JPS6055154B2 - Sewing machine tacking control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of the Invention The present invention relates to an electric sewing machine, and more particularly to a control device for controlling the start and end of sewing of an electric sewing machine.

A conventional electromagnetic clutch type electric sewing machine is shown in FIG.

The main body MA of the sewing machine is placed on a table TA, and the lower side thereof is an oil tank OB containing lubricant for the sewing machine.

A pulley PUL2 and a position detection mechanism are mounted on the sewing machine shaft, and the pulley PUL2 is driven by the pulley PUL1 via a belt VB. Pulley PULI is a transmission mechanism that includes a clutch and a brake...
is driven by a motor Mo. CB is a control unit to which commands are given by the operation of a foot switch FSW.

As shown in FIG.
A latch plate a movable in the axial direction is arranged between the CM and the brake friction plate URM, and this clutch plate CL
The pulley PULI is directly connected to B. Clutch plate CLB is activated by exciting clutch coil Cl.
The clutch friction plate CLM rotates, and the brake/friction plate BRM stops rotating by exciting the brake coil BR. The clutch coil Cl is controlled by a transistor Tl as shown in FIG. 3, and the transistor Ti is operated by a clutch signal CLS. Similarly, the brake coil BR is also controlled by the transistor T2,
The transistor T is operated by the brake signal BRS. The degree of coupling between the clutch friction plate LM and the clutch plate q can be changed by changing the value of the current flowing through the clutch coil Cl. The value of the current flowing through the clutch coil Cl can be changed by changing the magnitude of the clutch signal A3 or by turning the clutch signal 03 on and off. The rotational speed of the sewing machine main body MA changes depending on the degree of coupling between the clutch friction plate CLM and the clutch plate ClB. When the coupling is strongest, the clutch friction plate CLM and the clutch plate CLB rotate together and the maximum speed is obtained. On the other hand, if the coupling is loose, a slip occurs between the clutch friction plate CLM and the clutch plate CLB, and it is possible to reduce the rotational speed. In other words, clutch signal C
By changing the size of LS or by making it intermittent, it is possible to freely change the rotation speed of the sewing machine main body MA. Furthermore, if the rotational speed is higher than the scheduled speed, the brake can be used to decelerate and operate at a constant speed.
Generally, in the case of sewn items, tacking is performed at the beginning and end of sewing to prevent threads from fraying. The tacking stitch at the beginning of sewing is performed by moving forward a predetermined number of stitches and then moving backward a predetermined number of stitches, and the tacking stitch at the end of sewing is performed by moving backward a predetermined number of stitches and then moving forward a predetermined number of stitches. The tacking stitches are performed by a device installed in the sewing machine that reverses the stitch feed. This device is operated using a solenoid.
That is, a method is generally used in which a solenoid of a reversing device is energized to move the vehicle backward, and the solenoid is de-energized to move the vehicle forward. The number of stitches for tacking varies depending on the product to be sewn, but it is necessary for the quality of the product to have a consistent stitch pattern. Furthermore, securing stitches must be performed at high speed in order to improve work efficiency. Therefore, conventional methods have been used to limit the maximum speed to a certain value or rotate at a constant speed for the tacking stitch at the beginning of sewing, and to rotate at a constant speed for the tacking stitch at the end of sewing. is taken. Now, set the starting and ending tacking stitches at a constant rate! In the case of sewing at high speed, the sequence control of the starting tacking stitch will be explained based on FIG. 4 when the forward and backward movement of the starting tacking stitch and the backward and forward movement of the ending tacking stitch are set to 4 stitches. UPS is a signal that indicates the upper position of the sewing machine needle, DOWNS also indicates the lower position 1
BTS is a signal that excites the solenoid that operates the reversing device, and BTM indicates the movement of the solenoid. Also, CLS'' is a clutch signal that is operated by foot.
S'' indicates the clutch signal actually input to the transistor T1, and SPD indicates the number of rotations of the sewing machine.When sewing starts, the sewing machine needle is stopped at the upper position.The foot switch FSW shown in Fig. 1 When the foot switch FSW is fully pressed forward, the speed signal NH from the foot switch FSW will be the maximum speed ml.
command. As described above, when sewing the first tacking stitch at a constant intermediate speed, the clutch signal is set to NM by a control circuit (not shown) during the first tacking stitch. The speed of sewing machine MA is accelerated from a stopped state) and clutch signal C
It is accelerated to NM by LS'', rotates at intermediate speed NM until the initial locking stitch is completed, and clutch signal CLS'' instructs maximum speed NH, and then accelerates to maximum speed H.
Since the setting for the initial tacking stitch is 4 stitches, the lower position signal DO
When WNS appears 5 times, the four forward stitches are completed. In this case, the first lower position signal DOWNS only moves the sewing machine needle from the upper position to the lower position, and no stitches are created. When 4 stitches of forward movement are completed, the solenoid excitation signal BT is activated to perform 4 stitches of reverse movement next.
'Turn on M. The solenoid includes inductance, and the rise of the solenoid's excitation current is delayed, so the solenoid BTM begins to move with a delay of time Tll and takes time Tl to complete its movement. This means that I will be delayed. Also, after completing 4 stitches of reverse movement, the solenoid operation signal BTS
Similarly, when the solenoid BTM is turned off, the solenoid BTM returns to its original position after the delay times T2l and T22 have elapsed. For this reason, the actual stitches to be sewn do not become the desired stitches a as shown in FIG. 5, but instead become stitches b as shown in FIG. 5 due to the delay in the operation of the solenoid BT'M. In other words, the first backward stitch is a forward stitch because it takes time Tl2 for the solenoid BTM to complete its movement, and the delay time T2 for the return of the solenoid BTM. 1 after the solenoid operating signal BTS is turned off for
The needle will move backwards. For this reason, conventionally, if the solenoid operation signal is turned on when three forward stitches have been completed and turned off when seven stitches have been completed counting from the beginning of sewing, the forward movement is one stitch less than the stitch shown in b, so that the target a can be achieved. The stitches shown are obtained. In this way, the conventional electromagnetic clutch type electric sewing machine has about 4 stitches for tacking, and the tacking speed is A
IM is also 1000r. p. m~1500r. p. m, and there were no particular problems using the method described above.

However, when the number of tacking stitches increases to 7 to 8 stitches, a lot of time is required for tacking, and the tacking speed NM is reduced to 20
00~2500r. p. It is necessary to raise it to m. Therefore, the fixing stitch speed south was set at 2000 to 2500 r. p
．． If the value is increased to m, the number of stitches between the solenoid BTM operation and return delay times Tl2 and T22 will be one stitch or more, and since the delay times Tl2 and T22 vary depending on the voltage applied to the solenoid BTM, etc. The stitches were not aligned, leading to a decline in the quality of the sewn product. An object of the present invention is to provide a sewing machine stopper that can increase the number of stitches in tacking stitches and increase the tacking stitch speed without degrading the quality of sewn products by adjusting the ON/OFF timing of the solenoid of the reversing device. An object of the present invention is to provide a sewing control device.

In the present invention, the sewing machine rotation speed is set to 2000 to 2500 r. p. m
If it is raised to 0, the solenoid will be turned 0N and 0FF at a timing that matches the sewing machine's reverse rotation mechanism.

FIG. 6 shows an embodiment of the sewing machine tacking control device according to the present invention.

B terminal of one-shot multi 1, NAND circuit 2, N,
It is input to AND circuit 3.

The output terminal Q of the one-shot multi 1 is connected to another input terminal of the NAND circuit 2. This one-shot multi 1 is constructed so that its operating time can be varied by a variable resistor 4. The output of the N,AND circuit 2 is H→
The output Q of the flip-flop 5 is connected to the flip-flop 5 through a differentiation circuit that operates at the falling edge of the L level.
is connected to the base of the reversing device drive solenoid via a resistor. The other two inputs of the NAND circuit 3 are connected to the output of the inverter 6 through a differentiation circuit that operates with one input as the BTC signal and the other input with the rise from L to H level. , UPS signals are input. Now, when the reverse drive device solenoid drive signal BTS is input,
One shot multi 1, after a delay of ゛chu time, NAND
The output of the circuit 2 changes from H to L level, and is input to the set input S of the flip-flop 5 via the next-stage differentiation circuit.
The output Q becomes H, the transistor Tr turns 0N, the solenoid BTN operates, and the sewing machine creates stitches in reverse feed.

When the solenoid BTMf) is 0FF, only one stitch from the bottom to the bottom immediately before the set BTS turns OFF as shown in Figure 7 is BT.
Since C is being output, at the point where the upper position signal falls to H-+L at the end just before BTS (1) goes 0FF, all H level signals enter the inputs of the NAND circuit 3, and the output becomes L level. One shot multi 7 works.

The one-shot multi 7 has a time r! that can be varied with the variable resistor 4. ! After 7rF elapses, the output Q changes from H to L level, the next stage differentiating circuit operates, L is input to the reset input of flip-flop 9, Q is set to L level, and the transistor Tr
and solenoid BTM. Therefore,
BTS saw a fixed time delay, solenoid BTM turned 0N,
After a certain time delay from the end of the upper position immediately before the BTS turns OFF, the solenoid BTM can be turned OFF and a clean stitch can be obtained. FIG. 7 shows a sequence for controlling ON and OFF of the solenoid in the embodiment shown in FIG.

The sewing machine needle bar moves in a sin curve, where 0 is the bottom dead center of the needle bar, the top dead center of the needle bar is 180 degrees, and the bottom dead center of the needle bar is 360 degrees. The movement of the feed dog that actually feeds the cloth is 90 to 1
Between 80 and 80 degrees, it comes out above the throat plate surface and cloth feeding becomes possible, and between 270 and 3600 degrees, it goes down below the throat plate surface,
Perform cloth feeding and create stitches. When the reversing solenoid operates, the movement of the feed dog is reversed from forward feed to rear feed to perform tacking stitches. Therefore, if the mechanical suction and return of the solenoid are completely completed while the feed dog is below the throat plate surface, it is possible to obtain neatly aligned stitches, which greatly improves work efficiency and improves quality. You can measure your improvement. The upper position signal UPS is lower than the lower position signal DO between 180 and 270.
WNS outputs a signal between 0 and 901 at a predetermined position and at a predetermined angle.

BTS is the signal that excites the solenoid that operates the reversing device for the set number of stitches, and BTC is the signal that excites the solenoid that operates the reversing device for the set number of stitches.
The control signal BT'S'', which outputs the sewing solenoid for one stitch from bottom to bottom just before it is turned off, is the signal actually input to the transistor Tr.Now, as shown in Fig. 5, forward and backward movement is performed. When both are set to 4 stitches, the BTS outputs a signal at the 4th lower position counting from the start of sewing, and turns the output to 0FF at the 8th lower position.
The 1st stitch immediately before FF is 0N at the 7th lower position, and OFF at the 18th lower position, adjusting the 0FF timing of the solenoid without affecting the set stitch. In some cases, BTS'' is output with a delay of TN time after BT'S is output,
It turns OFF after a delay of Tp from the end of the next upper position after the seventh lower position. In other words, when actually aligning the stitches, taking into consideration the mechanical delay of the sewing machine, rotation speed, solenoid suction and return, when suctioning, it is useful for aligning the stitches of forward sewing, and when returning, BTSf ) If the solenoid is turned OFF after passing the upper position immediately before turning OFF, the solenoid will return to its original position at the 8th lower position, since the feed dog has already been lowered below the throat plate surface. The result is the same as turning the solenoid to 0FF, but since it takes longer for the next feed dog to come out to the top, the return time of the solenoid can be completely compensated for, so the sewing machine rotation speed during tie stitching can be increased. It can be made at high speed, and the resistance RI3 of the surge suction flywheel circuit when the solenoid drive circuit is 0FF is
This also makes it possible to use transistors with lower breakdown voltages. As explained above, according to the present invention, it is possible to increase the number of stitches in the tacking stitch and increase the tacking speed without degrading the quality of the sewn product.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing the configuration of a conventional electric sewing machine;
The figure is a partially enlarged view of the power transmission section of the electric sewing machine shown in FIG. 1, and FIG. 3 is a circuit diagram showing the drive section of a conventional electric sewing machine.
FIG. 4 is an explanatory sequence diagram of conventional reverse stitching, FIG. 5 is a diagram showing stitches, FIG. 6 is a circuit diagram of an embodiment according to the present invention, and FIG. 7 is an embodiment illustrated in FIG. 6. FIG. 1, 7... One shot multi, 2, 3...
...NAND circuit, 4...Variable resistor, 5...
...Flip-flop, 6...Inverter, Tr...Transistor, BTM...
solenoid.

Claims (1)

[Claims] 1 It has an electromagnetic brake and an electromagnetic clutch, the electromagnetic brake and the electromagnetic clutch are controlled by a foot switch, a solenoid is controlled by the foot switch, the reversing device is operated by this solenoid, and the sewing machine is A tacking device for a sewing machine equipped with a single variable speed electromagnetic clutch motor including means for generating a needle position signal, comprising: means for turning on the solenoid later than a set signal when the sewing machine is operated; 1. A sewing machine tacking control device comprising means for delaying turning off of the solenoid for a certain period of time based on a needle top position signal immediately before the solenoid is turned off in response to a signal for turning off the solenoid.