JPS6289828A - Method for controlling electron beam in electron beam heating - Google Patents

Abstract

PURPOSE:To decrease the change of an irradiation region with the output of the electron beam as far as possible and to improve the accuracy of the electron beam control by monitoring the change of the above-mentioned irradiation region while exactly reflecting the same on a monittor medium. CONSTITUTION:An acceleration voltage detector 20 receives an accleration voltage U, divides down the same and outputs the divided voltage as an acceleration voltage detection signal (u) when the acceleration voltage changes from U0 to U. The signal (u) is then converted to vout=(U0/U)<0.5> in a correction function calculator 21 and is outputted as a correction calculation signal vout. The signal vout is inputted together with a detected deflecting current value is obtd. by converting the X deflecting current I0 in an X-axis deflecting quantity with a deflecting current detector 22 to a multiplier 23 and is further inputted as the multiplied value Xin outputted from the multiplier 23 to the X-terminal of a synchroscope 26. Yin is similarly inputted with regards to a Y-terminal side. An operator, therefore, monitors, the deflecting condition of the electron beam based on the Lissajous' waveform displayed on a synchroscope 26 and decreases the change of the irradiation region as far as possible.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is applicable to
To heat the object to be irradiated with an electric r-beam using a device etc.,
Tate,',t! : By monitoring changes in the irradiation area due to output adjustment of the f-beam can while accurately reflecting them on the monitoring medium 1- such as a synchroscope, the changes in the irradiation area can be reduced as much as possible and the electric r-beam This invention relates to an electron beam control method that allows for highly accurate control. [Prior Art] Due to the progress of metal cutting technology, applied technology using Cr-Heat L1 is attracting attention. Techniques using electric r-beams include electric r-beam melting and electron beam injection71, among which 1k
F-heam melting is carried out using an apparatus as shown in FIG. That is, the cough melting device 1 irradiates the object 5 to be melted in the water-cooled PJ type 4 with electron beams 1.3 emitted from the cathode 2a of the electric r-beam gun 20, and the object 5 to be melted is heated by the heat generated at this time. It is something that is trying to dissolve. Further, simultaneously with this melting, it is also possible to refine impurities in the material 5 to be melted or to perform vapor deposition by injecting the material 5 to be melted. In such a 'tj r-beam melting device; δ1,
The trick is to irradiate the boundary surface 5a between the material to be melted 5 and the water-cooled VF mold 4 with a particularly strong electric r-beam, but what is the purpose of this? A' (Precise control of the IF of the beam, for example, control of the irradiation area is required.) By the way, when controlling the electron beam, the filament 7 on the cathode 2a side as shown in FIG.
Thermionic electrons 8 generated by heating are accelerated through the auxiliary upper pole 9 and the 7-node ring 10, and are further By adjusting the deflection current, the deflection within the plane (in the direction of the paper) is controlled. The reality is that such adjustment of the x and Y deflection currents is carried out while observing and confirming the electron beam irradiation situation on the boundary surface 5a through an observation window (not shown) or the like. . However, as the melting of the material to be melted 5 progresses, the evaporated matter may adhere to the glass of the observation window, etc., making the electron beam irradiation position unclear, or the deposition of splash on the water-cooled mold 4 may cause the 11 My vision becomes blurry. This results in problems with the control of the electron beam, and furthermore, this poor control may cause problems such as erroneous irradiation of the water-cooled mold 4 and damage to the water-cooled mold 4. If the water-cooled mold 4 is damaged, water and molten metal may come into contact and cause a steam explosion, which may lead to a large iG failure. -However, it is clear that if too much emphasis is placed on preventing such disadvantages, the melting of the material 5 to be melted will be incomplete, leading to a decrease in yield. In view of these circumstances, the present inventors have completed a method of simultaneously displaying on a synchroscope and adjusting the deflection current based on the surge waveform and the irradiation area waveform.
A separate patent application has been filed. [Problems to be solved by the invention] However, depending on the nature of the object to be heated (or the object to be irradiated),
It is often necessary to adjust the irradiation power of the electron beam. As a method to adjust the output of the electron beam, (1
) A method of adjusting the amount of electrons emitted from the cathode by changing the temperature of the cathode, (2) A method of adjusting the amount of electrons emitted and the electron beam speed by changing the potential gradient between the cathode and the seventh node, etc. can be mentioned. The present inventors adjusted the irradiation output using the method (2) above, and while conducting a melting experiment of a heated object while adjusting the deflection current using the method using a synchroscope as described above, they found that A new problem was discovered: the irradiation area changes as the beam speed is adjusted, causing problems with electron beam control. The present invention has been made in view of these circumstances, and by monitoring changes in the irradiation area due to adjustment of the output of an electron beam while accurately reflecting the changes in the irradiation area on a monitoring medium such as a synchroscope. Reduce changes as much as possible,
The present invention aims to provide an electron beam control method that can improve the accuracy of electron beam control. [Means for Solving the Problems] The electron beam control method according to the present invention performs output adjustment by changing the electron velocity, and when heating is performed by an electron beam gun having a two-axis deflection function, a standard acceleration The gist is that the detected deflection current value is multiplied by a function including a ratio term given by the voltage versus the actually applied accelerating voltage, and the obtained signal is input to the monitoring medium and displayed. [Effect 1] The present inventors first conducted the following considerations in order to clarify the relationship between the speed of the electron beam and the irradiation area. As shown in Fig. 4, the current flowing through the deflection coil X is Ix, and the current flowing through the deflection coil Y is IV. Assuming that the electron beam is proportional, the electron beam near the center follows Fleming's left f law and curves '
It is deflected so that the u radius is expressed by equations (1) and (2), and from a point where the influence of the magnetic field is almost gone, it flies in the tangential direction and reaches the object to be melted. However, ■ = electrician speed 1 m: electronic quality, e: electronic charge,
B-magnetic flux density, r/curve-tz: t'-diameter. The X and Y suffixes indicate the X force direction and Y direction, respectively. The change in position ΔLx due to such deflection is determined as follows using FIG. 5゛, ΔLX=Lxtan OX + rx r core Here, in a sufficiently small range of O, ``!2)) Since l x2, similarly here, in order to handle the following in the cylinder, the suffix X
Let us express it as an expression with and Y removed. Next, the acceleration voltage U is expressed as follows. The electrons are accelerated to a velocity V by an accelerating voltage U applied between the cathode and the anode. e U = -m V 2- (fl) When equation (7) is substituted into equation (5) above, the relationship between ΔL and acceleration voltage U is expressed by equation (8) below. For the unreleased II Nagisa, etc., when the above equation (8) is changed for the case where the magnetic flux severity B is kept constant, that is, the deflection current is kept - constant, the acceleration '+i is changed, and the pressure is changed from Uo to U. Equation (9) was obtained. The inventors of the present invention have made various considerations through these modifications, and found that [When the acceleration voltage U changes, as can be seen from the above equation (9), the input signal of the deflection rate synchroscope ~ should be multiplied by J positive coefficient π. It's a good thing. As a result, changes appearing on the melting surface can be determined by the magnitude of the deflection current and can be monitored on a synchroscope. ” I learned that. The present inventors have completed the present invention as a result of intensive research based on such knowledge. That is, the present invention multiplies the detected deflection current value 1d by a function including U, /U, where the basic acceleration voltage is Uo, and the actually applied acceleration voltage U. Its greatest feature lies in the way it is input and displayed in the co-op. The present invention will now be explained in detail by giving examples. [Example 1] FIG. 1 is a circuit diagram illustrating an example of the present invention. '1i, the f-beam can 13 has a cathode 14, an anode 15 . It is composed of deflection coils (X deflection coil 16 and Y deflection coil 17), etc., and high street pressure (variable voltage of 3 to 30 KV) is applied between the cathode 14 and the anode 15 from the first day of the high voltage generator. be done. The accelerated beam 19 passing between the cathode 14 and the anode 15 is deflected 114. It is deflected by the current as described in +iii. If the acceleration voltage changes from UO to U at this moment, the acceleration type J[detector (consisting of a resistive window) 20 receives this U, divides it, and outputs it as an acceleration voltage detection signal U. . This acceleration voltage detection (No. 4 U is subjected to a conversion of ma out = 5 by the correction function calculator 21,

[I
The E calculation result is output as out. The complement +lE f
lit calculation-J-maout is the X deflection current IO in the Then, the multiplication value Xin output from the multiplier 23 is inputted to the X terminal of the synchroscope 26.The Y terminal side is similarly inputted as Yin.Therefore, the operator The deflection status of the electron beam can be monitored using the surge waveform as a reference.The deflection coil 16 generates a deflection magnetic field by the current from the deflection amplifier 24, and the effect of the actance on the deflection coil is According to
In order to avoid a decrease in the excitation current of the coil in the high frequency region, feedback 25 of the deflection current is applied to adjust the excitation current together with the deflection current command value id''.The acceleration voltage detection signal U is Since the acceleration voltage command value is generally fed back as an acceleration voltage command value within the high degree cardiac pressure generator 18, the acceleration voltage command value may be used as the correction signal command value. Usually its maximum (tri is l + M small (+
Since it is more than 10 times i, the complementary function does not necessarily affect the conversion in l calculator 21! There is no need to worry about using a coefficient such as <ua+in~ursaxc as shown in Figure 6.
(uwin is the minimum value of U, ufAaX is the maximum value of U) can be divided into 2 to 5 parts, and one curve can be approximated by a linear function αU + β. By doing this, the circuit can be Not only this, but it is also very effective in software processing using the CPU. [Effects of the Invention] Since the present invention is configured as described above, it is possible to monitor changes in the irradiation area due to adjustment of the output of the electron beam while accurately reflecting them on a monitoring medium such as a synchroscope. This made it possible to reduce the change in the irradiation area as much as ηf, thereby making it possible to improve the accuracy of electron beam control.

[Brief explanation of drawings]

Fig. 1 is a circuit explanatory diagram showing an embodiment of A:55 light;
Figures 11 and 3 show the principle of electron beam melting equipment.
FIG. 4IA is an explanatory diagram showing the situation when an electron beam is deflected by a deflection coil, and FIG. 5 is an explanatory diagram for determining the deflection distance of an electron beam. FIG. 6 is a graph showing another aspect of the calculation command in the correction function command calculation unit. 4... Mold 13... Electron beam gun U
O...Reference acceleration voltage U...Actually applied acceleration voltage id...Deflection current detection I^

Claims (1)

[Claims] When performing output adjustment by changing the electron speed and heating with an electron beam gun having a two-axis deflection function, a function containing a term of the ratio given by the standard acceleration voltage and the actually applied acceleration voltage is used as the deflection current detection value. 1. A method for controlling an electron beam, the method comprising multiplying and inputting the obtained signal to a monitoring medium and displaying the signal.