Magnetron for microwave ovens and method of forming same

A magnetron for microwave ovens includes an anode cylinder, a plurality of plate-shaped vanes radially arranged along an inside surface of the anode cylinder, one or more strap rings to electrically connect the plurality of plate-shaped vanes to each other, an antenna connected to one of the plurality of vanes to radiate microwaves generated from the plurality of vanes. Each of the vanes is plated with a brazing material to be brazed to one or more of the anode cylinder, the one or more strap rings and the antenna, and the brazing material has a plating depth of about 2.25 to 8 μm. The magnetron having the anode allows a manufacturing process of the anode to be simplified to reduce manufacturing time and equipment costs. Furthermore, the anode prevents brazing defects, and allows the magnetron to have an optimal performance.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 2003-63002, filed Sep. 9, 2003 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, in general, to a magnetron for microwave ovens and, more particularly, to an anode of a magnetron for microwave ovens, which allows the magnetron to have an optimal performance while causing a manufacturing process of the anode to be simplified and assembly of the anode to be easily performed.

2. Description of the Related Art

Generally, a magnetron for microwave ovens is a high frequency oscillation tube having a fundamental frequency at 2450 MHz. The magnetron includes a cathode and an anode coaxially arranged to form an electric field, and a pair of pole pieces to form magnetic fields above and below the cathode and the anode.

A structure of an anode100is described in detail below. As shown inFIG. 1, the anode100includes an anode cylinder110, a plurality of vanes120radially arranged in the anode cylinder110to form a resonant cavity, a plurality of strap rings130to electrically connect the plurality of vanes120to each other, and an antenna140connected to one of the plurality of vanes120to radiate microwaves. Assembly accuracy of the above-described component parts greatly influences performance of a magnetron. The anode100of the magnetron is manufactured by a conventional manufacturing method described below.

The anode cylinder110, the plurality of vanes120, the strap rings130, and the antenna140are separately formed. The anode cylinder110is formed by cutting off and processing a pipe-shaped material, strap ring notches121are formed in each of the vanes120to fasten the strap rings130, and an antenna notch122is formed in one of the plurality of vanes120to fasten the antenna140.

Further, the strap rings130and the antenna140are brazed with a brazing material to be joined to the vanes120.

The component parts are mounted on an assembly jig. The anode cylinder110, the plurality of vanes120, the strap rings130, and the antenna140are fastened at predetermined locations using the assembly jig. A wire shaped brazing material is supplied from predetermined locations so that the wire shaped brazing material inserts between the plurality of vanes120and the anode cylinder110.

The assembly jig on which the component parts are fastened is placed into a brazing furnace and is heated to more than 800° C. so that the brazing material melts and the component parts are joined to each other.

However, the conventional method of manufacturing the anode100of the magnetron is problematic in that complicated brazing processes, in which the wire shaped brazing material is used and the strap rings130and the antenna140must be separately plated with the brazing material, must be performed to braze the component parts. Furthermore, when the wire shaped brazing material is insufficiently inserted into joint portions, a brazing defect may be incurred.

SUMMARY OF THE INVENTION

Accordingly, it is an aspect of the present invention to provide a magnetron for microwave ovens, which has an anode to allow a manufacturing process thereof to be simplified, to allow the magnetron to have an optimal performance, and to prevent brazing defects attributable to insufficient blazing material from being inserted into the anode.

Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, of may be learned by practice of the invention.

The above and/or other aspects are achieved by providing a magnetron for microwave ovens, including an anode cylinder, a plurality of plate-shaped vanes radially arranged along an inside surface of the anode cylinder, one or more strap rings to electrically connect the plurality of the vanes to each other, an antenna connected to one of the plurality of vanes to radiate microwaves generated from the vanes, wherein each of the vanes is plated with a brazing material to be brazed to one or more of the anode cylinder, of the strap rings and of the antenna, and the brazing material has a plating depth in the range of about 2.25 μm to 8 μm.

The brazing material may be plated on one of entire surfaces and joint portions of the plurality of vanes to which the anode cylinder, the strap rings and the antenna are brazed.

The brazing material may contain silver of 72±2% in a weight ratio and copper of a remaining percentage.

Each of the vanes may be plated with a brazing material to be brazed to one or more of the anode cylinder, of the strap rings and of the antenna, and the brazing material may have a predetermined plating depth to prevent insufficiency and excess thereof after brazing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the embodiment of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

An anode200of a magnetron according to the present invention, as shown inFIG. 2, includes an anode cylinder10, a plurality of plate-shaped vanes20radially arranged along an inside surface of the anode cylinder10, one or more strap rings30to electrically connect the plurality of plate-shaped vanes20to each other, and an antenna140connected to one of the plurality of plate-shaped vanes20to radiate microwaves.

The anode cylinder10, the plurality of plate-shaped vanes20, the strap rings30, and the antenna40are generally made of oxygen-free copper materials. The plurality of plate-shaped vanes20are formed in rectangular plate shapes, strap ring notches21are formed on a top and bottom of each of the vanes20to fasten the strap rings30, and an antenna notch22is formed in one of the vanes20to fasten the antenna40. A total of four strap rings30with a first pair of strap rings30placed in the tops of each of the vanes20and a second pair of strap rings30placed in the bottoms of each of the vanes20are provided. Each of the pairs of strap rings30has an inner strap ring31having a smaller diameter and an outer strap ring32having a larger diameter. The inner strap ring31and outer strap ring32of each of the pairs of strap rings30are alternately joined to the plurality of plate-shaped vanes20through the strap ring notches21.

Furthermore, each of the plate-shaped vanes20is plated with a brazing material to be joined to the anode cylinder10, the strap rings30and the antenna40by brazing. The brazing material is an alloy, which contains silver of about 72% in a weight ratio and copper of a remaining percentage. The brazing material may be plated on entire surfaces of each of the vanes20, or on joint portions of each of the vanes20to join with other component parts of the anode200.

A method of manufacturing the anode200of the magnetron is described below.

The method has several operations, which include separately forming component parts, plating brazing material on each of the vanes20, mounting the component parts on an assembly jig, putting the assembly jig, on which the component parts are mounted, into a brazing furnace, heating the assembly jig, and separating a finished product from the assembly jig.

The component parts are separately formed. A pipe shaped material is cut off and processed to form the anode cylinder10. The plurality of vanes20are formed in rectangular plate shapes, the strap ring notches21are formed in a top and a bottom of each of the vanes20to fasten the strap rings30, and the antenna notch22is formed in one of the vanes20to fasten the antenna40. The strap rings30include the inner strap rings31each having the smaller diameter and the outer strap rings32each having the larger diameter. Further, the antenna40is formed to fasten to the one of the vanes20.

Each of the vanes20is plated with brazing material. The brazing material is used to join each of the vanes20to the anode cylinder10, the strap rings30, and the antenna40.

The component parts, which are the anode cylinder10, the plurality of vanes20, the strap rings30and the antenna40, fasten at predetermined locations using the assembly jig.

The assembly jig on which the component parts are mounted is placed into the brazing furnace and heated to more than 800° C., so that the brazing material plated on each of the vanes20melts and, thus, each of the vanes20adheres to joint portions of the anode cylinder10, the strap rings30, and the antenna40.

In the method of manufacturing the anode200of the magnetron, the brazing material is plated only on the vanes20. Thus, the manufacturing process is simplified and equipment and time needed for assembly of the anode200are reduced because the brazing material does not have to be plated on the strap rings30and the antenna40.

Furthermore, brazing defects incurred when using a conventional wire shaped brazing material which is insufficiently inserted into the joint portions are prevented.

Hereinafter, degrees of brazing so that the magnetron may operate at optimal performance according to plating depths of the brazing material plated on each of the vanes20are described in detail with reference toFIG. 3.

FIG. 3is a graph showing the degrees of brazing according to the plating depths of the brazing material. An X-axis represents the plating depth, while a Y-axis represents the degrees of brazing according to the plating depths. A one-dot chain line represents an optimal degree of brazing. Two dotted lines, which are shown above and below the one-dot chain line, respectively, represent tolerance limits of the degrees of brazing.

As shown inFIG. 3, the brazing depth with which the optimal degree of brazing is obtained is about 4 to 6 μm, and the tolerance limits of the brazing depth are about 2.25 μm and 8 μm. If the plating depth is smaller than 2.25 μm, a phenomenon, in which component parts that must be brazed are not brazed, may occur due to a shortage of the brazing material. If the plating depth is larger than 8 μm, the brazing material is excessive, so that the brazing material left over after brazing remains on surfaces of the component parts and, thus, negatively affect surface accuracies thereof and a performance of the magnetron may suffer.

As is apparent from the above description, a magnetron is provided, in which brazing material is plated only on vanes rather than on all of component parts, to braze the component parts of an anode, thus simplifying a manufacturing process thereof. Further, a manufacturing time and a cost of equipment are reduced. Moreover, a brazing defect caused by insufficient brazing material inserted between the vanes and an anode cylinder is prevented.

Further, when the plating depth of the brazing material is maintained within a range of about 4 μm to 6 μm, an optimal degree of brazing is obtained and a performance reliability of the magnetron is improved.