Abstract: An apparatus for welding webs of synthetic thermoplastic material as they move around a deflecting roller comprises an elongate housing, which is movable toward the deflecting roller to assume a position in which said housing is approximately concentric to said roller and closely surrounds said roller around a part of its periphery, and said housing is provided with at least one longitudinally extending hot-air duct, which is curved in the same sense as the housing and is provided with an inlet for receiving flowing hot air and is formed with a plurality of outlet bores or gaps in that wall of the housing which faces the deflecting roller.

Abstract: Apparatus for manufacturing webs of synthetic thermoplastics comprises a machine frame, a cooling roller mounted in said machine frame and provided with drive means, and an extrusion die mounted in said machine frame and spaced above said cooling roller and connected to a supply line for molten plastic material and having a die slot which faces the cooling roller and is parallel to a generatrix of said roller, also comprising two electrodes, which in the direction of rotation of the cooling roller precede the slot and are disposed adjacent to the lateral end portions of the slot and mounted in the machine frame and directed toward the cooling roller, and electric cables electrically connected to the electrodes and to the cooling roller. The electrodes consist of brush electrodes consisting of wire ends arranged like a brush.