Design for manufacturing for sheet metal parts

In the assembly process of auto-body, variations in the geometrical dimensions of sheet metal parts and fixtures are inevitable. These variations accumulate through the multi-station assembly process to form the dimensional variations of the final products. Compared with the assembly of rigid parts, the assembly process of the elastic parts is more complex because the variation accumulation patterns rely much on the variations of fixture, jointing methods and mechanical deformation. This paper aims at analyzing the variation transformation mechanism and accumulation characteristics for the assembly of sheet metal parts based on the analysis of dimensional coordination relations among parts and fixtures. Finite element method (FEM) and Monte-Carlo Simulation (MCS) were used to analyze the effect of jointing contact on variation transformation, while a state equation was developed to describe the variation accumulation mechanism. The result of the analysis indicates that the main characteristics of elastic assembly jointing are the overlap jointing methods and elastic contacts action. The fact that the variation transform coefficients (VTC) are variable makes the assembly variation distribution Non-Gaussian even if the dimension variation of parts is Gaussian distribution. The analysis conclusions have potential value for more reasonable tolerance synthesis of elastic parts assembly.

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Aanalysis of springback phenomenon in pipe bending

World Journal of Engineering ◽

10.1260/1708-5284.11.3.229 ◽

2014 ◽

Vol 11 (3) ◽

pp. 229-232

Author(s):

Rahul Hingole ◽

Vilas Nandedkar

Keyword(s):

Sheet Metal ◽

Research Work ◽

Deep Understanding ◽

Beam Theory ◽

New Approach ◽

Metal Parts ◽

Sheet Metal Parts ◽

Before And After ◽

Forming Tools ◽

Pipe Bending

The term springback is defined as the change in geometry of a component after forming, when the forces are removed from forming tools. As springback affects the final shape of the part, it can lead to significant difficulties in the assembly of component when springback is not proper. This problem leads to fabrication of inconsistent sheet metal parts; the elastic strain recovery in the material after the tooling is removed. Bendingis the plastic deformation of metals about a linear axis called the bending axis with little or no change in the surface area. Bending types of forming operations have been used widely in sheet metal forming industries to produce structural stamping parts such as braces, brackets, supports, hinges, angles, frames, channel and other nonsymmetrical sheet metal parts. Among them, quite a few efforts have been made to obtain a deep understanding of the springback phenomenon. The beam theory has been applied to formulate the curvature before and after loading of pipe. This research work has focused on study effect of springback effect with a new approach. The ANSYS software is used to analyze spring back effect. The detail study of this springback effect is presented in this paper.

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Optimisation of Springback Predicted by Experimental and Numerical Approach by Using Response Surface Methodology

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.6-8.753 ◽

2005 ◽

Vol 6-8 ◽

pp. 753-762

Author(s):

R. Bahloul ◽

Phillippe dal Santo ◽

Ali Mkaddem ◽

A. Potiron

Keyword(s):

Response Surface ◽

Sheet Metal ◽

Design Method ◽

Fem Simulation ◽

Numerical Approach ◽

Tool Geometry ◽

Nose Radius ◽

Element Analysis ◽

Metal Parts ◽

Sheet Metal Parts

Bending has significant importance in the sheet metal product industry. Moreover, the springback of sheet metal should be taken into consideration in order to produce bent sheet metal parts within acceptable tolerance limits and to solve geometrical variation for the control of manufacturing process. Nowadays, the importance of this problem increases because of the use of sheet-metal parts with high mechanical characteristics (High Strength Low Alloy steel). This work describes robust methods of predicting springback of parts in 3D modelling subjected to bending and unbending deformations. Also the effects of tool geometry in the final shape after springback are discussed. The first part of this paper presents the laboratory experiments in wiping die bending, in which the influence of process variables, such as die shoulder radius, punch-die clearance, punch nose radius and materials properties were discussed. The second part summarises the finite element analysis by using ABAQUS software and compares these results with some experimental data. It appeared that the final results of the FEM simulation are in good agreement with the experimental ones. An optimisation methodology based on the use of experimental design method and response surface technique is proposed in the third part of this paper. That makes it possible to obtain the optimum values of clearance between the punch and the die and the optimum die radius which can reduce the springback without cracking and damage of product.

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