JPH03147230A - Manufacture of metal halide lamp - Google Patents

Abstract

PURPOSE:To easily manufacture a light emitting tube having a constricted neck section without increasing the number of processes by disposing a forming mold around a thickened wall section of a glass tube material, with the forming mold having a valve section forming portion and, on both ends of the valve section forming portion, constricted neck section forming portions and performing blow forming. CONSTITUTION:A set of mating metal mold 7 is disposed in a mated condition around a thickened wall section 6, with the mold 7 having a valve section forming portion 7a of a spherical or rotated ellipsoidal shape in the center, a constricted neck section forming portions 7b on both ends of the valve section forming portion 7a, and glass tube material holding portions continuous to the constricted neck section forming portions 7b. Introducing a high pressure gas 8 such as nitrogen argon, etc., through an opening 1a of a glass tube material 1 to make the heated, thickened wall section 6 of the glass tube material 1 where the mating mold 7 is disposed bulge, a valve section 10 having constricted neck sections 9 on its both sides is simultaneously formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an arc tube for a metal halide lamp, and more particularly to a method for manufacturing an arc tube for a low-wattage metal halide lamp that is provided with apertures at both ends.

[Conventional technology]

Metal halide lamps, in which a metal halide is sealed together with mercury and a rare gas in an arc tube equipped with a pair of electrodes, have good color rendering properties and high luminous efficiency, and are therefore used as light sources in various fields.

However, in such metal halide lamps, the lower the wattage, the greater the relative value of heat loss from the ends of the arc tube, leading to problems such as deterioration of color characteristics and reduction in efficiency due to a decrease in the temperature of the coldest part. Conventionally, in order to reduce this problem, the arc tube was processed with a drawdown (narrow processing).
The process includes drawing, cutting, and cutting of the seal portion.

FIG. 2 is a diagram showing an example of the configuration of a conventional metal halide lamp in which a neck portion is formed by drawing at both ends of an arc tube. In Fig. 2, 101 indicates neck portions 1 at both ends.
02, electrodes 103 made of tungsten are fixed to sealing parts 104 at both ends of the arc tube 101, and a halide is sealed together with mercury and argon gas.

A molybdenum foil 105 for hermetically sealing the electrode 103 is embedded in a sealing part 104 at the base of the electrode 103, and a lead wire 106 is connected to the end of the molybdenum foil 105 to seal the sealing part. 104.

[Problems to be Solved by the Invention] By the way, in order to prevent deterioration of color characteristics and decrease in efficiency in low-wattage lamps, when constructing a metal halide lamp using an arc tube having neck portions at both ends, In the manufacturing process, a separate process of narrow machining or drawing is required to form the uneven portion, which complicates the manufacturing process and increases costs.

The present invention was made in order to solve the above-mentioned problems in the conventional manufacturing method of metal halide lamps.The present invention eliminates the need for a separate process for forming the neck part, and manufactures the arc tube of metal halide lamps in a simple process. The purpose is to provide a manufacturing method.

[Means and effects for solving the problem] In order to solve the above-mentioned problems, the present invention provides a method for manufacturing an arc tube for a metal halide lamp having apertures at both ends. The process involves holding one end of the glass tube with a movable chuck and the other end with a fixed chuck, heating a part of the glass tube between the two chucks while rotating the glass tube with both chucks, and the movable chuck. a step of moving the glass tube material toward the fixed chuck side to form a thickened portion in the heated glass tube material portion, and forming a spherical or spheroidal bulb portion forming portion and the bulb portion forming portion around the thickened portion of the glass tube material. The arc tube of a metal halide lamp is manufactured using a process in which molding molds having constricted neck forming portions are placed at both ends of the glass tube material, and high pressure gas is introduced from the open end of the glass tube material to perform blow molding.

By using the blow molding process using the above molding die, a spherical or spheroidal valve part and constricted neck parts disposed at both ends of the valve part are simultaneously formed in one process. Therefore, it is possible to easily manufacture an arc tube for a metal halide lamp having a constricted neck portion without increasing the number of manufacturing steps.

[Example] Examples will be described below. Figures 1 to 1) are preliminary manufacturing process diagrams illustrating an embodiment of the method for manufacturing an arc tube of a metal halide lamp according to the present invention. First, as shown for the first prisoner, a quartz glass tube 1 with one end sealed is prepared, and both ends of the glass tube are supported by a pair of chucks 2 and 3. One chuck 2 of the pair of chucks 2 and 3 is configured to be able to move toward and away from the other chuck 3, and the other chuck 3 is fixed in position. Then, while rotating the glass tube material 1 with the chuck 2.3, the burner 4 placed between the chuck 2.3
5, a portion of the glass tube 1 between the chucks 2 and 3 is heated.

Next, as shown in FIG. 1, one movable chunk 2 is moved in a direction approaching the other chuck 3, which is fixed in position, to form a thickened portion 6 in the heated portion of the glass tube material 1. .

Next, the rotation of both chucks 2.3 is stopped, and as shown in FIG. A mating mold 7 having a portion 7b and a glass tube material holding portion 7c connected to the constricted neck portion forming portion 7b,
It is arranged around the meat pocket 6. Then, high pressure gas 8 such as nitrogen or argon is introduced through the opening 1a of the glass tube 1, and the glass tube 1 has the mating mold 7 placed thereon.
The heated meat pocket 6 is inflated, and a valve part 10 having constricted neck parts 9 at both ends is simultaneously formed by blow molding.

Finally, by removing the matching mold 7 and cutting the side pipe parts 11 on both sides of the valve part 10, leaving a predetermined dimension,
Constricted neck portions 9 at both ends as shown in FIG.
A double-end type arc tube 12 is obtained, which includes a bulb portion 10 having the following characteristics.

In the above manufacturing process, the inner diameter of the constriction neck portion forming portion 7b of the mating mold 7 is at least 1
It is necessary to make the dimensions smaller than the outer diameter by 2.5% or less. This is because if the dimensions are made smaller than that, when the mating molds 7 are engaged from above and below, the glass wall of the glass tube material will protrude outside of the mating molds 7, and the molds 7 will not mesh accurately, and the molds will not be formed into the specified shape. This is because it will not be possible.

For the same reason, the wall thickness of the glass tube 1 should be 2.0 mm or less, and the moving distance of one movable chuck 2 to form the thickened portion should be 25% or less of the outer diameter of the glass tube I. is preferred.

〔Effect of the invention〕

As explained above based on the embodiments, according to the present invention, by using a blow molding process using a mold, a spherical or spheroidal valve part and a constricted neck arranged at both ends thereof are formed. Therefore, an arc tube of a metal halide lamp having a constricted neck portion can be easily manufactured without increasing the number of manufacturing steps.

[Brief explanation of the drawing]

Figures 1 to ■) are diagrams showing the manufacturing process for explaining an embodiment of the method for manufacturing the arc tube of the metal halide lamp according to the present invention, and Figure 2 is a diagram showing the manufacturing process for a conventional low-wattage metal halide lamp. FIG. In the figure, 1 is a quartz glass tube, 2 is a movable chunk, 3 is a fixed-position chuck, 4 and 5 are burners, 6 is a meat pocket, 7 is a mating mold, 8 is a high-pressure gas, and 9 is a constriction neck. 10 is a bulb part, 11 is a side tube part, and 12 is an arc tube.

Claims (1)

[Claims] 1. In a method for manufacturing an arc tube for a metal halide lamp having apertures at both ends, a quartz glass tube with one end sealed is held by a movable chuck at one end and a chuck at a fixed position at the other end, A process of heating a part of the glass tube between the two chucks while rotating the glass tube with the two chucks, and moving the movable chuck toward the fixed chuck to form a thickened portion in the heated portion of the glass tube. A molding die having a spherical or spheroidal bulb forming part and constricted neck forming parts at both ends of the bulb forming part is placed around the thickened part of the glass tubing, and the glass tubing is opened. A method for manufacturing an arc tube for a metal halide lamp, comprising the step of blow molding by introducing high pressure gas from the end.