JP6955208B2 - Glass article manufacturing method, glass article manufacturing equipment, and tube - Google Patents

Description

The present invention relates to a method for producing a glass article, an apparatus for producing a glass article, and a tube.

As disclosed in Patent Document 1, there is known a method of manufacturing a glass article by, for example, press molding or blow molding of molten glass flowing out of a spout. The outflow of molten glass from inside the spout is controlled by a plunger that reciprocates in a cylindrical tubular tube having a constant inner diameter. In order to allow a predetermined amount of molten glass to flow out from the spout, it is necessary to design the size of the tube to a certain size.

JP-A-54-069118

As described above, when the outflow of molten glass from the spout is controlled by a plunger that reciprocates in the tube, the components in the molten glass that are stagnant in the tube volatilize, resulting in foreign molten glass. There is. When the molten glass dissimilarized in this way flows out of the spout, there is a risk of causing defects such as bumps in the glass article.

An object of the present invention is to provide a method for producing a glass article, an apparatus for producing a glass article, and a tube capable of stabilizing the quality of the glass article.

The method for manufacturing a glass article that solves the above problems is to control the outflow of molten glass from the spout by a plunger that reciprocates in the tube, and to manufacture the glass article using the molten glass that flows out from the spout. It is a manufacturing method of goods
The tube has a diameter-expanded portion having a constant inner diameter and is arranged in the molten glass in the spout, and an inner peripheral surface provided above the diameter-expanded portion and continuous with the diameter-expanded portion. It has a reduced diameter portion whose inner diameter is smaller than that of the enlarged diameter portion, and positions the liquid level of the molten glass in the spout within the extending range of the reduced diameter portion.

According to this method, the area of the liquid surface of the molten glass in the tube can be reduced even if the size of the opening of the tube is maintained at a predetermined size. As a result, it is possible to suppress the volatilization of the components in the molten glass, so that the molten glass stagnant in the tube is less likely to become heterogeneous.

In the method for manufacturing a glass article, the reduced diameter portion includes a first reduced diameter portion having a constant inner diameter and a second reduced diameter portion located between the first reduced diameter portion and the enlarged diameter portion. It is preferable that the inner peripheral surface of the second reduced diameter portion is an inclined surface continuous with the inner peripheral surface of the enlarged diameter portion and the inner peripheral surface of the first reduced diameter portion.

According to this method, the molten glass around the second reduced diameter portion of the tube is less likely to stagnate. This makes it more difficult for the molten glass in the tube to become heterogeneous.
In the method for manufacturing a glass article, the reduced diameter portion includes a first reduced diameter portion having a constant inner diameter and a second reduced diameter portion located between the first reduced diameter portion and the enlarged diameter portion. It is preferable that the inner peripheral surface of the second reduced diameter portion is a curved surface that is continuous with the inner peripheral surface of the enlarged diameter portion and the inner peripheral surface of the first reduced diameter portion and bulges outward. ..

According to this method, the molten glass around the second reduced diameter portion of the tube is less likely to stagnate. This makes it more difficult for the molten glass in the tube to become heterogeneous.
In the method for producing a glass article, it is preferable that the liquid level of the molten glass in the spout is positioned within the extending range of the first reduced diameter portion.

According to this method, the area of the liquid surface of the molten glass in the tube can be made smaller. As a result, it is possible to further suppress the volatilization of the components in the molten glass, so that the molten glass stagnant in the tube is less likely to become heterogeneous.

In the method for manufacturing the glass article, the inner diameter of the portion of the reduced diameter portion located on the liquid surface of the molten glass is preferably 90% or less when the inner diameter of the enlarged diameter portion is 100%.
According to this method, the area of the liquid surface of the molten glass in the tube can be further reduced. As a result, it is possible to further suppress the volatilization of the components in the molten glass, so that the molten glass stagnant in the tube is less likely to become heterogeneous.

A glass article manufacturing apparatus that solves the above problems controls the outflow of molten glass from the spout by a plunger that reciprocates in the tube, and uses the molten glass that flows out from the spout to manufacture the glass article. In the article manufacturing apparatus, the tube has a diameter-expanded portion having a constant inner diameter and is arranged in the molten glass in the spout, and is provided above the diameter-expanded portion and is continuous with the diameter-expanded portion. It has an inner peripheral surface and a reduced diameter portion whose inner diameter is smaller than that of the enlarged diameter portion, and is used by positioning the liquid surface of the molten glass in the spout within the extending range of the reduced diameter portion.

The tube that solves the above problems is a tube in which a reciprocating plunger is inserted and is used to control the outflow of molten glass from the inside of the spout. The tube has a constant inner diameter and is inside the spout. It has an enlarged diameter portion arranged in the molten glass and a reduced diameter portion provided above the enlarged diameter portion and having an inner peripheral surface continuous with the enlarged diameter portion and having an inner diameter smaller than that of the enlarged diameter portion. Then, the liquid level of the molten glass in the spout is positioned within the extending range of the reduced diameter portion and used.

According to the present invention, it is possible to stabilize the quality of a glass article.

It is sectional drawing which shows the manufacturing apparatus of the glass article in embodiment. It is sectional drawing along line 2-2 of FIG. It is sectional drawing which shows a part of a tube and a plunger. It is sectional drawing which shows a part of a tube and a plunger. It is sectional drawing which shows the modification example of a tube. It is sectional drawing which shows the modification example of a tube. It is sectional drawing which shows the modification example of a tube. It is sectional drawing which shows the modification example of a tube.

Hereinafter, a method for manufacturing a glass article, an apparatus for manufacturing a glass article, and an embodiment of a tube will be described with reference to the drawings.
First, a glass article manufacturing apparatus and a tube will be described.

As shown in FIGS. 1 and 2, the glass article manufacturing apparatus 11 controls the outflow of the molten glass G from the inside of the spout 12 by a plunger 14 that reciprocates in the tube 13, and the melting that flows out from the inside of the spout 12. It is an apparatus for manufacturing a glass article using glass G. As is well known, such a glass article manufacturing apparatus 11 has a spout 12, a tube 13, and a plunger 14, and uses the outflow portion from which the molten glass G flows out and the molten glass G outflowing from the outflow portion to produce a glass article. It is provided with a molding portion for molding.

The spout 12 in the glass article manufacturing apparatus 11 is connected to the fore hearth of the glass melting furnace. The spout 12 has an opening through which the molten glass G supplied from the fore hearth flows out. An orifice having a circular hole is attached to the opening of the spout 12. The molten glass G flowing out of the orifice is cut by a cutting device (not shown) to obtain a glass gob for molding.

As shown in FIG. 3, the tube 13 in the glass article manufacturing apparatus 11 has a diameter-expanded portion 15 having a constant inner diameter and is arranged in the molten glass G in the spout 12, and is continuous with the diameter-expanded portion 15. It has a peripheral surface and a reduced diameter portion 16 having an inner diameter smaller than that of the enlarged diameter portion 15. The reduced diameter portion 16 is provided above the enlarged diameter portion 15. The reduced diameter portion 16 has a first reduced diameter portion 17 having a constant inner diameter, and a second reduced diameter portion 18 located between the first reduced diameter portion 17 and the enlarged diameter portion 15.

The liquid level GL of the molten glass G in the spout 12 is located within the extending range of the reduced diameter portion 16 of the tube 13. In the present embodiment, the liquid level GL of the molten glass G is located at the first reduced diameter portion 17. Here, the height H1 of the liquid level GL of the molten glass G and the height H2 of the boundary position TL1 (the lower end of the first reduced diameter portion 17) between the first reduced diameter portion 17 and the second reduced diameter portion 18 The difference ΔHA (ΔHA = H1-H2) preferably satisfies the relationship of the following formula (1).

0 <ΔHA ≦ 40 [mm] ・ ・ ・ (1)
The inner peripheral surface of the second reduced diameter portion 18 of the tube 13 is composed of an inclined surface 18a continuous with the inner peripheral surface of the enlarged diameter portion 15 and the inner peripheral surface of the first reduced diameter portion 17. The angle θ1 of the inclined surface 18a is preferably in the range of 15 to 45 ° with respect to the vertical surface. The angle θ1 of the inclined surface 18a is measured in the vertical cross section of the tube. The inner diameter of the portion of the reduced diameter portion 16 of the tube 13 located at the liquid level GL of the molten glass G (in the present embodiment, the inner diameter of the first reduced diameter portion 17) is 100% of the inner diameter of the enlarged diameter portion 15 of the tube 13. When it is, it is preferably 90% or less.

As shown in FIGS. 1, 2, and 4, the peripheral wall of the tube 13 has a through hole 19. The through hole 19 of the tube 13 has an inner peripheral shape that goes downward from the outside to the inside of the peripheral wall of the tube 13. The inner peripheral surface of the through hole 19 of the tube 13 in the present embodiment includes an inclined surface 19a that inclines downward from the outside to the inside of the peripheral wall of the tube 13. The inclined surface 19a in the through hole 19 of the tube 13 directs the air flow introduced into the tube 13 through the through hole 19 downward as shown by an arrow in FIG. The through hole 19 of the present embodiment is formed in the reduced diameter portion 16 (first reduced diameter portion 17) of the tube 13.

As shown in FIG. 2, the through hole 19 of the tube 13 is composed of a plurality of holes arranged along the circumferential direction of the peripheral wall of the tube 13. In the present embodiment, through holes 19 are formed at three locations having a central angle of 120 ° in the circumferential direction of the tube 13. The number of through holes 19 in the tube 13 may be changed. For example, the arrangement of the through holes 19 may be changed according to the number of through holes 19. The number of through holes 19 is preferably 1 or more and 6 or less.

As shown in FIG. 4, the inner peripheral surface of the through hole 19 of the tube 13 is inclined by 20 ° or more at an angle θ2 from horizontal to downward from the viewpoint of directing the airflow in a direction closer to the liquid level GL of the molten glass G. It is preferable to include the surface 19a. Further, the angle of the inclined surface 19a is preferably 45 ° or less at an angle θ2 extending downward from the horizontal from the viewpoint of ensuring the strength around the through hole 19. The angle of the inclined surface 19a of the through hole 19 is measured in the vertical cross section of the through hole 19.

The height H3 of the molten glass G in the spout 12 from the liquid level GL at the lower end of the opening inside the peripheral wall in the through hole 19 of the tube 13 is preferably in the range of 20 mm or more and 100 mm or less. The hole diameter of the through hole 19 of the tube 13 is preferably in the range of 5 to 20% when the outer peripheral length of the tube 13 is 100%. As the hole diameter of the through hole 19 of the tube 13 is increased, the air flow introduced into the tube 13 can be increased. The smaller the hole diameter of the through hole 19 of the tube 13, the easier it is to secure the strength of the tube 13. The through hole 19 of the tube 13 of the present embodiment has an inner peripheral shape having a constant inner diameter, and more specifically, has a cylindrical shape having a constant inner diameter.

As is well known, the tube 13 is made of a refractory material. The thickness of the peripheral wall of the tube 13 is, for example, in the range of 10 mm or more and 60 mm or less. The tube 13 can be obtained by a well-known molding method such as molding, cutting, and grinding. The glass article manufacturing apparatus includes a rotating mechanism for rotating the tube 13, and the tube 13 supported above the spout 12 is rotated around the tube axis by the rotating mechanism.

As shown in FIGS. 1, 2, and 3, a plunger 14 is arranged in the tube 13. The rod-shaped plunger 14 is arranged so as to be coaxial with the tube axis of the tube 13. As is well known, the plunger 14 is made of a refractory material. The plunger 14 is supported above the spout 12 and is connected to a reciprocating drive mechanism (not shown). With this reciprocating drive mechanism, the plunger 14 can be moved up and down.

As shown in FIG. 3, the distance W between the plunger 14 and the inner peripheral surface of the reduced diameter portion 16 (first reduced diameter portion 17) of the tube 13 is preferably in the range of 10 mm or more and 50 mm or less. When this distance W is 10 mm or more, it is easy to prevent the plunger 14 and the inner peripheral surface of the reduced diameter portion 16 of the tube 13 from coming into contact with each other due to vibration or the like. In addition, the plunger 14 and the tube 13 can be easily replaced. When this interval W is 50 mm or less, volatilization of the molten glass G can be further suppressed. The interval W is the interval between the plunger 14 and the portion having the smallest inner diameter (first diameter-reduced portion 17) of the diameter-reduced portion 16.

As shown in FIGS. 1 and 2, the glass article manufacturing apparatus 11 of the present embodiment includes a gas burner 20. The gas burner 20 is provided on the upper portion of the spout 12, and by injecting a flame into the spout 12, the molten glass G in the spout 12 is heated (heated). The injection port 20a of the gas burner 20 includes an injection port 20a arranged so as to face the outer peripheral surface of the tube 13. In the present embodiment, a plurality of injection ports 20a of the gas burner 20 are provided so as to surround the tube 13.

In the above-mentioned glass article manufacturing apparatus 11, the molten glass G flowing out of the spout 12 is cut by a cutting apparatus (not shown). The cut glass gob is supplied to the molding section and molded into a glass article having a predetermined shape. Examples of the glass molding machine used in the molding unit include a press molding machine and a blow molding machine. The glass molding machine may be a molding machine in which a press molding machine and a blow molding machine are combined. Examples of glass articles include containers (bottles, pots, dishes, etc.), electronic parts, optical parts, and the like.

Next, a method for producing a glass article will be described together with its main actions.
In the method for manufacturing a glass article, the outflow of the molten glass G from the inside of the spout 12 is controlled by a plunger 14 that reciprocates in the tube 13, and the glass article is manufactured using the molten glass G that has flowed out from the inside of the spout 12.

In the method for manufacturing a glass article, the liquid level GL of the molten glass G in the spout 12 is positioned within the extending range of the reduced diameter portion 16 (first reduced diameter portion 17) of the tube 13. According to this method, even if the size of the opening of the tube 13 is maintained at a predetermined size, the liquid level GL of the molten glass G in the tube 13 (between the reduced diameter portion 16 of the tube 13 and the plunger 14). The area of the liquid level GL) of the molten glass G can be reduced. As a result, it is possible to suppress the volatilization of the components in the molten glass G, so that the molten glass G stagnant in the tube 13 is less likely to become heterogeneous. Further, since the enlarged diameter portion 15 has a constant inner diameter, a predetermined amount of molten glass G can flow out from the inside of the spout 12.

Further, in the method for manufacturing a glass article of the present embodiment, an air flow is introduced into the tube 13 through a through hole 19 of the tube 13. In this method of manufacturing a glass article, the airflow introduced into the tube 13 through the through hole 19 of the tube 13 is directed downward by the inner peripheral shape of the through hole 19. According to this method, the air flow introduced into the tube 13 is directed to the liquid level GL of the molten glass G in the tube 13 along the plunger 14. As a result, the temperature of the molten glass G near the liquid level GL in the tube 13 can be stabilized, so that the molten glass G stagnant in the tube 13 is less likely to become heterogeneous.

According to the embodiment described in detail above, the following effects are exhibited.
(1) In the method for manufacturing a glass article, the outflow of the molten glass G from the inside of the spout 12 is controlled by a plunger 14 that reciprocates in the tube 13, and the glass article is produced using the molten glass G that has flowed out from the inside of the spout 12. It is a method of manufacturing. The tube 13 used in the method for manufacturing a glass article has a constant inner diameter, has a diameter-expanded portion 15 arranged in the molten glass G in the spout 12, and has an inner peripheral surface continuous with the diameter-expanded portion 15, and has a diameter-expanded portion. It has a reduced diameter portion 16 having an inner diameter smaller than that of the portion 15. The reduced diameter portion 16 is provided above the enlarged diameter portion 15. In the method for manufacturing a glass article, the liquid level GL of the molten glass G in the spout 12 is positioned within the extending range of the reduced diameter portion 16.

According to this method, as described above, the molten glass G stagnant in the tube 13 is less likely to become heterogeneous. Therefore, it is possible to stabilize the quality of the glass article.
(2) The reduced diameter portion 16 of the tube 13 used in the method for manufacturing a glass article is located between the first reduced diameter portion 17 having a constant inner diameter, the first reduced diameter portion 17, and the enlarged diameter portion 15. It has two reduced diameter portions 18. The inner peripheral surface of the second reduced diameter portion 18 of the tube 13 is an inclined surface 18a continuous with the inner peripheral surface of the enlarged diameter portion 15 and the inner peripheral surface of the first reduced diameter portion 17.

In this case, the molten glass G around the second reduced diameter portion 18 of the tube 13 is less likely to stagnate. This makes it more difficult for the molten glass G in the tube 13 to become heterogeneous. Therefore, it is possible to make the quality of the glass article more stable. Further, it becomes easy to secure the strength of the boundary portion between the diameter-expanded portion 15 and the diameter-reduced portion 16.

(3) In the method for manufacturing a glass article, the liquid level GL of the molten glass G in the spout 12 is positioned at the first reduced diameter portion 17 of the tube 13.
According to this method, the area of the liquid level GL of the molten glass G in the tube 13 can be made smaller. As a result, it is possible to further suppress the volatilization of the components in the molten glass G, so that the molten glass G stagnant in the tube 13 is less likely to become heterogeneous. Therefore, it is possible to make the quality of the glass article more stable.

(4) The inner diameter of the portion of the reduced diameter portion 16 of the tube 13 used in the method for manufacturing a glass article located at the liquid level GL of the molten glass G is 90% when the inner diameter of the enlarged diameter portion 15 of the tube 13 is 100%. The following is preferable. In this case, the area of the liquid level GL of the molten glass G in the tube 13 can be further reduced. Therefore, it is possible to further stabilize the quality of the glass article.

(5) The peripheral wall of the tube 13 used in the method for manufacturing a glass article has a through hole 19. The through hole 19 of the tube 13 has an inner peripheral shape that goes downward from the outside to the inside of the peripheral wall of the tube 13. In the method for manufacturing a glass article, the airflow introduced into the tube 13 through the through hole 19 of the tube 13 is directed downward by the inner peripheral shape of the through hole 19.

According to this method, as described above, the temperature of the molten glass G near the liquid level GL in the tube 13 can be stabilized, so that the molten glass G stagnant in the tube 13 is less likely to become heterogeneous. Therefore, it is possible to stabilize the quality of the glass article.

(6) In the tube 13 used in the method for manufacturing a glass article, the inner peripheral surface of the through hole 19 preferably includes an inclined surface 19a having an angle of 20 ° or more from the horizontal to the downward direction.

In this case, since the airflow can be directed in a direction closer to the liquid level GL of the molten glass G, the quality of the glass article can be made more stable.
(7) In the method for manufacturing a glass article, a gas burner 20 that injects toward the tube 13 is used. In this case, the airflow heated by the gas burner 20 is introduced from the through hole 19 of the tube 13, so that the temperature of the molten glass G near the liquid level GL in the tube 13 can be further stabilized. Therefore, it is possible to further suppress the heterogeneity of the molten glass G that is stagnant in the tube 13. Therefore, it is possible to make the quality of the glass article more stable.

(8) In the method for manufacturing a glass article, it is preferable that the lower end of the opening inside the peripheral wall in the through hole 19 of the tube 13 is provided at a height of 20 mm or more from the liquid level GL of the molten glass G in the spout 12. In this case, for example, it is possible to prevent the molten glass G from entering the through hole 19 of the tube 13. Therefore, the function of the through hole 19 of the tube 13 can be more reliably exerted.

(9) In the tube 13 used in the method for manufacturing a glass article, the through hole 19 has an inner peripheral shape having a constant inner diameter. In this case, the direction of the airflow introduced into the tube 13 can be controlled with high accuracy.

(10) The through hole 19 of the tube 13 is composed of a plurality of holes arranged along the circumferential direction of the peripheral wall of the tube 13. In this case, even if the through hole 19 has a relatively small inner diameter, it is possible to increase the inflow amount of the airflow into the tube 13. That is, it is possible to suppress a decrease in the strength of the tube 13 due to the formation of the through hole 19 and increase the amount of airflow flowing into the tube 13. Therefore, it is possible to secure the durability of the tube 13 and further stabilize the quality of the glass article. This makes it possible to improve the yield of glass articles, for example.

(Change example)
The above embodiment may be changed as follows.
As shown in FIG. 5, the inner peripheral surface of the second reduced diameter portion 18 of the tube 13 in the glass article manufacturing apparatus 11 includes the inner peripheral surface of the enlarged diameter portion 15 and the inner peripheral surface of the first reduced diameter portion 17. It is also possible to change to a curved surface 18b that is continuous with and bulges outward. Even in this case, the effect described in the above column (2) can be obtained. The curved surface 18b of the second reduced diameter portion 18 of the tube 13 is the boundary position between the reduced diameter portion 16 (second reduced diameter portion 18) and the enlarged diameter portion 15, and the second reduced diameter portion 18 and the first reduced diameter portion 17. Assuming an inclined surface continuous with the boundary position TL1 with, the angle θ3 is preferably in the range of 15 to 45 ° with respect to the vertical surface.

As shown in FIG. 6, the second reduced diameter portion 18 of the tube 13 in the glass article manufacturing apparatus 11 can be omitted. That is, the inner diameter of the reduced diameter portion 16 may be constant. In this case, the boundary portion between the inner peripheral surface of the enlarged diameter portion 15 and the inner peripheral surface of the reduced diameter portion 16 is formed by a right-angled step portion. In this tube 13, the difference ΔHB (ΔHB = H1-H4) between the height H1 of the liquid level GL of the molten glass G and the height H4 of the boundary position TL2 between the enlarged diameter portion 15 and the reduced diameter portion 16 is as follows. It is preferable to satisfy the relationship of the formula (2).

0 <ΔHB ≦ 40 [mm] ・ ・ ・ (2)
The liquid level GL of the molten glass G in the spout 12 of the glass article manufacturing apparatus 11 may be positioned at the second reduced diameter portion 18. Even in this case, since the area of the liquid level GL of the molten glass G in the tube 13 can be made smaller, the effect described in the above column (1) can be obtained.

-The through hole 19 of the tube 13 in the glass article manufacturing apparatus 11 can be omitted.
As shown in FIG. 7, in the tube 13 in the glass article manufacturing apparatus 11, the inner peripheral shape of the through hole 19 may be changed to an inner peripheral shape whose diameter decreases from the outside to the inside of the peripheral wall. In this case, the direction of the airflow introduced into the tube 13 can be controlled with high accuracy. This makes it possible to further enhance the effect described in the above column (4).

As shown in FIG. 8, the inner peripheral surface of the through hole 19 of the tube 13 in the glass article manufacturing apparatus 11 may include a horizontal portion. However, from the viewpoint of accurately controlling the direction of the airflow introduced into the tube 13, the through hole 19 of the tube 13 has the entire inner peripheral surface thereof, as in the above embodiment and the modified example shown in FIG. , It is preferable that the tube 13 has an inner peripheral shape that is inclined from the outside to the inside (in the thickness direction of the peripheral wall).

The inner peripheral shape of the through hole 19 of the tube 13 in the glass article manufacturing apparatus 11 is not limited to the cylindrical shape, but can be changed to a polygonal cylinder shape or the like. That is, the inclined surface 19a may be a curved surface having an arch-shaped cross section when viewed in the penetrating direction of the through hole 19, or may be a flat surface having a straight cross section when viewed in the same direction. Further, the inner peripheral shape of the through hole 19 of the tube 13 is a curved shape composed of only a curved surface without including the inclined surface 19a in the side cross-sectional view (cross-sectional view in the same direction as FIGS. 1, 4, 7 and 8). It may be a shape having both an inclined surface and a curved surface.

-The gas burner 20 in the glass article manufacturing apparatus 11 can be omitted. In this case, the airflow convective in the spout 12 can be introduced into the tube 13 through the through hole 19 of the tube 13.

-In the glass article manufacturing apparatus 11, the tube 13 and the plunger 14 are arranged so that the axial direction is aligned with the vertical direction, but the vertical direction representing the axial direction of the tube 13 and the plunger 14 is an installation tolerance. Including the case where the range is inclined with respect to the vertical direction.

11 ... Glass article manufacturing equipment, 12 ... Spout, 13 ... Tube, 14 ... Plunger, 15 ... Diameter expansion part, 16 ... Diameter reduction part, 17 ... First diameter reduction part, 18 ... Second diameter reduction part, 18a ... Inclined surface, 18b ... Curved surface, G ... Molten glass, GL ... Liquid level.

Claims (7)

A method for manufacturing a glass article, in which the outflow of molten glass from the spout is controlled by a plunger that reciprocates in the tube, and the glass article is manufactured using the molten glass that flows out from the spout.
The tube has a diameter-expanded portion having a constant inner diameter and is arranged in the molten glass in the spout, and an inner peripheral surface provided above the diameter-expanded portion and continuous with the diameter-expanded portion. A method for producing a glass article, which has a reduced diameter portion having an inner diameter smaller than that of the enlarged diameter portion, and positions the liquid level of the molten glass in the spout within the extending range of the reduced diameter portion. The reduced diameter portion has a first reduced diameter portion having a constant inner diameter and a second reduced diameter portion located between the first reduced diameter portion and the enlarged diameter portion.
The first aspect of claim 1, wherein the inner peripheral surface of the second reduced diameter portion is an inclined surface continuous with the inner peripheral surface of the enlarged diameter portion and the inner peripheral surface of the first reduced diameter portion. A method for manufacturing a glass article. The reduced diameter portion has a first reduced diameter portion having a constant inner diameter and a second reduced diameter portion located between the first reduced diameter portion and the enlarged diameter portion.
The inner peripheral surface of the second reduced diameter portion is a curved surface that is continuous with the inner peripheral surface of the enlarged diameter portion and the inner peripheral surface of the first reduced diameter portion and bulges outward. Item 2. The method for manufacturing a glass article according to Item 1. The method for producing a glass article according to claim 2 or 3, wherein the liquid level of the molten glass in the spout is positioned within the extending range of the first reduced diameter portion. Any of claims 1 to 4, wherein the inner diameter of the portion of the reduced diameter portion located on the liquid surface of the molten glass is 90% or less when the inner diameter of the enlarged diameter portion is 100%. The method for manufacturing a glass article according to item 1. A glass article manufacturing apparatus that controls the outflow of molten glass from the spout by a plunger that reciprocates in the tube and manufactures a glass article using the molten glass that has flowed out of the spout.
The tube has a diameter-expanded portion having a constant inner diameter and is arranged in the molten glass in the spout, and an inner peripheral surface provided above the diameter-expanded portion and continuous with the diameter-expanded portion. Manufacture of a glass article having a reduced diameter portion having an inner diameter smaller than that of the enlarged diameter portion, and using the molten glass in the spout so that the liquid level of the molten glass is positioned within the extending range of the reduced diameter portion. Device. A tube in which a reciprocating plunger is inserted and used to control the outflow of molten glass from inside the spout.
The tube has a diameter-expanded portion having a constant inner diameter and is arranged in the molten glass in the spout, and an inner peripheral surface provided above the diameter-expanded portion and continuous with the diameter-expanded portion. A tube having a reduced diameter portion having an inner diameter smaller than that of the enlarged diameter portion, and being used by locating the liquid level of the molten glass in the spout within the extending range of the reduced diameter portion.

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