Investigation of the pressure generated in the mould cavity during polyurethane integral skin foam moulding

Abstract

Abstract. An industrial scale measuring system was set up to investigate the pressure arising in the mould cavity during polyurethane integral skin foaming. The system is able to measure the pressure arising in the mould cavity and the pressure distribution using a piezoresistive pressure sensor. The pressure distribution was measured at 18 points along the mould surface at constant production parameters. Then six production parameters, which affect the pressure, were investigated in detail with the Taguchi method of experimental design. The results of the design were processed by ANOVA (analysis of variance). Three major influencing parameters were estimated by regression analysis. Finally an equation was developed to give a good estimation to the pressure arising in the mould cavity.

Rediseño y Automatización de un Molde para la Fabricación de Vitrinas Refrigeradas usando Inyección de Espuma de Poliuretano

“…En la revisión de la literatura muy poco se encuentra acerca de la presión real en el interior del molde. En [12] se realiza una medición obteniendo un valor máximo de 1,6 bares. Sin embargo, esta medición está muy relacionada con el tipo de molde utilizado.…”

“…Los parámetros de presión y densidad son muy importantes para la industria de la espuma de poliuretano, ya que la densidad es un requerimiento del producto a fabricar y la presión es esencial para fabricar el molde que contendrá la fuerza de expansión de la espuma. Pero el cálculo de la presión en el interior del molde y por lo tanto el diseño del molde, se basa en la experiencia del diseñador y ciertas estimaciones adicionales las cuales hacen que el mode quede sobredimensionado [12].…”

Structural and mechanical properties of flexible polyurethane foams cured under pressure

“…So far, attention has mostly been paid to the pressure build-up as well as the methods and techniques to detect the pressure in closed molds during foaming. 10 – 15 More fundamental research, both experimental as well as theoretical, on foaming power and the pressure generated in the foam bubbles during the foaming of 2C PU foam systems was conducted by Beruto et al 16 The influence of different surrounding pressures in the range 0.7–1.3 bar absolute pressure on the production of flexible 2C PU foams in slabstock production and its potential to control the density, and microstructural, and related properties was described by Cloakaerts and Mortelmans 17 in 1994. A linear relationship (Equation (1)) between the resulting density ρ p of polyurethane slabstock foam and the surrounding pressure p p was derived employing the ideal gas theory 17 with the standard atmospheric pressures p a and ρ a being the density of foam with equal chemical composition raised and cured at standard ambient conditions ( p a = 1 bar atmospheric pressure).…”