JPH02121248A - Electron beam generating device - Google Patents

Abstract

PURPOSE:To automate the correction of electron beams responding to the change with the passage of time by integrating the heating time of a cathode, and controlling the power to feed to the heating device depending on the correction characteristic to correct the electron beams which are changed with the time, responding to the integrated time. CONSTITUTION:When a beam switch 25 is operated, the value stored in an integral memory 32a is added, the responding value of the heating voltage is read from a correction feature table 31b depending on the integral value stored in the integral memory 32a and the feature stored in a feature designation memory 32b, and a heating power controller 29 is controlled. The correction of the electron beams responding to the change with the passage of time is carried out while the beam switch 25 is being operated. Consequently, the correction of the electron beams responding to the change with the passage of time is carried out automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron beam generator, and more particularly to an electron beam generator that automatically corrects an electron beam that changes over time.

[Conventional technology]

Conventionally, electron beam generators used in electron beam welding machines and the like have been equipped with a rod-shaped cathode, a filament placed around it, and a heat shield that covers them.The rod-shaped cathode is heated by the filament and generates electrons. It is designed to generate a beam. Since the heating temperature by the filament reaches about 3000 K, as the heating time increases, the rod-shaped cathode is worn out, the filament diameter changes, the heat shield is distorted, and the temperature of the rod-shaped cathode decreases. As a result, the electron beam gradually becomes unstable, and the accuracy with which the electron beam irradiates the object decreases.

In this way, since the electron beam generator is affected by changes over time, appropriate correction is necessary to keep the irradiation accuracy constant. Therefore, conventionally, whenever the electron beam became unstable and the required irradiation accuracy could not be obtained, the filament heating power was manually adjusted to increase the heating temperature to the rod-shaped cathode.

[Problems to be Solved by the Invention] However, the above-mentioned adjustment work is very complicated, and especially when welding by irradiating the details of parts of precision equipment with the electron beam, the adjustment work is very complicated. There is a problem in that the irradiation status must be frequently monitored, which wastes unnecessary labor and time.

Further, since the lifespan of the electron beam generator varies depending on the heating temperature, there is a problem that the lifespan is not constant due to variations in the adjustment by the person making the adjustment, making it difficult to manage. In particular, if the device is heated to a temperature higher than that required to obtain the desired accuracy, its life will be shortened.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an electron beam generator that automates correction of an electron beam according to changes over time.

[Means for Solving the Problems] In order to achieve the above object, the electron beam generator of the present invention includes an integrating means for integrating the heating time of the cathode, and an electron beam that changes over time according to the integrated time by the integrating means. and a control means for controlling the electric power supplied to the heating means in accordance with the correction characteristics for correcting the heating means.

Further, it may include a changing means for changing the correction characteristics.

[Operation] With the above configuration, the control means controls the electric power supplied to the heating means according to the correction characteristic according to the cumulative time by the integrating means.

Further, the correction characteristic is changed by a changing means.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

FIG. 3 is a sectional view schematically showing the basic structure of the in-shell electron beam generator 1. As shown in FIG. As shown in the figure, a coiled filament 5 is disposed coaxially with the axis of the rod-shaped cathode 3, and a heat shield 7 is further disposed to enclose the filament 5. And the rod-shaped cathode 3 is an impact type II! The cathode terminal of the impact power source 9 is connected to a potential terminal that divides the filament power source 11 into two. Both ends of the filament 5 are connected to an anode terminal and a cathode terminal of this filament power supply 11, and a heat shield 7 is further connected to the cathode terminal of the filament power supply 11. Further, a cathode terminal of a high voltage power supply 13 whose anode potential is grounded is connected to a cathode of an impact power supply 9, and the potential of the rod-shaped cathode 3 is maintained at a negative potential.

Further, a Wehnelt electrode 17 faces the end surface of the rod-shaped cathode 3 where the electron beam 15 is generated and focuses the electron beam 15.
The Wehnelt electrode 17 controls the amount of current of the electron beam 15 emitted from the cathode 3 to the anode 19 at ground potential. The Wehnelt electrode 17 is set at a lower potential than the rod-shaped cathode 3 by a bias power supply 21 .

With the above configuration, the rod-shaped cathode 3 is heated to a high temperature by the impact electron flow generated when the filament 5 is heated with electricity and by the radiant heat from the filament 5,
An electron beam 15 is generated.

The present invention has been made in an electron beam generator having the above-mentioned basic structure. 1
1 and the voltages of the impact power source 9 are controlled.

Next, the control circuit of the electron beam generator in this embodiment will be explained based on FIG.

The CPU 23 includes a beam switch 25 that instructs generation of an electron beam, a characteristic selection switch 27 that selects a desired one from a plurality of correction characteristics described later, a filament power supply control circuit 29a, and a heating source control circuit 29b for the shock 7. In addition to the power controller 29, a ROM 31 and a backup RAM 32 are connected.

The ROM 31 includes a program memory 31a that stores a program for controlling the entire device, and a correction characteristic table 31b that stores the correction characteristics shown in FIG. To explain the correction characteristic here, in the electron beam generator of this embodiment, the heating voltage required to obtain a predetermined irradiation accuracy according to the heating time has a characteristic A1.

In the figure, ■1 represents the initial heating voltage, and v2 represents the maximum heating voltage compensated by the device. Further, characteristic A2 has a heating voltage higher overall than characteristic A1, and is selected when obtaining higher irradiation accuracy. On the contrary, characteristic A
3 is selected when low irradiation accuracy is acceptable. The correction characteristic table 31b stores these characteristics.

On the other hand, the RAM 32 is an integration memory 32 that integrates and stores the time during which the electron beam is irradiated, that is, the heating time.
a, and a characteristic designation memory 32b that stores the characteristics selected and designated by the characteristic selection switch 27.

Hereinafter, the operation of the electron beam generator of this embodiment will be explained based on the flowchart of FIG.

First, when the power is turned on, an initial setting process (not shown) is performed, and then in step Sl (hereinafter simply referred to as Sl; the same applies to other steps), it is determined whether a switch has been operated, When it is not operated, the judgment of Sl is repeated. If the judgment of sl becomes YES, continue <32
．． In S3, it is determined whether the operated switch is the beam switch 25 or the characteristic selection switch 27, and if it is neither, other processing is performed in S4, and the process returns to Sl.

When the characteristic selection switch 27 is operated, the judgment in S3 is Y.
ES, and the characteristic selected in S5 is stored in characteristic specification memory 3.
2b. That is, the characteristics A1 to A3 in FIG.
Which characteristic is selected is stored.

When the beam switch 25 is operated, the judgment in S2 is Y.
ES, the value stored in the integration memory 32a is added in S6, and in S7, the corresponding heating voltage is determined based on the integration value stored in the integration memory 32a and the characteristics stored in the characteristic specification memory 32b. The value of is read from the correction characteristic table 31b, and the heating power controller 2
9 is controlled. While the beam switch 25 is operated, Sl, S2 . S6. The step S7 is repeated, and the electron beam is corrected in accordance with changes over time.

By the way, the characteristics B1, B2. in FIG. As shown in B3, when the characteristics of heating time and heating voltage can be approximated by a straight line, the characteristics can be stored as a simple linear function and the characteristics can be selected by changing the coefficients, or the characteristics can be selected using the correction characteristics table 31b. It is also possible to adopt a mechanism that changes the volume of a variable resistor over time without using such an electronic memory.

[Effects of the Invention] As described in detail below, in the electron beam generator according to the present invention, since the electron beam is automatically corrected in accordance with changes over time, complicated adjustment work is not required, and This has the effect of making the device life constant regardless of the operator.

Furthermore, by selecting the correction characteristics, it becomes possible to perform correction according to the required irradiation accuracy.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a control circuit of an electron beam generator in an embodiment of the present invention, Fig. 2 is a flowchart showing its operation, and Fig. 3 is a schematic diagram of the basic structure of a general electron beam generator. The cross-sectional views shown, and FIGS. 4 and 5 are explanatory diagrams showing correction characteristics of heating voltage with respect to heating time. In the figure, 3 is a rod-shaped cathode, 5 is a filament, 15 is an electron beam, 23 is a CPU, 27 is a characteristic selection switch, 31b
32a is a correction characteristic table, 32a is an integration memory, and 32b is a characteristic specification memory.

Claims (1)

[Scope of Claims] 1. An electron beam generating device having a cathode for generating an electron beam and a heating means for electrically heating the cathode, comprising: an integrating means for integrating the heating time of the cathode; and an integrating means for the integrating means. and control means for controlling power supplied to the heating means in accordance with a correction characteristic for correcting the electron beam that changes over time according to the cumulative time of the electron beam generator. 2. The electron beam generator according to claim 1, further comprising a changing means for changing the correction characteristic.