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Abstract: This paper presents a new approach for the determination of cutting-force coefficients. The proposed methodology models a practical mechanism for collecting and analysing experimental data. The surface error is the measured parameter used for defining the cutting-force coefficients. The cutting tool deviation resulting from the cutting forces is considered as the main element of the surface error. The proposed mechanism consists of cutting two strips with the same cutting conditions but the axial depth of cutting differs with the height of the elemental axial disk. Hence, the resultant surface error represents the deviation of the cutter while cutting the strip with axial depth equal to the cutter elemental axial disk. The size effect has been taken into account when generating the functions for the cutting-force coefficients. Milling experiments have been conducted to verify the methodology and are reported in the paper. The proposed method overcomes the need to analyse and recalculate the instantaneous chip thickness, which is associated with the experimentally measured cutting forces traditionally used in the process of defining the cutting-force coefficients. The new approach provides the simulation process with instantaneous cutting-force coefficients, which are independent of the cutting operation geometry. The results when applying the new cutting-force coefficients show a good agreement between the predicted and measured surface error. [Copyright &y& Elsevier]

Abstract: In comparison with machining of worm on a lathe or on a milling machine, whirling process uses a rotating tool ring carrying tools and encompassing the work blank. Due to nature of contact between tool and work blank, simulation of whirling process is necessary to understand the geometry of worm surface generated. In this paper, an attempt is made to simulate the whirling process and analyze the effect of tilting of tool head. In some applications worm geometry is specified and tool geometry has to be arrived at. An approach for profiling of tool is explained in this paper and validation of tool profile is carried out by simulation. Two worms, namely straight-sided in axial section and involute helicoid are taken as case studies and results are discussed. [Copyright &y& Elsevier]

The major purpose of this paper is to assure quality in mass production by using improved robust design. The essential activity in quality assurance is to achieve high quality (Cpk≥1.33). The reduction of dispersion and the reduction of bias are indispensable for the achievement of this high quality. This paper discusses the way to improve the robust design based on regression analysis for high quality, low cost and high productivity. Simulative experiments and simulative manufacturing using paper helicopters are used as concrete examples, and an education program is introduced in order to explain this approach in detail. [Copyright &y& Elsevier]

Abstract: A new rotary forming process used to thicken the rim of a disc-like part was proposed. The paper details the results, design and manufacture of the corresponding apparatus. The center point of a ring roller moves around the axis of a stationary work-piece in a plane spiral locus, like a rounding hula hoop. Thereby, the rim of stationary work-piece is rolled and thickened. A design rule for the rotary thickening process of the disc-like part was proposed, and a formula for calculating the feeding force of the roller was deduced. Both the design rule and the formula were verified by the results of experiment and finite element simulation. The forming and flow law during the thickening process were also illustrated. [Copyright &y& Elsevier]

Abstract: The present paper investigates the simulation analysis of simultaneous mold filling and solidification of ductile iron casting in a permanent mold by virtue of its thermal characteristics. Thermal analysis was performed to determine the solidification behavior and nature of alloy of the melt during its solidification. It revealed the variation in the nature of alloy due to the variations in eutectic freezing and carbon equivalent of the melt. The obtained thermal parameters from the thermal analysis were further used for the casting simulation of the melt. The simulation results show a progressive solidification behavior of the casting. There is a significant decrease in the overall heat transfer coefficient with time during the solidification process. The simulation results were further verified experimentally. The experimental results show porosity defects at the top section of the casting. Two distinct zones (center and outer) were observed on the produced samples based on the average graphite nodule counts and average graphite nodule size. [Copyright &y& Elsevier]

Abstract: The downscaling of manufacturing processes leads to a rise in new challenges in process design. Amongst these challenges is a decrease in the limiting drawing ratio observed in micro deep drawing of metal foils. Furthermore, fracture occurs at punch force levels well below those predicted by common equations. In this paper it is proposed that these phenomena can be accounted for by non-uniformities in the flow behavior of the material due the large difference between grain sizes. The localized strains before fracture – as recorded by digital image correlation – of stretch formed aluminum foils are presented and the strain evolution is examined. Evidence to verify the hypothesis is gathered by implementing the observed flow non-uniformities into a finite element simulation and comparing the computed results to the experimental ones. [Copyright &y& Elsevier]

Abstract: During the last few years it has become more and more customary for major industries to use FEM simulations during the product creation process. Most of these metal-forming process simulations are based on elastic plastic behaviour of material and use non-deformable tools. For a correct use of FEM simulations in product development stages, it is very important to determine the accuracy of the simulations. For multi-stage processes, it can be more effective not to simulate the total process but only a few stages of the process, with the last stages usually being the most important ones. To start simulations half way the total process calls for information on the semi-finished product. This information is generated by means of measured values in order to decrease the total modeling time and to increase the accuracy. This paper shows a method developed for handling these problems. The method based on a fully automatic measuring device, including a LECO hardness tester. The results of these measurements were used to verify models, including models based on the transformation behaviour of strain-induced martensite. The examples presented are based on products made of a stainless steel called Nanoflex . [Copyright &y& Elsevier]

Abstract: This paper presents a new looper–tension control scheme to minimize the tension variation between two stands in the hot strip finishing mill. The proposed control scheme is designed on the basis of a 5th order state space model for a looper system and composed of two main parts. First, a receding horizon control (RHC) feedback controller with a minimal-order disturbance observer (DOB) is employed to satisfy the constraints on the control input/state and guarantee the stability. The observer is also designed for attenuating the speed disturbances of the main motor. Second, a subspace-based state space system identification (4SID) model identifier is introduced to adopt the variation of system parameters. It is shown through simulation that the proposed control scheme satisfies the constraints on the control input/state, diminishes the tension variation for the parameter variation and the speed disturbances, and reduces the computational burden for the model adaptation as well. [Copyright &y& Elsevier]

Abstract: Multi-point stretch forming (MPSF) is a flexible manufacturing technique to form large sheet panels of mild curvature. The traditional fixed shape-stretching die is replaced by a matrix of punch elements, and the sheet metal are stretch-formed over the multi-point stretching die (MPSD) generated by the punch element matrix. In this paper, extensive numerical simulations of the processes for stretching parabolic cylinder, toroidal saddle and sphere parts were carried out by dynamic explicit finite element analysis. The forming results using multi-point die were compared with those of using traditional die. The use of an elastic cushion to suppress dimpling of the part caused by the discrete punch elements was investigated along with a discussion of its influence on part shape accuracy. The effect of the size of punch element and the shape of MPSD on the shape accuracy of formed parts were analyzed. The results may provide useful guidance on determining MPSF parameters and optimizing MPSF manufacture processes. [Copyright &y& Elsevier]

Abstract: A manufacturing process for fabricating a cylindrical crown gear drive that is provided with a controllable fourth order polynomial function of transmission error is proposed in this paper, and the procedures for creating the mathematical models of the tooth surfaces are described. In order to reduce the level of gear running noise, a pre-designed fourth order polynomial function of transmission error is assigned to the gear drive. To avoid edge contact, the tooth face of the output gear is longitudinally crowned by employing a form grinding wheel that is driven by a parabolic motion. Based on the theory of gearing, mathematical models of tooth contact analysis (TCA) are created, and mathematical models of principal curvatures and directions and contact ellipses are developed. A numerical simulation of meshing is performed, and the proposed gear drive is proved numerically to be able to reproduce the pre-designed fourth order polynomial function of transmission error. The influence of varying the parameter of parabolic motion of the grinding wheel on the dimensions of contact ellipses is also analyzed. [Copyright &y& Elsevier]

Abstract: The phenomenological models for material flow stress and fracture typically used in the finite element simulations of hard machining processes do not adequately represent the constitutive behavior of the workpiece that is usually heat treated to hardness levels ranging from 50 to 62HRC. Thus, new flow stress models which include also the hardness effect should be developed and used accordingly in computer simulation of hard machining. This paper describes the development of a hardness-based flow stress and fracture models for machining AISI H13 tool steel, which can be applied for a wide range of work material hardness. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the influence of work material hardness on the chip formation process. Predicted results are validated by comparing them with experimental results from literature. They are found to predict well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the hardness values change. [Copyright &y& Elsevier]

Paper describes means and methods for computer based optimisation of production processes using a new approach based on technological database (TDB) with genetic algorithm incorporated into a database management system (DBMS). The TDB serves as a store of tools and machine tools from which they can be assigned to different work operations. Work operations are basic entities of orders placed into queues. The goal of the model is to find available resources from the TDB in order to empty the queue in shortest time with lowest costs. To this purpose the model consist the technological database whose DBMS includes a genetic algorithm based optimiser. It checks the orders queue and searches for appropriate combinations of tools and machine tools from the TDB, which can be combined into needed work operations. It also performs an optimisation of time and costs according to so called static parameters of tools and machine tools. [Copyright &y& Elsevier]

Abstract: Virtual manufacturing (VM) is one of the research focuses in manufacturing at present. By analyzing and modeling the forming process of workpiece and the error sources contributing to machining precision of workpiece in turning operation, the cutter trajectory and attitude representation (CTA_Rep) is presented to characterize the geometric errors of machined workpiece in VM. Then a surface topography simulation model is established to simulate the surface finish profile generated after a turning operation. This representation is implemented in the Virtual Machining and Measuring Cell (VMMC) developed by the authors to represent and predict the geometric errors of workpiece. Satisfactory results are obtained. [Copyright &y& Elsevier]