Research Papers

Automated Flexible Forming Strategy for Geometries With Multiple Features in Double-Sided Incremental Forming

[+] Author and Article Information
Ebot Ndip-Agbor

Department of Mechanical Engineering,
Northwestern University,
2145 Sheridan Road,
Evanston, IL 60208
e-mail: ebot@u.northwestern.edu

Kornel Ehmann

Department of Mechanical Engineering,
Northwestern University,
2145 Sheridan Road,
Evanston, IL 60208
e-mail: k-ehmann@northwestern.edu

Jian Cao

Department of Mechanical Engineering,
Northwestern University,
2145 Sheridan Road,
Evanston, IL 60208
e-mail: jcao@northwestern.edu

Manuscript received April 11, 2017; final manuscript received October 30, 2017; published online December 21, 2017. Assoc. Editor: Gracious Ngaile.

J. Manuf. Sci. Eng 140(3), 031004 (Dec 21, 2017) (10 pages) Paper No: MANU-17-1246; doi: 10.1115/1.4038511 History: Received April 11, 2017; Revised October 30, 2017

Double-sided incremental forming (DSIF) is a dieless sheet metal forming process that uses two generic tools to form a part of arbitrary geometry from a clamped sheet via the accumulation of small localized deformations. In DSIF, there is a need for an automatic toolpath generation method to separate geometric features coupled with a strategy to form these features in the correct sequence such that they can be accurately formed. Traditional CNC machining toolpaths are not suitable for DSIF because these toolpaths are designed for material removal processes, which do not have to account for the motion of the virgin material during the process. This paper presents a novel and simple way to represent geometric features in a hierarchical tree structure during z-height-based slicing along with algorithms to generate different forming strategies using this tree structure. The proposed approach is demonstrated through physical experiments by forming a complex part with multiple features.

Copyright © 2018 by ASME
Topics: Algorithms , Geometry
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Fig. 1

Incremental forming strategies: (a) SPIF and (b) DSIF

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Fig. 2

Illustration of a complex geometry: (a) isometric view and (b) exploded view showing features and their curvatures

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Fig. 3

Relationships between intersection curves: (a) on the same z-height and (b) on adjacent z-heights

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Fig. 4

Relationship map for a geometry: (a) intersection curves at two slicing planes, (b) in-plane relationship maps for curves on slicing plane 1 and (c) curves on slicing plane 2, (d) out-of-plane relationship maps for curves on slicing plane 1 and (e) curves on slicing plane 2

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Fig. 5

Algorithm for constructing in-plane and out-of-plane relationship maps

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Fig. 6

Algorithm for combining curves into features

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Fig. 7

(a) Rooted tree data structure showing parent, left child, and right sibling attributes of each node and (b) rooted tree representation of geometric features

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Fig. 8

Recursive algorithm for building feature tree from feature relationship map

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Fig. 9

Strategy 1—forming parent features before child features

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Fig. 10

Strategy 2—Forming child features before parent features

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Fig. 11

Experimental setup showing top, bottom tool, and clamps

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Fig. 12

Arbitrary complex geometry: (a) top view, (b) bottom view, and (c) exploded view with features annotated

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Fig. 13

Feature tree and forming strategies for test geometry: (a) feature tree, (b) strategy 1 forming sequence, (c) strategy 2 forming sequence

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Fig. 14

Experiment for strategy 1

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Fig. 15

Experiment for strategy 2

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Fig. 16

(a) Sections A-A and B-B profiles in desired geometry, (b) section A-A, and (c) section B-B profiles both comparing strategies 1 and 2 to desired geometry



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