Papers by Author: Yun Shan Zhang

Abstract: Alloy cast iron cylinder is the mainstream product used in engine nowadays. However, the machinability of alloy cast iron is poor because of its enhanced mechanical properties. In this paper, turning experiment has been conducted to study machinability of alloy cast iron with uncoated and coated carbide tools under dry cutting condition. The results of the experiment indicated that the turning performance of alloy cast iron with coated tool was much better than uncoated tool in terms of cutting force coefficients and tool wear. Feed rate has a great influence on surface roughness, and appropriate tool wear is benefit of finished surface roughness.

Abstract: The purpose of this study was to analyze the effects of cutting parameters on the surface roughness (Ra) when turning of alloy cast iron using uncoated carbide insert under dry cutting condition. The mathematical model for the surface roughness was developed by response surface methodology (RSM).Response surface contours were constructed and used for determining the optimum cutting conditions to reduce machining time without increasing the surface roughness.

Abstract: These years, the mold has become a very important forming tool in modern industry. And the die steel is the most important technical and material base in mold industry. To obtain the optimized cutting parameters, this paper introduced the cutting performance of WC-Co carbide cutting tools (P10) from cutting force, the surface roughness, chip deformation and the chip-breaking performance in turning 4Cr13 die steel. And the cutting parameters were optimized by homogeneous design method and multiple linear regression analysis method in this paper. The regression models on cutting forces and surface roughness with the cutting parameters were studied and taken the tests of significance. The result showed that it was more suitable for finish turning 4Cr13 die steel using WC-Co carbide tools at vc =183.3m/min, f=0.2mm/r, ap=0.75mm or vc =200m/min, f=0.1mm/r, ap=1mm.

Abstract: 13%Cr stainless steel has good comprehensive performance, which makes it suitable to work under the condition of high temperature, high pressure and corrosive environment, such as petroleum industry. It can be used as materials of petroleum pipes with buttress thread. Buttress thread turning is a heavy-load machining, which places high requirement on the cutting tool. Based on the cutting characteristics of buttress thread, the machinability of 13%Cr stainless steel is studied by turning experiments. Two kinds of inserts with different geometries were employed in buttress thread turning experiments. Experimental results show that less cutting force, longer tool life, better chip curling effect and surface quality was acquired for the insert with rake angle of 12° , clearance angle of 3° and chip-curling groove during 13%Cr stainless steel buttress thread turning process.

Abstract: Rotor steel 26NiCrMoV145 has been widely employed in aerospace and power industry because of its unique properties. As to this new material that used widely in important places, it is worth studying its machinability. An experiment was carried out to study the cutting forces and tool wear mechanism during high speed dry turning using multilayer Al2O3 coated carbide insert. The orthogonal test was chosen, cutting forces were measured. SEM analysis has been carried out on worn tools to determine the tool wear mechanisms. Crater wear and coating peeling could be found in every cutting speed. Flank face wear appears smooth when cutting speed increases. At last, an optimization of the cutting condition was suggested when considering of material remove rate, cutting forces and tool wear.

Abstract: A new special drill is developed for iron cast drilling. The special drill has double point angle and 0°chisel rake angle which can decrease cutting force, tool wear and cutting temperature. Drilling performance is evaluated by trust force, torque, tool wear. The results indicate that new special drill is suitable for iron cast drilling with small cutting force and long tool life.

Abstract: The α+2βtype Ti-5Al-4.75Mo-4.75V-1Cr-1Fe (TC18) is a very difficult machine material for its low thermal conductivity, low elastic modulus, and high chemical activity. So how to improve the machining efficiency and prolong the tool life have got more and more attentions. In this paper, wear mechanism and wear types of coated (TiN+TiAlN) carbide tool and uncoated carbide tool are presented when face milling the Ti-18 alloy under the same machining condition. The results showed that wear types of PVD coated tool are mainly adhesive, diffusion and crater wear, while the mainly failure mode of uncoated carbide tool is tipping. So it is more appropriate to select the PVD coated tool than uncoated tool in the milling TC18 alloy process.

Abstract: Aluminum alloy, as a kind of large-scaled structures, have been widely used in modern aerospace industry. In order to reduce its machining deformation, cutting parameter optimization is absolutely necessarily. By fuzzy synthetic evaluation, cutting parameters are optimized based on factors: surface roughness, residual stress, radial milling force and milling temperature. By maximal grade of membership rule, optimized values are obtained by different two methods. And by BP network with Bayesian regularization method the corresponding milling parameters are obtained too.

Abstract: Research has been done on microstructure and machinability of two different free-cutting steels by using cutting tools coated and uncoated at the condition of different cutting parameters. The cutting force, surface quality, chip morphology and tool wear are investigated, which reveal the influence of the size and shape of sulphide inclusion on machinability. The experiment shows that the shape of spindled sulphide inclusion has relatively better machinability than stripped sulphide inclusion and the size of sulphide inclusion also plays some influence.

Abstract: Stainless 2Cr13 is used as petroleum pipe material for its good performance in condition of high temperature, high pressure and corrosive environment. Buttress thread turning is a type of heavy machining, which has a great influence on the residual stress of workpiece. Residual stress is usually determined by cutting parameters and tool geometries. Experiments with different geometrical tools were carried out and a finite element model was used to study the influence of tool geometries on the residual stress. Experimental and simulated results showed that relatively bigger rake angle and smaller corner radius make a relatively lower tensile residual stress of workpiece surface in dry turning buttress thread.