Papers by Keyword: Metal Cutting

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Authors: Yue Zhang, Tai Li Sun, Qi Dong Li, Xi Chuan Zhang
Abstract: The gases of nitrogen, oxygen, argon and carbon dioxide were employed as coolant and lubricant in metal cutting. Therefore, the smaller kinetic diameter of gas, the lower cutting forces can be obtained. A conical capillary model is proposed, based on the experimental results and the theory analysis of stress distributions at the tool-chip interface. According to the boundary-layer theory, the kinetics equations of gas flow were solute. The velocity and flux of gas molecule are presented. In the capillary, the adsorption of tool-chip interface results in boundary lubricating film; the conical shape of capillary limits the depth of coolant and lubricant penetrating; and the negative press is the motility for coolant and lubricant penetrating. The study results show the molecule size of the coolant and lubricant could effect on its performances, and the coolant and lubricant with a relatively small molecule may have the particularly effective nature, in metal cutting.
Authors: Mathias Agmell, Aylin Ahadi, Jan Eric Ståhl
Abstract: This study are focused on the deformation zones occurring in the work piece in a machining process and the corresponding cutting forces. The fully coupled thermo-mechanical FE-model for orthogonal cutting, developed in [1] is utilized. The work piece material is modeled with Johnson-Cook plasticity including damage formulation. Simulations for different feed depths were performed. The cutting forces, the chip thickness ratio and the deformation widths were determined experimentally by the quick-stop images and a force measurements. The results from the simulations have been compared to experimental data for the cutting forces and the chip thickness ratio as a function of the theoretical chip thickness.
Authors: Juan Huang, Yun Ming Zhu, Qin Feng Li, Gui Cheng Wang
Abstract: The burr formation and control is one key technology of achieving precision and ultra-precision machining and automatic machining. Based on the theory of system engineering, the metal cutting burr formation, control and removal technology system are constructed in the paper. Then, the basic principles of burr control are presented. Combined with precision and ultra-precision machining and automatic machining, the active control methods and technologies of burr are presented. They are the modified design of parts structure, the option of tool geometry parameters, the adjustment of cutting data and processing technologies optimization etc. So, these methods lay a solid foundation on achieving minimum burrs.
Authors: Su Yu Wang, Wen Jie Yang, Lin Lin Ma
Abstract: Work hardening reserches in metal cutting has an important significance in improving surface quality of the workpiece and the service performance of parts. The paper introduces current researches of the work hardening in metal cutting process, analyses the forming mechanism and influencing factors of the work hardening and discusses the effects of the work hardening on workpiece service performance. At last, the new trends of work hardening researches in metal cutting process are conclusively predicted.
Authors: Ming Zhen Liu, Liang Shan Xiong, Bin Lin
Abstract: The tool-chip friction coefficient influences the simulation result of the residual stresses distribution seriously when Finite element software is used to simulate. This paper presents a new tool-chip friction coefficient estimate approach. Frist, a new mathematical model of cutting forces, the cutting speed, feed amount and the tool-chip friction coefficient was established in this paper based on the simulation results of Advant Edge, and then the tool-chip friction coefficient was reversed when the cutting forces are measured. Comparing the simulation residual stress distribution of the friction coefficient in calculation, average coulomb friction coefficient, the default friction coefficient with experimental result; it turns out the distribution of residual stresses in the friction coefficient of calculation approaches to experimental result.
Authors: Jan Eric Ståhl, Fredrik Schultheiss
Abstract: A majority of the established systems for determination and optimization of cutting data are based on Woxén’s equivalent chip thickness, heW. In metal cutting theory and models, the equivalent chip thickness is of vital importance when the depth-of-cut ap is in the same order or smaller than the nose radius r. Woxén made considerable simplifications in his chip area model, that form the basis for calculations of the equivalent chip thickness. Basic mathematical solutions, e.g. describing the chip area on circular inserts, are lacking. This article describes the geometrical implications when machining with round inserts. The error in Woxén’s equivalent chip thickness is largest when the depth-of-cut is less than ¼ of the nose radius and are up to 40 % wrong for some combinations of cutting data in the finishing range. The presented results explain the difficulties in getting a good validity in the models used to calculate tool life in finishing machining. The error leads to an underrating of the tool load in many machining situations
Authors: Yue Zhang, Xi Chuan Zhang, Zhong Ren Liu, Yu Qiang Ma
Abstract: For investigating the effect of ultrasonic treatment on the cooling and lubricating action of cutting fluid, an ultrasonic treatment system of emulsion fluid was developed to be used in cutting experiments. And the comparison experiments were carried out with YT15 tool turning 45 steel, under the conditions of dry cutting, fluid and ultrasonic treatment fluid. The results show that as ultrasonic treatment one used cutting forces decrease about 10%-15% and 5%-10% to dry cutting and fluid; the cutting deformation coefficients reduce too; and the machined surfaces are enhanced. Therefore, the cooling and lubricating performances of the fluid are improved by ultrasonic treatment. As a result, the using quantity of emulsion fluid would reduce indirectly, and this help to energy saving and emission reducing.
Authors: Xue Feng Bi, Gautier List, Yong Xian Liu
Abstract: The streamline method was used to investigate the plastic strain rate in machining. The streamline function presented in this paper is a general equation with three parameters controlling the complex variation of flow line shape. Velocity and deformation field were obtained by streamline analysis. The validation of this model was conducted by comparing with other experimental results published. It shows that the streamline model presented in the paper can be applied to the evaluation of strain rate in machining.
Authors: Xue Feng Bi, Cheng San Yang, Yu Lun Chi, Yong Xian Liu
Abstract: Strain and strain rate are two important parameters evaluating plastic deformation of workpiece in cutting process. Finite element simulation is implemented to estimate plastic deformation of wokrpiece in this paper. Flow net function in simulation is used to capture deformation state of grids on workpiece, and the deformation result is compared with that observed by Stevenson and Oxley in cutting test. Point tracking function in simulation is utilized to calculate strain and strain rate distribution along flow lines, and the results are also compared with that calculated by streamline model.
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