Papers by Author: Hai Dong Yang

Abstract: Powder metallurgy valve seat is an important part for engine; the material has excellent properties such as the wear-resistance of high temperature, corrosion proof and high temperature stability etc. But because of its high hardness, porous nature and contains many microscopic characteristics of the hard particles and the like, common tools cut these parts wear out quickly. And the valve seat requires higher dimensional accuracy and surface roughness, so these bring a lot of difficulties to cut these parts. Because of Polycrystalline Cubic Boron Nitride (hereafter referred to as PCBN) cutting tool has such advantages as high hardness; wear resistance; minimum surface roughness, so it has a great advantage on hard cutting the powder metallurgy valve seat. By hard cutting the powder metallurgy valve seat experiments, to research on the wear form and the cutting parameters impact on the cutting force.

Abstract: Micro-textured technology which studies in the field of tribology shows that micro-textured surface can effectively improve the situation of friction between the friction interfaces. In this article, micro-textured surface technology has been applied to the cutting tools, in order to study the cutting mechanism of micro-textured carbide tools. The effect of cutting parameters on surface friction characteristics was studied when cutting 45 steel with YT15 cemented carbide tools. The results shown that all surface friction coefficient of the samples got the best value when the feed rate is 0.14mm/r; an appropriate increasing in feed rate can reduce the surface friction coefficient in the low-speed cutting. Throughout the course of the test, the average of the surface friction coefficient of the 4th and the 5th sample tools are better than other tools.

Abstract: Polycrystalline Cubic Boron Nitride (PCBN) tool is suitable for cutting powder metallurgy valve seat, which has high hardness and contains hard particles. By hard dry cutting different materials of powder metallurgy valve seat, the results show that: tool life when cutting melting copper powder metallurgy valve seat is longer; breakage failure is the main failure forms of tool and wear mechanism contains hard spots scratches, adhesive wear, diffusion wear and oxidation wear.

Abstract: A series of experiments was conducted in high speed machining of powder metallurgy material with PCBN tools. The main tool wear mechanisms were discussed by observing tool wear morphology utilizing scanning electron microscopy (SEM) and detecting the element distribution of the worn tool surface using energy dispersive spectroscopy (EDS).The experimental results indicate that fragile breakage occurred before it reached its blunt standard in high-speed machining of powder metallurgy material with PCBN tools,and the tools wear mechanisms are synergistic interaction among mechanical wear,binder wear and chemical wear.

Abstract: A systematic cutting test was conducted turning normalized AISI1045 carbon steel with two kinds of Ti (C, N)-based cermet cutters, which were made with micron and nanometer TiC powders. And the cutting performance and abrasion mechanism was discussed in the article. The effect of tool orthogonal clearance on tool life was also researched in this paper. Results showed that: The tool life was affected seriously by tool orthogonal clearance angle, and the optimum tool orthogonal clearance angle of Ti (C, N)-based cermet cutter was 5°when cutting normalized AISI1045 steel. The cutting Performance of Ti (C, N)-based cermet cutters which were made with nanoTiC powders was better than the ones which were made with micron TiC powders obviously. And the primary wear behaviors were wear.

Abstract: Through the experiment of cutting 45 steel, the influence of boronizing on Ti (C,N)-based ceramic cutting performance in different cutting speeds were discussed. The test results indicated that: regardless of boriding, cutting speed has a great influence on the life of Ti (C,N)-based ceramic cutting tool. Within the limit of 200~400 m/min, the lower the cutting speed is, the longer tools life. At the minimum speed, boronizing greatly improves cutting performance and doubles tool life. It has no significant but negative effects once over 300 m/min. The decrease of the abrasion resistance of boronized layer is mainly influenced by the intense thermal shock of high speed cutting.

Abstract: The lives of the two CERMETS cutters were investigated when turning 45carbon steel in the same cutting condition. The effect of tool orthogonal clearance on tool life was also researched in this paper. The results of the experiment were indicated as: the cutting performance of Nano TiN modified TiC-based CERMETS cutters was obviously superior to that of ultra-fine Ti(C, N)-based CERMETS cutters. And the length of cutting path of the two cutters was longest with the tool orthogonal clearance of 3-4°.

Abstract: Austenitic stainless steel has poor cutting performance, especially when the inappropriate choice of tool materials and cutting parameters, cutting tool life will be shortened and the quality of machined surface is poor. In this paper, 0Cr18Ni9 stainless steel dry cutting tests had been done with nano-TiAlN coated carbide blade YGB202, the relationship between tool life and cutting speed, tool wear mechanism had been analyzed. In order to improve the processing efficiency and tool life, process parameters were optimized.

Abstract: Aiming at the problems of coated carbide cutting tools used in Quenched 30crMnSiA steel milling such as poor cutting performance and shot service life.We have designed and produced a new type of PCBN tools as cutter head by welding. After high-speed milling and testing the Quenched 30CrMnsiA steel, we have optimized the process parameters and improved production efficiency. The experiment proved that the new type of PCBN tools can replace the carbide coated tools completely, It not only increases the tool life, but also reduces the tool costs, and fully demonstrated that the PCBN tools also have good application prospect in high-speed milling.

Abstract: The method of “cutting instead of grinding” on hardened steel is always attractive to engineers. To gain this aim the tool material must first be found. C3N4 is a new kind of super hard material and has comparable properties with diamond in high hardness, wear-resistance, low friction coefficient and thermal conductivity. A number of dry-cutting tests were carried out by C3N4-film coated tool on hardened steel, proved the coating tool is suitable for hard dry cutting.