Study On Some Key Technologies In Post-processing Of Five-Axis CNC Machining

The post-processing technology is one of the key CNC machining technologies, which is the tie connects CAD/CAM system and machinery manufacturing. The result of the post-processing not only affects the quality and efficiency of manufacturing, but also affects the machine tool work reliably directly. Five-axis CNC machining technology becomes more and more important in the machining of complex surface and high preeision parts because of its special advantages. Owing to the complexcity of the motion between the tool and the workpiece, it is very difficult to develop post-processing system. There is no algorithm suitable for nonlinear error and feedspeed control in the existing commercial post-processing software, which restricts the advantages of the5-axis CNC machining.In this paper, the5-axis machining center, a three-axis vertical machining center with a dual rotary table, as the study object, do stuy on the post-processing in5-axis machining and the complex surface’s program. The following content is researched:(1) Based on the characteristic of five-axis CNC machine tools’structure, by means of analysis of the kinetic model of five-axis CNC machine tools, solve the motion of the machine tools’axes.(2) Analysis the principle of nonlinear error in five-axis machining,model the nonlinear error and establish the simplified model of nonlinear error and its control strategy and verify the validity of the control strategy; proposes some influencing factors of non-linear errors.(3) Do a study on the principle of5-axis machining federate. In order to solve the inconsistency between the actual feed speed of the cutter relative to part surface and the speed defined in the NC codes, this paper proposes a correct-factor transformed by different dimension of angles and displacement in a post-processing speed control algorithm. With the correct-factor, the relationship between the peed defined in the NC codes and actual feed rate is derived. A new feed rate control strategy is acquired when combined with the actuator limitation. (4) Based on the correspondence betweem NC code and CLSF, the article develops a new software of post-processing for5-axis CNC machine with dual rotary table with the software of VB. The new software can not only do coordinate conversion but also have suitable algorithm to contol nonlinear error and federate. A post-processing parameter database is builded at the background of the software for Easy to use.(5) Based on impeller, the tool path of rough and finish machining are scheduled. Using the post-prosessing software the article developed, NC codes are getted. By simulation and actual test and analyzing the result of the test, verify the validity of the algorithm to post-prosessing the article posesd.The research of the paper has some important significance at resoving the problem of post-processing and improving the effectivity of five-axis CNC machining programming and provides clues for development of post-prosessing software of other five-axis CNC machinings.