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In this paper, the springback behavior of high strength aluminum alloy 7075 is studied by experiments and finite element (FE) simulation. Firstly, an analytical model is established to predict the springback angles and analyze the springback trend. The springback experimental tests are conducted by using the V-shaped stamping dies. The influence of deformation temperature, punch radius, and blank holder force on the springback angles is studied. Finally, an FE simulation model is performed to investigate the deformation characteristics and springback process of the aluminum alloy sheet. The results show that the change of springback angles is direct proportional to the punch radius. The springback angles increase with the decreasing deformation temperature and the increasing blank holder force. The stress relaxation that occurs during the die holding stage is the primary reason of reducing the springback compared with cold stamping. Low blank holder force will cause side wall curl, which results in the deviation of forming size. The FE simulation model considering stress relaxation is capable of precisely predicting the change of springback angles, and the simulation results exhibit good consistency with the experimental results.

Nowadays, the level of stamping dies in the world has been greatly improved, and stamping technology has also developed greatly. Based on the analysis of the pallet parts, it is determined that the required processes are punching and blanking. The compound dying for punching and blanking was chosen for processing after the processing method was examined. Specific design process: analyze the material used for the part, calculate the required punching force, and select the required press according to the punching force, the closing height of the die, and the size of the die handle hole. The parts required by the die, such as convex and concave die, stripper plate, fixed plate, and other components, should also be designed so that the processing of the parts can be completed after the assembly is completed. In the design process, CAD drawing software, three-dimensional drawing software, etc., can be used to complete the drawing of two-dimensional and three-dimensional drawings of parts, improve the efficiency of our drawing, and can also quickly solve problems existing in the drawing, which makes the design process simpler.

This paper presents a sustainable approach to utilizing oil lubricants in progressive die stamping for small components, aiming to reduce environmental impact while maintaining product quality. Numerical analysis explored the sensitivity of stamping operations to friction variations. Experimental tribological tests compared conventional lubrication practices with Minimal Quantity Lubrication (MQL), which applies less than 1 g/m 2 of oil. Results showed MQL increased friction slightly but maintained acceptable product quality. These findings highlight the need to optimize MQL parameters for stable performance in industrial stamping processes.

In order to determine the failure reason for the non-working area of a cracked A-pillar hot-stamping die insert, various instruments were used to detect the properties and microstructures of the cracks and matrix. The results show that the cracks are located in the area where the oxidative corrosion is more serious, and the cracks do not appear in the pitting area, verifying that crack initiation is related to the stress concentration on the upper half of the inner wall of the cooling channel. Meanwhile, pores and cracks exist in the grain boundary and crystal, making the impact energy of the die steel poor. Therefore, crack initiation and propagation easily occur along the brittle oxide layer. In summary, the die insert is damaged by stress-induced corrosion. In engineering applications of hot-stamping dies, we should pay more attention to the cracking of the cooling channel caused by stress and corrosion.

In this paper, the springback of the aluminium alloy AA5754 under hot stamping conditions was characterised under stretch and pure bending conditions. It was found that elevated temperature stamping was beneficial for springback reduction, particularly when using hot dies. Using cold dies, the flange springback angle decreased by 9.7 % when the blank temperature was increased from 20 to 450 °C, compared to the 44.1 % springback reduction when hot dies were used. Various other forming conditions were also tested, the results of which were used to verify finite element (FE) simulations of the processes in order to consolidate the knowledge of springback. By analysing the tangential stress distributions along the formed part in the FE models, it was found that the springback angle is a linear function of the average through-thickness stress gradient, regardless of the forming conditions used.

Even though high-strength steel is a favourable material because of its high strength and good formability, this material poses new challenges on the structure of stamping dies owing to potential damages of the die during production. Stamping dies are conventionally produced according to design manuals and standard manufacturing guidelines, where a high safety factor is specified to ensure that the stamping die is heavy and thick. A structural topology optimization method for a stamping die is presented in this study based on finite element simulations of the sheet metal stamping process. The finite element model of the stamping die is first established. Next, the boundary forces acting on the sheet metal are obtained from simulations and these forces are applied to the punch surface by means of load mapping during topology optimization. These forces are equivalent to the interaction between the blank and die. The objective function is to maximize the static stiffness under multi-conditions, which is defined by using the compromise programming approach. The analytic hierarchy process method is used to determine the weight ratio of the body stiffness in various load conditions and conduct topology optimization of the comprehensive objective function. The results show that the weight of the optimal punch is reduced while its performance is improved. More importantly, the reconstructed punch can be manufactured practically.

This study investigated the microstructure and corrosion behavior of 30MnB5 hot-stamped steel after applying a zinc coating using the cold-spraying method followed by heat treatment (HT). Al-10 wt%Si coating is essential for improving the high-temperature corrosion resistance of 30MnB5 steel during the hot-stamping process. Before HT, the coating layer primarily consisted of Al, whereas after HT, Fe–Al-based intermetallic compounds were formed throughout the layer. The Zn in the coating layer applied using the cold-spraying method was not uniformly distributed before HT. However, during HT, the low-melting-point Zn melted and re-solidified, allowing it to combine with Fe diffusing from the substrate. Consequently, Zn–Al–Fe-based intermetallic compounds were formed on the surface of the coating layer. In the Zn-coated specimens, the current density near the corrosion potential tends to be lower than that of the Al–Si-coated specimens because Zn corrodes preferentially owing to its sacrificial anode effect, thereby protecting the underlying Al–Si-coated layer and steel.

In hot stamping of aluminium, the need for efficient methods to evaluate, compare, and rank lubricants based on their tribological performance is critical in the early stages of selection. Pilot and simulative testing can be costly, time-consuming, and complex, making it inefficient for initial benchmarking. This work aims to develop a test methodology to assess lubricant performance for hot stamping under key operating conditions without fully simulating the forming process. The proposed method distinguishes the impact of temperature on lubricant degradation, friction, wear response, and cleanability. The tests utilised a conventional hot work tool steel and a 6010S aluminium alloy with two commercially available lubricants: a polymeric lubricant and a lubricant containing graphite. The tribological tests involved a reciprocating, sliding flat-on-flat configuration at two temperatures (100 °C and 300 °C). The methodology showed that the graphite-containing lubricant exhibited over a four times lower friction coefficient than the polymer-based lubricant at 10 wt.% concentration and 300 °C. At 100 °C, both lubricants provide lubrication and can be cleaned, but increasing temperature led to a significant decline of both aspects. The observed temperature range where the lubricants degrade was between 120 °C and 170 °C.

Sheet metal stamping is widely used for high-volume production. Despite the wide adoption, it can lead to defects in the manufactured components, making their quality unacceptable. Because of the variety of defects that can occur on the final product, human inspectors are frequently employed to detect them. However, they can be unreliable and costly, particularly at speeds that match the stamping rate. In this paper, we propose an automatic inspection framework for the stamping process that is based on computer vision and deep learning techniques. The low cost, remote sensing capability and simple implementation mean that it can be easily deployed in an industrial setting. A particular focus of this research is to account for the harsh lighting conditions and the highly reflective nature of products found in manufacturing environments that affect optical sensing techniques by making it difficult to capture the details of a scene. High dynamic range images can capture details of an environment in harsh lighting conditions, and in the context of this work, can capture highly reflective metals found in sheet metal stamping manufacturing. Building on this imaging technique, we propose a framework including a deep learning model to detect defects in sheet metal stamping parts. To test the framework, sheet metal ‘Nakajima’ samples were pressed with an industrial stamping press. Then optimally exposed, sequence of exposures, tone-mapped and high dynamic range images of the samples were used to train convolutional neural network-based detectors. Analysis of the resulting models showed that high dynamic range image-based models achieved substantially higher accuracy and minimal false-positive predictions.

The life of industrial dies and punches can be effectively increased by timely repair of damaged surfaces. In the present investigation, a procedure was developed to recover VF800AT steel stamping punches by gas metal arc welding (GMAW) process, using Tube-Alloy 260-G metal-cored filler wire (MCFW) with a diameter of 1.2 mm, that deposits a martensitic steel alloy, and a gas-shielded mixture with 25 vol.% CO 2  + 75 vol.% Ar, and a flow rate of 12 l/min. The repair procedure included the following steps: surface preparation, pre-heating, manual welding, post-welding tempering, and final inspection. The samples were pre-heated at 450, 500, and 550 °C, repaired by gas metal arc welding, and post-welding tempering. Subsequently, were characterized before and after the weld repair concerning the macrostructure, microstructure, and microhardness. The correlation of the hardness in the weld metal (WM), heat-affected zone (HAZ), and base metal (BM) regions with the pre-heating temperature and post-welding tempering steps was statistically evaluated by the analysis of variance (ANOVA). Performance tests of the new and weld repaired punches were carried out to experimentally validate these conditions. Optical microscopy and scanning electron microscopy images, energy dispersive system analysis, and roughness measurements were carried out to evaluate the cutting-edge radius and the type of wear acting on the punches. Punches pre-heated to 450 °C and submitted to one post-welding tempering step presented the best results, being the most suitable to recovering VF800AT steel stamping punches by the GMAW process.