Accommodation of Springback Error in Channel Forming Using Active Binder Force Control: Numerical Simulations and Experiments

1996 ◽  
Vol 118 (3) ◽  
pp. 426-435 ◽  
Author(s):  
M. Sunseri ◽  
J. Cao ◽  
A. P. Karafillis ◽  
M. C. Boyce
Keyword(s):  
Finite Element ◽  
Force Control ◽  
Control Method ◽  
Processing Parameters ◽  
Shape Error ◽  
Finite Element Analyses ◽  
Forming Process ◽  
Loop Control ◽  
Formed Part ◽  
Restraining Force

Springback in a forming process is due to the elastic deformation of the part during unloading. This manufacturing defect can be accounted for through proper tooling design or through proper design and control of the magnitude and history of restraining force. Using finite element analyses of the process: (1) the effects of restraining force on the springback phenomena when stamping channels from aluminum sheet are investigated; (2) a strategy to control the binder force during the forming operation in order to reduce springback and simultaneously avoid tearing failure is described; and (3) a binder force control strategy which provides robustness in the presence of process parameter uncertainty is implemented. The process history and controller designed using finite element analyses is then experimentally verified: excellent agreement between simulation and experiments is obtained. A binder force history, which leads to a significant reduction in the amount of springback incurred by the formed part without reaching critical stretching conditions, was proposed. Although an optimal forming history was found, in order to ensure that part shape error remained minimized even in the event of variations in processing parameters such as friction, a closed-loop control algorithm was developed whereby the binder force is altered during the process in order to provide a robust, repeatable stretching history. Experiments were performed using a double-action servo-controlled process and were found to produce the desired results demonstrating both the accuracy of the numerical simulation and the success of the proposed active-binder force control method to obtain net shape.

An inverse method for prediction of the required temperature distribution in the creep forming process

1998 ◽  
Vol 212 (1) ◽  
pp. 7-11 ◽  
Author(s):  
P Moreau ◽  
D Lochegnies ◽  
J Oudin
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Inverse Method ◽  
Numerical Procedure ◽  
Small Variation ◽  
Optimization Method ◽  
Glass Sheet ◽  
Finite Element Analyses ◽  
Forming Process ◽  
Identification Procedure

To achieve the creep forming of glass sheet from designer specifications, the manufacturer has to know the required temperature distribution in the glass sheet accurately: a small variation of the temperature produces great change in the viscosity, and therefore, in the final shape of the sheet. In order to find this distribution, the authors propose an inverse identification procedure based on an optimization method and finite element analyses. The inverse problem is solved using a modified Levenberg—Marquardt method to match the measured displacements to the finite element solutions which depend on the unknown forming parameters. The manufacture of recent rear automotive screens illustrates this efficient numerical procedure.

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 Residual Forming Stresses on Fracture in ERW Pipe

2016 ◽  
Author(s):  
Ted L. Anderson ◽  
Gregory W. Brown
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Fracture Behavior ◽  
Finite Element Simulations ◽  
Finite Element Analyses ◽  
Forming Process ◽  
Cold Expansion ◽  
The Past

Many older pipelines contain significant residual stress due to the forming process. Cold expansion or a normalizing heat treatment can virtually eliminate residual forming stresses, but these practices were less common in the past. In the absence of cold expansion or normalization, residual forming stresses can be reduced by hydrostatic testing or operating pressures, but not eliminated entirely. Residual stresses can contribute to fracture in pipelines, particularly when the material toughness is low. This article presents a series of analyses that seek to quantify the magnitude of residual forming stresses as well as their impact on pipeline integrity. The pipe forming process was simulated with elastic-plastic finite element analyses, which considered the effect of subsequent loading on relaxation of residual stresses. A second set of finite element simulations were used to quantify the effect of residual stresses on fracture behavior.

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

2019 ◽  
Author(s):  
Jian Xing ◽  
Yan-yan Cheng ◽  
Zhuo Yi
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Strain Distribution ◽  
Finite Element Models ◽  
Stretch Forming ◽  
Forming Process ◽  
Forming Quality ◽  
Staggered Arrangement ◽  
Simulation Results ◽  
Formed Part

To improve the effect of multi-point stretch forming of sheet metal, it is proposed in this paper to replace fixed ball head with swinging ball head. According to the multi-point dies with different arrangements, this research establishes the 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 fixed ball head with swinging ball head, the surface indentation of the formed part was effectively suppressed, the stress and tension strain distribution of the formed part was improved and the forming quality was improved; that the thickness of the elastic pad was reduced, the springback was reduced and the forming accuracy was improved; and that when the ball head was applied to multi-point die with staggered arrangement, better forming result was achieved, where the best forming result was achieved in combining the swinging ball heads with the multi-point die with parallel staggered arrangement. The 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.

Study of the control process and fabrication of microstructures using a tip-based force control system

2016 ◽  
Vol 232 (11) ◽  
pp. 1928-1942 ◽  
Author(s):  
Jingran Zhang ◽  
Yongda Yan ◽  
Zhenjiang Hu ◽  
Xuesen Zhao
Keyword(s):  
Atomic Force Microscopy ◽  
Force Control ◽  
Normal Force ◽  
Control Method ◽  
Low Cost ◽  
Three Dimensional ◽  
Control Process ◽  
Loop Control ◽  
Force Microscopy ◽  
Atomic Force

The atomic force microscopy tip-based nanomechanical machining method has already been employed to machine different kinds of nanostructures with the control of the normal force of the tip. The previous studies verified the feasibility of the nanomachining approach with the force control. However, there are still some shortcomings of small normal force, small machining scale, high cost and low machining efficiency. Therefore, in this study, a tip-based micromachining system with normal force closed-loop control is established based on the principle of atomic force microscopy. The control parameters are optimized based on an analysis of the control process to enable the production of a constant normal force during machining when using a tip tool. The maximum machining velocity that can be attained using this system while maintaining a constant normal force is obtained based on an analysis of the normal force variations during machining. By controlling nanoscale accuracy and high-precision stage, more complex microstructures, including microsquares, millimeter-scale microchannels and three-dimensional step microchannels, are successfully fabricated using the proposed force control method. Experimental results show that the tip-based normal force control method is a simple, low-cost and versatile micromachining method with the potential ability to machine more complex structures and is likely to find wider applications in the micromachining field.

scholarly journals Hybrid Position/Force Control for Dual-Machine Drilling and Riveting System

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Yi Liu ◽  
Qiang Fang ◽  
Yinglin Ke
Keyword(s):  
Force Control ◽  
High Performance ◽  
Control Method ◽  
Dynamics Model ◽  
Negative Effects ◽  
Forming Process ◽  
Stiffness Model ◽  
Feedforward Controller ◽  
Head Height ◽  
Deformation Error

The deformation of riveting machine caused by riveting force during rivet formed makes the riveting tool out of positioning, which leads to gapping underneath the rivet manufactured head and insufficient rivet drive head. This paper proposes a hybrid position/force riveting control method for the dual-machine drilling and riveting system to eliminate the negative effects of machine deformation. The cooperative work of two-side machine tool is realized by a hybrid position/force control strategy, which compensates for the force-induced deformation error without an accurate stiffness model of the riveting system. The position of pressing foot relative to the machine which represents the deformation of skin-side machine is obtained for the compensation to the displacement of skin-side actuator. Simultaneously, the advanced force control is adopted for the stringer-side actuator. The dynamics model of the stringer-side actuator in consideration of the machine deformation is established and identified. The disturbance observer (DOB) and feedforward controller are introduced as the model-based control algorithm to achieve the high-performance force control. Also, contrast experiments are conducted to validate the effectiveness of the proposed riveting control method. The results show that the rivet manufactured head can be seated in the countersink during the forming process and the gapping under the head is eliminated. The driven head height tolerance of ±0.1 mm is achieved by accurate force control.

A PROCESS MAP FOR SEQUENTIAL COMPRESSION-BACKWARD EXTRUSION OF AZ31 MG ALLOYS AT WARM TEMPERATURS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5649-5654 ◽  
Author(s):  
DUK-JAE YOON ◽  
EUNG-ZOO KIM ◽  
CHONG-DU CHO ◽  
YONG-SHIN LEE
Keyword(s):  
Finite Element ◽  
Mg Alloy ◽  
Finite Element Analyses ◽  
Warm Temperature ◽  
Forming Process ◽  
Process Map ◽  
Backward Extrusion ◽  
Az31 Mg Alloy ◽  
Forming Temperature ◽  
Deformation Behaviors

This paper is concerned with development of a process map for sequential compression-backward extrusion of bulk AZ31 Mg alloy at the warm temperatures. In experiments, metal flows and crack initiations are carefully investigated and formability is examined systematically for various forming conditions such as forming temperature, punch speed, and a gap between a specimen and die. Then, a process map for the sequential compression-backward extrusion of bulk AZ31 Mg alloy at the warm temperature is proposed. In order to further understand deformation behaviors and damage evolution during warm forming process, thermo mechanical finite element analyses coupled with damage evolutions are carried out. In general, finite element predictions support experimental observation. Finally, it is concluded that the process map, proposed for the sequential compression-backward extrusion of AZ31 Mg alloy, is valid.

Numeral Simulation of a New Forming Process: Stretch Forming Combined with Roll Forming

2011 ◽  
Vol 189-193 ◽  
pp. 2399-2403 ◽  
Author(s):  
Zhi Qing Hu ◽  
Ji Zhao ◽  
Yu Shan Deng ◽  
Hao Han Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Von Mises Stress ◽  
Roll Forming ◽  
Stretch Forming ◽  
Forming Process ◽  
Element Analysis ◽  
Formed Part ◽  
Von Mises ◽  
Rubber Rolling

In this study, the principle of the stretch forming combined with roll forming(SRF) is proposed, to present the availability of this process, it is simulated by the Method of Finite Element Analysis(FEA) by comparing traditional stretch forming(SF) with stretch roll forming (SRF), the result is shown that the roller covered the rubber rolling sheet metal is benefit to formed part, such as Von mises stress, the thickness thinned and the coincidence curve of formed part are studied.

Finite Element Simulation of Deep Drawing Processes for Shell Bar RR Impact RH/LH

2018 ◽  
Vol 875 ◽  
pp. 24-29
Author(s):  
Aekkapon Sunanta ◽  
Surasak Suranuntchai
Keyword(s):  
Finite Element ◽  
Deep Drawing ◽  
Yield Function ◽  
Production Quality ◽  
Die Design ◽  
Blank Holder Force ◽  
Forming Process ◽  
Blank Holder ◽  
Restraining Force ◽  
Shell Bar

Finite Element Method (FEM) is one of the most useful techniques to analyze problems in metal forming process because of this technique can reduce cost and time in die design and trial step [1]. This research is aimed to predict the optimal parameters in order to eliminate cracks and wrinkles on automotive deep drawing product “Shell Bar RR Impact RH/LH”. The material was made from high strength steel JSC440W sheet with thickness 1.8 mm. The parameters that had been investigated were blank holder force (BHF) and drawbead restraining force (DBRF). 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 material properties assumed to be anisotropic, behaved according to the constitutive equation of power law and deformed elastic-viscoplastic, which followed Barlat 3 components yield function. Most of the defects such as cracks and wrinkles were found during the processes on the parts. In the past, the practical productions were performed by trial and error, which involved high production cost, long lead time and wasted materials. From the results, when decreased blank holder force to 30 tons, cracks on the part were removed but wrinkles had a tendency to increase in part area because of this part is the asymmetrical shape. Finally, applying about drawbead restraining force at 154.49 and 99.75 N/mm could improve product quality. In conclusion, by using the simulation technique, the production quality and performance had been improved.

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