JP2003297256A - Magnetron and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a magnetron in which a long-life can be attained by suppressing fatigue break-down of a brazing section of a strap ring and an anode board, and also making miniaturization and high output can be realized. <P>SOLUTION: In the anode 33 of the magnetron 31, each anode board 55a, 55b, 55c, and so on of even numbers, which are arranged projecting to the inner circumference of an anode part 51, are constituted of a tip end section 75 located on a cathode board side, and a main body section 76 except this tip end section 75. The tip end section 75 is formed with another metallic material which excels in a heat-resisting property rather than the metallic material that forms the device body part 76. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron used in a microwave oven, a microwave heating device and the like, and more specifically, it suppresses fatigue damage of a brazing part between an anode strap ring and an anode plate. The present invention relates to an improvement for achieving a long life and an improvement in productivity.

[0002]

2. Description of the Related Art FIGS. 10 and 11 show an anode of a conventional magnetron used in a microwave oven, a microwave heating device and the like. As shown in the figure, the anode 1 includes a cylindrical anode body 3 in which a cathode (not shown) is inserted on a central axis, magnets (not shown) provided at upper and lower ends of the anode body 3, and the anode. An even number of anode plates (also called vanes) 7a, 7b. 7c, ...
And even number of anode plates 7a, 7b. A configuration including two strap rings 11 and 12 in which every other one of the tip ends of 7c, ... Is connected to the same potential, and an antenna 15 connected to one of the anode plates for leading high frequency energy to the outside. Is.

Ring insertion holes 14 and 15 for inserting the two strap rings 11 and 12 are formed at the tips of the anode plates 7a, 7b, 7c ,. Each of the strap rings 11 and 12 has a C-ring shape in which a rod-shaped member having a predetermined length is curved and formed into an annular shape having a predetermined diameter.

One of the strap rings 11 is inserted into the ring insertion hole 14 of each of the anode plates 7a, 7b, 7c, ... Then, the ring insertion holes are inserted into the even-numbered anode plates 7b, 7d, 7f ,. It is electrically and mechanically joined to the opening edge of 14 by brazing with a high melting point brazing material (for example, silver brazing material). Therefore, the ring insertion holes 14 formed in the even-numbered anode plates 7b, 7d, 7f, ...
In order to braze the inserted strap ring 11, the inner diameter is set so that the gap between the outer peripheral surface of the inserted strap ring 11 and the inner peripheral surface of the hole becomes small. Further, as shown in FIG. 11, the ring insertion holes 14 formed in the odd-numbered anode plates 7a, 7c, 7e, ...
Make sure that the strap ring 11 to be inserted is not in contact
The inner diameter is set larger than the ring insertion holes 14 formed in the even-numbered anode plates 7b, 7d, 7f, ....

The other strap ring 12 is inserted into the ring insertion hole 15 of each anode plate 7a, 7b, 7c, ... And then, the ring insertion hole is inserted into the odd-numbered anode plates 7a, 7c, 7e ,. The openings 15 are electrically and mechanically joined by brazing with a high melting point brazing material. Therefore, the odd-numbered anode plates 7a, 7c, 7
In order to braze the strap ring 12 to be inserted, the ring insertion hole 15 formed in e, ... has an inner diameter such that the gap between the outer peripheral surface of the strap ring 12 to be inserted and the inner peripheral surface of the hole becomes small. It is set. In addition, as shown in FIG. 11, even-numbered anode plates 7b, 7d, 7f,
The inner diameter of the ring insertion hole 15 formed in ... Is set to be larger than that of the ring insertion hole 15 formed in the odd-numbered anode plates 7a, 7c, 7e, so that the inserted strap ring 12 is not in contact. ing.

That is, the odd-numbered anode plates 7a, 7c,
, 7e, ... Are mutually connected to the same potential via strap rings 11 connected by brazing. On the other hand, the even-numbered anode plates 7b, 7d, 7f, ...
The two are mutually connected at the same potential via the strap rings 12 connected by brazing.

As shown in FIG. 12A, the opposite ends of the strap ring 11 and the strap ring 12 are connected by brazing with a high melting point brazing material to complete a continuous ring. In FIG. 12A, reference numeral 1
A portion indicated by 8 is a brazing portion made of a high melting point brazing material. The strap rings 11 and 12 and the anode plates 7a, 7b, 7c, ...
As shown in FIG. 2 (a), it is performed by brazing the entire circumference of the rod-shaped members forming the strap rings 11 and 12 with a high melting point brazing material. In FIG. 12A, a portion indicated by reference numeral 19 is a brazing portion made of a high melting point brazing material.

The brazing portion 18 at the end of each strap ring 11, 12 is usually inside the ring insertion hole 14, 15 for brazing the strap ring 11, 12 as shown in FIG. 12 (a). The joint strength is improved by brazing.

[0009]

By the way, the strap rings 11 and 12 and the anode plates 7a, 7b and 7 described above are to be solved.
Since c, ... Are also the conductors that make up the LC circuit,
It is preferable to use a metal having an excellent electric conductivity, and oxygen-free copper having a purity of 99.96% or more has been used so far. However, oxygen-free copper has not only high electrical conductivity but also good thermal conductivity, low heat resistance, and high thermal expansion coefficient.

Therefore, in the conventional magnetron in which the strap rings 11, 12 and the anode plates 7a, 7b, 7c, ... Are made of oxygen-free copper, the anode plates 7a, 7b, 7c ,. Of the anode plates 7a, 7b, 7c, ... Due to the large thermal expansion coefficient, the anode plates 7a, 7b, 7c ,. And
When the anode plates 7a, 7b, 7c, ... Are greatly thermally expanded, the strap rings 11, 12 bonded to the anode plates 7a, 7b, 7c ,.
A large load such as a bending load or a shearing load is applied to the brazing parts 19 of the anode plates 1 and 12 and the anode plates 7a, 7b, 7c, .... Then, the repeated thermal expansion and contraction of the anode plates 7a, 7b, 7c, ... Induces a fracture (crack) 21 in the brazing part 19 due to fatigue failure, as shown in FIG. There was a problem of lowering.

The breakage of the brazing parts 18 and 19 causes a decrease in the capacitance of the LC circuit composed of the anode body 3 and the anode plates 7a, 7b, 7c, ... And the strap rings 11 and 12, resulting in Specifically, malfunction of the magnetron due to abnormal oscillation frequency is caused.

Further, in recent years, there is a strong market demand for higher output of the magnetron. Increasing the output of the magnetron can be achieved by enhancing the direct current electric field applied between the cathode and the anode forming the magnetron, or enhancing the magnetic field applied in the direction orthogonal to the direct current electric field.

However, the enhancement of the DC electric field is accompanied by an increase in the heat radiation amount of the cathode, and if the anode plates 7a, 7b, 7c, ... There is a possibility that inconvenience may occur such that the tip portion of the plate is overheated and softened. Then, in order to prevent the excessive temperature rise of the anode plate, if the cooling fins are increased in size in order to improve the cooling performance by the cooling fins attached to the outer periphery of the anode, there arises a problem that the magnetron itself is increased in size. On the other hand, the magnetic field can be increased by replacing the magnets attached to the magnetic poles at both ends of the anode with larger magnets.
In the end, there was a problem that the magnetron itself became large due to the equipment of the large magnet.

Further, since the strap ring must be sequentially inserted into the ring insertion hole of each anode plate,
There was a problem that the assemblability was poor and the productivity of the magnetron could not be improved.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to prevent fatigue failure of a brazed portion between a strap ring of an anode and an anode plate to prolong the life thereof. Moreover, it is to provide a magnetron capable of realizing miniaturization and high output and improving productivity.

[0016]

In order to achieve the above object, the magnetron according to the present invention is, as described in claim 1, provided at least on the inner peripheral surface of the anode body radially toward the central axis. Even number of anode plates (Bain)
In a magnetron equipped with a strap ring that connects every other one of the even end portions of the anode plates to the same potential, the anode plate is formed by removing the leading end portion located on the cathode side and the leading end portion. A main body portion, and the tip portion is formed of another metal material having higher heat resistance than the main body portion.

During operation of the magnetron, the anode plate mounted on the anode receives heat from the cathode and heats up. The mechanism for raising the temperature of the anode plate is that the heat dissipation of the cathode is received by the tip of the anode plate located on the cathode side, and the temperature of the main body is raised by heat transfer according to the heat conduction characteristics of the tip. Become.

However, the tip portion is formed of another metal material having higher heat resistance than the main body portion, and suppresses heat conduction to the main body portion. Therefore, the tip portion suppresses the temperature rise of the main body,
The thermal expansion and contraction of the anode plate can be suppressed, and the thermal expansion and contraction of the anode plate reduces the load acting on the brazing part between the anode plate and the strap ring.

The magnetron according to claim 2 is
To achieve the above object, in the magnetron according to claim 1, further, the main body of the anode plate is made of oxygen-free copper, and the tip of the anode plate is made of a high heat-resistant metal containing a nickel component. It is characterized by having done.

As a high heat resistant metal containing a nickel component,
For example, a copper-nickel alloy (Cypro) synthesized by mixing nickel and copper in a ratio of 30:70 has a softening start temperature of 550.
~ 600 ° C, thermal conductivity 29 W / (m · K), thermal expansion coefficient 16.2 (× 10 −6 / ° K), melting point 1170
C., electric conductivity is 4.6 (% IACS). In the case of oxygen-free copper, the softening start temperature is 200 to 220 ° C., the thermal conductivity is 391 W / (m · K), and the thermal expansion coefficient is 17.7.
(× 10 −6 / ° K), melting point is 1083 ° C., and electric conductivity is 101 (% IACS).

That is, the copper-nickel alloy has a lower electric conductivity than oxygen-free copper, but has a remarkably high heat resistance and a low heat conductivity, and therefore is suitable for preventing the temperature rise of the main body. .
Therefore, compared with the conventional case where the entire anode plate is made of oxygen-free copper, thermal expansion and contraction of the anode plate are suppressed, and fatigue of the brazing part caused by repeated thermal expansion and contraction of the anode plate Destruction can be suppressed and a long life can be realized. Moreover, since nickel is a magnetic substance,
The nickel component contained in the tip portion acts on the magnetic field strength by the magnets assembled above and below the anode so that the strength difference is reduced.

Further, the magnetron according to claim 3 is
In order to achieve the above object, in the magnetron according to claim 1 or 2, a ring insertion hole for inserting the strap ring is further provided so as to extend over the main body portion and the tip end portion of the anode plate. It is a feature.

The ring insertion hole is completed as an insertion hole by aligning the ring insertion grooves formed on the abutting surfaces of the main body portion and the tip portion, and the tip portion is joined to the main body portion. In the stage before the step, the strap ring can be easily assembled to the anode plate by abutting the body portion and the tip portion with the strap ring positioned in the ring insertion groove of the body portion.

In order to achieve the above-mentioned object, the method of manufacturing a magnetron according to the present invention has, as described in claim 4, at least the inner peripheral surface of the anode body, which is provided with an even number of sheets radially arranged toward the central axis. In a method of manufacturing a magnetron comprising an anode plate and a strap ring that connects every other one of the tip parts of the even number of anode plates to the same potential, the anode plate includes a tip part located on the cathode side, and It is composed of a main body portion excluding the tip portion, and the strap ring is positioned in the ring insertion groove of the main body portion of the ring insertion groove formed on the abutting surfaces of the main body portion and the tip portion. It is characterized in that the tip portion is joined and manufactured.

Since the strap ring is inserted into the anode plate by joining the tip end portion to the main body, the troublesome work of piercing the conventional strap ring into the hole of the anode plate can be omitted. Assembling of the strap ring is improved, and productivity of the magnetron can be improved.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a magnetron according to the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a vertical sectional view of a first embodiment of a magnetron according to the present invention. The magnetron 31 of the first embodiment is used, for example, in an industrial microwave heating device or the like, and is inserted into the anode 33 having the working space 32 inside and the central axis of the anode 33. An antenna tube 3 which is assembled on the cathode 35 and the upper portion of the anode 33 to serve as a high frequency energy emission section.
7, a main body case 39 accommodating the anode 33, and a cooling fin 41 stretched between the anode 33 and the main body case 39 to let the heat generation of the anode 33 escape to the outside.

The anode 33 has a cylindrical anode body 51 in which the cathode 35 is inserted on the central axis, and magnetic poles 52, 5 provided at both upper and lower ends of the anode body 51.
3, an even number (10 in this example) of anode plates 55a, 55b, 55c, ... Radially mounted on the inner peripheral surface of the anode body 51 toward the central axis, and the anode plates 55a, 55b, 55c, ... Two strap rings 57 and 58, which are connected to the same electric potential at every other tip, and an antenna 61 connected to one anode plate 55a for extracting high frequency energy to the outside are provided. There is. Further, magnets 62 and 63 for guiding magnetic flux to the working space 32 are provided on the outer surfaces of the upper and lower magnetic poles 52 and 53.

Anode plates 55a, 55 of this embodiment
As shown in FIGS. 4 and 5, b, 55c, ... Consist of a tip portion 75 located on the cathode 35 side and a body portion 76 excluding the tip portion 75. The tip portion 75 is a body portion. 76
It is formed of another metal material having higher heat resistance than the metal material forming the. Specifically, the anode plates 55a, 55
The main body portion 76 of b, 55c, ... Is made of oxygen-free copper having a purity of 99.96%, and the tip portion 75 is made of nickel and copper at 30:70.
It is made of high heat-resistant copper-nickel alloy synthesized in the ratio. The tip portion 75 is joined and integrated with the tip surface of the main body portion 76 with a high melting point brazing material such as silver brazing.

Each of the anode plates 55a, 55b, 55c, ...
Ring insertion holes 65 and 66 through which the two strap rings 57 and 58 are inserted are formed at the tip end side of the main body portion 76. Each of the strap rings 57 and 58 is a linear rod-shaped member having a predetermined length and is provided on all of the anode plates 55a and 55a.
After being inserted into the ring insertion holes 65, 66 of b, 55c, ..., It has a C-ring shape which is curved and formed into an annular shape having a predetermined diameter. Small gaps S1 and S2 are left between the opposite ends of the strap rings 57 and 58, as shown in FIG.

The one strap ring 57 has ring insertion holes 6 for all the anode plates 55a, 55b, 55c, ....
5 and then curved and formed into a C-ring shape, and then with respect to the odd-numbered anode plates 55a, 55c, 55e, ...
The ring insertion hole 65 is electrically and mechanically joined to the opening edge by brazing with a high melting point brazing material (for example, silver brazing material). Therefore, the odd-numbered anode plates 55
Ring insertion holes 65 formed in a, 55c, 55e, ...
In order to braze the inserted strap ring 57, the inner diameter is set so that the gap between the outer peripheral surface of the inserted strap ring 57 and the inner peripheral surface of the hole becomes small. Further, as shown in FIGS. 2 and 3, the ring insertion holes 65 formed in the even-numbered anode plates 55b, 55d, 55f, ... Have an odd inner diameter so that the strap ring 57 to be inserted is not in contact. Th anode plate 55a, 5
It is set to be larger than the ring insertion hole 65 formed in 5c, 55e, ....

The other strap ring 58 has ring insertion holes 6 for all the anode plates 55a, 55b, 55c, ....
After being inserted into 6 and curved-formed into a C-ring shape, for even-numbered anode plates 55b, 55d, 55f, ...
The ring insertion hole 66 and the opening edge are electrically and mechanically joined by brazing with a high melting point brazing material. Therefore, the even-numbered anode plates 55b, 55d, 55f,
In order to braze the strap ring 58 to be inserted, an inner diameter of the ring insertion hole 66 to be formed is set so that the gap between the outer peripheral surface of the strap ring 58 to be inserted and the inner peripheral surface of the hole becomes small. ing. 2 and 3
, The odd-numbered anode plates 55a, 55c,
The inner diameter of the ring insertion hole 66 formed in 55e, ... Is larger than that of the ring insertion hole 66 formed in the even-numbered anode plates 55b, 55d, 55f, so that the inserted strap ring 58 is not in contact. It is set.

That is, the odd-numbered anode plates 55a, 55
, c, 55e, ... Are mutually connected to the same potential via a strap ring 57 connected by brazing. On the other hand, the even-numbered anode plates 55b, 55d, 55
f, ... Are mutually connected to the same potential via strap rings 58 connected by brazing.

As shown in FIG. 3, both ends of the strap rings 57 and 58 are opposed to each other in the ring insertion holes 65 and 66 of the anode plate to be brazed, and the opposed end faces are made to have a high melting point solder. The material is connected by brazing to form a continuous ring, and at the same time, the bonding strength with the anode plate is improved.

The magnetron 31 constructed as described above
In the above, in operation, the anode plates 55a, 55b, 55c, ... Equipped on the anode 33 are heated by the heat radiation of the cathode 35. The anode plates 55a, 55
As described above, the mechanism for increasing the temperature of b, 55c, ... Depends on the heat conduction characteristic of the tip portion 75 of the anode plate located on the cathode 35 side, receiving the heat radiation of the cathode 35. The heat transfer causes the temperature of the main body portion 76 to rise.

The copper-nickel alloy (Cypro) forming the tip portion 75 in this embodiment has a softening start temperature of 550 to 600 ° C., a thermal conductivity of 29 W / (m · K), and a thermal expansion. Coefficient 16.2 (× 10-6 / ° K), melting point 11
It has an electric conductivity of 4.6 (% IACS) at 70 ° C.
On the other hand, in the case of oxygen-free copper forming the main body portion 76, the softening start temperature is 200 to 220 ° C., and the thermal conductivity is 3
91 W / (m · K), thermal expansion coefficient 17.7 (× 10-
6 / ° K), melting point 1083 ° C, electric conductivity 101
(% IACS).

That is, the copper-nickel alloy used for the tip portion 75 has a lower electric conductivity than oxygen-free copper, but has a markedly high heat resistance and a low heat conductivity, and therefore, the main body portion. The heat conduction to 76 is suppressed, and the temperature rise of the main body 76 is suppressed.
Therefore, as described above, by forming the tip portion 75 of each anode plate with a copper-nickel alloy and forming the main body portion 76 with oxygen-free copper, the entire anode plate is formed with oxygen-free copper. Compared with the case, the anode plates 55a, 55b,
It is possible to suppress the temperature rise of 55c, ... And suppress the thermal expansion and the thermal contraction. That is, the anode plates 55a, 55b, 55
Anode plates 55a, 5 due to thermal expansion and contraction of c, ...
It is possible to reduce the load acting on the brazed portions of the strap rings 57, 58 with the 5b, 55c, .... Therefore, fatigue failure of the brazed portion due to repeated thermal expansion and thermal contraction of the anode plates 55a, 55b, 55c, ... Can be suppressed and a long life can be realized.

Moreover, since nickel is a magnetic material, the nickel component contained in the tip portion 75 serves to reduce the magnetic field strength difference by converging the magnetic flux generated by the magnets assembled to the upper and lower magnetic poles of the anode. Therefore, it is possible to increase the magnetic field and increase the output without increasing the size of the magnet, and it is possible to reduce the size and increase the output of the magnetron.

According to experiments conducted by the present inventors, when the entire anode plate is made of oxygen-free copper, the magnetic field distribution at the tip of the anode plate is the distribution shown by the curve F1 in FIG. When the tip of the anode plate is formed of the above-mentioned copper / nickel alloy as in the embodiment, the magnetic field distribution at the tip of the anode plate becomes the distribution shown by the curve F2 in FIG. It was confirmed that the magnetic field strength was improved by the above characteristics.

On the other hand, the high heat resistant metal has a characteristic that the electric conductivity is lowered, but the anode plate 55
a, 55b, 55c, ... Strap rings 57, 58 for electrically and mechanically connecting each other are brazed to a main body portion 76 formed of a metal having high electric conductivity, so that the anode plates 55a, 55b, 55c. , And the strap rings 57, 58 can maintain good electrical connection characteristics.

In the magnetron according to the present invention, the mounting positions of the ring insertion holes 65 and 66 in each anode plate, the shape of the tip 75 formed of a high heat resistant metal, and the cross-sectional shape of the strap rings 57 and 58. The present invention is not limited to the above-described embodiment, and for example, FIG.
It is possible to make appropriate improvements as in the embodiments shown in FIGS. In the embodiment shown in FIG. 7, a ring through which the strap rings 57 and 58 are inserted so as to straddle the body portion 76 and the tip portion 75 that form each anode plate 81 protrudingly provided on the inner periphery of the anode body 51. Insertion holes 65, 6
6 is provided. The body 76 is made of oxygen-free copper, and the tip 75
Similar to the first embodiment, it is formed of copper / nickel alloy which is a high heat resistant metal.

In the magnetron thus constructed, the ring insertion holes 65 and 66 are formed by aligning the ring insertion grooves 65a, 65b, 66a and 66b formed on the abutting surfaces of the main body portion 76 and the distal end portion 75, respectively. so,
It is a completed form as an insertion hole, and at the stage before joining the tip end portion 75 to the main body portion 76, even if the strap rings 57 and 58 are annular without a cut-off portion, the strap rings 57 and 58 can be attached to the main body portion. 76 ring insertion groove 6
It can be assembled to the main body part 76 by positioning the tip parts 75 on the 5 b and 66 b and joining them. The ring-shaped strap ring having no cut-off portion can be easily manufactured by punching a plate material or cutting a cylindrical body into a ring shape. Compared with the conventional manufacturing process of the strap ring, the manufacturing of the strap ring becomes easier.

Further, when the annular strap ring having no separation portion is adopted, the ring insertion hole is attached at the time of assembling with the anode plate as compared with the case where the conventional C-ring type strap ring is adopted. Since the troublesome work of penetrating the wire material into the wires 65 and 66 is not required, and the simple work of cutting into the groove is sufficient, the assemblability of the strap rings 57 and 58 is improved and the productivity can be improved.

The anode plate 83 shown in FIG. 8 is a further improvement of the anode plate 81 shown in FIG. This anode plate 83 is common to the second embodiment in that ring insertion holes 65 and 66 for inserting the strap rings 57 and 58 are provided so as to extend over the main body portion 76 and the tip end portion 75. . Further, the body portion 76 is made of oxygen-free copper, and the tip portion 7
The point that 5 is formed of a copper / nickel alloy which is a high heat resistant metal is also common to the second embodiment. However, the tip portion 75 of the present embodiment is set to have a vertical dimension shorter than that of the body portion 76, and the tip portion of the body portion 76 is vertically
Claws 76a and 76b that hold the tip 75 up and down are provided. As described above, by providing the main body 76 with the claws 76a and 76b that hold down the distal end 75, the joining surface by brazing becomes a three-dimensional arrangement, and the joining strength can be improved.

The anode plate 85 shown in FIG. 9 is a further improvement of the anode plate 83 shown in FIG. The anode plate 85 is similar to the second embodiment in that ring insertion holes 65 and 66 for inserting the strap rings 57 and 58 are provided so as to extend over the main body portion 76 and the tip end portion 75. . Further, the body portion 76 is made of oxygen-free copper, and the tip portion 7
The point that 5 is formed of a copper / nickel alloy which is a high heat resistant metal is also common to the second embodiment. However, the ring insertion holes 65 and 66 are rectangular through holes, and the strap rings 57 and 58 are annular rings having a rectangular cross section. The ring insertion holes 65 and 66 are formed by, for example, cutting a cylindrical body made of oxygen-free copper or the like into a ring, or punching a plate material made of oxygen-free copper into an annular shape to form a ring without separation. ing.

In the present invention, the composition ratio of the copper / nickel alloy used for the tip of the anode plate is not limited to that in the above embodiment. The component ratio can be appropriately adjusted according to the required heat resistance and the like. The high heat resistant metal used for the tip of the anode plate is not limited to the above-mentioned copper-nickel alloy. For example, if the main body of the anode plate is made of oxygen-free copper, and the heat-resistant metal is more excellent than oxygen-free copper, a copper-tin alloy in which tin is added to copper or a zirconium alloy in which zirconium is added to copper is used. Etc., these copper alloys are also high heat resistant metals that form the tip,
Useful enough. The heat resistance is improved in the order of oxygen-free copper → copper / tin alloy → zirconium alloy → copper / nickel alloy. The thermal conductivity, the thermal expansion coefficient, and the electrical conductivity gradually decrease in the order of oxygen-free copper → copper / tin alloy → zirconium alloy → copper / nickel alloy so as to be inversely proportional to heat resistance.

[0046]

As described above, according to the magnetron of the present invention as set forth in claim 1, since the main body of the anode plate is equipped with the tip having excellent heat resistance, The temperature rise due to heat dissipation is suppressed. Therefore, by repeated thermal expansion and thermal contraction of the anode plate, fatigue failure of the brazing part between the anode plate and the strap ring connecting the anode plates to each other can be suppressed, and a longer life can be realized.

Further, in the magnetron of the present invention described in claim 2, since the high heat resistant metal containing the nickel component is applied to the tip of the anode plate, the entire anode plate is made of oxygen-free copper. Compared with the conventional case, it is possible to suppress the thermal expansion and contraction of the anode plate and suppress the fatigue fracture of the brazing part due to the repeated thermal expansion and contraction of the anode plate to realize a longer life. it can. Moreover, since nickel is a magnetic substance, it acts to converge the magnetic flux by the magnets mounted above and below the anode, and it is possible to reduce the difference in magnetic field strength. Therefore, it is possible to increase the magnetic field and increase the output without increasing the size of the magnet, and it is possible to reduce the size and increase the output of the magnetron.

Furthermore, in the magnetron according to the present invention as defined in claim 3, since the ring insertion holes formed by aligning the ring insertion grooves formed on the abutting surfaces of the main body portion and the tip end portion are combined, the strap ring is separated. Even with a ring-shaped ring, it can be easily assembled to the main body,
Productivity can be improved.

Further, in the magnetron manufacturing method of the present invention as set forth in claim 4, since the strap ring is inserted through the anode plate by joining the main body portion and the tip end portion, the conventional strap ring is inserted. It is possible to omit the troublesome work of penetrating into the hole of the anode plate, improve the assembling property of the strap ring, and improve the productivity of the magnetron.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a first embodiment of a magnetron according to the present invention.

FIG. 2 is an enlarged perspective view of an anode of the magnetron shown in FIG.

3 is a cross-sectional view of the anode shown in FIG.

4 is a cross-sectional view taken along the line BB of FIG.

5 is an enlarged perspective view of the anode plate shown in FIG.

6 is a graph showing a magnetic field distribution at the tip of an anode plate (vane) in the magnetron shown in FIG.

FIG. 7 is an enlarged perspective view of a second embodiment of the anode plate in the magnetron according to the present invention.

FIG. 8 is an enlarged perspective view of a third embodiment of the anode plate in the magnetron according to the present invention.

FIG. 9 is an enlarged perspective view of a fourth embodiment of the anode plate in the magnetron according to the present invention.

FIG. 10 is a perspective view of an anode in a conventional magnetron.

11 is a vertical cross-sectional view of the anode shown in FIG.

12 is a cross-sectional view showing a form of a brazed portion between an anode plate and a strap ring in the anode shown in FIG. 10, (a) showing a proper joint state, (b) showing
[Fig. 4] is a transverse cross-sectional view of a state where a joint failure occurs.

[Explanation of symbols]

31 magnetron 32 working space 33 Anode 35 cathode 37 Antenna tube 39 Body case 41 cooling fins 51 Anode body 52, 53 magnetic poles 55a to 55j Anode plate (vane) 57,58 Strap ring (strap ring) 61 antenna 65, 66 Ring insertion hole 75 Tip 76 main body 76a, 76b Claw 81,83,85 Anode plate

Claims (4)

[Claims] 1. An even number of anode plates radially mounted toward the central axis on at least the inner peripheral surface of the anode body, and a strap ring for connecting every other tip of the even number of anode plates to the same potential. In the magnetron provided with, the anode plate is composed of a tip portion located on the cathode side and a body portion excluding the tip portion, and the tip portion is formed of another material having higher heat resistance than the body portion. A magnetron formed of a metal material. 2. The magnetron according to claim 1, wherein the main body of the anode plate is made of oxygen-free copper, and the tip of the anode plate is made of a high heat-resistant metal containing a nickel component. 3. The magnetron according to claim 1, wherein a ring insertion hole through which the strap ring is inserted is provided so as to extend over the main body and the tip of the anode plate. 4. An even number of anode plates radially provided toward the central axis on at least the inner peripheral surface of the anode body, and a strap ring for connecting every other end of the even number of anode plates to the same potential. In the method for manufacturing a magnetron, the anode plate is composed of a tip portion located on the cathode side and a body portion excluding the tip portion, and is formed on each abutting surface of the body portion and the tip portion. A method of manufacturing a magnetron, characterized in that the tip portion is joined to the main body portion in a state where the strap ring is positioned in the ring insertion groove of the main body portion of the ring insertion groove.