Development of a Cooling Die Used in Plastic Pipe Processing: Numerical and Experimental Analysis

Abstract

In this study, cooling of a plastic pipe-end during a hot-forming process that is one of the commonly used forming methods in plastic pipe production to get seal housing place (muff) was investigated numerically and experimentally. The aim of this study was development of a cooling die that has higher cooling performance and easier manufacturability. Cooling is supplied by the circulation of conditioned water in the channels located in the die in plastic production. The geometry of these channels and mass flow rate and temperature of the cooling water are the parameters affecting the quality of the formed region and process time. In the study, experimental analyses were performed, then numerical analyses were realised and validated with the experimental results for the existing die geometry. Continuity, momentum and energy equations were solved all together and heat transfer was investigated. After validating the model, a few different alternative die models were proposed and analysed to get an optimum which has highest cooling capacity and process ability. At the end of these studies, optimum alternative die geometry was determined. The channels in the suggested die were developed to increase the homogeneity of the cooling by changing the existing channel's shape which can be produced by only longitudinal holes. A simple production method was also suggested for the new die to locate the channels following the circumference of the pipe, like conformal cooling channels. Additionally, aluminium material was also used to decrease the pipe temperature and die weight in the analyses. In conclusion, although cooling process time and mean temperature of the pipe-end were 30 secs and 43.9 o C respectively for the existing cooling die, these values were determined as 30 secs and 39.5 o C for the optimised aluminium die. If the temperature of the cooled pipe is taken as the same with the existing cooling, the cooling time decreases to around 20 secs for the suggested die. The weight of the die was reduced from 86.57 kg to 16.22 kg.