JPH01220338A - Manufacture of glass bulb for tubular bulb - Google Patents

Abstract

PURPOSE:To simplify the process and improve the quality of a product by forming metal molds so as not to generate portions required to be cut off after molding in the process to mold the heated and softened glass with the metal molds. CONSTITUTION:A heated and softened large-diameter glass tube 1 is press- molded by split metal molds 3 and 3. A continuous wall 8 is formed between two legs of the U-shaped discharge path 7 of the glass bulb 6 to hold the strength, but the upper end section 13 of the continuous wall 8 must be cut off from the continuous wall 8 to seal mounts 14 and 14. A punching projection 20 and a punching hole 1 are formed on the metal molds 3 and 3 so that the upper section 13 of the continuous wall 8 does not appear. The cutting process of the upper section 13 is not required and the deformation and strength deterioration of this portion resulting from the cutoff is prevented as compared with the case that this upper section 13 has a glass wall and must be cut off.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method of manufacturing a glass bulb used in a U-shaped or serpentine fluorescent lamp.

(Prior art) As a method for manufacturing a fluorescent lamp, the applicant has disclosed
The method disclosed in Japanese Patent Publication No. -95828 is proposed.

The manufacturing method disclosed in the above publication heats and softens a glass tube with a relatively large diameter, and then molds the softened glass tube into a pair of molded surfaces that correspond to a bent discharge path, such as a U-shape. By pressing with a mold, a bulb having a curved discharge path as described above is molded.

This method has the advantage that a valve with little variation in wall thickness can be easily obtained and is highly suitable for mass production.

The above publication describes a technique for forming the curved discharge path and at the same time creating a continuous wall that connects the walls of adjacent discharge paths when a softened glass tube is pressed with a pair of molds. By forming such a continuous wall, even if an external force is applied that brings the walls of adjacent discharge channels closer together, the resistance of the continuous wall will prevent contact and damage to the bulb. It has the advantage of increased mechanical strength.

A conventional case in which the manufacturing method disclosed in the above publication is specifically implemented will be explained based on FIGS. 10 to 17.

In the figure, l is a large-diameter straight glass tube as a material to be formed into a glass bulb, and this large-diameter glass tube l is used in the burner 2... as shown in Fig. 10. Everything is heated evenly.

When the large diameter glass tube 1 is in a softened state, a pair of molds 3, 3
Press by. These molds 3, 3 are substantially symmetrical to each other, and as shown in FIG. 11, each has, for example, a substantially U-shaped molding surface 4 and a partition wall 5 in the center.

The softened large-diameter glass tube 1 is pressed by the collision of these molds 3°3, and in this state, as shown in FIG. 12, when pressurized air is sent into the large-diameter glass tube 1, the glass tube l
is blow molded, thus obtaining the glass bulb 6 shown in FIG.

The glass bulb 6 shown in FIG. 13 has a U-shaped discharge path 7, and a continuous wall 8 formed by the partition wall 5 is provided between adjacent walls of the discharge path. Note that a large diameter open end 9 remains at the end as a remnant of the large diameter glass tube l.

The glass bulb 6 is annealed by being heated by a heater 10, 10 or the like in a heat treatment furnace shown in FIG. This annealing process removes thermal distortion during molding by the mold 3.3.

After this, the glass bulb 6 is cut along the cutting line A-- shown in FIG.
A is cut, thereby cutting off the large-diameter opening end 9, thereby forming end openings 11.11 which become both ends of the discharge path 7, as shown in FIG. .

Next, in the glass bulb 6 shown in FIG. 16, the continuous wall 8 in the vicinity of the openings 11.11 at both ends is cut out using a cutter or the like (not shown). As a result, as shown in FIG. 17, a cutout portion 13 (discontinuous portion-slit) is formed at the end of the continuous wall 8.

Now, to explain the reason why the cutout 13 is formed in the continuous wall 8, electrode mounts 14.14 as shown in FIG. 17 are sealed to the openings 11.11 at both ends. It is necessary to heat and soften the peripheral walls of the openings 11.11 at both ends, and if the continuous wall 8 remains here, it is not possible to uniformly heat the openings 11.11 at both ends over the entire circumference. , temperature distribution becomes uneven, local thermal distortion occurs, and cracks are more likely to occur.

On the other hand, if the cutout portion 13 as described above is provided, the openings 11.11 at both ends are separated from each other, so that uniform heating can be performed and the occurrence of cracks can be prevented.

Moreover, a plurality of such glass bulbs B are arranged side by side,
One end opening 11 of one glass bulb B and the other end opening 11 of the other glass bulb B are connected to each other by a connecting member so as to be airtightly conductive to each other, and a serpentine shape having a large number of bent parts as a whole is formed. A light lamp may also be made by adding a discharge path. In such a case, if the continuous wall 8 exists on the same plane as the opening 11, it will interfere with the joining of the connecting members, making it difficult to achieve an airtight connection. In order to avoid such problems, it is effective to provide the cutout portion 13.

(Problems to be Solved by the Invention) The conventional method shown in FIGS. 10 to 17 above employs a method of cutting off using a cutter to form the cutout portion 13.

However, with the method of mechanically cutting with a cutter, since the object is glass, many invisible microscopic racks are generated, which later grow into large racks when sealing the mount 14゜14. This may cause defects or leaks.

On the other hand, when forming the cutout portion 13 in the continuous wall 8, it is also possible to burn it out by blowing it out with a burner flame without using a cutter, but such a method would cause the openings 11 and 11 at both ends to melt. This causes problems such as the shape of the opening being deformed and the mount 14.14 not being able to be sealed.

The present invention aims to provide a method of manufacturing a glass bulb for a tube without generating the above-mentioned rack when forming the cutout, and also without causing distortion of the openings at both ends.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides an advantage in that when a softened glass tube is press-molded by a pair of molds, an end portion of a continuous wall formed between adjacent walls of a discharge channel is It is characterized in that an opening is formed as a portion to be resected by punching out.

(Function) According to the method of the present invention, when a softened glass tube is press-molded using a pair of molds, an opening is formed as a portion to be cut, so a particularly troublesome process for forming the cut portion is eliminated. This reduces the number of steps and makes manufacturing easier, and since an opening is formed in the glass bulb as the part to be cut when it is softened, there is no possibility of slight deformation of the rack or opening. occurrence is prevented.

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

Although FIGS. 1 to 8 are shown in the order of steps, steps and members that may be the same as those shown in FIGS. 10 to 17 described above are given the same numbers and their explanations will be omitted.

In this embodiment, a punching protrusion 2o and a punching hole 21 into which the protrusion 2o fits are formed at the respective ends of the partition walls 5, 5 formed at the center of the pair of molds 3, 3, respectively. ing. As shown in FIG. 4, these punching protrusions 20 and punching holes 21
When the two abut against each other, the punched protrusion 20 enters the punched hole 21.

A large-diameter glass tube l that has been heated and softened in advance by a burner 2 shown in FIG. 1 is pressed by the pair of molds 8 and 3 shown in FIG. When these pair of molds 3゜3 are brought into contact with each other as shown in Fig. 3, the molding surfaces 4, 4 of these pair of molds 3, 3 form a nearly U-shaped discharge path as shown in Fig. 5. 7 is formed, and a continuous wall 8 is formed between the walls of the adjacent discharge paths between the partition walls 5, 5 of the molds 3, 3, and the partition walls 5, 5 are formed at the ends of the continuous wall 8. The punched protrusion 20 formed in 5 enters the punched hole 21 to form an opening 22 as a portion to be cut.
will be formed.

That is, the pair of molds 3, 3 press and mold the softened large-diameter glass tube 1, but when the glass tube 1 is still in a softened state, the punching protrusion 20 enters the punching hole 21. The end of the continuous wall 8 is pierced, thereby forming an opening 22 as a portion to be excised.

In addition, when pressing with the molds 3, 3, pressurized air is sent into the large diameter glass tube 1 to perform blow molding, as in the past, and a large diameter open end 9 remains at the end. ing.

The glass bulb 6 thus formed is subjected to a glazing treatment such as deburring by heating and softening the area around the opening 22 using a burner 25 shown in FIG. 5 or the like.

Next, the glass bulb 6 is annealed by being heated by a heater 10, 10 or the like in a heat treatment furnace shown in FIG. This annealing process removes the overall thermal distortion of the glass bulb B that occurred during molding using the molds 3, 3. Furthermore, after the bulb 6 has cooled, it is cut along the cutting line A-A shown in FIG. 7, thereby cutting off the large-diameter opening end 9.

By this cutting, as shown in FIG. 8, end openings 11 and 11 are formed, which are both ends of the discharge path 7, and at the same time, the ends of the opening 22, which is the part to be cut, are opened, so it is similar to the conventional method. A cutout portion 13 (discontinuous portion-slit) is formed at the end of the continuous wall 8.

According to the method of this embodiment, the punching protrusions 20 and the punching holes 21 are formed in the partition walls 5.5 of the pair of molds 3.3, and the large diameter The glass tube l is pressed to form the U-shaped discharge path 7 and the continuous wall 8. At the same time, the punched projection 20 and the punched hole 21 form an opening 22 as a portion to be cut. 13 is not required, and therefore the number of steps is reduced and work efficiency is improved.

Moreover, the opening 22 as the part to be resected is a large-diameter glass tube l.
Since it is molded while it is being heated and softened, there are fewer cracks and distortions.

In other words, since a conventional cutter is not used, there is no occurrence of a slight rack, and due to the sealing of the mounts 14.degree. 14, there is no crack growth, and sealing failures and leaks are eliminated.

Furthermore, compared to the case where the flame is blown out by the force of the burner flame, thermal deformation of the opening ti does not occur, so the mount 14 can be reliably sealed.

In the above embodiment, the punching protrusion 20 and the punching hole 21 are integrally formed in the pair of molds 3, 3.
, 8, by pressing the large diameter glass tube l heated and softened.
At the same time as forming a U-shaped discharge path 7 and a continuous wall 8,
Although the punching protrusion 20 and the punching hole 2I form an opening 22 as a portion to be cut, the present invention provides a method for forming each of a pair of molds 3.3 as another embodiment shown in FIG. Through holes 30.30 are formed in the partition walls 5, 5, and after the pair of molds 3, 3 are brought into contact with each other, a punching rod 31 of a different structure is inserted into these through holes 30.30. so as to break through the end of the continuous wall 8,
In this way, the opening 22 as the portion to be removed may be formed.

That is, the device for forming the opening 22 as the part to be resected is not limited to one that is integrally formed with the pair of molds 3, 3, and therefore, the device that forms the opening 22 as the part to be resected is not limited to one that is integrally formed with the pair of molds 3, 3. The device for forming the opening 22 is not limited to molding, and as shown in the other embodiments described above, the device for forming the opening 22 may be separate from the molds 3, 3, and its timing may also be the same as the discharge path 7. and after the continuous wall 8 is formed.

Further, the cross-sectional shape of the discharge path 7 is not limited to a perfect circle, but may be a flat shape such as an ellipse or an ellipse.

〔Effect of the invention〕

As explained above, according to the present invention, when a softened glass tube is press-molded using a pair of molds, an opening is formed as a portion to be cut, so a particularly troublesome process for forming the cut portion is not necessary. In addition to reducing the number of steps and making manufacturing easier, an opening is formed in the glass bulb as the part to be cut when the glass bulb is softened, so there is no possibility of slight deformation of the rack or opening. This has the advantage of preventing the occurrence of such problems.

[Brief explanation of the drawing]

1 to 8 show an embodiment of the present invention, FIG. 1 is an explanatory diagram of the heating process, FIG. 2 is an explanatory diagram of the suppression molding process,
Figure 3 is an explanatory diagram of the pressing process, and Figure 4 is IV- in Figure 3.
5 is a perspective view of the molded bulb, 6 is an explanatory diagram of the annealing process, 17 is an explanatory diagram of the cutting process, 8 is an explanatory diagram of the mount sealing process, FIG. 9 shows another embodiment of the present invention, and is a sectional view corresponding to FIG. 4, and FIGS. 10 to 17 are explanatory diagrams showing the conventional method in the order of steps. l... Large diameter glass tube M 3... Mold, 4... Molding surface, 5... Partition wall, B... Glass bulb, 7...
Discharge path, 8... Continuous wall, 13... Excision part, 20...
- Punching projection, 21... Punching hole, 22... Opening of the part to be resected. Applicant's Representative Patent Attorney Takehiko Suzue No. 4YJ Figure 3 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9. Figure 11 Figure 14 Figure 15

Claims (1)

[Claims] The curved discharge path is produced by heating and softening a large-diameter straight glass tube and pressing the softened glass tube with a pair of molds having molding surfaces corresponding to the curved discharge path. and a method for manufacturing a glass bulb for a tube, in which a bulb having a continuous wall between the walls of adjacent discharge channels is formed, and a cutout is formed at the end edge of the continuous wall, wherein the pair of molds A glass bulb for a tube, characterized in that when a softened glass tube is press-molded, an end portion of the continuous wall formed between the walls of adjacent discharge channels is punched out to form an opening as a portion to be cut. manufacturing method.