JPH0831371B2 - Power supply for magnetic check - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for controlling an excitation voltage applied to an excitation coil of an electromagnet chuck, and more particularly to a power supply device capable of changing the value of the excitation voltage.

(Prior Art) In a magnetic chuck, especially an electromagnetic chuck, when the workpiece has low rigidity and is easily deformed and high machining accuracy is required, the excitation voltage is adjusted to adjust the physical characteristics of the workpiece. And it is necessary to set the optimum magnetic force corresponding to the shape. From this, an electromagnet chuck in which the value of the excitation voltage is variable and a power supply device therefor have been proposed.

As a power supply device for an electromagnet chuck that can change the value of the excitation voltage, a rectifier circuit that has a thyristor and performs full-wave rectification of alternating current and applies the rectified voltage to the excitation coil, and adjusts the value of the excitation voltage And a voltage setting device such as a variable resistor to be set, a push button switch that generates an excitation start signal that starts excitation of the excitation coil, and a push button switch that generates an excitation stop signal that stops excitation of the excitation coil, When the voltage value set in the voltage setter, the excitation start signal and the excitation stop signal are received, and the excitation start signal is received, the pulse shape of the timing corresponding to the voltage value set in the voltage setter A control circuit for supplying the control signal to the thyristor, and changing the value of the voltage setter to change the phase of the control signal with respect to the alternating current. Is allowed, thereby adjusting the value of the excitation voltage applied to the exciting coil by changing the time of turn-on of the thyristor, there is a power supply.

However, since this power supply device determines the phase of the control signal with respect to the alternating current based on the value set in the voltage setter, the voltage setting is performed when the electromagnet chuck is in the excited state. When the value of the device changes, the excitation voltage changes, which changes the magnetic force and changes the processing accuracy. Further, if the excitation voltage changes while the magnetic substance is attracted, the attracted magnetic substance may be released, which is dangerous.

(Object of the Invention) The present invention is directed to when the electromagnet chuck is in an excited state,
An object of the present invention is to provide a power supply device in which the excitation voltage does not change even if the set value of the setting means is changed.

(Constitution of Invention) The present invention is a power supply device for applying an excitation voltage to an excitation coil of an electromagnet chuck, and means for rectifying an alternating current to generate the excitation voltage and means for setting a value of the excitation voltage. And command means for generating an excitation start signal for instructing the start of excitation and an excitation stop signal for instructing to stop the excitation,
The voltage value set in the setting means, the excitation start signal and the excitation stop signal are received, and the voltage value set in the setting means by receiving the excitation start signal is stored, and the stored voltage value is stored. And a control unit that operates the excitation voltage generation unit to apply the excitation voltage having a value corresponding to the above to the excitation coil.

(Effects of the Invention) According to the power supply device of the present invention, the voltage value set in the setting means by receiving the excitation start signal is stored, and the stored voltage value is used to correspond to the stored voltage value. Since the excitation voltage of the value to be applied is applied, even if the set value of the setting means is changed when the electromagnet chuck is in the excited state, the next excitation start signal is input to the control means for the stored voltage value. Is not updated and the excitation voltage does not change. Therefore, it is possible to prevent the quality of the workpiece from being deteriorated and the danger of the workpiece due to the erroneous operation of the power supply device.

(Example) Hereinafter, the Example of this invention shown in drawing is described.

The power supply device 10 shown in FIG. 1 is connected to a terminal from a commercial AC power source.
Excitation current generation circuit 16 that rectifies the alternating current input to 12 and applies the rectified voltage to the excitation coil 14 as the excitation voltage.
And the voltage setter 18 that sets the value of the excitation voltage to be applied.
And a push button switch 20 for generating an excitation start signal for starting the excitation of the excitation coil 14 and a push button switch 22 for generating an excitation stop signal for stopping the excitation of the excitation coil 14.
A voltage value set in the voltage setter 18, the excitation start signal, the excitation stop signal and the AC power supplied to the terminal 12, the pulse-like having a predetermined phase with respect to the alternating voltage between the terminals 12 And a control circuit 24 for supplying a control signal, that is, a firing pulse to the exciting current generating circuit 16.

The exciting current generation circuit 16 includes a rectifier circuit 26 that uses a plurality of rectifier elements such as diodes, and a control rectifier element 28 that opens and closes a flow path of alternating current supplied to the rectifier circuit 26. The rectifier circuit 26 is a known full-wave rectifier circuit of the bridge type, and when a complete alternating current as shown in FIG. 2 (A) is input, it outputs a rectified signal shown in FIG. 2 (B). To do. The control rectifying element 28 is a thyristor arranged between the terminal 12 and the rectifying circuit 26 in the illustrated example, and the control circuit 24
Is turned on by supplying the ignition pulse from Instead of arranging the control rectifying element 28 between the terminal 12 and the rectifying circuit 26, a plurality of thyristors are connected to the rectifying circuit 26.
May be arranged as a rectifying element, and the rectifying element may be turned on by the pulse signal.

As the voltage setter 18, if the set value can be changed, for example, a variable resistor and A / A for converting the voltage value obtained from the variable resistor into a digital signal corresponding to the variable resistor
A known circuit including a D converter or a digital switch that outputs a set voltage value by a binary code can be used.

The control circuit 24 receives the alternating voltage supplied to the terminal 12 via the transformer 30, and detects the phase of the received alternating voltage, a phase detector 32, a clock signal generator 34, and a counter for counting the clock signal. 36, a memory 38 that stores the voltage value set in the voltage setting device 18, and a signal from the voltage setting device 18, the pushbutton switches 20, 22, the phase detector 32, and the counter 36, based on the alternating voltage. A processing circuit 40 that uses a microprocessor to generate a pulse signal having a phase relationship corresponding to the voltage value stored in the memory 38, and a control rectifying element that receives the pulse signal and receives the pulse signal.
And a drive circuit 42 for supplying an ignition pulse for igniting 28 to the controlled rectifying element 28.

The phase detector 32 outputs to the processing circuit 40 the zero-cross signal, that is, the phase detection signal shown in FIG. 2 (C), when the input alternating voltage is zero volt, that is, when the phase of the alternating voltage is 0 ° or 180 °. It is a zero-cross detector that outputs.

The counter 36 is a preset type counter,
When the clock signal from the clock signal generator 34 is counted by the number corresponding to the voltage value stored in the memory 38, that is, the time corresponding to the stored voltage value from the time when the phase detection signal is input to the processing circuit 40. When delayed by T (see FIG. 2), the timing signal shown in FIG. 2 (D) is supplied to the processing circuit 40.

Instead of providing the counter 36, the function of the counter 36 may be performed by the processing circuit 40.
The timing signal from 36 may be directly supplied to the drive circuit 42 without passing through the processing circuit 40. Further, instead of the memory 38, an internal memory of the processing circuit may be used.

Next, the operation of the power supply device 10 will be described with reference to FIG.

When the power is turned on, the processing circuit 40 initializes the device, stores the non-excited state in the memory 38, clears the counter 36, and monitors whether or not an operation signal is input. This operation is repeated until an operation signal, that is, an excitation start signal is input from the push button switch 20.

When the excitation start signal is input to the processing circuit 40 by operating the push button switch 20, the processing circuit 40 firstly stores in the memory 38 the voltage value set in the voltage setter 18 and the excitation state. After storing it in the memory, the process waits until the phase detection signal is input from the phase detection circuit 32.

When the phase detection signal is input to the processing circuit 40, the processing circuit 40
Reads each information stored in the memory 38, confirms that the read information includes an excitation state, sets a value corresponding to the read voltage value in the counter 36,
After the counter 36 is activated, it waits until the timing signal is input from the counter 36.

When the count value of the counter 36 reaches a predetermined value, the counter 36
Since the timing signal is supplied from the processing circuit 40 to the processing circuit 40, the processing circuit 40 supplies the pulse signal having the same phase as the input timing signal to the drive circuit 42. As a result, an ignition pulse is supplied from the drive circuit 42 to the controlled rectifying element 28, and the controlled rectifying element 28 is turned on with a delay corresponding to the voltage value stored in the memory 38 with respect to the alternating voltage.

The reading of information from the memory 38, the setting of the read voltage value to the counter 36, and the output of the pulse signal to the drive circuit 42 are performed until the operation signal by the push button switch 22, that is, the excitation stop signal is supplied to the processing circuit 40. ,Repeated.
During this time, the value set in the counter 36 is the value corresponding to the voltage value stored in the memory 38.
Even if the voltage value set in 18 is changed, the value set in the counter 36 is not changed.

As a result, when the alternating current shown in FIG. 2 (A) is supplied to the terminal 12, the phase detector 32 outputs the phase detection signal shown in FIG. 2 (C), and the counter 36 is shown in FIG. 2 (D). , The processing circuit 40 and the drive circuit 42 respectively output a pulse signal and a control signal having the same phase as the timing signal of FIG. 2 (D). As a result, the voltage waveform on the output side of the controlled rectifying element 28 becomes the waveform shown in FIG. 2 (E), and the output voltage waveform of the rectifying circuit 26 becomes the waveform shown in FIG. 2 (F). The output of the rectifier circuit 26 is used as an exciting voltage by the exciting coil 14
Is smoothed by the exciting coil 14, so that an exciting voltage having a value equal to the voltage value stored in the memory 38 is applied to the exciting coil 14.

When the operation signal, that is, the excitation stop signal is input to the processing circuit 40 by operating the push button switch 22, the processing circuit 40 erases the excitation state, then initializes the device, and the non-excitation state. The step of storing the information in the memory 38, clearing the counter 36, and monitoring whether or not the operation signal is input is performed by the excitation start signal of the push button switch 20.
Repeat until you enter.

It should be noted that while the electromagnet chuck is excited, when the push button switch is operated again, the excitation start signal is input to the processing circuit 40, that is, before the excitation stop signal is input to the control circuit 40. Even when such an excitation start signal is input to the control circuit 40, the voltage value stored in the memory 38 may be updated to the voltage value set in the voltage setter 18. To do so, for example, the "excitation state determination step" between the "excitation start signal determination step" and the "set voltage value and excitation state storage step" in FIG. Can be omitted.

[Brief description of drawings]

FIG. 1 is a block diagram of an electric circuit showing an excitation of a magnetic chuck power supply device of the present invention, FIG. 2 is a diagram showing a waveform of an electric signal, and FIG. 3 is an operation explanatory diagram. 10: Power supply device, 12: Commercial AC power input terminal, 14: Excitation coil, 16: Excitation current generation circuit, 18: Voltage setting device, 20: Excitation start signal push button switch, 22: Excitation stop signal push button Switch, 24: Control circuit, 26: Rectifier circuit, 28: Control rectifier element, 32: Phase detector, 34: Clock signal generator, 36: Counter, 38: Memory, 40: Processing circuit, 42: Drive circuit.

Claims (5)

[Claims] 1. A power supply device for applying an exciting voltage to an exciting coil of an electromagnet chuck, comprising: means for rectifying an alternating current to generate the exciting voltage; means for setting a value of the exciting voltage; Command means for generating an excitation start signal for instructing start and an excitation stop signal for instructing stop of excitation,
The voltage value set in the setting means, the excitation start signal and the excitation stop signal are received, and the voltage value set in the setting means by receiving the excitation start signal is stored, and the stored voltage value is stored. And a control unit that operates the excitation voltage generation unit to apply the excitation voltage having a value corresponding to the above to the excitation coil. 2. The control means stores the voltage value set in the setting means, and then stores the voltage value corresponding to the stored voltage value until receiving the excitation stop signal or a new excitation start signal. The power supply device for the magnetic chuck according to claim (1), which is a means for operating the excitation voltage generating means to apply a voltage to the excitation coil. 3. The exciting voltage generating means includes a control rectifying element operated by an electric signal, and the controlling means outputs a phase detection signal when the AC voltage has a predetermined phase angle, and a phase detector. Receiving the phase detection signal, the voltage value set in the setting means, the excitation start signal and the excitation stop signal, and storing the voltage value set in the setting means by receiving the excitation start signal, A circuit that generates a pulse signal delayed each time the phase detection signal is received, the time delayed corresponding to the voltage value stored from the time when the phase detection signal is received; and a circuit that receives the pulse signal and each time the pulse signal is received. The magnetic chuck power supply device according to claim 1, further comprising: a drive circuit that supplies a pulsed control signal for operating the control rectifying element to the control rectifying element. 4. The exciting voltage generating means includes a control rectifying element operated by an electric signal, and the controlling means outputs a phase detection signal when the alternating voltage has a predetermined phase angle, and a phase detector. A clock signal generator, receiving the clock signal, the phase detection signal, the voltage value set in the setting means, the excitation start signal and the excitation stop signal,
The voltage value set in the setting means by receiving the excitation start signal is stored, and each time the phase detection signal is received, the clock signal is counted, and the count value corresponds to the stored voltage value. And a drive circuit which receives the pulse signal and supplies a pulsed control signal for operating the controlled rectifying element to the controlled rectifying element each time the pulse signal is received. The power supply device for a magnetic chuck according to claim 1, further comprising: 5. The pulse signal generating circuit is a circuit for generating the pulse signal until the excitation stop signal or a new excitation start signal is received after the voltage value is stored.
The power supply device for a magnetic chuck according to claim (3) or (4).