Search

The heat and mass transfer behavior of droplet transfer in the CO2 welding process plays a decisive role in weld formation, joint microstructure, and service performance. Studying the process of droplet transfer is of great significance for welding metallurgical analysis, stress deformation analysis, process control, and process optimization. In recent years, welding scholars have devoted themselves to the theoretical analysis of the dynamic information of droplet transfer through numerical simulation and combined with experimental research, so that the welding process has changed from qualitative analysis to quantitative analysis, and the theoretical research and experimental research have been upgraded to scientific research. Based on the available data, this paper takes the CO2 welding process as the object and finds that in recent years, the numerical simulation field of CO2 welding droplet transfer has developed in the direction of arc-droplet-pool integration. However, there are still some problems in the existing mathematical model, such as insufficient model accuracy, too much calculation, too many assumptions, and too large gap between the actual and other problems. It can be predicted that the future development direction of the numerical simulation of the droplet transfer will be towards refinement and high efficiency. [ABSTRACT FROM AUTHOR]

In tolerance analysis, the effect of clearance fits is especially difficult to estimate because the mating parts are not necessarily in actual contact and can take an infinite number of relative positions. The treatment of these situations is allowed in most of the available methods, possibly introducing additional elements in the dimension chains with appropriate statistical assumptions. The paper provides a similar extension for the static analogy, a previously proposed method that converts the tolerance analysis problem into an equivalent problem of force analysis. The procedure represents each fit, possibly between patterns of features (e.g., fasteners and holes), with a proper constraint in the equivalent static model. The ability of the constraint to transmit forces and torques is determined according to the types and directions of misalignments allowed by the joint clearance. With simple rules, this avoids complications in the static model, which must include only the constraint between parts rather than the geometric details of the mating features. The extended method, currently limited to 2D dimension chains, is demonstrated on examples involving both dimensional and geometric tolerances. The comparison with existing methods shows the correctness of the proposed procedure. The simplicity of the workflow confirms the possibility, already demonstrated for the static analogy, of avoiding numerical simulations or even the use of computer-based tools. [ABSTRACT FROM AUTHOR]

In this paper, thin-walled aluminum alloy parts were fabricated using electromagnetic incremental forming with an elastic cushion. The effect of the thickness of the elastic cushion and the discharge voltage on the skin-forming quality is analyzed using numerical simulation. When the discharge voltage is 6 kV, the springback of the sheet decreases with increasing cushion thickness. However, when the cushion thickness increases to 15 mm, the sheet surface produces a 0.78-mm bulge. When, however, a 10-mm-thick cushion is used, the springback of the sheet decreases with increasing discharge voltage. On the other hand, when the discharge voltage is 8 kV, the surface of the plate produces a 1.14-mm bulge, which makes the surface not smooth. Therefore, the optimal process parameters in this paper are a 7-kV discharge voltage and a 10-mm cushion thickness. Moreover, the springback of the sheet metal can be greatly reduced after discharging six times at different positions. Based on the optimum process parameters, which are determined by the numerical simulation, experimental testing is performed. The experimental results are consistent with the simulation. [ABSTRACT FROM AUTHOR]

Multi-stage hot forging is widely used to produce complex forged products in inFdustry. Flash after the forging should always be minimized for the material saving, and it is important to determine the preform shape minimizing the flash. The process parameters in multi-stage hot forging such as the billet temperature and the stroke have also an influence on the product quality as well as the flash, but they are still determined by a trial-and-error method. In this paper, multi-objective design optimization in three-dimensional multi-stage hot forging is numerically performed so as to minimize both the flash and the distribution of equivalent strain. The preform shape and the process parameters such as the billet temperature, the die temperature and the stroke are optimized. The three-dimensional numerical simulation is computationally so expensive that sequential approximate optimization that response surface is repeatedly constructed and optimized is adopted to identify the pareto-frontier between the flash and the distribution of equivalent strain. It is found from the numerical result that 60% reduction of flash can be achieved, compared to the conventional preform shape. In addition, the total forging energy considering the multi-stage hot forging is reduced. It is confirmed through the numerical result that the proposed approach is valid to determine the optimal preform shape and process parameters in multi-stage hot forging. [ABSTRACT FROM AUTHOR]

Cast steel nodes are widely used as important components of offshore platform, owing to their better performance than welded nodes. In this paper, the mold filling and solidification process of cast steel nodes were numerically simulated and verified by the finite element analysis commercial software package—ProCAST, and the occurrence of shrinkage porosity was quantitatively predicted based on the simulation results. The numerical simulation results of the preliminary design showed that the overall filling was stable with bottom gated system, agreeing well with the design requirements. However, the shrinkage porosities in the intersection of lower tubes and main tube were evident due to the insufficient feeding. Optimization of the casting design was carried out through repeated computer simulation. By incorporating chills in the cores, the optimized design showed that the shrinkage porosities in the intersection of lower tubes and main tube were effectively eliminated. In view of these aforementioned optimizations, the casting steel can meet the technical requirements in an actual production. [ABSTRACT FROM AUTHOR]

Elbow pipes are widely used in many industries such as petroleum, chemical, and metallurgy. Of various elbow pipe forming technology, hot pushing pipe bending process is an efficient and economical one for processing elbow pipes. This paper introduced the technological process and plastic deformation mechanism of hot pushing pipe bending. Four deformation assumptions were proposed to describe the main deformation characteristics in the bending process. The proportional relationship between the bending deformation and the diameter expansion deformation was derived and the horn mandrel was designed. The forming process of the elbow was simulated and the metal flow in the forming process of the elbow was obtained. The results showed that controlling the axial compression and circumferential expansion in proportion is the key to getting constant wall thickness. By using the horn mandrel with variable curvature axis, it benefits the metal flowing uniformity from the concave side to the convexity, avoiding the increase of the inner wall thickness and the decrease of the outer wall thickness during pipe bending. Taking the minimum change rate and good uniformity of the concave side wall thickness as goals, the optimal process parameters were obtained, that is, the heating temperature is 750° Celsius, the pushing speed is 3 mm/s, the friction factor is 0.15, the bending angle is 45° and initial bending radius is 2.0 mm. It will play a positive role in revealing the pipe forming mechanism and have a guiding effect on production practice. [ABSTRACT FROM AUTHOR]

This paper presents SERobWaS, a support environment for a fleet of mobile robots operating in warehousing environments. SERobWaS integrates three subsystems necessary to control the missions of the fleet of robots, namely a task scheduler, a route planner, and a motion planner. Task scheduler is responsible for allocating the required logistics tasks to robots. Route planner determines the necessary routes (paths) to be followed by the robots in order to achieve their (allocated) tasks. Motion planner produces the robots' collision-free movements on the generated routes. A motion plan specifies the actual motion to be executed by a robot and consists of a generated velocity profile along the path and a set of turning commands to the robot's wheels. In the algorithmic level, SERobWaS uses a special genetic algorithm (GA) to simultaneously address task planning, route planning, and global motion planning problems. Collisions avoidance between the robots during their motion is further achieved in a second stage by a simple quite fast algorithm. Computer simulations demonstrate the operation of SERobWaS. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation and numerical modeling of the mechanical behavior and damage of the near-surface layer of mechanical parts, pre-machined by the EDM process. The intended purpose is therefore to understand and then predict the impact of this process on the service life of machined parts. In situ mini-tensile tests under XRD were performed to characterize the mechanical behavior of the near-surface layer preloaded by the residual stress and strain-hardening gradients previously induced by the EDM process. These tests were also used to identify the parameters associated with the numerical model. The results of this study revealed that the interface between the base material and the near-surface layer is the seat of a significant incompatibility of plastic deformations, which accelerates the rate of damage in this zone and supports the development of microcracks. This cracking tendency is enhanced by the omnipresence of residual stress and strain-hardening gradients. [ABSTRACT FROM AUTHOR]

In the process of internal thread cold extrusion, the extrusion tap is an indispensable tool. Therefore, it is important to improve the service life of the extrusion tap and reduce the tool wear. In this paper, using Central Composite Design response surface test, the influence of the parameters (including the guide cone angle, backhoe capacity, guide cone length and working cone length) of the extrusion tap on the forming quality of internal cold extrusion are investigated, so as to obtain the minimum extrusion torque and the minimum extrusion temperature. A polynomial regression response model of the minimum extrusion torque and minimum extrusion temperature is obtained. Using the regression model, the objective function is optimized, and a group of optimal parameters is obtained (guide cone angle: 10°, backhoe capacity: 0.32, guide cone length: 4 mm, and working cone length: 13 mm). Numerical simulation of the optimal parameters is also carried out. The results show that the measured extrusion torque and extrusion temperature are close to the predicted values with errors of 2 and 2.55%, respectively, which are well fitted by the model. [ABSTRACT FROM AUTHOR]

The ring with inner grid ribs (RWIGR) is a key mechanical part. Because of its light structure, high strength, high stiffness, and high carrying capacity, it is widely used in aerospace, special transporting equipment, and petrochemical and nuclear energy industries. Currently, the manufacturing of complex grid ribs mainly adopts cutting methods, which has low material utilization rate and low processing efficiency. Therefore, this paper proposes a novel forming method of radial constraining based on the current technical problem of the difficulty in integral forming of such RWIGR. That is, on the basis of the cylindrical ring rolling process, the continuous partial radial constraining squeezing process (CPRCSP) is adopted, so that the RWIGR can be integrally formed. The paper mainly does the following research work: (1) the process principle of the radial constraining squeezing forming is expounded, and the design method of squeezing molds is proposed. In addition, the squeezing deformation process of RWIGR is simulated and analyzed by the ABAQUS software. (2) Through the FE simulation results, the flow law and strain distribution of metal in the CPRCSP of RWIGR are analyzed. (3) The squeezing forming process of RWIGR is simulated under different squeezing process parameters, and the effects of different squeezing process parameters on RWIGR forming are revealed. (4) The experiment of CPRCSP is designed and implemented, which fully verifies the feasibility of the forming process. [ABSTRACT FROM AUTHOR]

This paper proposes a new flexible and microscale roll gap control technology to obtain a stronger strip flatness control ability. According to the principle of microscale roll gap control technology, an electromagnetic control rolling mill with the function of roll profile control and large diameter ratio rolling is designed and built. To analyze the flatness control ability, a comprehensive finite element model (FEM) is established, and an indentation experiment and a rolling experiment are carried out. The simulation results show that under different rolling forces and tensions, the average quadratic crown control ability is more than 40 μm, and the average quartic crown control ability is more than − 3 μm. The control ability increment of the quadratic crown is greater than that of the quartic crown. In the indentation experiment, a stable roll profile can be achieved by PID control after reaching the target roll profile. Increasing the regulation amount can change the strip crown from positive to negative. Even under high rolling force conditions, microscale roll gap control technology can also realize a strip crown adjustment of 19.5 to 0.5 μm. Moreover, this technology can adjust the strip shape from edge waves to non-waves and middle waves in the rolling experiment. In this paper, the feasibility of using this technology to adjust the roll gap shape has been verified, and we demonstrate that the roll gap control goal of uniform transverse size distribution can be achieved. [ABSTRACT FROM AUTHOR]

Thin-walled tubular parts with longitudinal ribs are important lightweight components. To manufacture the complex shape, incremental forming processes like flow forming are increasingly used. However, it is still difficult to form deep longitudinal ribs by conventional flow forming like ball spinning (BS). This paper proposes a novel flow forming process named two-stage flow forming (TSFF) to manufacture the thin-walled tubular parts with deep longitudinal outer ribs. The TSFF process includes two forming stages of preforming and final forming. During the preforming stage, the balls make axially feed movement, which force the metal to flow radially, and preform the longitudinal outer ribs. In the final forming process, the balls make axial feed movement and the blank makes rotation, which forces the metal to flow along circumferential and radial direction. Thus, the wall thickness is reduced, and the deep longitudinal outer ribs are formed. Based on numerical simulation, the forming geometrical dimension by BS and TSFF is compared, and the forming effect of TSFF is better. To make further analysis of metal flow behavior, it can be found that TSFF promotes the metal to flow along tangential and radial direction, while restraining the axial flow of the metal, and finally improve the filling effect of the longitudinal outer ribs. In addition, the key process parameters of TSFF were studied, and it was found that the reduction of preforming and ball diameter had great influence on the filling effect of the outer ribs. Finally, the TSFF experiment is carried, and the result shows that thin-walled tubular parts with deep longitudinal outer ribs formed by TSFF are feasible. This study provides theoretical and experimental support for the development of the novel flow forming process. [ABSTRACT FROM AUTHOR]

In order to better analyze and control the micro milling process of micro ball-end milling cutter, a method combining finite element method (FEM) and regression analysis is proposed to simulate and analyze the micro cutting process of cutting edge micro-element at different axial height positions to achieve micro milling force prediction. Combining cutting edge curve equations and actual measurements establish an accurate micro ball-end milling cutter model, and discrete along the axial direction of the cutter to obtain multiple sets of cutting edge micro-element of equal thickness. In this study, a workpiece micro-element model corresponding to the axial height position of the cutting edge micro-element is established based on the actual cycloidal motion trajectory during the micro milling of the cutting edge. Finite element simulation of single-edge bevel cutting of cutting micro-elements is implemented. Based on the micro cutting force data obtained from the micro cutting simulation, regression analysis is used to obtain the cutting edge micro-element unit cutting force related to axial height and cutter rotation angle for a certain amount of feed per tooth, and then the integral summation is used to achieve the micro milling force prediction. A comparative analysis of the full slot micro milling experiments shows that the predicted micro milling forces are in good agreement with the measured values, which directly verifies the correctness and reliability of the cutting edge micro-element cutting numerical simulation and micro milling force prediction method in the paper. [ABSTRACT FROM AUTHOR]

When welding high-strength steel and ultra-thin plates, traditional resistance spot welding has technical problems such as a narrow process window and difficulty in ensuring both welding strength and forming quality, making it one of the bottlenecks in the manufacture of high-end structural parts in the fields of vehicles, aviation, and aerospace. The core reason is that the traditional spot welding thermal cycle mode is single, the energy is highly concentrated, and the controllability is poor. Therefore, there is an inconsistency between its energy distribution and nugget quality. In view of the above difficulties, a new idea of resistance spot welding of special-shaped electrodes based on energy distribution design is proposed. By inlaying insulating ceramics and other materials on the electrode end face, a "composite annular electrode" is prepared to realize the regulation of energy distribution in the welding process. In this paper, experimental and numerical simulation are carried out to reveal the detailed influence of the diameter of the ceramic core on the joint forming and thermal distribution. The results show that the welding effect of composite annular electrodes is better than that of traditional electrodes under different thickness plates. The maximum strength of the joint can reach 2600 N. The maximum temperature during welding shall not exceed 1930 °C. And the optimal ceramic core diameter is optimized for ultra-thin plates and high-strength steel plates commonly used in automobiles. [ABSTRACT FROM AUTHOR]

Laser direct energy deposition (L-DED) can improve the forming efficiency of parts by controlling laser power, scanning speed, powder flow rate, and spot size. It is a good way to complete the processing and repair of complex parts. In this paper, a three-dimensional numerical model is established to study the dynamic cladding process (pool geometry, energy transfer, and dynamic solidification) of Inconel718 alloy during direct energy deposition. The fluid of volume (VOF) method is used to track the free surface of the melt pool, and the powder source model is established by discrete method. The results show that the molten pool size (area, width, height, depth) of the model is relatively uniform and can predict the shape of the molten pool well. The energy transfer in the molten pool is disturbed to some extent by the metal powder flow. The temperature gradient and cooling rate of the cladding layer are relatively large near the mushy area during the solidification process. [ABSTRACT FROM AUTHOR]

This paper proposes a new measurement method based on a single probe scanning to measure the roundness error of the artifact. The presented method simplifies the mathematical processing. There is no need for complex forward and inverse Fourier transforms. The probe is installed on a micro-stage platform, and a voice coil motor drives the micro-stage platform. In this paper, a precise mathematical model of the proposed measurement method is carried out and a detailed introduction process. Computer simulation analysis proves the feasibility and repeatability of the method. The related factors affecting the accuracy of the measurement system are analyzed, and the corresponding suppression methods are proposed. Finally, a comparative experiment verifies that this method dramatically improves the measurement accuracy compared to direct measurement. [ABSTRACT FROM AUTHOR]

For realizing the precision dressing of worm grinding wheel of face gear, this paper studies the over-cutting phenomenon of worm grinding wheel in forming dressing and puts forward the solution. Combined with the forming principle of face gear worm and forming dressing method, the influence of the continuous dressing method on the grinding wheel helix and the relative position between the dresser and the worm are expounded. Based on the numerical simulation model and the actual machining phenomenon, two kinds of over-cutting phenomenon are discovered. To ensure the surface integrity of grinding wheel in continuous processing, the reasons and laws of over-cutting are deeply analyzed. The first kind of over-cutting can be eliminated by increasing the angle between the extended line and the axis on the dresser, and a method of estimating the minimum angle is proposed for a more reasonable design of the dresser. The second kind of over-cutting can be eliminated by choosing proper dressing interval while ensuring the utilization efficiency of worm, and the selection criteria of dressing interval in continuous dressing are put forward. To verify the proposed methods, digital model, Vericut, and SolidWorks are applied, and the results show that the proposed method can effectively solve the over-cutting problem. [ABSTRACT FROM AUTHOR]

5A06 aluminum alloy has good corrosion resistance and no low temperature brittleness, so it is widely used in aerospace sheet metal components. However, when forming complex thin-walled parts, the surface forming quality and accuracy of the alloy are poor, and the forming performance is limited, which has been an important problem in application. In this paper, on the basis of hydrodynamic deep drawing, the rigid-flexible composite drawing warm forming process is innovatively proposed, which improves the forming quality of 5A06 complex bottom aluminum alloy parts and fittability. Taking aluminum alloy concave-bottom cylindrical parts as the research object, the influence law of rigid-flexible composite drawing warm forming process on the forming process and the fitting accuracy of concave-bottom cylindrical parts was explored by using the method of numerical simulation and forming experiment. The results show that under the process conditions of hydraulic pressure 20 MPa, sheet forming height 50 mm, and forming speed 1.8 mm/s, the maximum thinning rate of special-shaped bottom cylinder wall thickness is 21.3%, and the fittability is 97.3%. [ABSTRACT FROM AUTHOR]

Since the deformation region involves the interaction of electric-thermal-force coupling in electric hot incremental sheet forming, the numerical simulation of the forming process is unusually difficult. Currently, the thermal-force coupling method is adopted to simulate approximately the whole forming process, and the Joule heating effect is often ignored. Therefore, the numerical simulation of the Joule heating effect is especially significant for the prediction accuracy of forming process. In this paper, a novel numerical simulation method considering electric-thermal-force parameters was proposed to update the thermal-force condition of the forming region instantly. Meanwhile, the model of contact thermal conductance was established, combining geometrical and electric-thermal parameters. Then a high-precision finite element model was obtained to predict the Joule heating effect of the forming region. In addition to this, the impact of thermal superposition on forming temperature was further analyzed, and a modified model of contact thermal conductance was established in electric hot incremental sheet forming. [ABSTRACT FROM AUTHOR]

The springback behavior of thin metal sheets will significantly affect the forming accuracy of microchannels during microstamping process, especially as the forming scale reduced to micro-/meso levels due to the size effects and grain structures. This paper aims to study the size effects on springback behavior and microchannel's formability in microstamping process. The thin sheet of SUS304 specimens with different grain sizes was prepared and employed in uniaxial tensile tests to examine the stress–strain relationship and used to study the effects of grain sizes on the material's plastic deformation behavior. A constitutive model incorporate surface layer and grain structures is developed to characterize the deformation behavior of thin-metal sheet with different grain sizes. Then, the constitutive model is utilized in finite element simulation of microstamping process to fabricate microchannel structures, and the results are verified by experimental testing. Both numerical simulation and experimental results showed that the size effect is critical in microstamping process, and the developed constitutive model is able to accurately characterize the global springback behavior of thin metal sheets during microstamping process. [ABSTRACT FROM AUTHOR]

Machining distortion has been a long-term obstacle in the machining of aircraft monolithic parts. Furthermore, its stability has to be considered. The machining distortion stability represents the fluctuation degree of the machining distortion. This paper investigates the evolution of elastic energy induced by initial residual stress inside materials, revealing that this evolution directly affects machining distortion. In this paper, the concept of machining distortion stability and bending potential energy is defined. By analyzing bending potential energy releasing, this study proposes a novel method for improving machining distortion stability through optimization of material removal sequence. Numerical simulation and milling experiments are performed to verify and validate the model, respectively. The results indicate that the machining distortion stability is significantly improved when optimized material removal sequence is applied. By controlling the machining distortion stability, the final distortion can be further reduced via re-machining the machining datum at the beginning of the finishing stage. [ABSTRACT FROM AUTHOR]

This paper compares the microstructure and mechanical evolution in a high-strength quenched and micro-alloyed steel during the austenitising bending process. Simulation results indicated a new finding that the stress neutral layer (SNL) tends to move to the tension zone during straining. The hardness gradient detected from the centre to compression/tension zones was resulted from comprehensive factors: First of all, the location of SNL revealed a prominent impact on strength. Second, the dislocation accumulation would be responsible for the hardness gradient on the surfaces. In addition, the overall strength decrease during straining was mainly ascribed to integrated effects of dynamic recovery (DRV) and dynamic recrystallisation (DRX). Apart from that, overall smaller martensite packet size and coarser prior austenite grains resulted in the increased hardness value at a lower bending degree. Also, the high consistency between experimental and simulation results is instructive for the practical forming process of railway spring fasteners. [ABSTRACT FROM AUTHOR]

The toolpath smoothing and feedrate scheduling in computer numerical control (CNC) system are critical for high-speed and high-precision machining. The existing toolpath smoothing schemes perform insufficiently in raising the smoothness of feedrate trajectory. Aiming at increasing the smoothness of toolpath and reducing machining vibration, a smooth S-curve acceleration/deceleration(AD) control algorithm based on the jounce limited profile is proposed. In the paper, for the curves that do not meet the complete smooth S-curve acceleration/deceleration conditions, they are divided into three cases according to the length of the curve and give a detailed calculation formula. All trajectory parameters are derived with the analytical algorithm to ensure an acceptable computational complexity. Finally, a series of numerical simulations and actual machining and measurement experiments are conducted, and the simulation and experimental results have showed the good performance of the proposed algorithm compared with previous method both in motion smooth and surface quality. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the discharge gap on the arc characteristics of sheet tungsten electrode under vertical sidewall anode configuration is discussed. By changing the horizontal discharge gap and vertical discharge gap, the temperature distribution, current density distribution, flow field distribution, pressure distribution, and viscosity distribution of non-axisymmetric arc are calculated. From the point of view of the change of current density distribution caused by the change of discharge gap, the influence of Joule heat on the temperature distribution is analyzed, and the influence of cathode jet behavior on the arc temperature field is further analyzed. At the same time, the factors such as viscosity force and shear force above anode are also considered. At the same time, the experimental verification is carried out through the arc pressure and arc grayscale image. The importance of the discharge gap on the arc characteristics of sheet tungsten electrode under vertical sidewall anode configuration is emphasized. [ABSTRACT FROM AUTHOR]

Thermoforming is a complex process with numerous parameters that potentially have an influence on the wall thickness distribution of the end product. Test benches do not allow for measuring all potentially relevant influences. Numerical simulations therefore have proven to be a useful tool in order to obtain deeper insight into the process and the mutual interactions between the input parameters. Forming air impact thermoforming can be thought of as an extension to common negative thermoforming that takes advantage of the flow inside the pressure chamber to obtain a favorable deformation behavior, ultimately leading to an improved final wall thickness distribution. The purposeful interaction between flow field and plastic sheet implies a significantly more complex physical system when approaching the process with modeling techniques. This paper describes the setup of a structural simulation model for thermoforming, that in an approximative manner includes effects of the flow field within the pressure box on the deforming plastic sheet. Special focus is laid on the implementation of counter-pressure due to the air trapped between sheet and mold. Validation simulations presented yield satisfactory results and thus show the high potential of simulations in modeling the complex interactions occurring in forming air impact thermoforming. [ABSTRACT FROM AUTHOR]

Direct ink writing (DIW) is an extrusion-based additive manufacturing (AM) technique. One of the required factors for printing quality in DIW is to extrude continuous and tubular freeform extruded filaments (FEF) with diameters close to the nozzle inner diameter. This paper established a simulation model of FEF with volume of fluid (VOF) method and then evaluated the FEF based on the simulation results. First, ink properties including density, surface tension coefficient, and rheological properties were determined by properties tests. Then, the model of FEF was established using VOF simulation method with the software OpenFOAM and two evaluation indicators, mean diameter and stability, were proposed to evaluate the FEF. Two inks, a cellulose ink and a Nivea Crème, were used under three levels of piston velocity to verify the method universality for different inks and variable process parameters. The prediction accuracy of the established simulation model was verified as the relative error between simulation and experimental results of diameter was less than 10.22%. In this work, it was found that (1) piston velocity needed to be set higher than a minimum value to overcome yield stress and surface tension to successfully extrude filaments; (2) mean diameter of FEF decreased while stability of FEF decreased firstly and then increased as piston velocity increased. The proposed model and evaluation indicators gave an accurate and effective framework to analyze effect of the piston velocity on FEF, characterize the ink printability, and find suitable printable windows for process parameters in DIW. [ABSTRACT FROM AUTHOR]

Sheet-tube connection structures are widely applied in chemical, petroleum, medicine, and other industries. Its reliable connection and manufacturing are of great significance for the function of the corresponding equipment. To avoid the occurrence of too deep pits and easy warpage during the single-sided annular sheet squeezing process, an improved method to join sheets to tubes by double-sided annular sheet squeezing is proposed in this paper. The joining process is to squeeze the sheet through the top and bottom dies simultaneously, resulting in radial metal plastic flow, forming the interlock between the sheet and the tube. By experimental and numerical simulation, the joining process of Al6061-T6 sheet and tube under different process parameters using double- and single-sided annular sheet squeezing was conducted and compared. The pull-out test is used to evaluate the quality of sheet-tube joints. Results showed that using the double-sided annular sheet squeezing method can obtain a symmetrical interlocking structure rather than an asymmetric structure by single-sided squeezing, effectively reducing the pit depth on the sheet surface. In addition, the improved method can effectively reduce about 25% of the joining force, but the pull-out strength is about 1.5kN lower than that obtained by the single-sided squeezing method. The joining strength is comprehensively affected by the thickness of the die annulus, punch stroke, and squeezing type. The influence mechanism of process parameters on pull-out strength is discussed. This study provides a new and efficient joining way for the manufacture of sheet-tube connection structures. [ABSTRACT FROM AUTHOR]

To solve the problem that 7075 aluminum alloy tends to fracture during conventional forming processes, a novel forming method (electromagnetic hot forming) is introduced and investigated in this paper. The optimum mesh number (in the thickness direction) is obtained for loose-coupling method and sequential-coupling method. Then, both the loose-coupling method and the sequential-coupling method are compared with the hot forming process, and the dynamic sheet-deformation process is analyzed. With increasing temperature, the sheet forming height decreases before it increases. The simulation results, which are calculated using the sequential-coupling method, are consistent with the experimental results for four different temperatures. However, regardless of the forming temperature, either the sheet profile or the maximum forming height of the loose-coupling method differs significantly from the experimental results. [ABSTRACT FROM AUTHOR]

Springback, fracture, and cross-section distortion are common defects in stretch bending process of profiles. The crease defect of profiles is not obvious in the traditional stretch bending process. However, in the 3D flexible stretch bending of multi-point roller die process, due to the multi-point roller dies instead of the whole die, the forming process is more complex. Therefore, the crease can no longer be ignored. In this paper, the finite element model is established, and the effect of different process parameters on crease defect is discussed, and experiments are carried out with the forming equipment. The validity of numerical simulation is verified by experimental results. The results show that the crease defect becomes more obvious with the increase of the pre-stretching length, the post-stretching length, and the friction coefficient. The number of roller dies has a significant effect on the change of crease defect. However, the change of roller die radius has little effect on the crease defect. [ABSTRACT FROM AUTHOR]

In order to reduce fuel consumption and thus pollutant emissions, the automotive industry is increasingly developing lightweight construction concepts that are accompanied by an increasing usage of aluminum materials. Due to poor weldability of aluminum in combination with other materials, mechanical joining methods such as clinching were developed and established in series production. In order to predict the relevant characteristics of clinched joints and to ensure the reliability of the process, it is simulated numerically during product development processes. In this regard, the predictive accuracy of the simulated process highly depends on the implemented friction model. In particular, the frictional behavior between the sheet metals as well as between the sheet metal and clinching tools has a significant impact on the geometrical formation of the clinched joint. No testing methods exist that can sufficiently investigate the frictional behavior in sheet materials, especially under high interface pressures, different relative velocities, and long friction paths, while allowing a decoupled consideration of the test parameters. This paper describes the development of further testing concepts based on a proven tribo-torsion test method for determining friction coefficients between sheet metal materials for the simulation of clinching processes. For this purpose, the correlation of interface pressure and the relative velocity between aluminum and steel sheet material in clinching processes is investigated using numerical simulation. Based on these findings, the developed concepts focus on determining friction coefficients at interface pressures of the above materials, yield stress, as well as the reproduction of the occurring friction conditions between sheet metal materials and tool surfaces in clinching processes using tool substitutes. Furthermore, wear investigations between sheet metal material and tool surface were carried out in the friction tests with subsequent EDX analyses of the frictioned tool surfaces. The developed method also allows an optical deformation measurement of the sheet metal material specimen by means of digital image correlation (DIC). Based on a methodological approach, the test setups and the test systems used are explained, and the functionality of the concepts is proven by experimental tests using different sheet metal materials. [ABSTRACT FROM AUTHOR]

In-line stockers are the choice of automated material handling systems in many modern TFT-LCD (Thin Film Transistor-Liquid Crystal Display) bays. The performance of an in-line stocker depends much on the performance of its stacker cranes. In this paper, the aim is to study three stacker-crane control problems, i.e., task-determination, port-selection, and cassette-selection, which affect the performance of stacker cranes. This study represents a significant contribution to the field, providing new insights into these critical control problems. The purpose of task-determination problem is to determine whether the next task of a stacker crane is a port-clearing task or a cassette-pickup-and-delivery task. The port-selection problem will appear if the next task of the stacker crane is port-clearing. Its purpose is to determine which port the stacker crane should visit to perform port-clearing task. On the other hand, if the stacker crane’s next task is cassette-pickup-and-delivery, the cassette-selection problem will appear. In this problem, the stacker crane needs to determine which cassette it should pick up and deliver first. Rules with different control logics are proposed for each problem. To understand the performance of the proposed rules, computer simulations were conducted. Simulation results in three performance measures—throughput, the mean flow time of cassettes and the mean tardiness of cassettes—that reflect the need to assess both the efficiency and effectiveness of the in-line stocker system, as well as its ability to meet customer demands and deadlines were collected. The analysis of the results led to the identification of the best rules, longest starvation time rule and shortest distance from the cassette’s current position to its destination port rule, for each problem and the best combination of rules for achieving the best overall performance, resulting in a more effective and efficient solution for solving stacker-crane control problems. The research findings have practical implications for improving the efficiency and productivity of stacker cranes in various industrial settings. It is believed this knowledge can benefit TFT-LCD manufacturers in improving the performance of their in-line stockers and increase their competitiveness as a result. [ABSTRACT FROM AUTHOR]

This paper proposes a finite element model implemented in ANSYS using Lagrangian formulation to assess heat generation and friction dynamics of a friction stir welding process on AA2024-T3 aluminum plates. For that aim, the model is enriched by estimating a temperature-dependent friction coefficient using theoretical relationships, and by considering a temperature-dependent multilinear isotropic hardening equation as a plasticity model representing the material. Both quantitative determinations are confirmed through experimental data collected on the real material. Finally, the contact conditions are modeled using the modified Coulomb criterion. The results of the model are in agreement with actual results observed on experimental applications. The study proves that the rotational speed of the tool is the most determinant factor in the results. As it rises, the friction-generated heat flow is higher. This study shows that the compressive stress-strain data in strain rate of 10s−1 is a good approximation of the plasticity behavior of aluminum alloy during the friction stir welding. [ABSTRACT FROM AUTHOR]

Molybdenum is a newly added material in additive manufacturing material cabinet, and it is under the spotlight owing to its crucial applications. The high-energy electron beam selective melting (EBSM) process is supposed to be a promising technique for molybdenum printing because of its vacuum environment. This paper presents EBSM numerical process simulation for molybdenum on macro- and mesoscale established with exclusive powder material modeling. Experimentally determined, process parameters are implemented in 3D macro- and 2D mesoscale models for a profound process insight. Primarily molybdenum powder material model is established, and a multi-track FEM simulation is performed to predict melt pool configuration, temperature field and phase transformation. Next, powder consolidation mechanism, side surface roughness, porosity, and voids are investigated through a CFD model, where the molybdenum particles are explicitly considered from the EBSM process viewpoint. Results proved the effectiveness of the numerical simulation for detailed EBSM process understanding for molybdenum material. [ABSTRACT FROM AUTHOR]

Large ellipsoid parts are prone to wrinkle when forming by using traditional stamping. Aiming to solve the wrinkling problem in large parts, the EMIF method with a variable blank holder is proposed in this paper. The numerical simulation has shown that the sheet material near the blank holder is, as a consequence of stamping, subjected to circumferential compressive stress. When the drawing height was 100 mm, the sheet metal was notably wrinkled. In the electromagnetic forming (EMF) process, the sheet region facing the coil becomes thinner. However, the sheet metal thickness corresponding to the coil edge increases with the increase in forming height. If the EMF forming height is 150 mm, the sheet, which is in contact with the smooth mold, is deformed without a wrinkle. Compared to traditional stamping, the EMF can significantly reduce the sheet metal wrinkling, improving the deformation height of the sheet metal smooth area. [ABSTRACT FROM AUTHOR]

Flexible skew rolling (FSR) with two rollers is a new technology for forming large shaft parts, which is especially suitable for manufacturing the shafts with small-batch and multi-variety. Hollow shaft parts can achieve lightweight forming of parts under the premise of meeting strength. In this paper, an exploratory study of the hollow shaft in FSR of 40Cr steel has been conducted for estimating the technological potential of FSR. The effects of the hot rolling main parameters (roll swing angle, compression ratio, initial wall thickness, and mandrel diameter) on forming quality have been investigated by means of finite element (FE) analysis and experiments. The data gained from the experimental tests conducted on the FSR mill was used to validate the model and the research results. The forming characteristics and forming precision of this process were investigated, and the microstructure of outer and inner surfaces of the hollow shaft was observed. The dimensional accuracy of the FSR hollow shaft decreases with the increase of the compression ratio, the relative mandrel diameter, the swing angle, and increases with the increase of the relative wall thickness. The microstructure near outer surface of the FSR hollow shaft is the first to be refined, the grain size of the inner wall is larger than the grain size of the outer wall and the mechanical properties of the rolled piece are significantly enhanced. [ABSTRACT FROM AUTHOR]

The forming limitation and the wall thickness distributions are the two main parameters for estimating the forming quality of T-shaped tubes. In this paper, the effects of three key factors on the forming limitation and the wall thickness distributions are investigated, which are punch front distance l1, reverse height h1, and the matching relationship between rubber hardness and axial feed Δl. A new position-limited backpressure mechanism is proposed, which is made up of the rigid position-limited lever, the flexible backpressure medium, and the rigid spacer. The simulations and experiments are carried out. Both results show that the thinning rate of the wall thickness decreases first and then increases, and the thickening rate decreases gradually with the increase of l1. The branch reaches the highest with the l1 of 5mm under the requirements of thinning rate and thickening rate. With the rise of reverse height h1, the bigger h1 is beneficial to the wall thickness thinning suppress at the top of the branch, and the branch reached the highest when h1 is 7mm. When Δl is fixed, the rubber hardness has a significant influence on the forming defects. The exorbitant rubber hardness causes the branch to rupture, and the excessive axial feed causes the wall to wrinkle. When rubber hardness is fixed, the thickening rate decreases with the increase of Δl. The best forming limitation and thickness distribution are achieved with the punch front distance l1 of 5mm, the reverse height h1 of 7mm, the rubber hardness of 75HA, and the axial feed Δl of 24mm. [ABSTRACT FROM AUTHOR]

In this paper, the method of limit analysis is adopted, and three kinds of self-bending extrusion dies controlled by combined function are presented. They are the sin-atan self-bending extrusion die, the sin-erf self-bending extrusion die, and the sin-tanh self-bending extrusion die. Through numerical simulation, self-bending profiles can be obtained from all three kinds of dies. These dies can make the billet flow closer to the real billet flow path and maximize the billet utilization rate. They also can reduce the extrusion load and reduce the local damage of the die and then prolong the die life. It is very effective to predict the bending deformation of the billet by analyzing the central flow line of the billet. It provides a theoretical reference for the design of the actual streamlined self-bending die. [ABSTRACT FROM AUTHOR]

The annular coaxial nozzle has good convergence and is widely used in laser melting deposition (LMD). In this paper, a new-type annular coaxial nozzle is developed, which can transform four-channel powder flow into annular distribution through the internal channel to obtain a more uniform distribution of powder in the circumferential direction. A three-dimensional computational fluid dynamics (CFD) numerical model is established. The dynamic behavior of Fe-based powder is described by discrete phase model (DPM). The influence of gas on powder particles is described by two-way turbulence coupling model. The convergence and transport characteristics of the nozzle are revealed. The accuracy of CFD model is verified by powder feeding experiment, and the deposition performance of powder nozzle is verified by single-track deposition experiment. The results show that the nozzle can provide stable powder feeding and excellent convergence characteristics. The powder flow is converged in a "Y" shape on the longitudinal section. The higher the powder concentration at the focal plane of the nozzle, the smaller the aspect ratio of single-track coating. The powder utilization rate of the nozzle can reach 76.97%. [ABSTRACT FROM AUTHOR]

This paper presents a new forming technology for manufacturing the AZ31 magnesium alloy thin-wall tube. The direct extrusion process and continuous shearing-bending process are combined to produce thin-wall magnesium tube, abbreviated as "TESB" (tube extrusion-shearing-bending). The process has been studied based on the combination of experiments and numerical simulations, and the influences of temperatures, extrusion stresses, and friction factors on the forming process have been studied by Deform-3D simulation. And the mechanical properties and the grain size of the formed product have been tested. TESB technology has been proved to refine the grains of magnesium alloy tube effectively, and the mechanical property of the product can be improved. The better experimental extrusion conditions were also obtained by simulation, and the properties of the products under the condition of lubrication were better when the temperature was 400°C. Three-dimensional finite element modeling is used to investigate the plastic deformation behaviors of wrought magnesium alloy during TESB process. Numerical results indicate TES could increase the cumulative strains effectively by direct extrusion and additional shearings. Experiments show that microstructures of magnesium alloy fabricated by TESB process can be refined to 50% of the original grain size with more uniform distribution. TES process could improve hardness of magnesium alloy obviously by comparing with which fabricated by direct extrusion. [ABSTRACT FROM AUTHOR]

Rubber pad pressing is one of advanced materials processing technologies. With the cooperation of both rubber pad and metal mold, the plate is accurately formed into the required shape. Not only the surface of the plate remains a good quality but also the springback is substantially reduced. In this paper, a new kind of two-step channel formed by the rubber pad pressing is researched. Both convex and concave metal molds are considered in the researches. All kinds of geometrical parameters like channel width, edge fillet, depth ratio, and second-step shape are discussed in this paper. In order to obtain a good two-step channel by rubber pad pressing, both FEM and real pressing experiments are done. Based on both FEM and experiment results, channel can be formed by rubber pad pressing with both convex and concave molds. The plate formed by convex mold can be better than that formed by the concave one. [ABSTRACT FROM AUTHOR]

Laser surface texturing and through-mask electrochemical micromachining (TMECMM) are some of the commonly used methods which include multiple steps to achieve micro-textures. However, for large-area applications, it is desirable to have an economical single-step process. In this regard, ECMM is expected to be a promising and economically viable micro-texturing process for micro-manufacturing industries. This paper proposes a novel maskless EC micro-texturing process using tool sinking technique with low voltage and short pulses. Methodology of using edges (∼30 μm each) of printed circuit boards (PCBs) for ECMM of micro-channels and micro-pillars is a unique one. Micro-pillars, micro-dimples and micro-channels are produced through a direct electrochemical cathode sinking process. Analysis of current density and prediction of width and depth of micro-dimples on a flat stainless steel surface are studied through 2D numerical simulation carried out on COMSOL 4.3a. The proposed method implies the use of less toxic electrolyte, low voltage (1-6 V), short pulses (5 to 50 μs) and selective polymer coating on the tool (cathode). A series of experiments of EC sinking for creating various micro-patterns and micro-structures has been carried out on the flat as well as curved metallic surfaces. This paper reports machining of micro-dimples of 200-300 μm diameter, micro-channels of 150-250 μm and square micro-pillars of 300-350 μm. Comparison of the predicted geometrical dimensions of the micro-dimples through the simulation shows reasonable agreement with the experimental results for the given process parameters of ECMM. The paper also reports a brief comparison of laser surface texturing (LSTex) and electrochemical surface texturing (ECSTex). [ABSTRACT FROM AUTHOR]

Integral impeller is a complex part commonly used in petroleum, chemical, shipbuilding, aerospace, and other industries. The manufacturing of the integral impeller involves the multi-axis machining of free-form surface, which is a time-consuming and error-prone process. Tool path planning is regarded as a key issue in this process, but there is still short of systematic solutions. In this paper, a parametric domain template trajectory mapping algorithm is presented to calculate the tool path of impeller channel machining. Through generating the template trajectory in the parametric domain, and mapping the template trajectory to the physical domain with the aid of the mapping model, and then the actual machining tool path can be obtained. The proposed method can realize the rapid acquisition and easy modification of the impeller machining tool path. Firstly, the trajectory mapping model from the parametric domain to the physical domain is established using the morphing technique, and the template trajectory mapping method in the parametric domain is given. Secondly, the clean-up boundary of the impeller channel is determined in the parametric domain, and the quasi-triangular and streamlined template trajectory of the impeller channel is defined. Finally, the template trajectory given in the parametric domain is mapped to the physical domain through the mapping model, and the streamlined and quasi-triangular tool paths of the impeller channel are calculated. An example analysis shows that the calculation difficulty of the tool path for impeller channel machining is greatly decreased, and the calculation efficiency is also improved. The simulation and actual machining are carried out. The result shows that the tool path generation method presented in this paper is effective and feasible, and it offers a new way for tool path planning of NC machining for impeller complex parts. [ABSTRACT FROM AUTHOR]

At present, many studies have shown that crosshatch micro structures can effectively improve surface performance. This paper presents a method for manufacturing micro structure based on ultrasonic-assisted grinding (UAG) and ordered grinding wheel. Firstly, the parameters of ordered grinding wheel and the surface characteristic parameters in relation to working performance are proposed. According to the kinematics of grinding, the governing equation between the surface characteristic parameters and the machining parameters is established. Based on the proposed characteristic parameters, the pattern parameters and machining parameters are inversely solved by the governing equation. The crosshatch micro structure manufacturing based on ordered grinding wheel and ultrasonic-assisted grinding is achieved, and because the fabrication technology of the grinding wheel is not mature, its correctness and feasibility are preliminary verified by the numerical simulation method and grinding experiment. The paper method is original for the active manufacturing of the crosshatch micro structure and is of reference value for the micro structure active manufacturing. [ABSTRACT FROM AUTHOR]

When the deviation between the actual pipelines and the ideal models cannot be neglected, the intersecting curve weld seam based on non-ideal models should be specially studied. This paper will introduce a novel method to quantify the deviation of the intersecting curve weld seam based on the non-ideal models. Weld location is a technical means for obtaining the actual position of weld seam, which may be used to obtain the location information of some key points on the intersecting curve. Combined with the information of weld location and the inherent characteristics of the intersecting curves, this paper analyzes the experimental results of actual intersecting curve welding, and all these works laid the foundation for the proposed algorithm. First of all, on the basis of previous studies, this paper introduces a kind of model for intersecting pipelines, which can cover most of the ways of coherence. Secondly, based on this model, the factors which may lead to the deviation of the theoretical intersecting curve from the actual intersecting curve are analyzed. Generally, there may be some connections or coupling between the sources of deviation. Against the above problem, the paper gives a solution to model each source of deviation and discuss the relationship among them, and then makes use of the information of weld location to quantify the main sources of deviation one by one, especially the quantification of the main pipes ovality. Finally, the correctness and flexibility of the algorithm are verified by the MATLAB simulation. [ABSTRACT FROM AUTHOR]

With the increasing demand for parts with large sizes and complex cross-sectional shapes, the required target shapes are increasingly difficult to meet. In this paper, a flexible 3D stretch bending device has been developed, which can form complex cross-sectional 3D parts with 2 degrees of freedom at one time and can form large sizes 3D parts. Compared with traditional monolithic molds, discrete molds using in flexible 3D stretch bending forming are more convenient for shape adjustment of target profile. The multi-point roller dies are composed of multiple different roller-type die units. In order to better evaluate the forming accuracy of 3D parts, the influence of the number, shape, and surface of the roller dies on the forming results is discussed. The influence of different parameters on the forming accuracy is studied by numerical simulation, and the results are compared with the experimental results. From the perspective of forming accuracy, the influence of FSBR process and different parameters on the forming result is analyzed. Analysis of the dimple and shape errors of the FSBR parts shows that the number, shape, and surface of RDU directly affect the forming accuracy. By modifying the die parameters, the surface dimples can be reduced and the forming accuracy can be improved. [ABSTRACT FROM AUTHOR]

Springback compensation is considered as the best method to reduce springback error. In view of the springback defect of 3D deformed workpiece, a springback compensation method based on variable compensation factor is proposed. This method can accelerate the convergence speed of iterative compensation. In this paper, the 3D flexible stretch bending of multi-point roller die technology (3D FSB-MPRD) is introduced firstly, and then, the principle of the springback compensation method based on variable compensation factor is explained. In order to improve the springback compensation accuracy of workpiece, the total springback compensation process is divided into horizontal bending springback compensation and vertical bending springback compensation. Taking the T-shaped profile with variable curvature as the research object, the die surface is optimized and the optimal springback compensation factor is obtained by using numerical simulation after multiple iterations. Finally, the results of springback compensation are compared with the desired shape. And the effectiveness of the springback compensation method based on variable compensation factor is verified by comparing the simulation results with the test results. [ABSTRACT FROM AUTHOR]

In the shipbuilding industry, the traditional manufacturing method for the complicated ship hull metal plates is line heating method, which is not only labor intensive but also inefficient. Considerable efforts have been taken to develop the new automated manufacturing processes at a reasonable quality, efficiency and price during the last few decades. This paper presents a novel flexible forming process called incremental bending to achieve complicated plates. In this method, the initial metal plate is supported by some rotatable hydraulic cylinders and the punches move according to the given path, which is decided by minimum energy method and springback compensation method, to achieve the final plate. Taking one variable curved metal plate as one example, this paper investigates the formability of this novel process based on experiment and numerical simulation. During the numerical simulation, the implicit method is used and the gravity of the plate is considered mainly for the automatic positioning of the plate during each springback process. Results show that the incremental bending process can achieve variable curved metal plates with good accuracy, high efficiency, and relatively small punch load. In comparison with the existing methods, the new process has greater potentiality in the ship hull manufacturing industry. [ABSTRACT FROM AUTHOR]

This paper proposes a new fault tolerant control strategy for a five-phase permanent magnet synchronous motor (PMSM) drive under single-phase open circuit condition. The loss of one phase causes problems such as disturbing rotating magneto-motive force (MMF) and generating undesirable torque pulsations. The development of suitable control strategy is a required task in order to ensure disturbance-free operation during post-fault operation. This paper proposes a new control technique for a five-phase PMSM based on adaptive sliding mode control (ASMC) in post-fault under the loss of one stator phase. The proposed method is compared to fault tolerant control strategy based on proportional resonant (PR) controller. The two control strategies are different from theoretical viewpoint proving their abilities to overcome the fault situation with favorable dynamic performance and faster control response of ASMC compared with PR controller. Depicted set of numerical simulation results always shows a close conformity with the developed theoretical background. [ABSTRACT FROM AUTHOR]

In this paper, we discuss about multiple coordinated robots that can form a fixtureless manufacturing cell. It is very important to ensure that the system stiffness is sufficient for manufacturing operations when external forces are exerted on the system. For this reason, a method is developed to model and analyze the stiffness of a multiple coordinated robot system. In this paper, first, the stiffness of a multiple coordinated robot system is defined. Similar to a single-arm robot, this definition provides us with a criterion to evaluate the stiffness performance of the entire multiple robot system. Second, a static stiffness model is derived including joint stiffness and link stiffness, and then this model is extended to a multiple robot system. Third, the coordinated static stiffness model is validated, and a comparison is made through simulation between a dual robot system and a single robot system. Finally, the developed model is applied to a real coordinated dual-arm robot system for validation. [ABSTRACT FROM AUTHOR]

The paper discusses the problems of forming parts such as stepped shafts by cross wedge rolling (CWR). In industrial practice, this rolling process is performed at stages, i.e., in several passes, when large cross-sectional reductions are involved. The same can also be done using a different design of this forming process, namely, multi-wedge cross rolling (MWCR), in which the workpiece is simultaneously formed by several pairs of tools (wedges). This paper compares the above two methods with respect to forming a drive shaft. Wedge tools used in both forming processes are described, and the numerical results of the simulations performed to verify the adopted solutions are reported. The results demonstrate that theMWCR method offers more advantages than the classical CWR technique. Consequently, MWCR is then verified in experimental tests. The experimental results confirm that parts such as stepped shafts can be formed by the MWCR method. [ABSTRACT FROM AUTHOR]