Abstract: A method for producing formed semiconductor articles with predefined shapes such as core tubes for CVD production of bulk polysilicon. The method is characterized by thermal spray deposition of the semiconductor material in a on a temperature controlled rotating mandrel that is shaped complementarily to the desired article shape, and by later separation of the formed semiconductor body from the mandrel by thermal contraction, melting, or chemical reduction of the mandrel size.

Abstract: Apparatus suitable for vitrifying nuclear waste comprises a tunable microwave cavity connected by a first wave guide to a source of microwave energy; cooling coils for cooling the exterior of the cavity; a hopper for loading particulate fusible material to the interior of the cavity; within the cavity a crucible made of melted and re-solidified fusible particulate material; an exit-chamber connected by a second waveguide to a second microwave source; and a pipe for supplying argon gas to the exit chamber so that a plasma torch can be generated. The separating of the crucible form the cavity walls by unmelted material gives significant advantages in case of cleaning and reduced energy consumption.

Abstract: A glass substrate for an information recording medium has an acid resistance represented by an etching rate of at most 45 nm/min. upon contact with a hydrofluoric acid having a temperature of 50° C. and a concentration of 0.1 weight %. The glass substrate has a recording surface having an average surface roughness Ra smaller than 0.3 nm.

Abstract: The invention concerns an automated method for producing a blown glass body, in particular a glass wall of an electrochemical sensor, wherein an immersion tube (10), through which air or gas can flow, is immersed into molten glass (8) and subsequently withdrawn to remove an amount of molten glass from the molten glass mass, and wherein the removed glass is blown into the form of the glass body to be produced by means of the air or gas flowing through the immersion tube (10), comprising the following features:

Abstract: A method for producing glass balls, wherein a glass flow is fed between two rollers which are driven synchronously but counter-rotatingly in a flow direction, from a feed tank containing a mass of molten glass. The rollers have hemispherical depressions distributed over the circumference and form spherical beads on a thin glass strip successively in the region of an imaginary contact tangent. A thickness of the glass strip is fixed by the spacing between the rollers externally of the depressions in the region of the contact tangent. Crude balls are separated from the glass strip by a separating device, once the glass strip, containing the spherical beads, is cooled. The crude balls are subjected to a cold surface finishing treatment.

Abstract: Disclosed is a method of and device for manufacturing a molded glass object. In the method, glass melt is made to flow from the front end portion of a nozzle; a prescribed weight of the glass melt flowing out is received by a glass melt receiving portion provided on a forming mold moved beneath the nozzle, wherein multiple forming molds are sequentially moved beneath the nozzle; the glass melt gob received is moved from the glass melt receiving portion to a hollow provided on said forming mold; and in the hollow, a molded glass object is formed while blowing gas upward through a gas outlet provided in the bottom of the hollow. The method is characterized in that the front end of said nozzle is constantly positioned outside the space vertically above said gas outlet. Methods of manufacturing press molded articles of glass and optical glass elements are described. In these method, a molded glass object manufactured by the above method is heated, softened, and press molded or precision press molded.

Abstract: Disclosed are a shaping mold for producing an optical fiber guide block which permits highly accurate positioning and fixing of optical fibers, an optical fiber guide block having such excellent properties, processes for the production of these, and an optical fiber array.

Abstract: A silica glass forming method is a method of pressing a synthetic silica bulk having at least a set of opposed surfaces, on the surfaces under a high temperature condition by a presser, wherein an elastic member with permeability is placed between the presser and the surfaces of the synthetic silica bulk pressed by the presser and wherein the synthetic silica bulk is pressed through the elastic member by the presser. This method is able to reduce bubbles remaining inside the synthetic glass formed product after the forming to a sufficiently small amount. Therefore, it becomes feasible to provide the method that permits high-yield production of silica glasses with excellent optical characteristics.

Abstract: In a method of producing a glass gob by continuously dropping a molten glass 9 from a nozzle 2 in a dropping direction, a gas flow 20 is caused to continuously flow in the dropping direction along an outer peripheral surface of the nozzle 2 at a predetermined flow rate. The gas flow 20 applies a wind pressure to the molten glass 9 appearing from a nozzle end 2a of the nozzle 2 to drop the molten glass 9.

Abstract: A device and process for forming hollow glassware comprising producing solid glass blanks in a manufacturing line, storing the blanks, feeding the blanks to a manufacturing line for forming hollow glassware, preheating the blanks during the feeding step, supplying the preheated blanks to a heating stage, heating to form solid plastically deformable glass globs, transferring the glass gobs to a blow molding stage and blow molding the glass gobs supported by a bottom lifter in a blow mold.

Abstract: A method of manufacturing a glass substrate for an optical disk using a press-mold formed of a super-hard material and having a surface of a prescribed roughness. A track pattern is formed in the surface of the glass substrate by inserting the substrate and a stamper containing track patterns into the press mold and pressing the substrate against the stamper. A film-like thermoplastic synthetic resin is disposed between the glass substrate and the stamper, and the glass substrate is heated to the distortion temperature point of glass.

Abstract: Glass raw material is fed to a glass furnace to prepare molten glass. At least one metal compound from one of the following metals: aluminum, titanium, silicon, zinc, magnesium, iron, chromium, cobalt, cerium or calcium is supplied to a foam layer formed on the molten glass to diminish or extinguish the foam layer.

Abstract: There are disclosed a method of manufacturing a thin-plate glass having a good flatness with a high mass productivity and a method of manufacturing a high-quality and high-performance glass substrate for an information recording medium and a magnetic recording medium with a high mass productivity. A glass gob is press-formed between upper and lower dies to form a thin-plate glass. The press forming is finished when the inside of the thin-plate glass is at a softening point Ts or a higher temperature. Subsequently, warp modification pressing is performed to modify a warp of the thin-plate glass. The warp modification pressing is finished when the inside of the thin-plate glass is at a transition point Tg or a higher temperature.

Abstract: A molded glass substrate for a magnetic disk is manufactured in the following manner: press-molding a heated glass material in the inside space of a molding die including a pair of dies, each having a predetermined processing plane, and a barrel die for slidably guiding the dies while forming the outer circumference of the glass material joined to both principal surfaces corresponding to the dies as a molding-free face; cooling the press-molded glass substrate; and forming a predetermined through-hole in the central portion of the glass substrate. This method enables manufacturing that prevents generation of industrial waste, such as glass power, abrasive, and solvent, as much as possible.

Abstract: A method for supplying a glass molding material by dropping it from a higher level onto a molding surface of a lower mold of a mold constituted of an upper mold and the lower mold, in which a guide means is used for dropping the glass molding material and is disposed at a position such that the glass molding material drops onto the molding surface of the lower mold, and the guide means used for this method are disclosed. Moreover, a method for supplying a glass molding material to a molding surface of a lower mold of a mold constituted of an upper mold and the lower mold, in which after the glass molding material is supplied to the molding surface of the lower mold the position of the glass molding material is corrected so that the vertical center of the glass molding material substantially coincides with the center point of the molding surface of the lower mold, and a position correcting means used for this method are disclosed.

Abstract: A fabrication method of graded index silica glass is disclosed. The method according to the present invention includes the steps of dispersing to form sol by mixing a starting material with a dispersion medium; molding the sol into a moisturized gel with a predetermined shape using a molding frame and separating the moisturized gel from the molding frame; drying the moisturized gel under a predetermined temperature and humidity level to remove the dispersion medium and to form a first dry gel having a predetermined moisture content distribution, hydrolyzing the moisture remained in the first dry gel and an additive solution by putting the first dry gel into the additive solution; re-drying the first dry gel, which underwent said hydrolysis, to form a second dry gel; and, thermal processing the second dry gel by supplying reaction gas thereto, removing impurities therefrom and annealing for isolation.

Abstract: An alkali-free glass applicable to a light transparent glass substrate in a liquid crystal display essentially consists, by weight, of basic elements of 40-70% SiO2, 6-25% Al2O3, 5-20% B2O3, 0-10% MgO, 0-15% CaO, 0-30% BaO, 0-10% SrO, and 0-10% ZnO, and a fining agent of a combination of 0.05-3% Sb2O3 and at least one of 0.05-2% SnO2 and 0.005-1% Cl2, which fining agent makes the resultant glass free from bubbles without the use of toxic As2O3 which has been known as the fining agent in the art.

Abstract: A method for forming a glass optical element by press forming a thermally softened glass material with a preheated forming mold composed of an upper and a lower die. The glass material, the upper die and the lower die are heated within respectively prescribed temperature ranges, the preheating temperature of the upper die being below the preheating temperature of the lower die. The thermally softened glass material is pressed in the preheated forming mold, and the forming surfaces of the upper and the lower dies are cooled simultaneously with the start of the initial pressing, during the process of the initial pressing, or after the completion of the initial pressing.

Abstract: Disclosed is a process for producing a glass substrate for an information recording medium by press-shaping a molten glass which gives a glass containing 0.1 to 30 mol % of TiO2, 1 to 45 mol % of CaO, 5 to 40 mol % of total of MgO and the above CaO, 3 to 30 mol % of total of Na2O and Li2O, 0 to 15 mol % of Al2O3 and 35 to 65 mol % of SiO2 and having properties of a liquidus temperature of 1,360° C. or lower and a viscosity of at least 10 poise in a shaping-allowable temperature range, or by preparing a preform formed of a glass which contains 0.1 to 30 mol % of TiO2, 1 to 45 mol % of CaO, 5 to 40 mol % of total of MgO and the above CaO, 3 to 30 mol % of total of Na2O and Li2O, 0 to 15 mol % of Al2O3 and 35 to 65 mol % of SiO2 and has properties of a liquidus temperature of 1,360° C. or lower and shaping the preform in the form of a disc by a re-heat pressing method.

Abstract: A process for forming a glass sheet, which is a process for continuously forming a glass sheet, and which comprises a step of introducing a vapor film-forming agent, which is not vapor at least around room temperature and which is vapor at a temperature above the glass transition point of the glass, into a support composed of a structure or a material capable of internally containing liquid, and a step of sliding the support and the glass of which temperature is above the glass transition point against each other via a thin layer of a vaporized vapor film-forming agent.

Abstract: A polished glass disk medium substrate table for use as a substrate for a hard disk, a hard disk containing the substrate and methods for making the substrate. Glass forming raw materials are formed into a disk having a diameter between about 70 mm and about mm, a thickness between about 0.7 mm and about 0.9 mm, a flutter of less than 90 nm at 10,000 rpm.

Abstract: A method for making preforms for use in a glass lens molding process and molding lenses is disclosed. A glass rod is formed preferably by dipping a bob into a homogeneous melt of a predetermined optical glass, maintaining the temperature of the homogeneous melt at least the melt temperature and producing a rod of glass from the homogeneous melt, allowing the rod of glass to cool and solidify, and then cutting the rod of glass into predetermined lengths. By withdrawing the bob at a predetermined pull rate the rod of glass can be produced with a predetermined diameter. Using a constant pull rate, the rod of glass will be cylindrical in shape and can be cut into a series of individual cylindrical preforms. The preforms can be inserted into a compression molding apparatus for the forming of a glass optical element therewith. The orientation of the preform is such that the cut planar surfaces of the preform are parallel to the direction of compression of the molding process.

Abstract: A semiconductor material having more excellent electric characteristics than polycrystalline semiconductor materials and readily formed on various kinds of substrates is provided. The semiconductor material is made of substantially single crystalline semiconductor crystal grains 3a. These crystal grains 3a are preferentially oriented in a common surface orientation, such as {100}, {111} or {110}-orientation, and grain boundaries 3b of adjacent ones of the crystal grains 3a are in substantial lattice matching with each other at least in a part thereof. In case of {100} orientation, each crystal grain 3a has an approximately square shape, and they are regularly aligned in rows and columns. In case of {111} orientation, each crystal grain 3a has an approximately equilateral hexagonal shape, and they are aligned in an equilateral turtle shell pattern.

Abstract: The invention relates to a strong UV absorbing glass consisting essentially of, expressed in cation percent, 15-30% SiO.sub.2, 50-60% B.sub.2 O.sub.3, 2-5% Al.sub.2 O.sub.3, 0-6% Li.sub.2 O, 0-3.0% Na.sub.2 O, 14-20% K.sub.2 O, 0.5-1.0% CuO, 0.4-0.7% SnO.sub.2, 0.5-1.5% Cl, and 0.7-1.5% Br. An essentially haze-free version of the glass is disclosed. A UV absorbing coating material made by suspending ground particles of the inventive glass in a suitable matrix is also disclosed.

Abstract: In a method for molding glass products having a fine structure as of an optical fiber holder with a high size precision, a mold used for the molding has the fine structure in a size such that a size difference occurring when the glass product is cooled down to a room temperature where at the end of molding with a pressure a size of the fine structure of the mold for glass product and a size of a fine structure of the glass product formed by transfer of the fine structure of the mold are the same as one another is so adjusted that a size of the fine structure of the completed glass product falls within a permissive size precision range. The mold may has a size satisfying, as a size of a fine structure at a room temperature, a formula [1+(.alpha.g-.alpha.m).times..DELTA.T+.alpha.g'.times..DELTA.T'].times.Sg, wherein Sg denotes a size of a fine structure of thc glass product at the room temperature; .alpha.

Abstract: A process for forming a glass sheet, which is a process for continuously forming a glass sheet, and which comprises a step of introducing a vapor film-forming agent, which is not vapor at least around room temperature and which is vapor at a temperature above the glass transition point of the glass, into a support composed of a structure or a material capable of internally containing liquid, and a step of sliding the support and the glass of which temperature is above the glass transition point against each other via a thin layer of a vaporized vapor film-forming agent.

Abstract: The present invention is directed to an apparatus and method for forming glass article from sheet glass. More specifically the apparatus comprises a mold, a plunger being cooperative alignment with the mold, wherein the mold and the plunger form a cavity exhibiting the shaped of the glass article, an outer trimmer for separating the glass article from the surrounding excess sheet glass, and an inner trimmer for forming the aperture in the glass article, and the method involves forming the aperture during the hot-forming process, therefore eliminating a post-formation step.

Abstract: The present invention relates to a glass envelope for an illuminating device, the glass envelope comprising a gas channel, a pair of electrodes in communication with the gas channel and a glow-discharge lamp as a source of free electrons coupled to the glass envelope to assist the starting of the illuminating device in dark conditions, for example at night. Preferably, the glass envelope has a front and back surface laminated and integrated together to form a unitary body essentially free of any sealing materials.

Abstract: The invention relates to lenses such as aspherical lenses and to a process for their manufacture. According to the invention, the lens is composed of a glass matrix including the constituents below in the following weight proportions:______________________________________ SiO.sub.2 65-85% Al.sub.2 O.sub.3 0-10% B.sub.2 O.sub.3 0-20% Li.sub.2 O + Na.sub.2 O + K.sub.2 O 3-20% CaO + MgO + BaO 1-15% FeO + Fe.sub.2 O.sub.3 0-0.1%, ______________________________________wherein the K.sub.2 O content is equal to or less than 1% and the BaO content is equal to or less than 1%.

Abstract: A material handling apparatus for processing heated formed ferrous metal products and/or glass products made of a face centered cubic crystal intermetallic alloy of a metal aluminide having the property of withstanding repeated thermal cycling from ambient temperature to about 1600.degree. F. wherein the metal is selected from the group consisting of a group VIII metal of the Periodic Table. Also described is an aluminide roll that also is characterized as retaining its ultimate tensile strength at 1600.degree. F. of at least 75% of the tensile strength the roll had at ambient room temperature.

Abstract: A process of making hermetically sealed glass semiconductor packages by injecting molding an electronic device within a body of molten thermoplastic glass which is solidified by cooling. The glass has a sealing temperature not over 350.degree. C. and a CTE not over 110.times.10.sup.-7 /.degree.C. and may be made of tin-phosphorus oxyfluoride or lead sealing glasses.

Abstract: A method to produce fused quartz particulates from quartz sand is disclosed employing continuous withdrawal of the molten material from a furnace apparatus. The molten material is rapidly cooled as withdrawn causing thermal fracture which is followed by mechanically pulverizing the fragments to a desired particle size.

Abstract: A method and apparatus for delivering a coated glass stream having a first inner layer and a second outer layer wherein the method comprises providing a vertical orifice, delivering molten glass from a first source through the orifice, providing a gap about the orifice intermediate its upper and lower ends, delivering glass from a second source about the gap such that the glass from the second source flows through the gap to provide an outer layer about the glass from said first source as it flows through the orifice, and controlling the size and shape of the gap parallel to the flow and the size of the gap perpendicular to the flow such that the gap provides sufficient flow resistance and the gap is of sufficient size and shape to prevent clogging.

Abstract: A press head drive cylinder control having a force sensing, force signal providing load cell on the drive cylinder of a glass molding press. The glass molding press having a base, a mold table rotatably mounted on the base, a plurality of mold positions on the table for locating from one to a plurality of molds thereon, at least one mold at a mold position, a press head, a press head tower, and a press head drive cylinder supporting the press head and being reciprocally mounted on the press head tower for movement of the press head to and from a mold aligned at a molding station. The press head drive cylinder control responds to force signals from the load cell to control the press head drive cylinder location, movement, and pressing force, during glass molding.

Abstract: Method and apparatus for producing vitreous optical elements by injection molding, which essentially includes the stages of: melting down a glass material into a molten state in a viscosity at or lower than a working point of the glass material; injecting molten glass under pressure into a mold cavity defined between transfer surfaces of relatively movable mold members of a mold assembly unit in communication with a sprue connecting the mold cavity with an injection port on the outer side of the mold assembly unit; and applying a predetermined pressure on the glass material in the mold cavity while cooling the mold assembly unit down to a temperature in the vicinity of yielding point of the glass material.

Abstract: A process for the manufacture of an object displaying a message includes the following steps: preparation of a support for the message having dimensions less than the dimensions of the object; manual or automatic application of the message to the support; introduction of the support carrying the message on its surface into a molten transparent material so as to surround the support with a sufficient quantity of molten transparent material to enable subsequent formation of a transparent body which completely surrounds the support; and formation of the transparent body by thermomechanical means.

Abstract: Cristobalite-containing silica glass is provided wherein .alpha.-cristobalite in the shape of a small sphere or a small, round-edged or sharp-edged, three-dimensional region is dispersed in the silica glass matrix. The diameter of each .alpha.-cristobalite sphere or region is, in the range of 0.1 um to 1000 um, and the content of the .alpha.-cristobalite is at least 10 wt. %. The cristobalite-containing silica glass is produced by heating a mixture of two kinds or more of crystalline silicon dioxide powder with melting points different from each other by 20.degree. C. or more. The mixture contains silicon dioxide having the highest melting point in the range of 10 wt. % to 80 Wt. % and is heated at temperatures ranging from the lowest melting point to a temperature lower than the highest melting point.

Abstract: The present invention is directed to a method for forming glass articles containing internal enclosed channels.

Abstract: The specification describes a method for the manufacture of fluoride glass optical fibers which are covered with a protective coating of phosphate glass. The coating is produced by dipping the fluoride glass preform in a phosphate glass melt prior to drawing the optical fiber. The fluoride glass is ZBLAN. The phosphate glass has a glass transition temperature below 200.degree. C., which allows the dipping step to be carried out at a relatively low temperature where the preform temperature is maintained well below the crystallization temperature of the fluoride glass, and also where the viscosity of the fluoride glass preform is substantially higher than the viscosity of the phosphate glass coating material.

Abstract: Air is blowed before an annealing step to corner portions in an inner face portion of a glass panel which has been press-formed in a mold to cool that portions to be stronger than the other portion whereby a temperature difference between the corner portions and the other portion is reduced.

Abstract: A liquid material such as molten silicon is stored in a crucible. A liquid material, which is identical to and held in the same conditions as the liquid material in the crucible, is continuously supplied from an auxiliary crucible to the crucible to keep constant the surface level of the liquid material in the crucible. The liquid material is continuously pulled up from the crucible at a predetermined speed while the liquid material is being solidified into a solid material such as a ribbon-like thin web of single-crystal silicon.

Abstract: In forming a piano-convex lens from a column-like lens blank by heating the blank to a temperature higher than the transition temperature thereof and by pressurizing an upper die with a closed space formed between the blank and the upper die, there are alternately repeated operations of pressurizing the upper die and stopping the application of pressure thereto. Through the control of the amount of displacement of the upper die, the maximum pressure of gas in the closed space at each pressurizing step is so controlled: as to be low according to the surface viscosity of the blank to the extent that no local concave deformation in the surface of the blank is produced; and as to be high to the extent that gas caught in the closed space is discharged at each step of stopping the application of pressure.

Abstract: Optical glass preforms for use in subsequent molding processes for the production of lenses are produced which have a controlled peripheral edge wall geometry. Gobs of molten glass of predetermined weight and volume are dripped onto a lower mold surface. A pressing head including a sleeve and a plunger are lowered such that the sleeve surrounds the gob. The plunger is then depressed such that the upper mold surface of the plunger resides in a predetermined elevation above the lower mold surface thereby forcing the gob to conform to the cavity created within the sleeve and between the upper and lower mold surfaces. In such manner the sleeve serves as a form or exterior boundary for the resultant preform such that a preform is produced which requires no grinding or polishing prior to its use in subsequent molding operations.

Abstract: A method of producing amorphous sample bodies that can be used for optical spectral analysis and X-ray spectral analysis, by batch-wise smelting in a crucible a mixture of analysis sample and a flux. The method is characterized by allowing a controlled flow of molten material to run out of the crucible and successively down onto a horizontal receiving surface and there form the sample bodies. The mixture is smelted suitably at a temperature of between 800.degree. and 1300.degree. C., preferably at about 1000.degree. C., and is carried out in a crucible having a hole in the bottom thereof. A apparatus for producing such amorphous sample bodies is also disclosed. The apparatus includes a smelt crucible provided with an opening in its lower part and which is designed to be downwardly tapered at least inside in order to prevent the mixture from coming out, but to facilitate running of molten material through the opening.

Abstract: In a method of manufacturing glass optical elements at high operational efficiency, a mass of molten glass which is dropped down is cut at a first step by a wind blast into a sequence of glass gobs each of which is received by a gas stream spouted from a lower portion. Each glass gob is kept afloat with a gas stream spouted to be adjusted to a temperature corresponding to a glass viscosity between 10.sup.5.5 and 10.sup.9 poises. Thereafter, the glass gob is pressed in a third step by the use of a pair of forming dies kept at a temperature which corresponds to a glass viscosity between 10.sup.8 and 10.sup.12 poises and which is lower than the temperature of the glass gob. During the third step, the forming dies are cooled to a temperature lower than the temperature corresponding to a glass viscosity of 10.sup.13.4 poises with the glass gob kept within the forming dies and are thereafter opened to release a shaped article from the forming dies.

Abstract: When blank-molded optical glass bodies are manufactured according to known methods based on blank-molding technology, the product exhibits rings in the glass and folds as well as an impression that precisely coincides with the contact surface of the parison inside the pressing die before the pressing operation. These defects are not permissible in blank-molded lenses, however, because they cause an undesirable optical effect such as changing the glare value in automobile headlights. Such defects are process-dependent and are caused by the fact that the transfer of the parison to the pressing die and the pressing itself are two separate operations that are performed with different tools.

Abstract: A method of making gob preforms for the optical quality lens molding comprising: i) ejecting a measured gob molten glass through an exit in a stem of the container of a supply of molten glass; ii) allowing the gob to settle under gravity from the exit to a catching tool while heating the gob and the catching tool; and iii) continuing to heat the gob and tool until the gob is round.

Abstract: Optical glass of cubic, spherical or polygonal shape is fire polished on a graphite or Cr.sub.2 O.sub.3, concave surface with a surface roughness of 100 Angstroms or less. The optical glass having a surface roughness of 400 Angstroms or less is placed on the concave surface and fire polished by heating the optical glass between the yield point and softening point of the glass in a reducing atmosphere if the concave surface is made of graphite. A Cr.sub.2 O.sub.3 concave surface is required for Pb.sup.+2 containing glasses. The molded preform obtained has a surface roughness of 100 Angstroms or less.

Abstract: The invention relates to a cooling method and a mold arrangement for the manufacture of glass articles or similar materials. The mold arrangement of this type includes a plurality of cooling passageways distributed independently and longitudinally around of the periphery of said mold, for the flow of a cooling fluid. A fluid distribution chamber coupled in coincidence with the cooling passageways, for the flow of the cooling flow, independently for each one of said passageway of the mold. A fluid regulating plate is coupled with the fluid distribution means, to regulate independently the flow of cooling in each one of the passageways of the mold, to regulate and control the cooling curve of said mold.

Abstract: A quartz glass component having a projection on a flat face is manufactured by molding a quartz glass body at a high temperature and under high pressure. The heating temperature is set to a range of from 1800.degree. to 2000.degree. C. and slight pressure is applied by the female die which forms the projection, or pressure in a direction against gravity. The molding die includes a graphite frame surrounding a molding space formed by a female die and a receiving die sandwiching the quartz glass body in the graphite frame. The space between the receiving die and the female die is width-reducible, the compositions of the graphite frame and the two graphite dies are made to differ, the female die and receiving die contacting the quartz glass body during pressure molding have a plurality of gas-permeable micropores such as in sintered graphite for example and are formed by a high-purity graphite material having air permeability.