中文摘要：

龙门式铣镗加工中心床身X轴与横梁Y轴垂直度超差是其垂直度超差的主要方面。对其成因进行分析后发现横梁重力是导致超差产生的重要原因之一。采用有限元分析技术对横梁上11个位置在重力作用下变形进行仿真分析，得到上下导轨基面与定位面的相应变形数值。由此得到基面与定位面应该加工成的形状后对横梁现有加工工艺进行改进。进行工艺补偿后通过试验发现，现有工艺产生的直线度误差基本得以消除，垂直度误差降低了85％，进而说明了工艺改进方法对于垂直度超差问题解决的有效性和可行性。

英文摘要：

Perpendicularity out-of-tolerance of gantry milling boring machining center of lathe bed X axis and vertical beams Y axis is the main aspect of perpendicularity error.To analyze the causes and find, beam gravity is one of the important reasons which caused the error.The finite element analysis （ FEA） technology was used to research that 11 positions gravity deformation of the beam. The corresponding deformation values of up and down guide rail base plane and location were gotten.As a result, the shape of base lev-el and location which should be processed is obtained.Thus, the existing machining process of beams was improved.Through the test finding that after compensation process, the straightness error of the existing process was eliminated basically, and perpendicularity er-ror was reduced by 85%.It is illustrating that the process improvement method for the problem solving has feasibility and effectiveness.