JP2004099404A - Method of forming glass tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming glass tubes, by which the side parts of parallelly arranged two or more glass tubes are airtightly melt-bonded to each other through communicating tubes without contacting and melt-bonding under pressure regardless of the internal diameter of glass tubes. <P>SOLUTION: The method of forming the glass tubes is a method for airtightly melt-bonding the side parts of parallelly arranged two or more glass tubes to each other through communicating tubes. The method comprises softening the side part of each glass tube by heating it, putting each glass tube into a mold, subjecting the glass tube to blow molding to form a projected part in the side part of the glass tube, taking the glass tube having the formed projected part out of the mold, heating the glass tube while blowing a fluid into it so as to open the projected part and to make the projected part having a partial opening part, heating the projected part having the partial opening part so as to make the projected part having a desired opening area, bringing together the peripheral edge parts of the opening parts of the projected parts to each other, and forming a communicating tube by melt-bonding the peripheral edge parts brought together. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a method for forming a glass tube, and more particularly, to a method for forming a glass tube for manufacturing a discharge lamp bulb or the like that requires a bent discharge passage.
[0002]
[Prior art]
In recent years, as a discharge lamp, a light bulb having a discharge path bent into a U-shape or an L-shape has been put into practical use because it can be downsized while achieving high light output.
In manufacturing such a discharge lamp, it is required that a glass tube having a bent discharge path can be efficiently manufactured.
[0003]
Japanese Patent Publication No. 6-45469 discloses a method of manufacturing a glass tube having a bent discharge path. Japanese Patent Publication No. 6-45469 discloses a method of forming a glass tube in which the side portions of a parallel glass tube are air-tightly connected to the outside via a communication hole. Two glass tubes are juxtaposed, a burner is inserted into each glass tube, and heated from the inner surface of the glass tube to soften the glass at the portion where the communication hole is formed. (2) A pincher head is inserted into each glass tube. (3) Remove the pincher head, insert the burner again into the glass tube, and insert the burner again into the glass tube inner surface. The welded portion is heated and melted, and the hole is opened by the wind pressure of the burner to form a communication hole. (4) The weld pool is pushed outward by the burner in the glass tube to form a joint tube.
[0004]
[Patent Document]
Japanese Patent Publication No. 6-45469 (Claim 1)
[0005]
[Problems to be solved by the invention]
However, in this method, when the inner diameter of each glass tube is small, there is a problem that the pincher head and the burner do not enter and the processing cannot be performed. Further, since the pincher head and the burner are inserted into each glass tube, there is a problem that the formation position of the discharge path is limited to a range where the tip of the pincher head or the burner can reach.
[0006]
In the prior art, a welding portion is formed by contact-welding the heat-softening portions by applying a pinch pressure.However, in a portion welded by contact while applying pressure, a pinhole may be generated in the glass. There is also a problem that the glass surface at the welded portion becomes wavy.
Further, if the contact welding is performed while applying pressure, the viscosity of the glass at the pressure welding portion increases. For this reason, it is difficult to increase the opening diameter in the step of extruding the weld pool at the welding location by a burner to the outside to form a joint pipe, and thus it is not possible to increase the wall thickness of the joint pipe. There was also a problem with strength.
[0007]
Accordingly, the present invention provides a method of forming a glass tube in which the side portions of a plurality of parallel glass tubes are hermetically welded via a communication tube without pressure contact welding regardless of the inner diameter of the glass tube. The aim is to provide a method.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, according to the invention of claim 1, there is provided a method for forming a glass tube, wherein the side portions of a plurality of parallel glass tubes are hermetically welded through a communication tube. Is heated and softened by heating, and the glass tube is put into a mold and blow-molded to form a projection on the side of the glass tube. The protrusions are opened by heating while blowing fluid into the glass tube, and the peripheries of the opened protrusions are joined together, and the joints are welded by heating to form a communication tube. A method of forming a glass tube.
Also, a method for forming a glass tube, in which the side portions of a plurality of parallel glass tubes are hermetically welded to each other through a communication tube, wherein the side portions of the glass tube are softened by heating, and the glass tube is heated. Into a mold and blow molding to form a projection on the side of the glass tube, take out the glass tube with the projection from the mold, and heat while blowing fluid into the glass tube. Thus, the projection is opened to form a partially opened projection, the partially opened projection is heated to form an opening projection having a desired opening area, and the peripheries of the opening projection are joined to each other. Are heated and welded to form a communicating tube.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be schematically described with reference to the drawings. FIG. 1 schematically shows an embodiment of the present invention, and FIGS. 2 to 4 are enlarged views thereof. The sections (a) to (i) in FIG. 1 indicate the order of steps, and the sections (a) to (i) in FIGS. 2 to 4 indicate the same step. FIGS. 1h and 1i are partial cross-sectional side views, the phases of which are changed by 90 degrees from the partial cross-sectional front views of FIGS. 1a to 1g show one glass tube, while FIGS. 1h and 1i show two glass tubes. 2B, FIG. 2C, FIG. 2D, FIG. 3E, FIG. 3F, FIG. 3G, FIG. 4H, and FIG. 4I, the cross-sectional views shown on the right side are respectively BB line, CC line, and DD line. EE, EE, FF, GG, HH, and II lines.
[0010]
In the illustrated embodiment, a discharge lamp bulb 11 in which the two glass tubes 1 are hermetically connected to the outside air from the two glass tubes 1 through a communication tube 4 serving as a discharge path as shown in FIG. However, the present invention is not limited to using two glass tubes, and a plurality of communicating tubes may be provided between a pair of glass tubes. Further, the present invention is applied not only to molding of a discharge lamp bulb but also to molding of a glass tube in general.
Further, the diameter of the communication tube 4 is not particularly limited, and any diameter is possible as long as it is smaller than the diameter of the glass tube 1. Further, in the illustrated embodiment, as shown in FIGS. 1h and 1i, the cross section of the communication pipe 4 is elliptical. However, in the present invention, the cross section of the communication pipe is not particularly limited.
[0011]
First, as shown in FIG. 1A and FIG. 2A, two bottomed tubular glass tubes 1 are prepared. As a method for manufacturing a glass tube, a known technique can be used. Usually, one end of a glass tube cut to a predetermined size is sealed with burner heating and blow pressure.
In the illustrated embodiment, a bottomed cylindrical glass tube is prepared, but a cylindrical glass tube whose end is not closed is used, and after forming a communication tube, the end of each glass tube is closed. It does not exclude doing.
Although the bottom of the illustrated glass tube has a U-shaped vertical cross section, the bottom may be flat or may be any as long as one side is sealed (if it has a bottom). The glass material (composition) of the glass tube used in the present invention is not particularly limited, and a known material such as a soft glass to a hard glass can be used. In addition, the outer diameter of the glass tube does not matter, and the inner diameter does not matter as described later.
[0012]
As shown in FIGS. 1b and 2b, the neck of such a glass tube 1 is clamped by a chuck 3, and the side of the glass tube 1 is heated by a burner 2 from the outer surface. The heating portion is a portion where the communication pipe 4 is to be formed, and the glass viscosity of this portion is increased to a level within a processable range by heating. The heating temperature may be in a temperature range in which the glass viscosity can be processed, and the temperature varies depending on the composition of the glass, but is usually about 700 to 800 ° C. The portion where the communication tube 4 is formed is not particularly limited as long as it is a side portion of the glass tube.
[0013]
As shown in FIGS. 1c and 2c, the glass tube 1 thus locally heated is put into a mold 6, and a fluid such as air is blown into the glass tube to deform the heated portion. A projection 41 is formed (FIGS. 1d and e, 2d, 3e).
The mold used here is formed with a concave portion 61 that forms a projection 41 for forming the communication tube 4.
In the discharge lamp bulb, as in the illustrated embodiment, the projection 41 (communication tube 4) is formed in a direction perpendicular to the axial direction of the glass tube 1, but the direction of formation of the communication tube is not shown in the figure. Is not limited to
For the blow molding for forming the projection 41, a known technique can be used, and the blow pressure, the blow time and the like are not particularly limited, and are appropriately selected.
In the glass tube 1 in which the projection 41 is formed in this way, the projection 41 is not open, and the projection bottom wall 411 exists.
[0014]
Next, the glass tube 1 on which the protrusion 41 is formed is removed from the mold, and the protrusion 41 is opened. In this case, when the protrusion bottom wall 411 of the protrusion 41 is heated by a burner or the like and a fluid is blown into the glass tube 1 (FIGS. 1E and 3E), the protrusion bottom wall 411 softened by the heating is blown. As a result, the projection 41 is opened to form a partially open projection 42 (FIGS. 1F and 3F). In this case, usually, the center of the projection bottom wall 411 is ruptured, and the peripheral edge of the bottom wall 411 remains.
In this case, the heating temperature varies depending on the composition of the glass, but is usually in a temperature range of about 850 ° C. Since the heating temperature is high, the air blows from the inside and there is no mold wall, the projection bottom wall 411 is ruptured. At this time, a part 412 of the projection bottom wall remains.
The blow pressure and blow time are not particularly limited, and are appropriately selected.
[0015]
Next, the protrusion bottom wall 412 remaining on the partially open protrusion 42 is removed, and the partially open protrusion 42 is completely opened. For this reason, when heating is performed by a burner or the like from the outside along the axial direction of the partially open protrusion 42 (FIGS. 1F and 3F), the thickness of the heated bottom wall 412 of the protrusion is partially increased due to surface tension. It flows to the outer periphery of the cylindrical wall 413 of the opening projection 42, and the opening projection 42 is partially opened to form the opening projection 43. In this case, the flesh of the projection bottom wall 412 is concentrated on the cylindrical wall 413, so that the cylindrical wall 413 is thickened, and the communication tube 4 of the discharge lamp 11 is strengthened.
Further, by adjusting the heating, the inner diameter of the communication hole 4 can be arbitrarily set.
The heating temperature in this case is a range in which the glass melts and the projection bottom wall 411 flows to the outer periphery of the cylindrical wall 413 due to surface tension. The temperature varies depending on the composition of the glass, but is usually 950 to 1100 ° C.
As described above, the steps shown in FIGS. 1A to 1G of the present invention need not be performed in parallel with two glass tubes. Therefore, the processing operation becomes easy.
[0016]
The two glass tubes 1 on which the opening protrusions 43 are formed are arranged so that the opening protrusions 43 face each other, the peripheral edges of the opening protrusions 43 are joined to each other, and heated by a burner or the like from the outside to open the glass tube 1. The projecting portions 43 are welded to each other to form the communication tube 4. In this case, the joint becomes gentle due to the phenomenon of surface tension due to the heating.
The heating temperature in this step is usually 950 to 1100 ° C.
[0017]
As described above, according to the present invention, the projection portion 41 is formed by heating the glass tube from the outside (FIG. 1b), placing the glass tube in a mold, and blowing fluid into the glass tube (FIG. 1c). Then, the projections 41 are heated from the outside and a fluid is blown into the glass tube (FIG. 1e) to open the projections 41 to form the opening projections 43, and the opening projections 43 are joined and welded. Things. That is, in the present invention, there is no need to insert a pincher head or a burner into the glass tube as in the prior art (Japanese Patent Publication No. 6-45469). For this reason, in the prior art, the inner diameter of the glass tube is limited, but in the present invention, the inner diameter of the glass tube is not limited.
Also, in the prior art, the communication tube can be formed only at a position where the tip of the pincher head or the burner can reach on the side of the glass tube, but in the present invention, the communication tube is formed at an arbitrary position. It is possible.
[0018]
In the above-mentioned prior art, it is necessary to seal the end of the glass tube after forming a communication hole in order to insert a burner and a pincher head into each glass tube, and to perform contact welding while applying pressure. Since the glass surface of the portion becomes wavy, it was necessary to prepare the sealing end portion and the communication hole portion with a mold as a final finish. Therefore, in the discharge lamp bulb manufactured according to the prior art, there is a problem that a parting line of a mold remains. However, in the present invention, since the burner and the pincher head are not inserted into each glass tube, it is possible to seal the end portion of the glass tube before the formation of the communication hole. Does not become wavy. Therefore, in the case where the end of the glass tube is sealed before the formation of the communication hole, it is not necessary to perform molding with a mold as a final step, and it is possible to manufacture a product without a parting line.
[0019]
【Example】
Two glass tubes made of ultraviolet transmitting glass were prepared. The glass tube had a bottomed cylindrical shape, an inner diameter of 10.5 mm, and a wall thickness of 0.7 mm.
The glass tube was heated to about 750 ° C. with a burner around a point 5 mm from the bottom, placed in a mold, and blown with 98 KPa air for 2 seconds. A concave portion having a major axis of 12 mm, a minor axis of 12 mm, and a depth of 4 mm was formed in the mold, and a projection 41 was formed.
The glass tube on which the projection 41 was formed was taken out of the mold, and the projection bottom wall 411 was heated to about 850 ° C. by a burner and air of 18.6 KPa was blown for 1.0 second. At its center was ruptured, and a partially open projection 42 was formed.
The projection bottom wall 412 of the partially opened projection 42 was heated to about 1000 ° C. by a burner to completely open the projection (long diameter 11 mm, short diameter 11 mm) to form the opening projection 43. The cylindrical wall 413 of the opening projection 43 had a thickness of 0.5 mm and a height of 3.5 mm. The peripheries of the opening projections 43 of the two glass tubes thus formed were joined to each other, and heated to about 1000 ° C. by a burner to form the communication tube 4.
[0020]
【The invention's effect】
According to the invention of claim 1, since it is not necessary to insert a pincher head or a burner into each glass tube, a communication tube can be formed even if the inside diameter of the glass tube is small, and the communication tube having an arbitrary inside diameter can be formed. Can be formed, and an arbitrary number of communication tubes can be formed at arbitrary positions.
In addition, since the communication pipe is formed without performing pressure welding, pinholes in the glass due to the pressure welding and the surface of the glass do not become wavy. If one end of the glass tube is sealed prior to the formation of the communication hole, there is no need to finally mold with a mold, and further, there is an effect that there is no parting line by mold molding.
The inside diameter of the communication tube can be adjusted by heating the burner from outside the glass tube, and a communication hole having an accurate inside diameter can be formed.
[Brief description of the drawings]
FIG. 1 shows an embodiment of the present invention, in which (a) is a partial sectional front view, (b) to (g) are partial sectional front views and transverse sectional views, and (h) and (i). ) Is a partial sectional side view and a transverse sectional view.
FIG. 2 is an enlarged view of FIGS. 1 (a) to 1 (d).
FIG. 3 is an enlarged view of FIGS. 1 (e) to 1 (g).
FIG. 4 is an enlarged view of FIGS. 1 (h) to 1 (i).
FIG. 5 is a partially sectional front view of a discharge lamp bulb formed according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Glass tube 11 Discharge lamp bulb 2 Burner 4 Communication tube 41 Projection part 411 Projection bottom wall 412 Projection bottom wall 413 Cylindrical wall 42 Partially opening projection part 43 Opening projection part 6 Mold 61 Recess

Claims (1)

A method for molding a glass tube, in which a plurality of side-by-side glass tubes are hermetically welded to each other via a communication tube,
The side of the glass tube is softened by heating,
By putting the glass tube in a mold and blow molding, a projection is formed on the side of the glass tube,
Take out the glass tube having the projection formed from the mold, blow the fluid into the glass tube, and heat it to open the projection,
A method for forming a glass tube, comprising joining the peripheries of the opened projections to each other, and welding the joined portions by heating to form a communication tube.

Images