JP3887680B2 - Method and apparatus for controlling needle thread tension of sewing machine - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a sewing thread upper thread tension control method and apparatus.
[0002]
[Prior art]
In many sewing machines, tension is applied to the upper thread by the thread tension. The optimum value of the tension varies depending on various conditions such as the type of needle thread, sewing speed, stitch to be formed, etc., so the operator manually operates the thread tension and adjusts the tension according to these conditions. . Therefore, this adjustment requires experience, skill, and labor, and it is difficult to cope with various conditions that change during operation. Of these conditions, a technique for automatically adjusting the thread tension according to the sewing speed has been developed for the sewing speed (Japanese Patent Laid-Open No. 54-60047). However, there is no prior art that considers other conditions.
[0003]
[Problems to be solved by the invention]
Therefore, a particular problem occurs when a stitch having a long stitch length and a stitch having a short stitch length are switched during operation. For example, since an embroidery sewing machine mainly forms so-called satin stitches that are sewn in a zigzag shape, the operator operates the thread tension to weaken the tension of the upper thread in accordance with the satin stitch. However, the embroidery sewing machine may be switched during operation to form a so-called walking stitch that is sewn linearly. In that case, if the tension of the upper thread remains weak for the satin stitch, the upper thread is sent too much, and the walking stitch sometimes floats in a loop from the workpiece. In other words, it is better to reduce the tension for a satin stitch with a long stitch length, but it is better to increase the tension for a walking stitch with a short stitch length. Therefore, when the walking stitch is lifted, the operator needs to operate the thread tension to increase the tension of the upper thread in accordance with the walking stitch, which is troublesome.
[0004]
The object of the present invention is to solve the above-mentioned problems, and even when a satin stitch having a long stitch length and a walking stitch having a short stitch length are switched during operation, an optimum tension is automatically applied to the upper thread so that a beautiful stitch is obtained. It is an object to provide an upper thread tension control method and apparatus for a sewing machine capable of forming
[0005]
[Means for Solving the Problems]
According to the needle thread tension control method of the sewing machine of the present invention, the stitch formation data input to the sewing machine control device is prefetched for each of a plurality of stitches counted sequentially from the next stitch for each stitch sewing operation by the sewing machine. a prefetch the plurality needles of data, when the next short walk stitch stitching long satin stitch or stitch lengths stitch length to be formed is determined in the immediately preceding the stitch, based on the determination, then the stitch to be formed is When the satin stitch is used, the tension of the upper thread is reduced . When the next stitch to be formed is the walking stitch, the tension of the upper thread is increased. When the tension of the upper thread is changed, the needle tip of the sewing needle is dead. This is performed when the balance is also lowered and the upper thread is loose.
[0006]
The upper thread tension control device of the sewing machine of the present invention is a sewing machine provided with tension applying means for adjusting the tension to the upper thread so that the tension can be adjusted. The stitch formation data input to the control device of the sewing machine is stitched by one stitch by the sewing machine. a prefetch means for prefetching by multiple needles minute counting from sequential next one needle for each operation, a plurality stitches of data prefetch look-ahead unit, the stitch to be formed next is a long satin stitch or stitch lengths stitch length Based on the discrimination by the discrimination means for judging whether the stitch is a short walking stitch, and the discrimination by the discrimination means , when the stitch to be formed next is the satin stitch, the upper thread weaken the tension, then an automatic operating means for strongly the tension of the upper thread when stitching the walk stitch forming, the automatic operation means, the sewing needle of the Previously located near the bottom dead center, when a loose upper thread have also lowered balance was assumed to change the tension of the upper thread.
[0008]
[Action]
According to the needle thread tension control method and apparatus of the present invention, even when a satin stitch having a long stitch length and a walking stitch having a short stitch length are switched during operation, the stitch forming input input to the control device of the sewing machine is performed. pre-read data by multiple needles minute counting from one stitch sewing operation each sequentially the next one stitch by a sewing machine, the pre-read multiple needles of data, then a long satin stitch or stitch length stitches of stitch length to be formed or shorter walk stitch was determined just before the stitched, based on the determination, and then stitch forming weak tension of the upper thread when the satin stitch, then the stitch of the walk stitch forming When the upper thread tension is increased, the upper thread tension is changed when the needle tip of the sewing needle is near the bottom dead center, the balance is also lowered and the upper thread is loose. Is performed, you can always form a clean stitch.
[0009]
【Example】
Hereinafter, an embodiment in which the present invention is embodied in an upper thread tension control method and apparatus for an embroidery sewing machine will be described with reference to the drawings. First, FIG. 1 schematically shows a main part of an embroidery sewing machine incorporating an upper thread tension control device. A thread tension 3 as a tension applying means is attached to the front surface of the thread guide device mounting base 2 provided above the sewing head 1.
[0010]
As shown in FIG. 2, the thread tension 3 includes a hollow tension shaft 5 fixed to the mounting cylinder portion 4 of the mount 2, a thread take-up spring 6 mounted on the outer periphery of the middle portion of the tension shaft 5, and a tension. A pair of front and rear tone plates 7, 8 mounted on the outer periphery of the front portion of the shaft 5, a conical coil-shaped tone spring 9 that biases the front tone plate 7 to the rear tone plate 8, and the tone shaft 5 A tension nut 10 that is screwed to the outer periphery of the front portion and adjusts the compression amount of the tension spring 9 is configured. The upper thread 11 sent from above to the thread tension 3 is wound between the tension plates 7 and 8, hooked by the thread take-up spring 6, and further sent downward.
[0011]
An adjusting shaft 28 that rotates together with the nut is attached to the tension nut 10. The adjusting shaft 28 is inserted into a hollow portion of the tension shaft 5 and extends rearward, and an end thereof serves as an automatic operation means of the thread tension 3. A rotary shaft 13 of a rotary driver 12 such as a rotary solenoid or a pulse motor is connected by a joint 14.
[0012]
As is well known, the sewing machine head 1 has passed through a hook-shaped upper thread guide 15 for turning the upper thread 11 fed from the thread take-up spring 6 upward, a balance 16 for passing the upper thread 11 fed from the upper thread guide 15, and a balance 16. A sewing needle 17 for passing the upper thread 11 is provided. A hook 21 is provided below the needle plate 19 of the sewing machine table 18 so that the lower thread 20 is fed out and entangled with the upper thread 11.
[0013]
An embroidery frame 24 with a work ground 23 is attached to a drive frame 22 provided immediately above the sewing machine table 18, and the drive frame 22 is an X-axis pulse motor 26 and a Y-axis pulse motor 27 of the drive means 25. Is driven in the X-Y axis direction.
[0014]
The control device 30 for the embroidery sewing machine includes a microcomputer 34 composed of a CPU 31, a memory 32, an input / output interface 33, and a data input device 35 such as a keyboard, a floppy disk drive, an IC card reader, and a CD-ROM drive. It has. By inserting a floppy disk, IC card, CD-ROM or the like in which data for stitch formation is stored into the data input device 35, the data is input to the control device 30. An encoder 38 for detecting the rotation angle of the sewing machine main shaft 37 driven by the main shaft motor 36 is connected to the input side of the control device 30, and the X-axis pulse motor 26 and Y are connected to the output side of the control device 30. A shaft pulse motor 27 is connected.
[0015]
Further, as shown in FIG. 3, the control device 30 of the present embodiment is configured to pre-read the input stitch formation data sequentially for 10 stitches, and from the data for 10 stitches pre-read by the pre-reading unit. And determining means for determining whether the stitch to be formed is a satin stitch or a walking stitch.
[0016]
The rotation driver 12 is connected to the output side of the control device 30, and the rotation driver 12 automatically rotates the tension nut 10 via the adjustment shaft 28 based on the determination by the determination means. Adjust the tension of the upper thread 11. That is, when the next stitch to be formed is a satin stitch, the tension of the tension spring 7 is decreased by decreasing the compression amount of the tension spring 9 to weaken the tension of the upper thread, and the next stitch to be formed is a walking stitch. In this case, the tension of the upper thread is increased by increasing the amount of compression of the tension spring 9 and increasing the bias of the tension plate 7. In parallel with this adjustment, the control device 30 drives the embroidery frame 24 through the control of the X-axis pulse motor 26 and the Y-axis pulse motor 27, and the sewing machine head 1 synchronizes with the rotation of the sewing machine main shaft 37 one by one. Form stitches. Every time one stitch is finished, as shown in FIG. 3, the prefetching means prefetches data for the next 10 stitches.
[0017]
The needle thread tension control method and apparatus of the present embodiment configured as described above operate, for example, as follows. As shown in FIG. 4, the needle drop points N1 to N11 are the satin stitches S, the needle drop points N12 to N27 are the walking stitches W, and the needle drop points N28 to N37 are the satin stitches. Assume an embroidery example such as S. FIG. 5 shows the relationship between the movement of the needle tip of the sewing needle 17, the movement of the embroidery frame 24, and the tension of the upper thread 11 in this embroidery example.
[0018]
{Circle around (1)} Before the sewing needle 17 falls to the needle drop point N1, the control device 30 as the pre-reading means and the discrimination means pre-reads the stitch formation data by 10 stitches, and the next stitch to be formed is the satin stitch S. It is determined that. Then, as shown in FIG. 2A, the rotation driver 12 automatically rotates the tension nut 10 based on the determination by the determination means, and weakens the tension of the upper thread 11. In this state, since the sewing needle 17 falls to the needle drop point N1 and the embroidery frame 24 moves each time the needle tip of the sewing needle 17 comes near the top dead center, the satin stitch S from the needle drop points N1 to N11 is formed. The Note that after the sewing needle 17 has fallen to the needle drop point N2, the control device 30 starts prefetching the data of the walking stitch W after the needle drop point N12. The upper thread tension is not changed until after N11.
[0019]
(2) Next, when the sewing needle 17 passes the needle drop point N11, the control device 30 determines that the next stitch to be formed is the walking stitch W from the pre-read and stored data. Then, as shown in FIG. 2B, the rotation driver 12 automatically rotates the tension nut 10 based on the determination by the determination means, thereby increasing the tension of the upper thread 11. In this state, the sewing needle 17 falls to the needle drop point N12, and the embroidery frame 24 moves each time the needle tip of the sewing needle 17 comes close to the top dead center. Therefore, the walking stitch W from the needle drop point N12 to N27 is formed. The Note that after the sewing needle 17 has fallen to the needle drop point N18, the control device 30 starts prefetching the data of the satin stitch S after the needle drop point N28. The upper thread tension is not changed until N28 is reached.
[0020]
(3) Next, when the sewing needle 17 has passed the needle drop point N27, the control device 30 determines that the next stitch to be formed is the satin stitch S from the data stored in advance. Then, the rotation driver 12 automatically rotates the tension nut 10 based on the determination by the determination means, and weakens the tension of the upper thread 11. In this state, since the sewing needle 17 falls to the needle drop point N28 and the embroidery frame 24 moves each time the needle tip of the sewing needle 17 comes near the top dead center, the satin stitch S from the needle drop points N28 to N37 is formed. The
[0021]
The needle thread tension is changed from (1) to (2) and from (2) to (3) when the needle tip of the sewing needle 17 is near the bottom dead center at the needle drop point N12 or N28. . That is, when the needle tip is at the bottom dead center, the balance 16 is also lowered and the upper thread 11 is loose. At this moment, the rotary driver 12 automatically rotates the tension nut 10 to switch the tension of the upper thread 11 and then lift the balance 16.
[0022]
Note that the data prefetched by the control device 30 is not limited to 10 stitches and can be changed as appropriate. In this embodiment, the upper thread tension is always changed every time switching between the satin stitch and the walking stitch. However, if the data of the satin stitch or the walking stitch does not continue for a predetermined stitch or more, the upper thread tension is changed. Can be set so as not to change, and the rotary driver 12 can be prevented from operating too frequently.
[0023]
Next, FIG. 6 shows a modified example of the automatic operation means of the thread tension 3. In this modified example, a pressing shaft 42 of a pressing driver 41 such as a push solenoid or a fluid pressure cylinder is in contact with an end of an adjustment shaft 40 extending rearward from the tone shaft 5. The pressing driver 41 is automatically activated and stopped based on the determination by the determination unit. That is, when the next stitch to be formed is a satin stitch, the operation is performed as shown in FIG. Decrease the tension of 11. When the next stitch to be formed is a walking stitch, as shown in FIG. 6 (a), the stitch is stopped and the tension shaft 5 is returned backward to increase the tension of the upper thread.
[0024]
In addition, this invention is not limited to the said Example, For example, as follows, it can also change suitably in the range which does not deviate from the meaning of invention, and can also be embodied.
(1) Use a device other than the thread tension as the tension applying means.
(2) To be embodied in various sewing machines other than the embroidery sewing machine.
[0025]
【The invention's effect】
Since the upper thread tension control method and apparatus of the sewing machine of the present invention is configured as described above, even when a satin stitch having a long stitch length and a walking stitch having a short stitch length are switched during operation, the upper thread is automatically selected. An excellent effect is achieved in that an optimal tension can be applied to the surface to form a beautiful stitch.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a main part of an embroidery sewing machine incorporating an upper thread tension control device according to an embodiment of the present invention.
FIG. 2 is a side view of a thread tension as a tension applying unit and a rotary driver as an automatic operation unit in the control device.
FIG. 3 is a flowchart showing a needle thread tension control method by the control device.
FIG. 4 is a plan view schematically showing an embroidery example by the embroidery sewing machine.
FIG. 5 is a time chart showing the relationship between the movement of the needle tip of the sewing needle, the movement of the embroidery frame, and the tension of the upper thread in the embroidery example.
FIG. 6 is a side view showing a modified example of automatic operation means.
[Explanation of symbols]
3 Thread tension 11 as tension applying means 12 Upper thread 12 Rotation driver 30 as automatic operation means Control device 41 as pre-reading means and discrimination means Press driver S as automatic operation means S Satin stitch W Walking stitch

Claims (2)

The stitch formation data input to the control device of the sewing machine is pre-read for each of a plurality of stitches counted from the next stitch for each stitching operation by the sewing machine.
A prefetch the plurality needles of data, stitches formed in the following, it is determined whether a short walk stitch long satin stitch or stitch lengths stitch length immediately before the stitch,
Based on the determination, when the next stitch to be formed is the satin stitch, the tension of the upper thread is weakened . When the next stitch to be formed is the walking stitch, the tension of the upper thread is increased .
The upper thread tension control method according to claim 1, wherein the change of the upper thread tension is performed when the needle tip of the sewing needle is near the bottom dead center, the balance is also lowered, and the upper thread is loosened. In a sewing machine provided with tension applying means for adjusting the tension to the upper thread in an adjustable manner,
Pre-reading means for pre-reading the stitch formation data input to the control device of the sewing machine by a plurality of stitches sequentially counted from the next one stitch for each stitching operation by the sewing machine;
A plurality stitches of data prefetch look-ahead unit, a determination unit for stitch to be formed next is to determine whether a short walk stitch long satin stitch or stitch lengths stitch length immediately before the stitch,
When the next stitch to be formed is the satin stitch, the upper thread tension is reduced by automatically operating the tension applying unit based on the determination by the determination unit, and the next stitch to be formed is the walking stitch. Has automatic operating means to increase the tension of the upper thread,
The automatic operation means is configured to change the upper thread tension of the sewing machine when the needle tip of the sewing needle is near the bottom dead center, the balance is also lowered, and the upper thread is loosened. Control device.

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