Moritoring Technology For CNC Machine Tools With Its Application

The wide application of CNC machine tools may bring a huge amount of processing information to a manufacture enterprise during production.How to collect these important information from the CNC system effectively and monitor the machine tools on-line has become a major problem that a manufacturing enterprise is facing.First,the current available data collection methods of CNC machine tools are studied,such as the data collection from PLC and electrical circuit,by RS232 serial port and macro instruction,method based on OPC specification,and method with FOCAS.The feature and application of these methods are discussed.One overall framework of CNC machine data collection system is presented based on the research,which includes the communication network architecture,software architecture and system database.The system will integrate the tradictional data acquisition card,RS232 interface and technology based on OPC,as well as its expansibility in the future.Special for the variation in operation and cycle time of CNC milling,turning and cutting machines,a combination data collection scheme is put forward,which combines acquisition cards and NC macro.This method can effectively solve the problems of some not support Ethernet network CNC equipments and save the cost in implement MDC.The OEE index and the workshop cost accounting method are also studied.The OEE calculation method which based on the real-time running state of the CNC machine tool is improved,and the OEE index is connected with the shifts,personnels and WIP.At the same time,the paper also analyzes the important role of NC machine tool real-time data acquisition system in cost accounting.Through the processing and running time of the actual machine tools,the distribution of the actural processing time of parts can be refined,which will give some scientificial and substantial data for workshop in production improvement.Finally,a MDC experimental software with ASP.NET development platform and SQL Server2008 was developed,which is tested by many CNC machine tools in the laboratory.