A Finite Element Based Die Design Algorithm for Sheet Metal Forming on Reconfigurable Tools

2000 ◽  
Author(s):  
Simona Socrate ◽  
Mary C. Boyce
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Design Procedure ◽  
Die Design ◽  
Tool Geometry ◽  
Fe Model ◽  
Stretch Forming ◽  
Design Algorithm ◽  
Die Surface ◽  
Actual Geometry

Abstract Tooling cost is a major contributor to the total cost of small-lot production of sheet metal components. Within the framework of an academic/industrial/ government partnership devoted to the development of a reconfigurable tool for stretch forming, we have implemented a Finite Element-based procedure to determine optimal die shape. In the reconfigurable forming tool [1], the die surface is created by the ends of an array of square pins, which can be individually repositioned by computer driven servo-mechanisms. An interpolating polymer layer is interposed between the part and the die surface to attain a smooth pressure distribution. The objective of the die design/algorithm is to determine optimal positions for the pin array, which will result in the desired part shape. The proposed “spring-forward” method was originally developed for matched-die forming [2, 3] and it is here extended and adapted to the reconfigurable tool geometry and stretch forming loading conditions. An essential prerequisite to the implementation of the die design procedure is the availability of an accurate FE model of the entire forming operation. The particular nature of the discrete die and issues related to the behavior of the interpolating layer introduce additional challenges. We have first simulated the process using a model which reproduces, as closely as possible, the actual geometry of the discrete tool. In order to optimize the delicate balance between model accuracy and computational requirements, we have then used the information gathered from the detailed analyses to develop an equivalent die model. An automated algorithm to construct the equivalent die model based on the discrete tool geometry (pin-positions) is integrated with the spring-forward method, to generate an iterative die design procedure that can be easily interfaced with the reconfiguring tool. The success of the proposed procedure in selecting an optimal die configuration is confirmed by comparison with experimental results.

A Finite Element Based Die Design Algorithm for Sheet-Metal Forming on Reconfigurable Tools

2000 ◽  
Vol 123 (4) ◽  
pp. 489-495 ◽  
Author(s):  
Simona Socrate ◽  
Mary C. Boyce
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Design Procedure ◽  
Die Design ◽  
Tool Geometry ◽  
Stretch Forming ◽  
Design Algorithm ◽  
Die Surface

Tooling cost is a major contributor to the total cost of small-lot production of sheet metal components. Within the framework of an academic/industrial/government partnership devoted to the development of a reconfigurable tool for stretch forming, we have implemented a Finite Element-based procedure to determine optimal die shape. In the reconfigurable forming tool (Hardt, D. E. et al., 1993, “A CAD Driven Flexible Forming System for Three-Dimensional Sheet Metal Parts,” Sheet Metal and Stamping Symp., Int. Congress and Exp., Detroit, MI, SAE Technical Paper Series 930282, pp. 69–76.), the die surface is created by the ends of an array of square pins, which can be individually repositioned by computer driven servo-mechanisms. An interpolating polymer layer is interposed between the part and the die surface to attain a smooth pressure distribution. The objective of the die design algorithm is to determine optimal positions for the pin array, which will result in the desired part shape. The proposed “spring-forward” method was originally developed for matched-die forming (Karafillis, A. P., and Boyce, M. C., 1992, “Tooling Design in Sheet Metal Forming using Springback Calculations,” Int. J. Mech. Sci., Vol. 34, pp. 113–131.; Karafillis, A. P., and Boyce, M. C., 1996, “Tooling And Binder Design for Sheet Metal Forming Processes Compensating Springback Error,” Int. J. Tools Manufac., Vol. 36, pp. 503–526.) and it is here extended and adapted to the reconfigurable tool geometry and stretch forming loading conditions. An essential prerequisite to the implementation of the die design procedure is the availability of an accurate FE model of the entire forming operation. The particular nature of the discrete die and issues related to the behavior of the interpolating layer introduce additional challenges. We have first simulated the process using a model that reproduces, as closely as possible, the actual geometry of the discrete tool. In order to optimize the delicate balance between model accuracy and computational requirements, we have then used the information gathered from the detailed analyses to develop an equivalent die model. An automated algorithm to construct the equivalent die model based on the discrete tool geometry (pin-positions) is integrated with the spring-forward method, to generate an iterative die design procedure that can be easily interfaced with the reconfiguring tool. The success of the proposed procedure in selecting an optimal die configuration is confirmed by comparison with experimental results.

scholarly journals The Effect of Swinging Ball Heads with Different Arrangements in Multi-Point Stretch-Forming Process

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 337 ◽  
Author(s):  
Jian Xing ◽  
Yan-yan Cheng ◽  
Zhuo Yi
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Sheet Metal ◽  
Strain Distribution ◽  
Finite Element Models ◽  
Stretch Forming ◽  
Forming Process ◽  
Forming Quality ◽  
Staggered Arrangement ◽  
Simulation Results

To improve the effect of multi-point stretch forming of sheet metal, it is proposed in this paper to replace a fixed ball head with a swinging ball head. According to the multi-point dies with different arrangements, this research establishes finite element models of the following stretch forming, i.e., fixed ball heads with conventional arrangement, swinging ball heads with conventional arrangement, swinging ball heads with declining staggered arrangement, and swinging ball heads with parallel staggered arrangement, and then numerical simulation is performed. The simulation results show that by replacing a fixed ball head with a swinging ball head, the surface indentation of the part formed was effectively suppressed, the stress and tension strain distribution of the part formed was improved, and the forming quality was improved; the thickness of the elastic pad was reduced, the springback was reduced and the forming accuracy was improved; and when the ball head was applied to a multi-point die with staggered arrangement, a better forming result was achieved, where the best forming result was achieved in combining the swinging ball heads with the multi-point die with a parallel staggered arrangement. Forming experiments were carried out, and the experimental results were consistent with the trend of numerical simulation results, which verified the correctness of the numerical simulation.

Sheet Metals Forming Die Design Using Finite Element Analysis and the Taguchi Method

2014 ◽  
Vol 621 ◽  
pp. 195-201
Author(s):  
Surangsee Dechjarern ◽  
Maitri Kamonrattanapisut
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Friction Coefficient ◽  
Taguchi Method ◽  
Finite Element Model ◽  
Sheet Metal ◽  
Element Model ◽  
Die Design ◽  
Forming Process ◽  
Element Analysis

Sheet metal deep-draw die is primarily constructed with draw bead, which is then modified based on trial and error to obtain a successful forming without splitting. This work aims at a robust design of forming die using numerical analysis and the Taguchi method. A three dimensional elastoplastic finite element model of a sheet metal forming process of SPCEN steel has been successfully developed using the material flow stress obtained from the modified Erichsen cup test. The model was validated with the actual forming experiment and the results agreed well. The influence of draw bead parameters on splitting and thinning distributions were examined using the Taguchi method. Four parameters, namely the friction coefficient, draw bead height, radius and shoulder radius were investigated. The Taguchi main effect analysis and ANOVA results show that the height and shoulder radius of the draw bead are the most important factor influencing the thinning distribution. Applying the Taguchi method and using the minimum thinning percentage as the design criteria, the optimum die design was identified as height, radius, shoulder radius and the friction coefficient of 4, 8, 8 mm and 0.125 respectively. The verified finite element model using the optimum die design was conducted. The predicted Taguchi response was within 5.9% from finite element analysis prediction. The improvement in the reduction of thinning percentage was 22.35%.

Design of Flexible Multi-Gripper Stretch Forming Machine by FEM

2011 ◽  
Vol 328-330 ◽  
pp. 13-17 ◽  
Author(s):  
He Li Peng ◽  
Mine Zhe Li ◽  
Qi Gang Han ◽  
Peng Xiao Feng ◽  
Hao Han Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Simulations ◽  
Simple Structure ◽  
Metal Sheet ◽  
Fe Model ◽  
Stretch Forming ◽  
Double Curvature ◽  
Better Than

In order to improve the performance of back drawing type of flexible multi-gripper stretch forming machine used for double-curvature metal sheet forming, back and down drawing type of flexible multi-gripper stretch forming machine was designed by finite element method (FEM), which has simple structure and cheap cost. The FE model of flexible multi-gripper stretch forming was established, and extensive numerical simulations of spherical parts for two kinds of flexible stretch forming machines were carried out. The variations of stress, strain, thickness and springback value of spherical parts for two kinds of drawing modes were analyzed. The numerical results show that the quality of spherical parts formed by the back and down drawing type of stretch forming machine is better than that by the back drawing type of stretch forming machine. This work provides a machine for developing the technology of stretch forming.

Study of Multi-Roll Stretch Forming Process Using Different Clamps

2010 ◽  
Vol 44-47 ◽  
pp. 2752-2756 ◽  
Author(s):  
Hao Han Zhang ◽  
Ming Zhe Li ◽  
Wen Zhi Fu ◽  
Zhi Qing Hu
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Opposite Direction ◽  
Critical Value ◽  
Finite Element Simulations ◽  
Stretch Forming ◽  
Forming Process ◽  
Wave Type ◽  
Tooth Type ◽  
Formed Part

Multi-Roll Stretch Forming process is a new flexible process which is used in forming hyperbolic-degree surface pieces. A series of finite element simulations and experiments have done for the process of forming saddle-shaped parts using two kinds of clamps named Tooth-type clamp and Wave-type clamp. The results show that Wave-type clamp can control the stretching force at an appropriate value. When the stretching force exceeds a critical value, the sheet metal can flow to the opposite direction of Stretch Forming as to maintain that stretching force. The formed part using Wave-type clamp has a better quality than the parts formed using Tooth-type clamp.

Effect of Addendum Parameters to the Formability of Aluminum AL 6303

2011 ◽  
Vol 264-265 ◽  
pp. 206-211 ◽  
Author(s):  
Afzeri ◽  
M.S. Shahdan ◽  
H. Shah Qasim
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Die Design ◽  
Minor Strain ◽  
Sheet Metal Part ◽  
Metal Part ◽  
Element Simulation ◽  
Strain Data ◽  
Final Design ◽  
Bead Diameter

Procedure of die design is mostly based on iterative try and error to obtain final design with good stamping formability. The stamping formability of sheet metal part is possible to be improved by adding addendum features at die model. In this paper discusses the effect of drawbars toward the formability of stamping process of aluminum AL6063. Effect of addendum size is evaluated Finite Element Simulation to prevent wrinkling and tearing. Simulation model is constructed by designing a simple die, punch and binder using variety drawbar diameters. The model further evaluated using LS-Dyna software interfaced by forming tool of LS-Prepost. Formability of the model is evaluated through yield stress, major strain and minor strain data. From the result of evaluation obtained that without draw beat, major/minor strain is above FLD while the formability is improved by applying 5 mm draw bead diameter.

Analysis and Correction of Defects for Deep Drawing Process of Stainless Sink by Use of Finite Element Simulation

2021 ◽  
Vol 889 ◽  
pp. 153-159
Author(s):  
Benjaphorn Khuanngern ◽  
Surasak Suranuntchai
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Sheet Metal ◽  
Deep Drawing ◽  
Forming Limit Diagram ◽  
Yield Function ◽  
Production Quality ◽  
Die Design ◽  
Forming Limit ◽  
High Production Cost

Finite Element Method (FEM) becomes one of the most useful techniques to analyze problems in sheet metal forming processes because of this technique can reduce cost and time in die design and trial step [1]. This research was aimed to predict the optimal parameters in order to eliminate cracks and wrinkles on stainless steel sink product under deep drawing named “DLS50”. The material was made from Stainless Steel 304 with thickness 0.6 mm. The parameters that had been investigated were punch angle and velocity as well as pressure of the punch. In order to simplify the process, punch and die in the simulation were assumed to be a rigid body, which neglected the small effect of elastic deformation. The properties of stainless steel sheet was assumed to be anisotropic, behaved according to constitutive equation of power law and deformed elastic-viscoplastic, which followed Barlat 3 components yield function. The deformation for Forming Limit Diagram (FLD) was predicted by the Keeler equation. Most of the defects such as cracks and wrinkles were found during the process on the parts. In the past, practical productions were performed by trial and error, which involved high production cost, long lead time, and wasted materials. From the prediction results, decreasing punch velocity from 50 mm/s to 8.33 mm/s would reduce the blank shearing zone on the corner bottom of the part and remove cracks in the process. The performing of the stainless sink by decreasing pressure in the process from 2.3 bar to 2 bar, and adjusting the punch shape increasing 5 mm. each side would increase formability of sheet metal in all direction, the reduction of cracking tendency zone out of the part. In conclusion by using the simulation technique, the production quality and performance had been improved.

The Effect of Loading Path on Forming Results in Multi-Gripper Flexible Stretch Forming

2014 ◽  
Vol 538 ◽  
pp. 108-112 ◽  
Author(s):  
You Wang ◽  
Ming Zhe Li ◽  
Hong Wei Liu
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Spherical Surface ◽  
Local Strain ◽  
Loading Path ◽  
Flow State ◽  
Stretch Forming ◽  
Forming Process ◽  
Loading Paths ◽  
Flexible Forming Process

Multi-gripper flexible stretch forming (MGFSF) is a recent technological innovation of sheet metal flexible forming process. Straight jaws in traditional stretch forming machine are replaced by a pair of opposed clamping mechanisms which can move relative to each other. Taking the case of forming a sheet metal into spherical surface by stretching the sheet in two opposite directions, the finite element models of MGFSF under various loading paths were established and the effects on stretch amount, strain and thickness of the simulated parts were analyzed comparatively. It is founded that compared to the horizontal-tilting (HT) and horizontal-vertical (HV) loading paths, the horizontal-tilting-vertical (HTV) loading path would result in more uniform stretch amount, strain and thickness distributions also with lower strain and thickness reduction, which improves the forming quality significantly. Finite element simulations also revealed that the material flow state in the transition zone can be improved effectively and the local strain concentration can be greatly suppressed with reasonable loading path, which would decrease the possibility of material failure.

scholarly journals Research on Contact State and Its Effect on Forming Precision in Uniform-Contact Stretch Forming Based on Loading at Multi-Position

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 719
Author(s):  
Lirong Sun ◽  
Zhongyi Cai ◽  
Xiangji Li
Keyword(s):  
Sheet Metal ◽  
Contact Region ◽  
Three Dimensional ◽  
Curved Surface ◽  
Stretch Forming ◽  
Contact State ◽  
Die Surface ◽  
State Evolution ◽  
Forming Precision ◽  
Loading Modes

Uniform-contact stretch forming based on loading at multi-position (UC-SF) was designed to substitute for conventional stretch forming (C-SF) in the manufacturing of qualified three-dimensional surface parts of a specified shape. Since the integral rigid clamps are replaced by discrete clamps, the sheet metal can be bent in a transverse direction (perpendicular to the stretching direction), and the sheet metal can be automatically warped to the die surface during the loading process. In this paper, finite element numerical simulations were performed to research the contact state evolution and its effect on forming precision by two kinds of loading modes (UC-SF and C-SF). The evolutions of contact state for spherical and saddle-shaped parts were analyzed in different steps, and the results reflect that, in UC-SF, the contact region of curved surface parts is gradually extended in a long strip, and the effective formed regions of the final parts can be in contact with the die surface. However, in C-SF, it is difficult for the final parts to be completely in contact with the die surface, especially spherical parts of a large curvature. Moreover, it is found that the noncontact region of the saddle-shaped part is susceptible to wrinkling in C-SF. Conversely, in UC-SF, the sheet metal can be constrained by contact with a die surface, such that the noncontact region and wrinkle defect disappear and high-precision parts are formed. Finally, stretch forming experiments were carried out and the perfect curved surface part was formed; thus, the experimental results verify the feasibility and effectiveness of UC-SF.

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