Papers by Keyword: Cutting

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Authors: Wei Yu, Qiang Feng, Cheng Zu Ren
Abstract: Abrasive machining is widely used as final machining process. It is still challenged to investigate the fundamental knowledge on the formation mechanism of groove and pile-up in single abrasive particle cutting. A 3D finite element analysis model to simulate single abrasive particle scratching on bearing steel (52100) workpiece with low cutting speed is proposed. An adaptive meshing technique is applied to handle large mesh deformation problem of the scratching process. The formation process of groove and pile-up for workpiece material is indentified qualitatively. The simulated results show that cutting speed has little effect on lateral profile. The height and area of pile-up increase with increase of depth of cut.
Authors: Hao Kai Yang, Yu Yang Tu
Abstract: Surface texturing has become a technique to reduce friction and wear in cutting process; laser surface texturing is a method used to create micro-dimples on the interface surface. It is considered that cutting of titanium is difficult. As the experiments are costly and time demanding, metal cutting modeling provides an alternative way for better understanding of machining processes under different cutting conditions. In this paper a 3D finite element model has been used to simulate the cutting process of titanium alloy Ti6Al4V to predict the cutting forces and temperatures.
Authors: Volker Schulze, Christoph Kühlewein, Hermann Autenrieth
Abstract: Latest research clearly demonstrates the excellent capability of the gear skiving process. For further improvement of the process and particularly for the enhancement of the process reliability fundamental scientific research is conducted. In this paper the result of investigation of process kinematics and chip formation mechanisms are presented. First the experimental analyses will be described, which represent an essential basis for developing and validating the models. In further experiments the material behavior of the test material SAE 5120 was determined and a material model was developed. The modeling of the process represents a central aspect of the research. This includes the basic modeling of the kinematics in a 3D-model. The simulation enables analysis of the kinematical conditions as well as the chip formation mechanisms and evaluation of the effects on process reliability. The results support the tool and process design and are an important basis for the implementation of the process.
Authors: Giovenco Axel, Frédéric Valiorgue, Cédric Courbon, Joël Rech, Ugo Masciantonio
Abstract: The present work is motivated by the will to improve Finite Element (FE) Modelling of cutting tool wear. As a first step, the characterisation of wear mechanisms and identification of a wear model appear to be fundamental. The key idea of this work consists in using a dedicated tribometer, able to simulate relevant tribological conditions encountered in cutting (pressure, velocity). The tribometer can be used to estimate the evolution of wear versus time for various tribological conditions (pressure, velocity, temperature). Based on this design of experiments, it becomes possible to identify analytically a wear model. As a preliminary study this paper will be focused on the impact of sliding speed at the contact interface between 304L stainless steel and tungsten carbide (WC) coated with titanium nitride (TiN) pin. This experiment enables to observe a modification of wear phenomena between sliding speeds of 60 m/min and 180 m/min. Finally, the impact on macroscopic parameters has been observed.
Authors: Zoltán Pálmai
Abstract: The common feature of the different forming technologies is that the deformation is concentrated into a relatively narrow shear zone. The behaviour of the material can be defined only by specific material properties, the definition of which is difficult and costly. We have developed a new method for the comparatively simple and cheap definition of these specific material properties based on the well known theory and the sophisticated measuring technology of cutting. To achieve this we have developed our previous dynamic technological model, which is described by evolution and delay differential equations. As an example, in the case of a steel with 13% Cr content T, C555520−≈8.26.2−≈=φεγ, the thermal softening 4410−−≈=sφεγ&&≈κ0.98±0.016 MPa/K, the strain rate sensitivity constant k≈0.034±0.009 and the strain hardening exponent n0.170.005.
Authors: Ernesto Lo Valvo, Roberto Licari
Abstract: The nesting of two-dimensional irregular shapes is a common problem which is frequently encountered by a number of industries where raw material has to be, as economically as possible, cut from a given stock sheet. A frequently recurring problem as far as cutting stock is concerned, is how to obtain the best nesting of some pieces of flat patterns which occupy minimalarea convex enclosure. The area of convex enclosure is related to the convex hull of the union of patterns which can be imagined as a large rubber band surrounding the set of all polygons. Our goal is to automatically obtain the smallest area convex shape containing all the patterns. As a matter of fact, Cheng and Rao have proposed an heuristic “stringy effect” procedure for clustering which follows a descending order of area of patterns. The “stringy effect” is able to put each new piece in a position which minimises the value of the distance between the centroid of each added piece and the centroid of the already formed cluster. The procedures till now shown in literature are quite complex. They make use of sliding techniques, and are not able to effectively work with relatively multiply-connected figures. In particular, the different procedures proposed are based on the No Fit Polygon computation of non-convex polygons, which often generates holes. This work is a proposal for a more efficient method, which can be used in heuristic procedure. In this paper a new procedure for the calculation of “No Fit Polygon” (NFP) of non-convex polygons is presented. Given two non-convex polygons, the algorithm is able to calculate their NFP very quickly and without any approximation by a polygon clipping method. By iterating this procedure with every polygon of our set, and positioning them using the “stringy effect” technique, it is so possible to obtain a convex shape that contains all the patterns, having the minimal area.
Authors: Ching Yen Ho, Mao Yu Wen, Shih Yu Lin
Abstract: This study has developed a thermal model for laser-assisted cutting of zirconia ceramics. Laser-assisted cutting can increase ceramics removal rates by utilizing a localized heat source to elevate the workpiece temperature prior to material removal with traditional cutting tool. At high temperatures the yield strength of ceramics can decrease below the fracture strength, changing the material deformation behavior from brittle to ductile and enabling the use of a single point cutting tool to remove material at rates approaching those of metal cutting. A thermal model has been developed for the workpiece of ceramics cylinder rotating with a constant speed, which was preheated by a laser and cut by cutting tool. Since the cutting tool followed the moving laser with a fixed distance in the axial direction, i.e. the feed rate of the cutting tool was the same as the moving velocity of the laser, this thermal model has been formulated in a cylindrical coordinate system that moved with the laser beam or cutting tool and therefore, this problem was a quasi-steady-state problem. An analytical solution for this thermal model has been obtained. The results calculated by this model agree with the available experimental data. The temperature field is presented during laser-assisted cutting of ceramics. The effects of feed rate and laser power on temperature field are also discussed in this study.
Authors: Xiao Bin Huang, Xing Chang
Abstract: In the present paper, the effects of the hardness, strength, chemical composition, microstructure, fracture properties of the material and other factors on the chips formation and deformation were studied during cutting the brittle metal. The process of cutting the brittle metal and the basic theory of the scrap fracture was also discussed comprehensively. In addition, this study pointed out the importance of the hot working process to avoid some metallographic organizations within the cast iron such as the stripy-like and inhomogeneous graphite.
Authors: Quan Lai Li, Chuan Zhen Huang, Jun Wang, Hong Tao Zhu
Abstract: Micro abrasive air jet (MAAJ) cutting is a promising technology for the fabrication of three-dimensional microstructures in hard and brittle materials. In this paper, a study on the cross-sectional shape of the kerf cut with MAAJ is presented. It shows that the machining depth and slope of the sidewall increase with an increase in air pressure, abrasive flow rate and jet incidence angle, while decrease with an increase in nozzle traverse speed. Using a dimensional analysis technique, predictive model for cross-sectional profile is developed. The research results may be meaningful to the highly precision three-dimensional micro-structural cutting.
Authors: Run Wei You
Abstract: The varying laws of the longitudinal grade at the partial any point on the vertical curve in the course of the freeway’s profile design were discussed via the analytical formulas calculation, and the minimum longitudinal gradient and the length of roads which cannot meet the current requirements were found out, then application effect of vertical curves with the large radius was explored. On this condition, some countermeasures and suggestions were provided for the reasonable design of the vertical curves.
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