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

Cai, Zhongyi; Wang, Shaohui; Xu, Xudong; Li, Mingzhe

doi:10.1016/j.jmatprotec.2008.02.010

Cited by 126 publications

(61 citation statements)

References 16 publications

(6 reference statements)

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“…An elastic cushion is required in MPF to protect the sheet from dimpling [12,13]. In this investigation, the material of the elastic cushion was chosen to be polyurethane A-90 as it is commonly used in this process [13].…”

Section: Introductionmentioning

confidence: 99%

Optimisation of multi-point forming process parameters

Abosaf

Essa

Alghawail

et al. 2017

Int J Adv Manuf Technol

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The need for sheet metal forming using reconfigurable dies has increased due to rapid changes in part design to meet customer requirements, especially in the automotive industry. Reconfigurable dies have relatively low manufacturing cost compared with solid dies, and the same tool can be readily changed to produce different parts. Previous investigations have focused on avoiding defects without taking into account the effects of process on the quality characteristics of fabricated parts. This study investigated the influence of parameters, such as the elastic cushion thickness, coefficient of friction, pin size and radius of curvature, on the quality of parts formed in a flexible multi-point stamping die. The aim was to determine the optimum values of those parameters. Finite element modelling was employed to simulate the multi-point forming of hemispherical parts. Using the response surface method, the effects of process parameters on wrinkling, deviation from the target shape and thickness variation were investigated and the process parameters yielding the best product quality characteristics were obtained. The results show that pin size and radius of curvature have the greatest influence on wrinkling and deviation between formed and target shapes, while coefficient of friction, pin size and radius of curvature significantly affect thickness variation.

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Section: Introductionmentioning

confidence: 99%

Optimisation of multi-point forming process parameters

Abosaf

Essa

Alghawail

et al. 2017

Int J Adv Manuf Technol

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“…Zhou [1] proposed the concept of multi-point stretch forming (MPSF) based on the multi-point forming (MPF) [2]. Cai [3] studied the effects of the elastic cushion, the punch element and the multi-point stretching die on the shape accuracy of the formed part in the MPSF. Wang [4] investigated the number of punch elements and the radius of the hemispherical end of elements on the surface smooth and the shape error of the formed parts in the MPSF.…”

Section: Introductionmentioning

confidence: 99%

Numerical contrast of flexible clamp and rigid clamp for stretch forming

Peng¹,

Li²,

Zhong³

et al. 2018

Proceedings of the 2017 3rd International Forum on Energy, Environment Science and Materials (IFEESM 2017)

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Abstract. The characters of flexible clamp stretch forming (FCSF) is introduced, the finite element model of FCSF is set up, and lots of numerical simulations for spherical part and saddle-shaped part are carried out. Contradistinctive analysis of strain, thickness and transitional length between RCSF and FCSF are investigated, and the minimum transitional length diagram of spherical part and saddle-shaped part are determined. FCSF machine was developed, and the forming experiment of spherical part was done. Consequently, the spherical part has good surface quality, which proves that the FCSF technology is feasible and the simulated results are valid. IntroductionCompared to other forming operations, stretch forming operation has litter springback value and better shape precision, so it becomes the primary method to form aircraft outer skin parts. Most of the aircraft outer skin parts are stretched by rigid die and clamp. But traditional rigid fixed die is designed to form a particular part and offers no shape flexibility, which leads the fabricating cost of stretching die is generally high. And traditional rigid clamp has no relative movement between clamp and sheet metal, which leads the sheet is difficult to fit the die when forming parts with large transversal curvature.In recent years, with the improvement of industrial level, the demands of sheet metal with complex shape and good forming quality increased rapidly in the field of aeronautics and astronautics. Flexible die and clamp are used to form parts with different shapes and improve the forming quality. Zhou [1] proposed the concept of multi-point stretch forming (MPSF) based on the multi-point forming (MPF) [2]. Cai [3] studied the effects of the elastic cushion, the punch element and the multi-point stretching die on the shape accuracy of the formed part in the MPSF. Wang [4] investigated the number of punch elements and the radius of the hemispherical end of elements on the surface smooth and the shape error of the formed parts in the MPSF. Adjustable clamp stretching machine was developed by ACB of France [5], but the machine needs to manually adjust the arc of sub-clamp based on the shape of stretching die, which leads to low forming precision and efficiency. Then, a new-type of flexible clamp stretch forming (FCSF) machine was designed [6]. It is attractive due to the flexibility of clamping method. The purpose of this paper is to investigate the difference between rigid clamp stretch forming (RCSF) and FCSF.

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“…Because of the MPD is composed of a series of regularly arranged, heightadjustable punch units, different three-dimensional die surfaces can be obtained by adjusting the height of each punch unit that can be controlled by the electrical system [8]. Therefore, the time and the cost of MPSF can be significantly reduced in the process of die designing, manufacturing, repeated debugging, and repairing [9,10]. MPSF process has successfully solved the difficulty in forming different parts with a single apparatus.…”

Section: Introductionmentioning

confidence: 99%

Effect of the arrangement of the punch units in multi-point stretch forming process

Jin

Cheng

et al. 2016

Int J Adv Manuf Technol

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Multi-point stretch forming (MPSF), by replacing the traditional rigid fixed-shape stretching die with the multi-point die (MPD), is an important flexible forming technique in sheet metal forming process. However, the particular dimples will be generated on the formed part surface when forming by MPD. In this paper, we prove that the dimple formation can be suppressed by changing the punch units of MPD arrangement. Therefore, the forming effect can be largely improved. Spherical parts are selected as the study objects. Under the same loading condition, two MPSF finite element numerical models are established for conventional arrangement multi-point die (CAMPD) and staggered arrangement multi-point die (SAMPD), respectively. Through the numerical simulations and the stretch forming experiments, the stress, strain, thickness, springback, and shape accuracy are compared between the two parts formed by CAMPD and SAMPD. The results show that the values of the stress, strain, thickness thinning rate, and springback of the formed part are smaller when forming by SAMPD. Moreover, the distributions of the stress, strain, and thickness are more uniform. Also, the surface forming quality and the shape accuracy are improved. These results provide a valuable guidance during developing the new types of MPD.

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

Cited by 126 publications

References 16 publications

Optimisation of multi-point forming process parameters

Optimisation of multi-point forming process parameters

Numerical contrast of flexible clamp and rigid clamp for stretch forming

Effect of the arrangement of the punch units in multi-point stretch forming process

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