Research On Key Technologies In Five-axis Turn-mill Complex Machining

Multi-axis turn-mill complex machining technology is a kind of advancedprocessing technology integrates modern advanced control technology, precisionmeasurement technology and CAD/CAM application technology based on traditionalmechanical design and precision manufacturing technology, as a new technology foradapting to modern manufacturing industry needs, more varieties, small quantity andindividuation development. It’s also included as one of the key tasks in CNC importantresearch in the national science and technology major projects of "High-End CNCMachine Tools and basic manufacturing equipment". For multi-axis turn-mill complexmachining control function requirementsto carry out research of high-end CNCmilling machining dynamic conversion function, five-axis machine tool kinematicslibrary, five-axis kinematics calibration and optimization of key technologies. The maincontributions of this dissertation are summarized as follows:1. Research on peripheral surface transformation for turn-mill complex end surface.For the problem of turn-mill complex machining complex kinematics transformation,proposed an approach based on modular machine tool data parameters dynamicconversion method on the basis of researching the face end machining processingcharacteristics and corresponding kinematic relationship to achieve polar coordinatemotion dynamic transformation between the Cartesian coordinate system and themachine tool polar coordinate system. Based on the existing motion trajectory planningmethod, dynamic conversion is completed in real-time interpolation to achieve turn-millcomplex polar coordinates machining functions. For C-axis motion overload problem inpolar coordinate interpolation extreme regional, provide polar coordinate interpolation smoothing process method in extreme regional based on the CNC system of C-axisconstraint coefficient α and transition coefficient β to achieve the smoothing pathinterpolation within the polar coordinate interpolation region. Resolved simplifyprogramming, improve processing efficiency.2. Research on cylinder surface transformation for the machining of cylinder jacketcurves. For the problem of turn-mill complex machining complex cylinders kinematicstransformation problems, proposed an approach based on modular machine tool dataparameters dynamic transformation method on the basis of researching the cylindermachining processing characteristics and corresponding kinematic relationship toachieve cylindrical coordinate motion dynamic transformation between the Cartesiancoordinate system and the machine tool cylindrical coordinate system. Based on theexisting motion trajectory planning method, dynamic transformation is completed inreal-time interpolation to achieve turn-mill complex cylindrical machining functions.Using structure XZCY expanded the cylindrical surface as the programming plane toslot cylindrical interpolation programming, interface and expanded surface of the slotvertical exactly. But with the cutter less than the diameter of slot processing flat slottingtool radius compensation, then the tool radius compensation amount in cross sectionwill be changed. By converting radius compensation into length compensation andlateral radius compensational in expanded plane and the introduction of auxiliary Y-axismotion compensation, linear displacement compensate compensation vector change inthe circumferential direction, ensure the wall perpendicular to the bottom surface of theslot, and nothing to do with the using the tool radius.3. Research on five-axis tool center point interpolation control method based on feed rate constraint. According to the tool shape and the desired tool angle, Multi-axismachining tool center point control allows user to directly program tool center path.CNC system will compensate for control point automatically in real time. Which canensure that the tool center is located in programming track, which is independent ofthe used tools or machine type. However, because of the rotary motion, between themovement of the tool center point and the actual machine axis exists non-linearrelationship, it is very difficult to control the movement of tool center point andmachine axis simultaneously in the motion controller. To solve this problem, completedthe real-time kinematic conversion within queues motion command and motioninterpolation queues based on the programmed feed rate according to the existingfive-axis motion control, to achieve real-time kinematic compensation before or afterinterpolation, and interpolation control method for high-speed mode and high qualitymode.4. Research on multi-axis machine tool calibration method based on complexgrouping of axes. First, in order completed verification and optimization of five-axismachine RTCP parameters fast and efficiently, automatically calculated for eachrotation axis direction vector and the position vector of the center of rotation byanalysing the tool center point position from online measured with regression analysis,based on the five-axis kinematics library and ISO230international standard to proofreadfive-axis RTCP function parameters and compensate errors of machine structure,reduce the difficulty of five-axis machine debugging and improve the RTCP machiningprecision. Second, according to composition characteristics of multi-axis turn-millcomplex machine HTM63150iy interpolation axis, combination of five-axis machine tools such as XYZ BC1, XYZ BC2, XYZAB(C1&C2)are divided. For eachcombination of the divided, the corresponding errors of multi-axis machine structure aremeasured simply. Finally, by structure error compensation for CNC system relatedfunction parameters to reduce cost and ensure precision effectively.