JP2009292681A - Apparatus for forming glass tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for forming glass tubes which prevents a drop of the volatile component in a molten glass from dropping onto the molten glass. <P>SOLUTION: The apparatus is constituted of a muffle furnace 11 which has a sleeve 20 and an opening 15a formed on the top thereof, a feeder 17 which has an orifice 16 for flowing out a molten glass 40, wherein the molten glass is formed with the metal frame 31 arranged along the inner wall 15a1 of the opening and the orifice 16 is provided from the opening 15a in the muffle furnace 11 and is faced to the side of the base part 20a of the sleeve 20 so that the molten glass 40 winds around the sleeve, and a frame-like shade 30 which has engagement pieces 32 being formed by a metal frame 31 with the upper edge 31a of the opening, troughs 33 and 34 surrounding the inner and outer circumferences of the bottom edge 31b and receiving drops evaporated from the molten glass 40, and a drain 36 to drop from a portion of the troughs avoiding the sleeve. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a Danner type glass tube forming apparatus.

  In order to form a glass tube used for an envelope such as a fluorescent lamp, it is generally manufactured by a Danner type glass tube forming apparatus. The glass tube forming device flows molten glass onto a rotating sleeve placed in an inclined position in a muffle furnace, winds the molten glass around the sleeve, pulls it while flowing down on the sleeve, and blows the molten glass at the tip of the sleeve by blowing air blown into the sleeve. A glass tube having a predetermined diameter is formed while maintaining the tubular shape.

  The muffle furnace keeps the periphery of the sleeve at a high temperature, for example, 1000 ° C. or more, and has a heat source such as a gas burner at the bottom. While the molten glass passes through the muffle furnace and is processed, some of the glass components volatilize and the furnace is in a saturated vapor state, condensing in the relatively low temperature part of the muffle furnace wall and forming a liquid layer. It is generated and flows as a droplet and falls. For example, borosilicate glass produces boric anhydride droplets.

When the sleeve shaft that rotationally supports the sleeve is at a low temperature, droplets are generated on the shaft and flow onto the sleeve and enter the molten glass. This hinders the production of a homogeneous glass tube by forming portions with unevenness and different refractive indexes in the molded glass. In order to prevent this, it has been proposed to form a stepped portion in the sleeve base (see Patent Document 1).
JP-A-11-180724

  Droplets are also generated on the upper wall of the muffle furnace and fall from an unexpected position onto the surface of the molten glass on the sleeve immediately below, causing the above-mentioned disadvantages. However, there has been no effective means for preventing the generation of droplets and dropping onto molten glass.

  The present invention provides a glass tube forming apparatus that eliminates the above-mentioned disadvantages and prevents the drop of volatile component droplets of molten glass.

  The present invention is a rotatable sleeve formed of a cylinder attached to a rotary drive machine with a sleeve shaft on the base side with the tip side inclined downward, a muffle furnace containing the sleeve and forming an opening in the upper part, A feeder having an orifice through which molten glass flows out, the orifice being disposed in the muffle furnace from the opening, facing the base side of the sleeve, and the molten glass being wound around the sleeve; and the opening The frame is formed of a metal frame disposed along the inner wall, and the frame has an engaging element that is engaged with the opening at the upper edge, and the melting and the lower edge of the frame wrap around the inner periphery and the outer periphery. A drain that drops by volatilization from the glass, and that drops the droplet by avoiding the sleeve that is formed in a part of the bottle and is located below A frame-like shade having, thereby obtaining a glass tube forming device comprising comprising a.

  The inside of the muffle furnace is filled with saturated steam of glass volatile components, and the components selectively aggregate in a relatively low temperature portion in the furnace. The sleeve shaft connected to the rotary drive outside the muffle furnace is at a low temperature, and the gas in the furnace is easily leaked from the opening where the orifice for flowing the molten glass flow is inserted. There is a possibility that the temperature near the part becomes low. Since the sleeve shaft is attached to the side wall, it is relatively easy to remove even if droplets aggregate, but if the droplets are generated on the upper surface of the furnace, it is not easy to remove.

  The present invention attaches a metal frame-like shade to the opening and positively collects the droplets that cause the saturated vapor to agglomerate in the shade. The drain extends away from the sleeve axis so as to avoid the sleeve portion immediately below. The droplet is dropped by the above.

  This prevents droplets from adhering to the molten glass wound around the sleeve, and produces a glass tube with good quality that does not cause irregularities on the surface of the glass tube to be formed, and does not cause partial refractive index fluctuations. be able to.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
1 to 6 show Embodiment 1 of the present invention. As shown in FIG. 1, the glass tube forming apparatus 10 includes a muffle furnace 11. The muffle furnace 11 forms a cylindrical inner chamber with a refractory wall, and a gas burner 12 is disposed in the lower portion so that the inner chamber can be heated to 1000 ° C. or higher. The inner chamber is formed in an inclined manner, and a sleeve 20 made of a fire-resistant rotating cylinder is arranged in an inclined manner along the center. The sleeve 20 is held by a sleeve shaft 21 that penetrates the side wall 13 on the upper side of the muffle furnace, and can be rotated by a rotary driving machine 22 connected to the sleeve shaft. The sleeve shaft 21 is formed of a hollow tube and communicates with the inside of the sleeve 20 from the sleeve base 20a to the sleeve tip 20b and opens at the tip. A blow air generator 23 is attached to the rotary drive side of the sleeve shaft, and air is blown into the sleeve shaft.

  A molten glass tube outlet 14a formed into a tubular shape is opened in the side wall 14 on the lower side of the muffle furnace, and the soft glass 41 formed into a tubular shape is drawn down from the sleeve 20 and drawn out. Here, the soft glass means molten glass adjusted to a viscosity suitable for glass tube forming. The soft glass 41 is cooled by outside air and gradually formed into a glass tube having a predetermined diameter. The sleeve base 20a side of the upper part of the muffle furnace is constituted by a flat furnace wall and forms a flat portion 15. The flat portion 15 is provided with openings 15a having a rectangular pattern. The opening 15a is for inserting the orifice 16 flowing out of the molten glass 40 and bringing it into proximity to the sleeve base 20a. The periphery of the orifice is covered with a cylindrical refractory 16a. The orifice 16 is provided in the lower part of the feeder 17 which stores the molten glass taken out from the melting furnace (not shown).

  As shown in FIG. 2 and FIG. 3, it was formed in a convex pattern as viewed from the top so as to circulate along the inner wall 15a1 of the opening 15a so as to cover the inner wall almost in line with the rectangular opening 15a. A cylindrical frame-shaped shade 30 is disposed. The shade 30 is preferably in close contact with the inner wall 15a1 of the opening 15a. 4 to 6, the frame-like shade 30 is formed of a refractory metal frame 31 made of Pt, W, Mo, Nb, Au, Ti, Ru, Pd, or an alloy thereof, and has one edge. That is, a plurality of projecting pieces that can be bent at intervals are formed on the upper edge 31 a, and these become the engaging elements 32. Reference numeral 38 denotes a stopper for clamping the furnace wall in the opening together with the engaging element 32. The other edge, that is, the lower edge 31b is formed in an inclination descending toward the convex portion 35 of the convex pattern, and has a U-shaped cross-section U-shaped cross-section 33 that receives a later-described liquid droplet so as to go around the inner and outer circumferences of the edge. , 34 are provided. The inner peripheral flange 33 presses the edge of the frame 31, and the outer peripheral flange 34 is attached by welding a refractory metal frame having an L-shaped cross section to the edge edge as shown. These wrinkles serve as a flow path for liquid droplets and flow toward the convex portion 35. The convex portion 35 forms a drain 36 by bending the edge 34a of the outer peripheral ridge 34 in the opposite direction, that is, downward, in order to drop the liquid flowing from the inner and outer peripheral ridges 33, 34. A notch 31c is provided at the frame edge of the bent portion so that the liquid droplets on the inner peripheral ridge 33 flow to the outer peripheral ridge 34 through the notch 31c. As a result, the inner and outer droplets can freely fall from the drain 36. The drain 36 is disposed at a position away from the sleeve in a direction crossing the sleeve shaft 20c so that the droplet to be dropped falls away from the sleeve 20 just below the frame-shaped shade 30 and the molten glass wound around the sleeve.

  As shown in FIG. 2, the orifice 16 is close to the sleeve base 20a, for example, 50 mm to 100 mm, and the cylindrical refractory 16a covering the orifice is also close to the sleeve base 20a. Therefore, the cylindrical refractory 16a may protrude from the lower edge of the frame-shaped shade 30. When droplets are generated here, they cannot be received by the frame-shaped shade 30. Therefore, in consideration of the case where droplets are condensed on the cylindrical refractory 16a, the circular bottom surface has a circular plane. A refractory metal receiving tray 37 having a tear drop pattern with a protruding portion as a portion is attached. The protrusion 37a side of the tear drop pattern is inclined downward so that the protrusion 37a serves as a drain so that the liquid droplet falls from the drain while avoiding the sleeve 20. The protrusion 37a corresponds to the position of the opening 15a and the drain 36 of the frame-shaped shade 30 so that the orifice 16 with the tray 37 attached to the muffle furnace is smoothly inserted into the opening 15a. I have to.

  The operation of this embodiment will be described. While the muffle furnace chamber is heated, the rotary drive 22 and the blow air generator 23 are operated, and the sleeve 20 is rotating, the molten glass 40 supplied from the feeder flows out of the orifice 16 and forms a ribbon. It is wound around the sleeve base 20a. The molten glass flows down toward the sleeve tip 20b while being fused to each other on the surface of the rotating sleeve, and is drawn out from the molten glass tube outlet 14a of the muffle furnace while forming a bag with blow air at the tip. The glass tube 41 drawn out from the glass tube forming apparatus in this way is still in a soft state, but is cooled by the outside air while moving on a roller (not shown), cured in a horizontal state, and cut to a predetermined size. It becomes a glass tube product according to the application.

  The volatile component of the molten glass in the muffle furnace is saturated vapor, which mainly condenses around the frame-shaped shade 30 and the opening to generate droplets, and drops around the opening. Since it becomes a collector and the frame-like shade 30 tends to be low in temperature, condensation of saturated steam can be concentrated on the shade, and condensation on other wall surfaces is eased. Droplets collected by the inner and outer peripheries 33 and 34 of the lower edge 31b of the shade and the drain 36 are dropped on the molten glass of the sleeve 20 while avoiding the molten glass of the sleeve 20, and dropped on the molten glass. To prevent.

  When a droplet is generated on the surface of the cylindrical refractory 16a covering the orifice 16, it is received by the receiving tray 37 and dropped on the molten glass by using the protruding portion 37a as a drain. Although only a frame-shaped shade 30 is attached, a considerable effect can be obtained.

(Embodiment 2)
As shown in FIG. 7, the present embodiment has a frame-like shade structure in which the inner peripheral flange 33 of the lower edge 31b from the orifice surface 16b is arranged on the sleeve 20 side. The same reference numerals as those in the first embodiment denote the same parts, and redundant description will be omitted. The opening 15b of the muffle furnace is formed into a circular shape having a slightly larger diameter coaxial with the cylindrical refractory 16a of the orifice, and the orifice 16 is inserted and arranged in the muffle furnace. The frame-like shade 40 is attached as a circular pattern along the inner wall of the opening. The inner diameter of the inner peripheral rod 33 of the frame-shaped shade 40 is set to be smaller than the outer diameter of the cylindrical refractory 16a so that droplets generated on the peripheral wall of the cylindrical refractory 16a can be received. As in the first embodiment, a part of the outer peripheral ridge 34 is extended and bent downward to form the drain 36a, and the droplet is dropped to a position avoiding the sleeve 20 positioned below and the molten glass wound around the sleeve. This arrangement is useful when the distance between the orifice 16 and the sleeve base 20a is relatively large.

  Although the present invention has been described above by way of the embodiment, the shape of the opening for arranging the orifice of the muffle furnace can be arbitrarily changed depending on the shape of the feeder, and the shape of the frame-like shade 30 attached to the opening is also convex. Not only the pattern but also the shape of the opening can be modified. The saucer 37 is the same. Furthermore, the connector of the frame-shaped shade may be a flange shape.

1 is a schematic cross-sectional view of Embodiment 1 of the present invention. FIG. 2 is a partially enlarged schematic sectional view taken along line AA in FIG. 1. The bottom view of the orifice vicinity of FIG. The perspective view of the frame-shaped shade of Embodiment 1. FIG. Sectional drawing which follows the BB line of FIG. Sectional drawing which follows the CC line | wire of FIG. The partially expanded schematic sectional drawing of Embodiment 2 of this invention.

Explanation of symbols

10: Glass tube forming apparatus 11: Muffle furnace 15: Flat part 15a: Opening part 16: Orifice 16a: Cylindrical refractory 17: Feeder 20: Sleeve 20a: Sleeve base part 20b: Sleeve tip part 21: Sleeve shaft 22: Rotation drive Machine 23: Blow air generator 30: Frame-shaped shade 31: Frame 31a: Upper edge 31b: Lower edge 32: Engagement element 33: Inner peripheral flange 34: Outer peripheral flange 34a: Edge 35: Convex portion 36: Drain 37: Sauce plate 37a : Projection

Claims (5)

A rotatable sleeve formed of a cylinder attached to a rotary drive machine with a sleeve shaft on the base side with the tip side inclined downward;
A muffle furnace containing the sleeve and forming an opening at the top;
A feeder having an orifice through which molten glass flows out, the orifice being disposed in the muffle furnace from the opening and facing the base side of the sleeve so that the molten glass is wound around the sleeve;
The frame is formed of a metal frame disposed along the inner wall of the opening, and the frame has an engaging element that engages with the opening at the upper edge, and circulates to the inner and outer circumferences of the lower edge of the frame. A frame-shaped shade having a drain that receives droplets generated by volatilization from the molten glass, and having a drain that is formed by a part of the bottle and that avoids the sleeve located below and drops the droplets;
A glass tube forming apparatus comprising:   The glass tube forming apparatus according to claim 1, wherein the engaging element of the frame-shaped shade is bent outward from the opening.   The glass tube forming apparatus according to claim 1, wherein a frame of the frame-shaped shade is a convex pattern.   The glass tube forming apparatus according to claim 1, wherein the frame-shaped shade is in close contact with the opening.   The bottom of the feeder is circular, and has a teardrop-shaped droplet receiving tray having a protruding portion on the bottom, and the protruding portion of the receiving plate drops the droplet while avoiding the sleeve located below. The glass tube forming apparatus according to claim 1, wherein the glass tube forming apparatus is formed to have a length to be used as a drain.

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