Lifting tool

Abstract

The present invention describes a lifting tool (1) comprising: a clamping device (10) configured to engage around the shaft (30) of the fastener (3); a yoke (16) for connecting the lifting tool (1) to a crane hook (20); and suspension means (18, 180) adapted to suspend the clamping means (10) from the yoke (16) such that the clamping means (10) is free to rotate about a horizontal axis (1X). A method of lifting a fastener (3) from a horizontal position (PH) to a vertical position (PH) using an embodiment of the lifting tool (1) is also described.

Description

Background Art

[0001] During the construction of a large tower, such as a wind turbine tower, it may be necessary to join adjacent flanges using fasteners such as bolts, stud bolts, etc. For example, a flange at the base of the tower may need to be bolted to an anchor ring of the foundation. Likewise, adjacent tower sections may be connected by inserting fasteners into holes of complementary flanges.

[0002] The type of flange bolts used to connect parts of a tall wind turbine tower may be stud bolts of appropriate diameter (M64, M80, etc.) and length of about 80 cm. Such flange bolts may weigh 40 kg or more, and many of them may be needed to connect a flange having a diameter of about 6.5 m to 9 m. The flange bolts may be transported to the base of the tower on a pallet, and then each bolt must be raised to the flange height. Manually lifting such heavy objects is avoided to avoid causing injury. Instead, it is preferred to deploy a lifting tool to lift the heavy flange bolt from its horizontal storage position, turn it into a vertical position, and lower it vertically into the through hole of the flange.

[0003] In a known method, a lifting tool including a strong electromagnet is used to lift the flange bolt in a two-step procedure. The lifting tool is suspended from a crane hook, and the crane can be operated to raise the hook (and the suspended load) to a higher level. In the first step, a magnet is placed along the middle section of the shaft of the flange bolt placed in a storage unit such as a pallet, and the flange bolt is lifted laterally to an intermediate position, where it is briefly "parked" in a position that allows the magnet to be repositioned (i.e., disengaged from the shaft and attached to the head of the flange bolt). The crane is then operated to raise the hook, causing the flange bolt to be "flipped" to a vertical position. The crane is then operated to raise the vertically suspended flange bolt to a desired position, such as to a level above a tower flange assembly, and the flange bolt is lowered into a through hole of the flange assembly. Due to the two independent steps and the need to manually adjust the position of the magnet, the known method is quite time-consuming. In addition, the accessories of the magnetic tool are usually specially designed for a specific bolt size, such as only for lifting M64 bolts. However, a build project may require large fasteners with different diameters, such as an M64 bolt at one connection interface and a heavier M80 bolt at another connection interface. The need to provide more than one magnetic tool increases the overall cost of the build. This approach is also more time consuming and dangerous due to the additional step of having to disconnect one tool from the crane so that another tool can be deployed. Summary of the invention

[0004] It is therefore an object of the present invention to provide a method of lifting heavy fasteners which avoids the problems discussed above.

[0005] This object is achieved by the claimed lifting tool and by the claimed method of lifting a fastener.

[0006] According to the invention, the lifting tool comprises: a clamping device, which is configured to engage around the axis of the fastener; a yoke, which is used to connect the lifting tool to the crane hook; and a suspension device, which is suitable for suspending the clamping device to the yoke so that the clamping device can rotate freely around a horizontal axis. In order to suspend the clamping device to the yoke so that the clamping device can rotate freely around the horizontal axis, the suspension device should be understood to include a pair of connection points, which are diametrically opposite on the clamping device. The suspension device also includes a pair of connecting members, each of which extends between the outer end of the yoke and the connection point. The diametrically opposite connection points define a horizontal axis, about which the clamp can rotate.

[0007] An advantage of the lifting tool of the present invention is that it can lift a fastener from an initial horizontal storage orientation to a final vertical installation orientation in a single motion, i.e., without having to reposition or rearrange the lifting tool. The gripping means of the lifting tool of the present invention can be positioned to fit around the axis of a horizontally lying fastener. As the lifting tool is raised, the suspension means allows the gripping means to tilt, thereby allowing the heavy fastener to assume a favorable vertical position, below and substantially in line with the crane hook. In this vertical position, the suspended fastener can be lifted to its intended destination.

[0008] According to the present invention, a method of using such a lifting tool to lift a fastener from a horizontal position to a vertical position includes the steps of engaging the clamping device of the lifting tool around the axis of the horizontally oriented fastener; attaching the yoke of the lifting tool to a crane hook; and operating the crane to raise the lifting tool to a height at which the weight of the fastener causes the clamping device to rotate about its horizontal axis, thereby allowing the fastener to assume a vertical orientation.

[0009] The method of the present invention has the advantage that the number of handling steps during the fastener lifting action is minimized. The clamping device only needs to be positioned once and does not need to be repositioned at any time during the lifting action. The clamping device is placed on the fastener in its initial horizontal storage position and does not need to be operated again until it is removed from the fastener's final vertical installation position. In this way, the lifting tool helps to comply with health and safety regulations in the workplace.

[0010] Particularly advantageous embodiments and features of the invention are given by the dependent claims, as revealed in the following description. Features of different claim categories may be combined as appropriate to give further embodiments not described herein.

[0011] In the following, it may be assumed that the lifting tool of the invention is deployed to lift the wind turbine tower flange fasteners from a storage location near the tower base to the level of the tower flange. Furthermore, it may be assumed that a crane, such as a telescopic boom crane, is deployed to lift the load (i.e. the lifting tool and the flange bolts) from its initial position to a higher final position.

[0012] In the following, without limiting the invention in any way, it may be assumed that the flange bolt is a threaded rod, also referred to as a stud or stud bolt, which is sized for insertion through a hole in a flange of a wind turbine tower. A nut screwed onto the end of the stud bolt is used to create tension, i.e. tighten the flange connection. Without limiting the invention in any way, the stud bolt may be a self-tapping stud bolt, a double-ended stud bolt, a fully threaded stud bolt, etc. The stud bolt for connecting a wind turbine tower flange may have a diameter of about 64 mm or more and a length of about 80 cm. In the following, it is understood that the weight of such a stud bolt may be 40 kg or more.

[0013] A stud bolt is a fastener without a head, instead a nut is screwed onto each (usually chamfered) end and turned with a wrench. Heavy duty studs of the type used to connect wind turbine tower flanges may be shipped with a nut already in place at the "upper end" so that the stud can be lowered into place into the flange hole. The lower nut can then be screwed onto the downward pointing end of the stud.

[0014] The clamping device is implemented to clamp the shaft of the stud bolt during the lifting action and may be referred to as a "clamp" hereinafter. The size of the clamp is preferably set to engage around a shaft with a diameter of at least 56 mm, that is, to hold at least an M56 bolt. The clamp can be constructed in any suitable way. In a particularly preferred embodiment of the present invention, the clamping device includes a first jaw and a second jaw rotatably connected to the first jaw. For example, the jaws can be connected by means of a pivot hinge, thereby allowing the jaws to be opened so that the clamp can be placed in place around the stud or removed from the stud. The clamp is preferably constructed so that when the jaws are "closed", the clamp achieves good contact with the stud bolt shaft.

[0015] In a preferred embodiment of the invention, the gripper is constructed to include a locking device to fix the jaws in their "closed" position. The locking device can be implemented in any suitable way, for example, after the gripper is placed around the axis of the stud, a strap can be wrapped around the jaws. In a particularly preferred embodiment of the invention, the locking device is implemented as a cam-action indexing plunger. Preferably, the locking device is arranged close to the hinge between the jaws so that the locking device can be easily accessed during the initial stage of placing the gripper around the axis of the horizontal bolt, that is, the worker does not need to reach into the narrow space that may exist between or under the heavy flange bolts lying flat on the pallet in order to manipulate any locking device. Preferably, the gripper jaws are constructed so that the body of the locking device is attached to one jaw, and when the gripper is in place around the stud axis, the plunger can extend into the matching hole formed in the other jaw. This configuration allows very fast locking and unlocking of the gripper, and also ensures that the gripper remains locked until the plunger is released.

[0016] As explained above, it may be necessary to lift fasteners having different shaft diameters. Therefore, in a particularly preferred embodiment of the invention, the gripper is provided with a diameter adjustment device, which is implemented to adjust the working diameter of the gripper between a first load diameter and a second load diameter. The term "working diameter" is to be understood as the diameter of the largest circle that can fit between the gripper jaws in the "closed" position of the gripper jaws. The diameter adjustment device can be implemented in any suitable manner, for example by providing pairs of arcuate arms, each pair being shaped to fit around a fastener having a specific diameter, and attaching a suitable pair of arcuate arms to the gripper jaws prior to the lifting procedure.

[0017] In a particularly preferred embodiment of the present invention, the diameter adjustment device is implemented as a pair of rotatable arcuate arms. Each arcuate arm is located on the clamp jaw and fixed by a pivot joint. In the default position, the arcuate arm is aligned with its clamp jaw. The diameter adjustment device also includes a position setter for each arcuate arm so that the arcuate arm can be rotated to different working positions, in which one end of the arcuate arm extends into the space between the clamp jaws, thereby reducing the working diameter of the clamp. In a preferred embodiment of the present invention, the position setter includes a longitudinal gap in the clamp jaw and a fastener for fixing the corresponding rotatable arcuate arm at the selected position. The diameter adjustment device allows the clamp to be used to lift stud bolts with a certain range of diameters, such as between 54mm (M54) and 80mm (M80). Preferably, the rotatable arcuate arm is formed by injection molding a synthetic polymer such as polyoxymethylene (POM), which has favorable properties such as high hardness and low friction.

[0018] The suspension arrangement allows the gripper to be suspended from a yoke or crane cradle in such a way that the gripper can freely rotate about a horizontal axis. This can be achieved in a number of ways, for example the gripper and yoke can be connected by a pair of vertically extending arms terminating in a pivot joint. Likewise, the suspension arrangement can be achieved by constructing the crane cradle as a kind of shackle and constructing each gripper jaw to include a "clevis pin" at one end.

[0019] The diametrically opposed connection points on the gripper can be implemented in any suitable manner. In a preferred embodiment of the invention, the connection points are eyelets on both sides of the gripper, and the chain preferably extends vertically between each eyelet and the outer end of the yoke. Suitable wires, ropes or cables can be used instead of chains. The inherent flexibility of the chain, rope or cable allows the jaws of the gripper to move apart or open to facilitate placing the gripper around the bolt axis and facilitate removing the gripper from the bolt axis. The yoke or crane hanger is preferably at least as wide as the gripper. The diametrically opposed eyelets define the horizontal axis of rotation of the gripper. Connecting such a chain, rope or cable to the gripper through the eyelet ensures that the gripper can rotate freely around the horizontal axis. In a preferred embodiment of the invention, the eyelet is arranged close to or on a line extending through the diameter of the stud shaft surrounded by the gripper. With this advantageous configuration, the horizontal axis of rotation of the gripper coincides with the diameter of the stud, thereby allowing the center of mass of the load to be located substantially directly below the crane hook. Thus, the heavy stud can be lifted from its horizontal storage position to its vertical installation position in one smooth movement.

[0020] The method of the invention preferably includes a preparatory step: two nuts are arranged on the "upper end" of the stud shaft, with sufficient space between the first nut and the second nut to easily accommodate the clamping device. In a first step, the clamp is placed around the stud shaft into position between the two nuts, and the lock is actuated to hold the clamp jaws in the "closed" position. The crane is then actuated to raise the lifting tool, thereby gradually lifting the stud from its horizontal position. As the lifting tool is raised, the weight of the stud held by the clamp causes the clamp to tilt, allowing the stud to assume a vertical position with its center of mass substantially below the crane hook. In this vertical position, the stud is raised to the flange and the crane is actuated to guide the stud into the flange hole. After the stud is lowered into the flange hole, the weight of the stud is carried by the lower nut. It is then simple and direct to remove the clamp from between the upper and lower nuts. The upper nut can then be removed and placed on the lower end of the stud in preparation for the bolt tightening procedure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other objects and features of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. It should be understood, however, that the accompanying drawings are designed for illustration purposes only and are not intended to limit the limits of the present invention.

[0022] Figure 1 An exemplary embodiment of a lifting tool of the present invention is shown;

[0023] Figure 2-9 shows the stages in a lifting procedure using an embodiment of the lifting tool of the present invention;

[0024] Fig.10 and 11 Other exemplary embodiments of the lifting tool of the present invention are shown;

[0025] FIG. 12 illustrates a prior art bolt lifting procedure.

[0026] In the drawings, like numbers refer to like objects throughout. Objects in the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0027] Figure 1 An exemplary embodiment of a lifting tool 1 of the present invention is shown. The lifting tool 1 comprises a gripper 10 having a pair of jaws 10A, 10B, which in this example are connected by a pivot hinge 100. A yoke 16 allows the lifting tool 1 to be suspended from a hook 20 and a cable 200 of a crane 2, as shown. The gripper 10 is freely suspended from the yoke 16 by a pair of chains 180, one chain on each side of the gripper 10. The upper end of each chain 180 is attached to the yoke 16 by an eyelet 18, and the lower end of each chain 180 is attached to the gripper 10 by an eyelet 18.

[0028] Figure 2-9 1 shows the stages in a lifting procedure using an embodiment of the lifting tool of the present invention. Figure 2 In the first stage shown in FIG. 1 , the clamp 10 is positioned around the axis 30 of the flange bolt 3. Here, the flange bolt 3 is shown lying horizontally on the pallet 5. The worker can manually open the jaws 10A, 10B of the clamp 10 to allow them to fit around the axis 30, as shown by the arrows. The worker can then Figure 3 As shown in ( Figure 31 (a cross section taken between the upper nut and the lifting tool) shows the locking of the jaws 10 by actuating the lock 14 to prevent the jaws 10A, 10B from moving, as indicated by the curved arrow. Here, the lock 14 is implemented as a cam-acting indexing plunger. Turning the operating lever of the lock 14 causes the pin to extend into the corresponding hole of the left jaw 10A, so that it can no longer move relative to the right jaw 10B. This figure shows the working diameter D30 of the lifting tool 1, i.e. the diameter D30 of the stud 3.

[0029] The crane is then operated to raise the lifting tool 1 so that the "upper end" of the bolt 3 is raised upward, as shown in FIG. Figure 4 and Figure 5 The weight of the flange bolt 3 causes the clamp 10 to gradually tilt about its horizontal axis 1X. When the stud 3 leaves the solid ground (its lower end is no longer in contact with the support plate), the weight of the stud 3 causes it to assume a substantially vertical position, as shown in FIG. Figure 6 , and the holder 10 is substantially horizontal. Figure 7 In the embodiment, the vertically suspended flange bolt 3 has been raised to the tower flange assembly and lowered through the matching holes of a pair of tower flanges 4. Once the lower nut 32 of the flange bolt 3 rests on the flange surface, the clamp 10 can be opened by actuating the lock, such as Figure 8 As shown in Figure 8 A plan view from above is shown. The release lock 14 allows the jaws 10A, 10B to be opened so that the lifting tool 1 can be removed from the flange bolt 3, as shown in FIG. Fig. 9 , i.e., a worker can manually open the jaws 10A, 10B of the clamp 10 to allow the clamp 10 to be removed from around the shaft 30, as shown by the arrows.

[0030] By leaving a gap between the lower nut 32 and the upper nut 34 that is slightly larger than the height of the jaws and the arcuate arms, it is possible to facilitate placement of the clamp around the bolt axis (e.g. Figure 2 ) and remove it again (as shown in Fig. 9 The appropriate size gap is Figure 7 Shown in.

[0031] Fig.10Another exemplary embodiment of the lifting tool 1 of the present invention is shown, in which the clamp 10 can be adjusted to be used with loads having different diameters. For this reason, a diameter adjustment device 12 is provided. In this embodiment, the diameter adjustment device 12 is implemented as a pair of rotatable arcuate arms 12A, 12B and a pair of position setters 120, 122. Each rotatable arm 12, 12B can pivot around a connector 126 (e.g., a metal screw). Each position setter includes a longitudinal slit 120 in the clamp jaws and includes a fastener 122, which is used to fix its rotatable arcuate arm at a selected position. The diameter adjustment device 12 allows the clamp 10 to be used for loads with diameters within a specific range Dmin-Dmax, as shown in the figure. For example, the clamp 10 and the diameter adjustment device 12 can be implemented as flange bolts for diameters between 54mm (M54) and 80mm (M80).

[0032] Fig.11 Another exemplary embodiment of the lifting tool 1 of the present invention is shown. This embodiment illustrates two further features which can be implemented independently of each other in any of the embodiments described above. Here, a biasing spring 102 is arranged between the jaws 10A and 10B of the gripper 10. The biasing spring serves to keep the gripper 10 in its closed position as an additional safety measure during lifting events.

[0033] The second feature illustrated in the figures is an alternative diameter adjustment device 12, which is implemented as a rotatable nose 124. In its first end position (as shown by the dashed line), the nose 124 allows the clamp 10 to fit around the maximum flange bolt diameter Dmax. In its second end position (as shown here), the nose 124 ensures that the clamp 10 will fit around the minimum flange bolt diameter Dmin. The intermediate diameter can be "set" by rotating the nose 124 an appropriate amount. The position of the nose 124 is fixed by tightening the screw 122, as shown here.

[0034] FIG. 12 illustrates a prior art method for lifting a heavy flange bolt, in which, in a first stage illustrated on the left, an electromagnet 7 suspended from a crane is placed on the shaft 30 of the bolt 3, which is placed in an initial horizontal storage orientation 70. The bolt 3 is then lifted to an intermediate orientation 71, in which the head of the bolt 3 is freely accessible, as shown in the middle. The electromagnet 7 is then detached from the shaft 30 and reattached to the bolt head. The bolt 3 can then be raised to a vertical position 72 (as shown on the right) and subsequently lifted to the level of the flange. This procedure is time consuming due to the various steps involved. In addition, a power supply is required to activate and deactivate the electromagnet 7. Due to the strong magnetic field generated during the activation of the electromagnet 7, additional safety requirements must be observed in order to avoid harm to personnel.

[0035] Although the present invention has been disclosed in the form of preferred embodiments and variations thereof, it will be appreciated that many additional modifications and variations may be made to the present invention without departing from the scope of the present invention. For example, the lifting tool of the present invention may be used to lift a heavy-duty screw, i.e., a fastener having a threaded shaft and a head, by placing a gripper near the head of a horizontally placed heavy-duty screw. The lifting tool may also be deployed to lift the heavy-duty fastener onto a pallet to prepare for transport to an installation site. After the fastener is lowered into a horizontal position on the pallet, the gripper may be easily separated from the fastener.

[0036] For the sake of clarity, it is to be understood that the use of "a" or "an" throughout this application does not exclude a plurality, and "comprising" does not exclude other steps or elements.

Claims

1. A lifting tool (1), comprising: - a clamping device (10) configured to engage around the axis (30) of the fastener (3); - a yoke (16) for connecting the lifting tool (1) to a crane hook (20); and - suspension means (18, 180) suitable for suspending the holding device (10) to the yoke (16) so that the holding device (10) can rotate freely around a horizontal axis (1X).

2. A lifting tool according to the preceding claim, the suspension means comprising a pair of eyelets (18) on either side of the clamping device (10) and a chain (180) extending from each eyelet (18) to the outer end of the yoke (16).

3. A lifting tool according to any one of the preceding claims, wherein: The horizontal axis (1X) extends through the eyelet (18) and substantially coincides with the diameter of the fastener shaft (30) encompassed by the clamping device (10).

4. A lifting tool according to any one of the preceding claims, wherein: The clamping device (10) is dimensioned to surround a surface having a diameter (D 30 ) is engaged with a cylindrical shaft (30).

5. A lifting tool according to any one of the preceding claims, wherein: The clamping device (10) includes a first clamping jaw (10A) and a second clamping jaw (10B) rotatably connected to the first clamping jaw (10A).

6. A lifting tool according to any one of the preceding claims, comprising a diameter adjustment device (12) for adjusting the working diameter (D 30 ).

7. A lifting tool according to any one of the preceding claims, wherein: The clamping device (10) comprises an anti-slip material arranged to abut against the surface of the fastener (3).

8. A lifting tool according to any one of the preceding claims, comprising a locking device (14) configured to fix the position of the second jaw (10B) relative to the first jaw (10A).

9. A lifting tool according to any one of the preceding claims, wherein: The locking device is a cam-acting indexing plunger (14).

10. A lifting tool according to any one of the preceding claims, suitable for lifting fasteners (3) having a weight of at least 40 kg.

11. A method of using a lifting tool (1) according to any one of claims 1 to 10 to lift a fastener (3) from a horizontal position (P H ) to the vertical position (P H ), the method comprising the steps of - engaging the clamping device (10) of the lifting tool (1) around the axis (30) of the horizontally oriented fastener (3); - attaching the yoke (16) of the lifting tool (1) to a crane hook (20); - operating the crane (2) to raise the lifting tool (1) to a height at which the weight of the fastener (3) causes the gripping device (10) to rotate about its horizontal axis (1X), thereby allowing the fastener (3) to assume the vertical position (P v ).

12. The method according to the preceding claim comprises a preparatory step of arranging a first nut (32) and a second nut (34) onto one end of the fastener shaft (30) with a gap between the first nut (32) and the second nut (34) to accommodate the clamping device (10).

13. A method according to any one of the preceding method claims, wherein: The lifting tool (1) is deployed to lift a wind turbine tower flange fastener (3) from ground level to the level of a tower flange (4).

14. The method according to any one of the preceding method claims, operating the crane (2) to lower the fastener shaft (30) vertically into a flange through-hole.

15. A method according to any one of the preceding method claims, comprising the step of actuating the lock (14) to release the clamping device (10) from the fastener shaft (30).

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