JPS6130869B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an instantaneous tool, such as an electric tacker, an electric hammer for formwork, etc., which operates continuously by operating a start switch.

The conventional control device for this type of instantaneous tool is the first one.
It is configured as shown in the figure. In the figure, 1 is an AC power supply, 2 and 3 are an electromagnetic solenoid and a main thyristor connected in series, and both ends of the main thyristor are connected to both ends of the AC power supply 1. 4 is an auxiliary thyristor for gate triggering the main thyristor 3;
6 is a voltage dividing resistor, and the gate trigger of the main thyristor 3 is performed by the voltage drop occurring across the resistor 6. 7 is a capacitor that supplies an anode current to the auxiliary thyristor 4, and 8 is a charging diode for the capacitor 7. 9 is an astable multivibrator synchronized with the AC power supply 1; 10 is a stabilized power supply that supplies a constant voltage to the astable multivibrator 9; and 11 is the astable multivibrator 9.
This is a starting switch inserted between the output terminal of the thyristor 4 and the gate of the auxiliary thyristor 4. In the above configuration,
When the start switch 11 is turned on and changed from the state shown by the solid line to the state shown by the broken line, the gate of the auxiliary thyristor 4 is connected to the AC power supply 1 from the astable multivibrator 9.
A pulse having a repetition period that is an integral multiple of one cycle of the AC power source 1 is output in synchronization with the beginning of the positive half cycle of the AC power source 1, and the auxiliary thyristor 4 is inactive at the beginning of the positive half cycle of the AC power source 1. It is turned on at the same period as the stable multivibrator 9, discharging the charge of the capacitor 7 to the resistors 5 and 6, and the resulting potential difference generated across the resistor 6 causes the main thyristor 3 to turn on in response.
Therefore, the main thyristor 3 supplies the electromagnetic solenoid 2 with a current for approximately half a cycle of the AC power supply at the same period as the astable multivibrator 9. Since a plunger (not shown) or the like is sucked down by the excitation of the electromagnetic solenoid 2, a continuous blow can be obtained while the starting switch is turned on.

However, the conventional control device described above had the following drawbacks. That is, since the auxiliary thyristor 4 is gate-triggered by the pulse output of the astable multivibrator 9, the repetition period of the astable multivibrator 9 may be changed due to a temperature rise of the control device or fluctuations in the output voltage of the stabilized power supply 10. When deviates slightly from an integral multiple of one cycle of the AC power supply 1, the excitation force of the electromagnetic solenoid 2 changes due to the change in the energization angle α of the main thyristor 3, and a constant striking force is obtained during continuous operation. The drawback was that there was no. This situation is shown in FIG. In the figure, a represents the voltage waveform of the AC power supply 1,
The hatched area indicates the energization range of the main thyristor 3. b shows the pulse output state of the astable multivibrator 9.

In addition, this type of instant-actuation tool requires a control device built into the handle to avoid deterioration in handling and operability, but when an astable multivibrator is used as the oscillation device, the configuration usually requires two devices. Since it requires a transistor, two capacitors, and four resistors, and requires a stabilized power supply for its operation, the number of electronic components that make up the control device increases, making it possible to store them in the handle. Become. As a result, the control device has to be housed in a separate control box, which has the disadvantage of cluttering the control box during work and reducing the handling and operability of the tool.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to make it possible to obtain a constant continuous impact force in this type of instant action tool, and to simplify the configuration of the control device. The goal is to make it smaller and easier to store.

The present invention connects an auxiliary thyristor to the gate of a main thyristor that controls power supply to an electromagnetic solenoid that drives a plunger, and in which the main thyristor is subsequently turned on when the auxiliary thyristor is turned on, the anode of the auxiliary thyristor is An oscillation circuit consisting of a capacitor and a trigger diode is connected in series, and a pulse generation circuit is connected to the gate of the auxiliary thyristor to supply a gate trigger pulse that is always synchronized with the beginning of the positive half cycle of the AC power supply. . The present invention will be explained below based on the embodiments shown in FIG. 3 and below.

In FIG. 3, 11 is an AC power source, 12 and 13 are electromagnetic solenoids and main thyristors connected in series, both ends of which are connected to both ends of the AC power source 11. 14 is an auxiliary thyristor that performs a gate trigger of the main thyristor 13; 15 and 16 are resistors and Zener diodes connected in series with each other and both ends of which are connected to the AC power supply 11;
The cathode of the Zener diode 16 outputs a voltage obtained by clipping the AC voltage with the Zener voltage. Reference numerals 17 and 18 are a capacitor and a resistor that are connected in series with each other and both ends of which are connected in parallel to the Zener diode 16 to form a differential circuit, and the connection end thereof is connected to the gate of the auxiliary thyristor 14. A portion 19 surrounded by a broken line shows a pulse generation circuit, which constantly generates pulses synchronized with the beginning of the positive half cycle of the AC power supply 11 to the auxiliary thyristor 1.
Supply to gate 4. 20 is the main thyristor 13
It is a resistor for adjusting the gate impedance of 2
1 is a gate noise absorbing capacitor connected in parallel to the gate and cathode of the main thyristor 13. 22 is a capacitor that outputs a pulse to the anode of the auxiliary thyristor 14; 23 and 24 are resistors and Zener diodes that are connected in series with each other and both ends of which are connected to the AC power supply 11;
5 is a semi-fixed resistor connected between the cathode of the Zener diode 24 and the capacitor 22 for adjusting the charging time constant of the capacitor 22. 26 is a trigger diode with negative resistance characteristics, such as a trigger diode or a bidirectional diode thyristor;
In the discharge circuit of the capacitor 22, it is connected in series to the anode side of the auxiliary thyristor 14. 2
7 is a start switch. The Zener diode 24 is provided to keep the oscillation period of the capacitor 22 constant, and prevents fluctuations in the charging voltage of the capacitor 22 due to fluctuations in the power supply voltage, and also prevents changes in the charging time constant when the temperature of the control device rises. It has the function of correcting changes in the breakover voltage of the trigger diode 26.

In FIG. 4, the symbol Vcc indicates the dual voltage waveform of the AC power supply 11, and the symbol I _G1 indicates the gate trigger current waveform of the auxiliary thyristor 14. VB ₀ indicated by dashed line
indicates the breaker overvoltage of the trigger diode 26, and _Cv indicated by a solid line indicates the charging voltage of the capacitor 22. I _G2 indicates the anode current waveform of the auxiliary thyristor 14, and _IAK indicates the anode current of the main thyristor 13.

Next, the operation will be explained. Start switch 27
In the state shown by the solid line in which the voltage is not turned on, the capacitor 22 is charged through the resistors 23 and 25 to the Zener voltage of the Zener diode 24.
In addition, from the pulse generation circuit 19 to the auxiliary thyristor 14
A gate trigger pulse synchronized with the beginning of the positive half cycle of the AC power supply 11 is constantly supplied to the gate of the AC power supply 11. (FIG. 4, I _G1 ) However, since there is no anode current in the auxiliary thyristor 14, the thyristor is not turned on. Further, the output pulse of the pulse generating circuit 19 flows through the resistor 20 to the gate of the main thyristor 13;
The main thyristor 13 does not turn on because its gate trigger sensitivity is less than that of the auxiliary thyristor 14 and is partially absorbed by the capacitor 21.

When the start switch 27 is turned on and the state shown by the solid line is changed to the state shown by the broken line, the discharge circuit of the capacitor 22 is closed. Charging voltage C of capacitor 22
Since _V is higher than the breakover voltage of the trigger diode 26, the gate trigger of the auxiliary thyristor 14 prepares the charge on the capacitor 22 to be discharged to the gate of the main thyristor 13. A gate trigger is given to the auxiliary thyristor 14 by the output pulse ○I of the pulse generating circuit 19 which is passed for the first time after the start switch 27 is turned on, and the trigger diode 26 breaks down and the auxiliary thyristor 14 is turned on.

Therefore, the charge in the capacitor 22 is discharged through the start switch 27, the trigger diode 26, the auxiliary thyristor 14, and the resistor 20 to the gate of the main thyristor, and the main thyristor 13 is discharged at the beginning of the positive half cycle of the AC power supply 11. Turn on at
Approximately half a cycle of current is supplied to the electromagnetic solenoid 12. By energizing the electromagnetic solenoid 12, a plunger (not shown) is sucked down and the first impact is performed. (FIG. 4, IG ₂ , I _AK ) As the discharge of the capacitor 22 progresses and its discharge current decreases, the trigger diode 26 recovers its blocking ability and the discharge of the capacitor 22 stops. Thereafter, the charging voltage of the capacitor 22 increases at a rate determined by the time constant of the charging circuit, and reaches the breakover voltage of the trigger diode 26 again after a time period corresponding to several to several tens of cycles of the AC power supply 11. (Fig. 4, VBO, _Cv ) A gate trigger is given to the auxiliary thyristor 14 by the output pulse ○ and ○ of the pulse generation circuit 19 that is passed thereafter, and the trigger diode 26 breaks down and the auxiliary thyristor 14 is turned on. In response to this, the main thyristor 13 is turned on, supplying approximately half a cycle of current to the electromagnetic solenoid 12. The second impact is performed by energizing the electromagnetic solenoid 12. When the start switch 27 is continued to be turned on, the electromagnetic solenoid 12 is continuously excited at a cycle slightly longer than the time to by the same operation as described above, and continuous strikes are obtained.

As is clear from the above description, the time to does not need to have a period that is an exact integer multiple of one cycle of the AC power supply, unlike the oscillation period of the monostable multivibrator of the prior art, and the time to Even if the constant, the breakover voltage of the trigger diode 26, the characteristics, etc. change, the electromagnetic solenoid 12 is always supplied with current for approximately the positive half cycle of the AC power supply 11, and a constant striking force can be obtained during continuous operation. It is.

Further, in the above embodiment, the semi-fixed resistor 25
A desired striking cycle can be obtained by adjusting the resistance value. Therefore, if a resistance value adjustment knob for the semi-fixed resistor 25 is provided on the handle of the tool, it becomes possible to easily select the optimum striking cycle for the work, and work efficiency can be greatly improved. can.

In addition, in the present invention, the portion 28 surrounded by a broken line
By adding , it is possible to make the striking force stronger and to modify it so that a constant striking force can be obtained even if the power supply impedance fluctuates. 29 is an electromagnetic solenoid, and 30 is a thyristor, which are connected in series, and both ends of which are connected to both ends of the AC power source 11. The thyristor 30 is connected to the AC power supply 11 with a polarity opposite to that of the main thyristor 13. 31 is a diode, 32 and 33 are voltage dividing resistors connected in series with each other and both ends thereof are connected in parallel to the electromagnetic solenoid 12, and the diode 31 is connected between the connected end and the gate of the thyristor 30. . In this embodiment, the electromagnetic solenoid 12 and the electromagnetic solenoid 29 are supplied with current in successive positive and negative half cycles, and a plunger (not shown) is successively suctioned and lowered by the two electromagnetic solenoids. It is something. In this embodiment, when the start switch 27 is turned on, the main thyristor 1 is turned on at the beginning of the positive half cycle of the AC power supply 11.
3 turns on and supplies current to the electromagnetic solenoid 12 for a positive half cycle, and furthermore, when the current supplied to the electromagnetic solenoid 12 passes the peak value, the potential across the electromagnetic solenoid becomes opposite to that of the main thyristor 13. The anode side becomes high potential,
A gate trigger current flows through the thyristor 30.
The thyristor 30 turns on at the beginning of the negative half cycle following the positive half cycle of the AC power supply 11 in which the main thyristor 13 is energized, and transfers the current over the negative half cycle to the electromagnetic solenoid 29.
to supply power.

As described above, the present invention makes it possible to obtain a constant impact force during continuous operation, and also to obtain continuous operation with a simple circuit configuration, so that the control device can be miniaturized and easily attached to the handle of a tool, etc. This has the effect that it can be stored in

[Brief explanation of the drawing]

FIGS. 1 and 2 are electrical circuit diagrams of a conventional control device for an instantaneous action tool, and waveform diagrams of each part thereof,
FIG. 3 is an electric circuit diagram showing a specific embodiment of a control device for an instantaneous action tool according to the present invention, and FIG. 4 is a timing chart showing waveforms of various parts in FIG. In the figure, 11 is an AC power supply, 12 is an electromagnetic solenoid, 13 is a main thyristor, 14 is an auxiliary thyristor, 19 is a pulse generation circuit, 22 is a capacitor,
26 is a trigger diode.

Claims (1)

[Claims] 1 A main thyristor and an electromagnetic solenoid connected in series to both ends of an AC power source, an auxiliary thyristor that performs a gate trigger of the main thyristor, and a pulse that constantly supplies a gate trigger pulse synchronized with the AC power source to the gate of the auxiliary thyristor. 1. A control device for an instantaneous action tool, comprising: a generating circuit; a capacitor; and a discharging circuit for the capacitor that discharges the charge in the capacitor to the auxiliary thyristor via a charging circuit for the capacitor and a trigger diode.