Computer-Aided Mold Design Modification for Product Design Change

The design of a plastic product may be changed many times during its mold design and manufacturing processes. Most existing commercial CAD systems cannot automatically modify the mold design if the design parameters of the part model and its injection mold are not available. This paper proposes a novel mold design modification algorithm for handling frequent product design changes. With the proposed algorithm, the modified region is identified by comparing the old and new plastic parts and the affected mold components are then modified. As the mold may need to be modified at different mold machining stages, different mold design modification methods have been developed separately for them. If the mold has been machined, an insert can be designed automatically for the region that needs extra material. If an insert is designed, a pocket will also be created automatically at the affected region to hold the insert. In such a case, the possible interference between the pocket and the holes in the mold will be detected. Different shapes of pockets and inserts are designed based on the interference condition in this algorithm and various types of fasteners will be modeled automatically for different inserts. As the proposed mold design modification algorithm does not rely on the product parameters that increase with the complexity of the product and the mold, the algorithm is applicable to both parametric and non-parametric parts. The algorithm has been tested with many industrial parts; it is proven to be able to modify the mold design automatically and efficiently according to the mold machining status for both parametric and non-parametric designed parts.