Verfahren und Vorrichtung fuer das UEberziehen von Metallstraengen

In coating a metallic strand 13 with molten metal 12, the temperature of the strand as it enters a molten bath 10 is maintained substantially constant thereby improving adherence and reducing dross formation. The strand 13 (e.g. strip, tubing or wire) passes through a furnace 14, a hood 16 and the molten metal 12 (e.g. Zn, Al, Sn or terne). As it passes through the hood, a heat-sensitive photo-detector 19 which operates in the infrared portion of the spectrum senses its temperature and a recording and controlling instrument 21 sends impulses to a control mechanism 23 for heating and/or cooling means 17. Coating may be by the method disclosed in Specification 453,803. Furnace gases and other contaminants present in the hood are prevented from reaching the optical part of the heat-sensing device by means illustrated in Fig. 2. A sensing device 25 is mounted at one end of a barrel 26 which screws at its other end into the hood. The device 25 is protected by a quartz lens 28 which in turn is protected by flushing gas (indicated by arrows) and also by gas entering at 39 and passing through ports 38 to form a conical curtain.