COATING THICKNESS CONTROL

摘要

This invention relates to the control of thickness of a coating applied to the surface of a sheet material. The invention provides an air knife assembly (15) including a body (14) for mounting adjacent to a sheet material which in use is moved past the body in a longitudinal direction, and a mouth (16) facing the sheet material and extending laterally with respect to the direction of movement of the sheet. The mouth (16) is defined by a pair of facing lips (17, 18) which are movable relative to the body (14). A moving means (41) is operable to move the lips (17, 18) relative to the air knife body (14). The assembly further includes a means for distributing a fluid under pressure through the body to enter and emerge from the mouth whereby pressurised fluid emerging from the mouth operates on a coating applied to a surface of the sheet material passing the air knife to thereby control the thickness of the coating.