Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2001-12-12
2004-05-04
Reichard, Dean (Department: 2831)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C445S043000, C219S091230
Reexamination Certificate
active
06729926
ABSTRACT:
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.
REFERENCES:
patent: 3610870 (1971-10-01), Sakamoto
patent: 4495397 (1985-01-01), Opprecht et al.
patent: 4650951 (1987-03-01), Koga et al.
patent: 5073693 (1991-12-01), Kikuchi et al.
patent: 5168142 (1992-12-01), Gartner et al.
patent: 6037559 (2000-03-01), Okabe et al.
patent: 60 117527 (1985-06-01), None
patent: 63 146326 (1988-06-01), None
patent: 02 061933 (1990-01-01), None
patent: 05 275019 (1993-10-01), None
patent: 2002-197984 (2002-07-01), None
Hasegawa Setsuo
Miki Kazuki
Murao Noriyuki
Nakai Satoshi
Okada Noriyuki
Darby & Darby
Estrada Angel R.
Reichard Dean
Sanyo Electric Co,. Ltd.
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