JP2507474B2 - Power supply for electronic beam welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to heavy electric machinery, welding of thick steel plates of machines, electrical equipment requiring low strain, mechanical parts, and electronic materials used for welding dissimilar metals. The present invention relates to a power source device for a beam welding device.

[Conventional technology]

Conventionally, the one that can be put into practical use for shutting down and controlling the electron acceleration high voltage when an arc discharge occurs is a high-voltage vacuum tube, but a high-voltage vacuum tube has a deterioration in performance due to the life of the filament, the decrease in the degree of vacuum, etc. Therefore, it has a short life such as about 1,000 hours, and it is difficult to improve the operating rate of the device, and there are drawbacks such as a large cost and a large loss.

[Problems to be solved by the invention]

In conventional electron beam welding equipment, when arc discharge occurs at the electron acceleration high voltage application part due to metal vapor and impure gas during welding, overcurrent continues, so the protection circuit operates and shuts off the low voltage side. Caused the electron acceleration high voltage to be cut off. The re-welding was done manually. In this conventional method, the low voltage side is shut off by an electromagnetic contactor, etc.
The energy is stored in the capacitor of the high voltage part in a long time, and the energy accumulated in the capacitor of the high voltage part is consumed by the arc discharge, so that the electron gun is largely damaged by the arc discharge. Since the time until re-welding is long, the molten metal in the welded portion solidifies and becomes a defect. In addition, the method of shutting off the electron acceleration high voltage by using a high-pressure vacuum tube has a long service life of the filament and deterioration of the degree of vacuum, which makes it difficult to operate for a long time.

In order to solve the above problems, the present invention reduces arc discharge energy by high-speed high-voltage interruption, prevents damage to the electron gun, and realizes a long life.

[Means for solving problems]

Insert a pulse transformer in series with the electron acceleration high voltage source,
During normal welding, a voltage that cancels the ripple voltage in the electron acceleration high voltage is applied to obtain a smooth electron acceleration high voltage.

When the arc discharge occurs, the electron acceleration high voltage source is short-circuited by the arc, and the electron acceleration high voltage decreases.
The decrease is detected, and a voltage reverse to the electron acceleration high voltage is generated to reduce the arc discharge so that the voltage becomes equal to or lower than the voltage at which the arc discharge is decreased in the pulse transformer.

Since the ions generated by the arc discharge are extinguished in a few milliseconds, the electron accelerating high voltage is reapplied and rewelded by setting the voltage of the pulse transformer to 0 after a few milliseconds.

If it is cut off for a few milliseconds, the molten metal does not solidify and no welding defect occurs. Further, since the reverse voltage is cut off on the high voltage side, the amount of energy accumulated in the capacitor of the high voltage portion is consumed by the arc discharge, and the damage to the electron gun can be reduced.

[Action]

The present invention relates to an arcing control circuit for detecting and interrupting arc discharge due to a decrease in electron acceleration high voltage due to arc discharge, generating a re-applied pulse signal, a drive transistor for amplifying a pulse signal, and driving a low voltage side of a pulse transformer. Electron acceleration A ripple control circuit that detects the ripple voltage of high voltage and generates a signal to reduce the ripple, and a pulse transformer that boosts the pulse signal amplified by the drive transistor to a high voltage pulse. And an electron acceleration high voltage power supply for generating an electron acceleration high voltage.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The constant voltage control circuit 1 for detecting the electron acceleration high voltage by the voltage divider 11 to control the electron acceleration high voltage to be constant, the electron acceleration high voltage power supply 2 for generating the electron acceleration high voltage, which is the high voltage transformer 3, It is composed of a high-voltage rectifier 4 and a high-voltage capacitor 5.

At the time of arc discharge, in order to extinguish the arc, a high-voltage reverse voltage pulse and a pulse transformer 6 for generating a voltage for reducing ripples in an electron acceleration high voltage, a drive circuit 7 for driving the pulse transformer, which is a drive transistor. 8 and drive power supply 12.

The ripple control circuit 9 detects the ripple voltage in the electron acceleration high voltage by the voltage divider 11 and amplifies only the ripple voltage,
A current is passed through the drive transistor 8 so as to reduce the ripple voltage, and a voltage for canceling the ripple voltage is generated on the high voltage side of the pulse transformer 6.

The arcing control circuit 10 causes arc discharge due to impure gas, metal vapor, etc. between the cathode 13 and the anode 15 of the electron gun 12 to which the electron acceleration high voltage is applied, and the electron acceleration high voltage drops. Is detected by the voltage divider 11 and a pulse current of several milliseconds is passed through the drive transistor 8 to generate a pulse voltage for canceling the electron acceleration voltage on the high voltage side of the pulse transformer 6 to reduce the arc discharge.

The grid 14 is an electrode that controls the electron beam current 16, and the work 17 is a metal that is welded by the electron beam current 16.

The operation of the present invention will be described with reference to the embodiment shown in FIG. 1 and the operation example shown in FIG.

In FIG. 2, during normal welding, the ripple voltage shown by the broken line in the electron acceleration high voltage is detected by the voltage divider 11 and amplified by the ripple control circuit 9 to generate a ripple control output. A voltage is generated to cancel the ripple voltage indicated by the broken line of the electron acceleration voltage to obtain a smooth voltage indicated by the solid line.

When the arc discharge occurs at the point, the electron acceleration high voltage decreases, and when it decreases to the arc discharge detection voltage, the arcing control circuit 10 operates and t1 as in the arcing control circuit output.
A current is passed through the time drive transistor 8 to generate a voltage indicated by the pulse transformer high voltage side on the high voltage side of the pulse transformer 6, and the electron acceleration high voltage is lowered until the arc discharge is extinguished. The t1 time is set to 5 to 20 msec at which ions generated by the arc discharge are extinguished.

After t1 hours, the arcing control circuit output is set to zero for t2 hours, the electron acceleration high voltage is reapplied, and if the electron acceleration high voltage does not rise to the arc discharge detection voltage at t2 hours, it is detected as rearcing, and again t1 hours. Cut off.

 If the electron acceleration high voltage rises, normal welding is achieved.

According to this embodiment, since the ripple voltage is reduced by the pulse transformer, even if the capacity of the high-voltage capacitor is small, a smooth electron acceleration high voltage is generated and the capacity of the high-voltage capacitor becomes small, so that the arc discharge is reduced. The energy of time is also reduced, and the damage of the electron gun is reduced.

〔The invention's effect〕

According to the present invention, a pulse transformer that does not deteriorate the performance of the filament due to the deterioration of the vacuum degree can be used to quickly interrupt the arc discharge generated at the portion to which the electron acceleration high voltage is applied, so that the damage to the electron gun is reduced. it can. Also, a few meters
Since it can be reapplied and re-welded in seconds, defects in the weld will not occur.

[Brief description of drawings]

FIG. 1 is a system diagram of one embodiment of the present invention, and FIG. 2 is an operation waveform diagram of the present invention. 1 ... Constant voltage control circuit, 2 ... Electron acceleration high voltage power supply, 3
...... High voltage transformer, 4 ...... High voltage rectifier, 5 ...... High voltage capacitor, 6 ...... Pulse transformer, 7 ...... Driving circuit, 8 ......
Drive transistor, 9 ... ripple control circuit, 10 ... arcing control circuit, 11 ... voltage divider, 12 ... electron gun, 13 ...
… Cathode, 14 …… Grit, 15 …… Anode, 16 ……
Electron beam current, 17 ... work.

Claims (2)

(57) [Claims] 1. In an electron beam welding apparatus, arc discharge generated at an electron acceleration high voltage applying section is detected, and a reverse voltage for canceling the electron acceleration high voltage is generated by a pulse transformer to interrupt the arc discharge. Characteristic electron beam, power supply for welding equipment. 2. The pulse transformer according to claim 1, wherein a voltage for canceling ripples in the electron acceleration high voltage is generated to reduce the ripples in the electron acceleration high voltage. Power supply unit for electron beam welding equipment.