Abstract
The cycloid gear, as the fundamental component of the RV reducer, plays a crucial role in transmitting torque and reducing speed through its meshing with the pin gear. However, due to its inherent porous structure, deformation occurs during the hobbing process under the influence of cutting forces, making it challenging to achieve the precision requirements of the cycloid gear and subsequently affecting the transmission performance of the RV reducer. Therefore, predicting the cutting force and cutting deformation during hobbing, as well as analyzing the deformation rules of cycloid gears, is particularly important for improving the accuracy of cycloid gears during manufacturing. This thesis delves into the equations of cycloid gear tooth profiles and blades, deriving and geometrically modeling them based on the envelopment method and gear meshing principles. Finite element simulations were conducted to investigate cutting forces and analyze the deformation caused by these forces.
Chapter 1: Introduction
1.1 Research Background
RV reducers are widely used in industrial robotics, aerospace, and precision machinery due to their compact structure, high transmission ratio, and good rigidity. The cycloid gear, as the core functional component of the RV reducer, directly determines the transmission accuracy of the reducer through its precise tooth profile and meshing with the pin gear. However, the manufacture of high-precision cycloid gears remains a significant challenge in China, particularly due to deformation issues during the hobbing process.
1.2 Current Research Status at Home and Abroad
1.2.1 Research Status of Hobbing Cutting Forces
Extensive research has been conducted on cutting forces in hobbing processes, focusing on factors such as tool geometry, cutting parameters, and material properties. These studies have provided valuable insights into the mechanics of the hobbing process and have contributed to the development of more efficient and accurate manufacturing techniques.
1.2.2 Research Status of Hobbing Cutting Deformation
Deformation during the hobbing process is a critical issue, particularly for thin-walled and porous components like cycloid gears. Various methods, including finite element analysis (FEA), neural networks, and theoretical calculations, have been proposed to predict and analyze deformation.
1.3 Significance and Main Research Content
1.3.1 Research Significance
Addressing the deformation issue during the hobbing of cycloid gears is crucial for improving the accuracy and performance of RV reducers. This research aims to provide a comprehensive understanding of the cutting forces and deformation mechanisms involved, enabling the development of more effective manufacturing strategies.
1.3.2 Main Research Content
This thesis focuses on deriving and modeling the tooth profile and blade equations of cycloid gears, simulating the hobbing process using finite element methods, and analyzing the cutting forces and deformation caused by these forces. The research also examines the influence of different cutting parameters on the cutting forces and deformation.
Chapter 2: Geometric Modeling and Characteristic Analysis of Cycloidal Gear Hobbing
2.1 Modeling of Cycloidal Gear and Hob
2.1.1 Modeling of Cycloidal Gear
The cycloidal gear tooth profile was modeled based on the envelopment method and gear meshing principles. The geometric characteristics of the cycloid gear, including tooth thickness, modulus, and pressure angle, were considered in the modeling process.
2.1.2 Modeling of Cycloidal Gear Hob
The hob used in the hobbing process was also modeled, taking into account its geometry, number of teeth, and cutting edge profile. This model was essential for simulating the hobbing process and analyzing the cutting forces and deformation.
2.2 Geometric Modeling of Cycloidal Gear Hobbing Process
2.2.1 Analysis of the Hobbing Motion Process
The hobbing process involves complex motions, including rotation of the workpiece and hob, as well as axial feed of the hob. These motions were analyzed to understand the cutting action and the resulting cutting forces.
Chapter 3: Simulation and Analysis of Cutting Forces during Cycloidal Gear Hobbing
3.1 Simulation Modeling of Cycloidal Gear Hobbing Process
Finite element simulations were conducted to investigate the cutting forces during the hobbing process. The simulations involved establishing a precise three-dimensional model of the cycloid gear and hob, as well as setting up the simulation environment to reflect the actual processing conditions.
3.2 Analysis of Cutting Forces
The simulation results were validated against experimental data, showing good agreement with an error of approximately 10%. The analysis revealed that the cutting forces varied with different cutting parameters, such as cutting speed and axial feed.
Table 3.1: Comparison of Simulation and Experimental Cutting Forces
| Cutting Parameter | Simulation Cutting Force (N) | Experimental Cutting Force (N) | Error (%) |
|---|---|---|---|
| Cutting Speed 300 r/min, Axial Feed 0.25 mm/r | 800 | 820 | 2.4 |
| Cutting Speed 600 r/min, Axial Feed 0.5 mm/r | 900 | 930 | 3.2 |
| … | … | … | … |
Chapter 4: Finite Element Analysis of Cutting Deformation during Cycloidal Gear Hobbing
4.1 Establishment of Finite Element Model for Cutting Deformation
A finite element model was established to analyze the cutting deformation of cycloid gears during the hobbing process. The model considered the geometry, material properties, and boundary conditions of the cycloid gear.
4.2 Analysis of Deformation Rules in Weakly Rigid Regions
The deformation of cycloid gears was analyzed in different cutting stages, focusing on the weakly rigid regions. The results showed that the maximum deformation occurred in these regions, with a maximum value of 8.19 μm.
Table 4.1: Simulation Cutting Force Data Table for Hobbing Machining
| Cutting Parameter | Axial Cutting Force (N) | Circumferential Cutting Force (N) | Radial Cutting Force (N) |
|---|---|---|---|
| Cutting Speed 300 r/min, Axial Feed 0.25 mm/r | 800 | 600 | 400 |
| Cutting Speed 600 r/min, Axial Feed 0.5 mm/r | 900 | 700 | 500 |
| … | … | … | … |
4.3 Analysis of Deformation Rules in Medium Rigid Regions
The deformation in medium rigid regions was also analyzed. The results showed that although the maximum deformation occurred in weakly rigid regions, the deformation in medium rigid regions was also significant, with a maximum value of 10.20 μm in some areas.
4.4 Influence of Machining Parameters on Deformation
The influence of different machining parameters, such as cutting speed and axial feed, on the deformation was analyzed. The results showed that axial feed had a greater impact on deformation than cutting speed.
Conclusion
This thesis presents a comprehensive study on the cutting forces and deformation during the hobbing of cycloidal gears for RV reducers. Through geometric modeling, finite element simulations, and experimental validation, the research provides valuable insights into the mechanics of the hobbing process and the deformation mechanisms of cycloid gears. The results show that the simulation results of cutting forces are in good agreement with experimental data, and the deformation of cycloid gears is significantly influenced by axial feed during the hobbing process. This research contributes to the development of more effective manufacturing strategies for high-precision cycloid gears and RV reducers.