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With the number of 3D CAD models increasing rapidly, retrieving models of similar parts has become an important activity as existing designs may contain vital information regarding design and manufacturing. This paper is targeted at retrieving and comparing sheet metal parts. In the method proposed herein, the general shape of a sheet metal part is represented by a simplified hierarchical tree wherein the nodes represent the planar walls of the part and feature-related information is attached to these nodes as textual attributes. A shape index is derived from this simplified tree and subsequently used to retrieve similar parts from the database. The retrieved parts are assessed for their similarity with the enquiry part using five criteria: the general shape of the part, bends and their direction, feature types, feature location and feature size. In addition to determining the degree of similarity, the main advantage of the proposed method is that the assessment provides useful feedback to design and manufacturing engineers based on these five criteria. A prototype system developed in C++ has been tested on a database containing a few hundred parts and the effectiveness of the proposed method in retrieving and comparing the parts is discussed. [ABSTRACT FROM AUTHOR]

Sheet metal parts with high-quality surface have wide applications in many manufacturing procedures. However, polishing these parts are challenging due to occurrence of deformations at contact area between the polishing tool and part. This stems from the thinness of these parts, making them susceptible to deformations, compared to thick solid parts. To address the above challenge, this study proposes a new robotic polishing path planing method that accounts for such deformations. The proposed method starts by estimating the contact area between the tool head, and the free-form surface of the sheet metal part is estimated using Hertz theory and differential geometry. Next, it uses a polynomial equation—that is derived from FEM-based contact analysis of the part—to calculate the true tool-part contact area under deformations. Then, it combines the contact-area information with a new constant speed robot path planing technique to ensure high-quality robot polishing. Numerical studies on several sample geometries verify the effectiveness of the method. [ABSTRACT FROM AUTHOR]

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