JPH01246153A - Forming of glass tube - Google Patents

Abstract

PURPOSE:To provide the title forming process so designed that the opening end of a glass tube is heated and softened while rotating the glass tube with horizontal attitude and the tube axis as a center, and a rotational forming roller is pressed on the softened part, thereby improving the accuracy of the opening diameter. CONSTITUTION:A large-diameter glass tube 10 and a fine-diameter glass tube 11 each made of hard glass (e.g. quartz) are horizontally and coaxially arranged at an interval so as to face each other. Thence, the tube 10, with tube axis as the center, is made to rotate in the direction of arrow A and the opening end is heated and softened using a gas burner 12; concurrently with this, a rotational forming roller 20, with the central axis 21 as the center, is made to rotate in the direction of arrow B, also to ascend in the direction of arrow C to press on the opening end of said tube 10 to effect diameter reduction. At this time, the circumferential surface of the lower part of the roller 20 is immersed in the water 23 in a tank 22 with the virtical motion of said roller 20. The reduced diameter end of the tube 10 and the end stopping the rotation, both ends being attached together and welded. The tube 11 is then drawn in the direction of the tube axis at a rate of ca. 2mm/s to trim the resulting joint, thus accomplishing the objective forming of glass tube.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for forming an open end of a glass tube used for a tube or the like.

(Prior art) For example, in a single-sealed halogen light bulb, as shown in FIG. 3. These internal lead wires 3, 3 are connected to metal foils 5, 5 made of molybdenum or the like sealed to a crush sealing part 4 formed at one end of the valve l. Note that the metal foil 5.5 is attached to the base 6 attached to the crushing sealing part 4 via an external lead wire (not shown).
It is connected to the.

In such a valve I, an exhaust pipe 7 is connected to the opposite end of the collapsible pair 1 part 4. The inside of the valve is exhausted through this exhaust pipe 7, halogen gas is supplied into the valve through this exhaust pipe 7, and then the exhaust pipe 7 is sealed off.

Since the exhaust pipe 7 is formed sufficiently smaller than the diameter of the bulb l, it is usually formed into a large diameter glass pipe lO as shown in FIG.
It is constructed by joining a small diameter glass tube 11 to the end of the tube. In this case, the end of the large-diameter glass tube 10 must be made thin enough to connect with the small-diameter glass tube 11.

Conventionally, as shown in FIG. 11, a large-diameter glass tube 10 serving as a bulb is held in a vertical position with its tube axis substantially vertical, and the large-diameter glass tube IO is rotated around the tube axis. The upper end opening was heated and softened with a gas burner 12. Normally, a glass tube has the property of contracting in diameter when its peripheral wall is uniformly heated and softened. Therefore, when the upper end opening of the large-diameter glass tube 10 is heated and softened, the diameter decreases as shown in FIG. 12. . Thereafter, as shown in FIG.
Welded to the opening of the reduced diameter end of 0, large diameter glass tube 1
A method of joining a glass tube 11 with a glass tube 11 having a small diameter was adopted.

(Problem to be Solved by the Invention) However, when heating and softening the large-diameter glass tube IO while maintaining it in a vertical position as described above, this softened portion 15
However, as shown in FIG. 13, the center may sag due to gravity. In order to prevent this, if we try to increase the rotational speed and utilize the centrifugal force, it is difficult to set the rotational speed, so if the speed becomes too high, the centrifugal force will be too strong and the softened portion 15 will appear as shown in Figure 14. There is a problem with the diameter expanding into a trumpet shape.

For this reason, it is easy to produce defective products in which the hole diameters of the openings 14 are uneven, the radius of curvature of the shoulder R is large, or the center of the opening is shifted.

Therefore, there is a problem in that the end of the large-diameter glass tube 10 cannot be reliably connected to the small-diameter glass tube 11 that becomes the exhaust pipe connected thereto.

The present invention aims to provide a method for forming a glass tube, which allows the end shape and opening diameter of the glass tube to be finished with high precision and is also excellent in workability.

[Structure of the Invention] (Means for Solving the Problems) The present invention maintains a glass tube with the tube axis in a substantially horizontal position, and heats the end portion of the glass tube while rotating the glass tube around the tube axis. It is characterized in that the opening diameter of this end portion is narrowed by softening it and pressing a rotary molding roller against this end portion from a direction perpendicular to the tube axis.

(Function) According to the method of the present invention, since the glass tube is heated and softened while maintaining the tube axis in a substantially horizontal position, the softened portion does not sag toward the center, and moreover, the softened portion is Because it is forcibly narrowed down, it is easy to find the center position,
The opening diameter can be regulated with high precision.

(Example) The present invention will be described below with reference to an example shown in FIGS. 1 to 8.

As shown in FIG. 1, a large-diameter glass tube 10 and a small-diameter glass tube 11 made of hard glass such as quartz or aluminosilicate glass are supported so that their tube axes are horizontal, and spaced coaxially from each other. vs.

Directed. The large diameter glass tube IO is rotated in the direction of arrow A around the tube axis. During this rotation, the open end of the large diameter glass tube IO is heated and softened by the gas burner 12.

When the open end of the large diameter glass tube 10 is heated and softened, the second
The open end of the large-diameter glass tube IO is pressed by a rotary forming roller 20 shown in FIGS. 5 to 5 to forcibly reduce its diameter. That is, the rotary molding roller 20 is rotated in the direction of arrow B around the central axis 21, and is moved upward in the direction of arrow C to form a tube at the softened open end of the large diameter glass tube 10. It is designed to push this open end by hitting it from a direction perpendicular to the axis.

In this case, the lower outer peripheral surface of the rotary molding roller 20 is immersed in water 23 of the water tank 22, and this water tank 22 moves up and down together with the rotary molding roller 20.

When the outer circumferential surface of the rotary molding roller 20 presses the softened opening end of the large diameter glass tube 10, the rotary molding roller 20 receives heat from the high temperature glass tube 10 and is thermally deteriorated. The life of the glass tube 10 is improved by immersing it in the water 23 of 22 and cooling it, and the silica of the glass tube 10 adheres to the outer peripheral surface of the rotary molding roller 20, which causes the shape of the opening end of the large diameter glass tube 10 to be irregular. Therefore, the attached silica is washed away by immersing it in the water 23 of the water tank 22.

Furthermore, when the outer circumferential surface of the rotary molding roller 20 presses the softened open end of the large diameter glass tube 10 as described above, the rotational speed v1 of the rotary molding roller 20 is relatively higher than that of the large diameter glass tube 10.
The rotation speed is set to be greater than the rotation speed v2 of 0 (V1≧v2).

This occurs, for example, when the rotational speed vl of the rotary molding roller 20 is smaller than the rotational speed v2 of the large diameter glass tube 10 (Vl<
V2)% As shown in FIG. 4, a sag 24 occurs at the front corner of the rotary molding roller 20 and the large-diameter glass tube 10, and this sag 24 bites into the roller 20, causing the glass to break. The finish of the molding surface becomes poor. In comparison, if the rotational speed v1 of the rotary molding roller 20 is set relatively higher than the rotational speed v2 of the large-diameter glass tube 10 (v1≧v2), the occurrence of dripping 24 is reduced, and even if the dripping Even if this occurs, as shown in FIG.
This is generated at the corner of the large-diameter glass tube IO after it is rotated, and since it adheres to the glass and is carried away, it does not impair the finish of the molding surface.

In this way, when the outer peripheral surface of the rotary forming roller 20 presses the softened open end of the large diameter glass tube 10, the softened open end of the large diameter glass tube IO is reduced in diameter as shown in FIG. Ru.

The opening diameter d1 of this reduced end is the diameter of the narrow glass tube 11.
(dl < d2).

Next, the reduced-diameter end of the large-diameter glass tube 10 and the end of the small-diameter glass tube 11 are heated and softened with a burner (not shown), and the rotation of the large-diameter glass tube IO and the small-diameter glass tube 11 is stopped. Both ends are brought into contact.

At this time of abutment, the narrow diameter glass tube 11 is joined to the large diameter glass tube 10 by pressing the reduced diameter end of the large diameter glass tube 10 by about the same thickness as the end of the small diameter glass tube 11 . As a result, as shown in FIG.
O and the small diameter glass tube 11 are welded together.

Immediately after this welding, as shown in FIG. 8, move the small diameter glass tube 11 slowly (2g
v/see) to slightly stretch the welded area. This adjusts the shape of the joint, and at this time air or inert gas is fed from the other end of the large-diameter glass tube 10 as shown by arrow E.

By supplying the gas in this manner, the gas flows from the large diameter glass tube 10 side toward the small diameter glass tube 11, thereby air cooling the welded joint between the large diameter glass tube 10 and the small diameter glass tube 11 from the inner side. I will do it. Therefore, in conjunction with pulling the small-diameter glass tube 11 in the direction of the arrow, it is cooled from the inside to promote hardening of the glass, so the shape and wall thickness of the corner at the joint should be set to a predetermined state. In addition, the curvature of the outer R portion can be set to a predetermined shape.

By doing so, glass tubes with different diameters as shown in FIG. 10 can be obtained.

Therefore, according to the above manufacturing method, the large diameter glass tube 1
0 is heated and softened while holding the tube axis in a substantially horizontal position, so the softened portion does not sag toward the center. Moreover, the rotation molding roller 20 allows the large-diameter glass tube 10 to be
The opening diameter can be regulated with high precision because the heated and softened end is forcibly narrowed down to reduce the diameter.

Further, the lower outer peripheral surface of the rotary molding roller 20 is connected to a water tank 22.
Since the rotary molding roller 20 is immersed in water 23 of
3, it is possible to extend the life of the glass tube 10, and even if the silica of the glass tube 10 adheres to the outer peripheral surface of the rotary molding roller 20, it is washed away by the water 23 of the water tank 22, so that the suppressing surface is kept clean. Become.

Then, the rotational speed v1 of the rotary molding roller 20 is set relatively higher than the rotational speed v2 of the large diameter glass tube 10 (vl≧v
2) Since it is solid, the finish of the glass molding surface is improved.

Note that the width X of the rotary molding roller 20 may be set as follows.

That is, as shown in FIG. 6, if D...outer diameter d1 of the large diameter glass tube 10...opening diameter t...wall thickness r...radius of curvature of the shoulder, then (2πr/ 4) +a-b a+r+t-(D/2)-(dl/2)b-(r
(π-2)+D-di-2t) /2xmb-r-
t Therefore, x= (r (π-4) +D-dl-4
It should be set to tl/2.

It should be noted that the present invention is not limited to manufacturing tube bulbs; in short, it may be used to form a glass tube with the end processed as shown in FIG. 6 from the glass tube shown in FIG. 1. .

[Effects of the Invention] As explained above, according to the method of the present invention, the glass tube is heated and softened while being held so that the tube axis is in a substantially horizontal position, so that the softened portion does not sag toward the center. Since the softened portion is forcibly squeezed using a rotary molding roller, the opening diameter can be regulated with high accuracy, and a highly accurate product can be obtained.

[Brief explanation of the drawing]

Figures 1 to 8 explain one embodiment of the present invention, with Figure 1 being an explanatory diagram of the heating process, Figures 2 to 5 being explanatory diagrams of the diameter reduction process, and Figure 6 being an illustration of the diameter reduction process. FIG. 7 is an explanatory diagram of the welding process, and FIG. 8 is an explanatory diagram of the shaping process. Figure 9 and the following are detailed explanations of the present invention. Figure 9 is a side view of a halogen light bulb, Figure 10 is a cross-sectional view of a glass tube with different diameters, and Figure 11 is a diagram explaining a conventional manufacturing method. Explanatory diagram of heating process 1. FIG. 12 is an explanatory diagram of the diameter reduction step, and FIGS. 13 and 14 are explanatory diagrams showing defective end shapes, respectively. ■... Arc tube bulb, 2... filament, 7...
...Exhaust pipe, lO...Large diameter glass tube, 11...Small diameter glass tube, 12...Gas burner, 20...Rotational molding roller. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 1! 4 @ Figure 5 Figure 6 Figure n Figure 7 Section 8 Figure 9 ○ Figure 12

Claims (1)

[Claims] In a forming method in which the opening end of a glass tube is heated and softened to reduce its opening diameter, the glass tube is held with the tube axis in a substantially horizontal position, and the glass tube is centered around the tube axis. A glass characterized in that the opening end is heated and softened while being rotated, and the opening diameter of the opening end is narrowed by pressing a rotary molding roller against the opening end from a direction intersecting the tube axis. How to form a tube.