Simulation And Ananysis For Turning-milling Muti-task Machine Tool Feed Systems

The turning-milling multi-task machine tool is one key equipment in metal machining,such as the machining of crankshaft and blade.The feed system is the important assembly unit which has great influence to the machine tool performance.So the feed system needs high rigidity and excellent dynamic character.The paper studies the status of feed system based on the dynamic and position performance.Then the paper clarifies the point which will be focused on following.This paper builds up the multi-task machine tool model in TOP-DOWN design method by using the CAD software Pro/Engineer and makes the calculation process of all X.Y.Z feed axis.According to the demand of lifetime and load capacity,the paper selects the proper ball screw with 32 mm diameter and two kinds of couplings which are quincuncial type coupling and diaphragm type coupling.After the establishing of dynamic mathematic model,the torsional rigidity and press rigidity are analyzed to find out the influence factors.Then all the rigidity numbers are calculated according to the rigidity formula.And the paper also discusses the influence of press rigidity which cause by the pre-stretch force to the ball screw nut and support bearing.After the building of rigid-soft coupled simulation model in CAE software ADAMS,the paper analyze the feed system dynamic performance influenced by the ball screw diameter,coupling type and pre-stretch force.Based on the simulation,the paper points out that,the dynamic performance can be improved by increasing the ball screw diameter to 40 mm,adopting quincuncial type coupling in X.Y axis and diaphragm type coupling in Z axis.After the calculation of force on support bearings,in order to reduce the load on bearings of the slant X axis,the structure of X axis is modified by using hollow cooling ball screw.For further studying the influence of ball screw diameter,coupling type and ball screw pre-stretch force to the feed systems,the paper also make the analyze of the position accuracy and machining quality.By using laser interferometer to produce feed system moving position curve and using contour roughness instrument to produce the machined part contour curve,at last the paper makes the conclusion when using bigger diameter ball screw with 40 mm diameter,adopting quincuncial type coupling in X.Y axis and diaphragm type coupling in Z axis,adding proper ball screw pre-stretch will get better position accuracy and machining quality.