JPS61173437A - Method for manufacturing luminous tube for high pressure metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To obtain a luminous tube having joint portions which have no fear of gas leak and excellent reliability by incorporating non-baked tubular material made of high purity alpha alumina to end plate material with secondary baking. CONSTITUTION:High purity alpha alumina powder having relatively small initial baking shrinkage ratio is used as the material of and end plate 1. While high purity alpha alumina powder having larger initial baking shrinkage ratio than that of alumina powder for end plate 1 is used as the material of a tube. And unbaked end plate material is put into end portions of unbaked tubular material. Thereafter, when the entire is baked primarily, end plate material is strongly tightened by the tubular material, and both material are put together by pressure. And when they are baked at high temperature as secondary baking, the end plate material and the tubular material become optically transmissive end plate 1 and tube 2 respectively, and crystalline composition at joint portions of the tubular material and end plate material are integrated to be combined gas tightly, and semi-closed type emitting luminous tubes can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing an arc tube for a high-pressure metal vapor discharge lamp.

(Prior art) Translucent alumina, which has excellent corrosion resistance and translucency, is used for the tube body of arc tubes for high-pressure metal vapor discharge lamps. Alumina is also used. As a method of manufacturing a semi-closed arc tube with sealed ends by combining these parts, the end plate material and the tubular material are first fired at a relatively low temperature to burn out the organic matter. Insert the end plate material into the end of the tubular material and heat the entire body to 1900℃.
A known method is to perform a second firing at a high temperature before and after the first firing to make the material transparent, and then use the difference in the firing shrinkage rate during the second firing to bond the two together. (For example, Japanese Patent Publication No. 50-30384. However, in such a conventional method, an end plate material that has also been hardened is inserted into a tubular material that has been hardened by the first firing, so there is no damage to the joint after the second firing. This had the disadvantage of creating gaps that easily caused gas leaks.In addition, in the conventional method, the image material was fixed with a special jig to prevent it from shifting during the second firing, which was carried out at a high temperature of around 1900 degrees Celsius. This, combined with the above-mentioned drawbacks, has led to the problem that the reliability of the joint cannot be made sufficiently high.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and easily connects a tubular material and an end plate material with excellent reliability without fear of gas leakage. This was completed with the aim of creating a method for manufacturing arc tubes for high-pressure metal vapor discharge lamps.

(Means for Solving the Problems) The present invention involves forming an end plate material made of high-purity α-alumina powder into a tubular shape made of high-purity α-alumina powder that has a higher initial firing shrinkage rate during the first firing than the end plate material made of high-purity α-alumina powder. It is characterized in that it is inserted into the end of the material, first fired to press the two together, and then second fired to form a joint with an integrated crystal structure.

(Example) Next, the present invention will be explained in detail together with examples.

In the present invention, the high-purity α-alumina powder used as the raw material for the end plate (11) is relatively It is possible to use α-alumina powder which has a small initial firing shrinkage rate and has a specific surface area of 2rrf/g and low sintering activity.Such high-purity α-alumina powder can be used at a pressure of 2 to 3 t/aJ. It is pressed and formed into an end plate material.Meanwhile, the tube body (2)
The high-purity α-alumina powder used as the raw material for the end plate (1) has a larger initial firing shrinkage rate than the high-purity α-alumina powder used for the end plate (1), as shown by (B) in the graph of Figure 2. , for example, specific surface area 5 cd
/H commercially available high purity α-alumina powder can be used. This high-purity α-alumina powder also has 2 to 3
It is pressed at a pressure of t/- and formed into a tubular material. Next, the unfired end plate material described above is fitted into the end of the similarly unfired tubular material. After that, the whole thing was placed in the air for 900 minutes.
When the primary firing is performed at ~1100℃, the high-purity α-alumina powder for the end plate has a lower sintering activity than the high-purity α-alumina powder for the tube body, and the initial firing shrinkage rate during the primary firing is smaller. As the first firing progresses, the end plate material is strongly tightened by the tubular material, and the two are crimped together. At this stage, the end plate material and the tubular material are only physically joined, but next they are heated for 1900 minutes in a reducing atmosphere using hydrogen gas.
If the secondary firing is performed at a high temperature around ℃, the end plate material and the tubular material will become transparent and become translucent end plate +11 and tube body (2), respectively, and the joint between the tubular material and the end plate material will become transparent. The crystal structure of is integrated, and the tube body (2) and the end plate Tl) are gas-tightly connected to obtain a semi-closed arc tube for a high-pressure metal vapor discharge lamp. It goes without saying that the shape of the tubular body (2) may be a cylindrical tube in addition to the irregularly shaped tube shown in the figure.

The arc tube for a high-pressure metal vapor discharge lamp manufactured as described above has a pressure difference between the tube body (2) and the end plate (l) due to the difference in initial firing shrinkage rate during the first firing at a relatively low temperature. During the second firing, the end plate material and the tubular material undergo an effective sintering reaction on the bonded surfaces, resulting in a structure in which the two are integrated in terms of crystal structure. Therefore, the joint is completely leak-tight. According to the present invention, since the fitting between the tubular material and the end plate material is performed in an unfired state, they become familiar with each other and can easily achieve a tight fitting, and further,
Since the painting material is fixed by the first firing at a relatively low temperature, it is possible to accurately join without positional displacement during the second firing at a high temperature without using a special jig. The reliability of the dimensions between the end plates of the section can be increased.

(Effects of the Invention) As is clear from the above description, the present invention is capable of bonding an unfired tubular material made of high-purity α-alumina and an end plate material by reducing the difference in initial firing shrinkage rate during the first firing. Since this is done by unifying the crystal structure during the second firing, it is easy to manufacture arc tubes for high-pressure metal vapor discharge lamps that have highly reliable joints with no risk of gas leakage. This meets the demands of the times when high reliability is required in the leaktightness of joints. Therefore, the present invention greatly contributes to the development of industry by solving the problems of the conventional method of manufacturing arc tubes for high-pressure metal vapor discharge lamps.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an arc tube for a high-pressure metal vapor discharge lamp manufactured by the method of the present invention, and FIG. 2 is a firing during the first firing of high-purity α-alumina powder used in the present invention. It is a graph showing shrinkage rate. (1): End plate, (2): Tube body. Figure 1 l

Claims (1)

[Claims] An end plate material made of high-purity α-alumina powder is formed and inserted into the end of a tubular material made of high-purity α-alumina powder, which has a higher initial firing shrinkage rate during the first firing than the end plate material, and then the first firing is performed. 1. A method for manufacturing an arc tube for a high-pressure metal vapor discharge lamp, which comprises crimping the two together and then performing a second firing to form a crimped part with an integrated crystal structure.