JPS6366554B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention controls the speed of a sewing machine at a variable speed according to the separation distance of a pedal from a prescribed position, and also positions and stops the sewing machine at a prescribed needle position as the pedal moves to a prescribed position. The present invention relates to a sewing machine drive device having a so-called needle fixed position stop function. Conventional configuration and its problems Conventionally, as a method for stopping the hands at a fixed position, a method as shown in the time chart of FIG. 1 has been generally adopted. Normally, a sewing machine uses a motor through a belt to
Alternatively, the sewing machine is directly driven, and by operating the pedal of the sewing machine, the sewing worker controls the motor through the control unit, and also controls the sewing machine at variable speed or stops the needle at a fixed position while sewing a predetermined sewing product. A series of tasks will be carried out to complete the project. Generally, when the sewing machine leaves the pedal in an open state (hereinafter referred to as neutral) where no force is applied by the sewing worker, the sewing machine remains in a stopped state, and when the pedal is depressed for a predetermined distance or more, The sewing machine is driven, and the speed varies depending on the treading distance.
Variable speed control is provided up to the maximum speed. In FIG. 1, when the pedal is depressed to its maximum position, the sewing machine is operating at maximum speed. When the sewing worker returns the pedal to the neutral position from such a state, the pedal position is first detected, the signal "PN" is switched from "L" to "H", and the signal "PN" is switched from "L" to "H". As a result, the sewing machine is set to a low speed "N _L " (hereinafter referred to as position speed) for positioning, and is rapidly decelerated. Next, after reaching the position speed "N _L ", the sewing machine is positioned and stopped when the needle position signal "ND" indicating the position to be stopped is confirmed. The above operations are performed, and the time "T _L " from reaching the position speed "N _L " to confirming the needle position signal "ND" is the longest time equivalent to one rotation at the position speed. This takes a long time, and the time varies depending on the rotation angle position when the position speed is reached. The time “T _L ” is the position speed “N _L ”
Since the sewing speed is low, the sewing length is very long, which is a major factor that significantly reduces sewing efficiency. Another disadvantage is that the time "T _L " changes every time the sewing is done, and the rhythm of the sewing does not match, making it impossible to perform the sewing work smoothly. In order to improve sewing efficiency, in the conventional method, the only way is to increase the position speed "N _L ".On the other hand, increasing the speed causes the stop position during positioning to change due to speed fluctuations. This may change due to various factors such as voltage fluctuations, and as a result, the needle position cannot be determined and the function of stopping the needle in the fixed position cannot be performed, causing problems such as hindrance to sewing work and reaching a limit. Ta. As mentioned above, the conventional method has the disadvantage that it takes a long time to sew between the final stitches during positioning, which reduces sewing efficiency. However, there is a limit to the accuracy of stopping the needle position, and countermeasures for these two conflicting problems are extremely difficult, and so far nothing has been resolved. OBJECTS OF THE INVENTION It is an object of the present invention to provide a sewing machine drive device that eliminates the above-mentioned drawbacks, improves sewing efficiency, and has high accuracy in stopping the needle at a fixed position. Composition of the Invention The present invention provides a plurality of sensors that, in the process of stopping the needle at a fixed position, have a plurality of One of the conversion elements is configured to select one of the conversion elements based on the measured speed, and data included in the conversion element that instructs the speed setting is selected based on the measured rotational angle position, and each of the conversion elements selects the speed setting according to the measured rotational angle position. By arranging the value data so that it becomes maximum at the passing position of the target stop position and minimum immediately before it, the rotation angle position and speed can be actually measured and the sewing machine can be targeted at a predetermined braking curve based on the results. It is intended to stop the sewing machine at the desired position, and is characterized in that the braking curve can be freely selected by selecting the speed setting value data using the selection hand. The time can be made sufficiently short and constant, making it possible to improve sewing efficiency.Furthermore, the speed just before the target stopping position can be maintained at the same speed as before or lower than before, so needle position stopping accuracy with less variation than before can be achieved. In particular, when a digital speed control system is constructed, it can be constructed at a very low cost by making full use of one-chip microcomputers (hereinafter referred to as microcomputers) that have been commonly used in recent years. It has many advantages. Various other features and advantages will become clear from the description below. DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the block diagram of FIG. In the figure, reference numeral 1 denotes a frequency generator, which is attached to the shaft end of the sewing machine and outputs a plurality of pulse signals "FP" per revolution with a period proportional to the rotational speed of the sewing machine. A needle position detector 2 is attached to the shaft end of the sewing machine in the same way as the frequency generator 1, and generates a needle position signal "ND" corresponding to the upper or lower position of the needle of the sewing machine. 3 is a speed setting device that detects the state of the sewing machine pedal (not shown), outputs a signal "PN" at the neutral position of the pedal, and converts a value that changes depending on the pedaling distance at the pedal depression position into a 4-bit speed setting device. Output as command signal “SV”. Reference numerals 4 and 5 denote a clutch coil and a brake coil, respectively, which are built into the output section of the motor 6, and when the clutch coil 4 is excited, the rotational force of the constantly rotating motor 6 is transmitted to the clutch lining and outputted through its magnetic circuit. The brake coil 5 is transmitted to the sewing machine through a shaft (not shown) and further via a pulley and a belt.
When excited, the brake lining (not shown) is brought into pressure contact with the stationary side through the magnetic circuit, and the stationary force is transmitted to the sewing machine as described above. Normally, variable speed control is performed by controlling the excitation current to the clutch coil 4, controlling the pressure contact force on the clutch lining surface, and producing appropriate slippage. The other parts are blocks of electronic circuits and can be replaced with discrete ICs, etc., and these will be explained one by one according to the operation explanation below. First, when the speed setting device 3 detects the depression of the pedal and the signal "PN" changes from "H" to "L", the stop control means 7 sets the signal "CLD" to "L" for a short time.
→ "H", flip-flop (hereinafter referred to as F/F) 9 is set via OR gate 8, clutch coil 4 is energized via driver 10, and the sewing machine is started as described above. The speed of the sewing machine that has started rotating as described above will be controlled digitally as shown below, but such a method has already been disclosed in Japanese Patent Application No. 1983-
This is disclosed in No. 139071 or Japanese Patent Application No. 139073. The above-mentioned speed control is shown in FIGS. 3 to 5, and the same figures will also be explained below. While the sewing machine starts rotating as described above,
The speed command signal “SV” from the speed setter 3 is 4.
The speed command signal "SV" is output as bit data and is given as address data of RM11, and by selecting the contents of the corresponding RM address, it is converted to a speed setting value indicating the number of divisions for speed setting, which will be described later. After that, data selector 12
Output to. The data selector 12 outputs an input on the "B" side because the input to its select terminal "S" is "L", and therefore, it outputs the input on the "B" side based on the speed command signal "SV" from the speed setting device 3. The speed setting value "DV" is output and set in the frequency divider 13. The frequency divider 13 divides the pulse signal "FP" outputted from the frequency generator 1 by the number of times of the set speed setting value "DV", and then outputs the signal "PD". The period counter 14 counts the clock pulse signal from the clock oscillator 15 over one period of the frequency-divided signal "PD", holds the counting result by the latch circuit 16, and calculates it as 8-bit period data "TP". output to the device 17.
Note that the clock pulse signal is an oscillation signal with a sufficiently short cycle relative to the frequency-divided output signal "PD", so that the speed will not change due to measurement errors, for example, variations in the cycle of one pulse. It is necessary to select a pulse signal with sufficiently short resolution that the control system is not affected much. After the arithmetic unit 17 performs the arithmetic operation described later,
According to the calculation result, if the periodic data “TP”
If is large (low speed), or gate 8,
The clutch coil 4 is excited via the F/F 9 and the driver 10, and if the periodic data "TP" is small (high speed), the OR gate 18,
The F/F 19 acts to excite the brake coil 5 via the driver 20, and its operating time is:
It is determined by presetting the calculation result data by the arithmetic unit 17 as 8-bit data in the preset counter 21 and counting the clock pulse signal by the number of data, and after this operation time has elapsed, the F19 is reset and the clutch coil 4 or brake coil 5 is turned off. In this way, after actually measuring the frequency-divided data "TP" of the pulse signal "FP" output from the frequency generator 1 and performing calculations, the data "TP" is calculated between the next frequency-divided periods. Actual measurements and controls are sequentially repeated to control the speed, just as the clutch coil 4 or the brake coil 5 is controlled.The details are shown in FIGS. I will tell you about it. FIG. 3 is a graphical representation of an example of the arithmetic expression by the arithmetic unit 17, where T _CB = AT _P −B
...(1) (A, B: Constant, T _P : Actual period,
T _CB ; indicates clutch or brake application time). In the above equation (1), the constant A determines the rate of change in the clutch/brake engagement time T _CB with respect to the measured cycle T _P , and is therefore considered to be a constant that determines the gain of the speed control system, It is determined by considering the stability or responsiveness of the system. On the other hand, constant B determines the rotation speed of the sewing machine, and when the load on the sewing machine is determined and the frequency division number is 0.
This is uniquely determined by determining the speed at which the vehicle is moving (hereinafter referred to as the reference speed). If the sewing machine is operating stably at point a shown in the same figure, a clutch current I _C flows according to the duty cycle T _CB1 in period T _P1 as shown in Fig. 4 a. , which will balance the load on the sewing machine. Fig. 4b shows the state of acceleration, and as the sewing machine accelerates, the measured period TP becomes shorter.
Therefore, the calculation results using the above calculation formula are also T _C1 , T _C2 ,
The clutch current I _C is gradually reduced to T _C3 and the above operation is repeated until the clutch current I C decreases and shifts to a stable state in which it balances the sewing machine load. On the other hand, Figure c shows the process in which the sewing machine gradually decelerates, and as the measured period "TP" increases, the brake-on time decreases to T _B1 , T _B2 , and the clutch-on time T _C1 , T _C2 , T _C3 , thus representing the process of switching from a decrease in brake current I _B to an increase in clutch current I _C. The above has described the operation at the reference speed, but by substituting the data after dividing the frequency by the number of divisions n as the actual measurement period "TP", it is possible to change the load of the sewing machine depending on the rotational speed. If the gain of the speed control system is sufficiently high, a stepped sewing machine speed as shown in equation (2) below can be obtained. N _S = (n+1) N _L ...(2) (However, n: Number of divisions N _S ; Sewing machine speed N _L ; Reference speed) From the above, 4 of the speed command signal "SV" corresponding to the front pedal position It is clear that by appropriately assigning the frequency division number to each address of the RM11 indicated by the bit data, it is possible to set the sewing machine speed with respect to the pedal depression position. An example of this is shown in FIG. ing. Note that the number of frequency divisions n is shown in parentheses. As described above, variable speed control is performed when the pedal is depressed.Next, the operation when the pedal is placed in the neutral position will be described. Here, reference numeral 22 indicates a position counter, which is reset at the front edge of the needle position signal "ND" every revolution while the sewing machine is running, and is reset by the pulse signal "FP" from the frequency generator 1. The counting is repeated, and therefore, the output "P" indicates the rotation angle position data with the front edge of the needle position signal "ND" as a reference. For example, if a 160-pole frequency generator 1 is used, the position data "P" will have 8-bit rotational angle position data from 0 to 160 as an 8-bit binary value. The RM23 uses only the upper 3 bits of the 8-bit position data and simplifies it so that its value is "0" to "5".
Address “0” of RM24, RM25 ~
"2", and speed setting value data corresponding to the frequency division number n is assigned to each RM in correspondence with each address. Furthermore, a switch 26 is connected to the upper address "3" of each RM, and the switch 26 allows selecting one of the two types of speed setting value data groups. Examples of data allocation to each of the above RMs are shown in the table below and FIG. 6. As shown in the figure, there are five types of data for the aforementioned position data "P",
Data shown in parentheses is assigned to each address, and either a or b can be selected by the switch 22. That is, RM23 is 6-2 (5-2), RM24 is 9-2
5 (7 to 4), RM25 sets 4 to 0 (3 to 0) to the position data in five stages such that the position where the front edge of the needle position signal passes is the maximum and the position immediately before that is the minimum. Assigned.

[Table] As mentioned above, when the pedal is depressed and the sewing machine is operating at high speed, then the pedal is brought to the neutral position, the speed setting device 3 first detects the neutral position of the pedal, and outputs the output signal "PN". “L” →
This output signal "PN" switches the data selector 12 to the "A" input selection state and instructs the stop control means 7 to start needle fixed position stop control. Here, the stop control means 7 is usually constituted by a microcomputer, and an example of its control operation is shown in the form of a flowchart in FIG. 7, and the operation will be described below with reference to the same figure. In the main routine, all flags are set at 27, and _C1 if the pedal is depressed.
~ _C3 output is in its initial state. Next, the pedal is set to neutral and the signal “PN” changes from “L” to “H”
Then, in response to the interrupt input of the frequency-divided pulse signal "TP", the TP interrupt processing first sets _C1 to "L" and selects the RM23, as shown at 28.
The data of the RM 23 selected as described above is sent to the frequency divider 13 via the data selector 12.
After the pulse signal "FP" is frequency-divided by the set number of divisions "DV", its period is actually measured and given as "TP" to the stop control means 7 again in the next cycle. It is determined in step 29 whether the period "TP" measured in this manner is greater than or equal to the set value _TP1 . In other words, this judgment is the sixth
It is determined whether the speed is higher than the speed indicated by the two-dot chain line in the figure. If the speed is high, then _C2 is set to "L" at 30 and the RM24 is selected. The selected RM24 has the position data "P"
While outputting the speed setting values 9 to 5 (7 to 4) according to the following, it is repeatedly determined whether the actually measured period “TP” is greater than or equal to the setting value “TP ₁ ” at step 31, and the actual measured period “TP” is set. When the value “TP ₁ ” or more is reached,
Set FLN ₁ . Thereafter, when the front edge of the needle position signal "ND" is confirmed at step 32, FLN ₂ is set, C ₃ is set to "L", RM25 is selected, and the speed setting is successively lowered, thereby performing sequential control. will be done. As described above, after "0" of the speed setting value of RM25 in FIG. When the front edge of "ND" is detected, the "BRD" signal is output for the time required to stop, the brake coil 5 is energized, the sewing machine is stopped at a predetermined needle position, and a series of needle fixed position stop controls are performed. complete. The above operation describes the case where the sewing machine stops from high speed, and in such a case, the above R
The speed is actually measured while repeating the speed setting described in M24, and after the point when the measured value becomes less than the set speed, the control is switched to sequential control, the set speed is sequentially lowered, and the needle position signal "ND" is When the front edge is detected, the RM25 is selected, and the set speed is further decreased according to the rotation angle, and after reaching the set speed of the reference speed before the needle position signal "ND", the needle of the sewing machine is moved at the front edge. This is done by stopping at a fixed position. Note that the needle fixed position stop control from a speed lower than the setting based on RM23 in FIG.
This is done by braking according to the set speed. The above-mentioned stopping process from high speed is shown in FIG. 8 as a time chart. The figure shows a case where the sewing machine performs the needle fixed position stop control from a high speed, and in such a case, the setting based on RM24 is repeated according to the actually measured rotation angle position. During this period, the brake coil is fully energized and the sewing machine is decelerated at the maximum inclination (negative acceleration), and at point "P ₁ " when the set speed based on RM24 is reached, the sewing machine enters the sequential control described above. and transitioned to RM24 and R
The speed of the sewing machine decreases according to the braking curve set by OM25, and finally stops at the determined needle position. Here, the above-mentioned stop control to the target position is performed by RM
24 and 25, but it is possible to increase the number of needles for even higher speed control, and the purpose of the present invention can be achieved. From this point of view, it is not a good idea to control the high speed side too much and make the slope gentle, and as shown in the application example of the present invention, it is preferable to set the above sequential braking control section one to two stitches before the target stop position. Goals are most effectively achieved if The time T _E required to sew one stitch before stopping in FIG. 8 can be determined by selecting the speed setting value of the RM 25 using the switch 22 and changing the slope of the braking curve for one revolution. That is, in the braking curve as shown in FIG. 6b, the section of the position speed is long, so the last stitch is long, but by turning on the switch 22, a quick stop as shown in FIG. 6a is achieved. If a configuration is adopted in which a larger number of speed setting value data groups of the RM are prepared than those shown in the embodiment and they are selected by several switches, the braking curve can be freely selected. However, the maximum slope is limited by the slope when the brake coil is fully excited. In addition, the stopping position when stopping the needle at a predetermined position varies due to variations in braking force due to variations in power supply voltage, variations in frictional force on the surface of the brake lining, etc., but the reference speed before stopping shown in the figure " It is generally clear that the above fluctuation range can be reduced by lowering N _L '', and by configuring it in this way, the present invention exhibits its effects even more. That is, this can be easily realized by increasing the constant B in equation (1) and therefore decreasing the reference speed N _L after the pedal is placed in the neutral position. The configuration of this embodiment described above is entirely digital, and most of it can be configured with a one-chip microcomputer. Effects of the Invention As is clear from the above description, the present invention measures the rotation angle position and rotation speed in the process of stopping the sewing machine needle at the target position, and stores braking curve data in advance based on the measurement results. This is based on the idea of stopping the sewing machine at a predetermined target position according to the braking curve while selecting the data of the converting element and setting the speed. According to the present invention, the sewing time between one stitch before the final stop, which conventionally took a long time, can be shortened and made constant, thus improving sewing efficiency. In addition, the operability has been improved, and the accuracy of the stopping position can be further improved, and the best braking curve can be selected in response to differences in load and inertia depending on the sewing machine, and it can be constructed at a lower cost. It has various characteristics, and its effects are very large.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the operation of the conventional example, Fig. 2 is a block diagram showing the configuration of the present invention, Figs. 3 to 5 are explanatory diagrams of the operation of variable speed control, and Fig. 6 shows a and b. An explanatory diagram showing a configuration example of speed setting data of a conversion element,
FIG. 7 is an explanatory diagram showing the operation of the present invention, and FIG. 8 is an explanatory diagram showing the relationship between sewing machine speed and time of the present invention. 1... Frequency generator, 2... Needle position detector, 3
...Speed setting device, 4...Clutch coil, 5...
Brake coil, 6... Motor, 7... Stop control means, 11, 23-25... RM, 12... Data selector, 13... Frequency divider, 14... Period counter, 17... Arithmetic unit, 21 ...Preset counter, 22...Position counter, 26...Switch.

Claims (1)

[Claims] 1. A sewing machine, a motor that drives the sewing machine,
a frequency generator that generates a pulse signal with a period that changes in proportion to the rotational speed of the sewing machine; a needle position detector that detects a predetermined needle position of the sewing machine and outputs a needle position signal; and a pedal regulation. a speed setter that outputs a stop command signal at the position and outputs a speed command signal according to the separation distance from the specified position; and a speed setter that is reset by the needle position signal, counts the pulse signals, and generates a rotation angle signal. a position measuring means for outputting, a speed detecting means for detecting the rotational speed of the sewing machine and outputting an actual speed signal, and a speed detecting means for detecting the rotational speed of the sewing machine and outputting an actual speed signal; The speed control means includes a conversion means for converting into a speed setting value, a selection means for selecting the speed setting value data of the conversion means, and a speed control means for controlling the speed of the motor. When it is moved to a position other than the specified position, it operates according to the speed command signal, and in the fixed position stopping process when the stop command signal is output, it is operated by the selection means from the conversion means. A sewing machine driving device configured to position and stop the sewing machine when the needle position signal is detected after operating according to a selected speed setting value. 2. The speed detection means includes a clock oscillator that generates a clock pulse signal and a counter, and is configured to count the number of clock pulse signals during one cycle of the pulse signal of the frequency generator and output the counting result as the actual speed signal. A sewing machine drive device according to claim 1. 3 The conversion element included in the conversion means is configured with a ROM, and the address of the ROM is designated according to the position signal, and the conversion element includes a plurality of ROMs, and one of the ROMs is configured according to the actual speed signal. The sewing machine drive device according to claim 1, wherein the sewing machine drive device is configured to select one of the two.