Papers by Author: Qiu Lin Niu

Abstract: In this paper, effects of milling parameters on cutting force and surface roughness during symmetrical face dry milling process of super high strength steel 30CrMnSiNi2A were presented. Multiple linear regression model and orthogonal rotary quadratic regression model were established to analyze cutting force and surface roughness, respectively. Their adequacy was estimated by variance analysis and experimental data comparison. Parameters optimization for maximum metal removal rate and minimum surface roughness were also discussed.

Abstract: As a typical high strength material, titanium alloy Ti-6Al-2Sn-4Zr- 2Mo-0.1Si (TA19) is used to manufacturing the compressor power-brake of aircraft engine and the aircraft skin. All the machining experiments were carried out on a CNC-milling center under the stable conditions of cutting speed, feed rate, and depth of cut. The performance and wear mechanisms of coated- and uncoated carbide tools have been investigated in this paper to evaluate the machinability of TA19 in face milling. The three tools used were PVD-TiN+TiAlN, CVD-TiN+Al2O3+TiCN and uncoated carbide inserts. The results indicated that PVD coating had the best performance than other tool materials in milling titanium alloy TA19, and the cutting force and the wear value were the smallest than that for CVD-coated and uncoated tools. The failure types of PVD-, CVD- and uncoated inserts were the crater wear and micro tipping; the crater wear and tipping; tipping. Abrasive wear and adherent wear were the predominant mechanism of PVD-TiN+TiAlN carbide insert in face milling TA19 alloy. For CVD- and uncoated carbide, adherent wear was predominant.

Abstract: As two kinds of advanced titanium alloys, TC18 and TA19 were introduced in this paper. The machinabilities of TC18 and TA19 alloys were described in the grinding process. Grinding experiments were completed using green silicon carbide grinding wheel with the coarser 100 grit. Grinding forces and specific energy in surface grinding were investigated. And then, for studying the grinding characteristic, SEM images of the workpiece material were obtained. The results indicated that specific chip formation had the great effect on the mechanism of grinding TC18 and TA19 alloys, and the scratch was the main characteristic of surface grinding. TC18 alloy had the poor grinding performance compared to TA19 alloy.

Abstract: The cryogenic treatment is an extension of the cold processing technology by which the material properties could be changed. This provides a new method for people to improving the performance of the cutting tools and prolonging the tool life. The micro-structure of two unknown types of carbide reamers after different cryogenic treatment was introduced in this paper. From the metallographic microstructure, SEM microstructure, EDS spectrum analysis and the hardness measurement, the detailed analysis on the microstructure of the reamers (1# and 2#) was provided in this paper. The results show that the matrix materials of the two reamers were the WC-Co cemented carbide, and they were the ultra-fine grain carbide (＜500nm); 2# reamer belonged to the high Co cemented carbide reamer. By the cryogenic treatment, the hardness of two reamers has increased. And the value of the hardness for 1# reamer was higher than that for 2#.

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.