JP2749064B2 - Manufacturing method of filter case for magnetron - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a metal-made housing for storing a low-pass filter provided for supplying power to a cathode while preventing leakage of microwaves in contact with the outside of a cathode of a magnetron tube. Manufacture of a magnetron filter case having a closed structure that prevents even the fifth harmonic of microwaves from leaking from the cover when the cover of the magnetron filter case comprising the case and the cover is put on the case. About the method.

[Prior Art] A magnetron used in a home microwave oven has a metal housing for storing a low-pass filter for supplying power to a cathode while preventing leakage of microwaves by contacting the outside of the cathode of a tube. A filter case consisting of a lid is attached, but in recent years it has become necessary to reliably shield up to the fifth harmonic of microwaves according to laws and regulations, and the cover of the filter case and the lid must be tighter. Is needed.

[Problems to be Solved by the Invention] In order to satisfactorily obtain the shielding effect of the filter case, a gap generated at a fitting portion between the housing and the lid, particularly, a gap having a length exceeding a predetermined value becomes a problem. Therefore, by intermittently caulking the fitting portion, a long gap is not generated in the fitting portion.However, since the housing and the lid are made of a relatively thin metal plate, It is said that when pressure is applied from the outside, warpage or deformation is likely to occur, and also due to warpage or deformation due to elasticity of itself, the fitting portion is likely to loosen, and it is difficult to always obtain a satisfactory shielding effect. There was a problem.

As a countermeasure against such a problem, Japanese Utility Model Application Laid-Open No. 62-88359 discloses a U-shaped cross-sectional groove which is inserted into the outer peripheral edge of the lid and is bent in a zigzag shape together with the open edge. It is described that it is provided. But if you do this,
Since the edge of the housing opening connected to the side where the feedthrough capacitor is mounted on the metal housing is also bent in a zigzag manner, the mounting portion of the feedthrough capacitor is not flat due to the effect, and the chassis plate of the feedthrough capacitor (earth plate) ), And as a result, it is difficult to obtain a satisfactory shielding effect.

The present invention does not cause the problem as in the conventional countermeasure technique described above, has high adhesion of the cover fitting portion between the peripheral edge of the housing opening of the filter case and the lid, and has the microwave shielding effect of the fifth harmonic. It is an object of the present invention to provide a sufficiently good filter case even when the filter case is used.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, an eaves-like portion that projects outward at substantially right angles is provided on the entire periphery of the housing opening, and the outer periphery of the groove is provided on the entire periphery of the lid. A first concave groove whose wall surface fits and contacts the inner surface of the upper end of the entire periphery of the housing opening, and the eaves-shaped portion of the housing periphery contacts the bottom surface of the groove, sharing the outer wall as its own inner wall. A second concave groove to be inserted and fitted to the upper surface, and a lid is placed on the housing opening at the peripheral edge as described above, and then the outer wall of the second concave groove is substantially perpendicular to the inner bottom surface side. The case is folded so as to be in contact with the back surface of the eaves-like portion of the housing, and a three-layer laminated portion sandwiching the eaves-like portion with the bottom surface at the bent portion is formed. In order to further enhance the adhesiveness of the three-layer laminated portion, if pressure is applied to the laminated surface of the three-layer laminated portion at right angles to bend the laminated portion in a wavy shape along the periphery of the housing, still better results can be obtained. Can be

[Operation] By taking the above-described means, the housing and the lid are connected to the upper end portion of the housing opening side wall and the outer wall surface of the first concave groove of the lid, and the projecting surface of the housing side wall upper end and the second portion of the lid. The bottom surface of the groove and the three-layer laminated portion formed by the outer surface make contact with each other, and these two contact surfaces are substantially orthogonal to each other. The effect of the bending operation to (3) or the pressing operation on the three-layer laminated portion is unlikely to spread to the side wall surface of the housing, and the shielding state of the feeder lead-out portion by the feedthrough capacitor is well maintained. In addition, the contact surface is vertically double in the three-layer laminated portion. Therefore, the close contact state of the fitting contact portion between the cover of the filter case and the housing according to the present invention is extremely good, and the shielding effect is naturally good.

[Embodiment] FIG. 2 shows a state before the cover of the embodiment of the present invention is covered with the lid.
It is sectional drawing of the state at the time of each independently (however, the housing | casing is fixed to a magnetron main body). One end of an annular permanent magnet 3 stacked on the cathode side magnetic pole part 2 of the magnetron 12 is magnetically coupled to the magnetic pole part 2, and the other end is connected to the other magnetic pole part of the magnetron 1 via the frame yoke 4. Are combined. In a metal housing 5 fixed on the outer end surface of the frame-shaped yoke 4, a stem portion 6 (a cathode terminal side metal sealing member 6a and a cathode side insulator 6b) serving as a cathode terminal lead-out portion of the magnetron 1 and the stem portion 6 are provided. A choke coil 8 having one end connected to the cathode terminal 7 of the section is stored. A through-type capacitor 9 is provided on the side surface 5a of the housing 5,
The chassis plate 9a of the capacitor and the side surface 5a are fixed with a dovetail.

The other end of the choke coil 8 is connected to a through conductor of the through capacitor 9. The open end of the housing 5 is terminated in an outwardly bent form (terminal end or overhang portion).
5c).

On the other hand, the metal cover 10 covering the opening of the housing 5 has a first U-shaped concave groove 10a on the outer periphery over the entire circumference, and further has an outer surface 10d of the first concave groove. 2nd to be inside
Is provided outside the first groove, and in the final stage of assembly of the magnetron device, the opening concave end projection 5c and a part of the side surface 5a of the housing 5 It is assembled so as to enter the concave groove 11. Then, the outer surface of the groove 11
10b is bent so as to be in contact with the back surface of the overhang portion 5c of the housing 5 that has entered the groove 11, and this overhang portion 5c is
The three-layer laminated portion 12 shown in FIG. FIG. 1 is a diagram showing a state in which a filter element or the like housed inside is removed for simplicity, a lid 10 is put on a housing 5, and a cover is brought into close contact with the case like mounting. Outer side surface 10b of the second groove 11
At the time of bending work, at the four corners of the lid, the flesh at the end of the outer surface 10b is excessive and wrinkles are likely to occur, but a large long gap is not generated between the bent outer surface 10b and the housing opening overhanging portion 5c. It is necessary to consider the processing jig. However, although a mild steel plate is usually used as a material metal, it is a material that is well-known and easy to process, so such a process is not difficult if attention is paid.

In order to improve the close contact state between the respective surfaces of the three-layer laminated portion 12, pressure is applied by sandwiching the corrugated tools from each other from a direction perpendicular to the laminated surface, and the laminated portion is pressed along the peripheral edge of the housing.
As shown in FIG. 1a, even if a gap is formed, a contact portion is surely formed at short intervals even if a gap is formed, so that a better shielding effect can be obtained more reliably.

[Effects of the Invention] As described above, according to the present invention, the filter case does not deform the side surface of the housing and a long wide gap does not occur in the fitting portion between the housing and the cover. Therefore, leakage of electromagnetic waves can be suppressed even after long-term use, and a good shielding effect can be obtained while using a relatively thin metal plate material. Further, since the side surface of the housing is not deformed, the state in which the chassis plate of the feedthrough capacitor is in good contact with the side surface of the housing is not impaired, and mass productivity is improved.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which a lid is put on a housing and a cover eye is brought into close contact with each other. FIG. FIG. 2 is a view showing an improved state, and FIG. 2 is a sectional view of a part of an embodiment of the present invention. 1 ... magnetron, 5 ... housing, 5c housing open end overhang, 8 ... choke coil, 10 ... lid, 10a ... first
... Second groove, 12... Three-layer laminated portion.

Claims (2)

(57) [Claims] 1. Manufacture of a magnetron filter case comprising a metal housing and a lid for storing a low-pass filter provided for supplying power to a cathode while preventing leakage of microwaves in contact with the outside of a cathode of a magnetron tube. In the method,
A first concave groove in which an outer wall surface of the groove contacts an inner surface of an upper end of the entire periphery of the housing opening; A second concave groove which shares the outer side wall as an inner side wall of each other and is inserted and fitted until the eaves-shaped portion of the peripheral edge of the housing comes into contact with the bottom surface of the groove; After covering as described above, the outer wall of the second concave groove is bent at an almost right angle toward the inward bottom surface side to contact the back surface of the eaves-like portion of the housing, and the bent portion and the bottom surface together with the bottom surface 3 sandwich the eaves
A method for manufacturing a filter case for a magnetron, comprising forming a layer laminated portion. 2. The method for manufacturing a magnetron filter case according to claim 1, wherein a pressure is applied at a right angle to the lamination surface of the three-layer lamination portion to bend the lamination portion in a wavy shape along the periphery of the housing.