JPH0261420B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a heating device for a glass tube used, for example, when molding a small U-shaped glass tube for a fluorescent lamp.

[Technical background of the invention and its problems]

When automatically forming a U-shaped fluorescent lamp glass tube 1' as illustrated in FIG. 1, it is necessary to heat the bent portion to a softening temperature. For this reason, in the past, means have been adopted to facilitate uniform heating, such as using a furnace or heating the glass tube with a burner while rotating it.

However, when a furnace is used, it is difficult to heat a desired area accurately and uniformly, especially if the heating range is small, such as when heating a part of a small glass tube. Furthermore, when attempting to automate bending by heating locally using a burner, it is often impossible to heat the glass tube uniformly, making automation difficult.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a glass tube heating device that can uniformly heat a desired part of a small glass tube.

[Summary of the invention]

The gist of the present invention is to include a heating burner that is provided on the lower surface of a heated portion of a glass tube and blows a flame from the lower side of the glass tube, and a flame guide that is provided on the upper surface of the glass tube. The flame guide is provided with a recess having a size and shape that surrounds the heated portion of the glass tube and is open on the lower side, and a ceiling wall of the recess is provided with a recess for allowing the flame to escape upward. This is due to the formation of flame escape holes.

According to the above configuration, since the flame of the heating burner rises so as to wrap around the heated part of the glass tube,
The part to be heated, that is, the part to be bent, can be heated uniformly over the entire circumference. Moreover, since the area surrounded by the flame guide can be heated intensively, the desired area can be accurately heated even with a small glass tube.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. Figure 2 shows an outline of the glass tube forming apparatus, and in the figure 1 shows the state before bending a soft glass tube with a tube diameter of 8 to 18 mm used for a fluorescent lamp into a U-shape. There is. The glass tube 1 is supported substantially horizontally by chuck portions 3 and 4 at both ends, which constitute a part of the bending mechanism 2.

A heating burner 5 is located near the center of the lower surface of the glass tube 1. The heating burner 5 blows out flame upward and heats the glass tube 1 from below. Further, the heating burner 5 can be moved horizontally by a burner drive mechanism 6.

Further, a flame guide 7 is located on the upper surface side of the glass tube 1, that is, facing the upper surface of the heating burner 5, and this flame guide 7 can be moved up and down by a drive mechanism 8. The flame guide 7 is made of a non-thermally conductive (thermally insulating) material such as carbon, and can surround the heated portion of the glass tube 1, as illustrated in FIGS. 3 and 4. It has a recess 9 which has a size and shape and is open on the lower surface side, and flame escape holes 10 are formed through the ceiling wall of the recess 9 to allow the flame to escape upward. In this embodiment, the inner surface shape of the ceiling wall of the recess 9 is approximately ∧-shaped so that the flame escape holes 10 are the highest.

The flame guide 7 and the heating burner 5 constitute a glass tube heating device.

Further, as a preferable example, an auxiliary burner 11 is installed below the heating burner 5. This auxiliary burner 11 has glass tubes 18,1
The gas sent from 9 and 20 is combusted to heat the glass tube 1 from below with a desired flame shape and strength.

On the other hand, the glass tube bending mechanism 2 is configured as follows. That is, in Fig. 2, 22,2
3 is a movable arm, and these arms 22, 23
are rotatable about shafts 24 and 25 in synchronization with each other. Drive gears 26, 27 are provided on the shafts 24, 25, and these gears 26, 27 mesh with a rack 28. The rack 28 can be driven vertically in the drawing by a drive mechanism 29.

Furthermore, chucks 3 and 4 are provided at the distal ends of the movable arms 22 and 23 to hold the openings 1a and 1a at both ends of the glass tube. The chuck parts 3 and 4 are the openings 1a and 1a of the glass tube.
At least one of the chuck parts 3 and 4 has an air supply port (not shown) for feeding compressed air into the inside of the glass tube 1. ) and a blow hose 38 for air supply.

Further, on the side of the glass tube 1, a U
A guide 40 is provided to maintain the distance m (see FIG. 1) when bending into a letter shape. This guide 40 can be moved by a drive mechanism 41 from the position shown in FIG. 2 to just above the portion of the glass tube 1 to be bent.

Next, the operation of the glass tube forming apparatus will be explained. The glass tube 1 carried by a transport mechanism (not shown) is supported horizontally by the chuck parts 3 and 4, and the drive mechanisms 6 and 8 are driven to move the heating burner 5 and flame guide 7 forward. , each fourth
The glass tube 1 is heated by being positioned as shown in the figure.

During this heating, since the heated portion of the glass tube 1 is located within the recess 9 of the flame guide 7 as shown in FIG. 4, the flame blown from below surrounds the heated portion. Flows upward, flame escape hole 1
Leaving from 0... Therefore, the portion to be heated, that is, the portion to be bent, can be heated accurately and substantially uniformly over the entire circumference. Moreover, since it is possible to provide a slight temperature difference between the lower surface side and the upper surface side of the glass tube 1 in the figure, that is, the outside and inside of the bend, it is also possible to obtain a temperature distribution suitable for bending.

After heating to a predetermined temperature after a certain period of time has elapsed, the heating burner 5 and the flame guide 7 retreat to a position where they do not interfere with the bending process described below, and the guide 40 for maintaining the distance moves forward. Next, while feeding compressed air into the glass tube 1 through the blow hose 38, the drive mechanism 29 is driven to move the movable arm 2.
Rotate and raise 2 and 23. As a result, the glass tube 1 is bent into a U-shape. During this time, the auxiliary burner 11 is constantly emitting a flame, which preheats the glass tube 1 and prevents the temperature of the heated portion from decreasing when the glass tube 1 is bent. Therefore, by combining uniform heating by employing the flame guide 7 and performing air blowing, it is possible to correctly bend the material into the desired shape.

As described above, according to the glass tube heating device consisting of the heating burner 5 and the flame guide 7, the portion of the glass tube 1 to be bent can be uniformly heated.
It is extremely suitable for bending small glass tubes (for example, lead glass tubes with an outer diameter of 10 mm and a length of about 100 mm). Furthermore, according to the glass tube forming apparatus shown in the above embodiment, there is no need for a forming mold, and there is no need to rotate the glass tube while heating it with a burner, so the apparatus is not large-scale and can be implemented at low cost. There is also the advantage of being able to do so.

FIG. 5 shows a modification of the flame guide 7, in which a recess 9 having a rectangular cross section is adopted, and a slit-shaped flame escape hole 10 is formed through the ceiling wall of the recess 9. . Even if such a modified example is used, substantially the same effects as those of the above embodiment can be achieved.

In carrying out the present invention, the shapes and structures of heating burners, flame guides, recesses, flame escape holes, etc., and the strength of the flame may be modified in various ways without departing from the gist of the present invention. Needless to say, it can be implemented by changing it to . Further, the present invention can be applied to soft glass tubes, hard glass tubes, quartz glass tubes, and the like.

〔Effect of the invention〕

As mentioned above, according to the present invention, even a small glass tube can be uniformly heated at a desired part, and the structure does not become complicated, so it plays a very important role in automatically forming small glass tubes. .

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, FIG. 1 is a perspective view of a glass tube after molding, FIG. 2 is a schematic perspective view of a molding device, and FIG. 3 is a perspective view of a flame guide. , FIG. 4 is a schematic side view showing the relationship between the flame guide and the heating burner, and FIG. 5 is a perspective view showing a modification of the flame guide. 1...Glass tube, 1'...Glass tube after molding,
5...Heating burner, 7...Flame guide, 9...Recess, 10...Flame escape hole.

Claims (1)

[Scope of Claims] 1. A heating burner provided on the lower surface side of a heated portion of a glass tube and blowing a flame from the lower side of the glass tube, and a flame guide provided on the upper surface side of the glass tube, This flame guide is provided with a recessed portion having a size and shape that surrounds the heated portion of the glass tube and is open on the lower side, and a flame escape hole is provided in the ceiling wall of this recessed portion to allow the flame to escape upward. A glass tube heating device characterized by forming a 2. The heating device for a glass tube according to claim 1, wherein the inner surface of the ceiling wall of the recess has a substantially ∧ shape such that the flame escape hole is highest.