Search

With the rapid development of precision micro-manufacturing technology, the connection and assembly processes of precision micro-devices have placed higher demands on the volume and precision of micro-dispensing technology. In the dispensing process, the adhesive dispensing volume is crucial to the bonding quality. In this paper, based on the analysis of the composition of critical contact force and the mechanism of action, a method was proposed to control the ultra-micro-adhesive dispensing volume at pL level. Firstly, a mathematical model describing the change of droplet size and critical contact force during the extrusion of adhesive was established, which provided a theoretical basis for analyzing the mapping relationship between contact force and adhesive dispensing volume. Then, the mathematical models describing the droplet initial volume, dispensing volume, and transfer ratio were derived. Based on this, a mechanism and method to control the volume of dispensing to the substrate by contact force control to trigger the liquid bridge pull-off action was developed. The critical contact force was detected in real time to determine the changing state of the process of adhesive contacting the substrate, and used as the basis for triggering the stretching stage of the liquid bridge, and then achieved the prediction and control of the adhesive dispensing volume. In this paper, a series of experimental studies were conducted on the method of controlling the adhesive dispensing volume through contact force by embedding a micro-force sensor with high resolution into the dispensing system. The experiments were conducted with the critical contact force in the range of 0.5–4.5 mN. The results showed that the increase of the critical contact force was approximately linear with the increase of the adhesive dispensing volume. The deviation rate of the dispensing volume under the same critical contact force was less than 1.7%, and the average deviation rate of the overall adhesive dispensing volume was about 0.6%, so it was basically possible to precisely control the adhesive dispensing volume at the pL level by changing the contact force. This study revealed the composition and variation mechanism of contact force, and the proposed method for controlling the adhesive dispensing volume have significant value and potential in the micro-assembly of viscous ultra-microfluids and other applications. [ABSTRACT FROM AUTHOR]

Nowadays, with the increasing demands for quality and precision in microelectronic packaging, the study and prediction of droplet parameters before packaging have become increasingly important. This paper aims to derive a predictive formula for droplet volume dispensing to improve packaging quality, optimize process parameters, reduce resource waste, enhance process control, and enhance product quality and reliability. Based on the needle transfer method for ultra-microdroplet dispensing, a droplet dispensing device that meets packaging requirements is established, and precise control of droplet volume is achieved by changing the factors that affect droplet formation. The droplets obtained from experiments are analyzed using pixel extraction, and a numerical fitting method is employed to establish a droplet volume model. It is found that the pixel method is a practical approach for determining droplet volume, with an average deviation of approximately 1.85%. By conducting droplet dispensing experiments with varying initial distances, the smallest droplet volume achieved is 24.33 pL, and it is concluded that larger initial distances result in smaller droplet volumes and reduced droplet contact area. Based on the droplet dispensing experimental data obtained by varying the initial distance, mathematical predictive models for droplet volume and droplet contact area are derived. The results show that the average difference rate between predicted and actual volumes is 0.51%, and the average difference rate between predicted and actual contact areas is 0.56%. [ABSTRACT FROM AUTHOR]

The die undergoing severe loads induces inevitable wear in the pressure forming process, and the wear of die arouses obsessions about the die's service lifetime. In order to predict the wear and lifetime for a pair of rollers in net-shape blade rolling process, this paper quantified the distributions and evolutions of the local wear over roller cavities based on the local contact load responses and predicted the lifetime which related to wear by a mathematical model. Firstly, the net-shape blade rolling process and the local contact load responses were summarized. Then, an improved wear model was provided based on the Archard formula, and the impact factors of the model were standardized by a regression analysis experiment. The transient wear distributions and evolutions over the roller cavities were enumerated, and the wear distribution for one rolling cycle was calculated based on wear accumulation effect. Finally, a lifetime prediction model was proposed to predict the service lifetime of the rollers according to the wear accumulation effect, and an experimental verification was carried out to validate the model. The results show that the wear model and lifetime prediction model can be used for investigating the wear and lifetime of the roller cavities for the net-shape blade rolling process. [ABSTRACT FROM AUTHOR]

Free-form milling is a flexible gear machining method that allows the use of general disc cutters to machine various gear types on a 5-axis machine tool. This paper proposes a two-dimensional simulation method for free-form milling of cylindrical gears with disc cutters. A mathematical model for free-form milling of cylindrical gears with disc cutters is constructed. By analyzing the spatial positional relationships between the cutter and the workpiece, the instantaneous contact line is derived and projected onto the gear end face; then, the intersection of the projected curves is used to obtain the final profile. This calculation method enables rapid simulation of the actual cutting conditions on the gear end face, which helps determine the machining interference and analyze the tooth profile accuracy during the gear machining process. The method proposed in this paper can also be used to analyze the sensitivity of geometric position errors of the machine tool axes. [ABSTRACT FROM AUTHOR]

Kitting – meaning to supply assembly with components in presorted kits – is widely seen as beneficial for assembly quality and efficiency when there is a multitude of component variants. However, the process by which kits are prepared – the kit preparation – is labour-intensive, and kit errors are problematic at assembly processes. The use of robotics to support kit preparation has received some attention by researchers, but literature is lacking with respect to how collaborative robots – cobots – can support kit preparation activities. The purpose of this paper is to identify the potential of a cobot to support time-efficient batch preparation of kits. To address the purpose, the paper presents a mathematical model for estimation of the cycle time associated with cobot-supported kit preparation. The model is applied in a numerical example with experimental data from laboratory experiments, and cobot-supported kit preparation is compared with manual kit preparation. The findings suggest that cobot-supported kit preparation is beneficial with diverse kits and smaller components quantities per SKU (Stock Keeping Unit) and provides less variability of the outcome, when compared to manual kit preparation. The paper reveals several insights about cobot-supported kit preparation that can be valuable for both academics and practitioners. The model developed can be used by practitioners to assess the potential of cobots to support kit-batch preparation in association with assembly, spare parts, repair and maintenance, or business to business industry. [ABSTRACT FROM AUTHOR]

Due to the complicated deformation of the billet in roll forming process and the lack of the theoretical understanding, there are still no unified methods to design and optimize roll profiles. Theoretical analysis of the deformation in roll forming process based on mathematical method is efficient and necessary. A qualified roll profile optimization method should be based on the accurate calculation of the spatial configuration of the billet. However, the existing models for calculating the spatial configuration of the billet in roll forming process cannot calculate the springback of the billet. In this paper, according to the mathematical model established by the author for calculating the spatial configuration of the billet, a roll profile optimization method for high-strength V channel roll forming process was proposed by taking the maximum edge membrane longitudinal strain as constraint conditions. After optimization, the number of roll stands required for final V channels was reduced from 8 to 5. Through analyzing and comparing the deformation of the billet in simulation results of bending and roll forming process, it is found that bending tests can also be used to verify the feasibility of the roll profile optimization method proposed in this paper. The bending tests were carried out using the original and optimized process parameters, respectively. The results show that the shape of the V channel obtained by the optimized process parameters is much closer to that of the designed V channel. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of ranking woven fabric defects (WFDs) observed in textile manufacturing using a data envelopment analysis (DEA) method. The paper shows that the optimal solutions of DEA models for decision-making units (DMUs) with multiple inputs can be found without the need of solving the corresponding models. The paper performs a mean-variance analysis for determining the most important statistical factors of WFDs in terms of multiple inputs. The paper also ranks the observed WFDs from the worst preferred using the suggested DEA formulation. The contribution of this study can be explained as follows. It introduces a new application for DEA method in textile manufacturing for ranking fabric defects. This is significant in defining rich project in reducing defects through prioritizing of quality specification of fabric defects by Six Sigma experts. Also, the result of this paper can be obtained using an efficient DEA method without the need of solving the corresponding DEA models for any sample size of fabric defects. [ABSTRACT FROM AUTHOR]

Due to gravity, a change in the welding position will significantly affect the flow of the molten pool, thus affecting the weld bead shape. An all-position welding process of low-power pulsed laser-MAG (metal active gas) hybrid welding was proposed to improve the welding efficiency and quality of all-position welding. This paper used the response surface method (RSM) to develop the weld bead geometry mathematical model. The analysis of variance confirmed the significance and accuracy of the model. The results show that the models can accurately predict the weld geometry, percentage errors for any models are less than 8.1%. Then, the effects of welding parameters and welding position on weld width, weld reinforcement, and weld penetration were analyzed. Finally, the optimal welding parameters at five positions of 0°, 45°, 90°, 135°, and 180° were obtained by numerical optimization with RSM. The study results can provide a reference for applying laser-MAG hybrid welding in all-position welding. [ABSTRACT FROM AUTHOR]

Electromagnetic clinching (EMC) is a high-speed connection technology that combines electromagnetic forming and mechanical clinching. The die structure significantly affects the mechanical properties of the joint. In this paper, an optimal method based on response surface methodology (RSM) and particle swarm optimization algorithm (PSO) is proposed to improve the mechanical properties of joints clinched by EMC. The mathematical models of die geometrical parameters and cross-sectional parameters of the joint are obtained by RSM and numerical simulation. Then, the die structure is optimized through PSO. Finally, the experiments are carried out using the optimized and standardized die. The results show small errors between the simulation and the experiment. The joint strength using a standardized die is 878 N, and energy absorption is 0.758 J. The joint strength using the optimized die is 1322 N, and energy absorption is 1.335 J. Compared with the standardized die, the joint strength and energy absorption of parts obtained by the optimized die are increased by 50.5% and 76.1%, respectively. [ABSTRACT FROM AUTHOR]

The whirl-machining process is a precise, efficient, and promising machine process for manufacturing workpieces over the milling process. At the same time, the roller-gear cam has advantages over the other cam-follower system. However, the whirl-machining process has not been applied to manufacture the roller-gear cam. Therefore, this paper proposes a novel method for roller-gear cam manufacturing using a whirl-machining process. Mathematical modeling is described for generating the roller-gear cam, roller, and whirl-milling tool surface. A novel CNC machine and its coordinate system are proposed. Cutting simulations for obtaining the surface topologies and normal deviations are conducted. Globoidal cam with different cylindrical rollers, globoidal cam with a conical roller, and cylindrical cam with a conical roller are taken as case studies, and results are discussed. A virtual cutting simulation was conducted using VERICUT. Some machining examples are shown to verify the benefits of the proposed method in roller-gear cam manufacturing. [ABSTRACT FROM AUTHOR]

The sculptured surface has been widely used in aerospace and machinery manufacturing industries. CNC machining of sculptured surfaces is an important research area, and computation efficiency improvements are considered critical topics in this field. This paper presents a highly efficient method to generate smooth tool paths by establishing a mathematical model to describe the relationship between the relative curvature of sculptured surface and the machining strip width in five-axis machining. The method is improved from the middle-point error control method (MPECM) and the feasible tool position surface method (FTPSM), by changing the objective from the complete optimization for each drive point to the drive points' interpolation. The drive point with the narrowest machining strip width and some sample points is selected to interpolate the remaining points. Both theoretical analysis and test examples show the correctness of the proposed method. Under the same condition, compared with the MPECM and the FTPSM, the computing time of the new method decreases to 10% at least. Besides, the fluctuation of the tool path is reduced. The machining examples verified the superiority of the proposed method. [ABSTRACT FROM AUTHOR]

Ultrasonic power plays an important role in ultrasonic surface rolling, and the maximum contact stress and springback generated by ultrasonic power during ultrasonic rolling also affect the surface quality of mechanical materials. In order to study the effect of different ultrasonic powers on the maximum contact stress and springback during the ultrasonic rolling process, in this paper, based on the elastic–plastic theory, a mathematical model for predicting the maximum contact stress and springback is proposed. In order to verify the mathematical model, the ultrasonic surface rolling experiment was carried out with 20 steel as the experimental sample. Through the analytical derivation of the mathematical model, and study other characteristic parameters of the model, such as rolling depth, Mises. And the ultrasonic surface rolling process is simulated numerically by ABAQUS. The results show that the mathematical model can effectively predict the maximum contact stress, rolling depth, Mises, and springback, and the average deviation is 10%. With the increase of ultrasonic power, Mises, pressure, and springback gradually decrease, and the rolling depth increases. [ABSTRACT FROM AUTHOR]

This paper proposes a topology modification method of generating gear grinding based on multi-axis linkage parameter optimization. In order to improve the accuracy of tooth flank modification in generating gear grinding and to reduce the transmission error of modified gear pair, a multi-objective optimization genetic algorithm is adopted to adjust machine movement. Firstly, according to the position and motion relationship among diamond wheel, worm wheel, and workpiece gear, the mathematical models of worm wheel dressing and generating gear grinding are established. The linkage relationships between motion axes are redefined to achieve topology modification. The radial feed F X 1 , tangential feed F Y 1 of worm wheel, and gear rotational angle φ g are defined as the fourth-order polynomial function of axial feed F Z 1 . Secondly, the transmission error model of modified gear is developed. And the polynomial coefficients of each axis are optimized with the objective of minimizing total tooth flank deviation and transmission error. Finally, the effectiveness of this method is verified by three numerical examples with different parameter groups. In addition, the diamond wheel and worm wheel used in the study are standard profile, which saves the cost of gear machining and improves the efficiency of production cycle. The research results could provide a theoretical reference for the improvement of generating gear grinding process. [ABSTRACT FROM AUTHOR]

Product design and development (PDD) involves various types of tradeoffs, for which multi-objective optimization has been a prevailing approach. Complex PDD optimization problems are associated with multidisciplinary decision makers and may encompass different levels of the design decision hierarchy. A practical concern is that many conflicting goals with diverse decision variables have to compete to arrive at equilibrium solutions, entailing a paradigm of leader-follower joint optimization (LFJO). In line with a typical decision chain of engineering optimization, comprising such consecutive stages as problem formation, optimization modeling, model solution, and optimization evaluation, this paper provides a state-of-the-art review of the LFJO problems that are widely observed in the PDD literature, along with a survey of LFJO mathematical modeling methods. Also reviewed is the status quo of bilevel programming (BLP) models for LFJO problems with focus on their engineering implications for PDD. The paper also reviews the prevailing algorithms for solving BLP mathematical models, as well as common practice of LFJO model evaluation in the PDD literature. Finally, the critical issues of LFJO problems and outlook for further research are discussed. [ABSTRACT FROM AUTHOR]

Currently, the quality check of bike frame still heavily relies on human operation. In practice, an entire checking process usually takes more than 30 min to complete. To overcome this dilemma, this paper aims to develop a fast high-precision measurement system using robotic arm based on 3D geometry mathematical model. Instead of four points needed to find coefficients of a space sphere, only three investigation points are required to achieve the sphere axis coordinates for measurement. The personal computer (PC) works as a control core, which to perform the mathematical model and control robotic arm movement. The robotic arm combined with contact sensor (probe) is used to move to the desired inspection points in shaft length, internal diameter, verticality, and parallelism following up the designated path planning route. The experimental results confirm that the proposed system can accurately reach the measurement outcomes. The entire checking cycle can be completed in 3 min at the range of 0.15 mm error, effectively reducing the process time with a high precision. [ABSTRACT FROM AUTHOR]

Under the load conditions of clamping force and riveting force, the part deformation problems are induced in the assembly process. For the component deformation problems of the thin-wall part assembly, in this paper, from the viewpoint of micro-aspect, the fractal theory model is proposed to analyze the relationship between the part deformation, loads, and contact area for rivet-joint parts; the micro-deformation values for different stages are solved and obtained through theoretical analysis. According to the self-similarity of fractal theory model, the change of the micro-convex body for contact surface will be researched to reflect the macro-deformation properties. Through the measuring experiment for thin-wall parts, the actual three-dimensional coordinate value of each measuring point is obtained before and after riveting assembly, and then, the wavelet neural network method (WNNM) is adopted to predict experiment deformation value based on the obtained deformation value after processing the coordinate value through fitting surface method. Hereby, according to the deformation value for every thin-wall part after processing experiment data, the fractal dimension value will be determined based on the fractal statistic method to analyze the deformation status of different stages. Through analysis and comparison, the results show that the variation regularity of deformation value based on two or three fractal deformation stages is well conformed to and similar to the experimental value and prediction value, which also verify the correctness and effectiveness of the theoretical model, and provide a theoretical basis for further research on thin-wall part assembly deformation from a micro-perspective and improving assembly accuracy quality in future. [ABSTRACT FROM AUTHOR]

This paper aims to study tasks' allocation problem in a single-station collaborative robot assembly system 4.0. Two products with identical demands are run in a system simultaneously in mixed mode to reduce the idle time and improve the system utilization. The idle time occurs due to balancing difficulties and particularly in this case restrictions in the task vs. robot-worker feasibility matrix. It is not allowed for the resources to assemble a same product simultaneously to avoid any direct contact between resources. Thus, the products are swapped between resources as needed to complete the assembly tasks. Two approaches, a novel mathematical model and the shortest processing time (SPT) rule, are propounded in this study to reduce the cycle and idle times and enhance the production rate of an assembly system. The two proposed methods rely on dividing the timeline of a station into unknown stages with unknown lengths. The performance of the proposed mathematical model and SPT rule are evaluated by two performance measures: the total number of stations and the % average station utilization. The obtained results are compared to the results of the modified COMSOAL heuristic. The findings revealed that the novel mathematical model dominated results. It guaranteed minimizing the cycle time and maximizing the production rate compared to the SPT rule and modified COMSOAL heuristic. However, many companies value a 1-s reduction in cycle time as valuable. This directly relates to the reduction of direct resources costs and the total number of stations. [ABSTRACT FROM AUTHOR]

Power skiving provides an effective solution and considerable machining efficiency for the machining of internal gears. The tool profile design and the reusability after resharpening is crucial in gear manufacturing. In this paper, a novel method of tool profile correction based on the inverse error-complement of involute profile is proposed. Firstly, the mathematical model of involute cutter with rake angle and relief angle is established. The profile error relative to the target gear is calculated by the mathematical model. Then, the distribution of the gear profile errors is fitted by a fifth-order multinomial. The fitted multinomial function is attached to the cutter profile. The maximum theoretical error of the target gear profile is in 10e-7 mm order of magnitude through the calculation of fewer iterations. Finally, the distribution of the multinomial coefficients along the resharpening direction is obtained by linear programming. The result shows that the cutter designed by the proposed method possess almost negligible error to the gear profile and good repeatability of resharpening. [ABSTRACT FROM AUTHOR]

Rotary-laser automatic theodolite (R-LAT) system is a distributed large-scale metrology system, which provides parallel measurement in scalable measurement room without obvious precision loss. Each of R-LAT emits two nonparallel laser planes to scan the measurement space via evenly rotations, while the photoelectric sensors receive these laser plane signals and perform the coordinate calculation based on triangulation. The accurate geometric parameters of the two laser planes play a crucial role in maintaining the measurement precision of R-LAT system. In practice, the geometry of the two laser planes, which is termed as intrinsic parameters, is usually unknown after assembled. Therefore, how to figure out the accurate intrinsic parameter of each R-LAT is a fundamental question for the application of R-LAT system. This paper proposed an easily operated intrinsic parameter calibration method for R-LAT system by adopting coordinate measurement machine. The mathematical model of laser planes and the observing equation group of R-LAT are established. Then, the intrinsic calibration is formulated as a nonlinear least-square problem that minimizes the sum of deviations of target points and laser planes, and the ascertainment of its initial guess is introduced. At last, experience is performed to verify the effectiveness of this method, and simulations are carried out to investigate the influence of the target point configuration in the accuracy of intrinsic parameters. [ABSTRACT FROM AUTHOR]

Some feasible mathematical model solution results in a recent paper (Fattahi et al., Int J Adv Manuf Technol, 53:363-378, 2011) are incorrect. In this note, we show by counterexamples that the results are incorrect and mathematical formulation is corrected by additional constraints. [ABSTRACT FROM AUTHOR]

This paper presents a review of the literature on generating cutting paths for laser cutting machines. Firstly, the cutting path problem is defined including all relevant technical side constraints which exist plentifully in laser cutting. Secondly, a former classification method is updated to include all types of cutting path problems. Thirdly, a comprehensive review of solution methods and related applications is presented. Throughout the literature review, trends in research in cutting path generation and interesting areas for future research are identified. [ABSTRACT FROM AUTHOR]

In this paper, a six-degree-of-freedom (6DOF) error measurement system based on geometric optics is proposed for linear stages. This measurement system uses an additional linear stage that drags the sensor onto the stage so that the light spot projected on the sensor moves back and forth with the moving stage. This method achieves long-range 6DOF measurement. Compared with commercial laser interferometers, the proposed measurement system has the advantages of a lower cost, a simpler structure, and the capability of measuring 6DOF errors simultaneously. Zemax software was used to simulate the relationships between the 6DOF errors and the values of position-sensitive detectors. MATLAB software was then used to construct the forward and inverse mathematical kinematic models of the optical paths and simplify the models through curve fitting. Finally, to address installation and manufacturing errors, a reverse kinematic mathematical solution was obtained through the use of a six-axis Stewart platform. The proposed measurement system was experimentally implemented on a commercial linear stage to measure the 6DOF errors and verified against results obtained with a commercial interferometer and electronic level. [ABSTRACT FROM AUTHOR]

Due to the increase in the difficulty and diversity of tasks performed by robots, robot "hand-eye" collaborative operation has attracted widespread attention. This technology is widely used in aerospace, medical, automotive, and industrial fields. Recently, hand-eye calibration technology is developing towards high precision and high intelligence. However, it has much work to be done in terms of identifying robot and camera parameters. This article introduces in detail the methods and theories involved in hand-eye calibration. According to the structure of the algorithm and the type of the optimization method, this paper summarizes the hand-eye calibration method into four steps: camera pose, mechanical claw pose, mathematical model, and error metrics. The well-known open problems about hand-eye calibration are finally stated, and some new research interests are also pointed out. The results of this review are useful for robot technicians to choose the correct parameter identification method and for researchers to determine further research areas. [ABSTRACT FROM AUTHOR]

In order to further improve the control accuracy of thickness, crown and tension in hot strip finishing mill, a multivariable optimizing strategy based on inverse linear quadratic (ILQ) control theory is proposed in this paper. First, the state space model of hot rolling process is established based on the basic dynamic mathematical model of rolling process and measured data collected from a certain plant. Then, the new ILQ control strategy is designed for the thickness, crown and tension control system in the complex rolling process, and the response performance and anti-interference performance of ILQ controller and PI controller were tested. The results show that the proposed ILQ control strategy has excellent control performance with the maximal overshoot 24.13% smaller than that of PI controller when strip crown, thickness and tension step signals are added simultaneously, and the ILQ control strategy has certain guiding significance for the actual production of hot rolling. [ABSTRACT FROM AUTHOR]

The paper presents results of CFD parametric study of centrifugal compressor stage vane diffusers in the Ansys CFX. The results obtained will be used to build a mathematical model of vane diffuser in optimization design system. Objects of research are vane diffusers with external relative diameter (relative to the diameter of the impeller) equal to 1.5; vane inlet angle of 20°; relative vane heights of 0.025, 0.034, 0.045, 0.06, and 0.08; and vane profile curvature angles of 10, 15, and 20 °. The characteristics of polytrophic efficiency, loss coefficient, recovery coefficient, ratio of inlet and outlet velocities, and flow deviation angle versus incidence angle are set. The analysis of the flow structure in the vane diffuser channels is presented. Unlike with a straight vane cascade, the deviation angle in the circular rows of vane diffusers tends to increase with increasing row density. This may be due to the complex nature of the interaction of the active part of the flow with separation zones. In rows with almost straight vanes at a lower density, the separation zone on the pressure side decreases and even shifts to the very end of the suction side. [ABSTRACT FROM AUTHOR]

Designing and planning a closed-loop supply chain in a comprehensive structure is vital for its applicability. To cope with the design and planning issue of a comprehensive closed-loop supply chain network, this paper develops an extended model, which is multi-echelon, multi-product, and multi-period in a mixed integer linear programming framework. The word 'comprehensive,' in our mathematical approach, in designing and planning a closed-loop supply chain problem, can be analyzed from two complementary angles: including all possible entities (facilities) of a real condition and considering minimum limitations on possible flows between entities. In our proposed model, customers can be supplied via manufacturers, warehouses, and distributors, as an example. The proposed model is solved by CPLEX optimization software and by a developed genetic algorithm. During this computational analysis, we compare results of proposed pretuned genetic algorithm with a global optimum of CPLEX solver. Then, a sufficient number of large-size instances are generated and solved by the proposed genetic algorithm. To the best of our knowledge, there has been no similar multi-period multi-product closed-loop supply chain design and planning problem utilizing any kind of meta-heuristics let alone genetic algorithms. Therefore, in this issue, it is an original research, and results prove the acceptable performances of the developed genetic algorithm. [ABSTRACT FROM AUTHOR]

The colleagues of the author of this paper applied the concept of 'contact' in differential geometry into the machining of the sculptured surface (Chun et al., Math Theor Appl, 23(3):105-108, ) and presented the second-order contact principle of the machining of complicated surfaces, using the circumference circle of the flat-end mill to sweep the curved surface instead of ball-end mill. But only mathematical deductions were presented in the paper. This paper proves that it is a highly effective method. Compared with other references, the theory of this paper is more restricted, and the method of this paper is suitable to the primary analytic geometry and the simulation surface of the numerical geometry as well. With definite procedure of calculation, the equations in this paper are easily solved. [ABSTRACT FROM AUTHOR]

In this paper, a multiproduct multiperiod capacitated production system that has been organized as a flow shop is considered. The main novelty of the paper is proposing a more efficient mathematical model for the problem of integrating lot sizing and scheduling with sequence-dependent setups. In comparison to the former model, because of fewer continuous and binary decision variables and constraints in the proposed model, this model is very easier to solve. Comparison between two models proves the superiority of the proposed model. Two mixed integer programming-based approaches with rolling horizon framework have been used to solve this model. To evaluate the performance of the proposed model and solution method, problems of different scales have been studied. The used algorithms search the solution space for both lot-sizing and scheduling problems and find a combination of production planning and scheduling that is feasible and close to optimum. [ABSTRACT FROM AUTHOR]

This paper suggests a data envelopment analysis (DEA) model for selecting the most efficient alternative in advanced manufacturing technology in the presence of both cardinal and ordinal data. The paper explains the problem of using an iterative method for finding the most efficient alternative and proposes a new DEA model without the need of solving a series of LPs. A numerical example illustrates the model, and an application in technology selection with multi-inputs/multi-outputs shows the usefulness of the proposed approach. [ABSTRACT FROM AUTHOR]

Many control problems encountered in industrial applications such as deburring, cutting, and polishing are required to simultaneously perform force control and contour following. If the mathematical model of the contour to be followed is known, then the control problem is straightforward, and many existing approaches can be used to tackle this problem. In contrast, if the mathematical model is not available, the control problem will become much more challenging. Among all possible solutions to circumvent the aforementioned difficulties, using a vision system to obtain the mathematical model of the contour to be followed is one of the best options. To this end, this paper proposes a vision-based approach, in which a vision system is employed to provide the exterior contour information of the object for machining. Subsequently, coordinate transformation between the image plane and the robot frame is performed. Based on the exterior contour information after coordinate transformation, a Pythagorean hodograph quintic spline interpolator based on S curve acceleration/deceleration is developed to generate motion commands. The fact that the arc length of a Pythagorean hodograph curve can be easily computed makes it particularly useful when performing motion planning for high-precision motion control systems. Moreover, in order to improve contour following accuracy, an integrated motion control structure consisting of an adaptive disturbance compensator, a sliding mode controller, and a friction compensator is also developed. Finally, several contour following experiments are conducted by a planar two-link robot manipulator to verify the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

The modeling of cutting forces plays an important role in the progress of research and technology in most machining processes. In particular, peripheral milling is a cutting process difficult to model due to the large number of variables involved. Among these variables, tool runout affects process performance by modifying milling force patterns, shortening the tool life and machine components, and by degrading workpiece quality. In this paper, a methodology to evaluate tool runout in peripheral milling is presented. The use of a boring toolholder is proposed to make controllable changes in the tool offset that modifies tool runout. In addition, the proposed methodology has been validated by means of a piezoactuator-based system that allows tool runout compensation through controlling workpiece displacement. Experimental and simulated results presented in this paper reveal the practical applications of this methodology for researchers and engineers involved in the practice of milling and its modeling. [ABSTRACT FROM AUTHOR]

The circular and cylindrical features are fundamental geometric features in machines. Cylindricity error affects the fitting conditions of cylindrical components and impacts the performance of the precision products. In this paper, the cylindricity error was modeled using L-F functions and evaluated by particle swarm optimization algorithm. Then the contact method is developed to determine the position accuracy through the virtual assembling of the bore and shaft using Monte Carlo simulation. The effects of the cylindricity error and the number of lobes on the position error were analyzed in detail. The results indicate that the cylindricity error has more significant influence on the position accuracy between the cylindrical parts than the roundness error. Using the suggested method in the paper, the position accuracy can be rapidly predicted after the design tolerances are allocated or the geometrical errors are measured on manufactured parts. [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]

In a free state, nonrigid parts can take on different shapes compared to their design model. Such behavior of nonrigid parts introduces particular challenges to engineers during the geometric and dimensional requirements specification and inspection steps. Given that the choice of inspection method is guided by the requirement specification type, this paper presents two sections dealing, respectively, with the specification and the inspection method used for nonrigid parts. Accordingly, this paper proposes a categorization of the particular specification methods used for the geometric dimensioning and tolerancing of nonrigid parts under the American Society of Mechanical Engineers and International Organization for Standardization standards, as well as a review of the available approaches for the fixtureless inspection method of these parts. Typical applications of each specification method, as well as the advantages and drawbacks of their use, are proposed as general guidance. Finally, the current research trends into the fixtureless inspection methods of nonrigid parts are underscored. [ABSTRACT FROM AUTHOR]

With the application of the 5-axis abrasive water jet (AWJ) machining center, some shape errors, such as cock tail striation, taper, etc., have been removed successfully, and the cutting precision has been improved greatly. However, the shape error located in the cut-in/cut-out region is still a big issue in AWJ cutting process. It often leads to the result that parts cut by AWJ becomes unacceptable. Based on theoretical analysis of the shape error in this region, it is found that the mathematical model used in 5-axis AWJ machining to compensate taper is often built on cutting data within normal cutting speed range. Therefore, the mathematical model becomes inaccurate in cut-in/cut-out regions, where very low cutting speeds are used. To solve this issue, a method of adding an extra nozzle tilting angle is proposed in this paper. This method has been proved to be effective through a series of experiments. With this method, the cutting precision could be improved not only in cut-in/cut-out regions, but also in corner regions where very low cutting speeds are used. [ABSTRACT FROM AUTHOR]

Studies on scheduling with learning considerations have recently become important. Most studies focus on single-machine settings. However, numerous complex industrial problems can be modeled as flowshop scheduling problems. This paper thus focuses on minimizing the makespan in an m-machine permutation flowshop with learning considerations. This paper proposes a dominance theorem and a lower bound to accelerate the branch-and-bound algorithm for seeking the optimal solution. This paper also adapts four well-known existing heuristic algorithms to yield the near-optimal solutions. Eventually, the performances of all the algorithms proposed in this paper are reported for small and large job-sized problems. The computational experiments indicate that the branch-and-bound algorithm can solve problems of up to 18 jobs within a reasonable amount of time, and the heuristic algorithms are quite accurate with a mean error percentage of less than 0.1%. [ABSTRACT FROM AUTHOR]

This paper addresses a dynamic capacitated production planning problem in steel enterprise employing a closed-loop supply chain strategy, in which the remanufacturing process is applied. Particularly, the remanufacturing problem considered in this paper is obviously different from the typical lot-sizing problems, within which all demands are met by production or remanufacturing without backlogs; the production, inventory, and remanufacturing levels all have limits; both the production and remanufacturing setup cost functions are arbitrary and time-varying; the objective is to minimize the total cost. Firstly, the closed-loop supply chain with remanufacturing model is formulated. Then, the genetic algorithm heuristic approaches are proposed to solve the NP-hard problem. Finally, a computational experiment is presented which can solve the 200 size problem efficiently. Furthermore, the comparisons against the branch and bound method show the effectiveness and efficiency of the proposed approach for solving the large size remanufacturing problem. [ABSTRACT FROM AUTHOR]

This paper studies the effects of geometrical errors on the repeatability of positioning of linear axes, based on theoretical modeling and an experimental study. Firstly, this paper elaborates on the mechanism of repeatability of positioning that is affected by motion pose of moving part. Secondly, a mathematical model is proposed between the geometrical error and motion pose of the moving part, based on point-by-point recursion. Subsequently, the influence of geometrical errors on the repeatability of positioning of the linear axes is obtained based on GA (genetic algorithm). Finally, the effectiveness of the proposed model is validated experimentally, and an assembly method for improving the repeatability of positioning is proposed. The method can provide designers and/or field engineers with informative guidelines for improving the repeatability of positioning in the design, manufacturing, and assembly processes. [ABSTRACT FROM AUTHOR]

The idea of Milk Run has been used in the context of logistic and supply chain problems in order to manage the transportation of materials. In this paper, we propose a new Milk Run method, as a mixed integer approach, to manage supply chain problems. Since the resulted problem formulation is NP-Hard, we use some meta-heuristic and compare the results with the optimal solutions of the proposed Milk Run method. The mathematical modeling of this paper is purposely customized for a special case of an auto industry. We implement the mathematical formulation and the meta-heuristic using some actual data and compare the results with the current strategy. The preliminary results indicate that the proposed method could provide a practical tool to significantly reduce the cost of logistic. [ABSTRACT FROM AUTHOR]

Traditionally, decisions on the use of machinery are based on previous experience, historical data and common sense. However, carrying out an effective predictive maintenance plan, information about current machine conditions must be made known to the decision-maker. In this paper, a new method of obtaining maintenance information has been proposed. By integrating traditional reliability modelling techniques with a real-time, online performance estimation model, machine reliability information such as hazard rate and mean time between failures can be calculated. Essentially, this paper presents an innovative method to synthesise low level information (such as vibration signals) with high level information (like reliability statistics) to form a rigorous theoretical base for better machine maintenance. [ABSTRACT FROM AUTHOR]

Electro-discharge machining (EDM) of thin deep features widens processing opportunities of difficult-to-cut materials, such as Ni-based alloys, towards attractive industrial applications. Conversely, the complex interaction between electrical, thermal, and chemical phenomena in EDM thwarts process modeling and prediction. As a matter of fact, recent experimental discoveries encourage setting forth a new theory of discharge ignition in the gap, based on the role of debris, which lays foundations for a recursive mathematical model showing a chaotic evolution. The paper reports on electro-discharge drilling of small deep holes in Inconel 718. Process performances are measured with varying electrode size and geometry, attesting a pivotal effect of gap pollution on productivity and on the onset of a secondary detrimental removal of material by intergranular corrosion. All findings support the emerging model for discharge ignition via debris bridges, and, most notably, debris chains are documented for the first time in the field of metals, second only to a previous case for a ceramic composite. On the whole, the paper provides conclusive validation of the role of debris in the ignition of discharges. [ABSTRACT FROM AUTHOR]

Nonlinear partial differential equation of temperature distribution with material properties varying was linearized by choosing appropriate linearization coefficient and solved through Green's function and Fourier transform methods. According to these results deduced, analytical model of arc welding temperature distribution under material properties varying condition was obtained. To verify precision of the analytical model obtained, temperature distribution of semi-infinite body under moving spot heat source was calculated through three different methods, including analytical model with and without considering material characters varying and finite element model. By comparing weld pool size calculated through the three methods, results got from analytical model of this paper were found more close to which got from finite element method. Conclusion was that, by taking material properties varying into account, analytical model deduced in this paper had higher precision, especially near the area of weld pool where temperature gradient was very great in welding process. [ABSTRACT FROM AUTHOR]

Variation propagation modeling of multistage machining processes enables variation reduction by making an accurate prediction on the quality of a part. Part quality prediction through variation propagation models, such as stream of variation and Jacobian-Torsor models, often focus on a 3-2-1 fixture layout and do not consider form errors. This paper derives a mathematical model based on dual quaternion for part quality prediction given parts with form errors and fixtures with N-2-1 (N>3) layout. The method uses techniques of Skin Model Shapes and dual quaternions for a virtual assembling of a part on a fixture, as well as conducting machining and measurement. To validate the method, a part with form errors produced in a two-stationed machining process with a 12-2-1 fixture layout was considered. The prediction made following the proposed method was within 0.4% of the prediction made using a CAD/CAM simulation when form errors were not considered. These results validate the method when form errors are neglected and partially validated when considered. [ABSTRACT FROM AUTHOR]

Slicing is an important step for all layer-based additive manufacturing (AM) processes. This paper proposes an improved and robust slicing algorithm with efficient contour construction to reduce the slicing time and be able to slice a complex STereoLithography (STL) model with millions of triangles (resulting from high-accuracy STL files). Also, another important feature of the proposed method is it can identify outer and inner contours automatically. Test results to demonstrate the improvements in execution time and comparisons with results from published papers have been given to illustrate the algorithm efficiency. The robustness of this slicing algorithm is demonstrated by several complex models with large numbers of nested contours on each slice. [ABSTRACT FROM AUTHOR]

Complex systems are categorized by large numbers of components and cut sets with different types or by statistical dependence between the components' states. Considering this fact, selecting the best maintenance policy for a complex system is a complicated problem. This problem becomes more difficult when we are faced with several actions such as replacement or different repair levels with different cost and failure reduction effects, for each component. In this paper, we propose a mathematical bi-objective model that considers the corrective maintenance (CM) and preventive maintenance (PM) to minimize cost and maximize the reliability for a complex system consisting of series and standby components. Since the proposed model is non-deterministic polynomial-time hard (NP-hard), we utilize the non-dominated sorting genetic algorithm II (NSGA II) that is mostly used to solve the multi-objective models. The proposed NSGA II has a memory to obtain better results in comparison with common multi-objective evolutionary algorithm. The performance of the proposed model has been examined against a numeric instance to indicate the model's efficiency and effectiveness. [ABSTRACT FROM AUTHOR]

This paper proposes a multi-objective mathematical formulation and a hybrid approach to solve buffer sizing and machine allocation problems simultaneously in unreliable production and assembly lines. This paper unlike prior researches assumes that time-dependent parameters of production systems are generally distributed (e.g., uniform, normal, gamma, etc.) and not only deterministic or exponential. This paper proposes a multi-objective mixed binary integer non-linear mathematical model to solve the problem of buffer sizing and machine allocation. The proposed mathematical model is capable of purchasing new machines (candidate) and also selling old machines (current available). In other words, this model compares the candidate machines to current available machines in each station based on different aspects and is capable to replace the current machines with candidate machines or to sell some of the current machines without replacement. To solve the mentioned problem, a new formulation for dealing with multi-objectiveness of the problem is proposed. This formulation generates a series of non-dominated solutions, and also, it is capable of generating a non-dominated solution between two adjacent non-dominated solutions determined by decision maker. A hybrid genetic algorithm (HGA) with a new dynamic mutation probability is proposed to solve the model. Since the proposed mathematical model and the proposed solution method are novel, the proposed HGA is compared to simple genetic algorithm and non-dominated sorting genetic algorithm (NSGA-II). The computational results indicate the effectiveness of the proposed HGA. [ABSTRACT FROM AUTHOR]

In the electroplastic wire drawing process, the drawing force is reduced with the application of an electric current. The drawing force drop is the result of a combination of various factors. The objective of this article is to build a theoretical formula between the electroplastic effect and the drawing force. Based on existing electroplastic effect theory and experimental results, the mechanical characteristics of the electroplastic wire drawing process are analyzed, and a mathematical model of the electroplastic drawing force is established. This calculation method takes into account both the influence of electroplastic effect on metal’s flow stress and the change of the wire temperature with an electric current applied. Finally, the results of experiment and theoretical calculations are compared and analyzed. The results of this paper will provide a reference for the theoretical calculation and simulation study of the electroplastic effect in engineering applications. [ABSTRACT FROM AUTHOR]

This paper presents a new decentralized/distributed decision-making (DDM) supply chain planning model. A supply chain is called decentralized when various decisions are made in different companies trying to optimize their own objectives. The proposed approach is applied to plan a wood supply chain network called Puya Wood Company. The supply chain network design problem discussed in this paper is an integrated multi-echelon, multi-product problem considering total costs of purchasing raw materials/returned product, transportation of raw materials, and inventory holding of raw materials. A coordination mechanism is designed to share information between the retailer model and the manufacturer model called centralized planning. The main contributions of this paper are summarized as follows: (1) presenting a decentralized (distributed) approach in order to address the production and distribution problem in supply chain including manufacturer and retailers and (2) proposing a coordination mechanism in order to handle problems related to production and distribution in a two-echelon supply chain network through a decentralized approach. The proposed model is tested using real case study. Sensitivity analysis is accomplished to find the effects of changing the parameter on the results. The proposed coordination mechanism provides high-quality solutions in reasonable number of iterations for the case study. This coordination mechanism can be applied in other supply chains such as natural gas and oil, water resource management, and crisis and disaster planning. [ABSTRACT FROM AUTHOR]

Abrasive waterjet (AWJ), due to its unique advantages over the traditional machining process, has been used as a main machining tool extensively. However, the kerf profile defect, which is inherent to AWJ cutting, is one of the major obstructions that limit its applications in high-precision cutting. To improve the precision of AWJ cutting, an intensive study on kerf profile is very important. Previous researchers used taper to characterize kerf profile generated by AWJ in past years. However, we find that the requirement of precision cutting cannot be satisfied by using taper error to describe the kerf profile defect and further by tilting cutting nozzle a taper angle in the opposite direction to eliminate taper error. In this paper, the parameters which might affect the kerf profile have been investigated in detail. Based on the investigation, the kerf profile has been characterized by a mathematical model instead of a taper angle. With this mathematical model, predicting the kerf profile accurately according to the cutting conditions becomes feasible. [ABSTRACT FROM AUTHOR]

The product variation in a machining process is mainly affected by datum error, fixture error, and machine tool path error. In spite of the success of equivalent fixture error approach to compensating datum error and machine tool path error, the machining-induced errors have not been explicitly modeled and compensated by the current compensation model based on equivalent fixture error. This will limit its application in compensation accuracy. This paper formulates a new error compensation model for machining process using equivalent fixture error concept based on differential motion vectors. With this model, datum error and machining-induced errors can be transformed to equivalent fixture locator errors and then compensated. A real cutting experiment and an error compensation simulation for machining process will be conducted in the case study to demonstrate the model validity. [ABSTRACT FROM AUTHOR]