JPS5813200B2 - Chain stitch sewing machine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a sewing machine that is driven and stopped in relation to the operation of a pedal, and forms a chain stitch by the cooperation of a needle and an upper thread catcher (looper). This invention relates to a control device for a chain stitch sewing machine that operates a thread cutting means that captures the upper thread or upper and lower threads that are continuous between the looper and the fabric when the needle stops at the upper position, and moves them to the cutting position to cut them. be.

Traditionally, decorative stitches have been made using sewing machines that form single thread loop stitches, sewing machines that form double loop stitches, or by placing the thread between the double chain stitch lines formed by two parallel needles. In a so-called chain stitch sewing machine such as a forming sewing machine, when the above-mentioned thread cutting means is operated, the following drawbacks occur.

That is, when the needle is stopped at the upper position, the loop of the upper thread caught by the looper and the lower thread of the looper, such as the one provided in the double-ring sewing machine described in Japanese Patent Publication No. 45-15708, are connected to the fabric. The hook section of the movable blade captures and moves the side connected to the thread, and cuts the captured suture thread in cooperation with the fixed knife waiting at the cutting position. In order for the section to capture only the sewing thread connected to the looper and the cloth, the sewing thread must have an appropriate tension.

That is, the needle thread loop is captured by the looper, and tension is applied to separate the needle thread that connects to the needle and the looper and the upper and lower threads that connect to the looper and the fabric so that they do not approach each other, and the upper and lower threads that connect to the looper and the fabric are separated. However, when the needle falls onto the fabric to form a stitch, the needle must be positioned on the path of movement of the hook part of the movable blade, but when the needle falls onto the fabric and forms a stitch, the needle must be placed on the stitch knot by the length of the needle that has been let out. Later, they are transported together with the fabric and pulled up by a thread take-up, so that the upper and lower threads captured by the looper at the time of tying the next stitch are given appropriate tension, and the upper and lower threads connected to the fabric and the upper thread connected to the needle are However, when the trailing edge of the fabric moves forward in the fabric feeding direction from the needle drop position and continues to knot the seam from the trailing edge of the fabric to the outside of the fabric, forming a so-called empty ring, only the sewing thread is attached to the presser foot. Since the feed dog moves while being held by the feed dog, the holding force is irregular and insufficient, and therefore the feed amount becomes shorter than the length of the upper and lower threads that have been let out, making it impossible to pull up the upper and lower threads that have been let out. However, the upper thread loop and bobbin thread, which are caught by the looper at the time of subsequent knot knotting, cannot obtain appropriate tension because of the insufficient length.

For this reason, the upper thread running from the needle to the looper may enter the moving path of the hook part of the movable blade and be caught and cut by the hook along with the upper and lower threads running to the fabric, or the upper and lower threads running from the looper to the fabric may fall outside the moving path of the hook. In the former case, the cut end of the needle thread protruding from the thread hole of the needle becomes shorter, so that when the needle descends at the start of the next sewing, the needle thread falls into the thread hole of the needle. This can cause the thread to fall off and leave undesirable needle drop marks on the fabric without tying the seam, or it is a tedious task to stop the sewing machine and rethread the thread through the needle hole.
In the latter case, the worker has to manually cut the upper and lower threads connected to the fabric, which is a tedious task, and this may result in uneven lengths of the cut ends of the sewing threads that protrude from the fabric, or when forming the next stitch. The starting end of the sewing thread protruding from the cloth becomes long, resulting in a disadvantage that work efficiency and product quality are significantly reduced.

For this reason, the operator must stop the sewing machine before the trailing edge of the fabric passes the needle drop position and after forming the stitch all the way to the trailing edge, which requires a high level of skill.
An unskilled person may have to slow down the sewing machine speed and pay attention to the pedal operation, resulting in a significant drop in work efficiency, or may cause the thread trimmer to operate before sewing to the rear edge of the fabric, resulting in the stitch length being shortened. However, the quality of the products was not constant, resulting in uneven products and a deterioration in quality.

The purpose of this invention is to eliminate the above-mentioned drawbacks of the conventional ones.

An embodiment of the present invention will be explained using a single-needle double chainstitch sewing machine.A needle 2 and a presser foot 3 are arranged in the sewing machine head 1, and an upper and lower looper 7 is provided below the throat plate 6 of the sewing machine bed 5.
.

In the thread cutting means, a movable blade 9 swings around a shaft 10 when an electromagnet Mg (described later) acts, and during the return movement, a needle thread loop (not shown) captured by the looper 8 and a looper thread (not shown) of the looper 8 are removed. ) and hook part 9 on the side that connects to the cloth.
It is caught at point a and cut by cooperation with the waiting fixed blade 11.

In front of the sewing machine sewing part described above in the cloth feeding direction, a light emitting body 1 is disposed vertically across the cloth path so as to detect the cloth edge.
2 and a photoreceptor 13 are arranged.

Next, the electric circuit will be explained.

The light receiving body 13 of the cloth detection means generates an H level output signal (hereinafter referred to as H output) when it receives the light from the light emitting body 12, that is, when there is no cloth intervening, and when it does not receive the light, that is, when there is cloth intervening. Sometimes, an L level output signal (hereinafter referred to as L output) is generated.

The sewing machine main shaft 14 is provided with needle position detection means 15a and 15b which separately detect the rotation angle of the main shaft corresponding to the vertical position of the needle 2 and generate H output position signals, respectively.

A front pedal switch 17 and a rear pedal switch 18 are provided at the front and rear operating positions of the pedal 16, which generate an L output operating signal when each pedal is operated.

G is a NAND gate, I is an inverter, F is a flip-flop, and O and S are one-shot multis.

Input A1 becomes an L output from when the power is turned on until the first operation signal of the front foot switch 17 is generated, input A2 becomes an L output when the main shaft 14 of the sewing machine is stopped, and input A3 becomes an L output when the movable blade 9 of the thread cutting means is turned on. L when returning and thread trimming is completed
Output occurs.

D is a delay circuit, and the H signal from the photoreceptor 13 is
E1 to E3 are integrator circuits, which generate an instantaneous L output by capturing the input rising signal.

S and C are drive control circuits using a microcomputer that control the sewing machine motor M and the thread trimming electromagnet Mg, and the motor M is always driven at a speed corresponding to the amount of front depression of the pedal 16, and the motor is activated by the pedal release operation. M
is driven at low speed and stopped at the needle down position in response to the generation of the down position signal, and the motor M is driven at low speed by a subsequent operation of the pedal and stopped at the needle up position in response to the generation of the up position signal. At the same time, the thread cutting electromagnet Mg is activated.

That is, while the input B3 is at the L level, the driving speed of the motor M is set to a predetermined medium speed, for example, a speed corresponding to the amount of front depression of the pedal 16 within a range with an upper limit of 2000 r.p.m. While B4 is at the L level, a predetermined low speed, such as 200r. p. Set the speed to correspond to the amount of front depression of the pedal within a range with m as the upper limit, and when the input B5 becomes L level, set the speed to the speed corresponding to the amount of front depression of the pedal within the high speed range,
When input B5 goes from L to +H level, the needle stops at the down position in relation to the input of the down position signal to input B2 after decelerating to a predetermined low speed, and when input B6 goes to L level, the speed decreases to a predetermined low speed. When the next upper position signal is input to input B1, the needle moves to the upper position. As soon as it stops, the electromagnet M
energize g.

CT1 is a stitch number counting circuit, which operates when the photoreceptor 13 becomes an H output, counts the lower position signal (i.e., the number of stitches), and generates an H output at the output C1 when counting the stitch number C1;
When counting the number of stitches C2 which is greater than the number of stitches C1, the output C
2, the counted number of stitches C1+C2 is the number of stitches required for the trailing edge of the cloth to move from the detection position of the cloth detection means to the needle drop position, and the number of stitches C1 is the number of stitches when the motor M is running at medium to low speed. This is the number of stitches that can be decelerated.

CT2 is a cloth edge counting circuit, which counts the number of times the photoreceptor 13 detects the rear edge of the cloth, and outputs C when counting a predetermined number.
3, generates an L signal.

Note that the count values generated by the outputs of the count circuits CT1 and CT2 can be adjusted from the outside.

S1 to S3 are manual switches, and switch S1 selects whether to enable or disable resetting flip F1 by the Q output of one-shot multi O, S, and switch S2 selects whether to enable or disable thread trimming based on material edge detection. , S3 enable or disable the cloth edge count circuit CT2.

This invention has the above configuration, and when the power is turned on, an L signal is generated at the input A1, and the gates G1G2, G3, G
4, G5 is set to H output, flip-flops F1, F2,
F3 is reset by inputting the L signal to the reset terminal R via inverters I1 and I2I3, and F1 inputs the Q terminal to H.
Outputs F2 and F3 have the Q terminal as L output and the Q terminal as H output, and F4 is set by the instantaneous L output of E2 caused by the Q output of F3, and the count circuits CT1 and CT2.
inputs an H signal to the reset terminal R to enter the reset state.

Now, the switch S2 is closed, the switches S1 and S3 are opened to disable the cloth edge counting circuit CT2, and the outputs C1 and C2 of the stitch number counting circuit CT1 are respectively set to predetermined values, that is, from the detection position of the cloth detection means to the needle The number of stitches C1+C2 allows the rear end of the cloth to move to the falling position, and the number C1 allows deceleration from medium speed to low speed. For example, C1 is set to 2 stitches and C2 is set to 5 stitches.

When the pedal 16 is pressed forward, an operation signal is generated from the front foot switch 17, the input A1 becomes the H output, and the gate G12 becomes the L output via the inverter 17, and the motor M is set at a speed corresponding to the amount of the front foot pedal. The gate G12 is driven to form a seam in the cloth, and the gate G12 is set to H by releasing the pedal 16.
After it becomes an output and decelerates to a low speed, it stops at the needle down position in response to the generation of the down position signal.

If the pedal 16 is operated forward again, the sewing machine will be driven 1 in the same way, and if the pedal is operated backward from the pedal release position, an operation signal will be generated from the rear pedal switch 18, and the inverter I7,
The gate G11 is set to H output via I8, the B6 input of the control circuit SC is set to L level via I5, the motor M is driven at low speed to raise the needle, and the needle is stopped at the upper position in relation to the generation of the upper position signal. At the same time, the electromagnet Mg is activated to operate the thread cutting means.

In a high-speed driving state in which the pedal 16 is pressed forward, when the trailing edge of the cloth passes through the cloth detection means, the photoreceptor 13 enters the light receiving state and generates an H output, and the gate G6 outputs an L output due to the H output of inputs A1 and A2. The gate G7 has the Q terminal of the flip-flop F1, G6 via the inverter I4,
The H output of each photoreceptor 13 is inputted to become the L output, and flip-flops F1 and F2 are set.

The transistor Tr1 becomes conductive due to the H output of the Q terminal of F2, and the B3 input of the control circuit SC becomes L level, the motor M is decelerated to within the medium speed range, and the L output of the Q terminal of F2 causes the gate G8 to output an H output. Then, the gate G9 is brought into a state where it can output an L signal by the lower position signal, and the stitch number counter circuit CT1 counts the L output of G9.

When the circuit CT1 counts 5 stitches, an L output is generated from the output C2 and the gate G2 is set to the H output, which resets the flip-flop F2 via I2 and the Q terminal's H output.
The output causes the integration circuit E1 to generate an instantaneous L, and the gate G3
becomes H instantaneously, resetting the circuit CT1 and setting the flip-flop F3, and the L output of its Q terminal maintains the H output of the gate G8, and the circuit C continues.
With T1 in a counting state, the transistor Tr2 becomes conductive due to the H output from the Q terminal, the B4 input of the control circuit SC becomes L level, and the motor M is decelerated to a low speed range.

The counter circuit CT1 newly counts the lower position signal, and when counting 2 stitches, that is, when the needle 2 drops to the rear edge of the cloth, an H output is generated at the output C1, the gate G10 becomes an L output, and the gate G4 is set to H output, flip-flop F3 is reset via I3, transistor Tr2 becomes non-conductive due to L output from Q terminal, gate G8 becomes L output due to H output from Q terminal, and gate G9 is set to H output. is held, and the counter circuit CT1 stops counting, and
Integrating circuit E2 generates an instantaneous L output to set flip-flop F4.

The L output of the Q terminal sets the gate G11 to the H output, sets the B6 input of the control circuit SC to the L level via I5, drives the motor M at low speed to raise the needle, and stops when the upper position signal is generated. The electromagnet Mg is also activated.

When the pedal 16 is released while the circuit CT1 is counting, the gate G12 becomes an H output and the sewing machine stops at the needle down position.When the pedal 16 is later depressed, G11 becomes an H output and thread trimming is started immediately. will be accomplished.

When thread trimming is completed, an L signal is generated at input A3, and gates G1 to G4 are set to H output to flip-flops F1 to F3.
And the counter circuit CT1 is reset.

Next, the switches S1 and S3 are closed, the switch S2 is opened, and the cloth edge count circuit CT2 is set to 4.

After the start of sewing, the same operation as described above is performed until the first trailing edge of the cloth is detected and an H output is generated from the C1 output of the stitch number counter circuit CT1 to set the flip-flop F4, but the switch S2 is open. Therefore, gate G11 is H
There is no output and the electromagnet Mg does not act.

The one-shot OS generates an L output for a set time due to the L output of the Q terminal of the flip-flop F4, sets the gate G1 to the H level, resets F1, and also resets the gate G3.
The circuit CT1 is reset by setting the gate G12 to H output.
is set to the H output, and the control circuit SC stops at the needle down position in response to the generation of the down position signal, regardless of whether the pedal 16 is pressed forward.

In addition, the instantaneous L output of the differentiating circuit E2 is transferred to the cloth edge counter circuit CT.
2 counts.

The same operation as above is repeated until the cloth detecting means detects the cloth trailing edge three times, that is, until the cloth edge counting circuit CT2 counts 3, and when the cloth trailing edge is detected four times, that is, the counting circuit CT2 counts 3. When counting 4, an L output is generated from the output C3, the gate G11 becomes an H output, and the B6 input of the control circuit SC is set to the L level via I5, and the needle rises to the upper position and stops as described above. At the same time, the electromagnet Mg is activated to operate the thread cutting means.

Therefore, when forming stitches on the four edges of a quadrilateral cloth such as a handkerchief, for example, when the stitches on three sides have been formed, the thread is stopped at the rear end of the cloth at the lower position without cutting, and the needle is stopped at the lower position on the last side. When the stitch formation is completed, the thread can be cut by stopping at the needle-up position.

In this embodiment, when the trailing edge of the fabric reaches the needle drop position, the sewing machine is stopped and the thread is trimmed.
The thread cutting operation may be performed by stopping at a position close to the trailing edge of the cloth within a range where the thread cutting action can be performed reliably.

In addition, in this embodiment, a counting circuit is provided to count the number of stitches after the trailing edge of the fabric is detected, and the sewing machine is stopped when the number of stitches reaches a predetermined number, and the thread is trimmed. A timer circuit may be provided to set the time required for the needle to move to the suture portion, and control may be performed based on time.

Furthermore, although the present embodiment has been described using a single-needle double chain sewing machine, the present invention may be implemented in other chain stitch sewing machines such as a single-thread chainstitch sewing machine and a multi-needle decorative stitch sewing machine.

As described above, according to the present invention, in connection with the detection means detecting that the trailing edge of the cloth passes through a predetermined position spaced apart in front of the sewing machine seam portion in the cloth feeding direction, the trailing edge of the cloth is moved to the detection position. The setting circuit CT1, which sets the number of stitches (number of stitches) or time required to move from By activating the fixed position stopping means to stop the sewing machine at the needle up position and at the same time activating the thread trimming means, the needle stops at the up position when the fabric is located at the needle drop position. Since the thread trimming means can operate while always applying a moderate tension to the upper and lower threads caught by the looper, the thread trimming means can capture only the upper and lower threads connected to the looper and the fabric. It is possible to cut the sewing machine reliably at all times without bothering the operator's hands, and the operator does not have to pay attention to pedal operation to stop the sewing machine before the trailing edge of the fabric passes through the needle entry position. This eliminates the need for the troublesome work of rethreading the thread through the fabric, resulting in a significant improvement in work efficiency.Also, the length of the thread protruding from the front and back edges of the fabric is always constant, and the length of the thread is always reliably extended to the back edge of the fabric. Since seams can be formed, the quality of products can be significantly improved.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional front view of the decorative stitch sewing machine of this embodiment.
2 is a perspective view, FIG. 3 is a perspective view of the thread cutting means, FIG. 4 is an electric circuit diagram, and FIG. 5 is a simple block diagram of the drive control circuit SC. In the figure, 15 is a needle position detection means, 12 and 13 are cloth detection means, 16 is a pedal, 9 and 11 are thread cutting means, Mg is an operating means, CT1 is a setting circuit, and F3, F4, and G11 are control circuits. be.

Claims (1)

[Claims] 1 Needle position detection means 15 that detects a predetermined rotation angle of the main shaft of the sewing machine corresponding to the upper position of the needle and generates an upper position signal; fixed position stopping means that is inoperative so as to stop at a fixed position, and cloth detection means 12 and 13 that detects passage of the trailing edge of the cloth and generates a detection signal at a position spaced apart in front of the sewing machine sewing section in the cloth feeding direction. , a pedal 16 associated with the sewing machine driving device so that a one-way operation drives the sewing machine at a speed corresponding to the amount of operation and a return operation stops the sewing machine, and a pedal 16 disposed below the throat plate that moves the sewing machine from a standby position to an operating position. Thread cutting means 9 and 11 move to capture and cut the sewing thread connected to the needle thread catcher and the cloth, and thread cutting means actuated by an actuation signal to move the thread cutting means from the standby position to the working position. and a setting circuit CT which acts in conjunction with the generation of the detection signal and generates an actuation signal when the seam is formed to the trailing edge of the cloth or to a point near it.
1, and control circuits F3, F4, and G11 that actuate a fixed position stop means regardless of one-way operation of the pedal in connection with the generation of an operation signal, and generate an operation signal. .