This article focuses on the research progress of gear high-efficiency precision grinding processing and surface integrity control technology. It begins with an introduction to the importance of gears in mechanical transmission systems and the increasing demands for high-quality, high-precision, and high-reliability gears in various industries. Grinding technology is crucial for gear manufacturing, but it faces challenges such as large grinding forces, high grinding temperatures, and difficult control of surface quality. The article then delves into different aspects of gear grinding technology, including grinding methods, material removal mechanisms, high-efficiency grinding research, precision grinding research, surface integrity research, and multi-energy field composite manufacturing technology. Finally, it summarizes the current research status and looks forward to future trends in gear grinding technology.
1. Introduction
Gears are fundamental components in mechanical transmission systems, widely used in aviation, shipping, vehicle, and other industries. With the development of industrial technology and the progress of aviation and aerospace fields, the requirements for transmission systems have become more stringent, leading to higher demands for gear processing in terms of quality, precision, and reliability. However, compared with international advanced levels, there are still gaps in China’s gear processing technology, such as inconsistent digitalization of machine tools, lower precision, and differences in processing methods and tool materials. Grinding, as a key method for precision processing of gears and other critical parts, offers unique advantages in machining difficult-to-process materials and ensuring gear accuracy and surface quality.
2. Gear Grinding Technology
2.1 Gear Grinding Processing Methods
2.1.1 Generation Grinding
Generation grinding controls the gear tooth profile and pitch through the generating motion of the grinding wheel. It has the advantages of high precision, high efficiency, and adjustable accuracy. However, it requires high-precision equipment and technology, and has high processing difficulty and production costs. For example, YU et al. studied the generation grinding of involute helical gears and analyzed the relationship between tooth surface distortion and gear parameters. CAO et al. proposed an adaptive design model for bevel gear generation grinding on a common gear grinder.
2.1.2 Form Grinding
Form grinding forms the gear tooth profile through the shape and motion trajectory of the grinding wheel. It has the advantages of high precision, good surface quality, and a wide range of applicable processing. In the form grinding process, the grinding wheel wears slowly, and the grinding efficiency is high. However, it usually requires a longer processing time for large or complex gears. Ding Guolong et al. established a contact model between the grinding wheel surface and the gear surface to solve the efficiency and accuracy problems in gear form grinding.
2.2 Gear Grinding Material Removal Mechanism Research
Researchers have studied the material removal mechanism during gear grinding through methods such as processing experiments, finite element simulations, and mathematical modeling. The research mainly focuses on grinding force, grinding temperature, material removal mechanism, and generated surface quality. For example, KRUSZYNSKI studied the thermal model of the gear grinding process in 1994. YI et al. established a three-dimensional heat source model for gear tooth profile grinding and further developed a residual stress finite element model.
3. Gear High-Efficiency Precision Grinding Processing Research Status
3.1 High-Efficiency Grinding
3.1.1 High-Speed Grinding
High-speed grinding uses a high-speed rotating grinding wheel for gear grinding. It has higher processing speed and efficiency compared to traditional grinding methods. It can quickly remove materials, reduce the heat-affected area, shorten the processing cycle, and improve production efficiency. EMURA et al. used a CBN grinding wheel and a high-speed CNC gear grinder to conduct experiments, and developed a synchronous controller for a high-productivity NC gear grinder.
3.1.2 Superhard Material Grinding Wheel Grinding
With the development of superhard materials, superhard material grinding wheels are widely used in grinding high-strength and high-hardness parts. The main superhard abrasives used for grinding are synthetic diamond and cubic boron nitride (CBN). CBN abrasives are ideal for grinding high-hardness iron-based materials due to their good chemical inertness with iron group elements, high thermal diffusivity, and high hardness. For example, in 1992, Fang Qixian et al. compared the grinding quality of CBN and corundum grinding wheels on carburized gears.
3.2 Precision Grinding
3.2.1 Grinding Force Research
Grinding force is an important parameter in the gear grinding process, affecting the stability of the grinding process, tool life, and processing accuracy. Many factors influence the magnitude and distribution of grinding force, such as cutting parameters, tool geometry, grinding fluid, and workpiece material. Researchers have established various models and conducted experimental analyses to study grinding force. For example, BOGDAN et al. analyzed the influence of gear grinding kinematics and grinding conditions on grinding force and established a relationship model.
3.2.2 Grinding Temperature Research
The generation and transfer of grinding heat in the gear grinding process are very complex. High grinding temperatures can cause problems such as thermal cracks, oxidation, and decreased surface quality on the workpiece surface, as well as accelerate the wear of the grinding wheel. Scholars have studied methods to control grinding temperature, such as using 微量润滑技术 (minimum quantity lubrication technology) and developing new temperature control processes. For example, WANG et al. studied the influence of grinding process parameters and cooling coefficients on the temperature field distribution of gear materials and derived a temperature model matrix.
4. Gear Grinding Surface Integrity Research Status
4.1 Grinding Residual Stress
Grinding residual stress is formed by the coupling of grinding force and grinding temperature during the gear grinding process. Residual stress can affect the life and fatigue strength of gears. Appropriate residual stress states can improve the anti-fatigue, corrosion resistance, and deformation resistance of parts. BALART et al. conducted grinding experiments on four types of hardened steels and detected the distribution of grinding surface residual stress.
4.2 Grinding Surface Topography
The grinding surface topography has an important impact on the surface integrity and service performance of gears. A good surface topography can reduce wear during meshing, improve transmission efficiency, and reduce friction noise and vibration. NOVOVIC et al. studied the influence of different processing parameters and processes on the surface topography and integrity of workpieces.
4.3 Grinding Surface Microhardness
The microhardness of the grinding surface is directly related to the surface quality of gears. Generally, a higher microhardness indicates better surface quality, less friction, and wear, and thus higher transmission efficiency and service life. WANG et al. studied the microhardness of 20CrMnTi steel gears ground by a microcrystal corundum grinding wheel.
5. Gear Multi-Energy Field Composite Manufacturing Technology
5.1 Electrochemical Composite Manufacturing
Electrochemical composite manufacturing combines electrochemical reactions with mechanical processing to achieve rapid, precise, and controllable material processing. It has the potential to replace traditional gear precision processing methods. For example, PANG Guibing et al. used electrochemical methods for the mechanical finishing of cylindrical gears and studied the influence of process parameters on gear accuracy and surface roughness.
5.2 Laser Composite Manufacturing Technology
Laser composite manufacturing technology combines laser processing and mechanical processing to manufacture high-precision and high-quality parts. It can change the microstructure and properties of materials and achieve heat treatment processes such as quenching, tempering, and carburizing on the gear surface. For example, BAO Zhijun used laser cladding to repair gears and optimized the laser processing parameters to solve the problem of uneven heat distribution.
5.3 Ultrasonic Vibration-Assisted Processing
Ultrasonic vibration-assisted grinding combines ordinary grinding with ultrasonic vibration to improve the grinding environment, extend tool life, and obtain better surface quality. For example, VENKATESH G et al. studied the ultrasonic-assisted abrasive flow finishing of bevel gears and established a three-dimensional finite element model.
6. Conclusion and Outlook
6.1 Conclusion
Grinding is an important method for precision processing of gears. Research on gear high-efficiency precision grinding processing technology mainly focuses on grinding force, grinding temperature, grinding wheel wear, process parameter optimization, grinding surface topography, surface integrity, and finite element analysis. Different grinding methods have their own advantages. High-efficiency grinding methods such as high-speed grinding and superhard material grinding wheels can improve grinding efficiency and quality. Grinding force and grinding temperature are important parameters affecting the grinding process. Surface integrity indicators such as grinding residual stress, surface topography, and surface microhardness play a crucial role in gear performance.
6.2 Outlook
In the future, the development trends of gear grinding technology may include: developing new grinding wheels with high precision and good wear resistance to adapt to new materials and processing requirements; further studying gear multi-energy field composite manufacturing technology to achieve better quality control; and developing high-performance gear grinding machines with advanced sensors, automation control systems, and cooling technologies to improve production efficiency and workpiece quality.
In conclusion, continuous research and innovation in gear grinding technology are essential to meet the increasing demands for high-performance gears in various industries.
7. Detailed Analysis of Gear Grinding Methods
7.1 Generation Grinding in Depth
Generation grinding is a sophisticated technique that relies on the precise movement of the grinding wheel to generate the gear tooth profile. This method demands high-precision machinery and a deep understanding of gear geometry and kinematics. For instance, in the study of YU et al., the approximation model for involute helical gears not only considered the flank twist but also provided valuable insights into how gear parameters influence the tooth side processing accuracy. This shows that any deviation in gear parameters can have a significant impact on the final product quality.
Moreover, the research by CAO et al. on beveloid gears highlights the complexity and adaptability of generation grinding. Their proposed continuous generating grinding method and the associated analysis of grinding characteristics demonstrate the need for a comprehensive understanding of the gear grinding process. By establishing a general mathematical model, they were able to evaluate the impact of various factors such as worm wheel dressing on the grinding accuracy. This indicates that even minor adjustments in the grinding process can lead to substantial improvements in gear quality.
7.2 Form Grinding: Advantages and Challenges
Form grinding, on the other hand, offers its own set of benefits and challenges. The ability of the grinding wheel to directly shape the gear tooth profile results in high precision and excellent surface quality. However, as seen in the research of Ding Guolong et al., ensuring that there is no interference between the grinding wheel and the gear during the process is crucial. Their contact model between the grinding wheel surface and the gear surface serves as a valuable tool for predicting and preventing such interferences.
Furthermore, the work of 李彦 et al. on addressing tooth surface distortion in form grinding emphasizes the importance of quantifying and minimizing errors. By establishing an error model and optimizing the grinding wheel dressing parameters, they were able to improve the accuracy of the gear tooth profile. This shows that continuous monitoring and adjustment of the form grinding process are essential for achieving high-quality gears.
8. Material Removal Mechanism: A Closer Look
8.1 Thermal Aspects of Material Removal
The study of the material removal mechanism during gear grinding is incomplete without a detailed understanding of the thermal aspects. KRUSZYNSKI’s early work on the thermal model of the gear grinding process laid the foundation for subsequent research. His analysis of the power density distribution at the wheel – workpiece interface provided a basis for calculating the temperature distribution during grinding.
Subsequent research by LISCHENKO et al. through finite element simulations further enhanced our understanding of the temperature field in gear grinding. Their 2D/3D temperature field calculations and discussions on the accuracy of the simulation results have been instrumental in validating theoretical models. For example, in the case of involute gear grinding, YI et al.’s establishment of a three – dimensional heat source model based on the principle of heat source superposition was a significant step forward. This model, along with the subsequent development of a residual stress finite element model, allowed for a more comprehensive analysis of the thermo – mechanical effects during gear grinding.
8.2 Influence of Gear Geometry and Material Properties
In addition to thermal factors, the geometry of the gear and the properties of the material being ground also play a crucial role in the material removal mechanism. Different gear geometries, such as helical gears, bevel gears, and worm gears, present unique challenges and opportunities for material removal. For example, the research on worm wheel grinding of end face gears by GUO et al. involved the establishment of a finite element model for the grinding temperature field, taking into account the specific geometry of the worm wheel and the end face gear.
The material properties, such as hardness, toughness, and microstructure, also affect the grinding process. Harder materials generally require more energy for material removal and can lead to higher grinding forces and temperatures. Understanding these relationships is essential for optimizing the grinding process and achieving high-quality surface finishes.
9. High-Efficiency Grinding: Key Technologies and Innovations
9.1 High-Speed Grinding: Principles and Applications
High – speed grinding has emerged as a key technology for improving the efficiency of gear grinding. The principle behind high – speed grinding lies in the ability of a high – speed rotating grinding wheel to quickly remove material with less heat generation. This is achieved through a combination of factors such as increased cutting speeds, optimized feed rates, and advanced cooling systems.
EMURA et al.’s experiments with CBN grinding wheels and high – speed CNC gear grinders demonstrated the potential of high – speed grinding. By increasing the rotational speeds of the grinding spindle and the work spindle, they were able to significantly improve the production efficiency of the gear grinding process. The development of a synchronous controller for a high – productivity NC gear grinder further enhanced the control and precision of the process.
In addition to improving efficiency, high – speed grinding also offers benefits in terms of reduced heat – affected zones and improved surface quality. The rapid material removal reduces the time during which the workpiece is exposed to high temperatures, thereby minimizing thermal damage and resulting in a better surface finish.
9.2 Superhard Material Grinding Wheels: Properties and Performance
Superhard material grinding wheels, particularly those made with CBN, have revolutionized the gear grinding process. The unique properties of CBN, such as its high hardness, good chemical inertness with iron group elements, and high thermal diffusivity, make it an ideal abrasive for grinding high – hardness iron – based materials.
The research by various scholars has demonstrated the superior performance of CBN grinding wheels compared to traditional abrasives. For example, the comparison by Fang Qixian et al. between CBN and corundum grinding wheels on carburized gears showed that CBN wheels resulted in lower grinding temperatures, larger surface residual compressive stresses, and a shallower surface metamorphic layer. These factors contribute to improved gear quality and longer service life.
Furthermore, the development of different types of CBN grinding wheels, such as electroplated, sintered, resin – bonded, and ceramic – bonded, has provided a wide range of options for different grinding applications. Each type of wheel has its own set of properties and performance characteristics, as summarized in Table 1. Understanding these differences is crucial for selecting the appropriate grinding wheel for a specific gear grinding task.
10. Precision Grinding: Achieving Optimal Surface Quality
10.1 Grinding Force: Modeling and Control
Grinding force is a critical factor in achieving precision in gear grinding. The accurate prediction and control of grinding force are essential for maintaining the stability of the grinding process, prolonging tool life, and ensuring high processing accuracy.
Researchers have developed various models to understand and predict grinding force. BOGDAN et al.’s model, which takes into account the gear grinding kinematics and grinding conditions, provides a comprehensive understanding of the relationship between grinding force and the grinding process. Other models, such as those developed by et al. and BRECHER et al., have also contributed to our understanding of grinding force through different approaches.
In addition to modeling, control strategies for grinding force have also been explored. These include optimizing grinding parameters such as cutting speed, feed rate, and grinding depth, as well as selecting the appropriate grinding wheel geometry and using suitable grinding fluids. By implementing these control strategies, it is possible to reduce the magnitude and variability of grinding force, thereby improving the precision of the gear grinding process.
10.2 Grinding Temperature: Impact and Mitigation
Grinding temperature has a significant impact on the surface quality and integrity of gears. High grinding temperatures can lead to thermal cracks, oxidation, and a decrease in surface hardness, which in turn can affect the gear’s performance and service life.
To mitigate the effects of high grinding temperatures, researchers have developed various strategies. One approach is to use advanced cooling techniques such as (minimum quantity lubrication technology). This technology reduces the heat flow density at the heat source by supplying a small amount of biodegradable lubricant to the cutting zone. Another strategy is to develop new temperature control processes, such as nano – enhanced bio – lubricant minimum quantity lubrication and low – temperature assisted minimum quantity lubrication. These processes aim to further reduce the grinding temperature and improve the surface quality of gears.
In addition to cooling techniques, accurate prediction of the temperature field distribution during gear grinding is also crucial. By developing accurate temperature models, such as those by WANG et al. and SU et al., it is possible to understand the impact of grinding process parameters on the temperature field and take appropriate measures to control the temperature.
11. Surface Integrity: The Key to Gear Performance
11.1 Grinding Residual Stress: Formation and Effects
Grinding residual stress is an important aspect of surface integrity in gear grinding. It is formed as a result of the coupling of grinding force and grinding temperature during the grinding process. Residual stress can have a significant impact on the life and fatigue strength of gears.
Excessive residual tensile stress can lead to deformation of the gear, reducing its strength and service life. On the other hand, residual compressive stress can improve the anti – fatigue performance and strength of the gear. BALART et al.’s research on grinding experiments of hardened steels demonstrated the importance of understanding the formation mechanism of residual stress. By monitoring the grinding temperature and analyzing the mechanical and thermal plastic deformation, they were able to determine the factors contributing to the formation of residual tensile stress.
11.2 Grinding Surface Topography: Importance and Optimization
The grinding surface topography also plays a crucial role in the surface integrity and performance of gears. A good surface topography can reduce wear during meshing, improve transmission efficiency, and reduce friction noise and vibration.
NOVOVIC et al.’s research on the effect of machined topography and integrity on fatigue life highlighted the importance of considering surface topography in gear design and manufacturing. By understanding the relationship between different processing parameters and surface topography, it is possible to optimize the grinding process to achieve a desired surface topography.
For example, DING et al.’s work on a tooth surface topography correction method for hypoid gears demonstrated the potential for improving surface topography through nonlinear analysis and model – based optimization. By establishing a general model and using the least squares method to solve the nonlinear target function, they were able to achieve a more controllable and practical approach to surface topography correction.
11.3 Grinding Surface Microhardness: Relationship with Gear Quality
The microhardness of the grinding surface is directly related to the surface quality of gears. A higher microhardness generally indicates better surface quality, less friction, and wear, and thus higher transmission efficiency and service life.
WANG et al.’s research on the microhardness of 20CrMnTi steel gears ground by a microcrystal corundum grinding wheel demonstrated the relationship between microhardness and different factors such as the microstructure of the surface layer. By understanding these relationships, it is possible to optimize the grinding process to achieve a desired microhardness and improve the overall quality of gears.
12. Multi – Energy Field Composite Manufacturing Technology: Future Directions
12.1 Electrochemical Composite Manufacturing: Potential and Limitations
Electrochemical composite manufacturing combines electrochemical reactions with mechanical processing to achieve rapid, precise, and controllable material processing. This technology has the potential to replace traditional gear precision processing methods in some cases.
PANG Guibing et al.’s work on electrochemical mechanical finishing of cylindrical gears demonstrated the benefits of this technology in terms of improving surface roughness and gear accuracy. However, like any technology, electrochemical composite manufacturing also has its limitations. For example, the need for a suitable electrolyte and the control of electrochemical reactions can be challenging in some applications.
Future research in this area could focus on improving the efficiency and controllability of electrochemical composite manufacturing, as well as exploring its application in more complex gear geometries and materials.
12.2 Laser Composite Manufacturing Technology: Advancements and Applications
Laser composite manufacturing technology combines laser processing and mechanical processing to manufacture high – precision and high – quality parts. This technology has seen significant advancements in recent years, particularly in the area of gear manufacturing.
BAO Zhijun’s work on laser cladding repair of gears demonstrated the potential of this technology for repairing damaged gears. By optimizing the laser processing parameters and controlling the heat distribution, it is possible to achieve a high – quality repair. In addition, the research by 王志坚 et al. on laser remanufacturing of parts showed that laser composite manufacturing technology can be used to control the geometric characteristics and shaping accuracy of formed parts.
Future research could focus on further improving the precision and quality of laser composite manufacturing, as well as exploring its application in new gear designs and manufacturing processes.
12.3 Ultrasonic Vibration – Assisted Processing: Benefits and Future Trends
Ultrasonic vibration – assisted grinding combines ordinary grinding with ultrasonic vibration to improve the grinding environment, extend tool life, and obtain better surface quality. This technology has been widely used in gear manufacturing in recent years.
VENKATESH G et al.’s work on ultrasonic – assisted abrasive flow finishing of bevel gears demonstrated the benefits of this technology in terms of improving material removal rate and surface roughness. The use of ultrasonic vibration changes the relative motion of the grinding grains with respect to the workpiece, resulting in a more efficient material removal process.
Future research could focus on further optimizing the ultrasonic vibration parameters to achieve even better surface quality and efficiency. In addition, exploring the combination of ultrasonic vibration with other energy fields, such as electrochemical or laser fields, could lead to new and innovative manufacturing processes for gears.
13. Conclusion: The Road Ahead for Gear Grinding Technology
The research on gear high – efficiency precision grinding processing and surface integrity control technology has made significant progress in recent years. From the understanding of different grinding methods and material removal mechanisms to the development of high – efficiency grinding technologies and the exploration of surface integrity aspects, researchers have made important contributions to the field.
However, there is still much room for improvement and innovation. The development of new grinding wheels with high precision and good wear resistance is essential to meet the challenges of new materials and processing requirements. The further study of gear multi – energy field composite manufacturing technology will enable better quality control and more efficient manufacturing processes. And the development of high – performance gear grinding machines with advanced sensors, automation control systems, and cooling technologies will improve production efficiency and workpiece quality.
In conclusion, continuous research and innovation in gear grinding technology are crucial for meeting the increasing demands for high – performance gears in various industries. By addressing these challenges and exploring new directions, the future of gear grinding technology looks promising, with the potential to deliver even higher quality gears for a wide range of applications.
