METHOD AND AN APPARATUS FOR SURFACE TREATMENT OF AN ELONGATED STRUCTURE E.G. A WIND TURBINE BLADE

A method for treatment of a surface (1) of an elongated structure e.g. a wind turbine blade is described. The method includes abrading the surface and cleaning the surface. The method comprising the steps of: - providing an abrasive head which comprises a housing containing abrasive lamellae (9) of an abrasive sheet, such as abrasive fabric, of which a front side (10) has abra- sive properties and which extend from an rotatable base of the abrasive head and which abrasive lamellae are supported on a back side by an elastic support element comprising support brushes (12) having almost the same length as the lamellae and which housing is provided with a suction outlet for removal of abrasive dust, - rotating the rotatable base in a first direction whereby the front side (10) with the abrasive properties is abrading the surface (1) of the elongated structure while moving the abrasive head across the surface following a path in a first direction from a first edge to a second edge, which first direction is transversal to the longitudinal direction of the elongated structure, - reversing the rotation of the rotatable base or rotating the abrasive head 180°, - moving the abrasive head across the surface following the same path in the opposite direction from the second edge to the first edge whereby the support brushes (12) brush the surface and thereby remove abrasive dust from the abraded surface (1) in the path, -translating the abrasive head along the longitudinal direction of the elongated struc- ture with a distance corresponding to the width of the path and repeating the abrading and cleaning for a neighboring path until the elongated structure is treated.