JP2003117276A - Sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely take synchronization by a simple control method, to accelerate a rotation speed and to improve productivity of a sewing machine, the needle and shuttle of which are independently controlled. SOLUTION: The sewing machine 1 is provided with the sewing machine needle 3 vertically moved so as to pass through an object S to be sewn mounted on a sewing machine bed 1a, the shuttle 4 capturing a loop of needle thread formed at a tip of the sewing machine needle 3, a main shaft servo motor 50 driving the sewing machine needle 3, a shuttle shaft servo motor 52 driving the shuttle 4 and a CPU 11 performing control so as to synchronously operate the main shaft servo motor 50 and the shuttle shaft servo motor 52, and the sewing machine needle 3 and the shuttle 4 are independently and synchronously driven. The CPU 11 performs synchronization control for a section from a reference position in front of a thread hooking position to the thread hooking position while the tip of the sewing machine needle 3 moves from a through position at which it passes through the object S to be sewn to a detaching position at which it is detached with higher accuracy compared to the other section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine in which a sewing needle and a thread hooking member for catching an upper thread passed through the sewing needle are independently driven and controlled.

[0002]

2. Description of the Related Art In a conventional sewing machine, a sewing machine needle is driven up and down by a main shaft driven by a main motor, and the rotation of the main shaft is mechanically transmitted to a lower shaft so that the sewing machine needle passes through the sewing machine needle. The needle and the thread hooking member are synchronized with each other by driving a member such as a hook for catching the thread (hereinafter, thread hooking member). However, in recent years, sewing machines have been developed in which the main shaft and the lower shaft are driven by different drive sources. In such a sewing machine, it is necessary to control the main shaft and the lower shaft with high accuracy so that the thread hooking member can surely catch the upper thread on the sewing machine needle side. For example, Japanese Patent Laid-Open No. 9-
Japanese Patent No. 140972 discloses that a rotation deviation adjustment amount (phase offset adjustment amount) of a hook is set in a memory for each rotation position in one cycle operation of a sewing machine needle, and control is performed based on the setting. A sewing machine is disclosed.

[0003]

By the way, in the sewing machine of the above publication, since the adjustment amount is set in advance, the rotary position of the shuttle relative to the sewing machine needle is set to 1 for a certain rotary position.
If you make a shift, you will maintain that state.
However, in actual sewing, the situation slightly changes with each cycle, so in the end, it is necessary to purposely correct the "deviation" of the hook (lower shaft) according to the situation, and complicated control is required. there were. In addition, since both axes are synchronized once for one cycle, it becomes impossible to synchronize when the rotation speed is increased, and as a result, the rotation speed is limited and productivity is low. there were.

An object of the present invention is to provide a sewing machine in which a sewing machine needle and a thread hooking member such as a shuttle are independently controlled and driven, and the sewing machine needle and the shuttle are reliably synchronized by a relatively simple control method, and the rotation speed is To increase productivity.

[0005]

In order to solve the above-mentioned problems, the invention described in claim 1 is, for example, as shown in FIGS. 1 to 4, a needle thread is passed through the sewing machine bed (1a). A sewing machine needle (3) that moves up and down so as to be capable of penetrating the work to be sewn (S) to be placed, and a thread hooking member (hook 4) that catches the upper thread of the sewing machine needle at a predetermined thread hooking position under the sewing machine bed. ) And needle driving means for driving the sewing machine needle (spindle servomotor 50)
, A thread hooking member drive means (hook shaft servo motor 52) for driving the thread hooking member, and a synchronous control means (CPU for controlling the needle drive means and the thread hooking member drive means to operate in synchronization with each other.
11), in which the sewing machine needle and the thread hooking member are driven independently and synchronously, in the sewing machine (1), the synchronization control means withdraws from the penetration position where the tip of the sewing machine needle penetrates the workpiece. It is characterized in that the synchronization accuracy of the threading section from at least the predetermined position (reference position) before the threading position to the vicinity of the threading position during the movement to the pulling-out position is controlled with higher accuracy than other sections. And

According to the first aspect of the invention, the tip of the sewing machine needle exceeds the penetration position where the load is applied when the sewing object penetrates, and the frictional resistance with the sewing object disappears when the sewing object is pulled out. Up to the withdrawal position, that is, when the tip of the sewing machine needle is below the material to be sewn, at least the synchronization accuracy of the threading section from the predetermined position before the threading position to near the threading position,
Control is performed with higher accuracy than other sections. With this, only a part of the section including the vicinity of the thread hooking position for catching the thread is precisely controlled, and the other sections are roughly controlled as compared with the thread hooking section, so that the rotation speed is increased and the productivity is improved. be able to. In addition, because it precisely controls only a part of the section including the vicinity of the yarn hooking position that captures the yarn,
The upper thread can be reliably caught, and defects such as skipping can be prevented. Further, since the precision is controlled only in a part of the section, when compared with the sewing machine of the above-mentioned publication in which the offset amount is set over 360 degrees of one cycle,
It requires a small amount of memory and data for control, and is a simple control method. Further, in the thread hooking section, since the tip of the sewing machine needle is below the material to be sewn and the fluctuation of the external force to the sewing machine needle is relatively small and the operation of the sewing machine needle is within a stable range, A high sewing speed can be maintained without slowing down so much. Here, the thread hooking member is a member that captures the upper thread, such as a fully rotating rotary hook that rotates, a half rotary hook that swings, and a looper.

According to a second aspect of the invention, in the sewing machine according to the first aspect, the synchronization control means divides the thread hooking section into a plurality of sections, and the synchronization accuracy of each section approaches the thread hooking position. Therefore, it is characterized in that it is controlled so as to gradually increase. According to the second aspect of the invention, the threading section is divided into a plurality of sections, and the synchronization is controlled with high accuracy gradually as the threading position is approached. The movements of the members can be adjusted without difficulty.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a control block diagram of a sewing machine 1 as an example of the present invention. Note that FIG.
Then, only the configuration necessary for the present invention is shown, and other drive circuits, drive sources, various sensors, etc., which are not necessary for explanation, are omitted. As shown in FIG. 2, the sewing machine 1 includes a needle bar 2 to which a sewing machine needle 3 through which an upper thread T is passed is fixed, and a sewing machine bed 1.
There is provided a shuttle 4 which is provided under a and in which a bobbin case (not shown) accommodating a bobbin wound with a bobbin thread is set. Then, the sewing machine 1 drives the needle bar 2 up and down by a main shaft servo motor (needle driving means) 50, and drives the hook 4 to a hook shaft servo motor (thread hook member driving means) 5.
While rotating by 2, the upper and lower threads are entangled to form a stitch (main stitch) on the workpiece S placed on the bed 1a. In the sewing machine 1, since the shuttle 4 and the sewing machine needle 3 are driven by independent motors, the sword tip 4a of the shuttle 4 which is a thread hooking member can reliably catch the upper thread passed through the sewing machine needle 3. The hook thread hook timing control is required to control the timing so that it can be performed. This will be described in detail later.

As shown in FIG. 1, the sewing machine 1 comprises a microcomputer (hereinafter referred to as a microcomputer) 10, a control section 20 for transmitting and receiving various control signals, an operation panel 30, a foot pedal 40 and the like.

The control unit 20 comprises a sewing machine control circuit 21, an input control circuit 22, and an output control circuit 23. The sewing machine control circuit 21 outputs a control signal for controlling the drive of the spindle servomotor 50 and the shuttle shaft servomotor 52 during sewing. Further, the main shaft servo motor 50 and the shuttle shaft servo motor 52 are respectively provided with a main shaft encoder 50a and a shuttle shaft encoder 52a for detecting the number of rotations (rotational speed) and a rotation angle for each one in close proximity to each other. The detection signals from the encoders 50a and 52a are input to the input control circuit 22. The spindle encoder 50
a and the hook shaft encoder 52a are the main shaft servo motor 50
And the hook shaft servo motor 52 need not be provided, but may be provided on the main shaft and hook shaft (not shown). Further, the sewing machine 1 is provided with a spindle motor origin sensor 51 for detecting a rotation reference position of the spindle servo motor 50 and a hook shaft motor origin sensor 53 for detecting a rotation reference position of the hook shaft servo motor 52. The signals from these sensors 51 and 53 are also input to the input control circuit 22. When the sewing machine needle 3 and the shuttle 4 are synchronized in an ideal correspondence relationship, the shuttle shaft origin sensor 53 detects the reference position of the spindle servo motor 50 by the spindle origin sensor 51 and simultaneously detects the reference of the shuttle servo motor 52. It is provided to detect the position. The specific configurations of the spindle motor origin sensor 51 and the shuttle shaft motor origin sensor 53 are not particularly limited, but for example, a commercially available sensor plate that operates optically, magnetically, or mechanically may be provided. Alternatively, if the main shaft encoder 50a and the shuttle shaft encoder 52a are incremental type rotary encoders, the origin may be detected by the output of the Z phase.

The operation panel 30 includes a display screen (not shown), input switches and buttons, etc. When an operator inputs a predetermined instruction or set value through these switches or the like, the input control circuit 22 of the control section 20 is instructed. Corresponding signal is input. Further, according to the output control signal from the output control circuit 23, predetermined contents are displayed on the display screen. The foot pedal 40 is operated by an operator when starting or ending sewing, and when operated, a predetermined signal is input to the input control circuit 22.

The microcomputer 10 is a CPU (Central Process
sing unit) 11 and ROM (Read Only Memory) 12
And a RAM (Random Access Memory) 13.
In the ROM 12, a control program of the sewing machine 1, control data, and various sewing data are written. The RAM 13 is provided with various work memories, counters and the like, is used as a work area during the sewing operation, and various data relating to the hook thread hooking timing control processing is also stored in the RAM 13.

CPU 10 which is the synchronization control means of the present invention
Sew the sewing machine 1 including the hook thread hooking timing control process while performing various processes based on various signals input to the input control circuit 22 while using the RAM 13 as a work area according to the control program and control data of the ROM 12. The operation is controlled and the display of the operation panel 30 is controlled. In the hook thread hooking timing control process, the CPU 10 causes the spindle motor origin sensor 51,
Based on the signals output from the shuttle shaft motor origin sensor 53, the main shaft encoder 50a and the shuttle shaft encoder 52a, the rotational positions of the main shaft and the shuttle shaft are compared. Then, it is monitored whether the difference between the rotational positions of the two is within the set phase difference (accuracy), and if it exceeds the range, a control signal is output to change the speed of the hook shaft servo motor 52. It is like this.

Next, the hook thread hooking timing control process will be described with reference to FIGS. At the time of sewing, the sewing machine needle 3 (needle bar 2) and shuttle 4 are
It operates like (a) to (c). First, sewing needle 3
2 descends from the state of being located at the top dead center as shown in FIG. 2A, and the shuttle 4 also rotates in the direction of the arrow. Next, the lowered sewing machine needle 3 reaches the sewing target S and penetrates it, as shown in FIG. 2B. The position of the sewing machine needle 3 at this time is defined as the penetration position.

When the sewing machine needle 3 further descends and reaches a predetermined bottom dead center (not shown), the sewing machine needle 3 starts to rise, and at the slightly raised position, the blade point 4a of the shuttle 4 is at the sewing needle 3 as shown in FIG. 2 (c). Approach. At this time, the upper thread continuing to the sewing machine needle 3 is hooked by the sword tip 4a. This position is the threading position. Further, the sewing machine needle 3 rises and comes out of the sewing object S to be in the same state as in FIG. 2 (b). The position of the sewing machine needle 3 at this time is referred to as a withdrawal position. After that, it rises further and returns to top dead center. The above operation is repeated during sewing.

Since the vertical movement of the sewing machine needle 3 (needle bar 2) is a constant cycle movement, it can be considered to be replaced with a circular movement as shown in FIG. 3 or equivalent to the rotational movement of the main shaft. Hereinafter, the movement of the sewing machine needle 3 (needle bar 2) will be described not as a vertical movement but as a rotational movement. In Figure 3,
An example of the angles of the penetrating position and the withdrawal position with respect to the top dead center (0 °) and the bottom dead center (180 °) when the movement of the sewing machine needle 3 in one cycle is 360 ° is shown. . Here, the penetration position is about 114 °, and the extraction position is about 246 °.

In the sewing machine 1, the accuracy (phase difference) of the rotational positions of the sewing machine needle 3 and the shuttle 4 is controlled while changing the accuracy so as to have the highest accuracy immediately before reaching the thread hooking position. . Specifically, first, the sewing machine needle 3 is provided with a reference position at a predetermined position beyond the penetrating position and before the thread hooking position, and further, immediately before reaching the thread hooking position beyond the reference position, the final angle adjusting position is reached. To provide. For example, the reference position is set to 150 ° and the final angle alignment position is set to 185 °.

Until the sewing machine needle 3 reaches the reference position, there is no problem even if the rotational positions of the sewing machine needle 3 and the shuttle 4 are slightly deviated from each other. Therefore, there is a relatively rough phase difference of ± 5 °. Control with precision. Control is performed with a phase difference of ± 3 ° from reaching the reference position to the final angle adjustment position. Control is performed with a phase difference of ± 0.5 ° from reaching the final angle alignment position to the thread hooking position. After the threading position, control is performed again at ± 5 °. In this way, the accuracy was gradually increased, and the control was performed with high accuracy from the reference position where the rotational position must be adjusted most precisely to the yarn hooking position, and the other parts were relatively rough controls. That is, the yarn hooking section of the present invention extends from the reference position to the yarn hooking position. The reference position, the final angle adjusting position, the thread hooking position, and the phase difference (accuracy) are set via the operation panel 30.

Whether or not the reference position has been reached is determined by receiving the detection signal of the spindle motor origin sensor 51. At the same time, when the reference position is reached, the counter for the rotation angle of the spindle is cleared, and while the angle is counted with the reference position as the reference, it is determined that the final angle adjustment position and the thread hooking position have been passed. ing. In this way, the reference position, the final angle adjustment position, and the thread hooking position are detected based on the rotational position of the main shaft. When the sewing machine needle 3 penetrates the sewing object S during the sewing operation, the deviation of the synchronization between the sewing machine needle 3 and the hook 4 is likely to be the largest due to the resistance of the sewing object S. Is set to a position where will be almost eliminated.

FIG. 4 shows a flow chart of the hook thread hooking timing control processing. First, in step S1, it is determined whether or not each motor of the sewing machine 1 is rotating. If it is not rotating, that is, if the sewing operation is not being performed, this process is finished as it is, and if it is determined that it is rotating, the process proceeds to step S2. In step S2, it is determined whether or not the reference position in FIG. 3 has been passed, and if it is determined that the reference position has not been passed, the process proceeds to step S3, in which the phase difference between the spindle and the shuttle is within ± 5 °. Determine whether. If it is within ± 5 °, the process returns to step S2, and if it is over ± 5 °, a process of adjusting the rotation speed of the shuttle shaft servo motor 52 is performed in step S4, and the process returns to step S2. Step S2 to pass the reference position
If S4 is repeated and it is determined in step S2 that the reference position is exceeded, the process proceeds to step S5.

In step S5, the counter counting the rotational position in the RAM 13 is cleared, and the counter is counted up from here (step S6). Next, in step S7, it is determined whether or not the counter value has reached a value equal to or greater than the counter corresponding to the final angle adjustment position. If it is determined that the phase difference is not reached, the process proceeds to step S8, where it is determined whether the phase difference is within ± 3 °. If it is within ± 3 °, the process returns to step S6, and if it is over ± 3 °, a process of adjusting the rotation speed of the shuttle shaft servo motor 52 is performed in step S9, and the process returns to step S6. The processing of steps S6 to S9 is repeated until the final angle adjustment position. When it is determined in step S7 that the counter value is equal to or larger than the value corresponding to the final angle adjustment position, the process proceeds to step S10.

In step S10, it is determined whether or not the counter value has reached a value equal to or greater than the counter corresponding to the thread hooking position. If it is determined that it has not reached step S11
Then, it is determined here whether the phase difference is within ± 0.5 °. If it is within ± 0.5 °, the process returns to step S6. If it is over ± 0.5 °, a process for adjusting the rotation speed of the hook shaft servo motor 52 is performed in step S12, and step S6 is performed.
Return to. Steps S10, S11, S1 to threading position
2, the process of S6 is repeated. When it is determined in step S10 that the counter value is equal to or larger than the value corresponding to the yarn hooking position, this process ends.

According to the sewing machine 1 described above, the synchronous control of the shuttle 4 with respect to the rotational position of the main shaft, that is, the sewing needle 3, is controlled with a relatively rough accuracy of a phase difference of ± 5 ° up to the reference position after the penetration position. However, if the reference position is reached by the signals from the spindle motor origin sensor 51 and the shuttle shaft motor origin sensor 53, ± 3 ° is from the reference position to the final angle adjusting position, and ± is from the final angle adjusting position to the thread hooking position.
A control method is adopted in which the accuracy is gradually increased toward the yarn hooking position that has to be most adjusted, such as 0.5 °. Therefore, it is possible to precisely control only the threading section from the reference position to the threading position in one cycle, and to increase the rotation speed in a range where the threading position is not precisely controlled, that is, after passing the threading position to the reference position. And productivity can be improved. Further, in the thread hooking section, the tip of the sewing machine needle 3 is below the article S to be sewn, the fluctuation of the external force to the sewing machine needle 3 is relatively small, and the operation of the sewing machine needle 3 is in a stable range. It is not necessary to slow down the speed even after entering the section, and a high sewing speed can be maintained.

Further, since the accuracy is improved only in the threading section,
Compared with the sewing machine of the above-mentioned publication in which the offset amount is set over 360 degrees in one cycle, the memory and data for control can be small. Further, since the control method is to check the phase difference in a certain range instead of setting the deviation for each rotational position, it is not necessary to make correction for each cycle, and simple control is also possible in that respect. . Although it is a relatively simple control method like this, since the main shaft and the shuttle shaft are synchronized with each other with sufficiently high accuracy in the thread hooking position, the upper thread can be reliably caught by the sword tip 4a of the shuttle 4. It is possible to reduce defects such as skipped stitches. In particular, since the accuracy is gradually increased in two stages of ± 3 ° and ± 0.5 ° for the yarn hooking section, it is possible to ensure synchronization without difficulty. Furthermore, since the thread hooking position and the accuracy (phase difference) can be set through the operation panel 30 and can be changed as appropriate, by changing the sewing conditions such as the material of the workpiece and the thread type, You can sew more beautifully. Further, by setting the thread hooking section to the shortest length according to the sewing conditions, it is possible to increase the rotation speed and improve the productivity. The changing method includes, for example, a method of directly inputting the start position and the end position of the thread hooking section by the operation panel 30 or a number of thread hooks corresponding to the sewing conditions such as the material of the workpiece and the thread type. The start position and the end position of the section are respectively R in advance.
A method of setting the angle between the start position and the end position of the thread hooking section by storing it in the AM 13 and selecting the sewing condition with the operation panel 30 can be considered.

The present invention is not limited to the above embodiment, and it goes without saying that it can be appropriately modified. For example, the respective positions such as the penetration position and the accuracy (phase difference) are not limited to the angles and values shown in FIG. 3 and can be changed. Further, in FIG. 3, the accuracy is increased in two steps with the final angle adjustment position as a boundary, but it may be increased in one step or in three or more steps. In particular, increasing the accuracy in one step is desirable in that the control can be simplified. Further, in the embodiment, the end position of the thread hooking section is set to the thread hooking position, but the present invention is not limited to this, and may be set between the thread hooking position and the withdrawal position. Further, the end position of the threading section may be near the threading position and before the threading position as long as the thread can be reliably captured. Further, the present invention is not limited to being always performed during the sewing period, but may be performed at a part of the sewing period, for example, a predetermined number of revolutions from the start of sewing to a predetermined number of revolutions until the end of sewing. Good. Further, in the present invention, the reference position, the final angle adjustment position, and the thread hooking position are detected based on the rotation position of the main shaft, but they may be detected based on the rotation position of the shuttle shaft.

[0026]

According to the invention described in claim 1, the tip of the sewing machine needle exceeds the penetration position where the load is applied when the sewing object penetrates and the friction resistance with the sewing object is caused by the removal of the sewing object. Until the withdrawal position is reached, that is, when the tip of the sewing machine needle is below the material to be sewn, the synchronization accuracy of the threading section at least from the predetermined position before the threading position to near the threading position is better than that of other sections. Control with high accuracy. With this, only a part of the section including the vicinity of the thread hooking position for catching the thread is precisely controlled, and the other sections are roughly controlled as compared with the thread hooking section, so that the rotation speed is increased and the productivity is improved. be able to. Further, since the control is precisely performed only in a part of the section including the vicinity of the yarn hooking position for catching the yarn, the upper yarn can be reliably caught and defects such as skipping can be prevented. Further, since only a part of the section is precisely controlled, as compared with the sewing machine of the above-mentioned publication in which the offset amount is set for 360 degrees of one cycle, there is less memory and data for control, and the control method It will be as easy as Further, in the thread hooking section, since the tip of the sewing machine needle is below the material to be sewn and the fluctuation of the external force to the sewing machine needle is relatively small and the operation of the sewing machine needle is within a stable range, A high sewing speed can be maintained without slowing down so much.

According to the invention described in claim 2, since the threading section is divided into a plurality of sections and the synchronization is controlled with high accuracy gradually as the threading position is approached, the sewing machine needle at the threading position is controlled. The movement of the thread hooking member can be reliably and reliably adjusted.

[Brief description of drawings]

FIG. 1 is a control block diagram of a sewing machine that is an example of the present invention.

FIG. 2 is a view for sequentially explaining the movements of the sewing machine needle and the shuttle, and the sewing machine bed is omitted in FIGS.

FIG. 3 is a diagram showing each rotational position for changing accuracy.

FIG. 4 is a flowchart showing hook thread hooking timing control processing.

[Explanation of symbols]

1 sewing machine 2 needle bars 3 sewing needle 10 Microcomputer 11 CPU (synchronous control means) 12 ROM 13 RAM 30 Operation panel 50 Spindle servo motor (needle driving means) 50a Spindle encoder 51 Spindle motor origin sensor 52 hook shaft servo motor (thread hooking member driving means) 52a hook shaft encoder 53 Hook shaft motor origin sensor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinji Kamakura             1 J, 8-2 Kokuryo-cho, Chofu-shi, Tokyo             Within TUKI CORPORATION F term (reference) 3B150 AA02 CB27 CE01 CE23 CE27                       GD14 GD22 JA08 LB01 MA17                       NA72 NA76 NC07 QA04 QA06                       QA07

Claims (2)

[Claims] 1. A sewing machine needle through which a needle thread is passed and which vertically moves so as to be capable of penetrating a sewing object placed on a sewing machine bed, and an upper thread of the sewing machine needle at a predetermined thread hooking position under the sewing machine bed. A thread hooking member that captures the thread, a needle drive unit that drives the sewing machine needle, a thread hooking member drive unit that drives the thread hooking member, and a synchronization that controls the needle driving unit and the thread hooking member drive unit to operate in synchronization. In a sewing machine including a control means, and the sewing machine needle and the thread hooking member are driven independently and synchronously, the synchronization control means is a withdrawal position where the tip of the sewing machine needle is pulled out from the penetration position where the sewing machine penetrates the workpiece. A sewing machine which controls the synchronization accuracy of a threading section from at least a predetermined position before the threading position to the vicinity of the threading position while moving to a higher accuracy than in other sections. 2. The synchronization control means divides the yarn hooking section into a plurality of sections, and controls the synchronization accuracy of each section so as to gradually increase as it approaches the thread hooking position. The sewing machine according to Item 1.