JPH0686886A - Sewing machine - Google Patents

Abstract

PURPOSE:To cut a needle thread stably and surely by regulating the movement of the needle thread by a groove provided on a bar looper for engaging a bobbin thread with the needle thread at the time of cutting the needle thread inserted in a sewing needle and the bobbin thread inserted in the looper. CONSTITUTION:A sewing machine sews with a needle thread inserted in a vertically moving sewing product 12 and a bobbin thread 18 inserted 10 a looper 34 moved horizontally forward and backward alternately with the sewing needle 12. At the end of sewing operation or at the time of shifting from one sewing line to the next sewing line, the needle thread 20 is cut with an upper knife 22 and a lower knife 24 automatically or by the manual operation. At that time, the needle thread 20 is stored in a groove part 34 provided on the root area 34b of the looper 34, thereby regulating the axial movement of the needle thread. Thus, the needle thread 20 is kept stable to be cut surely so that sewing work can be improved in efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine provided with a looper for engaging a lower thread with a needle thread inserted in a sewing needle and a cutting mechanism for cutting the needle thread moved along the looper. is there.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, sewing machines for double chain stitches and decorative stitches have a single or plural sewing needles 1.
2. A needle bar drive mechanism that vertically reciprocates the needle bar 14 attached to the lower end, and a looper 206 that reciprocates in the arrow L direction orthogonal to the cloth feed direction of the arrow K direction in accordance with the vertical reciprocating motion of the needle bar 14. It was equipped with a looper drive mechanism and a thread trimming device arranged immediately below the needle plate of the sewing machine bed. This thread trimming device uses the lower thread 18 and the needle thread 2 at the end of sewing.
The one in which 0 is cut by the upper knife 22 and the lower knife 24 automatically or manually is used. This lower female 2
4, a pressing spring (not shown) receives an upward biasing force (blade pressure) at the center thereof, so that the needle thread 20 can be cut most reliably at the center of the upper knife 22 and the lower knife 24.

After feeding the cloth, as shown in FIG.
4 moves from the looper root portion 206b to the looper tip portion 206a in the arrow B direction. After that, the lower knife 24
The looper 206 is moved from the looper tip portion 206a in the direction of arrow A to the looper root portion 206b and returned. During the movement, the lower thread 1 of the looper 206 is attached to the first hook 24a of the lower knife 24.
8 is engaged, the needle thread 20 is engaged with the second hook 24b, and the lower knife 24 further returns and moves, the lower thread 18 engaged with the first hook 24a and the second hook 24b are engaged. The needle thread 20 thus cut is sequentially cut by the upper knife 22 and the lower knife 24.

[0004]

[Problems to be Solved by the Invention] However, the needle thread 2
When 0 is cut by the upper knife 22 and the lower knife 24, the needle thread 20 shifts to the outside of the lower knife 24, the needle thread 20 becomes far from the center of the upper knife 22 and the lower knife 24, and the blade pressure is at a weak position. If so, there is a problem that a thread trimming error occurs.

Further, as shown in FIG. 8, since the looper root portion 206b is thicker than the looper tip portion 206a in order to have sufficient strength to fix the looper 206, as shown in FIG. And the root part 20 of the looper
The needle thread 20 moved to 6b spreads as shown by the broken line than when it is located at the looper tip portion 206a shown by the solid line, and moves to the outside of the second hook 24b. In that case, the needle thread 20 becomes far from the centers of the upper knife 22 and the lower knife 24, and the blade pressure becomes weak, so that there is a problem that a thread trimming error easily occurs, and further, the width of the loop formed by the needle thread widens. If the needle thread 20 becomes large, the needle thread 20 may come off the lower knife 24. Further, since the thread cutting operation is performed after the cloth is fed, when the stitch pitch is large as shown by the broken line in FIG. 10, the needle thread 20 is lower than the lower stitch when the stitch pitch shown by the solid line is small. 24
Therefore, when the stitch pitch is particularly large, the needle thread 20 similarly causes the needle thread 20 to be located outside.
2 and the lower knife 24 become farther from the center and the blade pressure becomes weaker, which causes a problem that thread cutting mistakes easily occur.

The invention described in claim 1 has been made to solve the above-mentioned problems, and a sewing machine capable of reliably cutting the needle thread by preventing the needle thread from shifting during cutting. Is intended to provide. Claim 2
The invention described in (1) is made in order to solve the above-mentioned problems, and an object thereof is to provide a sewing machine that can reliably cut a needle thread regardless of the shape of the looper. The invention set forth in claim 3 is made to solve the above-mentioned problems, and an object thereof is to provide a sewing machine capable of reliably cutting a needle thread regardless of the size of the stitch pitch. I am trying.

[0007]

In order to achieve this object, the sewing machine according to claim 1 of the present invention is provided with a regulating portion for regulating the movement of the needle thread when the cutting means cuts the needle thread. It has a looper.

In order to achieve this object, the sewing machine according to claim 2 of the present invention has a cutting means arranged near the root of the looper and a needle thread moved from the tip of the looper toward the root. And a looper having a restriction portion formed of a concave portion.

Further, in order to achieve this object, the sewing machine according to claim 3 of the present invention comprises a looper in which a regulating portion is formed on the downstream side surface of the workpiece cloth in the feed direction.

[0010]

In the sewing machine according to the first aspect of the present invention having the above structure, the regulation portion provided on the looper regulates the movement of the needle thread, and the cutting means reliably cuts the needle thread.

Further, in the sewing machine according to the second aspect of the present invention having the above-mentioned structure, the restriction portion formed by the recess restricts the movement of the needle thread and narrows the width of the loop formed by the needle thread.
Irrespective of the shape of the looper, the cutting means arranged near the root of the looper surely cuts this needle thread.

Further, in the sewing machine according to claim 3 having the above-mentioned structure, the regulating portion provided on the downstream side surface of the looper in the cloth feeding direction regulates the movement of the needle thread and the width of the loop formed by the needle thread. Is made narrower and the cutting means surely cuts the needle thread regardless of the stitch pitch.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The same numbers are given to the same configurations as the conventional configurations.

As shown in FIG. 2, the decorative stitch sewing machine 10 is composed of a bed portion 30 and an arm portion 32 standing upright from the bed portion 30. Tooth drive mechanism (not shown), looper 34
Looper drive mechanism (see FIG. 4) for reciprocally driving the cloth in a direction orthogonal to the cloth feed direction (arrow K direction), and a thread trimming device for simultaneously cutting the lower thread 18 of the looper 34 and the needle thread 20 of the sewing needle 12 (See FIGS. 5 and 6) and the like are provided. Further, the arm portion 32 is provided with a needle bar drive mechanism (see FIG. 3) for moving the needle bar 14 up and down, and at the lower end of the needle bar 14, three sewing needles 12 are attached so that they can be attached. Has been.

Next, the needle bar drive mechanism will be described with reference to FIG.

An upper shaft 40 is rotatably supported inside the arm portion 32, and an end portion of the upper shaft 40 is
The needle bar crank 42 is fixed, and one end of a connecting lever 44 is rotatably connected to the end of the needle bar crank 42. The other end of the connecting lever 44 has a needle bar holder 4
6, the needle bar 14 is reciprocally driven in the vertical direction via the connecting lever 44 in accordance with the rotation of the needle bar crank 42. . The needle attachment 50 is fixed to the lower end of the needle bar 14, and the sewing needle 12 is attached to the needle attachment 50 as described above. A needle thread 20 is inserted through a needle hole (not shown) of the sewing needle 12.

Next, the looper drive mechanism arranged in the bed portion 30 will be described with reference to FIG.

A lower shaft 54 is rotatably supported inside the bed portion 30 and is rotatably driven by a known sewing machine motor (not shown) in association with the upper shaft 40. . The lower shaft 54 has a crank portion 56.
Further, the upper end portion of the vertical connecting lever 58 is rotatably attached to the protruding portion of the crank portion 56. Therefore, the vertical connecting lever 58 is
As the lower shaft 54 rotates, it moves up and down. At the lower end of the vertical connecting lever 58, a tip end of a horizontal arm 62 fixed to a rotating shaft 60 is swingably attached. The rotating shaft 60 is rotatably supported inside the bed portion 30 so as to be orthogonal to the lower shaft 54, and thus,
The rotating shaft 60 reciprocally rotates within a certain rotation range as the lower shaft 54 rotates.

A lower end of a vertical arm 64 is fixed to the rotary shaft 60, and the vertical arm 64 extends above the rotary shaft 60. The upper end of the vertical arm 64 is divided into two legs, and the looper bar 66 is sandwiched between the two legs. The looper bar 66 is disposed parallel to the lower shaft 54, is rotatable, and is supported inside the bed portion 30 so as to be slidable in the axial direction (arrow P direction). A plate-shaped fixing member 6 is provided on the looper bar 66.
8 and 69 are fixed by sandwiching the forked portion of the vertical arm 64, so that the looper rod 66 moves the looper rod 66 in the axial direction (arrow P direction) as the lower shaft 54 rotates. Reciprocate to.

Further, the looper bar 66 is slidably inserted into both end portions 70a and 70c of a substantially U-shaped connecting member 70, and an intermediate portion 70b of the connecting member 70 is
It is located above the looper bar 66. A guide groove 70d is formed in the intermediate portion 70b, and an upper end portion 68a protruding upward of the fixing member 68 is movably inserted in the guide groove 70d along the guide groove 70d. One end of a horizontal connecting lever 76 is swingably attached to the side surface of the intermediate portion 70b. The other end of the horizontal connecting lever 76 is rotatably attached to the lower shaft 54 via an eccentric cam 78, and accordingly,
The horizontal connecting lever 76 swings the connecting member 70 as the lower shaft 54 rotates. The looper bar 66 is connected to the connecting member 70 via the fixing member 68, and thus the looper bar 6 is connected.
The reference numeral 6 is adapted to reciprocally rotate (arrow Q direction) within a constant rotation range in accordance with the rotation of the lower shaft 54, and also slide back and forth in the axial direction (arrow P direction).

The looper 34 is fixed to the tip of the looper rod 66 via a looper fixing member 80. As shown in FIG. 1, a groove portion 34d is obliquely formed on the side surface on the downstream side in the cloth feeding direction K near the looper root portion 34b. The groove 34d holds the needle thread 20 near the center of the lower knife 24 during thread cutting and prevents the width of the loop formed by the needle thread 20 from being expanded. The depth of the groove 34d and the oblique adjustment are set based on the arrangement of the thread cutting mechanism and the looper 34, which will be described later, and the movement amount of the looper 34.

Further, as shown in FIG. 4, the looper 3 is
4 has a thread groove 34e formed along the axial direction thereof, and the through holes 34f, 34 are provided at both ends of the thread groove 34e.
g (see FIG. 1) are respectively provided. Further, the downstream side surface of the looper 34 in the cloth feeding direction K is provided with an inclination for allowing the sewing needle 12 to slide on the surface of the looper 34 when the sewing needle 12 and the looper 34 are engaged with each other. There is.

The looper 34 rotates in the axial direction of the looper bar 66 (the direction of arrow P) as the lower shaft 54 rotates.
It reciprocates and swings (in the direction of arrow Q). Further, the lower shaft 54 is adapted to rotate corresponding to the upper shaft 40, and
Corresponds to the vertical movement of the sewing needle 12, so that the lower thread 18 and the needle thread 20 can be engaged with each other.

Next, a thread cutting device installed in the bed portion 30 immediately above the looper drive mechanism will be described with reference to FIGS. 5 and 6.

A base plate 82 is screwed in the bed portion 30, an upper female lever 84 is movably attached to the base plate 82 along a groove portion 84a, and a lower female lever 86 is in a groove portion 86a.
It is movably attached along 86b. The upper knife 22 is fixed to the upper knife lever 84, and the lower knife 24 having a first hook 24a and a second hook 24b formed at the tip thereof is fixed to the lower knife lever 86. The lower knife lever 86 is formed with an engaging portion 86c that engages with the upper knife lever 84, and as the lower knife lever 86 moves, the engaging portion 8c.
By engaging 6c with the upper knife lever 84, the upper knife lever 84 moves together with the lower knife lever 86. The thread cutting end of the upper knife 22 is located immediately above the looper root 34d when thread cutting the needle thread 20.

Incidentally, the first formed on the lower knife 24
The hook 24a and the second hook 24b are the lower female 24
Is formed so as to be cut into the central portion of the. Further, the upper knife 22 and the lower knife 24 stand by behind the looper 34 (downstream in the cloth feeding direction) during sewing so as not to interfere with the sewing.

A drive lever 90 is rotatably attached to the base plate 82 at its central portion, and one end of the drive lever 90 is attached to the lower female lever 8.
6, and the other end is rotatably connected to the operating shaft 92 of the thread trimming drive mechanism. A compression spring 94 is applied between the upper knife lever 84 and the base plate 82, and the upper knife lever 84 is always biased in the direction of arrow B by the biasing force of the compression spring 94. Further, a contact portion 84b is formed on the upper knife lever 84, and the contact portion 84b moves along with the movement of the upper knife lever 84 in the direction of arrow B.
It comes in contact with the stopper member 96 protrudingly provided to regulate the amount of movement.

The lower knife 24 is biased upward by a pressing spring (not shown) so that the blade pressure thereof is the upper knife 22.
And the lower scalpel 24. Since this pressing spring is provided at the center of the upper knife 22 and the lower knife 24, the center of the upper knife 22 and the lower knife 24 has the highest blade pressure and is the position where the thread can be cut most. . That is, if the needle thread 20 is positioned inside the first hook 24a and the second hook 24b without the width of the loop formed by the needle thread 20 being widened, the needle thread 20 is reliably cut.

The drive mechanism for thread cutting will be described below.

The operating shaft 92 is supported by a supporting member 98 attached to the bed portion 30 so as to be movable in the left and right directions. The operating shaft 92 has an operating lever 10
One end of 0 is fixed, and the other end of the operating lever 100 is connected to a plunger 108 of a solenoid 106 fixed to the bed 30. Accordingly, when the solenoid 106 is driven, the upper female lever 84
The lower female lever 86 is adapted to move in the direction of arrow B. When the solenoid 106 is no longer driven, the urging force of the compression spring 104 causes the upper knife lever 84 and the lower knife lever 86 to move in the arrow A direction. A compression spring 104 is provided between the spring receiving member 110 fixed on the operating shaft 92 and the supporting member 98.
Is installed.

Next, the thread cutting operation of the sewing machine thus constructed will be described.

After the sewing is completed, when the sewing needle 12 is raised to the needle up position and the looper 34 is moved to the engagement position which is the leftmost limit position shown in FIG. 4, the solenoid 106 is driven to operate the operating shaft. When 92 moves from the standby position shown in FIG. 5 in the direction of arrow A, the lower female lever 8 is moved through the operating lever 90.
6 is once obliquely moved along the groove portion 86a formed in the lower female lever 86, and then linearly moved in the direction of arrow B (the position shown in FIG. 6).

With the movement of the lower female lever 86, the upper female lever 84 is simultaneously moved to the arrow B by the action of the compression spring 94.
While moving in the direction, the upper female lever 84 abuts on the stopper member 96 during the movement and its movement is restricted and stops at the cutting position. At this time, the tip portion of the lower knife 24 moves in the direction of arrow B to the operating position immediately above the looper 34.

Thereafter, when the solenoid 106 is no longer driven, the lower knife 24 and the lower knife lever 86 move linearly in the direction of arrow A by the urging force of the compression spring 104, and then move diagonally to the standby position shown in FIG. Located in. During the movement of the lower knife 24 to the standby position (straight line movement), the lower thread 14 of the looper 34 is engaged with the first hook 24a, and the needle thread 2 is attached to the second hook 24b.
0 is engaged. Then, the lower thread 14 engaged with the first hook 24a and the needle thread 20 engaged with the second hook 24b are sequentially cut by the upper knife 22 and the lower knife 24. At this time,
As shown in FIG. 1, the needle thread 20 hooked on the second hook 24b of the lower knife 24 is pulled by the lower knife 24 and slides on the side surface of the looper 34 to form the looper root portion 34b.
Move to.

The needle thread 20 is looper root portion 34b.
Since the needle thread 20 is locked and the needle thread 20 is stable, it is surely cut. Further, at this time, since the needle thread 20 enters the groove 34d, the width of the loop formed by the needle thread 20 does not widen due to the shape of the looper root portion 34b, and the position of the needle thread 20 is located at the upper knife 22 and the lower knife 2
The needle thread 20 is reliably cut because it is held near the center of 4 and thread cutting is performed at a position where the blade pressure is sufficiently applied.
Further, since the groove portion 34d provided on the side surface of the looper 34 on the downstream side in the cloth feeding direction is formed, the width of the loop formed by the needle thread 20 is narrowed even if the stitch pitch is increased. Therefore, the thread is cut at the position of the needle thread 20 at the center of the upper knife 22 and the lower knife 24, that is, the position where the blade pressure is sufficiently applied, so that the needle thread 20 is reliably cut. In this way, since thread cutting is performed at the central portions of the upper knife 22 and the lower knife 24, the size of the upper knife 22 and the lower knife 24 can be small, and the design of other mechanisms inside the bed 30 can be reduced. The degree of freedom is increased and the bed portion 30 can be made compact.

Instead of the solenoid 106, an air cylinder or various types of actuators can be used.
Further, it is needless to say that the present invention can be applied to loopers of various kinds of sewing machines such as a decorative stitch sewing machine and a double chain stitch sewing machine in which a spreader is provided and an upper decorative thread is used. Further, it is only necessary that the width of the loop formed by the needle thread 20 becomes narrow, and it may be provided on the upstream side of the cloth feed.

[0037]

As is apparent from the above description, since the regulation portion provided on the looper regulates the movement of the needle thread, the needle thread is stably cut by the cutting means. Further, since the concave portion restricts the movement of the needle thread and narrows the width of the loop formed by the needle thread, the width of the loop formed by the needle thread does not widen due to the shape of the looper, and the needle thread is close to the root of the looper. It is surely cut by the cutting means arranged at. Further, since the regulating member is provided on the downstream side surface of the looper in the cloth feeding direction, and the regulating portion regulates the movement of the needle thread and narrows the width of the loop formed by the needle thread, the stitch pitch is large. Even then, the needle thread is reliably cut by the cutting means.

[Brief description of drawings]

FIG. 1 is a partial perspective view showing a relationship among a looper, a lower knife and a needle thread during thread cutting.

FIG. 2 is a perspective view of a decorative sewing machine provided with a thread cutting device.

FIG. 3 is a perspective view of a needle bar drive mechanism.

FIG. 4 is a perspective view of a looper drive mechanism.

FIG. 5 is a plan view of the thread cutting mechanism when the solenoid is not driven.

FIG. 6 is a plan view of the thread cutting mechanism when a solenoid is driven.

FIG. 7 is a partial perspective view showing the relationship between the sewing needle and the looper.

FIG. 8 is a view corresponding to FIG. 1 according to a conventional technique.

FIG. 9 is an explanatory diagram illustrating the relationship between the needle thread and the lower knife as seen from the tip of the looper.

10 is a view corresponding to FIG. 8 when the stitch pitch is large.

[Explanation of symbols]

 12 Sewing needle 18 Lower thread 20 Needle thread 22 Upper knife 24 Lower knife 34 Looper 54 Lower shaft 66 Looper bar

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naofumi Ikeda 15-1 Naedai-cho, Mizuho-ku, Nagoya-shi Brother Industrial Co., Ltd. (72) Inventor Tsunefumi Ito 15-1 Naedai-cho, Mizuho-ku, Nagoya-shi Brother Industry Co., Ltd. (72) Inventor Kiyoshi Ueda 15-1 Naeshiro-cho, Mizuho-ku, Nagoya City Brother Industry Co., Ltd.

Claims (3)

[Claims] 1. A rod-shaped looper for engaging another bobbin thread with a needle thread inserted into a sewing needle, a moving means for moving the needle thread along a side surface of the looper, and attached in the vicinity of the looper. A sewing machine that cuts the needle thread moved by the moving means, the looper is provided with a restricting portion that restricts movement of the needle thread when the cutting means cuts the needle thread. Sewing machine characterized by that. 2. The cutting means is disposed in the vicinity of the root of the looper, the needle thread is moved from the tip of the looper toward the root by the moving means, and the restricting portion is attached to the looper. The sewing machine according to claim 1, wherein the sewing machine is formed by a formed recess. 3. The sewing machine according to claim 2, wherein the restriction portion is formed on a side surface of the workpiece cloth on the downstream side in the feeding direction.