Papers by Author: Qin Feng Li

Abstract: The burr formation and control is one key technology of achieving precision and ultra-precision machining and automatic machining. Based on the theory of system engineering, the metal cutting burr formation, control and removal technology system are constructed in the paper. Then, the basic principles of burr control are presented. Combined with precision and ultra-precision machining and automatic machining, the active control methods and technologies of burr are presented. They are the modified design of parts structure, the option of tool geometry parameters, the adjustment of cutting data and processing technologies optimization etc. So, these methods lay a solid foundation on achieving minimum burrs.

Abstract: The Cemented carbide cutting tool is widely used in more machining factory, the 5 types of cemented carbide materials: YT30+Ta, YTS25, YH1, 726 and 758 and Selected to make brazing and cutting test. The experiment results shown that: (a) the hardness of cemented carbide cutting tool after being brazed does not change, redoes HRA0.1~0.2; (b) YT30+Ta, YTS25 types of cemented carbide could be brazed using 105# solder, brazing quality could be very well; (c) Wear characteristic of machine-clamping and brazed cemented carbide cutting tool is normal and hardly change in T<150 minutes. The study makes theory and experiment foundation to widely use cemented carbide cutting tools.

Abstract: In this paper, the forming processes, main effect factors and change law of the cutting direction burr in orthogonal cutting have been studied and related theories are analyzed based on the cutting experiments. The result shows that the forming processes of cutting direction burr consist of normal cutting, flexure deformation of end surface of workpiece, plastic effect, continuous cutting and shear-break separating in orthogonal cutting. And a new phenomenon was found that cutting direction burr is formed with the shear-break separation of the chip and workpiece machined surfaces. In addition, the size of cutting-direction burr varies with workpiece materials, cutting parameters and geometric parameters of cutting tool. The study may be important science and practical value in order to control and reduce cutting burr in precision machining.

Abstract: Grind-hardening machining is not only a complex process coupling mechanical, dynamical and thermal effects, but a process containing distinct changes of microstructure and properties of the workpiece grinded surface layer. Under the defined experimental conditions, an empirical formula was constituted to describe the relation between hardened layer depth and grinding parameter of grind-hardening layer, and the multi-parametric optimization was conducted. A commercial FEM software package was used to simulate the grind-hardening process. The distribution and variation characteristics of the temperature and microstructure in the grinded surface layer of workpiece were obtained and the forming mechanism of the grind-hardened layer is revealed.

Abstract: A forming model of the feed-direction burr for drilling process is made in this paper. The feed-direction burr formation is studied by experiment. The related theories are analyzed. The influence factors of the feed-direction burrs are pointed out. Furthermore, a certain number of measures to prevent and decrease the burr in drilling process are advanced.

Abstract: Based on grind-hardening experiments, the two side-direction burrs were studied. Three main stages (burr generation, augmentation and formation) in the burr yielding process were clarified and the varying laws of burr morphologies and dimensions were systematically revealed. In turn raises, some new technologies, processes and methods of actively controlling burrs were put forward.

Abstract: With the development of machine manufacture science and technology toward precise, quality evaluation of precision parts has put forward higher request. Problems are pointed out in this paper based on comparison and analysis of burr standard at home and abroad. This study suggests the viewpoint of edge quality of precision parts and provides the fundamentals for enhancing edge (burr) quality according to items such as economic cost, technology level, manufacture level, personnel technological capability and production management level. These have important theoretical value and applied prospects for further enriching and perfecting burr standard, promoting precision machining and automatic machining technology.

Abstract: The cutting-direction burr is one of the important factors that influence the edge quality and performance of precision parts. The cutting-direction burr formation process is simulated with DeformTH3D. The mechanism of cutting-direction burr formation is analyzed in terms of the results of the simulation. The negative shear zone and initiation negative shear angle are discussed too. Study results show that the deformation of
CDE is an important factor affect the cutting direction burrs’ size and shape.

Abstract: Based on the orthogonal cutting experiments, the two side direction burrs in metal cutting were studied. In this study, the cutting model of two side direction burr formation and translation is established with plane stress-strain theory. The main laws of formation and change of burr in size and type in orthogonal cutting are revealed, and it is confirmed by experiment results, which first realizes control of the forming and change of the two side direction burr in metal cutting operation.