JPH0151018B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing a tube.

Conventionally, arc tubes such as metal halide lamps are made by heating and crushing both ends of a quartz glass tube, and holding the base of the electrode at the crushing part, while also taking into account the heat retention and pressure resistance of the tube ends. The end portion is formed with a smaller diameter than the center portion of the tube.

That is, in order to increase the vapor pressure of the metal halide sealed in the arc tube, it is necessary to increase the temperature of the coldest part of the arc tube, and various methods have been used. For example, one method is to mold the inner surface of the tube near the electrodes into a V- or U-shape, but this method requires that the axial length of the crushed sealing portion be compared to the distance between the electrodes. However, in the case of lamps with a short distance between electrodes, the length of the crushed seal cannot be made so short in order to maintain airtightness, so the distance between the electrodes is This increases the heat conduction to the crushed sealing portion, making it impossible to maintain the required temperature at the coldest part of the arc tube. For this reason, measures may be taken to reduce heat radiation loss in this part or heat conduction loss to the atmospheric gas outside the arc tube by removing a part of the crushed sealing part, thereby increasing the heat retention effect. However, in this method, since the diameter of the quartz tube at the portion to be crushed and sealed is large, it is difficult to seal the electrode so as to accurately position it in the center of the tube.

On the other hand, after forming the arc tube so that the diameter of the part scheduled for crushing and sealing is smaller than the diameter of the central part of the arc tube,
There is also a method of more accurately regulating the attachment position of the electrode on the central axis of the tube by crushing and sealing.

For example, as shown in Fig. 1, there is a large diameter quartz tube 1 that forms the main body of the arc tube, and a smaller diameter quartz tube 2.
A small-diameter quartz tube 2 is crushed, and an introduction conductor 7 is hermetically sealed by joining an electrode 5 to one end of a metal foil 4 and an external introduction wire 6 to the other end of the crushed portion 3. Method. Alternatively, as shown in FIG. 2, after inflating the center portion 2a of the small-diameter quartz tube 2, the small-diameter end portion 2b is crushed and the conductor 7 is introduced into the crushed portion 3.
There are methods to airtightly seal the However, all of these methods have the disadvantage that the finished shape is not uniform, or that a complicated control device is required to make the shape uniform.

The present invention has been made to address the above-mentioned drawbacks.
It is an object of the present invention to provide a method for manufacturing an arc tube, which can form a simple and uniform sealed end shape of an arc tube, and can accurately seal an introduction conductor such as an electrode at a desired position.

The present invention is characterized by a first step of forming a collapsed part by leaving a hole in the end of the glass tube for placing the introducing conductor, and then, after placing the introducing conductor in the hole, further forming the crushed part. and a second step of heating and crushing to airtightly seal the introduced conductor.

Hereinafter, details of the present invention will be explained with reference to an illustrated embodiment. First, as the first step,
As shown in the figure, the end 1b of the quartz glass tube 1 with an inner diameter of 10 mm is heated and softened, and air is introduced into the quartz glass tube to increase the pressure inside the tube. The crushed portion 3 is formed using a pair of molds, such as those shown in FIG. 4, which have a recessed portion in the center so as to leave a hole 8 having a small diameter enough to accommodate the introduction conductor. Then,
As a second step, as shown in Figure C, a pair of lead-in conductors 7 made by joining an electrode 5 to one end of the metal foil 4 and an external lead-in wire 6 to the other end are connected with a distance between the electrodes of 15 mm.
After arranging the lead conductor 7 in the hole 8 such that the lead conductor 7 is placed in the hole 8, the crushed portion 3 is heated and crushed again to seal the lead-in conductor 7 airtightly.

If necessary, the heat from the crushed part 3 can be removed by cutting and removing a part 3a of the crushed part 3 using a laser beam or the like, as shown in FIG. It is also possible to reduce radiation and increase the heat retention effect of the arc tube.

Thereafter, mercury, a starting gas such as Ne--Ar, and metal halides such as scandium iodide (1.5 mg) and sodium iodide (8.5 mg) are sealed in the usual manner to produce a 100 W metal halide lamp arc tube.

According to this method, the introduction conductor is placed in the small-diameter hole formed in the collapsed part in the first step and then sealed, so the introduction conductor can be easily and accurately positioned at the center of the tube. Not only is this possible, but since the introduction conductor has not yet been placed in the first forming process, it is no longer necessary to use a non-oxidizing gas as the gas injected into the pipe to prevent undesired deformation of the pipe. It is economical because it is unnecessary and only requires air to be supplied. Also, there is no need to worry about oxidation of the introduced conductor, so
Since processing can be carried out at sufficiently high temperatures, the shape of the inner surface of the tube near the end of the tube, that is, near the electrode, can be formed into the desired shape and uniformly. Temperature fluctuations can be suppressed within a narrow range. Moreover, it has the advantage that it does not require a complicated control device like the conventional one.

As a result of measuring the luminous flux of 10 lamps manufactured in this way and 10 conventional lamps with crushed parts formed in one process, it was found that the conventional lamps were approximately 6000 lm±
While the variation was within a range of 1000lm, the lamp of the present invention had a variation of about 6000lm±500lm, and it was found that the variation was within a very narrow range.

Next, a 100W metal halide lamp arc tube was made through the first and second steps in exactly the same manner as in the above embodiment, and a portion of the crushed portion of this arc tube was removed using, for example, a laser beam, as shown in Figure 5. By cutting and removing the lamp, heat loss from the crushed part is prevented and the heat retention effect at the end of the arc tube is improved. As a result of measuring the luminous flux of each of 10 conventional lamps, it was approximately 7,200 lm ± 1,100 lm for the conventional lamp, while it was approximately 7,200 lm ± 600 lm for the lamp of the present invention, indicating that the variation in characteristics was again within a very narrow range. I found out.

Note that the present invention is not limited to the metal halide lamp of the above embodiment, but can also be applied to other bulbs such as high-pressure mercury lamps, if the shape of the sealed end is desired to be uniform and uniform. Alternatively, it is similarly advantageous when it is desired to increase the temperature at the end of the arc tube as much as possible to improve the heat retention effect.

As described in detail above, according to the present invention, a collapsed portion is formed in advance at the end of the glass tube, leaving a hole for arranging the lead-in conductor, and then the lead-in conductor is placed in the hole. Since the crushed portion is heated and crushed again to airtightly seal the introduced conductor, it is possible to form a uniform sealed end shape without using a complicated device as in the past, and it is also possible to form The introduction conductor can be accurately sealed at the desired position, and the temperature of the coldest part of the arc tube can be kept high, increasing the vapor pressure of the filled material and providing a tube with excellent characteristics. can.

[Brief explanation of drawings]

1 and 2 are process explanatory diagrams of a conventional tube manufacturing method, FIG. 3 is a process explanatory diagram of an embodiment of the method of the present invention, and FIG. 4 is a schematic perspective view showing an example of a crushing mold, FIG. 5 is an explanatory diagram of another embodiment. DESCRIPTION OF SYMBOLS 1... Quartz glass tube, 3... Crushing part, 7... Introducing conductor, 8... Hole.

Claims (1)

[Claims] 1. A first step of forming a crushed portion by leaving a hole in advance at the end of the glass tube for arranging the introducing conductor, and then further heating and crushing the crushed portion after arranging the introducing conductor in the hole. A method for manufacturing a tube, comprising a second step of hermetically sealing an introduction conductor.