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在机械加工中,工序尺寸的确定往往采用极值法。然而,极值法往往出现“精度过剩”,对工作母机和工艺设备要求过高,导致成本大幅度增加。因此,如何确定工序尺寸及其偏差,达到既能保证加工质量,又不致于出现“精度过剩”是我们所关心的问题。如图1所示,用极值法求解时,工序尺寸L_4=67.5_(+0.1)。毫无疑问,按照这个尺寸及公差加工,完全能保证封闭环的设计要求。如果L_4=67.65,即超差0.05,在工序检验时将认
In machining, the size of the process often used to determine the extreme value method. However, the extremum method often appears “excess precision”, demanding on the machine tools and process equipment, resulting in a substantial increase in costs. Therefore, how to determine the size of the process and its deviation, to achieve both to ensure the quality of processing, without causing “excess precision” is our concern. Shown in Figure 1, using extreme value method for solving, the process size L_4 = 67.5 _ (+0.1). There is no doubt that according to this size and tolerance processing, can fully guarantee the design requirements of the closed loop. If L_4 = 67.65, that is, the difference of 0.05, will be recognized in the process of inspection