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由于碳具有很多优良特性,所以以碳为基料而制成的各种机械零部件已广泛地应用于国民经济各个领域,其中尤以碳-石墨轴承更为突出。但碳-石墨是脆性材料、抗冲击能力较差,为了提高其机械强度,便于安装和维修,通常多以碳-石墨做轴衬,在其外周镶装金属轴套,构成碳-石墨组合轴承。碳-石墨组合轴承各部分公差选择得正确与否,直接影响它的使用寿命和工作效能。目前,多数使用厂家都是根据国家标准“公差与配合”选择碳轴承公差的。但因碳轴村与金属轴套的机械特性相差较远,若完全根据“公差与配合”确定公差,在某些情况下不尽合适,需要进行适当的修正,修正时要考虑如下因素:①润滑状态;②工作温度;③工作负荷;④运转速度;⑤轴与轴承的材质及结构等,其中以前两项尤为重要。碳-石墨组合轴承,主要控制两个公差(如图):
Because carbon has many excellent features, so all kinds of mechanical parts made of carbon-based materials have been widely used in various fields of the national economy, especially carbon-graphite bearings are more prominent. However, carbon-graphite is a brittle material with poor impact resistance. In order to increase its mechanical strength and facilitate installation and maintenance, carbon-graphite is usually made of a carbon-graphite bushing and fitted with a metal sleeve on its periphery to form a carbon-graphite composite bearing . Carbon-graphite composite bearing parts tolerances are chosen correctly or not, directly affect its service life and work efficiency. At present, most manufacturers are using the national standard “tolerance and cooperation” to choose carbon bearing tolerances. However, due to the far difference between the mechanical properties of the carbon shaft and the metal sleeve, if the tolerance is completely determined according to “tolerance and fit”, in some cases it is not suitable and proper correction is needed. The following factors should be taken into account when amending: Lubrication state; ② working temperature; ③ work load; ④ operating speed; ⑤ shaft and bearing materials and structures, of which the previous two are particularly important. Carbon - graphite composite bearings, the main control of two tolerances (pictured):