Optimization of the heating parameters of a robotized hot incremental forming of high impact polystyrene

Abstract. Single point incremental forming (SPIF) is a modern rapid manufacturing technology able to manufacturing complex sheet parts in small quantities. In comparison to conventional deep-drawing process, complex tools can be dispensed in order to reduce tool costs and the time required to achieve the first finished part. This new technology consists of locally and iteratively deforming plastically the sheet material by a punch that is generally hemispherical and of small dimensions, whose trajectory is programmed on a numerically controlled machine or a robot arm. The parts formed are mainly made from metallic materials (steel, aluminum, titanium or copper alloys). Very few studies focus on the incremental forming of thermoplastic parts. Because of the poor formability of thermoplastic parts and the large spring-back at room temperature, the use of heating systems of the work-piece during the forming process is required. In this work, a novel incremental sheet forming assisted by heat transfer was developed to improve the formability of thermoplastic sheet. By means of a series of experimental forming of High Impact Polystyrene pyramid frustum with constant wall angle at different heat temperatures, geometric accuracy was recorded and analyzed. This study aims to evaluate the behavior of polymer material in the hot incremental sheet forming with different pre-heating system using the finite element method.