Research on springback characteristic in flexible multi-points 3D stretch-bending process

The problem of springback is one of the most significant factors affecting the forming accuracy for aluminum 3D stretch-bending parts. In order to achieve high-efficiency and high-quality forming of such kind of structural components, the springback behaviors of the AA6082 aluminum profiles are investigated based on the flexible multi-points 3D stretch-bending process (3D FSB). Firstly, a finite element simulation model for the 3D FSB process was developed to analyze the forming procedure and the springback procedure. The forming experiments were carried out for the rectangle-section profile to verify the effectiveness of the simulation model. Secondly, the influence of tension on springback was studied, which include the pre-stretching and the post-stretching. Furthermore, the influences of the bending radius and bending sequence are revealed. The results show that: (1) The numerical model can be used to evaluate the effects of bending radius and process parameters on springback in the 3D FSB process effectively. (2) The pre-stretching has little effect on the horizontal springback reduction, but it plays a prominent role in reducing the springback in the vertical direction. (3) The increase of bending deformation in any direction will lead to an increase of springback in its direction and reduce the springback in the other direction. Besides, it reduces the relative error in both directions simultaneously. This research established a foundation to achieve the precise forming of the 3D stretch-bending parts with closed symmetrical cross-section.

A Bending Sequence Planning Algorithm Based on Multiple-Constraint Model

A sequence planning algorithm based on multiple-constraint model was proposed to solve the problems in the bending process of complex workpiece. By employing a heuristic search based A* algorithm, the sequence planning was converted to a generalized shortest path problem, and then a multiple-constraint model which includes the factors of bending feasibility, dimensional accuracy and processing efficiency was introduced to optimize the search process. A bend sequence planning system has been realized based on this algorithm. The testing results of the system indicate that the algorithm is efficient and stability, and the planning time of complex bending workpiece was reduced effectively, especially for the workpieces which don’t have the valid bending process.

Sequence Planning and Tool Selection for Bending Processes of 2.5D Sheet Metals

Planning of an appropriate bending sequence is one of the most important aspects in the processing of sheet metals as the appropriateness of the plan affects correct selection of bending tools and feasibility of bending processes. This study aims to propose a set of principles to be followed for the planning of bending sequences and selection of bending tools for 2.5D sheet metals. To this end, we first define basic bending patterns by characterizing each pattern with a set of operation rules. The sheet metal is then decomposed into a series of bending patterns that is in turn used in the planning of bending sequences. In order to select the bending tools, we combine the contours of each bending operation, choose appropriate bending punches from the bending-tool database, and then undertake an interference check with the bending contours.

Development of a Virtual Machine for the Sheet Metal Bending Process Simulation for Educational Purposes

In this work the development of a virtual machine for the simulation of the sheet metal bending process is presented. The developed software is based on SolidEdge® as commercial CAD base, and allows the student to design the whole sheet metal part in a 3D environment. The application guides the student during all process, including the selection of the press brake and the tools (dies and punches) by means of a graphical interface. Finally, the bending sequence is introduced and the application simulates the bending process. This way the student can see the problems during the manufacturing process, in particular collisions, that arise from the design of the part, from the tools selected or, in most cases, from the bending sequence. Finally, the student should fix these problems in order to manufacture the part.

Optimisation of Sheet Metal Bending Sequences Using Genetic Algorithms

This paper shows a solution to the problem of finding an optimum sheet metal bending sequence using Genetic Algorithms (GA). First it shall be explained how the problem can be modelled, previous to its solution by GA. Secondly the method for optimization, under different criteria, is described. Finally the results obtained and the advantages of using the GA are shown.

A Framework for Automatic Tool Selection in Integrated CAPP for Sheet Metal Bending

Sheet metal bending is a metal forming process, in which flat sheets are bent along straight bend lines in a specific bending sequence to form three-dimensional parts. A large number of tools with different characteristics can be used in this process. The task to choose the right tooling for a requested sheet metal part is however one of the bottle necks in process planning. An inefficient tool selection may result in failure of finding a feasible bending sequence. In previous work, methodologies for tool selection and optimization have been proposed. The presented paper describes a framework to implement these methodologies into a system that allows automatic tool selection in consistent consideration of bend sequencing. As a result, automated and optimized tool selection for sheet metal bending is achieved, as illustrated by performance test results for a robust software implementation.