Laser Shock Strengthening of Small Holes Across Varying Thicknesses
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Solution Overview
Problem
Existing methods for laser shock processing of small hole members with different thicknesses face challenges in achieving uniform strengthening effects and maintaining surface quality, particularly for small holes with diameters of 3 mm or less, due to limitations in controlling laser parameters and equipment requirements.
Innovation Solution
An empirical formula and process parameter determination method are developed to select optimal laser power density, pulse width, energy, and spot size based on material properties and thickness, along with the use of a constrained and absorption layer, to ensure satisfactory fatigue gain and surface quality, allowing for adjustable overlapping rates and impact layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional mechanical strengthening methods such as shot peening or extrusion are used, then the process is simple and equipment requirements are low, but small holes with diameters of 3 mm or less cannot be effectively strengthened
Solution Approach 1:
The patent replaces conventional mechanical strengthening methods (shot peening, extrusion) with laser shock processing. The laser beam generates shock waves that propagate through the material to induce residual compressive stresses in the hole wall, eliminating the need for mechanical contact and enabling effective strengthening of small holes with diameters of 3 mm or less.
Solution Approach 2:
The patent optimizes laser processing parameters including pulse width (10-30 ns), power density, and spot size to achieve effective strengthening of small holes. By carefully controlling these parameters, the laser shock processing can generate sufficient shock wave pressure while maintaining precision for small aperture holes.
2Strength
If laser shock processing is performed after drilling small holes, then non-contact strengthening is achieved, but the laser causes damage to the small hole and affects hole precision and surface quality
Solution Approach 1:
The patent applies preliminary protective measures before laser shock processing by placing a transparent constrained layer (such as glass or water) over the hole. This layer protects the hole from direct laser damage while still allowing the shock wave to propagate and strengthen the hole wall. The constrained layer is removed or drained after processing.
Solution Approach 2:
The patent introduces a constrained layer as an intermediary between the laser beam and the workpiece. This layer (transparent material or water) mediates the laser energy transmission, allowing the shock wave to pass through while protecting the hole from direct laser exposure and thermal damage. The intermediary layer is discarded or reused after the process.
3Strength
If high power laser equipment is used to ensure strengthening effect for all thicknesses, then strengthening quality is improved, but equipment cost and complexity increase
Solution Approach 1:
The patent employs dynamic adjustment of laser parameters based on material thickness. The system automatically adapts pulse width, power density, and spot size according to the thickness of the workpiece, allowing a single laser system to effectively process a wide range of thicknesses without requiring multiple high-power laser units.
Solution Approach 2:
The patent establishes parameter ranges optimized for different thicknesses: pulse width (10-30 ns), power density, and spot size. By varying these parameters within the optimized ranges, the system achieves effective strengthening across different material thicknesses using a single laser equipment platform, reducing overall system complexity and cost.
4Ease of manufacture
If a single set of laser parameters is used for all thicknesses, then the process is simple, but the strengthening effect is not optimal for different thicknesses
Solution Approach 1:
The patent implements a dynamic parameter selection system that automatically adjusts laser settings based on the measured or input thickness of the workpiece. The system stores pre-optimized parameter sets for different thickness ranges and selects the appropriate set automatically, maintaining process simplicity while achieving optimal strengthening for each specific thickness.
Solution Approach 2:
The patent defines specific parameter ranges optimized for different thickness categories. For example, pulse width is set between 10-30 ns, with specific values selected based on thickness. Power density and spot size are similarly adjusted. This systematic parameter management maintains operational simplicity while ensuring optimal strengthening effects across various thicknesses.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively strengthens small hole members of varying thicknesses, achieving stable fatigue gain and surface quality, breaking the limitations of previous technologies and reducing equipment requirements, while enabling the use of smaller energy lasers for cost-effectiveness.
Implementation Method 1
laser shock processing
Implementation Method 2
laser shock processing
Data Source
AI summary
The invention provides a laser shock processing method for small-hole component with different thickness. In this method, different process parameters are adopted for laser shock processing of small hole members with different thicknesses, and the empirical formula was obtained by statistical analysis of the experimental results, and the empirical formulaI0=AetBσs2Zis the relationship between power density and thickness of small hole members. According to this formula, the power density of laser shock strengthening of orifice member with different thickness is determined, and the selection and determination method of process parameters related to this is put forward. According to this method, reasonable residual compressive stress distribution can be obtained after laser shock strengthening with appropriate technology, and good strengthening effect can be achieved.