A press die for a raw material for large-size plate-like crystal growth, a pressing method, and a method of growing a crystal

Abstract

The present application relates to a kind of for large size plate crystal growth raw material pressing mould, pressing method and the method for growing crystal, pressing mould includes inner mould and outer mould;The inner mould includes lower die and upper die, the lower surface of lower die is raised downward and is concave in upper surface, forming the shaped mould cavity corresponding with the shape of the raised;Outer mould includes base and cushion block, the upper surface of base is concave downward, forming a limiting cavity, limiting cavity is adapted to the raised surface of lower die to accommodate lower die and prevent shaped mould cavity from extending horizontally when pressing;The middle part of the upper surface of upper die is concave downward, forming cushion block limiting sunken platform with the shape of shaped mould cavity, the shape of the cushion block is consistent with cushion block limiting sunken platform;The material of the upper die and lower die is flexible material with ductility, and the material of the base and cushion block is hard alloy.The present application can make the raw material keep the boat shape adapted to crucible throughout the pressing, and greatly reduce the volume of crystal raw material, and the pressing effect is compact.

Description

Technical Field

[0001] This invention belongs to the field of crystal material preparation technology, specifically relating to a pressing mold, pressing method, and crystal growth method for raw materials used in the growth of large-size plate-shaped crystals. Background Technology

[0002] Horizontal directional crystallization is an important method for preparing large-sized plate-shaped crystals. Crystals grown by this method have advantages such as being plate-shaped, easy to process, high crystal utilization, good uniformity after doping, low dislocation density, few defects and scattering particles, no core or side core required when growing garnet crystals, and low cost.

[0003] The crucible used in the horizontal directional crystallization method is a boat-shaped crucible. Currently, the crystal growth process of this method involves directly loading the raw material into the crucible, then placing the crucible into the crystal growth furnace, where the raw material melts and crystal growth occurs directly. Because the raw material is a powder, its form is too loose, and the crucible's capacity is very limited, resulting in very small crystal sizes obtained by directly adding the raw material. If a large amount of raw material is forcibly added to the crucible, the loose material easily spills into the furnace, causing contamination. To grow thicker products and improve product size and production efficiency, the raw material density must be as high as possible; therefore, pre-pressed raw material must be used for furnace loading.

[0004] The prior art CN114131994A discloses a raw material pressing mold for growing crystals by horizontal directional solidification, which can press multiple boat-shaped blocks of raw material at one time, improving the space utilization within the boat-shaped crucible and preventing them from scattering into the furnace. However, this method can only press loose powder into approximately boat-shaped blocks of raw material. In addition to the need to improve the fit with the boat-shaped crucible, the compressed raw material has a low degree of volume compression, and its density does not change much compared to powder. When pressing multiple layers of mold simultaneously, the pressing effect is worse closer to the center, resulting in inconsistent sizes of each pressed raw material that are difficult to control. When demolding, some powder remains adhering to the mold inside the sealed bag. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a pressing mold, pressing method and crystal growth method for raw materials for the growth of large-size plate crystals, so as to avoid the problem of poor pressing effect due to low volume compression in the existing crystal raw material pressing, and to achieve the effect of greatly reducing the volume of crystal raw materials.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A pressing die for raw materials used in the growth of large-size plate-shaped crystals, comprising an inner die and an outer die; The inner mold includes a lower mold and an upper mold. The lower surface of the lower mold protrudes downward and the upper surface is recessed to form a molding cavity corresponding to the protrusion shape. The outer mold includes a base and a pad. The upper surface of the base is recessed downward to form a limiting cavity. The limiting cavity is adapted to the lower surface of the lower mold to accommodate the lower mold and prevent the molding cavity from extending horizontally during pressing. The upper surface of the upper mold is recessed downward to form a pad block limiting recess that matches the shape of the molding cavity. The shape of the pad block is consistent with that of the pad block limiting recess. The upper and lower molds are made of a flexible material with ductility, while the base and pad are made of hard alloy.

[0007] To further improve the above technical solution, the forming cavity is a pentagonal prism, and the cross-sectional size and shape of the forming cavity match the crucible.

[0008] Furthermore, the shape of the bottom wall of the pad limiting platform is consistent with the cross-section of the molding cavity.

[0009] Furthermore, the length and width of the pad are both smaller than the pad limiting platform.

[0010] Furthermore, the lower surface of the upper mold protrudes downward to form a limiting boss, the circumferential sidewall of the limiting boss is adapted to the inner sidewall of the forming cavity, and the lower surface of the limiting boss is parallel to the bottom wall of the forming cavity.

[0011] Furthermore, the edge of the upper surface of the lower mold extends horizontally outward to form a first connecting edge around the top of the lower mold in a circumferential direction; The edge of the upper surface of the upper mold extends horizontally outward to form a second connecting edge around the top of the upper mold, the second connecting edge being adapted to the first connecting edge; Several through-holes are provided at intervals on the first and second connecting edges. The connecting holes on the first and second connecting edges correspond one-to-one and are directly opposite each other. Several screws pass through the several connecting holes to close and fix the upper and lower molds together.

[0012] Furthermore, the upper surface of the base is recessed downward along the circumference of the limiting cavity to form a recessed platform, the shape of which is adapted to the first connecting edge; The depth of the recessed platform is greater than the thickness of the first connecting edge and less than the sum of the thicknesses of the first connecting edge and the second connecting edge.

[0013] This invention also relates to a pressing method for raw materials used in the growth of large-size plate-shaped crystals. This method is based on a pressing die for raw materials used in the growth of large-size plate-shaped crystals as described above, and specifically includes the following steps: S1. Load the uniformly mixed raw material to be pressed into the forming cavity of the lower mold, align the limiting boss of the upper mold with the forming cavity of the lower mold and place it so that the second connecting edge is in contact with the first connecting edge, and fix the second connecting edge to the first connecting edge with several screws to obtain an inner mold containing the raw material to be pressed. S2. Place the inner mold containing the raw material to be pressed into the limiting cavity of the base. When placing it in, make the lower surface of the lower mold into the limiting cavity of the base, and use a wooden mallet to tap the upper mold so that the upper mold is completely embedded in the base; and place the pad block in the pad block limiting recess of the upper mold. S3. Place the assembled pressing mold on the worktable of the hydraulic press, and position the pad directly below the hydraulic press head. The hydraulic press head moves downward and acts on the pad to press the pressing mold vertically. The pressure value gradually increases to 0.02-0.05 MPa, and the pressing time is at least 2 hours. S4. After pressing is completed, remove the fixed upper and lower molds from the base, unscrew all screws, and finally remove the pressed block material from the lower mold.

[0014] Furthermore, in step S1, when filling the lower mold with raw material, the upper surface of the raw material is lower than the upper surface of the lower mold, and the difference in distance between the two is less than the thickness of the limiting boss of the upper mold.

[0015] This invention also relates to a method for growing crystals using a horizontal directional crystallization method. A crucible containing raw materials is placed into a crystal growth furnace. After the raw materials are melted, crystals are grown using a horizontal directional crystallization method. The raw materials are block-shaped materials that are adapted to the shape of the crucible. The block-shaped raw materials are obtained by pressing using the pressing method described above.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a pressing mold for raw materials used in the growth of large-size plate-shaped crystals. An inner mold is used to hold the raw material and is made of a flexible material with ductility. This facilitates demolding and allows for maximum compression of the raw material, reducing its volume. Simultaneously, a matching outer mold is provided outside the inner mold. The outer mold is made of hard alloy to prevent deformation of the raw material in the horizontal direction during pressing, ensuring that the size of the raw material only changes in the vertical direction. This pressing mold allows the raw material to maintain a boat shape that matches the crucible throughout the process, significantly reducing the volume of the crystal raw material and achieving a compact pressing effect.

[0017] 2. The pressing mold and pressing method for raw materials used in the growth of large-size plate-shaped crystals according to the present invention can control the size of the raw materials by changing the size of the limiting cavity in the base and the descent distance of the pad in the vertical direction, so that the specifications of the raw materials are more uniform and meet the standards. Attached Figure Description

[0018] Figure 1This is a schematic diagram of the upper mold in the embodiment; Figure 2 This is a schematic diagram of the lower mold structure in the embodiment; Figure 3 This is a schematic diagram of the base structure in the embodiment; Figure 4 This is a schematic diagram of the pad block structure in the embodiment; Figure 5 This is a cross-sectional view (excluding screws) of a pressing mold for growing raw materials of large-size plate crystals, as shown in the embodiment. Among them, the lower mold 1, the forming cavity 101, the first connecting edge 102, the upper mold 2, the pad block limiting platform 201, the limiting boss 202, the second connecting edge 203, the base 3, the limiting cavity 301, the platform 302, the pad block 4, the connecting hole 5, and the raw material 6. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figures, or the orientation or positional relationship commonly used when the product is in use. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance. In addition, the terms "horizontal," "vertical," etc., do not indicate that the component is required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] Please see Figures 1-5 A specific embodiment of a pressing mold for raw materials used in the growth of large-size plate-shaped crystals includes an inner mold and an outer mold; The inner mold includes a lower mold 1 and an upper mold 2. The lower surface of the lower mold 1 is raised downward and the upper surface is recessed to form a molding cavity 101 corresponding to the raised shape. The outer mold includes a base 3 and a pad 4. The upper surface of the base 3 is recessed downward to form a limiting cavity 301. The limiting cavity 301 is adapted to the lower surface of the lower mold 1 to accommodate the lower mold 1 and prevent the molding cavity 101 from extending horizontally during pressing. The upper surface of the upper mold 2 is recessed downward to form a pad block limiting recess 201 that is adapted to the shape of the molding cavity 101. The shape of the pad block 4 is consistent with the pad block limiting recess 201. The upper mold 2 and lower mold 1 are made of a flexible material with ductility, and the base 3 and pad 4 are made of hard alloy.

[0023] An embodiment of a pressing mold for raw materials used in the growth of large-size plate-shaped crystals uses an inner mold to hold the raw material 6, and is made of a flexible material with ductility. This facilitates demolding and also allows the raw material 6 to be pressed as much as possible to reduce its volume. At the same time, a matching outer mold is set outside the inner mold. The outer mold is made of hard alloy to prevent the raw material 6 from deforming in the horizontal direction during the pressing process, so that the size of the raw material 6 only changes in the vertical direction. This pressing mold can keep the raw material 6 in a boat shape that matches the crucible throughout the process, greatly reduce the volume of the crystal raw material, and achieve a compact pressing effect.

[0024] In practice, both the upper mold 2 and the lower mold 1 are made of rubber, and both the base 3 and the pad 4 are made of stainless steel.

[0025] Please see Figure 2 The molding cavity 101 is a pentagonal prism, and the cross-sectional size and shape of the molding cavity 101 match the crucible.

[0026] This makes the molding cavity 101 a boat shape that fits the crucible; in practice, regarding the molding cavity 101, the included angle of the boat head is 120°, the length of the triangular part of the head is 30mm, the length of the equal diameter part is 230mm, the width is 100mm, and the depth of the molding cavity 101 is 50mm.

[0027] Please see Figure 1 and Figure 2 The bottom wall of the pad limiting platform 201 has a shape that matches the cross-section of the molding cavity 101.

[0028] In this way, the pad 4, which is consistent with the shape of the pad limiting sink 201, can cover the upper surface of the raw material 6 to the greatest extent, so that the raw material 6 is subjected to uniform force in the vertical direction as much as possible, and the warping range around the raw material 6 is minimized.

[0029] Please see Figure 4 and Figure 5 The length and width of the pad 4 are both smaller than the pad limiting platform 201.

[0030] In this way, since the upper mold 2 and the lower mold 1 will be fixed by screws, the screw fixing part will be slightly raised, and the pad 4 must be slightly smaller than the size of the pad limiting countersunk platform 201.

[0031] Please see Figure 1 , Figure 2 and Figure 5The lower surface of the upper mold 2 protrudes downward to form a limiting boss 202. The circumferential sidewall of the limiting boss 202 is adapted to the inner sidewall of the forming cavity 101, and the lower surface of the limiting boss 202 is parallel to the bottom wall of the forming cavity 101.

[0032] Thus, after the material is loaded into the lower mold 1, the setting of the limiting boss 202 serves two purposes: first, it further restricts the upper surface of the raw material 6, making it into a regular boat shape; second, it ensures that the lower surface of the upper mold 2 is always in contact with the forming cavity 101, preventing the upper mold 2 from shifting in the horizontal direction.

[0033] Please see Figure 2 and Figure 5 The edge of the upper surface of the lower mold 1 extends horizontally outward to form a first connecting edge 102 around the top of the lower mold 1. The edge of the upper surface of the upper mold 2 extends horizontally outward to form a second connecting edge 203 around the top of the upper mold 2, the second connecting edge 203 being adapted to the first connecting edge 102. A plurality of vertically penetrating connecting holes 5 are provided at intervals on the first connecting edge 102 and the second connecting edge 203. The connecting holes 5 on the first connecting edge 102 and the second connecting edge 203 correspond one-to-one and are directly opposite each other. A plurality of screws pass through the plurality of connecting holes 5 to close and fix the upper mold 2 and the lower mold 1 together.

[0034] Thus, the arrangement of the first connecting edge 102 and the second connecting edge 203 facilitates the setting of the plurality of connecting holes 5 to close and fix the upper mold 2 and the lower mold 1; it also facilitates subsequent demolding.

[0035] Please see Figure 3 and Figure 5 The upper surface of the base 3 is recessed downward along the circumference of the limiting cavity 301 to form a recessed platform 302, the shape of which is adapted to the first connecting edge 102. The depth of the recessed platform 302 is greater than the thickness of the first connecting edge 102 and less than the sum of the thicknesses of the first connecting edge 102 and the second connecting edge 203.

[0036] In this way, when the entire inner mold and the raw material 6 are pressed, there will only be vertical dimensional changes, and no horizontal deformation.

[0037] Please see Figure 5 The present invention also provides a pressing method for raw materials used in the growth of large-size plate-shaped crystals. This method is performed using a pressing die for raw materials used in the growth of large-size plate-shaped crystals as described above, and specifically includes the following steps: S1. The uniformly mixed raw material 6 to be pressed is loaded into the molding cavity 101 of the lower mold 1. The limiting boss 202 of the upper mold 2 is aligned with the molding cavity 101 of the lower mold 1 and the second connecting edge 203 is attached to the first connecting edge 102. The second connecting edge 203 and the first connecting edge 102 are fixedly connected by several screws to obtain the inner mold containing the raw material 6. S2. Place the inner mold containing the raw material 6 into the limiting cavity 301 of the base 3. When placing it in, make the lower surface of the lower mold 1 into the limiting cavity 301 of the base 3, and use a wooden mallet to knock the upper mold 2 so that the upper mold 2 is completely embedded in the base 3; and place the pad 4 in the pad limiting sink 201 of the upper mold 2. S3. Place the assembled pressing mold on the worktable of the hydraulic press, and position the pad 4 directly below the hydraulic press head. The hydraulic press head moves downward and acts on the pad 4 to press the pressing mold vertically. The pressure value gradually increases to 0.02-0.05 MPa, and the pressing time is at least 2 hours. S4. After pressing is completed, remove the fixed upper mold 2 and lower mold 1 from the base 3, unscrew the screws, and finally remove the pressed block material 6 from the lower mold 1.

[0038] In step S1, when the raw material 6 is filled into the lower mold 1, the upper surface of the raw material 6 is lower than the upper surface of the lower mold 1, and the difference in distance between the two is less than the thickness of the limiting boss 202 of the upper mold 2.

[0039] In this way, the limiting boss 202 is given enough space to accommodate the material 6, and the limiting boss 202 can also perform preliminary pressing and shaping.

[0040] In this embodiment, in addition to the aforementioned dimensions of the molding cavity 101, the relevant dimensions of other boat-shaped parts are also described here: The upper mold 2 has a pad block limiting recess 201 with a depth of 3mm. Its boat-shaped head has an included angle of 120°, the length of the triangular part of the head is 27mm, the length of the equal diameter part is 227mm, and the width is 94mm. Pad 4: Thickness is 50mm, its boat-shaped head has an included angle of 120°, the length of the triangular part of the head is 24mm, the length of the equal diameter part is 224mm, and the width is 88mm; The limiting cavity 301 of the base 3 has a depth of 53mm, an included angle of 120° for its boat-shaped head, a length of 33mm for the triangular part of the head, a length of 233mm for the equal diameter part, and a width of 106mm.

[0041] During loading, the thickness of raw material 6 is 48mm, meaning the upper surface of raw material 6 is 2mm lower than the upper surface of the lower mold 1. When inserting the inner mold into the outer mold, the screw-fixed portion between the upper mold 2 and the lower mold 1 will slightly warp. If the entire inner mold cannot be fully embedded in the base 3, the screw-fixed portion can be pulled outwards until the inner mold is fully embedded in the limiting cavity 301. In short, when inserting the inner mold into the limiting cavity 301, it is essential to ensure that the lower surface periphery of the lower mold 1 is completely fitted with the limiting cavity 301, and that the entire inner mold is wrinkle-free. During pressing, the hydraulic press pressure is 0.03Mpa and maintained for two hours. After pressing, the thickness of raw material 6 is 28mm, and the volume is reduced to 60% of the original volume.

[0042] If the boat-shaped head of the inner mold arches when it is placed into the limiting cavity of the base 3, and the upper mold 2 is struck with a wooden mallet, the inner mold still cannot be embedded in the base. Take out the entire inner mold and squeeze its perimeter by hand to make the raw material 6 of the inner mold gather upwards. Put the squeezed inner mold back into the base. The inner mold does not arch. Use a wooden mallet to strike the upper mold 2 so that the lower surface periphery of the lower mold 1 is completely fitted with the limiting cavity 301 and the entire inner mold is wrinkle-free.

[0043] The present invention provides a pressing mold and pressing method for raw materials used in the growth of large-size plate-shaped crystals. The size of the raw material 6 can be controlled by changing the size of the limiting cavity 301 inside the base 3 and the descent distance of the pad 4 in the vertical direction, so that the specifications of the raw material are more uniform and conform to the standard.

[0044] The present invention also provides a method for growing crystals by horizontal directional crystallization, wherein a crucible containing raw materials is placed into a crystal growth furnace, and after the raw materials are melted, crystallization is performed by horizontal directional crystallization. The raw materials are block-shaped raw materials that are adapted to the shape of the crucible, and the block-shaped raw materials are pressed by the above-mentioned pressing method.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A pressing die for raw materials used in the growth of large-size plate-shaped crystals, characterized in that: Including inner mold and outer mold; The inner mold includes a lower mold and an upper mold. The lower surface of the lower mold protrudes downward and the upper surface is recessed to form a molding cavity corresponding to the protrusion shape. The outer mold includes a base and a pad. The upper surface of the base is recessed downward to form a limiting cavity. The limiting cavity is adapted to the lower surface of the lower mold to accommodate the lower mold and prevent the molding cavity from extending horizontally during pressing. The upper surface of the upper mold is recessed downward to form a pad block limiting recess that matches the shape of the molding cavity. The shape of the pad block is consistent with that of the pad block limiting recess. The upper and lower molds are made of a flexible material with ductility, and the base and pad are made of hard alloy. The shape of the bottom wall of the pad limiting countersunk platform is consistent with the cross-section of the molding cavity; The length and width of the pad are both smaller than the pad limiting sink.

2. The pressing die for raw materials used in the growth of large-size plate-shaped crystals according to claim 1, characterized in that: The molding cavity is a pentagonal prism, and the cross-sectional size and shape of the molding cavity match the crucible.

3. The pressing die for raw materials used in the growth of large-size plate-shaped crystals according to claim 1, characterized in that: The lower surface of the upper mold protrudes downward to form a limiting boss. The circumferential sidewall of the limiting boss is adapted to the inner sidewall of the forming cavity, and the lower surface of the limiting boss is parallel to the bottom wall of the forming cavity.

4. The pressing die for raw materials used in the growth of large-size plate-shaped crystals according to claim 3, characterized in that: The edge of the upper surface of the lower mold extends horizontally outward to form a first connecting edge around the top of the lower mold. The edge of the upper surface of the upper mold extends horizontally outward to form a second connecting edge around the top of the upper mold, the second connecting edge being adapted to the first connecting edge; Several through-holes are provided at intervals on the first and second connecting edges. The connecting holes on the first and second connecting edges correspond one-to-one and are directly opposite each other. Several screws pass through the several connecting holes to close and fix the upper and lower molds together.

5. The pressing die for raw materials used in the growth of large-size plate-shaped crystals according to claim 4, characterized in that: The upper surface of the base is recessed downward along the circumference of the limiting cavity to form a recessed platform, the shape of which is adapted to the first connecting edge. The depth of the recessed platform is greater than the thickness of the first connecting edge and less than the sum of the thicknesses of the first connecting edge and the second connecting edge.

6. A method for pressing raw materials for the growth of large-size plate-shaped crystals, characterized in that: This method is based on the pressing mold for raw materials used in the growth of large-size plate-shaped crystals as described in claim 4, and specifically includes the following steps: S1. Load the uniformly mixed raw material to be pressed into the forming cavity of the lower mold, align the limiting boss of the upper mold with the forming cavity of the lower mold and place it so that the second connecting edge is in contact with the first connecting edge, and fix the second connecting edge to the first connecting edge with several screws to obtain an inner mold containing the raw material to be pressed. S2. Place the inner mold containing the raw material to be pressed into the limiting cavity of the base. When placing it in, make the lower surface of the lower mold into the limiting cavity of the base, and use a wooden mallet to tap the upper mold so that the upper mold is completely embedded in the base; and place the pad block in the pad block limiting recess of the upper mold. S3. Place the assembled pressing mold on the worktable of the hydraulic press, and position the pad directly below the hydraulic press head. The hydraulic press head moves downward and acts on the pad to press the pressing mold vertically. The pressure value gradually increases to 0.02-0.05 MPa, and the pressing time is at least 2 hours. S4. After pressing is completed, remove the fixed upper and lower molds from the base, unscrew all screws, and finally remove the pressed block material from the lower mold.

7. The pressing method for raw materials used in the growth of large-size plate-shaped crystals according to claim 6, characterized in that: In step S1, when filling the lower mold with raw material, the upper surface of the raw material is lower than the upper surface of the lower mold, and the difference in distance between the two is less than the thickness of the limiting boss of the upper mold.

8. A method for growing crystals using a horizontally oriented crystallization method, comprising placing a crucible containing raw materials into a crystal growth furnace, melting the raw materials, and then growing the crystals using a horizontally oriented crystallization method, characterized in that: The raw material is a block-shaped raw material adapted to the shape of the crucible, and the block-shaped raw material is pressed by the pressing method described in claim 6.

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