A research method for key process technology of blisk polishing

Abstract

The present invention provides a method for studying key process technologies for polishing an integral blade disc, and relates to the field of polishing process technology. The present invention includes the overall scheme design of an integral blade disc grinding and polishing robot, the research on efficient grinding and polishing processes for integral blade discs, and the development of an intelligent grinding and polishing and control system for integral blade discs. For the overall scheme design of an integral blade disc grinding and polishing robot, an aero-engine integral blade disc grinding and polishing robot integrates robot control technology, passive compliance control technology, trajectory planning and offline programming technology, including a mechanical system, an electrical system, and a software system. The present invention eliminates the tool marks remaining from blade profile CNC milling and improves the polishing quality of the integral blade disc through the development and application of robot polishing equipment.

Description

Technical Field

[0001] The invention relates to the technical field of polishing technology, and in particular to a research method for a key process technology for polishing an integral blade disk. Background Art

[0002] Aircraft engines are highly complex and sophisticated thermal machines. As the heart of an aircraft, they are not only the driving force for the flight of an aircraft, but also an important driving force for the development of aviation. Every important change in the history of human aviation is inseparable from the technological progress of aircraft engines. After more than a hundred years of development, aircraft engines have developed into mature products with extremely high reliability. The aircraft engines in use include turbojet / turbofan engines, turboshaft / turboprop engines, ramjet engines, piston engines and other types. They are not only used as power for military and civilian aircraft, drones and cruise missiles for various purposes, but also gas turbines derived from aircraft engines are widely used in ground power generation, marine power, mobile power stations, natural gas and oil pipeline pumping stations and other fields.

[0003] The integral blade disk of an aircraft engine is a thin-walled structure. Its strength, fatigue, corrosion resistance and other properties are very sensitive to scratches and thickness changes caused by grinding and polishing. In order to achieve a smooth surface with continuous transition, it is necessary to use a variety of grinding tools and repeated grinding and polishing to ensure good appearance quality after grinding and polishing.

[0004] At present, the surface polishing of integral blades in China is all done manually, which requires a lot of labor and time costs. In addition, the surface quality and size of the polished surface are affected by the differences in the workers' skill levels, resulting in uneven surface quality of parts, which can easily lead to smearing, chopping and sharp edges on the leading edge of the blade, affecting the aerodynamic performance of the integral blade. Summary of the invention

[0005] The purpose of the present invention is to develop a key process technology research method for polishing an integral blade disk, which can eliminate the tool marks remaining in the CNC milling of the blade profile and improve the polishing quality of the integral blade disk through the development and application of a robot polishing device.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for researching key process technology of blisk polishing, comprising:

[0008] Overall design of blisk grinding and polishing robot, research on efficient blisk grinding and polishing process, and development of intelligent blisk grinding and polishing measurement and control system;

[0009] Among them, for the overall design of the integral blade disc grinding and polishing robot, the aircraft engine integral blade disc grinding and polishing robot integrates robot control technology, passive compliance control technology, trajectory planning and offline programming technology, including mechanical system, electrical system and software system;

[0010] For the research on efficient grinding and polishing of integral blades, a grinding and polishing process test platform is built based on industrial robots and multifunctional end effectors to simulate the actual working conditions of grinding and polishing of integral blades. As the hardware support for subsequent basic process research, the grinding and polishing requirements of complex surfaces with different structural characteristics are considered, and the structural characteristics and working principles of various types of abrasive tools are studied. Through systematic processing performance tests, the processing performance and applicable occasions of different abrasive tools are determined, the physical properties and process characteristics of different materials are studied, and the material removal mechanism in the grinding and polishing process of integral blades is analyzed. Experimental research on efficient grinding and polishing process is carried out. Through grinding and polishing mechanism research and experimental data analysis, different The influence of processing parameters on grinding and polishing effect and efficiency, as well as the coupling effect between different processing parameters, determine the appropriate type of abrasive tool and grinding and polishing process parameters according to the removal amount, accuracy, surface quality and efficiency requirements of the grinding and polishing of integral blades of different materials, carry out grinding and polishing effect processing tests through the grinding and polishing process test platform, detect the actual grinding and polishing removal amount and grinding and polishing effect, improve the grinding and polishing process plan, overcome the key technology of automatic grinding and polishing surface removal amount precise control of complex surface difficult to process materials, sort out the grinding and polishing requirements of integral blades, formulate grinding and polishing process plans according to the grinding and polishing accuracy and quality requirements of different structures of integral blades, and form a process expert database;

[0011] For the research and development of the intelligent grinding and polishing measurement and control system for the integral blade disc, according to the hardware composition of the integral blade disc grinding and polishing operation system and the requirements of the automatic grinding and polishing process of the integral blade disc, an intelligent grinding and polishing measurement and control system for the integral blade disc grinding and polishing robot is developed to realize the integrated control of the robot grinding and polishing operation system. The intelligent grinding and polishing measurement and control system mainly realizes the information collection, diagnosis and command control based on sensor information of various sensors of the grinding and polishing robot system, and is also used to realize automatic replacement of grinding tools, grinding pressure control, electric spindle / voice coil motor control, grinding and polishing process control, vacuum cleaner control and human-computer interaction.

[0012] Optionally, the mechanical system includes a robot body, a multifunctional end effector, a fixture, a dust collecting device, an automatic tool changing device, and an inner / outer protection unit, wherein the multifunctional end effector can be quickly replaced through a quick-change joint, and the system automatically replaces the actuator according to different grinding and polishing processes and processing requirements, thereby realizing the change of grinding and polishing processing modes, and can also automatically replace worn grinding tools;

[0013] The electrical system includes system control cabinet, robot control cabinet, and pneumatic control box;

[0014] The software system includes trajectory planning and offline programming software, intelligent grinding and polishing measurement and control system, and integral blade grinding and polishing process database.

[0015] Optionally, when the grinding and polishing robot is working, first import the CAD model of the integral blade disk, use the trajectory planning and offline programming software to automatically plan the grinding and polishing trajectory, and automatically obtain the optimal process parameters according to different processes, generate an offline program executable by the robot, transfer the offline program to the robot controller, start the robot for a trial run, observe whether there are interference collisions, robot singularities, verify the correctness of the program, and after confirming that the robot executes the program correctly, clamp the integral blade disk on the workbench, start the system, and let the robot clamp the end effector to run according to the planned trajectory, and control the polishing pressure, grinding and polishing inclination angle, and feed speed in real time to realize the automatic grinding and polishing processes of rough polishing, semi-fine polishing, and fine polishing of the integral blade disk. After completing the grinding and polishing, use a surface roughness meter and a three-coordinate measuring instrument for precision inspection to ensure that the grinding and polishing quality is qualified.

[0016] Optionally, there are many factors that affect the grinding and polishing efficiency and quality during the grinding and polishing of the integral blade disc. There is a coupling relationship between the influencing factors. It is necessary to study the grinding and polishing mechanism and the influence of different grinding and polishing process parameters on the grinding and polishing quality and efficiency for different materials, and further optimize the grinding and polishing process flow and process parameters. The research content includes:

[0017] Research on the grinding and polishing process of the integral blade disk based on the grinding mechanism: The grinding and polishing process of the integral blade disk is simplified to the process of removing the material from the surface of the integral blade disk by a single abrasive. The size, morphology and distribution of the abrasive on the grinding tool will affect the surface processing quality of the integral blade disk. The influence of a single abrasive on the roughness, defects, residual stress and sub-surface damage of the integral blade disk surface during the processing is studied.

[0018] Optimization of grinding and polishing process parameters based on neural network prediction model: The process factors that affect the surface quality and efficiency of grinding and polishing include part material and curvature, abrasive material, abrasive particle size, abrasive speed, grinding force, grinding times, grinding method, and feed speed. A grinding and polishing process prediction model is established based on a neural network to predict the output results of all process parameter combinations. For indicators within a given prediction range, the corresponding process parameter combination can be quickly obtained, and the optimal process parameters can be determined based on actual conditions to form an efficient grinding and polishing process database for aviation integral blades, effectively improving the efficiency of grinding and polishing process design;

[0019] Aviation blisk grinding and polishing process database and process specifications: After theoretical analysis of the grinding and polishing mechanism, process verification experiments and process parameter optimization, a process database is established. By inputting the grinding and polishing conditions and requirements of the blisk, the optimal process parameters are automatically generated. For different material properties and blisk types, theoretical analysis and process verification are conducted to further develop blisk grinding and polishing process specifications suitable for robot automatic grinding and polishing.

[0020] Optionally, a dual master station form of industrial computer and PLC is adopted. Based on ProfiNet bus, different control objects are connected in series to one bus through PLC remote slave station to realize distributed digital control of field equipment and field communication network. The industrial computer is used as the master station to mainly realize communication with the robot control cabinet, control the robot's posture and speed, and the PLC master station program modification function. The PLC master station is used as the common master station for field servo motors, solenoid valve groups, proportional valves and other electrical controllers to realize the coordinated work of each slave station and complete the automatic grinding and polishing task.

[0021] Optionally, the research method also includes the design of a multifunctional end effector for complex free-form surface grinding and polishing. The integral blade disc profile of an aero-engine is composed of complex free-form surfaces with numerous features and complex structures. The leading and trailing edges and tenons are difficult to grind and polish. Common integral blade disc grinding and polishing equipment only performs position control during the processing process, which is prone to over-grinding, resulting in defects on the surface of the integral blade disc, causing rework or scrapping. In addition, during the grinding and polishing process, the grinding amount is one of the main factors affecting the grinding and polishing quality, and there is a strong coupling relationship between the grinding amount and the grinding pressure. Accurate control of the grinding pressure is very important and is also the core of control. The end effector should have core functions including constant control of axial / radial grinding and polishing pressure, high-speed grinding and polishing, high-frequency reciprocating grinding and polishing, grinding and polishing inclination adjustment, quick change of actuators, and automatic replacement of molds to achieve grinding and polishing of different features and ensure grinding and polishing quality and precision.

[0022] Optionally, a high-speed electric spindle can be used to achieve automatic grinding and polishing of the blade body, leading edge, trailing edge and other surfaces. For tenons and other complex features, a voice coil motor can be used to drive the mold to perform reciprocating linear motion to achieve precision grinding and polishing. A constant force controller with controllable axial force is installed at the end of the robot to control the grinding force on the normal line of the contact area between the mold and the entire blade disk, avoiding the problem of force / position mixed control requiring frequent switching between force space and position space and lack of stability.

[0023] Optionally, during the grinding and polishing process, the normal grinding force has an important influence on the grinding and polishing efficiency, quality and precision, and it needs to be precisely controlled during grinding and polishing. The constant force controller achieves precise control of the cylinder pressure by precisely controlling the servo proportional valve, and uses force sensors and displacement sensors for real-time feedback to achieve active control of high-precision, large-range single-axis grinding force. In addition, during the grinding and polishing process, the axial direction of the constant force controller should be consistent with the direction of the grinding pressure to achieve constant force control. During grinding and polishing, the reaction force of the grinding tool on the grinding tool is along the radial direction of the grinding tool, that is, the radial direction of the electric spindle. At this time, the electric spindle should be rotated 90° so that the axial direction of the constant force controller is in the same direction as the radial direction of the electric spindle, so that the direction of the grinding pressure is consistent with the axial direction of the constant force controller. Therefore, a pneumatic rotation unit is required to switch the spindle between 0° and 90°.

[0024] Optionally, the research method also includes the development of trajectory planning algorithms and offline programming software for efficient grinding and polishing of integral blades. Factors including component geometry and topology, material properties, microstructure, process requirements, and processing efficiency are comprehensively considered to establish a grinding and polishing trajectory constraint model and feature model, classify features including grinding and polishing area edges, feature edges, and geometric shape mutation positions, design a region segmentation strategy based on surface features and structural characteristics, and based on the constraint model and grinding and polishing trajectory scheme, study an intelligent grinding trajectory generation algorithm with curvature adaptation and machining allowance adaptation functions for grinding coverage, accuracy, and efficiency requirements. With the goal of improving grinding and polishing efficiency, an optimization model is established based on the grinding and polishing trajectory envelope theory. Through the overall blade grinding and polishing process experiment, the grinding and polishing trajectory-related parameters are analyzed, the optimized grinding and polishing trajectory is obtained, and the intelligent generation of robot grinding and polishing instructions is realized.

[0025] Optionally, the research method also includes system integration and application verification of high-efficiency grinding and polishing robot for integral blades. According to the process requirements of automatic grinding and polishing of integral blades, unit testing of functional components and software is carried out, mechanical interface, data integration interface and integrated control interface are established, trajectory planning and offline programming software, intelligent grinding and polishing measurement and control system, multi-functional end effector, automatic tool changing device, industrial robot and other functional subsystems are integrated with hardware and software to achieve coordinated control of various functional subsystems, design and manufacture different types of aircraft engine integral blade test pieces, carry out application verification of integral blade grinding and polishing robot, and compile relevant process specifications for automated grinding and polishing of integral blades of aircraft engines according to the operating status of the integral blade grinding and polishing robot and the experience of aircraft engine integral blade grinding and polishing engineering.

[0026] The beneficial effects of the present invention are:

[0027] The present invention utilizes the advantages of industrial robots such as high automation, strong controllability, easy expansion, strong versatility, and moderate cost, and uses industrial robots to drive the end effector to grind and polish the fixed integral blade disk. Through the development and application of robot polishing equipment, the blade profile, flow channel, leading and trailing edges, root transition and other parts of the integral blade disk are polished and polished by robots, so that the surface of the parts meets the technical indicators required by the design drawings;

[0028] Grinding and polishing trajectory planning and offline programming are the key to complex free-form surface grinding and polishing technology, which is directly related to the surface quality and processing efficiency of the integral blade disc grinding and polishing. The present invention studies the trajectory planning and offline programming technology based on CAD data, aiming to quickly and automatically generate the robot motion trajectory and motion parameters that meet the processing requirements through the integral blade disc CAD model, and generate the robot program code through post-processing. At the same time, the offline programming software also has the functions of automatic selection of process parameters and human-computer interaction;

[0029] In order to solve the problem of automated grinding and polishing of super-large integral blades, the present invention is based on the design of a passive and flexible multifunctional end-effector mechanism, precise control technology of surface removal amount during grinding and polishing of complex curved surfaces, and efficient grinding and polishing trajectory planning and offline programming technology for complex curved surfaces and material properties. This eliminates the tool marks remaining from CNC milling of blade profiles, forms a set of automated grinding and polishing equipment for integral blades of aero-engines and an advanced process database, improves the production capacity of integral blades, reduces labor costs, and promotes the innovative development of grinding and polishing of integral blades of aero-engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 The control system architecture of the blisk grinding and polishing robot;

[0032] Figure 2 Research technical routes for efficient grinding and polishing of aircraft engine blisks;

[0033] Figure 3 Planning the technical route for efficient grinding and polishing trajectory of the blisk;

[0034] Figure 4 It is the overall architecture of the intelligent grinding and polishing measurement and control system. DETAILED DESCRIPTION

[0035] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0036] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0037] The present invention discloses a research method for key process technologies for polishing an integral blade disc, including overall scheme design of an integral blade disc grinding and polishing robot, research on efficient grinding and polishing technology for integral blade discs, design of a multifunctional end effector for grinding and polishing of complex free-form surfaces, development of trajectory planning algorithms and offline programming software for efficient grinding and polishing of integral blade discs, research and development of intelligent grinding and polishing measurement and control systems for integral blade discs, and system integration and application verification of efficient grinding and polishing robots for integral blade discs.

[0038] Overall design of the blisk grinding and polishing robot

[0039] The aircraft engine integral blade grinding and polishing robot integrates advanced technologies such as robot control technology, passive compliance control technology, trajectory planning and offline programming technology, and mainly includes mechanical system, electrical system and software system.

[0040] The overall solution and control system architecture are as follows: Figure 1 As shown, the mechanical system includes the robot body, multifunctional end effector, fixture, dust collection device, automatic tool changing device, internal / external protection unit, etc. Among them, the multifunctional end effector can be quickly replaced through a quick-change joint. The system automatically replaces the actuator according to different grinding and polishing processes and processing requirements, thereby realizing the change of grinding and polishing processing mode (high-speed rotation or reciprocating motion), and can also automatically replace worn grinding tools. The electrical system includes the system control cabinet, the robot control cabinet, the pneumatic control box, etc. The software system includes trajectory planning and offline programming software, intelligent grinding and polishing measurement and control system, integral blade grinding and polishing process database, etc.

[0041] When the grinding and polishing robot is working, it first imports the CAD model of the integral blade disc, uses trajectory planning and offline programming software to automatically plan the grinding and polishing trajectory, and automatically obtains the optimal process parameters according to different processes, generates an offline program executable by the robot, and transmits the offline program to the robot controller, starts the robot for trial operation, observes whether there are interference collisions, robot singularity points and other problems, and verifies the correctness of the program; after confirming that the robot executes the program correctly, clamps the integral blade disc on the workbench, starts the system, and the robot clamps the end effector to run according to the planned trajectory, and controls the polishing pressure, grinding and polishing inclination angle, feed speed and other process parameters in real time to realize the automatic grinding and polishing processes such as rough polishing, semi-fine polishing and fine polishing of the integral blade disc. After the grinding and polishing is completed, the surface roughness meter, three-coordinate measuring instrument and other instruments are used for precision inspection to ensure the qualified grinding and polishing quality.

[0042] Research on high-efficiency grinding and polishing technology of integral blade disk

[0043] Based on industrial robots and multi-functional end effectors, a grinding and polishing process test platform is built to simulate the actual working conditions of the grinding and polishing of the integral blade disc. As the hardware support for the subsequent basic process research, the grinding and polishing requirements of complex surfaces with different structural characteristics are considered, and the structural characteristics and working principles of various types of abrasive tools are studied. Through systematic processing performance tests, the processing performance and applicable occasions of different abrasive tools are determined, the physical properties and process characteristics of different materials are studied, the material removal mechanism in the grinding and polishing process of the integral blade disc is analyzed, and efficient grinding and polishing process experiments are carried out. Through grinding and polishing mechanism research and experimental data analysis, the influence of different processing parameters on the grinding and polishing effect and efficiency, as well as the coupling effect between different processing parameters, are determined.

[0044] In combination with the above research results, according to the requirements of removal amount, precision, surface quality, efficiency, etc. of grinding and polishing of integral blades of different materials, the appropriate abrasive tool type and grinding and polishing process parameters are determined, and the grinding and polishing effect processing test is carried out through the grinding and polishing process test platform to detect the actual grinding and polishing removal amount and grinding and polishing effect, improve the grinding and polishing process plan, overcome the key technology of automatic grinding and polishing surface removal amount precise control of complex surface difficult to process materials, sort out the grinding and polishing needs of integral blades, formulate grinding and polishing process plans according to the grinding and polishing precision and quality requirements of different structures of integral blades, and form a process expert database. The technical route of research on efficient grinding and polishing process of integral blades of aircraft engines is as follows: Figure 2 shown.

[0045] There are many factors that affect the grinding and polishing efficiency and quality during the grinding and polishing process of the integral blade disc. There is a coupling relationship between the various influencing factors. It is necessary to study the grinding and polishing mechanism of different materials and the influence of different grinding and polishing process parameters on the grinding and polishing quality and efficiency, and further optimize the grinding and polishing process flow and process parameters.

[0046] ① Research on grinding and polishing process of integral blade disk based on grinding mechanism

[0047] The grinding and polishing process of the integral blisk can be simplified as the process of removing material from the surface of the integral blisk with a single abrasive. The size, morphology and distribution of the abrasive on the grinding tool will affect the surface processing quality of the integral blisk. Therefore, the influence of a single abrasive on the roughness, defects, residual stress and sub-surface damage of the surface of the integral blisk during the processing is studied.

[0048] ②Optimization of grinding and polishing process parameters based on neural network prediction model

[0049] The process factors that affect the surface quality and efficiency of grinding and polishing include part material and curvature, abrasive material, abrasive particle size, abrasive rotation speed, grinding force, number of grindings, grinding method, feed speed, etc. If a comprehensive experiment is conducted, the scale of the experiment will be very large, which is often difficult to implement due to the limitations of experimental conditions, and it is difficult to obtain the optimal process parameters through traditional statistical methods. For this reason, a grinding and polishing process prediction model is established based on a neural network, and the output results of all process parameter combinations are predicted. In this way, for indicators within a given prediction range, the corresponding process parameter combination can be quickly obtained, and the optimal process parameters can be determined based on actual conditions, forming an efficient grinding and polishing process database for aviation integral blades, which effectively improves the efficiency of grinding and polishing process design.

[0050] ③ Aviation blisk grinding and polishing process database and process specifications

[0051] After theoretical analysis of the grinding and polishing mechanism, process verification experiments and process parameter optimization, a process database is established, and the optimal process parameters are automatically generated by inputting the grinding and polishing conditions and requirements of the integral blade. According to different material properties and integral blade types, through theoretical analysis and process verification, the integral blade grinding and polishing process specifications suitable for robot automatic grinding and polishing are further formulated.

[0052] Design of multifunctional end effector for grinding and polishing of complex free-form surfaces

[0053] The integral blade surface of an aircraft engine is composed of complex free-form surfaces with numerous features and complex structures. For example, the leading and trailing edges and tenons are difficult to grind and polish. Common integral blade grinding and polishing equipment only performs position control during the processing process, which is prone to over-grinding, resulting in defects on the surface of the integral blade, causing rework or scrapping. In addition, during the grinding and polishing process, the grinding amount is one of the main factors affecting the grinding and polishing quality. There is a strong coupling relationship between the grinding amount and the grinding pressure, so accurate control of the grinding pressure is very important and is also the core of control.

[0054] To achieve automatic grinding, the end effector should have core functions such as constant control of axial / radial grinding and polishing pressure, high-speed grinding and polishing, high-frequency reciprocating grinding and polishing, grinding and polishing inclination adjustment, quick change of actuators, and automatic replacement of grinding tools, so as to achieve grinding and polishing with different characteristics while ensuring the quality and accuracy of grinding and polishing.

[0055] Traditional manual grinding uses pneumatic grinding tools to drive the mold, but pneumatic tools cannot output constant torque. If the load is too large, the linear speed of the mold will decrease. The linear speed of the mold is an important parameter in the grinding and polishing process and needs to be precisely controlled. The present invention uses a high-speed electric spindle to achieve automatic grinding and polishing of blades, leading edges, trailing edges and other surfaces. For complex features such as tenons, a voice coil motor is used to drive the mold to perform reciprocating linear motion to achieve precision grinding and polishing. The present invention adds a constant force controller with controllable axial force at the end of the robot to control the grinding force on the normal line of the contact area between the mold and the integral blade disk, avoiding the problem of frequent switching between the force space and the position space and the instability of the force / position mixed control. It has high control accuracy, fast response, and is easy to integrate, and is suitable for robots of various models.

[0056] During the grinding and polishing process, the normal grinding force has an important influence on the grinding and polishing efficiency, quality and precision, and needs to be precisely controlled during grinding and polishing. The constant force controller achieves precise control of the cylinder pressure by precisely controlling the servo proportional valve, and uses force sensors and displacement sensors for real-time feedback, which can achieve high-precision, large-range active control of single-axis grinding force. In addition, during the grinding and polishing process, the axis direction of the constant force controller should be consistent with the direction of the grinding pressure to achieve constant force control. During grinding and polishing, the reaction force of the grinding tool on the grinding tool is along the radial direction of the grinding tool, that is, the radial direction of the electric spindle. At this time, the electric spindle should be rotated 90° so that the axis direction of the constant force controller is in the same direction as the radial direction of the electric spindle, so that the direction of the grinding pressure is consistent with the axis direction of the constant force controller. Therefore, a pneumatic rotation unit is required to switch the spindle between 0° and 90°.

[0057] Development of trajectory planning algorithm and offline programming software for efficient grinding and polishing of blisks

[0058] Taking into account the geometry and topology of components, material properties, microstructure, process requirements, processing efficiency and other factors, a grinding and polishing trajectory constraint model and feature model are established. The features including the edge of the area to be ground, the feature edge, the position of geometric shape mutation, etc. are classified, and the region segmentation strategy is designed according to the surface features and structural characteristics. Based on the constraint model and grinding and polishing trajectory scheme, and aiming at the requirements of grinding coverage, accuracy, efficiency and other requirements, an intelligent grinding trajectory generation algorithm with functions such as curvature adaptation and machining allowance adaptation is studied. With the goal of improving the grinding and polishing efficiency, an optimization model is established based on the grinding and polishing trajectory envelope theory. Through the integral blade grinding and polishing process experiment, the grinding and polishing trajectory related parameters are analyzed, and the optimized grinding and polishing trajectory is obtained to realize the intelligent generation of robot grinding and polishing instructions. The technical route of efficient grinding and polishing trajectory planning for integral blades is as follows: Figure 3 shown.

[0059] Research and development of intelligent grinding and polishing measurement and control system for integral blade disk

[0060] According to the hardware composition of the integral blade grinding and polishing system and the requirements of the integral blade automatic grinding and polishing process, the intelligent grinding and polishing measurement and control system of the integral blade grinding and polishing robot is developed to realize the integrated control of the robot grinding and polishing system. The intelligent grinding and polishing measurement and control system mainly realizes the information collection, diagnosis and command control based on sensor information of various sensors of the grinding and polishing robot system. It is also used to realize the functions of automatic replacement of grinding tools, grinding pressure control, electric spindle / voice coil motor control, grinding and polishing process control, vacuum cleaner control and human-computer interaction. Its overall framework is as follows Figure 4 shown.

[0061] Due to the large number of control objects, it is difficult to provide a large number of communication interfaces and ensure the stability of the control system using a single PC industrial computer. The industrial computer + PLC dual master station form is adopted, based on the ProfiNet bus, and different control objects are connected in series to a bus through the PLC remote slave station to realize the distributed digital control and field communication network of field equipment. As the master station, the industrial computer mainly realizes communication with the robot control cabinet, controls the robot's posture, speed, and the PLC master station program modification function; the PLC master station is a common master station for electrical controllers such as on-site servo motors, solenoid valve groups, proportional valves, etc., to realize the coordinated work of each slave station and complete the automatic grinding and polishing task.

[0062] System integration and application verification of high-efficiency grinding and polishing robot for blisks

[0063] According to the process requirements of automatic grinding and polishing of integral blades, unit testing of functional components and software is carried out; mechanical interfaces, data integration interfaces and integrated control interfaces are established to realize the software and hardware integration of various functional subsystems such as trajectory planning and offline programming software, intelligent grinding and polishing measurement and control systems, multi-functional end effectors, automatic tool replacement devices, industrial robots, etc., and to achieve coordinated control of various functional subsystems. Design and manufacture different types of aircraft engine integral blade test pieces, and carry out application verification of integral blade grinding and polishing robots. According to the operating status of integral blade grinding and polishing robots and the experience of aircraft engine integral blade grinding and polishing engineering, the relevant process specifications for the automatic grinding and polishing of aircraft engine integral blades are compiled.

[0064] The above embodiments are only preferred embodiments of the present invention and are not limitations of the technical solutions of the present invention. Any technical solution that can be implemented on the basis of the above embodiments without creative work should be deemed to fall within the scope of protection of the patent of the present invention.

Claims

1. A research method for key process technology of blisk polishing, characterized in that: include: Overall design of blisk grinding and polishing robot, research on efficient blisk grinding and polishing process, and development of intelligent blisk grinding and polishing measurement and control system; Among them, for the overall design of the integral blade disc grinding and polishing robot, the aircraft engine integral blade disc grinding and polishing robot integrates robot control technology, passive compliance control technology, trajectory planning and offline programming technology, including mechanical system, electrical system and software system; For the research on efficient grinding and polishing of integral blades, a grinding and polishing process test platform is built based on industrial robots and multifunctional end effectors to simulate the actual working conditions of grinding and polishing of integral blades. As the hardware support for subsequent basic process research, the grinding and polishing requirements of complex surfaces with different structural characteristics are considered, and the structural characteristics and working principles of various types of abrasive tools are studied. Through systematic processing performance tests, the processing performance and applicable occasions of different abrasive tools are determined, the physical properties and process characteristics of different materials are studied, and the material removal mechanism in the grinding and polishing process of integral blades is analyzed. Experimental research on efficient grinding and polishing process is carried out. Through grinding and polishing mechanism research and experimental data analysis, different The influence of processing parameters on grinding and polishing effect and efficiency, as well as the coupling effect between different processing parameters, determine the appropriate type of abrasive tool and grinding and polishing process parameters according to the removal amount, accuracy, surface quality and efficiency requirements of the grinding and polishing of integral blades of different materials, carry out grinding and polishing effect processing tests through the grinding and polishing process test platform, detect the actual grinding and polishing removal amount and grinding and polishing effect, improve the grinding and polishing process plan, overcome the key technology of automatic grinding and polishing surface removal amount precise control of complex surface difficult to process materials, sort out the grinding and polishing requirements of integral blades, formulate grinding and polishing process plans according to the grinding and polishing accuracy and quality requirements of different structures of integral blades, and form a process expert database; There are many factors that affect the grinding and polishing efficiency and quality during the grinding and polishing of the integral blade. There is a coupling relationship between the influencing factors. It is necessary to study the grinding and polishing mechanism of different materials and the influence of different grinding and polishing process parameters on the grinding and polishing quality and efficiency, and further optimize the grinding and polishing process flow and process parameters. The research content includes: Research on the grinding and polishing process of the integral blade disk based on the grinding mechanism: The grinding and polishing process of the integral blade disk is simplified to the process of removing the material from the surface of the integral blade disk by a single abrasive. The size, morphology and distribution of the abrasive on the grinding tool will affect the surface processing quality of the integral blade disk. The influence of a single abrasive on the roughness, defects, residual stress and sub-surface damage of the integral blade disk surface during the processing is studied. Optimization of grinding and polishing process parameters based on neural network prediction model: The process factors that affect the surface quality and efficiency of grinding and polishing include part material and curvature, abrasive material, abrasive particle size, abrasive speed, grinding force, grinding times, grinding method, and feed speed. A grinding and polishing process prediction model is established based on a neural network to predict the output results of all process parameter combinations. For indicators within a given prediction range, the corresponding process parameter combination can be quickly obtained, and the optimal process parameters can be determined based on actual conditions to form an efficient grinding and polishing process database for aviation integral blades, effectively improving the efficiency of grinding and polishing process design; Aviation blisk grinding and polishing process database and process specifications: After theoretical analysis of the grinding and polishing mechanism, process verification experiments and process parameter optimization, a process database is established. By inputting the grinding and polishing conditions and requirements of the blisk, the optimal process parameters are automatically generated. For different material properties and blisk types, theoretical analysis and process verification are conducted to further develop the blisk grinding and polishing process specifications suitable for robot automatic grinding and polishing. For the research and development of the intelligent grinding and polishing measurement and control system for the integral blade disc, according to the hardware composition of the integral blade disc grinding and polishing operation system and the requirements of the automatic grinding and polishing process of the integral blade disc, the intelligent grinding and polishing measurement and control system for the integral blade disc grinding and polishing robot is developed to realize the integrated control of the robot grinding and polishing operation system. The intelligent grinding and polishing measurement and control system mainly realizes the information collection, diagnosis and command control based on sensor information of various sensors of the grinding and polishing robot system, and is also used to realize automatic replacement of grinding tools, grinding pressure control, electric spindle / voice coil motor control, grinding and polishing process control, vacuum cleaner control and human-computer interaction; The mechanical system includes the robot body, multifunctional end effector, fixture, dust collection device, automatic tool changing device, and internal / external protection unit. The multifunctional end effector can be quickly replaced through a quick-change joint. The system automatically replaces the actuator according to different grinding and polishing processes and processing requirements, thereby realizing the change of grinding and polishing processing modes. It can also automatically replace worn grinding tools. The electrical system includes system control cabinet, robot control cabinet, and pneumatic control box; The software system includes trajectory planning and offline programming software, intelligent grinding and polishing measurement and control system, and integral blade grinding and polishing process database; When the grinding and polishing robot is working, first import the CAD model of the integral blade disk, use the trajectory planning and offline programming software to automatically plan the grinding and polishing trajectory, and automatically obtain the optimal process parameters according to different processes, generate an offline program executable by the robot, transfer the offline program to the robot controller, start the robot for a trial run, observe whether there are interference collisions, robot singularities, verify the correctness of the program, and after confirming that the robot executes the program correctly, clamp the integral blade disk on the workbench, start the system, and let the robot clamp the end effector to run according to the planned trajectory, and control the polishing pressure, grinding and polishing inclination angle, and feed speed in real time to realize the automatic grinding and polishing processes of rough polishing, semi-fine polishing, and fine polishing of the integral blade disk. After completing the grinding and polishing, the surface roughness meter and the three-coordinate measuring instrument are used for precision inspection to ensure the grinding and polishing quality is qualified.

2. The method for researching key process technology for blisk polishing according to claim 1 is characterized in that: It adopts the dual master station form of industrial computer and PLC, based on ProfiNet bus, and connects different control objects in series to one bus through PLC remote slave station to realize the distributed digital control and field communication network of field equipment. The industrial computer is used as the master station to mainly realize the communication with the robot control cabinet, control the robot posture and speed, and the PLC master station program modification function. The PLC master station is used as the common master station for the field servo motor, solenoid valve group, proportional valve and other electrical controllers to realize the coordinated work of each slave station and complete the automatic grinding and polishing task.

3. The method for researching key process technology of blisk polishing according to claim 1 is characterized in that: This research method also includes the design of a multifunctional end effector for complex free-form surface grinding and polishing. The integral blade disc profile of an aero-engine is composed of complex free-form surfaces with numerous features and complex structures. The leading and trailing edges and tenons are difficult to grind and polish. Common integral blade disc grinding and polishing equipment only performs position control during the processing process, which is prone to over-grinding, resulting in defects on the surface of the integral blade disc, causing rework or scrapping. In addition, during the grinding and polishing process, the grinding amount is one of the main factors affecting the grinding and polishing quality, and there is a strong coupling relationship between the grinding amount and the grinding pressure. Accurate control of the grinding pressure is very important and is also the core of control. The end effector should have core functions including constant control of axial / radial grinding and polishing pressure, high-speed grinding and polishing, high-frequency reciprocating grinding and polishing, grinding and polishing inclination adjustment, quick change of actuators, and automatic replacement of molds to achieve grinding and polishing of different features and ensure grinding and polishing quality and precision.

4. The method for researching key process technology for blisk polishing according to claim 3 is characterized in that: A high-speed electric spindle is used to achieve automatic grinding and polishing of the blade body, leading edge, trailing edge and other surfaces. For tenons and other complex features, a voice coil motor is used to drive the mold to perform reciprocating linear motion to achieve precision grinding and polishing. A constant force controller with controllable axial force is installed at the end of the robot to control the grinding force on the normal line of the contact area between the mold and the integral blade disk, avoiding the problem of force / position mixed control that requires frequent switching between force space and position space and is not stable enough.

5. The method for researching key process technology for blisk polishing according to claim 4 is characterized in that: During the grinding and polishing process, the normal grinding force has an important influence on the grinding and polishing efficiency, quality and precision, and it needs to be precisely controlled during grinding and polishing. The constant force controller achieves precise control of the cylinder pressure by precisely controlling the servo proportional valve, and uses force sensors and displacement sensors for real-time feedback to achieve active control of high-precision, large-range single-axis grinding force. In addition, during the grinding and polishing process, the axial direction of the constant force controller should be consistent with the direction of the grinding pressure to achieve constant force control. During grinding and polishing, the reaction force of the grinding tool on the grinding tool is along the radial direction of the grinding tool, that is, the radial direction of the electric spindle. At this time, the electric spindle should be rotated 90° so that the axial direction of the constant force controller is in the same direction as the radial direction of the electric spindle, so that the direction of the grinding pressure is consistent with the axial direction of the constant force controller. Therefore, a pneumatic rotation unit is required to switch the spindle between 0° and 90°.

6. The method for researching key process technology for blisk polishing according to claim 1 is characterized in that: This research method also includes the development of trajectory planning algorithms and offline programming software for efficient grinding and polishing of integral blades. It comprehensively considers factors including component geometry and topology, material properties, microstructure, process requirements, and processing efficiency, establishes grinding and polishing trajectory constraint models and feature models, classifies features including grinding and polishing area edges, feature edges, and geometric shape mutation positions, designs region segmentation strategies based on surface features and structural characteristics, and studies intelligent grinding trajectory generation algorithms with curvature adaptation and machining allowance adaptation functions based on constraint models and grinding and polishing trajectory solutions in order to meet grinding coverage, accuracy, and efficiency requirements. With the goal of improving grinding and polishing efficiency, an optimization model is established based on the grinding and polishing trajectory envelope theory. Through integral blade grinding and polishing process experiments, the grinding and polishing trajectory-related parameters are analyzed, the optimized grinding and polishing trajectory is obtained, and the intelligent generation of robot grinding and polishing instructions is realized.

7. The method for researching key process technology for blisk polishing according to claim 1 is characterized in that: This research method also includes the system integration and application verification of the high-efficiency grinding and polishing robot for integral blades. According to the process requirements of automatic grinding and polishing of integral blades, unit testing of functional components and software is carried out, mechanical interfaces, data integration interfaces and integrated control interfaces are established, trajectory planning and offline programming software, intelligent grinding and polishing measurement and control systems, multi-functional end effectors, automatic tool changing devices, industrial robots and other functional subsystems are integrated with hardware and software to achieve coordinated control of various functional subsystems, design and manufacture different types of aircraft engine integral blade test pieces, carry out application verification of integral blade grinding and polishing robots, and compile relevant process specifications for automated grinding and polishing of integral blades of aircraft engines based on the operating conditions of the integral blade grinding and polishing robots and the experience of aircraft engine integral blade grinding and polishing projects.

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