A resin triangular prism optical element manufacturing mold and a manufacturing method

Abstract

The application discloses a preparation mold and a preparation method of a resin triangular prism optical element. The mold comprises a two-color triangular prism injection mold or a single-color triangular prism injection mold, which is composed of a fixed mold and a movable mold. The fixed mold of the two-color triangular prism injection mold is divided into a first punching station and a second punching station, the movable mold is divided into a first mold and a second mold, and a station cavity with different shapes is formed between the movable mold plate and the corresponding fixed mold plate. The movable mold plate and the fixed mold plate of the single-color triangular prism injection mold are combined to form a product cavity. The extinction treatment area in the cavity is a cavity skin / ground area. The resin triangular prism is prepared by using the injection molding process. The triangular prism can be prepared by only one process, the steps are simple, the mold cooperation preparation process can greatly simplify the molding process, the prepared resin triangular prism optical element has similar performance to a glass triangular prism optical element, various optical structures, such as various optical structures of planes, spherical surfaces, aspherical surfaces and free curved surfaces, can be prepared on each optical surface of the triangular prism, and the resin triangular prism optical element is suitable for application in the field of precision optics.

Description

Technical Field

[0001] This invention relates to precision optical prisms, specifically to a mold for fabricating resin prism optical elements, and also to a method for fabricating resin prism optical elements. Background Technology

[0002] A prism typically has a main structure with three rectangular surfaces and two triangular surfaces. The two triangular surfaces of the main structure and the area around the light-entry surface generally need to undergo a certain degree of extinction treatment to form an extinction zone. This is used to prevent stray light from entering the prism from positions other than the entrance part and interfering with the imaging effect.

[0003] The applications of prism optical elements are becoming increasingly widespread, with growing demand in fields such as vision correction, photography, and optical instrument testing. Traditionally, prisms are primarily made of glass, especially in precision optical applications, such as periscope cameras in mobile phones.

[0004] Glass prism optical elements possess high thermal stability and high light transmittance, and the industry has conducted extensive research on them. Their manufacturing process mainly includes material roughing, multiple grinding, rough polishing, and fine polishing, as well as blackening. While multi-step processing ensures product precision, the entire process is extremely cumbersome, resulting in a very low first-pass yield. As optical lenses demand increasingly higher performance and smaller dimensions, correspondingly higher requirements are being placed on prisms. For example, complex structures such as aspherical, freeform, or spherical surfaces are being incorporated into the light-incoming and light-outgoing surfaces of glass prisms. This further complicates the manufacturing process, making it even more complex, or even impossible, to meet the demands of large-scale mass production. Furthermore, the heavy weight of glass and the high cost of optical glass limit their further adoption, especially in the consumer electronics sector.

[0005] Compared to glass, resin is lighter and cheaper, and is gradually gaining attention in prism applications. However, current prism manufacturing using this material suffers from low precision and cumbersome processes, hindering its application in precision optics. Using conventional injection molding technology has the following drawbacks:

[0006] Disadvantage 1: Because the thickness of the prism is uneven, with the thickest part in the central area and the thinnest part at the edge, the overall thickness is too large and uneven. During conventional injection molding, uneven shrinkage is likely to occur, resulting in poor surface precision of the product.

[0007] Disadvantage 2: The injection-molded prisms require a second process: edge blackening treatment, which increases both labor costs and the loss of defective parts during production. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a mold and a method for preparing resin triangular prism optical elements. The mold, combined with the preparation process, can greatly simplify the molding process. The prepared resin triangular prism optical elements have similar performance to glass triangular prism optical elements and are suitable for application in the field of precision optics.

[0009] To solve the above-mentioned technical problems, the first technical solution adopted by the present invention is: a mold for preparing resin prism optical elements, which is a two-color prism injection mold, including a fixed mold and a moving mold. The fixed mold is divided into a pre-forming station and a post-forming station. Each station has a hot runner plate on the lower end face of the fixed mold base plate, and a template is set on the lower end face of each hot runner plate. The pre-forming station is used to form the main structure of the prism, and the post-forming station is used to form the matte area. The moving mold is divided into a first mold and a second mold. The first mold and the second mold have an ejection mechanism on the moving mold base plate, a compression mechanism on each ejection mechanism, and a moving template on each compression mechanism. The moving template and its corresponding fixed template form station cavities of different shapes. One end of each station cavity is connected to a corresponding station hot nozzle, and each station hot nozzle is connected to a corresponding mold gate sleeve on the fixed mold base plate.

[0010] The first-stage mold of the fixed mold and the moving mold, after being closed together, form a first-stage mold cavity for injecting transparent material, and the second-stage mold of the fixed mold and the moving mold, after being closed together, form a second-stage mold cavity for injecting black material.

[0011] The compression mechanism is a compression plate, and a compression spring is provided between the compression plate and the corresponding moving template. A compression gap of about 2 to 4 mm is left between the compression plate and the moving template.

[0012] The compression mechanism consists of a compression ejector rod and a regular ejector rod on the ejector mechanism, with a compression mold core at the other end of the compression ejector rod.

[0013] The first and second molds of the moving mold have the same shape, while the shapes of the first and last machining stations of the fixed mold are different.

[0014] A 100mm heat insulation gap is provided between the first and last machining stations of the fixed mold.

[0015] The mold is equipped with a central rotating shaft, and the first and second moving molds are centrally symmetrical with respect to the rotating shaft.

[0016] The present invention provides a method for fabricating a prism using a mold for fabricating the above-mentioned resin prism optical element, comprising the following steps:

[0017] (1). The moving template of mold No. 1 is in the first-stage molded position, and together with the fixed template of the first-stage molded position, they form the first-stage molded cavity. The moving template of mold No. 2 is in the second-stage molded position, and together with the fixed template of the second-stage molded position, they form the second-stage molded cavity. The barrel of the first-stage molded position is made of transparent material, and the barrel of the second-stage molded position is made of black material.

[0018] (2). Adjust the clamping force of the two-color injection molding machine with clamping compression function. When manually clamping the mold with this clamping force, the mold should be able to be closed to the bottom and the compression gap should be 0.

[0019] (3) Set the clamping force of the injection molding machine to 1 / 3 of the normal clamping force. When the fully automatic operation starts, a gap of 0.1 to 0.2 mm will be left between the compression mechanism and the moving platen. The filling resin material is injected into the corresponding cavity through the corresponding mold gate sleeve and the station hot nozzle.

[0020] (4). When the cavity is filled to more than 99% and the pressure is switched, the mold clamping part of the injection molding machine starts to switch to the first stage of compression mode: expansion. At first, a smaller compression force is used. At this time, as the cavity is gradually filled, the pressure inside the mold gradually increases, exceeds the clamping force, and transmits the pressure to the compression mechanism through the compression mold core, driving the compression mechanism to move backward. The compression gap between the compression mechanism and the moving platen will gradually expand to 0.2~0.3mm.

[0021] (5). Entering the second stage of compression mode: compression, the clamping part of the injection molding machine gradually increases the clamping force, gradually exceeds the mold cavity pressure, and then drives the compression mechanism forward, the compression gap narrows, the compression mold core compresses the product evenly and thins it, and finally until the compression gap is narrowed to close to 0.

[0022] (6). After cooling for a period of time, open the mold again, and then rotate the moving mold side 180°. The moving platen of the first mold rotates to the rear working position. The product that has been punched out in the first mold and the fixed platen of the rear working position form the rear working position cavity. The moving platen of the second mold rotates to the first working position and forms the first working position cavity with the fixed platen of the first working position.

[0023] (7). The black material is injected at the next work station, while the transparent material is injected at the first work station.

[0024] (8). After cooling, the mold is opened, and the ejector mechanism at the rear station moves forward, driving the ejector pin to eject the product.

[0025] (9) The moving mold rotates 180° again to start the next cycle.

[0026] The second technical solution adopted in this invention is: a mold for preparing a resin prism optical element, which is a monochrome prism injection mold, including a fixed mold and a moving mold. The fixed mold includes a fixed mold base plate, a hot runner plate, and a fixed template. The moving mold includes a moving mold base plate, an ejection mechanism, a compression plate, and a moving template. The fixed mold base plate is located above the hot runner plate, and the hot runner plate is provided with a hot nozzle and a valve pin. The fixed template is located below the hot runner plate, and the valve pin and the hot nozzle penetrate the hot runner plate and the fixed template. The moving template is located above the compression plate. The moving template and the fixed template are combined to form a product cavity. The area in the cavity that needs to be matte is the cavity texture / frosted area. The compression plate is located below the moving template, and the compression plate is provided with a compression spring. Below the compression plate is the ejection mechanism, and below the ejection mechanism is the moving mold base plate.

[0027] This invention utilizes a method for preparing a resin prism optical element mold, as described above. A textured / frosted finish is applied to the mold corresponding to the area of ​​the product requiring matte treatment. After the mold is installed in the clamping section of an injection molding machine, it is heated to meet the required drying temperature and time for the resin material. The cycle then begins, with the clamping force of the injection molding machine set to 1 / 3 of the normal clamping force for the product. After mold closing, the injection section of the injection molding machine injects molten resin into the mold. Once the resin fills 99% of the cavity, the injection section switches to holding pressure. Simultaneously with or 1-2 seconds later, the clamping section gradually increases the pressure until the required normal clamping force for the product is reached, compressing the product by 0.1-0.2 mm. Under sufficient holding and compression pressure, the resin effectively replicates the shape of the mold surface, including the light-transmitting area and the textured / frosted area. After cooling, the solidified product possesses the shape designed by the mold, including the light-transmitting area and the required matte / frosted area.

[0028] The mold and method for preparing a resin prism optical element designed using the above-mentioned technical solution have the following beneficial technical effects:

[0029] (1). This invention prepares precision prism optical elements by injection molding. The resin material used is optical resin with stable physical and chemical properties such as polycarbonate (PC) or cyclic olefin copolymer (COC). These materials have good physical and chemical stability and can maintain very good stability during long-term use of the product. Moreover, compared with glass materials, they are cheaper and lighter.

[0030] (2) This invention replaces the traditional glass roughing, grinding, rough polishing, fine polishing, and blackening processes with a simple and efficient injection molding method. The production cycle only takes tens of seconds, and more than a dozen or even more cavities can be made on the injection mold, ensuring that multiple cavities are produced from a single mold. Traditional glass prism manufacturing requires a production cycle of more than 48 hours. At the same time, the traditional cumbersome process of glass prism manufacturing results in a very low yield. This invention only requires one step to manufacture prisms, so the process yield is very high, which improves the efficiency of prism manufacturing and is very suitable for large-scale, low-cost mass production.

[0031] (3). This invention can efficiently produce prisms with various optical properties by processing complex optical structures, such as spherical, aspherical and freeform surfaces, on the surface of the injection mold through a simple injection molding process. This enables the production of complex glass prism structures that cannot be made by traditional cold processing, thereby simplifying the size of optical products and enabling more optical functions of the products.

[0032] (4). Although some people in the industry have begun to study the injection molding method for manufacturing prisms, the product precision is completely unable to meet the needs of precision optical applications. This invention uses compression injection molding molds and compression injection molding process, which can greatly improve the surface accuracy of prism products while ensuring high molding efficiency. The surface accuracy can be lower than 100nm, reaching the same level as glass prisms;

[0033] (5). By designing special injection molds and cooperating with corresponding injection molding processes, this invention ensures that the thinner and thicker areas of the resin material are always subjected to balanced holding pressure during the cooling and shrinkage process, ensuring consistent deformation in different areas, thereby controlling the surface accuracy of the product to be less than 100nm, achieving the same level as glass components. Attached Figure Description

[0034] Figure 1 A schematic diagram illustrating the structure of the two-color triangular prism injection mold for mold closing and compression according to the present invention;

[0035] Figure 2 A schematic diagram illustrating a planar triangular prism according to the present invention;

[0036] Figure 3 A schematic diagram illustrating the aspherical or spherical prism of the present invention;

[0037] Figure 4 This diagram illustrates another planar triangular prism according to the present invention.

[0038] Figure 5 A schematic diagram illustrating the structure of the two-color triangular prism injection mold for ejection compression according to the present invention;

[0039] Figure 6This is a schematic diagram showing the structure of the monochrome injection mold of the present invention;

[0040] Figure 7 A schematic diagram of a prism showing the texturing process of the present invention.

[0041] In the diagram: 10 - Fixed mold base plate; 11 - First mold sprue bushing; 12 - Second mold sprue bushing; 20 - First station hot runner plate; 21 - First station hot nozzle; 22 - First station needle valve inlet; 23 - Second station hot runner plate; 24 - Second station hot nozzle; 25 - Second station needle valve inlet; 30 - First station fixed mold plate; 31 - First station cavity (grid line filling area); 32 - Second station fixed mold plate; 33 - Second station cavity (slanted line filling area); 40 - Mold #1 moving mold plate; 41 - Mold #2 moving mold plate; 50 - Mold #1 compression plate; 51 - Mold #1 compression spring; 52 - Mold #2 compression plate; 53 - Mold #2 compression spring; 54 - Mold #1 support plate; 55 - Mold #2 support plate; 60 - Mold #1... Ejection mechanism, 61-Ejection mechanism of mold No. 2, 62-Ejection compression core of mold No. 1, 63-Compression ejector rod of mold No. 1, 64-Ordinary ejector rod of mold No. 1, 65-Compression gap reserved for ordinary ejector rod of mold No. 1, 66-Compression core of mold No. 2, 67-Compression ejector rod of mold No. 2, 68-Ordinary ejector rod of mold No. 2, 69-Compression gap reserved for ordinary ejector rod of mold No. 2, 70-Moving mold base plate, 80-Insulation gap, 90-Central rotation shaft, 201-Hot runner plate, 211-Hot runner manifold plate, 221-Valve needle, 241-Hot nozzle, 301-Fixed mold plate, 311-Cavity texture / frosted area, 401-Moving mold plate, 501-Compression plate, 511-Compression spring, 521-Compression gap, 601-Ejection mechanism. Detailed Implementation

[0042] The following description, in conjunction with the accompanying drawings, details the preparation mold and preparation method of a resin prism optical element according to the present invention.

[0043] This invention uses transparent optical resin as the main structure of a prism. The resin material is melted and injected into a molding die, then cooled and removed to produce a precision optical prism. The transparent resin material used for this main body includes chemically stable optical resins such as polycarbonate (PC) or cyclic olefin copolymers (COC), but is not limited to these materials. The refractive index of these resin materials can range from 1.48 to 1.71. It is understood that although the optical refractive index of resin materials is lower than that of glass materials, the refractive index of the aforementioned optical resins is sufficient for prisms used in reflective, total internal reflection, and refractive light paths. This invention, through the design of a special injection mold and the corresponding injection molding process, ensures that the thinner and thicker areas of the resin material are always subjected to balanced holding pressure during the cooling and shrinkage process, ensuring consistent deformation in different areas, thereby controlling the surface accuracy of the product to less than 100 nm, achieving the same level as glass components.

[0044] This invention discloses a mold and method for manufacturing resin prism optical elements. Example 1 illustrates this method. This example uses a mold with mold-closing compression function, combined with an injection molding machine also equipped with mold-closing compression function, to achieve the desired result through a mold-closing compression process. (See also...) Figure 1 It includes a fixed mold and a moving mold. The fixed mold is further divided into a pre-machined station and a post-machined station. The moving mold is divided into mold number one and mold number two, for a total of four parts. Mold number one and mold number two of the moving mold have the same shape, while the pre-machined station and the post-machined station of the fixed mold have different shapes.

[0045] The pre-forming station of the fixed mold includes a fixed mold base plate 10, a pre-forming station hot runner plate 20, a pre-forming station hot nozzle 21, a pre-forming station needle valve inlet 22, and a pre-forming station fixed platen 30. The pre-forming station hot runner plate 20 is disposed on the lower end face of the fixed mold base plate 10, and the pre-forming station fixed platen 30 is connected to the lower end face of the pre-forming station hot runner plate 20. The post-forming station of the fixed mold includes a fixed mold base plate 10, a post-forming station hot runner plate 23, a post-forming station hot nozzle 24, a post-forming station needle valve inlet 25, and a post-forming station fixed platen 32. The post-forming station hot runner plate 23 is disposed on the lower end face of the fixed mold base plate 10, and the post-forming station fixed platen 32 is connected to the lower end face of the post-forming station hot runner plate 23. In this invention, the pre-forming and post-forming stations share a single fixed mold base plate 10.

[0046] The first moving mold includes a first moving mold platen 40, a first mold compression plate 50, a first mold compression spring 51, a first mold ejection mechanism 60, and a moving mold base plate 70. The first mold ejection mechanism 60 is mounted on the moving mold base plate 70, the first mold compression plate 50 is mounted on the first mold ejection mechanism 60, and the first mold moving platen 40 is mounted on the first mold compression plate 50. A first mold compression gap 54 is left between the first mold compression plate 50 and the first mold moving platen 40. The second moving mold includes a second moving mold platen 41, a second mold compression plate 52, a second mold compression spring 53, a second mold ejection mechanism 61, and a moving mold base plate 70. The second mold ejection mechanism 61 is mounted on the moving mold base plate 70. A second mold compression plate 52 is mounted on the second mold ejection mechanism 61, and a second mold moving template 41 is mounted on the second mold compression plate 52. A second mold compression gap 55 is left between the second mold compression plate 52 and the second mold moving template 41. In this invention, the first mold and the second mold share a single moving mold base plate 70.

[0047] The present invention can form a cavity 31 (a transparent area of ​​a prism) by the first mold-forming station of the fixed mold and the moving mold after they are closed. The cavity 33 (a black area of ​​a prism) can be formed by the second mold-forming station of the fixed mold and the moving mold after they are closed.

[0048] One end of the pre-drilling cavity 31 is connected to the pre-drilling hot nozzle 21 via the pre-drilling needle valve inlet 22. The pre-drilling hot nozzle 21 is connected to the pre-drilling mold sprue sleeve 11 on the fixed mold base plate 10. The pre-drilling hot nozzle 21 is located inside the cavity of the pre-drilling hot runner plate 20. One end of the post-drilling cavity 33 is connected to the post-drilling hot nozzle 24 via the post-drilling needle valve inlet 25. The post-drilling hot nozzle 24 is connected to the post-drilling mold sprue sleeve 12 on the fixed mold base plate 10. The post-drilling hot nozzle 24 is located inside the cavity of the post-drilling hot runner plate 23.

[0049] A compression spring 51 for the first mold is connected between the compression plate 50 of the first mold and the corresponding moving template 40 of the first mold, and a compression spring 53 for the second mold is connected between the compression plate 52 of the second mold and the corresponding moving template 41 of the second mold.

[0050] In this invention, a 100mm heat insulation gap 80 is provided between the first and last machining stations of the fixed mold. The mold has a central rotation axis 90, and the first and second moving molds are centrally symmetrical with respect to the central rotation axis 90.

[0051] This mold clamping compression mold requires a mold clamping compression process and must be used with an injection molding machine that has a mold clamping compression function. The specific implementation method is as follows:

[0052] 1. In the initial state, the moving mold plate of mold No. 1 is in the first-mold-ejection position, forming the first-mold-ejection cavity with the fixed mold plate of the first-mold-ejection position. The moving mold plate of mold No. 2 is in the second-mold-ejection position, forming the second-mold-ejection cavity with the fixed mold plate of the second-mold-ejection position. The barrel of the first-mold-ejection position is made of transparent material, and the barrel of the second-mold-ejection position is made of black material.

[0053] 2. Adjust the appropriate clamping force according to product requirements. When manually closing the mold with this clamping force, the mold should be able to close completely, and the compression gap should be 0.

[0054] 3. Set the clamping force for standby compression to about 1 / 3 of the normal clamping force. When the fully automatic system starts and the mold closes, the clamping part of the injection molding machine will standby when it reaches about 1 / 3 of the normal clamping force. At this time, a compression gap (54, 55) of 0.1 to 0.2 mm will be left between the compression plate and the moving platen. During the injection filling process, this clamping force is sufficient to ensure that no flash overflows from the parting surface.

[0055] 4. When the cavity is filled to more than 99%, and the holding pressure is switched, the injection molding machine's clamping part starts to switch to the first stage of compression mode: expansion. At first, a smaller compression force is used. At this time, as the cavity is gradually filled, the pressure inside the mold gradually increases, exceeding the clamping force, and the pressure is transmitted to the compression plate through the compression mold core, driving the compression plate to move backward. In this way, the compression gap between the compression plate and the moving platen will gradually expand to about 0.2 to 0.3 mm.

[0056] 5. Entering the second stage of compression mode: compression. The clamping part of the injection molding machine will gradually increase the clamping force, gradually exceeding the mold cavity pressure, and then drive the compression plate forward, the compression gap will shrink, and the compression mold core will evenly compress the product and make it thinner, until the compression gap shrinks to close to 0;

[0057] 6. After cooling for a period of time, open the mold again, then rotate the moving mold side 180°, and rotate the moving platen of the first mold to the rear machining position. The products that have been machined out in the first mold and the rear fixed mold form the rear machining position cavity. The moving platen of the second mold rotates to the first machining position and forms the first machining position cavity with the first machining position fixed platen.

[0058] 7. The black material is injected at the rear work station, while the transparent material is injected at the front work station at the same time;

[0059] 8. After cooling, the mold opens, the ejector mechanism at the rear station moves forward, driving the ejector pin forward to eject the product;

[0060] 9. The moving mold rotates 180° again to start the next cycle.

[0061] This invention Figure 2 , Figure 3 , Figure 4 In the image above, the product form (transparent material, main structure) is shown after the cavity is first injection molded. The area marked by the diagonal line at the bottom of the image is shown after the cavity is second injection molded (black material, matte area). The diagonal line plus the transparent area is the final injection molded product form.

[0062] The resin prism produced in Example 1 can be made into a planar structure for its light-entering and light-exiting surfaces.

[0063] Example 2 of the present invention discloses a mold and method for manufacturing resin prism optical elements. This example uses a mold with ejector compression function, combined with an injection molding machine with ejector compression function, to achieve the manufacturing process through ejector compression. See [link to documentation]. Figure 5 It includes a fixed mold and a moving mold. The fixed mold is further divided into a pre-machined station and a post-machined station. The moving mold is divided into mold number one and mold number two, for a total of four parts. Mold number one and mold number two of the moving mold have the same shape, while the pre-machined station and the post-machined station of the fixed mold have different shapes.

[0064] The pre-forming station of the fixed mold includes a fixed mold base plate 10, a pre-forming station hot runner plate 20, a pre-forming station hot nozzle 21, a pre-forming station needle valve inlet 22, and a pre-forming station fixed platen 30. The pre-forming station hot runner plate 20 is disposed on the lower end face of the fixed mold base plate 10, and the pre-forming station fixed platen 30 is connected to the lower end face of the pre-forming station hot runner plate 20. The post-forming station of the fixed mold includes a fixed mold base plate 10, a post-forming station hot runner plate 23, a post-forming station hot nozzle 24, a post-forming station needle valve inlet 25, and a post-forming station fixed platen 32. The post-forming station hot runner plate 23 is disposed on the lower end face of the fixed mold base plate 10, and the post-forming station fixed platen 32 is connected to the lower end face of the post-forming station hot runner plate 23. In this invention, the pre-forming and post-forming stations share a single fixed mold base plate 10.

[0065] The moving mold No. 1 includes a moving mold platen 40, a mold support plate 54, an ejection mechanism 60, and a moving mold base plate 70. The ejection mechanism 60 is mounted on the moving mold base plate 70, the mold support plate 54 is mounted on the ejection mechanism 60, and the moving mold platen 40 is mounted on the mold support plate 54. The ejection mechanism is equipped with a compression core 62, a compression ejector rod 63, and a standard ejector rod 64. The standard ejector rod 64 is divided into two sections: one section is fixed to the ejection mechanism 60, and the other section is fixed to the mold support plate 54. A compression gap 65 is provided between the two sections.

[0066] The second moving mold includes a second moving mold plate 41, a second mold support plate 51, a second mold ejection mechanism 61, and a moving mold base plate 70. The second mold ejection mechanism 61 is mounted on the moving mold base plate 70. The second mold support plate 55 is mounted on the second mold ejection mechanism 61. The second mold moving mold plate 41 is mounted on the second mold support plate 51. The second mold compression core 66, the second mold compression ejector rod 67, and the second mold ordinary ejector rod 68 are mounted on the second mold ejection mechanism 61. The second mold ordinary ejector rod 68 is divided into two sections: one section is fixed to the ejection mechanism 61, and the other section is fixed to the second mold support plate 55, with a compression gap 69 reserved between them. In this invention, the first and second molds share a single moving mold base plate 70.

[0067] After the fixed mold first-mold station and the moving mold are closed, they can form the first-mold station cavity 31 (the transparent area of ​​the triangular prism). After the fixed mold last-mold station and the moving mold are closed, they can form the last-mold station cavity 33 (the black area of ​​the triangular prism).

[0068] One end of the pre-drilling cavity 31 is connected to the pre-drilling hot nozzle 21 via the pre-drilling needle valve inlet 22. The pre-drilling hot nozzle 21 is connected to the pre-drilling mold sprue sleeve 11 on the fixed mold base plate 10. The pre-drilling hot nozzle 21 is located inside the cavity of the pre-drilling hot runner plate 20. One end of the post-drilling cavity 33 is connected to the post-drilling hot nozzle 24 via the post-drilling needle valve inlet 25. The post-drilling hot nozzle 24 is connected to the post-drilling mold sprue sleeve 12 on the fixed mold base plate 10. The post-drilling hot nozzle 24 is located inside the cavity of the post-drilling hot runner plate 23.

[0069] In this invention, a 100mm heat insulation gap 80 is provided between the first and last machining stations of the fixed mold. The mold has a central rotation axis 90, and the first and second moving molds are centrally symmetrical with respect to the central rotation axis 90.

[0070] The compression process used in this mold is specifically implemented as follows:

[0071] 1. First, the moving mold platen of mold number one is in the first-stage machining position, forming the first-stage machining cavity with the fixed mold platen of the first-stage machining position. The moving mold platen of mold number two is in the second-stage machining position, forming the second-stage machining cavity with the fixed mold platen of the second-stage machining position. The barrel of the first-stage machining position is made of transparent material, while the barrel of the second-stage machining position is made of black material.

[0072] 2. The compression rod stroke can be preset to within 0.1 to 2 mm;

[0073] 3. Use normal injection to fill the cavity of the first injection station to about 99%, then switch to holding pressure;

[0074] 4. After holding the pressure for 5 to 10 seconds, the ejector compression is initiated at the first station. The ejector mechanism drives the compression ejector rod and the compression mold core forward to compress the cavity at the first station.

[0075] 5. After cooling for a period of time, open the mold again, then rotate the moving mold side 180°, and rotate the moving platen of the first mold to the rear machining position. The products that have been machined out in the first mold and the rear fixed mold form the rear machining position cavity. The moving platen of the second mold rotates to the first machining position and forms the first machining position cavity with the first machining position fixed platen.

[0076] 6. The black material is injected at the rear work station, while the transparent material is injected at the front work station at the same time;

[0077] 7. After cooling, the mold opens, and the ejector mechanism at the rear station moves forward, driving the ordinary ejector pin forward. The reserved gap on the ordinary ejector pin gradually decreases and makes contact until the ordinary ejector pin ejects the product.

[0078] 8. The moving mold rotates 180° again to start the next cycle.

[0079] Figure 2 , Figure 3 , Figure 4 This is a product image.

[0080] In addition to the compression methods described in the two embodiments above, other compression methods may also be available for this invention:

[0081] 1. When using a standard mold for standby compression, no special compression plate or compression gap is needed. A certain gap should be left between the stationary and moving molds during mold closing. To prevent flash, an interlocking surface is required. When switching to pressure holding mode, continue mold closing until tightly closed.

[0082] 2. Non-expansion compression plates are used for compression. There are also special compression plates and compression gaps, but a larger clamping force is used when closing the mold. There is no expansion process when holding pressure, and the compression gap is directly reduced to 0.

[0083] The resin prism produced in Example 2 can be made into a planar structure for its light-entering and light-exiting surfaces.

[0084] This invention relates to a mold and method for fabricating a resin prism optical element, as described in Example 3. Besides the two-color injection molding method described in the above examples, this invention also provides other methods to replace the fabrication process of the extinction region. See [link to example]. Figure 6 and Figure 7 This mold is divided into a fixed mold and a moving mold. The fixed mold is further divided into a fixed mold base plate (10), a hot runner plate (201), and a fixed mold plate (301). The moving mold is divided into a moving mold base plate (70), an ejection mechanism (601), a compression plate (501), and a moving mold plate (401). The fixed mold base plate (10) is above the hot runner plate (201), which contains a hot nozzle (241) and a valve pin (221). The fixed mold plate (301) is below the hot runner plate (201), and the valve pin (221) and the hot nozzle (241) penetrate the hot runner plate (201) and the fixed mold plate (301). The moving mold plate (401) is above the compression plate (501). The moving mold plate (401) and the fixed mold plate (301) together form the product cavity. The area inside the cavity that requires matte finishing is the textured / frosted area (311). Figure 6 Product slant area. Compression plate 501 is located below moving mold plate 401. Compression spring 511 is installed inside compression plate 501. Below compression plate 501 is ejection mechanism 601. Below ejection mechanism 601 is moving mold base plate 70.

[0085] The process used in this mold, specifically, is as follows:

[0086] The mold corresponding to the area of ​​the product requiring matte finish has already undergone a textured / frosted treatment. After the mold is installed in the clamping section of the injection molding machine, it is heated to a suitable temperature (for PC resin, the mold temperature is generally 100-140℃). The resin material also needs sufficient drying temperature and time (for PC resin, generally 120℃ for 4 hours). Then the cycle begins. The injection molding machine first closes the mold with a lower clamping force (generally about 1 / 3 of the normal clamping force of the product; for example, if a prism requires 50 tons of clamping force, then only 10-20 tons of clamping force needs to be set initially to ensure that there are no flashes on the parting surface). After the mold is closed, the injection section of the injection molding machine injects molten resin into the mold. After the resin fills 99% of the cavity, the injection section of the injection molding machine switches to holding pressure (holding pressure is generally set to 5-20 MPa). Simultaneously with or 1-2 seconds later than holding pressure, the clamping section gradually increases the pressure until it reaches the normal clamping force required for the product (e.g., 50 tons), compressing the product, generally by 0.1-0.2 mm. Under sufficient holding and compression pressure, the resin will effectively replicate the shape of the mold surface, including the light-transmitting area and the leather / frosted area. After a certain cooling time (generally 100-200 seconds), the solidified product will have the shape designed by the mold, including the light-transmitting area with strict surface requirements and the leather / frosted area that needs to be matte.

[0087] Understandably, applying a textured / frosted finish to the surface of an injection mold is a very simple process. However, using this method in the molding process of prism optical elements can greatly simplify the traditional blackening process for prism optical elements, while also streamlining the two-color injection molding process of this invention, further improving product manufacturing efficiency. For example... Figure 2 As shown, the transparent area of ​​the product is the main structure of the prism, and the shadow area of ​​the product corresponds to the matte area after two-color injection molding or leather / frosted treatment.

[0088] The resin prism produced in Example 3 can be made into a planar structure for its light-entering and light-exiting surfaces.

[0089] This invention provides a mold and method for preparing a resin prism optical element. In Example 4, in the structure of Example 1 or Example 2, the light-entering and light-exiting surfaces of the prism can be made such that the light-entering surface is aspherical and the light-exiting surface is planar.

[0090] Example 5 of the present invention provides a mold and method for preparing a resin prism optical element. In the structure of Example 1 or Example 2, the light-entering and light-exiting surfaces of the prism can be made to be aspherical structures.

[0091] Table 1 shows a comparison of the structure and product performance of different embodiments of the present invention:

[0092] Table 1

[0093] Inlet and outlet light surface shapes Light-gathering surface profile accuracy / nm Light-emitting surface profile accuracy / nm Reflective surface (all flat) surface accuracy / nm Angular accuracy tolerance / minute Material Example 1 flat 96 95 240 ±5 PC Example 2 flat 82 80 230 ±4 PC Example 3 flat 68 70 180 ±2 PC Example 4 The light-entry surface is aspherical, and the light-exit surface is planar. 100 80 250 ±3 PC Example 5 Both the light-entry surface and the light-exit surface are aspherical. 110 105 260 ±2.5 PC Comparative Example 1 flat 72 75 190 ±2 Glass .

[0094] This invention employs injection molding to fabricate resin prisms. The injection molding process can be two-color compression injection molding, where transparent resin material forms the main structure of the prism, and black resin material forms the extinction area. Alternatively, it can be single-color compression injection molding, where the non-textured / frosted transparent resin material area corresponds to the main structure of the prism, and the textured / frosted area corresponds to the extinction area. The latter method eliminates the need for two-color injection molding, making the fabrication process simpler and more efficient. Understandably, both methods can be applied simultaneously, which improves the adhesion of the black injection layer and, through the combined effect, achieves a better extinction effect. Using the technical approach of this invention, various shapes, including planar, spherical, aspherical, and freeform surfaces, can be fabricated on the optical surfaces of the prism, further expanding and supporting the application of the prism in the field of precision optics.

Claims

1. A mold for fabricating a resin prism optical element, characterized in that: A two-color triangular prism injection mold includes a fixed mold and a moving mold. The fixed mold is divided into a pre-forming station and a post-forming station. Each station has a hot runner plate on the lower end face of the fixed mold base plate, and a template is set on the lower end face of each hot runner plate. The pre-forming station is used to form the main structure of the triangular prism, and the post-forming station is used to form the matte area. The moving mold is divided into a first mold and a second mold. The first mold and the second mold have ejection mechanisms on the moving mold base plate, and a compression mechanism is set on each ejection mechanism. The moving mold is set on each compression mechanism. The moving mold plate and its corresponding fixed mold plate form station cavities of different shapes. One end of each station cavity is connected to the corresponding station hot nozzle, and each station hot nozzle is connected to the corresponding mold sprue sleeve on the fixed mold base plate. The compression mechanism is provided with a compression ejector rod and a normal ejector rod on the ejection mechanism, and a compression mold core is provided at the other end of the compression ejector rod. The first station of the fixed mold and the moving mold are combined to form a first station cavity for injecting transparent materials, and the last station of the fixed mold and the moving mold are combined to form a last station cavity for injecting black materials.

2. The mold for fabricating a resin prism optical element according to claim 1, characterized in that: The compression mechanism is equipped with a compression plate, and a compression spring is provided between the compression plate and the corresponding moving template. A compression gap of 2-4 mm is left between the compression plate and the moving template.

3. The mold for fabricating a resin prism optical element according to claim 1, characterized in that... The first and second molds of the moving mold have the same shape, while the first and last machining stations of the fixed mold have different shapes.

4. The mold for fabricating a resin prism optical element according to claim 1, characterized in that... A 100mm heat insulation gap is provided between the first and last machining stations of the fixed mold.

5. The mold for fabricating a resin prism optical element according to claim 1, characterized in that... The mold is equipped with a central rotating shaft, and the first and second moving molds are centrally symmetrical with respect to the rotating shaft.

6. A method for fabricating a prism using a mold for fabricating a resin prism optical element according to any one of claims 1 to 5, characterized in that... Includes the following steps: (1). The moving template of mold No. 1 is in the first-stage molded position, and together with the fixed template of the first-stage molded position, they form the first-stage molded cavity. The moving template of mold No. 2 is in the second-stage molded position, and together with the fixed template of the second-stage molded position, they form the second-stage molded cavity. The barrel of the first-stage molded position is made of transparent material, and the barrel of the second-stage molded position is made of black material. (2). Adjust the clamping force of the two-color injection molding machine with clamping compression function so that when manually clamping the mold with this clamping force, the mold can be closed to the bottom and the compression gap is 0. (3). Set the clamping force of the injection molding machine to 1 / 3 of the normal clamping force and start fully automatic. The compression gap between the compression mechanism and the moving platen will leave a gap of 0.1 to 0.2 mm. The filling resin material is injected into the corresponding cavity through the corresponding mold gate sleeve and the station hot nozzle. (4). When the cavity is filled to more than 99% and the pressure is switched, the mold clamping part of the injection molding machine starts to switch to the first stage of compression mode: expansion. At first, a smaller compression force is used. At this time, as the cavity is gradually filled, the pressure inside the mold gradually increases, exceeds the clamping force, and transmits the pressure to the compression mechanism through the compression mold core, driving the compression mechanism to move backward. The compression gap between the compression mechanism and the moving platen will gradually expand to 0.2~0.3mm. (5). Entering the second stage of compression mode: compression, the clamping part of the injection molding machine gradually increases the clamping force, gradually exceeds the mold cavity pressure, and then drives the compression mechanism forward, the compression gap narrows, the compression mold core compresses the product evenly and thins it, and finally until the compression gap is narrowed to close to 0. (6). After cooling for a period of time, open the mold again, and then rotate the moving mold side 180°. The moving platen of the first mold rotates to the rear working position. The product that has been punched out in the first mold and the fixed platen of the rear working position form the rear working position cavity. The moving platen of the second mold rotates to the first working position and forms the first working position cavity with the fixed platen of the first working position. (7). The black material is injected at the next work station, while the transparent material is injected at the first work station. (8). After cooling, the mold is opened, and the ejector mechanism at the rear station moves forward, driving the ejector pin to eject the product. (9) The moving mold rotates 180° again to start the next cycle.

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