机械零件工艺基准
Process standard of mechanical parts
零件在加工和装配过程中所使用的基准，称为工艺基准。工艺基准按用途不同又分为装配基准、测量基准及定位基准。
The datum used in the processing and assembly of parts is called process datum. According to different purposes, process datum can be divided into assembly datum, measurement datum and positioning datum.
（1）装配基准 装配时用以确定零件在部件或产品中的位置的基准，称为装配基准。
(1) Assembly datum the datum used to determine the position of a part in an assembly or product during assembly is called assembly datum.
（2）测量基准 用以检验已加工表面的尺寸及位置的基准，称为测量基准。
(2) The benchmark used to check the size and position of the machined surface is called the benchmark.
（3）定位基准 加工时工件定位所用的基准，称为定位基准。作为定位基准的表面（或线、点），在第一道工序中只能选择未加工的毛坯保定平面设计培训 保定空调维修 保定管道通风 包装盒定做 化粪池模具 废旧电缆回收 不锈钢铸件 表面，这种定位表面称粗基准.在以后的各个工序中就可采用已加工表面作为定位基准，这种定位表面称精基准。
(3) Positioning datum refers to the datum used for workpiece positioning during machining. For the surface (or line, point) as the positioning reference, only the rough surface can be selected in the first process. This positioning surface is called the rough reference. In each subsequent process, the machined surface can be used as the positioning reference, and this positioning surface is called the fine reference