JPH0679462B2 - Method for manufacturing anode structure for magnetron - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing an anode assembly of a magnetron used in microwave heating equipment such as a microwave oven.

2. Description of the Related Art Generally, an anode assembly of a magnetron is composed of an anode cylinder made of copper having a large number of radially arranged vanes on its inner peripheral surface, and a pair of mortar-shaped magnetic poles provided at both open ends of the anode cylinder. And a pair of eyelet-shaped metal tubes which are attached or arc-welded to the opening edge of the anode cylinder so as to cover the magnetic pole pieces.

According to the anode assembly manufacturing technique disclosed in Japanese Utility Model Publication No. 57-178362, the outer peripheral edge of the mortar-shaped magnetic pole piece and the eyelet shape are formed on the step portion provided on the inner peripheral surface side of the opening edge of the anode cylinder. After sequentially stacking the outer peripheral edges of the flange portion of the metal tube, the opening edge of the anode cylinder is melted by arc welding, and the edge is hermetically sealed to the outer peripheral edges of the metal tube and the pole piece. There is.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention When applying the arc welding method and performing the above-described sealing, the anode cylinder must be filled with a reducing gas such as nitrogen in order to prevent oxidation of the electrode member. However, part of the reducing gas leaks out of the anode cylinder through the gap that exists between the anode cylinder and the pole piece or metal tube that is fitted into the opening edge of the anode cylinder. As a result of mixing with the argon gas supplied on the surface, it becomes difficult to obtain a good weld surface. In particular, when irregularities or pinholes are generated on the welded surface, the vacuum degree inside the tube of the completed magnetron is reduced, which is a fatal defect.

Means for Solving the Problems According to the present invention, the outer peripheral edge of the mortar-shaped magnetic pole piece and the eyelet-shaped metal tube are provided on the step portion provided on the inner peripheral surface side to make the opening end edge of the copper anode cylindrical body thin After sequentially stacking the outer peripheral edges of the flange portion of, the pressing body rotating on the central axis concentric with the anode cylinder is brought close to the anode cylinder, and is rotatably provided in the peripheral part of the pressing body. The inclined edge of the conical roller is pressed to bend the opening edge toward the tube axis, and then a reducing gas is introduced into the anode cylinder to melt the opening edge from the outside by arc welding. The edges are hermetically sealed to the outer peripheral edges of the metal tube and the pole piece.

With this structure, the opening edge of the anode cylinder before arc welding almost completely covers the outer peripheral edges of the pole piece and the metal tube inserted therethrough, so that the reduction filled in the anode cylinder is reduced. Gas leakage is blocked, and the argon gas atmosphere formed for arc welding on the outer peripheral surface side of the anode cylinder is not disturbed by the mixing of other gases. Also,
Since the opening edge of the anode cylinder at the time of arc welding is already shaped by the bending, an extremely good welded surface can be obtained.

EXAMPLES Next, the present invention will be described with reference to the examples shown in the drawings.

As shown in FIG. 1, the opening end edge 1a of the drawn copper anode cylinder 1 is made thin by a step 2 formed on the inner peripheral surface side thereof, and is a mortar made of iron or iron alloy. The outer peripheral edge of the magnetic pole piece 3 and the outer peripheral edge of the flange portion 4a of the eyelet-shaped metal tube 4 are sequentially stacked on the step portion 2.
Reference numeral 5 is a vane, and 6 is a microwave output lead wire.

The pressurizing body 7 is prepared for bending the opening end edge 1a of the anode cylinder 1 toward the tube axis 8 side, and includes a conical roller 9 which is rotatable about its axis for pressing the opening end edge 1a. The shaft 11 is connected to a power mechanism (not shown) for rotating and raising and lowering so that it can rotate about a central axis 10 concentric with the tube axis 8 and can be raised and lowered. On the other hand, the anode cylinder 1
Are fixed by a jig (not shown).

When the pressurizing body 7 descends in the direction of the arrow while rotating, as shown in FIG. 2, the inclined surface of the conical roller 9 comes into contact with the opening end edge 1a of the anode cylinder 1 and the roller 9 rotates. To start. When the pressing body 7 further descends, the roller 9 moves to the third position.
As shown in the figure, the opening edge 1a is bent circumferentially uniformly toward the tube axis 8 side. Thus, since the outer peripheral edges of the metal tube 4 and the pole piece 3 are covered by the opening end edge 1a of the anode cylinder 1,
Then, a reducing gas such as nitrogen gas is introduced into the anode cylinder 1, and the bent opening edge 1a is, as shown in FIG.
Melted by arc welding. Reference numeral 12 indicates an electrode rod for arc welding.

Although the bending at one opening edge of the anode cylinder 1 has been described above, the other opening edge is also bent in the same manner as described above. Further, in the above-mentioned embodiment, the shaft 9a of the conical roller 9 is arranged in the direction orthogonal to the tube axis 8, but it may be arranged along the tube axis. However, it goes without saying that the roller 9 in that case must be set so that the small diameter portion is on the lower side. Furthermore, a plating layer of nickel, silver, copper, or the like can be provided on at least the welded surfaces of the pole piece 3 and the metal tube 4.

Effects of the Invention As described above, according to the present invention, the opening edge of the anode cylinder,
Between the pole piece and the metal tube inserted through the edge,
Since it is almost completely blocked before arc welding, it is possible to eliminate arc welding defects caused by leakage of the antioxidant reducing gas that has filled the anode cylinder body during arc welding to the outside of the anode cylinder body. Since the opening edge of the anode cylinder is shaped in advance by the bending, it is possible to obtain a very good welded surface having high airtightness.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing the relative relationship between an anode assembly manufactured by applying the manufacturing method of the present invention and a pressurizer, and FIGS. 2 and 3 are sectional views of an anode cylinder manufactured by the manufacturing method. FIG. 4 is a side sectional view of the main part of the step of bending the opening edge, and FIG. 4 is a side sectional view of the main part of the step of arc welding the opening edge of the anode cylinder by the manufacturing method. 1 ... Anode cylinder, 3 ... Magnetic pole piece, 4 ... Metal tube, 7 ...
Pressure body, 9 ... Roller.

Claims (1)

[Claims] 1. An outer peripheral edge of a mortar-shaped magnetic pole piece and an outer peripheral edge of a flange portion of an eyelet-shaped metal tube are sequentially formed on a step portion provided on an inner peripheral surface side of the copper anode cylindrical body so as to have a thin wall. A pressure member rotating on the central axis concentric with the anode cylinder, is brought close to the anode cylinder, and the inclined surface of the conical roller rotatably provided on the periphery of the pressure member. Bend the opening edge toward the tube axis side by pressing, then, introducing a reducing gas into the anode cylinder to melt the opening edge from the outside by arc welding, and the edge is the metal pipe and A method for manufacturing an anode assembly for a magnetron, comprising airtightly sealing each outer peripheral edge of the magnetic pole piece.