Large austenitic stainless steel pipes are widely used in high-end fields such as petrochemicals, nuclear power, and aerospace due to their excellent corrosion resistance, high temperature resistance, and mechanical properties. However, polishing the inner bore of large pipes has always been a difficult problem in mechanical processing. The inner bore of large pipes is narrow, and traditional manual polishing has difficulty reaching deep, and the polishing force is uneven, which can easily lead to scratches and uneven defects on the inner bore surface, affecting the performance of the pipe. At the same time, austenitic stainless steel has high hardness and strong toughness, and is prone to work hardening during the polishing process, which increases the difficulty of polishing. In addition, the large size of large pipes makes it difficult to transport and fix them, which also brings many challenges to the inner bore polishing operation.
To address the challenges of polishing the inner bores of large austenitic stainless steel pipes, the industry is constantly exploring and innovating polishing technologies. Currently, commonly used polishing methods include mechanical polishing, chemical polishing, and electrolytic polishing. Mechanical polishing achieves improved finish through friction between the polishing tool and the inner bore surface. Commonly used tools include grinding wheels, polishing belts, and flap wheels. To accommodate the characteristics of large pipe inner bores, mechanical polishing equipment typically utilizes a retractable polishing arm that can be adjusted based on the inner bore diameter to ensure full contact between the polishing tool and the inner bore surface. During the polishing process, the polishing speed, pressure, and feed rate must be properly controlled to avoid over-polishing or under-polishing.
Chemical polishing uses a chemical solution to corrode the inner surface of austenitic stainless steel, thereby removing the rough surface layer and achieving the desired polishing effect. This method does not require complex mechanical equipment, is relatively simple to operate, and can evenly polish even complex inner surfaces. Chemical polishing solutions typically consist of ingredients such as acids, oxidants, and corrosion inhibitors, with different formulations suited to different polishing requirements. During chemical polishing, the solution concentration, temperature, and treatment time must be strictly controlled to prevent excessive corrosion of the inner surface, which could affect the dimensional accuracy and mechanical properties of the pipe. Furthermore, wastewater generated by chemical polishing must be properly handled to avoid environmental pollution.
Electropolishing involves placing a large austenitic stainless steel tube as the anode in an electrolytic cell. Direct current is applied to dissolve the metal ions on the inner surface, achieving polishing. Electropolishing offers advantages such as high efficiency, excellent polishing results, and stable surface quality, resulting in a mirror-like finish. During the electropolishing process, parameters such as the electrolyte composition, current density, and electrolysis time must be carefully selected to ensure optimal polishing. Furthermore, electropolishing equipment must be well sealed and secure to prevent electrolyte leakage and electric shock accidents.
With the continuous advancement of science and technology, the technology for polishing the inner bore of large austenitic stainless steel pipes has also been developing continuously. In recent years, automated polishing equipment has been gradually applied to inner bore polishing operations. By controlling the motion trajectory and parameters of the polishing tool through robots or CNC systems, the polishing process has become automated and intelligent. Automated polishing not only improves polishing efficiency and quality, but also reduces manual labor intensity and the impact of human factors on the polishing effect. At the same time, the development of new polishing materials and polishing fluids has provided more options for inner bore polishing, further improving polishing performance. In the future, with the continuous upgrading of the manufacturing industry, the inner bore polishing technology for large austenitic stainless steel pipes will develop towards higher precision, higher efficiency, and more environmentally friendly directions.
