Columnar glass, method for manufacturing columnar glass, and apparatus for manufacturing columnar glass.

Abstract

The present invention aims to provide a method, an apparatus, and the cylindrical glass obtained by the method for manufacturing cylindrical glass with a small cross-sectional area without grinding and abrasion of the sides. A method for manufacturing cylindrical glass from glass material includes: preparing a cylindrical mold having a first opening and a second opening, the second opening communicating with the first opening and having an opening area smaller than that of the first opening; disposing glass material within the cylindrical mold; heating the disposed glass material to soften it; inserting a first mold having a glass extrusion surface into the first opening so that the glass extrusion surface contacts the glass material; and extruding the softened glass material by moving at least one of the first mold and the cylindrical mold, thereby discharging the glass from the second opening to form a cylindrical glass.

Description

Technical Field

[0001] This invention relates to columnar glass with small cross-sections, a method for manufacturing columnar glass, and an apparatus for manufacturing columnar glass. Prior Technology

[0002] Optical glass is typically obtained as a strip material or a long, thin plate material called an E-bar, which is then shaped into glass products with a specified shape. Specifically, first, a small glass sheet with a relatively simple shape is made with the same glass volume as the target object, and then this small glass sheet is precisely shaped. From an industrial convenience point of view, it is desirable to mass-produce products of the same shape for optical glass; therefore, even when manufacturing such small glass sheets, it is desirable to mass-produce small glass sheets of the same shape.

[0003] An example of a method for manufacturing such small glass sheets can be given as follows: Prepare a long, narrow rectangular glass piece with sides longer than the others. Shape this rectangular glass piece into a cylindrical rod. Then, cut it perpendicular to the height of the cylinder to obtain a small, flat glass sheet (here referring to a disc-shaped or cylindrical shape). Flat glass sheets are better suited for use as materials for optical lenses due to their similar shape.

[0004] As a method for manufacturing small, flat glass sheets as described above, the method in Patent Document 1 can be cited as an example. Patent Document 1 discloses "a method for manufacturing a lens, characterized in that: a glass block heated to a softening temperature above and below the flow temperature is placed between three or more rollers that rotate in the same direction in parallel with each other, forming a glass rod with a predetermined diameter that can be clamped based on the spacing of the rotating rollers, and then the glass rod is cut, shaped, and polished to form a lens with a predetermined radius of curvature."

[0005] Furthermore, Patent Document 2 discloses "a method for manufacturing a glass rod, characterized in that: a glass material with a surface heated to a viscosity of at least 10 10 poise is moved on a guide ramp (groove) and thus guided onto a plurality of rollers arranged parallel to each other and rotating in the same direction, the guide ramp (groove) being arranged parallel to the rotation axis of the rollers, the glass material being shaped into a rod shape with a circular cross-section by rotating the glass material in a direction opposite to the rotation direction of the rollers, the movement of the glass material on the guide ramp (groove) being carried out by the glass material rolling down the guide ramp (groove)".

[0006] Patent document 3 discloses "a method for manufacturing small glass materials for lenses, characterized in that: when manufacturing multiple small glass materials for lenses from a glass rod, a glass rod is inserted between two rollers rotating in the same direction, the gap between the two rollers is reduced, and the glass rod heated to above the softening temperature is squeezed from both sides. Multiple flange-shaped blades are arranged at equal intervals in the axial direction on at least one of the two rollers to simultaneously form multiple circumferential grooves on the glass rod. Then, each groove of the glass rod is cut to form small glass materials of equal weight suitable for lenses." [Existing Technical Documents] [Patent Literature]

[0007] Patent Document 1: Japanese Patent Application Publication No. 54-117514; Patent Document 2: Japanese Patent Application Publication No. 2000-16822; Patent document 3: Japanese Patent Application Publication No. 2002-114532. Summary of the Invention

[0008] [The problem the invention aims to solve]

[0009] As shown in Patent Documents 1 to 3, methods for manufacturing cylindrical glass (hereinafter also referred to as cylindrical glass) as a material for flat small glass sheets are being widely developed. On the other hand, there is a high demand for miniaturized glass products, and in the field of optical lenses, there is also a requirement for smaller lens diameters. If the cross-sectional diameter of the cylindrical glass used as an optical lens material can be made close to the diameter of the optical lens as the final product, the time and amount of glass cutting on the sides of the cylindrical glass can be reduced. This reduces glass manufacturing costs and minimizes the amount of glass shards (debris) generated during glass cutting, which is also beneficial to the environment.

[0010] Patent Document 1 does not specify the diameter of the round glass rod immediately after it is formed. Furthermore, while Patent Document 2 discloses a round glass rod with a diameter of 6 mm in paragraph

[0061] , it does not disclose round glass rods with a smaller diameter. Moreover, while Patent Document 3 discloses a round glass rod with a diameter of 7 mm in paragraph

[0029] , it does not disclose round glass rods with a smaller diameter. Furthermore, as mentioned above, Patent Documents 1 to 3 do not disclose cylindrical glass with a diameter of 6 mm or less because it is impossible to manufacture cylindrical glass with a diameter of 6 mm or less (e.g., 3.5 mm or less) using only the technology described in Patent Documents 1 to 3. In the case of forming with three rollers, when the roller diameter is 40 mm, structurally only cylindrical glass with a minimum diameter of 6.5 mm can be manufactured; when the roller diameter is 20 mm, structurally only cylindrical glass with a minimum diameter of 3.5 mm can be manufactured. However, it is believed that when the roller diameter is 20 mm, the roller itself will be damaged by pressure. Although shortening the roller length to withstand pressure is considered, it is impossible to manufacture long cylindrical glass under such conditions. Therefore, the technical solutions described in Patent Documents 1 to 3 cannot manufacture cylindrical glass with a specified length of 3.5 mm or less in diameter.

[0011] Furthermore, the technology in Patent Documents 1 to 3 can only manufacture round rod glass with a circular cross-section. If it can also manufacture columnar glass with triangular, quadrilateral, or other cross-sections, the application range of the manufacturing device will be expanded, which is preferable. [Solutions for solving the problem]

[0012] The inventors conducted research on the above-mentioned problems and developed a manufacturing method that can produce columnar glass with small cross-sectional area from block-shaped solidified glass without cutting, and can be formed into various cross-sectional shapes, thus completing the present invention. That is, the present invention includes the following contents. [1] A method for manufacturing columnar glass, comprising: manufacturing columnar glass from glass material, including: The step of preparing a cylindrical mold having a first opening and a second opening, wherein the second opening communicates with the first opening and has an opening area smaller than that of the first opening; The step of placing the glass material inside the cylindrical mold; The step of heating the prepared glass material to soften it; The step of inserting a first mold having a glass extrusion surface into the first opening to bring the glass extrusion surface into contact with the glass material; and The step of extruding glass from the second opening to form cylindrical glass by moving at least one of the first mold and the cylindrical mold to compress softened glass material. [2] According to the columnar glass manufacturing method described in [1], wherein, The cylindrical mold has a second mold inside, and the second mold has a glass channel through which the softened glass material is discharged from the second opening to become the columnar glass. [3] According to the columnar glass manufacturing method described in [2], wherein, The second mold has one or more of the glass channels. [4] The method for manufacturing columnar glass according to any one of [1] to [3], wherein, The columnar glass has a polygonal, circular, or elliptical cross-section. [5] A columnar glass manufacturing apparatus, comprising: A cylindrical mold having a first opening and a second opening, wherein the second opening communicates with the first opening and has an opening area smaller than that of the first opening; A first mold for extruding glass material disposed inside the cylindrical mold, having a glass extrusion surface capable of being inserted into the cylindrical mold from the first opening; An extrusion unit is used to extrude the first mold into the glass material; and A heating unit is used to soften the glass material. [6] The columnar glass manufacturing apparatus according to [5], wherein, The cylindrical mold has a second mold inside, the second mold having a glass channel, the second mold being configured to allow softened glass material to be discharged through the glass channel from the second opening to become the cylindrical glass. [7] A columnar glass having an arithmetic mean roughness Ra of 0.001 to 0.20 μm and a ten-point mean roughness Rz of 0.01 to 1.2 μm on its side surface. [8] The columnar glass according to [7], wherein, The difference between the crystallization peak temperature Tc and the temperature at logη=5.3 ((crystallization peak temperature Tc) - (temperature at logη=5.3)) is above 0℃. [9] The columnar glass according to [7] or [8], wherein, The shapes of the vertical cross-sections relative to the length direction are the same or approximately the same.

[10] A method for manufacturing columnar glass, comprising: manufacturing columnar glass from glass material, including: The step of preparing a cylindrical mold having at least one opening; The step of inserting the glass extrusion surface of the mold, which has a glass extrusion surface, into the cylindrical mold while the glass material is in contact with the mold through the opening; The steps of heating and softening the glass material; and The step of extruding the glass material as a columnar glass from a glass outlet provided in the mold by moving at least one of the mold or the cylindrical mold.

[11] According to the method for manufacturing columnar glass described in

[10] , wherein, The mold has a glass channel through which the extruded glass is discharged as the columnar glass from the glass outlet.

[12] According to the columnar glass manufacturing method described in

[11] , wherein, The mold has one or more of the glass channels.

[13] According to the method for manufacturing columnar glass described in

[10] , wherein, The columnar glass has a polygonal, circular, or elliptical cross-section.

[14] A columnar glass manufacturing apparatus, comprising: A cylindrical mold having at least one opening; A mold for extruding glass material into the interior of the cylindrical mold, insertable into the cylindrical mold through the opening, and having a glass outlet for discharging glass during extrusion; An extrusion unit for extruding glass material using the mold; and A heating unit is used to soften the glass material.

[15] A method for manufacturing columnar glass, comprising: manufacturing columnar glass from glass material, including: The step of preparing a cylindrical mold having a first opening and a second opening communicating with the first opening, wherein a second mold is provided inside the cylindrical mold; The step of placing the glass material inside the cylindrical mold; The step of heating the prepared glass material to soften it; The step of inserting a first mold having a glass extrusion surface into the first opening to bring the glass extrusion surface into contact with the glass material; and The step of extruding glass from the second opening to form cylindrical glass by extruding softened glass material through moving at least one of the first mold and the cylindrical mold.

[16] According to the columnar glass manufacturing method described in

[15] , wherein, The second mold has a glass channel through which softened glass is discharged from the second opening to become the columnar glass.

[17] According to the columnar glass manufacturing method described in

[16] , wherein, The second mold has one or more of the glass channels.

[18] According to the columnar glass manufacturing method described in

[16] , wherein, The columnar glass has a polygonal, circular, or elliptical cross-section.

[19] A columnar glass manufacturing apparatus, comprising: A cylindrical mold having a first opening and a second opening communicating with the first opening; A first mold for extruding glass material disposed inside the cylindrical mold, having a glass extrusion surface capable of being inserted into the cylindrical mold from the first opening; An extrusion unit is used to extrude the first mold into the glass material; The second mold is disposed inside the cylindrical mold; and A heating unit is used to soften the glass material.

[20] The columnar glass manufacturing apparatus according to

[19] , wherein, The second mold has a glass channel for discharging glass material.

[21] The columnar glass manufacturing apparatus according to

[20] , wherein, The second mold has one or more of the glass channels. [Invention Effects]

[0013] The method for manufacturing columnar glass of the present invention enables the production of columnar glass without grinding or polishing the sides. Furthermore, by changing the shape of the second opening and the glass channel through which the glass is discharged, the cross-sectional shape of the resulting columnar glass can be altered. Moreover, by increasing the number of second openings and glass channels, multiple columnar glass pieces can be obtained simultaneously. The resulting cylindrical glass naturally has no grinding damage and can be shipped directly from the factory. By making the cross-section circular and cutting the cylindrical glass approximately perpendicular to its length, the cut glass can be used directly as lens material, and glass lens material of a specified size can be manufactured while minimizing the amount of glass cut, i.e., glass waste. Furthermore, since the columnar glass manufacturing method of the present invention can manufacture columnar glass without raising the temperature to a temperature that facilitates crystallization, it can suppress crystallization inside the glass and obtain high-quality columnar glass. Simple Explanation of the Diagram

[0014] Figure 1 shows a schematic cross-sectional view of the apparatus D1 for manufacturing columnar glass. Figure 2 shows a schematic cross-sectional view of the manufacturing apparatus D2 for columnar glass. Figure 3 shows a cross-sectional view formed along a line perpendicular to the length direction of the manufacturing apparatus D2 (III in Figure 1). Figure 4 shows the manufacturing of columnar glass using the columnar glass manufacturing apparatus D4. Figure 5 shows an example of the second mold. Figure 6 shows the state of the discharged cylindrical glass being stretched using guide roller 7. Figure 7 shows a schematic cross-sectional view of apparatus D3 for manufacturing columnar glass. Figure 8 shows a graph of differential scanning calorimetry (DSC) for typical glass. Figure 9 is a magnified side view of Example 1. Figure 10 shows a schematic cross-sectional view of apparatus D4 for manufacturing columnar glass. Figure 11 shows a schematic cross-sectional view of apparatus D5 for manufacturing columnar glass. Implementation

[0015] Detailed Implementation

[0016] In this specification, unless otherwise specified, the "~" symbol used for specific numerical ranges indicates that both the upper and lower limits are included in the range.

[0017] [Method and apparatus for manufacturing columnar glass] The present invention discloses a method for manufacturing columnar glass from cured glass material, comprising: preparing a cylindrical mold having a first opening and a second opening, the second opening communicating with the first opening and having an opening area smaller than that of the first opening; disposing of glass material within the cylindrical mold; heating the disposed glass material to soften it; inserting a first mold having a glass extrusion surface into the first opening such that the glass extrusion surface contacts the glass material; and extruding the softened glass material through the second opening by moving at least one of the first mold and the cylindrical mold to form columnar glass. The following is a detailed description with reference to the accompanying drawings.

[0018] As shown in Figures 1 and 2, the manufacturing apparatuses D1 and D2 of the present invention include a cylindrical mold 3, which can contain a solid glass material 1. The cylindrical mold 3 can be a single unit or, as shown in Figures 1 and 2, divided into a cylindrical mold side portion 31 and a cylindrical mold discharge portion 32. Furthermore, the cylindrical mold discharge portion 32 can be a component with a glass discharge channel 35 communicating with the glass channel 41 of the second mold 4, as in manufacturing apparatuses D1 and D2, or it can be a cylindrical cavity as described later in manufacturing apparatuses D4 (Figure 10) and D5 (Figure 11).

[0019] The cylindrical mold 3 may have a container 5 inside as shown in Figure 1, or it may not have a container as shown in Figure 2. For ease of explanation, the manufacturing apparatus D2 without a container (Figure 2) will be explained first, and then the container 5 will be explained using Figure 1. As shown in Figure 2, the cylindrical mold 3 has a first opening 33 and a second opening 34. The second opening 34 communicates with the first opening 33 and has an opening area smaller than that of the first opening 33. That is, the cylindrical mold 3 has two openings and an internal space that connects the first opening 33 and the second opening 34, allowing the material glass 1 to be placed within it. The cross-sectional shape of the internal space can be circular, elliptical, or polygonal; a circular shape is preferred to reduce glass residue remaining inside after molding. Furthermore, the shape of the outer side of the cylindrical mold 3 is not particularly limited, but a cylindrical or polygonal cylindrical shape is preferred.

[0020] The first opening 33 is an opening for inserting the glass material 1 in a solid state, and the first opening 33 is also an opening for inserting the first mold 2 after the glass 1 is inserted. The second opening 34 is an opening for discharging the softened glass material 1 from the cylindrical mold 3 into a cylindrical shape. Therefore, in embodiments D1 and D2, the shape of the second opening 34 is preferably the same as the cross-sectional shape of the discharged cylindrical glass 11. For example, if the cylindrical glass is to be a cylindrical bar, the cross-sectional shape of the second opening 34 is preferably circular. The area of ​​the cross-section of the second opening 34 is preferably such that the glass material 1 fed in as material will not fall downwards. Furthermore, there may be one or more second openings 34. To manufacture columnar glass, it is preferable to have a glass discharge channel 35 communicating with the second opening 34. A glass discharge channel 35 of a predetermined length allows for stable glass shape during discharge.

[0021] In this invention, a container 5 can be included as needed. The manufacturing apparatus D1 in Figure 1 is provided with the container 5. The container 5 can be disposed inside the cylindrical mold 3 in a tightly fitted state. For example, if the internal spatial cross-section of the cylindrical mold 3 is circular, then the shape of the cross-section of the container 5 perpendicular to the length direction is also circular, resulting in a tightly fitted state as shown in Figure 1. Figure 3 shows the cross-sectional shape when cut with the III shown in Figure 1, which is in a tightly fitted state. Due to the tight fit, heat from the outside can be easily conducted to the internal material glass 1. The cross-sectional shape of the interior of container 5 is the same as that of the interior of cylindrical mold 3, and can be circular, elliptical, or polygonal. In order to press the first mold 2 into the second mold 4, the cross-sectional shape of the interior of container 5, except for the annular notch 52 described later, is preferably approximately the same at any position (height). The interior surface of the cylindrical mold 3 of the compressed material glass 1 is easily degraded by heating and pressure. Therefore, by arranging a container 5 inside that can be separated from the cylindrical mold 3, even if damaged, only container 5 needs to be replaced to obtain an interior surface without deterioration. In addition, the container 5 has a container first opening 51, and when using the manufacturing apparatus D1, the material glass 1 and the first mold 2 are inserted from the container first opening 51 (refer to Figure 1) located inside the first opening 33.

[0022] The manufacturing apparatus D1 and D2 of the present invention require a first mold 2. The first mold 2 has a first mold glass extrusion surface 21. The shape of the first mold glass extrusion surface 21 is preferably such that it can be inserted into the first opening 33 and the first opening 51 of the container, and has a gap that prevents glass leakage when compressing the material glass 1. If the gap is not suitable, the glass may leak out from the gap between the first mold 2 and the cylindrical mold 3 (or the container 5) during extrusion.

[0023] Furthermore, the downward extrusion of the first mold 2 (in the direction of the arrow in Figure 1) is usually performed by extruding the first mold 2 using an extrusion unit (not shown). However, it is also possible to extrude the internal material glass 1 by fixing the first mold 2 and moving the cylindrical mold 3 upward. Alternatively, it is possible to extrude the material glass 1 by rotating the manufacturing apparatus D1 and D2 90° vertically and moving the first mold 2 and / or the cylindrical mold 3 laterally. Both manufacturing apparatuses D1 and D2 can perform this extrusion method. Here, the method of extrusion by fixing the cylindrical mold 3 and moving the first mold 2 downward will be explained.

[0024] The manufacturing apparatuses D1 and D2 of the present invention include a second mold 4 as needed. The second mold 4 is located at the lowest part inside the cylindrical mold 3 and is locked in place. In the case of manufacturing apparatus D1, since there is a container 5, the second mold 4 is positioned at the lowest part of the container 5. The second mold 4 can be separated from the cylindrical mold 2 and the container 5. The second mold 4, located at the bottom of the innermost part of the cylindrical mold 3, has a second mold glass extrusion surface 43 on its upper surface that comes into contact with the glass 1. Due to the large pressure applied, it is one of the most damaged parts. However, by being able to separate it, the damaged second mold 4 can be replaced with an undamaged mold. The second mold 4 has a glass channel 41. The glass channel 41 is a channel that connects the interior of the container 5 (the glass extrusion surface 43 of the second mold) with the glass discharge channel 35 and the second opening 34. The shape of the glass channel 41 is not particularly limited, but from the perspective of stabilizing glass discharge, it is preferable to have the same shape as the glass discharge channel 35 of the cylindrical mold 3.

[0025] Furthermore, there are no particular restrictions on the cross-sectional shape and number of glass channels 41 in the second mold 4. Figure 5(a) shows the second mold 4 used in Figure 1, with a glass channel 41 having a circular cross-section formed in the center. Additionally, the second mold 4 shown in Figure 5(b) has five glass channels 412 formed. Therefore, five columnar glass pieces can be manufactured using the second mold in Figure 5(b). In Figure 5(c), the glass channel 413 has a triangular cross-section, and in Figure 5(d), the glass channel 414 has a long, narrow rectangular cross-section. By using these second molds, triangular prism glass and plate glass can be manufactured respectively. In addition, when using the second mold as shown in Figures 5(b) to (d), it is preferable that the glass discharge channel 35 and the second opening 34 are also of corresponding shapes. The end of the glass extrusion surface 43 of the second mold 4 has an annular notch 42 formed on its outer periphery, which engages with the annular notch 52 formed on the inner periphery of the container 5 to suppress glass leakage.

[0026] The manufacturing apparatus D1 to D5 of the present invention can use two guide rollers 7 to stretch the discharged cylindrical glass 11 downwards as needed (see Figure 6). The guide rollers 7 consist of two discs, which clamp the cylindrical glass 11 between them and guide it in a predetermined direction. Without the guide rollers 7, in the initial stage of discharge of the cylindrical glass 11, the downward stretching force is small because the amount of glass discharged is small. However, as discharge progresses, the weight increases due to the increased amount of glass discharged, thus increasing the downward stretching force, and sometimes causing the cylindrical glass 11 to elongate and thin. However, by using two guide rollers 7 rotating at a fixed speed, the cylindrical glass 11 can be stretched at a fixed speed, thereby suppressing deformation of the cross-sectional shape of the cylindrical glass 11 and enabling stable manufacturing of the cylindrical glass. As shown in Figure 6, guide roller 7 causes the two disks to rotate relative to each other in a manner that stretches the glass downwards.

[0027] Figure 7 shows a manufacturing apparatus D3 according to another aspect of the present invention. In D3, a cylindrical mold 3 with a closed upper part is used. Above the interior of the cylindrical mold 3, there is a first mold 2 integral with the cylindrical mold 3. The lower part of the cylindrical mold 3 is open, allowing the insertion of a second mold 4 with a through glass channel 41. The second mold 4 is supported by one or more telescopic parts 8 (composed of a first telescopic part 81 and a second telescopic part 82) in a position that does not interfere with the exit of the glass channel 41. As long as the telescopic parts 8 can raise the second mold 4 and the glass material 1 disposed above the second mold 4, this method is not limited, and various lifting mechanisms can be used.

[0028] The manufacturing apparatus D3 is designed to fix the cylindrical mold 3 and raise the second mold 4. However, it can also be designed to compress the glass material 1 by using the telescopic part 8 to fix the second mold 4 and lower the cylindrical mold 33. In addition, similar to manufacturing devices D1 and D2, manufacturing device D3 has a heating unit around the cylindrical mold 3, which can heat the glass inside.

[0029] The manufacturing apparatus D4 in Figure 10 and the manufacturing apparatus D5 in Figure 11 differ from manufacturing apparatuses D1 and D2 in that the cylindrical mold discharge section 32 is not configured as a component, but rather as a cylindrical cavity. Therefore, the second opening 34 of manufacturing apparatuses D4 and D5 has a large opening area, and the opening shape of the second opening 34 of D4 does not need to be the same as the cross-sectional shape when the resulting cylindrical glass is cut perpendicular to its length. The glass discharged from the glass discharge port 44 of the second mold 4 is stretched into a cylindrical shape in the length direction and discharged from the second opening 34 via the cylindrical mold discharge section 32. The cross-sectional shape of the columnar glass obtained using manufacturing apparatuses D4 and D5 is the same as the shape of the glass outlet 44. Furthermore, the second mold modification examples in Figures 5(b) to (d) and the roller in Figure 6 can also be applied to manufacturing apparatuses D1 to D5.

[0030] [Manufacturing Method] Next, the manufacturing method of the columnar glass 11 of the present invention will be described using Figure 4. In the manufacturing apparatus D4 used in Figure 4, a block of material glass 1 of a specified size is fed into the first opening and is pressed from above to below by the first mold 2. The glass material 1 can be loosely contained inside the container 5 before extrusion. After inserting the glass material 1 of a specified size into the container 5, the first mold 2 is positioned at the first opening 51 of the container from the top (Figure 4(a)). Furthermore, in the manufacturing method of the present invention, since the high temperature required to melt the glass material 1 is not reached, no release agent such as powdered boron nitride (BN) is added. Therefore, the manufacturing method of the present invention is very suitable for glass that is sensitive to changes in glass composition. Although it is preferred not to use a release agent, it can be used as appropriate as long as it does not hinder use.

[0031] Next, the glass material 1 is heated by a heating unit (not shown). The heating unit heats the material from the outside of the first mold 2 and the cylindrical mold 3 using a predetermined method such as a burner. This softens the glass material 1. By pressing the softened material glass 1 downwards, the material glass 1 is deformed. Even if the glass is not in a shape that fits tightly against the inside of the cylindrical mold 2 when inserted, it can be expanded in the vertical direction (lateral direction) relative to the length direction by pressing, and the glass is filled in the lateral direction without gaps (Figure 4(b)). At this point, the viscosity of the glass is approximately 1.0 × 10⁴ Pa·s to 5.0 × 10⁵ Pa·s.

[0032] As the pressure continues to increase, the glass is discharged as columnar glass 11 (Figure 4(c)).

[0033] There are no particular restrictions on the temperature suitable for extrusion, as long as the glass can be deformed by extrusion. However, it is preferable to set the viscosity of the glass to be between 1.0 × 10⁴ Pa·s and 5.0 × 10⁵ Pa·s. For example, the specific temperature of the glass in this case is 500 to 900 °C.

[0034] There are no particular limitations on the discharge speed, i.e., the extrusion speed, of the discharged columnar glass 11. For example, it can be a speed of 1 to 30 mm / min, or for example, a speed of 1 to 20 mm / min. If the discharge speed is faster than this range, the extrusion pressure is too high, and there is a risk that the glass material 1 will break before deformation. If the discharge speed is slower than this range, the manufacturing speed is too slow and the efficiency is low.

[0035] The pressure applied to the glass material 1 is preferably 1.5 to 50 MPa. Furthermore, since a fixed extrusion speed is preferably used when manufacturing this columnar glass 11, the load and pressure are preferably adjusted accordingly to the extrusion speed.

[0036] Although not shown in the figure, it is preferable to place a heat-resistant sheet between the first mold glass extrusion surface 21 of the first mold 2 and the glass material 1. This prevents glass from intruding into the gap between the container 5 and the first mold 2. Examples of heat-resistant sheets include carbon-containing sheets, specifically expanded graphite sheets.

[0037] For manufacturing apparatuses D1, D2, and D5, columnar glass can also be manufactured under the same conditions as D4 described above.

[0038] In the manufacturing apparatus D3 shown in Figure 7, manufacturing is carried out by the following method. That is, the manufacturing method using manufacturing apparatus D3 includes: a step of preparing a cylindrical mold having at least one opening; a step of placing the glass material on the glass extrusion surface of the mold, the mold having the glass extrusion surface and a glass channel penetrating the mold from the glass extrusion surface; a step of extruding the glass material with the mold by inserting the mold containing the glass material into the cylindrical mold through the opening and moving the mold or at least one of the cylindrical molds; and a step of extruding the extruded glass through the glass channel from the opening to form a cylindrical glass.

[0039] The specific manufacturing method using manufacturing apparatus D3 will be described using Figure 7. Glass material 1 is placed above the second mold 4. The second mold 4 has a second mold glass extrusion surface 43 and a glass channel 41. With the glass material 1 placed on it, the second mold 4 and the glass material 1 on the second mold 4 are raised by the extension telescopic part 8. The lower opening of the cylindrical mold 3 allows the second mold 4 to be inserted into it. By the rising of the second mold 4 and the glass material 1 on it, the second mold 4 and the glass material 1 on it are inserted into the cylindrical mold 33. Although not shown, the glass inside the cylindrical mold 33 is heated to a temperature suitable for molding by a heating unit. The telescopic section 8 is raised further until the second mold 4 and the glass material 1 disposed on the second mold 4 come into contact with the first mold 2 disposed in the upper part (opposite to the opening) inside the cylindrical mold 3. As it rises further, the heated glass material 1 deforms, causing the columnar glass 11 to be discharged from the glass outlet 44 communicating with the glass channel 41 and the opening of the cylindrical mold 3.

[0040] [Columnar glass] The columnar glass 11 obtained by the manufacturing apparatus and manufacturing method of the present invention will be described. In one embodiment of the present invention, one or more columnar glass 11 are obtained corresponding to a material glass 1 inserted into the manufacturing apparatus. That is, the glass volume of the material glass 1 is substantially the same as the volume of the obtained columnar glass 11 (except where a portion of the material glass 1 remains inside the manufacturing apparatus).

[0041] The cross-sectional shape of the cylindrical glass 11 depends on the shape of the second opening 34 or the glass outlet 44 of the second mold 4. That is, if the shape of the second opening 34 or the glass outlet 44 of the second mold 4 is circular, a cylindrical glass 11 with a circular cross-section is obtained. In addition, by changing the shape of the second opening 34 or the glass outlet 44 of the second mold 4, it is also possible to form polygonal cross-sections such as triangles and quadrilaterals, or elliptical cross-sections.

[0042] The columnar glass 11 obtained by the present invention is characterized by a very small cross-sectional area. This is defined by the cross-sectional area. The cross-sectional area can be, for example, 50 mm² or less, for example, 40 mm² or less, and furthermore, 30 mm² or less.

[0043] The columnar glass 11 has a surface that allows it to be shipped directly from the factory without grinding. Because it is unground, it can suppress glass breakage. The surface of the cylindrical glass 11 obtained by the manufacturing method of the present invention can be shipped even in an unpolished state. For example, multiple precision extruded glass materials (sometimes called preforms) can be produced simply by dividing the cylindrical glass. In the unpolished state, the arithmetic mean roughness Ra is 0.001~0.20 μm, and the ten-point mean roughness Rz is 0.01~1.2 μm. In this specification, the arithmetic mean roughness Ra and the ten-point mean roughness Rz are values ​​measured by a surface roughness and profile shape measuring instrument (Tokyo Seimitsu Corporation, SURFCOM 2900 SD3-12). In addition, the arithmetic mean roughness Ra and the ten-point mean roughness Rz are measured by scanning the side surface of the cylindrical glass parallel to the length direction. The columnar glass 11 obtained by the manufacturing method of the present invention sometimes has straight stripes in the length direction. This is because it is formed by extruding softened glass under pressure. Due to the straight stripes in the length direction, the cutting blade has an anti-slip effect during the cutting process to divide the columnar glass into multiple pieces. In addition, as mentioned above, since no mold release agent is required, no foreign matter from the mold release agent will appear on the surface or inside of the glass.

[0044] Furthermore, the columnar glass 11 obtained by the manufacturing method of the present invention can be manufactured with a uniform or substantially uniform cross-sectional shape. In a columnar glass 11, the ratio (maximum area / minimum area) of the cross-sectional shape with the largest area to the cross-sectional shape with the smallest area is preferably 1.2 or less, and more preferably 1.1 or less.

[0045] Furthermore, in the manufacturing method of the present invention, the glass material for which the difference between the crystallization peak temperature and the temperature at logη=5.3 ((crystallization peak temperature (Tc℃)) - (temperature at logη=5.3℃)) is preferably 200℃ or less is preferred. In addition, the difference between the crystallization peak temperature and the temperature at logη=5.3 is preferably greater than 0℃, more preferably 50℃ or more, and further preferably 100℃, 150℃, and 200℃ or more, sequentially. Generally, a large difference between the crystallization peak temperature and the temperature at logη=5.3 makes devitrification during molding less likely. From this perspective, the difference between the crystallization peak temperature and the temperature at logη=5.3 is preferably greater than 0°C, more preferably greater than 50°C, and further preferably greater than 100°C, 150°C, and 200°C, as described above. On the other hand, even for glasses where the difference between the crystallization peak temperature and the temperature at logη=5.3 is less than 200°C, devitrification during molding according to the present invention can be suppressed. Therefore, the combination of the method of the present invention and glass with a crystallization peak temperature less than 200°C from logη=5.3 is preferred. Such glass exhibits high stability in the viscous region and can be suitably manufactured using the manufacturing method and apparatus of this invention. Furthermore, Figure 8 shows a differential calorimetric analysis chart of a typical glass, with the crystallization peak temperature being Tc. For glasses with high thermal stability and difficulty in crystallization during heating, no clear crystallization peak will appear in the DSC curve, or even if a crystallization peak exists, the difference between the crystallization peak temperature Tc and T(logη=5.3) will be a large value. On the other hand, glasses with Tc-T(logη=5.3) below 200°C are prone to devitrification when heated, softened, and formed, and their devitrification resistance is insufficient. However, according to the present invention, high-quality columnar glass can be obtained without devitrification. Therefore, as a forming method for glass with Tc-T(logη=5.3) below 200°C, the columnar glass manufacturing method of the present invention has particular advantages.

[0046] Example A columnar glass with a volume of 22 cm³, cured at room temperature, was manufactured using the manufacturing apparatus D1 shown in Figure 1. In D1, the cross-sections of the glass channel 41 and the glass discharge channel 35 are sized to match the shape of the cross-section of the manufactured columnar glass. Furthermore, a 1.5 mm thick expanded graphite sheet is disposed between the first mold glass extrusion surface 21 of the first mold 2 and the material glass 1. The conditions are as follows. Furthermore, although heating is performed to soften the glass, the temperature is appropriately adjusted to keep it within the viscosity range described below. Additionally, in Table 1, the range of crystallization peak temperatures (Tc) - (temperature at logη = 5.3) [°C] is recorded for glasses that are relatively difficult to crystallize and have a slightly larger deviation in crystallization peak temperature among those that are easily crystallized. Glass used: Optical glass 1-4 (the resulting columnar glass shapes are shown in Table 1 below) Speed: 10 mm / min; Load: 770~12315N; Temperature: 550~860℃; Glass viscosity: 2.0×10⁴ Pa·s ~ 1.0×10⁵ Pa·s.

[0047] [Table 1]

[0048] (result) A columnar glass of a specified shape is obtained from any of the glass materials 1 to 4 of the optical glass. Longitudinal striations are observed on the sides of the columnar glass. Furthermore, regarding the columnar glass of Example 1, Ra is 0.025 μm, Rz is 0.845 μm, and no foreign matter such as crystals larger than 3 μm was observed. Additionally, the characteristics of the optical glass 1 of Example 1 are recorded in Table 2, and a magnified photograph of Example 1 is shown in Figure 9.

[0049] [Table 2]

[0050] 1: Material: Glass 11: Cylindrical glass 2: First mold 21: First mold glass extrusion surface 3: Cylindrical mold 31: Side of cylindrical mold 32: Cylindrical mold discharge section 33: First Opening 34: Second opening 35: Glass removal channel 4: Second mold 41, 412, 413, 414: Glass passageway 42: Annular notch 43: Second mold glass extrusion surface 44: Glass outlet 5: Container 51: First opening of the container 52: Annular notch 7: Guide rollers 8: Telescopic section 81: First telescopic section 82: Second telescopic section D1~D5: Manufacturing Equipment

Claims

1. A columnar glass manufacturing apparatus comprising: a cylindrical mold having a first opening and a second opening, the second opening communicating with the first opening; a first die for extruding glass material disposed inside the cylindrical mold, having a glass extrusion surface capable of being inserted into the cylindrical mold through the first opening; an extrusion unit for extruding the first die into the glass material; a heating unit for softening the glass material; and guide rollers for stretching the discharged columnar glass downwards.

2. The columnar glass manufacturing apparatus as described in claim 1, further comprising: A second mold, included inside the cylindrical mold, has a glass channel and is configured such that softened glass material is discharged through the glass channel from the second opening to become the cylindrical glass, wherein the second mold is held in place within the cylindrical mold by means of the cylindrical mold in a state that allows it to be separated from the cylindrical mold.

3. The columnar glass manufacturing apparatus as claimed in claim 2, wherein, The second mold has one or more of the glass channels.

4. The columnar glass manufacturing apparatus as claimed in claim 2, wherein, The interior of the cylindrical mold further includes a cylindrical container.

5. The columnar glass manufacturing apparatus as claimed in claim 4, wherein, The second mold includes an annular notch, and the second mold engages with the cylindrical container.

6. A method for manufacturing columnar glass, comprising: The step of preparing a cylindrical mold having a first opening and a second opening, wherein the second opening is in communication with the first opening; The steps of placing glass material in the cylindrical mold; heating the placed glass material to soften it; inserting a first mold having a glass extrusion surface into the first opening so that the glass extrusion surface contacts the glass material; extruding the softened glass material by moving at least one of the first mold and the cylindrical mold to form a columnar glass from the second opening; and stretching the discharged columnar glass downward by guide rollers.

7. The method for manufacturing columnar glass as described in claim 6, wherein, The method for manufacturing columnar glass is carried out using the columnar glass manufacturing apparatus as described in claim 2.

8. The method for manufacturing columnar glass as described in claim 7, wherein, The second mold has one or more of the glass channels.

9. The method for manufacturing columnar glass as described in claim 7, wherein, The columnar glass has a polygonal, circular, or elliptical cross-section.

10. The method for manufacturing columnar glass as described in claim 7, wherein, The columnar glass has an arithmetic mean roughness Ra of 0.001 to 0.20 μm and a ten-point mean roughness Rz of 0.01 to 1.2 μm on its side surface.

11. The method for manufacturing columnar glass as described in claim 7, wherein, The difference between the crystallization peak temperature Tc of the columnar glass and the temperature at logη=5.3 ((crystallization peak temperature Tc) - (temperature at logη=5.3)) is above 0℃.

12. The method for manufacturing columnar glass as described in claim 7, wherein, The columnar glass sections have the same or approximately the same shape relative to their length direction in the vertical cross-section.

13. A columnar glass, manufactured using the columnar glass manufacturing apparatus as described in claim 1, or manufactured by the columnar glass manufacturing method as described in claim 6, having an arithmetic mean roughness Ra of 0.001 to 0.20 μm and a ten-point mean roughness Rz of 0.01 to 1.2 μm on its side surface.

14. The columnar glass as claimed in claim 13, wherein, The difference between the crystallization peak temperature Tc and the temperature at logη=5.3 ((crystallization peak temperature Tc) - (temperature at logη=5.3)) is above 0℃.

15. The columnar glass as described in claim 13 or 14, wherein, The shapes of the cross sections perpendicular to the length direction are the same or approximately the same.

16. The columnar glass as described in claim 13 or 14, wherein, The columnar glass has a cross-section perpendicular to its length that is circular, polygonal, or elliptical.

17. The columnar glass as claimed in claim 13 or 14, wherein, The columnar glass has a triangular or quadrilateral shape in its vertical cross-section relative to its length.

18. The columnar glass as claimed in claim 13 or 14, wherein, The area of ​​the columnar glass section perpendicular to its length is less than 50 mm².

19. The columnar glass as claimed in claim 13 or 14, wherein, The side of the columnar glass has straight stripes running along its length.

20. The columnar glass as claimed in claim 13 or 14, wherein, The columnar glass system does not contain any foreign matter from the release agent on the surface or inside the columnar glass.

21. The columnar glass as described in claim 13 or 14, wherein, The ratio of the maximum area to the minimum area (maximum area / minimum area) of the columnar glass relative to its length direction is less than 1.2.

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