JPH0756777B2 - Method for manufacturing magnetron device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetron device including a magnetron and an exciting circuit member thereof.

2. Description of the Related Art Generally, a magnetron device used in a microwave heating device such as a microwave oven is configured as shown in FIG. 2, and the magnetron 1 includes a first and a second magnetic pole piece 2 facing each other,
3 has anode cylinders 4 at both open ends. The outer end surface of the first magnetic pole piece 2 is covered with the flange portion 5a of the eyelet-shaped metal cylinder body 5, and the metal cylinder body 5 is sealed to the anode cylinder body 4 at the outer peripheral edge of the flange portion 5a. There is. Then, the microwave output terminal 8 is sealed to the metal tubular body 5 via the insulating ring 7. The outer end surface of the second magnetic pole piece 3 is covered with the flange portion 9a of the dovetail-shaped metal tubular body 9, and the outer peripheral edge of the flange portion 9a is sealed to the anode tubular body 4 so that The cathode terminal lead-out stem 10 is sealed.

A large number of heat radiation fins 11 are attached to the outer peripheral surface of the anode cylinder 4 in multiple stages, and the first annular magnetic ring 11 is coaxially stacked on the outer end surface of the first magnetic pole piece 2 via the flange portion 5a. The permanent magnet 12 of the first magnetic pole piece 2 has the one magnetic pole surface 12a at the first magnetic pole piece 2a.
Is magnetically coupled with. Further, the annular second permanent magnet 13 coaxially superposed on the outer end surface of the second magnetic pole piece 3 via the flange portion 9a has the one magnetic pole surface 13a and the second magnetic pole piece 3. Magnetically coupled first and second permanent magnets
The other magnetic pole surfaces 12b and 13b of the magnets 12 and 13 are magnetically coupled to each other by a frame yoke 14 that surrounds the permanent magnets 12 and 13 and the radiation fin 11. Reference numeral 15 indicates a metal shield case that houses the LC filter circuit member, and 16 indicates an auxiliary yoke plate.

During operation of the magnetron 1, the anode cylinder 4 and the magnetic pole pieces 2, 3
When the temperature becomes high, the temperature of the permanent magnets 12 and 13 made of ferrite also rises, which may cause irreversible demagnetization of the magnets. Therefore, small protrusions 17 and 18 are provided on the flange portions 5a and 9a, and the space between the pole piece 2 and the permanent magnet 12 and between the pole piece 3 and the permanent magnet 13 are provided.
There is a small gap for insulation between and. Further, while the forced air cooling airflow is circulated between the radiation fins 11,
Both side edges of the heat radiating fin 11 are brought into contact with both side walls of the frame yoke 14 to expand the heat radiating area.

Problems to be Solved by the Invention In the conventional magnetron device configured as described above, it is possible to prevent the coercive force from declining due to the high temperature of the permanent magnets 12 and 13, but at least the frame for that purpose. A considerable amount of forced air-cooling airflow must be sent into the yoke 14. Otherwise, as the temperature of the anode cylinder 4, the pole pieces 2 and 3, and the metal cylinder 9 rises, the heat radiation fins 11 and the frame yoke 14 also become hot, and the frame yoke 14
This is because the temperature of the permanent magnets 12 and 13 thermally coupled to the temperature rises remarkably. Therefore, it has been almost impossible to reduce the number of heat radiation fins to be used or to reduce the size thereof.

Means for Solving the Problems According to the present invention, a filter made of filter paper is laid in the compression molding die of the permanent magnet, and the mesh surface of the filter causes the second magnetic pole surface, that is, the outer magnetic pole surface of the permanent magnet to be formed. , Has a lot of fine irregularities.

Function With this structure, the degree of thermal coupling between the permanent magnets and the frame yoke is reduced, the transfer of heat from the frame yoke to the permanent magnets is reduced, and the heat dissipation fins are downsized and the number of sheets used is reduced. Alternatively, it is possible to reduce the amount of forced air cooling airflow. Besides,
No complicated secondary processing is required to form the irregularities, and the filter paper laid in the compression molding die for forming the irregularities acts as a drainage filter, so that the effect of two birds with one stone can be obtained.

Embodiment An embodiment of the present invention is shown in FIG. 2 is different from the conventional configuration shown in FIG. 2 in that the first and second annular permanent magnets 19 and 20 made of ferrite are
The point is that a large number of fine irregularities 21 and 22 are provided on the respective outer end surfaces, and other configurations are the same.

The irregularities 21 and 22 are formed in the process of molding the permanent magnets 19 and 20 by compression molding. It is sufficient that the projection length and the projection width of the irregularities 21 and 22 are each about 0.2 mm to 0.8 mm. Such a concavo-convex surface can be easily formed by the mesh surface of this filter simply by laying a filter for the filter paper inside the molding die used in the compression molding step, and the filter is the compression molding. Sometimes it acts as a drain filter.

In the above-described embodiment, the first and second permanent magnets 19 and 20 are provided with the irregularities 21 and 22 on their outer end faces, respectively. However, even if only one of the permanent magnets is provided with the irregularities on their outer end faces. Well, it is equally applicable to magnetron devices having only a single permanent magnet.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, the filter paper laid in the compression molding die of the permanent magnet causes many fine irregularities on one end surface of the permanent magnet. The effect of two birds with one stone can be obtained because it also functions as a filter for draining water. Moreover, the number of minute irregularities that are uniformly generated without secondary processing can reduce the degree of thermal coupling between the permanent magnets and the frame-like yoke, downsizing the heat radiation fins, and reducing the number of sheets used. Alternatively, it is possible to reduce the amount of air blown.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view of a magnetron device embodying the present invention, and FIG. 2 is a partially cutaway side view of a conventional magnetron device. 2,3 …… Pole piece, 4 …… Anode cylinder, 11 …… Radiation fin, 1
4 …… Frame-like yoke, 19,20 …… Permanent magnets, 21,22 …… Unevenness.

Claims (1)

[Claims] 1. A magnetron having a large number of heat radiation fins mounted in multiple stages on an outer peripheral surface of an anode cylinder, and a first magnetic pole piece stacked on the first magnetic pole piece of the magnetron so that the first magnetic pole surface is magnetically attached to the magnetic pole piece. A permanent magnet made of ferrite bonded to the permanent magnet; and a frame yoke for magnetically coupling the second magnetic pole surface of the permanent magnet to the second magnetic pole piece of the magnetron. In the manufacture of the magnetron device which is thermally coupled to the magnetic pole surface of 2 and the radiation fin, a filter made of filter paper is laid in the compression molding die of the permanent magnet, and the mesh surface of the filter is used to A method of manufacturing a magnetron device, characterized in that a large number of fine irregularities are provided on a magnetic pole surface of the.