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The development of Single Point Diamond Turning(SPDT) technique provided technologic and technical base for the mass production and application of aluminum mirrors. To ensure the image quality of the optical system, stress-caused... more
The development of Single Point Diamond Turning(SPDT) technique provided technologic and technical base for the mass production and application of aluminum mirrors. To ensure the image quality of the optical system, stress-caused distortion of reflective surface by mounting pretension stress and uneven mounting surfaces needed to be attenuated. Multiple typical structural shapes of the stress-relief support were demonstrated and the design principle was summarized. The SPDT technique created a new technical route to aid the optical assembly process. The design of assembly assisted by SPDT was showed in instances of reflective surfaces on unilateral side and bilateral sides in single mirror and detached double mirrors. The integral SPDT machining flow of optical surfaces, structural mounting surfaces, transferring datum and reference surfaces of interference detection linking with concrete examples implemented the transfer of high-precision assembly reference and ensured high-accuracy alignment of mirrors. This method could improve the assembly efficiency and shorten the manufacture period of optical systems.
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In mechanical manufacturing, the surface roughness of a machined part is a significant parameter to evaluate the products’ quality, and as a result, it must be thoroughly measured. Many researches have been studied over the past few to... more
In mechanical manufacturing, the surface roughness of a machined part is a significant parameter to evaluate the products’ quality, and as a result, it must be thoroughly measured. Many researches have been studied over the past few to reduce the inherent drawbacks, such as contact, off-line inspection, speed of limited measurement, in the conventional measurement system using contact method. In this paper, the feasibility of the contactless inspection of part surface roughness using Microsoft Kinect v2 have been demonstrated. The part roughness parameters have been estimated by using of PCA plane fitting on point cloud data. In addition, the results received with the Microsoft Kinect v2 system are finally compared to those received with a stylus contact surface roughness measurement system to verify the proposed approach within this paper.
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As an efficient and fast developing surface finishing technique, polishing processes have been widely used in the machining of aero-engine blisk blade. Since a number of processing input variables will influence surface quality and... more
As an efficient and fast developing surface finishing technique, polishing processes have been widely used in the machining of aero-engine blisk blade. Since a number of processing input variables will influence surface quality and production time, controlling surface finish and machining efficiency require a carefully designed combination of various processing parameters. Therefore, this paper presented a comprehensive multi-objective parameter optimization method that integrates grey relational analysis (GRA), radial basis function (RBF), as well as firefly algorithm (FA). The purpose is to simultaneously obtain the optimal parameter combination for minimum surface roughness and the greatest material removal rate by optimizing rotational speed, feed rate and polishing force in Ti-6Al-4V blisk blade polishing. The hybrid experiments were carried out by combining the orthogonal experimental design with the single-factor experimental design. GRA was run for converting multi-objective...
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Bai bao nay giới thiệu tổng quan tinh hinh sản xuất, chế tạo của nganh cơ khi tự động hoa va cơ điện tử nước ta hiện nay; phân tich vai tro của khoa học cong nghệ trong nganh cong nghiệp cơ khi tự động hoa va cơ điện tử; trinh bay một... more
Bai bao nay giới thiệu tổng quan tinh hinh sản xuất, chế tạo của nganh cơ khi tự động hoa va cơ điện tử nước ta hiện nay; phân tich vai tro của khoa học cong nghệ trong nganh cong nghiệp cơ khi tự động hoa va cơ điện tử; trinh bay một cach nhin, cach tiếp cận để đưa khoa học cong nghệ vao sản xuất, chế tạo cơ khi; va đanh gia sự lien kết tich hợp cộng năng của cac nganh khoa học cong nghệ: cơ khi, điện, điện tử, điều khiển học, cong nghệ thong tin, cong nghệ vật liệu,…va cả khoa học về quản li, thực sự la vấn đề cốt loi trong sự phat triển của cac sản phẩm cơ khi tự động hoa va cơ điện tử, dưới đây gọi chung la cơ khi.
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This chapter used the Taguchi experimental design method in order to study the surface roughness and vibration during thermal-assisted milling of SKD11 steel. The effect of cutting parameters such as cutting speed, feed rate, cutting... more
This chapter used the Taguchi experimental design method in order to study the surface roughness and vibration during thermal-assisted milling of SKD11 steel. The effect of cutting parameters such as cutting speed, feed rate, cutting depth and support elevated temperatures on the output data were evaluated. Multi-objective optimization for minimum both surface roughness and vibration was also estimated to improve the cutting process. The optimal set of control parameters to achieve the minimum of surface roughness and vibration amplitude could be obtained as Vc = 280 m/min, f = 230 mm/min, t = 0.5 mm, T = 400 °C.
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Electric discharge machining (EDM) is widely used for machining difficult to cut materials, complex shapes and products requiring high precision work. The limitations of this process are the low productivity and low surface quality after... more
Electric discharge machining (EDM) is widely used for machining difficult to cut materials, complex shapes and products requiring high precision work. The limitations of this process are the low productivity and low surface quality after machining. Therefore, to overcome these limitations of EDM process is an utmost concern of the present study. This paper presents the study of the influence of titanium powder mixed in dielectric fluid on the surface quality of SKD61 steel machined by EDM process. The machined surface was characterized for surface roughness, thickness of heat-affected zone, chemical composition, microhardness and topography. Results of the characterization shows that powder mixed in dielectric medium can be a solution to improve the quality of machined surface.
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Nowadays, increasing productivity and quality of machining become major challenges of the metal cutting process. Due to the complexity of the chip formation process at high cutting speeds, the finite element method (FEM) has been widely... more
Nowadays, increasing productivity and quality of machining become major challenges of the metal cutting process. Due to the complexity of the chip formation process at high cutting speeds, the finite element method (FEM) has been widely used as an approximate solution. In the metal cutting, the chip formation is essentially concerned with the large strains and the high strain rates. In this chapter, two numerical models with and without strain rate effects are proposed. An appropriate model is then verified by comparing the simulated cutting forces under varying cutting parameters. The simulation model with strain rate is consistent with the experimental value, whereas the model without strain rate underestimates the cutting forces. The strain rate also modifies the cutting forces owing to the stresses that occurred at cutting regions and significantly affected by the strain rate.
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The vacuum pump usually used traditional curves such as the circular, cycloidal curves and their combinations to construct tooth profile. However, to increase efficiency and design flexibility for ...
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It is very essential to form such high stregth and hard-to-cut materials by using modern machining methods. It is important to introduce the efforts on modification of the process for improving the machining quality. In the present... more
It is very essential to form such high stregth and hard-to-cut materials by using modern machining methods. It is important to introduce the efforts on modification of the process for improving the machining quality. In the present investigation, an effort was made to analyze the effects of micro size aluminium particles mixed dielectric medium under different powder concentration on machining titanium alloy in electro erosion process. The response-surface-methodology(RSM) based algorithm was utilized to analyze the performance measures by considering machinning time with Cost of Goods Manufactured (COGM) method in PMEDM process. It was found that the micron size powders can significantly help to enhance the surface quality of the Ti-6Al-4V surface during machining in EDM process. The presence of carbon, oxygen elements and the formation of surface oxides and carbides has been found due to the decomposition of dielectric fluid in PMEDM process. The lower deep cavities and uniform ma...
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This paper introduces a study on multi-criteria optimization of the dressing parameters in surface grinding for 90CrSi tool steel. The aim of the study is to minimize the surface roughness, the normal shear force and maximize the grinding... more
This paper introduces a study on multi-criteria optimization of the dressing parameters in surface grinding for 90CrSi tool steel. The aim of the study is to minimize the surface roughness, the normal shear force and maximize the grinding wheel life by using Taguchi method and Grey Relational Analysis (GRA). This multi-objective optimization is obtained by optimizing four four-level and two two-level dressing parameters in sixteen experiments based on an orthogonal array L16(44×22). From the results of the study, the optimum dressing parameters were proposed. Also, to evaluate the optimum dressing model, an experiment was performed. The results of the comparison between the predicted model and the experiment show that the proposed model has been proven and it can be used for further applying of surface grinding.
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This study aims to optimize the dressing parameters of grinding wheel for 9CrSi tool steel to minimize roughness average and flatness tolerance using Taguchi method and Grey Relational Analysis (GRA). These objectives are minimized by... more
This study aims to optimize the dressing parameters of grinding wheel for 9CrSi tool steel to minimize roughness average and flatness tolerance using Taguchi method and Grey Relational Analysis (GRA). These objectives are minimized by optimizing four four-level and two two-level dressing parameters in sixteen experiments based on an orthogonal array L16(44×22). Taguchi method and GRA are combined to solve the multi-objective optimization problem and determine optimal dressing parameter level combination. Results show that, the optimal dressing parameters to obtain the minimal roughness average and flatness tolerance are coarse dressing depth of 0.025 mm, coarse dressing times of 3 times, fine dressing depth of 0.005 mm, fine dressing times of 2 times, non-feeding dressing of 3 times and dressing feed rate of 1.6 m/min, respectively. Experiments with the optimized dressing parameters have been done to verify the predict model. Results of the roughness average and flatness tolerance f...
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In this article, a deep-drawing process using a double-action hydraulic press is examined for its ability to machine the shaping deformation of a fuel-filter cup made from SPCC steel. Many researchers have studied the geometric, physical,... more
In this article, a deep-drawing process using a double-action hydraulic press is examined for its ability to machine the shaping deformation of a fuel-filter cup made from SPCC steel. Many researchers have studied the geometric, physical, and technological parameters of the deep-drawing process. However, most of those studies ignored the optimization parameters of the two shaping deformation states to ensure uniformity of thickness and the disappearance of wrinkling and tearing during machining. In this study, geometric and technological parameters (e.g. blank-holder force, die-shoulder radius, and radial clearance between punch and die) are optimized in both states. The deep-drawing process for a fuel-filter cup is simulated using ABAQUS software, and optimal parameters are determined by applying the Taguchi orthogonal array computation and combining it with an analysis of variance method. The numerical results are then verified with corresponding experiments. The obtained numerica...
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This paper aims to analysis the effect of coolant parameters on surface roughness in internal cylindrical grinding of annealed 9CrSi steel. The concentration and flow rate of the coolant are investigated in thirteen experiments by central... more
This paper aims to analysis the effect of coolant parameters on surface roughness in internal cylindrical grinding of annealed 9CrSi steel. The concentration and flow rate of the coolant are investigated in thirteen experiments by central composite design and response surface method. The effect of each parameter and their interaction on the surface roughness are analyzed by their regression model. From that model, optimal parameters are determined to obtain the minimum surface roughness. The measured roughness matches with the predicted roughness from the regression model. This proposed is proven and it can be further applied for optimizing other machining processes.
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This paper presents experimental studied results about surface roughness during end milling SKD11 steel under room temperature and work-piece preheated condition. Conventional samples were first performed. The samples which are same... more
This paper presents experimental studied results about surface roughness during end milling SKD11 steel under room temperature and work-piece preheated condition. Conventional samples were first performed. The samples which are same technical parameters were then performed at elevated temperatures to evaluate effective of heating process on the surface roughness. Orthogonal array Taguchi method was used to experimental design. The results showed that the surface quality of product was significantly improved under thermal - assisted milling. The surface roughness model during machining at room and elevated temperatures were evaluated and showed a good agreement with result of experiments.
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Improving the quality of surface molds after electrical discharge machining is still being considered by many researchers. Powder-mixed dielectric in electrical discharge machining showed that it is one of the processing methods with high... more
Improving the quality of surface molds after electrical discharge machining is still being considered by many researchers. Powder-mixed dielectric in electrical discharge machining showed that it is one of the processing methods with high efficiency. This article reports on the results of surface quality of mold steels after powder-mixed electrical discharge machining using titanium powder in fine machining. The process parameters such as electrode material, workpiece material, electrode polarity, pulse on-time, pulse off-time, current, and titanium powder concentration were considered in the research. These materials are most commonly used with die-sinking electrical discharge machining in the manufacture of molds and has been selected as the subject of research: workpiece materials were SKD61, SKT4, and SKD11 mold steels, and electrode materials were copper and graphite. Taguchi’s method is used to design experiments. The influence of the parameters on surface roughness was evalua...
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The electrical discharge machining process is hampered by a low material removal rate (MRR), high tool wear, and low quality of machined surface, which limit its applicability. The use of powder mixed electrical discharge machining helps... more
The electrical discharge machining process is hampered by a low material removal rate (MRR), high tool wear, and low quality of machined surface, which limit its applicability. The use of powder mixed electrical discharge machining helps overcome this drawback and increases the efficiency of the machining process. This study focused on the machining of SKD61, SKD11, and SKT4 die steels using titanium powder. Taguchi methods and analysis of variance were employed to identify the main parameters that affect the MRR. The other process parameters considered were the electrode material, workpiece material, electrode polarity, pulse-on time, pulse-off time, electric current, and titanium powder concentration. The results indicated that electric current, electrode material, and powder concentration were the most significant parameters that influenced the MRR. A powder concentration of 20 g/l increased the MRR by 42.1 %, as compared with no-powder machining. Further, the optimal value of the MRR was determined to be 45.734 mm3/min.
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Electrical discharge machining (EDM) has found a widespread application in both tool and mould and aerospace industries. Therefore, improving the quality of the EDM process has become a major research area. In this paper, the effect of... more
Electrical discharge machining (EDM) has found a widespread application in both tool and mould and aerospace industries. Therefore, improving the quality of the EDM process has become a major research area. In this paper, the effect of various titanium powder concentrations on the material removal rate (MRR), tool wear rate (TWR), and surface roughness (SR) using powdermixed electrical discharge machining (PMEDM) was carried out. The workpiece material used was SKD61 hot work steel and the electrode tool material was copper (Cu). The polarity of the electrodes and the concentrations of abrasive powder in the dielectric fluid were used as the input process parameters. Results showed that titanium powder suspended in the dielectric fluid of the EDM process enhanced the MRR without increasing the TWR. TWR and SR were improved in both cases of the polarity. The results showed an improvement in machining efficiency.
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In order to predict correctly stress-strain curve for tensile tests at elevated and cooling temperatures, a modification of a Johnson–Cook (J-C) model and a new method to determine (J-C) material parameters are proposed. A MATLAB tool is... more
In order to predict correctly stress-strain curve for tensile tests at elevated and cooling temperatures, a modification of a Johnson–Cook (J-C) model and a new method to determine (J-C) material parameters are proposed. A MATLAB tool is used to determine material parameters by fitting a curve to follow Ludwick and Voce's hardening law at various elevated temperatures. Those hardening law parameters are then utilized to determine modified (J-C) model material parameters. The modified (J-C) model shows the better prediction compared to the conventional one. An FEM tensile test simulation based on the isotropic hardening model for metal sheet at elevated temperatures was carried out via a user-material subroutine, using an explicit finite element code. The simulation results at elevated temperatures were firstly presented and then compared with the measurements. The temperature decrease of all elements due to the air cooling process was then calculated when considering the modifie...
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In this study, a modified Johnson‐Cook (J‐C) model and an innovated method to determine (J‐C) material parameters are proposed to predict more correctly stress‐strain curve for tensile tests in elevated temperatures. A MATLAB tool is used... more
In this study, a modified Johnson‐Cook (J‐C) model and an innovated method to determine (J‐C) material parameters are proposed to predict more correctly stress‐strain curve for tensile tests in elevated temperatures. A MATLAB tool is used to determine material ...