基于热力耦合变形的机床主轴公差建模方法研究

Research on Tolerance Modeling Method of Machine Tool Spindle Based on Thermo Mechanical Coupling Deformation

机床主轴的公差建模很少同时考虑切削力与摩擦热耦合变形的影响,导致公差模型与工程实际存在较大差异,难以保证机床主轴加工精度的问题。为此,研究一种基于热力耦合变形的机床主轴公差建模方法。根据机床主轴的实际工况,运用小位移旋量理论表达特征的几何变动,建立主轴原始几何误差的Jacobian-Torsor公差模型;根据几何变动修正Jacobian-Torsor公差建模,增加典型配合特征的公差变动表示模型;利用ANSYS计算主轴在切削力与摩擦热耦合作用下的变形量;将结果引入修正的Jacobian-Torsor模型,得到热力耦合变形下的机床主轴公差模型。结果表明:主轴与轴承的装配间隙在径向y方向上的平动量减少0.009 mm,沿着径向的转动量减少0.000 8 mm,过盈增大,加快了主轴的磨损,影响主轴的回转精度。所设计的模型可为机床主轴的公差设计提供参考,并可预测和改善主轴的工作性能。

The influence of the cutting force and the frictional thermal coupling deformation is rarely considered simultaneously when conducting tolerance modeling of machine tool spindles,resulting in a great difference between the tolerance model and the engi⁃neering practice,and it is difficult to guarantee the machining accuracy of machine tool spindle.Therefore,a tolerance modeling method of machine tool spindle based on thermal coupling deformation was studied.According to the actual working condition of ma⁃chine tool spindle,the Jacobian-Torsor tolerance model of original geometric error of spindle was established by using small displace⁃ment screw theory to express the geometric change of feature;the Jacobian-Torsor tolerance model was modified according to geometric variation,and the tolerance variation representation model of typical fit features was added;the deformation of the spindle under the coupling of cutting force and friction heat was calculated by using ANSYS;the results were introduced into the modified Jacobian-Torsor model to obtain the tolerance model of machine tool spindle under thermal mechanical coupling deformation.The results show that the translation of the assembly clearance between the spindle and the bearing in the radial y direction is reduced by 0.009 mm,the rotation along the radial direction is reduced by 0.0008 mm,the interference is increased,the wear of the spindle is accelerated,and the rotation accuracy of the spindle is affected.The designed model can provide reference for tolerance design of machine tool spin⁃dle,and the performance of spindle can be predicted and improved by using the model.