Information
-
Patent Grant
-
6729926
-
Patent Number
6,729,926
-
Date Filed
Wednesday, December 12, 200123 years ago
-
Date Issued
Tuesday, May 4, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Reichard; Dean
- Estrada; Angel R.
Agents
-
CPC
-
US Classifications
Field of Search
US
- 445 35
- 445 43
- 445 44
- 445 23
- 445 6
- 445 31
- 219 9123
- 219 93
- 219 12113
- 219 12114
- 228 175
- 228 164
-
International Classifications
-
Abstract
A magnetron has an anode cylinder, a plurality of vanes arranged radially within the anode cylinder, a magnetic piece disposed at an open end section of the anode cylinder, an anode vacuum container including a metal container disposed to cover an upper surface of the magnetic piece, a cathode disposed along a central axis of the vacuum container, and an antenna externally discharging microwaves. The magnetic piece and the metal container are placed, in that order, on a shelf formed inwardly on a thin end section projecting from the open end section of the anode cylinder. When tightly welding the thin end section, a predetermined number of projections, projecting inwardly from the thin end section of the anode cylinder, loosely secure an outer perimeter bend of the metal container. The metal container is then accurately tightly welded to the anode cylinder without the metal container shifting off-center.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a method for making magnetrons. More specifically, the present invention relates to a method for making magnetrons used in radars, microwave heating devices, e.g., microwave ovens, or the like.
Referring to
FIG. 4
, a conventional magnetron includes a plurality of vanes
52
formed within a cylindrical anode cylinder
51
. An anode vacuum container
55
includes a magnetic piece
53
and a metal container
54
disposed at the open end section of the anode cylinder
51
. A cathode
57
, disposed along the center axis of vacuum container
55
, includes a top hat
56
a
, an end hat
56
b
, and a filament
56
c
. An antenna
58
extracts a microwave, e.g., at 2450 MHZ, generated in the hollow space. In this magnetron, the thermoelectrons discharged by filament
56
c
spin inside the active space formed between vanes
52
and filament
56
c
, generating a microwave. This microwave, flowing along a vane
52
, is transferred to antenna
58
connected to vain
52
. The microwave is then discharged externally through antenna
58
.
Anode cylinder
51
and metal container
54
are bonded by tightly welding thin end section
59
of anode cylinder
51
. Referring to FIG.
5
(
a
), before the welding operation, thin end section
59
of anode cylinder
51
has a roughly even thickness between end
59
a
and base section
59
b
. Magnetic piece
53
and metal container
54
are placed on an inner shelf
60
of thin end section
59
.
Referring to FIGS.
4
and
5
(
b
), thin end section
59
of anode cylinder
51
is melted by welding to form a tight bond with outer perimeter bend
54
a
of metal container
54
.
If a slight gap forms between the inner wall surface of thin end section
59
of anode cylinder
51
and outer perimeter bend
54
a
of metal container
54
due to dimensional tolerances, misalignment of the parts, or the like, this gap will remain, even after the tight welding. This can lead to reduced sealing properties. Discarding such assemblies results in increases material costs, while performing repairs of these assemblies increases the number of steps involved in the procedure.
To prevent these gaps, the parts may be formed with shapes that provide alignment relative to each other. If alignment between the parts is not possible, dedicated tools or equipment may be used to secure the parts while welding. However, with each of these methods there is an increase in production costs.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for making a magnetron which overcomes the foregoing problems.
More specifically, it is an object of the present invention to provide a method for making magnetrons that easily improves the quality of the tight welding operation.
Briefly stated, the present invention provides a magnetron having an anode cylinder, a plurality of vanes arranged radially within the anode cylinder, a magnetic piece disposed at an open end section of the anode cylinder, an anode vacuum container including a metal container disposed to cover an upper surface of the magnetic piece, a cathode disposed along a central axis of the vacuum container, and an antenna externally discharging microwaves. The magnetic piece and the metal container are placed, in that order, on a shelf formed inwardly on a thin end section projecting from the open end section of the anode cylinder. When tightly welding the thin end section, a predetermined number of projections, projecting inwardly from the thin end section of the anode cylinder, loosely secure an outer perimeter bend of the metal container. The metal container is then accurately tightly weld to the anode cylinder without the metal container shifting off-center.
According to an embodiment of the present invention, a method for making magnetrons includes a magnetron having an anode cylinder, a plurality of vanes arranged radially within the anode cylinder, a magnetic piece disposed at an open end section of the anode cylinder, an anode vacuum container including a metal container disposed to cover an upper surface of the magnetic piece, a cathode disposed along a central axis of the vacuum container, and an antenna externally discharging microwaves. The magnetic piece and the metal container are placed, in that order, on a shelf formed inwardly on the thin end section projecting from the open end section of the anode cylinder. When tightly welding the thin end section, a predetermined number of projections projecting inwardly from the thin end section of the anode cylinder is used to loosely secure an outer perimeter bend of the metal container.
According to another embodiment of the present invention, a method for making magnetrons includes providing a magnetron having an anode cylinder, a plurality of vanes arranged radially within the anode cylinder, a magnetic piece disposed at an open end section of the anode cylinder, an anode vacuum container including a metal container disposed to cover an upper surface of the magnetic piece, a cathode disposed along a central axis of the vacuum container, and an antenna externally discharging microwaves. The magnetic piece and the metal container are placed, in that order, on a shelf formed inwardly on the thin end section projecting from the open end section of the anode cylinder. When tightly welding the thin end section, a ring-shaped projection, projecting inward from the thin end section of the anode cylinder, is used to loosely secure an outer perimeter bend of the metal container.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic cross-section drawing showing an embodiment of a magnetron according to the present invention.
FIG.
2
(
a
) is a schematic cross-section drawing showing a magnetron, according to the present invention, before elements are loosely secured.
FIG.
2
(
b
) is a schematic cross-section drawing showing a magnetron, according to the present invention, after elements are loosely secured.
FIG.
3
(
a
) shows a state of a magnetron, according to another embodiment of the present invention, before elements are loosely secured.
FIG.
3
(
b
) is shows a state of a magnetron, according to another embodiment of the present invention, after elements are loosely secured.
FIG. 4
is a schematic cross-section drawing showing an example of a conventional magnetron.
FIG.
5
(
a
) is a cross-section drawing of a conventional magnetron before tight welding is performed.
FIG.
5
(
b
) is a cross-section drawing of a conventional magnetron after tight welding is performed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the attached drawings, the following is a description of a method for making magnetrons according to the present invention.
Referring to
FIG. 1
, a magnetron according to an embodiment of the present invention includes an anode vacuum container
1
. A cathode
2
is disposed along the central axis of container
1
. An antenna
3
extracts microwaves generated in a hollow manner. The magnetron further includes an antenna ceramic
4
and cathode supports
5
a
,
5
b.
Anode vacuum container
1
includes a cylindrical anode cylinder
6
. A plurality of vanes
7
are arranged radially inside anode cylinder
6
. Magnetic pieces
8
,
9
are disposed at the upper and lower openings of anode cylinder
6
. Metal containers
10
,
11
cover the upper surfaces of magnetic pieces
8
,
9
.
Cathode
2
includes an end hat
12
secured to the end of cathode support
5
a
. A top hat
13
is secured to the end of cathode support
5
b
, which passes through end hat
12
. A filament
14
is wrapped around cathode support
5
b
between top hat
13
and end hat
12
.
Thin end section sections
6
a
, projecting from the ends of the upper and lower openings of anode cylinder
6
, are tightly welded to outer perimeter bends
10
a
,
11
a
of metal containers
10
,
11
. This forms a tight bond between metal containers
10
,
11
and anode cylinder
6
.
Next, the procedure for tightly welding outer perimeter bends
10
a
,
11
a
of thin end sections
6
a
will be described. To facilitate the discussion, the tight welding between thin end section
6
a
, projecting from the end of the upper opening of anode cylinder
6
, to outer perimeter bend
10
a
will be described.
Referring now to FIG.
2
(
a
), anode cylinder
6
is prepared as a cylindrical material with upper and lower openings from the ends of which are projected ring-shaped thin end sections
6
a
. Magnetic piece
8
and metal container
10
, having a bent outer perimeter, are placed, in that order, on a shelf
15
, formed on the inner side of thin end section
6
a
. Then, a projection tool
17
, on which a projection
16
having a predetermined shape, is placed at the outer side of anode cylinder
6
, opposite from thin end section
6
a.
Referring to FIG.
2
(
b
), projection tool
17
is impacted on thin end section
6
a
of anode cylinder
6
, forming an inward projection
18
on thin end section
6
a
. Inward projection
18
abuts outer perimeter bend
10
a
. It would be desirable to form at least three inward projections
18
along the perimeter so that metal container
10
stays centered. Next, thin end section
6
a
and outer bend
10
a
are tightly welded together. This tight welding is performed, for example, by using electron beam welding.
In this embodiment of the present invention, the tight welding operation is performed by loosely securing metal container
10
using projection
18
of thin end section
6
a
. This prevents metal container
10
from becoming off-center, allowing accurate welding of metal container
10
to thin end section
6
a
. As a result, a tight seal is formed and maintained between anode cylinder
6
and metal container
10
. Metal container
10
is supported by laterally projecting projection
18
. Metal container
10
is loosely secured in a reliable manner even if the end surface of projection
18
, formed on thin end section
6
a
, is positioned lower than the upper surface of metal container
10
. As a result, the metal container is loosely secured even without increasing the height of anode cylinder
6
. This reduces the material costs for anode cylinder
6
.
In this embodiment of the present invention, the projection is formed by first positioning the magnetic piece and the metal container and then using the projection tool placed outside the thin end section of the anode cylinder. However, the present invention is not restricted to this specific embodiment. It would also be possible, for example, to first place the magnetic piece at an open end of the anode cylinder, on which is formed a predetermined inward projection positioned opposite from the thin end section. Then, the metal container would be positioned, and the outer perimeter bend of the metal container would be pressed into the projection, thus assembling the elements before making the tight weld.
Referring now to FIG.
3
(
a
), it is also possible to place, on the opening of anode cylinder
6
, magnetic piece
8
and a metal container
21
, on which is formed a predetermined number of holes
22
along outer perimeter bend
21
a
. Then, projection tool
17
is placed outside of anode cylinder
6
, opposite from thin end section
6
a.
Referring to FIG.
3
(
b
), projection tool
17
is aligned with hole
22
and impacted against thin end section
6
a
of anode cylinder
6
. Thin end section
6
a
forms inward projection
18
. Inward projection
18
is inserted into hole
22
. It is desirable to have at least three inward projections
18
and holes
22
engaged at the same time along the perimeter so that metal container
21
stays centered. Then, thin end section
6
a
and outer perimeter bend
21
a
are tightly welded.
In this embodiment of the present invention, inward projection
18
of thin end section
6
a
loosely secures metal container
21
, thus keeping metal container
21
centered, allowing accurate welding of thin end section
6
a
and metal container
21
. This provides a tight bond between anode cylinder
6
and metal container
21
. Metal container
21
is supported by laterally projecting inward projection
18
. Thus, as with the embodiment described above, loose securing is achieved without increasing the height of anode cylinder
6
. As a result, the material costs for anode cylinder
6
are reduced.
In these embodiments, the outer perimeter bend of the metal container is loosely secured by a predetermined number of projections projecting inward from the thin end section of the anode cylinder. The present invention is not restricted to this, however, and it would also be possible to loosely secure the outer perimeter bend of the metal container using a ring-shaped projection projecting inward from the thin end section of the anode cylinder.
As described above, the present invention allows improved welding for the assembly of the main magnetron unit. Additional, the present invention provides a tight bond between the anode cylinder and the metal container.
Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.
Claims
- 1. A method for making a magnetron wherein said magnetron comprises:an anode cylinder; a plurality of vanes arranged radially within said anode cylinder; a magnetic piece disposed at an open end section of said anode cylinder; an anode vacuum container, including a metal container covering an upper surface of said magnetic piece; a cathode disposed along a central axis of said vacuum container; and an antenna externally discharging microwaves; said method having steps comprising: placing said magnetic piece and said metal container, in that order, on a shelf formed inwardly on a thin end section projecting from said open end section of said anode cylinder; forming a predetermined number of projections projecting inwardly from said thin end section of said anode cylinder, whereby said metal container is loosely secured; and tightly welding said thin end section with said metal container.
- 2. The method for making magnetrons as described in claim 1, wherein an outer perimeter of said metal container is bent inward to form an outer perimeter bend, covering a substantial section of end portions of said magnetic piece.
- 3. The method for making magnetrons as described in claim 2, wherein said predetermined number of projections are formed after said metal piece and said metal container have been installed by using a projection tool disposed outside said thin end section of said anode cylinder.
- 4. The method for making magnetrons as described in claim 3, wherein said predetermined number of projections are inserted into a predetermined number of holes disposed on said outer perimeter bend of said metal container.
- 5. The method for making magnetrons as described in claim 2, wherein:said predetermined number of projections are fanned before said metal container is installed; and loosely securing said metal container by pushing said outer perimeter bend of said metal container into said predetermined number of projections.
- 6. The method for making magnetrons as described in claim 5, wherein said predetermined number of projections are inserted into a predetermined number of holes disposed on said outer perimeter bend of said metal container.
- 7. The method for making magnetrons as described in claim 2, wherein said predetermined number of projections are inserted into a predetermined number of holes disposed on said outer perimeter bend of said metal container.
- 8. The method for making magnetrons as described in claim 2, wherein an end surface of said thin end section formed as a projection is formed lower than an upper surface of said metal container.
- 9. The method for making magnetrons as described in claim 8, wherein said predetermined number of projections are inserted into a predetermined number of holes disposed on said outer perimeter bend of said metal container.
- 10. A method for making magnetrons including, said magnetrons comprising:an anode cylinder; a plurality of vanes arranged radially within said anode cylinder; a magnetic piece disposed at an open end section of said anode cylinder; an anode vacuum container including a metal container disposed to cover an upper surface of said magnetic piece; a cathode disposed along a central axis of said vacuum container; and an antenna externally discharging microwaves; said method having steps comprising: placing said magnetic piece and said metal container, in that order, on a shelf formed inwardly on a thin end section projecting from said open end section of said anode cylinder; and forming a substantially ring-shaped projection, projecting inwardly from said thin end section of said anode cylinder, whereby said metal container is loosely secured; and tightly welding said thin end section with said metal container.
- 11. The method for making magnetrons as described in claim 10, wherein an outer perimeter of said metal container is bent inward to form an outer perimeter bend, covering a substantial section of end portions of said magnetic piece.
- 12. The method for making magnetrons as described in claim 11, wherein said ring-shaped projection is formed after said magnetic piece and said metal container have been installed by using a projection tool disposed outside said thin end section of said anode cylinder.
- 13. The method for making magnetrons as described in claim 12, wherein an end surface of said thin end section formed as a projection is formed lower than an upper surface of said metal container.
- 14. The method for making magnetrons as described in claim 11, wherein an end surface of said thin end section formed as a projection is formed lower than an upper surface of said metal container.
- 15. The method for making magnetrons as described in claim 11, wherein:said ring-shaped projections is formed before said metal container is installed; and loosely securing said metal container by pushing said outer perimeter bend of said metal container into said ring-shaped projection.
- 16. The method for making magnetrons as described in claim 15, wherein an end surface of said thin end section formed as a projection is formed lower than an upper surface of said metal container.
- 17. A method for making a magnetron wherein said magnetron comprises:an anode cylinder; a plurality of vanes arranged radially within said anode cylinder; a magnetic piece disposed at an open end section of said anode cylinder; an anode vacuum container, including a metal container covering an upper surface of said magnetic piece; a cathode disposed along a central axis of said vacuum container; and an antenna externally discharging microwaves; said method having steps comprising: bending inward an outer perimeter of said metal container to form an outer perimeter bend for covering a substantial section of end portions of said magnetic piece; placing said magnetic piece and said metal container, in that order, on a shelf formed inwardly on a thin end section projecting from said open end section of said anode cylinder; forming a predetermined number of projections projecting inwardly from said thin end section of said anode cylinder before said metal container is installed; loosely securing said metal container by pushing said outer perimeter bend of said metal container into said predetermined number of projections; and tightly welding said thin end section with said metal container.
- 18. A method for making magnetrons including, said magnetrons comprising:an anode cylinder; a plurality of vanes arranged radially within said anode cylinder; a magnetic piece disposed at an open end section of said anode cylinder; an anode vacuum container including a metal container disposed to cover an upper surface of said magnetic piece; a cathode disposed along a central axis of said vacuum container; and an antenna externally discharging microwaves; said method having steps comprising: bending inward an outer perimeter of said metal container to form an outer perimeter bend for covering a substantial section of end portions of said magnetic piece; placing said magnetic piece and said metal container, in that order, on a shelf formed inwardly on a thin end section projecting from said open end section of said anode cylinder; and forming a substantially ring-shaped projection before said metal container is installed, projecting inwardly from said thin end section of said anode cylinder; loosely securing said metal container by pushing said outer perimeter bend of said metal container into said ring-shaped projection; and tightly welding said thin end section with said metal container.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-390962 |
Dec 2000 |
JP |
|
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A |
4495397 |
Opprecht et al. |
Jan 1985 |
A |
4650951 |
Koga et al. |
Mar 1987 |
A |
5073693 |
Kikuchi et al. |
Dec 1991 |
A |
5168142 |
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Dec 1992 |
A |
6037559 |
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A |
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Number |
Date |
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Jun 1985 |
JP |
63 146326 |
Jun 1988 |
JP |
02 061933 |
Jan 1990 |
JP |
05 275019 |
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JP |
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