Heated tool flash welding of polyethylene pipes at low temperatures of the environment: investigation of the cooling process

摘要

In this study, the possibilities of regulating the cooling rate of welded joints by controlling the process of convective heat exchange using a heat-insulating chamber are theoretically substantiated. An increase of the temperature of the air in the chamber as a result of heat transfer from the surface of the pipe and the flash reduces the cooling rate of the wall. The temperature of air in the heat-insulating chamber, which depends on the dimensions of the chamber, may be used as the controlling parameter of the convective heat exchange rate. Thus, the cooling rate at low air temperature may be regulated by varying the dimensions of the chamber and using the heat stored by the welded material in flashing. As a result of the low heat capacity of air and transfer of approximately the same amount of heat from the internal surface of the welded joint, the temperature inside the pipe does not differ greatly at different temperatures of the surrounding air. This can also be confirmed by calculations.