JPS61240529A - Manufacture of cathode assembly for magnetron - Google Patents

Abstract

PURPOSE:To enhance the accuracy of assembly work, by stacking a cathode and a second end plate on a first end plate, and performing high-frequency induction heating in a vacuum or the like while placing the second end plate in pressure contact with the flat end face of second lead wire. CONSTITUTION:A cathode assembly for a magnetron comprises a first end plate 2 fixed with a first lead wire 4, a spiral cathode 1, and a second end plate 9 fixed with a second lead wire 5. The end face of the second lead wire 5, which is made of molybdenum and extends through the cathode 1 along its axis without coming into contact with the cathode, is finished to be a plane perpendicular to the axis of the second lead wire. The cathode assembly is subjected to high-frequency induction heating by a coil 11 in a vacuum or a reducing gaseous atmosphere while the second end plate 9 made of molybdenum is placed on the end face of the second lead wire 5 under pressure 10, so that the second end plate and the second lead wire are conjoined to each other. Easy accurate assembly work can thus be performed without using a complicated jig.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a cathode assembly for a magnetron, which comprises a spiral cathode and a support member that supports the cathode.

Conventional technology 2 - In general, the cathode structure of a magnetron used in a microwave oven, etc. is constructed as shown at 914 in FIG. 1, a second neck 3 that fixes the other end of the throat 2 and 5, and a first neck 2.
A first lead wire 4 has one end fixed to the lower surface of the second end hat 3, and a second lead wire 4 passes through the first end hat 2 and the cathode 1 without contact and has one end fixed to the center of the second end hat 3. It is supported by a support member consisting of a lead wire 6 and is supplied with power through the support member. In addition, the first.

2nd Entno., 2, 3 and 1st. The second lead wires 4 and 6 are made of a high melting point metal such as molybdenum.
The other end portions of the second lead wires 4 and 6 hermetically penetrate the bottom plate portion of the ceramic stem 6 and protrude to the outside of the tube.

In manufacturing such a cathode structure, the cathode 1 and the second antenna 3 are sequentially and coaxially stacked on the first connector 2 fixed to the first lead wire 4, and the second connector・The second hole inserted into the center hole 3a of the cut 3
One end of the lead wire 5 is fixed by soldering with a high melting point brazing material 7 or by plasma arc welding using a torch. and are only in loose contact within the center hole 3a, so the second end hat 3 during soldering or welding
A second jig 8 is required to hold it in place.

The jig 8 is located around the cathode 1 and plays the role of a spacer to regulate the mutual spacing between the first and second end hats 2 and 3, and also has the function of preventing the second end hat 3 from lifting up. The structure is relatively complicated, and its installation and removal are quite complicated. However, the jig 8 also suffered from high-temperature deterioration, which was one of the factors preventing improvement in assembly accuracy and reduction in manufacturing costs. Furthermore, solder materials made of platinum, ruthenium-molybdenum alloys, etc. are expensive, and it is not only difficult to supply them in the right amount in the right place, but also because brazing is difficult at times.
There was also a problem in that the cathode support member was likely to become brittle and deformed due to the high temperature of 000°C or higher. Furthermore, it is suitable for arc welding.

Problems to be Solved by the Invention Accordingly, an object of the present invention is to attach the second end hat to the second end without using a complicated jig as described above and without deforming the cathode support member. An object of the present invention is to provide a method for manufacturing a cathode structure that can be fixed to a second lead wire.

Means for Solving the Problems According to the present invention, while the second end hat is pressed against one flat end surface of the second IJ lead wire which penetrates the first end hat and the spiral cathode when they come into contact with each other, The pressure-welded portion is heated by high-frequency induction heating in a reducing gas atmosphere in a vacuum chamber or in a reducing gas atmosphere to join the second end hat to the second lead wire.

Function: In this way, the flat end surface of the second lead wire 6.

When the second end hat is strongly pressed against the second end hat and high-frequency induction heating is performed, both members are diffused and joined together at a temperature below their recrystallization temperature. Note that the second lead wire is usually about 2
Made of molybdenum with a wire diameter of φ? The second end hat can be kept in a horizontal position simply by finishing one end surface into a plane perpendicular to the line axis, and no complicated jig is required.

Embodiment As shown in FIG.
As is conventional, a spiral cathode 1 made of thorium tungsten and a second end hat 9 made of molybdenum are sequentially and coaxially stacked on the first end hat 2. However, the second end hat 9 does not have a central hole, and when the lower surface of the center comes into contact with the first end hat 2 and the cathode 1, it comes into contact with one end surface of the second lead wire 5 made of molybdenum that passes through the first end hat 2 and the cathode 1. The lead wire 5 is pressed against the second lead wire 5 by a reduction blade 10 of about 100 kg applied from above.

The second lead wire 6 has a wire diameter of about 26 mm, and one end surface is finished to be a plane perpendicular to the wire axis, so the reduction blade of 1° acts on the second lead wire 6. The second end hat 9 remains in a horizontal position.

The temporarily assembled structure is assembled in a vacuum and in a reducing gas atmosphere by connecting the second end hat 9 and the second lead wire 5.
The pressure contact portion is heated by high frequency induction, and the two are diffused and joined together by this heating. Note that the heating is set at a temperature below the solidus line of the base material Darmolybdenum, preferably at about 100Q°C, which is lower than the recrystallization temperature (about 12oO°C). 11 indicates a coil for high frequency induction heating.

One flattened end surface of the second lead wire 5 can be coated in advance with a plating layer 12 of a different metal as shown in FIG. In another embodiment shown in FIG. 3, the surface of the second end hat 9 is coated with a plating layer 13 of a different metal. The materials for the plating layers 12 and 13 are silver, copper, and nickel.

Titanium, tantalum, niobium, tungsten, etc. can be used alone or in a composite form, but by configuring it in this way, the heating temperature and time during bonding, as well as the reduction blade, can be selected to appropriate values. be able to. Note that the plating layer can be provided on both the second lead wire 5 and the second end hat 9 by only one dimension.

Effects of the Invention Since the present invention is constructed as described above, the second upper end throat is connected to one end of the second lead wire with high precision.
Moreover, the end hat can be fixed at low cost without using solder or complicated jigs, and the cathode support member is not deformed, so that the end hat's original function can be fully demonstrated.

[Brief explanation of the drawing]

FIG. 3 is a cutaway perspective view showing essential parts of another embodiment of the present invention, and FIG. 4 is a side sectional view of a conventional cathode assembly. DESCRIPTION OF SYMBOLS 1...Cathode, 2...1st node, 4...1st lead wire, 5...2nd lead wire, 9... ...Second end hat, 10...
・Reducing blade, 11... Coil for high frequency induction heating.

Claims (1)

[Claims] A spiral cathode and a second end hat are sequentially and coaxially stacked on a first end hat fixed to one end of a first lead wire, and the first end hat and the cathode are brought into contact with each other. While the second end hat is pressed against one flat end surface of the second lead wire that has passed through the second lead wire, the pressed part is heated by high frequency induction in a vacuum or a reducing gas atmosphere, and the second end hat is heated by high frequency induction heating in a vacuum or a reducing gas atmosphere. A method for manufacturing a cathode assembly for a magnetron, the method comprising joining it to a second lead wire.