JPS6223591B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed setting device for an industrial sewing machine.

In recent years, in the field of sewing machine control, products that make full use of electronic components such as microcomputers (hereinafter referred to as microcomputers), memory, and ICs have been commercialized, and in the field of speed control in particular, products that make full use of the electronic components mentioned above are also being commercialized. A so-called digital control method has also begun to be developed, and the development of control technology is remarkable.

However, complete digitalization of the speed control section using a microcomputer is accompanied by various difficulties and has not yet been realized, and it can be said that the current mainstream is still analog control.

Conventionally, analog control has been the mainstream for speed control as described above, and therefore, as a sewing machine speed setting device, the most desirable configuration is one that outputs an analog value, and has actually been adopted.

The present invention is intended to provide a sewing machine speed setting device that is simplest in configuration, inexpensive, and highly reliable when configured as a digital speed control system centered on control elements such as a microcomputer.

The basic speed control for industrial sewing machines is variable speed control according to the amount of pedal depression. When the pedal is in the neutral position, the sewing machine is stopped, and when the pedal is pressed lightly, it starts rotating at a low speed, and when the pedal is pressed deeply, the speed increases.Variable speed control is generally used. In addition to the variable speed control described above, modern highly automated industrial sewing machines require fairly strictly fixed speeds in order to perform various functions.

The first is a low speed setting for thread trimming control. The thread cutting operation is normally carried out during the half revolution leading to the needle down position, and the speed at this time must be kept at a strictly low speed, which varies depending on the sewing machine.

The second is an intermediate speed setting for controlling reverse stitching. At the beginning and end of sewing, it is necessary to automatically perform backstitching to prevent fraying, and the speed at that time must be maintained at an intermediate speed regardless of the pedal position.

The third is the maximum speed setting when the pedal is fully depressed, which requires a selectable function depending on the skill level of the operator and the type of product to be sewn.

These low speed, intermediate speed, and maximum speed all require adjustable specified speeds that are independent of the pel position depending on the sewing machine function, and the present invention provides these speed settings at low cost and with high reliability. That is.

The present invention will be explained below with reference to the drawings. Fig. 1 shows a basic block diagram of the present invention, in which 1 is a speed setting mechanism, 2 is a speed control mechanism, 3 is a motor, and 4 is a clutch/brake coil, driver, lining, etc. as seen in an electromagnetic clutch/brake motor. 5 is a sewing machine, and 6 is a speed detection mechanism attached to the sewing machine 5 for detecting the speed of the sewing machine.

The operation is performed as follows. First, when a sewing machine pedal (not shown) is depressed, the speed setting mechanism 1 outputs a speed _{setting signal V S based} on the amount of pedal depression. The rotational force of 3 is transmitted to the sewing machine 5, and the sewing machine 5 starts rotating. Further, a speed detection mechanism 6 linked to the sewing machine 5 detects the rotation speed of the sewing machine 5 and outputs a speed detection signal V _F , and when this speed detection signal V _F is balanced with the speed setting signal V _S The sewing machine 5 is operated at a speed of .

Here, FIG. 2 shows a block diagram that is a more specific form of the basic block diagram mentioned above.

In Figure 2, 7 is a sewing machine pedal (not shown)
8 is a microcomputer, and in this embodiment, it is a 4-bit 1-chip microcomputer that includes memory, I/O, etc. It shows the case. Reference numerals 9 and 10 indicate drivers for the clutch coil 11 and brake coil 12, which act to transmit the rotational force of the motor 3 to the sewing machine 5 via the magnetic circuit, lining, and belt, as described above. Further, a frequency generator 13 is fixed to the sewing machine shaft (not shown) of the sewing machine 5, and generates a pulse train having a frequency corresponding to the rotational speed of the sewing machine. The waveform shaping circuit 14 is composed of a Schmitt trigger circuit, and shapes the pulse train into a square wave. The low speed setting element 15, the intermediate speed setting element 16, and the maximum speed setting element 17 are each constituted by a pulse generator.

The operation of the system configured as described above is performed as follows.

First, as mentioned above, when the sewing machine pel is depressed, a speed setting signal V _S corresponding to the amount of depression
is input from the variable speed setting element 7 to the microcomputer 8 as 4-bit digital data, and the microcomputer 8 confirms that the sewing machine pedal has been depressed.
The clutch coil 11 is excited via the driver 9, and the rotational force of the motor 3 is transmitted to the sewing machine 5 via the belt as described above, and the sewing machine 5 is started.

When the sewing machine 5 is started in this manner, the frequency generator 13 attached to the sewing machine shaft generates a pulse signal having a period according to the rotational speed of the sewing machine, and the waveform is further shaped into a square wave by the waveform shaping circuit 14. , a pulse train V _F having a period indicative of the sewing machine speed is fed back to the microcomputer 8.

If the speed increases too much with respect to the speed setting signal V _S , the brake coil 12 is energized via the driver 10, and the sewing machine 5 is decelerated. By controlling the excitation, the rotational speed of the sewing machine is maintained in accordance with the speed setting signal.

Here, the speed control function based on the arithmetic expression of the microcomputer 8 will be described below with reference to FIGS. 3 to 5.

In the case of minimum speed operation, the microcomputer performs calculations according to the following calculation formula, as shown in FIG.

T _BC =aT _F -b (1) However, a: gain constant b: constant T _BC : If the result is positive, it indicates the clutch-on time, and if it is negative, it indicates the brake-on time.

T _F ; Pulse train period of the frequency generator First, the pulse train section from the frequency generator 13 is actually measured, and after calculating according to equation (1), the time obtained by the calculation in the next pulse train section |T _B.C.
| only acts to excite the clutch or brake coil, and speed control is achieved by repeating this in sequential order. Normally, in stable operation where the sewing machine load is constant, the sewing machine is driven at point a in the figure.
The state of the current flowing through the clutch coil 11 at this time is shown by a solid line in FIG.

Here, the gain constant a in equation (1) determines the gain of the system. That is, when a becomes large, even a slight variation in the period T _F causes a large change in the engagement ratio of the clutch (or brake) coil, and therefore the gain of the system increases.

Further, the speed can be adjusted by changing the size of the constant b. That is, when |b| becomes smaller (as shown by the broken line in Figure 3), the engagement ratio of the clutch increases and attempts to move to point β, but at the same time the speed increases and the clutch engagement ratio decreases to a predetermined value. The operation is performed so as to stabilize at a point. The state of the current flowing through the clutch coil 11 at this time is shown by the broken line in FIG.

In this way, constant speed control is performed at the lowest speed. On the other hand, the medium speed to high speed operation is performed by dividing the pulse train of the frequency generator 13 by the software of the microcomputer 8. In other words, if the minimum speed obtained as described above is _S1 , the frequency division ratio is 1/N, and the gain of the system is high enough to ignore sewing machine load fluctuations due to changes in rotational speed, then the speed S will decrease. It is expressed by the formula.

S=NS ₁ ......(2) (However, N=1, 2, 3, ......) Here, according to the speed setting signal V _S from the variable speed setting element 7 in FIG. By switching N, the speed S can be switched stepwise. That is, the speed setting signal V _S is 4
When the bit data is input to the microcomputer 8, the microcomputer 8 converts the above 4-bit data into (2) according to the contents preset in the internal ROM.
It functions to convert into N in the equation and perform frequency division.
Therefore, it can be said that by appropriately configuring the ROM, various speed curves such as those shown in "" or "" in FIG. 5 can be selected.

The above is the normal control according to the speed setting signal V _S from the variable feed setting element 7.
Various setting elements in the figure will be described below with reference to FIG. 2.

The low speed setting element 15, the intermediate speed setting element 16, and the maximum speed setting element 17 are each constituted by a pulse generator as described later, and their operations are performed as follows.

First, from the low speed setting element 15, the low speed setting signal V
Microcontroller 8 as _L is a pulse signal with variable width
, the microcomputer 8 actually measures the "H" section of the pulse signal V _L and converts it into a numerical value between "0\" and "15" using a program to be described later. The data of the low speed setting signal V _L is converted according to the built-in ROM table configured to obtain a predetermined value corresponding to the value of "15", and the data after the conversion is converted into the constant of the formula (1). b and performs arithmetic processing.In other words, the low speed setting element 15 can perform 16 steps of switching such as moving the stable point a to γ in FIG. The minimum speed of the sewing machine can be changed in the following manner.

Next, when the intermediate speed setting signal V _M is inputted to the microcomputer 8 from the intermediate speed setting element 16, the "H" time of the pulse signal V _M is actually measured in the same way as above, and the "0\" After being converted to a numerical value of ~ “15” and further converted to a predetermined numerical value according to the built-in ROM table, the converted data is converted to the above-mentioned
It is given as the frequency division number N in equation (2), and therefore acts to change the intermediate speed. Therefore, it is possible to switch between 16 intermediate speeds according to the input data. Here, whether to adopt the variable speed setting signal V _S from the variable speed setting element 7 or the intermediate speed setting signal V _M is separately determined by the microcomputer 8 according to the sewing process of the sewing machine. Further, if the intermediate speed is not fixed and the converted data of the variable speed setting signal V _S is smaller than the converted data of the intermediate speed setting signal V _M , the variable speed setting signal V _S is enabled. It is also possible to configure it as follows. That is, it can be said that it is possible to command only the upper limit intermediate speed from the intermediate speed setting element 16.

Next, when the maximum speed setting signal V _H is input from the maximum speed setting element 17 to the microcomputer 8, the "H" time of the pulse signal V _H is actually measured in the same manner as described above, and the "0\" ~ After being converted to a numerical value of “15” and further converted to a predetermined numerical value according to a built-in ROM table different from the above, the converted data is divided by the frequency division number in the above formula (2). N, therefore, this acts to change the maximum speed. By keeping the data after the conversion sufficiently large, it becomes possible to switch the maximum speed in 16 steps, as shown by the broken line in FIG.

As described above, variable speed control is performed according to the amount of depression of the sewing machine pedal by the variable speed setting element 7, or speed control is performed according to commands from various speed setting elements.

Here, the variable speed setting element 7 detects the amount of depression of the sewing machine pedal and converts it into a 4-bit variable speed setting signal, and its configuration is firstly a rotary encoder with several bit switches, or a rotary encoder with several sets of switches. A light-emitting/light-receiving element and a shielding plate that passes between them and changes the signal from the light-receiving element according to the movement of the sewing machine pedal, or a magnet that moves according to the movement of the sewing machine pedal, Various configurations are conceivable, such as one in which the amount of movement is detected by a magnetically sensitive element and further converted into a several-bit signal by an A/D conversion circuit.

Further, a more specific configuration example of the low speed setting element 15, intermediate speed setting element 16 and maximum speed setting element 17 is shown in FIG. 7, the waveform of the output pulse is shown in FIG. 8, and the actual measurement of the above output pulse is shown in FIG. The flowchart is shown in FIG. 9, and the explanation will be added below according to the same figure.

In Fig. 7, 18 indicates an oscillator, which is composed of an IC, and has a variable resistor R _A , a fixed resistor R _B , and a capacitor C externally connected to its input terminal, and oscillates from its output terminal "UT". The configuration is such that pulses are output and input to input ports i~ _i2 of the microcomputer 8.

The output pulse signal waveform from the oscillator 18 is shown in FIG.
The time "T _h " can be changed by the value of the variable resistor R _A as shown in the following equation.

T _h ∝ (R _A + R _B )C ......(3) That is, if the variable resistor R _A is increased according to the above equation (3), the above "T _b " will become longer, and if it is reversed, it will become smaller. It can be said that the "H" time of the pulse signal can be adjusted.

When the pulse signals set by the variable resistor R _A from each of the speed setting elements are input to the input ports i〓 to _i2 of the microcomputer 8, the microcomputer 8
Selected the pulse signal from the necessary speed setting element from among the speed setting elements mentioned above, measured the time of the "H" section of the pulse signal in particular, and changed it to a value between "0\" and "15". After that, the processing described above will be performed.

Here, the conversion of the pulse signal to "0\" to "15" is performed as shown in the flowchart of FIG. That is, first, at 19, the counter C of the internal RAM is cleared, at 20, the edge of the pulse signal from "L" to "H" is detected, and at 21, the delay time is determined by an internal timer configured by software. The counter C is incremented every `` <sub>TD</sub> '', and when the pulse signal becomes ``L'' or when the counter reaches ``15'', the pulse signal changes from 0\ to 15. Finish converting to .

As described above, the pulse signals from each speed setting element are converted into numerical values from "0\" to "15", and further converted into necessary speed setting data according to the built-in ROM table as described above. It will be processed.

The operation example shown in the above flowchart is one embodiment of the present invention, and the pulse signal from the oscillator may change from "L" to "H" or from "H" to "L" during a certain period of time. The object of the present invention can be easily achieved by adopting a program configuration of the microcomputer that counts the switching points of , and allows the counted value to range from "0\" to "15".
Furthermore, a configuration example different from the above embodiment is shown in FIGS. 10 and 11, and will be described below with reference to the drawings.

In FIG. 10, 22 represents a monostable multivibrator, which is composed of an IC, and is externally connected to a fixed capacitor C and a variable resistor _RA .

The operation is performed as follows. first. The output ports of microcomputer 8 ~ ₂ are normally “L”,
For example, when reading the signal from the low speed setting element 15, the output port of the microcomputer 8 is set to "H", and the edge input from "L" to "H" causes the monostable multivibrator 22 to drop below the NT terminal. A pulse signal V _L of "H" for a time "T _h " according to the formula is output as shown in FIG.

T _h ∝ R _A C ...... (4) The microcomputer 8 measures the "T _h " time of the above pulse signal V _L from the input port i by 21 in FIG. 9, and calculates it from "0\" to "15 After converting it into a numerical value, it is then converted into valid data and processed using the built-in ROM table as described above.

The same goes for reading signals from other speed setting elements, and the speed is set according to the pulse width "T _h adjusted by the variable resistor R _A.

Although the above embodiment describes the case where a 4-bit microcontroller is used, it goes without saying that 8-bit microcontroller is used.
The present invention is also effective when using other microcomputers such as 16-bit and 16-bit microcomputers. In addition, the ROM part, which is a means for converting input data to the microcomputer from the various setting elements into valid data, is not built-in but is provided outside the microcomputer, or the frequency dividing means is provided outside the microcomputer, etc. The present invention is also effective.

As is clear from the above explanation, according to the present invention, digital control by a control element such as a microcomputer is performed with a very simple configuration, and therefore reliability is improved and a low cost product is realized. The effect is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of the present invention.
Fig. 2 is a detailed block diagram showing the configuration of the present invention, Fig. 3 is a diagram showing the principle of speed control, Fig. 4 is a diagram showing the clutch current waveform in constant speed operation, and Fig. 5 is a diagram showing the clutch current waveform in constant speed operation.
The figure shows an example of the configuration of a curve of sewing machine rotational speed against the amount of sewing machine pedal depression, Figure 6 shows an example of setting the maximum speed using maximum speed setting elements, and Figure 7 shows a specific example of the configuration of various speed setting elements. Figure 8 is a diagram showing the output pulse signal waveforms of the various speed setting elements, Figure 9 is a diagram showing a flowchart of actual measurement of the time width of the output pulse signal, and Figure 10 is a diagram showing the different speed setting elements. Block diagram showing a specific example of the configuration, Part 1
FIG. 1 is a diagram showing the output pulse signal waveform of each speed setting element. 1...Speed setting mechanism, 2...Speed control mechanism, 3
...Motor, 4...Drive mechanism, 5...Sewing machine, 6
... Speed detection mechanism, 7 ... Variable speed setting element, 8
... Microcomputer, 15 ... Low speed setting element, 16 ... Intermediate speed setting element, 17 ... Maximum speed setting element.

Claims (1)

[Claims] 1. A drive mechanism that drives a sewing machine by a motor;
a speed detection mechanism that detects the speed of the sewing machine shaft; a speed setting mechanism that commands the speed of the sewing machine shaft; and a speed that controls the rotation of the sewing machine shaft by comparing the output of the speed detection mechanism and the output of the speed setting mechanism. and a control mechanism, the speed detection mechanism is configured with a frequency generator that generates a plurality of equally spaced pulses for each revolution of the sewing machine or motor, and the speed setting mechanism corresponds to the movement of the sewing machine pedal. The speed control mechanism includes a variable speed setting element that outputs a variable speed signal, and a prescribed speed setting element that includes a pulse generator that outputs a pulse signal, and the speed control mechanism is configured to set a specific setting range of the variable speed signal according to the pulse signal. A sewing machine speed setting device that regulates the speed according to the width or cycle of the sewing machine. 2. The sewing machine speed setting device according to claim 1, wherein the minimum speed setting that can be set by the variable speed setting element can be adjusted by the specified speed setting element. 3. The sewing machine speed setting device according to claim 1, wherein the maximum speed setting that can be set using the variable speed setting element can be adjusted using the specified speed setting element. 4. The sewing machine speed setting device according to claim 1, wherein an intermediate speed setting that can be set using the variable speed setting element can be adjusted using the specified speed setting element. 5. The sewing machine speed setting device according to claim 1, wherein the prescribed speed setting element including the pulse generator has an oscillator. 6. The sewing machine speed setting device according to claim 1, wherein the prescribed speed setting element including the pulse generator has a monostable multivibrator. 7. The sewing machine speed setting device according to claim 5, wherein the output of the oscillator is input to a microcomputer forming a part of the speed control mechanism. 8. Claim 6, characterized in that the output of the monostable multivibrator is input to a microcomputer forming a part of the speed control mechanism.
Sewing machine speed setting device as described in section.