Method and equipment for repairing the roots of wind turbine blades

A method for repairing wind turbine blades, comprising a reinforcement ring embedded in a blade root, provided with threaded axial blind holes for receiving threaded bolts for fixing to a wind turbine hub through a bearing, a support configured for being fixed to the reinforcement ring, and a head which is assembled in the support in a selectable position, which head holds means for making radial bore holes in the reinforcement ring, through the wall of the root, each intended for receiving a pin, and means for axially grinding and drilling the threaded axial blind holes, eliminating the thread of said holes and extending same until they reach the coinciding radial bore holes,

• which method is particularly conceived to prevent the occurrence and/or propagation of cracks in said reinforcement ring, the method comprising:
• a) making on the reinforcement ring, through a wall of the blade root, a series of radial bore holes, axes of which are located on one and a same plane perpendicular to an axis of the blade, coplanar with and perpendicular to the axes of the threaded axial blind holes, and located axially between a plane containing a bottom of said threaded axial blind holes and a plane containing an edge with a smallest section of the reinforcement ring;
• b) grinding and drilling the threaded axial blind holes to eliminate a thread and extend said ground axial holes until they reach a coinciding radial bore hole;
• c) inserting into each radial bore hole a pin which has a diameter that is approximately the same as the diameter of the radial bore hole, is provided with a threaded diametrical passage having a diameter slightly smaller than the diameter of said ground axial hole, and positioned in alignment with a ground and extended axial hole;
• d) inserting through the ground and extended axial holes bolts having a measurement coinciding a measurement of the threaded diametrical passage of the pins, and screwing the bolts into said threaded diametrical passages for anchoring the blade to the wind turbine hub;
• e) making the radial and axial holes at the same time, by radial and axial drilling means synchronized in more than one position, with an on-site portable precision drilling tool, with a support and a head, both referenced to the ground threaded axial blind holes to ensure the needed alignment accuracy for being able to assembly the bolts to the pins in a following operation.