JPS6019276B2 - Sewing machine stitch tension control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stitching tension control device for a sewing machine that allows good stitching tension to be obtained during sewing work.

In a sewing machine, the sewing tension is adjusted by adjusting the thread tension, but it requires skill to adjust to a good sewing condition. Obtaining stitches is a difficult task.

The present invention improves this drawback, and after temporarily performing a test warp to detect the upper thread length of the first stitch required for good stitching, the needle thread length required for good stitching is determined in the subsequent full-scale sewing operation. The needle thread is always paid out in the same amount as required, so that a good light can be obtained at all times.

That is, before performing the sewing work, a test stitch is temporarily performed, and the length of the needle thread required for one stitch is detected by combining the fabric to be sewn under the conditions of underhang sewing, and the length and the length of the needle thread required for one stitch are detected. Calculate the needle thread length required for one stitch in the case of hanging stitching, which corresponds to the sum of 0 and the pitch length of one stitch, and calculate the length equivalent to 1/2 of the sum of the pitch length of one stitch. Calculate needle thread length only 1
This is to ensure that the needle thread is consumed for each stitch so that good stitching can be performed.

To explain according to the drawings, Fig. 1 is an explanatory diagram showing the relationship between the upper thread and bobbin thread when sewing fabrics with a thickness of d. It shows the condition.

In the diagram A showing the lower suspension sewing state, the needle thread length required for one stitch is P+4d, where P is the stitch pitch, and in the opening diagram showing the upper suspension sewing state, the needle thread length required for one stitch is P + 4d. The needle thread length required for one stitch is P, and in Figure C showing a good sewing condition, the needle thread length required for one stitch is P10. If you try,
Since sewing work is normally performed with a constant stitch pitch, if it is possible to detect the needle thread length P14d required for one stitch in the hanging sewing state, it is possible to detect the needle thread length P14d required for one stitch for a good stitch. The yarn length P+phantom can be determined by simple subtraction such as (P+4d+P)/2. Incidentally, since the pitch P is known from the adjustment of the stitch pitch adjusting device of the sewing machine, it is clear that if P+necessary is detected, P+illustration can be easily calculated. Note that this calculation is performed by a built-in calculation circuit. In the present invention, in order to obtain a fully suspended state in the temporary mochi-ketsu stitch, the time when the upper thread and the bobbin thread cross each other on the lower surface of the sewing fabric (interlaced time of the downwardly suspended stitch state) is determined by the upper thread. The tension change is detected by a strain gauge, and by releasing the upper thread gripping by the upper thread gripper at that time, the upper thread tension is set as the base tension to obtain a suspended sewing state.

FIG. 2 is a diagram showing the sewing machine neck 1 according to the present invention, which is used as an upper thread output amount detector for measuring the upper thread payout base by winding the upper thread around the pulley and rotating the pulley as the upper thread is fed. An encoder 2 with a pulley 2 An upper thread gripper 3 is provided which holds the thread with two disks under electromagnetic control. ,
The needle thread is guided through an upper thread gripper 3, an upper thread tension variable material strain gauge 7, and a thread take-up lever 8 to a needle 9, which stitches the cloth 10 on the table.

It is clear that if the tension applied to the upper thread is reduced when the upper thread and bobbin thread intertwine on the bottom surface of the sewing material, the lower thread will not be pulled up into the sewing material and will remain at that level, resulting in a hanging stitch. , the upper thread tension increases due to the interlacing of the upper thread and lower thread.
Diagram (oscillograph diagram showing changes in needle thread tension)
If the upper thread gripper 3 is opened at the time t when the upper thread starts to change as shown in FIG. The needle thread length P + illusion required for the first stitch at that time is determined using the encoder 2 with a pulley.
By detecting this and dividing the sum of this and one stitch length P by 1/2, the needle thread length P+phantom required for good stitching can be obtained. In this way, the needle thread 1 stitch length P required for good sewing
Since ten visions have been obtained, when the encoder 2 with a pulley detects that the amount of needle thread taken out by the thread take-up is P+ during full-scale work, the needle thread gripping device 3 holds the needle thread. If you prevent the upper thread from being let out any further, the upper thread will always be let out by the length of P+ for each stitch, so good stitching will always be performed. When a pulse motor with a pulley is used instead of the encoder 2 with a pulley, the needle thread length required for one stitch is detected by the number of pulses generated by idle rotation of the pulse motor during test sewing, and the length of the needle thread required for one stitch is detected during the actual sewing work. The upper thread is forcibly moved to P + phantom by driving the pulse motor with an intermediate value between the number of pulses corresponding to the needle thread length required for one stitch and the number of pulses corresponding to the stitch pitch length. may be fed to the thread take-up side, and the thread thread take-up may be made to perform only the thread tightening action.Furthermore, in another embodiment, an electromagnetic needle thread tension adjustment disc device is used as the needle thread gripper 3, and The overall lowering condition of the upper thread and bobbin thread by the strain gauge 7 At the time of interlacing, the upper thread gripper by the tension disc is released, and the upper thread amount is detected by the encoder 2. During full-scale sewing, the upper thread amount is detected as a tension disc device. The needle thread tension may be adjusted so that the amount of needle thread bran drawn out by the thread take-up becomes the appropriate length P+phantom.

In this case, the encoder 2 detects when the upper thread line is on base, and feeds back to the adjustment disc device so that the amount of bare thread line becomes P+. As explained above, according to the present invention, a strain gauge for detecting changes in needle thread tension is provided in a sewing machine to detect the interlacing timing of the upper thread and bobbin thread on the entire lower surface of the fabric (intersecting longitudinal timing in the suspended sewing state). Therefore, the length of the needle thread for the first stitch required for a good key in the sewing work of the sewing machine is determined by the mystery stitch, and the needle thread is paid out by this length, so it is easy to use in any situation. Can perform good sewing work.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the sewing state by the sewing machine, where A shows the lower hanging stitch, the opening shows the upper hanging stitch, and C shows the good sewing condition, Fig. 2 is a diagram showing an embodiment according to the present invention, and Fig. 3 shows the sewing condition of the sewing machine. The figure is an oscillographic diagram showing changes in needle thread tension. 1... Sewing machine, 2... Encoder with IJ or pulse motor with pulley, 3... Needle thread gripper or electromagnetic needle thread tension adjustment counter, 4... Needle thread, 6... Bevel - Tension plate, 7...Needle thread tension change gauge, 8...
- Balance, 10... Cloth, P... Stitch pitch, d...
Cloth thickness. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A base tension device, a needle thread payout amount detector, an electromagnetic needle thread gripper,
A strain gauge for detecting changes in needle thread tension is provided, and the time when the needle thread and bobbin thread are intertwined on the lower surface of the sewing material (interlacing time in the hanging sewing state) is determined by measuring the needle thread tension between the needle thread gripper and the thread take-up lever. The system is configured to detect the change using a strain meter, and at that time, release the upper thread gripping by the upper thread gripper to temporarily perform test sewing as a hanging stitch. After detecting the required needle thread length, the built-in calculation circuit calculates the sum of 1/2 of this needle thread length and the pitch length of one stitch, and then threads the needle thread of a length corresponding to that length for each stitch. A sewing tension control device for a sewing machine that allows the sewing machine to be fed out for full-fledged sewing. 2 A pulse motor with a pulley is used as the needle thread payout amount detector. During test sewing, the needle thread length required for one stitch is detected by the number of pulses generated by idle rotation of the pulse motor, and during full-scale sewing, the needle thread length is detected by pulses. 2. The sewing machine sewing tension control device according to claim 1, wherein the motor is configured to supply the needle thread length of the first stitch required for good stitching to the thread take-up side. 3. The stitching tension control device for a sewing machine according to claim 1, which uses an electromagnetic needle thread tension adjustment disc device as the needle thread gripper.