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In the face of global warming, sustainability has become a hot topic. Sustainable manufacturing aims to analyze and improve industrial processes to mitigate their negative impact on the environment in terms of energy use and greenhouse gas emissions. In terms of sheet metal forming, and especially in incremental forming processes, it is important to study how to manipulate parameters in a way that reduces energy consumption and CO2 emissions without degrading the quality of the final product. These impacts can be controlled by the manipulation of process parameters such as: rotational speed of the tool, radial displacement, and axial advance per pass. The main objective in this study is to determine energy savings and reduce CO2 emissions caused during the forming processes. The present work shows the experimental analysis for a steel sheet (ASTM A653), subjected to a conventional forming process through a simulation that reproduces the process conditions, providing the consequent energy consumption. Additionally, the single-point incremental shaping process is experimentally developed using current- and load- sensors that record the energy consumption of the process in real-time. The results obtained clearly determine the nature of the analyzed processes in a way that reduces energy consumption and CO2 emissions, which in turn improves the process in terms of overall sustainability.

The 3D printing thixo-forming process is a method that utilizes semisolid thixotropic feedstock for layer extrusion by controlling feedstock viscosity below the complete melting temperature of metallic alloys to form a 3D structure. The process of producing metallic feedstock has a significant impact on alloy microstructure, which is critical for the material’s printability. This study aims to propose a semisolid heat treatment processing window of Pb-40% Sn alloy for use as feedstock billets for a variety of extruder nozzles (sizes 1–3 mm) during the 3D printing thixo-forming process. Firstly, Pb-40% Sn alloys were cold deformed to reduce the specimens’ diameters. Semisolid treatments for deformed specimens were performed at a variety of semisolid heating temperatures and three separate holding times (2, 5, and 10 min). The microstructure of semisolid feedstock specimens was then investigated. The temperature and time of the semisolid heating processing window of Pb- 40% Sn alloy were optimized to feedstock specimens and thixo-extruding processes with different printed output sizes. Therefore, the proposed semisolid heat treatment processing window was a promising approach to pave the way for the low-cost manufacturing of AM, which yields higher printing rates and improved scalability of printed lines. Additionally, this approach allows for a versatile manufacturing route for producing 3D metal parts with maximum density and intricate geometries as a result of the ability to tailor the microstructure.

Superplastic Forming (SPF) is the designers first choice for producing the products that have complexity as used in automobiles and aircrafts, in which the ratio of strength to weight is the major concern. SPF of sheet widely used in the manufacture of the products with more significant complexities simultaneously lighter and stronger than with any other manufacturing process. Superplastic formed products having shapes like hemispherical, conical and box results significant variation in thickness. Lowest thickness will be at the locations where the sheet contacts the die at the last. Complexity of the product, forming depth, and pressure affect the thinning. Unmitigated understanding of stress, strain rates, and strains during the forming process and the use of suitable pressures for forming can reduce this problem. In this study Lead & Tin alloy has chosen, as an exemplar material for Superplastic forming to carry out investigations. The results obtained can be applied for any other superplastic materials. The present investigation focused on studying suitable strain rates and Normalized Thickness Variation during the superplastic cone forming. Results revealed that Normalized Thickness Variation (NTV) is lower i.e., 2.27 when formed at the pressure of 3 bar, which provides an equivalent strain rate of 1.1 × 10−4 s−1. Therefore 3 bar pressure is desirable for cone forming. Results also disclosed that strain rates obtained in this investigation are in the limits of superplastic forming zone and hence no fracture happened on the conical dome due to the thinning.

Reasonable laser process parameters and heating paths are crucial in laser forming (LF) technology. Obtaining the proper laser processing parameters and the heating path is the decisive factor to determine the forming efficiency and precision of the complex 3D surfaces with double curvature. First, the 3D target surfaces with double curvature were developed in this paper to flat plates through the finite element numerical simulation tool, and the magnitude and direction of in-plane and bending strains were obtained; the direction perpendicular to the principal strain is the direction of the heating paths. Second, the database of laser process parameters and principal strains was established to determine the proper laser process parameters. Finally, combined with the above laser parameters and heating paths, the “pillow” and “spherical” surfaces were obtained, and the accuracy of this method was verified by experiments.

The superplastic forming process has been used extensively in aerospace applications for its advantages in manufacture of complicated components. But it has been limited to the long production cycle and the non-uniform thickness distribution of the final formed part. The two-stage SPF process in opposite directions for 5083 aluminum alloy door frames was investigated. A finite element model in PAMSTAMP was used to simulate the forming process. Analyzed the effect of pre-forming die parameters on the minimum thickness of the final formed part by the Response Surface Methodology and optimized the pre-forming die parameters. Moreover, the influence of different rated pressure on the forming quality and forming time of the door frames under the same strain rate were investigated to determine the ideal pressure profile. The result was that the minimum thickness meets the requirements (thinning not exceeding 40%) while reducing the production cycle. Finally, the two-stage superplastic forming experiment in opposite directions was conducted to verify the accuracy of the numerical simulation and produce the door frames with high quality.

Due to the poor formability of zirconium alloy, crack is one of its most common failure modes when the alloy is used for strips of spacer grids of nuclear fuel assembly during the sheet forming process. In this paper, the relationships between processing parameters (including punching speed, stamping clearance and blank-holder force (BHF)) and the crack risk of sheet forming process are discussed. A continuous forecasting model is constructed by using support vector machine regression (SVR) method. The maximum thinning ratio (TMTR), which is usually used as an index to quantitatively evaluate the crack risks during sheet forming, serves as the output while the processing parameters as the input variables of the forecasting model. The performances of the SVR model are assessed by six different regression metrics and results are compared with five other machine learning models. The evaluation results demonstrate that the SVR model has the best performance (with a relative mean error of 2.76% and the value of R 2 0.939) and the capacity to accurately predict the maximum thinning ratio of the sheet forming process of zirconium alloys. The coupled and interactive effects of the processing parameters on the sheet forming are also analyzed through the results of the forecasting model.

Electromagnetic forming (EMF) is a type of noncontact and high-speed forming process that offers several advantages, such as high material formability, low springback, and low die cost. In this study, titanium bipolar plates (BPPs) for proton exchange membrane fuel cells are fabricated by EMF using a uniform pressure actuator that provided a uniform pressure distribution and high efficiency. A three-dimensional coupled electromagnetic-mechanical simulation model is established to optimize the dynamic forming process. Simulation results show that the channel depth is proportional to the impact velocity of the titanium workpiece. A forming window is established as a design guideline. Finally, a titanium BPP with sufficient channel depth (0.4 mm), high aspect ratio (0.67), low thinning rate (not exceeding 15.89%) and high corrosion resistance is successfully fabricated at a velocity of 286 m/s, thereby demonstrating that EMF is a feasible process for fabricating titanium BPPs.

Fresnel lenses are important compact optical components, which are comprised of multiple faceted concentric rings. These lenses are the most widely utilized diffractive optical element in the industry and has been extensively applied in various optical systems due to their distinct advantages. These include the reduction in the lens thickness, smaller occupied volume and less material required compared to their conventional spherical and aspherical counterparts. In general, the processes to manufacture Fresnel lenses can be categorized into two distinct groups: subtractive fabrication and precision forming. Precision forming processes, like molding and embossing, are usually used in mass production to replicate the optical features and profiles usually employ the use of lens molds generated by subtractive fabrication processes. Thus, the process of molding Fresnel lenses are not substantially different from that of conventional molding processes for other optical components, still relying on the accuracies of the molds utilized. Unfortunately, there is a lack of a comprehensive study to summarize and evaluate the recent advances of UPM techniques to generate these optical Fresnel lens structures. Fresnel lenses and molds differ from each other in terms of lens design, work material and tool/workpiece geometries, and such variations will then drive the development of different machining and characterization methods in terms of tool setting, tool wear, tool path generation as well as lens measurement. This paper summarizes the existing fabrication techniques to generate these lens structures, excluding molding. In addition, a discussion and analysis of the strengths and future areas of research interest of the reviewed techniques are conducted. This review is believed to be helpful and educational for the progress and further development of machining of ultra-precision Fresnel lens structures for advanced optical applications.

Considering the fact that the most of the human equipment developed by forming processes, one of the methods of producing these materials is through the metal forming process. In Industrial process, prediction of the final dimension of the part after unloading is an essential problem. Thickness distribution is the geometric change made to a part at the end of the forming process when the part has been released from the forces of the forming tool. In this study, the effects of grain size and sheet thickness on the formability of annealed copper sheets in the deep drawing process were studied. To this end, the effect of friction coefficient was evaluated for a total of 64 different cases by the finite element method (FEM). The effect of optimal parameters and grain size on the maximum deep drawing height (DDH) and thickness distribution of the square part was investigated. According to the literature review, punch and die radii uses were spotted. Based on the simulation software, the best thickness distribution was obtained in no-friction force between tools. According to the experimental results, as the grain size increased from 33 to 161 μm and from 25 to 158 μm, the thickness of wall and bottom specimens was increased, and the corner was decreased.

Cladding tube is an important part of nuclear power components. This paper presents a simulation and experimental study on the cold drawing process of one kind of cladding tubes, namely thin-walled ribbed steel tube. Three kinds of drawing processes are studied: single pass drawing, tube sinking and fixed-plug combined drawing process, and two pass fixed-plug drawing process. The finite element (FE) simulation model considering Johnson-Cook constitutive equation is established to analyze the effective stress, effective plastic strain, and contact force in different drawing processes. Different out diameter (OD) and wall thickness (WT) 316L stainless steel (SS) tubes are used to investigate the forming process of the ribbed tube. Furthermore, experiments with the same parameter settings are compared with the simulations. It is found that the simulation and experimental results are in good agreement, the ribs height highly depends on the tube OD and WT. The results show that the formation of tube ribs is caused by the extrusion of the drawing die. In addition, during the forming of the tube ribs, inner grooves will be formed on the inner wall of tube, and the fixed-plug drawing process can effectively reduce the depth of the inner groove. Finally, the microstructure and hardness of the ribbed tube at different position are investigated. This work provides a reference for the integrated forming process of the ribbed tube.

In this work, the development of a hybrid lightweight automotive chassis control arm is demonstrated. It includes the development of a new simulation method for designing metal — LFT (long fiber-reinforced thermoplastics) rehybrid parts and the new hybrid forming method for its manufacture. Beginning with the original geometry of a series steel chassis control arm, the design was optimized for the hybrid forming process where a steel sheet part is reinforced by an LFT rib structure, and both parts are joined by an LFT layer. For this purpose, a new FE optimization process chain was established. The thickness of the sheet metal and LFT layers, the geometry and thickness of the ribs of the hybrid control arm could be determined to meet both mechanical and light weight requirements. Afterwards, a suitable tooling concept and process for the hybrid forming were developed and tested. The forming behavior of two different steel grades along with an LFT was demonstrated and analyzed with the help of 3D measurement techniques and relevant section cuts. Finally, a weight reduction of nearly 20 % compared to the original component was realized with the hybrid forming process.

Press-brake bending is one of the important sheet metal forming processes widely used to fabricate different angles and channels in automotive applications. Plastic deformation of material during bending generates elastic stress waves known as acoustic emission (AE), enabling online monitoring of the bending process. The analysis of these stress waves helps in process characterization and aids in the identification of defects. The non-homogeneous plastic deformation that occurs during bending leads to the development of residual stress (RS) in the bend regions after forming. The locked-in residual stresses that remain after bending are measured using the x-ray diffraction method. The present study aims to use the AE technique for online bend monitoring of austenitic stainless steel (SS) of type 304L and correlate the AE parameters acquired during bending with the final locked-in RS present in the bend regions. Toward this, SS 304L sheets were bent to various bend angles, viz. 45°, 60°, 90°, 108°, 120°, and 135°, along the rolling direction and perpendicular to the rolling direction. Among the many AE parameters derived from the analysis of AE signals, it is shown that normalized cumulative counts and energy increase with bend angle. The increase in AE is well correlated with the RS that develops due to plastic deformation. The observed correlations between AE parameters acquired during bending and RS measured after bending are discussed.

Purpose The purpose of this paper is to study the wire and arc additive manufacturing (WAAM) method and path planning algorithm of truss structure parts, to realize the collision-free rapid prototyping of truss structures with complex characteristics. Design/methodology/approach First, a point-by-point stacking strategy is proposed based on the spot-welding mode of cold metal transfer welding technology. A force analysis model of the droplet is established, which can be used to adjust the posture of the welding torch and solve the collapse problem in the WAAM process of the truss structure. The collision detection model is developed to calculate the interference size between the truss structure and the welding torch, which is used to control the offset of the welding torch. Finally, the ant colony algorithm has been used to optimize the moving path of welding torch between truss with considering the algorithm efficiency and collision avoiding and the efficiency of the algorithm is improved by discretizing the three-dimensional workspace. Findings A series of experiments were conducted to prove the validity of the proposed methods. The results show that the wire feeding speed, welding speed are the important parameters for controlling the WAAM process of truss parts. The inclination angle of the welding torch has an important influence on the forming quality of the truss. Originality/value The force analysis model of truss structure in the WAAM process is established to ensure the forming quality and a collision-free path planning algorithm is proposed to improve forming efficiency.

Heat-assisted rotary draw bending (HRDB) is a promising technique for manufacturing difficult-to-form tubular components comprising high-strength titanium tubes (HSTTs) with small bending radii. However, as a multidie constrained and thermomechanical coupled process with many uncertainty factors, a high risk of several defects, such as cross-section distortion, over wall thinning, or even cracking, is present. Achieving the robust design optimization (RDO) of complex forming processes remains a nontrivial and challenging scientific issue. Herein, considering a high-strength Ti-3Al-2.5V titanium alloy tube as a case material, the five significant uncertainty factors in HRDB, i.e., temperature distribution, tube geometrical characteristics, tube material parameters, tube/tool friction, and boost velocity had been analyzed. Subsequently, considering the preheating and HRDB of HSTT, a whole-process thermomechanical three-dimensional finite element model was established and validated for virtual experiments. Further, considering the maximum section distortion Q and maximum wall-thickness thinning t as the optimization objectives and the mean and variance of material and forming parameters, an RDO model was established. Finally, the Pareto optimal solutions were obtained using the nondominated sorting genetic algorithm II, and a minimum distance selection method was employed to obtain the satisfactory solution. Results show that the optimized solutions considering the uncertainty factors reduce the maximum section distortion rate of HSTT after bending by 38.1% and the maximum wall-thickness thinning rate by 27.8%.

To avoid degradation of material properties, high equipment investment, low efficiency, and potential safety issues caused by conventional technologies like line heating, multi-point plate forming, and explosive forming, a new die-less single-tool multi-point plate forming (DS-MPF) technology is proposed. In DS-MPF, a moving bar is used as a single forming tool and combined with horizontal and vertical motions relative to the plate. To reduce forming force component from the membrane stress, simple support boundary condition is preferred to avoid the plate edge being bent, trimmed, or thinning after being formed. However, this boundary may easily cause instability of the forming process and worse geometric accuracy of a formed part if an unsuitable toolpath is employed. In this paper, the forming mechanism and toolpath design principle are clarified to develop this new technology. Numerical and experimental forming case from an 8-mm SS400 steel plate into a spherical surface with a radius of curvature of 1000 mm was performed to validate the new technology and its design principle. The strain analysis of results shows DS-MPF tends to be a local forming method. The formed plate normally has local positive bending strain at the tool-contacted area and limited negative bending strain at the tool-uncontacted area between adjacent strokes. Forming a 3D curved shape with high geometric accuracy in DS-MPF can be achieved with appropriate control of the local bending strain produced in each stroke, stroke position, and forming sequence.

Thin-walled tubes are widely used as energy absorbers due to their high crashworthiness performance. This study aims to evaluate the effect of plastic forming history carried out for thickness optimization on crashworthiness performance of thin-walled square tube (TWST). Within the scope of the study, a series of numerical analyses were conducted for the TWST using a commercial finite element (FE) software. In order to determine individual effect of optimization, FG thickness of TWST was first obtained using LS-OPT software. Later, thickness gradient was achieved by performing rolling process to consider individual plastic forming effect Afterwards, deep drawing process was carried out to shape TWST by considering springback and trimming effects. Finally, crash responses were obtained under axial high velocity impact loading to determine the coupled effect of optimization and plastic forming on the crashworthiness performance of the TWST. It was determined that the coupled effect, which takes plastic forming and optimization effects into account, reduced the peak crush force of the TWST by 24% and increased the absorbed energy value by 39%. The results obtained from this study showed that coupled effect of optimization and plastic forming processes has significant effect on the crashworthiness performance of the TWST and otherwise either overestimated or underestimated results are obtained.

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

Bimetal sheets are prominently expanded in industries due to their unique properties including high strength, low density, and corrosion resistance compared to single-layer sheets. On the other hand, incremental forming is found to be one of the most suitable methods to form complex parts. In this regard, a numerical and experimental study was conducted to consider the behavior of explosively welded aluminum–copper sheets. A nonlinear explicit solver was employed to simulate the incremental collar forming process. Experimental tests were performed to validate thickness variation, dimension and tool average force. A coupled artificial neural network and finite element method are utilized to generate an objective function of thickness reduction. The new metaheuristic whale optimization algorithm using a trained neural network (ANN–WOA) is utilized to improve sheet thickness distribution by finding optimum parameters. The developed artificial neural network could reliably predict thickness reduction in Al/Cu bimetal sheet during incremental collar forming while minimum thickness reduction occurs in the circular area of obround shape with less than 4% deviation from ANN results. It is also shown that optimum incremental forming parameters of obround shapes with length to diameter ratio between 2 and 3 are very close.

The state-of-the-art non-isothermal Hot Forming and cold die Quenching (HFQ®) process can enable the cost-effective production of complex shaped, high strength aluminium alloy panel components. However, the unfamiliarity of designing for the new process prevents its widescale adoption in industrial settings. Recent research efforts focus on the development of advanced material models for finite element simulations, used to assess the feasibility of new component designs for the HFQ process. Though useful, FE simulations take place late in design processes, require forming process expertise and are unsuitable for early-stage design explorations. To address these limitations, this study presents a novel application of a Convolutional Neural Network (CNN) based surrogate as a means of rapid manufacturing feasibility assessment for components to be formed using the HFQ process. A diverse dataset containing variations in component geometry, blank shapes, and processing parameters, together with corresponding physical fields is generated and used to train the model. The results show that near indistinguishable full field predictions are obtained in real time from the model when compared with HFQ simulations. This technique provides an invaluable tool to aid component design and decision making at the onset of a design process for complex-shaped components formed under HFQ conditions.

The free bending forming (FBF) technology is a new die-less forming process suitable for bending complex-shaped thin-walled tubes with several bending radii. A new theoretical model of convoluted spiral tubes manufactured through FBF technology is proposed in this investigation for revealing and understanding the parameters of manufacturing the spiral tubes using FBF technology. After that, finite element modelling and experimentation were performed to verify the accuracy and reliability of the proposed theoretical model. The max error determined by comparing the experimental results with those acquired from the theoretical analysis is less than 7%. This verifies the reliability and the accuracy of the new theoretical analysis. Afterwards, the forming limit of a convolute spiral tube manufacturing by FBF technology is explored. It is realized that the spiral diameter (D) was affected by distance A which is the distance between the front end of the guide mechanism and the centre of bending die in Z direction; and eccentricity (U). In addition, it is detected that D is directly proportional with distance A and inversely proportional with distance U, where D increased by increasing distance A and decreasing U.

Electromagnetic forming is a high-speed forming process, and it can generate high contact force between the sheet metal and die. Therefore, the effects of die counter-impact on aluminum alloy sheet during electromagnetic forming were numerically and experimentally investigated. Firstly, the numerical simulations of electromagnetic free forming and electromagnetic die forming were performed with the Gurson-Tvergaard-Needleman damage model. When the aluminum alloy sheet impacted the die, an unignorable normal stress occurred along the thickness direction. The void volume fraction was reduced due to the negative stress triaxiality, and the residual stress became smaller. Secondly, the effect of die counter-impact on the pre-deformed aluminum alloy sheet was numerically inspected for quasi-static and dynamic hybrid electromagnetic forming. Compared with the electromagnetic die forming of aluminum alloy sheet without pre-deformation, the void volume fraction and residual stress reductions were more significant for the pre-deformed aluminum alloy sheet. Finally, the aluminum alloy sheets after different electromagnetic forming experiments were compared by optical microscope and Vickers hardness. The results show that the damage suppression and hardness enhancement are attributed to the effect of die counter-impact, especially for the hybrid quasi-static and dynamic forming processes.

Chain-die forming is an emerging sheet metal technique for manufacturing advanced high strength steel (AHSS) products. Springback and longitudinal bow are two of the major shape defects in gradual forming. In this study, the springback and longitudinal bow of AHSS in chain-die forming of hat and U profiles are investigated through experiment and finite element simulation. The disparity of springback along the longitudinal direction and disparate longitudinal bow signifies complex deformation processes of chain-die forming. Finite element simulation of the chain-die forming process gives an insight into the formation of non-uniform springback and longitudinal bow. The gradual forming process by one die block after another causes bending and reverse-bending deformation in the web area and the redundant deformation of the sheet metal, which further leads to non-uniform bending moment and accumulated stresses along the longitudinal direction. At the same time, the redundant deformation will also result in the longitudinal strain on the edge, while the downhill deformation decreases the maximum longitudinal strain at the edge and introduces the longitudinal strain on the web. The different non-uniform longitudinal strain distribution along the transversal direction causes disparate longitudinal bow behaviors for chain-die formed AHSS hat and U profiles, downward bowing and upward bowing respectively. By the established model, the disparate springback and longitudinal bow behavior can be determined, which also contribute to the process design for chain-die formed AHSS products.

The dimensional accuracy of cold extruded sun gear is poor since the material flow is considerably complex in the forming process. A novel precision finishing method was proposed in this study to improve the dimension accuracy of cold extruded sun gear, and a new finite element (FE) prediction strategy was developed to obtain an in-depth understanding of the deviation distribution laws of the finished sun gear. Then, the forming laws of internal-external gears such as material flow, tooth deformation, forming load, and tooth accuracy were analyzed using FE simulation and verified experiment. The investigation results show that the single deviations in profile and helix both first diminished remarkably, and then rose gradually, while the single M value deviation decreased remarkably with increasing the tooth width. The simulation results of teeth deviations are well agreed with the experimental ones, which verifies the reliability of the FE prediction strategy. Moreover, the profile accuracy of external gear can be improved from ninth to seventh class, lead accuracy can be enhanced from tenth to eighth class, and total M value deviation of internal spline is reduced to 72.3 μm, which proves the feasibility and effectiveness of the precision finishing method.

In the traditional hot forging, the temperature of the billet is heated to the forming range, and the die does not need to be heated or only slightly preheated. In isothermal forging, the temperature of the die needs to be heated to the same as that of the billet and kept constant during forging. This paper proposes a new method, which is to control the die temperature to a certain extent higher than that of the billets during the hot forming process. The method was verified by the upsetting process. The finite element analysis and upsetting experiment were carried out, and the method result was compared with the ordinary upsetting method and isothermal upsetting method. It has been found that this method can significantly improve the bulging phenomenon during upsetting. The KD value was introduced to characterize the bulging degree of the forging. Increasing the die temperature has a significant inhibiting effect on the instability of large-size billets during upsetting. By this method, when the billet is heated to 380 °C and the die temperature is stabilized at 405 °C, the upsetting of 2024 aluminum alloy with an aspect ratio of 3.7 can be realized. This method has not been reported to our knowledge.

Laser forming has been used as a non-contact forming technology to conduct plate deformation by using uneven thermal stress induced by a laser light source. Laser forming of 3D complex surface has wide application prospects. The study obtained “saddle surface” and “bowl shape surface” by using a round 7075 aviation aluminum plate as research object and applying a reasonable technology parameter and path plan. Furthermore, the study investigated the deformation rule under various technology parameters. Results show that when the diameter of circular direction heating route is 35 mm, the forming accuracy of the “saddle surface” is the highest. The main factor that affects the plate forming accuracy is the non-uniform distribution of temperature on the heating line. Adopting a sectional-type symmetry scanning method can effectively control the “edge effect” that occurs during the process of round-shaped plate laser forming, which can enhance forming accuracy. The shape of the forming surface is related to the energy density of the heating line.

Currently, a great deal of controversy exists regarding the real forces generated in drawbeads during sheet metal forming processes. The present work focuses on the analysis of the uplift force. First, a detailed literature review is carried out to analyse previous experimental procedures used to measure uplift forces. It is found that previous setups do not perfectly replicate the real geometry of industrial drawbeads. In order to obtain reliable forces, an experimental drawbead tester capable of adequately replicating industrial drawbeads is developed. Later, a variety of steels ranging from mild steels to 3rd-generation ultra-high-strength steels are tested and reliable uplift and also restraining force values are obtained. The main purpose of the work is to share with the research community reliable experimental data that allows precise evaluation of the accuracy of current drawbead models and that supports the generation of new numerical and equivalent drawbead models. In parallel to the experimental procedure, a step forward in the understanding of the drawbead closing phenomena is also achieved through a 2D numerical model. The main purpose of the model is to identify the variables that greatly affect uplift force. Going beyond previous studies, in which some variables were analysed, the present work covers, in a holistic manner, the impact that material properties, the geometry of drawbeads and contact behaviour between sheet and drawbead have on the uplift force. It is determined that surprisingly minor geometrical deviations in the drawbead nominal geometry have a large impact on the uplift force.

The machining quality of array flow channels directly affects the performance of solid oxide fuel cells as they are the key structures on the metallic interconnects of these cells. Electrochemical machining (ECM) is an efficient and low-cost technology for fabricating array flow channels. In the conventional ECM method, the cathode tool is usually designed to have cavity structures above the ribs to avoid collisions between the tool and workpiece. These cavities provide a passage for stray current to corrode machining fillets, causing electrolytes to flow away, and resulting in an uneven distribution of electrolyte flow velocity. To address these challenges, the authors propose a novel type of ECM cathode tool with a comb-shaped insulator. As the cathode tool is fed, the comb-shaped insulator is pressed tightly to the ribs by the spring compression device. This allows the insulator to shield the stray current and block the electrolyte shunt gap, thus enhancing the profile accuracy of the ribs and stability of the electrolyte flow field significantly. Furthermore, to verify the beneficial effect of comb-shaped insulator tools, the authors carry out simulations of the forming processes and flow field in the ECM of array flow channels. Finally, the experiments were carried out to compare 13 flow channels with lengths of 60 mm using the conventional and proposed methods. The experimental results show that the machined specimen exhibited better flatness at the top surface of the ribs and an enhanced surface quality of the channels’ bottom when the cathode tool with a comb-shaped insulator was used.

This study reports on the forging simulation of P91 steel at a temperature range of 900–1200°C and a strain rate range of 1–15 s−1 using Deform 3D finite element software. The study investigated th...

The hydraulic bulging technology of tubes can provide hollow parts with special-shaped cross sections. Its manufacturing process can effectively improve material utilization and product accuracy and reduce the number and cost of molds. However, the hydraulic bulging process of parts is very complicated. The size of the tube blank, the design of the loading route, and the forming process parameters will have an effect on the molding quality. Closed tubular torsion automobile beam is considered as the research object to study hydraulic bulging die design and optimize forming process parameters. CATIA software is used to design torsion beam product structure and hydraulic bulging die. AMESim software is employed to design hydraulic synchronous control system for cylinders on both sides of the hydraulic bulging die. Mathematical control model is established and verified in Simulink software. DYNAFORM software is applied to conduct numerical simulation of hydraulic expansion. The supporting pressure, molding pressure, friction coefficient, and feeding quantity are taken as orthogonal experiment level factors. Maximum thinning and maximum thickening rates are taken as hydraulic pressure expansion evaluation indexes to complete the orthogonal experiments. Main molding process parameters are analyzed via orthogonal experiment results and optimized by employing the Taguchi method. Optimal hydraulic bulging parameters are obtained as follows: supporting pressure of 20 MPa, molding pressure of 150 MPa, feeding quantity of 25 mm, and friction coefficient of 0.075. Simulation analysis results indicate that the maximum thinning rate is equal to 9.013%, while the maximum thickening rate is equal to 16.523%. Finally, the design of hydraulic bulging die for torsion beam was completed, and its forming process parameters were optimized.

The local strain approach (LSA) is an established concept to calculate the fatigue life of mechanical components for failure criterion crack initiation in several fields of engineering. In an elastic static finite element simulation, the critical stress state is detected and forms the basis for an elastic–plastic fatigue calculation with the LSA in a post-processing routine. This paper introduces extension options of the LSA to consider the influences of forming processes on the fatigue life of components.

Gear rolling process is a continuous rolling process by rotating and radial feeding motion of rolling wheel. It has advantages of low manufacturing cost, high gear strength and low forming load. The rolling processes of extrusion forming, gear splitting, continuous rolling and reshaping were analyzed by finite element method. The kinematic relationship between the rolling wheel and the forming gear during rolling deformation was studied. The results showed that the meshing motion between the rolling wheel and the billet could be guaranteed when the initial extrusion of the billet was not less than 1 mm. At the rolling gear splitting stage, the equivalent strain of the billet was shown to be related to the deformation of the material, which attained the largest at the root of the tooth. However, the equivalent stress of the billet was found to be dependent on the contact position of the rolling wheel, which has the maximum value at the root of the tooth in the contact area. During the continuous rolling forming stage, the forming load varied regularly and increased continuously with the rolling feed. The tooth profile of the gear was complete after the rolling reshaping process. According to the analysis and calculation results, the structure of rolling forming device was designed. Experiments showed that spiral bevel gears were able to be formed by rolling, and the billet size had an effect on the rolling process. When the size of billet was about 2 mm larger than the dividing circle radius of target gear, the quality of rolled gear was better. The results have important guiding significance for further research rules of rolling forming processes.

There is imprecision in the stage of construction because of manual quality control in the construction procedures. Forming and processing point clouds image of as is truss part with its CAD data are researched to identify and repair the geometric discrepancies and imprecision. Approved suggested technique of processing building model was done. Instead of manual processing of the 3D models points. BPNN architecture give the best coordinates processing training. It is applied to optimize the points forming process between the input laser scanned coordinates of the as-built model with the output true CAD coordinates. RMSE in x, y, xy, z and space vector R of all processing tasks are computed acceptably.

A material–structure–process–performance integration multi-objective optimization design of a magnesium/aluminum alloy punch-forming solid rivet joint based on Taguchi, grey relational analysis (GRA), and fuzzy rough set theory (FRST) weighting method was proposed. First, the material constitutive models of the rivet and riveted sheets were established through experiments. Second, simulation models of the rivet forming process and the pull-out and shear tests of the riveted joint were established, and corresponding experiments verified accuracy. Finally, the FRST weighting method was proposed. The integration multi-objective optimization of a rivet joint was conducted based on Taguchi, GRA, and FRST methods with optimization objectives (the rivet forming head’s dimensions and the riveted joint’s maximum pull-out and shear forces) and design variables (the material, structure, and riveting process parameters of the rivet joint). The optimal combination of design variable levels was obtained. Optimization results show that the rivet forming head’s dimensions were quite close to the recommended values after optimization, and the pull-out and shear mechanical strengths of the riveted joint were increased by 10.7% and 12.8%, respectively. Furthermore, a comparison was presented among FRST, principal component analysis, and entropy weighting methods. The FRST weighting method was concluded to be highly effective.

Advanced high-strength steels have been widely used to improve the crashworthiness and lightweight of vehicles. Different from the popular cold stamping, hot forming of boron-alloyed manganese steels, such as 22MnB5, could produce ultra-high-strength steel parts without springback and with accurate control of dimensions. Moreover, hot-formed medium-Mn steels could have many advantages, including better mechanical properties and lower production cost, over hot-formed 22MnB5. This paper reviews the hot forming process in the automotive industry, hot-formed steel grades, and medium-Mn steel grades and their application in hot forming in depth. In particular, the adaptabilities of medium-Mn steels and the presently popular 22MnB5 into hot forming were compared thoroughly. Future research should focus on the technological issues encountered in hot forming of medium-Mn steels to promote their commercialization.

Small-batched metal plates with free-form surfaces are widely used in different manufacturing industries; however, it is unrealistic to produce such metal plates based on traditional die stamping and rolling processes. Over the last few decades, numerous efforts have been adopted to produce the metal plates with free-form surfaces with acceptable quality, efficiency, and cost through flexible forming processes. In the present paper, a heat-assisted incremental bending process was proposed to manufacture metal plates with large unsymmetrical curvatures. The test metal plates were supported by some hydraulic cylinders, and the punch moved up and down to press the metal plates according to the loading path determined by the minimum energy method. In addition, an induction heating system was applied to heat the metal plates at the punching position. One objective metal plate with large unsymmetrical curvature is deformed based on the heat-assisted incremental bending experiments. The obtained results indicate that the proposed thermo-mechanical flexible forming process could produce complex metal plates with good accuracy and high efficiency.

Magnesium alloys, because of their good specific material strength, can be considered attractive by different industry fields, as the aerospace and the automotive one. However, their use is limited by the poor formability at room temperature. In this research, a numerical approach is proposed in order to determine an analytical expression of material formability in hot incremental forming processes. The numerical model was developed using the commercial software ABAQUS/Explicit. The Johnson-Cook material model was used, and the model was validated through experimental measurements carried out using the ARAMIS system. Different geometries were considered with temperature varying in a range of 25–400 °C and wall angle in a range of 35–60°. An analytical expression of the fracture forming limit, as a function of temperature, was established and finally tested with a different geometry in order to assess the validity.

This study focuses on the Bubnov-Galerkin finite element model used to obtain the stresses and pressure fields set up at various cross-sections of a blank during the metal forming process. Four Lagrange quadratic elements were assembled to represent the various blanks. The governing equation adopted is a one-dimensional differential equation describing the pressures and stresses exerted on the forming process. In conducting the analysis, the various blanks are divided into a finite number of elements and further applying the Bubnov-Galerkin-weighted residual method to obtain the weighted integral form; the finite element model is obtained in a matrix form, from the weighted residual boundary conditions which are now applied to obtain the pressure distribution across the cross-section of the various blanks. Finite element results are obtained for a value of the coefficient of friction, die angle, length, and blank radius. Solution of the finite element method was compared with the exact solution, along with an experimental test known as press-fit analysis using Ansys Workbench, a program-controlled mesh of polar hexahedral elements which was utilized to further validate the result. Furthermore, the use of a computer-aided software assists in visualizing the solution of the tube sinking problem. The results were all presented in both tabular and graphical modes. This study shows that there are potentials for using this approach in engineering practices to ensure that the strength of materials be considered before usage in design and fabrication. These results are expected to improve advance knowledge in manufacturing processes.

With the rapid development of manufacturing technology in the fields such as aerospace, aviation, national defense, and automobiles, the demands for lightweight, toughening, and forming accuracy of products have increased. As one of the main defects in the plastic forming of thin-walled components, wrinkling failure has always been a key element in forming control. The sheet metal is restrained by the mold in actual forming process and the wrinkling is significantly affected by the boundary conditions. To study the effect of the mold constraints on the wrinkling failure in the actual forming process, a stretching wrinkling test of wedge plate with the boundary constraint conditions of mold was designed. By establishing the simulation model for wrinkling failure of sheet forming under mold constraints and its wrinkling limit diagram (WLD), the accurate prediction of sheet metal wrinkling failure form and the critical state in actual forming was realized. At the beginning of the research, the wedge plate tensile test was implemented for using as verification for simulation results, then the wrinkle simulation model of Buckle-Dynamic with the instability mode as the initial defect was established. By combining with the non-contact full-field strain measurement system DIC to obtain the strain data of the specimens in the test process, the accuracy of the simulation model was verified. On this basis, the critical wrinkling limit diagram (WLD) was established for the wrinkle partition on the wedge specimen, and the influence of stress state, stress loading path, principal compressive stress increment, principal stress ratio factors on the distribution and propagation direction of wrinkles, as well as the morphology and characteristics of WLD are discussed. The research content of this study is of guiding significance for the prediction of the actual wrinkling failure of sheet and shell forming.

Additive manufacturing (AM), also known as 3D-printing (3DP) technology, is an advanced manufacturing technology that has developed rapidly in the past 40 years. However, the ceramic material printing is still challenging because of the issue of cracking. Indirect 3D printing has been designed and drawn attention because of its high manufacturing speed and low cost. Indirect 3D printing separates the one-step forming process of direct 3D printing into binding and material sintering, avoiding the internal stress caused by rapid cooling, making it possible to realize the high-quality ceramic component with complex shape. This paper presents the research progress of leading indirect 3D printing technologies, including binder jetting (BJ), stereolithography (SLA), and fused deposition modeling (FDM). At present, the additive manufacturing of ceramic materials is mainly achieved through indirect 3D printing technology, and these materials include silicon nitride, hydroxyapatite functional ceramics, silicon carbide structural ceramics.

This study applies high rate forming technology to the manufacture of miniature parts and proposes a novel miniature parts bulk forming method, that is, laser shock micro-bulk forming (LSMBF). Through the numerical simulation and experimental research on 1100Al rod, the feasibility of manufacturing miniature parts using the LSMBF method is discussed. The similarities and differences of two simulation methods, namely, the smooth particle dynamics and finite element coupling (SPH-FE) and coupled Euler–Lagrangian (CEL) methods, were analyzed. Results show that the SPH-FE method is more consistent with the experiment and is more suitable for simulating the complex large deformation forming process of LSMBF than the CEL method. This study shows that the plastic deformation process of LSMBF is as follows. First, the upper end of the rod undergoes mushroom-shaped upsetting. Then, the bottom of the rod touches the micro die, and the upsetting phenomenon occurs. Finally, the micro-die is gradually filled. The plastic deformation of metal is related to the stress wave propagation and inertia effects. The main flow direction of the metal is axial, and the flow uniformity is fine. This study also shows that increasing the laser energy intensity is beneficial to improving the uniformity of the parts when impacting micro-die at high speed.

Aluminum alloys are characterized by low formability limits under cold forming conditions. The accurate prediction of deformation and failure in sheet metal forming allows for the optimization of forming process parameters and reduces tooling modifications and materials costs. Several models for ductile damage have been developed in the past decades to quantify and predict forming and damage response of sheet metal under complex-forming conditions. However, there is a need to identify a robust model which can provide realistic predictions for the behavior of aluminum sheet metal under the cold forming condition and different loading conditions. This work aims to investigate the prediction capabilities of different damage models for AA-5754 during the cold forming process. The experimental tensile and forming limit diagram (FLD) data of AA-5754 sheet metal used for the damage models’ calibration were obtained from literature. In this article, four damage models available in two broadly used the FE software; namely, LS-DYNA and PAM-STAMP were investigated. The models utilized from LS-DYNA material library were MAT_JOHNSON_COOK, MAT_GURSON, and MAT_GISSMO; while from the PAM-STAMP software, the novel CDM model was used. The cross-die formability tests for AA-5754 sheets were performed to validate these damage models. The predictions of the novel CDM model were found to give a good agreement with the experimental results obtained from the formability tests.

A novel method named hydrodynamic deep drawing process utilizing a combined floating and static die cavity (HDDC) was proposed in this research, in order to depress wrinkling during hydrodynamic deep drawing process to form a conical cup with higher height. A special experimental setup of a combined die cavity, which a static chamber inlaid with an inner floating die cavity, was designed to implement the modified hydrodynamic deep drawing experiments. At first, the feasibility of the modified method was evaluated in detail by numerical analyses and experimental tests. Then, the effects of the liquid counter pressure in die cavity on the forming process were also studied. It was found that the proposed method HDDC was feasible and the suppressing wrinkling effect dramatically came into being by using a floating die cavity during the hydrodynamic deep drawing process for conical cups of higher height. The rigid contact between the crater corner of the floating cavity and the blank contributes to the suppressing wrinkle effect during the hydrodynamic deep drawing process utilizing a combined floating and static die cavity. The hydrodynamic deep drawing process of conical cups utilizing a combined die cavity becomes more robust compared with the conventional hydromechanical deep drawing process.

Process-induced residual stresses significantly influence the mechanical properties of a formed component. A polymer pad is used as a flexible die in two-point incremental forming to induce compressive residual stresses in the component during the forming process. Experimental and numerical results illustrate the influence of compressive stress superposition on the component properties. It is shown that the active support, using a geometry-independent polyurethane die, causes beneficial compressive residual stresses on the tool side compared to the tensile residual stresses induced by the single-point incremental forming process without such a supporting die.

This study presents a novel method using a disk-like sample to assess the workability of metal during the cross wedge rolling (CWR) process. Using this method, we can quantitatively evaluate the moment destruction which occurs at the center of the sample during CWR. In this study, 45 steel was selected to demonstrate the proposed method. Firstly, we designed a model for the tools and sample, conducted finite element simulations to analyze the distribution regulations of metal flow, stress, and strain, and evaluated the relationship between the damage and moving distance of the tool during the forming process. Then, we obtained the optimal deformation temperature range, rolling speed, and geometry parameters for the tool. Finally, experiments were conducted from 20 °C to 1 200 °C to verify the accuracy of the developed model. It was demonstrated that the model was significantly accurate in accessing the workability of 45 steel in the CWR process. The proposed method could be generalized to investigate the CWR process for other materials, such as aluminum alloys, superalloys, titanium alloys, etc.

As an additive manufacturing technology, selective laser melting (SLM) can form any complex metal parts, which has unparalleled advantages compared to traditional processing methods. However, there are still some problems such as accuracy and non-repeatability to overcome to apply SLM to production practice. The high-precision monitoring and degradation feedback technology of SLM equipment is the future development direction. The real-time monitoring machine can repair itself and avoid the tedious detection in the post-processing stage. The researchers mainly monitor the quality of the forming process by molten pool signal, temperature signal, sound signal, and scanning track. The forming process is monitored using coaxial detection or paraxial detection through a high-speed camera, pyrometer, and other equipment. This paper can provide theoretical support for the SLM intelligent monitoring field.

FRP material properties offer unique opportunities for architecture, but their mould-based standard forming processes stand in contrast to contemporary practices, aiming for variation and surface a...

Sheet metal forming technologies have been intensively studied for decades to meet the increasing demand for lightweight metal components. To surmount the springback occurring in sheet metal forming processes, numerous studies have been performed to develop compensation methods. However, for most existing methods, the development cycle is still considerably time-consumptive and demands high computational or capital cost. In this paper, a novel theory-guided regularization method for training of deep neural networks (DNNs), implanted in a learning system, is introduced to learn the intrinsic relationship between the workpiece shape after springback and the required process parameter, e.g., loading stroke, in sheet metal bending processes. By directly bridging the workpiece shape to the process parameter, issues concerning springback in the process design would be circumvented. The novel regularization method utilizes the well-recognized theories in material mechanics, Swift's law, by penalizing divergence from this law throughout the network training process. The regularization is implemented by a multi-task learning network architecture, with the learning of extra tasks regularized during training. The stress-strain curve describing the material properties and the prior knowledge used to guide learning are stored in the database and the knowledge base, respectively. One can obtain the predicted loading stroke for a new workpiece shape by importing the target geometry through the user interface. In this research, the neural models were found to outperform a traditional machine learning model, support vector regression model, in experiments with different amount of training data. Through a series of studies with varying conditions of training data structure and amount, workpiece material and applied bending processes, the theory-guided DNN has been shown to achieve superior generalization and learning consistency than the data-driven DNNs, especially when only scarce and scattered experiment data are available for training which is often the case in practice. The theory-guided DNN could also be applicable to other sheet metal forming processes. It provides an alternative method for compensating springback with significantly shorter development cycle and less capital cost and computational requirement than traditional compensation methods in sheet metal forming industry.

Spring-back of sheet metal affects the dimensional accuracy of the components after stamping and has to be eliminated or corrected. Advanced high strength steels (AHSS) are prone to spring-back while forming at ambient temperatures. Hot stamping process is an effective technique to reduce the spring-back upon forming. The forming temperatures and the phase transformations associated with quenching are known to influence the spring-back. However, the detailed experimental analysis on spring-back behaviour is limited due to the difficulty in physically simulating the thermal-mechanical conditions prevailing in a typical hot forming process. In the present work, a novel V-bending technique is presented for effectively measuring the spring-back using a thermal-mechanical simulator, Gleeble™. V-bending is carried out by applying a compressive force along the longitudinal plane of AHSS steel strips at forming temperatures. Upon V-bending, samples were cooled at different cooling rates while maintaining the forming loads to simulate die quenching. Results indicate that the spring-back decreases and becomes close to zero (at a cooling rate of 20 K s−1) with an increase in cooling rate for a hot stamping steel. Further, an increase in cooling rate results in spring-forward owing to the formation of an increased volume fraction of martensite.

In developing the 4.0 industrial revolution era, vehicle body repair manufacturing companies are required to carry out technological innovations to support effective and efficient performance. One way is in the metal forming process, namely by changing the metal's shape into a variety of products by the company to increase the selling value of the material. The method of forming metal or these materials uses a bead roller machine with a compressive force to carry out the forming process on sheet metal plates according to the size of the tools' geometry and shape. The design of this bead roller machine is operated by using an electric motor with a power of 0.5 HP, using an Alternating Current (AC) voltage, the thickness of the iron frame dimensions of 1.2 cm, and using a reducer with a ratio of 1: 100. Selection of engine parts such as shafts, bearings, tools, and sprockets using materials that are economical and easy to obtain. The design uses Autocad 2014 Software, starting with designing a bead roller machine design paying attention to the strength of the materials used, then assembling the components and the machine's electrical system. The result of this design will be displayed by performing the bead roller machine performance. This bead roller can increase work productivity efficiently and effectively concerning sheet metal media for vehicle body repair compared to manual roll bending tools.

The article presents an attempt at conceptual assembly on a platform of systemic ideas about modern globalization and observed global dynamics. The relevance of this article lies in ideas and approaches arising from the increasing formation of the "third wave" of globalization and state formation and the mechanisms of global and national-state regulation and management relevant to them.