Heat treatment of synthetic yarns.

摘要

The present specification discloses an oven foruse in the orientation and heat setting of synthetic yearns and filaments. One known oven comprises an elongate chamber (1) through which a filament to be processed is passed, hot gas being introduced intot he chamber (1) near to the region where the filament enters the chamber. The hot gas is introduced into the chamber (1) under pressure in the general direction of filament travel and thus heats the filament as it passes through the chamber (1). However there is a problem as the hot gas quickly reduces in temperature due to the heat absorption by the filament and also due to the expansion of the gas as it enters the chamber (1). Thus very little heating is found to take place after the filament has passed through the jets of hot gas on entry into the chamber (1). The present invention provides an oven comprising an elongate chamber (1) with an inlet orifice (5) at one end and an outlet orifice (7) at the other end, via which a filament can pass through the chamber (1). Primary nozzles (15) for use in introducing hot gas into the chamber (1) are arranged, together with a gas outlet port (13), adjacent to the said one end (5) of the chamber (1). Preferably the outlet port (13) is nearer to the said one end (5) than the primary nozzles (15). Secondary nozzles (17) also for introducing hot gas into the chamber (1) are arranged adjacent to the other end (7) of the chamber. In use, hot gas is fed under pressure into the chamber (1) via the primary and secondary nozzles (15,17) against the direction of filament travel. Whilst the hot gas is fed under high pressure through the primary nozzles (15), the hot gas is fed at a relatively low pressure but high volume through the secondary nozzles (17). In this way the filament is heated all along its length in the chamber (1).