Study On Forming Principle And Controlling Technology Of Burrs In Drilling

Drilling(holemaking) is one of the most time-consuming metal cutting operations in the typical shop, and its application field is more and more wide. As the manufacturing trends for precision and high precision machining, the increase of drilling efficiency and drilling quality is inevitable. While the deformation of drilling burr greatly reduces the drilling efficiency and destroy the surface integrity of precision parts. Therefore, the research on the formation mechanism of drilling burr and its controlling technology will help to promote the development of precision and high precision drilling technology.On the basic of the previous research progress at home and abroad, the theoretical analysis and experimental research were carried out in this paper. The formation rules of drilling burr were revealed after the analysis on the drilling burr formation mechanism,forming process and its influencing factors. Furthermore, a diverse range of measures to restrain and decrease the drilling burr have been advanced. The main contents and contributions of this paper are as follows:The research status and the major problems which remain to be solved of the drilling burr were described. The surface topography and the type of the drilling burr were analyzed,then a drilling burr formation model and the drilling burr formation mechanism were presented.With the use of DEFORM, the formation of drilling burr was simulated, then the all stage of drilling burr formation and the influence of workpiece bottom hole on the drilling burr were analyzed. Combining with the results of simulation, the decisive stage of drilling burr formation was pointed out.An experimental research was conducted to study the influence of the cutting parameters, geometry of the twist drill, material and end-shape of the workpiece on the drilling feed-direction burr, then the fundamental law of the drilling burr formation was revealed. Furthermore, based on the experimental results, the drilling burr formation mechanism was deeply discussed.The main influence factors of drilling burr formation were analyzed, then the basic principles and several common methods of less burr drilling were presented. Based on the theoretical analysis and experimental research, a diverse range of measures to restrain and decrease the drilling feed-direction burr were advanced, such as overlapping workpiece,selecting drilling parameters, adjusting drill geometry, improving drill type, strengtheningthe end material of the workpiece, step drilling and so on. Furthermore, an arc edge step drill was developed, which could restrain and decrease the drilling burr.This research work is a part of National Natural Science Foundation of China project(No.51075192).This paper enriches the basic theory of drilling cutting, drilling burr formation and its’ controlling technology. And it has a certain theoretical significance and practical application value.