JPS58173591A - Speed setting apparatus of sewing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

In recent years, in the field of sewing machine control, microcomputers (hereinafter referred to as microcomputers) or Memo IJ, I
Products that make full use of electronic components such as C are being commercialized, and in the field of speed control in particular, so-called digital control methods that make full use of the above electronic components are beginning to be developed. d] There is something remarkable.

However, there are various difficulties involved in completely converting the speed control section to a gage digital system using a microcomputer, and it has not yet been realized, so it can be said that analog control is currently the mainstream.

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

The present invention aims to provide a sewing machine speed setting device that is simplest in configuration when configured as a digital speed control system centered on control elements such as a microcomputer, and is inexpensive and highly reliable. The basic speed control of a sewing machine is variable speed control according to the amount of pedal depression. In other words, 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 generally performs various functions. Therefore, in addition to the variable speed control described above, a fairly strictly fixed speed is required.

The first is a low speed setting for controlling thread trimming. The thread cutting operation is normally performed during a half rotation from the needle down position to the needle -L position, but the speed at this time must be maintained at a strictly low speed that 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 reverse stitching to prevent tangling, and the speed at that time is as follows:
It must be maintained at an intermediate speed regardless of 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 a specified speed that can be adjusted independently of the pedal position depending on the sewing machine function, and the present invention allows these speed settings to influence each other. We aim to provide this product at low cost and with high reliability.

Embodiments of the present invention will be described 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, and lining 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 to detect the speed of the sewing machine.

The operation is performed as follows. When the sewing machine pedal (not shown) is depressed to an appropriate level, the speed setting mechanism 1 outputs a speed setting signal vs based on the amount of pedaling, and this speed setting signal vs causes the speed control mechanism 2, drive mechanism 4
The rotational force of the motor 3 is transmitted to the sewing machine 5 through the sewing machine 5, and the sewing machine 5 starts rotating. Furthermore, the speed detection mechanism 6 linked to the sewing machine 5 detects the rotational speed of the sewing machine 6 and outputs a speed detection signal vF, and the speed when this speed detection signal vF is balanced against the speed setting signal vs. Then, the sewing machine 5 is driven.

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

In FIG. 2, 7 is a variable speed setting element having means for detecting the amount of depression of a sewing machine pedal (not shown) and converting it into a speed setting signal, and 8 is a microcomputer. This example shows a 4-bit single-chip microcontroller including memo IJ, Ilo, etc. 9 and 10 indicate drivers for the clutch coil 11 and brake coil 12;
As described above, it functions to transmit the rotational force of the motor 3 to the sewing machine 5 via the magnetic circuit, lining, and belt. Further, a same wave number generator 13 is fixed to the sewing machine shaft (not shown) V 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. Low speed setting element 15.
The intermediate speed setting element 16 and the maximum speed setting element 17 are each composed of a switch and an interface circuit.

The system constructed as described above operates as follows.

As mentioned above, when the sewing machine pedal is depressed,
The speed setting signal VS corresponding to the amount of pedal depression is input from the variable speed setting element 7 to the microcomputer 8 as 4-bit digital data. The clutch coil 11 is excited through the belt, and therefore, as described above, the rotational force of the motor 30 is transmitted to the sewing machine 5Vc through the belt, and the sewing machine 5 is started.

When the sewing machine 5 is started in this manner, the frequency generator 13 attached to the min/min shaft generates a pulse signal with a period according to the monthly rotation speed VC of the sewing machine, and furthermore, the waveform shaping circuit 14 The waveform is shaped into a square wave by
will be given feedback.

If the speed is too high for the speed setting signal vs.
2 is excited, the sewing machine 5 acts to be decelerated, and by controlling the excitation of the clutch coil 11 or the brake coil 12 in this way, the sewing machine rotational speed according to the speed setting signal is maintained. Become.

Here, the speed control function based on the arithmetic expression of the microcomputer 8 will be described below with reference to FIGS. 3 to 6. .

In the case of minimum speed operation, the microcomputer 8 performs calculations according to the following calculation formula as shown in Figure 3.

TBc-aTF-booooooo (1) First, calculate the pulse train section from the frequency generator 13 using formula (1), and then calculate the pulse train section from the next pulse train section obtained by the calculation. Only the time ITBC1 acts to disengage the clutch or excite the brake coil, and speed control is performed by repeating this sequentially. usually,
In stable operation where the sewing machine load is constant, the sewing machine is driven at point α in the figure.

The state of the current flowing through the clutch coil 11 at this time is determined by the fourth
Shown in the figure as a solid line.

Here, the gain constant a in equation (1) determines the gain of the system. That is, when d is a dog, even a slight variation in the period TF causes a change in the closing ratio of the clutch (braking or braking) coil, thereby increasing the yarn gain.

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

In this way, constant speed control is performed at the lowest speed e. On the other hand, for medium speed to high speed operation, the frequency generator 13
This is done by dividing the pulse train of 1 by using the software of the microcomputer 8. That is, if the minimum speed obtained as described above is 81, the division ratio is 17/N, and the gain of the system is high enough to ignore the sewing machine load fluctuation due to changes in the rotation speed, the speed S can be calculated using the following formula. expressed.

5=NS1...(2) (However, N-1, 2, 3,...) Here, by modifying the speed setting signal V3 from the variable speed setting element 7 in FIG.
2) By changing N in the equation, the speed S can be changed stepwise. That is, when the speed setting signal Vs is input to the microcomputer 8 as 4-bit data, the microcomputer 8 converts the 4-focus data to N in equation (2) according to the contents preset in the internal ROM, It acts to perform frequency division. Therefore, the above R
It can be said that by appropriately configuring the OM, various speed curves such as those shown by "I" or "I" in FIG. 5 can be selected.

The following is the normal control according to the speed setting signal s from the variable speed setting element 7.Next, various setting elements shown in FIG. 2 will be described below with reference to FIG.

Low speed setting element 15. The intermediate speed setting element 16 and the maximum speed setting element 17 each have a 4-bit code as described later.
It is composed of a circuit that includes multiple circuits, and its operation is performed as follows.

First, when the low speed setting signal VL is input from the low speed setting element 15 to the microcomputer 8 as 4-bit data, the microcomputer 8 has a built-in device configured in advance to correspond to the low speed setting signal VL and obtain a predetermined numerical value. Convert the data of the above low speed setting signal ■L according to the ROM table of
The data after the conversion is substituted into the constant of the equation (1), and the arithmetic processing is performed. That is, the low speed setting element switches from the calculation straight line shown by the solid line in FIG. 16
The minimum speed of the sewing machine can be changed in 16 steps.

Here, as described above, the speed to be changed by the low speed setting element 16 is only the minimum speed of the sewing machine where N is 1, and the N is set by the equation (2).
For speeds greater than = 2, the speed should be adjusted to the standard calculation straight line, which is predetermined and fixed.
It can be obtained by setting 1. That is, the above (2
) in the formula is distinguished between N-1 and other cases, and only in the case of N-1, the calculation straight line can be switched by the low speed setting element 16, and in cases other than N-1, the calculation straight line is set to a constant value. The reference calculation straight line is adopted, and the operation is performed as described above in S1.

Next, the intermediate speed setting signal VM is output from the intermediate speed setting element 16.
is input to the microcomputer 8, it is converted into a predetermined numerical value according to a built-in ROM table different from the above in the same manner as above, and then the converted data is entered into the above equation (2). This is given as the frequency division number N, which acts to change the intermediate speed. Therefore, it is possible to switch intermediate speeds in 16 stages according to input data. Here, the variable speed setting signal vs from the variable speed setting element 7
Alternatively, which of the intermediate speed setting signals vM to be adopted is separately determined by the microcomputer 8 according to the sewing process of the sewing machine. However, if the intermediate speed is not fixed and the converted data of the variable speed setting signal vs is smaller than the converted data of the intermediate speed setting signal vM, then the variable speed setting signal vs is It is also possible to configure it so that it is enabled. In other words, it can be said that only the upper limit intermediate speed can be commanded from the intermediate speed setting element 16. Next, the maximum speed setting signal vH is sent from the maximum speed setting element 17.
is input to the microcomputer 8, it is converted into a predetermined numerical value according to a built-in ROM table different from the above in the same manner as above, and then the converted data is used in the above equation (2). As the number of divisions N! therefore, this acts to change the maximum speed. By making the data after the above conversion sufficiently large, as shown by the broken line in Figure 6, 1
It is possible to switch between 6 levels of maximum speed.

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, or speed control is performed according to commands from various speed setting elements.

Normally, the minimum speed of a sewing machine requires delicate adjustment in order to accurately stop the sewing machine at a predetermined position. It is desirable from the viewpoint of operability of sewing work that the relationship between the sewing machine rotational speed and the amount of treading does not change. As mentioned above, one feature of the present invention is that only the lowest speed of the sewing machine can be varied by the low speed setting element, and other intermediate speeds are not affected at all.
Therefore, the above problem is solved.

Next, 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 first 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 possible, such as one in which this amount of movement is detected by a magnetically sensitive element and further converted into a several-bit signal by an A/D conversion circuit.

Still, the low speed setting element 15. Intermediate speed setting element 16
．． A more specific example of the configuration of the maximum speed setting element 17 is shown in FIG.

In FIG. 7, each switch represents a 4-bit code switch, and each switch can be switched in 16 types, including the low speed setting element 15° and the intermediate speed setting element 16.
．． The 0 dimension shows the three code switches of the high speed setting element 17. Each IC is a tri-state IC, and when the output ports O8 to 02 of the microcomputer 8 are high, they become inactive, and the above The output of the IC is in a high impedance state, but the input port 'O'''-''3 of the microcomputer 80
As mentioned above, the output of each code switch is switched by the output ports % to 02 of the microcomputer 8, and after selection, the matrix is read from the input ports F10 to i3 of the microcomputer 8. It is structured as follows.

The operation usually starts with the output port O8 of the microcomputer 8.
02 is "HI+", so input port i to the microcomputer 8. -13 is all "L" regardless of the status of each code switch, so set the output port of the code switch you want to read next to "L", and input For example, when reading the state of the code switch of the low speed setting element 15, the output port % of the microcomputer 8 is set to "L" without changing it, and then the input ports 1° to i3 are
When the switch is on, the state of the switch is read, and when the switch is on, the signal is H'', and when the switch is off, the signal is L''.

Normally, each code switch is switched by rotating it, but in this case, in order to prevent unexpected data from occurring at the boundary between each switch, which would cause the speed setting to fluctuate abnormally, It can be said that it is desirable to have a Gray code configuration in which only one of the switches corresponding to each bit changes and switches at the above boundary.

An example of the configuration of a code switch using the above Gray code is shown in the table below.

(Left below) (O20N) 2 Examples (I') The case where a 14-bit microcomputer is used is described, but of course other microcomputers such as 8-bit and 16-bit microcomputers were used. The present invention is also effective in cases where 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 The present invention is effective in any case in which the microcomputer is provided outside the microcomputer.

As is clear from the above description, according to the present invention, digital control by a control element such as a microcomputer is performed in a very simple configuration, and therefore reliability is improved and a product is realized at low cost. It is very much a dog.

[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, and Fig. 4 is a diagram showing the principle of speed control. A diagram showing a clutch current waveform, FIG. 5 a diagram showing an example of the configuration of a curve of the sewing machine rotation speed with respect to the amount of sewing machine pedal depression, and FIG. 6 a diagram showing an example of setting the maximum speed by the maximum speed setting element.
FIG. 7 is a circuit diagram showing a specific example of the configuration of various speed setting elements. 1... Speed setting mechanism, 2... Speed control mechanism, 3... Motor, 4... Drive mechanism, 6... Sewing machine, 6... Speed detection mechanism, 7... Variable speed setting element, 8... Microcomputer, 13... Frequency generator, 15...
...low speed setting element, 16... intermediate speed setting element, 17... maximum speed setting element. Name of agent: Patent attorney Toshio Nakao and one other IL
Figure 3 Figure 4 Figure 5

Claims (5)

[Claims] (1) A drive mechanism that drives the 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 combination of the output of the speed detection mechanism and the speed setting mechanism. a speed control mechanism for controlling the rotation of the sewing machine shaft by comparing the output with the sewing machine shaft; The speed 1 change setting mechanism is composed of a variable speed setting element corresponding to the movement of the sewing machine pedal and a plurality of prescribed speed setting elements including at least a low speed setting element, and the speed adjustment by the low speed setting element is performed by the variable speed setting element. A sewing machine speed setting device configured to affect only the low speed of an element and not to affect other variable speeds or other prescribed speed setting elements. (2) The sewing machine speed setting device according to claim 1, wherein the specified speed setting element includes a code switch comprising a plurality of set contacts. (3) The sewing machine speed setting device according to claim (2), wherein the code switch is constructed of a gray code. (4) The sewing machine speed setting device according to claim (2), wherein the output of the code switch is input to a microcomputer forming a part of the speed control mechanism. (5) The sewing machine according to claim (2), wherein the output of the code switch is constituted by a matrix selectable by the output of the microcomputer forming a part of the speed control mechanism, and the output is input to the microcomputer. Speed setting device 0