| CNC machine tools produce heat during the process,so its key components consequent thermal deformation,thus affecting the machining accuracy.Machining accuracy is the basis of all equipment manufa cturing,so take simple and practical way to ensure thermal error compensation machining precision,meaning the development of major manufacturing countries.After analyzying the thermal deformation on domestic and foreign machine tool precision compensation method,find that foreign machine tool compensation structure is more complex,multi-parameter mathematical model built for demanding precision CNC system,while expensive,which does not apply status of the domestic machine tool industry;domestic crude mad-based compensation is not satisfactory,complicated operation and related requirements,nor popularization.In this thesis,take the Q2W-184 CNC milling and boring machine as the study,first discuss the Q2W-184 CNC milling and boring machine thermal deformation mechanism.The main heat source is static film relative movement of the moving parts produced by extrusion lead calorific value,and because of the larger size of this machine,exposed parts such as large-size bed,slide,headstock and columns,etc.,are good heat dissipation effect,small thermal error with temperature change.The main machined parts as ram and boring spindle,because the boring spindle included in the ram,ram included in the headstock,which are in a closed state,the cooling effect is poor,affected obviously by temperature changes.At the same time the tool from the recent direct impact on the machine machining accuracy,is belong to the key member.In this thesis,after the thermal error measurement of Q2W-184 CNC boring and milling machine without compensating measures,the thermal analysis is carried out: under the condition of continuous rotation speed of 1000 rpm,the measured temperature rise is 24 ℃,the maximum elongation of pillow is 0.31 mm,and the maximum elongation of boring axis is 0.18 mm.Therefore,it is confirmed that the ram and boring axis are affected by the temperature c hange greatly.By selecting the key temperature point test of Q2W-184 CNC boring and milling machine,the three points of the upper surface of the front end of the ram and the three main shaft bearings and the two points of the oil level between the ram and the headstock are the key temperature points.The effect is very large,so these five points is the key temperature collection point for therm al error compensation.The relationship between the temperature and the elongation of the boring spindle with the time is measured and the relationship between the temperature and the time of the boring spindle is measured and analyzed.Using the machine FAGOR 8055 M CNC system with the compensation function,the mathematical function of the relationship between the CNC system can be programmed to read the program.Through the measurement of the key temperature point of the machine,the temperature of the analog signal is converted to digital signal,through the pre-established mathematical function relationship from the temperature variable indirect prediction of thermal deformation error,according to the estimated error by the PLC controller Servo motor dr ive shaft position,so that the NC machine tool coordinate system in accordance with the offset value of the input offset generated coordinates,and thus real-time thermal elongation compensation.At the same time,PLC and PC is connected to achieve dynamic display monitoring.The thermal elongation compensation method with the temperature as the variable determines make the axial length error of the boring axis from 0.18 mm to 0.06 mm,which ensures the accuracy of the tool tip position of the boring shaft and greatly improves the machining accuracy. |
PDF Full Text Request