JPH0262276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a speed control device for a cycle sewing machine.

[Conventional technology]

Conventionally, a speed control device in a cycle sewing machine, such as a hole sewing machine, operates a deceleration cam disposed on the main cam in order to operate the knife and forcibly stop the sewing machine needle at approximately top dead center without impact. A few stitches before the end of one sewing cycle, the main shaft of the sewing machine, which is currently in a high-speed rotation state, is brought into a low-speed rotation state, and then the motor is controlled by a stop cam, and the sewing machine main shaft, which is attached to the main shaft, is controlled by a stop cam. The main shaft is stopped at a fixed position by a position detection device, and the sewing machine needle is stopped at a fixed position.
Also, the number of stitches required for one sewing cycle, that is,
The number of stitches formed during one rotation of the rotary disk is set by appropriately changing the gear ratio of the stitch number changing gear.

Therefore, the ratio of the number of stitches in the high-speed drive section and the low-speed drive section is constant, and if the number of stitches required for one sewing cycle increases by m times, the number of stitches in the low-speed drive section also increases by m times in proportion. Become.

[Problem that the invention seeks to solve]

Conventional cycle sewing machine speed control devices only require low-speed drive for a certain number of stitches in order to drop the knife and stop at a fixed position. Accordingly, the main shaft of the sewing machine is driven at a low speed, and as the total number of stitches increases, the unnecessary low speed time required for one sewing cycle increases, resulting in a decrease in work efficiency.

In order to solve this problem, it is possible to adjust the mounting position of the deceleration cam every time the total number of stitches changes, but this is not only cumbersome, but if the adjustment is incorrect, the low-speed drive section will be too long. If the thread is wasted or is too short, problems such as the thread trimming knife operating during high-speed operation may occur.

[Means for solving problems]

This invention aims to shorten the time required for one sewing cycle by keeping the number of stitches constant during the low-speed drive (second drive mode) period, regardless of the total number of stitches required for one sewing cycle. a reference signal generating means that generates one pulse for each rotation of the
1) An up-down counter, in which the number n of stitches for low-speed driving is preset, and that counts pulses from the (n+1)-adic counter when counting down, and pulses from the reference signal generating means when counting up, and low-speed driving. A switching means is provided for switching the up-down counter from a down counter to an up counter at a switching time set in advance according to the number of stitches n.

〔Example〕

FIG. 1 shows an embodiment of the invention. In the figure, 1 is an upper shaft rotatably supported on the sewing machine frame 2, 3 is a drive pulley fixed to the main shaft 1, 4 is a worm gear fixed to the main shaft 1, and 5 is attached to the main shaft 1. A worm wheel is fixed to one end of a shaft 6 provided in a direction perpendicular to the worm gear 4, and meshes with the worm gear 4. 7 is a stitch number changing gear detachably attached to the other end of this shaft 6; 8 is a shaft provided parallel to the shaft 6; 9 is a stitch number changing gear detachably attached to one end of this shaft 8; It meshes with the gear 7. 10 is a main cam drive gear fixed to the other end of this shaft 8; 11 is a main cam that meshes with the main cam drive gear 10; it rotates once per sewing cycle; The operation required for sewing machine operation during one sewing cycle, for example, by reciprocating the cloth feed arm connected to the cloth feed mechanism following the groove of the heart groove cam provided on the surface of the main cam 11, to feed the sewing machine. is going on. By appropriately converting the stitch number changing gears (reduction gears) 7 and 9, the rotation ratio of the main cam 11 to the upper shaft 1 is changed. Reference numeral 13 denotes a cutoff cam provided on the surface of this main cam 11. Reference numeral 14 denotes a hook release lever, whose central portion is pivotally supported by the sewing machine frame 2 and biased clockwise in the figure by a spring. One end of the lever 14 is connected to the main cam 11.
A protrusion 15 that engages with the cutoff cam 13 is provided on the surface thereof, and a hook portion 16 is provided on the other end. A lever 17 is pivotally supported by a support 18 provided on the sewing machine frame 2. A spring 19 is stretched between the center portion of the lever 17 and the sewing machine frame 2, and the lever 17 biases the lever counterclockwise. Reference numeral 20 denotes an engaging protrusion provided at one end of the lever 17, which is adapted to engage with a hook portion 16 provided at one end of the hook removal lever 14. 21 is a switch push plate provided at the other end of the lever 17, and when the projection 15 and the cutoff cam 13 are engaged, the hook portion 16 and the projection 20 are disengaged, and the lever 17 is reacted by the action force of the spring 19. By rotating clockwise, the stop switch 23 is pressed. When this stop switch 23 is pressed by the switch push plate 21, it outputs an L signal, and when the pressure is released, it outputs an H signal. Reference numeral 22 denotes a switch as a position detection means, which is composed of a light shielding plate 22a provided on the peripheral edge of the main cam 11 with one end protruding outward, and a photo interrupter 22b provided near the main cam 11. The photo interrupter 22b outputs an L signal when its optical path is blocked by the light shielding plate 22a, and outputs an H signal otherwise.
The blocking cam 13 and the light blocking plate 22a are connected to the main cam 11.
The angle α made with the center point of is α=360/(n+
1) is satisfied. However, n will be described later (n+
1) It is n of the decimal counter 41c. Reference numeral 24 denotes an L-shaped starting link, the elbow portion of which is rotatably supported by a support 25 provided on the sewing machine frame 2.
One end of the activation link 24 is connected to an activation pedal 27 via a rod 26. 28 is a protrusion provided at the other end of this starting link 24, which is a projection provided on the other end of this starting link 24,
7 in the clockwise direction presses a protrusion 29 provided at one end of the lever 17. Reference numeral 30 designates an electromotor that rotationally drives the driving pulley 3 via a V-belt 31, and an electromagnetic clutch 30a and an electromagnetic brake 30b are provided on the rotating shaft. Reference numeral 32 denotes a speed detection device, which is provided on the upper shaft 1 and detects the rotational speed of the upper shaft 1. Reference numeral 33 is fitted and fixed to the end of the main shaft 1, and a magnet 35 is arranged at the peripheral edge. Reference numeral 37 denotes a Hall element as a reference signal generating means provided near the disk 33, which detects the magnetism of the magnet 35 and outputs an L signal. Further, the signal is generated at a predetermined spindle rotation angle position so that the spindle 1 always stops at a fixed position when it stops. The magnet 35 and the Hall element 37 constitute a reference signal generating means. 39 is a drive control device, and speed detection device 3
2. Based on the signals from the switch 22 and the Hall element 37, the electromotor 30 is driven and controlled to a preset rotational speed, and the stop switch 23
Based on the signal from the Hall element 37, the magnet 35
The position of the motor 30 is detected and the rotation of the motor 30 is stopped at the fixed position. 40 is a knob for setting the maximum rotational speed of the electromotor 30, 41 is a speed switching circuit, and as shown in FIG. ((n+1) base counter) 41c, mono multivibrator 41m, R
-S flip-flop (-F/F) 41f,
41r, 41s, NAND gate 41g, 41h,
AND gate 41k, OR gate 41j, 41l,
It is composed of an inverter 41i and a digital switch 41d.

Next, the effect will be explained.

It is now assumed that the sewing machine is in a stopped state and the various parts are as shown in FIG. That is,
The cutoff cam 13 and the protrusion 15 are in an engaged state, and the stop switch 23 is pressed by the switch push plate 21 and is in the ON state (FIG. 4, 1).

Further, the number of stitches to be driven at low speed (7 stitches in this embodiment) is set in the daisy switch 41d. The total number of stitches is 108.

In this state, when the start pedal 27 is stepped forward (the start pedal 27 rotates clockwise in the figure), the protrusion 28 is pressed against the protrusion 29 as the start link 24 rotates counterclockwise, so the lever 17 is rotated clockwise, and as a result, the switch push plate 21 is separated from the stop switch 23.

When the switch push plate 21 leaves the stop switch 23, the output signal level of the stop switch 23 changes from low level L to high level H.

(1) When starting the sewing machine (i) This H signal is transmitted to the mono multivibrator 41.
When input to m, a single pulse of L is output from the terminal of the mono multivibrator 41m. Then, since the terminal level changes from H to L, the level of the terminal Q of the R-S F/F 41f remains in the L state, and therefore,
The level of one input terminal of the NADN gate 41g becomes L. Therefore, the level of the output terminal of the NAND gate 41g is maintained at the H level.

On the other hand, the level of one input terminal of the NAND gate 41h becomes H because the level of the terminal Q of the F/F 41f is inverted by the inverter 41i. Therefore, the level of the output terminal of this NAND gate 41h, that is,
The level of the terminal T _D of the up-down counter 41u follows the level of the output terminal Q of the octal counter 41c.

Also, since the terminal Q level of F/F41r is H,
It is L. Therefore, the level of the output terminal of OR gate 41j is H.

Furthermore, since the levels of the input terminals of the OR gate 41l are both H, the output terminal is H. Therefore, the level of the output terminal of AND gate 41k is H because the levels of these input terminals are both H. the result,-
The level of the terminal Q of the SF/F 41s becomes H when a single pulse is output from the mono multivibrator 41m. In addition, a single pulse from a 41m mono-multivibrator causes
L is entered in the up-down counter 41u, thereby presetting the value on the digit switch 41d.

(ii) When the H signal from the stop switch 23 is input to the drive control device 39, - F/
Since the level of terminal Q of F41s is L,
The electromotor 30 starts rotating at high speed (FIG. 4, 2).

(iii) When the electromotor 30 starts rotating, the upper shaft 1 rotates, and the main cam 11 rotates via the worm gear 4, worm wheel 5, stitch number changing gears 7 and 9, and main cam drive gear 10. Then, as the main cam 11 rotates, the protrusion 15 of the hook removal lever 14 is disengaged from the cutoff cam 13, and at the same time, the hook portion 16 engages with the surface portion 20a of the engagement protrusion 20. At this time, even if the foot is released from the starting pedal 27, the lever 14 does not return to its original position, and the electromotor 30 continues to drive at high speed (first drive mode) (FIG. 4, 3).

(iv) The octal counter 41c counts 1 for each revolution of the spindle 1, and outputs 1 pulse from the terminal Q every 8 counts to the NAND gate 41h.
Terminal of up-down counter 41u via
Output to T _D. Then, the up-down counter 41d counts down from the preset number of low-speed stitches (=7). In other words, the number of pulses every 8 counts when rotating by angle β (360° - α) in Figure 3 is
If N1, then N1=β÷n (where n is the count number). Also, if α=N2 and N1=N2, then α=β÷n β=α×n, so α, β , n is set to satisfy the above equation.

(2) When the value of the up-down counter 41u is 0, the up-down counter 41u counts down and the count value becomes 0, and when the terminal T _D of the up-down counter 41u becomes L,
L is output from the terminal. However, under other conditions, an H signal is output to the terminal. However, at this time, - F/
Since the level of the terminal of F41r is H, the terminal Q level is H, but - F/F41
The level of the terminal Q of s remains at L, and the electromotor 30 continues to drive at high speed. (Figure 4 4).

(3) When the switch 22 is turned on (i) The electromotor 30 continues to be driven at high speed to perform sewing, and the switch 22 is turned on.
When ON, a single L pulse is output from switch 22, so - F/F41
The level of the terminal Q of f changes from L to H (at this time, the level of the terminal is H). Further, the output terminal of the inverter 41i changes from H to L.

However, OR gates 41j, 41l
The output terminal level of does not change because the level of one input terminal is H, so -
The level of the terminal Q of the SF/F 41s does not change, and the electromotor 30 continues to drive at high speed (FIG. 4, 5).

(ii) When the switch 22 is turned on, as mentioned in (3)(i) above, - terminal Q of F/F41f
changes from L to H, the level of one input terminal of the NAND gate 41h is inverted by the inverter 41i and becomes L.
Therefore, the level of the output terminal of the NAND gate 41h remains high, and the level of the output terminal of the NAND gate 41h remains high, and the level of the output terminal of the NAND gate 41h remains high.
The signal from 1c will no longer be read.

On the other hand, the level of the output terminal of the NAND gate 41g follows the output signal level of the sensor 37 since the level of one input terminal is H. Therefore, the switch 22
At the ON point, the down counter is switched to the up counter, and from then on, pulses from the sensor 37 are counted.

(iii) 96 stitches (=
108360-40/360) is being sewn. The count value of the up-down counter 41u is
-5 (=7-96/8).

(4) When the count value of the up-down counter 41u becomes 0, the up-down counter 41u counts up and down, and when the count value becomes -1 and the terminal T _U becomes L, the up-down counter 41u L is output from the terminal.
However, under conditions after that, H is output. At this time, since the level of one of the input terminals of the OR gate 41l is L, L is output from this output terminal.

Further, at this time, the output terminal level of the OR gate 41j does not change.

As a result, a single L pulse is output from the output terminal of the AND gate 41k, and therefore -
Terminal Q of F/F41s changes from L to H.

At this point, the electromotor 30 changes from high speed drive (first drive mode) to low speed drive (second drive mode).
drive mode) (Fig. 4, 6).

(5) When the electromotor 30 is driven at low speed and the protrusion 15 and the cam 13 come into contact during one revolution of the main shaft just before stopping, the hook portion 16 and the surface portion 2 of the engagement protrusion 20
0b is disengaged, and the lever 17 is moved by the spring 19.
The elastic force causes it to rotate counterclockwise. As a result, the stop switch 23
It is pressed and turned ON.

At this time, an L signal is input from the stop switch 23 to the drive control device 39, and the electromotor 3
0 stops at the position where the Hall element 37 detects the magnetism of the magnet 35 (FIG. 4, 7).

Note that when sewing starts in the middle of a cycle, such as re-sewing after a problem such as thread breakage occurs during sewing, the up-down counter 41u will not be displayed even after all the remaining stitches of the cycle have been formed. of
Although it may happen that the CRO does not output the L signal, the present invention prevents the sewing machine from operating at high speed during the operation time of the thread trimming knife. That is, if the L signal is not generated in the up-down counter 41u during high-speed driving, the motor 30 is switched from high-speed to low-speed driving at the same time as the output of the switch 22 changes from H to L.

Further, in this embodiment, the total number of stitches is 108, but if it is 56 or more stitches, the number of stitches in the low-speed drive section will always be 7 no matter how many stitches there are.

〔Effect of the invention〕

As explained above, in this invention, even if the total number of stitches in one cycle is changed by replacing the stitch number changing gear, the number of stitches in low speed drive (second drive mode) remains constant.
No adjustments required. Moreover, this has the effect that the time required for one sewing cycle can be shortened and work efficiency can be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a specific example of the speed switching circuit shown in FIG. 1,
FIG. 3 is a perspective view showing the connected state of the upper shaft 1 and the main cam 11, and FIG. 4 is a time chart. In the figure, 35 is a magnet, 37 is a sensor, 41
is a speed switching circuit, 41c is an octal counter, 41u
is an up-down counter with preset.

Claims (1)

[Claims] 1. A sewing machine comprising a main shaft that rotates in conjunction with a sewing machine motor, a main cam 11 that rotates at a reduced speed in conjunction with the main shaft, and a set of reduction gears that are replaceably arranged between the main shaft and the main cam. , in a cycle sewing machine in which the number of stitches in one sewing cycle can be changed by changing the gear ratio of the reduction gear, a first drive mode in which the main shaft of the sewing machine is driven at a first rotation speed; a second drive mode in which the main shaft of the sewing machine is driven at a slow rotation speed; a position sensing means 22 which generates a position signal in relation to a specific rotation angle β of the main cam;
A reference signal generating means 37 that generates pulses, a counter 41c that counts pulses from the reference signal generating means and outputs one pulse each time the value reaches a predetermined fixed value n, and a second drive mode. an up-down counter 41 in which the number of low-speed sewing stitches to be driven is set in advance, and which counts output pulses from the counter when counting down and pulses from the reference signal generating means when counting up;
u, switching means 41f for switching the counting operation of the up-down counter from down-counting to up-counting in response to a position signal from the position detection means, and switching means 41f for switching the counting operation of the up-down counter from down-counting to up-counting, and switching means 41f for switching the operation of the sewing machine when the up-count value of the up-down counter reaches zero. The control means 41s and 39 switch from the first drive mode to the second drive mode and stop driving the sewing machine when a preset number of low-speed stitches is reached, and the angle at which the main cam rotates during one sewing cycle. When α is the value obtained by subtracting the angle β from
A speed control device for a cycle sewing machine, characterized in that the speed control device is configured to have a speed of n.