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1
Sakamoto, Satoshi, Masaya Gemma, Yasuo Kondo, Kenji Yamaguchi, Mitsugu Yamaguchi et Takao Yakou. « Influence of the Characteristics of a Workpiece on the Slicing Characteristics Including Tool Wear ». MATEC Web of Conferences 221 (2018) : 04005. http://dx.doi.org/10.1051/matecconf/201822104005.
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Multi-wire saws with a diamond electrodeposited wire tool are widely used to slice hard and brittle materials. The properties of the materials significantly affect the saw’s performance in terms of slicing quality, efficiency, and accuracy. In this study, the effects of the material properties of workpieces on wire tool performance and tool wear are described. The main conclusions are as follows: the higher the hardness and toughness of the workpiece material, the longer the slicing time and greater the damage to the wire tool. The brittleness of the workpiece adversely affects the thickness variation more than its hardness. In addition, the frequency of chipping mainly depends on the hardness of the workpiece, whereas the chipping size mainly depends on the toughness of the workpiece.
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Luo, Ming, Ding Hua Zhang, Bao Hai Wu et Ming Tang. « Modeling and Analysis Effects of Material Removal on Machining Dynamics in Milling of Thin-Walled Workpiece ». Advanced Materials Research 223 (avril 2011) : 671–78. http://dx.doi.org/10.4028/www.scientific.net/amr.223.671.
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In aerospace industry, thin-walled workpieces are widely used in order to reduce the weight and to fulfill the high demands of their later applications. These workpieces are usually highly sophisticated and difficult to machine according to their geometry and material choice. In this paper, influence of material removal within the thin-walled workpiece machining operation on the dynamic properties of the workpiece and the machining process system is discussed. Aiming at learning about dynamic properties evolution during the machining operation, different milling processes of thin-walled plate are studied. Numerical simulation methods are employed in the study to investigate the dynamic properties evolution and machining stability with the material removal process in the milling process of thin-walled workpiece. The investigation results are expected to be used for designing optimized material removal sequence, which will guarantee highly material removal rate as well as highly machining accuracy of thin-walled workpiece.
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Denkena, Berend, Thilo Grove et Eike Hasselberg. « Workpiece Shape Deviations in Face Milling of Hybrid Structures ». Materials Science Forum 825-826 (juillet 2015) : 336–43. http://dx.doi.org/10.4028/www.scientific.net/msf.825-826.336.
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A currently common method to design high-performance workpieces is to combine two or more materials to one compound. This way, workpieces can be composed of the most qualified materials according to local loads.When machining high-performance workpiece compounds (e.g. cylinder crankcases), high quality requirements concerning the accuracy of dimension and shape as well as the surface roughness must be fulfilled. However, machining of workpiece compounds leads to unfavorable changes of the workpiece quality in comparison to machining of the single materials. Significant shape deviations occur when different materials are machined alternately in one cutting operation. This is due to unequal material properties, cutting characteristics, chip formation mechanisms as well as characteristic interactions between the single components.The focus of this research is on the process understanding as well as on the identification of measurable shape deviation indicators that describe the surface finish of hybrid structures. Here, the indicators material height deviation, transition deviation at the material joint, surface roughness deviation as well as surface defects (e.g. scratches) on the surface are presented. The overall aim of this research is to predict the surface finish resulting from face milling an aluminum/cast iron compound or a polyurethane/cast iron compound.
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Rajabinasab, Fereydoon, Vahid Abedini, Mohammadjafar Hadad et Ramezanali Hajighorbani. « Experimental investigation of the effect of tool material on the performance of AISI 4140 steel in the rotary near dry electrical discharge machining ». Proceedings of the Institution of Mechanical Engineers, Part E : Journal of Process Mechanical Engineering 234, no 4 (6 mai 2020) : 308–17. http://dx.doi.org/10.1177/0954408920922102.
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This research conducts in three sections. The first section studies the effect of tool materials and gases on rotary workpiece electrical discharge machining. During the experiments, the effects of three kinds of tool materials (Cu, Cu-Cr, and Cu-Sn) and three types of industrial gases (air, argon, and CO2) on the material removal rate, tool wear rate, and workpiece surface roughness are investigated. The second is a comparison between rotary workpiece, rotary tool, and the fixed workpiece by choosing the appropriate tool material and gas in order to observe the effect of workpieces rotation on the process. Finally, another comparison has been done between wet electrical discharge machining and near dry electrical discharge machining of the fixed workpiece in order to study the effect of the dielectric. The results show the copper tool has the best performance compared with other tools. Scanning electron microscopy output shows the Cu-Sn tool creates shallow micro-cracks on the surface. Air and CO2 gases have the higher material removal rate in low current, but argon has better function than other gases in high current. In addition, a rotational speed causes an increase in material removal rate and tool wear rate and surface roughness decrease in near dry electrical discharge machining. The level of tool wear rate has decreased by 14% in the rotary workpiece compared with the rotary tool.
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Chudin, V. N., et V. I. Platonov. « Drawing with Thinning under Viscoplasticity Deformation of the Anisotropic Material ». Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no 2 (145) (juin 2023) : 73–82. http://dx.doi.org/10.18698/0236-3941-2023-2-73-82.
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The paper considers the drawing process with wall thinning of the anisotropic workpieces made of high-strength materials exposed to viscoplasticity deformation. Scientific literature is paying insufficient attention to calculation of the deformation processes of workpieces exposed to viscoplasticity. Relationships are proposed to determine stresses and continuity of the workpiece material during drawing in heating the cylindrical products with a thinned wall. State of hot material viscoplasticity is accepted under the plane deformation scheme. Equilibrium equation, yield condition for anisotropic material and discontinuity kinetics equations were used making it possible to predict strength characteristics and accuracy of the products obtained. Calculations of the drawing process modes for workpieces made of the AMg6 aluminum alloy and of the VT6s titanium alloy were performed. Graphic dependences are demonstrated of alterations in the operation specific force and in the material continuity value on the motion speed of the deforming punch. At the given forming temperatures, the energy continuity equation corresponds to the aluminum alloy, and the deformation equation corresponds to the titanium alloy. Influence of the workpiece mechanical properties anisotropy on the drawing technological conditions was studied. It is shown that force modes and continuity alteration of the deformed material depend on the anisotropy coefficient at a given temperature. This factor is determined by strain strengthening of the workpiece material and softening over time
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Tiffe, Marcel, Dirk Biermann et Andreas Zabel. « Fitting of Constitutive Material Parameters for FE-Based Machining Simulations for Functionally Graded Steel Components ». Key Engineering Materials 611-612 (mai 2014) : 1202–9. http://dx.doi.org/10.4028/www.scientific.net/kem.611-612.1202.
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The composition of different materials and their specific properties like tensile strength and toughness is one way to achieve workpiece characteristics which are tailored to the later application. Another approach is the subsequent local heat treatment of workpieces made of homogeneous materials. However, both ways are costly and go along with several subsequent process steps. Therefore, mono-material workpieces which were manufactured by thermo-mechanical forming processes may provide such tailored properties in the form of functional gradations. Furthermore, the process chain is shortened by the combination of forming and heat treatment, but nevertheless machining processes are still needed for proper workpiece finish. This puts the challenge of varying process conditions due to hardness alterations within a single process step, e.g. turning. In addition to experimental investigations simulative analysis techniques are desired to evaluate mechanical as well as thermal loads on tool and workpiece. In the case of FE-based microscopic chip formation simulations proper material behaviour needs to be determined with respect to material hardness. This paper describes the approach of fitting Johnson-Cook material parameters as a function of workpiece material hardness. In order to achieve realistic stress states within the process zone, this approach considers the yield strength as a linear function of the hardness. It is shown how the hardness influences the cutting conditions and how the Johnson-Cook parameters are identified. Then these parameters are validated in three-dimensional simulations of exterior dry turning by comparison of simulated process forces and chip formation to experimentally achieved ones.
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Han, Bing, Cheng Zu Ren, X. Y. Yang et Guang Chen. « Experiment Study on Deflection of Aluminum Alloy Thin-Wall Workpiece in Milling Process ». Materials Science Forum 697-698 (septembre 2011) : 129–32. http://dx.doi.org/10.4028/www.scientific.net/msf.697-698.129.
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The deflection of Aluminum alloy thin-wall workpiece caused by the milling force leads to additional machining errors and reduces machining accuracy. In this paper, a set of experiments of milling thin-wall workpiece were carried out to study the deflection of thin-wall workpiece. The workpieces, with different types of material and different thicknesses, were machined on CNC machining center. The deflections of workpiece were measured by a three-coordinate measuring machine. Effects of Aluminum alloy material and thickness on deflection are discussed based on the experimental data.
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Lee, Seok Won, et Andreas Nestler. « Virtual workpiece : workpiece representation for material removal process ». International Journal of Advanced Manufacturing Technology 58, no 5-8 (5 octobre 2011) : 443–63. http://dx.doi.org/10.1007/s00170-011-3431-2.
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Jatti, Vijaykumar S., et T. P. Singh. « Effect of Deep Cryogenic Treatment on Machinability of NiTi Shape Memory Alloys in Electro Discharge Machining ». Applied Mechanics and Materials 592-594 (juillet 2014) : 197–201. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.197.
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NiTi shape memory alloys usually consist of binary alloys of nickel and titanium concentrations near the equiatomic composition. Due to high hardness of NiTi alloys, the traditional machining processes are not able to machine these alloys. Nontraditional processes like electro discharge machining (EDM) ; due to their unique mechanism of material removal are useful alternatives in such case.The overall machining performance of electro discharge machining process depends on the electrical, thermal properties of both tool and workpiece materials. Cryogenic treatment has a history of improving mechanical, electrical, and thermal properties of materials. Recently, very few researchers applied cryogenic cooling and treatment of workpiece and tool in conventional EDM and found notable improvement in machining performance. In this study, NiTi shape memory alloys was subjected to around-185C for cryogenic treatment and the effects of cryogenic treatments on the machiniability of NiTi shape memory alloys workpieces in electro discharge machining have been investigated. The electrical conductivity of workpiece exceptionally improved. Experimental results showed about 19% increase in material removal rate of cryogenic treated workpieces. Variations in tool wear rate was found to be marginal.
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Ivanova, Tatyana N., Aleksandr I. Korshunov, Jozef Peterka, Ivan A. Ratnikov et Peter Pokorny. « The Possibility of Modeling Parts in Production Technology ». Multidisciplinary Aspects of Production Engineering 3, no 1 (1 septembre 2020) : 359–73. http://dx.doi.org/10.2478/mape-2020-0031.
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AbstractThe object of the research is a part “Flange half of differential case”, which has complex shape of a housing. The subjects of the research are the processes of selection of analogue material, workpiece production method, and justification of the structural and technological parameters of a part, taking into account 3D-modeling of the structure, deformations, displacements, stresses, and safety factor. The selection of analogue material is connected with suspension of production of open-hearth steel grade Mst.6 GOST 380-50. The objectives of the work include juxtaposition of computer models of deformations, displacements, stresses, safety factors of the part made of different analogue materials; comparison of models according workpiece production methods with consideration of material utilization ratio, structural and technological features of resulting workpieces. For modelling we have chosen the several types of materials. Research on modelling processes was fulfilled by means of software of Kompasv17, Solid Works, Solid works simulation. Volumetric models of parts and workpieces for all studied materials have been created taking into account the deformations, displacements, stresses, and safety factor. There results of modelling of “Flange half of differential case” allowed us to make recommendations for production conditions. These recommendations include the use of steel 45 GOST 1050-2013 as analogue material, hot forging of a workpiece on a horizontal forging machine, creating of design and technological documentation for the manufacture of the part.
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Wan, Min, Weihong Zhang, Kepeng Qiu, Tong Gao et Yonghong Yang. « Numerical Prediction of Static Form Errors in Peripheral Milling of Thin-Walled Workpieces With Irregular Meshes ». Journal of Manufacturing Science and Engineering 127, no 1 (1 février 2005) : 13–22. http://dx.doi.org/10.1115/1.1828055.
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The finite element formulation is studied in this paper to predict static form errors in the peripheral milling of complex thin-walled workpieces. Key issues such as cutter modeling, finite element discretization of cutting forces, tool–workpiece coupling and variation of the workpiece’s rigidity in milling are investigated. To be able to predict static form errors on the machined surface of complex form, considerable improvements are made on the proper modeling of the material removal in milling and the iterative calculations of tool-workpiece deflections. A general simulation approach is developed based on 3D irregular finite element meshes. By using illustrative examples, rigid and flexible models are compared with existing ones to show the validity of the approach.
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Slătineanu, Laurenţiu, Margareta Coteaţă, Irina Besliu, Oana Dodun et Miroslav Radovanović. « Surface Generation by Material Removal in Manufacturing Processes from Machine Building ». Applied Mechanics and Materials 659 (octobre 2014) : 112–17. http://dx.doi.org/10.4028/www.scientific.net/amm.659.112.
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The examination of the main machining methods applied in manufacturing processes from machine building and based on material removal from workpiece highlights essentially the existence of distinct processes able to generate material. An analysis of certain machining methods able to develop processes of material removal from workpieces was initiated by taking into consideration the principle machining schema and the capacity of generating machined surfaces. One concluded that within distinct machining processes, various phenomena are applied in order to obtain material removal from workpiece.
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Li, Junye, Zhenguo Zhao, Junwei Li, Fujun Xiao, Rongxian Qiu, Hongcai Xie et Wenqing Meng. « Molecular Dynamics Simulation Study on the Influence of the Abrasive Flow Process on the Cutting of Iron-Carbon Alloys (α-Fe) ». Micromachines 14, no 3 (22 mars 2023) : 703. http://dx.doi.org/10.3390/mi14030703.
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The plastic deformation behavior and microstructural changes in workpieces during ultra-precision machining have piqued the interest of many researchers. In this study, a molecular dynamics simulation of nano-cutting iron-carbon alloy (α-Fe) is established to investigate the effects of the fluid medium and cutting angle on workpiece temperature, friction coefficient, workpiece surface morphology, and dislocation evolution by constructing a molecular model of C12H26 as a fluid medium in the liquid phase using an innovative combined atomic approach. It is demonstrated that the presence of the fluid phase reduces the machining temperature and the friction coefficient. The cutting angle has a significant impact on the formation of the workpiece’s surface profile and the manner in which the workpiece’s atoms are displaced. When the cutting angle is 0°, 5°, or 10°, the workpiece’s surface morphology flows to both sides in a 45° direction, and the height of atomic accumulation on the workpiece surface gradually decreases while the area of displacement changes increases. The depth of cut increases as the cutting angle increases, causing greater material damage, and the presence of a fluid medium reduces this behavior. A dislocation reaction network is formed by the presence of more single and double-branched structures within the workpiece during the cutting process. The presence of a fluid medium during large-angle cutting reduces the number of dislocations and the total dislocation length. The total length of dislocations inside the workpiece is shorter for small angles of cutting, but the effect of the fluid medium is not very pronounced. Therefore, small cutting angles and the presence of fluid media reduce the formation of defective structures within the workpiece and ensure the machining quality.
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Kolisnyk, Mykola, et Maxim Sluzalyuk. « RESEARCH OF METHOD OF CALCULATION AND SELECTION OF TECHNOLOGICAL PARAMETERS OF STAMPING WRAPPED WITH COMPLEX PROFILE PRODUCTS USING COMPUTER SIMULATION ». ENGINEERING, ENERGY, TRANSPORT AIC, no 1(108) (27 août 2020) : 123–33. http://dx.doi.org/10.37128/2520-6168-2020-1-14.
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The article conducted a study of calculation methods and the selection of technological parameters for stamping by rolling in complex profile products. It is shown that the achievement of significant sizes of various elements of the workpiece is possible by ensuring the directional flow of metal by changing the relative positions of the roll and the workpiece. The most effective rolling stamping operations are upsetting, deposition and backward extrusion. The zones of workpieces that are deformed under stress conditions have been identified, therefore, to determine the technological capabilities for them, an assessment of the deformation of metals should be carried out. The manufacture of thin-walled elements of the workpiece using the operation of backward extrusion is accompanied by the appearance of significant contact stresses, therefore, to prevent the roll from being removed from the workpiece, back-up rollers should be provided. The analysis of the study showed that the stamping process by rolling over the workpieces with conical and cylindrical rolls makes it possible to control the flow direction of the workpiece material by changing the size and direction of the relative position of the axes of the workpiece roll, relative to the direction of rotation of the workpiece. The technological capabilities of SHO are limited mainly by the loss of stability and destruction of the workpieces, which, in turn, substantially depends on the direction of the metal flow in the contact of the roll with the workpiece. The modeling of the SHO process is considered. It has shown that the stress-strain state, the shape change and the deformability of the workpiece material substantially depend on these parameters. The purpose of the simulation was to analyze the stress-strain (VAT) state and shape change of the workpieces during the deformation process, to determine the energy-power parameters of the process, as well as the geometry of the deforming tool, providing a high-quality product with guaranteed profile filling, accurate dimensions in the transverse and longitudinal directions, as well as surface cleanliness profiled cavity.
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KUTS, V. V., A. S. BYSHKIN et M. S. RAZUMOV. « METHOD FOR DETERMINING THE LIMITS OF ELASTICITY AND PROPORTIONALITY OF MATERIALS FOR SUBSEQUENT DRILLING OF WORKPIECES IN THE STRESS–STRAIN STATE ». Fundamental and Applied Problems of Engineering and Technology 3 (2020) : 164–70. http://dx.doi.org/10.33979/2073-7408-2020-341-3-164-170.
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Drilling holes is one of the most common operations in the manufacture of parts. As a result, improving the efficiency of this process is an urgent task. To improve the efficiency of the drilling process, a method was developed at the Southwestern University for drilling with pre–stressed–deformed material of the workpiece, in which the sample is subjected to elastic deformation at a load that does not exceed the proportionality limit of the workpiece material, that is, when the load is removed, the dimensions of the workpiece remain the same. As part of this work, an experimental device was developed and designed to determine the limits of elasticity and proportionality of materials for subsequent drilling of workpieces in a stress–strain state. This invention will improve the automation and accuracy of measurement. An example of measurement and calculation is considered. Calculation formulas for determining the measurement error are given.
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Guo, C., et S. Malkin. « Analysis of Transient Temperatures in Grinding ». Journal of Engineering for Industry 117, no 4 (1 novembre 1995) : 571–77. http://dx.doi.org/10.1115/1.2803535.
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Temperatures generated in the workpiece during straight surface plunge grinding follow a transient behavior as the grinding wheel engages with and disengages from the workpiece, and throughout the entire grinding pass for workpieces which are shorter than needed to reach a quasi-steady state condition. In the present paper, a thermal model is developed for the transient temperature distribution under regular and creep-feed grinding conditions. Numerical results obtained using a finite difference method indicate that the workpiece temperature rises rapidly during initial wheel-workpiece engagement (cut in), subsequently reaches a quasi-steady state value if the workpiece is sufficiently long, and increases still further during final wheel-workpiece disengagement (cut out) as workpiece material is suddenly unavailable to dissipate heat. Cooling by a nozzle directed at the end face of the workpiece should significantly reduce the temperature rise during cut out.
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Dautzenberg, J. H., S. P. F. C. Jaspers et D. A. Taminiau. « The Workpiece Material in Machining ». International Journal of Advanced Manufacturing Technology 15, no 6 (14 juin 1999) : 383–86. http://dx.doi.org/10.1007/s001700050080.
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Guo, Canzhi, Chunguang Xu, Juan Hao, Dingguo Xiao et Wanxin Yang. « Ultrasonic Non-Destructive Testing System of Semi-Enclosed Workpiece with Dual-Robot Testing System ». Sensors 19, no 15 (31 juillet 2019) : 3359. http://dx.doi.org/10.3390/s19153359.
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With the rapid development of material science, more and more workpieces, especially workpieces with complex curved surfaces, are being made of composite materials. Robotic non-destructive testing (NDT) systems for complex curved surface composite material parts are being used more and more. Despite the emergence of such flexible NDT systems, the detection of semi-enclosed parts is also a challenge for robotic NDT systems. In order to overcome the problem, this paper establishes an NDT solution for semi-enclosed workpieces based on a dual-robot system of synchronous motion, in which an extension arm is installed on one of the robots and presents a trajectory planning method that always ensures the extension arm is parallel to the rotary axis of a semi-enclosed workpiece and that the ultrasonic probes are perpendicular to the workpiece surface. Trajectory analysis experiments and ultrasonic NDT experiments utilizing the optimal water path distance determined by simulation result of multi-Gaussian beam model for two types of semi-enclosed workpieces are performed with the dual-robot NDT system. Experimental results prove that the dual-robot NDT scheme functions well and the planned trajectories are correct. All the hole-shaped artificial defects with diameters ≥3 mm are detected by using 2.25 MHz ultrasonic probes through the transmission testing method. Vivid 3D C-scan image of a small diameter cylindrical workpiece based on the testing result is provided for convenience of observation.
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Bian, Jianxiao, Baoji Ma, Haihong Ai et Lijun Qi. « Experimental Study on the Influence of Tool Electrode Material on Electrochemical Micromachining of 304 Stainless Steel ». Materials 14, no 9 (29 avril 2021) : 2311. http://dx.doi.org/10.3390/ma14092311.
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Different cathode materials have different surface chemical components and machining capacities, which may finally result in different machining quality and machining efficiency of workpieces. In this paper, in order to investigate the influence of cathode materials on the electrochemical machining of thin-walled workpiece made of 304 stainless steel, five cylindrical electrodes are used as the target working cathodes of electrochemical machining to conduct experiments and research, including 45# steel, 304 stainless steel, aluminum alloy 6061, brass H62, and tungsten steel YK15. The stray current corrosion, taper, and material removal rate were used as the criteria to evaluate the drilling quality of efficiency of a thin-walled workpiece made of 304 stainless steel. The research results show that from the perspectives of stray current corrosion and taper, aluminum alloy 6061 is an optimal tool cathode, which should be used in the electrochemical machining of thin-walled workpieces made of 304 stainless steel; on the aspect of material removal rate, the 45# steel, 304 stainless steel, and aluminum alloy 6061 present close material removal rates, all of which are higher than that of brass H62 and tungsten steel YK15. Based on comprehensive consideration of both machining quality and machining efficiency, the aluminum alloy 6061 is the best option as the cathode tool in the electrochemical machining of thin-walled workpieces made of 304 stainless steel.
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Mihaila, Lucian Adrian. « Material Handling Mechanisms Used in Flexible Manufacturing Systems ». Applied Mechanics and Materials 245 (décembre 2012) : 197–202. http://dx.doi.org/10.4028/www.scientific.net/amm.245.197.
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In small and medium batch series manufacturing the small tool and workpiece changing time is one of the main objectives to follow in obtaining high productivity. These auxiliary times are defined as the times consumed with preparing and changing the next tool or workpiece to follow the machining process, times that usually overlap the machining process. For this purpose machining centres are equipped with an automatic tool changer system and an automatic pallet changer system. The palletizing systems imply eliminating the times consumed with the alignment, fixing and clamping of the workpieces, these systems consisting of several mechanisms: the pallet, the automatic pallet changing mechanism, the positioning mechanism and the pallet clamp/unclamp mechanism. In this paper we present an general overview of the automatic pallet changing mechanisms used both in flexible manufacturing systems and machining centres.
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Shtuts, Andrii. « COMPUTER SIMULATION OF THE PROCESS OF STAMPING BY ROLLING CYLINDRICAL AND PIPE PREPARATIONS USING THE DEFORM - 3D SOFTWARE COMPLEX ». Vibrations in engineering and technology, no 4(99) (18 décembre 2020) : 101–13. http://dx.doi.org/10.37128/2306-8744-2020-4-12.
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The purpose of modeling is the analysis of the stress-strain (VAT) [7,14] condition and deformation of tubular, cylindrical workpieces in the deformation process, determining the energy parameters of the process, as well as the geometry of the deforming tool. transverse and longitudinal directions, as well as the cleanliness of the surface of the profiled cavity. This article analyzes the features of local deformation, which define stamping by rolling as an independent type of metal pressure treatment in the metalworking industry. This problem is most effectively solved by using cold plastic deformation processes, which allow to bring the shape of the workpiece as close as possible to the shape of the finished product, and in some cases eliminate the need for further processing. Using the method of cold deformation instead of cutting, you can increase 2… 3 times the utilization of the metal. This ensures high quality of the workpiece surface, improves the physical and mechanical characteristics of the material, increases productivity and creates conditions for full automation of production. Examples of the most complete realization of advantages of stamping by rolling that provides efficiency of industrial use are resulted. In the priority areas of science and technology, a special role is given to energy and resource conservation. In [3] the simulation results for rolling stamping without restriction with one-sided and two-sided restriction of metal flow along the length of lead blanks are presented. Analysis of the experimental study showed that the process of stamping rolling (SHO) workpieces with conical and cylindrical rolls, allows you to control the flow of workpiece material by changing the size and direction of the axes of the workpiece roll, relative to the direction of rotation of the workpiece. The conducted modeling of SHO processes showed that the stress-strain state, deformation and deformability of the workpiece material also significantly depend on these parameters. The technological capabilities of the SHO are limited mainly by the loss of stability and destruction of the workpieces, which, in turn, significantly depends on the direction of flow of metal at the contact of the roll with the workpiece. Thus, the ability to control the direction of flow of the metal largely determines the ability to manufacture workpieces of the desired shape and size without destruction and loss of stability [2].
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Matviychuk, Viktor, Volodymyr Mikhalevich et Mykola Kolisnyk. « EVALUATION OF DEFORMABILITY OF MATERIAL OF PREPARATIONS IN DIRECT AND REVERSE EXTRACTION BY ROLLING STAMPING METHOD ». Vibrations in engineering and technology, no 1(104) (29 avril 2022) : 81–91. http://dx.doi.org/10.37128/2306-8744-2022-1-10.
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The article presents the results of development and research of various technological schemes of the process of stamping by rolling cylindrical and conical rolls to obtain complex profile workpieces. It is shown that the achievement of significant dimensions of the various elements of the workpiece is possible by providing a directed flow of metal by changing the relative position of the roll and the workpiece. The most effective rolling operations are landing, settling, unloading, reverse and direct extrusion. The paper focuses on the analysis of operations of reverse and direct extrusion to obtain complex profile blanks with developed, including thin-walled elements. Since the technological capabilities depend on the deformability of the material, the analysis of the stress-strain state of the workpieces was performed using the method of grids, hardness measurement and microstructural analysis. The main result of the analysis was the construction of ways to deform the particles of the workpiece material in the coordinates "deformation intensity - stress index". Zones of blanks that are deformed in the conditions of "rigid" stress state are established, therefore for these zones the deformability of metals was assessed using the criteria of phenomenological theory. In addition, the assessment of deformability was also performed for areas with the maximum degree of deformation of the material. The manufacture of thin-walled elements of the workpiece, using the operation of reverse extrusion, is accompanied by the appearance of significant contact stresses. To prevent the roll from being pushed out of the workpiece and forming elements with a constant thickness, support rollers should be provided. In the case of direct extrusion, the increase in contact stresses requires the application of additional measures to increase the strength of the tool.
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Rozzi, Jay C., Frank E. Pfefferkorn, Yung C. Shin et Frank P. Incropera. « Experimental Evaluation of the Laser Assisted Machining of Silicon Nitride Ceramics ». Journal of Manufacturing Science and Engineering 122, no 4 (1 décembre 1999) : 666–70. http://dx.doi.org/10.1115/1.1286556.
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To assess the feasibility of the laser assisted machining (LAM) process for the machining of difficult-to-machine materials such as structural ceramics, experiments were performed on silicon nitride workpieces for a wide range of operating conditions. Data for cutting forces and surface temperatures indicate that the lower bound of the material removal temperature for avoidance of cutting tool and/or workpiece fracture corresponds to the YSiAlON glass transition temperature (920–970°C). As temperatures near the cutting tool increase to values above the glass transition temperature, the glassy phase softens, facilitating visco-plastic flow and, correspondingly, the production of semi-continuous or continuous chips. The silicon nitride workpiece machined had a surface roughness of Ra=0.39 μm at the nominal LAM operating condition. Examination of the machined surfaces and chips reveals no detectable sub-surface cracking or significant changes in microstructure, respectively. Relative to grinding, the most significant advantage of LAM is its ability to achieve much larger material removal rates with high workpiece surface quality and reasonable levels of tool wear. [S1087-1357(00)00704-8]
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Moran, Andrew, Brian Skinn, Stephen Snyder et Timothy Hall. « (Digital Presentation) HF-Free, Pulse-Reverse Electrochemical Machining of Tantalum ». ECS Meeting Abstracts MA2022-01, no 25 (7 juillet 2022) : 1220. http://dx.doi.org/10.1149/ma2022-01251220mtgabs.
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Electrochemical machining (ECM) is a manufacturing technology wherein metal is precisely removed by electrochemical oxidation and dissolution/dispersal into an electrolyte solution. ECM is especially well suited for “difficult to cut” materials (high strength/toughness, work-hardening, etc.) such as high strength steel, chrome-copper alloy (C18200), nickel alloy (IN718), cobalt-chrome alloy (Stellite 25) and tantalum-tungsten alloy (Ta10W) since the material removal process involves no mechanical interaction between the tool and the part. In ECM, an electrochemical cell is established wherein the workpiece is the anode and the tool is the cathode; by relative movement of the shaped tool into the workpiece while applying a suitable electrical voltage, the mirror image of the tool is “copied” into the workpiece. Production of parts with complicated and intricate geometries can thus be achieved in these challenging materials by design of a suitably-shaped tool made from a much more easily-machinable material. Compared to mechanical or thermal machining processes, where metal is removed by cutting or electric discharge/laser machining, respectively, ECM does not suffer from tool wear or result in a thermally damaged surface layer on the workpiece. Additionally, the use of pulse and/or pulse-reverse electrical waveforms can enable successful ECM of even highly passive materials using benign, HF-free electrolytes. Advanced materials such as refractories (e.g., W, Mo, Ta, and their alloys) provide highly desirable characteristics such as high strength, corrosion resistance, and survivability in extreme environments (high temperature, high chemical reactivity, plasma exposure, etc.). As motivation to adopt these materials has increased, conventional fabrication methods have proven progressively less able to successfully machine workpieces of the myriad needed geometries. ECM is a natural non-conventional fabrication method for these materials and workpieces, for the reasons described above. In this talk, we will present results from a proof-of-concept demonstration of pulse-reverse ECM of linear grooves in flat Ta and Ta10W alloy coupons using benign electrolytes, illustrating the potential for cost-effective, safe, environmentally-friendly fabrication using these exotic materials.
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Jermolajev, Stepan, et Ekkard Brinksmeier. « A New Approach for the Prediction of Surface and Subsurface Properties after Grinding ». Advanced Materials Research 1018 (septembre 2014) : 189–96. http://dx.doi.org/10.4028/www.scientific.net/amr.1018.189.
Texte intégralRésumé :
This paper presents a diagram of maximum contact zone temperatureTmaxversus contact timeΔt, based on the analysis of workpiece surface layer properties after cylindrical grinding experiments. Apart from resulting surface layer properties, process quantities (Tmax, normal and tangential grinding forcesFn,Ft) are investigated with reference to the resulting workpiece surface layer state as well. Ground workpieces are analyzed by performing Barkhausen noise level measurements together with subsequent metallographic and X-ray diffraction investigations. By mapping characteristic valuesTmaxand the contact timeΔtto corresponding surface layer properties, a general analysis of workpiece material response to the thermo-mechanical load during grinding is possible.
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Kato, T., et H. Fujii. « Temperature Measurement of Workpiece in Surface Grinding by PVD Film Method ». Journal of Manufacturing Science and Engineering 119, no 4B (1 novembre 1997) : 689–94. http://dx.doi.org/10.1115/1.2836810.
Texte intégralRésumé :
The near-surface temperature in the workpiece in surface grinding is measured by applying the PVD film method developed recently for measurement of cutting tool temperature. The boundary, identified clearly, between the melted film zone and unmelted film zone is regarded as the isotherm of the melting point of the film material deposited on the inner surface of the workpiece. The temperature for two kinds of workpieces, plain carbon steel and 18-8 stainless steel, was measured under conventional surface grinding conditions. It was found that the technique is useful in estimating the temperature in the workpiece.
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Kefer, Stefan, Julian Zettl, Cemal Esen et Ralf Hellmann. « Femtosecond Laser-Based Micromachining of Rotational-Symmetric Sapphire Workpieces ». Materials 15, no 18 (8 septembre 2022) : 6233. http://dx.doi.org/10.3390/ma15186233.
Texte intégralRésumé :
Sapphire is a robust and wear-resistant material. However, efficient and high-quality micromachining is still a challenge. This contribution demonstrates and discusses two novels, previously unreported approaches for femtosecond laser-based micromachining of rotational-symmetric sapphire workpieces, whereas both methods are in principal hybrids of laser scanning and laser turning or laser lathe. The first process, a combination of a sequential linear hatch pattern in parallel to the workpiece’s main axis with a defined incremental workpiece rotation, enables the fabrication of sapphire fibers with diameters of 50 μm over a length of 4.5 mm. Furthermore, sapphire specimens with a diameter of 25 μm over a length of 2 mm can be fabricated whereas an arithmetical mean height, i.e., Sa parameter, of 281 nm is achieved. The second process combines a constant workpiece feed and orthogonal scanning with incremental workpiece rotation. With this approach, workpiece length limitations of the first process are overcome and sapphire fibers with an average diameter of 90 µm over a length of 20 cm are manufactured. Again, the sapphire specimen exhibits a comparable surface roughness with an average Sa value of 249 nm over 20 cm. Based on the obtained results, the proposed manufacturing method paves an innovative and flexible, all laser-based way towards the fabrication or microstructuring of sapphire optical devices, and thus, a promising alternative to chemical processes.
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Patel, Chandrahas, et Sachin D. Kore. « Dual Electromagnetic Forming Using Single Uniform Pressure Coil ». Key Engineering Materials 611-612 (mai 2014) : 723–30. http://dx.doi.org/10.4028/www.scientific.net/kem.611-612.723.
Texte intégralRésumé :
Electromagnetic Forming (EMF) is a high-speed forming process that can be applied for shaping, joining and cutting of workpieces made of electrically conductive material eg. aluminium. This paper proposes a dual electromagnetic forming method. Energy efficiency of the dual electromagnetic forming is compared with the single sided electromagnetic forming using FEM simulations. In uniform pressure rectangular coil, the top layer of the coil assists in the deformation of the workpiece while the bottom layer hinders the workpiece deformation.To make the bottom layer of the coil also to assist in the deformation of the workpiece, a uniform pressure rectangular coil is designed and placed between the two sheet metal workpiece. The efficiency of the two processes are compared by determing the maximum deformation obtained for each case.
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Pan, Wei Min, Ke Ke Shi et Xian Qing Lei. « Research on Electrical Discharge Machining for Injection Mold of Automotive Connector ». Key Engineering Materials 522 (août 2012) : 17–20. http://dx.doi.org/10.4028/www.scientific.net/kem.522.17.
Texte intégralRésumé :
Electrical discharge machining (EDM) processing is generally applied on the area of molding plastic component or mating surface required high accuracy. The areas determine the quality of the plastic components. The principle of EDM is based on the material vaporization of high potential difference across the workpiece and Tool electrode. Tool electrode and workpieces are discontiguous when the EDM processes. Because there is no mechanical contact, Hardness and strength of the workpiece material have minimal effect on the material removal rate .The application of EDM technology on injection mold of automotive connector is focused on in this paper. Processing of the complex cores is researched. The design and processing of the tool electrode have been completed in the meantime.
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Hwang, Joong-Ki. « Effect of Contact Pressure on Strain Distribution during Compression-Type Bulk Forming Processes ». Materials 16, no 14 (17 juillet 2023) : 5041. http://dx.doi.org/10.3390/ma16145041.
Texte intégralRésumé :
Inhomogeneity of the material properties of workpieces developed during compression-type bulk forming processes (CBFPs) is an important issue. The effect of contact pressure on the workpiece surface on the strain inhomogeneity in the workpiece was investigated to understand and reduce the formation of strain inhomogeneity during CBFPs. Workpieces fabricated via rod caliber rolling, rod flat rolling, plate flat rolling, and rod compression were analyzed and compared. The extent of strain inhomogeneity in a workpiece differs with the forming process, because the occurrence of macroscopic shear bands (MSBs) is dependent on the workpiece shape and tool design. A flat-rolled rod exhibits the maximum strain inhomogeneity, whereas a flat-rolled plate shows the minimum strain inhomogeneity. The occurrence of MSBs was influenced by the distribution of the normal contact pressure or compression stress. The MSBs were stronger when the contact pressure was higher in the edge region of the surface. For example, the flat-rolled plate exhibited weak MSBs due to the relatively uniform or higher contact pressure on the central region. In contrast, strong MSBs appeared in the flat-rolled rod and compressed rod, because the contact pressure in the edge region of these two processes was high. Thus, the strain inhomogeneity in a workpiece fabricated via CBFPs can be reduced by controlling the contact pressure distribution on the workpiece surface.
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Wang, Jing Si, Keita Shimada, Masayoshi Mizutani et Tunemoto Kuriyagawa. « Smoothed Particle Hydrodynamics Simulations for Ultrasonic Machining of Different Workpiece Materials ». Advanced Materials Research 1017 (septembre 2014) : 758–63. http://dx.doi.org/10.4028/www.scientific.net/amr.1017.758.
Texte intégralRésumé :
The material removal in ultrasonic machining (USM) is based on brittle fracturing of workpiece materials. The properties and fracture behavior are different for varied materials, and they would have an influence on the machining performance of USM. The smoothed particle hydrodynamics (SPH) method was used to simulate the USM process for different workpiece materials. Three typical hard and brittle materials, i.e. silicon carbide (SiC), alumina (Al2O3), and glass will be used as the workpiece materials. Experiments are also conducted for comparing with the simulation results. Through this study, the material fracturing processes for different work materials are shown visually using the SPH method, which is very useful for USM study.
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Zhou, Jun, Jian Xin Deng, Li Li Liu, Zhan Qiang Liu et Xing Ai. « Intelligent Matching of Cutting Tools with Workpiece Materials ». Key Engineering Materials 315-316 (juillet 2006) : 411–15. http://dx.doi.org/10.4028/www.scientific.net/kem.315-316.411.
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With the advantage of Case-Based Reasoning (CBR), selection method about matching of cutting tools with workpiece materials is presented through establishing the matching knowledge and rules in such respects as mechanical, physical and chemical properties of cutting and workpiece materials. Intelligent matching system of cutting tools with workpiece materials is developed based on CBR. This system has such advantages as higher matching speed and better accuracy, which offers a strong support tool for material selection between the cutter and workpiece.
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Moumi, Eric, Philipp Wilhelmi, Christian Schenck, Marius Herrmann et Bernd Kuhfuss. « Material flow control in plunge micro rotary swaging ». MATEC Web of Conferences 190 (2018) : 15014. http://dx.doi.org/10.1051/matecconf/201819015014.
Texte intégralRésumé :
In rotary swaging, the material flow is not fully controlled by closure of the forming dies. This is especially noticeable in plunge rotary swaging of rod, where the workpiece is positioned into the forming zone und processed locally. As result, an uncontrolled elongation of the workpiece in axial direction takes place and an axial position shift of the workpiece relative to the dies occurs. This is a special challenge in production of linked micro parts, where single parts are interconnected in order to enable the handling as a strip and thereby a roll-to-roll production. The axial shift influences not only the subsequent positioning of neighbouring parts, but also the final geometry of the currently processed part. The presented investigation analyses the material flow during plunge micro rotary swaging on basis of in-process measurements of the workpiece shift on both sides of the forming zone as well as with the help of contour measurements of the processed parts. It is shown that the measured shift is strongly influenced by the workpiece clamping and fixation and that it can be controlled by applying low axial forces to the workpiece on one or both sides of the forming zone. Further, the geometry of the workpiece can be affected by these measures.
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Baili, Maher, Vincent Wagner, Gilles Dessein, Julien Sallaberry et Daniel Lallement. « An Experimental Investigation of Hot Machining with Induction to Improve Ti-5553 Machinability ». Applied Mechanics and Materials 62 (juin 2011) : 67–76. http://dx.doi.org/10.4028/www.scientific.net/amm.62.67.
Texte intégralRésumé :
The manufacturing of aeronautic parts with high mechanical properties requires the use of high performance materials. That’s why; new materials are used for landing gears such as the titanium alloy Ti-5553. The machining of this material leads to high cutting forces and temperatures, and poor machinability which requires the use of low cutting conditions. In order to increase the productivity rate, one solution could be to raise the workpiece initial temperature. Assisted hot machining consists in heating the workpiece material before the material removal takes place, in order to weaken the material mechanical properties, and thus reducing at least the cutting forces. First, a bibliography review has been done in order to determine all heating instruments used and the thermal alleviation that exists on conventional materials. An induction assisted hot machining was chosen and a system capable to maintain a constant temperature into the workpiece during machining (turning) was designed. Trails permit to identify the variation of cutting forces according to the initial temperature of the workpiece, with fixed cutting conditions according to the TMP (Tool-Material-Pair) methodology at ambient temperature. Tool life and deterioration mode are identified notably. The results analysis shows a low reduction of specific cutting forces for a temperature area compatible with industrial process. The reduction is more important at elevated temperature. However, it has consequences on quality of the workpiece surface and tool wear.
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Straka, Luboslav, et Gabriel Dittrich. « Impact of physical properties of workpiece material on material removal rate at EDM ». International Journal of Engineering and Management Sciences 4, no 1 (3 mars 2019) : 230–37. http://dx.doi.org/10.21791/ijems.2019.1.29.
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The volume stock removal from the workpiece during the EDM is one of the important parameters that characterize the productivity of the electro-erosion process itself. Therefore, in terms of the economic efficiency of the electro-erosion process, it is appropriate that the value of the MRR parameter is as high as possible. The paper describes the results of experimental research to identify the extent of influence of the physical properties of the workpiece material on the workpiece material removal rate at EDM. The experiments were carried out using an Aggregron Hyperspark 3 electro-erosion machine on selected tool steels. As a tool electrode material for experimental purposes, graphite with the designation EX-60 was chosen because of its practical advantages.
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Zhang, Chang Qing, Bo Qiang Li et Xi Jing Wang. « Lap Joint Properties of FSBRed Dissimilar Metals AZ31 Mg Alloy and DP600 High-Strength Steel with Various Parameters ». Advanced Materials Research 228-229 (avril 2011) : 427–32. http://dx.doi.org/10.4028/www.scientific.net/amr.228-229.427.
Texte intégralRésumé :
The Friction stir blind riveting (FSBR) process consists of a blind rivet is driven at high rotational speed and brought into contact with the workpieces, thereby generating frictional heat between the rivet and the workpiece, which softens the workpiece material and enables the rivet to be driven into the workpieces under reduced force. The riveting of lap joint of AZ31B(3mm) magnesium alloys plate and a DP600 (1mm) high strength steel plate was produced by FSBR using 2200rpm rotation speed, various feet rates and different lap mode to investigate the effects of the joint morphology and strength. The joint strength depended strongly on the shank of rivet itself shear strength，however in which case the strength of joint impacted by rivet assembly quality (the lap of plates, the tightness rivet of workpiece). So positioning the steel sheet on the top is desirable, the maximum shear strength of the joint reached about 6.0KN.
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Xu, Lin Hong, Zheng Feng Jiang et Jan Eric Ståhl. « Machinability Prediction of Workpiece Material with a Diagraph Method ». Advanced Materials Research 97-101 (mars 2010) : 2072–75. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.2072.
Texte intégralRésumé :
This work presents a diagraph method for the description and predication of the potential machinability of work materials. In the method, a radar chart with five axes was used to examine the machinability of different work materials and each axis representing a behavior or property, i.e. abrasiveness or hardness of workpiece material by grading the 5 different machinability properties. Such charts are seen to be helpful in the setup work to machine the new materials or unknown materials when choosing suitable tool properties and the cutting data suitable for the new material machining.
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Wang, Rensheng, Shichao Xiu, Cong Sun, Shanshan Li et Xiangna Kong. « Study on Material Removal Model by Reciprocating Magnetorheological Polishing ». Micromachines 12, no 4 (8 avril 2021) : 413. http://dx.doi.org/10.3390/mi12040413.
Texte intégralRésumé :
In this study, a new reciprocating magnetorheological polishing (RMRP) method for a flat workpiece was proposed. Based on the RMRP principle and Preston equation, the material removal rate (MRR) model of the RMRP as well as its normal polishing pressure model was established. On this basis, the effects of different technological parameters including workpiece rotation speed, eccentric wheel rotation speed and eccentricity on the MRR of the workpiece were investigated. The K9 optical flat glass was polished with the RMRP setup to verify the MRR model. The experimental results showed that the effect of workpiece rotation speed on the MRR was much greater than that of eccentric wheel rotation speed and eccentricity, and the MRR increased from 0.0115 ± 0.0012 to 0.0443 ± 0.0015 μm/min as workpiece rotation speed rose. The optimum surface roughness reduced to Ra 50.8 ± 1.2 from initial Ra 330.3 ± 1.6 nm when the technical parameters of the workpiece rotation speed of 300 rpm, the eccentric wheel rotation speed of 20 rpm and the eccentricity of 0.02 m were applied. The average relative errors between the theoretical and experimental values were 16.77%, 10.59% and 7.38%, respectively, according to the effects of workpiece rotation speed, eccentric wheel rotation speed and eccentricity on MRR.
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Salunke, Saurav. « Testing Tool Material on Scratch Tester ». International Journal for Research in Applied Science and Engineering Technology 9, no 12 (31 décembre 2021) : 1926–30. http://dx.doi.org/10.22214/ijraset.2021.39661.
Texte intégralRésumé :
Abstract: In manufacturing industry cutting tools are considered as the backbone of the metal cutting operation. In metal cutting operation there is relative motion between the tool and the workpiece. As the tool material is harder than the workpiece material, there is deformation of the workpiece which acts as a base for the formation of chips. If we observe the process of metal cutting, we can easily find out that there is a considerable amount of heat generated during the machining operation. As there is a point of interface between the tool and the workpiece, there is absorption of generated heat into both the tool as well as work material. Due to the absorption of the heat there is distortion in the tool material. In this research article we have taken the base parameters as speed, load and stroke and the output parameter is taken as the load which breaks the coating of the tool. Keywords: tool coating, scratch tester, speed, stroke, coating.
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Pardede, Michael Louddrup. « PENGARUH VARIASI PEMAKAIAN CAIRAN PENDINGIN (COOLANT) TERHADAP KEKASARAN PERMUKAAN BESI AS PUTIH ST 41 HASIL PEMBUBUTAN SILINDRIS ENGSEL ». JURNAL PERSEGI BULAT 1, no 2 (7 décembre 2022) : 17–26. http://dx.doi.org/10.36490/jurnalpersegibulat.v1i2.473.
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Coolant has special uses in the lathe machining process. In addition to extending tool life, coolant in some cases can reduce force and smooth the surface of the manufactured product. This study aims to determine the effect of differences in the use of coolant on the surface roughness of the hinge cylindrical turning (hinge) of ST 41 iron material. The choice of this material is because it is often used in machining tools and the price is economical. This type of research is experimental research conducted in a laboratory. This study uses quantitative methods. In the multilevel straight turning process as many as 3 hinge workpieces using 3 types of coolant (coolant). Hinge workpiece A uses water cooling without a mixture, hinge workpiece B uses water cooler with a mixture of coolant (coolant) and hinge workpiece C uses lubricant coolant. The turning of the three hinge workpieces is done by cylindrical turning. The results showed that the use of the lowest mean surface roughness cooling type was water cooler with a mixture of coolant (1,254 mm), the highest type of surface roughness average value was oil cooler (1,850 mm). While the average value of moderate surface roughness is the type of coolant (1,489 mm).
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Huuki, Juha, Mikael Hornborg et Jermu Juntunen. « Influence of Ultrasonic Burnishing Technique on Surface Quality and Change in the Dimensions of Metal Shafts ». Journal of Engineering 2014 (2014) : 1–8. http://dx.doi.org/10.1155/2014/124247.
Texte intégralRésumé :
This paper presents ultrasonic burnishing as a mechanical surface treatment for improving the quality of rotating shafts. Ultrasonic burnishing is a modern method for finishing workpieces to produce a good surface quality. This process improves the surface quality and increases the surface hardness of the workpiece, and the surface roughness of the workpiece improves. As a result, wear resistance and fatigue life increase. Furthermore, these improvements are achieved without expensive equipment or long processing times. In this paper the influence of the ultraburnishing technique on the change in diameter and its effects on the out-of-roundness of rotating shafts are investigated. This paper also takes a look at the magnitudes of the improvement of the surface roughness as a result of using ultrasonic burnishing. Three different materials, aluminium, 34-CrNiMo6 tempering steel, and S355J2 structural steel, are examined. The results showed that ultrasonic burnishing is a treatment that improves the quality of components. Ultrasonic burnishing also has a reducing effect on the final diameter and out-of-roundness and increases the hardness of the workpiece. It can also be stated that the material of the workpiece does not have a significant effect on the magnitude of the reduced surface roughness values.
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Bratan, Sergey, Stanislav Roshchupkin, Anastasia Chasovitina et Kapil Gupta. « The effect of the relative vibrations of the abrasive tool and the workpiece on the probability of material removing during finishing grinding ». Metal Working and Material Science 24, no 1 (15 mars 2022) : 33–47. http://dx.doi.org/10.17212/1994-6309-2022-24.1-33-47.
Texte intégralRésumé :
Introduction. Grinding remains the most efficient and effective method of final finishing that is indispensable in the production of high-precision parts. The characteristic features of grinding materials are that the removal of the material roughness of the workpiece surface occurs due to the stochastic interaction of the grains of the abrasive material with the surface of the workpiece, in the presence of mutual oscillatory movements of the abrasive tool and the workpiece being processed. During processing workpieces with abrasive tools, the material is removed by a large number of grains that do not have a regular geometry and are randomly located on the working surface. This makes it necessary to apply probability theory and the theory of random processes in mathematical simulation of operations. In real conditions, during grinding, the contact of the wheel with the workpiece is carried out with a periodically changing depth due to machine vibrations, tool shape deviations from roundness, unbalance of the wheel or insufficient rigidity of the workpiece. To eliminate the influence of vibrations in production, tools with soft ligaments are used, the value of longitudinal and transverse feeds is reduced, but all these measures lead to a decrease in the operation efficiency, which is extremely undesirable. To avoid cost losses, mathematical models are needed that adequately describe the process, taking into account the influence of vibrations on the output indicators of the grinding process. The purpose of the work is to create a theoretical and probabilistic model of material removing during finishing and fine grinding, which allows, taking into account the relative vibrations of the abrasive tool and the workpiece, to trace the patterns of its removal in the contact zone. The research methods are mathematical and physical simulation using the basic provisions of probability theory, the laws of distribution of random variables, as well as the theory of cutting and the theory of deformable solids. Results and discussion. The developed mathematical models allow tracing the effect on the removal of the material of the superimposition of single sections on each other during the final grinding of materials. The proposed dependencies show the regularity of the stock removal within the arc of contact of the grinding wheel with the workpiece. The considered features of the change in the probability of material removal when the treated surface comes into contact with an abrasive tool in the presence of vibrations, the proposed analytical dependences are valid for a wide range of grinding modes, wheel characteristics and a number of other technological factors. The expressions obtained allow finding the amount of material removal also for the schemes of end, profile, flat and round external and internal grinding, for which it is necessary to know the magnitude of relative vibrations. However, the parameters of the technological system do not remain constant, but change over time, for example, as a result of wear of the grinding wheel. To assess the state of the technological system, experimental studies are carried out taking into account the above changes over the period of durability of the grinding wheel.
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Ibañez, Aratz Iturgaiz, Pedro Jose Arrazola et Klaus Bonde Ørskov. « Workpiece Material Influence on Stability Lobe Diagram ». Procedia Manufacturing 47 (2020) : 479–86. http://dx.doi.org/10.1016/j.promfg.2020.04.342.
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Kundrák, János, Vladimir Fedorovich, Angelos P. Markopoulos, Ivan Pyzhov et Yevgeniy Ostroverkh. « Theoretical Assessment of the Role of Bond Material during Grinding of Superhard Materials with Diamond Wheels ». Machines 10, no 7 (5 juillet 2022) : 543. http://dx.doi.org/10.3390/machines10070543.
Texte intégralRésumé :
The grinding of superhard materials poses an important challenge to manufacturing industry, due to the increased wear and the high possibility of fracture of both the wheel and workpiece material. Various strategies have been proposed for effective grinding of these materials, but further research is still required, especially in cases in which the hardness of the wheel and the workpiece are almost equal. In this study, the role of the bond of a diamond grinding wheel during the processing of superhard materials, such as synthetic diamond, is investigated using theoretical models and FE simulation. Six different types of bonds are studied and the effect of their properties on the stress distribution of workpiece material is determined. Results indicate that even a slight increase in elastic modulus can affect considerably the stress state of the workpiece, directly affecting the critical embedding value of grains into the bond, something that can alter considerably the efficiency of grinding superhard materials. Thus, grinding wheels with bonds of high elastic modulus should be selected in order to increase grain retention, increase processing efficiency, and reduce specific consumption even at higher cross feeds and wheel speeds.
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Očkajová, A. « The tool wear versus its tool material and workpiece material ». Holz als Roh- und Werkstoff 54, no 2 (mars 1996) : 105–7. http://dx.doi.org/10.1007/s001070050147.
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Lee, Young Seon, J. H. Lee, Yong Nam Kwon et T. Ishikawa. « Effects of Material Properties on Elastic Characteristics of Cold Forged Part ». Materials Science Forum 449-452 (mars 2004) : 853–56. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.853.
Texte intégralRésumé :
The dimension of cold forged part is larger than that of the die cavity. The difference could be originated from the various features, such as the elastic characteristics of die and workpiece, thermal influences, and machine-elasticity. Among these features, elastic behavior of die and workpiece has been considered as the most important element for the precision cold forging. In the present study, the effect of material properties of both workpiece and die on the dimensional precision of forged part was investigated using FE and experimental analyses. Three materials, such as SCM420H, Cu-OFHC and Al6061 alloy, were used to divide the effect of the elastic modulus and flow stress on the dimension specifically. From the results of FEA, the elastic deformation of die was found to be more dominant than that of workpiece. The die expansion depends on the flow stress of workpiece during a loading stage. On the other hand, the die contraction during unloading was affected by both the flow stress and elastic modulus of workpiece. The elastic modulus of workpiece affects the elastic recovery of forged part after ejecting stage.
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Galaeva, E., et P. Prosuntsov. « Simulation of the curing of composite materials using microwave radiation with control of individual magnetrons ». E3S Web of Conferences 376 (2023) : 01024. http://dx.doi.org/10.1051/e3sconf/202337601024.
Texte intégralRésumé :
The traditional approach to the organization of the technological process of curing a binder polymer using microwave radiation is to rotate a workpiece around one axes in order to reduce the non-uniformity of its heating. Nevertheless, using this technical solution might lead to considerable difficulties when rotating larger workpieces, creating desired pressure on their surfaces and diagnosing the process. The approach suggesting that the workpiece itself remains stationary while the uniformity of its heating is achieved by creating a traveling electromagnetic wave in the operating area is to be considered a more promising direction in the development of curing technology. However, creating such a wave would require constructing a new and rather complex scheme for individual control of magnetrons, the theory of which has not been developed yet. The present work offers such a scheme of individual control and shows that using it allows to reduce the non-uniformity of the temperature field in a workpiece made of a polymer composite material with the maximum deviation of no more than 60 K, whereas the level of non-uniformity in the central part of the workpiece is not higher than 21 K.
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Unyanin, Alexander N., et Pavel R. Finageev. « Research of the Influence of the Physical and Mechanical Properties of the Workpiece Material on the Temperature Field of the Turning Process ». Materials Science Forum 1037 (6 juillet 2021) : 300–308. http://dx.doi.org/10.4028/www.scientific.net/msf.1037.300.
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To predict the parameters of the quality of the processed parts and the period of durability of the cutting tool, mathematical models are needed that will allow us to calculate not only the mathematical expectation of the parameters of the machining process, but also the dispersion of these parameters. The working capacity of the tool and the quality parameters of the parts depend significantly on the temperature on the contact surfaces of the tool, as well as on the surface of the workpiece. Mathematical dependences for calculating the components of the total heat generation capacity during turning are given. It is assumed that the yield stress, which determines the cutting and friction forces on the contact surfaces of the cutter, workpiece and chip, depends on the temperature in the area of plastic deformation. The heat transfer at the boundaries of objects in contact with the process fluid or air is given in the form of the Newton-Richman law. The equations of thermal conductivity of contacting objects were solved together with the general boundary conditions in the contact zone, using the finite element method. The results of numerical simulation of the main component of the cutting force and temperatures in the contact zones of the face of the cutter with the chips and the fiank surface with the workpiece, depending on the yield strength of the workpiece material, are presented. The values of fluctuations in the cutting force and contact temperatures depending on the spread of the yield stress of the workpiece material during turning of workpieces made of 45 and 12X18H10T steels are determined. Based on the results of numerical modeling, regression equations are obtained for calculating the tangential component of the cutting force, the temperatures on the face and flank surfaces of the cutter, and the temperature on the surface of the workpiece.
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Liu, Dong Sheng, Ming Luo et Ding Hua Zhang. « Experimental Analysis of Damping Fixture for Thin-Walled Workpiece Milling ». Materials Science Forum 836-837 (janvier 2016) : 296–303. http://dx.doi.org/10.4028/www.scientific.net/msf.836-837.296.
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Thin-walled workpieces are widely used in the aerospace manufacturing industry in order to reduce the weight of structure and improve working efficiency. However, vibration is easy to occur in machining of thin-walled structures due to its low stiffness. Machining vibration will result in lower machining accuracy as well as machining efficiency. In order to reduce the machining vibrations of thin-wall workpieces, commonly used method is to select proper machining parameters according to the chatter stability lobes, which is generated according to the machining system parameters. However, this method requires exact system parameters to be determined, which are always changing in the machining process. In this paper, a special designed fixture with damping materials for the thin-walled workpiece is presented based on the machining vibration control theory, and analysis of the effect of vibration suppressing is obtained through the contrast of vibration tests of milling the thin-walled workpiece on the damping clamp. The damping material is used to consume vibration energy and provide support for thin-walled structure. Machining test was carried out for thin-walled structure machining to validate the effectiveness of the proposed method.
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Surmann, Tobias, Eduard Ungemach, Andreas Zabel, Raffael Joliet et Andreas Schröder. « Simulation of the Temperature Distribution in NC-Milled Workpieces ». Advanced Materials Research 223 (avril 2011) : 222–30. http://dx.doi.org/10.4028/www.scientific.net/amr.223.222.
Texte intégralRésumé :
In most cases the simulation of temperature distributions in machined workpieces is carried out by moving a heat source along a predefined workpiece model within a commercial FEM-system. For performance reasons, the material removal is often neglected or performed by removing small predefined parts of the workpiece. Furthermore, the heat source often has a constant heat flux and therefore it is not dependent on the current tool engagement. In this paper we present a voxel-based finite difference method for the thermal behavior of the process-state dependent workpiece, which is integrated into the milling simulation system NCChip, developed at the ISF. This simulation is capable of modeling the cutting forces along any arbitrary NC-path. Since the tool rotation and the cutting edges in this time domain simulation are divided into discrete angle steps and cutting wedges respectively, the thermal energy that is applied to the workpiece at each time step and at each cutting wedge can be computed as a fraction of the corresponding cutting work. In this way, the correct heat is introduced to the workpiece exactly at the current contact zone of the tool.