Silicon mold for high temperature compression molding and method of making the same

Abstract

The present application relates to a kind of silicon mould device for optical device production in high temperature environment and its preparation method.The silicon mould device used in the present application uses symmetrical structure, the deformation generated when heated is uniform, thereby reducing the eccentric problem generated;In addition, step-shaped silicon mould core is used, fixed by the force applied by electrode pressure plate, the parallelism of the whole is improved, support column supports the base, and the mold pressing of upper and lower molds is realized;Each independent support column can be adjusted in corresponding parallelism, which is beneficial to promote the precision and reliability of optical device preparation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of precision mold pressing forming, and relates to a mold frame device for fixing a silicon mold core and a preparation method thereof, in particular to a silicon mold device for optical device production in a high-temperature environment and a preparation method thereof. BACKGROUND

[0002] Precision mold pressing forming is a precision manufacturing technology for copying the surface morphology of a mold to an optical material substrate at high temperature, and has the characteristics of high precision, high efficiency and low cost, and can easily cope with the manufacturing of large-area optical elements with complex morphology. In recent years, various types of optical glass elements have been widely used in consumer electronics, medical facilities, military weapons and other fields. Single crystal silicon material has excellent mechanical properties and stable chemical properties at high temperature, and has become a common choice for mold materials in high-temperature precision mold pressing forming. The fixing of the silicon mold core requires a special mold frame, and the current selection of mold frame materials is generally the use of mold steel. The silicon mold core and the mold frame are assembled together to form a mold, which is a precision tool with complex shape, and bears the expansion force of the blank, so it has high requirements on structural strength, rigidity, surface hardness, surface roughness and machining precision, and the development level of mold production is one of the important indicators of mechanical manufacturing level.

[0003] However, the traditional silicon mold design has the following problems: (1) the deformation of the mold frame material itself due to thermal expansion is ignored, so the deformation of the mold frame can change the centering position of the mold, ultimately affecting the precision of the product. (2) The expansion deformation of the silicon mold core at high temperature is ignored, which causes the eccentricity of the mold core, ultimately affecting the precision of the product. (3) The design of the size tolerance ignores the parallelism problem during machining, which cannot be adjusted subsequently, ultimately affecting the precision of the product.

[0004] Chinese Patent No. CN206644116U discloses a new silicon carbide mold, which comprises a fixed base and a mold base. The fixed base comprises a bearing bottom plate, a fixed screw hole and a limiting groove. The limiting groove is arranged on the right side of the fixed screw hole, and the limiting groove is fixedly connected with the fixed screw hole on the right side. The bearing bottom plate is fixedly connected with the mold base above. The mold base comprises an upper mold plate, a lower mold plate, a cylinder, a mold groove, a bushing and a through hole. The cylinder is arranged below the upper mold plate, and the through hole is arranged in the cylinder. The cylinder is fixedly connected with the mold groove on the outside. The mold groove is provided with a bushing on the outside, and the bushing is fixedly connected with the lower mold plate below. The lower mold plate is provided with a tablet press above.

[0005] However, the existing silicon carbide mold ignores the expansion deformation of the mold frame and the mold core due to heat, and also has the problem that the parallelism of the connection and fixation of the upper and lower molds cannot be adjusted. SUMMARY

[0006] The present application aims to provide a mold frame device for fixing silicon mold cores and a preparation method of the mold frame device, particularly relates to a silicon mold device for optical device production in a high temperature environment and a preparation method of the silicon mold device; the silicon mold device and the preparation method of the silicon mold device provided by the present application ensure the overall machining precision; the parallelism of the silicon mold device is adjusted, and the adjustability of the overall silicon mold is increased.

[0007] The present application provides a silicon mold for high-temperature mold pressing, characterized in that it comprises an upper mold frame, a silicon mold core, a lower base, an upper base, upper base support columns, a lower mold frame, and an electrode pressing plate, wherein the upper mold frame is oppositely arranged with the lower mold frame, the upper mold frame is fixed on the upper base, the silicon mold core is fixed on the lower base and supported by the lower base; the area of the upper base is larger than that of the upper mold frame, and the upper base is supported by the upper base support columns at the edges of the upper base to stabilize the overall structure of the silicon mold and realize the closing and pressing of the upper and lower molds; the silicon mold core is located at the center of the lower mold frame and is fixed by the electrode pressing plate; larger positioning holes are arranged around the upper surface of the lower mold frame, and detection holes are arranged at the edges of each positioning hole; spring push blocks, pre-pressing blocks, and quartz strips are respectively arranged around the silicon mold core, wherein the spring push blocks are symmetrically arranged outside the silicon mold core; the spring push blocks are connected to the lower mold frame through springs, and the movement of the spring push blocks is changed through the springs, so that the size of the force for fixing the silicon mold core is changed; the quartz strips are arranged below the spring push blocks; when the silicon mold core is fixed, the quartz strips limit the specific position of the silicon mold core.

[0008] In one aspect of the silicon mold, the upper base support columns are four, located at the four corners of the rectangular upper base, and each support column is fixedly combined with the upper base to adjust the parallelism between the upper base and the lower base; the upper base and the lower base are kept parallel; a stepped silicon is used as the silicon mold core, which is fixed by the electrode pressing plate.

[0009] In another aspect of the silicon mold, the positioning holes are four, arranged on the surface of the rectangular or circular lower mold frame; the tolerance between the positioning holes and the outer circle of the lower mold frame is limited within 1 micron; the parallelism between the middle pit of the entire lower mold frame and the lower surface of the lower mold frame, and the parallelism between the upper surface and the lower surface of the lower mold frame are kept within 1 micron, so as to ensure that the dimensional tolerance and geometric tolerance finally reach 1 micron.

[0010] In still another aspect of the silicon mold, the detection holes arranged at the edges of the positioning holes are used to detect the deformation state of the upper mold frame and the lower mold frame after multiple high-temperature heating.

[0011] In another aspect of the silicon mold of the present application, the spring push block is two or four, and the size of the silicon mold core is adjusted by the movement of the spring push block, and the force for fixing the silicon mold core is changed to disassemble or assemble the silicon mold core; the pre-press block is arranged above the spring push block; the pre-press block on the spring push block limits the movement direction of the spring push block, and ensures the stability of the silicon mold core; the quartz bar is a high-precision quartz bar, and the specific position is limited when the silicon mold core is fixed.

[0012] The present application provides a method for preparing a silicon mold for high-temperature molding, comprising: providing a silicon mold device comprising an upper mold frame and a lower mold frame, wherein the upper mold frame and the lower mold frame are respectively fixed with an upper base and a lower base, and are respectively provided with an upper silicon mold core and a lower silicon mold core, and the upper silicon mold core and the lower silicon mold core are oppositely arranged; spring push blocks are arranged at the symmetric positions outside the upper silicon mold core and the lower silicon mold core, respectively, and the spring push blocks are connected with the upper mold frame and the lower mold frame through springs, respectively, and the movement of the spring push blocks is changed through the springs, so that the size of the force for fixing the upper silicon mold core and the lower silicon mold core is changed; placing optical glass raw materials for preparing lenses in the silicon mold device, and closing the silicon mold device, heating from room temperature 20 degrees Celsius to about 700 degrees Celsius, and the whole heating process is about 90 seconds, and the molding of the lenses is completed; cooling the molded lenses.

[0013] In one aspect of the preparation method of the present application, a pre-press block (11) is added below the spring push block (10), and the movement direction of the elastic push block (10) is limited by the pre-press block (11).

[0014] The mold frame device for fixing the silicon mold core provided by the present application adopts a symmetrical structure, and the deformation generated when heated is uniform, thereby reducing the eccentricity problem; in addition, the support column supports the base, and realizes the closing of the upper and lower molds for stamping; each independent support column can be adjusted in parallel. The mold frame device provided by the present application also adopts an elastic push block, a pre-press block and a quartz bar, which can limit the specific position when the silicon mold core is fixed; the detection hole in the mold frame facilitates the detection of the deformation state of the mold frame after multiple high-temperature heating. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some examples of the present application, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.

[0016] Figure 1 It is a structural schematic diagram of the silicon mold device of the present application;

[0017] Figure 2 Figure 1 is a schematic diagram of the structure of a silicon mold core and a lower mold frame in a silicon mold device of the present application;

[0018] Figure 3 Figure 2 is a flow chart of the preparation of a silicon mold device of the present application. DETAILED DESCRIPTION

[0019] The present application will now be described with reference to the attached drawings, of which:

[0020] Figure 1The figure is a schematic diagram of the structure of the silicon mold device. The silicon mold device as a whole comprises an upper mold frame 1, a silicon mold core 2, a lower base 3, an upper base 4, an upper base support column 5, and a lower mold frame 6 and an electrode pressure plate 7. In an embodiment, the upper mold frame 1 and the lower mold frame 6 can be made of S136 mold steel. The silicon mold device as a whole is placed in a temperature environment of about 700 degrees for heating. Due to the fact that the upper mold frame 1 and the lower mold frame 6 are made of mold steel, the deformation of the mold steel under heat is very small and can be ignored. The upper mold frame 1 is arranged opposite to the lower mold frame 6, the upper mold frame 1 is fixed on the upper base 4, the silicon mold core 2 is fixed on the lower base 3 and is supported by the lower base 3; similarly, another silicon film core (not shown in the figure) is also fixed on the upper mold frame 1 opposite to the lower mold frame 6. The silicon mold core 2 can be of various shapes, such as a cube, a cuboid and a stepped shape. In an embodiment, the area of the upper base 4 can be larger than the upper mold frame, and is supported by the upper base support column 5 at the edge of the upper base 4, for stabilizing the entire silicon mold structure and realizing the clamping and imprinting of the upper and lower molds; in an embodiment, the support column can be four, located at the four corners of the rectangular upper base 4; each support column can be used to adjust the parallelism between the upper and lower molds; the connection and fixation of the four support columns can be adjusted for parallelism, increasing the adjustability of the entire silicon mold; the silicon in the form of steps is used as the silicon mold core 2 and is fixed by the electrode pressure plate 7. Due to the difference in material between the upper mold frame 1, the lower mold frame 6 and the silicon mold core 2, when the entire silicon mold device is heated, the materials of the upper mold frame 1 and the lower mold frame 6 will expand and deform under heat; the corresponding symmetric structure arranged at the symmetric position is to solve the problem of expansion and deformation of the upper and lower mold frames under high temperature; when the upper and lower mold frames produce micron-level expansion and deformation under the condition of heating at a high temperature of 700 degrees, the size of the upper and lower mold frames changes in the same direction, reducing the eccentricity problem and effectively ensuring the centration. Therefore, the upper and lower mold frames should be symmetric structures; in an embodiment, a central symmetric structure is adopted; when the two are clamped, they should be the same mirror symmetric structure.

[0021] Figure 2Figure 1 is a schematic diagram of the structure of the silicon mold core and the lower mold frame in the silicon mold device of the present application. The silicon mold core 2 is located at the center of the lower mold frame 6 and is fixed by the electrode pressing plate 7. Larger positioning holes 8 are arranged around the upper surface of the lower mold frame 6. In one embodiment, four positioning holes can be arranged on the rectangular or circular or similar shaped surface of the lower mold frame. Detection holes 12 are arranged at the edges of each positioning hole 8. Spring pushing blocks 10, pre-pressing blocks 11 and quartz strips 9 are arranged around the silicon mold core 2. The spring pushing blocks 10 are arranged at the symmetrical positions outside the silicon mold core. In one embodiment, two spring pushing blocks 10 can be arranged. In another embodiment, four spring pushing blocks 10 can be arranged. The spring pushing blocks 10 are connected to the lower mold frame by springs. The movement of the spring pushing blocks 10 can be changed by the springs, thereby changing the size of the force for fixing the silicon mold core and facilitating the disassembly and assembly of the silicon mold core. High-precision quartz strips 9 are arranged around the silicon mold core 2. The quartz strips 9 are in strip shape and are arranged below the spring pushing blocks 10. When the silicon mold core 2 is fixed, the quartz strips 9 limit the specific position of the silicon mold core 2. Pre-pressing blocks 11 are arranged above the spring pushing blocks 10. In one embodiment, two pre-pressing blocks 11 can be arranged. In another embodiment, four pre-pressing blocks 11 can be arranged. The pre-pressing blocks 11 limit the movement direction of the spring pushing blocks 10. The spring pushing blocks are used to fix the silicon mold core 2, thereby increasing the range of the adjustable size of the silicon mold core, facilitating the change of the size of the force for fixing the silicon mold core and facilitating the disassembly and assembly. The pre-pressing blocks 11 on the spring pushing blocks limit the movement direction of the spring pushing blocks, thereby ensuring the stability of the silicon mold core. The high-precision quartz strips 9 arranged around the silicon mold core limit the specific position of the silicon mold core when it is fixed. In addition, in order to achieve the best effect of the present application, the key dimensions of the mold frame need to be ensured. For example, the tolerance between the positioning hole and the outer circle of the mold frame needs to be limited within 1 micron. The parallelism between the middle recess of the entire lower mold frame and the lower surface of the lower mold frame and the parallelism between the upper surface and the lower surface of the lower mold frame need to be ensured within 1 micron, thereby ensuring that the size tolerance and the shape and position tolerance can reach 1 micron and ensuring the overall machining precision. Detection holes 12 are arranged at the edges of each positioning hole 8, thereby facilitating the detection of the deformation state of the mold frame after multiple high-temperature heating.

[0022] Figure 3A flow chart for preparing the silicon mold device of the present application. In step 301, a silicon mold device is provided, which includes an upper mold frame and a lower mold frame, wherein the upper mold frame and the lower mold frame are respectively fixed to an upper base and a lower base, and are respectively provided with upper and lower silicon mold cores, and the upper and lower silicon mold cores are oppositely arranged; in step 302, spring push blocks are respectively arranged at symmetrical positions outside the upper and lower silicon mold cores, and the spring push blocks are respectively connected to the upper and lower mold frames through springs, and the movement of the spring push blocks is changed through the spring, so that the force for fixing the upper and lower silicon mold cores is changed; in an embodiment, a pre-pressing block can be added below the spring push block, and the pre-pressing block is used to limit the movement direction of the elastic push block; in step 303, optical glass raw materials for preparing lenses are placed in the silicon mold device, and the silicon mold device is closed, and the temperature is increased from room temperature 20 degrees Celsius to 700 degrees Celsius, and the whole heating process is about 90 seconds, and the lens is formed by mold pressing; in step 304, the formed lens is cooled, and whether the product is a qualified product is detected. Under the optical microscope, if there is no defect and no bubble in the product, it means that the product is a qualified product.

[0023] The present application provides a feasible scheme for the design of high-temperature mold pressing forming silicon mold. The use of the symmetrical silicon mold effectively reduces the influence of parallelism error and controls it within 2 microns. The size accuracy and surface accuracy of the product are greatly improved, and the yield can be as high as 85%. The silicon mold has good repeatability and reliability, and the product still has high accuracy after multiple hot stamping. The present application creates favorable conditions for the mass production, high accuracy and high efficiency of optical elements, and promotes the accuracy and reliability of optical device preparation.

[0024] As used herein, "one embodiment", "an embodiment" or "one or more embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0025] The above description is only used to illustrate the technical solutions of the present application, and any person skilled in the art can modify and change the above embodiments without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application should be subject to the scope of claims. The present application has been described above in conjunction with examples. However, other embodiments beyond the above embodiments within the scope of the present application are also feasible. Different features and steps of the present application can be combined in other methods different from the described methods. The scope of the present application is only limited by the appended claims. More generally, all the parameters, dimensions, materials and configurations described herein are actual parameters, dimensions, materials and / or configurations for demonstration purposes, which will depend on specific applications or applications to which the present application is used.

Claims

1. A silicon mold for high temperature compression molding, characterized by The silicon mold comprises an upper mold frame (1), a silicon mold core (2), a lower base (3), an upper base (4), upper base support columns (5), a lower mold frame (6), and an electrode pressing plate (7). The upper mold frame (1) is arranged opposite to the lower mold frame (6), and the upper mold frame (1) is fixed on the upper base (4). The silicon mold core (2) is fixed on the lower base (3) and is supported by the lower base (3). The area of the upper base (4) is larger than that of the upper mold frame (1), and the upper base (4) is supported by the upper base support columns (5) at the edges of the upper base (4) to stabilize the whole silicon mold structure and realize the closing and pressing of the upper and lower molds. The four upper base support columns (5) are arranged at the four corners of the rectangular upper base (4), and each upper base support column (5) is fixedly combined with the upper base (4) to adjust the parallelism between the upper base (4) and the lower base (3) so that the upper base (4) is kept parallel to the lower base (3). The upper mold frame (1) and the lower mold frame (6) are made of S136 mold steel. When the whole silicon mold device is heated, the materials of the upper mold frame (1) and the lower mold frame (6) with symmetrical structures arranged at symmetrical positions will expand and deform in the same direction. The silicon mold core (2) is arranged at the center of the lower mold frame (6) and is fixed by the electrode pressing plate (7). Larger positioning holes (8) are arranged around the upper surface of the lower mold frame (6), and detection holes (12) are arranged at the edges of each positioning hole (8). Spring pushing blocks (10), pre-pressing blocks (11), and quartz strips (9) are arranged around the silicon mold core (2). The spring pushing blocks (10) are arranged at symmetrical positions outside the silicon mold core (2). The spring pushing blocks (10) are connected with the lower mold frame (6) by springs, and the movement of the spring pushing blocks (10) is changed by the springs, so that the force for fixing the silicon mold core is changed. The quartz strips (9) are arranged below the spring pushing blocks (10), and the specific position of the silicon mold core (2) is limited by the quartz strips (9) when the silicon mold core (2) is fixed.

2. The silicon mold of claim 1, wherein the silicon mold core (2) is made of stepped silicon and is fixed by the electrode pressing plate (7).

3. The silicon mold of any one of claims 1-2, wherein the four positioning holes (8) are arranged on the surface of the rectangular or circular lower mold frame (6), and the tolerance between the positioning holes (8) and the outer circle of the lower mold frame (6) is limited within 1 micron. The parallelism between the middle pit of the whole lower mold frame (6) and the lower surface of the lower mold frame (6), and the parallelism between the upper surface and the lower surface of the lower mold frame (6) are both kept within 1 micron, so that the final accuracy of the dimensional tolerance and the geometric tolerance reaches 1 micron.

4. The silicon mold of claim 3, wherein the detection holes (12) arranged at the edges of the positioning holes (8) are used to detect the deformation state of the upper mold frame (1) and the lower mold frame (6) after multiple high-temperature heating.

5. The silicon mold according to any one of claims 1-2, wherein the spring push block (10) is two or four, the size of the silicon mold core (2) is adjustable by the movement of the spring push block (10), the force for fixing the silicon mold core (2) is changed so as to disassemble and assemble the silicon mold core (2); the pre-pressing block (11) is arranged above the spring push block (10) correspondingly; the pre-pressing block (11) on the spring push block (10) limits the movement direction of the spring push block (10) to ensure the stability of the silicon mold core (2); the quartz bar (9) is a high-precision quartz bar, which limits the specific position when the silicon mold core (2) is fixed.

6. A method for preparing a silicon mold for high-temperature mold pressing, comprising: providing a silicon mold device comprising an upper mold frame (1) and a lower mold frame (6), wherein the upper mold frame (1) and the lower mold frame (6) are respectively fixed with an upper base (4) and a lower base (3), and are respectively provided with upper and lower silicon mold cores, the upper and lower silicon mold cores are oppositely arranged; spring push blocks (10) are arranged at the symmetric positions outside the upper and lower silicon mold cores, the spring push blocks (10) are connected with the upper mold frame (1) and the lower mold frame (6) by springs, the movement of the spring push blocks (10) is changed by the springs, thereby changing the size of the force for fixing the upper and lower silicon mold cores; the upper base support columns (5) are four, located at the four corners of the rectangular upper base (4), each upper base support column (5) is fixedly combined with the upper base (4) and is respectively used for adjusting the parallelism between the upper base (4) and the lower base (3); the upper base (4) is kept parallel to the lower base (3); the upper mold frame (1) and the lower mold frame (6) are made of S136 mold steel; when the whole silicon mold device is heated, the materials of the upper mold frame (1) and the lower mold frame (6) with corresponding symmetric structures at the symmetric positions will expand and deform in the same direction; placing the optical glass raw material for preparing lenses in the silicon mold device, and closing the mold of the silicon mold device, heating from room temperature 20 degrees Celsius to about 700 degrees Celsius, the whole heating process is about 90 seconds, and the mold pressing of the lenses is completed; cooling the formed lenses.

7. The method according to claim 6, wherein the pre-pressing block (11) is added below the spring push block (10), and the movement direction of the spring push block (10) is limited by the pre-pressing block (11).

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