A device and method for online detection and control of composite microstructure array microforming

Abstract

This invention provides an online detection and control device for microforming composite microstructure arrays. Its hot-pressing system includes, from top to bottom, a heating device, an upper template, a core fixing device, a microstructure core, an elastic microporous mesh, a workpiece, a workpiece positioning device, and a lower template. The microstructure core is fixed below the upper template by the core fixing device, and the upper template and the microstructure core are heated by the heating device. The elastic microporous mesh covers the bottom of the microstructure core. The workpiece and the microstructure core are positioned opposite each other. The diffuse reflection optical detection and control system includes a light emitting device, a light receiving device, and a light signal processing control module. This invention also provides an online detection and control method for microforming composite microstructure arrays, which detects the forming status of the composite microstructure on the workpiece surface or the planar microstructure on the workpiece surface by controlling the light emitting device to emit light onto the workpiece surface and controlling the light receiving device to receive diffusely reflected light.

Description

Technical Field

[0001] The present invention relates to the technical field of online monitoring and intelligent fault diagnosis of hot pressing micro-molding of composite micro-structure arrays on workpiece surfaces, and more specifically, to a device and method for online detection and control of micro-molding of composite micro-structure arrays using the principle of diffuse reflection. Background Art

[0002] High-precision microstructure arrays can be applied to LED lighting, microfluidic chips, photovoltaic power generation, optical sensors, optical imaging systems, liquid crystal displays, solar cells and other fields. Compared with planar microstructure arrays, spatial composite microstructures have a larger surface area ratio and show superior performance. However, its manufacturing cost is high. The hot pressing micro-molding technology of composite microstructure arrays is a low-cost manufacturing method, making industrialization possible. The key technology is how to quickly and accurately copy the micron or even nano array structure morphology to the workpiece surface, and intelligently detect the composite microstructure molding morphology online, and quickly feedback to the control center to realize the intelligent manufacturing of composite microstructures. At present, the morphology detection of microstructure arrays uses physical probe method and white light interferometry, but if the molding accuracy of the macroscopic surface microarray is detected, the work efficiency will be very low, and it cannot be detected and identified online. Spatial composite microstructure arrays require three-dimensional stereoscopic detection, which is even less efficient.

[0003] However, the increasingly personalized and diversified production requires different sizes of composite microstructures on the workpiece surface, and in the actual production process, product quality is easily affected by weather temperature changes, workpiece size, and equipment vibration. Therefore, it is necessary to conduct online detection during the production process of hot pressing micro-molding of composite microstructure arrays, adjust the hot pressing micro-molding process parameters in real time, and realize the precision manufacturing of composite microstructure array macro products. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings and deficiencies in the prior art and provide a device for online detection and control of micro-molding of composite microstructure arrays. The device uses the principle of diffuse reflection to quickly and reliably detect the microstructure molding of the workpiece surface, which not only greatly improves the detection efficiency and shortens the detection cycle, thereby reducing the time cost, but also provides a basis for adjusting the process parameters of subsequent process production to improve the processing quality and efficiency. The present invention also provides an efficient and reliable method for online detection and control of micro-molding of composite microstructure arrays to achieve adaptive control of composite microstructure hot pressing process.

[0005] In order to achieve the above-mentioned purpose, the present invention is implemented by the following technical scheme: an online detection and control device for micro-molding of a composite microstructure array, characterized in that it includes a hot pressing system and a diffuse reflection optical detection and control system; the hot pressing system includes a heating device, an upper template, a core fixing device, a microstructure core, an elastic microporous mesh, a workpiece, a workpiece positioning device and a lower template, which are arranged in sequence from top to bottom; the microstructure core is fixed to the bottom of the upper template by the core fixing device, and the upper template and the microstructure core are heated by the heating device; the elastic microporous mesh is coated on the bottom of the microstructure core; the workpiece is fixed to the lower template by the workpiece positioning device, and is arranged opposite to the microstructure core;

[0006] The diffuse reflection optical detection control system includes a light emitting device, a light receiving device and an optical signal processing control module; the light emitting device and the light receiving device are respectively located on both sides of the hot pressing system; the light receiving device is signal-connected to the optical information processing control module.

[0007] In the above scheme, the device of the present invention controls the lower template to drive the workpiece to close the mold on the microstructure mold core coated with an elastic microporous mesh, and maintains the pressure for a certain period of time, so that the surface of the workpiece is micro-molded to obtain a composite microstructure composed of the microstructure mold core surface and the elastic microporous mesh; and controls the light emission to emit light to the workpiece surface and controls the light receiving device to receive diffusely reflected light to detect the molding condition of the composite microstructure on the workpiece surface, thereby realizing the use of the diffuse reflection principle to quickly and reliably realize online detection of the microstructure molding condition on the workpiece surface, which not only greatly improves the detection efficiency and reduces the time cost, but also provides a basis for adjusting the process parameters for subsequent process production to improve the processing quality and efficiency.

[0008] The incident angle θ of the light beam emitted by the light emitting device and the workpiece surface is 10° to 80°; the relationship between the number n of light emitters in the light emitting device and the width d of the workpiece irradiated by a single light beam and the width l of the workpiece is:

[0009] The light receiving device is a light intensity sensor; the light intensity sensor is arranged in the theoretical direction where the incident light is specularly reflected on the surface of the workpiece.

[0010] The elastic microporous mesh is made of nylon threads or metal threads; or, the elastic microporous mesh is a microporous mesh formed by punching holes on the surface of the material using a laser punching method.

[0011] The microstructure mold core is made of stainless steel material, ceramic material or silicon carbide material.

[0012] The aperture of the elastic microporous mesh is smaller than the surface microstructure size of the microstructure mold core; the elastic microporous mesh coated on the bottom of the microstructure mold core is in a naturally stretched state.

[0013] A method for online detection and control of micro-molding of a composite microstructure array, characterized in that: by controlling a light emitting device to emit light to a workpiece surface and controlling a light receiving device to receive diffusely reflected light, the molding condition of the composite microstructure on the workpiece surface or the plane microstructure condition on the workpiece surface is detected;

[0014] Testing the forming of the composite microstructure on the workpiece surface means:

[0015] First, the target molding height of the composite microstructure and the hot pressing process parameters were set;

[0016] Secondly, the lower template is controlled to drive the workpiece to close the mold on the microstructure mold core coated with the elastic microporous mesh, and the pressure is maintained for a certain period of time, so that the surface of the workpiece is micro-molded to obtain a composite microstructure composed of the microstructure mold core surface and the elastic microporous mesh; wherein the composite microstructure includes a micro-groove structure and a surface small microlens structure;

[0017] Then, in the process of demolding the workpiece driven by the lower template, the light emitting device is controlled to move, a single light emitter is used to emit parallel light to the workpiece, and a light receiving device is used to receive diffuse reflected light, so as to realize point-by-point detection of the forming condition of the composite microstructure on the surface of the workpiece; after the workpiece is demolded and stationary, the light emitting device is controlled to use several light emitters to emit parallel light to the workpiece, and finally a light receiving device is used to receive diffuse reflected light, so as to realize comprehensive detection of the forming condition of the composite microstructure on the surface of the workpiece;

[0018] Finally, the diffuse reflectance is calculated based on the ratio of the received diffuse reflected light flux to the emitted parallel light flux, and the relationship between the diffuse reflectance and the size of the composite microstructure in the empirical database is compared to determine the depth and quality of the micro-groove structure and the surface small microlens structure of the composite microstructure. At the same time, the reasons for the micro-forming of the composite microstructure are analyzed, and the horizontality of the workpiece fixation or the hot pressing process parameters are adjusted according to the analysis results, so that the actual height of the hot-pressed composite microstructure gradually approaches the target forming height of the composite microstructure, thereby realizing adaptive control of the hot pressing process.

[0019] Specifically, the detection of the forming condition of the composite microstructure on the surface of the workpiece includes the following steps:

[0020] 1) Setting the target molding height and hot pressing process parameters of the composite microstructure; the microgroove structure height h1 of the composite microstructure is 1-1000 μm, and the height h2 of the surface microlens structure is 1-200 μm; the hot pressing process parameters are: hot pressing pressure 3-30 MPa, holding time 0.1-20 s, microstructure mold core temperature 20-200 ° C, and lower template movement speed 0.1-10 mm / s; controlling the lower template to drive the workpiece to close the mold to the microstructure mold core coated with an elastic microporous mesh under the action of the hydraulic system, and holding the pressure for a certain time to micro-form the workpiece surface to obtain a composite microstructure composed of the microstructure mold core surface and the elastic microporous mesh, wherein the composite microstructure includes a microgroove structure and a surface microlens structure;

[0021] 2) The lower template is controlled to start driving the workpiece away from the microstructure mold core and move at a uniform speed along the negative direction of the Z axis under the action of the hydraulic system. The light emitting device emits parallel light during the demoulding process, and the incident angle between the light and the workpiece surface is θ; wherein θ is 10° to 80°;

[0022] 3) The light emitting device turns on a single light emitter during the demoulding process, and uses the principle that when the workpiece moves away from the mold core at a uniform speed along the negative direction of the Z axis, the incident point of the light beam on the workpiece surface will move at a uniform speed along the positive direction of the Y axis, so as to realize point-by-point accurate detection of the composite microstructure forming condition on the workpiece surface;

[0023] 4) When the workpiece returns to the workstation and stops, all the light emitters are turned on to irradiate the entire workpiece surface, so as to quickly detect the composite microstructure forming condition on the entire workpiece surface;

[0024] 5) The light receiving device receives the light diffusely reflected from the workpiece surface, and finally performs logical processing on the light information through the optical signal processing control module;

[0025] 6) The optical signal processing control module calculates the diffuse reflectance according to the ratio of the received diffuse reflected light flux to the emitted parallel light flux, and compares the relationship between the diffuse reflectance and the size of the composite microstructure in the empirical database to determine the depth and quality of the microgroove structure of the composite microstructure and the micro-molding of the surface micro-lens structure;

[0026] 7) The optical signal processing control module analyzes the reasons for the composite microstructure forming, and adjusts the horizontality of the workpiece fixation or the hot pressing process parameters according to the analysis results, including the hot pressing pressure, holding time, microstructure core temperature and lower template movement speed, and transmits them to the PLC of the hot pressing system, and performs the next hot pressing process according to the adjusted process parameters; the above steps are repeated to make the actual height of the hot-pressed composite microstructure gradually approach the target forming height of the composite microstructure, thereby realizing adaptive control of the hot pressing process.

[0027] The establishment of the empirical database is based on the previous experiments, which means: firstly, changing the hot pressing process parameters, then recording the diffuse reflectivity of the workpiece surface and the height of the micro-groove structure of the composite microstructure and the small micro-lens structure on the surface under different hot pressing process parameters, then establishing the relationship between the diffuse reflectivity and the height of the micro-groove structure of the composite microstructure and the small micro-lens structure on the surface, and finally correlating the diffuse reflectivity with the hot pressing process parameters;

[0028] Among them, the empirical formula of the height of the micro-groove structure of the composite microstructure and the height of the small micro-lens structure on the surface and the diffuse reflectivity m is:

[0029] h1=a1m+b1;

[0030] h2=a2 m 2 +b2m+c2;

[0031] Wherein, h1 and h2 represent the height of the micro-groove structure and the height of the small micro-lens structure on the surface, respectively, in μm; m represents the diffuse reflectance, in %; a1, a2, b1, b2, c2 are constants, in μm, 0.01≤a1≤1, 5≤b1≤500, 0.001≤a2≤0.002, 0.01≤b2≤0.2, 5≤c2≤20.

[0032] The priority order of adjusting process parameters is holding time, core temperature, hot pressing pressure and lower template movement speed.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] 1. The present invention uses the diffuse reflection principle to sense the change of light illumination online, and reflects the change of the height of the composite microstructure array on the workpiece surface in real time. Compared with the method of detecting the microarray hot pressing molding by ordinary macro light sources radiating in all directions in space, it is more accurate. In addition, this method can detect both planar microstructure arrays and composite microstructure arrays, and can detect both transparent workpieces and micromolding on the surface of opaque workpieces. In addition, compared with the use of a profilometer to detect the contour shape of the composite microstructure, the detection efficiency is greatly improved, the detection cycle is shortened, and the time cost is reduced.

[0035] 2. The present invention only turns on a single light emitter during the demoulding process, and can accurately detect the composite microstructure molding situation on the workpiece surface point by point. When the workpiece returns to the workstation and stops, all light emitters are turned on, and the micro-molding situation of the composite microstructure on the entire surface can be instantly and quickly detected. Therefore, it has the characteristics of convenient operation, flexibility, high integration and multi-function.

[0036] 3. The present invention utilizes real-time analysis and diffuse reflection optical detection control system to fuse, characterize and compare the composite microstructure height, diffuse reflectivity and hot pressing parameter data, and intelligently adjusts the process parameters in real time, thereby realizing adaptive closed-loop control of the micro-molding effect of the composite microstructure array on the macroscopic surface of the product, which is beneficial to improving the anti-interference ability of the production process and can meet the needs of precise and rapid molding of diversified products, thereby reducing production costs and improving processing quality and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of a device for online detection and control of micro-molding of a composite microstructure array according to the present invention;

[0038] Figure 2 It is the principle diagram of mirror reflection;

[0039] Figure 3 This is the diffuse reflection principle diagram;

[0040] Figure 4 It is a composite microstructure micro-molding effect diagram;

[0041] Among them, 1. light source fixing device; 2. upper template; 3 (A) and 3 (B), core fixing device; 4. heating device; 5. microstructure core; 6. elastic microporous mesh; 7. receiver fixing device; 8. light receiving device; 9. lower template; 10. workpiece clamping device; 11. workpiece; 12. workpiece positioning device; 13. light emitting device; 14. optical signal processing control module. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0043] Embodiment 1

[0044] like Figure 1As shown, an online detection and control device for micro-molding of a composite microstructure array includes a hot pressing system and a diffuse reflection optical detection and control system, wherein the hot pressing system includes a heating device 4, an upper template 2, a core fixing device 3 (A), 3 (B), a microstructure core 5, an elastic microporous mesh 6, a workpiece 11, a workpiece positioning device 12 and a lower template 9 arranged in sequence from top to bottom; the microstructure core 5 is fixed to the bottom of the upper template 2 by the core fixing device 3 (A), 3 (B), and the upper template 2 and the microstructure core 5 are heated by the heating device 4; the elastic microporous mesh 6 is coated on the bottom of the microstructure core 5, and the workpiece 11 is fixed to the lower template 9 by the workpiece positioning device 12 and is arranged opposite to the microstructure core 5. The diffuse reflection optical detection and control system includes a light emitting device 13, a light receiving device 8 and an optical signal processing control module 14; the light emitting device 13 and the light receiving device 8 are fixed to the two sides of the hot pressing system by the light source fixing device 1 and the receiver fixing device 7 respectively, and the light receiving device 8 is connected to the optical information processing control module 14 by signal.

[0045] In this embodiment, the incident angle θ of the light beam emitted by the light emitting device 13 and the surface of the workpiece 11 is 45°, and the number n of light emitters in the light emitting device 13 can be calculated by the formula To calculate, the width l of the workpiece in this embodiment is 20 mm, the width d of the workpiece irradiated by a single light beam is 5 mm, and the number n of light emitters can be calculated to be 4.

[0046] The light receiving device 8 of the present invention is a light intensity sensor, which is arranged in the theoretical direction of the incident light specularly reflected on the surface of the workpiece 11. The elastic microporous mesh 6 of this embodiment is made of nylon thread, and the aperture of the elastic microporous mesh 6 is 20μm and the height is 30μm. The workpiece 11 of this embodiment is made of acrylic material, the microstructure core 5 is made of stainless steel, the surface microgroove structure is 100μm high and 375μm wide, the elastic microporous mesh 6 is fixed to the side wall of the microstructure core 5 on all sides, and the elastic microporous mesh 6 coated on the bottom of the microstructure core 5 is in a naturally stretched state.

[0047] The method used by the present embodiment for online detection and control of the composite microstructure array micro-molding device is as follows: by controlling the light emitting device 13 to emit light to the surface of the workpiece 11 and controlling the light receiving device 8 to receive the light after diffuse reflection, the molding condition of the composite microstructure on the surface of the workpiece 11 is detected, specifically:

[0048] First, the target molding height of the composite microstructure and the hot pressing process parameters were set;

[0049] Secondly, the lower template 9 is controlled to drive the workpiece 11 to close the mold to the microstructure mold core 5 coated with the elastic microporous mesh 6, and the pressure is maintained for a certain period of time, so that the surface of the workpiece 11 is micro-molded to obtain a composite microstructure composed of the surface of the microstructure mold core 5 and the elastic microporous mesh 6; wherein the composite microstructure includes a micro-groove structure and a surface small microlens structure;

[0050] Then, when the lower template 9 drives the workpiece 11 to form a film, the light emitting device 13 is controlled to move, and a single light emitter is used to emit parallel light to the workpiece 11, and the light receiving device 8 is used to receive the diffusely reflected light, so as to realize point-by-point detection of the forming condition of the composite microstructure on the surface of the workpiece 11; after the workpiece is demolded and stationary, the light emitting device 13 is controlled to use a plurality of light emitters to emit parallel light to the workpiece 11, and finally the light receiving device 8 is used to receive the diffusely reflected light, so as to realize a comprehensive detection of the forming condition of the composite microstructure on the surface of the workpiece 11;

[0051] Finally, the diffuse reflectance is calculated based on the ratio of the received diffuse reflected light flux to the emitted parallel light flux, and the relationship between the diffuse reflectance and the size of the composite microstructure in the empirical database is compared to determine the depth and quality of the micro-groove structure and the surface small micro-lens structure of the composite microstructure. At the same time, the reasons for the micro-forming of the composite microstructure are analyzed, and the fixed horizontality or hot pressing process parameters of the workpiece 11 are adjusted according to the analysis results, so that the actual height of the hot-pressed composite microstructure gradually approaches the target molding height of the composite microstructure, thereby realizing adaptive control of the hot pressing process.

[0052] Specifically, the following steps are included:

[0053] 1) Setting the target molding height and hot pressing process parameters of the composite microstructure; the microgroove structure height h1 of the composite microstructure is 70 μm, and the height h2 of the surface microlens structure is 30 μm; the hot pressing process parameters are: hot pressing pressure 10 MPa, holding time 2 s, microstructure mold core temperature 118°C, and lower template movement speed 3 mm / s; controlling the lower template 9 to drive the workpiece 11 to close the mold to the microstructure mold core 5 coated with the elastic microporous mesh 6 under the action of the hydraulic system, and holding the pressure for 2 seconds to micro-form the surface of the workpiece 11 to obtain a composite microstructure composed of the microstructure mold core surface and the elastic microporous mesh, wherein the composite microstructure includes a microgroove structure and a surface microlens structure;

[0054] 2) Control the lower template 9 to start driving the workpiece 11 away from the microstructure mold core 5 and move at a constant speed in the negative direction of the Z axis under the action of the hydraulic system. The light emitting device 13 emits parallel light during the demoulding process, and the incident angle between the light and the workpiece surface is θ; wherein θ is 45°;

[0055] 3) The light emitting device 13 turns on a single light emitter during the demolding process, and uses the principle that when the workpiece 11 moves away from the mold core at a uniform speed along the negative direction of the Z axis, the incident point of the light beam on the surface of the workpiece 11 will move at a uniform speed along the positive direction of the Y axis, so as to realize point-by-point accurate detection of the composite microstructure forming condition on the surface of the workpiece 11;

[0056] 4) When the workpiece 11 returns to the workstation and stops, the light emitting device 13 turns on all the light emitters to irradiate the entire surface of the workpiece 11, thereby realizing rapid detection of the composite microstructure forming condition on the surface of the entire workpiece 11;

[0057] 5) The light receiving device 8 receives the light diffusely reflected from the surface of the workpiece 11, and finally performs logical processing on the light information through the light signal processing control module 14;

[0058] 6) The optical signal processing control module 14 calculates the diffuse reflectance according to the ratio of the received diffuse reflected light flux to the emitted parallel light flux, and compares the relationship between the diffuse reflectance and the size of the composite microstructure in the empirical database to determine the depth and quality of the micro-groove structure of the composite microstructure and the micro-lens structure on the surface.

[0059] 7) The optical signal processing control module 14 analyzes the reasons for the composite microstructure forming, and adjusts the horizontality of the workpiece fixation or the hot pressing process parameters according to the analysis results, including the hot pressing pressure, the holding time, the microstructure core temperature and the lower template movement speed, and transmits them to the PLC of the hot pressing system, and performs the next hot pressing process according to the adjusted process parameters; the above steps are repeated so that the actual height of the hot-pressed composite microstructure gradually approaches the target forming height of the composite microstructure, thereby realizing adaptive control of the hot pressing process.

[0060] The establishment of the experience database of the present invention is based on the previous experiments, and its establishment means: firstly, changing the hot pressing process parameters, then recording the diffuse reflectivity of the surface of the workpiece 11 and the height of the micro-groove structure of the composite microstructure and the small micro-lens structure on the surface under different hot pressing process parameters, then establishing the relationship between the diffuse reflectivity and the height of the micro-groove structure of the composite microstructure and the small micro-lens structure on the surface, and finally correlating the diffuse reflectivity with the hot pressing process parameters;

[0061] Among them, the empirical formula of the height of the micro-groove structure of the composite microstructure and the height of the small micro-lens structure on the surface and the diffuse reflectivity m is:

[0062] h1=a1m+b1;

[0063] h2=a2 m 2 +b2m+c2;

[0064] Wherein, h1 and h2 represent the height of the micro-groove structure and the height of the small micro-lens structure on the surface, respectively, in μm; m represents the diffuse reflectance, in %; a1, a2, b1, b2, c2 are constants, in μm, 0.01≤a1≤1, 5≤b1≤500, 0.001≤a2≤0.002, 0.01≤b2≤0.2, 5≤c2≤20.

[0065] The priority order of adjusting process parameters is holding time, core temperature, hot pressing pressure and lower template movement speed.

[0066] In this embodiment, a single light emitter detects that the diffuse reflectances of the composite microstructures formed at three locations on the surface of the workpiece 11 are 33%, 30%, and 33%, respectively. The method of online detection and control of micro-molding of composite microstructure arrays of the present invention can be used to determine the height of the composite microstructure at the edge of the surface of the workpiece 11: the height h1 of the microgroove-shaped structure is 66.5μm, the height h2 of the small microlens structure on the surface is 27.49μm, and the height of the middle composite microstructure: the height h1 of the microgroove-shaped structure is 65, and the height h2 of the small microlens structure on the surface is 25μm; since it is lower than the preset composite microstructure molding height, and the middle is lower than the edge, it indicates that the surface of the workpiece 11 is unevenly stressed or heated. Therefore, the workpiece 11 is gradually adjusted by extending the hot pressing time, lowering the temperature of the microstructure mold core, or adjusting the fixed horizontality of the workpiece 11 until the target composite microstructure is formed. The hot pressing process parameters were finally adjusted to a hot pressing pressure of 10MPa, a holding time of 4s, a core temperature of 115°C, and a lower template movement speed of 3mm. The surface morphology of the composite microstructure micro-molded by hot pressing is as follows Figure 4 If the target size of the composite microstructure on the workpiece surface changes, or there is a large change in weather temperature, a change in the size of the workpiece being processed, or significant vibration of the equipment, the parameters are intelligently readjusted.

[0067] Embodiment 2

[0068] The only difference between this embodiment and the first embodiment is that the method of online detection and control of micro-molding of composite microstructure arrays in this embodiment is to detect the planar microstructure of the workpiece surface by controlling the light emitting device to emit light to the workpiece surface and controlling the light receiving device to receive diffusely reflected light.

[0069] This embodiment is carried out according to the following steps:

[0070] like Figure 1 As shown, the acrylic workpiece 11 is placed above the workpiece positioning device 12 and clamped by the workpiece clamping device 10. The light emitting device 13 and the light receiving device 8 are respectively fixed to the left and right sides of the hot pressing system through the light source fixing device 1 and the receiver fixing device 7, and the light receiving device 8 is connected to the optical information processing control module 14.

[0071] The workpiece 11 is not subjected to hot pressing, and the light emitting device 13 turns on all the light emitters to irradiate the entire surface of the workpiece 11. Since the original surface of the acrylic workpiece 11 to be processed is smooth, the light receiving device 8 can receive almost all the light reflected by the mirror surface of the workpiece 11. The principle of mirror reflection and diffuse reflection is as follows: Figure 2 and Figure 3 This embodiment can use this method to fully detect the surface microstructure of the acrylic workpiece 11 that is not subjected to hot pressing, greatly improving the detection efficiency, shortening the detection cycle, and thus reducing the time cost.

[0072] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for online detection and control of composite microstructure array micro-molding, characterized in that: By controlling the light emitting device to emit light to the workpiece surface and controlling the light receiving device to receive diffusely reflected light, the forming condition of the composite microstructure on the workpiece surface can be detected; The detection of the forming condition of the composite microstructure on the workpiece surface includes the following steps: 1) Setting the target molding height and hot pressing process parameters of the composite microstructure; the microgroove structure height h1 of the composite microstructure is 1-1000 μm, and the height h2 of the surface microlens structure is 1-200 μm; the hot pressing process parameters are: hot pressing pressure 3-30 MPa, holding time 0.1-20 s, microstructure mold core temperature 20-200 ° C, and lower template movement speed 0.1-10 mm / s; controlling the lower template to drive the workpiece to close the mold to the microstructure mold core coated with an elastic microporous mesh under the action of the hydraulic system, and holding the pressure for a certain time to micro-form the workpiece surface to obtain a composite microstructure composed of the microstructure mold core surface and the elastic microporous mesh, wherein the composite microstructure includes a microgroove structure and a surface microlens structure; 2) The lower template is controlled to start driving the workpiece away from the microstructure mold core and move at a uniform speed along the negative direction of the Z axis under the action of the hydraulic system. The light emitting device emits parallel light during the demoulding process, and the incident angle between the light and the workpiece surface is θ; wherein θ is 10° to 80°; 3) The light emitting device turns on a single light emitter during the demoulding process, and uses the principle that when the workpiece moves away from the mold core at a uniform speed along the negative direction of the Z axis, the incident point of the light beam on the workpiece surface will move at a uniform speed along the positive direction of the Y axis, so as to realize point-by-point accurate detection of the composite microstructure forming condition on the workpiece surface; 4) When the workpiece returns to the workstation and stops, all the light emitters are turned on to irradiate the entire workpiece surface, so as to quickly detect the composite microstructure forming condition on the entire workpiece surface; 5) The light receiving device receives the light diffusely reflected from the workpiece surface, and finally performs logical processing on the light information through the optical signal processing control module; 6) The optical signal processing control module calculates the diffuse reflectance according to the ratio of the received diffuse reflected light flux to the emitted parallel light flux, and compares the relationship between the diffuse reflectance and the size of the composite microstructure in the empirical database to determine the depth and quality of the microgroove structure of the composite microstructure and the micro-molding of the surface micro-lens structure; 7) The optical signal processing control module analyzes the reasons for the composite microstructure forming, and adjusts the horizontality of the workpiece fixation or the hot pressing process parameters according to the analysis results, including the hot pressing pressure, holding time, microstructure mold core temperature and lower template movement speed, and transmits them to the PLC of the hot pressing system, and performs the next hot pressing process according to the adjusted process parameters; the above steps are repeated so that the actual height of the hot-pressed composite microstructure gradually approaches the target forming height of the composite microstructure, and the adaptive control of the hot pressing process is realized; The establishment of the experience database means: firstly, changing the hot pressing process parameters, then recording the diffuse reflectivity of the workpiece surface and the height of the micro-groove structure of the composite microstructure and the small micro-lens structure on the surface under different hot pressing process parameters, then establishing the relationship between the diffuse reflectivity and the height of the micro-groove structure of the composite microstructure and the small micro-lens structure on the surface, and finally correlating the diffuse reflectivity with the hot pressing process parameters; Among them, the empirical formula of the height of the micro-groove structure of the composite microstructure and the height of the small micro-lens structure on the surface and the diffuse reflectivity m is: h1=a1m+b1; <h2 style=";text-align:left;direction:ltr">h2 = a2 m<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +b2m+c2; Wherein, h1 and h2 represent the height of the micro-groove structure and the height of the small micro-lens structure on the surface, respectively, in μm; m represents the diffuse reflectance, in %; a1, a2, b1, b2, c2 are constants, in μm, 0.01≤a1≤1, 5≤b1≤500, 0.001≤a2≤0.002, 0.01≤b2≤0.2, 5≤c2≤20.

2. The method for online detection and control of composite microstructure array micro-molding according to claim 1, characterized in that: The priority order of adjusting process parameters is holding time, core temperature, hot pressing pressure and lower template movement speed.

3. A device for online detection and control of composite microstructure array micro-molding, characterized in that: The method for online detection and control of micro-molding of composite microstructure arrays according to claim 1 is used for detection, and the device for online detection and control of micro-molding of composite microstructure arrays includes a hot pressing system and a diffuse reflection optical detection and control system; the hot pressing system includes a heating device, an upper template, a core fixing device, a microstructure core, an elastic microporous mesh, a workpiece, a workpiece positioning device and a lower template, which are arranged in sequence from top to bottom; the microstructure core is fixed to the bottom of the upper template by the core fixing device, and the upper template and the microstructure core are heated by the heating device; the elastic microporous mesh is coated on the bottom of the microstructure core; the workpiece is fixed to the lower template by the workpiece positioning device, and is arranged opposite to the microstructure core; The diffuse reflection optical detection control system includes a light emitting device, a light receiving device and an optical signal processing control module; the light emitting device and the light receiving device are respectively located on both sides of the hot pressing system; the light receiving device is signal-connected to the optical information processing control module.

4. The device for online detection and control of composite microstructure array micro-molding according to claim 3, characterized in that: The incident angle θ of the light beam emitted by the light emitting device and the workpiece surface is 10° to 80°; the relationship between the number n of light emitters in the light emitting device and the width d of the workpiece irradiated by a single light beam and the width l of the workpiece is:

5. The device for online detection and control of composite microstructure array micro-molding according to claim 3, characterized in that: The light receiving device is a light intensity sensor; the light intensity sensor is arranged in the theoretical direction where the incident light is specularly reflected on the surface of the workpiece.

6. The device for online detection and control of composite microstructure array micro-molding according to claim 3, characterized in that: The elastic microporous mesh is made of nylon threads or metal threads; or, the elastic microporous mesh is a microporous mesh formed by punching holes on the surface of the material using a laser punching method.

7. The device for online detection and control of composite microstructure array micro-molding according to claim 3, characterized in that: The microstructure mold core is made of stainless steel material, ceramic material or silicon carbide material.

8. The device for online detection and control of composite microstructure array micro-molding according to claim 3, characterized in that: The aperture of the elastic microporous mesh is smaller than the surface microstructure size of the microstructure mold core; the elastic microporous mesh coated on the bottom of the microstructure mold core is in a naturally stretched state.

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