工程图样中重影点标注常见错误探讨

Discussion on Common Mistakes of Labeling Overlapping-dot in Engineering Drawing

重影点不仅是工程制图中的一个重要概念,而且也是作图求解某些问题的重要理论依据.近年来出版的教材在作图求解的例图中,存在对重影点标注不规范的现象;甚至有些教材中另外加注的规定还淡化了重影点的概念.该文详细论述了重影点的概念、标注原则,以及如何标注空间点、线、面对某一投影面投影;同时又进一步详细分析了有些教材中在作图求解的例图中出现的重影点标注的错误,并给出了如何正确的标注.

The conception of overlapping-dot is not only a basic conception in engineering drawing,but also important theory evidence when solving some problems with the method of drawing picture.With regard to overlapping-dot labeling,there were some nonstan-dard labeling in recent publishing teaching materials.Moreover,the conception of overlapping-dot was even weakened in some teaching materials.In this paper,the author expatiated the conception of overlapping-dot,labeling rule,and how to label the projec-tion of certain dot,line and surface,and also analyzed errors of labeling overlapping-dot in illustrational drawing of some teaching materials and pointed out how to rightly label them.