Papers by Author: Min Li Zheng

Abstract: Mould surface loading state is one of the most important factors which would affect the mould performance in the course of service. According to the established hardened steel milling surface geometry model, a bending forming numerical simulation of hardened steel milling is conducted, the influence law of service process surface load state is analyzed under machined surface geometry structure which is formed by different milling parameters. The research results show: surface load concentrated area is mainly focusing on mould edge transition and fillet in the course of service; the surface geometry structure has an important influence on the mould service load in the course of service, service load more smaller which is more helpful to improve the mould service performance in the course of service.

Abstract: The service performance is seriously effected by milling machined surface integrity of auto hardened steel mould. Basing on the microscopic damage evolution theory and hardened steel mould material micro-voids cell model, according to the service process load condition of hardened steel milling machined surface, surface microscopic damage evolution analysis had been conducted, surface evolution characteristics was obtained under different shapes void cell. Through comparative analysis the change law of damage evolution internal variable under different shapes void cell can know: respect to the ideal spherical, when the change of void volume fraction and the degree of matrix material yield were considered, the oblate hole more faster and the prolate hole more slower, which provide a further prediction for surface damage.

Abstract: This paper proposes a method to choose machine resources in order to realize the on-demand use of machine resources in cloud manufacturing environment. A convergence mode of the machine resources is described and the selection process is given. A multi-level matching process of machine tools is proposed. Different matching methods are designed for different parameter types of machining tasks and machine resources, and then machine resources are screened according to the requirements of machining tasks to form the machine resources candidate sets. Then a multi-objective optimal selection model of machine resources is constructed, regarding minimization of costs and time and maximization of service quality and reputation as the target, which is solved by using genetic algorithms. Finally, the algorithm is analyzed and validated with an example, and a kind of solution thinking and method is provided to select machine tools in manufacturing cloud environment.

Abstract: Residual stress ,with the branch of type, size and direction, is defined as the stress state which exists in a body after all the external loads are removed [1].According to the mutual influence scope size,residual stress can be divided into macroscopic residual stress and micro residual stress. Cutting residual stress is mainly caused by mechanical stress, thermal stress and phase transformation.

Abstract: Ti6Al4V has great affinity with tool material in machining process, which easily leads to tool diffusion wear. Turning experiments were carried out to study cutting temperature and pressure at tool-chip/workpiece. Based on the analysis, a scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS) was used to analyze tool wear morphology. The affinity of tool and workpiece material using the Ti-W, Ti-Co diagram was also studied to elaborate the diffusion mechanism in this present study. The results shows that the cutting temperature is very high and the temperature increases with the increase of cutting speeds in machining Ti6Al4V. At the contact area, the highest temperature is located in tool rake face near to tool tip. The resilience of workpiece results in serious attrition between tool flank face and the machined surface. The highest pressure is located in tool flank face near to tool tip and the pressure in tool-workpiece interface is much higher than that in tool-chip interface. Under the high cutting temperature and high pressure at tool-chip/workpiece interface, diffusion occurred both at tool rake an flank face in machining Ti6Al4V. Because of the higher temperature at tool rake face diffusion at tool rake face ia more sever than that at tool flank face.

Abstract: titanium alloy cutting force testing experiment of end-surface turning is made, and spectrum character is analyzed by obtained data of cutting force experiment, and ten the influencing rule of cutting parameter on cutting force character is discovered; using the similarity between tools vibration character and cutting force spectrum character, and based on obtained data of machined surface roughness testing experiment, the two characteristic parameters of vibration frequency and amplitude value relative to work piece is calculated, and the relationship curve between cutting parameters and tools vibration character parameter is established is this paper.

Abstract: The machining efficiency of titanium alloy Ti6Al4V is low and the tool wear is serious. In this paper, uncoated carbide tool and two kinds of coated cemented carbide tool were used for dry turning titanium alloy. The experiments used CCD Observing System and the EDAX analysis of SEM to study tool wear mechanism and analyze the cutting performance through tool life, cutting force and cutting temperature. The results show that the main wear reasons are adhesion, diffusion and oxidation wear. For coated tool, the coating peeled off first, and then tool substrate damaged. Compared with coated carbide tool, the uncoated carbide tool with fine grain has longer tool life and lower cutting force and cutting temperature. The changes of cutting force and cutting temperature with cutting speed are not obvious when using the ccomposite coating (TiAlN and AlCrN) carbide tool. The results can help to choose tool material reasonably and control tool wear.

Abstract: Through the analysis on damaged tool in sticking failure experiment by cutting austenitic stainless steel (1Cr18Ni9Ti) with scanning electron microscopy (SME), found that there are micro cracks existent on rake face near the tip of the cutting tool, through the research of the emergence, development and distribution direction of the crack, the direct reason for tool breakage is the crack being out of control. Combining the study of cutting tool element density change in cutting zone and grooving wear on rake face, this paper analyzed the cause of the binding between chip and tool and the influence factors of sticking failure during the cutting process.

Abstract: The problem of Sticking Failure of cutting tool is serious for cutting stainless steel 1Cr18Ni9Ti, on the basis of the Sticking Failure orthogonal experiment of YG8, it researches the range of temperature for Sticking Failure, chooses the best cutting parameters, and researches the effect for Sticking Failure, which provides the academic basis for the study of criterion of the mechanism of Sticking Failure.

Abstract: Considering the problems of the current cutting tools, such as wide varieties, low management efficiency, high cost and selection difficulty, this paper builds a cutting tools total life cycle management system model, by using the total life cycle management concept the total life cycle management of the milling cutters from purchasing to the use and discarding is realized. In this paper, through researching on cutters selection law, rules for milling cutters selection is made and intelligent cutters selection system is established with rule reasoning method.