Method for obtaining an ejection map in injection molded parts

Résumé

In this paper, a new methodology for automated geometrical layout localization and dimensioning of the ejection system elements of a plastic injection mold is presented. The proposed method focuses on an analysis of the discretized geometry of the plastic part. Thus, a nodal quadrature on the part surfaces belonging to core plate is generated. Then, the map of the ejector pins on the plastic part surface is obtained by means of the analysis of variations in the part thickness and the distance between nodes of the quadrature and the vertices of the original mesh. To conclude, the dimensioning of the optimal ejection system is performed through a genetic algorithm. This new method does not require heuristic techniques to achieve its goal and does not employ features as a tool for the geometrical recognition of the surface of the plastic part, avoiding the problems of dependency from the CAD modeller. The proposed methodology provides the cartesian coordinates, diameter and ejection force of each ejector pin. The results can be exported and used in others CAM/CAE applications.