JPS596021B2 - Magnetronno Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a directly heated cathode for, for example, a magnetron for a microwave oven.

An example of a conventionally commonly used manufacturing method for a directly heated cathode for a magnetron using a thorium tungsten filament will be explained with reference to FIGS. 1 to 5.

Figure 1 shows the thickness of the material fixed to the cathode bushing.
．． A cylindrical cathode support 11 made of thin molybdenum plates of , , and a molybdenum end hat 1 on the cathode bushing side.
2, the point a1 is arc welded in a hydrogen atmosphere.

Figure 2 shows the next step.

A cathode support 13 made of a tungsten rod having a diameter of 2 Wtm is electrically insulated from the cathode support 11, fixed to the cathode bushing, and arranged concentrically with the cathode support 11.

The directly heated cathode 14, which is made by winding a thorium tungsten filament with a wire diameter of 0.6 mm in a spiral shape with an outer diameter of 5 mr/L, and the molybdenum end piece 15 on the top of the cathode are positioned using all the jigs as shown above. The fitting point a2 of the end hat 12 and the cathode support 13 is arc welded in a hydrogen atmosphere.

Next, point P1 and P2 are heated to 1769 by induction heating using high frequency.
Heat to above 0.1° and platinum braze.

The next step will be explained with reference to FIG. The cathode product 2 is placed in a bell jar 16, and a mixed gas flow of benzene and hydrogen is introduced from the top 11 of the bell jar 16, and the directly heated cathode 14 is electrically heated and carbonized.

Figure 4 shows a getter 18 manufactured by punching out a 0.1 mm thick zirconium plate, which is similar to the cathode product 2.
It is provided with a fitting passage 19 for loading.

The final step of cathode assembly will be explained with reference to FIG.

The getter 18 is fitted into the carbonized cathode product 3 at points r and j.
Resistance weld r2.

By the way, one drawback of this manufacturing method or magnetrons made using this manufacturing method is that the assembly method differs depending on each process, making it necessary to change workers and work stations depending on the process, and the wide variety of manufacturing equipment makes it difficult to manage and invest in equipment. There are some drawbacks.

Another drawback is that loading platinum solder during platinum brazing is a delicate process, and that excess white wax may flow along the filament and shorten the effective cathode section, which requires a relatively high level of skill. That's what it takes.

Another drawback is that getter loading is a delicate process and resistance welding requires relatively high skill, and gettering easily peels off from the notch.

Another drawback is that the end hats are made of molybdenum for heat resistance and are manufactured by cutting, which is relatively expensive.

This invention solves the above-mentioned problems.
The inner diameter of the nodular part of the end hat made by the method is brought into contact with the outer diameter of the tungsten filament, and the contact point is preferably connected to the magnetron by irradiating a laser beam from the outside of the nodal part of the end hat. This is a method of manufacturing.

This invention will be explained in detail with reference to the drawings below.

An embodiment of the present invention will be explained with reference to FIGS. 6 to 10.

In FIG. 6, a cylindrical cathode support 21 made of a molybdenum thin plate with a thickness of 0.1 mm and a cathode support 23 made of a tungsten rod with a diameter of 2 mm are concentrically and electrically insulated and fixed to the cathode bushing. There is.

An end piece 22 on the cathode bushing side having a flange-like part and a cylindrical part manufactured by press working from a thin molybdenum plate with a thickness of 0.2 mvr is fitted onto the outside of the cathode support 21 to form a laser beam generator. Spot welding is performed by applying the Lede beam obtained from the above from the direction indicated by t.

Also in the following description, the welding positions and directions by the laser beam are indicated by arrows 12, 13, . . . .

Next, a directly heated cathode 2 is made by winding a thorium tungsten filament with a wire diameter of 0.6 nm in a spiral shape with an outer diameter of 5 mm.
4 and a 0.2-mm-thick molybdenum thin plate by press working, the t-shaped support 25 is positioned with a jig and fitted into the end 22 and the cathode support 23, and the laser beam t2 is inserted. , 13. Spot weld at 1°.

At this time, the inner part of the end piece 22 and the cup-shaped support 25 are brought into contact with the outer diameter part of the surface heating type cathode 24.

Next, carbonization is performed in the same manner as described above.

The next step will be explained with reference to FIG.

The thickness is 0.0 mm as shown in FIG. A getter 28 manufactured by punching out a zirconium plate of Im is spot-welded to the end point 22 using a laser beam t5.

The final process will be explained with reference to FIGS. 9 and 10.

Manufactured by press processing from a thin molybdenum plate with a thickness of 0.2 mm (also, the above getter 28 is attached to the end hat 26 on the top of the cathode).
are welded with laser beam t6.

Next, the top end
・Spot weld the semi-finished product 6 with the laser beam t7.

FIG. 11 shows another embodiment of the invention.

The manufacturing method and structure are the same as in the previous embodiment except that the direction in which the end piece 32 is fitted into the cathode support 31 is reversed.

However, in this example, the getter 33 has a structure in which it is held between a support 35 and an end 36.

The magnetron manufacturing method described above and the magnetron obtained by this method can eliminate carbonization and narrow down the process to laser beam welding, so there is no need to change workers or work stations, and work and equipment management is easy; There are no problems associated with platinum brazing, the getter is easy to load and weld, there is no cut in the getter, so there is no peeling from here, and the end hat and support parts can be made by press processing from heat-resistant thin metal sheets. This has advantages such as low precipitation, increased vibration resistance and impact resistance because the cathode is lightweight, and easy centering of the tungsten filament.

[Brief explanation of the drawings] Figures 1, 2, and 5 are diagrams showing the conventional manufacturing method of a thorium tungsten cathode, Figure 4 is a diagram showing the shape of a conventional getter, and Figure 3 is a diagram showing the carbonization method. Figures showing Figure 6, Figure 1,
9 and 10 are diagrams showing one embodiment of the manufacturing method of this invention, FIG. 8 is a diagram showing the shape of a getter used in the manufacturing method of this invention, and FIG. 11 is a diagram showing another embodiment of this invention. It is a diagram. 21... Cathode support, 22... End, 2
3... Cathode support, 24... Direct heating type cathode, 25...
・Cop-shaped support, 26... End hat, 28...
- Getter, 31... Cathode support, 32... End hat, 35... Cup-shaped support, 36... End.
・T, 38...getta.

Claims (1)

[Claims] 1. Cathode supports 2 mutually fixed to the cathode bushing part.
L31 and a rod-shaped cathode support 23 extending further along the axis than this support, a cylindrical portion and a flange-shaped portion having an inner diameter dimension equivalent to the outer diameter dimension of the spiral filament directly heated cathode 24. The cathode bushing side thin metal plate ends (22, 32) having the above-mentioned cathode support 21,
31 and welding and fixing by applying a laser beam from the outside of the end piece, and then inserting the cathode 24 from the tip side of the rod-shaped cathode support 23 into the cylinder of the end hole 22.32. At the same time, the other end of the cathode 24 is fitted with a cup-shaped support 25.35 made of a thin metal plate having an inner diameter equivalent to the outer diameter of the cathode, and the central cylindrical part thereof. 22. Fitting the end portion of the rod-shaped cathode support 23 into the end portion of the cathode 23;
32 by applying a laser beam from the outside of the end cylindrical part, and welding the other end of the cathode 24 and the cup-shaped supports 25, 35 by applying a laser beam from the outside of the supports. a step of applying and welding, a step of electrically connecting the central cylindrical portion of the cup-shaped support 25°350 and the tip of the rod-shaped support, and a step of carbonizing the cathode and the surface portion of the rod-shaped support. A method for manufacturing a magnet (magnet) comprising: