JPH09300128A - Position setting mechanism in shearing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a stable and high precision position setting to be attained under application of a general type of motor. SOLUTION: An induction motor 7 controlled by an inverter 5 moves a position setting member 9, a position sensing means 15 detects a position of the position setting member 9 so as to perform a position setting in response to a positional signal. At this time, a control device changes over a turning-on or a turning-off of the inverter 5 so as to control a moving speed of it. In the control device, a pulse signal generated by a pulse oscillating device 19 and an ON/OFF signal from a control section 16 are added by an adding device 23, the added signal is sent to the inverter 5 as an instruction signal and at the same time a speed instruction section 17 generates directly a speed instruction signal to the inverter 5. Or, a calculation part changes over the ON/OFF of the inverter 5 at a high speed in accordance with a program so as to perform a high speed control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning mechanism in a shearing machine, and more particularly to a positioning mechanism in a shearing machine equipped with an inexpensive positioning correction mechanism.

[0002]

2. Description of the Related Art As a positioning means for metal material processing machines such as back gauges such as shearing machines for shearing plate materials, general-purpose motors (induction motors, etc.) that output in accordance with the frequency of a servo motor capable of highly accurate positioning. Two of the + inverters are common. The former is highly accurate but extremely expensive and has the disadvantage of not being able to reduce costs. The latter is a general-purpose motor that has been around for a long time, and an inverter control is added to the induction motor, which has a low cost, in order to bring out the accuracy as much as possible, in order to achieve both accuracy and cost. However, the back gauge of the shearing machine has a considerable weight because it is rigid enough to withstand the metal material that is abutted, and the inertial force at the time of stop is large due to the demand for high-speed positioning. It slows down and eventually coasts to a stop.

FIG. 7 shows a positioning operation by a positioning mechanism for controlling a general-purpose motor such as a conventional induction motor by an inverter. That is, after starting, the vehicle accelerates (section 101 in FIG. 7) and moves at the highest speed (section 103). If the frequency of the inverter is lowered when the target value is approached to some extent, the first deceleration section 105
After that, the moving speed decreases (section 107), the frequency of the inverter is further lowered, and further deceleration movement is performed via the second deceleration section 109 (section 111). Then, in general, a stop command is issued to the motor at a position PS before the target value DP by a coasting amount, and then the motor is moved to the target position by coasting (section 113).

However, according to this method, accurate positioning cannot be performed unless the coasting amount is constant. For example, if the actual coasting amount is less than the set coasting amount, the vehicle will stop before the target value. When the amount of coasting is large, the target value is exceeded.

In order to solve the problem of the deterioration of the positioning accuracy due to the coasting amount, it is considered that the load of the drive system is kept constant and the coasting amount is always kept constant. Alternatively, it is conceivable to make the final positioning speed as low as possible so that the coasting amount falls within the error range of the target value.

[0006]

However, there is a problem that it is difficult to keep the coasting amount constant, especially when stopping the above-mentioned heavy member. That is, this is because the frictional resistance changes due to changes in the amount of grease in the sliding parts and rotating parts that transmit power to the positioning mechanism and changes over time in the same members.

In addition, the minimum frequency of the inverter is fixed due to its characteristics, and the v / f (voltage / frequency) is constant control, and when the frequency is reduced for deceleration, the torque also decreases,
I am not good at generating low speed and some torque. In order to realistically meet the positioning accuracy of heavy members such as the above-mentioned processing machines, if the speed is low and the frequency is low, the torque for driving the member will be insufficient and the member will not move.If the frequency is increased to increase the torque, the speed will also increase. There was a problem that the amount of coasting increased and a high-precision positioning was not possible, resulting in a dilemma.

The object of the present invention has been made in view of the above-mentioned conventional techniques, and provides a positioning mechanism in a shearing machine capable of performing stable and highly accurate positioning using a general-purpose motor. To do.

[0009]

In order to achieve the above object, a positioning mechanism in a shearing machine according to a first aspect of the present invention comprises an induction motor for driving a positioning member and an inverter for outputting a drive output command to the induction motor. And position control means for detecting the position of the positioning member, and control means for controlling the inverter based on a position signal from the positioning means. The control means turns on a drive output command from the inverter. -A pulse signal that issues a run signal that indicates off and a speed command that determines the set frequency of the inverter itself, and that emits a pulse signal, and the pulse signal from this pulse oscillator interrupts the first run signal to the inverter And a gate circuit.

Therefore, the induction motor controlled by the inverter moves the positioning member, the position detecting means detects the position of the positioning member, and positions the positioning member based on the position signal. At this time,
The control means determines the set frequency of the inverter itself, and also issues a signal that determines the on / off state of the output signal from the inverter and the control direction. Emits a second run signal to.

A positioning mechanism in a shearing machine according to a second aspect of the present invention comprises an induction motor for driving the positioning member, an inverter for outputting a drive output command to the induction motor, and position detecting means for detecting the position of the positioning member. A control means for controlling the inverter based on a position signal from the positioning means, the control means comprising a run signal for instructing on / off of a drive output command from the inverter and a set frequency of the inverter itself. And a waveform forming section for forming an output waveform of the run signal into an intermittent waveform.

Therefore, the induction motor controlled by the inverter moves the positioning member, the position detecting means detects the position of the positioning member, and positions the positioning member based on the position signal. At this time,
The control means determines the set frequency of the inverter itself, and turns on the inverter with the intermittent waveform formed by the waveform forming section.
A run signal to turn off is issued.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An example of a preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a first embodiment of a positioning mechanism 1 in a shearing machine. As shown in FIG. 1, an inverter 5 is connected to the control device 3 as a control means, and an induction motor 7 is connected to the inverter 5.

The induction motor 7 is a motor in which a rotating magnetic field is generated by the input of a current and the rotor is dragged by this magnetic field to rotate, and the rotational speed of the motor is determined by the number of winding poles and the power supply frequency. Yes, it is defined that a predetermined rotation output is obtained when the power supply frequency is determined.

A ball screw 11 for moving and positioning a positioning member 9 such as a back gauge is connected to the induction motor 7 via a gear mechanism (not shown) or the like. Further, a ball nut 13 screwed onto the ball screw 11 is attached to the positioning member 9.

Further, the induction motor 7 is provided with an encoder 15 as a position detecting means,
The encoder 15 is connected to the control device 3. Therefore, the encoder 15 is the induction motor 7
The position of the positioning member 9 is detected on the basis of the rotation angle and the position signal is fed back to the control device 3.

On the other hand, the control device 3 includes a speed command section 17 for controlling the speed of the inverter 5 and the encoder 15.
An arithmetic unit 16 having a position determination unit 21 that determines the position of the positioning member 9 by receiving a position signal from the pulse generator 19, a pulse oscillator 19 that generates a pulse signal, and an adder 23 that is a gate circuit are provided.

The arithmetic unit 16 issues a first run signal P1 for controlling the inverter 5 to the adder 23, and the speed command unit 1
7 directly issues a speed command signal P0 to the inverter 5 on the basis of the signal from the position determination unit 21 to set the frequency of the inverter 5 itself.

The pulse oscillator 19 is connected to the adder 23, and the pulse signal P from the pulse oscillator 19 is outputted.
2 is input to the adder 23 and inverted. The pulse oscillator 19 is activated when the positioning member 9 reaches the final deceleration position (in FIG. 3) based on the signal from the calculation unit 16. Therefore, before reaching the final deceleration position, the signal P2 is always off because the pulse oscillator 19 does not operate,
Therefore, the second run signal P3 is inverted by the adder 23.
Is always an ON signal.

The adder 23 is a first for controlling the inverter 5.
The run signal P1 and the pulse signal P2 are added to each other to issue the second run signal P3 to the inverter 5 to control the signal issued from the inverter 5.

Next, the operation of the positioning mechanism 1 in the shearing machine will be described with reference to FIGS. Since the overall operation is the same as that described in the section of the related art (see FIG. 7), the operation after the aforementioned second deceleration section 109 will be described.

In the second deceleration section, the induction motor 7 is driven at a predetermined low frequency to a certain extent (step SA1, section in FIG. 3), and the encoder 15 moves until the final deceleration position is detected (step SA2). This position is a position that is a predetermined amount before the target value.

During this period, the first run signal P1 issued from the control unit 16 to the adder 23 is in the ON state (see FIG. 4), and the signal P2 issued from the pulse oscillator 19 is in the OFF state, but is inverted to ON by the adder 23. Then, the second run signal P3 is generated and transmitted to the inverter 5. Therefore, the second run signal P issued from the adder 23 to the inverter 5
Since 3 is a continuous ON signal, the inverter 5 rotationally drives the induction motor 7.

When the final deceleration position (in FIG. 3) is detected and the pulse oscillator 19 is driven, pulse operation is started. (Steps SA3 to 5, Section in FIG. 3) In this pulse operation, when the pulse signal P2 from the pulse oscillator 19 is on, the adder 23 turns off the second run signal P3 even if the first run signal P1 is on. , The motor drive output command from the inverter 5 which is on is not issued.

On the other hand, when the pulse signal P2 from the pulse oscillator 19 is off, the adder 23 turns on the first run signal P1 and turns on the second run signal P3, and the inverter 5 outputs a motor drive output command. Then, the induction motor 7 operates.

That is, as the pulse signal P2 from the pulse oscillator 19 is turned on / off, the signal P from the inverter 5 is held while the frequency of the inverter 5 is kept constant.
By switching the second run signal P3 for controlling the output of No. 4 at high speed, the induction motor 7 can be rotated at extremely low speed to move the positioning member 9. Actually, the inverter 5 is intermittently operated at a frequency higher than the lowest frequency in order to generate torque, but by switching on and off at high speed, it is apparently in a continuous operation state at a frequency lower than the lowest frequency.

In this way, when the target value is reached, the first run signal P1 is turned off and the second run signal P3 is turned off to stop the inverter 5 and complete the positioning (step SA6).

According to the positioning mechanism 1 in such a shearing machine, the movement of one step lower than the minimum speed possible by the inverter 5 can be realized without reducing the torque of the induction motor 7. The final coasting amount can be made extremely small, and highly accurate positioning can be smoothly performed even when the load changes.

In the above embodiment, the case where the adder (AND circuit) 23 is used as the gate circuit has been described, but when the pulse output is off, the run signal P3 is secondly output to the inverter 5. That is, the same effect can be obtained by combining a plurality of gate circuits such as a NAND circuit and an OR circuit.

Next, an example of the second embodiment will be described with reference to FIGS. The same parts as those in the example of the first embodiment described above are denoted by the same reference numerals, and the duplicated description will be omitted.

In the positioning mechanism 25 in the shearing machine shown in FIG. 5, a control device 27 as a control means for controlling the induction motor 7 for moving the positioning member 9 is a central processing unit (hereinafter referred to as "CPU") 29. , An input means 33 such as a keyboard connected to the CPU 29 through the I / O port 31, and a CR
It has an output means 35 such as T.

Further, the CPU 29 confirms the position of the positioning member 9 based on the position signal from the main memory 37 storing the program, the sub memory 39 for storing necessary data in and out, and the encoder 15, and the inverter 5 An arithmetic unit 41 and the like, which is a waveform unit that issues an on / off control signal, is connected. The calculation unit 41 is connected to the inverter 5 and sends a waveform command to the inverter 5 to control the induction motor 7 intermittently. The calculation unit 41 turns on / off the run signal P3 without using the force of the pulse oscillator 19 in the example of the first embodiment. The CPU 29 has a speed command unit 40 and is connected to the inverter 5 to directly set the frequency of the inverter 5 itself.

The operation of the calculation unit 41 of the control device 27 in the secondary deceleration will be described with reference to FIG. In the second deceleration section, the induction motor 7 is operated at a predetermined low frequency (step SB1), and the encoder 1
5 until the final deceleration position is detected (step SB
Move to 2). This position means a position that is a predetermined amount before the target value. When the final deceleration position has not been reached, an ON signal is issued to the inverter 5 in the same state to continue the low speed operation.

When it is confirmed that the final deceleration position has been reached, the on / off of the run signal P3 is switched at high speed in accordance with the program for creating the waveform shape stored in the main memory 37, and the intermittent operation is performed by the inverter 5. Instruct (step SB3). As a kind of program stored in the main memory 37, a basic waveform of one frequency of a pulse in the coordinate data system may be stored and the basic waveform read by the arithmetic unit 41 may be continuously output to the inverter 5. it can. The intermittent operation is continued until it is confirmed by the position signal from the encoder 15 that the positioning member 9 has reached the target value (step SB
4) A stop command (run signal P3 off) is issued to the inverter 5 (step SB5) to complete the positioning.

According to the positioning mechanism 25 in such a shearing machine, it is possible to obtain the same effects as those of the above-described first embodiment, and it is possible to easily change the existing shearing machine by changing the program. Can be applied.

The present invention is not limited to the above-described embodiments, but can be implemented in other modes by making appropriate changes. For example, in the example of the above-described embodiment, the case where the ratio of the ON signal and the OFF signal is constant has been described, but by changing this ratio, the rotation speed of the induction motor 7, that is, the positioning member 9 is changed according to the load. It is also possible to finely control the moving speed.

A change in load is detected by monitoring the amount of movement per unit number of pulse transmissions (for example, 0.
If it should move by 05 mm, but it does not move, it can be judged that the load has become heavy, and conversely, if it has moved 0.1 mm in two pulses, it can be judged that the load has become light. ), If the load becomes heavy, increase the pulse on time. Also, when the load becomes light, the CPU automatically performs operations such as shortening the pulse on time,
Stable positioning can be performed even when the load changes significantly. In addition, by adjusting the frequency up and down according to the change of the load to raise and lower the torque and changing the ratio of the on / off time of the pulse to the high / low of the motor rotation speed with the increase / decrease of the frequency, low speed high torque and high speed low torque Adjustment is possible.

Further, in the example of the above-described embodiment, the case where the position stopped by coasting after the correction command is before the target value has been described, but when the target value is passed by coasting, pulse driving is performed. Or, the direction of the intermittent operation is only the reverse direction, and the others are exactly the same. However, when backlash must be taken into consideration, such as when using a trapezoidal screw, it is necessary to perform positioning in one direction. It is necessary to return and then perform intermittent operation.

Further, instead of using the encoder 15 as the position detecting means, a linear scale or the like may be provided on the positioning member 9 or other known means may be used in the same manner.

[0041]

As described above, in the positioning mechanism of the shearing machine according to the present invention, the induction motor controlled by the inverter moves the positioning member, and the position detecting means detects the position of the positioning member. The positioning member is positioned based on the position signal. At this time, the speed command section of the control means determines the set frequency of the inverter itself and the gate circuit for continuously switching the run signal to the inverter based on the pulse oscillator and the pulse signal to turn on / off the output signal from the inverter. Since it is provided, the extremely low speed movement can be performed without reducing the torque of the induction motor itself. As a result, the final coasting amount can be suppressed to be extremely small even when the load changes, and therefore the positioning accuracy is improved.

In the positioning mechanism of the shearing machine according to the second aspect of the present invention, the induction motor controlled by the inverter moves the positioning member, the position detecting means detects the position of the positioning member, and the positioning is performed based on the position signal. Position the members. At this time, the speed command section of the control means determines the set frequency of the inverter itself, and an on / off signal for turning on / off the inverter is issued by the intermittent waveform formed by the waveform forming section, so that the torque of the induction motor itself is changed. It is possible to move at extremely low speed without dropping. As a result, the final coasting amount can be suppressed to be extremely small even when the load changes, and therefore the positioning accuracy is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a first embodiment of a positioning mechanism in a shearing machine according to the present invention.

FIG. 2 is a flowchart showing an operation of a positioning mechanism in the shearing machine shown in FIG.

FIG. 3 is a graph showing a moving state of a positioning member.

FIG. 4 is a table showing ON / OFF states of respective signals in FIG.

FIG. 5 is a block diagram showing an example of a second embodiment of a positioning mechanism in the shearing machine according to the present invention.

6 is a flowchart showing an operation of a positioning mechanism in the shearing machine shown in FIG.

FIG. 7 is a graph showing a conventional moving state of positioning.

[Explanation of symbols]

 1, 25 Positioning mechanism 3, 27 Control device (control means) 5 Inverter 7 Induction motor 9 Positioning member 15 Encoder (position detecting means) 17 Speed command section 19 Pulse oscillator 23 Adder (gate circuit) 41 Computing section

Claims (2)

[Claims] 1. An induction motor that drives a positioning member, an inverter that outputs a drive output command to the induction motor, a position detection unit that detects the position of the positioning member, and a position signal from the positioning unit. And a control means for controlling the inverter,
The control means issues a run signal for instructing on / off of a drive output instruction from the inverter and a speed instruction for determining a set frequency of the inverter itself, a pulse oscillator for issuing a pulse signal, and a pulse oscillator from the pulse oscillator. A positioning mechanism in a shearing machine, comprising: a gate circuit for interrupting a run signal to the inverter by a pulse signal. 2. An induction motor that drives a positioning member, an inverter that outputs a drive output command to the induction motor, a position detection unit that detects the position of the positioning member, and a position signal from the positioning unit. And a control means for controlling the inverter,
The control means issues a run signal for instructing on / off of a drive output command from the inverter and a speed command for determining a set frequency of the inverter itself, and a waveform for forming an output waveform of the run signal into an intermittent waveform. A positioning mechanism in a shearing machine, comprising a forming part.