Feed unit for strip wrapping material

摘要

A strip of wrapping material is advanced by a feed unit that includes a gumming device composed of a gumming roller and a transfer roller contra-rotating about horizontal and parallel axes and in tangential contact one with another along an area coinciding with a straight line generator common to both. At least one of the two rollers is maintained at a given temperature by a fluid directed through a circuit of which a first portion extends along a shaft supporting and driving the roller and a second portion is located internally of the roller itself; the circuit includes valves operating respectively along a flow branch and a return branch of the circuit, associated both with the drive shaft and with the respective roller and interposed between the first and second portions so that these can be opened and closed when required, while the first portion is connected to an inlet duct and to an outlet duct rigidly associated with a frame and connected to the circuit by way of a hydraulic or pneumatic rotary coupling.