Method for manufacturing quartz molded bodies

Abstract

This invention provides a simple method for manufacturing quartz molded bodies having a curved shape. [Solution] An initial shape mold is prepared that corresponds to a flat initial shape different from the desired target shape. A slurry containing quartz is poured into the mold and allowed to harden. After demolding, the mold is dried and degreased to form an initial shape molded body as a calcined body before the crystals vitrify. Next, a target shape mold is prepared that corresponds to a target shape having a curved surface, such as a dome shape. The initial shape molded body is then placed on the target shape mold and heated to sinter it. In this process, when the calcined body reaches its softening point, the initial shape molded body deforms under its own weight and is sintered while deforming into a shape that conforms to the target shape mold. In this way, a quartz molded body with a curved surface can be manufactured in a relatively simple manner without the waste of grinding and polishing, and without the need to prepare a large mold corresponding to the curved surface.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a quartz molded body having a curved surface shape.

Background Art

[0002] Quartz molded bodies are used in various applications such as optical fibers. These days, quartz molded bodies having a curved shape such as a dome shape are also required for use in the field of semiconductor manufacturing and the like. The following techniques are available for processing a quartz molded body into a curved shape. Patent Document 1 discloses a technique for forming a curved surface on a quartz glass substrate by grinding and polishing in an embodiment. Patent Document 2 discloses a technique for accurately grinding and polishing a quartz block into a curved surface shape. Patent Document 3 discloses a technique for heating and bending a flat quartz glass. In addition, a technique for forming a quartz molded body by curing a slurry is also known. According to this method, a curved quartz molded body can also be manufactured by preparing a mold having a curved shape.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there was still room for improvement in the conventional technology. For example, in the manufacturing methods by grinding and polishing disclosed in Patent Documents 1 and 2, the amount of quartz to be ground and polished increases as the size of the quartz molded body increases, resulting in a great deal of waste. The bending process disclosed in Patent Document 3 cannot be used to manufacture quartz molded bodies with three-dimensionally curved shapes such as dome shapes. Furthermore, in the case of methods that harden slurry, molds corresponding to curved shapes such as dome shapes require dimensions in the thickness direction, which presents the challenge of increasing the overall size of the mold. These challenges were common to various shapes having curved surfaces that should be achieved by bending, not just curved shapes (hereinafter, in this specification, such shapes having curved surfaces will be referred to as "curved shapes"). The present invention aims to provide a technology for solving these problems. [Means for solving the problem]

[0005] The present invention is a method for manufacturing a quartz molded body, A process of forming a calcined quartz body before vitrification into an initial shape that allows the quartz molded body to achieve the desired shape through bending deformation, The process of preparing a mold according to the target shape, The process involves placing the calcined body in the mold, applying a bending load in the direction along the mold, and sintering the calcined body to form the quartz molded body. A manufacturing method can be provided that includes the following features.

[0006] Quartz is more easily deformed during the vitrification process from calcined material to glass than glass after sintering. This invention utilizes this property to form a quartz molded body of the desired shape by deforming a calcined material, initially formed in its original shape, during sintering. Because the deformation occurs during sintering, bending to the desired shape can be achieved relatively easily. Thus, this invention solves various problems of conventional technology, such as waste caused by grinding and polishing, and enables the efficient production of curved quartz molded bodies in a relatively simple and waste-free manner.

[0007] In this invention, the initial shape can be determined arbitrarily. Shapes that cannot achieve the target shape even after bending deformation, or shapes that become smaller than the target shape, cannot be adopted as the initial shape. Conversely, even if the result of bending deformation does not perfectly match the target shape, it can be adopted as the initial shape if the target shape can be achieved by subsequent processes such as grinding and polishing. The load can be applied in various ways. It can be applied by the object's own weight, mechanically, or by using the pressure of a fluid. It is preferable to adjust the magnitude of the load so that it does not cause damage or residual stress to the molded object.

[0008] In the present invention, The calcined body may be formed by injecting a slurry or sol containing quartz into a mold corresponding to the initial shape and allowing it to harden.

[0009] This makes it relatively easy to form a calcined body of any initial shape.

[0010] In the present invention, Preferably, the mold is made of a non-metallic material having a softening point higher than the softening point of the calcined body.

[0011] During sintering, the temperature reaches a high enough level to soften the calcined material, generally exceeding 1500°C. If a metal mold is used at such high temperatures, a reaction between the quartz and the metal may occur, potentially resulting in the quartz molded product containing impurities. In contrast, according to the above embodiment, a non-metallic material that does not soften at the softening point of the calcined material is used, thus maintaining the shape of the mold at high temperatures and avoiding contamination by metal.

[0012] As one example mentioned above, The mold may be made of carbon, silicon carbide, or boron nitride.

[0013] These materials meet the requirements of having a higher softening point and being non-metallic than calcined materials. However, the materials used for the mold are not limited to these.

[0014] In the present invention, One or both of grooves and concavo-convexities may be formed in part or all of the portion of the quartz formed body of the mold where the quartz formed body is formed.

[0015] By doing so, there is an advantage that the quartz formed body easily detaches from the mold. The width of the groove, the size and interval of the concavo-convexities, etc. may be appropriately set within a range that does not inhibit the achievement of the target shape. In addition, such grooves and concavo-convexities may be even more useful when the mold is non-metallic. When using a non-metallic mold, reaction gas with quartz may be generated, and deformation along the mold may occur. In such a case, if grooves and concavo-convexities are provided, the reaction gas can be released, and it becomes possible to improve the accuracy of molding.

[0016] In the present invention, The initial shape may be a flat plate.

[0017] If it is an initial shape in a flat plate state, a calcined body can be easily formed. When using a method of injecting a slurry or sol containing quartz into a mold according to the initial shape and curing it, it is also possible to avoid an increase in the size of the mold. In addition, deformation can also be easily performed, and the production of the quartz formed body can be efficiently performed.

[0018] When using an initial shape on a plane, The initial shape may be a shape obtained by projecting the target shape onto a plane.

[0019] By doing so, after deformation, a shape generally close to the target shape can be obtained, and the load in subsequent processes and waste generated in subsequent processes can be avoided.

[0020] In the present invention, The bending load may be applied by the self-weight of the mold or the calcined body.

[0021] Applying a bending load using the material's own weight has the advantage of avoiding excessive loads and easily applying an appropriate load in accordance with the softening of the calcined material. To utilize the weight of the mold, the mold should be placed on top of the calcined material during sintering. Conversely, to utilize the weight of the calcined material, the calcined material should be placed on top of the mold during sintering.

[0022] Among the above embodiments, It is more preferable that the bending load is applied by the weight of the calcined body by placing it on the mold.

[0023] This is because using the weight of the calcined material itself, which is the object being deformed, rather than the weight of the mold, allows for a more appropriate application of load.

[0024] In the present invention, The quartz is preferably synthetic quartz.

[0025] Generally, synthetic quartz has a high softening point and is difficult to process after vitrification, which is why the present invention is highly effective.

[0026] The various features described above do not necessarily need to be all present; some can be omitted or combined as appropriate. [Brief explanation of the drawing]

[0027] [Figure 1] This is a process diagram showing the manufacturing process for molded products. [Figure 2] This is an explanatory diagram showing an example of a molding die. [Figure 3] This is an explanatory diagram showing an example of molding. [Figure 4] This is an explanatory diagram showing the results of the shape analysis of a molded example. [Figure 5] This is an explanatory diagram showing an example of a mold for testing. [Figure 6] This is an explanatory diagram showing the results of the shape analysis in the test (1). [Figure 7]This is an explanatory diagram showing the results of the shape analysis in the test (2). [Modes for carrying out the invention]

[0028] The following describes examples of quartz molded bodies having a curved shape. Figure 1 is a process diagram showing the manufacturing process of a molded body. It shows the process of manufacturing a molded body using the slurry casting method. In the slurry casting method, the slurry is first prepared (step S1). In this step, a glass raw material solution containing silica glass powder, solvent, dispersant, and curable resin is mixed in a ball mill for a predetermined time. Distilled water can be used as the solvent. This glass raw material solution may contain various additives and impurities.

[0029] Next, a hardening agent is added to the prepared slurry and poured into the initial shape mold to cure (Step S2). Curing can be achieved by leaving it at room temperature, but heating is also acceptable. In this embodiment, as described later, a quartz molded body is formed by deforming a calcined body while sintering it. The initial shape mentioned above refers to the shape of the calcined body before deformation. The method for determining the initial shape will be described later.

[0030] Once the initial-shaped molded body has hardened, it is detached from the initial-shaped mold (step S3), and the solvent in the initial-shaped molded body is removed by drying (step S4). Subsequently, the curable resin in the initial-shaped molded body is removed by degreasing. Degreasing can be carried out under various conditions, but for example, it may be carried out under a temperature of about 850°C. The initial-shaped molded body in this state is called a calcined body.

[0031] Next, the initial-shaped molded body is placed on the target-shaped mold (step S6). The target shape refers to the shape of the quartz molded body that should be obtained through the manufacturing process. For example, to obtain a dome-shaped quartz molded body, a planar circular molded body with a convex central portion can be used, as shown in the figure. Then, the circular, flat initial-shaped molded body is placed on top of it. Alternatively, a molded body with a concave top can be used instead of the convex molded body. In this way, the method of placing the target-shaped molded body and the initial-shaped molded body can be arbitrarily determined according to the target shape.

[0032] Subsequently, the initial shaped molded body is subjected to chlorine treatment and sintering (step S7). This allows the quartz in the calcined body to be vitrified, resulting in a hard quartz molded body. Both chlorine treatment and sintering are a series of processes performed at high temperatures. Chlorine treatment involves heating the molded body in a chlorine gas atmosphere. However, it is also acceptable to omit the chlorine treatment and perform only sintering. During this sintering process, the initial molded body is subjected to a bending load that bends its periphery downwards due to its own weight, as shown in the figure, causing it to deform into a shape that conforms to the desired mold.

[0033] This bending load can be applied, for example, by placing weights around the initial molded body, pressing it downwards with a press member, or spraying fluid onto it. However, applying excessive load to the initial molded body may lead to unintended deformation or damage. In this respect, applying a bending load due to the weight of the initial molded body has the advantage of allowing for an appropriate bending load to be applied depending on the degree of softening during the sintering process.

[0034] In the manufacturing process described above, a method utilizing the weight of the initial molded body was illustrated. However, for example, in the reverse of the diagrams for steps S6 and S7, the target mold could be placed on top of the initial molded body, and a bending load could be applied by the weight of the target mold.

[0035] Figure 2 is an explanatory diagram showing an example of a mold. It shows an example of a mold for obtaining a dome-shaped quartz molded body. The target shape mold 10 can be formed from any material, but since it is necessary to prevent softening during sintering of the calcined body, it is necessary to select a material that has a softening point at least higher than the softening point of the calcined body. Also, if metal is used, it may react with quartz during the sintering process and impurities may be mixed into the quartz molded body, so it is preferable to use a non-metal. From this viewpoint, carbon, silicon carbide, or boron nitride (BN) can be used as the material for the target shape mold. In this example, carbon was used.

[0036] Figure 2(a) shows a perspective view from diagonally above, and Figure 2(b) shows a view from the side. As shown in Figure 2(a), the mold 10 for forming the target shape has a circular raised portion 11 that corresponds to the dome shape. As shown in Figure 2(b), the raised portion 11 is curved upwards with its central part 11C being the apex. Since the target shape is a dome shape, the raised portion 11 is curved with the same curvature in all radial directions. A groove 12 is formed in the raised portion 11. This allows the quartz molded body to be easily released from the mold 10 of the desired shape. In addition, it provides a vent for gases generated during the sintering process, thus preventing gas from accumulating between the mold 10 of the desired shape and the calcined body, which would reduce the accuracy of the molding. The width and spacing of the grooves 12 can be adjusted as needed. Alternatively, instead of grooves 12, uneven surfaces may be provided.

[0037] Figure 3 is an explanatory diagram showing an example of molding. It illustrates a quartz molded body formed using the target shape mold 10 shown in Figure 2. Figure 3(a) shows a perspective view, and Figure 3(b) shows a side view. As shown in Figure 3(a), the quartz molded body has a planar circular shape, and as shown in Figure 3(b), the entire body has a dome shape that curves upwards. The initial molded body is a disc shape with a thickness of 10 mm and a radius of 180 mm, and it can be confirmed that it curves nicely in both radial directions during the sintering process.

[0038] Figure 4 is an explanatory diagram showing the shape analysis results of a molded example. As shown in Figure 4(a), in the initial circular molded body, the diametrical direction passing through the injection port (indicated by a black circle in the figure) for pouring the slurry (see step S2 in Figure 1) was defined as line 2, and the direction perpendicular to line 2 at the center of the circle was defined as line 1. Figure 4(b) shows the measurement results obtained by measuring the height according to the position in the directions of lines 1 and 2 using a three-dimensional measuring machine. Curve C1 is the shape along line 1, and curve C2 is the shape along line 2. In the area A enclosed by the dashed line, a slight discrepancy can be observed between curves C1 and C2, but overall, the two curves are in good agreement. In other words, it can be confirmed that the initial molded body deformed along the target shape mold in both the direction of line 1 and line 2.

[0039] Tests were conducted to investigate how complex a shape the initial molded body can be deformed into using the manufacturing method of this embodiment. The results are described below. Figure 5 is an explanatory diagram showing an example of a mold for testing. It schematically shows the mold as viewed from the side. As shown in the figure, the mold for testing has a shape in which discs M1 to M4 of a certain thickness are stacked. The diameter gradually decreases from the bottom to the top, and the envelope is set to form the target dome shape shown in Figure 2. The material of the mold for testing is also carbon.

[0040] Figure 6 is an explanatory diagram showing the shape analysis results (1) in the test. The initial molded body is a disc shape with a thickness of 10 mm and a radius of 180 mm. Figure 6(a) shows the shape obtained when the initial-shaped molded body, after being sintered and vitrified while maintaining its initial shape, is placed on the mold shown in Figure 5 and sintered again. Curve C11 shows the shape in the direction of line 1 shown in Figure 4(a), and curve C12 shows the shape of line 2. Figure 6(b) shows the shape of the initial shape molded body of the calcined material, which has not been vitrified, when placed on the mold shown in Figure 5 and sintered. Curve C21 shows the shape in the direction of line 1, and curve C22 shows the shape of line 2. Because the mold is formed in a stepped shape, unlike the curved shape shown in Figure 4(b), the curves C11 and C12 in Figure 6(a) and the curves C21 and C22 in Figure 6(b) are all slightly distorted from curves to irregular shapes. Conversely, this indicates that even when using the initial molded shape after vitrification, deformation to some extent along the target shape mold is possible. The circled areas in Figures 6(a) and 6(b) represent the parts with the smallest radius of curvature in each molding process. When using the initial molded shape after vitrification (Figure 6(a)), the radius of curvature was 104 mm. When using the initial molded shape of the calcined material (Figure 6(b)), the radius of curvature was 75 mm. In other words, it was confirmed that by using the calcined material as the initial molded shape, a small radius of curvature can be achieved, enabling the creation of a shape that conforms smoothly to the target mold, thus improving the accuracy of the molding process. Furthermore, it was confirmed that it is also possible to mold complex shapes.

[0041] Since the deformability of an initial molded body is thought to be affected by its thickness, we investigated the effect on the shape when the thickness is changed. Figure 7 is an explanatory diagram showing the results of the shape analysis (2) in the test. It shows a magnified view of the part of the overall shape shown in Figure 6 where the radius of curvature is smallest. Figures 7(a) and 7(b) are magnified views of the areas circled in Figure 6(a) and Figure 6(b), respectively. To avoid cluttering the diagram, only the circled parts of curves C12 and C22 are shown. These results were obtained using an initial molded body with a thickness of 10 mm, and the radii of curvature are 104 mm for Figure 7(a) and 75 mm for Figure 7(b). Figure 7(c) shows the shape of a 2mm thick calcined body as the initial molded shape. Curve C31 represents the shape in one direction, and curve C32 represents the shape in two directions. The circled area is the part with the smallest radius of curvature, and the shapes of curves C31 and C32 are in good agreement. The radius of curvature in this example was 11mm. This confirms that by making the calcined material thinner, the radius of curvature can be further reduced, and even more complex target shapes can be achieved.

[0042] Based on the above examples and test results, the manufacturing method of this embodiment allows for the efficient and accurate molding of quartz molded bodies with curved shapes, without the need for grinding or other waste, and without increasing the size of the mold. If further precision is required, grinding and polishing can be performed as a post-processing step. The various features described in the examples do not necessarily have to be present in their entirety; some may be omitted or combined as appropriate. Furthermore, the present invention can be modified in various ways other than those described in the examples. In the examples, a dome-shaped quartz molded body was illustrated, but the present invention is not limited to such a shape and can be used for quartz molded bodies having various curved shapes that should be achieved by bending. The planar shape is also not limited to a circle. [Industrial applicability]

[0043] This invention can be used to manufacture quartz molded bodies having a curved shape. [Explanation of symbols]

[0044] 10 Target shape mold 11 Ridge 11C Center 12 grooves

Claims

1. A method for manufacturing a quartz molded body, A process of forming a calcined quartz body before vitrification into an initial shape that allows the quartz molded body to achieve the desired shape through bending deformation, The process of preparing a mold according to the target shape, The process involves placing the calcined body in the mold, applying a bending load in the direction along the mold, and sintering the calcined body to form the quartz molded body. A manufacturing method that includes the following features.

2. A manufacturing method according to claim 1, The calcined body is formed by pouring a slurry or sol containing quartz into a mold corresponding to the initial shape and allowing it to harden.

3. A manufacturing method according to claim 1, A manufacturing method wherein the mold is formed of a non-metallic material having a softening point higher than the softening point of the calcined body.

4. A manufacturing method according to claim 3, A method for manufacturing the mold, wherein the mold is formed of carbon, silicon carbide, or boron nitride.

5. A manufacturing method according to claim 1, A manufacturing method wherein grooves and / or irregularities are formed in part or all of the portion of the mold in which the quartz molded body is formed.

6. A manufacturing method according to claim 1, The manufacturing method described above has an initial shape that is a flat plate.

7. A manufacturing method according to claim 6, A manufacturing method wherein the initial shape is the shape obtained by projecting the target shape onto a plane.

8. A manufacturing method according to claim 1, A manufacturing method in which the bending load is applied by the weight of the mold or the calcined body.

9. A manufacturing method according to claim 8, A manufacturing method in which the bending load is applied by the self-weight of the calcined body by placing the calcined body on the mold.

10. A manufacturing method according to claim 1, The aforementioned quartz is synthetic quartz, and the manufacturing method is described.

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