Method and equipment for repairing the roots of wind turbine blades

Abstract

Method and equipment for repairing the roots of wind turbine blades, by drilling on the root of the blade, and through the ring thereof, radial bore holes located in positions that radially match the axial threaded blind holes of the ring; grinding and drilling the axial threaded blind holes to remove the thread, and to achieve the extension of the ground axial holes until they reach the matching radial bore hole; introducing, into each radial bore hole, a pin provided with a threaded diametral passage aligned with a threaded axial hole of the ring; screwing bolts into the axial threaded blind holes and threaded diametral passages, for fastening the blade to the hub of the wind turbine. The equipment has a support that can be fastened to the reinforcement ring and a head for carrying radial and axial drilling tools.

Claims

1. 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, 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, the 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.

2. 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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A possible embodiment given by way of non-limiting example is shown in the attached drawings, in which:

(2) FIG. 1 shows a front view of the root of a wind turbine blade.

(3) FIG. 2 shows, on a larger scale, a section of the blade root and ring contained therein, taken along section line II-II of FIG. 1.

(4) FIG. 3 shows a view similar to FIG. 2, with a radial bore hole going through the wall of the root and the ring.

(5) FIG. 4 shows a view similar to FIG. 3, with the ground and extended axial blind holes.

(6) FIG. 5 shows a view similar to FIG. 4, with a pin housed in the radial bore hole.

(7) FIG. 6 shows a perspective view of the pin with its threaded diametrical passage included in the radial bore hole of FIG. 5.

(8) FIG. 7 shows a perspective view of the ring with equipment for repairing assembled therein.

(9) FIG. 8 shows a section of the ring, in which the making of the radial bore holes by means of the equipment of FIG. 1 can be seen.

(10) FIG. 9 shows a section similar to FIG. 8, in which the grinding and extension of the threaded axial blind holes can be seen.

DETAILED DESCRIPTION OF AN EMBODIMENT

(11) FIG. 1 shows a plan view of the blade root incorporating a ring (1) provided with several threaded axial blind holes (2) into which the threaded bolts (3) are screwed, FIG. 2, for fixing to the bearing of the wind turbine hub.

(12) The section view of FIG. 2 shows a crack (4) in the ring, the propagation of which can cause the blade to break and fall off.

(13) To eliminate this problem, according to the invention, a series of radial bore holes (5) are made in the blade root, FIG. 3, going through the ring (1), and located in axial positions coinciding with at least part of the threaded axial blind holes (2) and preferably with all of said threaded axial blind holes.

(14) The axes of all the radial bore holes are located on one and the same plane, perpendicular to the axis of the blade, said plane is located between the bottom of the threaded axial blind holes (2) and the edge (6) with the smallest section of the ring (1). Furthermore, these axes are coplanar with and perpendicular to the axes of the coinciding threaded axial blind holes (2).

(15) As shown in FIG. 4, the threaded axial blind holes (2) are ground and extended by means of the corresponding tool to eliminate the thread at least partially and extend said hole until it reaches the coinciding radial bore hole (5), a ground axial blind hole (2′) having a greater depth being obtained.

(16) As best seen in FIG. 6, a pin (7) which is provided with a diametrical passage (8) with an inner thread is arranged in each radial bore hole (5), FIG. 5. The pins (7) are arranged such that the threaded diametrical passages (8) are aligned with the ground axial holes (2′).

(17) The radial bore holes are made such that they are shifted towards the edge (6) with the smallest section of the ring, with respect to the position of the crack (4).

(18) Threaded bolts (3′) that are longer than the original bolts (3), with the same measurement as the measurement of the threaded passages (8) of the pins (7), FIG. 5, are inserted through the ground axial holes (2′), screwed into said passages, to be used as means for anchoring the blade to the wind turbine hub.

(19) The pins (7) will have a diameter that is almost the same as the diameter of the radial bore holes (5) and an adhesive and/or a sealant can be applied between them to assure the attachment of the pin in the radial bore hole and prevent the rotation or movement of the pin with respect to the passage in which it is housed, in the event of disassembling the blade, providing at the same time more robustness to the assembly.

(20) When the pins (7) do not have the threaded diametrical passage (8), said bore hole must be made once the pin is assembled in the radial bore hole (5), an operation that will be carried out by means of the corresponding drilling and thread-making tool inserted through the ground axial hole (2′).

(21) In order to perform the different grinding, drilling, and screwing operations, equipment such as the one shown in FIG. 7 can be used, said equipment being made up of a support (9) configured for being assembled in and fixed on the reinforcement ring (1) through its threaded axial blind holes (2), and a head (10) which is assembled in the support (9) in a selectable position.

(22) The head (10) comprises a central body (11) with radial arms (12) projecting therefrom, each of which holds radial drills (13) and axial drills (14) which make up the means for making radial bore holes (5), grinding and extending the threaded axial blind holes (2), and where appropriate, producing the threaded diametrical passages (8).

(23) The support (9) consists of a star-shaped structure made up of a central core (15) and radial profiles (16). The central body (11) of the head (10) is suspended from the central core (15) with ease of rotation and height adjustment. The radial profiles (16) are screwed on the threaded axial blind holes (2) and the ends of the radial arms (12) are positioned in the threaded axial blind holes (2) of the ring through positioning elements made up of retractable dowels or balls (12′), for example.

(24) FIG. 8 shows the production of the radial bore holes (5) by means of a radial drill (13), whereas FIG. 9 shows the operation of grinding and extending the threaded axial blind holes (2) until reaching the radial bore holes (5) by means of an axial drill (14) which will be replaced, where necessary, with the tool required for producing the diametrical passages (8) and for making threads therein.

(25) Once the different operations described in a first position of the equipment have come to an end, the head (10) is rotated to carry out the same operation in the next position, in which a new group of radial bore holes (5), ground axial holes (2′), etc., is obtained. This goes on until the required operations come to an end.

(26) To machine the position corresponding to the starting position of the radial profiles (16), the star-shaped structure is rotated and fixed to adjacent holes which allow accessing the radial arms (12) with tools.

(27) In order to make positioning the pins (7) in the radial bore holes easier so that the diametrical passage (8) of said pins is aligned with the corresponding ground axial blind hole (2′), said pins will have on one of their faces an indentation (7′), FIG. 5, for example, a housing for an Allen key, which allows them to be easily rotated until reaching the position of alignment mentioned above. Similarly and to make the placement thereof easier, the threaded bolts (3′) can have a recess, indentation, or slot (3″), for example, for an Allen key, which allows them to rotate and be screwed into the threaded diametrical passages (8) of the pins (7) without any damage to their thread.

(28) The dimension and the alignment of the threaded axial blind holes (2) with the diametrical passages (8) is assured by utilizing the pre-existing threaded axial blind holes of the ring (1), as well as the geometry of the root, to position the described equipment.

(29) Preferably, the diametrical passages (8) will be made to coincide with all the threaded axial blind holes (2) of the ring (1), or at least in a sufficient number to eliminate the effect of the existing cracks (4), the risk of the occurrence of new cracks, and to assure a robust attachment of the blade to the wind turbine hub.