Bolted joint for a wind turbine blade
According to some implementations a bolted joint for modular blades is provided that comprises a single bolt that joins the inserts incorporated on the flange of the beam, screwing the two modules facing each other. A spacer is added to each bolt, and the bolts is then pre-tensioned by pulling, either mechanically separating the modules with a mechanical separator or thermally by applying heaters to the bolt and coolers to the spacer, or by torqueing the bolts.
1. A method of connecting first and second modules of a wind turbine blade, each of the first and second modules having a plurality of respective first and second threaded inserts that respectively have first and second surfaces that face one another, the method comprising:
joining the first and second modules by the use of a plurality of bolts, each bolt having a first threaded end and a second threaded end, the first threaded end being threaded into one of the first threaded inserts and the second threaded end being threaded into one of the second threaded inserts by rotating the bolt in a first direction, the bolt being rotated to produce a gap having a first length, the first length being a distance between the facing first and second surfaces of the respective first and second threaded inserts; and
simultaneously tensioning the plurality of bolts by:
(a) applying a force to mechanically separate the first and second modules in a manner to simultaneously elastically elongate the plurality of bolts and to produce a gap having a second length between the first and second threaded inserts, the second length being a distance between the facing first and second surfaces of the respective first and second threaded inserts, the second length being greater than the first length, the plurality of bolts including a first number of bolts and the force being applied by a second number of mechanical separators, the first number being greater than the second number,
(b) inserting one or more spacers having a third length in the gap having the second length, the third length being greater than the first length and less than the second length,
(c) terminating applying the force so that the bolts elastically shorten and a gap of the third length is established between the first and second threaded inserts.
2. The method according to claim 1 , wherein each of the first and second threaded ends of each bolt comprise right-handed threads.
3. The method according to claim 1 , wherein each of the bolts is at least partially surrounded by one of the spacers.
4. The method according to claim 1 , wherein prior to joining the first and second modules each of the first and second threaded inserts is respectively integrated into a composite material laminated portion of the first and second modules.
5. The method according to claim 1 , wherein the one or more spacers are respectively positioned on one or more of the plurality of bolts.
6. The method according to claim 1 , wherein applying the force to mechanically separate the first and second modules includes applying a first force to the first threaded insert in a first direction and applying a second force to the second threaded insert in a second direction opposite the first direction.
7. The method according to claim 6 , wherein the first force is applied to a face of the first threaded insert and the second force is applied to a face of the second threaded insert.
8. The method according to claim 6 , wherein the first force is applied to a side of the first threaded insert and the second force is applied to a side of the second threaded insert, the first and second forces being applied to the first and second sides of the respective first and second threaded inserts by the use of pins extending into the sides of the first and second threaded inserts.