JPH0119916B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cloth feeding device for a sewing machine, and more particularly to a cloth feeding device directly driven by a pulse motor.

(Prior art) In the conventional electronically controlled zigzag sewing machine,
Generally, the needle bar vertical movement mechanism and the feed dog vertical movement mechanism for feeding the cloth are driven by a sewing machine motor, and the needle bar swing mechanism and the feed dog back and forth movement mechanism are driven by respective pulse motors.

Incidentally, recently, a zigzag sewing machine has been proposed in which the feed dog back-and-forth movement mechanism is directly driven by an independent pulse motor, thereby simplifying the drive system and accurately controlling the fabric feed based on the latest required fabric feed amount. ing.

For example, Japanese Patent Publication No. 57-30026 is equipped with a cloth feeding device that is driven independently of the upper shaft of the sewing machine, and detects the rotational phase of the upper shaft of the sewing machine with an upper shaft phase signal generator, By setting in advance so that the rotational phase of the feed shaft corresponds to the rotational phase of the upper shaft, and controlling the rotational phase of the feed shaft so that it corresponds to the preset rotational phase based on the upper shaft phase signal. , a cloth feeding device is described in which the end timing of cloth feeding is controlled to be constant.

(Problems to be Solved by the Invention) When the fabric feeding device of an electronically controlled zigzag sewing machine is driven by an independent pulse motor or the like in synchronization with the vertical movement of the needle bar, the following problems generally occur.

That is, the rotational speed of the sewing machine motor that drives the needle bar, that is, the sewing speed, is not constant but is set appropriately over a range from low speed to high speed, and the amount of cloth feed varies for each stitch of stitch formation. Due to reasons such as the number of drive pulses output to the pulse motor fluctuating and the pulse cycle of the drive pulses being constant, if the cloth feed start timing is set constant, the cloth feed end timing will not be constant and the balance will Due to the cooperation between the movement of the sewing machine and the cloth feeding movement, cloth feeding ends before the needle thread is sufficiently tightened, causing various problems in terms of sewing quality, such as the needle thread being caught between the processed fabric and the throat plate. Ru.

On the other hand, according to the cloth feeding device described in the above publication, although it is possible to appropriately control the end timing of cloth feeding, the upper shaft phase signal generator that detects the rotational phase of the upper shaft of the sewing machine and the feed shaft It is necessary to provide an electric signal means or the like for setting the rotational phase of the upper shaft to correspond to the rotational phase of the upper shaft, which causes problems such as the configuration of the device becoming complicated and the manufacturing cost increasing.

By the way, the speed of the sewing machine motor is feedback-controlled by the speed control means so that the actual speed of the sewing machine motor becomes the speed commanded (set) by the speed command means. When controlling the cloth feed based on the command signal from the speed command means, the following problem occurs.

In other words, when the command speed (set speed) for the sewing machine motor is changed, the command speed changes discontinuously (stepwise), whereas the actual speed of the sewing machine motor varies discontinuously due to the inertia of the motor and drive system. As a result, a response delay occurs because the command speed cannot be followed, and the difference between the command speed and the actual speed becomes extremely large for a short period of time immediately after the command speed is changed.

That is, as shown in FIG. 8 according to the embodiment of the present invention, a follow-up period is required from when the command speed is changed to when the command speed reaches the changed command speed, both during acceleration and deceleration. The length increases approximately in proportion to the amount of change in speed.

During the above follow-up period, the cloth feed device feeds the cloth based on a commanded speed that is different from the actual speed of the sewing machine motor, which causes a lag in the timing at which the cloth feed ends, causing various problems in terms of sewing quality. Ru.

(Means for Solving the Problem) A cloth feeding device for a sewing machine according to the present invention has a sewing needle that is driven by a sewing machine motor to perform vertical reciprocating motion, and transports a workpiece cloth in synchronization with the vertical reciprocating motion of the sewing needle. a cloth feeding member directly driven by a pulse motor; a speed command means for generating a command signal corresponding to the desired speed in order to change the speed of the sewing machine motor to a desired speed; and a speed control means for controlling the speed of the sewing machine motor, a detection means for detecting a change in the command signal is provided, and in response to the detection of the change in the command signal by the detection means, the actual speed of the sewing machine motor is A pseudo signal generating means is provided which generates a pseudo signal corresponding to the changed command signal according to the changed command signal, and the pulse A feed control means for determining the cycle of command pulses for the motor is provided.

Further, if necessary, the pseudo signal generating means may include:
It may be configured such that the amount of change in the pseudo signal varies depending on when the command signal increases and when it decreases.

(Function) According to the fabric feeding device of the sewing machine according to the present invention, as explained above, the sewing needle is driven by the sewing machine motor to make vertical and reciprocating movements, and the workpiece cloth is pulsed in time with the vertical and reciprocating movements of the sewing needle. The cloth is fed by a cloth feeding member linearly driven by a motor.

A command signal corresponding to the desired speed is output from the speed command means so that the speed of the sewing machine motor reaches a desired speed, and the speed of the sewing machine motor is controlled by the speed control means in accordance with the command signal.

The change in the command signal is detected by a detection means, and in response to the change in the command signal detected by the detection means, a pseudo signal corresponding to the actual speed of the sewing machine motor is generated in accordance with the changed command signal. is output by .

In the feed control means, the period of the command pulse of the pulse motor is determined according to the pseudo signal and the feed amount signal corresponding to the cloth feed amount by the cloth feed member, and the command pulse of the determined period is is output to the pulse motor to control cloth feeding.

In other words, when the speed of the sewing machine motor is low or the feed amount is small, the command pulse period is long, and when the sewing machine motor is high speed or the feed amount is large, the command pulse period is short. Even during periods when the speed changes from high to low or from high to low, the cycle of command pulses is determined based on a pseudo signal that corresponds to the actual speed of the sewing machine motor, thereby controlling the start timing and end timing of cloth feeding at a constant level. be done.

(Effects of the Invention) According to the cloth feeding device of the sewing machine according to the present invention, as explained above, when changing the speed of the sewing machine motor to a desired speed, the change in the command signal from the speed command means is detected by the detection means. A pseudo signal corresponding to the actual speed of the sewing machine is generated according to the changed command signal from the pseudo signal generating means, and the cloth feed pulse motor is controlled according to the pseudo signal and the feed amount signal for feeding the work cloth. Since the period of the command pulse is determined, even when controlling cloth feed based on the speed command signal from the speed command means, the start timing and end timing of cloth feeding can be kept constant regardless of the sewing machine speed. By controlling the sewing machine, it is possible to maintain a constant tightening operation of the upper thread by the thread take-up, thereby improving the quality of sewing.

Moreover, since the speed command means is effectively utilized for the above control without providing any special expensive detection device, the control system is not complicated and the manufacturing cost can be reduced.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

This embodiment relates to a cloth feeding device for an electronically controlled zigzag sewing machine in which a pulse motor directly drives the work cloth based on the commanded speed to the sewing machine motor, and the commanded speed of the sewing machine motor can be varied from low to high speed. When the command speed is selected and set, the command speed changes instantaneously and discontinuously, but the actual speed of the sewing machine motor changes from the time the command speed is changed due to the inertia of the sewing machine motor and drive system, as shown in Figure 8. It takes a follow-up period to reach the set command speed, and during that follow-up period (acceleration period if the sewing machine motor accelerates, deceleration period if it decelerates), the speed corresponds to the expected actual speed of the sewing machine motor. The purpose of this method is to find a pseudo speed at which the material moves, and then control the cloth feed based on that pseudo speed.

In the case of this zigzag sewing machine, the needle bar vertical movement mechanism and the thread take-up lever are driven by the sewing machine motor, while the cloth feed mechanism, which has a cloth feed roller that always partially protrudes from the top of the throat plate, uses pulse pulses. Directly driven by a motor.

Since the needle bar vertical movement mechanism and the thread take-up are the same as those of a normal electronically controlled zigzag sewing machine, a detailed explanation will be omitted. First, the cloth feeding device will be explained with reference to FIGS. 1 to 3.

A presser foot holder 2 is attached to the lower end of the presser foot 1 extending from the top of the arm of the sewing machine with a mounting screw 4, a presser foot 3 is detachably attached to the presser foot holder 2, and a needle is mounted in front of the presser foot 1. A sewing needle 5 attached to a rod (not shown) and a needle bar is provided.

Below the presser bar 1 and the needle bar, a roller type cloth feeding device as described below is provided in the bed section.

That is, at a position that corresponds to a slightly rearward side of the approximate center of the throat plate 6 and also corresponds to the presser foot 3 and the vicinity of the left side thereof, there is a groove 3 that is directly below the throat plate 6 and is oriented in a direction perpendicular to the cloth feeding direction. Book roller shafts 7a, 7b, 7c
These roller shafts 7a, 7b, and 7c are arranged parallel to each other at appropriate intervals in the front and back, and these roller shafts 7a, 7b, and 7c are pivotally supported by brackets 8 in the bed portion B at both ends.

Directly below the presser foot 3, a pair of rollers 1 located on both sides of the needle hole 9 are mounted on the front roller shaft 7a.
0 is fixed, and four rollers 10 are fixed to each of the two roller shafts 7b and 7c on the rear side, and these rollers 10 are slightly moved from the opening of the throat plate 6 onto the throat plate 6. The work cloth is protruded from the presser foot 3, and by rotating the rollers 10 while holding the work cloth between the rollers 10 and the presser foot 3, the cloth can be fed.

A cloth feed pulse motor 11 for rotationally driving the rollers 10 of the roller shafts 7a, 7b, 7c to feed the cloth is attached to the bracket 12 of the bed portion B so as to face in the same direction as the roller shafts 7a, 7b, 7c.
A driven gear 14 that meshes with the drive gear 13 of the motor shaft 11a is pivotally supported by the brackets 8 and 12, and is connected to a pulley 15 provided on the support shaft of the driven gear 14 and pulleys 16a and 16c of the roller shafts 7a and 7c. The timing belt 17A is then hooked up, and the timing belt 1 is attached to the pulley 15 and the pulleys 16b, 16c of the roller shafts 7b, 7c.
7B is hung, and these timing belts 17
A, 17B are guided by a pair of idle pulleys 18, and the tension of the timing belt 17B is adjusted by a tension pulley 19. Both timing belts 17A, 17B are guided by the pulse motor 11.
All the rollers 10 of the roller shafts 7a, 7b, 7c can be rotationally driven through the roller shafts 7a, 7b, 7c.

Note that fine teeth are formed on the outer peripheral surface of the roller 10 to prevent it from slipping on the work cloth.

In the figure, reference numeral 20 is a horizontal hook that accommodates a bobbin thread bobbin, and reference numeral 21 is a sliding plate.

However, instead of the ten rollers 10, a flexible or bendable belt made of metal or synthetic resin with excellent wear resistance is provided over the range of these rollers 10, and this belt is connected to the pulse motor 1.
1 may be configured to feed the work cloth, or the feed dog provided in an existing sewing machine may be configured to be driven forward and backward and vertically by the pulse motor 11. .

In short, the cloth feeding device has a pulse motor 1
1, it is sufficient if it is directly driven.

Next, a control device for controlling the sewing machine motor, cloth feed pulse motor 11, needle bar swing pulse motor, etc. will be explained based on the block diagram of FIG. 4.

A speed command device that commands the speed of the sewing machine motor 30 to a desired speed includes a speed setting device 32 and an A/D
It is configured with a converter 32a and outputs a speed command signal to a speed control device to be described later.

The speed setting device 32 selects and sets the rotational speed of the sewing machine motor 30 so as to achieve a desired sewing speed, and is composed of, for example, a potentiometer.
The voltage signal is A/D converted by the A/D converter 32a and then output to the CPU 33.

The speed control device that controls the speed of the sewing machine motor 30 includes a speed detector 31, a CPU 33 (central processing unit), a ROM 34 (read-only memory), a RAM 35 (random access memory), and a sewing machine motor drive circuit. Consists of 36,
Feedback control is performed so that the rotation speed of the sewing machine motor 30 becomes the command speed commanded by the speed command device.

The speed detector 31 detects the rotational speed of the output shaft and upper shaft of the sewing machine motor 30 using, for example, an electromagnetic pickup sensor, and the detection signal is A/D converted by an A/D converter (not shown). Rear CPU3
Output to 3.

The ROM 34 stores in advance a control program for controlling the sewing machine motor 30 based on the actual speed signal output from the speed detector 31 and the speed command signal output from the speed command device. Control that receives the above-mentioned speed signals and processes them based on a control program, temporarily stores signals and data read from the ROM 34 or data of the calculation results in the RAM 35 as needed, and controls the sewing machine motor 30. The signal is output to the sewing machine motor drive circuit 36. The sewing machine motor drive circuit 36 outputs a drive current corresponding to the control signal to the sewing machine motor 30.

As mentioned above, when the sewing machine is in operation, the sewing machine motor 3
Feedback control is always performed so that the zero speed becomes the command speed, and this speed control is similar to existing electronically controlled zigzag sewing machines.

Next, a control device that controls the cloth feed pulse motor 11 and the needle bar swing pulse motor 38 includes a drive timing detection sensor 39, a stitch pattern selection device 40, a stitch pattern data memory 41, and a CPU 4.
2 (central processing unit), ROM 43 (read-only memory), RAM 44 (random access memory), and cloth feed motor drive circuit 45
, a needle bar swing motor drive circuit 46, and the like.

The drive timing detection sensor 39 detects when the needle bar reaches its highest position in each cycle of vertical movement of the needle bar using a limit switch, a photo interrupter, etc., and its drive timing signal is output to the CPU 42. .

The stitch pattern data memory 41 is a memory that stores data regarding the cloth feed amount and needle bar swing amount (needle swing amount) of each sewing operation for each stitch pattern in one group of addresses, The stitch pattern selection device 40 outputs a pattern selection signal to the CPU 42 in order to select each stitch pattern stored in the stitch pattern data memory 41 by code number or the like.

The ROM 43 includes a cloth feed pulse motor 11.
and the needle bar swing pulse motor 38. When the CPU 42 receives a stitch pattern selection signal, the CPU 42 stores each data of a group of stitch pattern data corresponding to the stitch pattern selection signal into the stitch pattern data memory. 41 and performs arithmetic processing, and temporarily stores the data and signals in the RAM 44 as necessary, and sends each series of control signals to the cloth feed motor drive circuit 45 at each predetermined timing determined based on the drive timing signal. and the needle bar swing motor drive circuit 46, respectively.

The cloth feed motor drive circuit 45 and the needle bar swing motor drive circuit 46 output each series of drive pulses corresponding to each series of control signals to the cloth feed pulse motor 11 and the needle bar swing pulse motor 38, respectively. ,
The stitch pattern selected by the stitch pattern selection device 40 will be sewn.

Among the controls for sewing the above-mentioned stitch pattern, the controls other than the cloth feed control for controlling the cloth feed pulse motor 11, which will be described later, are the same as those of existing electronically controlled zigzag sewing machines.

Here, according to the command speed of the sewing machine motor 30 and the feed amount of the workpiece cloth, the cloth feed pulse motor 11
Cloth feeding control that makes the start and end timing of cloth feeding constant by controlling the pulse period of the drive pulse output to will be described in detail below.

Fig. 5 shows the vertical movement curve of the sewing needle 5 and the vertical movement curve of the thread take-up, which moves up and down in synchronization with the vertical movement of the sewing needle 5. Cloth feeding is performed at least after the sewing needle 5 reaches its highest point. It is desirable to do so, and it is necessary to complete the cloth feeding by the time when the descending sewing needle 5 pierces and inserts the workpiece cloth. It is most desirable to carry out cloth feeding after the needle thread has been sufficiently tightened by the thread take-up, but the period from when the thread take-up reaches its maximum point to when the cloth coincides is relatively short, so it is especially When the speed of the sewing machine motor 30 is high, the above period becomes very short and it may be difficult to carry out cloth feeding within this period. Assume that cloth feeding is performed.

In this case, the timing to start cloth feeding is determined by the drive timing signal, and the thread take-up is driven by the sewing machine motor 30 in conjunction with the vertical movement of the sewing needle 5, so the timing of the cloth matching point, that is, the end of cloth feeding. The timing is calculated according to a predetermined program based on the rotational speed of the sewing machine motor 30 and the drive timing signal.

FIGS. 6 and 7 illustrate the sewing needle vertical movement curve and drive pulse when controlling the feed as described above, and the rotation speed of the sewing machine motor 30 is
This is the case at 400rpm and 800rpm. Assuming that the number of driving pulses is the same, when the speed is low as shown in Fig. 6, the driving pulse period becomes large, and when the speed is high as shown in Fig. 7, the driving pulse period becomes small.
The start timing and end timing of cloth feeding are constant.

However, since the cloth feed control described above is executed based on the commanded speed of the sewing machine motor 30, no particular problem occurs as long as the commanded speed of the sewing machine motor 30 and the actual speed match. As described above, during the transient follow-up period after changing the commanded speed, the actual speed does not match the commanded speed, and the actual speed gradually approaches the commanded speed.

Therefore, during the above-mentioned transient follow-up period, as shown in FIG. determining the pulse period;

In other words, the start timing of cloth feeding is when the sewing needle reaches the highest point and the drive timing signal is input, so the command speed when this drive timing signal is input and the time when the previous drive timing signal is input are determined. The speed difference △V between the similar speed and the stored similar speed is calculated, and when the speed difference △V is positive, a constant B is added to the previous similar speed and stored as the current pseudo speed, and the current similar speed is calculated. to determine the pulse period.

When the speed difference ΔV is negative, the pulse period is determined using a pseudo speed obtained by subtracting the constant C from the previous similar speed.

The above constant B is calculated based on the expected increase in the actual speed between the input of the previous drive timing signal and the input of the current drive timing signal when the command speed of the sewing machine motor 30 is changed to a higher speed than the current one. is set to the corresponding value.

The constant C corresponds to the expected decrease in the actual speed between the input of the previous drive timing signal and the input of the current drive timing signal when the command speed of the sewing machine motor 30 is changed to a lower speed than the current speed. set to the value.

However, when the command speed of the sewing machine motor 30 is increased or decreased, although the rate of increase and decrease of the actual speed shows a constant tendency, the interval of the drive timing signal changes depending on the actual speed of the sewing machine motor 30, so the above-mentioned The speed increment B and the speed decrease C may be calculated and determined based on similar speeds of the sewing machine motor 30.

In this way, the current pseudo speed is obtained by adding the speed increment B to the previous similar speed, and by sequentially adding the speed increments B, a pseudo speed that approximately approximates the actual speed can be obtained even during a transient tracking period. The pulse period of the cloth feed pulse motor 11 can be determined using the following.

Of course, this also applies to the case where the sewing machine motor 30 is decelerated.

The cloth feed control routine will be explained below using the flowcharts shown in FIGS. 9 and 10.
The control program for this cloth feed control is stored in ROM4 in advance.
The input is stored in 3.

In Fig. 9, when the sewing operation starts,
Control is started in the CPU 42, and step S
1, the drive timing signal is initialized, and in step S2, it is determined whether or not a drive timing signal has been input from the drive timing detection sensor 39. If the drive timing signal has not been input, the process returns to step S2, and the drive timing signal is input. Then, the process moves to step S3, where a speed (command value) representing the command speed of the sewing machine motor 30 is read from the speed command device.

Next, in step S4, the previous similar speed is stored as speed V1, in step S5, the speed read value is stored as speed V2, and in step S6, the speed difference ΔV between speed V2 and speed V1 is calculated.

Then, in step S7, it is determined whether the absolute value of the speed difference ΔV is less than or equal to a constant A. If it is less than or equal to the constant A, the process moves to step S11, and if it is larger than the constant A, the process moves to step S8.

The above-mentioned constant A is a range of speed fluctuations that is permissible in terms of sewing quality caused by minute fluctuations in the power supply voltage.

Next, in step S8, it is determined whether the speed difference ΔV is positive or not. If it is positive, the process moves to step S9, and if it is negative, the process moves to step S10.
In step S9, the value obtained by adding the constant B to the speed V1 is set as the current similar speed, and the process moves from step S9 to step S11.

Also, in step 10, a constant C is subtracted from the previous speed V1 to obtain the current similar speed, and step S
10, the process moves to step S11.

Next, in step S11, the pattern data for each sewing operation of the stitch pattern corresponding to the pattern selection signal is read from the stitch pattern data memory 41, and in step S12, the pattern data for each sewing operation of the stitch pattern corresponding to the pattern selection signal is read. The number of driving pulses is temporarily stored in the RAM 44.

In step S13, the internal timer in the CPU 42 is initialized (reset), and the internal timer interrupt processing routine shown in FIG. 10 is started on the condition that the internal timer is reset.

When this interrupt processing is started, step S2
At 0, the feeding end time is calculated based on the current similar speed, the cloth feeding time is calculated, and the period of the driving pulse is calculated based on this cloth feeding time and the number of driving pulses.

Next, in step S21, when the drive pulse period is set in the internal timer, the internal timer outputs a trigger signal for each drive pulse period.

In step S22, a control signal is output from the CPU 42 to the cloth feed motor drive circuit 45 in synchronization with the trigger signal from the internal timer, and the cloth feed pulse motor 11 is driven by one step.

Next, in step S23, it is determined whether or not the driving for the number of driving pulses has been completed. If not, the process returns to S22 and step S22 is repeated, and the cloth feed pulse motor 11 is moved by the number of driving pulses.
is driven and the work cloth is fed by the feed amount for the next sewing operation, the process moves from step S23 to step S24, and in step S24, the timer interrupt is masked and the interrupt processing is completed, as shown in FIG. Return to main routine. After this return, in step S14, the timer interrupt mask is canceled to enable the next interrupt.
The process moves from step S14 to step S2, and the same process is repeated thereafter.

Further, in the above embodiment, the routine shown in FIG. 10 is executed by interrupt processing, but this routine may be incorporated into the routine shown in FIG. 9.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a partial longitudinal sectional front view of the presser foot etc. on the bed part of an electronically controlled zigzag sewing machine and the cloth feeding device provided in the bed part, and FIG. 3 is a plan view of the cloth feeding device, FIG. 4 is a block diagram of the control device of the sewing machine, and FIG. 5 is a diagram showing part of the vertical movement curve of the lever and the vertical movement curve of the sewing needle. , Fig. 6 and Fig. 7 are explanatory diagrams showing part of the sewing needle vertical movement curve and drive pulses at low speed and high speed, respectively, and Fig. 8 shows the command speed and actual speed when changing the command speed of the sewing machine motor. and an explanatory diagram of pseudo speed,
9 and 10 are schematic flowcharts of a control routine for cloth feeding control. 5... Sewing needle, 10... Roller, 11... Cloth feed pulse motor, 31... Speed detector, 32... Speed setting device, 32a... A/D converter, 33... CPU, 34
...ROM, 35...RAM, 36...Sewing machine motor drive circuit, 39...Drive timing detection sensor, 40
... Stitch pattern selection device, 41... Stitch pattern data memory, 42... CPU, 43... ROM, 44... RAM,
45...Cloth feed motor drive circuit.

Claims (1)

[Scope of Claims] 1. A sewing needle that is driven by a sewing machine motor to perform vertical reciprocating motion, and a cloth feeding member that is directly driven by a pulse motor to transport the work cloth in synchronization with the vertical reciprocating motion of the sewing needle. and speed command means for generating a command signal corresponding to the desired speed in order to change the speed of the sewing machine motor to a desired speed, and speed control means for controlling the speed of the sewing machine motor in accordance with the command signal. a detection means for detecting a change in the command signal;
pseudo signal generating means for generating a pseudo signal corresponding to the actual speed of the sewing machine motor in accordance with the changed command signal in response to detection of a change in the command signal by the detection means; and the pseudo signal and the cloth feeding member. A cloth feeding device for a sewing machine, comprising: a feed control means for determining a command pulse cycle of the pulse motor according to a feed amount signal corresponding to a feed amount of a work cloth. 2. Fabric feed for a sewing machine according to claim 1, wherein the pseudo signal generating means is configured to vary the amount of change in the pseudo signal depending on when the command signal increases and when it decreases. Device.