JPS63105788A - Yarn passage controllable sewing machine - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a sewing machine capable of controlling thread passage, and particularly to a sewing machine that includes a thread engaging body that makes point contact at a bend in a thread supply path from a thread supply source to a sewing needle. This invention relates to a device that controls thread passage.

(Prior art) In general, a thread take-up that moves up and down in synchronization with the main shaft of a sewing machine is
When descending, the upper thread for sewing with the sewing needle is supplied to the lower thread bobbin side, and when ascending, the upper thread loop formed in the eye of the sewing needle is tightened during the sewing process, and the upper thread is supplied to the lower thread bobbin for sewing the next stitch. It plays the role of replenishing a predetermined amount of thread from the thread spool.

A thread tension device is generally installed in a portion of the thread supply path from the thread spool to the thread holding portion of the take-up thread, which applies resistance to the upper thread or stops the upper thread from passing at a predetermined timing.

The above-mentioned thread tension device has a mechanism in which a pair of thread tension discs are brought into pressure contact with each other by a compression spring, and frictional resistance is applied to the upper thread passing between the pair of thread tension discs.

As the latter thread tension device, for example, the Japanese Patent Publication No. 53-4158
As described in Publication No. 0, by pressing a pair of thread tension discs into contact with each other using an electric actuator such as a solenoid coil, the upper thread passed between the pair of thread tension discs is clamped and restrained at a predetermined timing. It looks like this.

(Problems to be Solved by the Invention) The conventional thread tension device described above has a mechanism in which a thin needle thread is held between a pair of thread tension discs, so the plane accuracy of the thread tension discs must be maintained at a high level. In order to secure needle thread tension of approximately 250g, a compression spring force of approximately 1500g is required, resulting in very low force conversion efficiency.
A large spring and electric actuator are required, making the thread tension device larger and higher in cost.In the case of an electric thread tension device, impact noise is generated due to collision between the thread tension discs when they open and close. There are problems such as.

(Object of the Invention) An object of the present invention is to provide a sewing machine capable of controlling thread passage, which is equipped with a thread passage control device that can stabilize the thread tension, has a simple and compact structure, and does not generate impact noise. It is.

(Means for Solving the Problems) A sewing machine capable of controlling thread passage according to the present invention has a thread supply path extending from a thread supply source to an eye of a sewing needle and having at least one bending portion, and a thread supply path extending from a thread supply source to an eye of a sewing needle, and A sewing machine is provided with a thread passage control device that applies passage resistance to the supplied sewing thread or stops the passage of the sewing thread in time with the rotation of a sewing machine main shaft, the thread passage control device clamping the sewing thread. a pair of yarn engaging bodies that are relatively movable in a direction parallel to a plane containing the yarn supply path near the bending point and arranged on both sides of the bending point; The outer surface of at least one of the two thread engaging bodies is formed into a curved surface in the direction of supply of the thread so that the two thread engagement bodies make point contact in the direction of supply of the thread.

If necessary, the thread engaging body located on the bending direction side of the thread supply path at the bending point is fixed to the sewing machine frame, and the thread engaging body located on the opposite side to the bending direction side is movable. It may also be installed on the sewing machine frame.

If necessary, the thread engaging body fixed to the sewing machine frame has a cylindrical curved surface, and the movably installed thread engaging body has a 7-shaped groove that can be engaged with the cylindrical curved surface. You can.

(Function) In the sewing machine capable of controlling thread passage according to the present invention, the thread supply path from the thread supply source to the eye of the sewing needle has at least one bending point, so that the sewing thread supplied toward the sewing needle has resistance to passage. A device on the thread passing side 'a' is provided for giving a movement of the sewing machine main shaft or for stopping the passage of the sewing thread in synchronization with the movement of the sewing machine main shaft.

In this yarn passage control device, two parts are provided on both sides of the bending part and are movable relative to each other in a direction parallel to the plane containing the yarn supply path.
By passing the suture between the pair of thread engaging bodies and bringing the curved surface of one thread engaging body into point contact with the other thread engaging body, the suture thread is held and restrained between the pair of thread engaging bodies.

In this way, since the suture thread is held at the point contact portion between the pair of thread engaging bodies, a large restraining force is generated with a relatively small driving force. Furthermore, since the two thread engaging bodies do not come into metal touch, almost no impact noise is generated.

Furthermore, when fixing the thread engaging body located on the bending direction side of the bending point to the sewing machine frame, the length of the sewing thread from the bending point to the sewing needle via the thread holding part of the thread take-up is kept constant. Therefore, when the thread take-up is raised to tighten the needle thread, the tension and elongation of the needle thread hardly change and the thread tension is stabilized.

(Effects of the Invention) According to the sewing machine capable of controlling the thread passage according to the present invention, as explained above, the force for restraining the sewing thread in the thread passage control device is concentrated in a narrow local area in the form of point contact. , the surface pressure that restrains the sewing thread is high, the thread restraining force becomes large, and the force conversion efficiency becomes high.

Therefore, it is possible to accurately control the thread passage by applying resistance to the sewing thread or stopping the passage of the sewing thread, to appropriately control the thread tension of the stitches, and to downsize and simplify the thread passage control device. Effects such as being able to reduce impact noise in the yarn passage control device and making it a quiet device by suppressing the generation of impact noise in the yarn passage control device can be obtained.

(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 has been applied. An arm portion 6 extending leftward from the upper end is disposed horizontally 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. A needle bar 10 and a presser bar 18 are attached to the head 8, and the needle bar 10 and the sewing needle 12 at its lower end are attached to the head 8.
As will be described later, the sewing machine main shaft 28 drives the sewing machine main shaft 28 vertically, and a swinging mechanism (not shown) swings left and right. The presser bar 18 and the presser foot 20 at its lower end are raised and lowered by operating an operating body not shown.

The bed section 2 is provided with a needle plate 22 and a feed dog 23 that passes through the needle plate 22 and appears on the top surface of the bed section 2. A predetermined seam will be formed in the cloth. The cloth feeding mechanism is similar to an existing general structure, so a detailed explanation will be omitted.

2 to 4 show the internal mechanism provided in the head 8 of the sewing machine M and the arm portion 6 in the vicinity thereof.

As shown in the figure, a sewing needle 12 is attached to the lower end of the needle bar 10, and the needle bar 10 is attached to a needle bar support 24 so as to be movable up and down. As a result, the needle bar 10 is movable to the left and right about the pin 26 together with the needle bar support 24. It is designed to be driven up and down by a needle bar crank 30 at the end.

A presser foot 20 is removably attached to the lower end of the presser bar 18, and the presser foot 18 is attached to the machine frame by a mechanism not shown in the drawings, and is switched between a raised position and a lowered position. When in this position, the presser foot 20 presses the work cloth against the throat plate 22.

Next, the balance mechanism will be explained with reference to FIGS. 2 to 4.

The main shaft 28 of the sewing machine is rotatably attached to the machine frame via a bushing metal 32, etc., and a sub-shaft 34 is disposed diagonally above and behind the main shaft 28 in parallel with the main shaft 28, and this sub-shaft 34 is attached to the machine frame. It is rotatably attached to. This secondary shaft 34
One end of a swinging lever 36 is rotatably connected to the swinging lever 36, and the swinging lever 36 extends from the subshaft 34 to the left end side of a balance crank 38 fixed to the main shaft 28. Elongated cam hole 42 of swing lever 36
A connecting plate 44 is fixed to the left end of the crank pin 40 on the left side of the swing lever 36, and the needle bar crank 30 is attached to a pivot pin 46 extending leftward from the connecting plate 44. The lower end portion of the needle bar crank 30 is connected to the middle portion of the needle bar 10.

At the upper end of the front part of the swing lever 36, a thread take-up 48 (thread take-up body) that extends upward in a crank shape is formed in one piece, and at the upper end of this thread take-up 48, a thread holding part 48a is formed. There is.

The cam hole 42 of the first drive lever 36 prevents the crank pin 40, which is located at the same radius as the rotation locus of the crank pin 40 and near the uppermost position, from rotating approximately 74 degrees as shown in FIGS. 2 and 3. The cam hole 42 is formed of a circular arc hole 426a and a short straight hole 42b extending straight from both ends of the circular arc hole 42a, and the outer circumference of the cam hole 42 is reinforced with a reinforcing portion 36a.

With the crank pin 40 inserted into the cam hole 42 of the swing lever 36, the balance crank 38 and the crank pin 40
rotates around the main shaft 28, the swing lever 36 rotates around the sub shaft 3.
4 as a pivot center, the crank pin 40 is driven to reciprocate up and down by a crank pin 40 between an uppermost position shown by a solid line in FIG. 3 and a lowermost position shown by a phantom line in FIG. At this time, the needle bar 10 is reciprocated up and down via the needle bar crank 30 and crank pin 40 in synchronization with the rotational movement of the sewing machine main shaft 28.

Since the circular arc hole 42a as described above is formed in a part of the cam hole 42 of the swing lever 36, the movement of the balance 48 using the rotational phase angle of the main shaft 28 as a parameter is as shown by the curve MA in FIG. The movement of the sewing needle 12 attached to the lower end of the needle bar 10 is as shown by the curve MB in FIG.
become that way.

The thread take-up 48 is held at the uppermost position from when the main shaft 28 rotates approximately 40 degrees after the start of cloth feeding until the eye of the sewing needle 12 reaches the upper surface of the throat plate 22. Therefore, the thread take-up 48 is held at the uppermost position during the period when cloth feeding is substantially carried out, except at the initial stage of cloth feeding. However, the swing lever 36 may be configured so that the thread take-up lever 48 is located at the uppermost position from the start of cloth feeding. In any case, the structure of the swing lever 36 in this embodiment is relatively simple and operates smoothly and quietly.

Next, the yarn passage control mechanism will be explained with reference to FIGS. 2 to 7.

Right next to the needle bar crank 30 at the left end of the main shaft 28.

On the left side, a plate member 50, which is part of the machine frame, is provided perpendicularly to the main shaft 28. As shown in FIGS. 2 and 3, at a position slightly forward of the main shaft 28, on the left side of the plate member 50 is a britension device 52 that can provide passing resistance to the needle thread 14.
will be provided as necessary.

This britension device 52 allows the upper thread to pass between a pair of thread tension discs 52a, and by rotating a dial, the spring force can be adjusted to adjust the thread passing resistance. , this britension device 52 may be omitted.

Furthermore, the movement of the main shaft 28 moves the needle thread 14 from the thread spool 16 to the thread holding portion 48a of the thread take-up lever 48 in the needle thread supply path that extends from the thread spool 16 to the thread holding portion 48a of the thread take-up lever 48 to the eye of the sewing needle 12. A yarn passage control device 54 as described below is provided so that the yarn can be restrained or released in time.

A thread path regulating plate 56 (thread engaging body) is fixed to the left side of the plate member 50 at a position below the britension device 52,
A movable plate 58 disposed near the left side surface of the yarn path regulating plate 56 and the lower end of a link arm 60 are rotatably connected to the plate member 5o by stepped screws 62, so that the movable plate 58 can be moved. ring 6
4 (thread engaging body) contacts the regulating portion 56a of the thread path regulating plate 56 from below, and the upper thread 1 is inserted between the regulating portion 56a and the movable ring 64.
The movable plate 58 is elastically biased by a spring 66 whose one end is fixed to the machine frame so that the movable ring 64 of the movable plate 58 is pressed against the regulating portion 56a. A contact shaft 68 at the upper end of the arm portion 58a contacts a contact portion 60a near the lower end of the link arm 60 from the front.

As shown in FIG. 2, FIG. 3, and FIG. The regulating portion 56a is formed in an inverted U shape when viewed from the side so as to be engaged with the groove 64a from above, and the regulating portion 56a is formed in a real screen shape with a U-shaped cross section.

The needle thread 14 that has passed through the britension device 52 is bent into a U-shape at the regulating portion 56a of the thread path regulating plate 56, and extends to the sewing needle 12 via the thread holding portion 48a of the thread take-up lever 48.

The needle thread 14 bent by the regulating portion 56a is held between the regulating portion 56a and the V-groove 64a at two points and is strongly restrained. In particular, the movable ring 6 moves in a direction parallel to the plane including the thread supply path of the needle thread 14 bent at the regulating portion 56a.
4 is driven and clamps and restrains the upper thread 14 in a transverse manner.
The surface pressure that clamps the needle thread 14 becomes extremely large. In other words, even when the force pressing the movable ring 64 is small, the needle thread 14 can be strongly restrained.

Then, in order to drive the movable ring 64 of the movable plate 58 up and down in synchronization with the rotation of the main shaft 28 to release and restrain the upper thread 14 at a predetermined timing, a movable ring 64 corresponding to the right end side of the sub-shaft 34 is provided. In this position, a rotating cam 70 having an elliptical cam groove 72 is fixed to the main shaft 28 , and a contact 74 a at the tip of a first arm 74 fixed to the subshaft 34 is engaged with the cam groove 72 .

On the other hand, a second arm 76 is fixed to the left end of the subshaft 34, and the lower end of the second arm 76 is connected by fitting a pin 76a into a loose pin hole 60b at the upper end of the link arm 60.

In the yarn passage control device 54 described above, when the main shaft 28 rotates and the first arm 74 rubs via the elliptical cam groove 72, the second arm 76 rubs via the subshaft 3, and the second arm When 76 swings, the link arm 60 slides around the stepped screw 62.

As a result, the contact portion 68 at the contact portion 60a of the link arm 60
When is pushed forward, the movable plate 58 rotates against the spring force, the movable ring 64 separates from the regulating portion 56a of the thread path regulating plate 56, and the upper thread 14 is released from the restrained state. Further, when the contact portion 60a of the link arm 60 moves rearward, the movable plate 58 rotates by the elastic force of the spring 66, and the movable ring 64 moves toward the restriction portion 5.
6a, and the needle thread 14 is held and restrained between the regulating portion 56a and the movable ring 64. In this way, the upper thread 14 is released and restrained at predetermined timings. The timing at which the needle thread 14 is released or restrained in this manner is shown by the curve MC in FIG.

As can be seen from FIG. 5, the thread take-up 48 is raised from the lowest position to the highest position (when the upper thread 14 is tightened, the upper thread 14 is restrained by the thread passage control device 54, so the upper thread 14 is not tightened). When the thread take-up 48 reaches the uppermost position and tightening of the upper thread 14 is completed, the thread passage control device 54 is operated in conjunction with the cloth feed to supply the upper thread 14.
The restriction is released, and the required amount of needle thread 14 is supplied from thread spool 16 toward thread take-up 48. In this way, cloth feeding and needle swinging are completed with the needle thread 14 released, and the sewing needle 1
2 reaches the throat plate 22, the upper thread 14 is restrained again, and the sewing operation is performed with the upper thread 14 restrained in this way, and an upper thread loop is formed on the lower thread bobbin side. Therefore, the required amount of needle thread 14 consumed for cloth feeding and needle swinging is reliably supplied, and since the needle thread 14 is restrained when forming the needle thread loop, unnecessary needle thread 14 is not supplied.

As shown in curve MC in FIG. 5, due to the restraining characteristics determined by the elliptical shape of the cam groove 72 of the rotating cam 70, in the case of a thin needle thread 14, it is released at point F, and at point C3.
In contrast, in the case of the thick upper thread 14, it is released at point F2, which is later than point F+, and returns to point C.
It is constrained at point C2, which is earlier than 0. Therefore, when the needle thread 14 is thin, the needle thread 14 is tightened with an appropriate weak tension, and when the needle thread 14 is thick, the needle thread 14 is tightened with a suitably strong tension.

Next, while the thread take-up lever 48 is sliding downward and the upper thread 14 is being restrained by the movable ring 64 and the thread path regulating plate 56, the thread spool 16 is
The thread pay-out mechanism 78 that pays out and stores a predetermined amount of needle thread 14 will be described with reference to FIGS. 2 to 4.

A sleeve 80 is rotatably fitted around the subshaft 34 that supports one end of the friction lever 36, and one end of the friction lever 36 is fixed to the sleeve 80. This sleeve 80 has an actuation arm 82 that is crank-shaped when viewed from the side.
is fixed to the actuating arm 82, and a hook-shaped thread catching portion 82a is formed at the tip of the actuating arm 82. A gate-shaped thread guide body 84 is disposed at the upper end of the left end of the arm part 6 of the sewing machine M, and the thread guide body 84 extends from the upper plate part 84a and the right and left ends of the upper plate part 84a, respectively. First guide plate 84b extending vertically downward
and a second guide plate 84c.
The thread guide body 84 is attached to the machine frame by fixing the guide plate 84c to the upper end of the plate member 50 with screws 86, and the thread guide body 84 is disposed near the top of the operating arm 82. The first guide plate 84b and the second guide plate 84c face each other with a predetermined distance apart in the left-right direction, and the first guide plate 84b and the second guide plate 84c have a first guide groove 88a and a second guide groove 88b, respectively. are formed to face each other laterally, and the rear end portions of the first and second guide grooves 88a and 88b are connected to the upper thread 14.
has been released for introduction. Furthermore, a third guide groove 9 notched from above is provided at the front end of the second guide plate 84c on the left side.
0 is formed.

The upper thread 14 extending from the thread spool 16 is connected to the first guide groove 88a and the second guide groove 88a.
from the left side of the second guide plate 84c through the guide groove 88b.
The yarn is introduced into the guide groove 90 in a bent manner, and is passed from the third guide groove 90 through the britension device 52 and between the yarn path regulating plate 56 and the movable ring 64 at the bent portion of the regulating portion 56a of the yarn path regulating plate 56. It is bent upward, and extends from the bent portion to a thread holding portion 48a at the tip of the thread take-up lever 48, and from the thread holding portion 48a to the eye of the sewing needle 12 via thread guide portions 92 and 94.

The operating arm 82 and the TG movable bar 36 are both fixed to the sleeve 80 and are driven to swing through the balance crank 38 in synchronization with the rotation of the main shaft 28, as shown by solid lines in FIG. The opening actuating arm 8 with the balance 48 in the uppermost position
2 are first and second guide grooves 88a and 8 as shown by dotted lines.
It is located behind the upper thread 14 passing through the front end of the thread 8b, and is activated when the lever 36 swings around the secondary shaft 34 when the thread take-up 48 descends to the lowest position as shown by the imaginary line. The arm 82 also moves forward about the secondary shaft 34 as shown by the imaginary line, and the thread catcher 8 at the tip of the operating arm 82 moves forward.
2a moves forward so as to intersect the needle thread 14 extending between the front ends of the first and second guide grooves 88a and 88b. At this time, the needle thread 14 is let out a predetermined distance forward by the thread catching portion 82a of the operating arm 82. During this unwinding, the upper thread 14 is restrained by the thread path regulating plate 56 and the movable ring 64, so that a predetermined amount of upper thread is reliably let out from the thread spool 16.

In this way, while the thread take-up lever 48 is at the lowest position, the upper thread 14 is let out by the actuating arm 82 of the thread let-out mechanism 78, and passes from the thread let-out mechanism 78 through the britension device 52 to the thread path regulating plate 56. The needle thread 14 reaching the bent portion is in a relaxed state. In this state where the needle thread 14 is loosened, the thread take-up 48 is raised as described above to tighten the needle thread 14, and when the thread passage control device 54 releases the restraint, the feed dog tightens the needle thread 14. The feeding action and the needle swinging action cause the necessary amount of needle thread 14 to be supplied to the thread take-up lever 48 and the sewing needle 12 through the thread passing control device 411 device 54.

Note that cloth feeding is performed even before the upper thread 14 is released, but the amount of the upper thread 14 consumed by this cloth feeding is replenished by the amount of elastic stretch of the upper thread 14, and when the upper thread 14 is released from the restraint. The upper thread 14 is supplied while the amount of elongation is resolved.

In this way, the timing of binding and releasing the upper thread 14 is automatically controlled according to the thickness of the upper thread 14, and the required amount of upper thread 14 determined by the cloth feed amount and needle swing amount is reliably replenished one after another. Therefore, the thread tension is optimal depending on the thickness of the upper thread 14.

Note that the above embodiment may be partially modified as follows.

<11 Regarding the yarn path regulating plate 56 and the movable ring 64 of the yarn passage control device 54, a U groove 64b may be formed on the circumferential surface of the movable ring 64 as shown in FIG. 8, or a U groove 64b may be formed as shown in FIG. The moving direction of the movable ring 64 may be inclined with respect to the thread path regulating plate 56, or the circumferential surface of the movable ring 64 may be formed into a cylindrical surface as shown in FIG. Furthermore, although not shown, a thread path regulating plate 56
The movable plate 5 replaces the movable ring 64 that comes into contact with the regulating portion 56a.
A member fixed to 8 may also be used. Furthermore, as shown in FIG. 11, the regulating portion 56a is configured with a grooved idler ring 56A, the needle thread 14 is bent along the half circumference of the idler ring 56A, and the engaging member 64A in place of the movable ring 64 is replaced by the idler ring 56A. It is also possible to make contact with a point contact point.

(2) The mechanism for driving the movable plate 58 in the yarn passage control device 54 is constituted by an electric actuator, and the drive is controlled by a control signal from a control device not shown.

(3) In the thread passage control device 54, the sewing machine main shaft 28
However, the first arm 74, second arm 76, link arm 60, etc. are omitted, and the spring 66 is omitted.
By appropriately setting the spring force, the structure may be such that passing resistance is applied to the needle thread 14 in the same way as a conventional spring-type thread tension device.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic perspective view of a sewing machine, FIG. 2 is a perspective view of the main parts of the internal mechanism built into the arm and head of the sewing machine, and FIG. 3 is a schematic perspective view of the sewing machine. 4 is a front view of the internal mechanism, FIG. 5 is a time chart showing the operation of each mechanism of the sewing machine, FIG. 6 is a sectional view taken along line Vl-Vl in FIG. 3, and FIG. The figure is a sectional view taken along the line ■--■ in FIG. 4, and FIGS. 8 to 11 are schematic diagrams corresponding to FIG. 6 according to modified examples. M... Sewing machine, 10... Needle bar, 12... Sewing needle, 1
4. Upper thread, 16. Thread spool, 22. Throat plate, 24.
・Needle bar guide, 28... Sewing machine main shaft, 34... Sub-shaft,
36... Swing lever, 38... Balance crank,
40...Crank pin, 42...Cam hole, 42a...
Arc hole, 48... Balance, 48a... Thread holding part, 5
4. Thread passage control device, 56. Thread path regulation plate, 56
a... Regulation part, 56A... Play ring, 58... Movable plate,
60...Link arm, 62...Step screw, 64...
Movable ring, 64A...Engagement member, 66...Spring, 6
8...Contact ring, 70...Rotating cam, 72...Cam groove,
74...First arm, 76...Second arm. Patent applicant: Brother Industries, Ltd.Forward Figure 3Figure 4Figure 6Figure 8Figure 9

Claims (3)

[Claims] (1) A thread supply path that extends from the thread supply source to the eye of the sewing needle and has at least one bending point, and that provides passage resistance to the sewing thread supplied toward the sewing needle or is timed to the rotation of the sewing machine main shaft. and a thread passage control device for stopping the passage of the sewing thread, the thread passage control device moving the thread in a direction parallel to a plane including the thread supply path near the bending point in order to nip the sewing thread. It has a pair of thread engaging bodies that are relatively movable and are arranged on both sides of the bending point, and at least one of the thread engaging bodies is arranged so that the pair of thread engaging bodies are in point contact in the suture feeding direction. A sewing machine capable of controlling thread passage, characterized in that an outer surface is formed into a curved surface in the sewing thread supply direction. (2) The thread engaging body located on the bending direction side of the thread supply path at the bending point is fixed to the sewing machine frame, and the thread engaging body located on the opposite side to the bending direction side is movable to the sewing machine frame. Claim 1 is characterized in that it is installed in
Sewing machine capable of controlling thread passage as described in Section 1. (3) The thread engaging body fixed to the sewing machine frame has a cylindrical curved surface, and the movably installed thread engaging body has a V-shaped groove that can be engaged with the cylindrical curved surface. A sewing machine capable of controlling thread passage according to claim 1.