JP7387580B2 - Heat molding jig, heat molding device, and heat molding method - Google Patents

Description

The present invention relates to a hot molding jig, a hot molding device, and a hot molding method, and particularly to a hot molding jig, a hot molding device, and a heating method for hot molding a quartz glass ingot to form a quartz glass molded body of a predetermined shape. Regarding the molding method.

One method for manufacturing a synthetic quartz glass body suitable for optical applications is to manufacture an ingot of synthetic quartz glass, then heat the quartz glass ingot at a predetermined temperature to soften it, and then use a mold of a predetermined shape to soften the quartz glass ingot. A manufacturing method involving molding is known.
The quartz glass ingot is manufactured, for example, by a method in which a silica raw material such as silicon tetrachloride is subjected to a hydrolysis reaction using oxygen and hydrogen, and glass fine particles are deposited on a target.

A mold (heat molding jig) used in a method of heating this quartz glass ingot and molding the softened quartz glass into a predetermined shape is proposed in Patent Document 1.
This proposed mold is a mold for heating and molding a quartz glass ingot in an upright state, and the quartz glass ingot is housed in the mold and softened by heating the quartz glass ingot. Silica glass is molded into a predetermined shape.

Specifically, as schematically shown in FIG. 8(a), a molded part 51 having an internal shape (inner peripheral surface shape) according to the shape of the bottom surface and outer peripheral surface of the quartz glass molded body, and the molded part The support part 52 is installed above the quartz glass ingot X and supports the outer peripheral surface of the quartz glass ingot X with a cylindrical inner peripheral surface.

In this way, in the mold described in Patent Document 1, since the outer circumferential surface of the quartz glass ingot X is supported by the supporting section 52, the supporting section 52 is in contact with the outer circumferential surface of the quartz glass ingot X. As the heating and softening progresses, the outer circumferential surface of the quartz glass ingot X slides on the inner circumferential surface of the support section, and finally, as shown in the transition state shown in FIGS. 8(b) and 8(c), the quartz glass ingot Contained and molded.

Japanese Patent Application Publication No. 2015-120619

As shown in FIG. 8(a), the columnar quartz glass ingot X manufactured by the method described above has many layered striae C remaining along its growth surface. When the quartz glass ingot X in which such layered striae C remain is heated and softened in the mold 51, it is deformed to flow downward from the outer periphery as described above, and as shown in FIGS. As shown in (c), it gradually becomes longer horizontally.

However, the quartz glass molded body formed in the mold 51 has veins in the lower part of the quartz glass molded body at the outer periphery where the glass flow distance is the longest during heating and softening, as shown in FIG. 8(b). The material C bends in the vertical direction due to the frictional force of the bottom plate. As shown in FIG. 8(c), the quartz glass molded body has bent portions, resulting in non-uniform optical properties, which poses a problem that it is not suitable for optical applications. Incidentally, FIG. 9 shows an enlarged view (cross-sectional view) of the bent striae C, and hereinafter, such a striae will be referred to as a bent striae C1.

The inventors of the present application have conducted extensive studies on this bending striae, and found that in the process in which a quartz glass ingot is heated and softened and deformed, horizontal deformation is suppressed by friction between the bottom of the ingot and the bottom of the mold. It was discovered that the rate of deformation in the vertical direction becomes faster than the rate of deformation in the horizontal direction, and as a result, bending striae occur, leading to the invention.

The object of the present invention is to provide a heating molding jig, a heating molding apparatus, and a heating molding method that can suppress the occurrence of bending striae in a quartz glass molded body that is formed by heating and softening a quartz glass ingot in a mold. Our goal is to provide the following.

The heat molding jig according to the present invention, which has been made to solve the above problems, includes a molding tray that has a bottom part and a side part and forms a quartz glass molded body of a predetermined shape from a quartz glass ingot; a mounting table provided on the bottom part of the tray and on which the quartz glass ingot is placed , and the quartz glass ingot is placed on the periphery of the upper surface of the placing table on which the quartz glass ingot is placed. It is characterized in that an inclined surface is formed that slopes downward in the vertical direction, which is the direction in which gravity acts, with respect to the upper surface .
Note that this mounting table may be provided separately from the bottom of the molding tray, or may be provided integrally with the bottom of the molding tray.

Further, it is preferable that the angle of inclination of the inclined surface formed on the mounting table with respect to the outward extension of the upper surface of the mounting table is 30° or more and less than 90°.
Note that in a state where the quartz glass ingot is placed on the mounting table, the lower end surface of the quartz glass ingot may be partially located above the inclined surface.

Further, the inclination angle is 45° or more and 75° or less, and the ratio of the length Y of one side inside the bottom part of the molding tray to the length T of one side or diameter of the upper surface of the mounting table, Y:T is 8:5 to 8:6, and furthermore, when the length from the outer peripheral end of the inclined surface of the mounting table to the side surface of the molding tray is d3, the ratio of T: d3 is 1. : Desirably 0.12 to 0.28.

Further, a heat forming apparatus according to the present invention, which has been made to solve the above problems, includes the above-mentioned heat-forming jig, a heating furnace that houses the heat-forming jig, and a quartz glass ingot that is housed in the heating furnace. and a heater for heating.

Further, the heat forming method according to the present invention, which has been made to solve the above problems, includes the above-mentioned heat-forming jig, a heating furnace for accommodating the above-mentioned heat-forming jig, and a quartz glass ingot housed in the heating furnace. A quartz glass ingot is placed on the mounting table of the heating molding jig, and the quartz glass ingot is softened by heating with the heater, and the quartz glass ingot is heated by the heater. A quartz glass molded body having a predetermined shape is formed from a quartz glass ingot using a receiving tray.

According to the present invention, a heating molding jig, a heating molding device, and a heating molding method are capable of suppressing the occurrence of bending striae in a quartz glass molded body that is formed by heating and softening a quartz glass ingot in a mold for deformation. can be obtained.

FIG. 1 is a sectional view showing a schematic configuration of a heat molding jig and a heat molding apparatus according to the present invention. FIG. 2 is a plan view of the inside of the thermoforming apparatus of FIG. 1. FIG. 3 is a perspective view of a mounting table provided in the heat molding jig according to the present invention. FIG. 4 is a partially enlarged side view of the heat forming jig shown in FIG. 3 and the quartz glass ingot placed thereon (with d1 in the positive direction). FIG. 5 is a perspective view showing a modification of the mounting table provided in the heat molding jig according to the present invention. FIGS. 6A and 6B are cross-sectional views showing the state of a quartz glass ingot deformed by heating. FIG. 7 is a sectional view showing a modification of the heat molding jig (molding tray) according to the present invention. FIGS. 8A, 8B, and 8C are cross-sectional views showing the state of deformation of a quartz glass ingot in a conventional heat forming jig. FIG. 2 is a partially enlarged cross-sectional view of an end face of a quartz glass molded body.

Hereinafter, embodiments according to the present invention will be described based on FIGS. 1 to 7. Note that FIGS. 1 to 7 schematically represent the shapes of the apparatus and the jig for the purpose of explanation.

FIG. 1 is a diagram showing a schematic configuration of a heat forming apparatus 1, which includes at least a heating furnace 2, a heat forming jig 3, and a heater 4 for heating a quartz glass ingot X. We are prepared.
The heating furnace 2 houses a heater 4 therein, and heats the quartz glass ingot X with the heat generated by the heater 4. The heating molding jig 3 is a jig for forming a quartz glass molded body of a predetermined shape while heating and softening the quartz glass ingot X, as will be described in detail later.

The quartz glass ingot X is manufactured by, for example, subjecting a silica raw material such as silicon tetrachloride to a hydrolysis reaction and depositing glass particles on a target, and the body part X1 is formed in a cylindrical or prismatic shape, and its upper end The portion X2 is formed in a curved shape or a sloped shape whose diameter gradually increases. Further, the lower end surface X3 is formed as a flat surface.

That is, the quartz glass ingot X has a cylindrical or prismatic shape with an upper end having a curved or inclined convex shape, and a lower end having a horizontal surface. As shown in FIG. 1, a mounting table 10 is arranged on the bottom surface P1 of the receiving tray P, and the lower end surface (bottom surface) X3 of the quartz glass ingot X is placed on the upper surface thereof. This lower end surface X3 is precisely leveled horizontally to the extent that the flatness required for a quartz glass molded body can be obtained.

Next, the configuration of the heat molding jig 3 housed in the heat molding apparatus 1 will be explained based on FIGS. 1 to 4. Note that FIG. 2 is a plan view of the inside of the heat molding apparatus 1, and FIG. 3 is a perspective view of the mounting table 10. Moreover, FIG. 4 is a partially enlarged side view of the heat-forming jig and the quartz glass ingot placed thereon.

This hot molding jig 3 includes at least a molding tray P and a mounting table 10 arranged on the bottom of the molding tray P. Here, a case will be described in which the molding tray P and the mounting table 10 are separate bodies, but the mounting table may be integrally formed above the bottom surface of the molding tray.
A first support 5 (5A, 5B) placed on the upper edge of the molding tray P, and a cylindrical second support 6 placed on the first support 5. We are prepared.

The first support 5 supports the second support 6, is placed on the upper edge of the molding tray P, and surrounds the quartz glass ingot X. The first support body 5 includes a pair of first beams 5A arranged with an interval equal to or larger than the diameter of the silica glass ingot It is constructed by assembling a pair of second beams 5B into a cross-shaped structure. Further, the second support body 6 is formed in a cylindrical shape and is placed on top of the first support body 5, and the quartz glass ingot X is stored inside the second support body 6. Ru.

The molding tray P is a mold for molding a quartz glass molded body of a predetermined shape from the quartz glass ingot As shown in FIG. 2, it is formed into a rectangular shape. This molding tray P is basically a mold that defines the shape of the quartz glass molded body after molding, but the mold is formed by the upper surface of the mounting table 10 placed on the bottom surface P1 and the side surface P2. is formed.

Specifically, when the quartz glass ingot X is placed on the mounting table 10 and the quartz glass ingot It is molded by.

As shown in FIG. 3, the mounting table 10 is a flat rectangular plate as a whole, and includes a flat first upper surface 10a, sloped surfaces 10b formed on each of the four sides of the periphery, and a lower end of the sloped surface 10b. It has a flat second upper surface 10c formed at a portion.
Here, as shown in FIG. 3, the circular lower end surface X3 of the quartz glass ingot X is placed in a state in which it is entirely in contact with the first upper surface 10a of the mounting table 10.
The diameter of the quartz glass ingot X is larger than the first upper surface 10a, and the quartz glass ingot X is placed with the outer circumference of the lower end surface X3 partially protruding (floating) above the inclined surface 10b of the mounting table 10. In some cases.

As shown in FIG. 4, the diameter at the bottom of the quartz glass ingot The distance between the outer peripheral surface of the glass ingot X and the outer edge of the first upper surface 10a is d1.
As shown in FIG. 3, the distance d1 between the outer circumferential surface of the silica glass ingot becomes shorter at .
Here, the outer circumferential surface of the quartz glass ingot The distance from the outer edge of 10a is d1.

Further, the diameter of the quartz glass ingot X is larger than the first upper surface 10a, and the quartz glass ingot X is placed with the outer circumference of the lower end surface X3 partially protruding above the inclined surface 10b of the mounting table 10 (floating state). There are cases. The distance between the outer circumferential surface of the silica glass ingot X and the outer edge of the first upper surface 10a at this time is d1 (in the positive direction).

In addition, the distance from the outer peripheral surface of the quartz glass ingot X to the lower end of the inclined surface 10b of the mounting table 10 (radial length parallel to the lower end surface X3 of the quartz glass ingot The length (radial length from the outer circumferential end of the inclined surface 10b to the side surface P2 of the saucer P) is assumed to be d3.
Similarly to d1, d2 is the distance between the outer peripheral surface of the quartz glass ingot X and the lower end of the inclined surface 10b at the center of the outer edge of the first upper surface 10a.
Similarly, d3 is the radial length of the second upper surface 10c on the extension line of the central portion of the outer edge of the first upper surface 10a.

Further, the angle of inclination of the inclined surface 10b with respect to the outward extension of the first upper surface 10a of the mounting table 10 (lower end surface X3 of the quartz glass ingot X) is assumed to be θ. Preferred aspects of these parameters will be described later.

Although FIG. 3 shows an example in which the upper surface 10a of the mounting table 10 has a rectangular shape, the present invention is not particularly limited to this. For example, as shown in FIG. 5, the upper surface 10a may have a circular shape. It may also be shaped. In this case, the diameter length of the first upper surface 10a of the mounting table 10 is the same as the length T of one side of the upper surface 10a of the mounting table 10.
Further, the material of the molding tray P and the mounting table 10 is not particularly limited as long as it is a heat-resistant material that does not easily react with quartz glass. For example, a high-purity carbon material is preferably used.

By the way, if the shape of the inclined surface 10b as shown in FIG. 4 has one or more steps having an apex, there is a possibility that air bubbles may be drawn into the glass deformed at the apex. In the present invention, the shape of the inclined surface 10b is preferably a linear shape as shown in FIG. Alternatively, it may be a gentle curved shape (a curved shape with a large radius of curvature), in which case θ is determined by the angle between the straight line connecting the starting point and the ending point of the curve and the upper surface 10a.

Further, it is preferable that the surface roughness of the inclined surface 10b is smooth enough to allow smooth movement of the heated and softened quartz glass.

Next, the functions of the hot molding jig, hot molding device, and hot molding method according to the present invention will be explained.
First, the quartz glass ingot X is placed in the molding tray P such that the center of the quartz glass ingot Place it on top.

The striae C can be observed by a known method, and the projection method or the Schlieren method is preferably used. Furthermore, as shown in FIG. 9, the bent striae C1 in the present invention refers to striae that have grown in one direction from the center when the end face of the quartz glass molded body is observed (in a direction perpendicular to this) ( It refers to a shape that is rolled up in the vertical direction. In particular, a typical shape is a shape in which the rounded portion is close to 90°.

Subsequently, a pair of first beams 5A are placed on the upper edge of the molding tray P with an interval equal to or larger than the diameter of the quartz glass ingot X. Furthermore, the second beam 5B is arranged perpendicularly to the first beam 5A with an interval equal to or larger than the diameter of the quartz glass ingot X. Then, taking into consideration the height of the quartz glass ingot X, the first beam 5A and the second beam 5B are assembled into a cross-shaped structure to form the first support body 5.

Next, the second support 6 is lowered from above the quartz glass ingot X so that the center of the second support 6 coincides with the center of the quartz glass ingot X, and the quartz glass ingot X is housed therein. . This second support 6 is placed on the first support 5. Then, it is confirmed whether the center of the second support 6 and the center of the quartz glass ingot X are on the same straight line. If they are not on the same straight line, the mounting position of the second support 6 is shifted and the center of the second support 6 and the center of the quartz glass ingot X are aligned.

After placing the quartz glass ingot X on the heating molding jig, the quartz glass ingot X is heated and softened by the heater 4 shown in FIG. By this heating, the diameter of the quartz glass ingot X gradually expands from the bottom, as shown in FIG. . At the same time, the height of the quartz glass ingot X decreases. At this time, the lower end surface X3 of the quartz glass ingot X is deformed along the inclined surface 10b of the mounting table 10. The friction that the lower end surface X3 of X receives is reduced, and the striae, which has changed into a bent shape, flow into d3.
As a result, bending striae that occurs due to bending at the ends of striae can be effectively prevented.

Then, as shown in FIG. 6(b), after the entire quartz glass ingot X advances and is accommodated inside the molding tray P, it is cooled to produce a quartz glass molded body. Then, by horizontally cutting and removing the bottom of the quartz glass molded body, a shape that can be processed as a product is obtained.

Preferred embodiments of the present invention will be described below. First, regarding d1, if d1 exists in the negative direction, that is, if L of the quartz glass ingot There is a distance traveled in contact with the (horizontal plane), which tends to offset the effect of the present invention by that distance.

On the other hand, when d1 exists in the positive direction, that is, as shown in FIG. 4, when L of the quartz glass ingot Since the contact area with 10a (horizontal surface) is reduced, friction is reduced, and the effect of the present invention is less impaired than when d1 is zero or negative.
However, if d1 is large in the positive direction, there is a risk that the quartz glass ingot X may lack stability when placed or in a softened state, and the center of the quartz glass ingot X may be misaligned with the top surface 10a of the mounting table 10. It is not guaranteed that the softening and lowering will proceed evenly at all locations around the entire outer periphery of the quartz glass ingot X, which is also not desirable.

Taking the above into account, if d1 exists in the positive direction, the absolute value of d1 should not exceed 0.25 times L, or be 100 mm or less, to avoid noticeable defects in practical use. It can be said to be preferable because it can prevent the occurrence.
Furthermore, it is preferable that the absolute value of d1 is 0.05 times or more and less than 0.25 times L.
Further, when d1 exists in the negative direction, it is preferable that the absolute value of d1 does not exceed 0.36 times L, for example.

The angle of inclination θ of the inclined surface 10b formed on the mounting table 10 with respect to the outward extension of the first upper surface 10a of the mounting table is preferably 30° or more and less than 90°. If the inclination angle θ is less than 30°, there is a possibility that the above-described effect of reducing striae bending cannot be sufficiently obtained.
On the other hand, when the inclination angle θ is set to 90° (vertical), the softened quartz glass ingot X falls rapidly and becomes excessively deformed. Moreover, air bubbles are generated due to the rapid fall of the quartz glass ingot X, resulting in a problem that the air bubbles are mixed into the quartz glass molded body.
Therefore, the inclination angle θ is more preferably 45° or more and 75° or less.

If the length d3 from the outer circumferential end of the inclined surface of the mounting table to the side surface of the molding tray is too large, the concave shape of the bottom of the quartz glass molded body after molding is completed will be excessive, and the amount to be removed will be If there is too much, the amount of product obtained will decrease, which is not preferable. Preferably, d3 is in the range of 3/50 to 3/16 of the length of one side of the molding tray P.

In addition, the inclination angle θ is 45° or more and 75° or less, and the ratio of the length Y of one side inside the bottom part of the molding tray P to the length T of one side (or diameter) of the upper surface of the inclined surface of the mounting table 10 is Y:T. is preferably 8:5 to 8:6, and more preferably, when T is 1, d3 is a ratio of 0.12 to 0.28.
The inclination angle is 45° or more and 75° or less, so that the lower end surface X3 of the softened quartz glass ingot deforms more smoothly along the inclined surface 10b of the mounting table 10, thereby preventing the occurrence of the bending striae. It can be prevented more effectively.

Furthermore, in order to significantly enhance the effect of preventing the occurrence of bending striae, it is preferable to use a hot forming jig as shown in FIG. That is, in the side surface P2 of the molding tray P, a recess 11 is formed that extends upward from the same height as the first upper surface 10a of the mounting 10 and extends to the outer periphery. Thereby, the bending striae C1 can be suppressed more reliably.
When the extension length of the recess 11 to the outer periphery is d4 and the vertical height is d5, the length dimension of Y is 500 mm to 1500 mm, and the ratio is Y:T:d3:d4:d5=8:5. By setting the ratio to 5:1.25:0.2:0.4, the degree of deformation of the quartz glass ingot X is optimized, so the effects of the present invention are most effectively exhibited, and this is particularly preferable.

As explained above, in the heat-forming jig, heat-forming device, and heat-forming method according to the present invention, the quartz glass ingot Since it is placed on the surface, horizontal friction is reduced during deformation due to heating, making it possible to prevent or reduce the occurrence of bending striae.

The heat molding jig, heat molding device, and heat molding method according to the present invention will be further explained based on Examples.

(Common conditions)
A quartz glass ingot X having a bottom diameter of 400 mm, a height of 900 mm, and a weight of about 200 kg was produced by a known oxyhydrogen flame melting method using silicon tetrachloride, hydrogen gas, and oxygen gas. Next, using a heat forming apparatus as shown in Fig. 1 and a heat forming jig as shown in Fig. 2, the above quartz glass ingot The mixture was allowed to cool to obtain a quartz glass molded body approximately 800 mm square. Observation of flexural striae was performed using a projection method.

(Examples 1 to 3)
As the mounting table, a mounting table 10 as shown in FIG. 4, whose upper surface 10a is rectangular as shown in FIG. 3, was used.
At this time, the length Y of one side of the molding tray P is 800 mm, and the length T of one side of the first upper surface 10a of the mounting table 10 is 500 mm (Example 1), 550 mm (Example 2), and 600 mm ( Example 3), and d3 is the radial length of the second upper surface 10c (the radial length from the lower end of the inclined surface 10b to the side surface P2 of the saucer P), 120 mm (Example 1), 95 mm (Example 3). Example 2), 70 mm (Example 3), and the length ratios of Y, T, and d3 are 8:5:1.2 (Example 1) and 8:5.5, respectively. :0.95 (Example 2), 8:6:0.7 (Example 3). (The ratio of d3 when T is 1 is 0.24 (Example 1), 0.17 (Example 2), and 0.12 (Example 3), respectively.) Here, the inclination angle of the inclined surface is θ was set to 45°.

As shown in FIG. 6, the quartz glass molded body after heating and melting had a concave portion extending downward by 30 mm at the outer periphery, following the shape of the mounting table 10. Next, the concave portion was cut to obtain a square block with a thickness of 120 mm. In any of Examples 1, 2, and 3, bending striae were not observed in the square block, but were observed above the concave portion.

(Example 4)
Example 1 was carried out in the same manner as in Example 1, except that the inclination angle θ of the inclined surface was set to 60° and the value of d3 was accordingly changed to 133 mm.
The quartz glass molded body after heating and melting had a concave portion following the shape of the mounting table 10, as in Example 1. Flexural striae were not observed in the square block, but were observed in the middle of the concave area.

(Example 5)
Example 1 was carried out in the same manner as in Example 1, except that the inclination angle θ of the inclined surface was set to 75° and the value of d3 was accordingly changed to 142 mm.
The quartz glass molded body after heating and melting had a concave portion following the shape of the mounting table 10, as in Example 1. Flexural striae were not confirmed in the square block, but were confirmed in the lower part of the concave part.

(Comparative example 1)
The synthetic silica glass ingot X was placed on a plate whose entire surface was flat as shown in FIG. 8, without using the mounting table 10 as shown in FIG. Other conditions were the same as in Example 1. As a result, the lower part was a flat quartz glass molded body, and bending striae were confirmed on the outer periphery.

(Example 6)
Example 1 was carried out in the same manner as in Example 1, except that the inclination angle θ of the inclined surface was set to 15° and the value of d3 was accordingly changed to 38 mm.
As a result, bending striae were confirmed at the extreme end of the square block, but not in the concave portion.

(Example 7)
The experiment was carried out in the same manner as in Example 1, except that the inclination angle θ of the inclined surface was 90° and the value of d3 was accordingly changed to 150 mm.
As a result, air bubbles were generated at the end of the quartz glass molded body due to the clearance created between the bottom plate of the quartz glass molded body and the mounting table 10. Flexural striae were not observed in the square block, but were observed at the base of the concave portion.
In Experimental Examples 1 and 2, although the manufacturing yield was inferior, by cutting off the extreme end, a square block equivalent to that of the above Example could be obtained.

As described above, in the embodiments of the present invention, bending striae (or air bubbles) did not occur in the portions of the obtained quartz glass molded bodies used as products. From this, it was confirmed that the present invention can more effectively suppress the occurrence of flexural striae, which has been difficult to solve with conventional methods.

1 Heat forming device 2 Heating furnace 3 Heat forming jig 4 Heater 5 First support 6 Second support 10 Mounting table 10a First upper surface 10b Inclined surface 10c Second upper surface C Striae C1 Flexural striae P Receiver for molding X Quartz glass ingot L Diameter of quartz glass ingot X

Claims (5)

a molding tray that has a bottom part and a side part and forms a quartz glass molded body of a predetermined shape from a quartz glass ingot;
a mounting table provided on the bottom surface of the molding tray and on which the quartz glass ingot is placed;
Equipped with
The periphery of the upper surface of the mounting table on which the quartz glass ingot is placed is formed with an inclined surface that slopes downward in the vertical direction, which is the direction in which gravity acts, with reference to the upper surface on which the quartz glass ingot is placed. A heat molding jig characterized by: 2. The hot molding jig according to claim 1, wherein an angle of inclination of the inclined surface formed on the mounting base with respect to an outward extension of the upper surface of the mounting base is 30° or more and less than 90°. The inclination angle is 45° or more and 75° or less,
The ratio of the length Y of one side inside the bottom part of the molding tray to the length T of one side or diameter of the upper surface of the mounting table, Y:T is 8:5 to 8:6,
Further, when the length from the outer peripheral end of the inclined surface of the mounting table to the side surface of the molding tray is d3, the ratio of T: d3 is 1:0.12 to 0.28. The hot molding jig according to claim 2, characterized in that: The heat molding jig according to any one of claims 1 to 3,
a heating furnace that houses the heating molding jig;
a heater that is housed in the heating furnace and heats the quartz glass ingot;
A thermoforming device comprising at least the following. The heat molding jig according to any one of claims 1 to 3,
a heating furnace that houses the heating molding jig;
a heater that is housed in the heating furnace and heats the quartz glass ingot;
Using a heat molding device equipped with at least
A quartz glass ingot is placed on the mounting table of the heating molding jig, the quartz glass ingot is softened by heating with the heater, and a quartz glass molded body of a predetermined shape is formed from the quartz glass ingot using the molding tray. A heat molding method characterized by:

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