Introduction

Gear machining plays an indispensable role in mechanical transmission systems. The precision and reliability of gears directly determine the performance of transmission systems, especially for parts working under high-load conditions. With the widespread application of industrial automation and high-performance equipment, gears not only need to work continuously under harsh conditions but also must maintain their mechanical properties under high pressure, high temperature, and impact loads. Enhancing the reliability of gears under high-load conditions lies in understanding the complex stress field during gear machining, particularly the interaction between residual and contact stresses.

This article will explore the key technologies in gear machining from the perspective of composite stress fields and reveal how optimizing gear manufacturing processes can enhance the fatigue life and damage resistance of components, with insights drawn from real-world examples from China and Europe.

1. Stress Distribution in Gear Machining

1.1 Impact of Contact Stress

During gear meshing, contact stress plays a crucial role in determining the fatigue life of the gear surface. Under rolling-sliding contact, the gear surface experiences alternating stresses, leading to the initiation and propagation of cracks. The concentration of contact stress is highest in the contact area of the gear surface, and it intensifies under high load and speed conditions, accelerating wear and fatigue.

1.2 Role of Residual Stress

Residual stress, typically formed during processes like carburizing, grinding, and shot peening, significantly influences gear performance. Proper control of compressive residual stress can improve fatigue resistance, while tensile residual stress can accelerate crack formation. Therefore, managing the distribution of residual stress in gear manufacturing is crucial.

Data Table: Influence of Various Manufacturing Processes on Residual Stress

1.3 Effect of Composite Stress Fields on Fatigue Life

The composite stress field, which combines residual and contact stresses, plays a vital role in determining fatigue life. Compressive residual stress helps mitigate the impact of contact stress, delaying crack initiation, while tensile residual stress accelerates fatigue failure. Studies show that stress concentrations often occur beneath the gear surface, making the analysis of subsurface composite stress fields essential for accurate fatigue life prediction.

2. Key Technologies for Improving Gear Reliability

2.1 Application of Rapid Prototyping Technology

Rapid prototyping technology has become widely adopted in gear manufacturing, particularly during the design phase. It allows quick generation of gear prototypes to validate structural strength and stress distribution, enabling the optimization of final designs. This technology shortens the development cycle and helps engineers analyze stress fields more effectively.

Case Study: In a European wind power project, the gear transmission system was improved using optimized prototyping techniques, significantly enhancing the gear's service life under high-load conditions.

2.2 Optimization of Shot Peening Techniques

Shot peening enhances the fatigue strength and wear resistance of gear surfaces by inducing compressive residual stress. Optimizing this process, including shot peening strength and media size selection, further extends the gear's lifespan.

3. Predicting Crack Initiation and Propagation

3.1 Crack Initiation Model

Crack initiation in gears often occurs at the subsurface, particularly in complex composite stress fields. The Dang Van criterion effectively predicts crack initiation sites, and through optimization of the gear’s geometry and manufacturing processes, crack initiation periods can be extended.

3.2 Crack Propagation Model

Crack propagation determines the gear's final failure time. By controlling the crack growth resistance of the gear material and using stress intensity factor models, the crack growth path can be accurately predicted.

4. Conclusion

Composite stress field analysis in gear machining provides crucial insights for improving the reliability of high-load components. By controlling the distribution of contact and residual stresses, combined with process optimizations like rapid prototyping and shot peening, the fatigue performance and service life of gears can be significantly enhanced. Future research into the effects of composite stress fields on crack initiation and propagation will provide even more precise guidance for high-performance gear design and manufacturing.