1. Introduction
Spiral bevel gears play a crucial role in aviation transmission systems, such as in aircraft engines, engine reducers, and helicopter transmission systems. The milling process is a key step in the manufacturing of these gears, which significantly affects the final quality and performance of the gears. This article focuses on the design and verification of the milling process for aviation transmission spiral bevel gears, aiming to provide a comprehensive understanding and practical guidance for process designers.
1.1 Importance of Spiral Bevel Gears in Aviation
Spiral bevel gears are essential components in aviation mechanical systems. They are required to meet high technical standards to support various functions such as power transmission, speed reduction, and direction change. These gears need to possess excellent mechanical properties, including high strength, good wear resistance, and low vibration and noise characteristics, to ensure the reliable operation of the entire aviation system.
1.2 Significance of the Milling Process
The milling process is a critical operation in the production of spiral bevel gears. It determines the initial shape and accuracy of spiral bevel gear teeth, which has a direct impact on the subsequent grinding process and the final quality of spiral bevel gears. A well-designed milling process can improve machining efficiency, reduce production costs, and ensure the consistency and quality of gear production.
2. Architecture Design
2.1 The Concept of the R & D V Model
The R & D V model is adopted to decompose the traditional continuous milling process into different stages, including requirements analysis, preliminary design, detailed design, etc. This model provides a structured approach for process designers to systematically consider various factors and requirements in the design process.
2.2 Relationship between Milling Workpiece, Tool, and Equipment
In the milling process, there are complex static and dynamic relationships among the workpiece, tool, and equipment. These relationships need to be carefully analyzed and calculated by process designers. For example, the geometry and material properties of the workpiece affect the selection of tools and equipment, while the characteristics of the tools and equipment also influence the machining parameters and quality of the workpiece.
| Factors | Impact on Milling Process |
|---|---|
| Workpiece Geometry | Determines tool path and cutting parameters |
| Workpiece Material | Affects tool wear and cutting force |
| Tool Geometry | Influences tooth profile and surface finish |
| Tool Material | Determines tool life and cutting efficiency |
| Equipment Specifications | Constrains machining range and accuracy |
3. Design and Verification Stages
3.1 Requirements Analysis and Verification
3.1.1 Meeting the Needs of the Grinding Process
The milling process design needs to meet the requirements of the grinding process, which is the final finishing operation for spiral bevel gears. The grinding process typically uses the tooth engagement imprint as a comprehensive performance verification result and the characteristics of the tooth surface, tooth root, and tooth root fillet as physical performance verification results.
3.1.2 Verification Methods
To verify the design requirements, specific engagement specimens are designed for matching verification. In addition, with the wide application of gear professional software such as GEMS, KIMOS, and CHIMES, the theoretical tooth model and topography can be calculated, and specific parts can be measured and compared using a gear-specific measuring machine for mutual verification with the imprint.
3.2 Preliminary Design and Verification
3.2.1 Calculation of Gear Blank Geometric Parameters
The geometric parameters of spiral bevel gear blank, such as cone distance, tooth length (tooth width), and total tooth height, need to be calculated. Considering the relationship between tooth volume and accuracy, and the need for subsequent grinding processing, the geometric parameters of spiral bevel gear blank cannot be simply calculated according to the nominal value but should take into account the tolerance.
3.2.2 Calculation of Tooth Geometric Parameters
In addition to the basic tooth parameters provided in the traditional design drawing, such as the number of teeth, module, and tooth thickness, other geometric parameters required for tooth processing, such as the tooth groove width, tooth bottom fillet, arc tooth thickness, chord tooth thickness, and their corresponding tooth heights in various sections and directions of the tooth root, need to be calculated using spiral bevel gears manual size card.
3.2.3 Consideration of Equipment, Tool, and Fixture
The equipment, tools, and fixtures for milling processing need to consider not only the basic requirements provided by the tooth parameters but also factors such as equipment specifications, tool standards, and the interaction structure between parts and fixtures. The tooth surface, tooth root, and tooth root fillet need to consider the final characteristics and grinding allowance. At the same time, the balance between the tool cutting path and the fillet needs to be considered.
3.2.4 Verification of Geometric and Shape Characteristics
The geometric and shape characteristics of the teeth can be verified by calculating the theoretical tooth model and then using a gear-specific measuring machine to measure specific parts or selecting specific sections to measure characteristics such as tooth thickness, tooth groove width, tooth depth, and runout. For characteristics that are difficult to directly measure, sample parts can be made for comparison.
3.3 Detailed Design and Verification
3.3.1 Design of Milling Cutting Calculation Table
According to the gear manual, a milling cutting calculation table is designed. By inputting the relevant parameters and specifications of the workpiece, tool, and equipment, the motion relationships such as angles and distances among them can be calculated.
3.3.2 Adjustment of Machining Parameters based on Imprint
Trial machining of engagement specimens with reduced tooth thickness is carried out, and the imprint is checked using the engagement specimens, engagement machine, and tooling. Based on the imprint results, the machining is adjusted within the allowable tooth thickness range. Generally, low-order parameters (such as angles) are adjusted first, followed by high-order parameters (such as change rates). After obtaining stable adjustment parameters, the calculation tables for the large and small wheels are optimized respectively for batch machining.
3.3.3 Application of TCA and Gear Professional Software
TCA (Tooth Contact Analysis) is used to accurately evaluate the contact area and motion transmission of spiral bevel gears, eliminating the need for long trial fitting processes. Gear professional software can be used to calculate the theoretical imprint, optimize the imprint shape, optimize the engagement curve, and optimize the contact area stress. Based on the optimized imprint, machining and testing programs can be generated.
3.4 Machining and Detection
3.4.1 Design of Clamping and Detection Benchmarks
For the traditional cutting machining system, clamping and detection benchmarks need to be designed for parts before and after machining and on machining and detection equipment or tooling. The design benchmark of the traditional spiral bevel gears assembly area can be used as the clamping and detection benchmark between processes. For milling parts, attention should be paid to the relationship between the design benchmark and the clamping and detection benchmark formed between processes. In some cases, substitute benchmarks may need to be processed.
3.4.2 Determination of Cutting Parameters
Based on the actual performance of the equipment, the properties of the teeth and tool materials, the back cutting depth and cutting line speed are determined. While considering the surface quality of the workpiece, the life of the tool and equipment, and avoiding the influence of machining resistance on the system, the machining efficiency is appropriately pursued.
3.4.3 Evaluation of Cutting Parameters
By detecting the surface states of the workpiece and tool, the rationality of the cutting parameters is evaluated. If the production volume is high, the surface performance of the tool can be further improved, and even the workpiece can be dissected to study the state of the surface compressive stress layer to meet the needs of subsequent processes.
4. Digital Transformation and System Solutions
4.1 Development of Gear Process Modeling and Simulation Algorithms
With the development of digital transformation, it is necessary to develop gear process modeling, calculation simulation, and analysis algorithms and programs that meet the needs of different scenarios such as design calculation, machining calculation, and detection testing. These algorithms and programs can improve the accuracy and efficiency of the design and verification process.
4.2 Standardization of Milling Process Operations
Standard operation procedures for the milling process, including process specifications, operation guidelines, and standard operation instructions, need to be developed to solidify the operation-level business and ensure the consistency and quality of the milling process.
4.2.1 Process Specifications
The process specifications should clearly define the machining steps, cutting parameters, and quality requirements for each step of the milling process. This helps to ensure that the milling process is carried out in a standardized and controlled manner.
| Step | Machining Steps | Cutting Parameters | Quality Requirements |
|---|---|---|---|
| 1 | Rough milling of gear blank | Cutting speed: , Feed rate: , Depth of cut: | Tooth profile accuracy within tolerance |
| 2 | Semi – fine milling of tooth surface | Cutting speed: , Feed rate: , Depth of cut: | Surface roughness meets standard |
| 3 | Fine milling of tooth details | Cutting speed: , Feed rate: , Depth of cut: | Tooth geometry meets design requirements |
4.2.2 Operation Guidelines
The operation guidelines should provide detailed instructions for the operation of milling equipment, including machine startup and shutdown procedures, tool installation and adjustment methods, and safety precautions. This helps operators to correctly operate the milling equipment and avoid accidents.
4.2.3 Standard Operation Instructions
The standard operation instructions should summarize the key points of the milling process operation, including the preparation work before machining, the operation sequence during machining, and the inspection and maintenance work after machining. This helps to ensure that the milling process is carried out smoothly and efficiently.
4.3 Development of Gear Professional Software
Gear professional software with the ability to calculate standardized and customizable products, tools, and equipment needs to be developed. This software can establish a gear database containing enterprise manufacturing resource attributes and integrate it into the enterprise manufacturing operation management system. It can also provide powerful calculation and analysis functions for the design and verification of the milling process.
4.4 Optimization of System Elements using Data Analysis Tools
By introducing data analysis tools, the parameters of system elements can be further optimized on the basis of stable business indicators (such as machining quality, efficiency, and comprehensive cost). This helps to improve the overall performance and competitiveness of the manufacturing system.
5. Conclusion
The design and verification of the milling process for aviation transmission spiral bevel gears is a complex and systematic task. By following the R & D V model and considering various factors in different design and verification stages, process designers can effectively design and optimize the milling process. With the development of digital transformation, the application of advanced technologies and software can further improve the efficiency and quality of the milling process, providing strong support for the production of high-quality aviation transmission spiral bevel gears. Future research and development should continue to focus on improving the design and verification methods, exploring new materials and machining techniques, and enhancing the overall performance and reliability of spiral bevel gears in aviation applications.