Research On Synthetical Error Compensation Of Heavy-Duty NC Floortyped Milling And Boring Machine Tool

Heavy CNC milling and boring machine is suitable for large size partsmachining and the application of this machine tool is limited due to its inaccuracy.It has important practical significance to control and compensate error effectivelyfor machine tool. However, the research on accuracy measurement and errorcompensation for machines is inadequate.In this paper, traceable error analysis of heavy-duty CNC milling and boringmachine is carried out. The coupling mechanism of geo metric and thermal error isintroduced. The synthetic error model containing geometric and thermal couplingerror and dynamic error is established. The error sensitivity matrix is developed.The error measurement uncertainty is analyzed and the method for precisionretaining is developed. Error measurement in multi-stat ion is proposed withworkspace segment based on laser tracker. The distribution of measurementuncertainty of components is discovered according to the experimental result.Thermal drift error is the main error when the temperature of machine tool raiseslittle through machine thermal experiment, and themal drift error of spatial point ismodeled. The effect of machine repeatability on uncertainty is analysed. Themeasurement uncertainty is estimated by Monte Carlo method according to lasertracker. In order to decrease measurement uncertainty, the measurement systemstation is optimized. The measurement in multi-station is proposed with workspacesegment, which are proved validity by co mparing with experiment result.Geo metric error is identified based on measurement in multi-stat ion.Sensitivity of volumetric error about geometric errors is analysed, as well as theinfluence of spatial dimensions on sensitivity based on error sensitive matrix. Anerror identification methodology based on four-line measurement and part icleswarm optimization(PSO) is proposed. The particle swarm optimization(PSO) isbrought in. The squareness error, linear displacement error, angle error are identifiedrespectively. The method is proved validate through co mparing with the resultsmeasured by laser interfero meter.The tracking error of the servo system and the circular trajectory contour errorare modeled for identifying error parameters. The circular trajectory distribution isanalysed by actual measurement results of XY circle. The method for decouplingdynamic error and the quasi static error is researched. The parameters of servosystem are identified based on contour error model and Tracking error decoulped.The prediction accuracy is verified.The prediction accuracy of sythetical error model is verified based on theerror parameters identified. Volumetric error in Z-axis is analysed based on finiteelement method(Anasys) and experiment. The source of Z-axis thermal drift erroris discovered based on the establishement of the error chain o f thermal deformationof the spindle box. The mature commercialization error real-t ime measurement andcompensation system is developed based on Invar alloy rod.Based on error co mpensator developed for Simense NC system, the volumetricerror is compensated, which demonstrates the compensation validity by comparingvolumetric error withouth compensation. The dynamic matching time is adjustedaccording to servo parameters identified, which leads to 80% decrease of contourerror. The application research of thermal dirft compensation system for SimenseNC system is introduced. Thermal drift error co mpensation system is verifiedstability by experiments. Synthetic error compensation technologies are applied inheavy-duty milling and boring machine too l. The machining error is decreaseddramaticly for a total reduction of 35% after compensation.