METHOD FOR MANUFACTURING SEAMLESS TUBE FOR HOLLOW SPRING STEEL SEAMLESS TUBE FOR SPRING STEEL PRODUCED BY THIS AND AUTOMOBILE SUSPENSION SPRING STEEL USING SAME

摘要

The present invention relates to a method for manufacturing a seamless tube for hollow spring steel with improved processability, a seamless tube for spring steel manufactured by the same, and a vehicle suspension spring using the same, and durability of 300,000 cycles or more, which is the level of a vehicle suspension spring that can be applied to a real vehicle in a hot process Through the mandrel plug to pierce the center of the round bar to form a seamless seamless tube, and in the cold process, if there is a flaw in the inner diameter of the seamless tube, the depth of the flaw is prevented to prevent the cause of premature damage due to concentration of stress. After processing to 20 µm or less, the drawn seamless tube is polished and then, after the polishing process to minimize the depth of surface defects of the inner diameter of the seamless tube, pilger rolling is introduced into the final process to improve processability.