In this study, the response surface method (RSM), back propagation neural network (BPNN), and genetic algorithm (GA) were used for modeling and multi-objective optimization of the forming parameters of AA5052 in incremental sheet forming (ISF). The optimization objectives were maximum forming angle and minimum thickness reduction whose values vary in response to changes in production process parameters, such as the tool diameter, step depth, tool feed rate, and tool spindle speed. A Box–Behnken experimental design was used to develop an RSM and BPNN model for modeling the variations in the forming angle and thickness reduction in response to variations in process parameters. Subsequently, the RSM model was used as the fitness function for multi-objective optimization of the ISF process using the GA. The results showed that RSM effectively modeled the forming angle and thickness reduction. Furthermore, the correlation coefficients of the experimental responses and BPNN predictions of the experiment results were good with the minimum value being 0.97936. The Pareto optimal solutions for maximum forming angle and minimum thickness reduction were obtained and reported. The optimized Pareto front produced by the GA can be a rational design guide for practical applications of AA5052 in the ISF process.

Metal additive manufacturing (AM) is a low-cost, high-efficiency functional mold manufacturing technology. However, when the functional section of the mold or part is not a partial area, and large-area additive processing of high-hardness metal is required, cracks occur frequently in AM and substrate materials owing to thermal stress and the accumulation of residual stresses. Hence, research on residual stress reduction technologies is required. In this study, we investigated the effect of reducing residual stress due to thermal deviation reduction using a real-time heating device as well as changes in laser power in the AM process for both high-hardness cold and hot work mold steel. The residual stress was measured using an X-ray stress diffraction device before and after AM. Compared to the AM processing conditions at room temperature (25 °C), residual stress decreased by 57% when the thermal deviation was reduced. The microstructures and mechanical properties of AM specimens manufactured under room-temperature and real-time preheating and heating conditions were analyzed using an optical microscope. Qualitative evaluation of the effect of reducing residual stress, which was quantitatively verified in a small specimen, confirmed that the residual stress decreased for a large-area curved specimen in which concentrated stress was generated during AM processing.

Additive manufacturing (AM) has recently been receiving global attention. As an innovative alternative to existing manufacturing technologies, AM can produce three-dimensional objects from various materials. In the manufacturing industry, AM improves production cost, time, and quality in comparison to existing methods. In addition, AM is applied in the fabrication and production of objects in diverse fields. In particular, metal AM has been continuously commercialized in high value-added industries such as aerospace and health care by many research and development projects. However, the applicability of metal AM to the mold and die industry and other low value-added industries is limited because AM is not as economical as current manufacturing technologies. Therefore, this paper proposes an effective solution to the problem. This study examines a method for using direct energy deposition and heterogeneous materials, a heterogeneous material additive-manufacturing process for metals used to optimize the cooling channels and a key process in manufacturing hot-stamping dies. The improvements in the cooling performances and uniform cooling were evaluated by heat-flow analysis in a continuous process. Finally, trial products were fabricated using the proposed method, and a trial for hot stamping was conducted to examine the possibility of it being used in commercial applications.

Welding-induced distortion is a major concern for the industrial joining practice. The welding-induced distortion at the weldment between the coupled torsion beam axle (CTBA) of the automotive rear chassis parts and trailing arm connected to the wheel hub axle module seriously affects the tow angle, camber angle, and caster of the wheel axle. In this paper, the welding process between CTBA and trailing arm was numerically analyzed via SYSWELD (i.e., a finite element analysis code), using the material properties predicted via J-MatPro SW, material properties software, considering the thermo-mechanical-metallurgical properties of materials. From the numerical study for the weldment of CTBA and trailing arm, we predicted the welding and thermal distortions, temperature variation, microstructure, and residual stress at the concerned area. As a result, the temperature of the welded area was predicted between 102 °C and 840 °C at the end of weldment and converged to room temperature after 1000 s. The maximum portion of the martensite structure at the welded area was expected to be 55%. The expected distortions of the trailing arm after the weldment were 0.52 mm, −1.47 mm, and 0.44 mm in the x, y, and z-directions, respectively. Finally, the limitations of this research and recommendations are presented.

Most solenoid valves in use today require a magnetic coil to be continuously energized to maintain the magnetization of the magnetic body in order to operate. The problem is that if the power is still supplied, the power consumption will continue. In addition, problems such as shortening the lifespan of solenoid valve internal parts due to the increase in the internal temperature of the electronic stability control (ESC) due to the continuous heating of the magnetic coil, and malfunction due to instantaneous power failure may occur. In this study, we conducted a study on the permanent magnet traction control valve (TCV) for ESC that can minimize the unnecessary power consumption of electric vehicle batteries. For optimal permanent magnet design, polarity direction setting and permanent magnet specifications were studied through FE simulation. A permanent magnet TCV was fabricated and an electromagnetic force test was conducted to compare and evaluate it with the FE simulation result. By using a permanent magnet, it was possible to lower the initial current value for the TCV to drive, therefore, it was possible to develop a permanent magnet TCV that can minimize the unnecessary power consumption of electric vehicle batteries.

Hot stamping uses boron (B) steel to simultaneously form parts at high temperatures while cooling the parts in a mold, which is advantageous because of the ability to freeze the forms. However, compared to conventional cold forming, this technique requires additional facilities that include heating devices and additional time for cooling after forming at high temperatures. Additionally, because of the high strengths of hot stamping parts, shear process operations after molding tend to be difficult to perform as a continuous operation via press processing; thus, most operations depend on separate laser processing, which results in lower productivity and increased manufacturing costs. This limitation continues to be the most significant problem with this technology, therefore, restricting its commercialization because of increased mold manufacturing costs and durability problems. This study investigated a low-cost, high-functionality shear mold manufacturing method for 1.5 GPa grade hot-stamped components using heterogeneous metal additive manufacturing. After the concentrated stress in steel during the shearing processes was analyzed using a multi-physical analysis, metal additive manufacturing was used to fabricate the shear mold. Its life was evaluated through trial molding and compared with that for conventional technology. Finally, the commercialization potential of the newly developed method was assessed.