摘要
装夹布局的合理规划是影响工件加工质量与生产安全的关键因素,为此系统地提出了工件位置偏离的动力学预测模型及其控制方法。首先通过将工件与夹具之间的接触模式等价地转化为线性弹簧-阻尼系统,利用运动学和弹性力学理论推导出工件的振动微分方程,以确定工件在装夹布局中的位置偏离。根据工件与夹具之间的接触为单向这一实际情况,运用胡克定律建立了工件位置偏离的约束条件。通过坐标转换方法,提出在约束条件下振动微分方程的模态分析求解方法,实现工件位置偏离的预测,试验结果表明所提出预测结果与试验结果完全吻合。其次,为使工件位置偏离达到最小,构建工件位置偏离的最小2-范数为目标的装夹布局优化模型,通过以合理装夹布局中工件位置偏离的2-范数为自变量构造个体适应度,提出装夹布局优化模型的遗传算法求解技术。提出的工件位置偏离预测与控制方法,能够避免工件处于非稳定状态下优化模型的求解过程,为复杂工件装夹布局方案的合理设计提供了基础理论。
The reasonable planning of the fixturing layout is crucial to guarantee the machining quality and safety manufacturing. Therefore, the prediction and control method is systematically proposed for the workpiece position error. Above all, by transforming the contacts between the workpiece and fixture into the linear spring-damp system, the vibration differential equation of the workpiece, which can determine the position movement of the workpiece in the fixturing layout, is concluded to obtain the workpiece position deviation according to the theory of kinematics and elastic mechanics. Based on the fact that the contacts between the workpiece and fixture are unidirectional, the hook law is used to formulate the constraint conditions of the workpiece position deviation. According to coordinate transformation method, the modal analysis solution technology of the vibration differential equation is proposed to predict the workpiece position error. A numerical test is demonstrated to validate the prediction results are in good agreement with the experimental data in the reference. And then, in order to minimize the workpiece position deviation, the optimal model with the objective of minimizing the 2-norm of the workpiece position deviation is proposed for the fixturing layout. According to the workpiece position deviation in the reasonable fixturing layout, the individual fitness is defined by taking its 2-norm as independent variable. Thus, the genetic algorithm can be skillfully developed to solve the optimal model of fixturing layout. The presented prediction and control method of workpiece position error can avoid the solution of the optimal model under the condition of the workpiece in unstable fixturing. It can provide a basic theory of fixturing layout design for the complex workpiece.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2017年第1期110-120,共11页
Journal of Mechanical Engineering
基金
国家自然科学基金(51465045
51165039)
深圳市科创委基础研究(JCYJ2014050917410668)资助项目
关键词
装夹布局
工件位置偏离
振动
优化
遗传算法
fixturing layout
workpiece position deviation
vibration
optimization
genetic algorithm
