Parallel Computation Of Synthesis Errors Compensation For CNC Machine Tool Based On MDO Theory

Many researches prove that geometrical errors and thermal errors are major effective ones in all kinds of errors that can influence high precise CNC machine tools. And about 45% of errors are thermal errors, which has become the biggest error source. That means, only compensating geometrical errors can not satisfy our requirements, we need synthetical errors compensation to improve machining precise. Synthetical errors can be decreased by improving the structure of machine tools, but many restrictions make our problems cannot be solved by this method. Then synthetical compensation comes into many experts'eyes as it is an effective and low-cost way to improve machining precise, and that is why this paper to research compensation of synthetical errors for CNC machine tools systematically.At first, the paper analyzes CNC machine tools, the complicated system, by Multidiscipline Design Optimization Theory, or MDO. CNC machine tools are divided into five parts, including synthetical errors system, geometrical errors system , thermal errors system, loading errors system and servo optimazating system, and the paper uses Coordinated Optimization as the optimal model of synthetical errors compensation.Then, based on Kinematical Theory of Multibody System, it creats the synthetical error compensating model for CNC machine tools. Taking ZK7640 CNC machine tool for example, it describes topological structures, transpositional matrixes of ZK7640 machine tools, and determines equations for tool's tracks. It gets the relationship between computing values of geometrical errors and thermal errors by analysing the method of measure and calculation.It introduces and analyses the GA, and put forward the CNC machine tools'codes searching method based on GA. The new method for precise codes comes true.Finally, using VC++ 6.0 to write a synthetical compensation software for ZK7640 machine tools based on MDO, which is able to determine the precise G code that meet users'requirements and simulate ideal, factual and precise paths of tools for showing the results of synthetical errors compensation.