Structure Optimization Of The Hydraulic Bearing System's Plank Subordinate To The Large Ultraprecise Machine

In the domain of national defence industry and civil optical-mechanical-electrical product, the large aspherical part have a very important application, and the large ultraprecise machine is the key equipment to process these part. In order to guarantee the machining accuracy of these part, the hydraulic principal axis system is applied in the large ultraprecise machine in the world presently, to ensure the principal axis system's high rotating accuracy and carrying capacity.The up plank is a key part in the hydraulic bearing axis system, it would occur micrometer relative displacement in the direction of oil cavity pressure, which could be many micron. In this condition, the thickness of oil film in the main axis system is changed, so the key qualification of the bearing system is affected, such as rotating accuracy and rigidity.Based on theoretical analysis to the up plank's distortion, the finite element method calculation model is established, by the certification of specific experiment, the validity of this FEM model is demonstrated. In the condition of the hydraulic pressure is 1.0,1.5 and 1.8MPa, the relative displacement of the up plank in the hydraulic pressure direction is tested using the inductance meter. It is indicated that when the oil pressure is 1.5Mpa, the largest relative displacement is 18.0 micron, which has a well agreement with the FEM calculation result.In the foundation of previous analyse, the APDL finite element calculation method is used to research the up plank's relative displacement in the direction of oil pressure, which is related to three important structural parameter, such as the distance between the oil pressure's centerline and the bolt hole,the thickness of the up plank,number of the connecting bolt. In succession, the optimization design method is used to get a better structural of the up plank, whose largest displacement in the oil pressure direction is 2.6macro when the pressure is 1.8Ma, this value could attain the performance design desire of the large machine, so the rotating accuracy and loading capacity of the large aspherical machine is guaranteed.