论文部分内容阅读
在机械制图的教学实践中,笔者发现,对尺寸标注部分的教学若只根据现行教材来讲述,效果不佳。如在零件图绘制中,常出现一些不合理的、尺寸缺少或多余的标注,反映出学生对尺寸标注理解掌握得很不完善,不能适应将来工作的需要。为此,笔者在零件图的教学中,加强了尺寸标注的训练。一、对三个基本尺寸要素的标注1.基本尺寸和公称尺寸的含义及注法基本尺寸是设计给定的尺寸,如图1中的尺寸20与φ10,不包括公差。公称尺寸是某一要素或零件尺寸的名义值。如图2中的φ4,是锥销孔的公称尺寸,它既非该孔大端直径,也非小端直径,而是与其相配合的圆锥销
In the teaching practice of mechanical drawing, the author found that the teaching of the dimensioning part if only based on the current teaching material to tell, the effect is not good. Such as parts drawing, there are often some unreasonable, lack of size or redundant callouts, reflecting the understanding of the students mark the imperfections, can not adapt to the needs of future work. To this end, the author in the teaching of parts drawings, to strengthen the dimension of the training. First, the three basic dimensions of the label 1. The basic size and nominal size of the meaning and method of injection The basic size is the design of a given size, as shown in Figure 1, the size of 20 and φ10, excluding tolerances. Nominal size is the nominal value of a feature or part size. Figure 4, φ4, is the nominal size of the tapered pin hole, which is neither the large end diameter of the hole, nor the small end diameter, but with the mating tapered pin