JP2000149802A - Magnetron device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetron device preventing a stud bolt from coming out without losing an oscillation function and its manufacturing method. SOLUTION: An attaching hole 21c is provided to a part of a ferromagnetic substance yoke 21 arranged in the outside of a magnetron body. A stud bolt 23 is provided with a flange part 23b and a screw part 23a, and is also provided with a protuberance 23c in a surface of a side the flange part 23b on the side of the screw part 23. The screw part 23a of the stud bolt 23 is inserted into the attaching hole 21c of the ferromagnetic substance yoke 21, and the ferromagnetic substance yoke 21 is welded to the protuberance 23c of the stud bolt 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetron device in which a ferromagnetic yoke plate and a mounting stud bolt are joined by projection welding, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a magnetron device used for a microwave oven or the like, permanent magnets are arranged above and below a magnetron body. A radiation fin is arranged around the magnetron body, and a ferromagnetic yoke for forming a magnetic path is provided outside the permanent magnet and the radiation fin. A stud bolt for fixing the magnetron device is attached to the ferromagnetic yoke.

Here, a conventional magnetron device in which stud bolts are attached to a ferromagnetic yoke will be described with reference to FIG. FIG. 4A shows a portion where a stud bolt is attached to a ferromagnetic yoke. Reference numeral 41 denotes a ferromagnetic yoke, and a hole 41a is formed in a part of the ferromagnetic yoke 41. And
A stud bolt 42 is attached to the hole 41a. In addition, the stud bolt 42 has a flange portion 42a.
And a knurl portion 42b, a screw portion 42c, and the like.

[0004] Next, a method of attaching a stud bolt 42 to a ferromagnetic yoke 41 will be described with reference to FIG.
This will be described with reference to FIG.

First, as shown in FIG. 4A, a stud bolt 42 is inserted into a hole 41a of a yoke 41 made of a ferromagnetic material. Next, the stud bolt 42 is inserted into the space 43a of the die portion 43 of the press machine. Also, stud bolt 4
The punch portion 44 is applied to the second flange portion 42a. Then, the ferromagnetic yoke 41 and the flange portion 42a of the stud bolt 42 are sandwiched between the die portion 43 and the punch portion 44 from both sides, and a force is applied in the arrow Y direction. Thus, the knurled portion 42b of the stud bolt 42 is pressed into the hole 41a of the ferromagnetic yoke 41, and the stud bolt 42 is attached to the ferromagnetic yoke 41.

The ferromagnetic yoke into which the stud bolts are press-fitted is assembled into a magnetron body or the like in a later assembling step, and is assembled into a magnetron with a thread for mounting.

[0007]

In a conventional magnetron device, a stud bolt is press-fitted into a hole of a ferromagnetic yoke using a press machine. For this reason, if the diameter of the hole formed in the ferromagnetic yoke or the diameter of the knurled part of the stud bolt varies, or if the bonding strength varies due to wear of the press machine, etc., after mounting, Stud bolts may come off.

When a stud bolt is press-fitted into a ferromagnetic yoke integrally assembled with the magnetron main body for reasons such as simplification of man-hours, the vibration of the press machine is transmitted to the oscillating portion of the magnetron main body and the like. Function may be impaired.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and to provide a magnetron device which prevents stud bolts from coming off and does not impair the oscillation function, and a method of manufacturing the same.

[0010]

SUMMARY OF THE INVENTION The present invention provides a magnet for forming a magnetic field in an oscillating portion of a magnetron body, a ferromagnetic yoke for forming a magnetic path of a magnetic flux generated by the magnet, and a ferromagnetic yoke for forming a magnetic path. In a magnetron device including a stud bolt attached to a yoke, the ferromagnetic yoke and the stud bolt are joined by welding.

The method for manufacturing a magnetron device according to the present invention further comprises the steps of: providing a mounting hole in a part of a ferromagnetic yoke disposed outside the magnetron body; providing a flange portion and a screw portion; Inserting the screw portion of the stud bolt having a protrusion formed on the surface of the flange portion on the screw portion side into a mounting hole of the ferromagnetic yoke, so that the protrusion formed on the flange portion has the strength. Arranging the flange portion of the stud bolt to be connected to one electrode, connecting the ferromagnetic yoke to the other electrode, and Applying a voltage between the electrode and the other electrode to weld the ferromagnetic yoke and the stud bolt.

[0012]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1A is a front view showing a part of the left half in a cross section. FIG. 2B is a perspective view. Reference numeral 11 denotes a magnetron body that generates a high-frequency signal. The magnetron body 11 includes an anode cylinder 12 that constitutes an oscillating unit, a cathode 13 located at the center of the anode cylinder 12, and poles located at both upper and lower ends of the anode cylinder 12. It comprises a piece 14, an anode vane 15 provided radially inside the anode cylinder 12, a strap ring 16 connecting the anode vanes 15, and an output antenna 17 for taking out a high-frequency signal to the outside.

Further, annular permanent magnets 18 and 19 are arranged above and below the magnetron body 11.
A radiator 20 including a plurality of cooling fins is press-fitted around the magnetron body 11. Further, a first ferromagnetic yoke 21 is provided in contact with the upper permanent magnet 18, and both ends of the first ferromagnetic yoke 21 are connected to form a first U-shaped cross section. 2 ferromagnetic yoke 2
2 are provided. The first and second ferromagnetic yokes 21 and 22 form a magnetic path connecting the upper and lower permanent magnets 18 and 19. A plurality of stud bolts 23 are attached to the first ferromagnetic yoke 21.

A shield case 2 for accommodating a filter circuit and the like is provided below the second ferromagnetic yoke 22.
4 is provided, and a capacitor 25 forming a filter circuit is attached so as to penetrate the shield case 23.

The line MM indicates the tube axis.

Here, the structures of the first ferromagnetic yoke 21 and the stud bolt 23 will be described with reference to FIG. In FIG. 2, portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and overlapping description is partially omitted.

As shown in FIG. 2A, the ferromagnetic yoke 21 has a substantially square shape as a whole. For example, four outwardly protruding flange portions 21a are provided at four peripheral portions thereof. Have been. A large hole 21b is formed in the center,
A mounting hole 21c is formed in each flange 21a.

On the other hand, the stud bolt 23 is shown in FIG.
As shown in FIG. 5, the projection 23c is composed of a screw portion 23a, a flange portion 23b, and the like. A plurality of projections 23c for projection welding are provided on a surface of the flange portion 23b on the screw portion 23a side.

Next, a method of attaching the stud bolt 23 to the ferromagnetic yoke plate 21 will be described with reference to FIG. In FIG. 3, portions corresponding to FIG. 1 and FIG. 2 are denoted by the same reference numerals, and duplicate description will be partially omitted.

First, as shown in FIG. 3A, a stud bolt 23 is attached to a mounting hole 21c of a ferromagnetic yoke plate 21.
Is inserted. Then, as shown in FIG. 3B, the plurality of projections 21c provided on the flange portion 21b of the stud bolt 23 come into contact with the surface of the ferromagnetic yoke plate 21, for example, the surface of the peripheral portion of the mounting hole 21c. Let it.

Next, the flange portion 2 of the stud bolt 23
1b is connected to an upper electrode 31 for projection welding, and the back surface of the ferromagnetic yoke plate 21 is connected to a lower electrode 32 for projection welding. The lower electrode 32 is provided with a space 32a into which the screw portion 23a of the stud bolt 23 is inserted.

Next, a voltage is applied between the upper electrode 31 and the lower electrode 32 and the ferromagnetic yoke plate 21 and the stud bolt
The projection welding. The ferromagnetic yoke 21 and the stud bolt 23 are welded at four flange portions 21a of the ferromagnetic yoke.

Next, the ferromagnetic yoke to which the stud bolts are welded is assembled into a magnetron body or the like in a subsequent assembling process, and is assembled into a magnetron with mounting screws.

According to the above construction, the ferromagnetic yoke and the stud bolt are joined by projection welding. According to this method, the mounting work of the stud bolt is simplified as compared with the conventional technique of press-fitting using a press machine. Further, the influence of variations in the dimensions and shapes of the components is reduced, and a substantially constant bonding strength can be obtained.
In addition, the vibration applied to the oscillating unit body of the magnetron is also reduced.

As a result, the number of steps is simplified, and a magnetron with a mounting screw of stable quality is realized.

In the above embodiment, projection welding is used for welding the ferromagnetic yoke and the stud bolt. Projection welding does not have the problem of oxidation, such as arc welding or gas welding, and suppresses deterioration of magnetron quality. In addition, projection welding has a shorter time required for welding than arc welding or gas welding, such as that a large number of locations can be welded by one welding, and is effective for application to a continuous production line. Also,
The cost can be reduced as compared with the case where laser welding is used.

[0027]

According to the present invention, it is possible to realize a magnetron device which prevents stud bolts from coming off and does not impair the oscillation function.

[Brief description of the drawings]

FIG. 1 is a schematic structural diagram for explaining an embodiment of the present invention.

FIG. 2 is a schematic structural view for explaining a ferromagnetic yoke and stud bolts used in the present invention.

FIG. 3 is a schematic structural view for explaining a method of attaching a ferromagnetic yoke and stud bolts according to the present invention.

FIG. 4 is a schematic structural diagram for explaining a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Magnetron main body 12 ... Anode cylinder 13 ... Cathode 14 ... Pole piece 15 ... Anode vane 16 ... Strap ring 17 ... Output antenna 18, 19 ... Permanent magnet 20 ... Radiator 21 ... First ferromagnetic yoke 21a ... Ferromagnetic Flange part of body yoke 21b ... hole of ferromagnetic body yoke 21c ... mounting hole 21 of ferromagnetic body yoke 22 ... second ferromagnetic body yoke 23 ... stud bolt 23a ... thread part of stud bolt 23b ... Stud bolt flange 23 23c Stud bolt projection 31 Upper electrode 32 Lower electrode

Claims (4)

[Claims] 1. A magnet for forming a magnetic field in an oscillating portion of a magnetron body, a ferromagnetic yoke for forming a magnetic path of a magnetic flux generated by the magnet, and a stud bolt attached to the ferromagnetic yoke. The magnetron device provided, wherein the ferromagnetic yoke and the stud bolt are joined by welding. 2. The magnetron device according to claim 1, wherein the stud bolt is provided with a flange portion and a screw portion, and a projection is formed on a surface of the flange portion on the side of the screw portion. 3. The stud bolt according to claim 2, wherein the projection formed on the flange portion is welded to a ferromagnetic yoke.
The magnetron device as described. 4. A step of providing a mounting hole in a part of a ferromagnetic yoke disposed outside a magnetron body, providing a flange portion and a screw portion, and providing a flange portion and a screw portion on the screw portion side of the flange portion. The threaded portion of the stud bolt having a projection formed on its surface is inserted into a mounting hole of the ferromagnetic yoke so that the projection formed on the flange portion comes into contact with the surface of the ferromagnetic yoke. And connecting the flange portion of the stud bolt to one electrode, connecting the ferromagnetic yoke to the other electrode, and applying a voltage between the one electrode and the other electrode. Welding the ferromagnetic yoke and the stud bolt to the magnetron device.