Abstract

Laser cladding technology, particularly high-speed laser cladding, has shown remarkable potential in repairing slender piston rods used in coal mine hydraulic supports. Traditional repair methods, such as electroplating, often result in significant deformation and low pass rates. High-speed laser cladding offers several advantages, including low heat input, high efficiency, and minimal deformation. This method provides substantial economic and environmental benefits, making it an ideal choice for slender piston rod repair in the mining industry.

I. Application Background and Repair Requirements

Slender piston rods, typically measuring approximately φ70 mm × 1000 mm with an aspect ratio exceeding 10:1, are critical components in hydraulic support systems used in coal mining. Traditional electroplating repair methods often lead to deformation, causing rods to bend after stripping and resulting in a re-electroplating pass rate of less than 20%. As a result, many piston rods are scrapped due to excessive deformation, leading to wasted resources and increased costs.

Statistics show that the domestic coal mining machinery industry repairs about 2 million slender piston rods annually. Replacing all of these parts would cost approximately 1.04 billion yuan. By utilizing high-speed laser cladding technology, the industry can save about 150 yuan per piece, leading to annual cost savings of approximately 300 million yuan. This represents a significant economic advantage for the industry.

II. Principles and Features of High-Speed Laser Cladding Technology

High-speed laser cladding technology, developed by the Fraunhofer Laser Institute in Germany, is an advanced version of traditional laser cladding. The key features of this technology include:

1.Low Heat Input: Around 80% of the laser energy is used to melt the powder, minimizing thermal impact on the substrate, which prevents deformation.

2.High-Speed Scanning: Scanning speeds range from 200 to 500 m/min, leading to rapid cooling of the melt pool and refined microstructure.

3.Thin-Layer Cladding: Coating thicknesses vary from 25 to 500 μm, ensuring high surface quality and enabling direct grinding and polishing.

4.High Powder Utilization: The interaction between the laser beam and the powder flow enhances material utilization, improving the overall efficiency of the process.

These features allow high-speed laser cladding to address the thermal deformation problem in the repair of slender piston rods, achieving low deformation, high-performance repairs.

III. Comparison with Traditional Repair Processes

When compared to traditional repair methods, high-speed laser cladding significantly reduces deformation of the workpiece while maintaining excellent coating bond strength and wear resistance. This makes laser cladding an ideal method for the precise repair of slender, thin-walled parts, such as slender piston rods in mining machinery.

IV. Current Status and Trends in Technology Development

High-speed laser cladding technology has been successfully applied across multiple industries, including coal, metallurgy, aerospace, and shipbuilding. Leading research institutions such as Fraunhofer ILT, RWTH Aachen University, and Harbin Institute of Technology have made significant progress in material systems, process optimization, and equipment development.

Currently, high-speed laser cladding has been commercialized for large hydraulic support cylinders. However, further optimization and equipment development are required for mass repair of heat-sensitive parts, such as slender piston rods, to ensure more widespread application.

V. Conclusion

High-speed laser cladding technology provides substantial advantages, such as low heat input, high cladding efficiency, and low deformation, making it particularly well-suited for high-precision repair of slender piston rods. This advanced technology improves repair yield and product lifespan while offering significant energy savings and cost reductions. Furthermore, it provides a more environmentally friendly alternative to traditional electroplating methods. Laser cladding holds great promise for the future of mining machinery repair and has the potential for broader adoption in other industries.