Influence of Element Number on Shape Accuracy in Multi-Point Stretch Forming of Air Craft

2011 ◽  
Vol 130-134 ◽  
pp. 2240-2244
Author(s):  
Jing Ling Wang ◽  
Zhong Yr Cai ◽  
Mine Zhe Li ◽  
Hui Yang
Keyword(s):  
Flexible Manufacturing ◽  
Three Dimensional ◽  
Great Influence ◽  
Stretch Forming ◽  
Forming Process ◽  
Shape Accuracy ◽  
Part Quality ◽  
Die Surface ◽  
Dimensional Shape ◽  
Element Number

Multi-point stretch forming is a flexible manufacturing technique for three-dimensional shape forming of craft skin. Its die surface is constructed by many pairs of matrices of elements whose height is controlled by computer. It uses the curved surface of elements instead of the die surface. The element numberis an important parameter because it has great influence on the part quality. This paper simulates the forming process of paraboloid part and saddle-shaped part with different number of elements and studies the influence of element number on the shape accuracy of the part .That will provides guidance for the application of multi-point stretch forming.

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.

Optimal Design of Flexible Manufacturing System Based on Optical Measurement Principle

2010 ◽  
Vol 142 ◽  
pp. 219-222
Author(s):  
Shao Sheng Wang ◽  
Wan Tao He ◽  
Rong Bin Liu ◽  
Jun Ting Cheng
Keyword(s):  
Flexible Manufacturing ◽  
Manufacturing System ◽  
Flexible Manufacturing System ◽  
Optical Measurement ◽  
Recognition Rate ◽  
Three Dimensional ◽  
Recognition Quality ◽  
Measurement Principle ◽  
Dimensional Shape ◽  
The One

The material recognition and size measuring cell is very important for the development and practicability of flexible manufacturing system (FMS). However, the existing FMS mostly recognize the two-dimensional shape of the workpiece, measure the one- dimensional shape of the finishing product. This greatly limits the performance of FMS. In this paper, these cells have been optimally designed to identify and measure the three-dimensional shape of the workpiece based on the optical measurement principle. The method has the advantage at robust recognition rate and high recognition quality.

Numerical Simulation of Multi-Roll Stretch Forming Process with Different Lubrication and Rollers

2011 ◽  
Vol 110-116 ◽  
pp. 1512-1518
Author(s):  
Hao Han Zhang ◽  
Ming Zhe Li ◽  
Wen Zhi Fu ◽  
Peng Xiao Feng
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Friction Coefficient ◽  
Flexible Manufacturing ◽  
General Idea ◽  
Stretch Forming ◽  
Forming Process ◽  
New Process ◽  
Traditional Process ◽  
Stretching Process

Multi-roll stretch forming process is a new flexible manufacturing technique that the general idea of discretizing is put in use in the design of stretch forming machine. In the new process, the metal sheet can be more easily formed, and the flexibility can be much higher, which the traditional process cannot compare with. In this paper, in through extensive numerical simulations of the MRSF stretching process of toroidal saddle parts, A series of finite element simulations have done for the process of forming toroidal saddle parts using different lubricant and two kinds of rollers named damped rollers and ordinary rollers. The results show that the smaller the friction coefficient is, the easier the center of toroidal saddle part is stretched. Damped rollers can increase the stretching force and the ordinary rollers can increase the mobility of sheet metal. Arranging the damped rollers and ordinary rollers at a reasonable position can make the workpiece a more uniform stretching.

Numerical Simulation and Experiment Research on Surface Defects for Thick Plate Multi-Point Forming Process

2013 ◽  
Vol 385-386 ◽  
pp. 59-62
Author(s):  
Le Li ◽  
Li Yong Wang
Keyword(s):  
Flexible Manufacturing ◽  
Surface Defects ◽  
Three Dimensional ◽  
Metal Plate ◽  
Curvature Radius ◽  
Forming Process ◽  
Explicit Finite Element ◽  
Deformation Features ◽  
Simulation And Experiment ◽  
Forming Defects

Multi-point forming (MPF) is an advanced flexible manufacturing technology for three-dimensional sheet metal forming. The substance of MPF is replacing the conventional solid dies by a set of discrete punches called punch group. Due to the discrete contacts between the workpiece and punches, the dimple defects occurred, which are inevitable and particular for MPF. In this study, the analysis of the deformation features of the dimple defects was implemented. The dynamic explicit finite element method was chosen to implement the simulation of MPF process. The influencing factors of the surface defects were researched. The relevant experiment was implemented, and it verified that the forming defects decreased with the increasing of the thickness of metal plate and the objective surface curvature radius.

Numerical Analysis of the Multi-Point Stretch Forming Process of Aircraft Outer Skin Part

2010 ◽  
Vol 154-155 ◽  
pp. 1068-1072
Author(s):  
Shao Hui Wang ◽  
Zhong Yi Cai ◽  
Ming Zhe Li ◽  
Ying Wu Lan
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Flexible Manufacturing ◽  
Stretch Forming ◽  
Forming Process ◽  
Outer Skin ◽  
Free Length ◽  
Simulation Results ◽  
The Cost ◽  
Elastic Cushion

As a flexible manufacturing technique, Multi-point stretch forming (MPSF) is a suitable method for forming aircraft outer skin part. The traditional solid stretching die is replaced by the discrete multi-point die (MPSD), and the sheet metal is stretch-formed over the MPSD generated by serial adjusting mode or parallel adjusting mode. The MPSF can be used to form the parts of different shape and reduce the cost and leading time of stretching die fabrication for aircraft outer skin part. A series of numerical simulations on typical MPSF processes of aircraft outer skin part were carried out. The thickness of elastic cushion and free length are important factors to influence on the stretch forming results of stretch-formed parts. The numerical simulation results show that the thicker the elastic cushion is, the more valid the dimple will be suppressed .The longer the free length is, the easier the wrinkle will be brought.

scholarly journals Adaptive Stretch-Forming Process: A Computer Vision and Statistical Analysis Approach

Machines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 357
Author(s):  
Cosmin Constantin Grigoras ◽  
Valentin Zichil ◽  
Bogdan Chirita ◽  
Vlad Andrei Ciubotariu
Keyword(s):  
Computer Vision ◽  
Classical Method ◽  
Industrial Process ◽  
Industrial Sector ◽  
Production Costs ◽  
Stretch Forming ◽  
Forming Process ◽  
Part Quality ◽  
High Degree

An industrial process is defined through its quality of parts and their production costs. Labour-intensive operations must be applied to produce high-quality components with inexpensive resources. Recent development in dedicated software allows the industrial sector to rely on more and more autonomous solutions to obtain an optimum ratio between part quality and cost. The stretch forming process is an operation that has a high degree of difficulty, due to the process parameters and the spring-back effect of materials. Our approach to solving several of the shortcomings of this process was to develop a self-adaptive algorithm with computer vision capabilities that adapts to the process in real-time. This experimental study highlights the results obtained using this method, as well as a comparison to a classical method for the stretch-forming process (SFP). The results have noted that the stretch-forming algorithm improves the process, while adapting its decisions with each step.

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.

scholarly journals Research on the Cross Section Forming Quality of Three-Dimensional Multipoint Stretch Forming Parts

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jiaqi Yu ◽  
Yi Li ◽  
Fei Teng ◽  
Jicai Liang ◽  
Xiangfeng Lin ◽  
...  
Keyword(s):  
Cross Section ◽  
Three Dimensional ◽  
Bending Test ◽  
Stretch Forming ◽  
Forming Process ◽  
Cross Sectional ◽  
Forming Quality ◽  
Factors Affecting ◽  
Forming Parameters ◽  
The Cross

This paper introduced the basic principle and main influencing factors of the three-dimensional multipoint stretch forming process and investigated the optimized scheme of the cross section forming quality. The main factors affecting the stretch forming process were studied by the orthogonal test through the numerical simulation technique. In the case of a good target shape, the best combination of forming parameters was established by using the range method. The cross-sectional distortion of the formed profile is the smallest when the prestretching amount is 1% of the profile length, the poststretching amount is 0.8% of the profile length, the number of the die heads is 12, and the friction coefficient is 0.15. The optimal combination of forming parameters was verified by the multipoint bending test.

Numerical Investigation on the Process of Stretch-Forming Based on Discretely Loading for Spherical Sheet Metal Parts

2013 ◽  
Vol 816-817 ◽  
pp. 682-685 ◽  
Author(s):  
Zhong Yi Cai ◽  
Mi Wang ◽  
Zhen Yang ◽  
Kun Peng
Keyword(s):  
Sheet Metal ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
Equivalent Strain ◽  
Stretch Forming ◽  
Sheet Metal Part ◽  
Metal Part ◽  
Forming Process ◽  
Sheet Metal Parts ◽  
New Process

Stretch-forming based on discretely loading is a new process for manufacturing three-dimensional sheet metal part, the stretching load is applied at discrete points on the two ends of sheet metal, by controlling the loading trajectory at each discrete point, an optimal stretch-forming process can be realized, and the formed surface with the strains and stresses more uniformly distributed are obtained so that the forming defect can be avoided. The numerically investigated results on the stretch-forming process of spherical sheet metal part show that, comparing with the traditional stretch-forming, the equivalent strain in the new process is reduced by approximately 30% and equivalent stress reduced by 10%, the range of the strain and stress distributions are reduced by approximately 30%.

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