Method of upgrading a knuckle-boom crane and a heave-compensating crane

Abstract

A method of upgrading a knuckle-boom crane to a heave-compensating crane includes: removing a knuckle-boom from a main boom; mounting a main boom extension to the main boom for increasing the length of the main boom; and mounting a heave-compensating boom at a far end of the main boom extension such that the heave-compensating boom extends in a downward vertical direction (Z) in operational use of the heave-compensating crane. The heave-compensating boom is configured to be pivotable with respect to the main boom extension in both horizontal directions (X, Y). A heave-compensation system is provided to the knuckle-boom crane, wherein the heave-compensation system compensates for horizontal variations by controlling the orientation of the heave-compensating boom relative to the main boom extension, and compensates for vertical variations by means of a further vertical heave-compensation system, such as a winch-based heave-compensation system.

Claims

1. Method of upgrading a knuckle-boom crane to a heave-compensating crane, the method comprising: providing a knuckle-boom crane having a crane base, a main boom pivotably mounted to the crane base, and a knuckle-boom pivotably mounted to the main boom; removing the knuckle-boom from the main boom; mounting a main boom extension to the main boom for increasing the length of the main boom; mounting a heave-compensating boom at a far end of the main boom extension such that the heave-compensating boom extends in a downward vertical direction (Z) in operational use of the heave-compensating crane, wherein the heave-compensating boom is configured to be pivotable with respect to the main boom extension in both horizontal directions (X, Y) defined with respect to the downward vertical direction (Z), and providing a heave-compensation system to the knuckle-boom crane comprising a plurality of actuators and the heave-compensating boom which is pivotable by at least one of the plurality of actuators, wherein the heave-compensation system is configured for compensating for horizontal variations by controlling the orientation of the heave-compensating boom relative to the main boom extension, and for compensating the vertical variations by means of a further vertical heave-compensation system which comprises a winch system configured for manipulating a hoisting cable to compensate the vertical variations.

2. The method according to claim 1, wherein, in mounting the main boom extension, the main boom extension comprises a top-sheave at a far end of the main boom extension.

3. The method according to claim 2, wherein, in mounting the heave-compensating boom, the heave-compensating boom comprises a hoisting cable guiding system for cooperating with the top-sheave.

4. The method according to claim 3, wherein the heave-compensating boom comprises a first end coupled to the main boom extension and a second end spaced apart from the first end, and wherein, in mounting the heave-compensating boom, the hoisting cable guiding system comprises a pair of sheaves mounted on a rotatable head provided at the second end of the heave-compensating boom.

5. The method according to claim 1, wherein, in mounting the heave-compensating boom, the heave-compensating boom comprises a first arm that is pivotably mounted to the main boom extension for allowing a rotation in a first horizontal direction (X), the heave-compensating boom further comprising a second arm that is pivotably mounted to the first arm for allowing a rotation in a second horizontal direction (Y) orthogonal to the first horizontal direction (X).

6. The method according to claim 5, wherein, in mounting the heave-compensating boom, the first arm is mounted such that the first arm extends in a substantially horizontal direction (X) in operational use of the heave-compensating crane, and the second arm is mounted such that the second arm extends in the downward vertical direction (Z) in operational use of the heave-compensating crane.

7. The method according to claim 5, wherein, in mounting the heave-compensating boom, said first and second arms are provided with electric or hydraulic actuators to control respective orientations of said arms.

8. The method according to claim 1, further comprising completion steps of completing the heave-compensating crane for making the heave-compensating crane ready for operational use, wherein the completion steps comprise the installation of the hoisting cable along the main boom, the main boom extension and the heave-compensating boom.

9. A heave-compensating crane comprising: a crane base; a main boom having a near end pivotably mounted to the crane base and a far end spaced apart from the near end, the main boom extending in a single linear direction along the entire length of the main boom; a heave-compensating boom pivotably mounted at a far end of the main boom and having a first end pivotably coupled to the far end of the main boom and a second end coupled to a rotatable head, the length between the far end of the main boom and the second end of the heave-compensating boom being fixed, wherein the heave-compensating boom extends in a downward vertical direction (Z) in operational use of the heave-compensating crane, wherein the heave-compensating boom is configured to be pivotable with respect to the main boom in both horizontal directions (X, Y) defined with respect to the downward vertical direction (Z), a first heave-compensation system comprising a plurality of actuators, the rotatable head, and the heave-compensating boom which is pivotable by at least one of the plurality of actuators, and wherein the first heave-compensation system is configured for compensating for horizontal deviations by controlling the orientation of the heave-compensating boom relative to the main boom, and a second heave-compensation system comprising a winch system configured for manipulating a hoisting cable to compensate vertical deviations.

10. The heave-compensating crane according to claim 9, wherein the main boom comprises a top-sheave at the far end of the main boom.

11. The heave-compensating crane according to claim 10, wherein the heave-compensating boom comprises a hoisting cable guiding system for cooperating with the top-sheave.

12. The heave-compensating crane according to claim 11, wherein the hoisting cable guiding system comprises a pair of sheaves mounted on the rotatable head provided at the second end of the heave-compensating boom.

13. The heave-compensating crane according to claim 9, wherein the heave-compensating boom comprises a first arm that is pivotably mounted to the main boom for allowing a rotation in a first horizontal direction (X), the heave-compensating boom further comprising a second arm that is pivotably mounted to the first arm for allowing a rotation in a second horizontal direction (Y) orthogonal to the first horizontal direction (X).

14. The heave-compensating crane according to claim 13, wherein the first arm is mounted such that the first arm extends in a substantially horizontal direction (X) in operational use of the heave-compensating crane, and the second arm is mounted such that the second arm extends in the downward vertical direction (Z) in operational use of the heave-compensating crane.

15. The heave-compensating crane according to claim 13, wherein said first and second arms are provided with electric or hydraulic actuators to control respective orientations of said arms.

16. The heave-compensating crane according to claim 9 wherein the main boom comprises a first boom section joined to a second boom section at a joint, wherein the first boom section comprises the near end of the main boom and the second boom section comprises the far end of the main boom, and wherein the joint is configured to maintain the first and second boom sections extending in the single linear direction.

17. The heave-compensating crane according to claim 16, wherein the heave-compensating boom comprises a first arm that is pivotably mounted to the main boom for allowing a rotation in a first horizontal direction (X), the heave-compensating boom further comprising a second arm that is pivotably mounted to the first arm for allowing a rotation in a second horizontal direction (Y) orthogonal to the first horizontal direction (X).

18. The heave-compensating crane according to claim 17, wherein the first arm is mounted such that the first arm extends in a substantially horizontal direction (X) in operational use of the heave-compensating crane, and the second arm is mounted such that the second arm extends in the downward vertical direction (Z) in operational use of the heave-compensating crane.

19. The heave-compensating crane according to claim 17, wherein said first and second arms are provided with electric or hydraulic actuators to control respective orientations of said arms.

20. The heave-compensating crane according to claim 9 wherein the main boom comprises a plurality of boom sections joined together, and wherein the main boom is free of a knuckle-boom.

21. The heave-compensating crane according to claim 9 wherein the crane base comprises the second heave-compensation system.

22. The heave-compensating crane according to claim 9, wherein the main boom comprises a first boom section joined to a second boom section by an elongate mounting bar connected between the first boom section and the second boom section such that the first boom section is prevented from pivoting relative to the second boom section.

23. The heave-compensating crane according to claim 9, wherein the length between the first end of the heave-compensating boom and the rotatable head is fixed.

24. A heave-compensating crane comprising: a crane base; a main boom having a near end pivotably mounted to the crane base and a far end spaced apart from the near end, the main boom extending in a single linear direction along the entire length of the main boom; and a first heave-compensation system comprising a plurality of actuators and a first heave-compensating boom pivotably mounted at a far end of the main boom and having a first end pivotably coupled to the far end of the main boom and a second end coupled to a rotatable head, the length between the far end of the main boom and the second end of the heave-compensating boom being fixed, wherein the first heave-compensating boom is pivotable by at least one of the plurality of actuators and extends in a downward vertical direction (Z) in operational use of the heave-compensating crane, wherein the first heave-compensating boom is configured to be pivotable with respect to the main boom in both horizontal directions (X, Y) defined with respect to the downward vertical direction (Z); wherein the first heave-compensating boom comprises a first arm that is pivotably mounted to the main boom for allowing a rotation in a first horizontal direction (X), the first heave-compensating boom further comprising a second arm that is pivotably mounted to the first arm for allowing a rotation in a second horizontal direction (Y) orthogonal to the first horizontal direction (X); wherein the crane base comprises a second heave-compensation system comprising a winch system configured for manipulating a hoisting cable to compensate vertical deviations.

25. The heave-compensating crane according to claim 24 wherein the first arm is mounted such that the first arm extends in a substantially horizontal direction (X) in operational use of the heave-compensating crane, and the second arm is mounted such that the second arm extends in the downward vertical direction (Z) in operational use of the heave-compensating crane.

26. The heave-compensating crane according to claim 24, wherein the main boom comprises a first boom section joined to a second boom section by an elongate mounting bar connected between the first boom section and the second boom section such that the first boom section is prevented from pivoting relative to the second boom section.

27. The heave-compensating crane according to claim 24, wherein the length between the first end of the heave-compensating boom and the rotatable head is fixed.

Description

BRIEF INTRODUCTION OF THE DRAWINGS

(1) In the following is described examples of embodiments illustrated in the accompanying drawings, wherein:

(2) FIG. 1 shows a knuckle-boom crane that has been upgraded to a heave-compensating crane;

(3) FIGS. 2-12 show different stages of a method of upgrading a knuckle-boom crane to a heave-compensating crane in accordance with the disclosure;

(4) FIG. 13 illustrates a first aspect of the operation of the heave-compensated crane;

(5) FIG. 14 illustrates a further aspect of the operation of the heave-compensated crane;

(6) FIG. 15a shows an enlarged front view of the far-end of the main boom extension of the crane;

(7) FIG. 15b shows a cross-sectional view of FIG. 15b;

(8) FIG. 16a shows an enlarged side view of the far-end of the main boom extension of the crane;

(9) FIG. 16b shows a further cross-sectional view of FIG. 16a, and

(10) FIG. 17 shows an enlarged view of the tip of the heave-compensating boom of the crane.

DETAILED DESCRIPTION OF THE DISCLOSED EXEMPLARY EMBODIMENTS

(11) Various illustrative embodiments of the present subject matter are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers'specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

(12) The present subject matter will now be described with reference to the attached figures. Various systems, structures and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the present disclosure with details that are well known to those skilled in the art. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the present disclosure. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.

(13) FIG. 1 shows a knuckle-boom crane that has been upgraded to a heave-compensating crane 100. The heave-compensating crane 100 in this embodiment is the result of an up-grade of an existing knuckle-boom crane, which will be explained with reference to FIGS. 2-12. The heave-compensating crane 100 comprises a crane base 110 that is rotatable mounted on a crane pedestal 105. The crane pedestal 105 is typically mounted in the deck of a ship (not shown). The crane base 110 comprises a main winch system 112, which comprises heave-compensated winch system 114, such as an active heave-compensation (AHC) winch system, in order to take care of variations in the Z-direction. Heave-compensated winch system 114 may also be referred to herein as a further or second heave-compensation system 114 comprising the winch system 112. On the crane base 110 there is pivotably mounted a main boom 120 that is actuated via main boom actuators 115 as shown. All construction and operation aspects of a crane are considered to be well known to the person skilled in the art and will therefore not be discussed in more detail here. The main boom 120 of the crane comprises an original main boom 121 of a knuckle-boom crane and a main boom extension 122. At the end of the main-boom extension 122 there is mounted a heave-compensating boom 140, which forms an important part of the embodiment shown. This heave-compensating boom 140 provides for an additional heave-compensation system, next to the AHC system, and is configured for compensating for variations in the X-direction and Y direction.

(14) FIGS. 2-12 show different stages of the method of upgrading a knuckle-boom crane to a heave-compensating crane in accordance with the disclosure. In the discussion of these figures only the differences with respect to the previous figure are discussed.

(15) FIG. 2 shows a first stage of the method, wherein a knuckle-boom crane 100a is provided. The knuckle-boom crane 100a comprising a main boom 121 and knuckle-boom 130 (also called jib) that has been folded in. The figure also shows the main boom actuators 115 and the knuckle-boom actuator 125.

(16) FIG. 3 shows a further stage of the method, wherein the knuckle-boom 130 (and all parts connected to it) has been removed.

(17) FIG. 4 shows another stage of the method, wherein the main boom 121 is extended with a main boom extension 122. In this embodiment the main boom extension 122 is mounted to the pivoting point or axle of the original main boom 121, wherein a mounting bar or joint 122mb is provided at the position where originally the actuator 125 was located. However, it must be stressed that other constructions and solutions are also possible to lengthen the main boom 120 as illustrated. The main boom extension 122 also comprises a far end 122e that is prepared to receive a heave-compensating boom later in the process.

(18) FIG. 5 shows another stage of the method, wherein a top-sheave 128 is rotatably mounted in the far end 122e of the main boom extension 122.

(19) FIG. 6 shows another stage of the method, wherein first arm actuators 129 are mounted on the far end 122e of the main boom extension 122. Said actuators 129 serve to actuate the first arm of heave-compensating boom to be mounted, and are therefore referred to as first-arm actuators 129. These first-arm actuators 129 are also referred to as “rotating lever actuators”. The operation and function of these actuators is considered to be well-known as such and therefore not illustrated or discussed in further detail.

(20) FIG. 7 shows another stage of the method, wherein the first arm 142 of the heave-compensating boom is pivotably mounted at the far end 122e of the main boom extension 122. The first arm 142 is also referred to as “rotating lever”

(21) FIG. 8 shows another stage of the method, wherein a second arm 144 of the heave-compensating boom is pivotably mounted to the first arm 142. The second arm 144 is also referred to as “pivot boom”.

(22) FIG. 9 shows another stage of the method, wherein second arm actuators 145 are mounted on the first arm 142. Both the first arm actuators 129 as well as the second arm actuators 145 may be electric or hydraulic actuators. The second arm actuators 145 are also referred to as “pivot boom actuators”. The operation and function of these actuators is considered to be well-known as such and therefore not illustrated or discussed in further detail.

(23) FIG. 10 shows another stage of the method, wherein a rotatable head 146 is mounted at a far end 140e of the second arm 144 of the heave-compensating boom 140 as illustrated. The rotatable head 146 is configured for receiving a pair of in-line oriented sheaves (not shown) for guiding a hoisting cable 131, shown in FIG. 1 disposed along top sheave 128.

(24) FIG. 11 shows another stage of the method, wherein the pair of sheave 148 is mounted in the rotatable head 146. This step effectively completes the heave-compensating boom 140.

(25) FIG. 12 shows another stage of the method, where the heave-compensating crane 100 is almost completed. The only thing missing in the figure is the hoisting cable. The figure further serves to define the different directions (for heave-compensation), planes and orientation to which reference is made throughout the claims and the description. The first horizontal direction is defined in the direction of the arrow indicated with X. This is referred to as X-direction, but in other places also reference is made to the X-plane, which is then defined as the plane defined by the X and Z arrows. The second horizontal direction is defined orthogonal to the X-direction and indicated by the arrow indicated with Y. This is referred to as Y-direction, but in other places also reference is made to the Y-plane, which is then defined as the plane defined by the Y and Z arrows. The third direction is the vertical direction and defined in the direction of the arrow indicated with Z. This is referred to as Z-direction.

(26) FIG. 13 illustrates a first aspect of the operation of the heave-compensated crane. This figure serves to illustrate the movement of the main boom 120 and how the heave-compensating boom 140 is constantly directed in a downward direction during this movement. However, the heave-compensating boom 140 can be actuated in the directions of the arrows within the X-plane to compensate for position variations in the X-direction due to heaves. During these movements of the heave-compensating boom 140 the hoisting cable (not shown) is properly guide by the sheaves 128, 148. The maximum angle over which the heave-compensating boom needs to be pivoted is typically 20 degrees with respect to the vertical direction Z.

(27) FIG. 14 illustrates a further aspect of the operation of the heave-compensated crane. In this case the heave-compensating boom 140 is actuated in the directions of the arrows within the Y-plane to compensate for position variations in the Y-direction due to heaves. An important aspect of this embodiment is that the rotating head 146 with the pair of sheaves 148 is now rotated with respect to the heave-compensating boom 140 to facilitate proper guiding of the hoisting cable (not shown) during these movements.

(28) FIG. 15a shows an enlarged front view of the far-end of the main boom extension of the crane. FIG. 15b shows a cross-sectional view of FIG. 15b. These figures show some more details, which have been discussed but are harder to extract from the other drawings. As mentioned the heave-compensation boom 140 is the compensator part that will handle the sideways movement in relation to the crane boom orientation. The movement is held by an electrical or hydraulic system and it is done at the pivotable connection between the first arm 142 and the second arm 144. In this embodiment this interface is a slew bearing, gear ring or equivalent, which will facilitate the movement and handle the torques involved. The sideways movement may go up to 20°, both ways, depending on the loads applied. The rotatable/pivotable first arm 142 and the pivotable arm 144 together facilitate that the movement shape possibilities stay within a cone, because the base of the movement at the end of the heave-compensating boom 140 will be more or less a circle.

(29) FIG. 16a shows an enlarged side view of the far-end of the main boom extension of the crane. FIG. 16b shows a further cross-sectional view of FIG. 16a. The first arm 142 will connect the crane boom 120, or main boom extension 122, in on end and connect the second arm 144 on the other end. The movement of the first arm will give a motion—forwards and backwards—in the same direction as the crane main boom orientation. Movement is driven electrically, or hydraulically, with the gearboxes carrying the movement while interacting with a gear ring, or equivalent, which may be installed on the side of the main sheave. This part of the system comprises a bigger sheave 128 with conical side shape to hold the side forces that occur due to 3D compensation. The first arm 142 will move in order to compensate the main boom 120, or main boom extension 122, up and down movements, by its own rotation.

(30) FIG. 17 shows an enlarged view of the tip of the heave-compensating boom 140 of the crane, in particular the rotatable head 146. The rotatable head 146 intends to secure the hoisting cable (rope) position and gives its final support while the orientation is being given by the other two parts. The sheaves 148 have a smaller D:d than the main sheave 128, at the first arm 142, to support since there is no actual bending over these. The movement done by electrical, or hydraulic, actuators with the movement being carried by a slew bearing system, or equivalent. Both sheaves 148 have installed load cells (not shown), for overload safety, in order to get the amount of force felt by the head of the compensator. This rotation will ensure ±90° in relation to its stand by position (both sheaves 148 aligned with the main boom). The figure further illustrates actuators 147 inside the second arm 144 for rotating the rotatable head 146.

(31) It has already been mentioned that this disclosure also relates to a heave-compensating crane no matter the method by which it is made. It is very well possible to build up such crane from the start. In that case the main boom extension may be dispensed with and a longer main boom may be manufactured and used.

(32) Furthermore, there are many variations possible with respect to the example embodiments here discussed. For example, the heave-compensating crane of the disclosure can be made much bigger, with lifting capacities up to 2500 T, for instance when using parallel wire and parallel 3D compensator arms, with two or multipart blocks. Furthermore, the crane may be installed on a so-called A-FRAME.

(33) All the movements may also, when possible, be carried with the help of a triangular centre positioning system. That will help the precision by getting the correct/updated coordinates in real time while lowering or lifting.

(34) The particular embodiments disclosed above are illustrative only, as the disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the method steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. Accordingly, the protection sought herein is as set forth in the claims below.

(35) It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware.