WO2011127935A1

WO2011127935A1 - Lifting equipment and method for using such a lifting equipment

Info

Publication number: WO2011127935A1
Application number: PCT/DK2011/050119
Authority: WO
Inventors: Jørgen HANGEL
Original assignee: Conelto Aps
Priority date: 2010-04-12
Filing date: 2011-04-11
Publication date: 2011-10-20

Abstract

Lifting equipment, for elevating objects, where the lifting equipment engages the outside of the objects, where said lifting equipment comprises two or more lifting towers, where each lifting tower is provided with engagement means for engaging the object to be lifted, and where said towers extend substantially vertically from a lifting surface to and above a predefined lifting height, where lifting means are provided for hoisting the engagement means upwards, and where each engagement means is provided with two relatively displaceable sliding means, where at least one of the means is provided with a surface facing the other means, where said surface is angled relative to the lifting direction.

Description

LIFTING EQUIPMENT AND METHOD FOR USING SUCH A LIFTING EQUIPMENT

Field of the Invention

The present invention is directed at a lifting equipment for lifting objects, in particular concrete elements, as well as a method for using said lifting equipment in order to elevate the concrete elements.

Background of the Invention

In the art there are a number of obvious and well proven manners in which to elevate objects such as concrete elements to a desired height. These usually include a crane, which will position the lower most panel/element first, and after having secured the position of this element, the following element will be placed on top of the previously placed element. This lifting procedure is very well proven and has a number of advan- tages, but when desiring to build especially tall constructions, the requirements to the crane construction increases, and at a certain construction height the cost of constructing, raising and dismanteling a crane suitable for the task becomes prohibitive.

Another method of building high structures is using a travelling or sliding scaffold or falsework where a substantially continious concrete casting process is used. As the concrete is placed inside the sliding falsework, the falsework is slowly elevated such that the sliding falsework is climping on the already cast concrete structure. Also this method has been used with success for raising relatively tall buildings/structures as a well proven concept and is usually carried out with a large degree of success. There are, however, some inherited disadvantages in using this method in that all concrete castings are carried out in situ, and therefore the conditions under which the concrete is cast is influenced by the ambient weather conditions such as for example rain, slow, wind etc.

All these influences may be detrimental to the finished structure or may at least slow down the process in that the hardening of the concrete is dependant on the ambient temperature. Furthermore, for constructions having varying in cross action along its longitudinal length, the sliding falsework will need to be adapted/rebuild in order to provide the desired cross section.

Object of the Invention

It is therefore an object of the present invention to provide a lifting equipment which provides for new and inventive advantages as compared to previously used methods as described above.

Description of the Invention

The present invention therefore provides a lifting equipment, for elevating objects, where the lifting equipment engages the outside of the objects, where said lifting equipment comprises two or more lifting towers, where each lifting tower is provided with engagement means for engaging the object to be lifted, and where said towers extend substantially vertically from a lifting surface to and above a predefined lifting height, where lifting means are provided for hoisting the engagement means upwards, and where each engagement means is provided with two relatively displaceable sliding means, where at least one of the means is provided with a surface facing the other means, where said surface is angled relative to the lifting direction. The two relatively displaceable sliding means, where at least one of the means is provided with a surface facing the other means, where said surface is angled relative to the lifting direction provides for a wedge like construction such that as the two relatively displaceable sliding means are displaced vertically relative to each other, the wedge shape will exert a radial pressure inwardly towards the object to be lifted such that as the engagement means are being elevated, the sliding means will exert sufficiently pressure in order to create a frictional connection with the object to be lifted, whereby the object is lifted together with the engagement means due to the frictional engagement between the engagement means and the object. The lifting towers may be spaced at various distances from lift to lift according to the requirement of the present object to be lifted. Furthermore the number of lifting towers may be varied according to the weight of the present object to be lifted. A flexible lifting equipment solution capable of lifting objects of a range of different sizes and weights is hereby provided, because there is no need to rebuild or perform substantial structural changes of the lifting equipment between individual lifting assignments.

In a furhter advantageous embodiment of the invention the lifting means comprises a wire connecting the engagement means to a winch, where a dead weight is connected to said winch, and that said wire passes at least one pulley between the engagement means and the winch.

This very well proven concept of using a wire connected via a pulley to a winch allows for a very simple yet very well proven and easy to operate lifting solution. Furthermore, by providing a dead weight, for example on the lifting tower or adjacent the lifting tower, it is easy to adapt the lifting equipment to any load necessary such that vari- ous sizes of objects may be lifted with the inventive lifting equipment. In this connection it should be remarked that naturally a system where a plurality of pulleys is used between the engagement means and the winch in order to lower the load on the wire and thereby lower the load on the winch may be implemented without further modifications by persons skilled in the art.

In a further advantageous embodiment the lifting means comprises a wire connecting the engagement means to a dead weight, and that said wire passes at least one pulley, between the engagement means and the dead weight, where at least one pulley is arranged at the distal end of a hydraulic piston, where said hydraulic piston moves verti- cally when activated.

This embodiment differs from the previously mentioned embodiment in that in place of a winch a hydraulic piston is used such that once the wire has been tensioned between the engagement means and a dead weight running over the pulley, activation of the hydraulic piston in a vertical direction will move the pulley upwards and thereby also move the engagement means upwards which in term lifts the object to be elevated. By reversing the direction of the hydraulic piston by moving it downwards, the pulley will be lowered and thereby also the engagement means will be lowered. In this embodiment an even lifting may be achieved by providing means for monitoring the oil pressure in the hydraulic pistons arranged in its lifting tower such that the same force is exerted in all the wires whereby a substantially vertical and linear lift of the object is achieved.

In a still further advantageous embodiment four lifting towers are arranged equidistant along a periphery of an imaginary circle, where a lifting surface is arranged inside said imaginary circle. Naturally depending on circumstances two or more lifting towers may be used in order to elevate the object, but once the object reaches a certain size and thereby a certain weight, it is advantageous for stability reasons to have three or preferably four or more lifting towers arranged equidistantly along the periphery of an imaginary circle, such that for control of the lifting process and guidance of the object to be lifted is achieved due to the position of the lifting towers substantially surround- ing the object to be lifted.

In a still further advantageous embodiment of the invention two or more engagement shells are provided, which engagement shells are fixed to one or two engagement means, such that each engagement shell has a surface facing the object to be lifted, sub- stantially corresponding to the contours of at least a section of the object to be lifted. Especially where a large number of substantially identical objects are to be lifted, the provision of engagement shells whereby a larger and better fitting friction surface will be established between the lifting means and the object is advantageous. In addition to providing a friction surface the engagement shells will also guide the object during the elevation process and thereby stabilize the entire operation.

In a still further advantageous embodiment of the invention the engagement means are provided with movable sledges, where said sledges are arranged for movement along the face of the lifting towers facing the object to be lifted, where said sledges maintains a constant distance between the lifting tower and the object to be lifted.

The sledges transfer the horizontal forces which are generated as the relatively sliding means engages the object to be elevated by friction thereby creating both a horizontal force and a vertical force, where the sledges assist in transferring the horizontal forces to the lifting towers and from there to the foundations of the lifting towers.

Typically, the lifting towers will be placed on and fastened to the structures foundation structure, which has been created prior to erecting the structure.

In order for the elevating process to be carried out completely linear, it is important that the sledges maintain a constant distance between the lifting tower and the object to be lifted such that no wobbling or horizontal displacement of the object due to the occurrence of horizontal forces or resistance between the sledges and the lifting towers occurs.

In a still further advantageous embodiment of the invention control means are provided on the lifting equipment, where the lifting means are provided with sensors, strain gauges, pressure sensors or the like, and that the engagement means are provided with laser reflectors, where input is collected from the control means and used in order to control, monitor and conduct the lifting process.

Naturally, when the lifting process only elevates very few objects to a relatively low height, it is relatively easy to make sure that the construction achieves the desired shape. However, for substantially higher constructions such as wind turbine towers which may reach 100, 120 or even 150 metres, it is very important to control with very high precession each object's precission and especially each object's relative precission relative to a neighbouring object in order to achieve a completely linear turbine tower. For these purposes it is important, with very high accuracy to register the exact position of each object.

In a further advantageous embodiment two or more parallel rails are arranged, where said rails pass between the lifting towers and extends a distance on either side of the lifting equipment, and where a trolley is provided which trolley is adapted to travel on the rails carrying objects to be lifted.

By providing rails between the lifting towers it is possible to prepare the following object to be elevated outside the lifting area, while the lifting process for another object is being executed. As the object is elevated it is possible to slide the next object into posi- tion underneath the just elevated object in accordance with the method of using the lifting equipment as will be further explained below.

As allready mentioned the invention is also directed to a method for elevating objects by means of lifting equipment as described above, where the method includes the following steps: a) the first object to be elevated is placed equidistant and centrally between the lifting towers;

b) the engagement means are fitted around the outer periphery of the object, and the engagement means are connected to the lifting means;

c) the lifting means are activated by means of a winch, whereby the engagement means are brought into frictional contact with the object to be lifted;

d) the continued activation of the lifting means elevates the object to a desired eleva- tion;

e) the following object to be elevated is placed equidistant and centrally between the lifting towers and superposed under the previously elevated object;

f) the previously elevated object is lowered until it rests on the object below;

g) the engagement means are released and lowered down into a position ready to en- gage the newly placed object;

steps b) through g) are repeated for each object.

From the method described above it is evident that the construction is build from the top down such that the first object to be placed in the lifting equipment will, once the structure is finished, be the upper most object. In this manner it is foreseen that the lifting equipment as such does not have to be able to lift the objects to the very top of the construction, but shall only be able to lift to a height corresponding to one, two or three objects which requires a much smaller construction. During the first cycle only one object is lifted by the lifting equipment, during the second cycle both the firstly placed and the second object will be lifted together, and in the third cycle the first, second and third object will be lifted together and so forth. As the objects are lowered unto themselves between each lift, it is relatively easy to stop the building process, should any unforeseen events or circumstances suddenly arise, in that the lifting equip- ment simply lowers the engagement means until all the objects are resting on top of each other, whereby a substantially steady construction is obtained.

As the weight is increased which the lifting equipment has to lift as more and more objects are positioned on top of each other, the winch or hydraulic means may be replaced by stronger means or a number of pulleys may be inserted such that the resulting force which the winch or hydraulic means has to overcome is relatively diminished. This is also possible due to the fact that between lifts there is no tension or substantially no tension in the lifting means such that it is possible to reconfigure the lifting means during operation i.e. during construction of for example a wind turbine tower.

Therefore, by simply repeating the steps of positioning an object below the just lifted object and lowering the first object down to the second object moving the engagement means into frictional contact with the almost object and hoisting the entire construction, it is possible in a very controlled manner to erect a relatively high construction.

In comparison to the sliding falsework described in the introductory part, with the present method, it is possible to manufacture the objects under factory conditions such that a homogeneous production of high quality may be achieved for all objects whereby improved and constant strength characteristics of all elements, homogeneous surface characteristics etc. are achievable compared to the in situ casting process used with for example sliding falsework. Also should adverse weather conditions hindering the casting process arise, the present method having all the objects cast under factory conditions, it is only the erection process which is influenced by weather conditions. In such conditions as already mentioned above, it is possible to halt the erection process simply by lowering the already elevated objects on to each other and maintain the erected structure in a stable position.

In order to further improve this the method in the further advantageous embodiment provides stabilizing lines connecting the uppermost object and optionally further objects below to discrete foundations arranged radially around the lifting equipment. By having these temporary means it is possible relatively quickly to stabilize the entire structure, should a storm or other adverse weather condition suddenly arise. As already mentioned above, the method builds the structure from the top down. For wind turbine towers, it is possible to mount the nacelle onto the uppermost element, such that this work may also be carried out at more controlled conditions. The turbine blades may be mounted at a relatively lower height than normal, providing savings in that the lifting equipment for lifting the blades to 120 or 150 meters may be saved, and replaced by lifting means being able to mount the blades in 70 meters height for example.

Description of the Drawing

The invention will now be explained with reference to the accompanying drawing where in

Figure 1 illustrates a side elevation of the lifting equipment;

Figure 2 illustrates a plane view of the lifting equipment on site;

Figure 3 illustrates the principle in the engagement means;

Figure 4 illustrates a schematically construction process of a tower

Detailed Description of the Invention

In figure 1 is illustrated a lifting equipment 1 on top of a foundation 2 for example for a wind turbine tower.

In this side elevation only two lifting towers 3, 4 are illustrated. Each tower 3, 4 is securely connected to the foundation 2 such that any forces arising during the elevation of the object, which in the following will be referred to as tower elements, will be transferred from the lifting mechanism to the foundation as will be explained below. Each lifting tower comprises a rail 5 which rail extends a certain height in a vertical direction where the height is sufficient to allow the tower element to be lifted more than the tower elements' own height.

Engagement means 6, 7 are connected to lifting means 8, 9 such that the engagement means 6, 7 may be lifted along the vertical rail 5 of the lifting towers 3, 4. The engagement means 6, 7 are provided with sledges 10, 11. In the illustrated embodiment three sledges are provided for each engagement means 6, 7. The purpose of the sledges is to allow the engagement means 6, 7 to freely travel along the vertical rails 5 of the lifting towers, and at the same time transfer any horizontal forces arising from the engagement means gripping the tower elements to be lifted.

The tower element 20 is arranged substantially centrally between the lifting towers 3, 4 as is evident from figure 2.

In order to improve the frictional contact between the tower element 20 and the engagement means 6, 7 the engagement means are provided with shells 12, 13 which shells 12, 13 substantially surround the tower element 20. In this manner the tower element 20 is fixed by the shell elements 12, 13 which are connected to the engagement means 6, 7. As the engagement means 6, 7 are lifted the engagement means will fric- tionly engage the tower element 20 as will be explained with reference to figure 3.

Turning to figure 2 the tower element 20 is placed centrally between the lifting towers 3, 3 ', 4, 4'. The engagement means and shells are not illustrated. Furthermore, a set of rails 14 is provided such that as the tower element 20 is being prepared for elevation, further tower elements 20' og 20" illustrated in phantom lines may be prepared outside the lifting circle, and as the tower element 20 is elevated, as will be explained with reference to figure 4, the next tower element 20' may by means of for example a trolley be placed in position for lifting inside the lifting circle between the four lifting towers 3, 3', 4, 4'.

In this connection it is important to notice that although the tower elements are illustrated as circular, it is clear that rectangular or square elements are also suitable to be lifted with the constellation of four lifting towers. In the situation where the elements are rectangular or square, the shells 12, 13 will be substantially planar such that they may engage the planar side surfaces of the rectangular or square elements. Turning to figure 3 the frictional engagement between the lifting tower/engagement means and a tower element are illustrated. The lifting tower and the lifting means as well as the tower elements 20 are only partly illustrated. In this embodiment which is only schematically illustrated in order to illustrate the principles of the frictional engagement, the engagement means 6, 7 comprises two wedge- shaped elements 15, 16. When the lifting means are activated the first wedge 15 will travel vertically along the lifting tower 5 by means of the sledges 10 and at a certain point the first wedge member will engage the second wedge 16 thereby exerting a hori- sontal force on to the tower element 20. In this situation the friction between the wedges 15, 16 the sledges 10 and the lifting tower will be such that by further hoisting the lifting means 8 the tower element will be elevated. As the plurality of lifting towers are arranged schematically about the circumference of the tower element, the elevation of the tower element 20 will occur due to the frictional engagement between the en- gagement means 6, 7.

In figure 4 a lifting cycle is illustrated with reference to the figures a) b) c) d) e) and f).

In figure 4 a tower element 20 is arranged between the lifting towers 3, 4 which tow- ers' are firmly connected to the tower foundation 2. After having arranged the engagement means (not illustrated) such that they are in frictional contact with the tower element, the tower element 20 is elevated into the position illustrated in figure 4b. While the tower element 20 is suspended above the lifting surface 19, the following tower element 20' is placed in position directly underneath the first tower element 20 as illustrated in figure 4c. The first tower element 20 is thereafter lowered such that it will rest on the top of the second tower element 20' whereafter the engagement means are released from the first tower element 20 and lowered such that the engagement means may engage the second tower element 20'. After the engagement means has frictional engaged the second tower element, the lifting process is resumed such that the two tower elements 20, 20' are elevated into the position indicated in figure 4e. In this position the third tower element 20" may be placed on the lifting surface directly underneath the first and second tower element 20, 20' whereafter the steps as explained above with reference to figures 4d and 4e are repeated as often as desired in order to create a tower structure having the desired height. The invention has now been explained with reference to a specific example, but it is clear that other engagement means are suitable to be employed with the inventive lifting equipment in order to carry out the inventive lifting method.

Claims

1. Lifting equipment, for elevating objects, where the lifting equipment engages the outside of the objects, where said lifting equipment comprises two or more lifting tow- ers, where each lifting tower is provided with engagement means for engaging the object to be lifted, and where said towers extend substantially vertically from a lifting surface to and above a predefined lifting height, where lifting means are provided for hoisting the engagement means upwards, and where each engagement means is provided with two relatively displaceable sliding means, where at least one of the means is provided with a surface facing the other means, where said surface is angled relative to the lifting direction.

2. Lifting equipment according to claim 1, characterised in that the lifting means comprises a wire connecting the engagement means to a winch, where a dead weight is connected to said winch, and that said wire passes at least one pulley, between the engagement means and the winch.

3. Lifting equipment according to claim 1, characterised in that the lifting means comprises a wire connecting the engagement means to a dead weight, and that said wire passes at least one pulley, between the engagement means and the dead weight, where at least one pulley is arranged at the distal end of a hydraulic piston, where said hydraulic piston moves vertically when activated.

4. Lifting equipment according to any of claims 1 to 3, characterised in that four lifting towers are arranged equidistant along a periphery of an imaginary circle, where a lifting surface is arranged inside said imaginary circle.

5. Lifting equipment according to any of claims 1 to 3, characterised in that two or more engagement shells are provided, which engagement shells are fixed to one or two engagement means, such that each engagement shell has a surface facing the object to be lifted, substantially corresponding to the contours of at least a section of the object to be lifted.

6. Lifting equipment according to any preceding claim, characterised in that the engagement means are provided with moveable sledges, where said sledges are arranged for movement along the face of the lifting towers facing the object to be lifted, where said sledges maintains a constant distance between the lifting tower and the object to be lifted.

7. Lifting equipment according to any preceding claim, characterised in that control means are provided on the lifting equipment where the lifting means are provided with sensors, strain gauges, pressure sensors or the like, and that the engagement means are provided with laser reflectors, where input is collected from the control means and used in order to control, monitor and conduct the lifting process.

8. Lifting equipment according to any preceeding claim, characterised in that two or more parallel rails are arranged, where said rails passes between the lifting towers and a distance on either side of the lifting equipment, and where a trolley is provided which trolley is adapted to travel on the rails carrying objects to be lifted.

9. Method of elevating objects by means of lifting equipment according to any of claims 1 to 8, characterised in that the method includes the following steps:

a) the first object to be elevated is placed equidistant and centrally between the lifting towers;

d) the continued activation of the lifting means elevates the object to a desired elevation;

g) the engagement means are released and lowered down into a position ready to engage the newly placed object; steps b) through g) are repeated for each object.

10. Method according to claim 9 wherein stabilizing lines are provided connecting the uppermost object and optionally further objects below to discrete foundations arranged radially around the lifting equipment.