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This study focuses on the effects of the key process parameters during a modified hydrodynamic deep drawing utilizing a combined floating and static die cavity (HDDC). A two-stage hydraulic loading path is recommended in the novel process, and each stage of the hydraulic loading path is a linear loading path with an inflection point. The method to evaluate the wrinkle and forming dimension precision of the formed parts is introduced at first. Then, the influence of the key parameters of the two-stage hydraulic loading path as well as the blank holder force on the dimension accuracy and surface quality of the formed parts was studied in detail. The results showed that the influence of the liquid pressure during the second stage is more significant than that in the first stage in hydrodynamic deep drawing utilizing a combined floating and static die cavity. The initial pressure of the second stage and the maximum pressure arriving moment during this stage have a significant impact on the dimensional accuracy of the formed parts, and the smaller initial pressure or the later the maximum pressure of the second stage arrives, the higher the accuracy of the formed part is. Similarly, the influence of the blank holder force in the second stage on the forming accuracy is more significant than that in the first stage.

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.

A high percentage of folding defects were more easily introduced into the outer area of the sleeve hole during the mass production of track link forgings. In this study, it could be found that the folding defects were induced by the end-surface quality of the billet with the streamline characterization and the points tracking simulation. A defect elimination method based on the preforming design was proposed according to the numerical simulation and the experiment. The outer wall of the sleeve hole in the die cavity was shrunk inwards a certain distance to extrude the surface defects of the billet into the flash during the pre-forging. And then, the original flat shape punching wad of the sleeve hole was designed as an oblate-frustum of a cone shape to compensate the shortage of the material volume. The shrinkage range and the justified height of the oblate-frustum preform were recommended by the numerical simulation. As a result, the experiments showed that the proposed preforming design method completely eliminated the folding defects of the track link forgings.

Demand for micromachine parts, including mini gears, has been increasing recently because of the continuously decreasing size of consumer electronic products. Forging is a conventional method of manufacturing mini gears, and it is characterized by a higher production rate, low material cost, and low total cost. Therefore, many researchers have focused on improving the technology used for forging mini gears. The present study investigated the effect of grain size of a material on the die cavity filling rate for the material during the forging of mini gears. Experimental results were compared against those of a simulation software for analyzing the applicability of software to simulations of materials with different grain sizes. The analysis indicated that materials with large grain sizes exhibit poor material flow capacity on the die base plate compared with materials with smaller grain sizes. For materials with large grain sizes, the maximum load required to fill die cavities is lower. The difference in the maximum load between the experimental results and the simulation results increased when the grain size exceeded the addendum thickness.

Transverse uniformity is an important measurement of the coating quality for slot coating. In this paper, the influence of die structure on the transverse uniformity is investigated according to a fully 3D mathematical modelling and numerical simulations. In the modelling part, the coating liquid is regarded as generalized Newtonian fluid and the fluid flow inner the die head is governed by the 3D incompressible Navier-Stokes equations. In solving the model, an efficient fractional step finite element method is used. Four kinds of commonly used die structures are simulated and analysed. The results show that the die structure has great influence on the transverse uniformity. Generally, dies with double cavities can get better transverse uniformity that single cavity.

Cooling channels play a critical role in various casting and molding processes, impacting both the cycle time and quality of the product. As additive manufacturing technologies become increasingly prevalent, conventional straight-drilled channels are being progressively substituted by intricate cooling lines that conform to the contours of the fabricated part. This transition can lead to a significant reduction of the solidification time and temperature gradients, consequently lowering the occurrence of part defects. However, designing such channels becomes challenging as geometric complexity and manufacturing constraints increase. In this work, we present a density-based topology optimization approach to generate conformal cooling channels in molds and dies inserts. To mitigate temperature variations, the objective function is penalized using the temperature standard deviation of the insert cavity surface. A density-gradient-based constraint is further utilized to reduce the generation of overhanging structures and promote manufacturability. In particular, the use of this constraint leads to the generation of channels characterized by a teardrop-shaped cross section. The cooling efficiency of a selected optimized design is confirmed through computations using a body-fitted solver. The geometry is subsequently manufactured by Laser Powder Bed Fusion (LPBF) and experiments are conducted to compare its performance in comparison to a design featuring straight-drilled channels. The results demonstrate that the optimized geometry significantly enhances the heat extraction rate and further leads to a 43% reduction of the cavity temperature standard deviation.

The friction and initial setting position of preform have an important influence on the metal flow and cavity filling during die forging process of large-scale component, especially for closed-die forging with flash of large-scale titanium alloy strut. This paper studies the influence of processing parameters on the die forging process of large-scale strut by targeting the filling difference ( f ) between right and left cavities, and some relational models such as relationship between friction and preform position were established. The results indicated that the friction amplitude ( m ) and initial setting position ( x ) of preform have notable influence on the filling states of right and left cavities, but the loading speed ( v ) of upper die and initial temperature ( T d ) of dies have little influence on the filling state; with the initial position of preform moving to right cavity (head of strut), the fluence of m on f reduces, but the fluence of x increases; the established relationship between m and x can obtain the feasible region with an optimal point for initial setting position of preform, and the feasible region with a linear range for the initial setting position of preform can be obtained by considering the expected accuracy of filling difference f , and then the feasible region with an areal range for the initial setting position of preform can be obtained by considering the fluctuation of frictional condition in further.

Aluminum high-pressure die castings (HPDC) are widely used in the automotive and other industries to achieve lightweight components with high productivity. However, the formation of externally solidified crystals (ESCs) during HPDC process can significantly reduce the mechanical performance, particularly the elongation and fatigue, of these cast parts. ESCs can be classified into two main types: Type I, consisting of large α-Al dendrites, and Type II, characterized by large crystals with fine dendrites that exhibit a clear boundary with the matrix. This study investigates the formation mechanisms of these two types of ESCs during the HPDC process. The effects of various process parameters on the formation and movement of ESCs were analyzed through high-pressure die casting trials, computer simulations, and water analog experiments. The investigation suggests that both types of ESCs start within the shot sleeve. Type I ESCs form and float within the melt, while Type II ESCs develop along the shot sleeve wall and plunger tip post-pouring. Increasing the melt temperature was found to reduce the formation of Type II ESCs. Both types of ESCs are carried into the die cavity during the filling process. Their distribution is closely related to the fast shot speed and the turbulence of the molten aluminum. Notably, a reduced fast shot speed was found to significantly decrease the number of ESCs transported into the die cavity, especially Type II ESCs. This reduction led to a considerable improvement in the mechanical performance of the cast components, particularly in terms of elongation. These findings on ESC formation as related to process parameters provide important guidance to achieve high-performance castings in industrial applications.

Feeding path and movable die designs are crucial to implement bellows manufacturing with an appropriate hydraulic pressure and make the products satisfy the required geometrical and dimensional specifications. In this paper, a tube hydroforming process combined with movable die designs is developed to obtain an appropriate forming range of the internal pressure and increase the thickness uniformity in the formed product. Two kinds of feeding types are proposed to discuss the effects of the feeding path and die design on the convolution heights and thickness uniformity in the formed bellows. A finite element simulation software “DEFORM” is used to analyze the plastic deformation of the tube within the die cavity using the proposed feeding types for three different shape bellows. Allowable forming ranges of internal pressures for sound products with required tolerances in geometry and dimensions using different feeding types are also investigated. Finally, tube hydroforming experiments of three-convolution bellows are conducted and experimental thickness distributions and convolution heights of the products are compared with the simulation results to validate the analytical modeling with the proposed movable die concept.

The paper presents the results of the research on the impact of process parameters of high-pressure, cold-chamber die casting of an industrial casting made of aluminium alloy on the casting properties assessed macroscopically by measuring the casting average density and microscopically through the characteristics of the casting microstructure. The analysis covers the influence of three selected velocity settings of the pressing plunger, which determine the filling time, and three values of the compression pressure setting characteristic of the third phase of the casting process. The cooling and solidification simulations of the casting were performed using the ProCAST software. During the simulation tests, the impact of the filling rate of the alloy into the die cavity on the cooling rate and the alloy solidification path at selected points were determined. The conducted research allowed linking the process parameters with the parameters of the casting structure with different wall thicknesses. Metallographic examinations of the castings were carried out using a light microscopy, SEM, and EDS analysis. The fraction of the phases α(Al), the size of dendritic cells, and the size of silicon particles, in the cross-sections of the castings with wall thickness of 3, 6, and 11 mm, respectively, were determined.