser foot with knife 12. Further provided. In the needle clamping state, the thread pulling hook 322 extends above the presser metal with knife 12 and swings from directly below one of the needle bars 20 to directly below the other needle bar 20 to hold two needles. The upper thread of the bar 20 is hooked together. The two needle bars 20 are spaced apart from each other in the front and rear direction, but the front, rear and left sides of the sewing machine are all positions that need to be occupied for sewing work, so they do not interfere with operation. As shown, the bird's nest prevention mechanism 3 must be installed on the right side of the head. The sewing machine stops the needle, and the thread pulling hook 322 extends directly below the needle bar 20 in front to hook the corresponding upper thread. By reaching directly below the needle bar 20 and hooking the other needle thread, it is possible to hook the needle threads of the two needle bars 20 together, and when sewing is started next time, the bird's nest is at the start position of the suture thread. , thereby improving suture quality.

In some embodiments, referring to Figures 8 and 9, the bird's nest prevention mechanism 3 includes a fixed base 31, a thread pulling device 32, and an elastic plate 33 for thread clamping. Among them, the fixed base 31 is fixedly connected to the sewing machine main body 1 and has an electromagnetic telescopic rod 311 at one end remote from the presser plate with knife 12 . The stringing device 32 is slidably connected to the fixed base 31 and connected to the output end of the electromagnetic telescopic rod 311 , and the stringing device 32 is provided with a stringing hook 322 . The elastic plate 33 for thread clamping has one end connected to the fixed base 31 and the other end elastically resists the side wall of the thread pulling hook 322 and is used to clamp the needle thread when the thread pulling hook 322 is retracted. be done. When the thread pulling device 32 pulls back the upper thread from the two needle bars 20, the thread pulling hook 322 is pulled back for thread clamping because of the elastic pinching force between the thread pulling hook 322 and the elastic plate 33 for thread clamping. As soon as the upper thread is retracted until it is aligned with the urging end of the elastic plate 33, the upper thread is clamped between the thread pulling hook 322 and the elastic plate 33 for thread clamping, thereby facilitating the process of moving the thread in the next stitch. When the thread is cut by a presser foot 12 with a scalpel, it is possible to prevent the upper thread from dropping to the sewing position and forming thread entanglement to affect the appearance of sewing.

By way of example, referring to FIG. 10, a chute 312 is provided on the fixed base 31, and a guide groove 313 is provided at one end of the chute 312 toward the presser plate 12 with knife. The stringing device 32 includes a slide base 321 slidably connected to the chute 312 , a stringing hook 322 hingedly connected to the slide base 321 , and an elastic member 323 . The elastic member 323 has one end connected to the slide base 321 and the other end connected to the stringing hook 322 . A concave guide surface 3221 is provided on the side wall where the stringing hook 322 separates from the elastic member 323 . When the stringing hook 322 extends, the concave guide surface 3221 elastically resists the groove wall of the guide groove 313 away from the elastic member 323 . When the stringing hook 322 is retracted, the concave guide surface 3221 slides out of the guide groove 313, causing the stringing hook 322 to swing. It should be understood that the width of the stringing hook 322 is smaller than the width of the guide groove 313, and the width at the position where the concave guide surface 3221 is provided is smaller. Since the stringing hook 322 is located inside the guide groove 313, when the stringing hook 322 extends to the concave guide surface 3221 and becomes aligned with the groove wall of the guide groove 313, the elastic action of the elastic member 323 causes the string to be pulled out. The pull hook 322 has a large swing width. When the stringing hook 322 is retracted, the concave guide surface 3221 slides out of the guide groove 313, so that the stringing hook 322 gradually turns back due to the guiding action of the concave guide surface 3221, thereby reaching the stringing position of the stringing hook 322. One needle bar 20 swings downward from the other needle bar 20, the threading process is stable and reliable, and the success rate of threading is high.

In some embodiments, referring to FIGS. 8 and 9, a suction head 34 is further provided at one end of the fixed base 31 toward the presser plate 12 with a knife, and the suction head 34 is provided with a negative pressure vent 341 . When the stringing device 32 is stretched to pull the string, the stringing hook 322 passes through the opening of the negative pressure vent 341 . The elastic plate 33 for pinching the thread and the thread pulling hook 322 together hold the needle thread. When the thread is stopped, the threading device 32 is extended to perform the next threading. In this thread pulling process, when the thread pulling hook 322 passes through the position of the negative pressure vent 341, the upper thread (thread end) is no longer clamped by the elastic plate 33 for clamping the thread at this time, so that the negative pressure vent is closed. 341 can be sucked, thereby avoiding the free fall of the thread end.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. should be contained within

1... Sewing machine body 11... Horizontal rotary hook 12... Presser plate with knife 121... Knife 13... Power shaft 2... Needle assembly 20... Needle bar, 21... Connection base, 210... Slide hole, 22... Slide bar, 220... Accommodating groove, 2201... Rack structure, 221... Connection shaft, 23... Transmission Member 230... Gear structure 231... First rotary shaft 2311... First gear 2312... First polygonal hole 2313... Shaft hole 2314... First through hole, 2315... First push rod, 2316... Return hole, 232... Second rotating shaft, 2321... Second gear, 2322... Second multi Square hole 2323... Shaft sleeve 2324... Second through hole 2325... Second push rod 233... Polygonal slide pin 234... Return spring 3... Bird's nest prevention mechanism, 31... Fixed base, 311... Electromagnetic telescopic rod, 312... Chute, 313... Guide groove, 32... String pulling device, 321... Slide base, 322 ... String pulling hook, 3221 ... Concave guide surface, 323 ... Elastic member, 33 ... Elastic plate for thread clamping, 34 ... Suction head, 341 ... Negative pressure vent.

Claims (9)

a sewing machine body having a horizontal rotary hook and a presser foot with a knife;
A needle assembly vertically connected to the head of the sewing machine body and having a power input end connected to a power shaft of the sewing machine body, comprising two needle assemblies spaced apart in the longitudinal direction of the sewing machine body. a needle assembly having a needle bar;
Among them, the frequency of threading by the rotation of the horizontal rotary hook is twice the frequency of the vertical movement of the power shaft, and the two needle bars are needles stopped above the presser foot with the knife. It has a stopped state and further has a sewing state in which it alternately moves up and down, and in said sewing state, said horizontal rotary hook sequentially hooks needle threads of said two needle bars,
The needle assembly is
a connection base provided with a slide hole extending vertically upward from a bottom end, the top end of which is fixedly connected to the head;
Two slide bars each slidably connected in the slide hole along the vertical direction and having the needle bar detachably connected to the bottom end thereof, one of which is the top end of the slide bar. two slide rods each provided with a connection shaft, one end of the connection shaft extending vertically upward through the top wall of the connection base and connected to the power shaft;
a transmission member provided in the slide hole and connected to each of the two slide rods for transmitting reverse driving force between the two slide rods;
A two-needle chain stitch sewing machine characterized by: 2, the two slide bars are installed facing each other, the adjacent side walls of the two slide bars are slidably resisted, and the other side walls are slidably resisted by the hole wall of the slide hole; Adjacent side walls of the slide bar of the book are both provided with a receiving groove, groove walls of the two receiving grooves are both provided with a rack structure extending in a vertical direction, and the transmission member includes two The transmission member is horizontally drilled between the two receiving grooves, and both ends are rotatably connected to the hole walls on both sides of the slide hole, and the transmission member has a gear structure that meshes with the two rack structures to be
The two-needle chainstitch sewing machine according to claim 1, characterized in that: The two rack structures are staggered along the horizontal direction, and the transmission member is
It is rotatably connected to the connection base, one end is inserted through the slide hole, and an extension end is formed by horizontally extending between the two accommodation grooves, and the extension end is engaged with one of the rack structures. a first rotating shaft fitted with a first gear;
It is rotatably connected to the connection base, one end is inserted into the slide hole along the axial direction of the first rotating shaft to form an insertion end, and the insertion end is an extension of the first rotating shaft. a second rotating shaft rotatably connected to one end and having a second gear fitted to the insertion end to mesh with the other rack structure;
Among them, the extending end of the first rotating shaft is provided with a first polygonal hole extending along its axial direction, and the insertion end of the second rotating shaft is provided with extending along its axial direction. A second polygonal hole is provided, a polygonal slide pin is provided in the second polygonal hole, and the polygonal slide pin is entirely recessed inside the second polygonal hole. having a separated state and further having a fitted state in which one end extends into the first polygonal hole;
The two-needle chainstitch sewing machine according to claim 2, characterized in that: A shaft hole is provided in the extension end of the first rotating shaft, and the first polygonal hole is provided in the hole bottom of the shaft hole. A first through hole communicating with the first polygonal hole is provided, a shaft sleeve is provided at the insertion end of the second rotating shaft, and the second polygonal hole is provided at the center of the shaft sleeve. , the shaft sleeve extends into the shaft hole and is rotatably connected to the shaft hole, and the second rotary shaft communicates with the second polygonal hole along its axial direction. a second through hole is provided;
The two-needle chainstitch sewing machine according to claim 3, characterized in that: A first push rod is screwed into the first through hole, one end of the first push rod abuts one end of the polygonal slide pin, and a second push rod is inserted into the second through hole. is screwed, and one end of the second push rod abuts the other end of the polygonal slide pin,
The two-needle chainstitch sewing machine according to claim 4, characterized in that: The sewing machine main body is further provided with a bird's nest prevention mechanism having a thread puller hook extending and contracting in the direction of the presser foot with knife. By extending and swinging from directly under one of the needle bars to directly under the other needle bar, the upper threads of the two needle bars are hooked together.
The two-needle chainstitch sewing machine according to any one of claims 1 to 5, characterized in that: The bird's nest prevention mechanism includes:
a fixed base fixedly connected to the sewing machine body and provided with an electromagnetic telescopic rod at one end remote from the presser foot with a knife;
a stringing device slidably connected to the fixed base, connected to the output end of the electromagnetic telescopic rod, and having the stringing hook provided thereon;
an elastic plate for thread clamping, one end of which is connected to the fixed base and the other end of which elastically resists the side wall of the threading hook for clamping the needle thread when the threading hook is retracted; including,
The two-needle chainstitch sewing machine according to claim 6, characterized in that: A chute is provided on the fixed base, and a guide groove is provided at one end of the chute toward the presser metal with a knife. The stringing hook connected by a hinge, and an elastic member having one end connected to the slide base and the other end connected to the stringing hook,
A concave guide surface is provided on the side wall where the stringing hook is separated from the elastic member, and when the stringing hook is pulled out, the concave guide surface is elastically attached to the groove wall of the guide groove which is separated from the elastic member. resisting and when the stringing hook is retracted, the concave guide surface slides out of the guide groove, causing the stringing hook to swing;
The two-needle chainstitch sewing machine according to claim 7, characterized in that: A suction head is further provided at one end of the fixed base facing the presser plate with knife, and the suction head is provided with a negative pressure air hole. pass through the mouth of the negative pressure vent,
The two-needle chainstitch sewing machine according to claim 7, characterized in that:

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