JPH0211357B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam deflection device for moving the irradiation position of the electron beam on the surface of an object to be irradiated from the current position to the target position at high speed and with high precision in an electron beam processing device. be.

As an example of this type of apparatus, an electron beam welding machine for detecting in-process welding lines shown in FIGS. 1 to 8 will be described. FIG. 1 shows a configuration example of an in-process welding line detection device for electron beam welding. In the figure, 1 is an electron gun, 2 is a workpiece to be welded,
3 is a welding line on the workpiece 2; 4 is an electron beam for welding (hereinafter referred to as a welding electron beam); 5 is a scanning electron beam for detecting the welding line 3; 6 is a scanning electron beam for detecting the welding line 3;
is X with the current irradiation position of welding electron beam 4 as the origin
7 is also the Y-axis, 8 is the X-axis deflection coil for obtaining the scanning electron beam 5, 9 is the same Y-axis deflection coil, and 10 is the irradiation position of the scanning electron beam 5 on the workpiece 2 (hereinafter simply referred to as 11 is a triangular locus (hereinafter simply referred to as a locus) of the irradiation position), and 11 is a backscattered electron, secondary electron, or X-ray (hereinafter referred to as
(referred to as backscattered electrons or A waveform generator, 16 a Y-axis scanning waveform generator, 17 an X-axis scanning waveform amplifier (hereinafter referred to as an X-axis amplifier), 18
is a Y-axis scanning waveform amplifier (hereinafter referred to as Y-axis amplifier), 19 is an X-axis deflection current, 20 is a Y-axis deflection current,
21 is a detection resistor for the X-axis deflection current 19 (hereinafter referred to as X-axis detection resistor), 22 is a detection resistor for Y-axis deflection current 20 (hereinafter referred to as Y-axis detection resistor), and 23 is an output signal of the gate pulse generator 14. The operation is started by the detection signal of the X-axis deflection current 19, the detection signal of the Y-axis deflection current 20, and the amplifier 13 of the detector 12.
24 is a servo amplifier that generates a motor drive signal based on the output signal of the calculation device 23, 25 is an electron gun drive device, and 26 is a workpiece drive device.

Fig. 2 is an enlarged view of the vicinity of the locus 10, where 27 is the part where welding has already been completed (hereinafter referred to as the "already welded part"), 28 is the origin which is the current irradiation position of the welding electron beam, and 29 is the case where triangular scanning is performed. 30 is the starting point of welding line detection, 31 is the second scanning line when performing triangular scanning, 32 is the point at which welding line 3 is detected, 33 is the ending point of welding line detection, 3
4 is the third scanning line when performing triangular scanning.

FIG. 3 is a configuration diagram of the X-axis scanning waveform generator 15 and the Y-axis scanning waveform generator 16, where 35 is a reference power supply, 36 is a reference power source, and 36 starts operation at the rising edge of the output signal of the gate pulse generator 14. The integrator 37 of the reference power supply 35, which is reset in the descending portion, is an adder for the output signal of the gate pulse generator 14 and the output signal of the integrator 36.

FIG. 4 is a waveform diagram showing the scanning signal of the scanning electron beam, where a is the X-axis signal, b is the Y-axis signal, t is the time axis, and 39a is the output voltage of the X-axis scanning waveform generator 15 (hereinafter referred to as 40a is the output voltage of the Y-axis scanning waveform generator 16 (hereinafter referred to as the Y-axis output voltage).

FIG. 5 shows the trajectory of the scanning electron beam, and numeral 41 indicates the trajectory of the scanning electron beam actually obtained (hereinafter referred to as the actual trajectory). Figure 6 shows X-axis amplifier 1
7 is a constant current amplifier (for the X axis in the figure) used for the Y-axis amplifier 18, 42 is an operational amplifier with a large output, 43 is an input resistor, 44 is a current detection resistor, and 45 is a feedback resistor. FIG. 7 shows the scanning signal of the scanning electron beam, where a is the X-axis signal and b is the Y-axis signal. FIG. 8 shows the locus of the scanning electron beam.

Next, the operation will be explained. The welding electron beam 4 emitted from the electron gun 1 creates a welding line 3 on the workpiece 2.
When welding the workpiece 2 of the welding electron beam 4
It is necessary to align the upper irradiation point exactly with the welding line 3. An in-process weld line detection method is a method for this purpose. In this detection method, the welding electron beam 4 is time-divisionally deflected by deflection coils 8 and 9 to create a scanning electron beam 5, which scans the area in front of the current irradiation point of the welding electron beam 4. The scanning electron beam 5 is produced as follows. The output signal of the gate pulse generator 14 operates the X-axis scanning waveform generator 15 and the Y-axis scanning waveform generator 16, and the output signals are amplified by the X-axis amplifier 17 and Y-axis amplifier 18, respectively, and the X-axis deflection current is 19 and Y-axis deflection current 20 to form X-axis deflection coil 8 and Y-axis deflection coil 9.
, and deflects the scanning electron beam 5 along the X-axis 6 and the Y-axis 7. The X-axis deflection current 19 and the Y-axis deflection current 20 are detected by an X-axis detection resistor 21 and a Y-axis detection resistor 22, respectively, and are input to an arithmetic unit 23. On the other hand, the scanning electron beam 5
As is well known, the reflected electrons or X-rays 11 generated by colliding with the The signal is input to the arithmetic unit 23. The arithmetic unit 23 operates during the output period of the gate pulse generator 14, and calculates the time when the Y-axis deflection current 20 becomes zero and the backscattered electrons or the X-axis 1.
Find the difference between the time when the intensity of 1 becomes zero. This time difference is an error between the welding line 3 and the irradiation point at a position in front of the current irradiation point of the welding electron beam 4, which is determined from the X-axis deflection current 19. This error is output as an error signal from the arithmetic unit 23 and amplified by the servo amplifier 24. Next, the electron gun drive device 25
Alternatively, the welding object drive device 26 is connected to the electron gun 1, respectively.
Alternatively, the welding object 2 is moved in the Y-axis direction to correct the position of the irradiation point of the welding electron beam 4 on the welding object 2.

As an example of the locus 10, a triangular one is shown in FIG. In this case, weld line detection is performed in the second scanning line 31 portion. FIG. 3 shows the configuration of an X-axis and Y-axis scanning waveform generator for creating this triangular locus. As the X-axis scanning waveform signal, the output signal of the gate pulse generator 14 is used as is. Furthermore, the signal of the Y-axis scanning waveform is obtained by integrating the voltage of the reference power supply 35 from the rising part of the output signal of the gate pulse generator 14 by the integrator 36, and by integrating the voltage of the reference power supply 35 from the falling part of the output signal of the gate pulse generator 14. Vessel 3
6 to create a triangular wave, and add it to the output signal of the gate pulse generator 14 in the adder 37. Therefore, the X-axis amplifier 17
and the output voltage of the Y-axis amplifier 18 is
When voltage amplification types are used for 7 and 18, the input signal 39 of each amplifier 17 and 18 shown in FIG.
It has the same waveform as a and 40a. However, since the load of each amplifier 17, 18 is a deflection coil, that is, an inductive load, the X-axis deflection current 19a and the Y-axis deflection current 20a, as shown in FIG. The voltage is different from the voltage 40a. Therefore, the trajectory is not triangular and the fifth
The trajectory will be as shown at 41 in the figure.

Therefore, in order to make the actual locus 41 triangular, it is conceivable to make each of the amplifiers 17 and 18 a constant current type as shown in FIG. In this case, the deflection current is detected by the current detection resistor 44 and negative feedback is applied to make the output current the same as the input voltage signal. However, since welding is interrupted during the weld line detection period, the time allowed for detection is 1 to 10 ms, and since rectangular wave signals are used, the frequency band of each amplifier 17 and 18 is required to be extremely wide. be done. Therefore, transient oscillations in the output current due to instability of each amplifier 17 and 18 are unavoidable, resulting in waveforms 19b and 20b as shown in FIGS. 7a and 7b. Therefore, the trajectory oscillates near the detection starting point 30 as shown in FIG.
It becomes like this, and it vibrates around the origin 28 again and becomes 41
It becomes like b.

Conventional electron beam welding machines that perform in-process welding detection are configured as described above, so if a voltage amplification type deflection signal amplifier is used, the transient response of the deflection coil current is faster than the time constant of the deflection coil circuit. This will slow down the deflection speed of the electron beam. Therefore, when welding line detection is performed using welding beam current in a time-sharing manner during welding, the time required for welding line detection becomes longer, which has a negative effect on the molten part of the welded part, and also reduces the amount of time required to detect the welding line. The heat input to the scanning part becomes large, causing melting and thermal distortion of the non-welded part. In addition, when a constant current type deflection signal amplifier is used, the deflection current oscillates transiently, the trajectory of the scanning electron beam on the workpiece is distorted, and signal processing after welding line detection is complicated and takes a long time. There were some shortcomings.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and it uses a pulse voltage that instantly moves the electron beam irradiation position on the workpiece and a scanning electron beam trajectory on the workpiece. It is an object of the present invention to provide an electron beam deflection device capable of high-speed deflection of an electron beam by simultaneously or sequentially applying corresponding voltage waveforms to deflection coils.

Hereinafter, first, the principle of this invention will be explained with reference to the drawings. In FIG. 9a, 46 is a deflection signal generator, 47 is a deflection coil having self-inductance L, and 48 is a series of resistance values R equivalently representing the output resistance of the deflection signal generator 46 and the internal resistance of the deflection coil 47. The resistance, i, is the deflection current flowing through this circuit.

In order to cause the current i ₀ shown in FIG. 9b to flow through the deflection coil 47, the deflection signal generator 46 should generate a step voltage E ₀ =Ri ₀ shown by the waveform 50. In this case, the current The transient response of i is shown in waveform 51 in FIG. 9b, and is expressed by the following equation.

i=E ₀ /R (1−e ^−t/ 〓) However, τ=L/R, which is a constant specific to the circuit. Therefore, the normalized time t/τ to approach the value of i ₀ is 90% of i ₀ : t/τ = 2.30 99% of i ₀ : t/τ = 4.61 99.9% of i ₀ : t/τ = It becomes 6.91.

Next, consider a method in which the deflection signal generator 46 generates a step voltage E ₁ 52 greater than E ₀ and lowers E ₁ to E ₀ at time t ₀ when the current i reaches i ₀ . In this case, the transient response of the current i becomes as shown by the waveform 53 in FIG. 9c, and is expressed by the following equation.

i=E ₁ /R(1-e ^-t/ 〓) O≦t≦t ₀ i=E ₀ /R t ₀ <t Further, t ₀ /τ is expressed by the following formula.

t ₀ /τ = -ln (1-E ₀ /E ₁ ) Therefore, the relationship between E ₀ /E ₁ and t ₀ /τ is E ₁ = 10E ₀ :t ₀ /τ = 0.105 E ₁ = 100E ₀ :t ₀ /τ=0.0101. For example, compared to the time it takes to reach 99% of i ₀ using the former method, the latter method of adding a pulse of E ₁ = 10E ₀ takes about 1/44th of the time, and moreover _, No deviation occurs.

Next, consider the case where lamp current i=Kt is caused to flow through the deflection coil 47. In this case, the deflection signal generator 4
When the lamp voltage 54E=KRt is generated in 6, the current i
The transient response of is shown in waveform 55 in FIG. 10a, and is expressed by the following equation.

i=Kτ(e ^-t/ 〓-1)+Kt Therefore, a deviation of Kτ(e ^-t/ 〓-1) occurs from the set value. Next, in the deflection signal generator 46, E=KRt
Waveform 56 in which a step voltage of E ₂ =Kτ is superimposed on
When , the transient response of the current i becomes as shown by the waveform 57 in FIG. 10b, and is expressed by the following equation.

i=Kt Therefore, no deviation from the set value occurs.

Next, an embodiment based on the above principle will be described with reference to the drawings. In FIG. 11, 58a, 58
b, 58c, and 58d are pulse voltages that instantaneously move the irradiation position (hereinafter referred to as moving pulse voltages), and 59a and 59b are voltage waveforms corresponding to the trajectory (hereinafter referred to as reference voltage waveforms). Further, in FIG. 12, 60 is an X-axis D/A converter, 61 is a Y-axis D/A converter, 62 is a gate signal corresponding to the output signal of a conventional gate pulse generator, and 63 is a microcomputer.

Next, the operation will be explained.

The locus 29, 3 of the triangular waveform shown in Fig. 2 is placed on the workpiece to be welded.
The electron beam is scanned along lines 1 and 34, and the welding line 3
Consider the case of detecting. Scanning from origin 28 to detection start point 30 and from detection end point 33 to origin 2
Scanning to 8 is performed instantaneously regardless of weld line detection. Scanning from the detection start point 30 to the detection end point 33 is performed parallel to the Y-axis 7 at a constant speed. in this case,
The waveform required for the X-axis deflection current is 19c in Figure 11a, and the voltage waveforms required to flow this current 19c are 58a, 59a, 59a,
It becomes 58b. The waveform required for the Y-axis deflection current is 20c in Figure 11b, and this current 2
The voltage waveforms required to flow 0c are 58c, 59b, and 58d based on the above principle. These voltage waveforms can be divided into several basic waveforms. The moving pulse voltages 58a and 58c move the irradiation position from the origin 28 to the detection start point 30, and the moving pulse voltages 58b and 58d move the irradiation position from the detection end point 33 to the origin 28. Moving pulse voltages 58a, 58b, 58
The peak voltages of c and 58d are set to scan near the maximum voltages that can be output by the X-axis amplifier 17a and the Y-axis amplifier 18a. Further, the reference voltage waveform 59a is for keeping the X-axis coordinate of the irradiation position constant during the welding line detection period, and the reference voltage waveform 59b is for moving the irradiation position at a constant speed parallel to the Y-axis during the welding line detection period. As shown in the above principle, a step voltage is superimposed on the lamp voltage. The voltage waveforms 39b and 40b, which are the composites of the moving pulse voltages 58a, 58b, 58c, and 58d and the reference voltage waveforms 59a and 59b, can be easily created using a pulse circuit, but these voltage waveforms 39b, 40b is simply a combination of pulse voltage and lamp voltage, and as shown in FIG.
The converters 60 and 61 allow voltage waveforms to be synthesized quickly and easily.

Note that in the above embodiment, an electron beam welding machine that performs in-process welding line detection was explained.
The present invention may be an electron beam hardening machine that requires moving the electron beam irradiation position at high speed and with high precision, and the same effects as in the above embodiments can be achieved. In the case of an electron beam hardening machine, scanning is performed at high speed and intermittently in order to limit the heat input range of electron beam power.

As described above, according to the present invention, the pulse voltage that instantaneously moves the electron beam irradiation position on the workpiece and the voltage waveform corresponding to the trajectory of the scanning electron beam on the workpiece are deflected simultaneously or sequentially. Since it is configured to be applied to the coil, scanning can be performed 10 to 100 times faster than when no moving pulse voltage is applied, and transient vibrations do not occur after movement, and scanning with high positional accuracy is possible even during movement. There is an effect that can be done.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram showing an electron beam welding machine that performs in-process welding line detection, Figure 2 is a diagram showing the locus of the scanning electron beam irradiation position on the workpiece, and Figure 3 is a diagram showing the conventional scanning waveform. The configuration diagram of the generator, FIGS. 4 to 8 are diagrams for explaining the conventional drawbacks, and FIGS. 9 a, b, and c and FIGS. 10 a and b are diagrams for explaining the principle of the present invention. , FIGS. 11a and 11b are diagrams for explaining the operation according to an embodiment of the present invention, and FIG. 12 is a schematic configuration diagram showing a scanning waveform generator according to an embodiment of the present invention. In the figure, 1 is an electron gun, 2 is an object to be welded, 8 is an X-axis deflection coil, 9 is a Y-axis deflection coil, 12 is a detector,
13 is an amplifier, 19 is an X-axis deflection current, 20 is a Y-axis deflection current, 21 is an X-axis detection resistor, 22 is a Y-axis detection resistor, 23 is an arithmetic unit, 24 is a servo amplifier, 2
5 is an electron gun drive device, 26 is a workpiece drive device,
58a and 58b are X-axis movement pulse voltages, 5
8c and 58d are Y-axis movement pulse voltages, 60
61 is an X-axis D/A converter, 61 is a Y-axis D/A converter, and 62 is a microcomputer. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. In an electron beam processing device, a deflection coil to which a deflection current is supplied for deflecting the electron beam so that the electron beam follows a predetermined scanning trajectory; means for generating a scanning locus voltage waveform and simultaneously or sequentially superimposing a voltage pulse on the scanning locus voltage waveform for correcting a waveform difference with the scanning locus voltage waveform due to a transient response of the deflection current. An electron beam deflection device characterized by: 2. The electron beam deflector according to claim 1, wherein the electron beam processing device is an electron beam welding machine, and the deflection coil and the means are provided for time-sharing welding line detection during welding. Device.