Research On Technology Of Assembly Reliability Of CNC Machine Tool

The quality of domestic CNC machine tool is far away from abroad, mainly embody in the aspect as low reliability、poor accuracy stability and e tc. As the principal part of NC machine tool manufacturing, assembly process is very significant to the reliability of prod uct. Aiming at researching defects and other factors influencing assembly reliability in the assembly process, it is of great theoretical and practical significance to the in-depth study of assembly reliability of NC machine tool.This paper combined with National Major Scientific and Technological Special Project(“Reliability Promoting of High- grade Domestic NC Grinder Machine”, No.2013ZX04011-013, and “High Performance and Flexible Production Line of Precision Machine Tool Spindle ”, No.2013ZX04012-051), selected home- made NC machine as the object, making the assembly process as the breakthrough point, analysis the assembly defect, forming theoretical foundation of NC machine tool assembly reliability research by integrating reliability into traditional assembly process, formulated the Assembly Process Driven by Reliability. The main work is as follows:①Defining the concept of assembly reliability of NC machine, introduced assembly process, analyzed relationship between assembly reliability and assembly process, at the same time, define the concept of assembly defect and analyzed relationship between assembly defect and failure of product. Related concepts of Assembly Process Driven by Reliability and its formulating flows were introduced. On the basis of these, the research theory of assembly reliability of NC machine tool was built.②On the basis of analyzing assembly defects of assembly process, taking the NC grinder as an example, got the main failure modes and causes of the key functional component wheel head with FMEA and FTA, made the quantitative analysis of the original data using Entropy and Rough Set, extracted the key failure sources influencing assembly reliability of wheel head, taken some actions to prevent them from happening, so the reliability of assembly process can be guaranteed.③Taken assembly process as the research object, the FGSPN model of NC machine assembly process was built and made an quantitative calculation for assembly reliability. The wheel head of grinding machine was taken as an example, the assembly process plan driven by reliability was established to guarantee the assembly reliability according to the analysis result.