用调整法大批量生产如图所示箱体零件，平面A、B已加工完毕，欲以平面B定位安排镗孔工序，保证设计尺寸205±0.1mm。试建立尺寸链、指明各环性质并求工序尺寸H的大小及偏差。
参考答案：
(1)画尺寸链图如下图所示，
封闭环205±0.1
增环355±0.05
减环H
(2)计算
H的基本尺寸：由205=355-H，得H=150
下偏差：+0.1=0.05-EIH
得EIH=-0.05
上偏差：-0.1=-0.05-ESH
ESH=+O.05
故H=150±0.05mm
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