Papers by Keyword: Hardened Steel

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Authors: K.M. Nambiraj, R. Rajeswari, S. Madhavan
Abstract: This paper reports the development of a cutting tool insert prepared by consolidation, followed by Spark Plasma Sintering (SPS) of TiB2 (Titanium diboride) particles processed through an in-situ reaction and AlN (Aluminium nitride) manufactured by the direct nitridation process. In-situ TiB2 particles, formed during reaction of KBF4 (Potassium tetra Fluoroborate) and K2TiF6 (Potassium Fuorotitanate) with Al alloy, are obtained by dissolving the Al-TiB2 composite in an acidic medium. The extracted TiB2 (30%) particles are blended with AlN and Al2O3 in the weight ratio of 67%-3% and sintered (SPS) at 1440°C with a compaction load of 50 MPa and a total sintering time of 8 minutes. The sintering is carried out in vacuum. The sintered ceramic displays high hardness of nearly 15.5 GPa and extraordinary toughness of 7MPa.m1/2. The inserts are manufactured according to SNGN (Square Double-sided ceramic) configuration. To study its performance, machining is carried out on hardened steel (EN 24). The developed AlN based inserts show increased wear resistance and provide good surface finish when compared with commercially available ceramic inserts (70%Al2O3+30%TiC). Cutting forces are recorded with a Kistler® dynamometer to correlate them with the tool wear. Methods of preparation and comparison of wear resistance and surface finish of the machined material with those pertaining to commercial ceramic inserts are also presented. SEM images are displayed, which support the results.
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Authors: Wei Zhang, Jin Hui Xu, Min Li Zheng, Hong Li Liu, Tong Wu
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.
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Authors: Sergio Delijaicov, Carlos Eddy Valdez Salazar, Éd Claudio Bordinassi, Linilsson Rodrigues Padovese
Abstract: This work studies the influence of machining parameters, such as cutting speed and forces, feed rate, cutting depth, and tool flank wear, on the generation of surface residual stresses in DIN 100Cr6 steel conical bearing rings submitted to a hard turning process. A complete factorial planning was used to perform the tests and projected measurement. Cutting forces were measured by a piezoelectric dynamometer and residual stresses were determined by the hole-drilling method using strain gage. Results showed that after 2000 m of tool machining, phase transformations had been observed on sample surfaces, with white layer formation, and deeper, a dark layer whose thickness varied depending on the severity level of turning and the tool wear (in machined distance). Increase in tool wear generated minor values of compressive residual stresses and the surface roughness presented almost the same values in all experiments, except when the bigger parameters were used.
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Authors: Guang Jun Chen, Liang Wang, Bai Ting He, Ling Guo Kong, Xiao Qin Zhou
Abstract: The cutting vibration has a great influence on the processing quality of Hardened steel. The research conducted in this paper is about how the cutting parameters influence the cutting vibration amplitude when the hardened steel is cut. The experiments were performed on CNC lathe CAK4085 with PCBN tool, where the cutting speed, feed rate, cutting depth and corner radius had been orthogonally combined. The cutting materials were hardened steel Cr12MoV and GCr15 whose hardness is HRC50-52 and HRC62-64. The cutting vibration amplitude under different group parameters was collected by electric eddy current sensors. An analysis about the influence rule of cutting parameters on cutting vibration amplitude had been made. With the increase of cutting speed, vibration amplitude will increase first, and then decrease. With the appropriate increase of feed rate, vibration amplitude will be reduced. With the increase of cutting depth and corner radius, vibration amplitude will both increase. This research can provide reference for improving cutting quality.
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Authors: Chun Juan Tu, Xu Hong Guo, Wei Wang, Chi Hong Wang
Abstract: Researching on dry turning hardened steel was to replace the grinding with turning, which would improve efficiency and reduce cost. The contrast experiments of turning hardened steel with ceramic and CBN cutting tools were carried out. The cutting forces of two tools with different cutting parameters were measured by Kistler cutting force acquisition system. The difference with two chips was observed by scanning electron microscope(SEM). The experimental equations of cutting forces were built up by the linear regression analysis method. The results indicated that the variation trend of cutting forces with ceramic and CBN cutting tools in same conditions was same. The thrust force was maximal, next was tangential force, axial force was minimum. The thrust force and tangential force of ceramic cutting tools were almost double compared with CBN cutting tools. The shapes of chips with ceramic and CBN cutting tools were saw-tooth, the rough slice layer with periodic flow was shown on outer surface and the friction mask was distributed well-proportioned on inner surface. The spacing of rough slice layer of chips with CBN cutting tools was more wide, the friction mask of chips with ceramic cutting tools was more clear.
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Authors: Xiao Bin Cui, Jun Zhao
Abstract: In the present study, face milling of AISI H13 steel (46-47 HRC) with CBN tools was conducted. Cutting speeds 389 and 1592 m/min were adopted in order to identify the characteristics of cutting force and tool wear at low and high cutting speeds. For each cutting speed, the metal removal rate and axial depth of cut were set to be invariable, and different combinations of radial depth of cut and feed per tooth were selected. The optimum combination of radial depth of cut and feed per tooth for each cutting speed was distinguished. For different cutting speeds, the cutting force changed in varying ways with different combinations of cutting parameters. At the cutting speed of 389 m/min, after the initial cutting stage, the tool wear rate was low even at the end of tool life. When the cutting speed was 1592 m/min, the tool wear increased rapidly, and the tool wear rate changed little in the whole tool life span. Adhesion and abrasion were the main wear mechanisms of the tool faces at the cutting speed of 389 m/min. While at the cutting speed of 1592 m/min, fracture contributed greatly to the final tool failure.
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Authors: L.D. Wu, Cheng Yong Wang, D.H. Yu, Yue Xian Song
Abstract: Hardened steel P20 at 50 HRC is milled at high speed by TiN coated and TiAlN coated solid carbide straight end mills, and the cutting forces and tool wear are measured. The result shows that TiAlN coated tool is more suitable for cutting hardened steel at high speed. Then the hardened steel is milled under different cutting parameters. It is indicated that the effect of cutting speed on cutting forces is small, but the effect of cutting speed on machine vibration should be considered. Increase feed per tooth or radial depth of cut will increase the cutting forces.
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Authors: Shu Cai Yang, Bin Jiang, H.Y. Li, M.L. Zheng, S.J. Wang
Abstract: In order to solve the problem of machined surface damage and machining efficiency decline that caused by the decrease of effective cutting thickness in high speed ball-end milling hardened steel, using high speed cutting adiabatic shearing model, analyzed the adiabatic shearing deformation on hardened steel, and proposed the criterion of chip separating position. Analyzed the force in the transformation process from cutting to plowing, the influence of cutter deformation on cutting thickness was studied, and established the minimum cutting thickness model. Having done finite element analysis of cutter and experiment of high speed milling hardened steel, the validity of the minimum cutting thickness model was proved. The results show that cutting thickness changes from small to large, and then from large to small under the influence of cutting trajectory and tool edge radius. The deformation of cutter leads to the increase of the minimum cutting thickness, and further enhances chip thickness thinning effect. High feed can compensate cutting thickness thinning and the minimum cutting thickness model provides an effective way to restrain the damage of machined surface and cutter caused by cutter plowing.
24
Authors: Grzegorz Struzikiewicz, Tadeusz Otko
Abstract: The article focuses on analysis of the effects cutting parameters on the surface roughness and shape errors. Research was performed for longitudinal turning of hardened steel 145Cr with using ceramic tools of different nose radius. Shape deviations and roughness for machined surfaces ware determined. Results were analysed and conclusions were presented.
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Authors: Zhi Lin Han, Bin Lin, Bao Xing Zhang, Lei Zhang
Abstract: In this paper, the optimization of cutting parameters in turning thin-walled 45Cr steel workpieces with cermets tool is researched. A new integrated optimization method is proposed, in which the parameter design of the Taguchi method, principal component analysis method and response surface method (RSM) are applied to obtain the optimal parameter for a hard turning process using mixed cermets tools. The orthogonal array experiment is conducted to economically obtain the response measurements. The Principal Component Analysis (PCA) is applied to transform the original evaluation variables into new, uncorrelated comprehensive variables, which includes most information of original variables, then the output response can be calculated by the principal components. At last, the RSM is used to build the relationship between the input parameters and output responses, and obtain the desired machining parameters. The quality of workpieces and the process efficiency are improved obviously.
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