JPS61107646A - Electron beam processing machine - Google Patents

Abstract

PURPOSE:To interrupt operation of the captioned machine when electrical discharge is produced in an electron gun by detecting a current flowing in a circuit and voltage applied to load, and operating a high-tension interruption device in a state thereof insulated from an earth by means of optical fibers. CONSTITUTION:A high-tension main circuit of an electron beam processing machine is adapted to have a high-tension power source 1, an electron gun 2, and a high-tension interruption device 3, and adapted to interrupt operation of the electron gun 2 by making use of the high-tension interruption device 3 when electrical discharge is produced in the electron gun 2, and return it to an original state after the elapse of prescribed time for protecting the device. A control circuit 4 thereupon receives signals from a beam current detector circuit 6 disposed serially between the high-tension power source 1 and an earth and an accelerating voltage detector circuit 7 arranged parallely to the high-tension main circuit for controlling the high-tension interruption device 3 with use of optical fibers 5. Accordingly, a problem of dielectric strength of the device against the earth can be eliminated to prevent any electrical discharge form being produced in the electron gun 2 for applying the captioned machine with ease to existing processing machines.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an electron beam processing machine, and particularly to an electron beam processing machine that prevents discharge occurring within an electron gun and does not require modification of a high-voltage power supply in consideration of voltage resistance. The present invention relates to an electron beam control device suitable for application to conventional machines.

[Background of the invention]

The closest known example of the present invention was compiled in Japanese Patent Publication No. 48-27278. This technology detects the high-voltage circuit current when a discharge occurs in the electron gun, and if this value exceeds the current limit of 0.6 people, the electron gun is shut off in less than 25 microseconds ( turn-off), return after 35 milliseconds (
It was developed with the aim of protecting the equipment due to overload by providing a control device for the high voltage circuit that can be turned on and off.

This conventional example has three problems.

First, in high-voltage circuits, the withstand voltage of each device with respect to grounding becomes a major problem. When applying this conventional technology to an existing electron beam processing machine, it is theoretically necessary to place a device that interrupts and controls the electron beam in series between the negative side of the high-voltage power supply and the electron gun. This is difficult due to the problem of its own withstand voltage, and a control device must be placed in series between the positive side of the high-voltage power supply and ground. However, in this case, it becomes necessary for the high-voltage power supply to have a withstand voltage higher than the power supply voltage, which requires significant modification or replacement of the high-voltage power supply.

Second, when using this technology, in an electron beam processing machine with an accelerating voltage of 30 kV or more, if the turn-off time is less than 25 microseconds, the surge voltage will be large, and the parts of the electronic control circuit will be affected by the L of the high voltage circuit. Destroyed by surge.

Thirdly, with the interruption elapsed time of 35 milliseconds according to the present technology, weld continuity cannot be maintained in horizontal penetration welding of, for example, 100 mm IJ thickness, resulting in void defects.

As a result of the above, currently it is necessary to significantly modify the high-voltage power supply when applying it to conventional machines, and furthermore, it is not possible to prevent welding defects such as voids that occur in the welded part due to the generation of electrical discharge during welding. .

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, to prevent discharge from occurring in the electron gun during electron beam processing, to obtain good processing results, and to be easily integrated into existing electron beam processing machines. An object of the present invention is to provide an applicable electron beam control device Ct.

[Summary of the invention]

In order to achieve such an object, the present invention provides a high-voltage electric circuit composed of a high-voltage power supply of an electron beam processing machine and an electron gun, which is a load of the electron beam processing machine, and a current flowing in the circuit. The voltage applied to the load is detected, and the detection signal is transmitted from the control circuit of the high-voltage cut-off device to the high-voltage cut-off device having a large potential difference with respect to the ground while being insulated from the ground by using, for example, an optical fiber. By doing so, it is possible to place the cutoff and control mechanism 1111, which cuts off the high-voltage electric circuit for a selected period of time and stops the operation of the electron gun, between the negative side of the voltage power supply and the electron gun, which is the load of the power supply. .

[Examples of inventions]

Hereinafter, the invention will be described in detail based on illustrated embodiments. FIG. 1 is a block diagram of one practical example of the present invention. In the figure, in the electron beam processing machine, a high voltage power supply 1, an electron gun 2, and a high voltage cutoff device 3 constitute a high voltage main circuit. The high voltage cutoff device 3 turns on and off the high voltage main circuit in response to a signal from the control circuit 4. Here, the optical fiber 5 is used to transmit the 4H signal from the control circuit 4 to the high voltage cutoff device 3. Also, the signal sent to the control circuit 4 is high voltage!
, a beam current detection circuit 6 arranged in series between the source 1 and ground, and an acceleration voltage detection circuit 7 arranged in parallel with the high voltage main circuit.

Current detection circuit 6 and solder pressure detection circuit lol! A specific example in which the control circuit 4 is driven by the signal r7 is shown in FIG.

FIG. 2 shows a high-voltage isolation system #, which is constructed by connecting N high-voltage power supplies 1, electron guns 2, and high-voltage semiconductor modules 9 in series;
3 is used as the high voltage main circuit. Each high voltage semiconductor module 9 is protected from surges by a surge absorber 10. The driving power for the high voltage semiconductor module 9 is sent via an isolation transformer 11 and an inverter 12.

The isolation transformer 11 is 51. Power is supplied from a droplet source 13.

The turn-on and turn-off of the high-voltage semiconductor module 9 is controlled by the LED transmitter circuit 14, and a light trigger is transmitted from the LED 15 in the LED transmitter circuit 14 through the original fiber 5 to the light receiving diode 1 of the cylindrical half-shaped module 9.
6.

In this embodiment, the signals sent to the LED oscillation circuit 14 are generated by the beam current detection circuit 6 and the acceleration voltage detection circuit 7.

Discharge control during electron beam welding using this embodiment will be explained below.

In a steady state in which no discharge occurs, the high-voltage cutoff device 3 is in a conductive state, and a turn-on signal is sent to the LED circuit 14. When abnormal discharge occurs within the electron Vcz, the output voltages of the beam current detection circuit 6 and the voltage detection circuit 7 change. Changes in the output voltage of the beam current detection circuit 6 are determined by the setting voltage of the voltage setting device 17 and the beam current comparison circuit 18.
are compared and output a DC output signal. Further, the change in the output voltage of the accelerating voltage detection circuit W&7 is compared with the set voltage of the voltage setting device 19 by an accelerating voltage comparison circuit 20 to output a DC output signal. The output signal of the multivibrator 21 is generated by selecting one of the above output signals, operates the photocoupler 22, and connects the NOT circuit 23 in the LED transmitting circuit 14.
The signal is inverted, turning off transistor 24. As a result, the light receiving diode 16 in the high-voltage semiconductor module 9 connects the base 11tR of the transistor 17 through the optical fiber 5.
Set the 8FET260 gate voltage below the cutoff voltage,
All MO in the high-voltage semiconductor module 9 according to the principle shown in FIG.
Turn off the 8FET. By performing this operation simultaneously for N high voltage semiconductor modules 9, the high voltage cutoff device 3 can cut off the high voltage circuit. After the cutoff, the output signal of the multivibrator 21 becomes 0 after a set time, and the high voltage cutoff device t3 becomes conductive again and the operation of the electron gun is resumed.

FIG. 3 shows the operation of the circuit described above in more detail.

In a steady state, a beam acceleration voltage V is applied to the electron gun to perform electron beam welding. However, during welding, if metal vapor etc. released from the weld metal enters the electron gun, high voltage (cathode-anode or bias-yoshikaku) dielectric breakdown occurs, causing discharge within the electron gun. .

Therefore, the accelerating voltage V decreases and the beam current E increases. However, the degree of decrease in accelerating voltage and increase in beam magnetic current differs depending on the degree of release. When a discharge occurs and the beam current becomes I=(Is=LI1.), that is, when it increases from point 35 to point 36, the output voltages of the beam current detection circuit 6 and the voltage setting device 17 are compared; The current comparison circuit 18 operates to operate the multivibrator 21 and the NOT circuit 23 in the LED light emitting circuit 14.
The signal is reversed, the LED 15 is turned off, and the Shimada shutoff device i3 enters the shutoff operation. During this time, the beam current increases from point 36 to point 37, but this time 1o is less than a few microseconds and is sufficiently negligible. This L
When the ED 15 is turned off, a voltage is applied between the anode and the cathode of the high voltage cutoff device 3 so that the beam current changes from point 37 to point 38 (zero ampere) in 1 second. Along with this, the acceleration voltage also decreases as the beam current decreases, and the point 27
to point 28, point 29, and then point 30 (zero potential).

At this time, at point 28, that is, Vb (Vb=0.9v), a DC voltage is output from the acceleration voltage comparison circuit described above, and an ON signal is given to the multivibrator. At this time, since the beam current is zero, the output of the beam current comparison circuit described above is 1. It becomes zero after a second. However, as described above, since the multivibrator selects either the output signal of the beam current detection circuit or the accelerating voltage detection circuit, a voltage is applied between the anode and cathode of the suppression cutoff circuit by the output of the multivibrator. Also, the output of the multivibrator will be held for t1 seconds.

Therefore, when the output of the multivibrator is turned off after 13 seconds, the LED starts emitting light and sends a turn-on signal to the MOSFET of the high-voltage semiconductor module.The cylinder-pressure semiconductor module is turned on and the anode of the high-voltage cut-off device is turned on.・Between cathodes.

The voltage becomes zero after 4 seconds. Accordingly, the acceleration voltage of the electron gun is initially set from point 30 to point 31, and the value becomes 9V, and the beam current also changes from point 3B to point 39.
After that, the process returns to the value at point 40, and continuous electron beam welding is possible again.

In addition, the theory that discharge occurs and the beam current does not change significantly and only the accelerating voltage decreases to Vb (Vb = 0.9V-) is because the DC voltage is output from the accelerating voltage comparison circuit as described above. is output and the multivibrator is turned on immediately.
and performs the same operation, @ , −)−t z +t3+
After ta seconds, the steady state is restored and continuous electron beam welding becomes possible.

Furthermore, in this device, if the re-ignition of the accelerating voltage fails, the multivibrator performs the above operation again after Jtl+ts seconds from point 31, recovers the accelerating voltage from point 33, and recovers normally at point 34. It has the function of An example of the operation of each element in this case is shown by a dashed line. Furthermore, excessive beam current (from ≧) upon restriking the accelerating voltage
If a flow occurs, the above-mentioned operation is performed to restore normal operation. The most important factor in the operation of each element above is 4.
Tsuka, Ib, Vb, t2, t3 and t4. These specific setting values and their results are shown below.

t, and t4 should be set from 500 microseconds to 1 millisecond to protect the device.

This is because the inductance L present in the high-voltage circuit generates a surge voltage when the circuit is abruptly interrupted, damaging electronic components. Experimentally, at an accelerating voltage of 30 kV, 100
At a beam current of mA, the damage occurred when t2 was 100 microseconds or less. The beam tR used for this purpose,
It has been found that it is effective to set the time between 500 microseconds and 1 millisecond depending on the situation.

(2) - is a drop of about 20% in 30 to 50 milliseconds, which poses no problem for welding, so it was set to half that, 10%. Furthermore, since it has been confirmed that an increase in tW of about 20% in 30 to 50 milliseconds for Ib does not occur in welding, it was set to half of that, 10%.

t3 is also an important value for maintaining weld continuity, that is, for obtaining a sound weld.

As a result of electron beam bath contacting a plate of 100 W grade with a negative welding speed at a welding speed of 100 WR/min, good results were obtained when tz+t, +t4 was 12 milliseconds or less, but when this was exceeded, despite rapid recovery, A void defect occurred. This situation is shown in FIGS. 4 and 5.

Figure 4 shows that workpieces 41 and 42 with a thickness of 100 m are butt welded, and the recovery of the discharge generated in the electron gun described above is 1
．． +1. +1. This is the result of electron beam welding with the time set to 12 milliseconds or less, and the cross section of the weld is (a) and its A
-A section, that is, a longitudinal section is shown in (b). Weld metal 43 showed good quality with no defects in any cross section. Further, the back bead 44 also shows a uniform and good shape. On the other hand, when the time is longer than 12 milliseconds, as shown in FIG. 5, a vertical cross section is shown, a depression 46 and a ridge 47 are formed on the bead surface, and a void 45 is formed in a part of the bead surface.

Furthermore, similar binding was obtained for thin plates having a thickness of 9.3 to 30.9 cm.

From the above, it is desirable that t3 be 10 milliseconds or less.

The embodiments of the present invention have been described above. Furthermore, a great effect of this embodiment is that when adding it to existing equipment, there is no need to consider major modifications to the high-voltage power supply. In FIG. 1, in the prior art, on the positive side 49 of the circuit, the ground 5
A breaking device, such as a vacuum tube, is placed between 0 and the beam current detection circuit 6, and when a discharge occurs, the vacuum is used to perform the breaking operation, and the positive terminal of the high-voltage power supply is connected to the power supply voltage with respect to ground. The corresponding voltage will be applied. That is, if the outer box of the high voltage power supply is to be grounded for safety, the outer box of the high voltage power supply, the positive terminal, and the positive circuit must be insulated according to the power supply voltage. However, the positive side terminal and outer box of a high-voltage power supply that does not have a cutoff device are generally grounded, and when the cutoff circuit according to the present invention is inserted into the positive side 49, modification of the high-voltage power supply is not necessary. In order to provide a sufficient voltage gap, the outer box must be made larger, which poses a serious problem.

On the other hand, in this embodiment, as is clear from the state of the relevant position in FIG. It's zero volts. In other words, there is no need to consider the withstand voltage of the high-voltage power supply (the minimum necessary design-required withstand voltage may be taken into account), the high-voltage power supply can be made smaller, and the electron beam processing machine itself can be made smaller. This results in a device with high economic efficiency.

〔Effect of the invention〕

According to the present invention, it is possible to eliminate welding defects caused by discharge generated within an electron gun in electron beam welding. Furthermore, it is possible to eliminate damage to electronic components of the device due to surges caused by discharge. Furthermore, the present device can be applied to conventional electron beam processing machines without requiring major modification or replacement due to the problem of withstand voltage of the high-voltage power supply.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is a specific example thereof, Fig. 3 is a diagram showing the operation of the control device, and Fig. 4 (a)
is a cross-sectional view of the welded part of the workpiece processed by this device, and Figure 4 (b
) is a sectional view taken along the line A-A in FIG. 4(a), and FIG. 5 is an explanatory diagram of the occurrence of defects in welded parts of workpieces by a method other than the present invention. DESCRIPTION OF SYMBOLS 1... High voltage power supply, 2... Electron gun, 3... High voltage cutoff device, 4... Control circuit, 5... Optical fiber, 6...
...beam current detection circuit, 7...acceleration voltage detection circuit,
8... Vacuum level detection circuit within the electron gun, 9... High voltage semiconductor module, 10... Surge absorber, 11... Insulation transformer, 12... Inverter, 13... AC power supply, 14... ...LED transmitter circuit, 15...LED, 16
... Light receiving diode, 17... Voltage setting device, 18.
...Beam current comparison circuit, 19...Voltage setting device, 20
...Acceleration voltage comparison circuit, Decay 21...Multi-vibrator, 22...7 Otokabura, 23...NOT circuit, 24...Transistor,
25...Transistor, 26...MOSFET, 2
7-34... Indicates a running point to explain the change situation of the acceleration voltage, 35-40... Indicates a point to explain the change situation of the beam flow, 41.42... Workpiece Material, 43
... Weld metal, 44... Back bead, 45... Void defect, 46... Front bead dent, 47... Back bead protrusion, 48... Negative side of circuit, 49... Circuit The positive side (earth side) of 50...earth. Kan T figure! '43 Country Time → Kan 4 Shinogi 5 Diagram

Claims (1)

[Claims] 1. A high-voltage electric circuit consisting of a high-voltage power source of an electron beam processing machine and an electron gun that is a load of the power source, and detects the beam current flowing in the circuit and the accelerating voltage applied to the load. ,
In the cutoff and control mechanism, the high voltage electric circuit is cut off for a selected period of time by transmitting the detection signal from the control circuit of the high voltage cutoff device to the high voltage cutoff device as an insulated signal, and the operation of the electron gun is stopped. An electron beam processing machine characterized in that it can be placed between the negative side of a high-voltage power source and an electron gun that is a load of the power source so that there is no need to consider the withstand voltage of the power source. 2. The electron beam processing machine according to claim 1, characterized in that the time for stopping the operation of the electron gun is 10 milliseconds or less, and the turn-on and turn-off times are controlled within 500 microseconds to 1 millisecond. .