A laser polishing system and method based on real-time feedback

Abstract

The application discloses a laser polishing system and method based on real-time feedback, and the system comprises a light beam emitting module, a light beam movement module, a processing module, a surface measurement module and a control module. The method utilizes the light beam emitting module to emit a processing light beam and a measurement light beam used by the system; the processing light beam and the measurement light beam pass through the light beam movement module, and always keep a fixed distance to make the same movement; the surface measurement module is utilized to acquire height information on a scanning path of a sample to be polished, and the height information is fed back to the control module in real time; the control module real-time regulates and controls corresponding laser polishing process parameters and a laser walking path in the processing module, and realizes real-time feedback processing through the computer control of the light beam emitting module, the light beam movement module and the processing module. Under the premise of ensuring the polishing quality, the application utilizes the computer-aided control technology, overcomes the problem of great difficulty in real-time monitoring in the processing, and provides a new method for surface treatment of complex 3D configuration workpieces.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser advanced manufacturing, in particular to a laser polishing system and method based on real-time feedback. BACKGROUND

[0002] Laser polishing technology is a new type of non-contact polishing technology, which has many unique advantages, such as no mechanical tool wear, high flexibility, no need for grinding and polishing agents, no need for subsequent cleaning process, conformal processing, high-speed processing of arbitrary (non-planar) geometric surfaces (~10 cm2 / s), selective processing of local micro surfaces (~μm), etc. Compared with traditional grinding polishing, it can achieve lower micro-roughness, is suitable for processing hard and brittle materials, and is green and pollution-free. At present, polishing of complex three-dimensional structure surfaces still depends on manual grinding and polishing, which is not only time-consuming but also high in labor cost and poor in repeatability. Laser polishing provides a new method for surface treatment of complex 3D workpieces, especially in the field of additive manufacturing. Similar laser-based manufacturing methods are beneficial to integrated sub-processes and reduce manufacturing and equipment costs.

[0003] At present, the commonly used monitoring means for the evolution of the molten pool in the laser polishing process are high-speed cameras, infrared cameras and pyrometers, etc. However, the change process of the molten pool generated in the laser processing process is very fast, the molten pool temperature is high, the field brightness is strong, the size and width are generally within a few millimeters, the cooling speed is very fast, and it is usually blocked by the plasma or vapor generated by the processing, which produces strong interference in the visible light to infrared band, making observation difficult and ineffective. The monitoring of the molten pool in the laser polishing process is to reveal the scientific problem of the mechanism of laser polishing. The idea of using it for real-time monitoring and feedback in the processing process and adjusting the process parameters is not easy to achieve at present, and the reasons are as follows. The laser polishing speed is usually very fast, about hundreds of millimeters per second. In this process, the collection, extraction and analysis of the molten pool topography image, and then the feedback calculation of the process parameters, and finally the adjustment of the process parameters, this process is difficult to achieve with the current technical means. Therefore, in the current field of laser polishing, it is still a problem for those skilled in the art to realize real-time monitoring and feedback control in the processing process. SUMMARY

[0004] The present application aims to overcome the shortcomings and deficiencies of the prior art, and provides a laser polishing system and method based on real-time feedback, which comprises a light beam emitting module, a light beam motion module, a processing module, a surface measurement module and a control module. The method uses the light beam emitting module to emit the processing light beam and the measurement light beam used by the system; the processing light beam and the measurement light beam pass through the light beam motion module, and always maintain a fixed distance apart to make the same motion; the measurement light beam measures the height of the workpiece surface during processing, and the height difference between the maximum height and the minimum height after filtering the surface profile is fed back to the control system once every processing light beam radius length, and the system adjusts the processing speed of the light beam in the light beam motion module according to the height difference to complete the feedback adjustment during processing. The method provides a practical solution for laser polishing of three-dimensional workpiece surfaces, overcomes the difficulty of real-time monitoring during processing under the premise of ensuring polishing quality, and provides a new method for processing of complex 3D workpiece surfaces.

[0005] In order to solve the problems existing in the prior art, the present application provides a laser polishing system based on real-time feedback, which comprises a light beam emitting module, a light beam motion module, a processing module, a surface measurement module and a control module;

[0006] The light beam emitting module comprises a processing laser, a detection laser and a corresponding laser modulation system, the processing laser emits a processing light beam, including a continuous laser and a pulsed laser; the detection laser emits a measurement light beam for the continuous laser or the pulsed laser;

[0007] The light beam motion module is divided into a galvanometer-assisted motion device and a mechanical arm-assisted motion device according to the processing parameter requirements, in the scanning process, the measurement light beam is in front of the processing light beam, the scanning direction is unidirectional scanning, and the distance apart is a fixed distance, and the measurement light beam is irradiated on the workpiece surface, and the galvanometer-assisted motion device or the mechanical arm-assisted motion device is selected according to the processing size and the scanning speed of the workpiece;

[0008] The processing module comprises a protective atmosphere chamber and a processing moving platform, the object to be polished is placed on the plane composed of x and y, and the laser light source realizes the movement in the z direction; in the polishing process, the combined movement in the x, y and z directions realizes the polishing of the surface of the three-dimensional object;

[0009] The surface measurement module comprises a echo processing unit, an information processing unit, a processor unit, a laser emission association unit and a laser reception association unit;

[0010] The control module comprises a computer and a data transmission unit, a data processing unit, a laser control sensor unit, a light beam motion control sensor unit, a processing parameter control sensor unit and a surface height measurement sensor unit.

[0011] Further, the processing motion platform is a three-coordinate high-precision moving platform.

[0012] Further, the echo processing unit in the surface measurement module receives the reflected light beam with height information, and transmits the signal of the reflected light beam with height information to the information processing unit; the information processing unit converts the signal of the reflected light beam with height information into a digital signal and stores the digital signal into the processor unit; the processor unit can realize storage or reading of data, and transmission; the digital signal with height information is transmitted to the control module for data processing; the laser emission correlation unit and the laser receiving correlation unit are connected with the light beam emission module, and are used for recording the emission and receiving states of the laser; the surface measurement module converts the time information of the light beam reflection transmission into height information during the movement of the measurement light beam, and can complete storage and transmission of data;

[0013] The computer in the control module is a hardware facility of the control module, and has a data transmission unit for receiving and transmitting information from other modules; a data processing unit for processing data information from other modules; a laser control sensor unit for monitoring and controlling the light beam emission module, a light beam movement control sensor unit for monitoring and controlling the light beam movement module, a processing parameter control sensor unit for monitoring and controlling the processing module, and a surface height measurement sensor unit for monitoring the surface measurement module; the control module transmits control instructions to the light beam emission module, the light beam movement module and the processing module, receives data information from the surface measurement, and performs real-time regulation and control on the control instructions transmitted by the emission module, the light beam movement module and the processing module

[0014] Further, the height information of the scanning path of the sample to be polished obtained by the surface measurement module is fed back to the control module in real time, the control module regulates and controls the corresponding laser polishing process parameters and laser walking path in the processing module in real time, and the computer controls the light beam movement module and the processing module to realize real-time feedback processing,

[0015] The application also provides a laser polishing method based on real-time feedback, which comprises the following steps:

[0016] S1: according to the material information and the initial surface roughness information of the sample to be polished, a polishing process strategy is initially formulated;

[0017] S2: initial process parameters of processing are set in the control module, the position of the sample in the processing system is calibrated and zeroed, and the sample is processed; in the initial processing stage, the processing light beam starts processing after the measurement light beam moves a length L, the measurement light beam stops scanning after scanning a path, and the processing light beam stops processing after processing a path;

[0018] S3: In the processing process, the processing light beam and the measuring light beam are always apart from a fixed length L, the light beam movement module drives the processing light beam and the measuring light beam to move at the same time, in the moving process, the measuring light beam measures the height of the workpiece surface, every time a fixed processing length less than L is scanned, the height data is fed back to the control module once;

[0019] S4: The control module performs data filtering processing on the height data to obtain surface profile data and surface roughness data; the surface profile data is used to plan the displacement of the laser walking in the z-axis direction within the measurement length; the surface roughness data is used to calculate the height difference Rz and divide the level, and the speed of the laser walking in the x-axis direction within the measurement length is adjusted according to the level of Rz; the control module transmits instructions to the processing module;

[0020] S5: After the laser processing light beam processes each one-way path, it returns along the original processing path, in the returning process, the measuring light beam measures the height of the processed surface and stores the height data, in the control module, after measuring the surface height of each processing path, the line roughness data is calculated, when all the line roughness data meets the processing requirements, the processing is completed, otherwise, the surface is processed multiple times.

[0021] Further, in step S1, the laser parameters and process parameters for laser polishing are determined according to the material parameters of the sample to be polished, including defocusing amount, scanning pitch, scanning path, scanning speed and scanning times.

[0022] Further, in step S3, the height of the workpiece surface is measured by the measuring light beam, and the specific method is: after the measuring light beam irradiates on the workpiece surface, the pulse signal reflected is transmitted to the echo processing unit in the surface measurement module to the laser receiving correlation unit, the information processing unit calculates the time required for the laser pulse to detect the detection object and return to the receiver, and the original height information h of the surface is calculated, stored in the processor unit, and transmitted to the control module.

[0023] Further, in step S4, the specific method for calculating the original height information h of the surface is: the information processing unit of the control module filters the height data in each processing length, provides the height information after filtering the surface profile, then extracts the maximum and minimum values of the height, and calculates the surface height difference as the original height information h.

[0024] Further, in step S4, the processing scanning path is adjusted according to the surface height difference, and the specific method is: according to the obtained original height information h , the surface profile h'' of the sample is calculated ij In the processing process, the processing moving platform h zAccording to h'' ij Up and down movement.

[0025] Further, in step S4, the height level classification criteria are: first class: Rz<10 μm; second class: 10 μm<Rz<50 μm; third class: 50 μm<Rz<320 μm.

[0026] Further, in step S5, the scanning speed is adjusted according to the surface height difference. According to the laser power, laser radius, pulse width and frequency determined in the polishing strategy of step S1, and the corresponding optimal process parameter combination, including scanning speed and scanning interval, the adjustment method of scanning speed in different surface height levels is determined. Specifically, for first class: scanning speed v 1=v0, where v0 is the initial scanning speed in the polishing process strategy initially determined in step S1; for second class: v 2=v0- Δv 1 ( Rz ) ; for third class: v 3=v0- Δv 2 ( Rz ) , where Δv 1 ( Rz ) and Δv 2 ( Rz ) are speed adjustment functions, which are proportional to the absolute value of the surface height difference.

[0027] Speed adjustment function Δv 1 ( Rz ) and Δv 2 ( Rz ) are coefficients determined by the sample material and the surface height level, where -0.2v0 Δv 1 ( Rz ) <0, -0.8v0 Δv 2 ( Rz ) <-0.2v0.

[0028] Compared with the existing laser polishing technology, the present application has the following advantages and beneficial effects:

[0029] The application provides a laser polishing system and method based on real-time feedback, which combines real-time monitoring with laser polishing technology, can realize rapid measurement by using a segmented simplified algorithm before processing a sample with a processing beam, performs high analysis and calculation on the surface of the sample to be polished, adjusts and sets differential polishing process parameters according to the local differential characteristics of the sample surface, realizes feedback adjustment movement of the processing speed and the processing path in the processing process by using a computer to assist in controlling the movement module of the beam and the processing moving platform in the processing module, finally realizes selective differential laser polishing of a three-dimensional surface, and realizes real-time measurement of the polished surface. The laser polishing method realizes a polishing method with real-time detection feedback by using computer-aided analysis and control, and realizes real-time monitoring of the surface quality after polishing, is simple to operate, low in cost, and easy to implement with current technology. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A laser polishing system flowchart of the embodiment of the application

[0031] Figure 2 A laser polishing system flowchart of the embodiment of the application

[0032] Figure 3 A laser polishing method flowchart of the embodiment of the application

[0033] Figure 4 A surface measurement module flowchart of the embodiment of the application DETAILED DESCRIPTION

[0034] To make the objects, technical solutions and advantages of the embodiments of the application clearer, the technical solutions in the embodiments of the application will be described below in conjunction with the drawings of the embodiments of the application. Obviously, the described embodiments are some but not all of the embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0035] Figure 1 A system flowchart of a laser polishing system based on real-time feedback provided by the embodiment of the application, Figure 2 A laser polishing system flowchart of a laser polishing system based on real-time feedback provided by the embodiment of the application, Figure 3 A laser polishing method flowchart of the embodiment of the application. As shown in Figure 1 、 Figure 2 、 Figure 3 The embodiment of the application provides a laser polishing system and method based on real-time feedback, which specifically comprises a beam emission module, a beam movement module, a processing module, a surface measurement module and a control module.

[0036] The light beam emitting module includes a processing laser, a detection laser and a corresponding laser modulation system. The processing laser emits a processing light beam, including a continuous laser and a pulse laser. The parameters of the continuous laser include but are not limited to: wavelength λ ranging from 1070 nm to 1090 nm, power P ranging from 1 W to 6000 W, beam radius r greater than 80 μm; the parameter range of the pulse laser includes but is not limited to: wavelength λ green light of 515-532 nm or infrared light of 1030-1090 nm, power P ranging from 1 W to 1000 W, beam radius r greater than 80 μm, pulse width τ 1 ns-500 ns, and frequency ƒ ranging from 20 kHz to 400 kHz; the detection laser emits a measurement light beam, and the parameters thereof include but are not limited to: a small-power continuous laser or a pulse laser with power of 0.1 W-1 W, beam radius r greater than 80 μm, pulse width τ 1 ns-500 ns, and frequency ƒ ranging from 20 kHz to 400 kHz.

[0037] The light beam movement module is divided into a galvanometer-assisted movement device and a mechanical arm-assisted movement device according to the processing parameter requirement. In the scanning process, the measurement light beam is irradiated on the workpiece surface at a fixed distance before the processing light beam, and the scanning direction is unidirectional scanning. When the length of the processing surface of the workpiece size is 10 cm or less, the galvanometer-assisted movement device is used to control the light beam scanning movement. When the length of the processing surface of the workpiece size is more than 10 cm and the processing speed is more than 20 mm / s, the galvanometer-assisted movement system is used to control the light beam scanning movement and the moving movement device in the processing module to move the workpiece to be processed to complete the processing surface scanning processing together. When the length of the processing surface of the workpiece size is more than 10 cm and the processing speed is 20 mm / s or less, the mechanical arm-assisted movement device is used to control the light beam scanning movement.

[0038] The processing module includes a protective atmosphere chamber and a processing moving platform. The processing moving platform is a three-coordinate high-precision moving platform. The object to be polished is placed on the plane composed of x and y, and the laser light source realizes the movement in the z direction. In the polishing process, the combined movement in the x, y and z directions realizes the polishing of the surface of the three-dimensional object.

[0039] The surface measurement module comprises an echo processing unit, an information processing unit, a processor unit, a laser emission correlation unit and a laser receiving correlation unit, which convert the time information of the light beam reflection transmission into height information during the movement of the measurement light beam; wherein the echo processing unit receives the reflected light beam with height information, and transmits its signal to the information processing unit, the information processing unit converts the reflected light beam signal with height information into a digital signal and stores it in the processor unit, the processor unit can realize data storage or reading, transmission, etc., and transmits the digital signal with height information to the control module for data processing. The laser emission correlation unit and the laser receiving correlation unit are connected with the light beam emission module, and are used to record the emission and receiving state of the laser. The surface measurement module converts the time information of the light beam reflection transmission into height information during the movement of the measurement light beam, and can complete data storage and transmission.

[0040] The control module comprises a computer and a data transmission unit, a data processing unit, a laser control sensor unit, a light beam motion control sensor unit, a processing parameter control sensor unit and a surface height measurement sensor unit, the control module transmits control instructions to the light beam emission module, the light beam motion module and the processing module, receives data information from the surface measurement and real-time regulates the control instructions transmitted by the emission module, the light beam motion module and the processing module. The computer is a hardware facility of the control module, and its data transmission unit is used to receive and transmit information from other modules; the data processing unit is used to process data information from other modules, such as performing extraction, classification, filtering, screening and other functions on the height information transmitted by the surface measurement module; the laser control sensor unit is used to monitor and control the light beam emission module, the light beam motion control sensor unit is used to monitor and control the light beam motion module, the processing parameter control sensor unit is used to monitor and control the processing module, and the surface height measurement sensor unit is used to monitor the surface measurement module.

[0041] A laser polishing method based on real-time feedback, as shown in Figure 3 The height information of the scanning path of the sample to be polished is obtained by the surface measurement module and fed back to the control module in real time, the control module real-time regulates the corresponding laser polishing process parameters and laser walking path, and the computer controls the light beam motion module and the processing module to realize real-time feedback processing, comprising the following steps:

[0042] S1: According to the material information and the initial surface roughness information of the sample to be polished, the polishing process strategy is initially formulated;

[0043] The initial laser polishing strategy is characterized by comprising the following steps:

[0044] According to the material parameters of the sample to be polished, including: melting point T m (K), boiling point Te (K), density ρ (g / cm 3 ), heat transfer coefficient k (W / (m 2 ·K), heat capacity Cp (J / (kg·K), dynamic viscosity mu (Pa·s), heat capacity at constant pressure, absorption, etc.; determine the range of power density suitable for laser processing of the material workpiece I (kW / cm 2 ); when using a pulsed laser as the processing beam, determine the range of suitable single-pulse energy density E (J / cm 2 ).

[0045] Determine the laser parameters for laser polishing, including processing power, spot size, pulse width, pulse frequency, etc., and the specific method is:

[0046] • Processing power P : According to the principle of maximizing processing efficiency, select the maximum power P max as the processing power according to the laser parameters;

[0047] • Spot radius r: Under the condition of meeting the processing power density, select the largest spot radius r;

[0048] • Pulse width tp: When using a pulsed laser as the processing beam, the pulse width is within the range of meeting the single-pulse energy density E, and is selected according to the initial surface roughness, the higher the initial surface roughness, the larger the selected pulse width;

[0049] • Pulse frequency f: Selected according to the pulse width;

[0050] Determine the process parameters for processing, including defocusing amount, scanning pitch, overlap rate, scanning path, scanning speed, scanning times, etc., and the specific method is:

[0051] • Defocusing amount H 0: Determine the defocusing amount according to the spot radius;

[0052] • Scanning pitch L s : Set the range to r / 6<Ls< r ;

[0053] • Scanning speed v : Determined according to the processing power density and initial surface roughness, and the specific way is: establish a two-dimensional micro-unit numerical model containing temperature field, flow field and velocity field, and the model size is long 2 r × high rThe model is a two-dimensional micro-element numerical model with a surface roughness of Ra0. The model input is a defined laser power density. Appropriate boundary conditions are set based on material properties. The two-dimensional micro-element numerical model is iteratively calculated using the energy conservation equation, momentum conservation equation, and mass conservation equation. The calculation stops when the surface roughness Ra0 is minimized, and the corresponding time is [time value missing]. t s The determined scan rate is: v 0=2 r / t s .

[0054] • Number of scans N According to the required surface roughness Ra _Required If the required surface roughness cannot be obtained in one scan, the number of scans is increased until the requirement is met.

[0055] • Scanning path: determined based on the three-dimensional morphology of the sample surface, and the spacing between paths is determined by the scanning spacing.

[0056] S2: Set the initial process parameters in the control system, calibrate and initialize the position in the processing system, and process the sample. Initially, the processing beam starts processing after the measuring beam moves a length of L. The measuring beam stops scanning after each path is completed, and the processing beam stops processing after completing each path.

[0057] S3: During the processing, the processing beam and the measuring beam are always separated by a fixed length L. The beam motion module drives the processing beam and the probe beam to move simultaneously. During the movement, the measuring beam measures the height of the workpiece surface. Every time a fixed processing length less than L is scanned, the height data is fed back to the control module.

[0058] Figure 4 This is a simplified diagram of the surface measurement module according to an embodiment of the present invention. The measuring beam measures the height of the workpiece surface, such as... Figure 4 As shown, the specific method is as follows: A laser (such as a continuous-wave HeNe laser) emits a laser beam, which is then re-collimated using an adjustable lens and enters a beam splitter. The beam is split into a reference beam and a measurement beam. The measurement beam illuminates the workpiece surface, and the reflected beam is reflected back to the beam splitter and passes through a pair of cylindrical lenses before being placed on a charge-coupled device (CCD). The emitted laser, such as HeNe, displays images at different positions on the CCD based on the distance between the beam and the workpiece surface, thereby determining the height change of the workpiece surface. This measurement accuracy can reach sub-nanometer levels. With a measurement repeatability of 1 μm, the single height measurement range can reach 10 mm, and the continuous displacement measurement height can reach tens of millimeters.

[0059] In the actual measurement process, the laser beam is split into a column of i-beam beam matrix, in the process of laser walking, multiple pulses are emitted, a set of height matrix H0 is obtained through the processing unit, after removing the system measurement error and the reference height, a set of original height data matrix H of the measured surface is obtained:

[0060] H = (H1, H2, …, H i ) T ;

[0061] Wherein: H1= ( h 11 , h 12 , …, h 1j ), H2= ( h 21 , h 22 , …, h 2j ), …, H i = ( h i1 , h i2 , …, h ij ), respectively, the height value of each beam of the split measurement beam on the walking track.

[0062] In order to improve the data processing efficiency of the system, the height information is fed back to the control module once after each scanning of the machining length;

[0063] S4: the control module carries out data filtering processing on the height data to obtain surface profile data and surface roughness data; the displacement of the laser walking in the z-axis direction within the measurement length is planned according to the surface profile data, and the speed of the laser walking in the x-axis direction within the measurement length is planned according to the surface roughness data; the control module transmits instructions to the machining module.

[0064] Calculate the surface height difference, the specific method is: the control module carries out filtering processing on the height data H within each machining length, and provides the height information H of the filtered surface profile ’ , that is:

[0065] H ’ = (H ’ 1,H ’ 2, …,H ’ i );

[0066] Wherein: H1 ’ =( h ’ 11, h ’ 12 , …, h ’ 1j ), H ’ 2= (H h ’ 21 , h ’ 22 , …, h ’ 2j ), …, H ’ i = (H h ’ i1 , h ’ i2 , …, h ’ ij ),

[0067] Then the maximum and minimum of height are extracted:

[0068] h max = MAX(H ’ );

[0069] h min = MIN(H ’ );

[0070] The surface height difference is calculated:

[0071] Rz = h max - h max ;

[0072] The surface height is divided into levels, and the height level division standard is:

[0073] First class: Rz<10 μm;

[0074] Second class: 10 μm<Rz<80 μm;

[0075] Third class: 80 μm<Rz<320 μm.

[0076] According to the surface height difference, the scanning speed is adjusted, and the specific method is: according to the laser power, laser radius, pulse width and frequency determined in the initial polishing strategy, and the corresponding optimal process parameter combination, including scanning speed and scanning spacing, the adjustment method of scanning speed in different surface height levels is formulated, which is:

[0077] First class: scanning speed: v1 = v0, no adjustment;

[0078] Second class: scanning speed: v 2 = v0- Δv 1 ( Rz ) ;

[0079] Third class: v 3 = v0- Δv 2 ( Rz ) , wherein Δv( Rz ) is a speed adjustment function, -0.2 v 0< Δv 1 ( Rz ) <0, -0.8 v 0< Δv 2 ( Rz ) <-0.2 v 0; Δv( Rz ) is proportional to the absolute value of the surface height difference, and the coefficient is determined by the sample material and the surface height level, and the higher the surface height level, the slower the speed.

[0080] According to the surface profile data, the displacement of the laser walking in the z-axis direction within the measurement length is planned, and the specific method is: according to the obtained original height data matrix H, the surface profile of the sample is calculated, and the specific calculation method is:

[0081] The height matrix data is filtered to leave only the low-frequency data of the height data, and the roughness data of the surface is filtered out to obtain the surface profile data matrix H'':

[0082] According to the surface height difference, the machining scanning path is regulated, and the specific method is:

[0083] H '' s = (H '' 1s ,H '' 2s , …,H '' is );

[0084] Wherein: H '' 1s =( h ’’ 11 , h ’’ 12 , …, h ’’ 1j ), H2s '' =( h ’’ 21 , h ’’ 22 , …, h ’’ 2j ),…,H is '' =( h ’’ i1 , h ’’ i2 , …, h ’’ ij ),

[0085] In the processing process, the processing moving platform in the processing module h z According to h ’’ ij Up and down movement.

[0086] S5: After processing each one-way path, the laser processing beam returns along the original processing path, and in the process of returning, the measurement beam measures the height of the processed surface and stores the height data. In the control module, after measuring the surface height of each processing path, the line roughness data is calculated. When all the line roughness data meets the processing requirements, the processing is completed, otherwise, the surface is processed multiple times.

[0087] The processing module specifically comprises a three-coordinate high-precision moving platform, a rotating holding device, and a corresponding computer control system in the control module.

[0088] During processing, the sample to be polished is placed on the plane composed of x and y of the three-coordinate high-precision moving platform, and this plane can move on the x, y, and z planes; the movement in the x and y directions is mainly to assist the beam movement module in scanning processing of large-size samples; the movement in the z direction is to adjust the processing scanning path according to the surface height difference, so as to realize scanning processing of three-dimensional surfaces.

[0089] It should be understood that the above description of the preferred embodiments is more detailed, and therefore should not be considered as limiting the scope of patent protection of the present application. Those skilled in the art can make substitutions or modifications without departing from the scope of the claims, and all such substitutions or modifications fall within the scope of the present application. The scope of protection of the present application should be subject to the appended claims.

Claims

1. A laser polishing method based on real-time feedback, characterized in that: Laser polishing is performed based on a real-time feedback laser polishing system, which includes: a beam emission module, a beam motion module, a processing module, a surface measurement module, and a control module. The beam emitting module includes a processing laser, a probe laser, and a corresponding laser modulation system. The processing laser emits a processing beam, including a continuous laser and a pulsed laser. The probe laser is either a continuous laser or a pulsed laser that emits a measurement beam. The beam motion module is divided into a galvanometer-assisted motion device and a robotic arm-assisted motion device according to the processing parameter requirements. During the scanning process, the measuring beam is ahead of the processing beam, the scanning direction is unidirectional, and they are separated by a fixed distance, illuminating the surface of the workpiece. The galvanometer-assisted motion device or the robotic arm-assisted motion device is selected according to the processing size of the workpiece and the scanning speed. The processing module includes a protective atmosphere chamber and a processing moving platform. The object to be polished is placed on the plane formed by its x and y axes. The laser light source moves in the z direction. During the polishing process, the combined motion in the x, y, and z directions achieves the polishing of the three-dimensional object surface. The surface measurement module includes an echo processing unit, an information processing unit, a processor unit, a laser emission correlation unit, and a laser receiving correlation unit; The control module includes a computer and data transmission unit, a data processing unit, a laser control sensor unit, a beam motion control sensor unit, a processing parameter control sensor unit, and a surface height measurement sensor unit. The height information along the scanning path of the sample to be polished is obtained in real time by the surface measurement module and fed back to the control module. The control module adjusts the corresponding laser polishing process parameters and laser path in the processing module in real time, and the real-time feedback processing is achieved by controlling the beam motion module and the processing module through computer control. The method includes the following steps: S1: Based on the material information and initial surface roughness information of the sample to be polished, a preliminary polishing process strategy is formulated; S2: Set the initial process parameters in the control module, calibrate and zero the sample position in the processing system, process the sample. In the initial stage of processing, the processing beam starts processing after the measuring beam moves by a length of L. The measuring beam stops scanning after scanning one path, and the processing beam stops processing after processing one path. S3: During the processing, the processing beam and the measuring beam are always separated by a fixed length L. The beam motion module drives the processing beam and the measuring beam to move simultaneously. During the movement, the measuring beam measures the height of the workpiece surface. Every time a fixed processing length less than L is scanned, the height data is fed back to the control module. S4: The control module performs data filtering on the height data to obtain surface contour data and surface roughness data; based on the surface contour data, it plans the displacement of the laser in the z-axis direction within the measurement length; based on the surface roughness data, it calculates the height difference Rz and classifies it into levels; based on the level of Rz, it adjusts the speed of the laser in the x-axis direction within the measurement length; the control module transmits the instructions to the processing module. S5: After processing each unidirectional path, the laser processing beam returns along the original processing path. During the return process, the measuring beam measures the height of the processed surface and stores the height data. In the control module, after measuring the surface height on each processing path, the line roughness data is calculated. When all line roughness data meet the processing requirements, the processing ends; otherwise, the surface is processed multiple times.

2. The laser polishing method based on real-time feedback according to claim 1, characterized in that: The machining moving platform is a three-axis high-precision moving platform.

3. The laser polishing method based on real-time feedback according to claim 1, characterized in that: The echo processing unit in the surface measurement module receives the reflected beam carrying height information and transmits its signal to the information processing unit. The information processing unit converts the reflected beam signal carrying height information into a digital signal and stores it in the processor unit. The processor unit can store or retrieve data, as well as transmit it, and transmit the digital signal carrying height information to the control module for data processing. The laser emission correlation unit and the laser reception correlation unit are connected to the beam emission module and are used to record the emission and reception status of the laser. During the measurement of the beam movement, the surface measurement module converts the time information of the beam reflection transmission into height information and can complete the data storage and transmission. The computer in the control module is the hardware facility of the control module. Its data transmission unit is used to receive and transmit information from other modules; the data processing unit is used to process data information from other modules; the laser control sensor unit is used to monitor and control the beam emission module; the beam motion control sensor unit is used to monitor and control the beam motion module; the processing parameter control sensor unit is used to monitor and control the processing module; and the surface height measurement sensor unit is used to monitor the surface measurement module. The control module transmits control commands to the beam emission module, the beam motion module, and the processing module, receives data information from the surface measurement module, and performs real-time adjustment of the control commands transmitted by the emission module, the beam motion module, and the processing module.

4. The laser polishing method based on real-time feedback according to claim 1, characterized in that, In step S1, the laser parameters and process parameters for laser polishing are determined based on the material parameters of the sample to be polished, including defocusing amount, scanning spacing, scanning path, scanning speed, and number of scans.

5. The laser polishing method based on real-time feedback according to claim 1, characterized in that, In step S3, the measuring beam measures the height of the workpiece surface. Specifically, after the measuring beam irradiates the workpiece surface, the pulse signal is reflected and transmitted to the echo processing unit in the surface measurement module and then to the laser receiving association unit. The information processing unit calculates the time required for the laser pulse to detect the object and return to the receiver, thereby calculating the original surface height information h, storing it in the processor unit, and transmitting it to the control module.

6. The laser polishing method based on real-time feedback according to claim 5, characterized in that, In step S4, the specific method for calculating the original surface height information h is as follows: the information processing unit of the control module performs filtering processing on the height data within each processing length, provides the height information after filtering the surface contour, and then extracts the maximum and minimum height values, and calculates the surface height difference as the original height information h.

7. The laser polishing method based on real-time feedback according to claim 6, characterized in that, In step S4, the processing scanning path is adjusted according to the surface height difference. Specifically, this is done by adjusting the original height information obtained. h Calculate the surface profile h'' of the sample. ij During the processing, the processing mobile platform in the processing module is based on h'' ij Up and down movement.

8. The laser polishing method based on real-time feedback according to claim 1, characterized in that, In step S4, the height classification criteria are as follows: Grade 1: Rz < 10 μm; Grade 2: 10 μm < Rz < 50 μm; Grade 3: 50 μm < Rz < 320 μm.

9. The laser polishing method based on real-time feedback according to claim 1, characterized in that, Step S5 further includes adjusting the processing scanning speed based on the surface height difference. Specifically, based on the laser power, laser radius, pulse width, and frequency determined in the polishing strategy established in step S1, and the corresponding optimal process parameter combination, including scanning speed and scanning spacing, a method for adjusting the scanning speed within different surface height levels is formulated. Specifically: Level 1: Scanning speed... v 1 = v0 not adjusted, where v0 is the initial scanning speed in the preliminary polishing process strategy defined in S1; Second class: v 2=v0- Δv 1; Third Class: v 3=v0- Δv 2, of which Δv 1 and Δv Both are velocity adjustment functions, proportional to the absolute value of the surface height difference; velocity adjustment function Δv 1 and Δv The coefficient 2 is determined by both the sample material and the surface height grade, where -0.2v0 < Δv 1<0, -0.8v0< Δv 2 < -0.2v0.

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