我国现在生产的客车车体,包括钢结构和木结构两部分。钢结构是由钢质板材、型材通过焊接、铆接等工艺手段制成,木结构大多是木质的梁、板材通过不同型号、不同规格的圆钉、螺钉、螺栓等连接组装而成。不管哪种结构,在设计图上,构成这些结构的零部件尺寸及相互关系尺寸的公差,大多是自由公差。即使有的标注了公差,也是很 China’s bus body is now produced, including steel and wood structure in two parts. Steel structure is made of steel plate, profile by welding, riveting and other technological means, most of the wood structure is a wooden beam, plate through different models, different specifications of the round nails, screws, bolts and other connections assembled. No matter what kind of structure, in the design drawings, the size of the components constituting these structures and the size of the relationship between the tolerance, mostly free to tolerance. Even if some of the tolerances, it is also very