Force-controlled sheet metal stretch-forming process based on loading at discrete points

2017 ◽  
Vol 93 (5-8) ◽  
pp. 1781-1789 ◽  
Author(s):  
Zhong-Yi Cai ◽  
Xiao-bo Liang ◽  
Zhen Yang ◽  
Xiang-Ji Li
Keyword(s):  
Sheet Metal ◽  
Stretch Forming ◽  
Forming Process

A New Stretch-Forming Process Based on Loading at Discrete Points and its Numerical Investigation

2013 ◽  
Vol 423-426 ◽  
pp. 737-740
Author(s):  
Zhong Yi Cai ◽  
Mi Wang ◽  
Chao Jie Che
Keyword(s):  
Sheet Metal ◽  
Three Dimensional ◽  
Discrete Point ◽  
Stretch Forming ◽  
Sheet Metal Part ◽  
Metal Part ◽  
Forming Process ◽  
Loading Trajectory ◽  
New Process ◽  
Forming Defects

A new stretch-forming process based on discretely loading for three-dimensional sheet metal part is proposed and numerically investigated. The gripping jaw in traditional stretch-forming process is replaced by the discrete array of loading units, and the stretching load is applied at discrete points on the two ends of sheet metal. By controlling the loading trajectory at the each discrete point, an optimal stretch-forming process can be realized. The numerical results on the new stretch-forming process of a saddle-shaped sheet metal part show that the distribution of the deformation on the formed surface of new process is more uniform than that of traditional stretch-forming, and the forming defects can be avoided and better forming quality will be obtained.

Flexible Stretch Forming Technology for Sheet Metal Based on Discrete-Gripper and Multi-Point Die

2014 ◽  
Vol 556-562 ◽  
pp. 460-463 ◽  
Author(s):  
Xue Chen ◽  
Ming Zhe Li ◽  
Wen Hua Liu ◽  
Zhi Qiang Hou
Keyword(s):  
Sheet Metal ◽  
Experimental Results ◽  
Shape Error ◽  
Stretch Forming ◽  
Forming Process ◽  
Structural Composition ◽  
Forming Technology ◽  
Working Principle ◽  
Material Utilization

To solve the problem of low material utilization in traditional stretch forming process, a flexible stretch forming method was proposed, which can be realized by interaction of the multi-point stretch forming die with discrete-gripper stretch forming machine. The principle and characteristics of sheet metal flexible stretch forming technology was introduced, structural composition and working principle of the multi-point stretch forming die and discrete-gripper stretch forming machine were expounded, and the technology experiments was carried out with a self-designed flexible stretch forming technology equipment for sheet metal. The experimental results indicate that structure of multi-point stretch forming die and discrete-gripper stretch forming machine are reasonable, and flexible stretch forming technology can be realized by above-mentioned die and machine, stretch forming parts has a good quality and its shape error can satisfy requirements of production.

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.

scholarly journals TENDENCIES IN FORMING SHEET METAL PARTS USING INCREMENTAL FORMING ADVANCED TECHNOLOGIES

2019 ◽  
Vol 25 (3) ◽  
Author(s):  
CATALINA CIOFU ◽  
BOGDAN CHIRITA ◽  
ROXANA LUPU ◽  
COSMIN GRIGORAS ◽  
CRINA RADU ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Incremental Forming ◽  
Stretch Forming ◽  
Micro Forming ◽  
Forming Process ◽  
Metal Parts ◽  
Sheet Metal Parts ◽  
Advanced Technologies ◽  
Metal Materials ◽  
Forming Methods

Stretch forming of sheet metal materials is a highly required process in aerospace industry for manufacturing skin parts. Automation of some processes such as cutting, punching, forming, shearing and nesting in conventional manufacturing tends to combine these forming methods. Some researches are made on the formability of sheet metal materials obtained in incremental forming process with stretch forming and water jet incremental micro-forming with supporting dies. This paper is an attempt to review the newly researches made on optimization of manufacturing metal skin parts to achieve geometrical accuracy.

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.

scholarly journals TENDENCIES IN FORMING SHEET METAL PARTS USING INCREMENTAL FORMING ADVANCED TECHNOLOGIES

2019 ◽  
Vol 25 (3) ◽  
pp. 15-21
Author(s):  
CATALINA CIOFU ◽  
BOGDAN CHIRITA ◽  
ROXANA LUPU ◽  
COSMIN GRIGORAS ◽  
CRINA RADU ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Incremental Forming ◽  
Stretch Forming ◽  
Micro Forming ◽  
Forming Process ◽  
Metal Parts ◽  
Sheet Metal Parts ◽  
Advanced Technologies ◽  
Metal Materials ◽  
Forming Methods

Stretch forming of sheet metal materials is a highly required process in aerospace industry for manufacturing skin parts. Automation of some processes such as cutting, punching, forming, shearing and nesting in conventional manufacturing tends to combine these forming methods. Some researches are made on the formability of sheet metal materials obtained in incremental forming process with stretch forming and water jet incremental micro-forming with supporting dies. This paper is an attempt to review the newly researches made on optimization of manufacturing metal skin parts to achieve geometrical accuracy.

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.

A Process Comparison of Simple Stretch Forming Using Both Conventional and Electrically-Assisted Forming Techniques

2010 ◽  
Author(s):  
Joshua J. Jones ◽  
Laine Mears
Keyword(s):  
Sheet Metal ◽  
Manufacturing Process ◽  
Electrical Current ◽  
Stretch Forming ◽  
Forming Process ◽  
Process Comparison ◽  
Directional Flow ◽  
Direct Electrical Current ◽  
Electrically Assisted ◽  
Electrically Assisted Manufacturing

A common manufacturing process typically used to create large surface contours in sheet metal is stretch forming. With this process, the ability to create geometrically accurate parts and smooth surfaces is achievable, yet there are certain limits when considering the achievable elongation of the material and the inability to produce sharp contours in the sheet metal. Present research using Electrically-Assisted Manufacturing (EAM) has shown that applying direct electrical current to the workpiece during the forming process can increase the formability and reduce springback of the material, while also lowering the required forming forces. Seeing the advantageous qualities of EAM, this study examines the use of EAM for a simple stretch forming process. Specifically, this research examines this stretch forming process with regards to how the location where the electrical current is applied to the material affects the process, the achievable forming depth without fracture, and the application direction of the current. Overall results displayed that the directional flow of electrical current and the application location did not affect the obtained forming forces or forming depths using EAM.

Numerical simulation for the multi-point stretch forming process of sheet metal

2009 ◽  
Vol 209 (1) ◽  
pp. 396-407 ◽  
Author(s):  
Zhong-Yi Cai ◽  
Shao-Hui Wang ◽  
Xu-Dong Xu ◽  
Ming-Zhe Li
Keyword(s):  
Numerical Simulation ◽  
Sheet Metal ◽  
Stretch Forming ◽  
Forming Process
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