Deep Rolling Fixture for Hollow Fan Blade Fatigue Life

The patent extracts the essential function of hydraulic burnishing (applying controlled pressure to induce compressive residual stress) while removing the complex hydraulic actuation system. Instead, it uses a simple spring-loaded mechanism that automatically provides the necessary contact pressure, eliminating the need for hydraulic pumps, valves, and pressure control systems while maintaining the core beneficial effect.

The patent replaces the expensive, maintenance-intensive hydraulic system with a simple, inexpensive spring mechanism. The spring-loaded tool can be easily replaced or adjusted without requiring complex maintenance procedures, making it more economical and suitable for production environments where tool wear is expected.

The patent segments the contact surface from a single point (ball bearing) to a distributed line contact (roller). This segmentation allows multiple points along the roller length to contact the workpiece simultaneously, increasing the effective processing area while maintaining the controlled pressure necessary for quality surface finish. The roller can be thought of as multiple ball bearings arranged in a line, working in parallel.

The patent transitions from zero-dimensional point contact (ball) to one-dimensional line contact (roller). This dimensional change increases the contact surface area available for processing without sacrificing the controlled pressure application, thereby improving productivity while maintaining surface finish quality.

The patent implements a self-adjusting mechanism where the spring automatically adapts to different workpiece geometries and required contact pressures. The spring-loaded tool shaft self-regulates the contact force based on the reaction force from the workpiece, eliminating the need for operator intervention or complex control systems. The tool serves itself by automatically maintaining optimal contact pressure throughout the processing operation.

The patent uses a dynamic spring-loaded system that can automatically adapt to varying processing conditions. The spring constant and pre-load can be selected to provide the appropriate contact pressure for different materials and geometries, making the system versatile without requiring manual adjustment or complex control mechanisms.

The patent uses a spring-loaded mechanism that inherently cushions the contact between the tool and workpiece. The spring acts as a buffer that prevents excessive contact stress by yielding when the optimal pressure is reached or when unexpected variations in workpiece geometry occur. This beforehand cushioning protects against material damage while ensuring sufficient contact stress is applied to induce the desired compressive residual stress for improved fatigue life.

The spring-loaded system provides inherent feedback through the contact force. As the tool engages the workpiece, the spring compresses and automatically adjusts the contact pressure based on the reaction force from the workpiece. This passive feedback mechanism ensures that contact stress remains within safe limits while achieving the necessary level to improve fatigue properties, preventing both under-processing and over-processing.