JP2011236101A - Mold for forming cylindrical quartz glass and forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for producing a quartz glass molding while preventing displacement of a center axis of a recess formed at the center of the glass molding.SOLUTION: The mold 10 forms the outline of a cylindrical glass product by heating and melting a quartz glass material 16. The outer diameter of a guide member 20 of the mold is set to be smaller than the inner diameter of an outer cylinder 14 by 2-10 mm to form a gap between the guide member 20 and the outer cylinder 14, and the thickness of the guide member 20 is set to be ≥30 mm to prevent seizure of the guide member 20 with the inner wall face of the outer cylinder 14 and to prevent the displacement of the center axis of the recess formed at the center of the formed quartz glass 16 even if the upper face of the quartz glass material 16 is inclined by local temperature rise.

Description

  The present invention relates to a mold material and a method for molding a quartz glass material using the mold material, and more specifically, a mold material used when molding a quartz glass material into a cylindrical shape while being heated and melted, and quartz glass using the mold material. The present invention relates to a molding method of a molded body.

  In recent years, quartz glass is not limited to optical devices such as optical lenses, but has advantages such as durability and chemical stability. Photomasks for manufacturing semiconductor manufacturing jigs and liquid crystal display (LCD) panels. Alternatively, it is widely used for precision parts for optical communication.

  In the production of quartz glass products, a process that mainly uses a removal process that removes unnecessary regions from the workpiece, such as etching and grinding, has been adopted. However, the etching process is performed on the surface of the workpiece. The quartz glass products obtained were limited to relatively fine processing.

  Therefore, as shown in Patent Document 1 (Japanese Patent Application Laid-Open No. 2009-234858), when forming a cylindrical member, when the quartz glass material is heated and melted, the central portion of the material is pressed and a concave portion is formed in the central portion. A mold material and a molding method for molding a rough shape of the final quartz glass product having the above were proposed.

JP 2009-234858 A

  Briefly describing the contents, FIG. 1 shows a schematic configuration of a mold 10 on which a quartz glass material 16 is placed, and FIG. 2 shows a cross-sectional view taken along line AA of FIG. FIG. 3 shows an AA cross-sectional view of the quartz glass material (molded body) and the mold material 10 after the quartz glass material 16 is heated and melted.

  The mold material 10 used for forming the quartz glass material 16 is placed on the bottom plate 12, a cylindrical outer cylinder 14 having a desired inner diameter disposed on the upper surface 12 a of the bottom plate 12, and the inner center of the outer cylinder 14. A lower mold 52, a guide member 20 slidably movable in the vertical direction on the inner peripheral surface 14a of the outer cylinder 14, and a fused quartz glass material 16 placed on the upper surface 20a of the guide member 20. A load plate 22 for forming under load, and a substantially cylindrical shape that is disposed on the lower surface 20b of the guide member 20 and presses the quartz glass material 16 of the workpiece placed on the upper surface 52a of the lower mold 52 from above. The upper pressing jig 18 is configured. The outer cylinder 14 may be a cylindrical shape, but may be formed into a cylindrical shape by assembling members divided into three to four in the circumferential direction.

  The lower mold 52, the quartz glass material 16, the pressing jig 18, the guide member 20, and the central axis of the load plate 22 are disposed so as to be positioned on the central axis (XX) of the outer cylinder 14. Further, carbon is adopted as the material of these mold materials 10 from the viewpoints of thermal stability, chemical stability, workability, and cost. Furthermore, the upper surface 12a of the bottom plate 12 and the inner peripheral surface 14a of the outer cylinder 14 are used. The lower surface 18b, the side surface 18c of the pressing jig 18, the upper surface 52a of the lower mold 52, and the side surface 52c are coated with a release agent.

  In order to melt-mold the quartz glass material 16 into a rough shape of a quartz glass product using the mold material 10, a heating device (not shown) such as an electric furnace is used for the mold material 10 on which the quartz glass material 16 is placed. For example, heating is performed at a heating temperature of 1500 ° C. to 2000 ° C. in an inert gas atmosphere such as nitrogen gas. The heated quartz glass material 16 is heated and melted, and as shown in FIG. 3, the quartz glass material 16 is formed as a quartz glass molded body having the same dimensions as the inner diameter of the outer cylinder 14 and having recesses on the upper and lower surfaces.

  The quartz glass material 16 thus formed becomes a quartz glass product having a desired shape through mechanical processing such as grinding.

  In the above description, the case where the lower mold 52 is used to form the recesses up and down has been described. However, the same method can be used when the recesses are formed only on the upper part without using the lower mold 52. The

  When the quartz glass material 16 is melt-molded using the mold material 10 shown in FIG. When the deviation of the central axis is increased, the machining allowance for obtaining a cylindrical body having a desired shape is increased, the processing time is increased, the material loss is increased, and the merit of using the mold material is reduced. Further, when the deviation of the central axis becomes large, correction by processing becomes impossible, and the melt-molded quartz glass molded body may be wasted.

  Furthermore, when using a split-type outer cylinder, the outer cylinder is deformed as the number of uses increases, and the inner circumference of the outer cylinder formed by assembling the members of the outer cylinder is deformed to be the same as the inner diameter of the outer cylinder. There is a problem that it becomes impossible to install a guide member having an outer diameter of 5 mm inside the outer cylinder.

  When the cause of the shift of the central axis of the concave portion was sought, when the quartz glass material 16 is heated and melted, heat conduction is not uniformly performed, so the melting of the quartz glass material 16 starts locally, and the upper surface of the quartz glass material 16 It was found that the parallelism between the guide plate and the bottom plate is lost, and the outer peripheral side surface of the guide member is caught by the inner surface of the outer cylinder, so that sliding does not occur smoothly and tilts.

  The present invention enables the guide member to slide smoothly without being caught on the inner wall surface of the outer cylinder, and the center axis of the concave portion of the quartz glass molded body is displaced by the horizontal restoration of the guide member even when tilted. It is something to prevent.

  When the outer diameter of the guide member is made 2 mm to 10 mm smaller than the inner diameter of the outer cylinder, and the thickness of the guide member is 30 mm or more, melting starts locally and melting occurs, and the upper surface of the quartz glass material is inclined. Even if it occurs, the guide member is prevented from being caught on the inner wall surface of the outer cylinder, and the central axis of the concave portion at the center of the quartz glass molded body is not displaced.

  In addition, a flexible and easily deformable material such as carbon felt is wrapped around the outer periphery of the guide member, so that the guide member will not be caught on the inner wall surface of the outer cylinder even if it is locally heated and inclined. The central axis of the concave portion at the center of the quartz glass molded body is not displaced.

  If the difference between the outer diameter of the guide member and the inner diameter of the outer cylinder is less than 2 mm, the thickness of the guide member must be reduced, and the mold material deforms due to repeated use of the mold material, and the guide member contacts the outer cylinder. In addition, when the guide member is greatly deformed, it cannot be installed in the outer cylinder, so that the difference between the outer diameter of the guide member and the inner diameter of the outer cylinder is 2 mm or more.

  If the difference between the outer diameter of the guide member and the inner diameter of the outer cylinder is larger than 10 mm, the play of the guide member is too large, and the center axis of the pressing jig and the molded body is shifted during melt molding, so that the material is wasted. Not only does this occur, but the deviation of the central axis changes with each melt molding operation, so that it may not be possible to obtain a molded body having a desired shape.

  Regarding the thickness of the guide member, the thickness of the guide member is corrected because the outer peripheral wall of the guide member contacts the inner surface of the outer cylinder while the deviation of the central axis of the guide member is small when the thickness is increased. Is preferably 30 mm or more. The thickness of the guide member can be appropriately determined according to the height of the outer cylinder, the lower mold, the quartz glass material, and the size of the heating device. As the thickness increases, workability decreases due to an increase in weight, so the thickness is determined in consideration of work efficiency.

  When the thickness is less than 30 mm, the deviation of the central axis of the guide member is not sufficiently corrected, and the central axis of the pressing jig and the molded body is shifted, which is not preferable because it takes time and effort to process the molded body into a desired shape. .

  By winding a carbon felt around the outer peripheral side surface of the guide member, the outer diameter of the guide member can be increased and the thickness of the guide member can be reduced. By changing the thickness of the felt, the guide member can be used for outer cylinders having different diameters. Further, since the felt has flexibility, there is an advantage that the slidability of the guide member is increased.

  In the present invention, the outer diameter of the guide member, which is a component of the mold material used in the melt molding of the quartz glass material, is made 2 mm to 10 mm smaller than the inner diameter of the outer cylinder, so that the guide member slides during the melt molding. As a result, the yield in obtaining a molded article having a desired shape was improved. Moreover, the weight of the quartz glass material used when manufacturing a cylindrical quartz glass product can be reduced, and thereby the production cost can be reduced.

The perspective view explaining schematic structure of a mold material. AA sectional drawing of FIG. 1 before heat-melting. AA sectional drawing of FIG. 1 after heat-melting.

DESCRIPTION OF SYMBOLS 10 Mold material 12 Bottom plate 12a Bottom plate upper surface 14 Outer cylinder 14a Outer cylinder inner peripheral surface 16 Quartz glass material 18 Press jig 18b Press jig lower surface 18c Press jig side surface 20 Guide member 20a Guide member upper surface 20b Guide member lower surface 22 Load plate 52 Below Mold 52a Lower mold upper surface 52c Lower mold side

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
A lower mold 52 having an outer diameter of 200 mm and a height of 30 mm is placed in the center of a circular carbon bottom plate 12 having a thickness of 1 cm and a diameter of 50 cm, and a quartz glass material 16 having an outer diameter of 270 mm and a height of 170 mm is placed thereon. The pressing jig 18, the guide member 20, and the load plate 22 having an outer diameter of 220 mm and a height of 150 mm were installed with the central axes of the two being aligned and the central axes being aligned.

  The outer cylinder 14 was divided into three parts having an inner diameter of 420 mm, a thickness of 30 mm, and a height of 550 mm. The outer cylinder 14 was assembled so that its central axis coincided with that of the quartz glass material 16 or the like.

The melt molding was carried out by transferring the mold 10 assembled as described above into an electric furnace and heating it at 1900 ° C. for 2 hours in a nitrogen gas atmosphere.
After cooling, the molded body was taken out from the mold member 10, and the deviation of the central axis between the molded body and the depressions on the upper and lower surfaces of the molded body was measured.

  Test results of Examples and Comparative Examples are shown in Tables 1 and 2. Here, Table 1 shows an example in which the degree of deviation between the central axis of the concave portion of the formed body and its upper and lower surfaces was changed by changing the gap and changing the thickness of the guide member by changing the outer diameter of the guide member. It is a test result.

Table 2 shows test results obtained by examining the degree of deviation of the central axis of the comparative example by changing the outer diameter and thickness of the guide member in the same manner as above.
In these tests, the conditions not shown in Tables 1 and 2 were all the same.

  As shown in the test results of Table 1 and Table 2, when the gap between the guide and the outer cylinder is 5 mm or less and the thickness of the guide is 30 mm or more, the molded body and the depressions on the upper and lower surfaces of the molded body It has been found that the deviation of the center axis of the tube is 2 mm or less, the machining allowance for obtaining a cylindrical body having a desired shape is small, the machining time is increased, and the material loss is small.

Here, in Example 7 of Table 1, the guide outer diameter is described as (400 + 14) mm, which is because a carbon felt having a thickness of 7 mm is wound around the outer periphery of the guide having an outer diameter of 400 mm.
Moreover, although the column of the deviation of the central axis of Comparative Example 5 in Table 2 is not measurable, this is because the pressing jig 18 bites into the molded body obliquely, so that the central axis of the recess on the upper surface of the molded body This is because it could not be determined.

Claims (4)

A mold material for roughly forming a quartz glass product having a cylindrical shape by heating and melting quartz glass material, and a bottom plate, and an outer cylinder disposed on the bottom plate in contact with the bottom plate and one opening, A guide member slidably movable in the vertical direction in the outer cylinder, and disposed on the lower surface of the guide member, and presses the upper surface of the quartz glass material placed on the bottom plate in the outer cylinder In the mold material having a pressing jig to perform and a load plate for applying a load to the pressing jig, the outer diameter of the guide member is 2 mm to 10 mm smaller than the inner diameter of the outer cylinder, and the thickness is 30 mm or more. Features a mold material for forming quartz glass. A mold material for roughly forming a quartz glass product having a cylindrical shape by heating and melting quartz glass material, and a bottom plate, and an outer cylinder disposed on the bottom plate in contact with the bottom plate and one opening, A lower mold disposed on the bottom plate in the outer cylinder, a guide member slidably movable on the inner peripheral surface of the outer cylinder in the vertical direction, and a lower surface of the guide member. And a mold member having a pressing jig for pressing the upper surface of the quartz glass material placed on the lower mold in the outer cylinder, and a load plate for applying a load to the pressing jig. A quartz glass molding die characterized in that the diameter is 2 mm to 10 mm smaller than the inner diameter of the outer cylinder and the thickness is 30 mm or more. 3. The quartz glass molding die according to claim 1 or 2, wherein the diameter is adjusted by winding a carbon felt around the outer periphery of the guide member. A method for producing a quartz glass molded body having a concave portion at the center of the upper surface or the center of the upper and lower surfaces by melting the quartz glass material using the mold material for molding a quartz glass according to claim 1.