Field of the Invention

The present invention relates to a crane hook and use thereof. Background of the Invention

There exist different solutions for cranes lifting, transporting and erecting items with a height which is several times larger than the width of the item.

Examples of such an item are tower segments of wind mills, segments of chimneys and similar constructions.

When erecting wind mill tower segments two cranes are often used of which one crane is the main crane which lifts the upper end of the wind mill tower section. The second crane is called the help crane and lifts the lower end of the wind mill tower to support the lower end of the segment while the main crane erects the tower segment from horizontal to vertical position.

Tower segments of wind turbines are usually hollow and comprise a flange at the inner surface at each end for attaching one segment to the next segment being arranged on top of the first segment etc.

When erecting such items, the crane hook of the help crane usually grabs the flange of the lower end of the tower segment. Then the segment is lifted in horizontal position by the two cranes and, if necessary, transported in horizontal position to the erection position. During erection of the tower segment from horizontal position to vertical position, the main crane lifts the upper end of the tower section while the help crane supports the lower end in slightly lifted position to support the lower end of the tower segment.

During erection of the tower segment the hook of the help crane may cause torsion and/or bending forces to the area in which it grabs the flange of the lower end of the tower segment which may cause deformation of the lower end flange and/or the lower end of the tower section and/or may cause deformation to or wreck the crane hook.

Conventional crane hooks are usually C-shaped. When a C-shaped hook is attached to the flange of a wind mill tower segment, the hook on the help crane will be rotated during erection of the tower segment from horizontal position to vertical position resulting in that the lifting point at the crane is not positioned directly above the attachment to the flange on the inner surface of the tower section. This causes torsion to the C-hook, which may cause the deformation described above.

In addition, there is a risk that the wire and/or the attachment means which attaches the C-hook to the wire is dragged below the lower edge of the tower, and that the lower end of the tower then is lifted with forces acting on the hook, the attachment means attaching the wire to the hook and/or the wire during and in particular after being erected from horizontal to vertical position. This may cause the attachment means and/or the wire to be positioned below the hanging load of the erected tower segment. If the load on the attachment means and/or the wire causes either of them to break, it may result in an extremely dangerous situation for the workers, e.g. by the broken wire slashing around. In addition, since the tower segment is no longer supported properly by the help crane, there is a risk that the tower segment starts moving or swinging which may cause injury to the workers. In addition, the wire or wire attachment means may rub towards the lower end of the tower segment and result in scratches, dents or similar damages to the lower end of the tower segment.

US 3091492 A discloses a crane hook for use in foundries that comprises two hook arms where the hook arms are mounted in a rotatable manner on a clevis member and held in place by a bolt. The tips of the hook arms point away from each other and the angle between the hook arms are provided as an inverted V-shaped configuration.

DE 102011 118498 A suggests a solution to this problem by providing a generally C- shaped crane hook with a gripping area which is provided in a rotatable element provided in a bearing provided at the C-hook. The rotatable element is attached to the flange at the lower end of the tower segment and rotates as the tower segment is erected while also supporting the lower end. When this type of hook is attached to a flange on the inner surface of a hollow oblong body, e.g. a wind mill tower element, to be lifted and then erected into upright position, the hook is no longer in equipoise when the wind mill tower is in an upright position. This will cause the hook to start swinging when hanging freely in the wire after the grip is released. The swinging of the hook will most probably result in the hook bumping into the tower element and cause damage to the tower element, such as scratches, dents and/or even formation of cracks.

Object of the Invention

It is an object of the present invention to provide means for lifting items which is easy to use.

It is an object of the present invention to provide means for lifting items which is safe to use.

Further, it is an object of the present invention to provide means for lifting items, which leaves no marks on the item lifted and/or which reduces or eliminates any deformation of the body and/or a flange on the body in which the body is lifted.

Description of the Invention

The drawbacks of the prior art mentioned above as well as the objects above are met by the present invention which provides a crane hook with a hook element having a mouth intended for gripping around an item to be lifted. The crane hook is special in that said crane hook comprises a hook body to which a lifting wire of a crane is attachable at an upper end of the hook body at one or more wire fastening means, where two hook elements are mounted to the hook body in a rotatable manner at the lower end of the hook body and with the mouth of the hook elements facing away from each other, each hook element comprising an upper end having a hole for engaging a hook mounting shaft for rotatable attachment of each of the hook elements to the hook body, and where a toothed rim is provided at a part of the upper edge of the hook element which surrounds the shaft, and where the hook body further comprises at least one locking mechanism for locking the position of the hooks when at a predetermined position. Hereby is obtained a crane hook with significantly reduced tendency to start swinging when the grip is released after lifting and erecting oblong items with a height being several times the width. This further reduces or even eliminates the risk of damaging and or deformation of the item, such as scratches, dents and/or formation of cracks. In addition, the design of the crane hook provides low risk of causing damage to the item caused by torsion on the hook during lifting and erecting of the oblong item into upright position. Torsion on the hook while it is attached to the lower end and/or a flange connected to the lower end may cause damage to the lower end of the tower.

The crane hook according to the present invention is particularly used when lifting and erecting oblong items, i.e. items with a height several times larger than the width, into upright position from horizontal position to vertical position. The crane hook is in particular used on the help crane which assists the primary crane, by lifting and maintaining the lower end of the oblong item into position during erection thereof.

In the present application, the present invention is illustrated in use when erecting tower segments of wind turbines, although not being limited to the use in connection with lifting and/or erecting tower segments of wind turbines. The present invention is equally applicable for use when lifting and subsequently erecting other similar items in particular items with a height which is larger than the width. Other examples of such oblong items are e.g. chimney elements. In addition, the crane hook is applicable for lifting and/or erecting of oblong items, it only requires that the mouth of the hook elements is angled differently in order to be able to grip the edge of a plate shaped element. In this case the mouth of the hook elements will be substantially horizontal, and thus perpendicular to the lifting direction.

Wind mill tower segments typically comprise a flange along the lower end of the inner surface to which the crane hook from at least the help crane is attached during lifting and/or erection of the.

The upper end of the body of the crane hook is attached to a crane's lifting wire by means of an attachment means. The hook elements are attached to the lower end of the hook body. The J-hook elements are in the following also called J-hooks. The J refers to the shape of the hooks, as their shape may be generally be described as resembling a J.

The J-hooks are attached to the hook body by hook element mounting shafts on which the J-hooks are rotatable. When J-hooks are not lifting an item they are resting with the back against each other. Thus, the angle A between the J-hooks is 0°. In this position the crane hook is in equipoise in relation to the point at the upper end of the crane body in which it hangs from the crane wire. Thus, the crane hook will hang stable from the crane wire and not make any unintended movement which could potentially cause damage to the tower.

When lifting an oblong item and subsequently raising it from lying to upright position one of the two J-hooks are attached to the lower end of the tower segment. The mouth of the J-hook grips the flange along the lower edge of the inner surface of the tower segment when the tower segment is in horizontal position. The two cranes lift the tower segment horizontally until it is free of the ground. Then the lifting of the help crane is stopped, while the main crane continuously lifts the top end of the tower section.

During erection of the tower segment to vertical position, the two J-hook elements are rotated in synchronous manner because the toothed rims on the upper end of the hook elements interact with each other and acts as cog wheels, which causes the J-hooks to rotate away from each other synchronously to provide an angle A between the two J- hooks. The Angle A increases as the tower segment comes into vertical position.

When the tower segment is raised to vertical position, the angle A is increased to its maximum. The angle A between the J-hooks in this position is 160-240 degrees, preferably 180-200 degrees, or substantially horizontal position. The locking mechanism acts on at least one of the J-hooks to lock the J-hooks in this position at the maximum angle A.

Thereby the J-hook can easily be released from attachment to the flange at the lower end of the tower segment simply by moving the help crane towards the tower segment and/or by pulling a line which may be attached to the crane hook. The crane hook will detach from the tower, and because the position of the J-hooks is locked, the J-hooks will stay in this substantially horizontal position, i.e. the position of the crane hook is in equipoise in relation to the attachment point of the crane wire at the upper end of the hook body. Thus, any unintended movement, e.g. swinging, of the crane hook which could damage the paint or surface of the tower segment, e.g. by scratches or dents is elegantly prevented

Preferably, the hook body comprises two oppositely facing parallel side plates between which the two J-hooks are mounted on the hook shafts. The hook shafts are mounted perpendicularly to the outer surfaces of the plates, which are parallel thus suspending the J-hooks

Hereby is obtained that the stability of the crane hook is even further improved, because the J-hooks are then positioned in the same plane as the point of attachment for the crane wire. In addition, the side walls of the crane body protects the cog-wheellike mechanism and the locking mechanism from mechanical impacts or e.g. splashes of water, mud or the like which could otherwise affect the action of the cog-wheel like interaction between the J-hooks and/or the locking mechanism and cause need for cleaning and/or repair thereof.

Preferably, the locking means comprises at least one rotatable locking cam arranged in the hook body and a shoulder at the upper end rim of at least one of the hook elements, where said locking cam is intended for preventing reverse rotation of the hooks when the locking cam engages the shoulder on the rim on the hook element.

Hereby is obtained a simple and effective locking mechanism which locks the J- hooks in position with the maximum angle A between them as described above. Further, the J-hooks are maintained in their second stable position which reduces the risk of movement of the crane hook after being released from the flange of the tower segment after erection.

Preferably, each hook element comprises a head end for attachment to the hook body having a generally circular form with the hole for the shaft preferably arranged at the centre of the generally circular head end and a hook member having a generally J shaped form extending from the head end.

Hereby is obtained that the toothed rim of the two hooks can interact and cause synchronous rotation of the J-hooks in relation to the crane body.

The crane hook may preferably comprise a stabilising means which is attachable to at least one of the hook elements.

In case the flange on the tower segment is too weak for the lift, and/or there is a risk that the tower section will be oval during the lift, the stabilizing means can be attached to a number of positions along the flange, such as two additional positions which are preferably mirrored in relation to a vertical axis through the position of the J-hook. The stabilising means are e.g. two brackets where each bracket is at one end attached to each side of the J-hook which is used in lifting action, and to the flange in the opposite end. This prevents the tower segment from becoming oval during the lifting action and/or damage to the flange is prevented. The stabilizing means will eliminate any need for attachment of a stabilizing frame around the lower end body of the tower segment as is standard procedure today.

The above mentioned objects and effects of the present invention are also met by use of a crane hook as described above for lifting and/or erecting of items having a height which is several times larger than the width of the item using two cranes, where a main crane lifts the upper end of the item. A help crane lifts and supports the lower end of the item, and where the crane hook is used on the help crane.

As also discussed above, the crane hook is preferably used for lifting of segments of a tower of a wind turbine or segments of a chimney where said segments comprise an upper and lower end and attachment flanges at the inner surface of the segments and where the crane hook engages the flange when lifting the segment.

As also described above the use of the hook may comprise use of a stabilising frame which is attached to the crane hook, i.e. the J-hook, which lifts the lower end of the tower segment and which is attached to the lower end flange at at least two additional positions.

Description of the Drawing

In the following, the present invention will be described with reference to the drawing in which

Fig 1 shows the crane hook in perspective view in starting position

Fig 2 shows the crane hook in a side view

Fig 3 shows the crane hook in exploded view

Fig. 4 shows the crane hook with the two hooks partly rotated

Figs 5-18 show different situations during erection of a wind mill tower using the crane hook, some of which show the hook in detail while some of the figures show the position of the cranes and the wind mill tower during erection, and

Fig 19 shows the crane hook used in combination with a stabilising frame

Detailed Description of the Invention

Figs. 1-3 show the crane hook 1 according to the invention in perspective, in a side view and in exploded view respectively.

The crane hook 1 is provided with hook elements 3a, 3b being generally J-shaped. A mouth area 4 is intended for gripping around an item to be lifted, such as a frame of a tower segment.

The crane hook 1 comprises a hook body 2 to which a crane wire of a crane (wire and crane is not shown in figs 1-3) is attachable at an upper end of the hook body 2 at one or more wire fastening means 12, 13.

The fastening means for the crane wire is e.g. an eye mounted on the hook body, a wheel/roller rotatably attached to the hook body, a shackle 13, or a bolt through two eyes on the hook body 2. Two hook elements 3a, 3b, i.e. the J-hooks, are mounted to the hook body 2 in a rotatable manner at the lower end of the hook body. The mouth 4 of the J-hooks 3a-3b faces away from each other. The hook elements 3 a, 3b comprise an upper end having a through-going hole 5 for engaging with the hook mounting shaft 6 for attaching the J- hooks 3 a, 3b to allow rotation of the J-hooks on the hook shafts 6. A toothed rim 7 is provided at a part of the upper edge of hook element which surrounds the shaft hole 5. This upper end area of the J-hooks 3a, 3b is substantially circular to allow the toothed rims 7 of the J-hooks to interact as cog wheels.

Preferably, the hook body 2 comprises two oppositely facing parallel side plates 10a, 10b, between which the two J-hooks 3a, 3b are mounted on the hook shafts 6. The hook shafts 6 are thus mounted perpendicularly across the free area 11 between the side plates 10a, 10b and the J-hooks are attached to the hook shafts 6 between the side plates 10a, 10b.

The J-hooks 3a, 3b can rotate on the hook shafts 6 in synchronous manner because the toothed rims 7 on the two J-hooks interact. This causes the angle A (see fig. 4) between the J-hooks to increase.

To prevent the J-hooks from returning to vertical position, the locking means comprises at least one rotatable locking cam 8 arranged rotatably in the hook body 2 and a shoulder 9 next to the toothed rim 7 to the end of the toothed rim which faces the mouth 4 of the J-hook 3 a. There is at least one locking cam 8 and a corresponding shoulder 9 on at least one of the hook elements 3 a, 3b. The locking cam 8 is intended for preventing reverse rotation of the J-hooks 3a, 3b when the locking cam 8 engages the shoulder 9. A handle 18 or similar manually operated actuation means, e.g. an electrical actuator, such as a battery operated actuator or hydraulic actuator, may be provided for releasing the locking cam 8 from engagement of the shoulder 9 to release the J-hooks and allow them to obtain the original vertical position.

The crane hook according to the present invention is particularly used when lifting and erecting oblong items to vertical position, i.e. items with a height several times larger than the width, into upright position from horizontal position to vertical position. This is shown in figs. 5-18. A main crane 16 lifts the upper end of the tower segment 15 while the help crane 17 lifts the lower end of the tower segment 15. The crane hook 1 is in particular used on the help crane 17.

Wind mill tower segments typically comprise a flange 19 along the upper and the lower end of the inner surface. The crane hook 1 of at least the help crane is attached to the flange 19 during lifting and/or erection of the tower segment.

The mouth 4 of one of the J-hooks 3a grips the flange 15 when the tower segment 15 is in horizontal position, see figs. 7-9. The two cranes lift the tower segment horizontally until it is free of the ground. Then the lifting of the help crane is stopped, while the main crane continuously lifts the top end of the tower section.

During lifting and subsequently during erection of the tower segment to vertical position, the two J-hooks 3a, 3b are rotated on the hook shafts 6 in a synchronous manner because the toothed rims 7 on the upper end of the hook elements interact with each other and act as cog wheels. This causes the J-hooks 3a, 3b to rotate away from each other synchronously to provide an angle A between the two J-hooks, see fig 3, fig. 8, fig. 12, and fig. 15. The Angle A increases as the tower segment comes into vertical position.

When the tower segment is raised to vertical position, the angle A is increased to its maximum. The angle A between the J-hooks in this position is 160-240 degrees, such as 180-200 degrees, or slightly above substantially horizontal position, see fig. 13 or 15. Thereby the locking cam 8 passes over the shoulder 9. The locking mechanism allows the J-hooks to rotate slightly backwards before the locking cam 8 engages the shoulder 9 to lock the J-hooks 3a, 3b in substantially horizontal position, see fig. 18.

Then J-hook 3 a can be released from attachment to the flange 19 at the lower end of the tower segment simply by moving the help crane 17 towards the tower segment see figs 14-17. The crane hook 1 will detach from the tower segment 15, and because the position of the J-hooks 3a, 3b is locked, the J-hooks will stay in this substantially horizontal position, i.e. the position of the crane hook 1 is in equipoise in relation to attachment point 12 of the crane wire at the upper end of the hook body 2. Thus, any unintended movement, e.g. swinging of the crane hook which could damage the paint or surface of the tower segment, e.g. by scratches or dents, is elegantly prevented.

As shown in fig. 19 the crane hook 1 may preferably comprise stabilising means 20, which are attachable to the J-hook 3b which lifts the tower segment 15.

In case the flange 19 on the tower segment is too weak for the lift, and/or there is a risk that the tower section will be oval during the lift, the stabilizing means 20 can be attached to a number of positions along the flange 15. The stabilising means are e.g. two brackets 20a, 20b where each bracket is at one end attached to each side of the J- hook 3b, and to the flange 15 in the opposite end.