JPH10249087A - Automatic sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely cut a cloth side needle thread and a bobbin thread no matter which direction a needle operating direction before cutting the thread is in by driving an X-Y driving device so as to draw a cutting object thread to the moving track side of a moving knife blade part to the pinhole center of a throat plate at the time of cutting the thread by a moving knife. SOLUTION: A timer to be simultaneously operated when a CPU detects the lower position signals of an upper shaft angle 135 deg. and turns ON thread cutting cam signals is provided, and after the timer times prescribed time, a cloth presser (upper presser and lower presser) for holding an object to be sewn is X-Y relatively driven. To put it concretely, the cutting object thread W at a part where an X axis indicated by the right arrow of the figure and a Y axis indicated by an upper arrow are crossed is drawn to the side of the moving track A of the moving knife blade part 9c to the center of the pinhole O, to a forth quadrant side in a coordinate whose origin is the center of the pinhole O preferably. Thus, since the cutting object thread W is moved to the side of the moving track A of the moving knife blade part 9c and the side of a fixed knife 10, the thread is surely cut and a thread remaining amount at the back of the cloth is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to an apparatus for cutting a cloth side upper thread and a lower thread in an automatic sewing machine for relatively moving a sewing machine head and a cloth presser for holding an object to be sewn, based on sewing pattern data stored as Y coordinate values. .

[0002]

2. Description of the Related Art In a conventional automatic sewing machine provided with a half-turn shuttle having a needle drop position between a lower thread lead-out point of a bobbin and an outer hook knife point, cutting of a cloth side upper thread and a lower thread by a thread cutting device in a conventional automatic sewing machine is performed by This is performed as shown in FIG.

The moving knife 9 moves forward from the standby state shown in (1) as shown in (2), and loosens (the forward movement of the moving knife 9 to cut the lower thread and the upper thread on the cloth side before cutting the thread). The operation of guiding the moving knife 9 to the thread reeling portion 9b) is started. The upper thread is sufficiently drawn into the shuttle, so that the leading end 9a of the separating portion of the moving knife can reliably enter. Then, as shown by the black arrow in (3), the lower thread is loosened. Next, as shown in (4), the cloth-side upper thread is separated. As shown in (5), the moving knife retreats last, and the loosened cloth-side upper thread passes over the outer periphery of the loosening portion of the moving knife and enters the thread reeling portion 9b. Thereafter, as shown in (6), the moving knife 9 starts to move backward, and the thread is threaded on the thread reeling portion 9b in the order of the cloth side upper thread and the lower thread, and as shown in (7), the upper thread is It is pulled up by a balance and held so as to be wound around a moving knife. Then, the bobbin thread is pulled out by the moving knife, and the required amount is fed out. At this time, the reciprocating speed of the moving knife 9 is controlled so that the bobbin does not spin out (excessive rotation) because the bobbin thread is pulled out too fast, and does not adversely affect the next sewing start. The upper thread held by the moving knife 9 is the remaining thread on the needle side after thread cutting. Finally,
As shown in (8), the upper and lower threads on the cloth side are cut.

[0004]

The cutting of the upper thread and the lower thread in the conventional automatic sewing machine is performed as described above.
As shown in the figure, the moving knife 9 is set so that the movement locus A of the blade portion 9c is on the right side of the center of the needle hole O in the needle plate due to the moving knife thread handling. There is a problem. That is, when the needle moving direction before the thread cutting is performed from left to right, the direction in which the thread W to be cut deviates from the movement locus A of the moving knife blade 9c by the cloth feed (left side in the figure).
, The thread W to be cut tends to deviate from the center of the spherical blade portion 9c of the moving knife 9, and a cutting failure, particularly a cutting failure of the upper thread, may occur.

[0005] Originally, if both sides of the moving knife spherical blade portion 9c exactly match the fixed knife 10, cutting failure does not occur. However, since the moving knife blade is spherical, it is difficult to align both sides of the moving knife spherical blade 9c with the fixed knife 10 due to variations in the inclination of the fixed knife 10 and the eccentricity between the moving knife spherical surface and the blade. It is.

It is an object of the present invention to provide an automatic sewing machine that can reliably cut a cloth-side upper thread and a lower thread regardless of the direction of needle movement before thread cutting.

[0007]

A thread cutting device in an automatic sewing machine according to the present invention is arranged such that, when a thread is cut by a moving knife 9, the moving locus A of the moving knife blade 9c with respect to the center of the needle hole O of the needle plate.
The XY drive device drives the yarn W to be cut so as to be brought closer by the idle feed after the final needle movement before the yarn cutting for forming the sewing.

Preferably, X is set so that the thread Y to be cut is moved to the fourth quadrant at coordinates with the center of the needle hole O of the needle plate as the origin.
-Driven by a Y drive device.

In the above arrangement, the home position is returned after the driving of the XY driving device at the time of thread cutting.

When the XY driving device is driven at the time of thread cutting, and then the origin is returned, the origin may be returned based on data stored in advance.

In the case of driving the XY driving device at the time of thread cutting, and thereafter returning to the origin, the origin return may be calculated based on the final hand movement data and the needle position data after the thread cutting, respectively.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic sewing machine according to the present invention will be described with reference to FIGS.

As shown in FIG. 1, the automatic sewing machine according to the present invention is a sewing machine for holding a work to be sewn comprising an upper presser 1 and a lower presser 2 based on sewing pattern data stored as XY coordinate values in a storage device. The presser foot and the sewing machine head 3 are relatively moved. In the present invention, it is important to slightly drive the XY drive device separately from the sewing pattern during the final rotation of the upper shaft of the sewing machine after the completion of the moving knife thread separation. The XY drive device in the illustrated automatic sewing machine includes an X-axis pulse motor 6 and a Y-axis pulse motor 7 mounted inside the bed 5, and these work motors 4 The upper presser foot 1 and the lower presser foot 2 located above the needle bar 8
Is driven XY.

This automatic sewing machine has a half-rotary hook having a needle drop position between the lower thread take-out point of the bobbin and the middle hook hook point (hereinafter, referred to as a DB-specified half-rotary hook in a broad sense). As shown in FIG. 2, in the thread cutting device, a support shaft (not shown) is located on the right front side of the needle hole O in the needle plate as viewed from the operator (on the near side in the drawing), and the thread pulling portion 9b is set in a standby state toward the user. And a fixed knife 10 that cooperates with the moving knife 9 to cut the cloth side upper thread and lower thread. Controlled by hole 12.

The moving knife 9 has a thread separating portion tip 9a, a thread reeling portion 9b, and a thread cutting blade 9c (a blade portion is formed at a front edge of a hole called an eyeball), and has several links. 1
The rotation of the upper shaft of the sewing machine is transmitted through 3 to enable clockwise rotation (forward movement) and counterclockwise rotation (backward movement). In the forward movement, the lower thread is loosened first. Then, the cloth side upper thread is loosened. Also, at the time of the backward movement, the cloth side upper thread and lower thread are threaded and cut.

The fixed knife 10 is located above the moving knife 9 and the thread cutting blade at the tip is located slightly before the needle drop position.

The shuttle upper spring 11 is fixed on the upper side of the shuttle 14 of the DB type semi-rotary shuttle, and has a thread control hole 12 of a special shape formed at the center of the needle dropping position. . In FIG. 2, reference numeral 15 denotes a hook shaft for rotating the half-turn hook, 16 denotes a bobbin case, and 16a denotes a corner of the bobbin case.

FIG. 3 shows a curve indicating the movement of the needle point, which has a locus of a sine curve, and a top dead center when the upper axis angle is 0 °. Also, indicates the position of the needle plate,
Is an XY feed operation section. By the way, a sensor (not shown) for transmitting an upper position signal indicating an upper shaft angle of 50 ° and a sensor (not shown) for transmitting a lower position signal indicating an upper shaft angle of 135 ° are attached to the upper shaft of the sewing machine. The driving of the -Y feed is controlled by a central processing unit (CPU) based on signals from these sensors so that the driving is performed when the needle is raised above the needle plate.

Is a thread cutting cam signal which is turned on at a position below the upper axis angle of 135 °. When the thread cutting cam signal is turned on, the moving knife 9 starts operating, and the upper shaft angle becomes approximately 300
When the angle is °, the moving knife is released, and a series of operations is terminated at the upper axis angle of 50 角度. By the way, at the time of thread cutting, the speed of the upper shaft of the sewing machine is reduced a few stitches before stopping, and when the thread cutting cam signal is turned on, the rotation speed of the sewing machine is about 2
00 rpm. Therefore, 165 ° from the turning on of the thread cutting cam signal at the upper shaft angle of 135 ° after the final cloth feed to the upper shaft angle of 300 ° at the end of moving knife separation is about 140 milliseconds (ms) in time.

Therefore, when the CPU detects the lower position signal of the upper shaft angle of 135 ° and turns on the thread cutting cam signal, there is provided a timer which operates simultaneously, and after the timer measures a predetermined time (about 140 ms), The cloth presser for holding the workpiece (the upper presser 1 and the lower presser 2) is driven relative to XY.
This driving is performed based on data stored in the ROM in advance. Specifically, the thread W to be cut is inserted into the needle hole at a position where the X axis indicated by the right arrow in FIG. O
To the movement locus A of the moving knife blade 9c, preferably to the fourth quadrant side of the coordinates with the center of the needle hole O as the origin. The relative driving of the upper presser 1 and the lower presser 2 at this time is referred to as idle feed. This idle feeding is performed uniformly regardless of the position of the last needle. In this case, the thread W to be cut moves to the fixed knife 10 side and the moving locus A side of the moving knife blade 9c, so that the thread is cut reliably.
The amount of thread remaining on the back of the cloth becomes shorter. Thereafter, the sewing machine upper shaft is stopped by the upper position signal, the thread cutting cam signal is turned off, and the process proceeds to the next cycle. Then, thereafter, as shown in FIG. 6, it is possible to return to the origin () from the needle position B after the thread cutting. In this case, the origin return is also performed based on the data stored in the ROM in advance.

As described above, when the lower position signal is detected, the thread cutting cam signal is turned on, and the timer is operated.
Although the Y drive is performed, a new sensor for detecting the angle at which the moving knife is released may be provided, and the XY drive for tensioning the yarn to be cut may be performed based on the signal. In the XY driving, an upper position signal may be used instead of the lower position signal, or a sensor for detecting the angle of the upper shaft of the sewing machine may be used.

In the idle feed, the [feed direction] and [feed amount] of the upper presser 1 and the lower presser 2 can be determined by the CPU based on the needle movement data of the last needle or the relative drive data of the cloth presser. That is, a, b with arrows in FIG.
FIG. 5A shows the relationship between the relative drive vector of the final needle presser foot, the vector of the best thread cutting point, and the idle feed vector, and the radius R of the needle hole O.
When the final needle pitch is equal to or smaller than the radius R of the needle hole O, as shown in (1), the calculation is performed as [empty feed vector] = [vector of the best thread cutting point] − [relative drive vector of the final needle presser foot]. You. Further, as shown in FIG. 5 (2), when the final needle pitch is equal to or larger than the radius R of the needle hole O, [empty feed vector] = [vector of the best thread cutting point]-(radius of needle hole /
[The magnitude of the relative drive vector of the presser foot of the last needle]) ×
It is calculated as [the relative drive vector of the presser foot of the last needle]. Also in the case of such a calculation, the thread is reliably cut, and the remaining thread amount on the back of the cloth is shortened. Thereafter, as shown in FIG. 6, the upper presser 1 and the lower presser 2 can be returned to the origin () from the needle position B after thread cutting. In this case, the home position return is also calculated from the data of the needle position B after the thread cutting.

Alternatively, as the idle feed data, angles 0 °, 30 °, 6 in the final relative drive vector of the work clamp
The idle feed vectors corresponding to 0 °, ─, 330 ° and each absolute value (magnitude) can be stored in the ROM of the CPU. That is, the idle feed vector is determined by the combination of the direction and the size of the final relative drive vector of the work clamp.

Although slightly rough, the upper presser 1 and the lower presser 2 are forcibly moved by the distance corresponding to the diameter of the needle hole O in the X direction on the movement locus A side of the moving knife blade 9c as the idle feed. You may do so.

In the above-described embodiment, the home return operation is performed after the XY driving device is driven at the time of thread cutting. However, the thread to be cut is moved with the moving knife blade relative to the center of the needle hole at the time of thread cutting. When the driving direction of the XY driving device for moving in the direction toward the trajectory side is the origin returning operation direction, the driving of the XY driving device for moving the yarn to be cut is the origin returning operation. XY driving device for driving.

Instead of obtaining the driving force in the XY directions by combining two linear motions, the driving force may be obtained by combining two arc motions as shown in FIG. Specifically, the first swing arm 51 is swung about the shaft 52 by the first drive source 50, and the second swing arm 54 is swung about the shaft 55 by the second drive source 53. , These swing arms 51, 5
The cloth presser 56 is driven in the X-Y direction by the combined force of No. 4.

[0027]

Since the present invention is configured as described above, it has the following effects.

That is, no matter what direction the needle is moved before the thread is cut, the thread to be cut is moved to the moving locus side of the moving knife blade when the moving knife cuts the thread. The yarn can be reliably cut, and the remaining amount of the yarn on the back of the cloth can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of an automatic sewing machine.

FIG. 2 is a perspective view of a thread cutting device in the automatic sewing machine according to the present invention.

FIG. 3 is a diagram illustrating a relationship between a movement of a needle point and each signal in the automatic sewing machine according to the present invention.

FIG. 4 is a plan view for explaining a thread shifting operation at the time of thread cutting of the automatic sewing machine of the present invention.

FIG. 5 is a plan view for explaining empty feed data at the time of thread cutting of the automatic sewing machine according to the present invention, wherein (1) shows a case where the final needle movement amount is equal to or less than a needle hole guide radius, and (2) shows a final needle. This is the case where the needle movement amount is equal to or larger than the needle hole guide radius.

FIG. 6 is a plan view for explaining data of return to origin after thread cutting.

FIG. 7 is a plan view showing a relationship between a thread to be cut and a movement locus of a moving knife blade when a conventional automatic sewing machine cuts a thread.

FIG. 8 is a perspective view illustrating a yarn cutting operation in a conventional yarn cutting device.

FIG. 9 is a plan view of an XY driving device that obtains a driving force in the XY directions by combining two arc motions.

[Explanation of symbols]

 1 Upper presser 2 Lower presser 3 Sewing machine head 6 X-axis pulse motor 7 Y-axis pulse motor 9 Moving knife 9c Moving knife blade 11 Hook upper spring 12 Hook upper spring hole A Moving locus of moving knife blade B After thread cutting Needle position O Needle hole in needle plate

Claims (6)

[Claims] An automatic sewing machine driven by an XY drive device to move a thread to be cut to a moving locus side of a moving knife blade portion with respect to a center of a needle hole of a needle plate when a thread is cut by a moving knife. 2. The automatic sewing machine according to claim 1, wherein the sewing machine returns to the home position after driving the XY drive device at the time of thread cutting. 3. The automatic sewing machine according to claim 1, wherein driving of the XY driving device at the time of thread cutting is performed based on data stored in advance. 4. The automatic sewing machine according to claim 1, wherein driving of the XY driving device at the time of thread cutting is performed by calculating from last hand movement data before thread cutting. 5. The automatic sewing machine according to claim 2, wherein driving of the XY driving device at the time of thread cutting and subsequent return to the origin are performed based on data stored in advance. 6. The automatic sewing machine according to claim 2, wherein the driving of the XY driving device at the time of thread cutting and the return to origin thereafter are performed by calculating from the last hand movement data and the needle position data after thread cutting, respectively.