基于虚拟控制面约束的机匣类零件工序模型建立方法

在多岛屿特征机匣类零件的数控加工中,建立准确的加工工序模型是实现该类零件智能加工的关键技术。为了获得多岛屿特征机匣类零件准确的加工工序模型,提出了一种基于虚拟控制面约束的机匣类零件工序模型建立方法。首先,根据多岛屿特征机匣类零件的加工特征对建模过程中虚拟控制面约束的引入进行了分析,并结合虚拟控制面约束思想给出了拉格朗日超限插值的建模理论;然后,结合机匣类零件的几何特征确定了虚拟控制面的分布位置和几何形状的计算方法,在此基础上根据虚拟控制面建模理论构造了中间变形曲面,依据切削深度约束确定了工序模型,并对其进行了轨迹规划;最后,在一类多岛屿特征的机匣零件上对算法进行了验证,结果表明,本文方法能够根据机匣零件加工特征分布情况有效地控制工序模型的几何形状,避免了同时处理多个加工特征所导致的工序曲面过早趋于复杂现象,为多岛屿特征机匣类零件的数控加工提供有效的工序模型,一定程度上降低了该类零件数控加工的工艺规划难度。

A method of generate intermediate process models for casing parts based on virtual control surface constraints

In numerical control (NC) machining of a multi-island casing part, establishing accurate machining process model is a key technology to realize intelligent processing of such parts. In order to obtain accurate machining process model of a multi-island casing parts, a method based on virtual control surface constraints to structure process models of a casing part is proposed. Firstly, the introduction of virtual control surface constraints in modeling process is analyzed according to machining characteristics of the multi-island casing parts, and the Lagrange transfinite interpolation modeling theory is given by combining the idea of virtual control surface constraints. Then according to geometrical characteristics of the casing parts, the algorithm for calculating the distribution position and geometric shape of the virtual control surfaces is determined; on this basis, according to the modeling theory of virtual control surface to structure the middle surface, the process model according to cutting depth constraint and plan the tool path for it is determined. Finally, a validation is conducted on a multi-island casing part. The result shows that the proposed method is able to control the geometry of process model effectively according to the distribution of machining characteristics, avoid the geometry of process surface prematurely tending to be complicated caused by handling multiple processing characteristics simultaneously and provide some effective process models for multi-island casing parts in NC machining; to some extent, the difficulty of the process planning for a multi-island casing parts is reduced.