جستجوی مقالات مرتبط با کلیدواژه « شکل‎دهی غلتکی سرد » در نشریات گروه « مکانیک »

The roll forming of an asymmetrical channel section is associated with a twisting defect, but this defect also occurs in a symmetrical section whose holes are asymmetrical. Therefore, first, a finite element model was presented to investigate the process. By designing the full factorial method, the important factors affecting the twisting defect and the effect of each during the cold roll forming process have been investigated. In the end, it was concluded that the thickness of the sheet and the diameter of the holes are the most important factors affecting the twisting defect. It was concluded that the greater the difference in the diameter of the holes on both sides of the channel, the higher the amount of twisting defect. For the forming angle of 45 degrees, by increasing the thickness of the sheet from 2 mm to 3 mm, the twist angle of the piece increased from 1.5 degrees to 2.5 degrees. According to the behavior of the metal, a series of experimental tests were designed and the effect of the hole diameter factor on this defect was determined. Appropriate matching of experimental and numerical results indicates reliable and verifiable numerical results.

One of the important sections of cold roll forming lines is the shearing of profiles, which is usually performed as the guillotine shearing for open profiles. Despite the importance of shearing quality on the assemblability of the open profiles, few researches have been done on their shearing operation. In this paper, the guillotine shearing of a complex open profile, door frame, was investigated. For this purpose, the guillotine shearing of this profile was simulated in Abaqus software and the effects of the important process parameters on the shearing quality were determined. In the experiments, the profiles were initially annealed to remove residual stresses produced during deformation and then were sheared. The experimental and finite element–predicted shearing cross-section were compared and the shearing defects were analyzed. The comparison revealed a good agreement and confirmed the finite element model. The results showed the increase of the shearing angle and the clearance between dies and profile reduces the shearing quality. In addition, the increase of the clearance between dies and profile and the clearance between dies reduces the shearing force. Finally, the best shearing conditions were proposed based on the results.

This paper has focused on the joint type effect on the creation and gradient temperature of weld metal in the welded pipe. The main purpose is to reduce the heat generated in the weld metal and the temperature gradient in the pipe thickness direction, by joint type Changes. To obtain a suitable joint type, different joint types have been studied experimentally and numerically by Comsol software. By using destructive and non-destructive tests, the mechanical properties, such as the ultimate tensile strength and the elongation of the weld metal, have been investigated. Evaluation of the metallurgical properties, for instance, the grain boundary and the enlargement of the heat affected zone, has also been examined. The results show that changing the joint type reduces the generated temperature 19% and the temperature gradient in the weld metal. Follow it, the grain boundaries increase and a rectangular weld metal profile is created. Increases the ultimate tensile strength 5% but not obvious change in elongation.increases the ultimate tensile strength by 5%.

springback is one of the challenges in the final shape of the steel in the cold roll forming process of the steel plate.The precision of the simulation of metal sheet forming processes for prediction of the springback depends on the stress-strain relationship, the yield function and the selected hardening model and the anisotropy of the material. In this paper, using alternating tension-compression experiment and using simulation in software LS-OPT, the variables of the Yoshida-Uemori hardening model have been obtained for St37 steel. Springback in the final shape of steel plate deformation is a challenge of the roll forming process. Since consideration of the hardening law is important in the springback, various models of hardening law are proposed for more accurate prediction of material behavior. One of the most accurate models in predicting metal behavior is the Yoshida-Uemori hardening model. The experimental tests were also carried out as well as the simulations in the Ls-dyna simulation software with and without Yoshida-Umari hardening. It was shown that the prediction of springback with using the Yoshida-Umari model was more accurate.

In this research, the twist and the longitudinal bow defects were studied by finite element analysis in the asymmetrical channel sections. Effects of the geometrical properties including the strip thickness, the web width, and the flange width were investigated on the above effects. Some experiments were performed on an industrial roll-forming machine to verify the accuracy of the finite element model. The results showed that the twist angle decreases with the increase of both strip thickness and web width. However, the twist angle increases with the increase of flanges width. Also the variations of the longitudinal bow height are similar to those of the average residual longitudinal strain of both flange edges.

The Cold roll forming is a complex forming process which quality of its products is highly dependent on the process parameters. The edge wrinkling defect is one of the common defects in the cold roll forming process of wide profiles. Edge wrinkling leads to several problems such as decrease in dimensional quality¡ wearing of forming rolls due to contact with the buckled edge and non-uniform distribution of forming forces through the production line. In order to investigate the edge wrinkling defect in this study¡ the finite element simulation and experimental tests were used. At first¡ for validation of simulation results¡ one model in exact in accordance with experimental set up and with one holding station and one forming station to produce one trapezoidal profile was created. Then by simulating this process in Abaqus software and comparing the longitudinal strain in simulation and experimental results¡ the numerical model was validated. After verifying the numerical model¡ it was used for simulating a similar profile with two channels in transversal direction and in three forming stations and then the effect of sheet material (yield stress and work hardening exponent)¡ strip thickness and distance between the roll stands are investigated on the edge wrinkling defect of products. Results of this study show that wrinkling increases with the yield stress increase¡ but decreases with increase in work hardening exponent¡ strip thickness and distance between the roll stands.

Cold roll forming process is a process that a strip passes through a collection of rotary rolls to be converted to a desired profile. Hat channel section is one of the roll forming products that has many applications in various industries especially in automotive industry. In the present study proper flower pattern for production of hat channel section is determined. Proper flower pattern in the cold roll forming process can prevent some defects such as bowing and wrinkling. Flower pattern of hat channel section was predicted by ABAQUS 3D simulation. Longitudinal strain is one of the results of simulation which was used as a criterion for product quality evaluation. Results of simulations were verified by experimental tests for first forming stand of hat channel section which were done in the present study. In the experimental part of present study, effect of roll angle was investigated on the bow defect of product. Experimental and numerical results of this study have a good agreement. Numerical and experimental of this study showed that bow defect increases by increasing bending angle.

Cold roll forming is one of the most complex forming processes in which quality of products is highly dependent on the process parameters. Estimation of forming torque and power in the cold roll forming process is one of the most important parameters. Eective parameters on the forming torque and forming power are investigated in the present study. These parameters are rolls geometry, sheet thickness, sheet width, strength of sheet, andformingangle. So, theformingprocessissimulated in the nite element software Abaqus for both
at and angled geometry of the top roll. Simulation results show that with yield strength, sheet thickness, and increase of roll angle, forming torque and power will increase. Also, the rolls force increase and the forming torque decrease with sheet width increasing. The results of this study show that the forming torque and power for the top roll with
at geometry is lesser than the top roll with angled top roll. Due to easier process of manufacturing of
at rolls, this type of rolls geometry can be used for channel sections. The eect of thickness and width of sheet is investigated experimentally on the forming torque and power. Numerical results are veri ed by experimental results of the present study. Results show that forming torque and power increase with yield strength, then forming angle and sheet thickness increase as well. Therefore, engineers can consider the eects of these parameters on the forming torque, forming power, and selecting proper type of motors. Edge longitudinal strain of numerical simulations of the present study is veri ed by numerical results of Lindgeren, 2007 [8]. This comparison shows that numerical results of the present study is near to the results of Lindgeren, 2007. Results show that edge longitudinal strain decreases with the increase of yield strength. These results also show that the increase of edge longitudinal with the increase of roll forming angle.

Cold roll forming is a sheet metal forming process that it looks simple, but the lot of parameters that influence this process and interaction of this parameters over each other's are challenges. One of the defects that affect the quality of the products in this process, is the thinning. This defect occurs mainly in bending zone is affected by the parameters of the process. Parameters such as forming angle, sheet thickness, roller diameter, roller corner radius and distance between stations have a major effect on the occurrence of fructure. In this paper, the roller corner radius, forming angle and sheet thickness have been investigated to the thinning defect in this process. Cold roll forming experiments for this study has been done and the Abaqus finite element simulation software used to predict the thinning in the bending zone. St52 steel sheet was used to experiments. The results showed that from three parameters investigated in this paper the radius of the corner of 5mm with 41.7% and forming angle of 600 whit 40.7% have the greatest effects on this defect. In fact for reduction of transverse strains in bending zone it is better that forming angle decrease so the number of forming stations increase.

Cold roll-forming is a process in which a metal sheet will get its required section form by passing it through a series of rotating rollers. The pre-notched sections have frequent usage in different industries. The problem with these products is about deformation of the holes after completion of the forming process. Also, there are problems like edge waves, buckling, bending, distortion of the holes, etc. In order to analyze and predict the important parameters in deforming the ellipsoidal holes during the cold roll-forming of U-channel section, a three-dimensional model with finite element has been taken into account. Furthermore, for modelling of the sheets. The effective parameters of forming the U-channel section with pre-notches such as the minor and major hole diameter, hole spacing, the distance of holes from the flange edge, thickness and the material were intended. Furthermore, by usage of response surface methodology, the set of tests were designed. Afterward, a set of out-put parameters such as: edge buckling, the wave of the holes, the change of the hole spacing size, the change of the distance of the holes from the flange edge, the change of the hole size were considered. The output parameters were measured and the chart of experiment design were completed. Then, by applying ANOVA, the accuracy of the statistical results was obtained. Also, by comparison of the results with experimental study, the accuracy of the simulated models was analyzed. the effect of the significant parameters has been extracted both in statistical form and mathematical functions.

The forming torque is one of the most important information needed for starting-up a roll-forming line. In this paper the effect of profile geometric parameters on the forming torque is investigated, in roll-forming of symmetric channel section. The parameters which are to be studied include sheet thickness, fold angle, flange width and web width. To end this, the torque is predicted by a neural network algorithm. Finite element simulation has been utilized to train the neural network and the simulation results were validated, comparing with existing experimental results. Then an equation is proposed to determine forming torque. The results show that forming torque is considerably affected by sheet thickness, fold angle and flange width, while the effect of web width is negligible.

One of the most important issues in the review of cold roll forming process of metals is estimation of required torque. The optimum production line can be designed by determining the effective parameters on torque. Some of these parameters are sheet material and thickness, bending angle, lubrication conditions, rolls rotational speed and distance of the stands. The aim of this study is to predict amount of required torque considering the factors influencing torque, including thickness, yield strength, sheet width and forming angle using artificial neural network. So the forming process was 3D simulated in a finite element code. Simulation results showed that with increase of yield strength, thickness and forming angle, applied torque on rolls will increase. Also the increase in sheet width -assuming constant web length- will decrease the torque needed for forming. The effects of thickness and sheet width were experimentally investigated which verified the results obtained by finite element analysis. A feed-forward back-propagation neural network was created. The comparison between the experimental results and ANN results showed that the trained network could predict the required torque adequately.

Cold roll forming is a sheet metal forming process in whichthe bending occurs gradually in several forming steps from an undeformed strip to a finishedprofile. Althoughsimple appearance, the process is influenced by several parametersthat complicate the process design and control such as springback.
The main purpose in this article is to determine a simple criterion for the springback and to introduce a fast solution to obtain it and therefore artificial neural network was proposed for achiving this goal. Cold roll forming of a channel section in the first station was simulated by a commercial package named “Msc Marc Mentat”. The data obtained from the finite element simulations were used as training and testingsetsfor neural networks. Perfect performance of neural network was proved when the neural network outputs were compared with the testing set that did not exist in the training set.

Cold roll-forming is a process in which the roll of sheet is formed by passing continuously through the set of rotary rollers without changing thickness in a cool way until it is formed to the desired profile. In this paper a parametric study on the section twist angle in roll-forming the non-symmetric channel is presented, using finite element simulation. At first finite element simulation results are validated by comparing the computed longitudinal strain, near the flange edge, with previously published experimental strains, for a special symmetric channel section. Here symmetric channel section was considered for verifying the finite element results, because of the lack of previous researches on non-symmetric channel section. Then by repeating the finite element simulation for similar section but with different flange width and changing the geometrical parameters such as flange width difference, sheet thickness and profile angle the effect of these parameters on twist angle is investigated. Investigating the results show that section twist angle is increased by decreasing the profile angle and sheet thickness and by increasing the flange width difference. All simulations were carried out using the commercial software ABAQUS 6.7.

In this paper, buckling of orthotropic rectangular plates under different loadings was investigated. For this reason, governing buckling equations for an isotropic plate were modified by applying constitutive equations of orthotropic materials. After obtaining the equations of orthotropic plates, Generalized Differential Quadrature method (GDQM) was applied on buckling equations and thus a set of Eigen value equations resulted. In order to solve this Eigen value problem, a computer program was developed using MATLAB software in a way that the influence of different parameters such as length to width ratio (aspect ratio), the number of layers, the angle of layers arrangement, material of layers, kind of loading and boundary conditions were included. A buckling load factor was calculated for simply supported and clamped supported plates. The results of GDQ method were compared with reported results from Rayleigh – Ritz method and with results from solving the Finite element using ANSYS 8.0 software. The comparison showed the accuracy of obtained result clearly.