Measurement And Monitoring Technology Of Deep-hole Internal Grinding For Cylinder With Large Depth-diameter Ratio

The actuator or cylinders with deep holes and thin-walled structures are the key parts of the undercarriage.The cylinder is made by some hard processing material such as high-strength steel.The requirement of processing accuracy and the difficulty of machining the deep hole have become the challenge for the aeronautical manufacturing enterprise.The cylinder with complicated cavity has some step surface and transition arc.It is more difficult to process the parts with hole diameter less than 100 mm and depth-diameter ratio greater than 10.In the actual processing,the grinding is often used as the last process to guarantee the accuracy requirement.At present,the deep-holes of cylinders are usually processed on the grinding machine by hand or the ordinary CNC,but there exist problems such as low machining accuracy,low consistency at surface,low production efficiency,high working intensity and low qualification rate.Besides,the existing grinding machine has limited machining ability,which is difficult to meet the deep-hole process needs of the parts with hole diameter less than 100 mm and depth-diameter ratio greater than 10.There are many limitations.The stiffness of the grinding bar is poor and its rotation speed is limited.In addition,it's incapable of conducting on-machine measurement,effectively evaluating the processed parts,as well as measuring some features such as arc radius.Moreover,there still lack necessary monitoring means for grinding wheel setting and monitoring the state of grinding,which mainly depends on vision and hearing of operators.In view of the above-mentioned processing facts,the thesis mainly studies some key technologies including the structure design of the grinding machine,on-machine measurement and on-line monitoring.Finally,the study integrates the key technologies to develop a measurement-monitoring integrated grinding machine.The specific research contents are as follows:(1)The structure of the deep-hole internal grinding machine is designed.The main components and motor units are introduced,and on this basis the electricity control system is developed.(2)On-machine measurement technology is studied.The measurement hardware system is constructed.The measuring scheme is put forward and the measuring path is discussed.Stylus position correction and the measurement error compensation technologies are researched.Meanwhile,the measurement system software is developed,including macro program and measurement data analysis program based on MATLAB.Then,the measurement experiment is conducted to verify measurement accuracy and reliability.(3)Acoustic emission(AE)testing is studied.The AE monitoring system is constructed and its connection with machine control system is established.Then the monitoring experiments are conducted for grinding wheel setting and anti-collision function.(4)Finally,experiments are conducted on the grinding machine tool to verify holistic machining ability.