JPS6055153B2 - electric sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric sewing machine, and more particularly to an electric sewing machine that can detect the end of an object to be sewn, such as cloth, and automatically stop stitching at an optimal position.

Conventionally, when sewing small pieces of fabric, such as for pockets, onto a large piece of fabric, a skilled sewing worker can proceed with the work efficiently with his/her proficiency, but an unskilled person may have trouble finishing the sewing at a predetermined position. It often deviates from the position of If the sewing end position is before the predetermined position, it is necessary to sew again, which results in double effort and reduces work efficiency, and if the sewing end position exceeds the predetermined position, the quality of the product deteriorates. In order to solve these problems, an electric sewing machine has been proposed which is equipped with a stitch count setting device and has a mechanism that automatically stops the sewing machine after sewing the number of stitches set in the stitch count setting device. Ta.

However, in this electric sewing machine, the feed amount of the feed device and the actual feed amount differ depending on the type of fabric, sewing speed, etc. Therefore, even if the number of stitches is set constant using the stitch number setting device, the stitch length changes depending on the type of fabric, and the above-mentioned drawbacks cannot be completely eliminated.
This point will be explained more specifically.

When sewing a fabric of length L6 to a longer fabric,
Assuming that the feed amount per stitch of the feed device is 1-, and the ratio (slip) between the feed amount and the actual amount of cloth fed is S, the number of stitches N is determined by the following formula. N=L11(1-5)...
- (1) In this equation (1), the slip s changes depending on the type of fabric, sewing speed, presser foot pressure, etc.

The length L of the fabric to be sewn is 100Tn1, and the feed amount 1 per stitch of the feeder is 2T! g! When t1 slip S is 0.05 and 0.1, the number of stitches N is calculated from the above formula (1). When S is 0.05, N is 52.輯、
When S is 0.1, N is 55.61i''. In order to prevent the seams from coming out of the fabric, it is necessary to set the former to 5 stitches and the latter to 55 stitches. Therefore, If the former and the latter are sewn with the same number of stitches N, there will be an excess or deficiency of 3 stitches, and the number of stitches will be incorrect depending on the stitch length.For this reason, it is not possible to maintain a constant quality by simply setting the number of stitches. It is very difficult to obtain a sewn product with a high quality.An object of the present invention is to provide an electric sewing machine that eliminates the above-mentioned drawbacks of the prior art and can produce sewn products of stable quality.

To achieve this objective, the present invention includes an electric motor with a brake for driving the sewing machine, a stitch number setting device that can set the number of stitches, and a device that detects whether the sewing machine needle is in the upper or lower position. In an electric sewing machine equipped with a sewing machine needle position detection device and a control device that controls the rotational speed of the sewing machine using signals output from the stitch number setting device and the sewing machine needle position detection device, A thickness detection device for detecting changes is installed at a predetermined distance from the sewing machine needle, and from the time when the thickness detection device detects that the thickness of the object to be sewn has decreased, the number of stitches is set in the stitch number setting device. The sewing machine is characterized in that the rotational speed of the sewing machine is controlled by the control device using the stitch number setting signal obtained by the sewing machine and the position detection signal from the sewing machine needle position detection device.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an electric sewing machine.

The sewing machine body 1 is installed above the sewing machine table 2, and at its end there is a sewing machine shaft pulley 1J3 and a speed generator. A synchronizer 4 including a sewing machine and a sewing machine needle position detection device are installed. Reference numeral 5 denotes an electric motor, and a clutch friction plate 6 is connected to the rotating shaft of the electric motor, and a brake friction plate 7 is installed at a predetermined distance from the clutch friction plate 6. A clutch plate 8 is slidably disposed between the clutch friction plate 6 and the brake friction plate 7, and a transmission pulley 9 is connected to the clutch plate 8. A belt 10 is stretched between them. A clutch coil 11 is provided near the clutch friction plate 6, and a brake coil 12 is provided near the brake friction plate 7. When the clutch coil 11 is excited, the clutch plate 8 moves in the axial direction depending on the strength of the excitation, and the rotation of the transmission pulley 9 can be accelerated or decelerated. When the excitation of the clutch coil 11 is the strongest, the clutch friction plate 6 and the clutch plate 8 rotate together to obtain the maximum speed, and when the excitation of the clutch coil 1-1 is weakened, the clutch plate 8 increases the clutch friction. A slip occurs against the plate 6, and the number of rotations can be lowered. When the brake coil 7 is energized, the clutch plate 8 moves toward the brake friction plate 6 and comes into contact with it, making it possible to stop the rotation of the transmission pulley 9. Therefore, by adjusting the current flowing through the clutch coil 11 or the brake coil 12, the rotational speed of the sewing machine main body 1 can be accelerated, decelerated, or stopped. 2 and 3 are diagrams showing the structure of the thickness detection device and its vicinity.

Reference numeral 13 is a cloth feeder built into the sewing machine, which is movable in vertical and horizontal directions, and a cloth presser foot 14 is disposed above the cloth feeder 13.

For example, the object to be sewn 16 made of a polymer of a large cloth 15A and a small cloth 15B is moved by the cloth feed 1 by the cloth presser foot 14.
It is elastically pressed toward the 3rd side. When the sewing object 16 is being fed normally, the tooth portion 17 of the cloth feeder 13 comes out above the sewing machine head surface 18 and moves in the direction of arrow P, so that the sewing object 16 is fed in the P direction. Although not shown, a sewing machine needle 19 (see Fig. 1) is disposed on the right side of the presser foot 14 so as to be movable up and down, and the sewing object 16 that is sent is sewn with the sewing machine needle 19. be combined. A thickness detection device 20 is installed on the left side of the presser foot 14 as viewed in the drawing.

This thickness detection device 20 is provided with two fixing parts 21 and 21 arranged symmetrically in the vertical direction, and a bearing part 23 is supported on each fixing part 21 via a spring 22. The bearing parts 23 face each other, and the lower bearing part 23 has an electromagnetic coil 24A, and the upper bearing part 23 has an electromagnetic coil 24A.
Electromagnetic coils 24B are rotatably supported by the respective electromagnetic coils 24A and 24B, and these electromagnetic coils 24A and 24B are always urged toward each other by the elasticity of the spring 22, respectively. The object to be sutured 16 passes between the electromagnetic coils 24A and 24B, and the distance G between the electromagnetic coils 24A and 24B is determined by the elasticity of the spring 23.
It is designed to be able to immediately respond to changes in the thickness of 6. FIG. 2 shows a polymer of large fabric 15A and small fabric 15B passing through thickness detection device 20. FIG.

Therefore, the distance q1 between the electromagnetic coils 24A and 24B at this time corresponds to the total dimension of the thickness of the cloth 15A and the thickness of the cloth 15B. As the stitching progresses, the cloth 15
When the end of B has passed between the electromagnetic coils 24A and 24B, the distance G2 between the electromagnetic coils 24A and 24B becomes the thickness of the cloth 15A. By reducing the distance between the electromagnetic coils 24A and 24B from G1 to G2 in this way, the electromagnetic coil 2
The inductances of 4A and 24B change, and the change in the thickness of the object 16 to be sewn, that is, the end of the small cloth 15B to be sewn, can be detected.
Since this thickness detection device 20 is arranged at a predetermined distance from the position of the sewing machine needle 19, by detecting the end of the small cloth 15B with the thickness detection device 20, the sewing machine needle 19 will inevitably be It is possible to set a constant dimension from the position to the end of the cloth 15B.

Distance from the position of the sewing machine needle 19 to the thickness detection device 20 (the end of the cloth 15B) is 20 m, the feed amount is 2 gourds, and the slip is 0.
．． Calculating the number of stitches for the cases of 0.05 and 0.1, the number of stitches after detection is 10.0 when the slip is 0.05. Sorry, if the slip is 0.1, it will be 11.1 stitches. In this way, the difference in the number of stitches due to the difference in slip becomes much smaller than in the conventional case, and as the thickness detecting device 20 is brought closer to the sewing machine needle 19, the difference in the number of stitches becomes smaller. FIG. 4 is a block diagram of the drive control section of the electric sewing machine. Based on the above calculation result, the number of stitches in the stitch number setting device 25 is set to 10E. On the other hand, the sewing machine needle position detection device 26
is to detect the number of times the sewing machine needle 19 comes to the lower position,
The lower position signal is output once per rotation of the sewing machine, and the thickness detection device 20 detects the sewing object 16.
It is input to the control device 27 as valid from the time when it is detected that the thickness of the filter has decreased. The control device 27 is connected to the clutch coil 11 and the brake coil 12 so as to be able to control the rotational speed of the sewing machine main body 1. Therefore,
At the point when the thickness detection device 20 detects that the thickness of the object 16 to be sewn has decreased (in the above example, the distance to the end of the small cloth 15B is 20!1 gR), the clutch coil 11 is actuated to start the sewing machine. While decelerating the rotation of the main body 1, advance the number of stitches by 1 stitch set in the stitch number setting device 25,
The number of lower position detection signals from the sewing machine needle position detection device 26 is 1 (
An automatic thread cutting device (not shown) is operated at the IBth thread to cut the thread. Thereafter, when the sewing machine needle 19 reaches the upper position, the brake coil 12 is activated to stop the sewing machine body 1 at a predetermined stitch position. In the above embodiment, the case of forward feeding of the object to be sutured has been described, but even in the case of reverse feeding, the end of the object to be sutured can be similarly detected and automatically stopped. Further, as means for detecting changes in the thickness of the object to be sutured, in addition to the above-mentioned embodiments, optical or capacitive means may be used. The present invention has the above-mentioned configuration, and no matter how long the stitch length becomes, the number of stitches is set within a fixed, relatively short distance near the end of stitching, so that the number of stitches is determined by the difference in slip. There is almost no error in numbers, and suturing can be automatically stopped at the optimal position.

Therefore, it is possible to provide an electric sewing machine that can significantly improve work efficiency and produce sewn products of stable quality.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of an electric sewing machine according to an embodiment of the present invention, Figs. 2 and 3 are enlarged sectional views showing the thickness detection device of the electric sewing machine and its surrounding structure, and Fig. 4 is a block diagram of a drive control section of the electric sewing machine. 1...Sewing machine body, 5...Electric motor, 6
・・・・・・Clutch 7 friction plate, 7・・・Brake friction plate, 8・・・Clutch plate, 11・・・・・・
・Clutch coil, 12...brake coil,
15A, 15B... Cloth, 16... Object to be sutured, 19... Sewing machine needle, 20...
Thickness detection device, 24A, 24B... Electromagnetic coil, 25... Stitch number setting device, 26... Sewing machine needle position detection device, 27... Control device.

Claims (1)

[Claims] 1. An electric motor with a brake for driving the sewing machine, a stitch number setting device that can set the number of stitches, and a sewing machine needle position detector that detects whether the sewing machine needle is in the upper or lower position. and a control device that controls the rotational speed of the sewing machine using signals output from the stitch number setting device and the sewing machine needle position detection device, detecting a change in the thickness of an object to be sewn. A thickness detection device is installed at a predetermined distance from the sewing machine needle, and from the time when the thickness detection device detects that the thickness of the object to be sewn has decreased, the number of stitches set in the stitch number setting device changes. An electric sewing machine characterized in that the control device controls the rotational speed of the sewing machine using a number setting signal and a position detection signal from the sewing machine needle position detection device. 2. In claim 1, the thickness detection device has at least two electromagnetic coils that are biased toward each other, and an object to be sutured is passed between the electromagnetic coils to detect the object to be sutured. An electric sewing machine that detects changes in the thickness of objects as changes in the inductance of an electromagnetic coil.