JPH0423371B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing a magnetron.

In general, magnetrons are widely used for heating or defrosting foods by being attached to microwave ovens or defrosting machines because they efficiently generate high-frequency output.

FIG. 1 is a cross-sectional view showing an example of a conventional magnetron. In the figure, 1 is an anode cylinder made of oxygen-free copper, for example, and has a plurality of radially divided anodes on its inner surface. A vane 2 forming a resonant cavity is provided, and the anode cylinder 1 and the vane 2 constitute an anode 3. A plurality of vanes 2 are arranged on the central axis of this anode 3.
A working space 4 is formed by the tip of the working space 4, and a thermionic emission cathode 5 made of, for example, thorium tungsten or the like in a spiral shape is disposed within the working space 4. In this case, a working space 4 with a predetermined distance is formed between the thermionic emission cathode 5 and the tip of the vane 2 . Further, 6 and 7 are end shields arranged at both ends of the thermionic emission cathode 5, respectively, to prevent electrons from deviating in the direction of the central axis. Further, side supports 8a, 8b and a center support 8c are fixed to the bottom surface of the end shield 7, respectively, to fixedly support the thermionic emission cathode 5 and supply operating current. The other end sides of these side supports 8a, 8b and center support 8c extend outward. Moreover, cone-shaped magnetic poles 9 and 10 are provided at both ends of the anode cylinder 1.
are respectively fixedly arranged, and the working space 4
It forms a magnetic path that converges a uniform magnetic flux inside. Furthermore, vacuum sealing members 11 and 12 made of, for example, iron are provided on the outer surfaces of the cone-shaped magnetic poles 9 and 10, respectively, for vacuum sealing the inside of the anode cylinder 1. Or anode 1
Cylindrical permanent magnets 13 and 14 are arranged on the outer surfaces of the vacuum sealing members 11 and 12, respectively, by arc welding. Further, a tin-shaped chiyoke 15 for preventing noise leakage is fixedly arranged on the inner surface of the vacuum sealing member 11, and an output-side insulator 16 formed in a cylindrical shape of ceramic or the like is provided on the outer surface of the vacuum sealing member 11. is firmly connected. An exhaust pipe 17 made of a copper pipe is fixed to the tip of this output side insulator 16.
This exhaust pipe 17 is hermetically pressed to an antenna conductor 18 connected to one end of the vane 2. Further, the outer surface of the exhaust pipe 17 is covered with a metal cover 19, which protects the press-contact portion of the exhaust pipe 17, prevents sparks due to electric field concentration, and functions as a high-frequency antenna. It will be taken outside. Also, anode cylinder 1
A plurality of aluminum heat sinks 20 extending in the tube diameter direction are fitted onto the outer circumferential surface of the tube, and are covered together with the outer circumferential surfaces of the permanent magnets 13 and 14 by a yoke 21 for forming a magnetic path. . Furthermore, a gasket 22 made of metal mesh or the like to prevent radio wave leakage is arranged on the outer surface of the permanent magnet 13, and this gasket 22 is connected to the end of the yoke 21 by a gasket receiver 23 to prevent it from falling off. It is held and fixed between it and the outer peripheral surface of the vacuum sealing member 11.

In the magnetron configured in this way,
When input is supplied from external terminals (not shown) between the side supports 8a, 8b, which also serve as lead wires, and the center support 8c, the thermionic emission cathode 5 is heated, and when a predetermined voltage is supplied to the anode 3,
Thermionic electrons are emitted from the thermionic emission cathode 5. These thermoelectrons act within the magnetic circuits of the magnetic poles 9 and 10 to generate high frequency oscillation, and the output is radiated through the antenna conductor 18 into the oven of a microwave oven, for example.

Now, FIGS. 2a and 2b are diagrams showing the sealed part between the anode cylinder and the magnetic pole of a magnetron.
This is an example of a conventional magnetron having a joining structure in which the outer circumferential ends of the magnetrons are arranged and the inside of the anode cylinder 1 is vacuum-sealed. Reference numerals 11 and 12 are vacuum sealing members made of iron.

According to such a joint structure, in order to vacuum seal the inside of the anode cylinder 1, when the joint part is welded by arc welding, it is difficult to form an alloy with only copper and iron materials, so after arc welding, As shown by symbol A in FIG. 2c, only the very thin part at the tip of the copper and iron is welded. For this reason, pinholes or cracks are likely to occur in this welded portion, and the inside of the anode cylinder 1 cannot be kept vacuum-tight due to poor welding.

In contrast, in the present invention, as shown in FIGS. 3a and 3b, the end 1a of the anode cylinder 1 made of copper material is formed to protrude larger than the ends of the magnetic poles 9 and 10, and arc welding is performed. It is vacuum sealed.

With this configuration, as shown in FIGS. 4a and 4b, the copper material of the anode cylinder is vacuum-sealed in the shape of being soldered and sealed. Therefore, the aforementioned welding defects, cracks, and pinholes are eliminated, and a reliable magnetron can be obtained.

In addition, FIGS. 3 and 4 show an anode cylinder 1,
Although an example of vacuum sealing by welding the magnetic poles 9 and 10 has been shown, as shown in FIG. , this protruding anode cylindrical end 1a is shown in FIG. 5b.
A similar effect can be obtained by welding and vacuum sealing as shown in the figure.

As explained above, according to the magnetron manufacturing method of the present invention, welding work becomes extremely easy, welding performance is greatly improved, there are no cracks or pinholes in the welded part, and quality and reliability are improved. can be significantly improved. Furthermore, extremely excellent effects such as significantly lower production costs and parts unit prices can be obtained.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main part showing an example of a conventional magnetron, Fig. 2 a, b, c is a sectional view of the main part showing an example of a conventional magnetron, Fig. 3 a, b, and Fig. 4 a, b 5 is a cross-sectional view of a main part showing an example of a magnetron according to the present invention, and FIGS. 5A and 5B are cross-sectional views of main parts showing another embodiment of the present invention. 1... Anode cylinder, 3... Anode, 9, 10... Magnetic pole, 11, 12... Vacuum sealing member, 13, 14...
...Permanent magnet, 21...Yoke, 22...Gasket, 23...Gasket receiver.

Claims (1)

[Claims] 1. A method for manufacturing a magnetron in which a sealing member or a magnetic pole made of an iron material is welded and fixed to both ends of an anode cylinder made of a copper material to maintain a vacuum inside the anode cylinder. The thin part for arc welding sealing is made to protrude longer than the end face of the arc welding sealing part of the sealing member or magnetic pole to which it is directly fixed by welding, and the arc welding seal provided on the anode cylinder during arc welding. A method for manufacturing a magnetron, characterized in that the sealing member or the sealing portion of the magnetic pole is covered with the anode cylindrical member by applying an arc to the vicinity of the thin-walled portion for melting.