جستجوی مقالات مرتبط با کلیدواژه « forming force » در نشریات گروه « مواد و متالورژی »

Incremental forming is one of the new forming methods. Single-point incremental forming (SPIF) has shown significant potential for forming complex metal parts. In the single-point incremental forming, a spherical tool head moves along a pre-defined path to form the desired geometry. The aim of this study is to optimize the fracture depth and forming forces of the three-layer metal-polymer sheet by using the single-point incremental forming process. By using response surface methodology (RSM), a series of experiments were designed in which tool diameter, step down and spindle speed were considered as process input parameters. The influencing parameters in fracture depth and forming forces have been identified by using statistical tools (response table, main effect diagram and ANOVA). Analysis of variance was used to show potential differences between the means of variables by testing the population value in each sample, which enables it to show the effects of input variables on output variables. The results show that the forming forces increased and the formability decreased by increasing the step down and the tool diameter. The highest forming force is 1476 N and the lowest value is 1045 N. Similarly, the highest fracture depth is 8.8 mm and the lowest is 7.1 mm. The best conditions are achieved when spindle speed is 2340.9 rpm, tool diameter is 7.51978 mm, and vertical step is 0.329552 mm. In this condition, the fracture depth is 8.50552 mm and the forming force is 776.03 N.

Single point incremental sheet forming is a die-less forming technology in which the sheet metal is formed progressively by the movement of a tool in the specified path. In this paper, the single point incremental forming of the AA3105-St12 two-layer sheet is studied through numerical and experimental approaches. Numerical simulation of the process is done based on the finite element method. The validity of the numerical model is evaluated via a comparison between the obtained numerical and experimental results. The force applied to the forming tool, the thickness distribution of formed sheets, and the maximum thinning that occurred in aluminum and steel layers were studied. The effects of the parameters of the two-layer sheet including total thickness, thickness ratio of layers, and arrangement of layers were investigated as well. The results showed that regardless of the contact of the steel or aluminum layer with the tool, increasing the ratio of the thickness of the steel layer to the thickness of the aluminum layer reduces the thinning in the aluminum layer and increases it in the steel layer. Hence, thinning becomes more severe in each layer when it is in contact with the forming tool.

Equal channel angular pressing (ECAP) process of AA7075 billet with the copper casing is comprehensively investigated. Firstly, ECAP process is simulated based on finite element method (FEM) in ABAQUS software and then is verified in comparison to the experimental data. The design of experiments using response surface methodology (RSM) is performed in order to investigate the processing parameters. The main effect of four considered parameters (channel angle, corner angle, friction coefficient and thickness of casing) on the maximum required force and strain was studied. Also, the regression models for estimating the maximum forming force and strain are represented in high reliability using analysis of variance (ANOVA). The results indicated that channel angle by 93.5% of contribution is the most effective parameter on the required forming force. It is concluded that the thickness of copper casing does not affect the forming force. Also, all terms of the presented regression model are effective on the strain value, according to the obtained results. Based on ANOVA results, channel and corner angel are the most effective parameters on the strain by 80 and 16% of the contribution, respectively. Also, the friction coefficient and the thickness of copper casing have almost no significant effects on the strain.

In this research, two new methods that improve the drawing depth of deep-drawing processes have been introduced. In the first technique, by creating ridges on the punch surface, the stress concentration is decreased on the blank near the punch edge, in turn increasing the drawing depth. The second method is based on the principle of reducing resistant force in the flange area between the die, the blank-holder and the blank that can decrease the required forming energy. By using the ridges on the flange surfaces of die and blank-holder, the contact surface is reduced, which in turn can decrease the force required for blank forming. The simulation results of finite elements are compared to the experimental data. It is found that the ridged punch may delay the blank rupture and significantly raise the drawability.

The mechanism of Single Point Incremental Forming (SPIF) process is based on localized plastic deformation of a sheet metal using a hemispherical-head tool that follows the path programmed into the controller of a CNC milling machine. In this process, no die is used under the sheet metal for support. The researchers' findings show that by applying ultrasonic vibration in forming processes, metallic samples are subjected to plasticization transiently and considerably. The beneficial results of applying ultrasonic vibration in the forming processes are due to volume and surface effects that are related to the change in the properties of material and change of frictional conditions, respectively. In this article, the Ultrasonic Vibration-assisted Single Point Incremental Forming (UVaSPIF) process was simulated in finite element software. The results of numerical analysis showed that ultrasonic excitation of the forming tool and increasing of the vibration amplitude reduced the friction force and the vertical component of forming force. In the following, the results of the simulation process were compared with the experimental results at a frequency of 20 kHz and 7.5 μm vibration amplitude. The study of the results showed that there was a very good agreement between the values of the vertical component of the forming force resulting from the numerical analysis and the experimental test.

Single point incremental sheet forming (SPISF) has demonstrated significant potential to form complex sheet metal parts without using component-specific tools and is suitable for fabricating low-volume functional sheet metal parts economically. In the SPIF process, a ball nose tool moves along a predefined tool path to form the sheet. This work aims to optimize the formability and forming forces of Al/Cu bimetal sheet formed by the single-point incremental forming process. Two levels of tool diameter, step size, tool path and sheet arrangement were considered as the input process parameters. The process parameters influential in the formability and forming forces have been identified using the statistical tool (response table, main effect plot and ANOVA). Analysis of variance (ANOVA) was used to indicate potential differences among the means of variables by testing the amount of population within each sample, which enabled it to show the effects of input variables on output ones. A multi response optimization was conducted to find the optimum values for input parameters by response surface methodology (RSM), and the confirmatory experiment revealed the reliability of RSM for this approach.

Deep drawing of two-layer sheet is a suitable way to achieve product with a desired shape and desired properties in sheet metal forming technology. Control of deep drawing parameter such as thinning is the most important challenge in this process. The most difficult part of this challenge is differences in material properties and geometry of each layer. In this paper, numerical approach has been exploited to plan and control of two layer deep drawing process. For this purpose, the three-dimensional (3D) finite element has been used. ST14– Al1100 (A.I. and S.I. lay-up) were selected as materials of two layer sheet metal. The results of simulation have been validated with experiments. Based on numerical study, effect of process parameters on the percentage of thinning, maximum plastic strain, rupture, required forming force and blank holder force (BHF) has been studied. This study has also been done on one-layer sheet metal and differences between deep drawing of one-layer and two-layer sheets have been comprehensively investigated. The results showed that maximum thinning is occurred in the upper layer of die radial region as well as in the lower layer of punch radial region. Also, the maximum equivalent plastic strain in the lower layer is more than the maximum of equivalent plastic strain in the upper layer.