JPH10338530A - Production of softened glass and floating holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process and apparatus capable of executing the transfer of the softened glass held afloat by a gaseous stream to the ensuing stage without the fusion of the glass to a receiving mold (floating jig) or the occurrence of contact flaws on the glass. SOLUTION: This process for producing the softened glass transfers glass gobs to the ensuing stage in the following manner: The dropping or falling down fused glass is accepted in the state of floating the glass by the gaseous stream on the holder which has a means for ejecting the gaseous stream upward and is dividable to a plurality, by which the glass gob 16 is formed. The glass gob is otherwise heated in the state of floating the glass by the gaseous stream on the holder which has the means 15 for ejecting the gaseous stream upward and is dividable to a plurality and the glass gob is softened. The holder is then divided and the glass gobs are dropped from the spacings of the holder formed by the division. In such a case, the floating holder 10 of the softened glass used in this process maintains the amt. of the gaseous stream ejected upward from the holder at >=80% of the amt. before the division even after the division of the holder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a glass optical element such as a glass lens which does not require grinding and polishing after press forming by floating and holding a softened glass material to be formed. The present invention relates to a floating holder used for this.

[0002]

2. Description of the Related Art In recent years, various methods for precision molding of glass optical elements such as lenses that do not require grinding and polishing after press molding have been studied. As a molding method of this kind, a reheat press method in which a glass preform (a glass material to be molded) is prepared in advance and then reheated and press-molded is mainly used, but a direct press method in which molten glass is directly precision-molded is also used. Are being considered.

For example, Japanese Unexamined Patent Publication No. Hei 6-340430 discloses, as shown in FIG.
A first mold member 30 comprising a split mold which is configured to eject gas from the surface of the porous member 33 and which can be opened and closed in the horizontal direction.
To obtain an optical glass element preform (FIG. 8)
a), a step of dropping the optical glass element preform 32 onto the second mold member 34 by opening the first mold member 30 in the horizontal direction (FIG. 8B), and the optics placed on the second mold member 34; Press-molding the glass preform 32 to obtain an optical glass element ".

Japanese Patent Application Laid-Open No. 9-12317 discloses that, as shown in FIG. 9, a lump of molten glass 41 is lifted by a split type receiving mold (floating device) 40 (or 50) by an airflow blown from below. While maintaining the temperature, the temperature of the receiving mold 40 is adjusted.
(Or 50) is opened and dropped on the forming die, and the molten glass lump 41 is placed in the first receiving die 40 (or 5).
After receiving in step (0), this is further transferred to a split receiving type second receiving mold 50 in the same manner as the first receiving mold, and the temperature is adjusted. Then, the receiving mold 40 (or 50) is opened to place it on the molding die. The method of dropping is shown.

On the other hand, Japanese Patent Application Laid-Open No. 8-133758 discloses a method of manufacturing a glass optical element by press-molding a heat-softened glass gob with a preheated molding die. The glass gob softened by heating while being heated, and the glass gob heated and softened is used as a floating jig for heating the glass gob.
A manufacturing method of a glass optical element, wherein the glass optical element is dropped by being divided into two or more parts, transferred to the preheated mold, and then pressed.

[0006] As a specific example of the floating jig, as shown in FIG.
2. A floating jig 60 (which can be divided into two parts) that floats the glass body 62 on the upper opening by an airflow that is smaller than the diameter of the upper opening 61 and flows upward from the bottom of the upper opening 61, and
As shown in FIG. 10B, a floating jig 7 for floating the glass body 62 by an airflow flowing out of a porous material 71 having a spherical surface or a flat surface approximating the curvature of the outer diameter of the glass body 62.
0 (can be divided into two) is shown.

According to these methods, the softened glass is floated and held by the airflow squirting upward without coming into contact with the first mold member (receiving mold / floating jig), and without using a carrier or the like. The glass is transferred to the mold by dropping, preventing fusing of glass, wrinkles and protrusions, contamination due to contact with the receiving mold, adhesion of glass volatiles, and the like. Optical elements can be molded. At the same time, these methods have the advantages that the molding cycle time is short and the production efficiency is high.

[Problems to be solved by the invention]

[0008] However, these prior art floating holding methods and floating holders (first mold member, receiving mold, floating jig)
All have drawbacks, and there is a problem that a sufficient effect according to the purpose cannot always be obtained. That is, in the method disclosed in JP-A-6-340430, a porous member is used as the floating holder (first mold member). In this case, when the optical glass element preform is dropped, the porous member is not used. Until the first mold member is closed, the gas flow which has been ejected only upward because the first mold member is closed opens the first mold member at the same time as the first mold member opens.
The mold members erupt from the entire area of the vertical surface where they abut each other, the amount of gas escaping upward is reduced at a stretch, and the floating force of the glass element preform is weakened. As a result, the glass element preform falls before the divided floating holders are sufficiently separated and a gap is formed to allow the glass element preform to drop and pass, and the first mold member The glass is fused or comes into contact with the first mold member, causing damage to the preform.

In the above two other prior arts,
The gas flow that has been ejected upward from the lower part of the receiving mold or the floating jig will flow at once to the space created by the opening of the receiving mold or the floating jig at the moment when the receiving mold or the floating jig is divided and opened. The floating force of the lump is weakened, and as a result, glass fusing or contact damage to the receiving mold (floating jig) occurs. Accordingly, an object of the present invention is to provide a method and apparatus for transferring softened glass, which is levitated and held by airflow, to the next step without fusing the glass to a receiving mold (floating jig) or causing contact damage to the glass. Is to provide.

[0010]

Means for Solving the Problems The inventor of the present invention has intensively studied to solve the above-mentioned disadvantages of the prior art. As a result, the above-described problem occurs due to a sudden decrease in the amount of gas flow that has been ejected upward at the time of splitting and opening of the floating holder, and the above problem occurs even after the splitting and opening of the floating holder. It has been found that if the amount of gas flow to be jetted is maintained at 80% or more of the jet volume before opening, it is possible to prevent the falling glass block from fusing to the holder and causing contact damage. Thus, the present invention has been completed.

That is, according to the present invention, a molten glass dripped or flowing down is received on a holder which can be divided into a plurality of parts having means for ejecting an airflow upward, and a glass lump is formed in a state where the molten glass is floated by the airflow. A method of manufacturing a softened glass, comprising a step of dividing the holder and dropping the glass lump from a gap between the holders formed by the division, thereby transferring the glass lump to a next step. The present invention relates to a method for producing a softened glass (first production method), characterized in that the amount of airflow spouting upward from a tool is maintained at 80% or more of that before the division even after the holder division.

Further, the present invention is characterized in that a glass lump is heated and softened while being floated by the air flow on a holder that can be divided into a plurality of parts having means for ejecting an air flow upward, and the holder is divided. And a method of manufacturing softened glass including a step of transferring the glass lump to a next step by dropping the glass lump from the gap between the holders formed by the division, and ejecting the glass lump upward from the holder. The amount of airflow,
The present invention relates to a method for manufacturing softened glass (second manufacturing method), wherein the ratio is maintained at 80% or more of the value before splitting even after the holder is split.

In addition, according to the present invention, there is provided a jig having a concave curved surface having a plurality of gas ejection holes and capable of being divided into a plurality of pieces, for holding a glass lump in a floating state, which is exposed by division. The surface (divided exposed surface) does not have a gas ejection hole, or the exposed surface generated by the division has a gas ejection hole, and the gas ejection amount from the divided exposed surface after dividing the gas ejection hole is as described above. A floating holder for softened glass, characterized in that the amount of gas jetted from the concave curved surface is set to 20% or less.

[0014]

Embodiments of the present invention will be described below. The first method for producing a softened glass according to the present invention is a method carried out in a direct press method in which a glass optical element such as a lens is directly precision-molded from molten glass. This is a method implemented in a reheat press method in which a reform (a glass material to be formed) is prepared in advance, reheated and press-formed.
Further, the floating holder of the present invention can be used in any of the above methods.

In the direct pressing method, usually, a step of obtaining a molten glass lump from molten glass, a step of adjusting the temperature (viscosity) of the molten glass to one suitable for press molding, and press molding the obtained molten glass lump , And three steps. And the first of the present invention
Can be carried out in the direct press method and / or the step. Hereinafter, the method for manufacturing softened glass and the floating holder according to the present invention will be described along the steps of the direct press method.

First Step The first step is a step of forming a glass lump from molten glass. Specifically, the molten glass continuously supplied from an outflow pipe is separated into individual glass pieces. This is the step of making a lump. It is desirable that the glass lump has a spherical shape or a marble shape (a flat shape of a sphere). For this reason, the molten glass lump dripped or flowing down from the outflow pipe is received by the airflow spouting from below, and is formed into a spherical or marble shape while being floated and held. The floating holder shown in FIG. 1 is used for receiving and holding the glass block. (A) is an AA sectional view of (b).

In FIG. 1, a floating holder 10 is made of metal, has a plate-like overall shape, and is provided with a concave portion 11 forming a concave curved surface at the center of its upper surface. This recess 11
The bottom is spherical and the top is conical. When the glass lump is placed in the concave portion 11 without jetting the airflow, it is appropriate to make the glass lump and the concave portion 11 come into contact with a conical surface from the viewpoint that the floating of the glass lump can be facilitated. In addition, a preferable opening angle of the conical surface differs depending on the shape of the glass lump, and from the viewpoint that the glass lump can easily float, for example, in the case of a spherical shape, it is preferably in the range of 20 to 80 °, and a marble shape In case, 50 ~ 11
It is preferably in the range of 0 °. The floating holder 10 is formed so that it can be divided into two parts symmetrically in the center at the center, and each of the pair of holders 10a and 10b is covered and supported by the support arm 12 except for the concave part 11 on the upper surface. . The support arm 12 transfers the glass lump formed in the floating holder 10 in the first step to a temperature adjusting chamber (not shown) together with the floating holder in the second step. Activated when splitting and opening.

A gap 13 is provided in the floating holder 10 covered and supported by the support arm 12 in a sealed state, and the gap 13 is provided from outside the floating holder 10.
Is provided with a gas introduction pipe 14 which communicates with the gas introduction pipe. Further, a plurality of pores 15 penetrating from the gap 13 to the bottom of the recess 11 are formed. The size of the pore 15 is
The diameter of 0.2 mm or more is preferable from the viewpoint that the glass lump can be held without causing the surface of the softened glass to be dented by the jetted air flow, and that the holes can be easily formed. The upper limit of the size of the pores 15 is about 1.5 mm even when the size of the glass block is large. In particular, when flowing the molten glass, if the pores are too large, traces of the pores may be formed. In addition, it is desirable that a large number of the pores 15 be provided near the center divided portion of the floating holder 10 as shown in FIG. Also,
For example, as shown in FIG. 1C, pores having different diameters can be provided. In FIG. 1 (c), a 1 mm pore 1
Four 5 'are provided at symmetrical positions around the bottom of the concave portion, and 0.4 mm fine holes 15 are provided so as to be arranged near the divided portion. By doing so, there is an advantage that it is possible to favorably maintain the levitation in the vicinity of the divisional ridge line where contact easily occurs. The molten glass dropped or dropped from the outflow pipe above the floating holder 10 is used as the floating holder 1
0 is guided to the cavity 13 via the gas introduction pipe 14 from outside, and is further held in a state of floating in the recess 11 by receiving a gas flow of gas ejected from the pores 15 provided on the bottom surface of the recess 11. A spherical or marbled glass block 16 is formed in the concave portion.

The second step The second step, while floating held by a gas stream which ejects the glass gob from the lower side, the temperature of the glass gob, and that the glass viscosity most suitable for molding in the third step This is the step of adjusting the distance to be adjusted. The second step can be performed continuously with the first step, using the floating holder 10 used in the first step as it is, but the glass block is removed from the floating holder 10 of the first step. The transfer may be performed to another floating holder dedicated to the second step.

When transferring the glass block from the floating holder dedicated to the first step to the floating holder dedicated to the second step, for example, the floating holder 10 in the first step is moved by the support arm 12 to the floating holder in the second step. It can be carried out by transferring the floating holder to the position directly above the holder, dividing the floating holder in the first step into two parts, and dropping the glass block onto the floating holder in the second step.

The speed at which the floating holder is opened to the right and left is relatively high. However, if the speed is too high, vibration occurs or the preform is pulled by the left or right floating holder, and a good drop is obtained. I can't get it. In addition, the floating holder
It is important that the recesses are set so that the recesses coincide completely without any level difference between the left and right sides when closed. If there is a deviation here, gas leakage occurs, and the lower surface of the softened preform is easily damaged, and the floating holder is easily damaged.

When the floating holder 10 in the first step is divided into two parts and opened, the amount of gas ejected above the floating holder is at least the amount of gas before opening the floating holder. It is maintained at 80% or more. It is most preferable that the amount of the ejected gas be maintained at the same amount (100%) after opening of the floating holder as before the opening. In the levitating holder 10 according to the present invention, the gas is ejected from the gap 13 provided in a sealed state inside the levitating holder, so that the gas is generated from the space generated in the open portion at the moment when the levitating holder is opened. Does not leak, and the ejection amount of 80% to 100% as compared to before the opening is maintained. By doing so, it is possible to drop and move without causing glass fusion and contact flaws, which are problems in the conventional method. The structure of the floating holder in the second step may be substantially the same as the structure of the floating holder 10 in the first step.

Third Step In the third step, the glass lump whose viscosity has been adjusted in the second step is formed by pressing with a pair of upper and lower forming dies, and then cooled to a predetermined temperature or less. This is a step of releasing the glass molded body from the mold. In the third step,
A conventionally known mold for precision molding of a glass optical element can be used.

The glass block formed into a spherical or marble shape through the first step and the second step is transported to a position directly above the lower mold of the molding die while being floated and held in the floating holder. Then, the floating holder is opened in two parts, the glass block falls into the lower mold, and the upper mold immediately descends to perform press molding. Also, when the floating holder is divided and opened to transfer the glass block from the second step to the third step, the amount of gas ejected above the floating holder is 80 to 1 before the split opening.
It is maintained at 00%.

As described above, the floating holding method and the floating holder of the present invention have been described along the steps of the direct press method. Next, a second manufacturing method for implementing the present invention in the reheat press method will be described. I do. The reheat press method is usually used for forming glass optical elements (final molded products)
Molding a glass preform to be used as a precursor, a step of reheating the glass preform to a viscosity suitable for molding, and a mold for molding the glass preform softened to an appropriate viscosity by reheating. And forming into a predetermined shape. And, the present invention can be carried out in the above-mentioned steps of the reheat press method.

That is, a state in which a glass preform previously formed in a known glass preform forming step is levitated by an airflow of gas ejected upward using the above-mentioned floating holder 10 shown in FIG. After being heated and softened by heating to form a glass lump, the floating holder 10 is moved to just above the lower die of the molding die, and the glass lump is dropped by opening it in two parts, and the glass lump is dropped and molded by the molding die. . Also in this case, when the floating holder is divided and opened, the amount of gas ejected upward is 8 times that before opening.
0 to 100% is kept. As the mold used in the preform molding step, a conventionally known mold can be used.

Although the embodiment of the present invention is as described above, the floating holder of the present invention is not limited to the one shown in FIG. For example, the levitation holder shown in FIG. 1 is formed so that it can be divided into two parts at the center part in the left and right directions. In short, it can be divided into multiple,
Any structure can be used as long as the glass lump can be dropped downward by the split opening. Further, as shown in FIG. 2, the floating holder 10 may be composed of a porous member 21 and an airtight member 22 covering other than the concave portion 11 forming the concave curved surface on the upper surface of the porous member 21. In this case, the recess 1 as shown in FIG.
The pores on one bottom surface are unnecessary, and the gas blows out through the fine holes in the porous member 21.

Further, as shown in FIG.
May be formed in a conical shape, and two (FIG. 3 (b)) or four (FIG. 3 (c)) or more pores 15 may be provided near the center of the bottom surface of the concave portion 11. Further, FIG.
As shown in the figure, when dropping the glass block 16 from the floating holder 10 to the lower mold 23 of the forming die, a funnel-shaped funnel 24 may be interposed between the floating holder 10 and the lower mold 23. By doing so, the glass lump can be accurately dropped to the center of the lower mold.

FIG. 5 (a) is a sectional view,
(B) is a view of the divided exposed surface as viewed from the front.) As shown in FIG. 3, if a horizontal hole 25 penetrating from the gap 13 of the floating holder 10 to the divided exposed surface of the floating holder is provided, When dropping the lump, an appropriate amount of gas can be ejected from the left and right divided surfaces of the floating holder 10, thereby restricting the falling of the glass lump 16 and preventing the glass lump from contacting the floating holder. can do. When the glass lump is in a marble shape, the recess 1 of the floating holder shown in FIG.
The opening angle of one conical surface is preferably 50 to 110 °. If the opening angle of the conical surface of the concave portion is smaller than 50 °, the inclination tends to occur during the floating of the preform, and vibration occurs. Conversely, if the opening angle of the conical surface is larger than 110 °, the roll becomes large, This is because good fall cannot be obtained. In addition, as described above, when the glass lump is spherical,
The opening angle of the conical surface is preferably in the range of 20 to 80 °.

It is preferable that the horizontal hole 25 is inclined upward toward the divided exposed surface of the floating holder so that the glass block can be properly dropped. Further, the size and the number of the lateral holes 25 are appropriate, but the size and the number are such that the amount of gas ejected upward from the fine holes 15 when the floating holder is divided and opened can be maintained at 80% or more of that before opening. It is necessary to be.

As shown in FIG. 6, a conical or concave concave portion 17 is further provided at the center of the concave curved surface of the floating holder.
The formation of is effective in preventing fusion of glass blocks and contact flaws at the time of falling. The size and shape of the recess 17
It can be appropriately determined in consideration of the size and shape of the glass block, the divisional moving speed of the floating holder, and the like. Also, as shown in FIG.
The formation of the notch 18 at the upper end edge of the divided exposure surface of the floating holder is effective in preventing the glass block from fusing and contact damage when falling. The angle and shape of the notch 18 can be determined as appropriate in consideration of the size and shape of the glass lump, the dividing movement speed of the floating holder, and the like.

[0032]

Embodiments of the present invention will be described below with reference to the drawings. Example 1 In this example, the floating holder shown in FIG. 1 was used. The material of the floating holder 10 is a tungsten alloy.
mm and height 10 mm. Also, the shape of the recess 11 is
As shown in the sectional view (FIG. 1A), the bottom has a spherical surface, and the upper portion has a conical surface. The opening angle of the conical surface of the concave portion 11 of this embodiment is 60 °. Further, a gap 13 is provided below the spherical surface of the recess 11, and the gas for floating flows into the gap 13 via a gas introduction pipe 14. A plurality of pores 15 penetrating from the gap portion 13 to the spherical surface of the concave portion 11 are opened as shown in FIG. In this embodiment, 18 pores having a diameter of 0.4 mm are provided. Reference numeral 12 denotes a support arm for making the floating holder have a closed structure and performing opening / closing and transport.
2 is made of stainless steel (SUS310S). The surface of the concave portion and the divided surface of the floating holder 10 are polished to obtain Ir-Pt.
-Coated with a Rh-Au alloy thin film. In addition, many pores 15 of the concave portion are arranged near the division surface.

Hereinafter, an example of forming barium borosilicate glass (transition point: 514 ° C., yield point: 545 ° C.) will be described. Viscosity of about 15 flowing down from the end of the outflow pipe (about 1,000 ° C) in a nitrogen atmosphere atmosphere
Poise's molten glass flow is received by a floating holder heated to 450 ° C., which is jetting 5 l / min of nitrogen gas, and then the floating jig is rapidly lowered by about 10 mm to cut the glass flow and float. The glass was transferred to the temperature control chamber by the support arm while being heated, and the glass viscosity was reduced to 10 by heating with a heater.
Prepared ^6.5 poise (647 ° C.), further Kitashi has directly above the lower mold of the mold, the glass viscosity of the glass gob by opening the support arm to the left and right on the lower mold kept at the corresponding 543 ° C. to l0 ^10.7 poise And the upper mold was immediately lowered to perform press molding. Obtained weight l. The 2 g biconvex lens had no surface defects and had good surface accuracy. In addition, when cooling and observing what was dropped on the lower mold without performing press molding, the glass lump had a lower radius of curvature than the radius of curvature of the spherical part of the floating holder, and the whole was a marble shape The entire surface was a free surface, and almost no surface defects were observed. Then, it dropped to the center of the lower mold without fail.

On the other hand, for comparison with the floating holder of the present invention, the same test as above was carried out using a floating holder (not shown) of the type in which the gap into which the gas flows was opened at the dividing surface. The falling of the glass lump is unstable, and a contact mark is formed around the lower surface of the glass lump.
The r-Pt-Rb-Au film partially peeled off and adhered to the glass block. In this embodiment, the step of receiving molten glass to form a glass lump and the step of adjusting the temperature for press molding were performed with one floating holder. The type floating holder may be separated from the split type floating holder for adjusting the temperature and dropping it to the mold.

Embodiment 2 In this embodiment, a floating holder shown in FIG. 3 was used. In this floating holder 10, the opening angle of the conical surface of the concave portion 11 is 4
0 °. Further, the gap 13 is sealed, and has a structure in which gas does not leak from the division surface when the floating holder is opened in two parts. Further, the bottom of the recess 11 has a gap 13
0.5m in diameter so that the gas introduced into
Each of the left and right holders is provided with one m-sized pore 15. In this embodiment, the material of the floating holder is a cemented carbide hardly containing a metal binder, the inner peripheral surface and the divided surface of the recess 11 are polished, and the surface is coated with a noble metal film as in the first embodiment.

In this embodiment, a glass drop was dropped from the outflow pipe onto the floating holder. The glass droplet is rotated by floating to become a true sphere.
00 mg of microlenses were press molded. Although the ascent and drop were good, the ball was light in weight, and when falling into the lower mold, it sometimes bounced and jumped out of the lower mold, so it was guided by a funnel-shaped funnel shown in FIG. This has made it possible to stably supply the material onto the lower mold.

Embodiment 3 In this embodiment, a floating holder shown in FIG. 5 was used. The diameter of the pore 15 on the bottom surface of the recess 11 was set to 0.6 mm (FIG. 5).
(A)), each of the left and right divided surfaces is provided with one horizontal hole 25 (FIG. 5 (b)). The material of the floating holder 10 is a material obtained by processing high-density carbon to a surface roughness of 5 μm Rmax or less and impregnating glassy carbon from the surface to a depth of about 1 mm (Nisshinbo, glassy carbon coat). In the present embodiment, the opening angle of the conical surface of the concave portion 11 is set to 90 °.

In the present embodiment, a method is employed in which a glass preform that has been once cooled is reheated and molded instead of directly performing precision molding from molten glass. In the production of the preform, a floating holder (not shown) which is not a so-called split type is used, and the falling glass is received and cooled by the floating holder, so that the marble l.
5 g of a preform were obtained. The preform thus obtained was reheated and softened by the floating holder shown in FIG. 5 to form a glass lump. The glass is barium borosilicate glass (transition point 514 ° C, yield point 545)
° C). The molding apparatus was in a 98% N ₂ + 2% H ₂ gas atmosphere, and the preform preheated to 450 ° C. was 0.5 l / l.
min. 98% N ₂ + 2% H ₂ gas is about 6
Put to 00 ° C. floating retainer and heated to 628 ° C. (glass viscosity l0 ⁷ poises) by upper and lower heaters in the furnace.

The preform softened while floating, and rotated with respect to the central axis of the conical surface of the concave portion 11. Thereafter, the support arm 12 was transported immediately above the lower mold, the support arm 12 was opened right and left, and the preform was dropped on the lower mold. The buoyancy decreases at the moment of opening, but no fusion occurs because the gas is ejected upward, the preform descends along the dividing surface, and when the opening width becomes larger than the preform diameter It fell from the floating holder 10 (FIG. 5A). In this embodiment, since the horizontal hole 25 is provided at the center of the division surface of the floating holder (FIG. 5B), the effect of preventing the fusion of the preform is further enhanced. After that, when cooled and observed without press molding, under these conditions, deformation due to softening was slight, and there was no surface defect.

As a mechanism for simultaneously opening and closing the floating holder in the left and right directions, for example, a push-up mechanism using a cam may be provided on a side of the support arm opposite to the position where the floating holder is located. As described above, the preform separated from the floating holder is dropped on the lower mold of the mold maintained at 550 ° C. (a temperature corresponding to a glass viscosity of ^10.2 poise) and immediately press-molded by the upper mold. Was. The surface quality of the resulting convex meniscus lens was good without defects, and the surface accuracy was also good.

Example 4 A convex meniscus lens was manufactured under the same conditions as in Example 3 except that a floating holder having a different material was used. Table 1 shows the materials of the floating holder used.

[0042]

[Table 1]

Good results were obtained for the floating holders using the materials shown in Table 1. In addition, fusion occurred in silicon carbide, quartz glass, and stainless steel used for comparison. From these results, it can be said that the floating due to the airflow of the softened glass is not completely floating without contact with the floating holder, but is sometimes floating with some contact. it can. Therefore, it is preferable to use a material to which the softened glass does not easily fuse as the floating holder.

[0044]

According to the method for producing softened glass by floating holding according to the present invention, when the floating holder is divided and opened to drop the glass lump and transport it to the next step, the glass lump is floated from below. Even after the levitation holder has been divided and released, the amount of gas blown out is maintained at the same level or 80% or more as before the release. Is not caused, and glass fusing or contact damage to the floating holder is not caused.

Further, according to the floating holder of the present invention, a closed space is provided in the floating holder, and a gas is blown out from the gap above the floating holder to float and hold the glass block. Therefore, when the floating holder is divided and opened, it is possible to effectively prevent the gas flow that should be spouted upward from flowing in the other direction, and maintain the floating force necessary for dropping the ideal glass block. Therefore, it is possible to prevent glass fusing and contact damage to the floating holder.

Further, according to the floating holder of the present invention, since the floating holder is formed of the porous member and the airtight member covering other than the upper surface of the porous member, the floating holder is divided when the floating holder is released. In addition, since the gas does not escape from the divided surface and a sufficient floating force of the glass lump can be secured, it is possible to prevent glass fusing and contact damage to the floating holder.
Further, in the floating holder of the present invention, a lateral hole for ejecting an appropriate amount of gas from the divided surface of the holder is provided, or
By forming a conical or concave concave portion at the center of the concave surface, or by cutting the upper edge of the dividing surface at a predetermined angle, the glass block can be prevented from dropping when the holding fixture is divided and opened. Appropriate regulation can prevent fusion of the glass lump and contact flaws on the floating holder more effectively.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view and a plan view showing a floating holder of the present invention.

FIG. 2 is a sectional view showing a floating holder of the present invention.

FIG. 3 is a cross-sectional view and a plan view showing a floating holder of the present invention.

FIG. 4 is a sectional view showing a floating holder of the present invention.

FIG. 5 is a cross-sectional view showing a floating holder of the present invention and a view showing a divided exposed surface of the floating holder.

FIG. 6 is a cross-sectional view and a plan view showing a floating holder of the present invention.

FIG. 7 is a cross-sectional view and a plan view showing a floating holder of the present invention.

FIG. 8 is a diagram showing a conventional technique.

FIG. 9 is a diagram showing a conventional technique.

FIG. 10 is a diagram showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Floating holder 11 Concave part 12 Support arm 13 Void part 14 Gas introduction pipe 15 Micropore 16 Molten glass lump 21 Porous member 22 Airtight member 23 Lower mold 24 Funnel 25 Side hole

Claims (14)

[Claims] 1. A glass lump is formed by receiving molten glass dripped or flowing down on a holder that can be divided into a plurality of parts having means for ejecting an airflow upward, in a state of being floated by the airflow. And a method of manufacturing a softened glass including a step of transferring the glass lump to a next step by dropping the glass lump from a gap between the holders formed by the division, and upward from the holder. A method for producing a softened glass, characterized in that the amount of the jetted airflow is maintained at 80% or more of that before the division even after the holder is divided. 2. A glass lump is heated and softened while being floated by the airflow on a holder that can be divided into a plurality of parts having means for ejecting an airflow upward, and the holder is divided and divided. A method for manufacturing a softened glass including a step of transferring the glass lump to the next step by dropping the glass lump from the gap of the formed holder, wherein the amount of airflow ejected upward from the holder is reduced. A method for producing a softened glass, wherein the temperature is maintained at 80% or more of the value before splitting even after splitting the holder. 3. The method for producing a softened glass according to claim 1, wherein the next step is a step of press-molding a glass lump. 4. The next step is a step in which the dropped glass block is received by an upwardly flowing airflow on a second holder having means for blowing out an upwardly flowing airflow, and further heated and softened in a floating state. 3. The method according to claim 1, wherein
A method for producing the softened glass according to the above. 5. A jig having a concave curved surface having a plurality of gas ejection holes and capable of being divided into a plurality of pieces, for holding a glass lump in a floating state, wherein the jig is exposed by division (hereinafter, referred to as a divided exposure surface). Does not have a gas ejection hole, or the divided exposure surface has a gas ejection hole, and the gas ejection amount from the divided exposure surface after dividing the gas ejection hole is gas ejection from the concave curved surface. A floating holder for softened glass, characterized in that the amount is 20% or less of the amount. 6. The holding tool has a cavity inside which communicates with an ejection gas introduction pipe, and the gas ejection hole is formed by a pore penetrating from the cavity to a concave curved surface and a divided exposure surface. The floating holder according to claim 5, wherein 7. The floating holder according to claim 5, wherein the diameter of the pore is 0.2 mm or more. 8. The floating holder according to claim 6, wherein the number of pores provided on the concave curved surface per unit area is higher at the center portion than at the periphery of the concave curved surface. 9. The floating holder according to claim 6, wherein a fine hole penetrating through the divided exposed surface is provided so as to discharge gas obliquely upward. 10. The method according to claim 1, wherein the concave surface is formed of a porous member, the porous member communicates with a jet gas introduction pipe, and the other than the concave surface is covered with an airtight member. 6. The floating holder according to 5. 11. The airtight member serving as a divided exposure surface is provided with pores penetrating from the porous member.
The floating holder according to 0. 12. The floating holder according to claim 11, wherein the fine holes are provided so as to discharge gas obliquely upward. 13. The floating holder according to claim 5, wherein a concave portion having a conical shape or a concave surface is further formed at a central portion of the concave surface of the holder. 14. The floating holder according to claim 5, wherein a notch is formed at an upper edge of the divided exposed surface of the holder.