JPH0359679B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a micro-inching device for machine tools, etc., and more specifically, for example, when moving a back gauge in a shearing machine, a press brake, or a ram in a press with high precision by an inching operation. The present invention relates to a suitable micro-inching device.

Conventionally, when moving a back gauge or the like at high speed using a general three-phase induction motor, for example, the amount of movement becomes large, making it impossible to perform minute positioning by inching operations. Therefore,
Minute positioning of back gauges, etc. is performed using a pole change motor, a motor with a transmission, or a DC motor as the drive source, but these motors have drawbacks such as the complicated configuration and the high cost. It was hot.

The present invention provides a micro-inching device capable of positioning a movable object such as a back gauge by inching operation at high speed and with high precision even when using a very common three-phase induction motor, and capable of minute positioning. The purpose is to

A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an electric circuit diagram in one embodiment of the present invention, and FIG. 2 shows a control section of the micro-inching circuit in FIG. 1.

In FIG. 1, a drive source M is a drive source for a moving body to be minutely positioned. This drive source M is a drive source for a micro-inching device, such as an electric back gauge or an electric front gauge, and may be a very common three-phase induction motor.

Terminals R, S, and T are terminals connected to a three-phase AC power source, and are connected to the drive source M via lines l _R , l _S , and l _T, respectively.

Each of the lines l _R , l _S , and l _T is provided with a responsive switch of a control means for controlling supply cutoff of power to the driving source M. In the case shown, each normally open contact MSF ₁ of the relay MSF described below is connected to the line
It is inserted in l _R , l _S , and l _T. In addition, each normally open contact MSR ₁ of the relay MSR to be described later is connected to the terminal T side of the normally open contact MSF ₁ inserted in the line l _T and the drive source M of the normally open contact MSF ₁ inserted in the line l _R. between the terminal _R side of the normally open contact MSF ₁ inserted in the line l R and the drive source M side of the normally open contact MSF ₁ inserted in the line l _T , and between the terminal R side of the normally open contact MSF ₁ inserted in the line l are connected in parallel with the normally open contact MSF ₁ .

Note that Th is a thermal relay.

One end of a first switching contact PB1 of a run button (PB) ₁ is connected to a line l1 connected to, for example, terminal R of the terminals R, S, and T. The other end of this first switching contact PB1 is the switch SW
is connected to one end of each of the first and second switching contacts SW ₁ and SW ₂ .

The above switch SW is its first switching contact
A state in which SW ₁ is closed, a state in which the second switching contact SW ₂ is closed, and any switching contact SW ₁ ,
It can be operated in three switching states, including the state in which SW ₂ is also opened. The other end of the first switching contact SW ₁ is connected to a line l ₂ connected to, for example, the terminal S of the terminals S and T via the normally closed contact MSR ₂ of the relay MSR and the relay MSF.
Further, the other end of the second switching contact SW ₂ is connected to the line l ₂ via the normally closed contact MSF ₂ of the relay MSF and the relay MSR.

In the example shown, the relay as the control means mentioned above
Regarding the MSR, a control part CO of the micro-inching circuit is provided. In this embodiment, the interface 3 in the control unit CO is connected to the aforementioned line l ₂ via the second switching contact PB ₂ of the operation button 1 .

An SSR (solid state relay) 5 in the control unit CO is connected between the line _l1 and one end of the relay MSR.

Next, in FIG. 2, the interface 3
is connected to terminal ta. This interface 3 is a circuit that detects whether the start signal is on or off (presence or absence), and converts alternating current from terminal ta into direct current.
Gives a signal at a logic level. The output of the interface 3 becomes "0" when there is no activation signal, and becomes "1" when the activation signal is received.

The terminal tb is a terminal to which an alternating current input, for example, AC100V, is supplied, and the zero point detector 7 is connected to this terminal tb. This zero point detector 7, as described later,
This circuit generates a pulse of approximately 1 ms, for example, when an AC input passes through a zero cross point.

The D input terminal of the DFF (delay flip-flop) 9 is connected to the above-mentioned interface 3, and the C input terminal is connected to the above-mentioned zero point detection circuit 7. As will be described later, this DFF 9 is a circuit in which the Q output rises at the above-mentioned zero cross point at any timing with respect to the input waveform. DFF9 is
This is necessary when the start signal is not at the zero cross point of the AC input when the operation button 1 is pressed, and as described later, even if the output signal "1" of the interface 3 is input to the D input terminal, the C No output is output to the Q output until one pulse of the output pulse signal from the zero point detector 7 is input to the input terminal, and the output is held in the "0" state, and when a pulse is input to the C input terminal. The Q output becomes "1" starting from .

Inverter 11 is connected to DFF9,
Invert the output signal from DFF9.

A reset terminal of the counter 13 is connected to the inverter 11, and an input terminal thereof is connected to the zero point detector 7. This counter 13 is a circuit that counts how many times the above-mentioned zero cross point has passed.
A setting device 15 is connected for presetting the number of pulses to be passed.

In other words, the output signal from the above DFF9 is "1"
is inverted by the inverter 11 and supplied to the reset terminal of the counter 13, so that the counter 13 becomes the initial state of "0", and when the counter 13 is reset, a zero cross occurs at the next zero cross point as described later. The pulse signal is set by the setting device 15, for example, “3” in the setting device 15.
In the case of presetting, only three pulses are allowed to pass, and when the pulse signal passes, the counter 13 finishes counting and outputs "1".

The inverter 17 is connected to the counter 13 and inverts the output signal from the counter 13.

One input terminal of the AND circuit 19 is connected to the aforementioned
The other input terminal is connected to the inverter 17. As will be described later, the AND circuit 19 outputs a signal obtained by ANDing the output signal of the DFF 9 and the output signal of the inverter 17, and controls the above-mentioned SSR 5 on and off using this output signal.

To explain the operation of the circuit with the above configuration, first, in FIG. 1, when the switch SW is operated from the illustrated state, that is, the OFF state, so that the first switching contact SW ₁ is closed, the relay MSF is activated. The first switching contact PB ₁ in the closed state of the button 1, the lines l ₁ , l ₂ via the normally closed contact MSR ₂ of the relay MSR
It is connected between the two and turned on. Therefore, the relay
Each normally open contact MSF ₁ of the MSF is closed, the drive source M is operated, and the movable body is thereby moved, for example, to the positive side.

Conversely, if the switch SW is operated from the state shown in the figure so that the second switching contact SW ₂ is closed, the relay MSR is turned on in the same way.
Each normally open contact MSR ₁ of relay MSR will be closed. Therefore, in this case, 2 of the 3-phase AC power supply
Since the phases are reversely connected and supplied to the driving source M, the driving source M operates in the opposite direction to that described above, and the movable body is also moved to the negative side opposite to that described above.

Here, in this example, the relay as above
The MSR is further controlled by the aforementioned control unit CO to perform minute positioning of the moving object.

In other words, in Figure 3, when controlling with a pulse signal of a constant width as shown in Figure B, regardless of the input waveform shown in Figure A, the relay The suction speed and force of the contacts become inconsistent. Therefore, even if the operation button is operated in the same way, the amount of movement of a movable body such as a back gauge due to inching changes depending on the position at which the pulse rises.

Therefore, in this embodiment, the pulse always rises at the zero-crossing point Z of the input waveform of A in the figure, as shown in C in the same figure, so that the operation timing of the relay MSR is kept constant.

FIG. 4 shows the operation sequence of micro-inching, which will be explained below with reference to FIG.

In FIGS. 1 and 2, it is assumed that the second switching contact PB ₂ of the operation button 1 is in an open state, and that no activation signal is applied to the interface 3. Therefore, in FIG. 2, the output of interface 3 is "0", so DFF9
The Q output of the inverter 11 is also "1", the output of the counter 13 is "1" since it is in the state before the reset, the output of the inverter 17 is "0", and therefore the output of the AND circuit 19 is also "1". "0"
And SSR5 is turned off.

It is also assumed that, for example, 3 is preset in the setting device 15 as the number of pulses to be passed.

Here, when the run button 1 is pressed, a start signal is input to the interface 3 by closing the second switching contact _PB2 . The zero point detector 7 receives an AC input as shown in FIG. A pulse signal of 1 is obtained.

In the above interface 3, when the activation signal is input, the output becomes "1", and this output signal becomes DFF9.
is applied to the D input terminal of. In this DFF9,
If the start signal is not at the zero cross point of the AC input when the operation button 1 is pressed, that is, the rising edge of the output signal "1" of the interface 3 is at the 4th point.
As shown by the broken line in Figure C, if it is not the zero cross point of the AC input in Figure A, the Q output of this DFF9 is still in the "0" state, and the zero point detection is supplied to the C input terminal of DFF9. When pulse P ₁ of the output pulse signal shown in FIG. 4B of the device 7 is applied, the Q output of the DFF 9 becomes "1", and the DFF
The output signal of 9 is as shown by the solid line in FIG. 4C.

Next, the output signal "1" of this DFF9 is applied to one input terminal of the AND circuit 19, and
It is supplied to the inverter 11.

This inverter 11 inverts the output signal "1" of the DFF 9 shown by the solid line in FIG. 4C, and applies the output to the reset terminal of the counter 13. Here, by applying the output signal from this inverter 11 to the reset terminal, the counter 13 becomes the initial state of "0", the output of the counter 13 becomes "0", and the output signal of this counter 13 becomes "0". ” is supplied to the inverter 17.

In the above inverter 17, this counter 1
The output signal "0" of the circuit 3 is inverted and its output "1" is applied to the other input terminal of the AND circuit 19. Therefore, in this AND circuit 19, the signal "1" is applied to both input terminals when "1" is obtained at the output of the DFF 9, and the output is determined by the logical product of these signals. becomes "1", and the SSR 5 is turned on by the output signal of the AND circuit 19 as shown in FIG. 4E.

Therefore, the above-mentioned relay MSR is energized by the AC power supplies of lines l ₁ and l ₂ via this turned-on SSR 5, and as shown in FIG. It turns on in sync with the point. When the relay MSR is turned on, its normally open contacts MSR ₁ are closed as described above, and the drive source M is operated to move the movable body in the same negative direction as described above.

On the other hand, when the counter 13 is reset as described above, the input terminal of the counter 13 receives the signal shown in FIG.
Since the output signal of the zero point detector 7 is supplied, as shown in FIG. When the pulse signal passes only 3 pulses, the counter 13 finishes counting the preset number 3 and outputs "1".
issue.

The output signal "1" of this counter 13 is inverted by an inverter 17 to become a signal "0", and the output signal "0" of this inverter 17 is supplied to an AND circuit 19. Therefore, when the counter 13 finishes counting three pulses, the signal from the inverter 17 becomes "0" and the AND circuit 19
Since the output signal from is also “0” again, the above
SSR5 is turned off as shown in Figure 4E, and the relay
The MSR is also turned off as shown in Figure F. In addition,
SSR5 may use thyristors. Using a thyristor allows it to turn off at the zero point.

Also, looking at the operation of relay MSR, first a start signal is input, and when "1" is obtained at the output of DFF9, SSR5 is turned on, and relay MSR is turned on, but there is actually a closing time, so the micro-inching time is is approximately 5ms.

In addition, in micro-positioning of a moving object such as a back gauge using the above-mentioned micro-inching device,
By presetting the minimum value 1 in the setting device 15, the counter 13 allows only one pulse to pass, so that a moving object such as a back gauge moves by an amount of movement per pulse, for example, about 0.03 mm. Therefore, this inching operation allows accurate positioning of the moving body.

Although the interface 3 is used in the above embodiment, it is not necessary if the activation signal can be directly obtained as a DC signal. Furthermore, although a case has been shown in which the driver M is driven using a three-phase AC power source, the micro-inching method of the present invention can be similarly adopted when a single-phase AC power source is used.

As can be understood from the above description of the embodiments, the present invention is an apparatus for performing micro-inching of a three-phase induction motor M, and a line l _R connecting the motor M to a three-phase alternating current,
A control unit that provides a normally open contact MSR ₁ of the relay MSR in each of l _S and l _T , and controls the excitation of the above relay MSR.
CO has a zero point detector 7 that detects the zero cross point of AC and outputs a pulse, and a switch contact PB _2.
Input signal due to ON operation of and the above zero point detector 7
The relay MSR is activated by inputting a pulse signal from
a counter 13 that counts the number of output pulses from the zero point detector 7 and stops energizing the relay MSR when the number becomes equal to a set value; and a set value of the counter 13. and a setting device 15 for setting in advance.

As is clear from the above configuration, in the present invention, it is possible to perform micro-inching operation of the three-phase induction motor M. The energization time during inching can be adjusted arbitrarily.
Therefore, for example, in the initial stage, the energization time is relatively long and the inching operation is performed, and in the final stage, the energization time is shortened and the inching operation is performed, thereby making it possible to perform efficient and accurate positioning. It is.

Note that this invention is not limited to the above-mentioned embodiments, and the invention can be implemented in modes other than the above-mentioned embodiments. It does not limit the technical scope.

[Brief explanation of drawings]

FIG. 1 is an electrical circuit diagram of an embodiment of the present invention;
2 is a block diagram showing the control section of the micro-inching circuit in FIG. 1, FIG. 3 is a signal waveform diagram for explaining the present invention, and FIG. FIG. 3 is a signal waveform diagram for explaining the operation order. MSR...Relay, CO...Control unit, 7...Zero point detector, 13...Counter, 15...Setter.

Claims (1)

[Claims] 1 A device for performing micro-inching of a three-phase induction motor M is provided, and a normally open contact MSR ₁ of a relay MSR is provided on each of the lines l _R , l _S , and lT that connect the motor M to a three-phase AC power source, and the relay MSR The control unit CO that controls the excitation of the MSR has a zero point detector 7 that detects the zero cross point of AC and outputs a pulse, and an input signal from the ON operation of the switch contact PB ₂ and the zero point detector 7. An energizing means 9 energizes the relay MSR by inputting a pulse signal, and a energizing means 9 that energizes the relay MSR when the number of output pulses from the zero point detector 7 is counted and becomes equal to a set value.
A micro-inching device comprising: a counter 13 that acts to stop energization to the MSR; and a setting device 15 that presets the set value of the counter 13.