JP2010105888A - Device for feeding molten glass and apparatus for producing glass molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for feeding molten glass where temperature falling at the edge of an outflow pipe is suppressed and to provide an apparatus and a method for producing a glass molded body. <P>SOLUTION: The device 10 for feeding the molten glass is equipped with the outflow pipe 20 to flow the molten glass out and a heating part 30 to heat the edge 23 of the outflow pipe 20. The edge 23 is covered with a cover 40 placed outside with a gap. The heating part 30 has coils 31 wound at the outer periphery of the cover 40 and a high frequency power source 33 to supply a high frequency current to the coils 31 and the edge 23 is induction-heated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for supplying molten glass.

  A method is widely known in which molten glass accommodated in a melting tank flows out through an outflow pipe to form a glass molded body. Here, in order to suppress the devitrification of the glass molded body, it is necessary to suppress the temperature drop at the tip portion where the opening of the outflow pipe is formed.

Therefore, conventionally, a mechanism for heating the tip of the outflow pipe has been developed. For example, Patent Document 1 discloses a mechanism in which a coil is wound around the outer periphery of a distal end portion of an outflow pipe, and a high frequency current is supplied to the coil to inductively heat the distal end portion.
JP 2006-143563 A

  However, in the conventional mechanism described above, the temperature drop at the tip of the outflow pipe is not sufficiently suppressed, and it may be difficult to reliably prevent devitrification of the glass molded body.

  This invention is made in view of the above situation, and it aims at providing the molten glass supply apparatus and method which can suppress the temperature fall of the front-end | tip part of an outflow pipe more, and a glass molded object manufacturing apparatus and method. To do.

  The inventors of the present invention have found that the temperature drop of the tip is significantly suppressed by induction heating of the tip under the condition that the outer periphery of the outflow pipe is covered with an interval, and the present invention is completed. It came to. Specifically, the present invention provides the following.

(1) A molten glass supply device comprising an outflow pipe for flowing out molten glass, and a heating means for heating the tip of the outflow pipe,
The tip portion is covered with a covering portion that is spaced outwardly;
The said heating means has a coil wound around the outer periphery of the said coating | coated part, and the high frequency current supply means which supplies a high frequency current to this coil, The molten glass supply apparatus which induction-heats the said front-end | tip part.

  (2) The molten glass supply apparatus according to (1), wherein the covering portion is connected to the tip portion at a predetermined distance from the tip of the outflow pipe to the base side.

  (3) The molten glass supply apparatus according to (1) or (2), wherein the covering portion extends downward from a tip of the outflow pipe.

  (4) The molten glass supply device according to (1), wherein the covering portion is connected to a distal end of the outflow pipe and has a shape that expands toward the base side of the outflow pipe.

  (5) The molten glass supply apparatus according to any one of (1) to (4), further including detection means that is disposed between the tip portion and the covering portion and detects the temperature of the tip portion.

  (6) The molten glass supply apparatus according to (5), further comprising control means for controlling the high-frequency current supply means based on a detection value of the detection means.

  (7) The heating means further includes a pair of electrodes disposed on the tip portion and the covering portion, and an electric flow means for passing a current between the electrodes, and the tip portion is energized and heated (1 ) To (6) The molten glass supply device according to any one of the above.

  (8) A glass molded body manufacturing apparatus comprising: the molten glass supply device according to any one of (1) to (7); and a forming unit that forms the molten glass supplied from the molten glass supply device.

(9) A molten glass supply method comprising: an outflow step of flowing out the molten glass from the outflow tube; and a heating step of heating the tip of the outflow tube,
The tip is covered with a covering portion that is spaced outwardly,
In the heating step, a molten glass supply method in which the tip portion is induction-heated by supplying a high-frequency current to a coil wound around the outer periphery of the covering portion.

  (10) The molten glass supply method according to (9), wherein the covering portion is connected to the tip portion at a predetermined distance from the tip of the outflow pipe to the base side.

  (11) The molten glass supply method according to (9) or (10), wherein the covering portion extends downward from the tip of the outflow pipe.

  (12) The molten glass supply method according to (9), wherein the covering portion is connected to a distal end of the outflow pipe and is increased in diameter toward the base side of the outflow pipe.

  (13) The molten glass supply according to any one of (9) to (12), further including a step of disposing a detection means between the tip portion and the covering portion, and detecting the temperature of the tip portion by the detection means. Method.

  (14) The molten glass supply method according to (13), further comprising a control step of controlling a supply condition of the high-frequency current based on the detection value of the detection means.

  (15) Any one of (9) to (14), wherein the heating step further includes a step of energizing and heating the tip portion by passing a current between a pair of electrodes arranged in the tip portion and the covering portion. The molten glass supply method of description.

  (16) A glass molded body manufacturing method including a step of molding the molten glass supplied by the molten glass supply method according to any one of (9) to (15).

  According to the present invention, since the high frequency current is supplied to the coil wound around the outer periphery of the covering portion that covers the tip portion, the tip portion is induction heated. Thereby, in addition to heating the tip part itself, the heat release to the outside air is suppressed by the covering part, so that the temperature drop of the tip part of the outflow pipe can be further suppressed.

  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.

  FIG. 1 is a schematic configuration diagram of a molten glass supply apparatus 10 according to the first embodiment of the present invention. FIG. 2 is an enlarged view of a main part of the molten glass supply apparatus 10 of FIG.

<Molten glass supply device>
The molten glass supply apparatus 10 includes an outflow pipe 20 through which molten glass flows out, and a heating unit 30 as heating means for heating the outflow pipe 20. Each component will be described in detail.

[Outflow pipe]
The outflow pipe 20 has a base portion 21, and the base portion 21 is inserted into a melting tank 29 that contains molten glass. As a result, the molten glass in the melting tank 29 is introduced into the base portion 21, passes through the base portion 21 and the distal end portion 23, and is eventually led out (outflowed) from the opening formed in the distal end 25.

  The molten glass that has flowed out of the opening is easily cooled rapidly by the outside air, and as a result, devitrification is likely to occur in the manufactured glass molded body. In order to sufficiently suppress devitrification, it is desired to sufficiently suppress the temperature drop of the distal end portion 23 of the outflow pipe 20. Since the present invention employs a configuration in which the tip portion 23 is induction-heated as will be described later, at least the tip portion 23 of the outflow pipe 20 is made of a material capable of induction heating, preferably a metal such as platinum or a platinum alloy. Preferably it is formed.

  As will be described later, when the base 21 is heated by energization, the base 21 is preferably formed of a material having electrical conductivity, preferably a metal such as platinum or a platinum alloy. In addition, the base 21 and the front-end | tip part 23 may be formed with the same or different raw material.

[Coating]
The distal end portion 23 of the outflow pipe 20 is covered with a covering portion 40 that is disposed outwardly with a gap. Thereby, in addition to the induction heating of the front end part 23, the heat radiation from the front end part 23 to the outside air is suppressed, so that the temperature drop is sufficiently suppressed. Here, if the covering portion 40 is formed of a material capable of induction heating, preferably platinum or a platinum alloy or the like, the tip portion 23 is also heated by radiant heat from the covering portion 40 that has been induction-heated. Is suppressed. In addition, if the covering portion 40 is formed of a heat insulating material, the temperature drop of the covering portion 40 due to the outside air is suppressed, and the radiant heat to the tip portion 23 is maintained at a high level. Can be suppressed.

  In the present specification, the “tip portion” includes a tip having an opening through which molten glass flows out, and indicates a region in a predetermined range where heating is desired from the tip to the base side. The predetermined range may be appropriately set according to the composition and temperature of the molten glass, the material of the tip portion 23, and the like. “Coating” preferably refers to surrounding the entire periphery of the tip, but is not limited to this and includes an embodiment of surrounding only a partial periphery.

  As shown in FIG. 2, the covering portion 40 is preferably connected to the distal end portion 23 at a predetermined distance D from the distal end 25 of the outflow pipe 20 toward the base 21 side. Specifically, in the present embodiment, the distal end portion 23 and the covering portion 40 are coupled via a coupling portion 45 provided at a predetermined distance D from the distal end 25 of the outflow pipe 20 to the base 21 side. The covering portion 40 may be connected to the distal end portion 23 via a connecting portion 45A provided at the distal end 25 of the outflow pipe 20, as shown in FIG. However, in the embodiment of FIG. 3, the molten glass tends to wet and move from the tip 25 to the connecting portion 45 </ b> A and the covering portion 40, making it difficult to make the outflow constant, or cooling and solidifying at the connecting portion 45 </ b> A and the covering portion 40. There is a possibility that the molten glass MG is contaminated by the molten glass. On the other hand, in the aspect shown in FIG. 2, since the connecting portion 45 is separated from the tip 25 by a predetermined distance D, a situation in which MG wets and moves to the connecting portion 45 (so-called wetting up) hardly occurs. preferable.

  Further, as shown in FIG. 4, even when the covering portion 40 </ b> B is connected to the distal end 25 of the outflow pipe 20, the diameter of the molten glass MG is increased by having a shape that expands toward the base 21 side of the outflow pipe 20. Can suppress wetting. In addition, in the aspect shown by FIG.2 and FIG.3, although the front-end | tip part 23 and the coating | coated part 40 are connected via the connection part 45, it is not restricted to this, The separate body from which the front-end | tip part 23 and the coating | coated part 40 isolate | separated. It may be. However, in the case of a separate body, it is likely to be difficult to sufficiently heat the tip 25 by energization heating which will be described later, and therefore the embodiment shown in FIGS. 2 to 4 is preferable.

  Returning to FIG. 2, the predetermined distance D is preferably 1 mm, more preferably 2 mm, and most preferably 3 mm, in terms of sufficiently suppressing the wetting of the molten glass to the connecting portion 45. . On the other hand, the upper limit of the predetermined distance D is preferably 40 mm, more preferably 30 mm, and most preferably 15 mm from the viewpoint of securing a space for installing a couple 51 described later.

  Moreover, the upper limit of the width of the connecting portion 45 (that is, the distance between the tip portion 23 and the covering portion 40) is 10 mm in that the radiant heat from the covering portion 40 can efficiently reach the tip portion 23. Is preferred, more preferably 9 mm, and most preferably 7 mm. On the other hand, when securing a space for installing a couple 51 described later, the width of the connecting portion 45 is preferably 3 mm or more.

  The connecting portion 45 may be formed of a conventionally known material. However, in a mode in which the tip 25 is energized and heated as described later, the connecting portion 45 is formed of an electrically conductive material, preferably a metal such as platinum or a platinum alloy. Preferably it is. In addition, the base part 21, the front-end | tip part 23, and the connection part 45 may be formed with the same or different raw material.

  As in this embodiment, the covering portion 40 preferably extends downward from the tip 25 of the outflow pipe 20. Thereby, since the molten glass MG which flowed out from opening of the front-end | tip 25 is surrounded by the coating | coated part 40, the rapid cooling is suppressed, and devitrification can be suppressed more reliably. Further, in this aspect, since the tip 25 that is most easily cooled is suppressed not only in the circumferential direction (left and right direction in FIG. 2) but also in the downward direction, the cooling of the molten glass MG is further suppressed indirectly. It is preferable in that it can be performed.

  The lower limit of the extending length E extending downward from the tip 25 of the outflow pipe 20 of the covering portion 40 is preferably 3 mm, more preferably 5 mm, and most preferably, in that the above effect can be obtained more. 7 mm. On the other hand, if the extension length E is excessively large, the distance from the tip 25 of the outflow pipe 20 to the mold for receiving the molten glass must be long, which makes it easy for the glass to be excessively cooled, The shape of the molten glass lump is easy to collapse due to the drop impact. Therefore, the upper limit of the extension length E is preferably 200 mm, more preferably 150 mm, and most preferably 100 mm.

[Heating section]
The heating unit 30 includes a coil 31 wound around the outer periphery of the covering unit 40, and a high-frequency power source 33 as a high-frequency current supply unit supplies a high-frequency current to the coil 31 through an electric wire. Induction heating. Then, in addition to the tip part 23 being heated, the heat release to the outside air is suppressed by the covering part 40, so that the temperature drop of the tip part 23 can be further suppressed. Note that the output of the high frequency power supply 33 is controlled by a control unit 61 described later.

  The range in which the coil 31 is wound is preferably the entire circumference of the covering portion 40, but may be a partial circumference of the covering portion 40. In FIG. 1, for convenience of explanation, the covering portion 40 is wound five times, but the number of turns is not limited to this. Further, the high frequency power supply 33 to be used may be a conventionally known one.

  As shown in FIG. 1, the heating unit 30 further includes a pair of electrodes 35 a ′ and 35 a disposed on the tip end portion 23 and the covering portion 40, and an electric flow means is provided between the electrodes 35 a ′ and 35 a. The alternating current power supply 36 passes a current. Thereby, since the front-end | tip part 23 and the coating | coated part 40 are electrically heated, devitrification of glass can be suppressed more reliably. The output of the AC power source 36 is controlled by a control unit 61 described later.

  Here, in order to efficiently heat the tip 25 that is most easily cooled by energization heating, a configuration in which the energized current easily passes through the tip 25, for example, as shown in FIGS. The structure connected to the front-end | tip part 23 is preferable.

  Further, the energization heating may be performed not only on the distal end portion 23 but also on the base portion 21. Thereby, since the temperature change which a molten glass receives while flowing the base 21 can be suppressed, it becomes easy to perform exact temperature control of the molten glass MG which flows out. Specifically, in FIG. 1, a pair of electrodes 37 a and 37 a ′ are provided on the base 21, and current from an AC power supply 38 is supplied to these electrodes 37 a and 37 a ′. Although only the electrodes 37a and 37a 'are shown in FIG. 1, a larger number of sets of electrodes may be provided (refer to JP-A-2006-143563 for details).

[Detection device]
The molten glass supply apparatus 10 is further provided with a couple 51 as a detecting means that is disposed between the tip portion 23 and the covering portion 40 and detects the temperature of the tip portion 23. In the present invention, since a space is formed between the distal end portion 23 and the covering portion 40, the couple 51 can be easily installed using this space. As a result, the temperature of the distal end portion 23 is grasped, and therefore the occurrence of devitrification is systematically suppressed by appropriately adjusting the output, supply time, timing, etc. of the high frequency power source 33, the AC power source 36, and the AC power source 38. it can. The couple 51 and a transmission unit 53 described later constitute a detection device 50.

  Moreover, it is preferable that the molten glass supply apparatus 10 is provided with the control apparatus 60 as a control means which controls the high frequency power supply 33 based on the detected value of the couple 51. Thereby, since the output, supply time, timing, etc. of the high frequency power supply 33 are automatically adjusted, the occurrence of devitrification can be more reliably suppressed by avoiding human error. As shown in FIG. 1, the control unit 61 of the control device 60 receives the temperature data measured by the couple 51 from the transmission unit 53 and controls the high-frequency power source 33 based on this detected value. Specifically, the control unit 61 increases the output and / or supply time of the high-frequency power source 33 when the detection value falls below a predetermined range, and conversely when the detection value exceeds the predetermined range, Reduce supply time. The transmission / reception method may be a conventionally known one.

  It should be noted that the period for controlling the high frequency power supply 33 by feeding back the temperature data detected by the couple 51 is preferably 0.08 seconds or less, more preferably 0 in that the fluctuation of the temperature of the tip 23 can be suppressed. .05 seconds or less, most preferably 0.04 seconds or less.

  The controller 61 preferably controls not only the high frequency power supply 33 but also the output, supply time, timing, and the like of the AC power supply 36 and / or the AC power supply 38. Thereby, since the grade of electric heating is also adjusted appropriately, the temperature management of molten glass MG can be optimized more.

  The glass molded body device according to the present invention includes the above-described molten glass supply device 10 and a forming device (not shown) as a forming means for forming the molten glass MG supplied from the molten glass supply device 10. This molding apparatus has a mold for receiving the molten glass flowing out from the outflow pipe 20 of the molten glass supply apparatus 10. The configuration of the molding apparatus specifically used may be appropriately selected according to the purpose. Although not particularly limited, in consideration of the fact that the molten glass is at a high temperature, it is preferable to perform the floating molding by using a porous member having a molding surface made of a porous member and ejecting gas from the molding surface. A plurality of molds constituting the molding apparatus may be used. For example, a mold for forming a preform and a mold for precision press molding may be used in combination.

<Glass compact manufacturing method>
The glass molded object manufacturing method which concerns on embodiment of this invention has the supply process which supplies a molten glass flow, and the shaping | molding process which shape | molds molten glass. Each process is demonstrated referring the above molten glass supply apparatus 10. FIG.

[Supply process]
The supply process includes an outflow process for flowing out the molten glass MG from the outflow pipe 20 and a heating process for heating the tip portion 23 of the outflow pipe 20. In the manufacturing method of the present invention, the distal end portion 23 is covered with the covering portion 40 that is arranged outwardly at a distance, and the coil 31 wound around the outer periphery of the covering portion 40 is heated from the high frequency power source 33 in the heating process. By supplying a high-frequency current, the tip 23 is induction-heated. Thereby, in addition to the induction heating of the front end part 23, the heat radiation from the front end part 23 to the outside air is suppressed, so that the temperature drop is sufficiently suppressed.

  As shown in FIG. 2, the covering portion 40 is preferably connected to the distal end portion 23 at a predetermined distance D from the distal end 25 of the outflow pipe 20 to the base 21 side. Thereby, it is possible to make it difficult for the MG to get wet and transfer to the connecting portion 45 (so-called wetting up). In addition, not only this but the coating | coated part 40 may be connected with the front-end | tip part 23 via the connection part 45A provided in the front-end | tip 25 of the outflow tube 20, as FIG. 3 shows. However, in the embodiment of FIG. 3, the molten glass tends to wet and move from the tip 25 to the connecting portion 45 </ b> A and the covering portion 40, making it difficult to make the outflow constant, or cooling and solidifying at the connecting portion 45 </ b> A and the covering portion 40. There is a possibility that the molten glass MG is contaminated by the molten glass.

  Therefore, when connecting the covering portion to the tip of the outflow pipe, it is preferable to expand the diameter of the covering portion 40B toward the base 21 side of the outflow pipe 20 as shown in FIG. Thereby, the wetting up of the molten glass MG can be suppressed.

  Further, as shown in FIG. 2, it is preferable that the covering portion 40 extends downward from the tip 25 of the outflow pipe 20. Thereby, since the molten glass MG which flowed out from opening of the front-end | tip 25 is surrounded by the coating | coated part 40, the rapid cooling is suppressed, and devitrification can be suppressed more reliably. Further, in this aspect, since the tip 25 that is most easily cooled is suppressed not only in the circumferential direction (left and right direction in FIG. 2) but also in the downward direction, the cooling of the molten glass MG is further suppressed indirectly. It is preferable in that it can be performed.

  It is preferable that the supplying step further includes a step of disposing a couple 51 between the tip portion 23 and the covering portion 40 and detecting the temperature of the tip portion 23 by the couple 51. As a result, the temperature of the distal end portion 23 is grasped, and therefore the occurrence of devitrification is systematically suppressed by appropriately adjusting the output, supply time, timing, etc. of the high frequency power source 33, the AC power source 36, and the AC power source 38 it can.

  It is preferable that the supply process further includes a control process for controlling the supply condition of the high-frequency current based on the detected value of the couple 51. Thereby, since the output, supply time, timing, etc. of the high frequency power supply 33 are automatically adjusted, the occurrence of devitrification can be more reliably suppressed by avoiding human error. Specifically, in the control process, when the detected value falls below a predetermined range, the output and / or supply time of the high-frequency power source 33 is increased. Conversely, when the detected value exceeds the predetermined range, the output and / or supply of the high-frequency power source 33 is increased. Reduce time. The transmission / reception method may be a conventionally known one.

  It is preferable that the heating step further includes a step of energizing and heating the tip end portion 23 by causing a current to flow from the AC power source 36 between the pair of electrodes 35 a ′ and 35 a arranged at the tip end portion 23 and the covering portion 40. Thereby, since the front-end | tip part 23 and the coating | coated part 40 are electrically heated, devitrification of glass can be suppressed more reliably.

[Molding process]
In the forming step, the molten glass MG supplied in the supplying step is formed to form a glass molded body. Specific procedures may be appropriately selected according to the purpose. Although not particularly limited, in consideration of the fact that the molten glass is at a high temperature, it is preferable to perform the floating molding by using a porous member having a molding surface made of a porous member and ejecting gas from the molding surface. A plurality of molds constituting the molding apparatus may be used. For example, a mold for forming a preform and a mold for precision press molding may be used in combination. Moreover, the transfer to another shaping | molding die can also be performed smoothly by using what can divide | mold a shaping | molding surface.

  Since the glass molded body thus produced has little or no devitrification, it is useful for substrate blanks for information magnetic recording media, preforms for producing optical elements, optical elements, and the like.

<Example>
SiO ₂ —Li ₂ 2O-based glass is melted, and this molten glass is melted into a molten glass supply device shown in FIGS. 1 and 2 (width of connection portion 45 mm, distance D 3 mm, distance E 10 mm, and length of covering portion 40 60 mm. , The inner diameter of the outflow pipe 20 was 9 mm), and flowed out from the tip 25 of the outflow pipe 20, received by the lower mold of the mold and pressed by the upper mold. During this time, heating was continued by supplying a high frequency current to the coil 31. The control period of the high frequency power supply 33 based on the temperature data detected by the couple 51 was set to 0.03 seconds.

  Devitrification was not confirmed in the produced glass molded body. Further, as a result of the constant flow rate of the molten glass, the weight of the obtained glass molded body was almost uniform.

(Comparative example)
A glass molded body was produced in the same procedure as in the example except that the outflow pipe without the heating unit 30 and the covering unit 40 was used and the tip of the outflow pipe was heated with a ring burner.

  The gas pressure supplied to the ring burner was likely to fluctuate, which caused the temperature at the tip of the outflow pipe to be unstable. Moreover, the produced glass moldings include those in which devitrification occurs, and in particular, many of the glass moldings produced in the early stage of molten glass outflow are devitrified.

  The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

It is a schematic block diagram of the molten glass supply apparatus which concerns on one Embodiment of this invention. It is a principal part enlarged view of the molten glass supply apparatus of FIG. It is a principal part enlarged view of the molten glass supply apparatus which concerns on another embodiment of this invention. It is a principal part enlarged view of the molten glass supply apparatus which concerns on another embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Molten glass supply apparatus 20 Outflow pipe 21 Base 23 Tip part 25 Tip 29 Melting tank 30 Heating part (heating means)
31 Coil 33 High frequency power supply (high frequency current supply means)
35 Electrode 36 AC power supply 37 Electrode 38 AC power supply 40 Covering part 45 Connection part 50 Detection device 51 Couple (detection means)
53 Transmission Unit 60 Control Device 61 Control Unit (Control Unit)

Claims (16)

A molten glass supply device comprising an outflow pipe for flowing out the molten glass, and a heating means for heating the tip of the outflow pipe,
The tip portion is covered with a covering portion that is spaced outwardly;
The said heating means has a coil wound around the outer periphery of the said coating | coated part, and the high frequency current supply means which supplies a high frequency current to this coil, The molten glass supply apparatus which induction-heats the said front-end | tip part.   The molten glass supply apparatus according to claim 1, wherein the covering portion is connected to the distal end portion at a predetermined distance from the distal end of the outflow pipe to the base side.   The molten glass supply apparatus according to claim 1, wherein the covering portion extends downward from a tip of the outflow pipe.   The molten glass supply apparatus according to claim 1, wherein the covering portion is connected to a distal end of the outflow pipe and has a shape that expands toward a base side of the outflow pipe.   The molten glass supply apparatus according to any one of claims 1 to 4, further comprising a detection unit that is disposed between the tip portion and the covering portion and detects a temperature of the tip portion.   The molten glass supply apparatus according to claim 5, further comprising a control unit that controls the high-frequency current supply unit based on a detection value of the detection unit.   The heating means further includes a pair of electrodes disposed on the tip portion and the covering portion, and an electric flow means for passing a current between the electrodes, and the tip portion is energized and heated. The molten glass supply apparatus in any one.   A glass molded body manufacturing apparatus comprising: the molten glass supply device according to any one of claims 1 to 7; and a molding unit that molds the molten glass supplied from the molten glass supply device. A molten glass supply method comprising: an outflow step of flowing out the molten glass from the outflow tube; and a heating step of heating the tip of the outflow tube,
The tip is covered with a covering portion that is spaced outwardly,
In the heating step, a molten glass supply method in which the tip portion is induction-heated by supplying a high-frequency current to a coil wound around the outer periphery of the covering portion.   The molten glass supply method according to claim 9, wherein the covering portion is connected to the tip portion at a predetermined distance from the tip of the outflow pipe to the base side.   The molten glass supply method according to claim 9 or 10, wherein the covering portion is extended downward from a tip of the outflow pipe.   The molten glass supply method according to claim 9, wherein the covering portion is connected to a distal end of the outflow pipe and the diameter is expanded toward a base side of the outflow pipe.   The molten glass supply method according to any one of claims 9 to 12, further comprising a step of disposing a detection means between the tip portion and the covering portion, and detecting the temperature of the tip portion by the detection means.   The molten glass supply method according to claim 13, further comprising a control step of controlling a supply condition of the high-frequency current based on a detection value of the detection means.   The molten glass supply according to any one of claims 9 to 14, wherein the heating step further includes a step of energizing and heating the tip portion by passing an electric current between a pair of electrodes arranged in the tip portion and the covering portion. Method.   A glass molded body manufacturing method comprising a step of molding the molten glass supplied by the molten glass supply method according to claim 9.

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