JPS6212028A - Attachment method for electrode of metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To decrease man-hours and enhance reliability of the welded part by caulking and welding two opposing points on the outer circumference of a tip part in the direction of an electrode mandrel under the condition that an electrode supported by an electrode supporting pole is inserted loosely in the center of the tip part of an electrode supporting tube. CONSTITUTION:The tip part 1a of an electrode supporting tube 1 is contracted, and in the hole 5a of an electrode supporting pole 5 fixed to a fixing member, an electrode mandrel 3 provided with an electrode 2 in its tip is inserted and fixed and then is covered by the electrode supporting tube 1. In this case, the electrode mandrel 3 keeps a condition that it is loosely inserted in the center of the tip opening 1b of the contracted part (the tip part) 1a of the electrode supporting tube 1. Then the tip opening 1b is caulked by adding force to A, B directions at two opposing points on the outer circumference of the tip opening 1b. Next, the junction between the electrode mandrel 3 and the tip part 1b of the electrode supporting tube 1 is welded, therefore it results in that nether bending of the electrode mandrel 3 and nor defective welding can take place in the case of welding. Thus, the electrode supporting tube 1 fixing the electrode 3 namely the electrode 2 is extracted from the electrode supporting pole 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for attaching electrodes to a metal vapor discharge lamp using a translucent alumina arc tube.

[Prior art] In metal vapor discharge lamps such as high-pressure sodium lamps, a cylindrical electrode support tube is airtightly inserted into the end wall of a perforated alumina arc tube, and an electrode is attached to the tip of the electrode support tube inside the arc tube. I am trying to install it.

4 to 7 show conventional electrode mounting structures. In FIG. 4, the electrode shaft 3 of the electrode 2 is fixed to the upper end of the cylindrical electrode support tube 1 by caulking from four directions.
After that, the joint between the electrode support tube 1 and the electrode mandrel 3 is welded,
Furthermore, exhaust holes 4 are bored at required positions. This exhaust hole 4
The reason why the electrode support tube 1 is provided is that the electrode support tube 1 is also used as an exhaust tube of the arc tube. In FIGS. 5 and 6, the upper end of the electrode support tube 1 is processed so that an exhaust hole 4 is formed when the electrode shaft 3 of the electrode 2 is caulked. 7th
In the figure, the upper end of the electrode support tube 1 is drawn, and the electrode shaft 3 of the electrode 2 is inserted into the tip and welded to form an exhaust hole 4.

[Problems to be Solved by the Invention] The electrode support tube is usually made of a high melting point metal such as niobium Nb. This high melting point metal is hard and difficult to process. For this reason, the conventional electrode mounting structures shown in FIGS. 4 to 7 have the following drawbacks.

(1) Manufacturing costs are high because it requires work to provide exhaust holes.

(2) Depending on the degree of caulking, there is a risk that the electrode mandrel may be bent or a welding defect may occur during welding between the electrode mandrel and the electrode support tube.

(3) As shown in FIGS. 5 and 6, if complicated processing is required before caulking, the manufacturing cost increases accordingly.

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electrode support structure that reduces the number of work steps and improves the reliability of welded parts. . In order to achieve this objective, the present invention has a cylindrical electrode support tube that is inserted into the end wall of a translucent alumina arc tube, with its tip end narrowed and supported by an electrode support rod in the center of the tip end. With the electrode inserted loosely, two opposing points on the outer periphery of the tip are caulked in the direction of the electrode core, and the electrode core and the tip of the electrode support tube are welded together.

[Function] With the above-described configuration, the present invention eliminates the need for complicated machining such as making cuts in the electrode support tube, and furthermore, a large gap is created between the electrode mandrel and the electrode support tube other than the welding point, and the exhaust hole is removed. Therefore, there is no need for a special work process to create an exhaust hole, and caulking is simple in two directions, and the welding work is performed with the electrode mandrel fixed with the electrode support rod, so the electrode mandrel There is no need to worry about bending or welding defects.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a diagram showing how to attach the electrode to the electrode support tube.
First, the tip 1a of the electrode support tube 1 is drawn. This is because the difference between the inner diameter of the electrode support tube 1 and the outer diameter of the electrode mandrel 3 is too large. The inner diameter of the tip portion 1a of the electrode is narrowed so that it is about 2 to 3 times the outer diameter of the electrode mandrel 3.

Next, the electrode mandrel 3 having the electrode 2 at its tip is inserted and fixed into the hole 5a of the electrode support rod 5 fixed to a fixing member (not shown), and the electrode support tube 1 is placed over it.

At this time, the shoulder of the electrode support rod 5 comes into contact with the inner surface of the constricted part (tip part) la of the electrode support tube 1, supporting the electrode support tube 1, and the electrode is placed in the center of the distal end opening 1b of the constricted part 1a. Mandrel 3
becomes loosely inserted. Then, force is applied in directions A and B at two opposing points on the outer peripheral edge of the tip opening 1b to caulk the tip opening ib. In this way, the electrode mandrel 3 is crimped while being supported at the center of the tip opening 1b by the electrode support rod 5, so crimping is facilitated.

In this state, next, the joint between the electrode mandrel 3 and the tip 1b of the electrode support tube 1 is welded using a plasma welder 6 or the like.

In this way, the electrode core 3 is supported by the electrode support rod 5,
That is, since welding is performed with the electrode mandrel 3 and the electrode support structure held together by caulking, the electrode mandrel 3 is not bent during welding, and welding defects do not occur.

When the electrode shaft 3, that is, the electrode 2 fixed to the electrode support tube 1 as described above is removed from the electrode support rod 5, the result is as shown in FIG. Since the two opposing points of the tip opening 1b of the electrode support tube 1 are welded together, the exhaust hole 4 is formed without any special processing on the electrode support tube 1, as shown in FIG. . The area of the exhaust hole 4 can be increased as the inner diameter of the tip opening 1b is made larger than the outer diameter of the electrode mandrel 3, and the exhaust speed can be increased.

[Effects of the Invention] As explained above, according to the present invention, it is possible to properly attach an electrode to an electrode support tube made of a high-melting point metal such as niobium, which is difficult to process, without performing any special processing, and also to form an exhaust hole. can be formed, thereby reducing the number of man-hours and costs.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a diagram showing an electrode mounting method according to an embodiment of the present invention, Fig. 2 is a block diagram of an electrode support tube to which an electrode is mounted by the method shown in Fig. FIG. 3 is a sectional view taken along the line ■-m in FIG. 2. FIG. 4, FIG. 5, FIG. 6, and FIG. 7 are perspective views of electrode support tubes showing different conventional electrode support structures, respectively. 1... Electrode support tube, 1a... Tip part (squeezed part), 2...
Electrode, 3. Electrode mandrel, 4. Exhaust hole, 5. Electrode support rod, 6. Welding machine. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1 Squeeze the tip of a cylindrical electrode support tube to be inserted into the end wall of a translucent alumina arc tube, insert the electrode mandrel supported by an electrode support rod loosely into the center of the tip, and A method for attaching an electrode to a metal vapor discharge lamp, which comprises caulking two opposing points on the outer periphery of the tip toward the electrode core and welding to the electrode core.