JPH0639171A - Sewing machine - Google Patents

Abstract

PURPOSE:To provide a sewing machine which is not likely to generate a gap through reduction of the wear of a slide surface and is free from jump of stitches by furnishing a transmitting member having a plane perpendicularly intersecting the axis of a looper rod on the top of a rock arm, and causing contacting a holding member by this plane. CONSTITUTION:The one-way rotational motion of a crank part of a lower shaft is converted into swing motions of a rock arm 10 through a looper rod 7, looper arm 9, and looper shaft 8. The swing motions are converted into horizontal reciprocations of a looper rod 11 by a square piece 12 as a transmitting member. As a result, the looper 4 makes horizontal reciprocations in the axial direction of the looper rod 11. On the other hand, the one-way rotational motion of an eccentric wheel 18 fixed to the lower shaft 6 is transmitted through a fore-and-aft, rod 19, rod pin 20, looper rod guide 21, slider 22, and holder 13 and converted into swing motions of the looper rod 11. As a result, the looper 4 makes swing motions with the axis of looper rod 11 as the center.

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 provided so as to move in synchronization with the vertical movement of a sewing needle,
For example, it relates to a double chain stitch sewing machine.

[0002]

2. Description of the Related Art Conventionally, in this type of sewing machine, the sewing machine shown in FIG.
As shown in FIG. 3, the unidirectional rotational movement of the spherical crank portion 31a eccentric to the axis of the lower shaft 31 that rotates in synchronization with the vertical movement of the sewing needle 30 is performed by the looper rod 32 and the looper arm 33.
Via the looper shaft 34 and the swing arm 35 fixed to the looper shaft 34 into a reciprocating rotary motion within a predetermined angle range (hereinafter, this motion is referred to as a swing motion). The upper end cylindrical portion 35a of the swing arm 35 is sandwiched by the holder left 37 and the holder right 38 fitted and fixed to the looper rod 36 so that there is no clearance on both side surfaces of the swing arm upper end cylindrical portion 35a. Then, the swing motion of the swing arm 35 is converted from the swing arm upper end cylindrical portion 35a into a horizontal reciprocating motion of the looper bar 36 via the holder left 37 and the holder right 38. Along with this, the looper 40 fixed to one end of the looper rod 36 horizontally reciprocates in the axial direction of the looper rod 36.

On the other hand, as shown in FIG. 10, an eccentric ring 4 eccentrically attached to the axis of the lower shaft 31 and detachably supported by the lower shaft 31.
One unidirectional rotational movement is converted into a swinging movement of the looper bar guide 43 via the front and rear rods 42. Holding the slider 44 inserted in the tapered long hole groove 43a in the looper bar guide 43 and the slider 44,
The holder left 37 fitted and fixed to the looper rod 36 causes the looper rod 36 to perform a swinging motion. Along with this, the looper 40 fixed to one end of the looper rod 36 swings back and forth around the axis of the looper rod 36.

In the above structure, the looper 40 performs an elliptic motion as shown in FIG. 3 by a combined motion of the horizontal reciprocating motion of the looper rod 36 in the axial direction and the back-and-forth swinging motion about the axial line. The front surface of the sewing needle 30 that moves up and down,
The back surface is moved back and forth alternately, and in cooperation with the sewing needle 30, a stitch such as a double chain stitch is formed.

[0005]

However, in the above-described conventional structure, since the upper end cylindrical portion 35a of the swing arm is cylindrical, the contact portions with the holder left 37 and the holder right 38 are in line contact, and the rotation is particularly high. In this case, a large load is applied to the contact portion of the swing arm upper end cylindrical portion 35a.

In particular, at both ends of the elliptical movement, inertial forces of the looper 40, the looper holder 45, the looper rod 36, etc. act to cause knocking wear at the contact portions. Therefore, when the sewing machine is operated for a long period of time, wear occurs on the swing arm upper end cylindrical portion 35a, the holder left 37, and the holder right 38 as shown in FIG. 11, resulting in a clearance in the horizontal movement direction.

When the clearance is generated, the rotational momentum of the sewing machine is increased and the horizontal momentum of the looper 40 is increased by the clearances on both sides. Therefore, when the looper blade tip 40a captures the loop formed by the sewing needle 30. The position of passing over the needle hole of is lower than the normal position, and the loop may be missed. In addition, the position where the sewing needle 30 is inserted between the loops formed by the looper 40 is displaced to the right from the normal position, and the sewing needle 30 may be inserted between the loops and miss the position. Therefore, stitch skipping occurs,
Defective products occur in sewn products. FIG. 12a shows a state of the regular sewing needle 30 and the looper blade tip 40a, and FIG. 12b shows a state of the sewing needle 30 and the looper blade tip 40a which easily cause skipping.

In such a case, in order to prevent the stitch skipping, the holder left 37 and the holder right 38 should be eliminated so as to eliminate the gap.
It is necessary to move either position. However, if the positions of the holder left 37 and the holder right 38 are changed so as to eliminate the clearance at either end of the elliptical motion stroke, the swing arm upper end cylindrical portion 35a and the holder 35a at the center of the elliptical motion stroke and the holder are changed. Since the sliding portions of the left 37 and the holder right 38 have a small amount of wear, the swing arm upper end cylindrical portion 35a is fixed by the holder left 37 and the holder right 38 at the center of the elliptical movement stroke, and the sewing machine does not rotate. If, for example,
Even if it rotates, the rotation torque becomes very heavy, the load is applied to the motor, the rotation of the sewing machine does not reach the normal rotation speed, and the seizure of the motor occurs.

Therefore, the present invention has been made to solve the above-mentioned problems, and a transmission member having a plane substantially orthogonal to the axis of the looper bar is provided at the upper end of the swing arm.
Since it makes contact with the holding member on that plane,
An object of the present invention is to provide a sewing machine in which stitches are not skipped by significantly reducing the wear of the sliding surface and making it difficult to form a clearance.

[0010]

A sewing machine of the present invention has a lower end to which a sewing needle can be attached, a needle bar drive mechanism for vertically reciprocating the needle bar, and a lower thread for engaging a needle thread. And the looper bar having one end fixed to the looper is oscillated around a fixed axis in a direction orthogonal to the cloth feed direction in synchronization with the vertical movement of the needle bar, and the axis line is provided via a holding member. A sewing machine provided with a looper drive mechanism that is movable along a plane, for moving the looper bar along the axis by contacting a holding member on the plane having a plane substantially orthogonal to the one fixed axis. Is characterized in that a transmission member of is provided.

[0011]

In the sewing machine of the present invention having the above-mentioned structure, the looper drive mechanism is arranged such that the looper rod having the looper fixed at one end is timed with the vertical movement of the needle bar and is fixed in a direction perpendicular to the cloth feed direction. Is swung around and is moved to the axis through the holding member. The transmission member contacts the holding member and moves the looper bar along the one fixed axis in a plane substantially orthogonal to the one fixed axis.

With the above functions, the transmission member converts the swinging motion of the swinging arm, which moves in synchronization with the vertical motion of the needle bar, into the horizontal reciprocating motion of the looper bar through the holding member. Reciprocate the looper fixed to. Then, by operating the looper and the needle in cooperation, the lower thread is engaged with the needle thread to form a stitch.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a decorative sewing machine will be described below with reference to the drawings.

As shown in FIG. 8, the decorative stitch sewing machine comprises a sewing machine bed portion 1 and an arm portion 2 which is erected from the right end portion of the bed portion 1 and extends leftward. In the bed 1, a feed dog drive mechanism (not shown) for feeding cloth, a looper 4 for catching a loop of the needle thread 5 can be swung about a fixed axis in a direction orthogonal to the cloth feeding direction A looper drive mechanism (see FIG. 1) and the like are provided so as to be movable. On the other hand, the arm portion 2 is provided with, for example, a needle bar drive mechanism (not shown) capable of mounting three sewing needles 3 on the lower end. Then, the decorative stitch sewing machine configured by the above mechanism rotates the sewing machine, whereby the sewing needle 3 moves up and down, and in synchronization with this movement, the looper 4 makes an elliptical movement so that the looper 4 can engage with the needle thread 5. This creates a seam,
Sewing is performed.

Now, a mechanism for driving the looper 4 in the bed portion 1 will be described with reference to FIGS. 1 to 7.

First, a drive mechanism in the major axis direction (direction of arrow A) of the elliptic motion of the looper 4 shown in FIG. 3 will be described with reference to FIG. One end of a looper rod 7 is rotatably connected to a spherical crank portion 6a of the lower shaft 6 which is rotated in one direction by a sewing machine motor (not shown). The other end of the looper rod 7 is rotatably connected to a looper arm 9 fixed to a looper shaft 8 so that the looper shaft 8 performs a swinging motion. A swing arm 10 is fixed to the looper shaft 8, and a square piece 12 that is rotatable in a direction orthogonal to the axis 11a of the looper rod 11 is connected to the upper end of the swing arm 10. As shown in FIGS. 4 and 5, the square piece 12 has two planes 12a and 12b which are parallel to the looper rod axis 11a in a direction perpendicular to the looper rod axis 11a. 13 facing the square piece of 13 and the holder right 14
It is slidably sandwiched by a and 14a.

The swing piece of the swing arm 10 is converted into a horizontal reciprocating movement by the square piece 12, the holder left 13, and the holder right 14. As a result, the looper bar 11 supported by the metal right 15 and the metal left 16 facing the sewing machine main body moves horizontally in the left-right direction. And the looper bar 11
A looper holder 17 is fitted and fixed to the left end of the looper 4. Since the looper 4 is fixed to the looper holder 17, the looper 4 also horizontally moves in the left-right direction.

Next, a drive mechanism in the minor axis direction (direction of arrow B) of the elliptic motion of the looper 4 shown in FIG. 3 will be described with reference to FIG. One end of a front and rear rod 19 is rotatably connected to an eccentric wheel 18 fixed to the lower shaft 6 which is rotated in one direction by a sewing machine motor, and the other end of the front and rear rod 19 is rotatably connected to a rod pin 20. The mounting position of the rod pin 20 on the looper bar guide 21 can be changed within a predetermined range. Therefore, the rotary motion of the eccentric wheel 18 is changed by the front and rear rods 19 to the looper bar guide
Is converted into a swinging motion. The oscillating motion of the looper bar guide 21 is such that one end is inserted into the tapered long hole 21a of the looper bar guide and the other end is fixed to the holder left 13 fitted and fixed to the looper bar 11 and fixed to the slider 22. Is transmitted to the looper bar 11. As a result, the looper 4 also swings around the looper rod axis 11a.

The operation of the decorative sewing machine constructed as above will be described.

The one-way rotational movement of the crank portion 6a of the lower shaft 6 is performed by the looper rod 7, the looper arm 9, and the looper shaft 8.
Is converted into a swinging motion of the swinging arm 10. This swinging motion is converted into a horizontal reciprocating motion of the looper bar 11 by the square piece 12. As a result, the looper 4 horizontally reciprocates along the axial direction of the looper rod 11. At the same time, the unidirectional rotational movement of the eccentric wheel 18 fixed to the lower shaft 6 is caused by the front and rear rods 19, the rod pins 20, the looper rod guides 21,
Looper rod 1 via slider 22 and holder left 13
1 is converted into a swinging motion, and as a result, the looper 4 swings around the axis of the looper rod 11.

From the above, the tip of the sword of the looper 4 is an elliptic motion as shown in FIG. 3 due to the combined motion of the reciprocating motion of the looper rod 11 in the axial direction and the swinging motion about the axial line of the looper rod 11. I do. Due to this elliptical movement, the tip of the looper 4 advances and retreats alternately on the front surface and the back surface of the sewing needle 3 which moves up and down, and cooperates with the sewing needle 3 to form a seam such as a double chain stitch.

According to this embodiment, the looper 4
In the mechanism for horizontally reciprocating in the major axis direction of the elliptic motion of No. 2, the sliding area is provided by providing the square piece 12 at a position where the swinging motion of the swinging shaft 10 is converted into the horizontal reciprocating motion of the looper rod 11 and transmitted. Is widened, and the inertial force in the axial direction of the looper rod 11 due to the looper 4, the looper holder 17, the looper rod 11, etc. received per unit area is reduced, the wear of the sliding surface can be greatly reduced, and the durability performance is improved. It can be dramatically improved. Therefore, the amount of horizontal reciprocating motion of the looper 4 does not increase, and the sword tip of the looper 4 passes over the needle hole when catching the loop formed by the sewing needle 3 and between the loop formed by the looper 4 and the sewing needle 3 The position to insert is also unchanged. Therefore, the defect of the sewn product due to the stitch skipping does not occur. Further, even if the sewing machine is used at a high speed for a long period of time, the clearance of the sliding portion is not significantly increased, so that the change in the sound of the sewing machine is small and the working environment burden on the sewing manufacturer is not increased.

In this embodiment, as shown in FIG. 4, the square piece 12 integrally has a shaft portion rotatable at a top end of the swing arm 10 in a direction orthogonal to the looper rod axis 11a. However, as shown in FIG. 7A, the square piece 23 and the shaft 2
4 may be divided into two parts. In addition, FIG.
A shaft portion may be arranged on the upper end portion of the swing arm 25 as shown in FIG.

[0024]

As is apparent from the above description, the present invention is as follows.
In order to reciprocate the looper rod to which the looper is fixed in the axial direction thereof, a motion transmitting portion between the swing arm and the looper rod is provided with a transmitting member having a plane substantially orthogonal to the looper rod axis, thereby providing the motion transmitting portion. The wear on the sliding surface of can be greatly reduced, and the durability performance can be dramatically improved. Furthermore, there is no need to readjust the clearance of the sliding part,
It is possible to obtain a good sewn product without skipping stitches for a long time. Also, even if the sewing machine is used at high speed for a long period of time, the increase in the clearance of the sliding part is very small, so there is little change in the sewing machine sound, and the excellent work environment burden on the sewing manufacturer does not increase. Play.

[Brief description of drawings]

FIG. 1 is a perspective view of a looper mechanism showing an embodiment of the present invention.

FIG. 2 is a front sectional view of a looper mechanism.

FIG. 3 is a diagram showing a locus of a sword tip of a looper.

FIG. 4 is an exploded view of a transmission member according to an embodiment of the present invention.

FIG. 5 is an enlarged view of a transmission member according to an embodiment of the present invention.

6 is a vertical cross-sectional view taken along the line YY of FIG.

FIG. 7 (a) is a partial cross-sectional view of a modified example of the present invention. FIG. 7B is a partial cross-sectional view of a modified example of the present invention.

FIG. 8 is a perspective view showing the external appearance of the sewing machine main body.

FIG. 9 is a view corresponding to FIG. 2 showing a conventional example.

FIG. 10 is a view corresponding to FIG. 6 showing a conventional example.

FIG. 11 is a diagram showing a state after a long time operation in the conventional example.

FIG. 12A is a diagram showing a state in which the relationship between the sewing needle and the tip of the sword of the looper is normal. FIG. 12B is a diagram showing a state where the relationship between the sewing needle and the tip of the sword of the looper is likely to cause skipping.

[Explanation of symbols]

 3 Sewing needle 4 Looper 5 Needle thread 11 Looper bar 12 Square piece (transmission member) 13 Holder left (holding member) 14 Holder right (holding member)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsunefumi Ito 15-1 Naesehiro-cho, Mizuho-ku, Nagoya City Brother Industries Ltd. (72) Inventor Hiroyasu Iwakoshi 15-1 Naesehiro-cho, Mizuho-ku, Nagoya City Brother Engineer Industry Co., Ltd. (72) Inventor Kiyoshi Ueda 15-1 Naeshiro-cho, Mizuho-ku, Nagoya City Brother Industry Co., Ltd.

Claims (1)

[Claims] 1. A needle bar having a lower end to which a sewing needle can be attached, a needle bar drive mechanism for vertically reciprocating the needle bar, a looper for engaging a lower thread with a needle thread, and the looper at one end. The fixed looper bar can be oscillated around one fixed axis in the direction orthogonal to the cloth feed direction in synchronization with the vertical movement of the needle bar.
In a sewing machine including a looper drive mechanism that is movable along the axis via a holding member, the sewing machine has a plane that is substantially orthogonal to the one fixed axis, and contacts the holding member on the plane to move the looper bar. A sewing machine having a transmission member for moving along the axis.