JP2006001821A - Apparatus and method of forming quartz glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method of forming quartz glass by which the strain or the crack of quartz glass hardly occurs in the hot press forming and the manufacture of a mold is facilitated. <P>SOLUTION: The apparatus is provided with the mold 15 having a hollow part 21 in which the quartz glass is housed and comprising a material having larger coefficient of expansion than that of the quartz glass, a pressing part 23 and a heating means 13. The quartz glass in the hollow part 21 is pressed in the pressing part 23 while being heated by the heating means 13 to be formed into a prescribed shape. The mold 15 has a plurality of side plates 19 combined to be contact with each other and forming the side surface surroundings, an engaging means 16a, 24 and a spacer 30. The hollow part 21 is formed inside the side plates 19 and the spacer 30 and is constituted so that an engaging state is kept in the forming and the engaging state is released by the force in the outward direction which is loaded on the spacer 30 and the side plates 19 based on the difference of the coefficient of the expansion between the mold 15 and the quartz glass in the cooling after the forming and the side plates 19 and the spacer 30 are separated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus and a molding method for forming a quartz glass into a predetermined shape by accommodating the quartz glass in a mold made of a material having a larger expansion coefficient than that of the quartz glass and performing heat and pressure molding.

Quartz glass is often used as a material for the illumination optical system of a projection exposure apparatus that uses a light source having a wavelength shorter than the i-line or an optical member such as a lens, mirror, or reticle of the projection optical system. This quartz glass is synthesized by, for example, a direct method for producing transparent quartz glass by flame hydrolysis.

  In the direct method, a combustion-supporting gas (oxygen-containing gas, for example, oxygen gas) and a combustible gas (hydrogen-containing gas, for example, hydrogen gas or natural gas) are mixed and burned in a quartz glass burner. A high purity silicon compound (for example, silicon tetrachloride gas) is diluted as a source gas from the center with a carrier gas (usually oxygen gas) and ejected, and the source gas reacts by combustion of the surrounding oxygen gas and hydrogen gas (Hydrolysis reaction) to generate quartz glass fine particles, and the quartz glass fine particles are deposited on a target made of an opaque quartz glass plate disposed under the burner and performing rotation, swinging and lowering movement, A quartz glass ingot is obtained by melting and vitrification by the combustion heat of the oxygen gas and hydrogen gas.

  According to this method, since it is easy to obtain a quartz glass ingot having a relatively large diameter, an optical member having a desired shape and size can be manufactured by cutting out a block from the ingot.

  In recent years, in order to obtain an optical member having a large surface, such as a large lens or reticle, or a large liquid crystal display, a quartz glass lump such as a pre-formed ingot is formed into a flat shape by heating and pressing. The molding method which expands is utilized.

  In this molding method, a quartz glass lump is accommodated in a mold and heated, and then molded by being pressed by a pressure unit, and then slowly cooled in the mold or further subjected to an annealing treatment. A molded body having a predetermined shape with an enlarged area is obtained.

  For example, the heat and pressure molding is performed in a graphite mold by heat and pressure molding at a temperature of 1700 ° C. or higher in a helium gas atmosphere having an absolute pressure of 0.1 Torr or higher and atmospheric pressure or lower. Then, a method of rapidly cooling to 1100 to 1300 ° C. is known. Also, a method of pressure molding at 1600 ° C. to 1700 ° C. using a graphite mold having a structure that relieves stress caused by a difference in thermal expansion coefficient between quartz glass and a mold mold (see Patent Document 1 below). ) And a molding apparatus in which the graphite mold has a vertical structure with two or more divisions (see Patent Documents 2 and 3 below). Furthermore, a method of forming a coating layer made of quartz powder on the inner surface of a graphite mold and performing pressure molding at 1550 ° C. to 1700 ° C. (see Patent Document 4 below) is also known. In such heat and pressure molding, a mold made of graphite is used in order to prevent impurities from being mixed and to ensure heat resistance strength during molding.

The expansion coefficient of this graphite is significantly larger than that of quartz glass, and graphite is 8 × 10 ⁻⁶ / ° C., whereas quartz glass is 5.5 × 10 ⁻⁷ / ° C. For this reason, after the molding, when the quartz glass is cooled while being accommodated in the mold, the amount of shrinkage of the mold becomes larger than the amount of shrinkage of the quartz glass. Glass tends to be distorted and broken. Therefore, Patent Documents 1 to 3 and the like employ a structure that avoids distortion in advance.
Japanese Patent Publication No. 4-54626. JP-A-56-129621. JP-A-57-67031. Japanese Patent Application Laid-Open No. 2002-22020.

  However, in order to form various types of quartz glass with high yield by such heat and pressure molding, it is necessary to prepare molds corresponding to the size of the type of quartz glass to be molded. For this reason, each mold must be provided with a structure that avoids the distortion and cracking that occurs in the quartz glass due to the difference between the shrinkage of the quartz glass and the shrinkage of the mold. It was.

  Accordingly, in the present invention, in quartz glass heating and pressure molding, quartz glass molding apparatus and molding that are difficult to cause distortion and cracking of quartz glass during molding, and that are easy to manufacture molds by sharing parts. It is an object to provide a method.

  The invention according to claim 1, which solves the above-mentioned problem, has a hollow part that can accommodate quartz glass, and is arranged so as to be movable inside the hollow part, a mold made of a material having a larger expansion coefficient than the quartz glass. And a heating means for heating the quartz glass accommodated in the hollow part, and the quartz glass in the hollow part is pressurized by the pressure part while being heated by the heating means. A molding apparatus for forming a plurality of side plates that are combined in a state of being in contact with each other to form a periphery of a side surface, and a fitting that is fitted around the side surface of the plurality of combined side plates. Means and a spacer disposed adjacent to at least one inner surface of the plurality of side plates, and the hollow portion is formed inside the plurality of side plates and the spacers combined, and during the molding, Mating means The fitting state is further maintained, and at the time of cooling after the molding, the fitting means is subjected to an outward force applied to the plurality of side plates based on a difference in expansion coefficient between the mold and the quartz glass. When the fitting state is released and the side plate moves through the spacer, the fitting surfaces of the plurality of side plates and the fitting means are formed in a tapered shape so that the plurality of side plates are separated from each other. It is characterized by being.

  The invention described in claim 2 is characterized in that, in addition to the configuration described in claim 1, the independent spacers are arranged for all the side plates.

  According to a third aspect of the present invention, in addition to the configuration according to the first or second aspect, the fitting means includes a frame-shaped support ring fitted to the outside of the plurality of side plates, and the outward direction. The plurality of side plates move in a direction away from each other when the fitting surfaces slide with each other and the support ring moves in the removal direction.

  According to a fourth aspect of the present invention, in addition to the configuration according to any one of the first to third aspects, the fitting means includes a bottom portion having a concave portion into which lower end portions of the plurality of side plates are fitted. And the plurality of side plates move in a direction away from each other by moving the plurality of side plates out of the recesses of the bottom by the outward force. .

  According to a fifth aspect of the present invention, in addition to the structure according to any one of the first to fourth aspects, the hollow section has a substantially polygonal cross-sectional shape, and the corner portion of the shape is an end of the spacer. It is formed in the R shape by the part.

  The invention according to claim 6 is the invention according to any one of claims 1 to 4, wherein the hollow section has a substantially polygonal cross-sectional shape, and a corner portion of the shape is an end of the spacer. A plurality of inclined surfaces are formed so as to have an obtuse angle.

  The method for molding quartz glass according to claim 7 is a method for molding quartz glass in which a block of quartz glass disposed in a mold is heated and pressed, and the mold is disposed at a bottom portion and an upper portion of the bottom portion. A side wall portion and a spacer disposed adjacent to the inside of the side wall portion, and the quartz glass is pressure-molded by a pressing means while the quartz glass is heated by a heating means. To do.

  According to the invention described in claim 1 or 2, the mold is disposed adjacent to at least one inner surface of the plurality of side plates which are combined in a state of being in contact with each other to form the periphery of the side surface. And a fitting means that fits these in a state in which the hollow portion is formed inside by combining them, so that the hollow portion can be easily replaced by replacing the spacer with a different thickness in a different molding process. The size can be changed. Therefore, since a plurality of side walls and fitting means can be used in common to form quartz glass having different sizes, the mold can be easily manufactured.

  In addition, the fitting state is maintained during molding, and during the cooling after molding, the fitting state is released by an outward force applied to a plurality of side plates based on the difference in expansion coefficient between the mold and quartz glass. Since the fitting surface is tapered so that the side plates move through the spacers, the quartz glass is formed on the basis of the difference in expansion coefficient during cooling after molding. When there is a difference in the amount of shrinkage between the mold and the mold, the fitting state of the fitting means is released, the spacer and the side plate are divided, the stress can be released, and the cracking and distortion of the quartz glass can be suppressed. it can.

  According to the invention described in claim 3, the fitting means has a frame-shaped support ring fitted on the outside of the plurality of side plates, and the fitting surfaces slide with each other by an outward force. Since the plurality of side plates move in a direction away from each other by moving in the removal direction, it is easy to attach and detach the plurality of side plates and fitting means when assembling and disassembling the mold. In addition, since the common side wall and the fitting means are used, the same operation can be obtained even if the planar shape such as the area of the hollow portion is changed, and the occurrence of distortion and cracking during cooling can be reliably prevented.

  According to invention of Claim 4, a fitting means has a bottom part provided with the recessed part by which the lower end part of a some side plate is fitted, and a some side plate is the direction which pulls out from the recessed part of a bottom part by external force. Since the plurality of side plates are configured to move in a direction away from each other, the plurality of side plates and the fitting means can be easily attached and detached when the mold is assembled and disassembled. Since the common side wall and the fitting means are used, the same operation can be obtained even if the planar shape such as the area of the hollow portion is changed, and the occurrence of distortion and cracking during cooling can be reliably prevented.

  According to the invention of claim 5, since the cross-sectional shape of the hollow portion is substantially polygonal and the corner portion of the shape is formed in an R shape by the end of the spacer, Stress can be prevented from concentrating on the corner portion, distortion and cracking of the corner portion can be prevented, quartz glass can be easily formed, and the yield can be greatly improved.

  According to the invention described in claim 6, since the cross-sectional shape of the hollow portion has a substantially polygonal shape, and the plurality of inclined surfaces are formed such that the corner portion of the shape has an obtuse angle with the end portion of the spacer. It is possible to prevent stress from being concentrated on the corner portion of the formed quartz glass, and it is easy to mold the quartz glass by preventing distortion and cracking of the corner portion, and it is easy to greatly improve the yield.

  According to the method for molding quartz glass according to claim 7, since quartz glass is pressure-molded by a mold in which spacers are arranged adjacent to the inside of the side wall portion, it is exchanged with spacers having different thicknesses in different molding processes. Then, different sizes of quartz glass can be formed using the side wall portion in common.

[Embodiment 1]
Embodiment 1 of the present invention will be described below.

  1 to 3 show a molding apparatus according to this embodiment.

  This molding apparatus 10 is composed of an ingot of synthetic quartz glass or a part thereof manufactured from a silicon compound such as silicon tetrachloride, silane, or organic silicon, or a refractive index of Ge, Ti, B, F, Al, or the like. From quartz glass such as synthetic quartz glass ingots and parts thereof with added components that change the size of, for example, large liquid crystal masks, reticles for photomasks such as semiconductor masks, and large optical imaging systems It is an apparatus for molding a plate-like body having a wide surface such as a lens material or other large glass blocks.

  In this molding apparatus 10, a heat insulating material 12 provided over the entire surface and a carbon heater 13 as a heating means provided in the vertical wall of the heat insulating material 12 are provided on the inner wall of a metal vacuum chamber 11, and A mold 15 having a hollow portion 21 is accommodated in a substantially central portion inside the vacuum chamber 11.

  The mold 15 includes a bottom portion 18 including a bottom plate 16 and a receiving plate 17, and a side wall portion 20 disposed above the bottom portion 18, and a hollow portion 21 is formed inside the side wall portion 20.

  The side wall portion 20 is a combination of a plurality of side plates 19 and a plurality of spacers 30 arranged adjacent to the inner surface 19 a side of the plurality of side plates 19, and as a fitting means around the outer peripheral side surface 19 b of the plurality of side plates 19. The support ring 24 is fitted and configured.

  The spacer 30 is a quadrangular plate material in which one surface is an inner surface 30a constituting the wall surface of the hollow portion 21, and the other surface is an outer surface 30b arranged in a state adjacent to the inner surface 19a of the side plate. In this embodiment, the outer surface 30b of the spacer 30 is in contact with the substantially entire surface of the inner surface 19a of the side plate 19, and each of the plurality of side plates 19 is arranged with the independent spacer 30 in contact therewith. . Further, the side edges of the spacer 30 have inclined side surfaces 30c oriented toward the inner surface 30a, and are arranged in contact with each other.

  The side plate 19 is a rectangular plate material in which one surface is an inner surface 19 a that contacts the spacer 30 and the other surface is an outer surface 19 b that forms the periphery of the side surface of the side wall portion 20. On both sides of the side plate 19, there are inclined side surfaces 19 c oriented toward the inner surface 19 a and are disposed in contact with each other. The upper end portion 19d and the lower end portion 19e have tapered fitting surfaces 19f and 19g respectively oriented to the outer surface 19b side. As well

  The support ring 24 is a quadrangular frame formed in a hollow shape, and has a tapered fitting surface 24 a that coincides with the fitting surface 19 f of the side plate 19 on the inner side.

  And this side wall part 20 makes the inclined side surfaces 19c contact each other, abuts the four side plates 19 in a square tube shape, and further combines the spacers 30 adjacent to each other in this state. Thus, the support ring 24 is mounted around the four side plates 19, and the fitting surface 24 a of the support ring 24 is fitted to the fitting surface 19 f of the side plate 19.

  Further, the bottom plate 16 of the bottom portion 18 is formed with a concave portion 16a as a fitting means into which the lower end portion 19g of the side wall portion 20 can be inserted. A tapered fitting surface 16b that coincides with the fitting surfaces 19g of the four side plates 19 is formed in the recess 16a.

  Then, by inserting the lower end 19e side of the side plate 19 assembled with the spacer 30 on the surface of the side plate 19a into the recess 16a, the recess 16 is fitted around the fitting surface 19g. The mold 15 is formed by fitting the mating surface 16 b and disposing the receiving plate 17 at the lower end portion in the hollow portion 21, that is, the lower portion inside the spacer 30.

  As shown in FIG. 3, the hollow portion 21 of the mold 15 has a quadrangular cross-sectional shape, and all corner portions 27 are formed in an R shape. The R shape is formed by continuing curved surface shapes formed on both side edges of the spacer 30.

  Furthermore, a top plate 23 as a pressurizing portion having a shape corresponding to the shape of the hollow portion 21 is movably disposed in the hollow portion 21 in a state where the massive quartz glass 25 is disposed.

  The top plate 23 presses the pressing surface 23b (upper surface) with a cylinder rod 26 of a hydraulic cylinder as molding means disposed outside the vacuum chamber 11, so that a block of quartz is formed on the pressing surface 23a of the top plate 23. The glass 25 can be pressurized.

  The hydraulic cylinder provided with the cylinder rod 26 is configured to be pressurized and moved by adjusting the hydraulic pressure supplied from the outside, but the detailed illustration is omitted.

  These bottom plate 16, receiving plate 17, side plate 19, spacer 30, support ring 24, and top plate 23 all have heat resistance and strength against the temperature and pressure at the time of forming the quartz glass 25, and at the time of forming It is made of a material that hardly mixes impurities even when it comes into contact with the quartz glass 25, and here, it is all made of graphite having an expansion coefficient larger than that of quartz glass.

Among these, a large bending direction force is applied to the side plate 19 and the spacer 30 during molding. Therefore, it is preferable to select the thickness of the side plate 19 according to the pressure applied at the time of molding. For example, the molding pressure at the time of molding is 0.3 to 0.3 of the pressure converted per unit area of the pressing surface 23a of the top plate 23. In the case of 5.0 kg / cm ² , it is preferably 20 to 70 mm, particularly 30 to 50 mm. When the plate thickness is thin, the side plate 19 is bent, and the stress for compressing the quartz glass 25 during cooling is likely to increase.

  The plate thickness of the spacer 30 is preferably 10 mm to 50 mm, particularly preferably 20 mm to 40 mm. If these plate thicknesses are thin, handling becomes difficult and they are easily damaged, whereas if the plate thickness is thick, extra time is required for electric heating.

  In this molding apparatus 10, the taper shape of the fitting surface 19f of the side plate 19 of the mold 15 and the fitting surface 24a of the support ring 24, and the taper of the fitting surface 19g of the side plate 19 and the fitting surface 16b of the recess 16a. Each of the shapes is set so that the fitting state can be maintained at the time of molding and the fitting state can be released at the time of cooling after molding.

  That is, the fitting surface 19f of the side plate 19 and the fitting surface 24a of the support ring 24, and the fitting surface 19f of the side plate 19 and the fitting surface 16b of the recess 16a are moved relative to each other by being in a fitted state. The friction force which suppresses is acting. In this state, when an outward force is applied to each side wall 19 via each spacer 30, there is a gap direction between the fitting surfaces 19f and 24a and between the fitting surfaces 19g and 16b according to the taper shape. The force of acts. Here, in a range in which the force in the pulling direction is smaller than the frictional force in the fitted state, the fitted state is maintained without sliding between the fitted surfaces 19f and 24a and between the fitted surfaces 19g and 16b. be able to. On the other hand, when the force in the pulling direction becomes larger than the frictional force in the fitted state, the fitted state is released by sliding between the fitted surfaces 19f and 24a and between the fitted surfaces 19g and 16b.

  Therefore, in this molding apparatus 10, the outward force of the side plate 19 generated by the quartz glass 25 being pressed and deformed by the top plate 23 during molding causes the fitting surfaces 19f, 24a and the fitting surfaces 19g, It is a taper shape in which the fitting state between 16b is maintained.

  At the same time, when cooling force after molding is applied to each side plate 19 due to a difference in shrinkage due to a difference in expansion coefficient between the mold 15 and the quartz glass 25, an outward force acts on the support ring 24 and the recess 16a. Each of the fitting surfaces 19f and 24a and between the fitting surfaces 19g and 16b slide to form a tapered shape in which the fitting state is released.

Such a taper shape can be appropriately selected depending on the properties of each fitting surface, etc. For example, when the pressure by the top plate 23 at the time of molding is in the range of 0.3 to 5.0 Kg / cm ² , The tapered shape of the fitting surface is preferably set so as to have an elevation angle of 60 ° to 75 °.

  Next, a case where the massive quartz glass 25 is subjected to heat and pressure molding by the molding apparatus 10 having the above configuration will be described. First, the mold 15 is formed by combining the bottom plate 16, the receiving plate 17, the side plate 19, the spacer 30 and the support ring 24 in the vacuum chamber 11. A massive quartz glass 25 is disposed in the hollow portion 21 of the mold 15, a top plate 23 is disposed thereon, and a pressing portion 26 a of the cylinder rod 26 of the hydraulic cylinder is provided on the pressing surface 23 b of the top plate 23. Set it in contact. In this embodiment, a synthetic quartz glass ingot is used as the massive quartz glass 25.

  Then, the inside of the vacuum chamber 11 is replaced with an inert gas, and the massive quartz glass 25 in the hollow portion 21 is heated by the carbon heater 13, so that the crystallization temperature is equal to or higher than the softening point, specifically, 1570 ° C. to 1670 ° C. The temperature is raised to 2 and molding is performed.

  At the time of molding, the cylinder rod 26 of each hydraulic cylinder is moved downward by hydraulic pressure, and the pressing surface 23b of the top plate 23 is pressed by the pressing portion 26a of the cylinder rod 26. Thereby, the top plate 23 moves in the pressing direction on the bottom side, and the massive quartz glass 25 is pressed by the pressing surface 23 a of the top plate 23.

Here, the pressure of the top plate 23 is reduced at the initial stage of molding, and the maximum applied pressure is set at the final stage. For example, the pressure converted to per unit area of the pressing surface 23a of the top plate 23 at an early stage and 0.3~1.5Kg / cm ^2, at the final stage of molding 1.0~5.0Kg / cm ² can do. Moreover, the descent | fall speed of the top plate 23 can be 5-20 cm / min, for example. By setting the pressure and the descending speed in such a range, the quartz glass 25 can be easily deformed gradually, and a large force can be hardly applied to the mold 15 locally.

  While the quartz glass 25 is pressed by the top plate 23, the pressing force of the top plate 23 is applied as an outward force to the plurality of spacers 30 and the plurality of side plates 19 through the quartz glass 25. In the final stage of molding, the volume of the hollow portion 21 below the top plate 23 becomes the volume of the quartz glass 25, and the cylinder rod 26 and the top plate 23 are moved by a predetermined amount so that there is no gap inside. As a result, the pressure of the top plate 23 is finally applied to the plurality of spacers 30 and the plurality of side plates 19.

  At that time, since the upper end portions 19d of the plurality of side plates 19 are maintained in a state of being fitted into the through holes 24a of the support ring 24, the upper end portions 19d of the plurality of side plates 19 do not move outward. Further, the plurality of spacers 30 do not move outward at the same time. Furthermore, since the lower end portions 19e of the plurality of side plates 19 are maintained in a state of being fitted in the recesses 16a of the bottom plate 16, the lower end portions 19e of the plurality of side plates 19 do not move outward. Further, the plurality of spacers 30 do not move outward at the same time. Therefore, at the time of molding, the shape of the hollow portion 21 of the mold 15 is reliably maintained.

  Then, when the massive quartz glass 25 is formed into a plate-shaped body having a predetermined shape, the pressurization by the top plate 23 is finished.

  After the pressurization is completed, the plate-like quartz glass 25 is cooled by appropriately setting the cooling rate while being placed in the mold 15.

  At this time, the quartz glass 25 immediately after molding is disposed in close contact with the inner wall of the hollow portion 21 of the mold 15, and when the temperature is lowered from this state, the quartz glass 25 and the mold 15 corresponding to the temperature change are heated. Causes contraction. Since the shrinkage at this time is in accordance with the respective expansion coefficients, the shrinkage of the mold 15 is larger than that of the quartz glass 25.

  Therefore, when the frame-shaped support ring 24 contracts, the fitting surface 19f of the upper end portion 19d of the side plate 19 that abuts on the inner circumferential fitting surface 24a is pressed inward. However, since the quartz glass 25 is less contracted, the upper ends of the spacer 30 and the side plate 19 cannot move inward, and as a result, an outward force is applied to the support ring 24 from the side plate 19. Thereby, the fitting state of the fitting surface 19f of the side plate 19 and the fitting surface 24a of the support ring 24 is released, and the support ring 24 moves from the side plate 19 in the upward removal direction.

  When the recess 16a contracts due to the contraction of the bottom plate 16, the fitting surface 19g of the lower end portion 19e of the side plate 19 in contact with the inner peripheral surface thereof is pressed inward. However, since the quartz glass 25 is less contracted, the lower ends of the spacer 30 and the side plate 19 cannot move inward, and an outward force is applied from the side plate 19 to the recess 16a. Thereby, the fitting state of the fitting surface 19g of the side plate 19 and the fitting surface 16b of the concave portion 16a is released, and the spacer 30 is also interlocked with the side plate 19 at the same time as the side plate 19 moves in the upward direction from the concave portion 16a. Move in the upward direction.

  In this way, when the fitting state of the fitting surface is released, the plurality of spacers 30 and the plurality of side plates 19 are moved away from each other, and the molded quartz glass 25 is compressed by the mold 15. This can be prevented. And shaping | molding is completed by fully cooling.

  According to the molding apparatus 10 for the quartz glass 25 as described above, a plurality of side plates 19 that are combined in contact with each other to form the periphery of the side surface, and a spacer that is disposed adjacent to the inner surfaces of the plurality of side plates 19. 30 and the hollow portion 21 is formed, and in this state, the concave portion 16a of the bottom plate 16 or the support ring 24 is fitted around the side surface 19b of the plurality of side plates 19, so in different molding steps, Even when the same side plate 19 and the same bottom 16 and support ring 24 are used, the size of the hollow portion 21 can be easily changed by replacing the spacer 30 with a different thickness. . Therefore, different sizes of quartz glass can be formed using the side wall 19, the bottom portion 16, the support ring 24, and the like in common.

  In addition, the recesses 16a of the bottom plate 16 or the support ring 24 around the side surfaces of the plurality of side plates 19 are configured to maintain a fitted state during molding, and can be released from the fitted state during cooling after molding. At the time of cooling after molding, the fitting state is released, so that the plurality of side plates 19 are separated together with the plurality of spacers 30 to release the stress. Therefore, it is possible to suppress cracking and distortion of the formed quartz glass 25.

  In addition, since the frame-shaped support ring 24 is fitted to the outside of the plurality of side plates 19 combined with the spacers 30 arranged on the inside, the plurality of side plates 19 are attached when the mold 15 is assembled or disassembled. If they are combined and inserted into or removed from the support ring 24, they can be easily detached. At the same time, the support ring 24 is fitted around the side surface 19b of the side plate 19 and can be moved in the pulling direction by an external force, so that the quartz glass 25 is distorted or cracked during cooling. Can also be prevented.

  Furthermore, since the concave portion 16a of the bottom plate 16 is fitted to the outer surface of the lower end portions 19e of the plurality of side plates 19 combined with the spacers 30 disposed inside, when the mold 15 is assembled or disassembled. If a plurality of side plates 19 are combined and inserted into or removed from the recess 16a of the bottom plate 16, they can be easily attached and detached. At the same time, the concave portion 16a is fitted around the side surface 19b of the side plate 19 and can be moved in the pull-out direction by an external force. Therefore, distortion and cracking of the quartz glass 25 during cooling can occur. Can be prevented.

  Therefore, even if quartz glass having a different shape is formed by disposing different spacers 30 by using the plurality of side plates 19 and the support ring 24 and the bottom plate 16, the distortion and cracking of the quartz glass 25 are exactly the same. Can be prevented.

  Moreover, since the cross-sectional shape of the hollow portion 21 has a substantially square shape and the corner portion 27 is formed in an R shape, stress is concentrated on the corner portion 27 in the formed quartz glass 25 having a square shape. Can be prevented, distortion and cracking of the corner portion 27 can be prevented, and the yield can be greatly improved.

  In the first embodiment described above, an example in which the plate-like quartz glass 25 is formed has been described. However, the present invention can be appropriately applied to a molded body other than the plate-shaped body.

  Further, in the above embodiment, the spacers 30 are arranged on each of the side plates 19 and the inner surface of the hollow portion 21 is formed only by the inner surface 30a of the spacer 30, but the hollow space is formed by using a small number of spacers 30. A part of the inner surface of the portion 21 can be constituted by the inner surface 19a of the side wall 19, and a spacer 30 having a different shape can be used if it can be molded.

  Further, in the above description, an example in which the plurality of side plates 19 and the spacers 30 are both made of graphite and are disposed in direct contact with each other is described. However, for example, felt carbon or the like is provided between each side plate 10 and the spacers 30. As described above, members having different thermal expansion coefficients may be arranged to prevent the side plate 19 and the spacer 30 from being joined after heating and pressing.

  Moreover, although the example which presses the top plate 23 with the cylinder rod 26 of one hydraulic cylinder was demonstrated above, you may press the top plate 23 using the several cylinder rod 26, and also with a hydraulic cylinder, It is also possible to use other mechanical forming means.

Further, in the above description, the example of forming at a temperature not lower than the crystallization temperature and not higher than the softening point temperature has been described. However, the forming may be performed at a temperature higher than the crystallization temperature of the quartz glass 25. For example, the temperature may be higher than the softening point.
[Embodiment 2 of the Invention]

  Next, a second embodiment will be described. FIG. 4 shows a molding apparatus according to the second embodiment.

  In the molding apparatus 10 according to the second embodiment, in the hollow portion 21 having a substantially square cross-sectional shape, a plurality of inclined sides 29 are provided on the side edge of the spacer 30 forming the corner portion 27 so as to have an obtuse angle. Others have the same configuration as the molding apparatus 10 of the first embodiment.

  Even in such a molding apparatus 10, stress can be prevented from being concentrated on the corner portion 27 in the formed substantially square-shaped quartz glass 25, so that distortion and cracking of the corner portion 27 can be prevented. As in the first embodiment, the yield can be greatly improved.

Examples will be described below.
Comparative Example 1

  A synthetic quartz ingot produced by a direct method using silicon tetrachloride having a diameter of 400 mm, a length of 500 mm and a weight of 138 kg as a raw material is placed in a quadrilateral graphite mold 15 having a quadrilateral shape with a side of 560 mm. It was set in a hot molding machine. A top plate 23 having a thickness of 30 mm was placed on the upper surface of the ingot, and a receiving plate 17 having a thickness of 30 mm was placed on the lower surface of the ingot. Further, a cylinder rod 26 is disposed on the top plate 23.

Then, after reducing the pressure in the vacuum chamber 11 to 50 Pa with a vacuum pump, pure nitrogen gas was filled to a pressure of 3 × 10 ⁴ Pa.

  Then, temperature increase was started, the temperature was increased to 1620 ° C. in 3 hours, and held at 1620 ° C. for 0.5 hour.

  Thereafter, the top plate 23 was pressed by the cylinder rod 26 at an initial load of 3.5 ton and a pressing speed of 5 mm / sec to form an ingot. When the displacement stroke of the cylinder rod 26 reached a calculated position where the hollow portion 21 below the top plate 23 had no gap, pressurization was terminated, and the temperature of the carbon heater 13 was lowered and rapidly cooled to 300 ° C.

  Then, the mold 15 was taken out and the molded product was taken out. The molded product had a side of 560 mm and a height of 200 mm.

When the molded product was observed, the entire surface was transparent, but some cracks occurred at the corners of the four corners. Also, some residual strain remained at the four corners. From this molded product, a plate-like body having a side of 460 mm, a thickness of 180 mm, and a weight of 84 kg was obtained as an effective square.
Example 1

  As the mold 15, a square shape having a side of 560 mm, a spacer 30 with a plate thickness of 30 mm, and a corner portion of R40 was used. Otherwise, the molded product was molded in the same manner as in Comparative Example 1. The molded product had a side of 500 mm and a height of 252 mm.

When the molded product was observed, the entire surface was transparent, but cracks could not be confirmed in the R shape at the four corners, and no distortion could be confirmed except for 15 mm around the periphery of the molded product. A plate-like body having a side of 460 mm, a thickness of 235 mm, and a weight of 109 kg was collected from the molded product as an effective square.
Example 2

  Comparative Example 1 is the same as the mold 15 except that a square shape with a side of 560 mm, a spacer 30 with a plate thickness of 30 mm, a corner portion with an inclined surface of 34 mm and two dividing lines is used. A molded product was molded in the same manner. The molded product had a side of 500 mm and a height of 253 mm.

When the molded product was observed, the entire surface was transparent, but no cracks and residual strain could be confirmed at the four corners. A plate-like body having a side of 470 mm, a thickness of 235 mm, and a weight of 114 kg could be collected from this molded product as an effective square.
Example 3

  Comparative Example 1 is the same as that of Comparative Example 1 except that the mold 15 has a square shape with a side of 560 mm, the plate thickness of the spacer 30 is 20 mm, and the corner portion has an inclined surface of 34 mm and two dividing lines. A molded product was molded in the same manner. The molded product had a side of 520 mm and a height of 233 mm.

  When the molded product was observed, the entire surface was transparent, but no cracks and residual strain could be confirmed at the four corners. From this molded product, a plate-like body having a side of 480 mm, a thickness of 213 mm, and a weight of 108 kg was collected as an effective square.

It is a schematic longitudinal cross-sectional view which shows the shaping | molding apparatus of Embodiment 1 of this invention. It is a schematic longitudinal cross-sectional view which shows the mold of the shaping | molding apparatus of the embodiment. It is a horizontal end view of the side wall part of the shaping | molding apparatus of the embodiment. It is a lateral end view of the side wall part of the shaping | molding apparatus of Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Molding apparatus 11 Vacuum chamber 13 Carbon heater 15 Mold 16 Bottom plate 16a Recessed part (fitting means)
18 bottom part 19 side plate 20 side wall part 20a, 20b taper part 21 hollow part 23 top plate (pressurizing part)
24 Support ring (fitting means)
25 Quartz glass 26 Cylinder rod (Molding means)
30 Spacer

Claims (7)

A hollow part that can accommodate quartz glass, a mold made of a material having a larger expansion coefficient than that of the quartz glass, a pressure part that is movably disposed inside the hollow part, and a hollow part that is accommodated in the hollow part A heating device that heats the quartz glass, and is a molding apparatus that presses the quartz glass in the hollow portion with the heating unit while being heated by the heating unit and forms the glass into a predetermined shape.
The mold includes a plurality of side plates that are combined in a state of being in contact with each other to form a side surface periphery, a fitting unit that is fitted around the side surface of the plurality of combined side plates, and at least one of the plurality of side plates. A spacer disposed adjacent to one inner surface;
The hollow portion is formed on the inner side of the combined side plates and the spacer,
The fitting state is maintained by the fitting means at the time of the molding, and at the time of cooling after the molding, the outward load applied to the plurality of side plates is based on the difference in expansion coefficient between the mold and the quartz glass. The fitting state between the plurality of side plates and the fitting means is such that the fitting state of the fitting means is released by force, and the side plates move through the spacer, so that the plurality of side plates are separated from each other. An apparatus for forming quartz glass, wherein a mating surface is formed in a tapered shape. The quartz glass molding apparatus according to claim 1, wherein the spacers are arranged independently for each of the plurality of side plates. The fitting means has a frame-shaped support ring that is fitted to the outside of the plurality of side plates, and the fitting surfaces slide with each other by the outward force so that the support ring moves in the removal direction. The quartz glass forming apparatus according to claim 1, wherein the plurality of side plates are configured to move in directions away from each other. The fitting means has a bottom portion with a recess into which the lower end portions of the plurality of side plates are fitted, and the plurality of side plates move in a direction of removal from the recess of the bottom portion by the outward force. The quartz glass molding apparatus according to any one of claims 1 to 3, wherein the plurality of side plates are configured to move in directions away from each other. The cross-sectional shape of the hollow portion has a substantially polygonal shape, and the corner portion of the shape is formed in an R shape by a side edge of the spacer. Quartz glass molding equipment. The cross-sectional shape of the said hollow part exhibits substantially polygonal shape, and the some inclined surface was formed so that the corner part of this shape might become an obtuse angle by the side edge of the said spacer. The apparatus for molding quartz glass according to any one of the above. In the method for forming quartz glass, in which the massive quartz glass placed in the mold is heated and pressed,
The mold includes a bottom portion, a side wall portion disposed at an upper portion of the bottom portion, and a spacer disposed adjacent to the inside of the side wall portion, and pressurizing while heating the quartz glass by a heating unit. A method for molding quartz glass, characterized in that the quartz glass is pressure-molded by means.

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