Research Of Theory And Approach For Spindle’s Dynamic Unbalance Detection Of NC Milling Machine Tool

The dynamic unbalance of spindle is a very important factor which leads to rotationerror, and spindle’s rotation error reduces the quality of the work-piece. However, theactive NC machine tools doesn’t have device to test the dynamic balance state of theirspindle which brings about uncertainty to assessment of the machine tool’s cutting ability.At the same time, with the modern numerical control technology continuing tomature and be in application, the use of modular machine tools and the machining centerincrease day by day. In use process of this kind of machine tool, tool changing action orwork-piece loading automatically is very normal; On the other hand, the spindle speed ofmodern numerical control machine tool continuously increases. These changes bringsevere challenges to the dynamic balance accuracy of spindle and tool system.Therefore, it is urgent to develop a method to test and compute spindle dynamicbalance.This paper presents simple discussion of spindle dynamic unbalance test technologyfor NC milling machine tool and its application in CNC. Also, this paper tries to developsome practical and efficient computing method and mathematic model.In particular, the main content of this paper includes the following four aspects.First, research the structure characteristics of common spindle, the spindle bearingstiffness calculation method, and basic mechanics characteristics of spindle dynamicunbalance. Combined with ISO1940-1:2003, the precision of the main shaft dynamicunbalance level is discussed.Second, for special phase signal in spindle dynamic unbalance test, developcorresponding separation and shaped technology. Research common problems ofseparation process for roundness error and rotation error. Describe traditional computationmethods for phase and amplitude of base frequency signal and the shaft center orbit.Thirdly, simplified mechanics model of spindle dynamic unbalance and relatedcomputation method.Finally, develop offline processing software for NC milling machine tool spindledynamic unbalance.This paper focuses on active duty CNC milling machine, and makes an organicintegration for vibration signal processing of spindle dynamic unbalance and spindledynamic unbalance identification and so on. It provides a basic rationale for theapplication of above-motioned technology in CNC in the near future.