Study On Data Acquisition Technique Of CNC Unit Based On OPC Standard

CNC machine tool is an electromechanical integration control equipment with high precision and many other characteristics, such as high processing efficiency and intelligentialize. Due to its complexity, the maintenance after breakdown offen costs extra time and efforts, thus the production plan will be seriously delayed. Remote monitoring and fault diagnosis system of CNC machine aims at finding out the abnormality of machine tool in time, so as to avoid more losses.Data acquisition is base to monitor CNC machine tool and locate fault, because accurate, effective and timely data guarantees effectiveness of monitoring and diagnosis result. This project is to build a CNC machine remote monitoring and fault diagnosis system for the overall goal, and it’s to be implemented in three phases: CNC machine data collection, network platform building and failure diagnosis algorithm research. Therefore, in this paper relevant research work focuses on the data acquisition and software development carried out as follows:1. Data acquisition method is certained for CNC machine tool. The hardware structure and the software system was investigated, and considering the application object in the task—SIEMENS open architecture CNC system SINUMERIK 840 D, the method based on OPC specification was chosen to accomplish the data acquisition.2. Massive process-data processing method was researched. Considering that the CNC machine tools in workshop produce massive process-data at all time, a new massive data processing algorithm based on Swing Door Trend(SDT) was proposed, and the testing results shew the advantage of this new algorithm.3. Data acquisition software was designed. According to the OPC specification and in conjunction with the actual situation of Siemens 840 D, the data acquisition software was coded in C#, including the base functions of data acquisition, massive data processing(hybrid programming with Matlab) and database communication. After that, the software was embedded into HMI with SIEMENS supports.4. The data acquisition software was tested. Two experiments about the data acquisition software needed to be done, one was the function test to find out whether this software can gain the right machine data. The other one was the performance test which focused on the influence to the CNC machine due to this embedded software. Therefore, this paper carried out both functional and performance test, and the results shew that this software completed the intended functions and had few influence to CNC machine.