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In this paper, a micro-bump tool is designed to prepare micro-bumps on the rake face of different tools for cutting titanium alloys. The study found that the micro-bump tool can effectively reduce the tool surface temperature (up to 26.83%) and reduce tool wear (up to 25.2%) due to the presence of bumps that change the contact state between the chip and the tool surface. The only downside is that the cutting force during cutting is higher than with ordinary tools. Aiming at this downside, this paper studies the cutting states (20–600 °C) of three conventional tools and corresponding micro-bump tools at different heat-assisted temperatures by using heat-assisted machining technology. The study found that the application of heat-assisted machining technology can effectively reduce the cutting force of the micro-bump tool, while retaining the advantages of the micro-bump tool, which can reduce temperature and reduce wear at different hot working temperatures. [ABSTRACT FROM AUTHOR]

In recent years, Ti-6Al-4V titanium alloy has been widely used in many fields because of its excellent material properties. However, the complex properties of Ti-6Al-4V titanium alloy make the common material constitutive model no longer applicable. It is difficult to accurately analyze the deformation process of Ti-6Al-4V titanium alloy in theoretical analysis or numerical simulation. In this paper, we take Ti-6Al-4V titanium alloy as the research object, and the change of elastic modulus of Ti-6Al-4V titanium alloy was studied. A mathematical model of titanium alloy variable elastic modulus was established. Based on the YLD2000-2D yield criterion and the mathematical model of variable elastic modulus, the constitutive model of Ti-6Al-4V titanium alloy was established. We have carried out the numerical simulation and field experiment of V-bending springback of Ti-6Al-4V titanium alloy sheet. The springback prediction accuracy of three different constitutive models was compared and analyzed. The influence of yield criterion and elastic modulus on springback prediction of titanium alloy V-bending was studied. The results show that the constitutive model established in this paper significantly improved the springback prediction accuracy of the numerical simulation of titanium alloy sheet bending. This work has made a great contribution to the field of titanium alloy bending forming. [ABSTRACT FROM AUTHOR]

This paper presents a method for machining an annular groove on the inner wall of a steel tube by ball spinning. Based on spatial analytic geometry theory and assumptions about radial helical feed, the process utilizes a simplified expression of boundary curves of radial and tangential contact area between ball and workpiece. Through curve integration, the equations of radial and tangential contact areas for calculating ball-spinning force have been obtained. Based on results from calculation examples, this paper discusses the relationships between spinning depth, ball diameter, spinning feed, and ball-spinning force. The comparison of calculation results between the analytical model and the finite element method has been supplied, and the validity of the model has been certified. [ABSTRACT FROM AUTHOR]

Ball screw feed systems serve as the feed components of machine tools, and its dynamic characteristics directly affect the machining quality of workpieces and reliability of ball screws. In this paper, the lateral equivalent dynamic model of ball screw feed systems is established considering the bending vibration of the ball screw, nut location, and joints based on the Euler–Bernoulli beam theory. Subsequently, the dynamic parameters of joints are identified according to the measured dynamic stiffness using the particle swarm optimization (PSO) algorithm with the determined initial range of stiffness and damping. The robustness of the dynamic model is verified by experiments conducted at different nut locations. In addition, the nonlinear dynamic model is established and the effects of cutting force, bearing clearance, and nut motion on dynamic characteristics are investigated. The numerical results indicate that bearing clearance mainly affects the equilibrium position of worktable vibration, while the cutting force at different rotational and moving speeds of the nut mainly affects the vibration mode of the worktable, but the vibration mode is always a quasi-periodic motion. The established dynamic model and numerical analysis results provide a useful understanding of the dynamic characteristics of ball screw feed systems. [ABSTRACT FROM AUTHOR]

Nowadays, direct-current (dc) non-transferred arc plasma torch has drawn significant interest from both academia and industry due to the capability to process products in an efficient and convenient way. The core of this technology is to clarify and manipulate the arc behavior at the interior of the dc plasma torch to produce ideal plasma jets for processing. To solve this problem, a quasi-steady axisymmetric model is built to simulate and compare the arc characteristics in different operating conditions and different nozzle structures of the plasma torch. The results uncover distinct aspects of the study on arc characteristics, including the detection of the primary arc attachment region and its spatial features caused by the choking effect of torch structure. The thermal efficiency focused on processing substrate is also calculated in this paper for estimating the performance of plasma processing. The calculated results show that increasing the mass flow rate brings better thermal efficiency and the greatest promotion is at least 6% in the same current value, whereas improving the arc current value causes the opposite result. Meanwhile, two types of nozzle are compared to the original design in thermal efficiency, where the wide nozzle is chosen for torch optimization due to its best power efficiency. The secondary arc attachment on the metal substrate is discovered though its impact scope is only within a radius of 10 mm from the torch axis, its effect on the processing could be ignored for the extremely low electric current value. [ABSTRACT FROM AUTHOR]

Generally, the accuracy stability of a precision motorized spindle unit is influenced by its structural thermal balance behaviors (power matching degree of spindle structural heat generation–dissipations). For the accurate analysis of this spindle heat transfer behaviors based on temperature detections, this paper describes a method constructed with the numerical simulation technology and a proposed genetic algorithm-extreme learning machine (GA-ELM) algorithm. Firstly, the heat–fluid–solid coupling FE transient model is established to simulate spindle thermal behaviors, determinations of its thermal loads/boundary conditions are initially based on empirical calculations. Secondly, according to spindle temperature detections, these initial values are applied to thermal simulations and corrected by GA to make simulated spindle temperatures gradually approach detections. Specially, ELM is adopted to estimate the functional relationships from the parent population to the child population generated by genetic operators with increasing fitness values, and the trained ELM model is utilized to ensure the GA faster convergence. Eventually, based on the corrected thermal load/boundary condition values and simulation results, the time-varying power matching conditions of spindle structural heat generation–dissipation are analyzed. This study provides a theoretical basis for the optimization and promotion of spindle structural design and coolant control strategy. [ABSTRACT FROM AUTHOR]

As a new manufacturing method of minimal metal loss, coherent metal streamline, and higher load-bearing capacity for straight face gears, hot rolling forming can effectively improve the forming quality and the fatigue strength of face gear. In this paper, the key technologies involved in hot rolling process are studied, and hot rolling forming simulation of straight face gears is realized by using Deform-3D. Orthogonal simulation experiments are carried out by introducing three evaluation indexes, such as proportion coefficient of lug, metal streamline defect, and rolling force. Combining with the multi-objective process parameter optimization method of improved DEMATEL (decision making trial and evaluation laboratory) and improved TOPSIS (technique for order preference by similarity to an ideal solution), the optimal combination of technological parameters for hot rolling of straight face gear is accurately determined. Based on the optimal combination of parameters, the hot rolling manufacturing experiment of straight face gear is realized. The rationality of the optimal technological parameters and the feasibility of the rolling forming manufacturing technology are verified by simulation results and experiment results, and the theoretical basis and practical value for the precision manufacturing of rolled face gear are provided. [ABSTRACT FROM AUTHOR]

The stirring effect of a rotating laser on a molten pool can expand the range of the laser heat source and effectively inhibit defects such as pores and improve the quality of the weld joint. Due to laser rotation, the physical characteristics of the heat source and the dynamic behavior of the keyhole and molten pool are more complicated than those of conventional laser welding. This paper adopts a numerical simulation method. A three-dimensional model is developed, which takes into account the coupling of the keyhole, recoil pressure, and molten pool. The model can describe the dynamic behavior characteristics of keyholes and fluid flow and the formation process and mechanism of keyhole-induced pores in welds during rotating laser welding. It can be concluded that in conventional laser welding, the keyhole is deep, narrow, and unstable, which usually results in the formation of bubbles. If the bubbles in the molten pool fail to overflow in time, pores are formed. With an increase in laser rotation frequency, the keyhole becomes shallow and wide, and the dynamic behavior of the keyhole tends to be stable, which can effectively inhibit the formation of pores. When the rotating frequency is increased up to 150 Hz, the formation of pores can be completely suppressed. [ABSTRACT FROM AUTHOR]

The continuous and synchronous calibration process for straightness and roundness of LSAW (longitudinally submerged arc welding, LSAW) pipes with three rollers is a bidirectional reciprocating bending process. It includes both axial and circumferential directions. It is particularly important to reveal the deformation mechanism, which provides theoretical support for the calibration process to be applied to actual production. Based on this, through the combination of references, theoretical analysis and numerical simulation, the deformation mechanism is analyzed in this paper. The whole deformation process of pipe is modeled and then numerically simulated with FEM software of ABAQUS. The results show that reciprocating bending can eliminate the difference of initial curvature, so that the axial curvature and circumferential curvature are unified to the same direction and value, respectively. The calibration process of LSAW pipes is realized by the synergy between the axial reciprocating bending straightening process and the circumferential reciprocating bending rounding process. The simulation and experimental results support the theoretical results, and the deformation is mainly caused by axial stress and circumferential stress. [ABSTRACT FROM AUTHOR]

An appropriate machining sequence can benefit the deformation control of structural parts. However, the existing machining sequence optimization methods can only take single-sided parts into consideration, which is not sufficient to the deformation control of the double-sided parts. To this end, this paper proposes a double-sided collaborative optimization method of machining sequence for deformation control of structural parts. Off-line numerical analysis and on-line deformation monitoring are combined in the proposed method, i.e., the relative residual stiffness of the workpiece in different machining sequence is obtained by off-line numerical analysis, and the residual stress distribution is reflected by on-line deformation monitoring data, respectively. Then, a fuzzy comprehensive evaluation model aiming to decrease the overall deformation is established to realize the collaborative optimization of machining sequence. The machining efficiency is also considered in this model by optimizing the number of alternate flip-over, where the machining features of the part with two sides are machined alternatively according to the optimized sequence. The experiment shows that the proposed collaborative optimization method of machining sequence can decrease the machining deformation of double-sided parts effectively. [ABSTRACT FROM AUTHOR]

Motorized spindle is an inevitable choice of precision machine, but it has a prominent heat problem for its specific configuration of build-in motor. The paper proposed temperature distribution and thermal deformation modeling and a thermal-structural coupling simulation analysis method for a motorized spindle system from a vertical machining center. In order to establish an accurate finite element model, the boundary condition of joint thermal contact resistance (TCR) was taken into account. The paper detailed on how to obtain the TCR value which is related to the machine tool parameters by means of experimental and theoretical methods, and carried out a simulation experiment for the purpose of acquiring a quantitative analysis of the TCR influence on the temperature results. In order to verify the effectiveness of the TCR relevant methods, the experiment was carried out. The agreement between the experimental results and the simulation results showed that the proposed method can more accurately simulate the thermal characteristics of the motorized spindle. [ABSTRACT FROM AUTHOR]

Most of the current studies focus on the moving heat source model of straight wheel. However, these cannot be applied to calculate the cup wheel grinding temperature field, especially for the grinding processes performed with an adaptive end-effector. Based on the moving heat method and the principle of heat source superposition, the analytical thermal model of annular moving heat source for large surface workpiece is deduced. According to the parameters of the grinding instance, the numerical model is established by the finite element method for comparison and validating in this paper. The comparison results show that the characteristics of temperature distribution predicted by the analytical model and the numerical model agree very well. Two evident peak temperatures in grinding zone appear at both edges at the back of the grinding wheel in the feed direction, and test results with different grinding parameters show the relative errors do not exceed 19%. The feasibility of the analytical model and the numerical model based on different mathematical foundations is mutually validated. In the view of the non-uniform features of temperature distribution, especially the location of the peak temperature values, there are some reasonable explanations and analyses in this paper. [ABSTRACT FROM AUTHOR]

The strip shape inheritance model is widely applied to improve the strip shape quality in tandem cold rolling (TCR). However, the inheritance mechanism is still currently unclear. To bridge this gap, this paper presents a new numerical method for calculating the strip crown inheritance factor. In addition, the effects of the entry strip crown on exit strip crown and flatness were quantitatively analysed at each stand in the TCR using a novel three-dimensional (3D) multi-stand elastic–plastic finite element (FE) model. The results show that the strip crown inheritance factor increases slowly from S1 (stand 1) to S3 (stand 3), while rising sharply from S3 to S5 (stand 5), reaching a peak value of 0.495 μm/μm at S5. This trend coincides with that of strip plastic rigidity, which verifies that the strip crown inheritance factor is dependent on the strip plastic rigidity. Furthermore, the variation of strip crown and flatness under different entry strip crowns from S1 to S5 is jointly influenced by the pass reduction and strip plastic rigidity. Moreover, the strip crown inheritance factor increases with the deformation resistance of the strip at both S1 and S5. These findings not only offer a fresh perspective to understand the mechanism of strip crown inheritance, but also provide an important basis for optimising the strip shape control in the TCR process. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of the workpiece pose errors on gear skiving accuracy. First, based on the theory of homogeneous coordinate transformation, the mapping relationship between the tooth flank of the workpiece and the skiving tool is established according to the principle of gear skiving. Second, the workpiece pose errors are defined, and the relationship between each workpiece pose error and cutting depth is analyzed. According to the kinematic chain of the machine tool, a method for measuring the workpiece pose errors based on the actual inverse kinematic model is proposed. Third, the tooth deviations caused by individual workpiece pose errors and the coupling workpiece pose errors are studied. Then, the sensitive errors are obtained by numerical simulation. Finally, the numerical analysis is verified by gear skiving experiments, and the proposed method can be used to identify the possible workpiece pose errors. Furthermore, the particle swarm optimization algorithm is introduced to guide the workpiece setting pose errors in the gear skiving process. [ABSTRACT FROM AUTHOR]

This paper reports the numerical analysis results of ultrasonic elliptical vibration cutting (UEVC) combined with the electrical discharge assistance (EDA), called UEVC + EDA. UEVC delivers decreasing cutting forces, repressing side-burrs, and lowering tool wear. EDA is a cutting technique using a pulsed spark to remove material using thermal energy. Difficult-to-cut materials, such as Ti-6Al-4 V, can be cut effectively by combining these two techniques. A numerical study was performed using ABAQUS finite element analysis (FEA) software by investigating the von Mises stress, cutting forces, and temperature. Numerical analysis was carried out by modifying the ultrasonic vibration frequency, distance of the discharge pulse, discharge voltage, and discharge pulse radius. UEVC + EDA was compared numerically and experimentally with regular cutting (NC) and UEVC in terms of cutting force and tool temperature. The results showed that the UEVC + EDA method could improve the cutting condition by reducing the cutting force and von Mises stress and increasing the tool temperature. [ABSTRACT FROM AUTHOR]

In today's competitive environments, companies need to be cost-effective, environmental-friendly, and social-friendly to deal with several challenges that exist in markets. In this context, reconfigurable manufacturing systems (RMSs) have emerged to fulfil these requirements. RMS is one of the attractive manufacturing paradigms. Machine components, software, or material handling units can be added, removed, modified, or interchanged as needed and imposed by the necessity to react rapidly and cost-effectively to changing. A multi-objective multi-product process and production planning problem in a sustainable reconfigurable manufacturing environment (SRMS) is considered in this paper. Three pillars of sustainability, respectively social, environmental, and economic are formulated and optimised. First, a linear mixed-integer model is proposed. Second, a Lagrangian relaxation-based approach is developed to solve the problem on the large scales, where an exact method is used to solve the problem in small and medium cases with GAMS software. To illustrate the applicability of the proposed approaches, some numerical examples and analyses are presented. Finally, a sensibility study of the problem according to some parameters is performed. [ABSTRACT FROM AUTHOR]

The centrifugal disc finishing process is an abrasive technique of mass machining, and it is very effective but very frequently time consuming. In this paper, a simulation of the centrifugal disc finishing process was presented in order to estimate the kinetic energy distribution of the working medium and to find its regions that make the process more efficient. Numerical results were obtained using an explicit method in the Ansys/Ls-Dyna program. Due to the fact that the physical properties of numerous objects in free motion need to be calculated in a simulation process, the discrete element method (DEM) was used. Results from the numerical simulations indicate that the velocity and energy of particles is variable in an axial cross-section of working medium. The article presents particle velocity distributions in the working chamber for various rotational speeds of the rotor. The typical changes in velocity in the function of time are also discussed. Statistical important functions of the average kinetic energy of the working medium and accumulated energy by machining surface have been estimated in respect to the rotational speed and machining time with a high value of adjustment coefficients. This article constitutes the first stage of research, which is continued in order to experimentally verify the results in the real process, as presented in the companion paper (Part 2: Experimental analysis with the use of acoustic emission signal). [ABSTRACT FROM AUTHOR]

Metal spinning, as a kind of rotary forming process, is widely applied in the production of various areas. In this paper, the mathematical model of the conchoid roller path is proposed based on the cylindrical part and applied in the experiments. The possible problems of the roller path and the product shape are verified by 2D simulation, while the 3D simulation is used to predict the product dimensions and defects. Based on the advantage of both 2D and 3D simulation, the flow of target product trial production is proposed. The simulation is verified by the experiments with hard-deformed superalloy GH3030. The crack mechanism of cylindrical part spinning process is studied with a combination of macro- and micro-methods. Results show that the forming effect of the conchoid roller path is good; the flow can reduce the trial production cost and time. The grain elongated obviously at the crack zone while metal accumulated at the edge of the product which is the main cause of the crack. [ABSTRACT FROM AUTHOR]

This work is motivated by the fact that the microstructures of nickel-based alloy forged parts influenced by hot deformation have a great impact on the mechanical properties of their final parts. In this paper, a simplified 2D half-symmetry FE model embedded with the JMAK model is developed to predict the deformation characteristics and microstructure behaviors of an IN718 aeroengine drum in hot forging procedure and then verified by experiments. Moreover, based on two evaluation indexes, the distribution uniformities and general levels of effective strain, strain rate, temperature, dynamic recrystallization, and grain size within the forged IN718 alloy drum are analyzed quantitatively. The results suggest that unlike strain rate and grain size, the maximum values of effective strain, temperature, and dynamic recrystallization volume fraction are located at the internal wall of the forged drum, and their distribution uniformities become worse with the increment of forging strokes. Besides, the Xavg and davg show an opposite evolution trend as increasing forging strokes, which are mainly related to the increments of εavg and Tavg as well as the grain refinement of dynamic recrystallization. [ABSTRACT FROM AUTHOR]

Tool surface temperature distribution and tool wear are important parameters in the cutting process. It is important to reduce the wear degree of tool surface for tool life. In this paper, a semi-elliptical profiling tool is designed according to the shape of ellipse and compared with three other tools with different shapes, and the effects of different shape parameters on the temperature and wear of Ti-6Al-4V cutting process are discussed. The contact angle of chip and texture and the direction of chip flow are compared, and the following shape parameters are discussed: tip distance, texture size, and distance to each micro-texture. The effects of these parameters are evaluated in terms of temperature and wear. It is found that the semi-elliptical tool designed according to the shape of ellipse can effectively reduce the wear depth and the surface temperature of the tool, and it is more stable for the variation of different texture parameters. We found that the elliptical micro-textured/grooved cutting tool has good stability and can face a variety of working conditions. [ABSTRACT FROM AUTHOR]

Off-line programming systems are essential tools for the effective use of robots in the manufacturing environment. This paper presents a dedicated off-line programming system for robotic drilling in aerospace manufacturing. Following a brief introduction of the system architecture, the paper discusses two major problems of off-line programming for robotic drilling, i.e., redundancy resolution and position correction. A new performance index is proposed for the combined requirements of singularity and joint-limit avoidance, followed by a discussion of the redundancy resolution scheme by using numerical optimization at the joint displacement level. A position correction method using measurement data of reference holes is developed for the enhancement of robotic drilling accuracy. Robot programs generated by using the developed system have been tested on a robotic drilling system, and the experimental results are provided. [ABSTRACT FROM AUTHOR]

Medium-Mn steel is an outstanding representative of the newly developed third-generation advanced automotive steels. In our previous experimental studies, industrial trial production of 0.1C–5Mn medium-Mn steel has been realized, anti-decarburization ability of warm-formed medium-Mn steel has been assessed compared with the conventional hot-formed 22MnB5 steel, and heterogeneous spot-welding performance evaluation has also been completed on the industrial production line. Previous results proved that the medium-Mn steel have a development trend of replacing hot-formed boron steel in the automotive industry. Besides, numerical simulation analysis on the forming process of an actual automotive part is also an important topic of the applicability research of medium-Mn steel. Therefore, in this paper, a warm-formed medium-Mn steel B-pillar part was investigated by simulation in order to elucidate the effects of process parameters. Firstly, mechanical property tests were carried out to obtain the material parameters for establishing an accurate finite element model of the B-pillar part. After that, the warm-forming process was simulated and the effectiveness of the simulation was validated by benchmarking with the experimental result. Finally, the deep drawing zone with maximum fracture risk was focused to analyze the sensitivity of process parameters including initial blank temperature (IBT), blank holding force (BHF), and forming velocity (FV). Research results show that the IBT has the greatest influence on the thickness of the deep drawing zone. The recommended IBT is between 450 and 550 °C, which is favorable to obtain higher total elongation without loss of strength. This study is helpful to provide a theoretical basis for the large-scale application of warm-forming medium-Mn steel. [ABSTRACT FROM AUTHOR]

There are many process parameters for directed energy deposition (DED) that influence product quality. Using a well-defined analytical model to simulate the process increases the knowledge of the process. In this paper, a finite element analysis of hardness and temperature history for a thin-wall hemisphere dome is investigated using the SYSWELD software. The dome diameter and thickness are 45 mm and 2 mm respectively, and 144 beads of varying lengths is required to fabricate this part without support structures. A three-dimensional thermo-metallurgical-mechanical solution is used to generate the hardness. Two approaches for heat input are applied: constant laser efficiency and constant melt pool size. The results show a reasonable match between the experimental hardness data and the finite element analysis. The numerical results correlated better for the base segments than for those built at the top. Influence factors vary as the component is built, as conduction into the substrate occurs for the base partitions, but convection and radiation influence the heat losses at the top for thin-walled components. This illustrates the challenges with respect to developing accurate results. Faster numerical analysis techniques need to be developed to simulate products fabricated by DED additive manufacturing processes. [ABSTRACT FROM AUTHOR]

This paper proposes and evaluates a near admissible heuristic search strategy and its application to a kind of flexible manufacturing system (FMS) scheduling in a Petri net framework. Petri nets can concisely model the strict precedence constraint, multiple kinds of resources, and concurrent activities. To cope with the complexities for scheduling of FMS with alternative routings, this paper proposes an admissible heuristic function based on the execution of P-timed Petri nets and presents an improved dynamic weighting A* strategy using the proposed heuristic function. The search scheme does not need to predict the depth of solution in advance and the quality of the search result is also controllable. Some numerical experiments are carried out to demonstrate usefulness of the algorithm. [ABSTRACT FROM AUTHOR]

This paper discusses characteristics unique in the two-phase high-frequency-testing (HFT) environment in semiconductor manufacturing. We believe this paper is the first to define, formalize, and analyze the decision making problem associated with the two-phase HFT. Specifically, this paper defines the problem of minimizing the total HFT capacity usage by systematically finding the optimal number of preliminary HFT bin-1 chips subject to the main HFT, with the existence of the target service rate. We also propose a heuristic algorithm that exploits the special structure of the problem for efficiently obtaining a near-optimal solution. Finally, a numerical analysis and a case study have been conducted to gain more insights on the problem structure and the proposed algorithm. [ABSTRACT FROM AUTHOR]

This paper presents a simulated genetic algorithm (GA) model of scheduling the flow shop problem with re-entrant jobs. The objective of this research is to minimize the weighted tardiness and makespan. The proposed model considers that the jobs with non-identical due dates are processed on the machines in the same order. Furthermore, the re-entrant jobs are stochastic as only some jobs are required to reenter to the flow shop. The tardiness weight is adjusted once the jobs reenter to the shop. The performance of the proposed GA model is verified by a number of numerical experiments where the data come from the case company. The results show the proposed method has a higher order satisfaction rate than the current industrial practices. [ABSTRACT FROM AUTHOR]

In this paper, we attempt to introduce an algorithm which considers not only time factor but also cost, risk, and quality criteria to determine the critical path under fuzzy environment. In this algorithm first, decision makers allocate time, cost, risk, and quality to each activity. We are lacking in data and information, so in the proposed algorithm, the ratings of each activity and the weight of each criterion are described by fuzzy numbers and linguistic variables, which can be expressed in triangular fuzzy number. Linguistic variables are applied to represent the intensity of preferences of one criterion over another. Then, we add up triangular fuzzy numbers to determine the final evaluation value of each criterion for paths. Next, we use fuzzy TOPSIS, a technique for order preferences by similarity to an ideal solution, a method proposed by the authors in another paper, to choose the best alternative. Finally, numerical example is solved to illustrate the procedure of proposed method at the end of this paper. [ABSTRACT FROM AUTHOR]

Variable blank holder force (VBHF) that the blank holder force varies through the stroke is recognized as one of the advanced manufacturing technologies for sheet metal forming. On the other hand, slide velocity (SV) that controls the die velocity is rarely discussed in the literature. In particular, variable SV (VSV) that the SV varies through the forming process is an attractive forming technique for improving the product quality and the productivity. This paper proposes a practical approach of optimization of VBHF and VSV trajectory for sheet forming. First, based on the experimental result, the finite element analysis model is developed. Then, a multi-objective design optimization considering the product quality and the productivity is performed. A sequential approximate optimization that response surface is repeatedly constructed and optimized is adopted to identify the pareto-frontier. Three points on the pareto-frontier are selected, and the experiment using the servo press (H1F200-2, Komatsu Industries, Corp.) is conducted. Through the comparison of numerical and experimental results, the validity of the proposed approach is examined. [ABSTRACT FROM AUTHOR]

In order to optimize the positions of the locators in peripheral milling of a thin-walled workpiece, a finite element model along with an accurate cutting forces model is proposed in this paper. The finite element model takes into account the thickness variations of the workpiece in peripheral milling. The locators on the secondary locating surface directly influence the surface errors in peripheral milling of thin-walled workpiece, so this paper deals with the optimization of the positions of the locators on the secondary locating surface. A method including two steps is presented. In the first step, the initial positions of the locators are determined by adding the locators at the position with the maximum deformation. In the second step, a heuristic algorithm is proposed to optimize the positions of the locators. Finally, a simulation example is used to illustrate the method. [ABSTRACT FROM AUTHOR]

Based on the theories of digital conjugate surface and gear meshing, a generating method for digital gear tooth surfaces (DGTS) is demonstrated in this paper. The research focuses on the conjugate motion between the DGTS, represented by discrete points, and the cutter figuration determined by analytic function in the manufacture process. Conjugate points in the cutter section corresponding to the discrete points on the digital surface and conjugate movements are solved. Automated sequence arrangements of the generating movement parameters have been performed and the discrete generating movements are interpolated in a continuous conjugate motion along the order. Strategies of error analysis and error compensation are also discussed in this paper. Computer-simulated examples of the generating machining of involute DGTS and non-standard shaped DGTS, the parameters of machining motions and real tooth surfaces verify the developed method. The research develops a new idea for the machining of DGTS, which breaks the limitations of conventional approaches based on analytic surfaces. It is of important theoretical and practical value to manufacture digital surfaces. Our method is not only be applicable in generating machining of discrete DGTS and analytic gear tooth surfaces with complex geometric design, but also in contributing to the processing of discrete digital cam and other 3-D digital surfaces . [ABSTRACT FROM AUTHOR]

This paper presents the development of a FE-simulation model to predict the mechanical stresses and thermal loads that a cutting tool of polycrystalline cubic boron nitride (pcBN) is subjected to, when machining AISI 316L. The serrated chip formation of AISI 316L has a major impact on the periodic loads acting on the cutting tool. Therefore, it is vital to correctly model this serrated chip formation. One of the major difficulties with FE-simulations of metal cutting is that the extreme deformations in the workpiece material, often leads to a highly distorted mesh. This paper uses the Coupled Eulerian-Lagrangian (CEL) formulation in Abaqus/Explicit, where the workpiece is modelled with the Eulerian formulation and the cutting tool by the Lagrangian one. This CEL formulation enables to completely avoid mesh distortion. To capture the chip serration process, the workpiece material is described with the Johnson-Cook damage model. The FE-simulation results are validated via comparison of the modelled cutting forces, chip serration frequency, and contact length against experimental ones. [ABSTRACT FROM AUTHOR]

Hardening layer with a certain thickness can be formed on the workpiece surface after grind-hardening process. It can provide a better using performance for the workpiece. Therefore, the study on surface hardening layer and its distribution has important meaning to improve the using performance of the workpiece after dry grinding process. The paper analyzed the hardness, thickness, and its consistency of hardening layer through grind-hardening experiment using 40Cr and 45 steel. And then the paper studied the temperature field of surface hardening layer on the workpiece by FEM simulation. The cooling rate v could be calculated by using temperature-time curve. The distribution of hardness and thickness of surface hardening layer was also obtained. Combined with experiment results, the characteristic of the consistency of surface hardening layer was analyzed. The result showed that the hardness of the surface hardening layer would increase with the increasing of depth of cut a and feeding rate v . The thickness of the surface hardening layer also increases with the increasing of a , but it decreases with the increasing of v . The Cr element benefited the formation of martensite when the depth of the cut is small. But when the depth of the cut reaches to a certain value, the effect of Cr element could no longer be obvious. The results also showed that the consistency of intermediate area on the workpiece is much better than that of the cutting-in area and cutting-out area. Therefore, in order to obtain surface hardening layer with the suitable hardness and thickness, both technological parameters and materials should be chosen appropriately. [ABSTRACT FROM AUTHOR]

This paper aims to provide an investigation of the bulge deformation rules by using finite element analysis software, ABAQUS/Standard. A three-dimensional thermo-mechanical coupling model, considering the dynamic contact between the slab and rolls, has been established to study the temperature and bulge deformation distributions of the slab over the casting process. The simulated results of temperature profile were compared with the measured temperatures during the continuous casting process, the results of which showed a high agreement. Moreover, the bulge deformation rules of the slab were investigated systematically, especially at the thickness direction of the cross section which is the bulge deformation of the slab on the narrow side. A wave motion was found in the bulge deformation on the wide side of the slab cross section due to the joint effect of the ferrostatic pressure and the roller supporting force. The bulge deformation on the narrow side without the constraint from the roller support was cumulative, which was greater than the recovery count and compensated the bulge deformation on the wide side. In addition, the influences of various casting process parameters on bulge deformation were studied systematically in this paper. The results showed that bulge deformation on the narrow side and the wide side both increased with an increase in casting speeds and roll pitch. The method of fixed-gap and variable-diameter was suggested to be applied in the manufacture process in order to reduce the bulge deformation. [ABSTRACT FROM AUTHOR]

The non-uniform temperature and crystallinity distributions present in carbon fiber–reinforced PA12 composite pipes, produced via laser-assisted tape winding (LATW), are investigated in this paper. The width of the laser source is usually larger than the substrate width which causes multiple heating and cooling of some regions of the (neighboring) substrate and hence temperature and crystallinity gradients during the adjacent hoop winding. A kinematic-optical-thermal (KOT) model coupled with a non-isothermal crystallinity model is developed to capture the transient temperature and crystallinity distributions for growing substrate thickness and width. The predicted temperature trends are validated with thermocouple and thermal camera measurements. The substrate temperature varies in the width direction up to 52%. This will lead to extra polymer remelting and possible degradation. The maximum variation of the crystallinity degree across the width is found to be 270% which shows agreement with the trend of the measured crystallinity degree. It is found that a more realistic description of the melting behavior of the matrix is needed to obtain a more accurate prediction of the crystallinity distribution. [ABSTRACT FROM AUTHOR]

This paper is concerned with explaining real options values (ROV) using an opportunity cost concept. Through exploring the opportunity costs embedded in the ROV, we hope that the following presentation will be helpful for engineers to understand the meaning of the terminologies relevant to the ROV. With this belief, we performed the work under which the real investment project was delayed by 1 year only. The three different opportunity costs were explored in this work for the purpose of the paper as follows: an interest earning opportunity, an opportunity loss, and an expected opportunity gain. A short numerical example was demonstrated to show that the real options value derived with the three opportunity costs was equivalent to the value done with the binomial lattice model proposed by Cox, Ross, and Rubinstein. [ABSTRACT FROM AUTHOR]

The intensive competition has forced the manufacturing industry to improve product quality and production efficiency, and meanwhile reduce production cost. Detecting potential manufacturability problems in early design stages would prevent unnecessary cost involved in re-work and/or re-design activities at later manufacturing stages. This paper presents an algorithm for determining re-design areas to feedback the designer when the design model involves machining holes and pockets using a three-axis computer numerical control machine. The algorithm takes into account the various sizes of tools and tool holders, and therefore allows a designer to test the manufacturability of their available cutters on their design models. A color-based obstacle-detecting method, based on layer-slicing of re-design areas, helps a designer to re-evaluate a design model for increasing manufacturability. Practical examples are provided as the output of the process. [ABSTRACT FROM AUTHOR]

The measure of bullwhip effect (BWE) has always been a challenging task to the researchers. BWE is one of the main performance measures for a supply chain. In the existing literature, the measurement of BWE has been performed based on the simple demand processes such as Moving Average, AR(1) (AutoRegression), AR(2), Exponential Smoothing and ARMA(1,1) (AutoRegressive Moving Average). In this paper, we have derived generalized expressions of BWE based on the generalized ARMA (p,q) demand process under the various replenishment policies. The expressions have been compared both algebraically and numerically in order to find out the appropriate replenishment policy that leads to minimum valued expression for BWE. [ABSTRACT FROM AUTHOR]

A number of factors, including environmental legislations and increasing global uncertainties, have led many companies to consider engaging in remanufacturing. In this paper, we mainly address a topical issue of choosing the appropriate reverse channel format for collecting used products from customers. We suppose a manufacturer who has three reverse hybrid collection channel structures to choose: (1) manufacturer and retailer collecting used products at the same time, (2) manufacturer contracting the collection of used products to a retailer and a third party, and (3) manufacturer and third party collecting used products at the same time. To generate managerial insights into this important issue, we develop a structural model to explore the appropriate reverse channel structure for the manufacturer. Numerical examples are presented to demonstrate the applicability of the presented model. The results show that, ceteris paribus, the manufacturer and the retailer hybrid collection channel is the most effective reverse channel structure for the manufacturer. We also find that, under the same conditions, the manufacturer and the retailer hybrid collection approach is obviously superior to the single channel collection approach. Finally, we explore the channel coordination mechanism to implement channel cooperation for the manufacturer and the retailer. Our results indicate that the strategic alliance between the manufacturer and the retailer can effectively achieve the desired channel coordination. Furthermore, the Nash bargaining model is utilized to implement profit sharing for the manufacturer and the retailer in the channel coordination of strategic alliance. [ABSTRACT FROM AUTHOR]

Smirlis et al. (Appl Math Comput 177(1):1-10, ) have proposed a pair of interval data envelopment analysis (DEA) models for computation of the efficiency of decision-making units (DMUs) in the presence of missing data. In this paper, we show that the interval DEA models presented by Smirlis et al. have some drawbacks due to the use of variable production frontier for computation of the efficiency intervals of DMUs. To overcome these drawbacks, this paper presents new interval DEA models based on interval arithmetic. It is shown that the proposed interval DEA models do not need extra variable changes and use a fixed, unified production frontier for computation of the efficiency intervals of the DMUs with interval input and output data. A numerical example is presented to illustrate the potential applications of the new interval DEA models and their effectiveness for measuring the interval efficiencies of the DMUs. [ABSTRACT FROM AUTHOR]

To achieve a better performance, a novel cutting tool has been developed with micro-grooves on its rake face. Such tools have great potential in manufacturing. However, micro-grooves of improper directions and shapes may adversely affect cutting tools. This paper investigates the performance of newly designed cemented carbide (WC/Co) cutting tools with micro-grooves on the rake face in the machining of titanium alloy Ti-6A1-4V using finite element (FEM) simulation. The objectives are to explore the influence of the directions and geometrical shapes of micro-grooves on the performance of cutting tools in dry turning of the titanium alloy and to compare it with conventional cutting tools. Specifically, the following aspects are compared: cutting temperature, cutting force, chip morphology, and stress distribution. It is found that these micro-grooved cutting tools generate lower cutting force and cutting temperature and increase chip curling. The maximum reduction of cutting force and cutting temperature occurs under different machining parameters. Compared with linear micro-grooves, the curvilinear micro-grooves diffuse the tool stress and weaken the stress concentration on cutting edges. In addition, the secondary cutting phenomenon of micro-grooved tools is analyzed, which can be effectively alleviated by reducing the width of micro-grooves and setting a reasonable radius of the secondary cutting edge. [ABSTRACT FROM AUTHOR]

Mould prediction represents a crucial aspect of the production chain of several manufacturing industries. In particular, if the ceramic industry is considered, during the production process the highly non-linear mechanical behavior of the material leads to final products that can differ from the forming mould up to 20 % of its characteristic length. Considering that production tolerances can be considered acceptable if they do not exceed 0.5 % of the same length, the mould prediction becomes a very challenging inverse engineering problem. In this paper, a numerical strategy, able to predict the mould shape starting from the desired design shape, is presented. The activity has been developed in collaboration with SACMI, a world leading company in the production of machineries and moulds for the ceramic industry. [ABSTRACT FROM AUTHOR]

Chatter prediction is crucial in high-speed milling, since at high speed, a significant increase of productivity can be achieved by selecting optimal set of chatter-free cutting parameters. However, chatter predictive models show reduced accuracy at high speed due to machine dynamics, acquired in stationary condition (i.e., without spindle rotating), but changing with spindle speed. This paper proposes a hybrid experimental-analytical approach to identify tool-tip frequency response functions during cutting operations, with the aim of improving chatter prediction at high speed. The method is composed of an efficient test and an analytical identification technique based on the inversion of chatter predictive model. The proposed technique requires few cutting tests and a microphone to calculate speed-dependent chatter stability in a wide range of spindle speed, without the need of stationary frequency response function (FRF) identification. Numerical and experimental validations are presented to show the method implementation and assess its accuracy. As proven in the paper, computed speed-dependent tool-tip FRF in a specific configuration (i.e., slotting) can be used to predict chatter occurrence in any other conditions with the same tool. [ABSTRACT FROM AUTHOR]

A rational determination of machining parameters of electrical discharge machining (EDM) is of vital importance to the machining quality. This paper proposes an ANSYS emulation, experimental correction, and numerical fitting method (AEN-XRD method) to determine the relationship between machining parameters and machining indicators of various kinds of machine tools. Firstly, it adopts ANSYS software to make simulation researches of the pit size with different electrical parameters. Theoretical calculation of corresponding machining indicators is presented. Based on the machine data, adjustment is made on the simulation outcome. And thereby, based on the adjusted outcome, numerical fitting method is adopted to determine the functional relation formula of machining parameters and machining indicators. Experiments of different machine tools have shown that there is a relatively high prediction accuracy of machining parameters and they are capable to meet the actual machining demand, which further proves the AEN-XRD method is of great practicability. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for the transformation of a product concept into a detailed design and manufacturing process chain for hybrid manufacturing platforms. Hybrid platforms offer new capabilities and opportunities for product design. However, they require high levels of process expertise for effective design and effective process selection. Design for hybrid manufacture is challenging as there is a requirement to understand a number of technologies, which may be highly varied. To address this challenge, a knowledge-based decision support system developed in this paper enables manufacturing expertise to be integrated into procedures for product design and process chain selection. This formalised numerical methodology is able to consider a wider range of varied manufacturing processes than any previous study. A feature-based design method is developed, which guides the designer towards an optimised product design during the embodiment design phase, and a process chain selection program is utilised to enable the effective analysis of a product design based on product evaluation criteria. The methodology has been successfully applied to the design of an LED product with internal geometries and electronics. [ABSTRACT FROM AUTHOR]

In this paper, we present a new reliability model and a unique condition-based maintenance model for complex systems with dependent components subject to respective degradation processes, and the dependence among components is established through environmental factors. Common environmental factors, such as temperature, can create the dependence in failure times of different degrading components in a complex system. The system under study consists of one dominant/independent component and n statistically dependent components that are all subject to degradation. We consider two aspects that link the degradation processes and environmental factors: the degradation of dominant/independent component is not affected by the state of other components, but may influence environmental factors, such as temperature; and the n dependent components degrade over time and their degradation rates are impacted by the environmental factors. Based on the thermodynamic study of the relationship between degradation and environmental temperature, we develop a reliability model to mathematically account for the dependence in multiple components for such a system. Considering the unique dependent relationship among components, a novel condition-based maintenance model is developed to minimize the long run expected cost rate. A numerical example is studied to demonstrate our models, and sensitivity analysis is conducted to test the impact of parameters on the models. [ABSTRACT FROM AUTHOR]

In this paper, an economic order quantity model for deteriorating items with time discounting has been developed for varying demand pattern over a fixed planning horizon. Optimal solutions with complete backlogging and without backlogging are established and has proven that the total variable cost is convex. The main contribution of this paper is based on the assumption of the demand which is the linear function of the instantaneous stock level I(t). In this paper, a new type of demand has been considered which will help us to obtain qualitative insights without much analytical complexity. Optimal solutions of the proposed models are derived and effects of deterioration on the inventory replenishment policies are studied with the help of numerical examples. [ABSTRACT FROM AUTHOR]

In this paper, a deteriorating production system subject to random machine breakdowns, repair and replacement activities, is investigated. The machine manufactures one type of product, and when a breakdown occurs, either a repair or a replacement action is chosen. The machine is replaced with a new one if the replacement option is selected, and no repair action is considered in such a situation. The decision variables of the control problem are the production rate and the repair/replacement switching policy upon machine failure. The objective of the study is to find the decision variables that minimize the overall cost, including repair, replacement, inventory holding, and backlog costs, over an infinite planning horizon. This paper differs from similar research projects in that it considers the fact that machine repair activities depend on the repair history, and a semi-Markov decision process is used to describe the dynamics of the system. The proposed optimality conditions are developed using the stochastic dynamic programming approach, with a numerical example given to illustrate the utility of the proposed approach, and a sensitivity analysis considered to confirm the structure of the control policy obtained. [ABSTRACT FROM AUTHOR]

In ultra-precision machining, the heating effect on a workpiece induced by cutting process itself plays an important role in the machining process as it affects tool life, machining accuracy, and the surface quality of the workpiece. This paper discusses the cutting-induced heating effect in ultra-precision raster milling based on the study of the time-temperature-dependent precipitation of 6061 aluminum alloy. Experiments are designed to estimate the temperature variation of the workpiece in ultra-precision machining by comparing the change in the size of precipitates in isothermal heat treatment with those in raster milling process under different depth of cut. Microscopical examination under a scanning electron microscope (SEM) revealed that the temperature on the raster-milled surface is much higher than 500°C. In the last part of this paper, the heat generation of the workpiece in the process of ultra-precision raster milling is simulated by finite element method, the result of which is found to be consistent with that from SEM. [ABSTRACT FROM AUTHOR]

This paper focuses on the facility location problem with two conflicting objectives. We observe that minimization of the total cost of a particular echelon may lead to the increase in the total cost of a supply chain as a whole. Thus, these conflicting objectives are required to be met together from a supply chain perspective. We have solved the problem formulated in mixed nonlinear programming by a multi-objective evolutionary algorithm (MOEA) known as non-dominated sorting algorithm, or NSGA II in short. Numerical example is provided to show the effect of the algorithm on the solution. [ABSTRACT FROM AUTHOR]

In traditional models of data envelopment analysis it is assumed that decision making units do not have dual-role factors. This paper proposes a model for selecting third-party reverse logistics (3PL) provider in the presence of multiple dual-role factors. A numerical example demonstrates the application of the proposed method. [ABSTRACT FROM AUTHOR]