Fuzzy set theory applied to bend sequencing for sheet metal bending

Abstract

Brake forming is widely applied in the high variety and small batch part manufacturing of sheet metal components, for the bending of straight bending lines. Currently, the planning of the bending sequences is a task that has to be performed manually, involving many heuristic criteria. However, set-up and bend sequencing procedures and knowledge have to be formally formalized and modeled, for the development of computer-aided process planning systems for sheet metal forming. This paper describes the application of fuzzy set theory, for the normalization and modeling of the set-up and bend sequencing process for sheet metal bending. A fuzzy-set based methodology is used to determine the optimal bending sequences for the brake forming of sheet metal components, taking into account the relative importance of handling and accuracy. © 1997 Elsevier Science S.A.

Sheet-metal bend sequence planning subjected to process and material variations

“…Bending errors caused by oversimplified process models and their correlation with flat pattern development were investigated in his work [10]. Ong et al devised a framework to integrate tolerance analysis with bend sequencing by utilizing fuzzy reasoning [11]. Detailed modeling was carried out of accuracy, positioning, and handling.…”

“…Based on this literature survey two kinds of bend sequence planning methodologies are found: (1) Bend sequence planning methodologies that are aimed to reduce allowable design tolerances for individual bends during the execution of a bending sequence [7,[10][11][12][13][16][17][18][19][20][21][22][23][24] (2) Bend sequence planning methodologies aimed to reduce total bending time by reducing tool and part handling tome, collision avoidance, ergonomic aspects, and geometric constraints [5,11,[25][26][27][28][29][30][31][32][33][34][35][36][37]. It is revealed during this survey that the effects of material and process variations on the overall part accuracy during the execution of a bending sequence is not reported in literature to the best of authors knowledge.…”

Integrated sheet-metal production planning for laser cutting and bending

“…Research has been conducted on optimisation of the bending process, mainly focusing on tool selection and bend sequencing (Lin 1995, S.K. Ong 1997, Duflou 2005, Nguyen 2005).…”

A manufacturability advisor for spun and rollformed sheet metal components

“…• Draft angle for vertical walls is lower than 0.5 • ; this causes excessive wear, so make it greater than or equal to 0.5 • • Bending radius for feature 2 should be greater than the specified stock thickness of 3 mm • Length of unformed feature 3 should be less than 125 mm; parts wider than 125 mm have a tendency to show waviness • Groove between features 5 and 9 is not feasible as grooves should not be deeper than 1.5 times the width • Bending radius for feature 10 should be greater than the specified stock thickness of 3 mm • Length of formed leg 15 should be greater than 9 mm, i.e., three times the stock thickness • Form depth is exceeding the maximum permissible 100 mm • Fillet radii for features 16,18,20, and 22 should be greater than 0.08 mm; fillet radii less than this are very difficult to manufacture • Hole feature 24 should be at least three times stock thickness (9 mm) away from part edge feature 23 • Hole feature 26 should be at least three times stock thickness (9 mm) away from bend feature 2 5.4 Advisor output for example part IV (rollforming)…”

“…Most of the these papers covered manufacturability by machining processes and only a few dealt with sheet metal components [6][7][8][9][10][11]. Further, papers which have been published on automated manufacturability evaluation of sheet metal components are often restricted to parts manufactured by bending and other forming processes [12][13][14][15][16][17]. We did not come across any automated manufacturability assessment system for sheet metal components being discussed in the literature, which dealt with spinning or rollforming processes.…”