自改革开放以来，我国引进了不少国外设备、图纸和其它技术资料，有不少发达国家的机械图样投影方法与我国所采用的投影方法不同。为了更好地学习发达国家的先进技术，故快速看懂国外机械图纸很有必要。1 概述 t当今世界上，ISO国际标准规定，第一角和第三角投影同等有效。各国 Since the reform and opening up, China has introduced a lot of foreign equipment, drawings and other technical data. Many developed countries have different projection methods for mechanical drawings than the projection methods used in our country. In order to better learn advanced technology in developed countries, it is necessary to quickly understand foreign mechanical drawings. 1 Overview t In today’s world, the ISO international standard states that the first and third-angle projections are equally valid. Countries