大型曲面箱底旋压成形　工艺规范Spinning process of large-curved tank bottom—Technological specificationICS 25.020CCS J 32中华人民共和国国家标准GB/T 44920—20242024-11-28 发布2025-06-01 实施国家市场监督管理总局国家标准化管理委员会发 布目　　次前言 ····················································...