JP2010013297A - Glass producing method and glass producing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass producing method and a glass producing apparatus in which the occurrence of striae can surely be suppressed. <P>SOLUTION: The glass producing apparatus 10 is provided with: a flow path 90 through which molten glass MG flows out; a heating device 20 for heating the flow path 90; and a mold 60. The heating device 20 is provided with: a cover member surrounding the tip 91 of the flow path 90 to keep a certain distance; and a communicating structure for communicating an inside space 29 surrounded by the cover member with the outside air at the lower end 26 of the cover member and a place 27 except the lower end 26. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a glass manufacturing method and a glass manufacturing apparatus.

  A general molten glass supply apparatus includes a holding container for containing molten glass, and a flow path is provided in the holding container. Thereby, the molten glass in a holding | maintenance container flows out out of a flow path.

  Here, when the temperature of the flow path is low, the molten glass located in the vicinity of the inner wall of the flow path is severely cooled, while the degree of cooling of the molten glass located in the central portion away from the inner wall is light. As a result, the temperature distribution in the molten glass flowing out from the flow path becomes non-uniform, and there is concern about the occurrence of striae. In addition, there is a concern that the optical characteristics of the glass product to be manufactured are deteriorated due to the generation of glass crystals.

Therefore, a measure is taken to heat the flow path by radiant heat by disposing a cover member around the flow path and heating the cover member with a heater (see, for example, Patent Document 1).
JP 2008-110880 A

  However, in the supply device shown in Patent Document 1, depending on the composition of the molten glass, striae occurring in the obtained glass molded body (for example, preform) may not be sufficiently suppressed.

  This invention is made | formed in view of the above situation, and it aims at providing the glass manufacturing method and glass manufacturing apparatus which can suppress generation | occurrence | production of striae more reliably. Specifically, the present invention provides the following.

  The present inventors surprisingly, by communicating the internal space of the cover member, which has been considered to be important to enhance the obstructive property in consideration of heating efficiency and the like, rather than communicating with the outside air at a plurality of locations, The inventors have found that the occurrence of striae is suppressed, and have completed the present invention. Specifically, the present invention provides the following.

(1) A glass manufacturing method in which molten glass flows out from the tip of a flow path to manufacture glass,
The molten glass encloses the front end of the flow path with a cover member, and the inner space surrounded by the cover member is in communication with outside air at a position excluding the lower end of the cover member and at the lower end. The glass manufacturing method that flows out.

  (2) The glass manufacturing method according to (1), wherein the lower end of the cover member is arranged at the same height as the end of the flow path or below the front end of the flow path.

  (3) The glass manufacturing method according to (1) or (2), wherein the cover member has an opening provided at a place other than the lower end, and the internal space and the outside air are communicated with each other through the opening.

  (4) The glass manufacturing method according to (3), wherein an opening ratio of the opening is set to 0.5 to 30% with respect to a surface area of a surface of the cover member surrounding a tip of the flow path.

  (5) The glass manufacturing method according to any one of (1) to (4), including a step of heating the cover member.

  (6) As the molten glass, a glass containing one or more elemental components selected from the group consisting of alkali metal elements, B, F, P, Ti, Nb, Sb, Te, and Bi is used. (5) The glass manufacturing method in any one.

  (7) An optical element manufacturing method including a procedure for precision press-molding the glass manufactured by the glass manufacturing method according to any one of (1) to (6).

(8) A heating device that heats the flow path through which the molten glass flows,
A cover member capable of separating and surrounding the tip of the flow path;
A communication apparatus comprising: a communication structure that communicates an internal space surrounded by the cover member with outside air at a portion other than one end of the cover member and the one end.

  (9) The heating device according to (8), wherein the cover member has an opening provided in a portion excluding one end of the cover member, and the internal space and the outside air are communicated with each other by the opening.

  (10) The heating device according to (9), wherein an opening ratio by the opening is 0.5 to 30% with respect to a surface area of a surface of the cover member surrounding a tip of the flow path.

  (11) The heating apparatus according to any one of (8) to (10), further including a heating unit that heats the cover member.

(12) A flow path through which the molten glass flows out, the heating device according to any one of (8) to (11), and a molding die,
The said shaping | molding die is a glass manufacturing apparatus which shape | molds the molten glass which flows out out of the said flow path.

  (13) The glass manufacturing apparatus according to (12), wherein a front end of the flow path is located at the same height as one end of the cover member or on the other end side from the one end.

  (14) An optical element manufacturing apparatus comprising: the glass manufacturing apparatus according to (12) or (13); and a precision pressing apparatus that precisely presses the glass manufactured by the glass manufacturing apparatus.

  According to the present invention, the occurrence of striae can be more reliably suppressed by communicating the internal space surrounded by the cover member with the outside air at a plurality of locations.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in description of each embodiment other than 1st Embodiment, the same code | symbol is attached | subjected about what is common in 1st Embodiment, and the description is abbreviate | omitted.

<First Embodiment>
FIG. 1 is a perspective view of a heating apparatus 20 according to the first embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of a glass manufacturing apparatus 10 including the heating apparatus 20 of FIG. The glass manufacturing apparatus 10 includes a heating device 20, a flow path 90, and a mold 60. Each component will be described in detail below.

  The flow path 90 is a tubular member, and its base 93 is connected to a molten glass manufacturing apparatus (not shown). The molten glass supplied from this molten glass manufacturing apparatus passes through the base 93 and is dropped from the tip 91 to the lower mold 60. The mold 60 has a configuration in which a porous body 61 is provided inside a mold container 63, and a glass molded body such as a preform is molded from molten glass on the porous body 61. In the present embodiment, the gas supplied from the gas path 65 is ejected from the porous body 61 to the molten glass, and the preform floats up from the porous body 61, so that a preform with reduced contamination can be formed. The deterioration of the porous body 61 can be suppressed.

  A heat insulating member 53 having excellent heat resistance is wound around the base portion 93, and cooling of the molten glass flowing through the base portion 93 is suppressed. The heating device 20 is disposed below the heat insulating member 53, and the heating device 20 heats the tip 91 of the flow path 90 extending from the end of the heat insulating member 53.

  Here, the heating device 20 includes a skirt 21, and the skirt 21 surrounds the tip 91 of the flow path 90 in a spaced manner. Thereby, when the skirt 21 is heated by the heating unit 30 described later, the tip 91 is warmed by the heat radiated from the skirt 21, so that the occurrence of striae due to the temperature reduction of the molten glass can be suppressed. .

  Specifically, the skirt 21 in the present embodiment has a cylindrical skirt main body 22, and a base portion 93 of the flow path 90 is inserted from the upper end 27 side of the skirt main body 22, and a tip 91 is an inner part of the skirt main body 22. It is arranged in the direction. And the burner 31 of the heating part 30 is arrange | positioned on the outer side of the skirt main body 22, and when the outer surface 223 of the skirt main body 22 is heated by high temperature with the flame which these burners 31 generate | occur | produce, it will tip from the inner surface 221 of the skirt main body 22 to the front-end | tip. A large amount of heat is radiated to 91. The configuration of the heating unit 30 is not particularly limited to the illustrated one, but it is preferable that the outer side of the skirt main body 22 be surrounded like a ring burner and the outer surface 223 of the skirt main body 22 be heated substantially uniformly. Alternatively, the skirt body 22 itself may be configured to generate heat. Further, the shape of the skirt is not limited to a cylindrical shape, and can be appropriately selected from shapes such as a quadrangular column and an elliptical column according to the heating location, the layout of the entire apparatus, and the like.

  In this embodiment, an upper collar portion 23 is provided at the upper end 27 of the skirt body 22, and a lower collar portion 25 is provided at the lower end 26. A burner 31 is provided between the upper collar portion 23 and the lower collar portion 25. Has been placed. Thereby, the fluctuation | variation of the flame which the burner 31 produces is suppressed, and heating efficiency can be improved.

  The present invention is characterized in that the internal space 29 surrounded by the cover member is communicated with the outside air at a place other than the lower end 26 and the lower end 26 of the cover member. The upper end 27 communicates with outside air. Specifically, the lower end 26 of the skirt 21 has an open port 40b, and the internal space 29 communicates with the outside air through the open port 40b. Further, the skirt 21 in the present embodiment is further provided with anchoring devices 28a and 28b, and these anchoring devices 28a and 28b extend in a direction away from the skirt body 22 (above the upper end 27 in FIG. 1). It is latched by the shielding part 51. As a result, the upper end 27 of the skirt body 22 is separated from the shielding part 51, and the opening 40a connected to the outside air is formed through the gap CL. As a result, the internal space 29 is communicated with the outside air also at the upper end 27 of the skirt body 22. The The above skirt 21, the shielding part 51, and the clearance CL constitute a cover member.

  In the configuration in which the internal space communicates with the outside air only at the lower end of the cover member as in the conventional case, the radiant heat from the skirt body 22 and the vaporized component of the molten glass flowing out from the tip 91 are highly accumulated in the internal space. It is considered that the internal space (for example, pressure, temperature, composition) tends to be in an abnormal state far away from the outside air, and the internal space in such an abnormal state may adversely affect the molten glass flowing out from the tip 91. On the other hand, in the glass manufacturing apparatus 10 of the present embodiment, the exchange of the internal space 29 and the outside air is promoted through the opening 40a and the opening 40b (a gas flow as shown in FIG. 2 is assumed). As a result, the internal space is unlikely to become abnormal, and the striae can be more reliably suppressed. However, the above operation is a guess and is not limited to this.

  The lower end 26 of the cover member (here, the skirt 21) is disposed at the same height as the tip 91 of the flow path 90 or below the tip 91 as in the present embodiment in that the occurrence of striae can be further suppressed. In other words, the tip 91 is preferably located at the same height as the lower end 26 of the skirt 21 or on the upper end 27 side of the lower end 26. In particular, the lower end 26 is more preferably disposed below the front end 91. Since the molten glass MG flowing out from the tip 91 is surrounded by the skirt 21 and heated sufficiently, it is estimated that the occurrence of striae is suppressed, but the present invention is not limited to this.

  In the case where the lower end 26 is disposed below the tip 91, if the interval becomes excessive, the fall distance of the molten glass from the tip 91 to the mold 60 becomes long. As a result, the molten glass MG is deformed from a desired shape by a drop impact. There is a risk. Therefore, the lower end 26 is preferably arranged at a position 15 mm or less below the tip 91, more preferably 12 mm or less, and most preferably 10 mm or less, depending on the composition of the molten glass and the viscosity at the time of molding. It is. Moreover, it is preferable that the lower end 26 is arrange | positioned in the position below 2 mm rather than the front-end | tip 91 at the point which can suppress a striae more preferably, More preferably, it is 4 mm or more, Most preferably, it is 6 mm or more.

  In the present embodiment, as described above, the opening 40a and the opening 40b function as a communication structure, and the opening 40a is connected to the outside air by the gap CL. Such an embodiment is preferable in that it can ensure a large opening area of the opening 40a and simplify the configuration, but is not limited thereto. For example, as shown in FIG. 3, an opening 40 a </ i> A may be provided in a part of the shielding part 51, and the opening 40 a </ b> A may be communicated with outside air through a pipe 43. Although only two openings 40aA are shown in FIG. 3, the present invention is not limited to this, and the pipe 43 penetrates the heat insulating member 53A from the shielding part 51A. is not.

  In addition, the openings 40a and 40aA shown in the above embodiment are arranged at the upper end 27 of the skirt body 22, and this aspect is preferable in that the internal space 29 and the outside air can be exchanged efficiently and the number of parts can be reduced. However, it is not limited to this. For example, embodiments as shown in FIGS. 4 and 5 are also included in the present invention.

  4, the skirt 21B is divided into an upper skirt body 22Ba and a lower skirt body 22Bb, and an opening 40Ba is formed between the upper skirt body 22Ba and the lower skirt body 22Bb, and the opening 40Ba. Is connected to the outside air by a gap CL between the lower collar portion 25Ba of the upper skirt body 22Ba and the upper collar portion 23Bb of the lower skirt body 22Bb.

  In this aspect, it is desirable to dispose the burner by removing the position of the gap CL in order to prevent the flame from entering the internal space from the gap CL. The heating unit 30B shown in FIG. The upper burner 31Ba is disposed on the outer periphery, and the lower burner 31Bb is disposed on the outer periphery of the lower skirt body 22Bb. Thereby, heating can be sufficiently performed while suppressing the flames of the upper burner 31Ba and the lower burner 31Bb from entering the internal space from the gap CL.

  Further, as shown in FIG. 5, if the extension portion 43C is provided in the opening 40Ca and the extension portion 43C is extended to a portion where the flame of the upper burner 31Ca and the lower burner 31Cb is not affected by the flame, Intrusion into the space can be prevented more reliably.

  The mode illustrated in FIGS. 4 and 5 is merely one mode for providing the opening at a place other than the upper end 27, and is not limited thereto. For example, in FIG. 4, the upper skirt main body 22Ba and the lower skirt main body 22Bb are divided as separate bodies. However, the present invention is not limited to this, and the skirt main body 22 shown in FIG. May simply be formed. In FIG. 5, the opening 40 </ b> Ca is provided around the entire tip 91. However, the present invention is not limited to this, and the opening 40 </ b> Ca may be provided only at a part around the tip 91.

  In any configuration, the opening ratio by the openings 40a and 40aA is preferably 0.5 to 30% with respect to the surface area of the surface surrounding the tip 91 of the flow path 90 in the cover member. If the aperture ratio is too low, the suppression of striae may be insufficient. On the other hand, if it is excessive, striae will easily occur due to the temperature drop of the internal space 29, and the glass that flows out will be lost. This is not preferable because there is a possibility that another problem of transparency will occur. The upper limit of the aperture ratio is more preferably 25%, and most preferably 20%. Further, the lower limit of the aperture ratio is more preferably 2%, and most preferably 5%. Here, the surface area of the surface surrounding the tip 91 of the flow path 90 in the cover member refers to the area of the virtual surface including the opening of the cover member, the gap CL, and the portion through which the flow path 90 is inserted. Corresponds to a portion indicated by a two-dot chain line in FIGS.

  According to the glass manufacturing method using the above glass manufacturing apparatus 10, when using molten glass of various compositions, striae can be suppressed with high probability, but as the molten glass, alkali metal elements, B, F, It is preferable to use a glass containing one or more elemental components selected from the group consisting of P, Ti, Nb, Sb, Te, and Bi. A glass containing a component that easily volatilizes from a molten glass tends to cause striae, but the production method of the present invention is effective for such a glass. In particular, the wrinkle-like striae that are characteristically generated when glass containing at least a P component (phosphoric acid type) is used can be extremely effectively suppressed by the glass manufacturing method of the present invention.

  Since the glass produced in the present embodiment is sufficiently suppressed in occurrence of striae, it can be suitably used for an optical element. Specifically, an optical element can be produced by precision press-molding glass. The glass manufacturing apparatus and the precision press apparatus used for precision press molding constitute an optical element manufacturing apparatus.

[Manufacture of molten glass]
Molten glass containing each component was produced with the composition shown below. That is, a phosphoric acid glass containing 48% P ₂ O ₅ by mass%, ₂ % LiO ₂ and 3% Sb ₂ O ₃ is melted at a melting temperature of 1050 ° C. in a melting pot made of platinum or a platinum alloy, After clarifying and stirring and mixing, the temperature was controlled to 810 ° C., which is a temperature suitable for molding.

[Outflow and molding of molten glass]
The produced molten glass is dropped from the tip 91 of the flow path 90 made of platinum or platinum alloy to the forming die 60 disposed 8 to 20 mm below the tip 91 using the glass manufacturing apparatus 10 shown in FIGS. Then, the preform was molded while floating on the mold 60. The dimensions of the skirt 21 and the flow path 90 are as shown in Table 1.

  Here, in the case where each cover member is used, an opening 40a formed by a gap is provided between the shielding part 51 and the upper collar part 23, and the width of the gap CL is set to 0 through the length of the mooring tools 28a and 28b. Changed between 6.9 mm. With the change in the width of the gap CL, the calculated aperture ratio was 0 to 18.7%. Based on the values, the aperture ratios are classified into four groups. As shown in Table 1, as the aperture ratio increases from the O group having no openings, the A group, the B group, and the C group did. For each of Examples 1 to 3, the striae appearance range and the density observed in the preforms molded with each aperture ratio group were scored, and this score was added to the number of preforms to obtain “strange defects”. The “number of points” is shown in FIG. The number of preforms for evaluation was 8 for each aperture ratio group. In addition, scoring is performed based on the reference | standard of Table 2, and the point number of A group of Example 2 is an average value.

  As shown in FIG. 6, in any of the first to third embodiments, the wrinkled striae may be drastically reduced under the condition where the gap CL exists, compared to the condition where there is no gap CL (the opening 40a does not exist). I understood. Thereby, it was confirmed that the occurrence of striae can be more reliably suppressed by flowing out the molten glass in a state in which the inner space 29 is communicated with the outside air at the location excluding the lower end 26 of the cover member and the lower end 26. .

  Further, when each embodiment is compared by paying attention to the aperture ratio A group, as shown in FIG. 7, the lower end 26 of the cover member is disposed below the front end 91 of the flow path 90, thereby generating striae. It was found that can be suppressed more reliably.

The above effects are not limited to the above phosphoric acid-based glass, but the phosphoric acid-based glass containing 12% P ₂ O ₅ , 25% AlF ₃ and 20% CaF ₂ in mass%, Thus, it was confirmed that the same effect was exhibited even with a bismuth glass containing 81% Bi ₂ O ₃ and 3% TeO ₂ .

It is a whole perspective view of the heating device concerning one embodiment of the present invention. It is a longitudinal cross-sectional view of a glass manufacturing apparatus provided with the heating apparatus of FIG. It is a longitudinal cross-sectional view of the glass manufacturing apparatus which concerns on one modification of this invention. It is a longitudinal cross-sectional view of the glass manufacturing apparatus which concerns on another modification of this invention. It is a longitudinal cross-sectional view of the glass manufacturing apparatus which concerns on another modification of this invention. It is a graph which shows the degree of striae in the glass manufactured using the glass manufacturing apparatus concerning one example of the present invention. It is a graph which shows the degree of striae in the glass manufactured using the glass manufacturing apparatus concerning one example of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Glass manufacturing apparatus 20 Heating apparatus 21 Skirt 22 Skirt main body 221 Inner surface 223 Outer surface 23 Upper collar part 25 Lower collar part 26 Lower end 27 Upper end 29 Internal space 30 Heating part 31 Burner 40a Opening part 40b Opening part 43 Pipe 51 Shielding part 53 Thermal insulation Member 60 Mold 61 Porous body 63 Mold container 65 Gas channel 90 Channel 91 Tip 93 Base CL Clearance

Claims (14)

A glass production method for producing molten glass by flowing molten glass from the tip of a flow path,
The molten glass encloses the front end of the flow path with a cover member, and the inner space surrounded by the cover member is in communication with outside air at a position excluding the lower end of the cover member and at the lower end. The glass manufacturing method that flows out.   The glass manufacturing method of Claim 1 which arrange | positions the lower end of the said cover member at the same height as the front-end | tip of the said flow path, or the downward direction rather than the front-end | tip of the said flow path.   The glass manufacturing method according to claim 1, wherein the cover member has an opening provided at a place excluding the lower end, and the internal space and the outside air are communicated with each other through the opening.   The glass manufacturing method of Claim 3 which makes the aperture ratio by the said opening part 0.5-30% with respect to the surface area of the surface surrounding the front-end | tip of the said flow path among the said cover members.   The glass manufacturing method in any one of Claim 1 to 4 which has the process of heating the said cover member.   The glass containing at least one elemental component selected from the group consisting of alkali metal elements, B, F, P, Ti, Nb, Sb, Te, and Bi is used as the molten glass. The glass manufacturing method as described.   The optical element manufacturing method which has the procedure of carrying out precision press molding of the glass manufactured by the glass manufacturing method in any one of Claim 1 to 6. A heating device that heats a flow path through which molten glass flows,
A cover member capable of separating and surrounding the tip of the flow path;
A communication apparatus comprising: a communication structure that communicates an internal space surrounded by the cover member with outside air at a portion other than one end of the cover member and the one end.   The heating apparatus according to claim 8, wherein the cover member has an opening provided at a portion excluding one end of the cover member, and the internal space and the outside air are communicated with each other by the opening.   The heating apparatus according to claim 9, wherein an opening ratio by the opening is 0.5 to 30% with respect to a surface area of a surface of the cover member surrounding a tip of the flow path.   The heating apparatus according to any one of claims 8 to 10, further comprising heating means for heating the cover member. A flow path through which molten glass flows, the heating device according to any one of claims 8 to 11, and a mold.
The said shaping | molding die is a glass manufacturing apparatus which shape | molds the molten glass which flows out out of the said flow path.   The glass manufacturing apparatus according to claim 12, wherein a front end of the flow path is located at the same height as one end of the cover member or on the other end side from the one end.   An apparatus for manufacturing an optical element, comprising: the glass manufacturing apparatus according to claim 12 or 13; and a precision press apparatus for precisely pressing glass manufactured by the glass manufacturing apparatus.

Images