CN107142624B - Sewing machine and sewing machine thread trimming mechanism - Google Patents

Abstract

The invention provides a thread trimming mechanism for a sewing machine and a sewing machine including the thread trimming mechanism. The fixed knife of the thread trimming mechanism is fixed on the casing of the sewing machine; its power mechanism is the lower shaft of the sewing machine, and a rotating part is fixed on the lower shaft; the movable knife is installed on the movable knife holder, which is rotatably arranged Inside the sewing machine casing; its transmission mechanism includes a gear 1, a second gear, a crank and a connecting rod; the gears are set on the lower shaft, located on one side of the rotating member, and can rotate relative to the lower shaft; the gears are set on the lower shaft. The external teeth of the first gear mesh with the external teeth of the second gear. The crank is connected to the second gear through the crank shaft. One end of the connecting rod is connected to the crank, and the other end is connected to the movable tool rest. The first gear corresponds to the rotating member. A matching engagement structure is provided for mutual engagement and separation under the action of the clutch mechanism. The thread trimming mechanism is simple in structure, low in cost and good in stability.

Description

Sewing machine and sewing machine thread trimming mechanism

technical field

The invention relates to a sewing machine, in particular to a thread trimming mechanism of the sewing machine.

Background technique

The sewing machine needs to trim the thread after completing a sewing operation, that is, to cut the thread connecting the needle and the sewing material. The traditional sewing machine itself does not have the thread trimming function, and the operator needs to use scissors to complete the thread trimming operation. In view of the inconvenience of manual thread trimming, the R&D personnel added the thread trimming function to the sewing machine. This kind of thread trimming mechanism includes a fixed knife fixedly installed on the casing, and a movable knife that can rotate back and forth. Its working principle is: when the thread needs to be trimmed, the clutch is driven by the driving device (such as an electromagnet, a pneumatic cylinder, etc.) to connect the thread trimming mechanism with the lower shaft of the sewing machine. The cam transmits the motion of the lower shaft to the thread trimming drive assembly according to a certain time sequence, and the thread trimming drive assembly drives the movable knife to engage with the fixed knife to realize thread trimming. After the thread trimming action is completed, the thread trimming drive assembly is reset to its original position under the action of a cam or a spring, and is ready for the next thread trimming. The thread trimming mechanism performs the thread trimming operation again and again in this way.

However, the above thread trimming mechanism has some defects. For example, the thread trimming mechanism requires a cam part with a complex trajectory, and the accuracy of the cam trajectory has a great influence on the reliability of the thread trimming function; Multiple parts and complex structure.

SUMMARY OF THE INVENTION

In view of the above-mentioned shortcomings of the prior art, the present invention at least aims to provide a thread trimming mechanism for a sewing machine and a sewing machine including the thread trimming mechanism, so as to simplify the structure of the thread trimming mechanism and improve the reliability of the thread trimming function.

In order to achieve the above purpose and other related purposes, in one embodiment, the present invention provides a sewing machine thread trimming mechanism, including a fixed knife, a moving knife, a power mechanism, a transmission mechanism and a clutch mechanism; the fixed knife is fixed on the sewing machine casing upper; the power mechanism is the lower shaft of the sewing machine, and a rotating member is fixed on the lower shaft; the movable knife is installed on the movable knife rest, and the movable knife rest is rotatably arranged in the casing of the sewing machine; the transmission mechanism It includes gear 1, gear 2, crank and connecting rod; the gear is set on the lower shaft, located on one side of the rotating part, and can rotate relative to the lower shaft; the outer teeth of gear 1 and the outer teeth of gear 2 The teeth mesh, the crank is connected with the second gear through the crank shaft, one end of the connecting rod is connected with the crank, and the other end is connected with the movable tool rest; They engage and separate from each other under the action of the clutch mechanism.

In one embodiment, the movable tool rest is rotatably arranged on the shaft sleeve of the lower shaft.

In one embodiment, the clutch mechanism includes a driving device and a clutch, the driving device drives the clutch to move back and forth along the lower shaft, and the clutch drives the first gear to engage and disengage from the rotating member.

In one embodiment, the driving device is an electromagnet, a pneumatic cylinder, a hydraulic cylinder or an electric motor.

In one embodiment, the clutch is a shift fork, one end of the shift fork is a fork head, which is connected with the first gear, and the other end is connected with the driving device, which is used to drive the first gear and rotate under the driving of the driving device. Parts engagement and disengagement.

In one embodiment, the clutch includes a push plate and a return spring, one end of the push plate is connected to the driving device, and the other end is located on the side of the first gear facing away from the rotating member, for pushing the gear One is engaged with the rotating member, and the return spring is used for the separation of the first gear and the rotating member.

In one embodiment, the engagement structure includes a push pin and a push portion respectively disposed on the first gear and the rotating member, the push pin extends from the gear one to the rotating member in the axial direction, or extends from the rotating member to the gear one in the axial direction Accordingly, the push portion extends radially outward from the rotating member or gear one, so that when the gear one is engaged with the rotating member, the gear one rotates synchronously with the rotating member due to the contact between the push portion and the push pin.

In one embodiment, the clutch includes a push plate, one end of the push plate is connected with the driving device, and the other end is located on the side of the first gear facing away from the rotating member, and the engagement structure includes a The axial pin hole on the first gear, a push pin is movably arranged in the pin hole, one end of the push pin passes through the pin hole and is located between the push plate and the first gear, and a push portion extends radially outward from the rotating part, and the first gear is connected to the first gear. When the rotating member is engaged, the push plate pushes the push pin to the rotating member, so that the push pin contacts the push portion, so that the first gear rotates synchronously with the rotating member; Return spring for reset.

In one embodiment, the present invention also provides a sewing machine comprising any of the aforementioned sewing machine thread trimming mechanisms.

As described above, one or more embodiments of the present invention have the following beneficial effects: by replacing the prior art in which the cam is matched with the thread trimmer drive assembly, the structure of the thread trimmer mechanism is more Simple, lower cost and better stability, while achieving the thread trimming effect, the thread trimming function is more reliable.

Description of drawings

FIG. 1 is a schematic structural diagram of an embodiment of the thread trimming mechanism of the sewing machine of the present invention.

Component label description

1 Chassis

2 moving knives

3 fixed knife

4 moving tool holder

5 Tool holder pressure plate

6 Lower axle front bushing

7 Lower shaft

8 cams

9 gear one

10 Fork

11 Nuts

12 connecting rod

13 crank

14 Crank bushing

15 gear two

16 Solenoid core

17 Electromagnet Bracket

18 Electromagnets

19 Spring

20 push pins

Detailed ways

The embodiments of the present invention are described below by specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

See Figure 1. It should be noted that the structures, proportions, sizes, etc. shown in the accompanying drawings of this specification are only used to cooperate with the contents disclosed in the specification, so as to be understood and read by those who are familiar with the technology, and are not used to limit the implementation of the present invention. Therefore, it does not have technical substantive significance, and any modification of structure, change of proportional relationship or adjustment of size should still fall within the scope of the present invention without affecting the effect that the present invention can produce and the purpose that can be achieved. The scope of the disclosed technical content can be covered. At the same time, the terms such as "up", "down", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and clarity, and are not used to limit this specification. The implementable scope of the invention, and the change or adjustment of the relative relationship thereof, shall also be regarded as the implementable scope of the present invention without substantially changing the technical content.

The thread trimming mechanism of the sewing machine of the present invention mainly includes a moving knife, a fixed knife, a power mechanism for providing power for the rotation of the moving knife, a transmission mechanism for transmitting the power of the power mechanism to the moving knife and causing the moving knife to reciprocate, and a transmission mechanism and the power A clutch mechanism that engages and disengages the mechanism. Engagement here refers to establishing a power transmission relationship between the two mechanical structures, while disengagement refers to breaking the above power transmission relationship. The power mechanism is the lower shaft of the sewing machine, and the lower shaft is fixed with a rotating member that rotates synchronously with the lower shaft; the clutch mechanism includes a driving device and a clutch.

FIG. 1 shows an embodiment of the thread trimming mechanism of the sewing machine of the present invention.

In this embodiment, the power mechanism is the lower shaft 7 of the sewing machine, which provides power for the rotation of the movable knife.

As shown in Figure 1, the fixed knife 3 is fixed on the casing 1 of the sewing machine, the movable knife 2 is installed on the movable knife rest 4, and the movable knife rest 4 is sleeved on the lower shaft front sleeve 6 of the lower shaft 7, and the movable knife rest 4 can be rotated relative to the front bushing 6 of the lower axle. The tool holder pressing plate 5 restricts the movable tool holder 4 on the front bushing 6 of the lower shaft. Although the movable tool rest 4 in this embodiment adopts the form in which the front shaft sleeve 6 is the rotating shaft, in other embodiments, other shafts, such as a shaft provided separately for it, can also be used as the rotating shaft, or in other ways. It is rotatably arranged in the casing 1 .

As shown in FIG. 1 , in this embodiment, the rotating member on the lower shaft adopts the cam 8 , and the transmission mechanism includes the first gear 9 , the second gear 15 , the crank 13 and the connecting rod 12 . The cam 8 is fixed on the lower shaft 7 and can rotate synchronously with the lower shaft 7. The gear one 9 is sleeved on the lower shaft 7 and is located on one side of the cam 8, but the gear one 9 is rotatable relative to the lower shaft 7, that is, the gear one 9 is rotatable relative to the lower shaft 7. When not engaged with the cam 8, it does not rotate with the rotation of the lower shaft 7. The external teeth of the first gear 9 mesh with the external teeth of the second gear 15 . The crank 13 is connected with one end of the connecting rod 12 to form a crank connecting rod mechanism. The other end of the connecting rod 12 is connected to the movable tool rest 4 . The crank 13 is connected with the second gear 15 through a crank shaft, and the crank shaft passes through the crank shaft sleeve 14 fixed on the casing 1 .

As shown in FIG. 1 , the clutch mechanism of this embodiment specifically includes a shift fork 10 and an electromagnet 18 , wherein the electromagnet 18 is a driving device, and the shift fork 10 is a clutch. The casing 1 is provided with an electromagnet support 17 , and the electromagnet 18 is provided on the electromagnet support 17 . One end of the electromagnet core 16 in the electromagnet 18 is connected with the shift fork 10, the nut 11 is used to fix the shift fork 10 on the electromagnet core 16 by means of screw connection, and the other end is connected with a spring 19, and the spring 19 is used for the electromagnet Reset of core 16. The fork head of the shift fork 10 is connected to the gear one 9, for example, the fork head of the shift fork 10 can be arranged in a slot (not shown) on the gear one 9, or any other method that can maintain connection with the gear one and A connection that does not hinder the rotation of the gear. The first gear 9 and the cam 8 are provided with corresponding engaging structures for engaging and disengaging with each other under the action of the clutch mechanism. In the embodiment shown in FIG. 1 , the first gear 9 is provided with a push pin 20 in the axial direction, and the cam 8 is correspondingly provided with a push portion radially. The sides protrude and extend radially. In the state where the gear one 9 is separated from the cam 8, the push pin 20 and the push part do not contact each other, the gear one 9 does not rotate with the rotation of the cam 8, and in the state where the gear one 9 is engaged with the cam 8, with the rotation of the cam 8 Rotating, the push part contacts the push pin 20, pushes the push pin 20, and then drives the gear one 9 and the cam 8 to rotate synchronously. In other embodiments, the push pin can also be arranged on the cam, the push portion can be arranged on the first gear, and the push portion is driven by the push pin.

The working process of the thread trimming mechanism will be described below based on the embodiment shown in FIG. 1 . When the thread trimming is not required, the gear one 9 and the cam 8 are separated from each other, and the gear one 9 does not rotate with the rotation of the lower shaft 7 . When thread trimming is required, the control system issues a thread trimming command, the electromagnet 18 is activated, the electromagnet core 16 pushes the shift fork 10 to move forward along the lower shaft 7, and the shift fork 10 pushes the gear one 9 to engage with the cam 8. The first part pushes the push pin 20, so that the gear one 9 rotates together with the lower shaft 7 under the drive of the cam 8, the gear one 9 further drives the gear two 15 to rotate, and the gear two 15 drives the crank 13 to rotate, thereby driving the connecting rod 12 to reciprocate, connecting the The reciprocating motion of the rod 12 drives the movable knife rest 4 together with the movable knife 2 to reciprocate and rotate, and cooperates with the fixed knife 3 to complete the thread trimming action during the rotation. After the thread trimming is completed, the moving knife 2 returns to the initial position driven by the connecting rod 12, and the electromagnet core 16 is reset, which drives the shifting fork 10 to reset, and then drives the gear one 9 to separate from the cam 8, waiting for the next thread trimming operation.

It should be further explained that although the clutch mechanism used in the embodiment shown in FIG. 1 uses an electromagnet as a driving device and a shift fork as a clutch, those skilled in the art can understand that any other suitable driving device and clutch can be used to replace above options. Likewise, the engagement structure of the first gear and the cam is not limited to the foregoing embodiment. For example, the driving device may be replaced by an electromagnet with a pneumatic cylinder, a hydraulic cylinder or an electric motor or the like. For example, the clutch can adopt the following structure, the shift fork is replaced with a push plate arranged on one side of the gear, which is used to push the gear one to engage with the cam, and a return spring is provided between the gear one and the cam for reset by the compression spring. To achieve the separation of the first gear and the cam after the thread trimming is completed, in other embodiments, the separation of the first gear and the cam after the thread trimming is completed can also be realized by the reset of the tension spring. One end of the tension spring is connected with the first gear, and the other end is fixed. appropriate location within the enclosure.

For another example, the engagement between the first gear and the cam can also be as follows: an axial pin hole is arranged on the first gear, a push pin is movably arranged in the pin hole, one end of the push pin passes through the pin hole, and the first gear and the push plate are connected. One end of the push pin between the two is connected to the return spring, for example, the spring is sleeved on the push pin, and the spring and the end of the push pin close to the push plate are fixedly connected to each other, and the two ends of the spring are respectively pressed against the push plate and the gear 1. When the thread trimming is completed, with the reset of the push plate, the push pin can be reset under the action of the reset spring, so that the first gear and the cam are separated. Like the embodiment shown in FIG. 1 , the cam is provided with a radial push portion, which is used to contact the push pin when the push pin is pushed toward the cam by the push plate through the pin hole, so as to push the gear to rotate with the cam. In this case, since the gear one does not need to move along the lower shaft, the return spring between the gear one and the cam can be omitted, as is the case with the tension spring.

To sum up, the above embodiments of the present invention make the structure of the thread trimming mechanism simpler, lower in cost and more stable by replacing the prior art in which the cam and the thread trimming drive assembly cooperate with the gear and crank connecting rod structure. Good, and because the thread trimming action is realized by reciprocating swing, when the thread trimming is completed, the thread stuck between the moving knife and the fixed knife can be brought out, thus avoiding the phenomenon of thread jamming. The thread trimming function is more reliable at the same time.

Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

The above-mentioned embodiments merely illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present invention should still be covered by the claims of the present invention.

Claims (9)

1. A sewing machine thread trimming mechanism, comprising a fixed knife, a moving knife, a power mechanism, a transmission mechanism and a clutch mechanism, is characterized in that: The fixed knife is fixed on the casing of the sewing machine; The power mechanism is the lower shaft of the sewing machine, and a rotating member is fixed on the lower shaft; The movable knife is installed on the movable knife rest, and the movable knife rest is rotatably arranged in the casing of the sewing machine; The transmission mechanism includes a first gear, a second gear, a crank and a connecting rod; the gears are set on the lower shaft, located on one side of the rotating member, and can rotate relative to the lower shaft; the outer teeth of the first gear and The external teeth of the second gear are meshed, the crank is connected with the second gear through the crank shaft, one end of the connecting rod is connected with the crank, and the other end is connected with the movable tool rest; The first gear and the rotating member are correspondingly provided with matching engaging structures for mutual engagement and separation under the action of the clutch mechanism. meshing. 2 . The thread trimming mechanism of the sewing machine according to claim 1 , wherein the movable knife holder is rotatably arranged on the shaft sleeve of the lower shaft. 3 . 3. The thread trimming mechanism of a sewing machine according to claim 1, wherein the clutch mechanism comprises a driving device and a clutch, the driving device drives the clutch to move back and forth along the lower shaft, and the clutch drives the gear 1 to rotate with the Parts engagement and disengagement. 4. The thread trimming mechanism of a sewing machine according to claim 3, wherein the driving device is an electromagnet, a pneumatic cylinder, a hydraulic cylinder or an electric motor. 5 . The thread trimming mechanism of a sewing machine according to claim 3 , wherein the clutch is a shifting fork, one end of the shifting fork is a fork head, which is connected with the gear, and the other end is connected with the driving device, which is connected with the driving device. 6 . Driven by the driving device, the first gear is driven to engage and disengage from the rotating member. 6 . The thread trimming mechanism of a sewing machine according to claim 3 , wherein the clutch comprises a push plate and a return spring, one end of the push plate is connected to the driving device, and the other end is located at the first gear, facing away from the One side of the rotating member is used to push the first gear to engage with the rotating member, and the return spring is used to separate the first gear and the rotating member. 7. The sewing machine thread trimming mechanism according to any one of claims 1-6, wherein the engaging structure comprises a push pin and a push portion respectively arranged on the first gear and the rotating member, and the push pin is axially removed from the gear. Extending to the rotating member, or extending axially from the rotating member to the gear-one, correspondingly, the push portion extends radially outward from the rotating member or the gear-one, so that when the gear-one is engaged with the rotating member, due to the contact between the push portion and the push-pin The contact causes the gear to rotate synchronously with the rotating member. 8 . The thread trimming mechanism of a sewing machine according to claim 3 , wherein the clutch comprises a push plate, one end of the push plate is connected with the driving device, and the other end is located at the side of the first gear facing away from the rotating member. 9 . On one side, the engaging structure includes an axial pin hole arranged on the first gear, a push pin is movably arranged in the pin hole, and one end of the push pin passes through the pin hole and is located between the push plate and the first gear, from the rotating member A push portion extends radially outward, and when the first gear is engaged with the rotating member, the push plate pushes the push pin to the rotating member, so that the push pin contacts the push portion, so that the first gear rotates synchronously with the rotating member; A return spring that is connected with the push pin and resets the push pin is arranged therebetween. 9. A sewing machine, characterized in that: the sewing machine comprises the sewing machine thread trimming mechanism according to any one of claims 1-8.

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