JPH0783799B2 - Automatic thread tension sewing machine balance device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a balance device for an automatic thread tension sewing machine, and more particularly to a link balance comprising a balance and a balance support so that the thread holding section moves substantially horizontally at the uppermost position of the balance. The present invention relates to a balance device for an automatic thread tension sewing machine, which constitutes an apparatus and arranges an engaging body of a thread passage control device at positions equidistant from a starting point and an ending point of horizontal movement of a thread holding section.

[Prior art]

Generally, a balance that moves up and down in synchronization with the main shaft of the sewing machine
When descending, the upper thread for sewing with the sewing thread is supplied to the lower thread bobbin, and when ascending, the upper thread loop formed in the eyelet of the sewing needle in the sewing process is tightened and the upper thread for the next sewing. Plays a role of replenishing a predetermined amount from the thread spool.

In the portion of the thread supply path from the thread spool to the thread holding portion of the thread take-up, a thread tensioner that gives a passing resistance to the upper thread is generally interposed in order to enable tightening of the upper thread wheel. . This thread tension device has a mechanism in which a pair of thread tension discs are pressed into contact with each other by a compression spring, and a frictional resistance is applied to an upper thread passing between the pair of thread tension discs.

However, in this type of thread tension regulator, the upper thread is supplied due to the mutual relationship between the tension acting on the upper thread after the thread tension regulator and the resistance force in the thread tension regulator. It is difficult to accurately control the amount of thread supplied, and it is possible to control the thread tension of the seam according to the thickness and type of work cloth (that is, the thickness and type of needle thread selected corresponding to these). Have difficulty.

Therefore, in recent years, for example, Japanese Patent Publication No. 53-41580 discloses a structure in which a pair of thread tension discs are brought into pressure contact with a solenoid type actuator instead of the spring type thread tension device.
An electric thread passage that allows the upper thread to pass for a predetermined period at a predetermined timing by driving the actuator in synchronization with the rotation of the sewing machine spindle, and restricts the upper thread to pass at other times. A controller is described.

However, in the yarn passage control device described in the above publication,
Regardless of the thickness and type of the work cloth, that is, the thickness of the upper thread, it only controls the thread passage in synchronization with the main shaft of the sewing machine, and also the operation speed when releasing the thread passage and the operation speed when restraining the thread passage. Is set independently of the rotation speed of the sewing machine spindle. Therefore, the upper thread is tightened and supplied uniformly regardless of the thickness and type of thread, and the thread tension of the seam becomes unstable.

Furthermore, since the supply amount of the upper thread changes subtly when the rotation speed of the sewing machine spindle changes, the thread tension also changes depending on the sewing speed.

Therefore, the applicant of the present application has proposed the following sewing machine capable of controlling thread passage (Japanese Patent Application No. 61-251333 (Japanese Patent Application Laid-Open No. 63-105790)).

That is, a balance is formed on the upper end of the swing lever, and the balance is held at the uppermost position until the needle hole reaches the upper surface of the needle plate after the main shaft rotates about 40 degrees after the needle bar reaches the uppermost position. A cam type balance mechanism for driving the swing lever by a rotating cam is provided, and further, in the upper thread supply path from the thread spool to the thread hole of the thread balance to the stitch eye hole, A thread passage control device for restraining or releasing the upper thread reaching to the point of time is coordinated with the movement of the main shaft.

The swing lever is provided with a cam hole formed by an arc hole and straight holes at both ends of the arc hole. The crank pin of the balance crank is inserted into the cam hole and the main shaft is rotated to rotate the crank. The balance is held at the uppermost position for about 75 degrees when the pin moves through the arc hole.

Further, in the yarn passage control device, a yarn path restricting plate on the machine frame side as a pair of engaging bodies and a movable wheel are provided, and a rotary cam provided on the spindle causes a movable wheel to rotate the spindle through a link mechanism. When the needle thread is tightened, it is driven so that it moves closer to or further from the thread guide plate, and the balance moves to the uppermost position.When the upper thread is tightened, the upper thread is restrained by the movable wheel, and after the upper thread is tightened. The upper thread is released from the thread spool before the cloth feed is completed, and the necessary amount of upper thread is supplied from the thread spool, and then the upper thread is restricted by the movable wheel before the eye of the sewing needle reaches the needle plate. is there.

[Problems to be solved by the invention]

In the thread passing controllable sewing machine having the cam type balance mechanism according to the above-mentioned application, a swing lever having a complicated cam hole composed of an arc hole and a straight hole is provided by rotating a main shaft. When moving vertically with the crank pin of the balance crank inserted in the cam hole, when the crank pin moves from the straight hole to the arc hole, that is, when the ascending movement of the swing lever is stopped, or when the crank pin moves from the arc hole to the straight hole. When moving, that is, when starting the downward movement of the swing lever, the swing lever is suddenly stopped and vertically driven with different motion curves. Especially when the main shaft rotates at high speed, the crank pin reciprocates at high speed in the cam hole, resulting in wear of the crank pin, cam hole, etc. and lack of durability, and noise generated by the collision sound between the crank pin and the cam hole. There are problems such as.

[Object of the Invention]

An object of the present invention is to provide a balance and balance device for an automatic thread tension sewing machine, which includes a thread passage control device for restraining and releasing the upper thread, and which comprises a link type balance device with a balance and a balance support. Especially.

[Means for solving problems]

An automatic thread tension sewing machine balance device according to the present invention comprises a balance having a thread holding portion at a free end and a balance support, and the thread holding portion is configured to move substantially horizontally at the uppermost position of the balance. A pair of link type balance device and a pair of upper threads from the thread supply source to the sewing needle via the thread holding portion to the sewing needle, which are locked and released in synchronization with the rotation of the sewing machine main shaft. And a thread passage control device having an engaging body, wherein the pair of engaging bodies are arranged at positions equidistant from the starting point and the ending point of the horizontal movement of the yarn holding section.

In addition, if necessary, the upper thread is disengaged from the hook while the balance is raised from the lowermost position than the distance between the pair of engaging bodies and the thread holding portion at the thread lowermost position. It may be arranged such that the distance between the engagement body and the thread holding portion at this time is shorter.

[Action]

In the balance device of the automatic thread tension sewing machine according to the present invention,
A balance having a thread holding portion for holding the upper thread at its free end,
Due to the cooperation of the rotation of the sewing machine spindle and the balance support, the sewing machine spindle is driven to the lowest position and the uppermost position in synchronization with the rotation of the sewing machine spindle, and the thread holder moves substantially horizontally at the uppermost position. To do.

Of the upper thread from the thread supply source to the sewing needle via the thread holding section, the upper thread from the thread supply source to the thread holding section is timed with the rotation of the main shaft by a pair of engaging bodies of the thread passage control device. When the thread holding part moves to the uppermost position, it is restrained for tightening the upper thread and the balance is opened to feed the required amount of the upper thread, and the balance is released during the cloth feeding to reach the uppermost position, and the sewing needle reaches the needle plate. Being restrained again before.

Therefore, when the balance moves from the lowermost position to the uppermost position, the needle thread wheel by sewing is sufficiently tightened, and the starting point and the end point when the thread holding portion moves horizontally at the uppermost position of the balance are equidistant from the engaging body. Since it is located at, the upper thread is not unnecessarily tightened by the horizontal movement of the thread holding portion.

That is, when the yarn holding section moves horizontally at the uppermost position,
The upper thread is released by the thread passage control device, and in conjunction with the cloth feeding movement, the upper thread is fed out from the thread supply source by a necessary amount and then restrained, so that the thread tension becomes stable.

The engaging body and the thread holding portion when the upper thread is disengaged from the hook during the ascending of the balance from the lowermost position than the distance between the engaging body and the thread holding portion when the engaging body is at the lowermost position of the balance. When arranging so that the distance between them becomes shorter, the amount of yarn corresponding to the shortened distance is supplied to the shuttle, and the required amount of shuttle yarn can be secured.

〔The invention's effect〕

As described above, according to the balance device for the automatic thread tension sewing machine of the present invention, the balance and the balance support which are driven from the lowermost position to the uppermost position while holding the upper thread by the thread holding section. Since the link-type balance device is configured with and the link-type balance device is configured to horizontally move the thread holding part of the balance at the uppermost position, the balance is moved upward, horizontally (stopping operation) and moved downward. The link type balance device operates smoothly with respect to (different motion curves), and is quiet and excellent in durability even with high speed rotation of the main shaft.

Further, since the thread holding portion is located at the same distance from the engaging body at the start point and the end point of the horizontal movement at the uppermost position, it is only necessary to reliably supply the required amount of the upper thread after tightening the upper thread. Instead, the needle thread amount from the thread holding section to the sewing needle is kept substantially constant over the entire period when the balance is at the uppermost position,
The needle thread is not unnecessarily tightened and has a stable thread tension.

In this way, with a simple configuration in which the shape and dimensions of the balance and the balance support are slightly changed, the balance can be moved almost horizontally at the uppermost position, making it ideal for tightening the upper thread (thread tension) and supplying the upper thread. It can be used as a general balance device.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an electronically controlled lockstitch sewing machine to which the present invention is applied. In this lockstitch sewing machine M, a pedestal portion 4 is erected at the right end portion of the bed portion 2, and the pedestal portion 4 is erected. An arm portion 6 extending leftward from the upper end is horizontally arranged so as to face above the bed portion 2, and a head portion 8 is provided at the left end portion of the arm portion 6. The head 8 has a needle bar 10 and a presser bar.
The needle bar 10 and the sewing needle 12 at the lower end of the needle 18 are vertically driven by a sewing machine main shaft 28 as described later, and are horizontally swung by a swing mechanism (not shown). Presser bar 18
And the presser foot 20 at the lower end thereof are moved up and down by operating the operating body 21.

The bed portion 2 is provided with a needle plate 22 and feed teeth 23 which penetrate the needle plate 22 and appear on the upper surface of the bed portion 2,
A predetermined stitch is formed on the work cloth by the cooperation of the horizontal hook containing the needle bar 10 and the lower thread bobbin in the bed portion 2 and the feed dog 23 of the cloth feed mechanism. Since the horizontal hook and the cloth feeding mechanism are the same as those of the existing general structure, detailed description thereof will be omitted.

2 to 3 show an internal mechanism provided in the head portion 8 of the sewing machine M and the arm portion 6 in the vicinity thereof.

As shown in the drawing, a sewing needle 12 is attached to the lower end of the needle bar 10, the needle bar 10 is vertically movably mounted on a needle bar support 24, and the upper end of the needle bar support 24 is a pin 26 on the machine frame. Is pivoted through
As a result, the needle bar 10 can swing left and right around the pin 26 together with the needle bar support 24, and the needle bar 10 is driven up and down with respect to the needle bar support 24 by the main shaft 28 and the needle bar crank 30. It is like this.

A presser foot 20 is detachably attached to the lower end of the presser bar 18, and the presser bar 18 is mounted on a machine frame by a mechanism (not shown), and the position is switched between an ascending position and a descending position, and the descending position is lowered. When in the position, the work cloth is pressed against the needle plate 22 by the presser foot 20.

Next, the link type balance device 36 will be described with reference to FIGS.

The sewing machine main shaft 28 is rotatably mounted on the machine frame via a bush metal 32, etc., and a balance crank 34 is fixed to the left end of the sewing machine main shaft 28.

The link-type balance device 36 is composed of a balance 38 and a balance support 40. The balance 38 and the balance support 40 look like a normal link-type balance, but in reality, they are normal in shape and size of each part. Is different from

The balance 38 is substantially V-shaped when viewed from the side and crank-shaped when viewed from the front, and is rotatably mounted via a crank pin 42 on a balance crank 34 that is fixed to the sewing machine main shaft 28 at a predetermined eccentric distance at its lower end. A thread holding portion 38a for holding the upper thread 14 is provided at its free end.

The balance support 40 is for moving the balance 38 up and down while moving up and down, and for horizontally moving at the uppermost position of the thread holding portion 38a. One end of the balance support 40 is pivoted to the middle of the balance 38. The other end is rotatably connected via a support pin 44, and the other end is rotatably connected to the machine frame via a pivot support pin 46. The balance 38 is rotated by the rotation of the balance crank 34 by the rotation of the main shaft 28.
When the lower end of the balance rotates along a predetermined circular orbit, the balance support 40 swings up and down around the pivot pin 46 to move the balance.
38 Limit the swing range of the middle section.

Since the link type balance device 36 is constituted by the balance 38 and the balance support 40 as described above, the movement of the balance 38 with the rotation phase angle of the main shaft 28 as a parameter becomes like a curve MA in FIG. The movement of the sewing needle 12 attached to the lower end of the rod 10 is shown by the curve in FIG.
It becomes like MB, and the horizontal feed movement of the feed dog 23 of the cloth feed mechanism becomes like the broken line MD in FIG. The phase angle in FIG. 7 is 0 degree when the needle bar 10 is at the uppermost position.

The balance 38 horizontally moves at the uppermost position as shown in FIG. 2 from the time when the main shaft 28 rotates about 30 degrees after the start of the cloth feeding to the time when the eyelet of the sewing needle 12 reaches the upper surface of the needle plate 22. Therefore, the balance 38 is held at the uppermost position during the period when the cloth feeding is substantially executed except the initial stage of the cloth feeding. However, the balance 38 may be configured so as to be located at the uppermost position from the start of feeding the cloth. In any case, the link type balance device 36 in this embodiment operates simply, smoothly and quietly.

A connecting plate 48 is fixed to the left end of the crank pin 42,
A needle bar crank 30 is rotatably connected to a pivot pin 50 extending leftward from the connecting plate 48, and a lower end portion of the needle bar crank 30 is connected to a middle portion of the needle bar 10.

Next, the thread passage control mechanism will be described with reference to FIGS.

Immediately to the left of the needle bar crank 30, a plate member 52, which is a part of the machine frame, is provided orthogonal to the main shaft 28. As shown in FIGS. 2 and 3, the plate member 52 is provided at a position in front of the main shaft 28.
A pretensioning device 54 capable of giving passage resistance to the upper thread 14 is provided on the left side of the.

The pretensioning device 54 is configured such that the upper thread 14 is passed between a pair of thread tension discs 54a and the spring force is adjusted by rotating the dial to adjust the thread passing resistance. The pretensioning device 54 may be omitted.

Further, the upper thread from the pretension device 54 to the thread holding portion 38a of the balance 38 in the upper thread supply path from the thread spool 16 to the eye hole of the sewing thread 12 via the pretension device 54 and the thread holding portion 38a of the balance 38. A thread passage control device 60 that controls passage of the upper thread 14 by approaching / separating the guide member 56 and the clamp member 58 so that the thread 14 can be restrained or released in synchronization with the movement of the main shaft 28. It is provided as follows.

A shaft member 62 is arranged below the pretensioning device 54 in the vicinity of the left side portion of the plate member 52 and to the right of the balance clamp 34 in parallel with the main shaft 28. The shaft member 62 is a support portion of a machine frame. It is rotatably attached to.

The rear end of the clamp member 58 is fixed to the left end of the shaft member 62, and the movable wheel 64 is attached to the front end of the clamp member 58.

The guide member 56 disposed immediately above the clamp member 58 is fixed to the left end surface of the plate member 52.
Has a guide portion 56a that bends downward, and the guide member 56 is disposed so as to contact the movable wheel 64 from above and to hold and constrain the upper thread 14 between the guide member 56 and the movable wheel 64. The guide member 56 and the movable wheel 64 form a pair of engaging bodies.

As shown in FIGS. 3 and 5, an annular V groove 64a is formed on the peripheral surface of the movable wheel 64, and the restricting portion 56b of the guide member 56 is located above the V groove 64a in the upper half of the movable wheel 64. It is formed in the shape of a projecting curved surface having a U-shaped cross section so as to be engaged with.

The needle thread 14 that has passed through the pretensioning device 54 is bent by the regulation 56b of the guide member 56 and extends to the sewing needle 12 via the thread holding portion 38a of the balance 38.

Then, the upper thread 14 that bends at the restricting portion 56b is pinched between the restricting portion 56b and the V groove 64a in two points, and is strongly restrained.

The movable wheel 64 is driven up and down in synchronization with the rotation of the main shaft 28 to drive the upper thread 14
In order to perform the release and restraint of the shaft member with a predetermined timing, a cam 66 is fixed to the main shaft 28 corresponding to the right end position of the shaft member 62, and a lever 68 fixed to the shaft member 62 is pressed against the cam 66 from diagonally above. The spring 70 is elastically biased so that

When the main shaft 28 rotates, the lever 68 moves the cam surface of the cam 66.
66a pushes diagonally upward against the spring force to rotate the shaft member 62, the clamp member 58 swings downward, the movable wheel 64 separates from the guide member 56, and the upper thread 14 is released from the restrained state. To be released. Further, when the lever 68 passes the cam surface 66a, the lever 68 is rotated by the elastic force of the spring 70, the movable wheel 64 comes into contact with the restricting portion 56b of the guide member 56, and the upper thread 14 moves between the restricting portion 56b and the movable wheel 64. It is sandwiched and restrained. In this way, the release and the restraint of the upper thread 14 are put into practical use at predetermined timings. Thus, the timing for releasing or restraining the upper thread 14 is shown by the curve MC in FIG.

As shown in FIG. 6 and FIG. 7, after the balance 38 is raised to the uppermost position, the guide member 56 and the clamp member 58 are separated from the starting point S where the horizontal movement starts and the end point E where the horizontal movement ends. The distances 1 ₁ and 1 ₂ to the constraint point P that restrains the needle thread 14 are equal. Therefore, the length of the upper thread 14 from the restraint point P to the thread holding portion 38a is kept substantially constant for a predetermined period when the balance 38 is at the uppermost position, so that the balance 38 moves horizontally. When the upper thread 14 is released, the upper thread 14 is released from the thread spool 16 by the required amount and is restrained after the upper thread 14 is released. It becomes a thread tension.

By the way, as can be seen from the hook thread amount curve MK in FIG.
Horizontal hook (not shown) after 12 moves below needle plate 22
When forming the upper thread loop with the sword tip, the maximum hook thread amount is required when the upper thread 14 is about 300 degrees out of the horizontal hook. On the other hand, since the lowermost position B of the balance 38 is about 260 degrees, the balance 38 starts to tighten the upper thread 14 at about 300 degrees, which requires the maximum amount of hook thread. (See FIG. 6) Therefore, in order to prevent the shortage of the hook yarn amount, the following structure is adopted.

As shown in FIGS. 2 and 6, the pair of engagement bodies (the guide member 56 and the movable wheel 64) of the yarn passage control device 60 are not located below the yarn holding portion 38a which has reached the lowest position, The thread holding portion 38a
It is arranged at the same height level as and in front of it.

In the upward movement trajectory passing through the lowest position B of the thread holding portions 38a movement locus of the balance 38, the upper thread 14 from the horizontal hook than the distance 1 ₃ between the constraint points P and lowest position B of the balance 38 Write a distance 1 ₄ between the N and the constraint point P the point at which the outside is configured to be shorter.

As a result, as shown by the upper thread amount curve MU in FIG. 7, the maximum amount of hook thread required is about 30 despite the upward movement of the balance 38.
When 0 °, that is, shorter towards the distance 1 ₄ when about 260 ° point N than the distance 1 ₃ when in the lowest position B of the balance 38, the yarn amount that became the shorter towards the hook Since it is supplied, the shortage of the hook yarn amount is replenished.

As can be seen from FIG. 7, when tightening the upper thread 14 as the balance 38 moves up from the lowermost position to the uppermost position, the upper thread 14 is restrained by the thread passage control device 60, so that the upper thread 14 is securely tightened. To be executed. When the balance 38 reaches the uppermost position and the tightening of the upper thread 14 is completed, the upper thread 14 is supplied in conjunction with the cloth feed and the constraint by the thread passing control device 60 is released, so that the required amount of the upper thread 14 is removed from the thread spool 16. It is supplied to the balance 38. By the time the cloth feed and needle swing are completed in the state where the upper thread 14 is released in this way, the upper thread 14
Is again restrained, and with the upper thread 14 restrained in this way, the upper thread loop is reliably formed on the lower thread bobbin side with the supplement of the shortage of the shuttle thread, and the sewing operation is executed.

Further, as shown by the curve MC in FIG. 7, due to the restraint characteristics, in the case of the thin upper thread 14, it is released at the point F ₁ and is restrained at the point C ₁ , whereas it is thicker. F _{1 for} upper thread 14
It is restrained at an early point C ₂ than is also the point C ₁ released at a slower point F ₂ than. Therefore, the thin upper thread 14 is tightened with a weak tension suitable for it, and the thick upper thread 14 is tightened with a strong tension suitable for it.

As described above, in the link type balance device 36, the balance 38 driven at the lowermost position and the uppermost position, and the thread holding portion 38a at the uppermost position of the balance 38 are moved to the uppermost position for a predetermined period. Since the balance 38 is held by the balance support 40, the balance 38 operates smoothly in each of the upward movement, horizontal movement (stopping operation), and downward movement even when the sewing machine spindle 28 rotates at high speed. As a result, the link type balance device 36 becomes quiet and has excellent durability.

Further, the start point S and the end point E from the engaging body of the thread passage control device 60
Since the distances up to are equal, the required amount of the upper thread 14 is fed out when the balance 38 is held at the uppermost position, and the thread tension is stable.

In addition, the distance from the constraining point P of the engaging member made up of the guide member 56 and the movable wheel 64 to the thread holding portion 38a is minimized in the middle of the ascending movement locus in which the balance 38 rises from the lowermost position. As a result, there will be no shortage of the hook yarn amount.

In the above embodiment, the case where the mechanical yarn passage control device 60 is provided has been described, but as the yarn passage control device, for example, an electric yarn passage control device having a mechanism in which the movable wheel 64 is driven by a linear solenoid is used. May be used.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a schematic perspective view of a sewing machine, FIG. 2 is a side view of an arm portion and an internal mechanism incorporated in a head of the sewing machine, and FIG. A front view of the mechanism, FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, and FIG.
FIG. 6 is a cross-sectional view taken along the line V, FIG. 6 is an explanatory view showing the locus of movement of the thread holding portion of the thread take-up unit, its main points and constraint points, and FIG. 7 is a time chart showing the operation of each mechanism of the sewing machine. M: sewing machine, 10: needle bar, 12: sewing needle, 14: needle thread,
16 …… Thread piece, 28 …… Sewing machine spindle, 34 …… Balance crank,
36 …… Link type balance device, 38 …… balance, 38a …… thread holding part, 40 …… balance support, 56 …… guide member, 58 …… clamp member, 60 …… thread passing control device, 62 …… axis Material, 64 ……
Movable wheel, 66 …… Cam, 66a …… Cam surface, 68 …… Lever.

Claims (2)

[Claims] 1. A four-bar linkage type balance device comprising a balance having a thread holding portion at its free end and a balance support, and the thread holding portion moving substantially horizontally at the uppermost position of the balance, and a thread supply device. A thread passage control having a pair of engaging bodies for restraining and releasing the upper thread from the thread source to the thread holding section among the upper thread from the thread source to the sewing needle, in synchronization with the rotation of the sewing machine main shaft. An automatic thread tension sewing machine balance device, wherein the pair of engagement bodies are arranged at positions equidistant from a starting point and an ending point of the horizontal movement of the thread holding portion. 2. The upper thread of the pair of engaging bodies is disengaged from the hook during the ascending of the balance from the lowermost position than the distance between the engaging bodies and the thread holding portion at the lowermost position of the balance. The balance device for an automatic thread tension sewing machine according to claim 1, wherein the engagement body and the thread holding portion are arranged such that the distance between them is shorter.