Abstract: Arc welding control apparatus includes a laser (10) for projecting a first reference mark (24) along a first axis onto the line of a weld (26) and a video camera (12) arranged to view the work piece along a second axis to generate a video image including the first reference mark. The apparatus is mounted on a welding torch for movement therewith, the first and second axes intersecting at a predetermined point relative to the video camera. Sensor control means (30) receives the video signal from the video camera, and generates a composite video signal representing the original image with an image of a second mark superimposed therein. The position of the second mark is adjustable within the image frame. The position of the welding torch is set such that the welding electrode is positioned with the first mark projected onto the line of the weld ahead of the torch. The location of the second mark is adjusted within the image frame such that it is aligned with the first mark.

Abstract: A rolling mill (1) for rolling metal strip has provision for applying discrete levels of liquid coolant to the strip and the temperature (te) of the strip leaving the mill is compared with a target temperature (ts) and the temperature (Te) the incoming workpiece is compared with a target temperature (Ts). The difference signals are employed to control the levels of liquid coolant and the rolling speed so that the exit temperature remains substantially equal to the target exit temperature.