Three-dimensional Tolerance Modeling and Precision Analysis of Flexible Body Based on the Assembly Load

The traditional precision design only considers the influence of geometric tolerances while not involving the parts deformation of under assembly load. In order to ensure the reliability and stability of mechanical system in the work process, not only to ensure that the parts have a good design performance and manufacturing quality in the process of product design and manufacturing, more important is to ensure the matching performance of the components in the assembly process. It takes a horizontal machining center as an example, the deformation data information of the parts under load effect is obtained by the finite element method. A comprehensive three-dimensional mathematical model for load deformation deviation of the parts is established based on the small displacement torsos theory, the homogeneous coordinate transformation theory and the surface authentication idea. The analysis results show that the deformation deviation of the parts under assembly load displays the trend of transfer and accumulation, and the cumulative deformation deviation at the end of the system reaches-0.024 9 mm. Therefore, the influence of the load deformation deviation on the precision of the mechanical system cannot be neglected. In the design stage of 3D tolerance analysis, the dimension tolerance, the geometric tolerance and the load deformation deviation on the assembly precision of the mechanical system should be considered comprehensively, which will form a mechanism of coordination and protection for the precision of the whole machine, and then to provide theoretical and technical support for improving the overall performance of complex precision mechanical systems.