Showing papers on "Stamping published in 2022"

Optimization of Heat Exchange Plate Geometry by Modeling Physical Processes Using CAD

Abstract: This article presents the possibility of evaluating the efficiency of the heat exchange element with a special stamping plate, which is based on the results of computer simulation. The method is based on a comparative analysis of convective heat transfer models implemented in ANSYS using a k-ε turbulence model. To conduct the study, 3D models of three different types of cavity geometry formed between two heat exchange plates (flat plate, chevron plate, and plate with conical stampings) were built. Simulation was performed by finite element analysis in ANSYS for channels formed by the three types of plates, one of which is a new configuration. The results of hydrodynamic and heat exchange parameters allowed for establishing the efficiency of convective heat exchange for plates of known structures and to compare them with the proposed one. It was found that the plates with conical stamping form the smallest channels through which the fluid moves. The velocity of the coolant is uniform throughout the cross section of the channel and equal to 0.294 m/s; the value of the heat transfer coefficient is the largest of the three models and is 5339 W/(m K), while the pressure drop is 1060 Pa. Taking into account the simulation results, the best heat transfer parameters were shown by the channel formed by plates with conical stamping and the highest pressure drop. To increase the efficiency, indicated by the ratio of heat transfer coefficients to hydraulic resistance, the geometry of the plate with conical stamping was optimized. As a result of optimization, it was found that the optimal geometric parameters of the heat exchange plate with conical stamping were achieved at a 55° inclination angle and 1.5 mm height for the cone. The results of this study can be used in the design of heat exchange elements of new structures with optimal parameters for highly efficient heating of liquid coolants.

A Review on Hot Stamping of Advanced High-Strength Steels: Technological-Metallurgical Aspects and Numerical Simulation

Abstract: The production of ultra-high strength automotive components requires a multi-directional approach. Hot stamping combines both forming and heat treatment processes to obtain a usually martensitic structure of complicated shaped automotive parts. The preparation for production using hot stamping must involve the latest methods of numerical analysis of both temperature changes and forming, which are applied for an increasing range of materials used. In this paper, the current state of knowledge about the basics of hot stamping, used technological lines, and the current state of material used with applied heat treatments and possible coatings have been reviewed. Moreover, the numerical modeling process has been described. The most important aspects of process automation, including the use of digital twins for simulation and optimization of operational kinetics of the robots accomplishing the production process, analysis and minimization of time of production cycles, and searching for weak operational points of the control systems and for real time visualization of operation of complete line, are considered. The digital twins and corresponding numerical models enable the symmetrical design of real production lines. The details of heat treatment profiles with so called tailored zone heat treatment are provided. Hot stamping is a dynamically developing technology as evidenced by the increasing range of materials used, also from the 3rd generation of advanced high strength (AHSS) steels. It starts to combine forming of symmetric or asymmetric elements with more complex heat treatment processes as required for dual phase (DP) stainless steels or the newest generation of high-strength and ductile medium-manganese steels.

Relating wear stages in sheet metal forming based on short- and long-term force signal variations

Abstract: Abstract Monitoring systems in sheet metal forming cannot rely on direct measurements of the physical condition of interest because the space between the die component and the material is inaccessible. Therefore, in order to gain further insight into the forming or stamping process, sensors must be used to detect auxiliary quantities such as acoustic emission and force that relate to the physical quantities of interest. While it is known that changes in force data are related to physical parameters of the process material, lubricant used, and geometry, the changes in data over large stroke series and their relationship to wear are the subject of this paper. Previously, force data from different wear conditions (artificially introduced into the system and not occurring in an industry-like environment) were used as input for clustering and classifying high and low wear force data. This paper contributes to fill the current research gap by isolating structural properties of data as indicators of wear growth to quantify the wear evolution during ongoing production in industry-like scenarios. The selected methods represent either established methods in sheet metal forming force data analysis, dimensionality reduction for local structure separation or generic feature extraction. The study is conducted on a set of four experiments with each containing about 3000 strokes.

Research of stamping of unequal channels. Part 6. Fibrous structure during channel extrusion. 1. Basic provisions

Abstract: The importance of predicting the fibrous structure of an extruded product is substantiated. Some erroneous statements of well-known works on channel extrusion are considered. The sequence of a correct analytical study of the fibrous structure is formulated. Keywords: forging, extrusion, misalignment of punch and die, plain strain, fibrous structure.mt13@bmstu.ru

Application of integrated drilling and stamping technology in gas extraction through layer drilling

Abstract: In coal mine gas extraction in China, the current hydraulic permeability enhancement measures generally have complex processes, low adaptability, long operation time, and high labor intensity. This makes it challenging to meet the requirements of coal mining enterprises for safe and efficient mining, and there is an urgent need to develop new technologies to enhance gas extraction and production. This paper proposed an integrated drilling and stamping technology to enhance gas extraction and production and integrates drilling, hydraulic jet fracturing, and hydraulic punching to enhance the permeability of coal seams. A field test was conducted using the specially-developed integrated drilling and stamping equipment to extract gas from the 16101 bottom pumping lane penetration hole in the Jiulishan Mine, Jiaozuo, Henan. The test results show that compared with the hydraulic punching technology previously used in the mine, the punching time of the soft coal seam was shortened by 66–75%, the coal output was increased by 1.7 times, and the punching hole aperture was increased by 1.3 times. Hydraulic injection fracturing was successfully performed to increase the permeability of the hard coal seams, and the fracturing formed a shot hole depth of 345–539 mm. After the integrated drilling and stamping of the drill holes, the coal output, gas extraction concentration, pure gas extraction volume, and coal seam permeability coefficient increased by 2.4, 2.2, 4, and 37.3 times, respectively. The gas flow decay coefficient of the drills holes was also further reduced, which significantly improved the extractionefficiency. Thus the integrated drilling and stamping technology can transform the process of gas extraction from regular extraction to quick, economic, pure, and clean extraction. Thus, this technology has large applicable value for underground gas management in coal mines.

Investigation of the effect of initial states of medium-Mn steel on deformation behaviour under hot stamping conditions

Abstract: Medium-Mn (MMn) steels have received much research attention recently because their low austenitisation temperature enables low-temperature hot stamping (LTHS). However, the effect of the initial state of the material on the hot stamping performance is still unknown. In this study, the effect of different initial states on the deformation behaviour of a typical MMn steel during uniaxial tensile testing under LTHS conditions (deformation at 500–600 °C under strain rates of 0.01–1 s −1 ) are investigated using a Gleeble 3800 materials simulator; the final mechanical properties after austenitising and quenching are also examined. The microstructure of each material state before and after the LTHS heating cycle is characterised using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Of the three states investigated the hot rolled and annealed (HRA) state shows the best hot deformation performance represented by larger strain hardening exponent and higher total elongation, followed by the cold-rolled (CR) state, with the cold-rolled and annealed (CRA) state exhibiting the worst performance. The final mechanical properties, however, are very similar among the three states. In addition, the yield point phenomenon is found during hot deformation in both the CR and CRA states, and absent in the HRA state. The hot deformation behaviour has been discussed in terms of differences in microstructural properties, namely the grain size and its degree of heterogeneity.

Friction Characteristics Analysis of Symmetric Aluminum Alloy Parts in Warm Forming Process

Abstract: There are many typical symmetric large plastic deformation problems in aluminum alloy stamping. Warm stamping technology can improve the formability of materials and obtain parts with high-dimensional accuracy. Friction behavior in the stamping process is significant for the forming quality. An accurate friction coefficient is helpful in improving the prediction accuracy of forming defects. It is hard to obtain a unified and precise friction model through simple experiments due to the complicated contact conditions. To explore the effect of friction behavior on the forming quality, warm friction experiments of the AA6061 aluminum alloy and P20 steel with different process parameters were carried out using a high-temperature friction tester CFT-I (Equipment Type), including temperatures, the interface load, and sliding speeds. The variation curves of the friction coefficient with various parameters were obtained and analyzed. The results show that the friction coefficient increases with temperature and decreases with the sliding speed and load. Then, the influences of process parameters on the surface morphology of the samples after friction were observed by an optical microscope; adhesive wear occurred when the temperature increased, and the surface scratch increased and deepened with the increase in the load. Finally, the friction coefficient models of the speed and load were established by analyzing the data with Original software. Compared with the experimental and the finite element analysis results of the symmetrical part, the errors of the velocity friction model in thickness and springback angle are less than 4% and 5%, respectively. The mistakes of the load friction model are less than 6% and 7%, respectively. The accuracy of the two friction models is higher than that of the constant friction coefficient. Therefore, those coefficient models can effectively improve the simulation accuracy of finite element software.

Evaluation of deformability of material of preparations in direct and reverse extraction by rolling stamping method

Abstract: The article presents the results of development and research of various technological schemes of the process of stamping by rolling cylindrical and conical rolls to obtain complex profile workpieces. It is shown that the achievement of significant dimensions of the various elements of the workpiece is possible by providing a directed flow of metal by changing the relative position of the roll and the workpiece. The most effective rolling operations are landing, settling, unloading, reverse and direct extrusion. The paper focuses on the analysis of operations of reverse and direct extrusion to obtain complex profile blanks with developed, including thin-walled elements. Since the technological capabilities depend on the deformability of the material, the analysis of the stress-strain state of the workpieces was performed using the method of grids, hardness measurement and microstructural analysis. The main result of the analysis was the construction of ways to deform the particles of the workpiece material in the coordinates "deformation intensity - stress index". Zones of blanks that are deformed in the conditions of "rigid" stress state are established, therefore for these zones the deformability of metals was assessed using the criteria of phenomenological theory. In addition, the assessment of deformability was also performed for areas with the maximum degree of deformation of the material. The manufacture of thin-walled elements of the workpiece, using the operation of reverse extrusion, is accompanied by the appearance of significant contact stresses. To prevent the roll from being pushed out of the workpiece and forming elements with a constant thickness, support rollers should be provided. In the case of direct extrusion, the increase in contact stresses requires the application of additional measures to increase the strength of the tool.

Experimental research into microgroove stamping by laser-induced cavitation

Abstract: This paper proposes a method for forming a microgroove using laser-induced cavitation bubbles. The laser energy, foil thickness, and the initial position of the cavitation bubbles were varied to investigate the micro-formability of aluminum foils. The surface morphology of the microgroove formed in the metal foil was measured by a laser scanning confocal microscope and a scanning electron microscope. The laser-induced cavitation bubbles were recorded by a high-speed camera. The experimental results indicate that the depth and surface roughness increased with the laser energy. For the focal distance to Al foil of −0.9 mm, the surface of the metal foil was severely ablated and oxidized. The roughness decreased as the distance between the bubble center and the top of the guide hole increased. The forming depth of the groove is inconsistent, since the middle had a greater depth than the ends. This research may lead to a new method for stamping metal materials.

A Novel Method for Friction Coefficient Calculation in Metal Sheet Forming of Axis-Symmetric Deep Drawing Parts

Abstract: Friction is one of the important factors in sheet metal forming. It greatly affects dynamic behaviors of metal sheets and stress and strain distributions in the metal sheets. In this study, deformation characteristics, stress–strain distribution, and change law of symmetrical parts in the process of deep drawing are analyzed using a new theoretical model based on the plastic flow law and partitioning the forming area. In the model, the least-square method is used to linearize the friction coefficient in nonlinear problems and reverse the calculation of friction coefficients to interpret the friction coefficient. To evaluate the model, the friction coefficient in sheet metal drawing of axis-symmetric deep drawing parts under various friction conditions was measured using a self-developed measuring system. The comparison between the experimental results and the calculation using the model shows a good agreement. The results show that the drawing force increases with the increase in punch depth; the friction coefficient decreases with the rise in punch depth. The friction coefficient obtained by fitting is relatively stable, and the average error is less than 3%. Using the friction coefficient model in finite element simulation analysis, it shows that the thickness and blank shape errors are less than 5%. The novel method studied in this paper shows great significance in support for theoretical research, numerical simulation research, and sheet metal stamping performance evaluation.

Topology optimization and lightweight design of stamping dies for forming automobile panels

Abstract: Accurate prediction of deformation and stress distribution on stamping die components is critical to guarantee structure reliability and lightweight design. This work aims to propose a new method for predicting die structural behaviors and reducing total weight based on numerical simulation. Sheet metal forming simulation was firstly conducted to obtain the accurate forming contact force. The linear static structural analyses under different load conditions were performed to investigate the deformation and stress distribution of the die structure. Topology optimization was employed to realize the lightweight design on the premise of ensuring structural safety. According to the manufacturing techniques and initial optimization results, the die structure was redesigned to guarantee the manufacturability of the new structure. The proposed methodology has several advantages of decreasing model scale, precluding intricate contact condition settings as well as time saving. A long beam stamping die used for forming automobile panels was selected to validate the proposed methodology, and about 18% weight reduction was achieved.

Universal Bifacial Stamping Approach Enabling Reverse-Graded Ruddlesden-Popper 2D Perovskite Solar Cells.

Abstract: Quasi 2D perovskite solar cells (PSCs) are promising light absorbers that overcome the inherent instabilities of 3D perovskites. High-performance and stable 2D PSCs require careful control over the crystallographic orientation and phase distribution. This study introduces a simple and universal bifacial stamping method to obtain highly oriented perovskite crystals with a reverse-graded structure, where the low-n-value 2D perovskite phases are located mainly at the film surfaces. Bifacial stamping of 3D perovskite films atop the 2D films enables incorporation of 2D spacer cations into the 3D film surfaces, forming reverse-graded quasi-2D perovskite films. During stamping, suppressed evaporation of the precursor solvent induces heterogeneous nucleation from the contact interface between the 2D and 3D films, resulting in well-crystallized perovskite films having out-of-plane alignments with respect to the substrate. Thus, a highly oriented and reverse-graded quasi-2D perovskite with an average n value of 18 is obtained with power conversion efficiency exceeding 17% and high open-circuit voltage of 1.11 V for iso-butylammonium (iso-BA)-based (iso-BA2 MAn -1 Pbn I3 n +1 ) PSCs. The unencapsulated device retains 92% of its initial efficiency after aging at 40 ± 5% relative humidity for 1200 h. This work provides a new strategy for fabricating highly oriented and phase-controlled quasi-2D PSCs.

Control of defects in the deep drawing of tailor-welded blanks for complex-shape automotive panel

Abstract: With the development of lightweight vehicles, tailor-welded blanks (TWBs) are being increasingly used in the automotive industry. Splitting and wrinkling are the main defects occurring during the deep drawing of TWBs. Accordingly, in this paper, a new method to control the forming defects is introduced in the forming process of TWBs. The microstructure and mechanical properties of TWBs are characterised by metallography and tensile tests. Finite element analysis is conducted for an automobile rear door inner panel made of TWBs to analyse the deep drawing. Edge and notch cutting are introduced to address forming defects and reduce the number of stamping tools. The thinning index, thickening index and minimum distance between the material draw-in and trimming lines are defined as the measurable index to analyse the numerical results. Orthogonal experiments, numerical simulations and multiobjective experiments are conducted to optimise the forming parameters. The proposed method and optimised parameters are verified through experiments, the results of which are essentially consistent with the numerical simulation. Indeed, the proposed method can provide guidance in controlling defects associated with the deep drawing of TWBs for complex-shape automotive panels.