平键键槽两侧面对基准轴线的对称度误差(简称键槽对称度误差),在实际加工中难以控制。正确规定键槽对称度公差和正确评定键槽对称度误差,对保证键联接的质量和降低生产成本具有重要意义。本文提出一种规定键槽对称度公差的新方法,并相应地提出一种按定位最小区域评定键槽对称度误差的计算公式,供有关设计、加工和检验人员参考。一、如何规定键槽的对称度公差笔者认为,键槽的对称度公差与键联接的装配顺序有关。键联接可按两种顺序进行装配,一种是键先在轴槽中固定,然后再与毂槽装配;另一种是键先在毂槽中固定,然后再与轴槽装配。现分别说明如下: Flat keyway on both sides of the reference axis of the symmetry error (referred to as keyway symmetry error), difficult to control in the actual processing. Correctly specifying the tolerances of the symmetry of the keyway and correctly evaluating the symmetry error of the keyway are of great significance for ensuring the quality of the key connection and reducing the production cost. In this paper, a new method of defining the tolerance of the keyway symmetry is proposed, and a formula for calculating the symmetry error of the keyway according to the minimum positioning area is proposed accordingly for reference by the relevant designers, processors and inspectors. First, how to regulate the symmetry of the keyway Tolerance I believe that the symmetry of the keyway tolerance and key connection assembly order. Key connection can be assembled in two sequences, one is the key first fixed in the shaft groove, and then with the hub groove assembly; the other is the key first fixed in the hub groove, and then with the shaft groove assembly. Now as follows: