JPH0449215B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing an electron gun for a microwave tube.

[Technical background of the invention and its problems] In an electron tube in which the electron beam travels in a straight line, such as a klystron or a traveling wave tube, a plurality of spherical grid electrodes aligned in front of a concave cathode surface are used as a piercing electron gun. It may be placed. This has a structure as shown in FIGS. 5 to 7. In the figure, reference numeral 31 is a cathode with a concave electron emitting surface, 32 is a heater, 33 is a cathode sleeve, 34 is a control grid electrode, 35 is a cylindrical grid support thereof, 36 is a support flange, and 37 is a The shadow grid electrode, 38 represents its ring-shaped grid support, and 39 represents its flange.

The feature of this structure is that the amount of electron beam emission is controlled by applying a negative or positive potential to the control grid electrode 34 with respect to the cathode, and the electrons emitted from the cathode directly flow into the control grid electrode 34. In order to prevent this, a shadow grid electrode 37 is interposed between the two. These cathodes 31 and shadow grid electrodes 3
7. The control grid electrodes 34 are formed into concentric spherical shapes with radii of curvature R1, R2, and R3, respectively, and are arranged at minute intervals g1, g2 of about 0.2 and 0.3 mm, respectively. Moreover, both grid electrodes are perfectly aligned along the electron beam emission trajectory from the entire surface of the cathode. Each grid electrode is made of a thin plate of high-melting point metal such as molybdenum (Mo) approximately 0.1 mm thick.
It is formed into a spherical shape and has a grid pattern consisting of a large number of radial slits 41 separated by grid wires 40 with a width of about 50 μm.

The method of forming a grid electrode with slits in such a fine grid pattern, and aligning, positioning and fixing both grid electrodes in front of the cathode has conventionally been generally performed by the method shown in FIGS. 8 and 9. It is based on That is, Fig. 8 a to e
The control grid structure is assembled as shown in FIG. 1, and the shadow grid structure is assembled as shown in FIGS. First, as shown in FIG.
form 2. Next, as shown in FIG.
form. At this time, 2 of the peripheral part of the thin material plate 51
At the same time, positioning notches 54 are formed at the locations. The control grid electrode 34 thus formed is then bonded to a previously formed grid support 35 as shown in FIG. Grid support 3
5 has two holes 55 for aligning with the notch 54 of the grid electrode 34 and four through holes 56 for aligning and positioning the two grid structures in the support flange portion 36. The hole is drilled in the specified position. In this way, the control grid body 57 is assembled as shown in FIG. In the same way,
As shown in g, a Mo material thin plate 58 having a diameter slightly smaller than that of the grid structure is pressed to form a spherical portion 59 having a predetermined radius of curvature. Next, as shown in FIG. 6H, a grid pattern 60 consisting of a large number of slits defined by fine grid wires is formed by electrical discharge machining or etching. At this time, the material thin plate 58
There are also two positioning notches 6 on the periphery of the
1 at the same time. The shadow grid electrode 37 thus formed is then bonded to a grid support 38 previously formed as shown in FIG. It is joined to this grid support 38. The grid support 38 has two holes 62 for alignment with the notches 61 of the grid electrode 37 and four holes 62 for aligning and positioning the two grid structures.
Through-holes 63 are bored at predetermined positions in the support flange portion 39 . In this way, the shadow grid structure 64 is assembled as shown in FIG. Then, as shown in FIG.
A rod-shaped jig 65 is inserted through the grid electrodes to align and assemble the grid wires and slits of each grid electrode, and both grid electrodes are fixed to each other by an electron gun component (not shown) that holds these grid structures.

However, such a conventional method has the disadvantage that it is difficult to obtain sufficient precision in alignment of both grid electrodes, especially in the rotational direction. The reason for this is that in addition to forming the positioning holes 56 and 63 on each grid support, the grid electrodes 3 with the grid pattern already formed on each grid support
This is because alignment accuracy decreases due to the accumulation of errors in accuracy when positioning and fixing 4 and 37, respectively.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and provides a method for manufacturing an electron gun for a microwave tube, in which a plurality of grid electrodes can be precisely aligned.

[Summary of the invention]

In this invention, first, a thin metal plate made of a high melting point material such as Mo, which will become each grid electrode, is formed into a spherical shape using a press molding machine and fixed to each grid support, and then each thin metal plate is formed by electrical discharge machining or etching. A large number of slits corresponding to the grid pattern are bored and at the same time corresponding predetermined positioning holes are formed in each grid support portion, and then each grid electrode is placed in front of the cathode and each grid support A method for manufacturing an electron gun for a microwave tube, characterized by inserting a position regulating rod-shaped jig into each positioning hole drilled in the body, aligning the grid wires of each grid electrode, and fixing both grid electrodes. .

[Embodiments of the invention]

Examples thereof will be described below with reference to the drawings. Note that the same parts are represented by the same symbols.

FIG. 1 shows an electron gun completed according to the present invention. In the figure, reference numeral 11 indicates a Wehnelt electrode;
2 is the four through holes formed therein, 13 is the ceramic insulating support rod, 14 is the control grid support ring, 15 is the first outer support tube, 16 is the second outer support tube, and 17 is the arc of both support tubes. Welded part, 18
19 is an insulating spacer, 19 is four positioning holes drilled in the flange of the control grid support cylinder, 20 is four positioning holes correspondingly formed in the shadow grid support ring, 2
1 is a ring-shaped support base, 22 is an inner first support cylinder, 2
3 is the inner second support cylinder, 24 is the heat shield cylinder, 25
26 is a heater lead, 26 is an inner support frame, 27 is a control grid structure, 28 is a shadow grid structure, and e is an electron beam. A shadow grid 37 held by the inner first support tube 22 and the support stand 21 is electrically shortened to the cathode 31 via the lower support frame 26. On the other hand, the control grid electrode 34 is given a negative or positive potential.

Now, in the manufacturing method of the present invention, each grid electrode structure is assembled as shown in FIG. Figure 2a
And as shown in b, a thin Mo material plate 51 is pressed to form a spherical portion 52 with a predetermined radius of curvature. Next, as shown in figure c, the flange portion 3 of the grid support 35 is
6 by welding or brazing. In this state, a grid pattern 53 consisting of a large number of slits defined by fine grid wires is formed in the thin material plate by electric discharge machining or etching as shown in FIG. 4(d). At the same time, a predetermined positioning hole 19 in the flange portion 36 of the grid support 35 is bored by electrical discharge machining or etching.
This determines the positional relationship between the grid pattern and each hole 19. In this way, the control grid structure 27 is assembled. Similarly, as shown in Figures e and f, a thin Mo material plate 58 having a diameter slightly smaller than that of the control grid structure described above is pressed to form a spherical portion 59 with a predetermined radius of curvature. Similarly, next, as shown in FIG. 7g, a thin material plate 58 is joined to the flange portion 39 of the ring-shaped shadow grid support 38 by welding or brazing. In this state, a shadow grid pattern 60 consisting of a large number of slits defined by fine grid wires is formed in the thin material plate 58 by electric discharge machining or etching as shown in FIG. At this time, four positioning holes 20 are simultaneously bored at predetermined positions in the grid support 38 by electric discharge machining or etching. This creates a grid pattern and each hole 2
The positional relationship with 0 is determined. In this way, the shadow grid structure 28 is assembled. The positioning holes 19, 20 of both grid structures are formed at corresponding positions.

Then, as shown in FIGS. 3 and 4, both grid structures are assembled and fixed with each grid pattern aligned. That is, first, as shown in FIG. 3, the control grid structure 27 is fixed by welding to the support ring 14 which is connected to the first outer support tube 15 supporting the Wehnelt electrode 11. At this time, the positioning hole 19 formed in the flange part
is fixed so as to substantially match the hole 12 of the Wehnelt electrode, which has a larger diameter than the hole 12 of the Wehnelt electrode. On the other hand, the shadow grid structure 28 is fixed on the support ring 21 which is integrally fixed to the cathode 31 together with the second outer support cylinder 16 which has been separated in advance. At this time, the upper surface of the support ring 21 is positioned so that the shadow grid electrode 37 is at a predetermined distance from the cathode. Further, the positioning hole 20 formed in the support body 38 is positioned above the support ring 21. Then, as shown in FIG. 4, the rod-shaped jig 30 is inserted into the positioning holes 19, 20 of both grid structures 27 , 28 to define their relative positions, and the outer first and second outer support cylinders 15, Arc welding electrodes P are made to face the 16 welded parts 15a and 16a, and welding is performed. The rod-shaped jig 30 has a large diameter portion 3 at one end.
0a, and the distance between the two grid electrodes in the tube axis direction is determined by the axial dimension L from the lower end surface of the large diameter portion at one end to the ground surface. By using the rod-shaped jig in this way, the relative positions of both grid electrodes in the rotation direction and tube axis direction are defined and aligned. After both grid structures are positioned and fixed by welding and fixing the outer support cylinders 15 and 16, the rod-shaped jig 30 is removed. In this way, an electron gun having the structure shown in FIG. 1 is assembled.

Note that the shadow grid should be made of a material with a high melting point because it is close to the high-temperature cathode, but the control grid should be made of a material with a lower melting point, such as hard copper, stainless steel, or other metal material. Good too. Further, the positioning holes formed in each grid structure may be smaller in the shadow grid structure than in the control grid structure. Then, the assembly may be performed using stepped position regulating rod-shaped jigs having different diameters.

〔Effect of the invention〕

As explained above, in this invention, a metal thin plate as a material for each grid electrode is formed into a spherical shape using a press molding machine, fixed to each grid support by welding or brazing, and then each material is processed by electrical discharge machining or etching. A large number of slits corresponding to the grid pattern are made in the thin metal plate, and at the same time, positioning holes are formed at corresponding predetermined positions on each grid support portion, and then each grid electrode is placed in front of the cathode. In this method, a position regulating rod-shaped jig is inserted into each positioning hole drilled in each grid support to align the grid wires of each grid electrode and fix both grid electrodes. With this, the positional relationship between each grid pattern and the positioning hole can be formed at the same time during electrical discharge machining or etching, so it can be formed with high precision. As described above, the position when assembling the structures can be determined with high precision in both the rotational direction and the tube axis direction by using the rod-shaped shaft. Therefore, the electron gun can be assembled with highly accurate grid alignment as a whole.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of main parts showing a completed electron gun structure according to an embodiment of the present invention, and FIGS. 2a to 2h
3 and 4 are longitudinal cross-sectional views of the main parts showing the state of the parts in subsequent steps, and FIG. 5 shows the structure of the electron gun. 6 is a sectional view of the main part, FIG. 7 is a top view of the main part of the grid,
FIGS. 8a to 8j are state diagrams of parts in each process showing a conventional manufacturing method, and FIG. 9 is an assembled perspective view in a subsequent process. 27... Control grid structure, 28... Shadow grid structure, 31... Concave cathode, 34
... Control grid electrode, 37... Shadow grid electrode, 35, 38... Grid support, 5
DESCRIPTION OF SYMBOLS 1, 58... Material thin metal plate, 53, 60... Grid pattern, 40... Grid wire, 41... Slit, 19, 20... Positioning hole, 30... Rod-shaped jig for position regulation.

Claims (1)

[Scope of Claims] 1. A microwave tube in which a plurality of spherical grid electrodes each fixed to a plurality of grid supports are arranged and fixed in front of a concave cathode with each grid wire aligned and at a predetermined interval. In the method for manufacturing an electron gun, the material thin metal plates for each of the above-mentioned grid electrodes are formed into a spherical shape using a press molding machine, and fixed to each grid support, and then the grids are formed on each of the above-mentioned material thin metal plates by electric discharge machining or etching. Drilling a large number of slits corresponding to the pattern and simultaneously forming positioning holes at corresponding predetermined positions in each of the grid support portions, then placing each of the grid electrodes in front of the cathode, and An electron gun for a microwave tube, characterized in that a rod-shaped jig for position regulation is inserted into each of the positioning holes drilled in each grid support to align the grid wires of each grid electrode and fix both grid electrodes. manufacturing method.