Manufacturing method of free-form surface large-view low-distortion automobile rearview mirror

Abstract

The invention belongs to the technical field of automobile part manufacturing, and discloses a free-form surface large-view low-distortion automobile rearview mirror manufacturing method which comprises the following steps: S1, curved surface design and modeling, S2, mold manufacturing, S3, mold polishing, S4, lens manufacturing, S5, lens optical treatment, S6, lens quality detection, S7, mirror shell manufacturing, S8, assembling and forming, and S9, quality detection. According to the technical scheme, the machining technology of the lens is simplified, meanwhile, the quality of the lens is improved, the production efficiency is improved, the production cost is reduced, large-scale application and popularization of the free-form surface rearview mirror are facilitated, the strict detection process is conducted on the quality of the lens, the curved surface characteristics of the rearview mirror can be known more comprehensively, more accurate curved surface description is obtained, and the production efficiency is improved. The detection efficiency is further improved; and meanwhile, the quality of the assembled product is detected, so that the rejection rate of the product is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile parts manufacturing, and particularly relates to a manufacturing method of a free-form surface large-view low-distortion automobile rearview mirror. BACKGROUND

[0002] During the driving of an automobile, a rearview mirror is an important part for ensuring driving safety, which can provide a driver with a view of the rear and side of the automobile. Traditional automobile rearview mirrors mostly adopt a planar or simple spherical surface design, and the view range of the rearview mirror with such a structure is limited, and there is a large visual blind area, which cannot meet the needs of a driver for observing the overall environment around the automobile. With the development of the automobile industry, free-form surface rearview mirrors have gradually attracted attention. A free-form surface can be constructed in a complex curved surface form according to optical design requirements, thereby effectively expanding the view range and reducing the blind area. However, there are many problems in the manufacturing process of the current automobile free-form surface rearview mirror. On the one hand, the forming precision of the free-form surface is difficult to guarantee, and the traditional mold forming method is difficult to accurately copy the complex free-form surface, resulting in unstable optical performance of the mirror; on the other hand, the manufacturing process is complex, the production efficiency is low, and the cost is high, which is not conducive to the large-scale popularization and application of the free-form surface rearview mirror; therefore, an automobile free-form surface rearview mirror manufacturing method capable of improving the forming precision, simplifying the manufacturing process and reducing the cost is urgently needed. SUMMARY

[0003] The present application aims to provide a manufacturing method of a free-form surface large-view low-distortion automobile rearview mirror to solve the problems in the background art.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0005] A manufacturing method of a free-form surface large-view low-distortion automobile rearview mirror, comprising the following steps,

[0006] S1, surface design and modeling, using a computer CAD software, a three-dimensional model of a free-form surface mirror is designed and drawn according to the view requirements, distortion requirements and installation requirements of the automobile rearview mirror; after the three-dimensional model of the mirror is established, the three-dimensional model data of the mirror is input into an optical simulation software, the optical performance of the surface is simulated and analyzed through the optical simulation software, the surface parameters are adjusted to ensure that the designed free-form surface can meet the requirements of expanding the view range and reducing the blind area; at the same time, a mirror shell model is designed through the computer CAD software, a mirror mold model is derived according to the three-dimensional model of the mirror, and a mirror shell mold model is derived according to the mirror shell model;

[0007] S2, making a mold, using 3D printing technology to make a lens mold; the lens mold model data generated in step S1 is imported into the 3D printer, and a resin material with high temperature resistance and high strength is selected; the printing accuracy, layer thickness and printing speed of the 3D printing are set, and after the setting is completed, the lens mold is printed, and the lens mold is obtained; select 718 steel to make a mirror shell mold, export the mirror shell mold model generated in step S1 as a processing drawing, and process the 718 steel according to the mirror shell mold model processing drawing to complete the manufacture of the mirror shell mold;

[0008] S3, polishing the mold, polishing the lens mold and the mirror shell mold made in step S2 to obtain smooth and accurate lens mold and mirror shell mold;

[0009] S4, making a lens, the lens raw material is selected from optical grade polycarbonate, the optical grade polycarbonate particles are dried to remove the water in the polycarbonate particles to prevent defects such as bubbles in the molding process; the dried polycarbonate particles are added to the barrel of the injection molding machine to melt, the lens mold prepared in step S3 is installed on the injection molding machine, the temperature of the lens mold is adjusted, the molten polycarbonate is injected into the lens mold cavity at an injection pressure of 50-80MPa, and the mold is opened after the lens is cooled and solidified to obtain the lens;

[0010] S5, optical processing of the lens, vacuum coating technology is used to coat an optical film on the surface of the lens, after the coating is completed, the lens surface is polished using a polishing device to further improve the flatness and smoothness of the lens surface, and the optical performance of the lens meets the design requirements;

[0011] S6, quality detection of the lens, the quality of the lens is judged by detecting the radius of curvature of the lens; including the following detection steps;

[0012] S61, determining the measurement point, selecting a plurality of representative points on the surface of the lens as measurement points;

[0013] S62, measuring the incident angle and the reflection angle, a parallel light is emitted by a laser pen to the selected measurement point, the included angle i between the incident light and the normal line of the mirror surface is measured, and the included angle r between the emitted light and the normal line of the mirror surface is measured, i is the incident angle, and r is the reflection angle; wherein the incident angle is equal to the reflection angle;

[0014] S63, calculating the radius of curvature, setting the air refractive index n1=1, determining the refractive index n2 of the lens material, n2 can be obtained by the lens material, and the calculation formula is established:

[0015]

[0016] The radius of curvature can be calculated by the following formula:

[0017]

[0018] Wherein R is the radius of curvature at the measurement point, L is the distance of the light ray from the point of incidence to the point of reflection on the lens surface, L can be obtained by direct measurement; and the radius of curvature at the measurement point can be obtained, and the radius of curvature of multiple measurement points can be measured in the same way;

[0019] S64, screening, comparing the measured radius of curvature with the design, within a reasonable error, that is, a qualified product, entering the next process, unqualified is discarded;

[0020] S7, making a mirror shell, the raw material of the mirror shell is ABS resin plastic, ABS resin plastic particles are placed in the injection molding machine for hot melting, and then the hot-melted ABS resin plastic is injected into the mirror shell mold prepared in step S3 through the injection molding machine, and the mirror shell is taken out after cooling and mold opening. Polishing the mirror shell to obtain a smooth mirror shell;

[0021] S8, assembling and forming, assembling the qualified lens in step S6 and the mirror prepared in step S7 to obtain a rearview mirror;

[0022] S9, quality detection, using optical detection equipment to detect the field of view, distortion and light transmittance of the rearview mirror to ensure that it meets the relevant standards.

[0023] Preferably, the printing accuracy in step S2 is controlled to be 0.01-0.05mm, the layer thickness is set to 0.02-0.08mm, and the printing speed is set to 20-60mm / s.

[0024] Preferably, the drying temperature of the optical grade polycarbonate particles in step S4 is 80-100℃, and the drying time is 4-6h.

[0025] Preferably, the melting temperature of the polycarbonate particles is set to 280-320℃, and the temperature of the lens mold is adjusted to 60-80℃.

[0026] Preferably, in step S4, the polycarbonate is injected into the cavity of the lens mold and then pressure is maintained for 10-20 seconds.

[0027] Preferably, in step S5, the optical film is selected to be an anti-reflection film or an anti-glare film.

[0028] Preferably, in step S7, a circulating water cooling method is used to accelerate the cooling speed of the ABS resin plastic in the mirror shell mold, and a protective layer is coated on the surface of the mirror shell after polishing.

[0029] Preferably, the protective layer is composed of 25% glass powder, 35% fluorite powder, 35% low-carbon powder and 5% silicon-calcium powder.

[0030] Preferably, in step S9, the impact resistance and vibration resistance of the rearview mirror are also detected; the rearview mirror is placed on a test bench, and the impact resistance of the rearview mirror is detected by free falling of a ball at different heights; the rearview mirror is clamped on a vibration table, and the vibration table is started to make the rearview mirror vibrate at a certain vibration frequency, thereby completing the detection of the vibration resistance of the rearview mirror.

[0031] Preferably, in step S9, the scratches, bubbles and impurities on the surface of the rearview mirror are also detected.

[0032] The technical scheme compared with the prior art has the beneficial effects that:

[0033] (1) The technical scheme adopts computer-aided design and optical simulation technology to design a free-form surface, which can accurately design a free-form surface meeting the optical performance according to the field of view requirement, thereby ensuring the optical quality of the rearview mirror from the source; the 3D printing technology is used to make a lens mold, which can more accurately copy the shape of the free-form surface compared with the traditional mold making method, improve the forming precision of the lens mold, shorten the mold making cycle and reduce the mold making cost; the polycarbonate particles are dried, and the barrel temperature, lens mold temperature, injection pressure and holding pressure time are controlled, thereby effectively reducing the generation of defects such as bubbles and deformation in the lens forming process, improving the forming quality and production efficiency of the lens; the lens processing technology is simplified, the lens quality is improved, the production efficiency is improved, the production cost is reduced, and the large-scale popularization and application of the free-form surface rearview mirror are facilitated.

[0034] (2) The technical scheme makes strict detection process for the quality of the lens, measures the incidence angle and reflection angle of the light on the lens surface, uses the geometric relationship between the angles and the curvature radius of the lens to solve the curvature radius, accurately measures the curvature radius of the lens, simplifies the detection process, improves the detection accuracy, and further improves the production efficiency and quality; a plurality of measurement points are selected, and the plurality of points are measured and calculated, so that the surface characteristics of the rearview mirror can be more comprehensively understood, a more accurate surface description can be obtained, and the detection efficiency is further improved; at the same time, the quality of the assembled product is also detected, and the product scrap rate is greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The flowchart of the present application is shown in the figure; DETAILED DESCRIPTION

[0036] The present application will be further described in detail below in combination with the drawings and embodiments:

[0037] A manufacturing method of a free-form surface large-view low-distortion automobile rearview mirror, comprising the following steps,

[0038] S1, curved surface design and modeling, using computer CAD software, according to the field of view requirements, distortion requirements and installation requirements of automobile rearview mirror, design and draw the free curved surface three-dimensional model of lens; after the three-dimensional model of lens is established, input the three-dimensional model data of lens into optical simulation software, and select Zemax in optical simulation software; simulate and analyze the optical performance of the curved surface through the optical simulation software, adjust the curved surface parameters, and ensure that the designed free curved surface can meet the requirements of expanding the field of view and reducing the blind area; at the same time, design the lens shell model through computer CAD software, export the lens mold model according to the three-dimensional model of lens, and export the lens shell mold model according to the lens shell model;

[0039] S2, making mold, using 3D printing technology to make lens mold; import the lens mold model data generated in step S1 into 3D printer, and select high-temperature and high-strength resin material as the printing lens mold raw material; set the printing precision, layer thickness and printing speed of 3D printing, the printing precision is set to 0.03mm, the layer thickness is set to 0.06mm, and the printing speed is set to 40mm / s; after setting, start printing the lens mold, and get the lens mold; select 718 steel to make the lens shell mold, export the lens shell mold model generated in step S1 as a processing drawing, and process the 718 steel according to the lens shell mold model processing drawing to complete the production of the lens shell mold;

[0040] S3, polishing mold, polishing the lens mold and lens shell mold made in step S2 to get smooth and accurate lens mold and lens shell mold;

[0041] S4, making lens, the lens raw material is selected as optical grade polycarbonate, the optical grade polycarbonate particles are dried, the drying temperature of the optical grade polycarbonate particles is 90℃, and the drying time is 5h, so as to remove the water in the polycarbonate particles and prevent defects such as bubbles in the forming process; melt the dried polycarbonate particles in the barrel of the injection molding machine, the melting temperature of the polycarbonate particles is set to 300℃, so as to avoid that the high temperature affects the structure of polycarbonate and reduces the lens forming quality, install the lens mold made in step S3 on the injection molding machine, adjust the temperature of the lens mold, and adjust the temperature of the lens mold to 70℃, inject the molten polycarbonate into the lens mold cavity at an injection pressure of 65MPa, avoid bubbles in the cooling process of polycarbonate, and keep pressure for 15 seconds; after the lens is cooled and solidified, open the mold to get the lens;

[0042] S5, lens optical processing, vacuum coating technology is adopted to coat optical film on the surface of the lens, the optical film is selected as antireflection film or anti-glare film, and corresponding optical film can also be coated according to actual needs in actual production; after coating, polish the surface of the lens using polishing equipment to further improve the flatness and smoothness of the lens surface, so that the optical performance of the lens meets the design requirements;

[0043] S6, quality detection of the lens, detecting the radius of curvature of the lens to determine whether the quality of the lens is qualified; comprising the following detection steps;

[0044] S61, determining the measurement point, selecting a plurality of representative points on the surface of the lens as measurement points;

[0045] S62, measuring the incident angle and the reflection angle, a parallel light is emitted by the laser pen to the selected measurement point, the angle i between the incident light and the normal of the mirror surface is measured, and the angle r between the emitted light and the normal of the mirror surface is measured, i is the incident angle, and r is the reflection angle; wherein the incident angle is equal to the reflection angle;

[0046] S63, calculating the radius of curvature, setting the air refractive index n1=1, determining the refractive index n2 of the lens material, n2 can be obtained by the lens material, and a calculation formula is established:

[0047]

[0048] According to the refraction law n1sini=n2sinr, the above formula can be obtained Further, the above formula can be derived,

[0049] Further, the radius of curvature can be calculated by the following formula:

[0050]

[0051] Wherein R is the radius of curvature at the measurement point, L is the distance between the incident point and the reflection point of the light on the surface of the lens, L can be obtained by direct measurement; and the radius of curvature at the measurement point can be obtained, and the distance radius of a plurality of measurement points is measured;

[0052] By measuring the incident angle and the reflection angle of the light on the surface of the mirror, the geometric relationship between these angles and the radius of curvature of the mirror is used to solve the radius of curvature. The law of reflection of light ensures that the incident angle and the reflection angle are equal, and the refraction law relates the propagation angle of light in different media to the refractive index of the medium;

[0053] S64, screening, comparing the measured radius of curvature with the design, within a reasonable error, it is a qualified product, entering the next process, and unqualified is discarded;

[0054] S7, making a mirror shell, the raw material of the mirror shell is ABS resin plastic, ABS resin plastic particles are placed into an injection molding machine to be hot-melted, then the hot-melted ABS resin plastic is injected into the mirror shell mold prepared in step S3 through the injection molding machine, and the mirror shell is taken out after cooling and mold opening, the cooling speed of the ABS resin plastic in the mirror shell mold can be accelerated by using a circulating water cooling method, and the mirror shell is polished to obtain a smooth mirror shell; a protective layer is coated on the surface of the mirror shell after polishing and polishing of the mirror shell, the protective layer is composed of 25% glass powder, 35% fluorite powder, 35% low-carbon powder and 5% silicon-calcium powder; the production of the mirror shell and the lens can be carried out simultaneously during production;

[0055] S8, assembling and forming, the qualified lens in step S6 and the mirror prepared in step S7 are assembled to obtain a rearview mirror;

[0056] S9, quality detection, the optical detection equipment is used to detect the field of view, distortion and light transmittance of the rearview mirror, so that the rearview mirror meets the relevant standards; the impact resistance and vibration resistance of the rearview mirror are detected; the rearview mirror is placed on a test table, and the impact resistance of the rearview mirror is detected by free falling of a ball with different heights; the rearview mirror is clamped on a vibration table, the vibration table is started to make the rearview mirror vibrate at a certain vibration frequency, and then the vibration resistance of the rearview mirror is detected; the scratches, bubbles and impurities on the surface of the rearview mirror are detected.

[0057] The above is only an embodiment of the present application, and the specific technical solutions and / or common knowledge of characteristics in the scheme are not described in detail. It should be noted that for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, which will not affect the effect and practicality of the present application. The protection scope of the present application should be subject to the content of its claims, and the specific embodiments in the specification can be used to explain the content of the claims.

Claims

1. A method for manufacturing a free-form surface large field of view low distortion rearview mirror for a vehicle, characterized in that, The method comprises the following steps, S1, curved surface design and modeling, using computer CAD software, according to the field of view requirements, distortion requirements and installation requirements of the automobile rearview mirror, design and draw the three-dimensional model of the free curved surface lens; After the three-dimensional model of the lens is established, the three-dimensional model data of the lens is input into the optical simulation software, the optical performance of the curved surface is simulated and analyzed through the optical simulation software, the curved surface parameters are adjusted, and it is ensured that the designed free curved surface can meet the requirements of expanding the field of view and reducing the blind area; At the same time, the lens shell model is designed by computer CAD software, the lens mold model is exported according to the three-dimensional model of the lens, and the lens shell mold model is exported according to the lens shell model; S2, making mold, using 3D printing technology to make lens mold; The lens mold model data generated in step S1 is imported into the 3D printer, and a resin material with high temperature resistance and high strength is selected; Set the printing accuracy, layer thickness and printing speed of 3D printing, and start printing the lens mold after setting is completed to obtain the lens mold; Select 718 steel to make the lens shell mold, export the lens shell mold model generated in step S1 as a processing drawing, and process the 718 steel according to the lens shell mold model processing drawing to complete the manufacture of the lens shell mold; S3, polishing mold, polishing the lens mold and the lens shell mold made in step S2 to obtain smooth and accurate lens mold and lens shell mold; S4, making lens, the raw material of the lens is selected as optical grade polycarbonate, the optical grade polycarbonate particles are dried to remove the water in the polycarbonate particles to prevent defects such as bubbles in the forming process; The dried polycarbonate particles are added to the barrel of the injection molding machine for melting, the lens mold made in step S3 is installed on the injection molding machine, the temperature of the lens mold is adjusted, the molten polycarbonate is injected into the lens mold cavity at an injection pressure of 50-80MPa, the pressure is maintained, and the lens is taken out after cooling and solidification to obtain the lens; S5, lens optical processing, vacuum coating technology is used to coat optical film on the surface of the lens, after coating is completed, polishing equipment is used for polishing the surface of the lens to further improve the flatness and smoothness of the surface of the lens, so that the optical performance of the lens meets the design requirements; S6, quality detection of the lens, the quality of the lens is judged by detecting the radius of curvature of the lens; The method comprises the following detection steps: S61, determining the measurement point, selecting a plurality of representative points on the surface of the lens as measurement points; S62, measuring the incident angle and the reflection angle, a parallel light is emitted by a laser pen to the selected measurement point, the included angle i between the incident light and the normal line of the surface of the rearview mirror is measured, and the included angle r between the emitted light and the normal line of the surface of the rearview mirror is measured, i is the incident angle, and r is the reflection angle; Wherein the incident angle is equal to the reflection angle; S63, calculating the radius of curvature, setting the air refractive index n1=1, determining the refractive index n2 of the lens material, n2 can be obtained by the lens material, and the calculation formula is established: And the radius of curvature can be calculated by the following formula: Wherein R is the radius of curvature at the measuring point, L is the distance of the light ray from the point of incidence to the point of reflection on the lens surface, L can be obtained by direct measurement; and the radius of curvature at the measuring point can be obtained, and the radius of curvature of a plurality of measuring points is measured in the same way; S64, screening, comparing the measured radius of curvature with the design, within a reasonable error, that is, a qualified product, into the next process, unqualified is discarded; S7, making a mirror shell, the raw material of the mirror shell is ABS resin plastic, ABS resin plastic particles are placed in an injection molding machine for hot melting, then the hot-melted ABS resin plastic is injected into the mirror shell mold prepared in step S3 through the injection molding machine, and the mirror shell is taken out after cooling and mold opening, and the mirror shell is polished to obtain a smooth mirror shell; S8, assembling and forming, the qualified lens in step S6 and the mirror prepared in step S7 are assembled to obtain a rearview mirror; S9, quality detection, using optical detection equipment to detect the field of view, distortion and light transmittance of the rearview mirror to ensure that it meets the relevant standards.

2. The method of claim 1, wherein the method further comprises: forming a first surface of the mirror substrate by a first molding process; and forming a second surface of the mirror substrate by a second molding process. The printing accuracy in step S2 is controlled to be 0.01-0.05mm, the layer thickness is set to be 0.02-0.08mm, and the printing speed is set to be 20-60mm / s.

3. The method of claim 1, wherein the method further comprises: forming a first surface of the mirror substrate by a first molding process; and forming a second surface of the mirror substrate by a second molding process. The drying temperature of the optical grade polycarbonate particles in step S4 is 80-100℃, and the drying time is 4-6h.

4. The method of claim 1, wherein the method further comprises: forming a first surface of the mirror substrate by a first molding process; and forming a second surface of the mirror substrate by a second molding process. The melting temperature of the polycarbonate particles is set to be 280-320℃, and the lens mold temperature is adjusted to 60-80℃.

5. The method for manufacturing a freeform surface large field of view low distortion automotive rearview mirror as described in claim 1, characterized in that, In step S4, the polycarbonate is injected into the lens mold cavity and then pressure is maintained for 10-20 seconds.

6. The method of claim 1, wherein the method further comprises: forming a first layer of the first material on the substrate; forming a second layer of the second material on the first layer; and forming a third layer of the third material on the second layer. In step S5, the optical film is selected to be an anti-glare film or an anti-fog film.

7. The method for manufacturing a freeform surface large field of view low distortion automotive rearview mirror as described in claim 1, characterized in that, In step S7, a circulating water cooling method is used to accelerate the cooling speed of ABS resin plastic in the mirror shell mold, and a protective layer is coated on the surface of the mirror shell after polishing.

8. The method for manufacturing a freeform surface large field of view low distortion automotive rearview mirror as described in claim 1, characterized in that, The protective layer is composed of 25% glass powder, 35% fluorite powder, 35% low-carbon powder and 5% silicon-calcium powder.

9. The method for manufacturing a freeform surface large field of view low distortion automotive rearview mirror as described in claim 1, characterized in that, In step S9, the impact resistance and vibration resistance of the rearview mirror are also detected; the rearview mirror is placed on a test bench, and the impact resistance of the rearview mirror is detected by free falling of a ball at different heights; the rearview mirror is clamped on a vibration table, and the vibration table is started to make the rearview mirror vibrate at a certain vibration frequency, and then the vibration resistance of the rearview mirror is detected.

10. The method of claim 1, wherein the method further comprises: forming a first layer of a first material on the substrate; forming a second layer of a second material on the first layer; and forming a third layer of a third material on the second layer, wherein the first material, the second material, and the third material are different materials. In step S9, the scratches, bubbles and impurities on the surface of the rearview mirror are also detected.

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