JPH0871282A - Automatic thread cutter - Google Patents

Abstract

PURPOSE: To provide an automatic thread cutter capable of sharply simplifying the structure of the thread cutter, reducing the cost, and rationalizing the kinetic dynamics of thread cutting. CONSTITUTION: This automatic thread cutter is provided with a thread cutting edge 5 fixed at the slant angle of about 45 deg. against the fabric feeding direction near a needle hole 4 below a throat plate 1 and a needle thread holder 6a and a bobbin thread holder 6b integrally rotatably supported on a shaft 7. When the needle thread holder 6a and bobbin thread holder 6b are rotated by a rotary solenoid 8, a needle thread 20 and a bobbin thread 22 held by thread hold sections 6c of the needle thread holder 6a and bobbin thread holder 6b are pressed to a thread cutting edge 5, and they are slid and cut on the edge 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic thread cutting device which automatically cuts a yarn to be cut based on a thread cutting command.

[0002]

2. Description of the Related Art Conventionally, in this type of automatic thread cutting device, for example, a thread cutting device of a sewing machine cuts upper and lower yarns by sliding a fixed blade and a moving blade that swings. . This general thread cutting mechanism is configured as shown in FIG. The operation of the thread cutting device will be described with reference to FIG. Incidentally, FIG. 4 is a perspective view with the shuttle removed.

When a thread cutting operation is instructed by operating a foot pedal or the like (not shown), a voltage is applied to the thread cutting solenoid 50 and the plunger 52 is displaced by a predetermined amount in the direction of arrow A in FIG. .

Along with this, the thread trimming cam lever set 54 is displaced in the direction of arrow A. The roller shaft 56 attached to the thread trimming cam lever set 54 is also displaced in the direction of arrow A at the same time, and moves on the circumference of the thread trimming cam 58. In addition, the thread trimming cam lever set 54
At the same time, the protrusion 60 attached to the shaft also moves in the direction of arrow A and deeply enters into the notch 63 of the bifurcated shaft 62. The shaft portion of the bifurcated shaft 62 is rotatably supported by the sewing machine frame.

As the lower shaft 64 rotates in the direction of arrow E,
The thread trimming cam 58 pushes up the roller shaft 56 in the direction of arrow C,
Rotational movement in the direction of arrow C is transmitted to the bifurcated shaft 62 via the thread trimming cam lever set 54.

A thread trimming lever 6 attached to a bifurcated shaft 62.
6 transmits the motion to the thread cutting holder 70 through the thread cutting connecting rod 68, and the thread cutting holder 70 rotates in the direction of arrow C. The thread trimming holder 70 is rotatably attached on the same axis as the rotating shaft of the lower shaft 64.

The movable blade 72 attached to the thread trimming holder 70 also rotates in the direction of arrow C and slides on a fixed blade (not shown) to cut the upper and lower threads.

Further, the lower shaft 64 further rotates in the direction of arrow E, and the action of a thread trimming lever spring (not shown) and the thread trimming cam 58 are performed.
The shape of the thread trimming cam lever set 54, the bifurcated shaft 62, the thread trimming connecting rod 68, and the thread trimming holder 70 are respectively indicated by the arrow D.
Rotate in the direction and return to the original position. With this,
The movable blade 72 is separated from a fixed blade (not shown).

The voltage applied to the thread trimming solenoid 50 becomes zero in response to the thread trimming completion signal, and the compressed cam lever return spring 74 returns to its original length. By the action of the cam lever return spring 74, the thread cutting cam lever set 54 is pushed in the direction of arrow B, the roller shaft 56 of the thread cutting cam lever set 54 is disengaged from the thread cutting cam 58, and the thread cutting operation is completed.

[0010]

However, the thread cutting device having the above-mentioned structure has the following drawbacks.
That is, since the transmission system is composed of many parts, the moment of inertia of the thread trimming mechanism becomes large, and it is not rational in terms of kinematics.

Further, the thread cutting mechanism has two driving sources, that is, a thread cutting solenoid and a lower shaft, and the two driving sources are transmitted by a cam, a lever, a roller shaft, etc., which naturally complicates the structure. Become.

Furthermore, the fact that the sewing mechanism is different for each model of the sewing machine means that the thread cutting mechanism itself, which uses the lower shaft as a drive source, must perform the same operation, but must be changed for each model of the sewing machine. It was also disadvantageous.

The present invention has been made in order to solve the above-mentioned problems, and the yarn to be cut is cut by moving it on a blade, thereby greatly simplifying the structure of the yarn cutting device. It is an object of the present invention to provide an automatic thread trimming device that can realize cost reduction and cost reduction, and can rationalize the kinematics of thread trimming.

[0014]

In order to achieve the above object, an automatic thread trimming device of the present invention is based on a thread trimming command,
In an automatic thread cutting device adapted to automatically cut a yarn to be cut, a cutting means having a fixed blade for cutting the yarn to be cut, and a contact between the yarn to be cut and a blade of the cutting means. Thread gripping means for gripping the thread to be cut on both sides of the contact portion, and the thread gripping means is driven to bring the thread to be cut held by the thread gripping means into contact with the blade of the cutting means, and And a gripper driving unit that moves the yarn to be cut on the blade of the cutting unit to cut the yarn.

Further, it is preferable that the blade of the cutting means is arranged so as to intersect obliquely with the moving direction of the yarn to be cut by the gripper driving means.

Further, the thread gripping means may be constituted by a pair of thread gripping bars that grip the thread to be cut near both sides of the contact portion.

[0017]

According to the automatic thread trimming device of the present invention having the above-mentioned structure, the thread gripping means for gripping the thread to be cut is driven by the gripping portion driving means based on the thread trimming command, whereby the thread gripping means is driven. The yarn to be cut held by the blade is brought into contact with the blade of the cutting means, and is moved and cut on the blade.

Further, since the blade of the cutting means is arranged so as to cross the moving direction of the yarn to be cut, when the yarn to be cut is brought into contact with the blade, The yarn to be cut is easily and surely cut due to the sliding action on the blade.

Further, the thread gripping means is composed of a pair of thread gripping bars for gripping the thread to be cut in the vicinity of both sides of the abutting portion, so that an inexpensive wire is bent to form the thread. The gripping structure can be further simplified.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a top perspective view of the vicinity of the needle drop according to the present embodiment, and FIG. 2 shows a state of a rotation angle in which the upper thread is caught by the tip of the hook of the hook and is about to pass through the inner hook 36. Cloth etc. are omitted. 4 is needle plate 1
It is a needle hole opened in the. A thread cutting blade 5 is provided on the lower surface of the needle plate 1 in the vicinity of the needle hole 4 and on the side opposite to the operator. As shown in FIG. 1, the thread cutting blade 5 is fixed in a state of being inclined at an angle of about 45 ° with respect to the cloth feeding direction, and the thread to be cut is pressed against the blade 5a to cut the thread. The yarn to be cut is cut by sliding on the blade 5. That is, in the present embodiment, the thread cutting blade 5
Constitutes the cutting means.

A thread gripping bar 6 as thread gripping means is provided near the needle hole 4 below the needle plate 1, and each thread gripping bar 6 is bent into a similar shape by a wire rod. The upper thread gripping bar 6a and the lower thread gripping bar 6b are formed, and the upper thread gripping bar 6a and the lower thread gripping bar 6b are
It is supported by a shaft 7 so as to be integrally rotatable. The upper thread gripping bar 6a is provided near the upper side of the thread cutting blade 5 and
b is located near the lower side of the thread cutting blade 5 and has an interval of 1 mm.
It is equipped as follows. As a result, the thread gripping pin 6 is configured to grip the thread to be cut at both ends of the contact portion between the thread cutting blade 5 as the cutting means and the thread to be cut. The thread gripping bar 6 has a thread gripping section 6c, a thread handling section 6d for selecting a thread to be cut and a thread not to cut, and a selected thread not to be cut in order from the end opposite to the shaft 7. A thread escape portion 6e is provided to prevent the thread cutting blade 5 from contacting the blade 5a.

A rotary solenoid 8 is connected to the shaft 7, and the rotary solenoid 8 rotates to cause the shaft 7 and the thread gripping rod 6 to rotate together.
It is configured so as to perform an arc motion centering around. As a result, the rotation of the rotary solenoid 8 causes the shaft 7 to move.
The thread gripping bar 6 rotates about the
The lower thread gripping bar 6b grips the thread to be cut at a position near the upper and lower sides of the thread cutting blade 5, and further presses the gripped thread to the blade 5a of the thread cutting blade 5 to perform a sliding operation. That is, in this embodiment, the shaft 7 and the rotary solenoid 8 form a gripper drive means.

The upper thread 18 and the upper thread 20 in FIG. 1 are shown in cross section, and correspond to the state of FIG. The lower thread 22 is a thread supplied from the bobbin case and is shown in cross section in FIG. The upper thread has 18 on the needle 38 side,
The sewn side is 20. When cutting this upper thread,
Since it is necessary to cut the thread remaining length on the sewing cloth side as short as possible and cut it so that the thread remaining length on the needle 38 side becomes a predetermined length or more, normally, the upper thread 20 on the sewing cloth side and the lower thread The thread 22 is a thread to be cut, and the upper thread 18 on the needle 38 side is a thread that is not cut.

The thread separating portion 6d of the thread gripping bar 6 is formed in the shape of an acute angle protrusion, and as shown in FIG. 1, the upper thread 20 and the lower thread 22, which are the threads to be cut, are transferred to the thread gripping section 6c. The upper yarn 18 which is a yarn that is not cut is selected and guided to the yarn escape portion 6e.

FIG. 3 shows a control circuit for controlling the thread cutting device.

The thread trimming switch 30 is actually provided on a foot pedal or the like, and instructs the execution of the thread trimming operation by operating the foot pedal. Spindle phase detector 32
Is attached to the spindle and detects the phase signal of the spindle rotation. The detected phase signal is supplied to the control circuit 34. The control circuit 34 determines the timing of the voltage applied to the rotary solenoid 8 based on the thread trimming switch 30 and the spindle phase detector 32, and outputs it to the rotary solenoid 8.

The operation of the thread cutting device of the sewing machine based on the above construction will be described below.

Now, in order to instruct the execution of the thread cutting operation,
For example, the thread trimming switch 30 is turned on by operating a foot pedal or the like (not shown). After that, the control circuit 34 detects a rotation angle (FIG. 2) at which the upper thread is caught by the sword tip of the hook and is about to pass through the inner hook 36 by a signal from the spindle phase detector 32. At the time of the rotation angle, the control circuit 34 applies a drive voltage (for example, DC 100V) to the rotary solenoid 8. Based on the output signal from the control circuit 34, the rotary solenoid 8 starts a rotating operation and rotates the entire thread gripping bar 6 clockwise around the shaft 7.

The thread gripping bar 6 is a thread separating section 6d of both the upper thread gripping bar 6a and the lower thread gripping bar 6b. First, the upper thread 20 and the lower thread 22, which are the threads to be cut, and the thread that is not cut. Upper thread 1
8 is selected, and the upper thread 18 which is the thread that is not cut is guided to the thread escape portion 6e. At the same time, the upper thread 20 and the lower thread 22, which are the threads to be cut, are gripped at two locations by the thread gripping portions 6c of both the upper thread gripping bar 6a and the lower thread gripping bar 6b.

The rotary solenoid 8 continues to rotate further, and the upper thread 20 and the lower thread 2 gripped by the grip portion 6c.
2 and 2 are brought into contact with the blade 5a of the thread cutting blade 5. At this time, the blade 5a is configured so that the blade 5a is located approximately in the center between the thread gripping portion 6c of the upper thread gripping rod 6a and the thread gripping portion 6c of the lower thread gripping rod 6b. Gripping rod 6
Each of b also moves at a close position within a distance of 1 mm from the thread cutting blade 5. When the rotary solenoid 8 is further rotated from the position where the upper thread 20 and the lower thread 22 are in contact with the blade 5a, they are gripped by the thread gripping portion 6c of the thread gripping bar 6 at two positions above and below the contact position. The upper thread 20 and the lower thread 22 are pressed against the blade 5a and are slid along the blade 5a with appropriate tension. By this operation, the upper thread 20 and the lower thread 22, which are the threads to be cut, are easily and reliably cut.

The rotary solenoid 8 completes its rotation operation according to its own stroke, but at this time, the needle thread 18 is cut by the thread cutting blade 5 because it is released to the thread escape section 6e. There is no. Control circuit 3
4 makes the voltage applied to the rotary solenoid 8 zero,
Due to the action of the return spring arranged inside the rotary solenoid 8, the thread gripping bar 6 returns to the position before the operation, and the thread cutting operation is completed.

The configuration and operation of one embodiment of the present invention has been described above, but the present invention is not limited to this. For example, in the present embodiment, the thread cutting blade 5 is fixed at an angle of about 45 ° with respect to the cloth feeding direction as shown in FIG.
The yarn to be cut is pressed against a and slid against the yarn cutting blade 5 to cut the yarn to be cut. It may be 40 ° or even 90 ° in extreme cases. However, if the angle is too close to 90 °, the sliding distance cannot be secured, and conversely, if the angle is made smaller, the sliding distance becomes too long before cutting,
Since the thread remaining length on the side of the sewing cloth may become too long, it is desirable to set it to an intermediate angle excluding both extreme angles.

Further, in the present embodiment, the thread gripping rod 6 which constitutes the thread gripping means, and the shaft 7 which constitutes the gripping portion driving means.
Although the rotary solenoid 8 and the rotary solenoid 8 are arranged on the right side of the inner hook 36 as seen from the operator, they may be arranged on the left side of the inner hook 36 depending on the configuration of the entire sewing machine and the cloth feed arrangement. Due to the positional relationship with the upper thread 18, which is a thread that is not cut, it is not necessary to provide the thread releasing portion 6e on the thread gripping bar 6, and the present invention can be realized with a simpler configuration.

Although the upper and lower threads are selectively cut at the same time in the example of the above apparatus, a cutting apparatus for only the upper thread or only the lower thread may be used.

Further, the voltage applied to the rotary solenoid 8 does not have to be constant. When the voltage applied to the rotary solenoid 8 is changed during the thread cutting operation, the grasped thread vibrates and abuts the thread cutting blade 5, so that the thread cutting performance is improved depending on the type of thread.

Further, although the present embodiment describes the automatic thread cutting device of the sewing machine, it is needless to say that the present invention can be applied to other textile machines that handle threads, such as a thread winding machine and a knitting machine.

[0037]

As is apparent from the above description, according to the automatic thread trimming device of the present invention, the thread gripping means for gripping the thread to be cut is driven by the gripping portion driving means, whereby the thread gripping means is driven. Since the thread to be cut held by the blade is brought into contact with the blade of the cutting means and the thread to be cut is moved on the blade of the cutting means to cut, the structure of the thread cutting device is greatly simplified. In addition, it is possible to reduce the cost and to rationalize the kinematics of thread trimming.

[Brief description of drawings]

FIG. 1 is a top perspective view of a sewing machine incorporating an automatic thread trimming device according to an embodiment of the present invention in the vicinity of a needle drop.

[Fig. 2] In a sewing machine incorporating an automatic thread trimmer,
It is a perspective view showing a state when the upper thread is about to pass through the inner hook.

FIG. 3 is a block diagram showing a control circuit of the automatic thread cutting device.

FIG. 4 is a mechanism explanatory view showing a thread cutting device of a conventional sewing machine.

[Explanation of symbols]

 5 thread cutting blade 5a blade 6 thread gripping rod 6a upper thread gripping rod 6b lower thread gripping rod 6c thread gripping part 7 axis 8 rotary solenoid

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiki Katayama 15-1 Naeshiro-cho, Mizuho-ku, Nagoya City Brother Industries, Ltd.

Claims (3)

[Claims] 1. An automatic thread trimming device for automatically cutting a yarn to be cut based on a thread trimming command, a cutting means having a fixed blade for cutting the yarn to be cut, and the cutting device. The thread gripping means for gripping the thread to be cut is provided on both sides of the contact portion between the cutting thread and the blade of the cutting means, and the thread to be cut held by the thread gripping means is driven by the thread gripping means. An automatic thread cutting device, comprising: a gripping portion driving means that is brought into contact with a blade of the cutting means and moves the yarn to be cut on the blade of the cutting means to cut the yarn. 2. The automatic thread trimming device according to claim 1, wherein the blade of the cutting means is arranged so as to intersect the moving direction of the yarn to be cut by the gripper driving means at an angle. . 3. The automatic thread cutting device according to claim 1, wherein the thread gripping means comprises a pair of thread gripping bars that grip the thread to be cut near both sides of the abutting portion.