JPH0574338A - Manufacture of magnetron - Google Patents

Abstract

PURPOSE:To enable one kind of anodes in the condition that banes are projected at the inside periphery of an anode cylinder to be used in common for plural kinds of magnetrons by connecting one end each of antenna leads to the optional positions at the end faces in axial direction of the vanes by welding method. CONSTITUTION:Vanes 2a are projected radially at time inside periphery of the anode cylinder 1 of a magnetron and an antenna lead 6a is connected to the vane 2a. The projection is crushed into a weld zone 20 by pressing the projection against the vane 2a after providing a projection at the end of lead 6a in place of a conventional groove, and bringing it close to the end face of the vane 2a, and applying voltage between both hands to generate arc discharge and raise the temperature. Accordingly, it can cope with the manufacture of plural kinds of magnetrons merely by preparing one kinds of anodes. Moreover, there is no hindrance of heat conduction by the many grooves for attachment of antenna leads aiming at correspondence to multikind, and relatively expensive silver solder also becomes needless.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetron, which enables a plurality of kinds of magnetrons having different characteristics to be manufactured by using anodes having the same shape and size.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view taken along a plane including a tube axis and an antenna lead of a magnetron generally used in a microwave oven or the like. In the figure, 1 is an anode cylinder, 2 is a vane, 3 is an inner pressure equalizing ring, 4 is an outer pressure equalizing ring, 5 is a pressure equalizing ring housing groove, 6 is an antenna lead, and 7 is a metal exhaust pipe for exhausting the inside of the pipe and its An antenna lead end part which is vacuum-tightly cut off together with an antenna lead passing therethrough, 8 is an output part which protects the antenna lead end part and radiates microwave power from the antenna lead end part to the outside, 9 is a cathode In order to form a static magnetic field in the axial direction of the tube in the cylindrical working space interposed between the end of the vane and the end of the vane, and contact with the upper and lower ends of the anode cylinder at the peripheral edge of the flat annular surface portion near the upper and lower ends of the operating space from the annular surface portion. A magnetic pole having a conical surface portion reaching 10 is a permanent magnet which is arranged in the vicinity of the annular surface portion of the magnetic pole and serves as a magnetomotive force source for forming the static magnetic field. The permanent magnets arranged Yoke for magnetically coupling between the two, 12 is a cathode surrounded by the end of the vane through the working space, 13 is an air-cooling that is fitted to the outer surface of the anode cylinder and dissipates heat generated in the anode during operation to the outside The cooling fin 14 is a mounting groove for connecting the end of the antenna lead to one of the vanes, and when the vane is extruded integrally with the anode cylinder, the vane for actually connecting the antenna lead is Only one piece is formed on all vanes because it is used to cut grooves during lathe work. In some cases, a vane formed separately from the anode cylinder may be fixed to the inner circumference of the anode cylinder for manufacturing. In such a case, only the vane to which the antenna lead is to be connected in advance has the antenna lead mounting groove. Can also be formed.

A portion surrounded by the anode cylinder 1 and the vane 2 respectively forms a cavity resonator. On the other hand, the outer anode cylinder 1 is normally grounded for safety reasons, and a large negative potential is applied to the inner cathode. The electrons accelerated by being attracted from the cathode to the anode are subjected to the Lorentz force orthogonal to the course due to the action of the static magnetic field acting at right angles to the movement direction, forming an electron cloud and orbiting in the action space. To do. In the cavity resonator group formed on the inner circumference of the anode cylinder as described above, the orbiting electron cloud induces high-frequency oscillation with a phase difference of exactly π between adjacent resonators during normal operation. The pressure equalizing ring electrically connects the portions where the voltages of the cavity resonators oscillating in the same phase should be in the same phase, respectively, to ensure the so-called π-mode oscillation. If the respective cavity resonators are completely in the same state, the connection points between the pressure equalizing ring and each vane are always at the same potential, and no current flows in the pressure equalizing ring.
However, as described above, the antenna lead 6 is connected to only one vane 2 in this example, and the resonators are not completely in the same state due to an unavoidable error at the time of manufacture. Current sometimes flows through the pressure equalizing ring.

Between the vane ends of the cavity resonator or between the pressure equalizing rings, capacitance acts, and the conductor portion such as the vane mainly acts as inductance. If the antenna lead is connected to a portion near the end of the vane on the tube axis side, a large voltage is generated there. Therefore, if the load side is well matched to the magnetron side, a large microwave power output can be obtained. If the antenna lead is connected to the vane near the inner circumference of the anode cylinder, the microwave power output from the magnetron will be small, but the matching state with the load side will be insensitive. In mass production of magnetron,
Actually, multiple types of magnetrons with different outputs are manufactured by using the same combination of anode cylinder and vane as far as the shape and dimensions are concerned, only changing the connection position of the antenna lead and the vane. There are also cases.

[0005]

FIG. 4 is a tube shaft showing a state in which the vanes 2 are radially projected from the inner circumference of the anode cylinder 1 of the conventional magnetron, and the antenna leads 6 are connected to the vanes 2. It is a cross-sectional view of a plane including an antenna lead, which is drawn as simple as possible. Further, FIG. 5 is a perspective view showing a structure of a portion where the antenna lead 6 is connected to the vane 2. As shown, the vane 2 has the above-described mounting groove 14 and the end portion of the antenna lead 6 as well. A groove 61 is provided so as to engage with the mounting groove 14 of the vane. If the connection between the bain and the antenna lead goes wrong,
As it affects the output characteristics of the magnetron as described above,
This connection must be accurately positioned. On the other hand, in the past, the work of fixing and protruding the vane to the inner circumference of the anode cylinder was often done by hard brazing using silver solder or the like, and therefore the work of fixing and connecting the antenna lead to the vane was also performed. It was done by hard brazing. In order to mass-produce such hard brazing work, an appropriate amount of silver brazing material is arranged in the engaging part of the related parts, or at least the end of the antenna lead is preliminarily plated with a thick silver brazing material. Then, it is passed through a brazing furnace (for example, a tunnel furnace whose hearth is a conveyor). During that time, the state of engagement between the parts cannot change, so
As shown in FIG. 5, grooves were provided in both engaging parts to braze in a kind of fitted state. In mass production by brazing, it is important to keep the engaged state of related parts constant, so many proposals have been made for the structure of this part, and basically, most of the above-mentioned grooves are engaged with each other. Although it is to match, extraordinary pain is paid to ensure the engaged state reliably and to facilitate mass production,
For example, in Japanese Patent Application Laid-Open No. 59-186235, an insertion portion to be inserted and fitted into the groove of the vane is provided above the groove of the antenna, and step portions with which side surfaces of the vane abut are provided on both sides of the insertion portion. Is disclosed.

However, if the groove for attachment is to be cut in advance at the place where the antenna lead of the vane is to be connected as described above, the vane having the groove cut at the specific place on the end face of the vane for the specific product is Even if the same anode cylinder can be used for a product other than the specified product, it cannot be used. As a result, it becomes difficult to accommodate parts, resulting in an increase in in-process inventory.
If, in order to avoid such a problem, the grooves for attaching the antenna leads are provided at all the parts of the vane corresponding to the plural types of magnetrons, heat conduction is deteriorated due to the large number of grooves. The price of silver brazing for silver brazing occupies a considerable part in terms of cost structure in the case of magnetron used for household microwave ovens.

The present invention solves the above-mentioned conventional problems, and provides a method of manufacturing a magnetron in which one type of anode component having a vane protruding from the inner circumference of the anode cylinder can be commonly used by a plurality of types of magnetrons. The purpose is to provide.

[0008]

In order to achieve the above object, in the present invention, a plurality of vanes are radially projected on the inner circumference of an anode cylinder made of a good conductor to form a cavity resonator group, In a method of manufacturing a magnetron, wherein one end of an antenna lead made of a good conductor for extracting wave power is connected to at least one of the vanes, and the other end of the antenna lead is connected to a microwave power output section. It is unnecessary to form a groove on the end face of the vane in the axial direction of the pipe by welding so as to prepare a groove for connection with the antenna lead in advance.

[0009]

In order to increase the Q of the cavity resonator, it is necessary to reduce the electric resistance of the material used as much as possible. Therefore, oxygen-free copper is generally used as the material of the anode cylinder and the vane of the magnetron, and especially The use of oxygen-free copper is a necessary condition when the anode cylinder and the vane are integrally formed by extrusion. Copper has a relatively low melting point, and once it begins to melt, the fluidity increases rapidly, making it by no means an easy material to weld. However, according to an experimental study by the present inventor, the precise control of the distance between the members to be welded, the pressure during welding, the applied voltage, etc., and the material of the antenna lead or some kind of metal on the surface of It was found that welding can be performed by means such as thick coating. It should be noted that the antenna lead can be shared by a plurality of types.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a tube shaft and an antenna lead showing a state in which a vane 2a is radially projected on the inner circumference of an anode cylinder 1 of a magnetron according to an embodiment of the present invention, and an antenna lead 6a is connected to the vane 2a. It is a cross-sectional view of a plane including and, and it is drawn as simple as possible. In the figure, 20 is a welded portion between the antenna lead 6a and the vane 2a.

FIG. 2 is a perspective view showing the structure of the portion where the antenna lead 6a is connected to the vane 2a. As shown in the drawing, the vane 2a is not provided with a conventional mounting groove, and this example is used. In, the thin streak 21 is provided as a mark (so-called marker) indicating the reference position for positioning. You may engrave or imprint instead of the streak. Further, in the present invention, a dedicated welding machine is used for mass production, one electrode of the welding machine is connected to a predetermined position of the vane or the anode cylinder, and the other electrode has an antenna lead in a predetermined position and posture. Since the antenna lead side electrode is not only able to precisely control and hold the distance between the antenna lead and the vane, it is also possible to perform accurate positioning control in the direction along the vane. Instead of providing a mark as a reference for determining, the inner surface of the anode cylinder or the tip of the vane may be used as the reference position for welding positioning, and the welding machine itself may perform the positioning.

In this embodiment, a projection 6b is provided at the end of the antenna lead 6a instead of the conventional groove. When the projection 6b is brought close to the end face of the vane 2a and a voltage is applied between the two, an arc discharge occurs between the two, and the temperature of both discharge parts rises. Then, when the antenna lead 6a is pressed against the vane 2a, the projection 6b of the copper antenna lead 6a is crushed and joined to the vane 2a to form the welded portion 20 as shown in FIG.

In the past, since there were many brazing points using silver brazing, in the mass production, an engaging member to be brazed was flowed in a belt furnace in a tunnel furnace.
If the antenna lead and the vane are welded according to the present invention, all the connection points are welded (for example, laser welding is also used), and the use of the above-described tunnel furnace for silver brazing is abolished. You can also do it. As a transitional measure, the antenna lead may be temporarily welded to the vane and then finally fixed by using a silver brazing material.

[0014]

As described above, according to the present invention, it is possible to cope with the manufacture of plural kinds of magnetrons by preparing only one kind of anode (an anode cylinder and a vane are fixed or integrally formed). As a result, the inventory quantity of work-in-progress can be reduced, there is no fear that the heat conduction of the vane will be hindered by the large number of grooves for mounting the antenna leads, which is aimed at supporting a wide variety of products, and it is relatively expensive as a raw material. The effect that unnecessary silver wax is unnecessary can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which vanes are radially provided on an inner circumference of an anode cylinder of a magnetron according to an embodiment of the present invention, and antenna leads are connected to the vanes by a welding method.

FIG. 2 is a perspective view showing a structure of a portion where the antenna lead of the embodiment is connected to the vane.

FIG. 3 is a cross-sectional view of a magnetron conventionally used in a microwave oven or the like.

FIG. 4 is a cross-sectional view showing a state in which an antenna lead is connected to a vane radially protruding from the inner circumference of an anode cylinder of a conventional magnetron.

FIG. 5 is a perspective view showing a structure in which grooves are provided in both the vane and the antenna lead in a conventional magnetron to perform brazing in a kind of fitting state.

[Explanation of symbols]

1 ... Anode cylinder, 2, 2a ... Vane, 3 ... Inner pressure equalizing ring, 4 ... Outer pressure equalizing ring, 5 ... Pressure equalizing ring housing groove, 6, 6a
... antenna lead, 6b ... projection part, 7 ... antenna lead end part where the metal exhaust pipe and the antenna lead passing through are cut off together, 8 ... output that protects the antenna lead end part and radiates microwave power to the outside , 9 ... Magnetic poles for forming a static magnetic field in the tube axis direction in the working space, 10 ... Permanent magnets, 11 ... Yoke for magnetically coupling between the permanent magnets, 12
... cathode, 13 ... cooling fins, 14 ... mounting groove for connecting the end of the antenna lead to the vane, 20
… Welding between antenna lead and vane, 21… mark.

Claims (1)

[Claims] 1. A plurality of vanes are radially projected on the inner circumference of an anode cylinder made of a good conductor to form a cavity resonator group, and one end of an antenna lead made of a good conductor for extracting microwave power is connected to the vane. In the method of manufacturing a magnetron, which is connected to at least one and the other end of the antenna lead is connected to a microwave power output unit, one end of the antenna lead is connected to an arbitrary position on the end face of the vane in the tube axial direction by a welding method, A method of manufacturing a magnetron, characterized in that it is not necessary to previously form a groove on the end face of the vane in the tube axial direction in preparation for connection with an antenna lead.