Abstract
Extendable lattice type crane boom (2) for a crane (1), the boom comprising a lattice type base boom section (2a) and at least one lattice type telescopic boom section (2b), wherein the at least one telescopic boom section is adjustable with respect to the base boom section between a retracted position, in which the telescopic boom section is substantially inside of the base boom section, and an extended position, in which the telescopic boom section is at least partly outside of the base boom section, wherein a distal end of the base boom section to which a first guiding system (21) is mounted, the guiding system being configured to guide a movement of the telescopic boom section along the base boom section; wherein a proximal end of the telescopic boom section comprises a second guiding system (30) configured to guide a movement of the telescopic boom section along the base boom section.
Claims
1. An extendable lattice type crane boom for a crane, the boom comprising a lattice type base boom section and at least one lattice type telescopic boom section, wherein the at least one telescopic boom section is adjustable with respect to the base boom section between a retracted position, in which the telescopic boom section is substantially inside of the base boom section, and an extended position, in which the telescopic boom section is at least partly outside of the base boom section, wherein a distal end of the base boom section comprises a first guiding system, the guiding system being configured to guide a movement of the telescopic boom section along the base boom section; wherein a proximal end of the telescopic boom section comprises a second guiding system configured to guide a movement of the telescopic boom section along the base boom section; wherein the base boom section comprises a third guiding system configured to guide a movement of the telescopic boom section along the base boom section, said third guiding system being spaced-apart from the first guiding section at a distance corresponding to a length of the telescopic boom section part remaining inside of the base boom section in the extended position of the telescopic boom section.
2. The extendable lattice type crane boom according to claim 1, wherein the first, second and/or third guiding system comprises guide rails and guide elements, wherein the guide elements are configured to be guided along the guide rails, wherein the guide rails are provided on one of the base boom section and the telescopic boom section and the guide elements are provided on the other one of the base boom section and the telescopic boom section.
3. The extendable lattice type crane boom according to claim 1, wherein the base boom section comprises a first collar to which the first guiding system is mounted and/or wherein the base boom section comprises a second collar to which the third guiding system is mounted.
4. The extendable lattice type crane boom according to claim 1, wherein the second guiding system includes at least one rail mounted to at least one chord of the base boom section, wherein a length of said rail is substantially shorter than a length of the telescopic boom section part configured to extend from the base boom section in the extended position of the telescopic boom section.
5. The extendable lattice type crane boom according to claim 2, wherein the first guiding system and/or the third guiding system comprise guide elements on each of the chords of the base boom section, wherein the guide elements of the first guiding system and/or of the third guiding system are provided at the same axial distance along the base boom section.
6. The extendable lattice type crane boom according to claim 1, wherein the first guiding system is an x-y guide system.
7. The extendable lattice type crane boom according to claim 1, wherein the third guiding system is an x-y guide system.
8. The extendable lattice type crane boom according to claim 6, wherein the first guiding system includes at least one rail mounted to or integrated into at least one chord of the telescopic boom section, said rail being shaped to guide both an x-guide roller as well as a y-guide roller of an x-y guide system.
9-10. (canceled)
11. The extendable lattice type crane boom according to claim 1, wherein the second guiding system is a radial guiding system, provided on a chord of the base boom section and/or the telescopic boom section under an angle of substantially 45? with respect to an upper or a lower side of the boom.
12. The extendable lattice type crane boom according to claim 1, further comprising a locking system configured to lock the at least one telescopic boom section with respect to the boom section in at least the extended position.
13. The extendable lattice type crane boom according to claim 12, wherein the locking system includes a plurality of pins, each pin being configured to extend, in at least the extended position of the boom, at least partly through a corresponding pin receiving aperture provided in one of the first collar and the telescopic boom section, wherein a size of the pin receiving aperture is at least 10 mm larger than a cross-sectional dimension of the corresponding pin.
14. The extendable lattice type crane boom according to claim 13, wherein the locking system includes as many pins as the telescopic boom section has chords, each chord being configured to receive only one pin.
15. The extendable lattice type crane boom according to claim 1, further comprising a telescopic system arranged to adjust the at least one telescopic boom section between said retracted position and said extended position, wherein said telescopic system comprises at least one reeving system.
16. The extendable lattice type crane boom according to claim 15, wherein the telescopic system comprises two reeving systems, each provided on an opposite side of the base boom section.
17. A crane comprising: an extendable lattice type crane boom according to claim 1; wherein said lattice type crane boom is movable between a transit position, in which said lattice type crane boom is in a substantially retracted and substantially horizontal position, and a working position, in which a load is hoistable; a crane base to which said extendable lattice type crane boom is pivotably connected; a boom hoisting system arranged to move the extendable crane boom between said transit position and said working position; a load hoisting system configured to hoist a load.
18. The crane according to claim 17, wherein the boom hoisting system is connected to a distal end of the base boom section as well as to a distal end of the telescopic boom section.
19. The crane according to claim 17, wherein the crane base is mountable around a leg of a jack up platform.
20. A jack up platform including a crane according to claim 17.
21. A jack up platform according to claim 20, wherein the crane base is mounted around a leg of the jack up platform.
22. A method of operating a crane, including the extendable lattice type crane boom according to claim 1, the method comprising the steps of: bringing the extendable lattice type boom from a transit position to a working position; operating a telescopic system to adjust the at least one telescopic boom section with respect to the base boom section from a retracted position, in which the telescopic boom section is substantially inside of the base boom section, to an extended position, in which the telescopic boom section is substantially outside of the base boom section; wherein the operating of the telescopic system and the operation of bringing the extendable lattice type boom from a transit position to a working position is done at least partly simultaneously.
23. The method according to claim 22, wherein the operating of the telescopic system is started when the extendable lattice type boom has reached a boom angle of at least 30 degrees, with respect to a horizontal position.
24. The method according to claim 22, wherein a length of boom hoisting wires of the boom hoisting system is fixated when the extendable lattice type boom has reached a boom angle of at least 30 degrees, with respect to a horizontal position.
25. The method according to claim 22, further comprising the step of locking the telescopic boom section with respect to the base boom section in the extended position of the telescopic boom section by inserting substantially simultaneously a plurality of pins through corresponding pin receiving apertures provided in chords of one of the telescopic boom section and the base boom section.
26. The extendable lattice type crane boom according to claim 7, wherein the third guiding system includes at least one rail mounted to or integrated into at least one chord of the telescopic boom section, said rail being shaped to guide both an x-guide roller as well as a y-guide roller of an x-y guide system.
Description
[0035] The present invention will be further elucidated with reference to figures of exemplary embodiments. Corresponding elements are designated with corresponding reference signs.
[0036] FIG. 1 shows a side view on a first embodiment of a crane including an extendable crane boom according to the invention in different positions;
[0037] FIG. 2 shows a perspective view on a distal end of a base boom section of the extendable boom of the crane shown in FIG. 1;
[0038] FIG. 3 shows a perspective view on a proximal end of a telescopic section of the extendable boom of the crane shown in FIG. 1;
[0039] FIG. 4 shows a perspective detailed view on the third guiding system of the extendable boom of FIG. 1;
[0040] FIG. 5 shows a perspective view on a base boom section of the extendable boom of the crane shown in FIG. 1;
[0041] FIG. 6 shows a perspective view on a part of the extendable boom of FIG. 1 in a first intermediate position;
[0042] FIG. 7 shows a perspective view on a part of the extendable boom of FIG. 1 in a second intermediate position.
[0043] FIG. 1 shows a side view on a first embodiment of a crane 1 including an extendable crane boom 2 according to the invention in different positions. The crane 1 comprises a crane base 3 to which said extendable lattice type boom 2 is rotatably connected. The crane base 3 may be mounted around a leg 4 of a jack up platform, for example as a slewing platform, but may also be mounted differently, for example on a standard pedestal with slewing bearing, on a jack up platform or on any other structure where this type of crane is needed. The lattice type boom 2 is movable between a transit position T, in which said lattice type boom 2 is in a substantially retracted and substantially horizontal position, and a working position W, in which the telescopic boom section 2b is in an extended position E, via an intermediate position I. To perform said movement of the crane boom, the crane 1 also includes a boom hoisting system 5 arranged to move the extendable boom 2 between said transit position and said working position. Said boom hoisting system includes at least one, preferably two, boom hoist winches 11 mounted on the crane base. The boom hoisting system 5 may include two parallel wire rope and sheaves systems both connected to a distal end of the extendable boom, and/or to a distal end of the base boom section 2a. The crane 1 is further equipped with a load hoisting system 6 configured to hoist a load. Said load hoisting system 6 may include at least one main hoist winch 10, a head assembly 7 mounted on a distal end of the extendable crane boom 2, as well as an optional secondary hoisting system 8 including an auxiliary hoist winch, which may be configured to hoist smaller loads, to a greater height and more quickly than the main load hoisting system. The main hoisting system may for example be configured to hoist loads of up to approximately 2500 tons to a height of approximately 115 m above ground/deck, or a load of up to approximately 1250 tons to a height of approximately 156 m above ground/deck. Such a configuration allows installation of off-shore wind turbines of up to approximately 16 MW. It is understood that this is just an example, and that smaller or larger configurations are possible. The extendable boom 2 comprises a lattice type base boom section 2a and at least one lattice type telescopic boom section 2b. The lattice type base boom section 2a, as well as the lattice type telescopic boom section 2b, each include longitudinal chords 15, in particular four chords 15, at each corner of the boom section 2a, 2b, which are interconnected with trusses 16. A diameter of the chords 15a of the base boom section 2a is typically larger than a diameter of the chords 15b of the telescopic boom section 2b. The telescopic boom section 2b is adjustable with respect to the base boom section 2a between a retracted position R, in which the telescopic boom section 2b is substantially inside of the base boom section 2a, and an extended position E, in which the telescopic boom section 2b is at least partly outside of the base boom section 2a. In the above-mentioned example of a hoisting system configured for hoisting loads up to 2500 tons, the total boom length may for example be around 95 m in a retracted position, whereas the total boom length in a most extended position may for example be as long as approximately 135 m, or longer or shorter. The boom hoisting system 5 is connected to a distal end of the base boom section 2a as well as to a distal end of the telescopic boom section 2b, more in particular, to the head assembly 7 on the telescopic boom section 2b and to a support structure 9 on a distal end of the base boom section 2a. In a working position W, as shown, when the process of extension of the telescopic boom section 2b has been completed, the crane boom 2 makes an angle ? with a substantially horizontal transit position of the crane boom 2 in a range of approximately 75?-85?, preferably an angle of approximately 80?. Said position can be considered as a starting position for hoisting loads, for which boom angles can be adjusted again to lower boom angles if needed. The transit and working positions also allow to define an upper side 17 and a lower side 18 of the extendable boom 2, the lower side 18 being the side of the extendable boom 2 turned downwards in a transit position, and the upper side 17 of the extendable boom 2 being the opposite side of the lower side 18. The boom hoisting system 5 is at least partly mounted on the upper side 17 of the extendable boom 2, whereas loads are hoisted along the lower side 18 of the extendable boom 2. The extendable crane boom 2 also comprises a telescopic system 12 arranged to adjust the at least one telescopic boom section 2b between said retracted position and said extended position. Said telescopic system 12 comprises at least one reeving system, preferably two reeving systems, each provided on an opposite side of the base boom section 2a, preferably on lateral sides of the base boom section 2a (see FIG. 4). The telescopic system 12 can be configured to extend the extendable boom 2 from a retracted position (R) to an extended position (E) relatively swiftly. The telescopic system 12 also includes at least one telescopic winch 13. The reeving system may be configured such that pulling a wire rope 14 in with the winch 13 can for example result in the telescopic boom section 2b being pulled out of the base boom section 2a at least partly, thus extending the boom, while moving along a guiding system. During retraction of a telescopic boom section 2b, the winch 13 can be operated to release a wire rope allowing the telescopic boom section to move inside of the base boom section. In order to speed up operations, which may be important in an harsh off-shore environment, it is desirable to start extending the telescopic boom section 2b during upending of the extendable boom 2, i.e. during the movement of the extendable boom 2 from a transit position T to a working position W, or start retracting the telescopic boom section 2b into the base boom section 2a while the boom 2 is being moved from a working position W to a transit position T. With prior art extendable boom cranes, such a combined movement of extending of the telescopic boom section and upending of the boom could cause distortions and sagging, especially at lower boom angles. With the present invention, it has become possible to start extending the telescopic boom section even at relatively low boom angles thanks to the innovative combination of three guiding systems, as will be explained further below.
[0044] FIG. 2 shows a perspective view on a distal end of a base boom section 2a of the extendable boom 2 of the crane 1 shown in FIG. 1. A distal end of the base boom section 2a comprises a first collar 20 to which a first guiding system 21 is mounted. The first collar 20 includes a cross-sectional reinforcement structure of the lattice-type boom section, such that the collar can take loads of the additional structures mounted to the collar, such as the first guiding system. The first guiding system 21 is configured to guide a movement of the telescopic boom section 2b along the base boom section 2a. Thereto, the first guiding system can comprise a set of guide elements 22 on the base boom section 2a and corresponding guide rails on the telescopic boom section 2b, or vice versa, (see FIG. 4). The guide elements 22 or guides 22, which can for example be embodied as rollers, are configured to perform a guiding movement, for example a rolling movement or a sliding movement, on or along corresponding guide rails on the telescopic boom section. The first guiding system 21 can for example include a set of guides 22 per chord. The corresponding rails of the first guiding system can be mounted on, or integrated into, each of the longitudinal chords of the telescopic boom section. The first guiding system can advantageously be an x-y guide system, in which each set of guides comprises at least two guides, for example rollers, which are configured to guide a movement of the telescopic boom section along two substantially transverse directions. In an innovative way, the base boom section 2a comprises a third guiding system 24 configured to guide a movement of the telescopic boom section 2b along the base boom section 2a. The third guiding system also includes a set of guide elements or guides 25 on the base boom section 2a and corresponding guide rails on the telescopic boom section 2b, or vice versa. Said third guiding system 24, in particular the set of guides 25 of the third guiding system, is spaced-apart from the first guiding system 21 at a distance corresponding to a length of the telescopic boom section part remaining inside of the base boom section 2a in the extended position of the telescopic boom section 2b. The base boom section 2a preferably comprises a second collar 26 to which the third guiding system 24, in particular the set of guides 25 of the third guiding system 24, is mounted. The second collar 26 can include one or more cross-sectional trusses, preferably as many cross-sectional trusses as a number of chords of the base boom section, for example four. Also the third guiding system 24 preferably is an x-y guide system. The first guiding system and the third guiding system are preferably of the same type. As such, both the first guiding system 21 as the third guiding system 24, in particular the guide elements of the respective first guiding system 21 and of the third guiding system 24 on the base boom section 2a, can share the same guide rails provided on the telescopic boom section 2b, as will be shown further on. The extendable crane boom can further comprise a locking system 27 configured to lock the at least one telescopic boom section 2b with respect to the base boom section 2a in at least the extended position. Thereto, the locking system 27 can include a plurality of pins, each pin being configured to extend, in at least the extended position of the boom, at least partly through a corresponding pin receiving aperture 28 provided in one of the first collar 20 and the telescopic boom section 2b. In case the plurality of pins extend from the first collar, then a size of the pin receiving aperture 28 in the telescopic boom section 2b may advantageously be at least 10 mm larger than a cross-sectional dimension of the corresponding pin, so that locking and unlocking of the pins can be done relatively easily without frictional forces hindering the pin movement in and/or out of the pin receiving aperture 28. Alternatively, the plurality of pins could also extend from the telescopic boom section, while the pin receiving apertures are present in the first collar. Also in that case, a size of these pin receiving apertures may be at least 10 mm larger than a cross-sectional dimension of the corresponding pin. The locking system can preferably include as many pins as the telescopic boom section has chords, each chord being configured to receive only one pin. As will be shown further, the telescopic boom section 2b of the present embodiment has four chords 29, so the first collar 28 includes four pin receiving apertures 28, which are each configured to receive a pin, which is configured to lock a position of the telescopic boom section 2b with respect to the base boom section 2a.
[0045] FIG. 3 shows a perspective view on a proximal end of a telescopic section 2b of the extendable boom 2 of the crane 1 shown in FIG. 1. A proximal end of the telescopic boom section comprises a second guiding system 30 configured to guide a movement of the telescopic boom section 2b along the base boom section 2a. The second guide system also includes a set of guides and corresponding rails, wherein the guides are provided on the telescopic boom section 2b and the rails are provided base boom section 2a or vice versa. Contrary to the first and the third guiding system, the second guiding system can be a radial guiding system. In the present embodiment, a set of guides 31, in particular rollers, are provided on a chord 32, in particular on the lower chords 32a of the telescopic boom section 2b under an angle of substantially 45? with respect to an upper or a lower side of the boom. Guides may also, but need not, be provided on the upper chords of the telescopic boom section. A guide rail of the second guiding system 30 may be provided on part of a length of the chords of the base boom section 2a, which preferably has a substantially circular cross-section. The guide rails are mounted correspondingly under an angle of substantially 45? with respect to an upper or a lower side of the boom. Alternatively, guides and guide rails may be switched.
[0046] FIG. 4 shows a perspective detailed view on the third guiding system of the extendable boom of FIG. 1. Contrary to the base boom section, the telescopic boom section 2b preferably has chords having a substantially rectangular cross-section. A guide rail 33 of the first guiding system 21 and/or the third guiding system 24 can be mounted on, or can be integrated into, a chord 32 of the of the telescopic boom section 2b. Said rail 33 may be shaped such as to guide both an x-guide roller as well as an y-guide roller of a x-y guide system. In particular, said guide rail 33 may include two adjacent guiding sides which are substantially transverse to each other. Such a guide rail 33 may then be placed at an outer edge of a chord of the telescopic boom section 2b having a substantially rectangular cross-section. It is preferred that a guide rail 33 on a chord of the telescopic boom section 2b can engage both a corresponding guide of the first guiding system 21 and of the third guiding system 24.
[0047] FIG. 5 shows a perspective view on a base boom section 2a of the extendable boom 2 of the crane 1 shown in FIG. 1. As in the previous figures, the lattice-type trusses between the longitudinal chords 29 have not been shown for clarity's sake. Also the second collar 26 may include two additional cross-sectional trusses or strengthening structures. As shown before, the base boom section 2a includes chords 29 having a substantially circular cross-section. The second guiding system 30 also includes at least one rail 34, preferably at least two rails 34, mounted to at least one chord 29 of the base boom section 2a, preferably to the lower chords 29a of the base boom section 2a. The guide rails 34 are preferably mounted under an angle of substantially 45? with respect to an upper or a lower side of the boom, such that they can engage the guides 31 of a radial guiding system. A length of said guide rail 34 can be substantially shorter than a length of the telescopic boom section part configured to extend from the base boom section 2a in the extended position E of the telescopic boom section 2b. The guide rail 34 can extend from a proximal end 35 of the base boom section 2a along the chords 29 of the base boom section 2a, for example over less than half of a length of the base boom section 2a.
[0048] FIG. 6 shows a perspective view on a part of the extendable boom of FIG. 1 in a first intermediate position. When moving the extendable boom from a retracted position R (shown in FIG. 1) in which the telescopic boom section 2b is substantially inside of the base boom section 2a, to an extended position E, in which the telescopic boom section is at least partly outside of the base boom section, the telescopic boom section 2b is first guided by the first guiding system 21 and by the second guiding system 30, as is shown in the intermediate position of FIG. 6. The guides 25 of the third guiding system 24 may engage the guide rail 33, but the third guiding system 24 hardly takes any load. In this phase of extending of the telescopic boom, the crane boom is statically undetermined.
[0049] FIG. 7 shows a perspective view on a part of the extendable boom of FIG. 1 in a second intermediate position. When the telescopic boom section 2b is extended further after the first intermediate position shown in FIG. 6, the guides 31 of the second guiding system 30 will at a certain point go beyond a length of the corresponding guide rail 34 of the second guiding system 30 so that the second guiding system stops guiding. The movement of the telescopic boom section 2b is then guided by the first guiding system 21 and the third guiding system 24. The second guiding system 30 takes no load at all anymore. The telescopic boom section 2b has reached its extended position E when the guides 31 of the second guiding system 30 have substantially reached the third guiding system 24 and/or the second collar 26. Extending the telescopic boom section 2b out of the base boom section 2a can be done when the extendable crane boom 2 is in a substantially upright position, in particular when the extendable crane boom 2 has a boom angle ? of substantially 80 degrees with respect of a horizontal plane. However, the present invention also allows earlier extending of the telescopic crane boom, in particular starting extending from a boom angle ? of substantially 30 degrees, or more preferably from a boom angle ? of substantially 50 degrees. More in particular, thanks to the present invention, part of the upending of the crane boom from a transit position T to a working position W can be done by fixating a length of boom hoisting wires of the boom hoisting system 5, the length of boom hoisting wires being measured from the boom hoisting winches 11 to the crane boom. A boom hoisting system 5 can for example be activated to hoist a crane boom from a transit position T to a first intermediate position at a boom angle ? in a range of more or less 30 to more or less 55 degrees with respect to a horizontal plane. Then the boom hoisting system 5 can be configured to keep hoisting wires at a constant length, for example by putting a brake on the boom hoist winches 11. Then the locking pins of the locking system 27 can be taken out of the pin receiving apertures 28, which locking system 27 had kept the telescopic boom 2 in a retracted position R. Next, the telescopic system 12 can be activated and extending of the telescopic boom can start. The start of the extending of the telescopic boom, in combination with the boom hoisting system being configured to keep hoisting wire ropes at a constant length, will make the upending of the crane boom continue towards the working position of the crane boom. So by at least partly performing extending of the telescopic boom during upending of the crane boom, or even better, by at least partly performing upending of the crane boom through extending the telescopic boom, time can be saved in making the crane ready for hoisting operations, while keeping these upending and extending operations relatively stable and thus safe thanks to the improved extendable crane boom.
[0050] For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. It may be understood that the embodiments shown have the same or similar components, apart from where they are described as being different.
[0051] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word comprising does not exclude the presence of other features or steps than those listed in a claim. Furthermore, the words a and an shall not be construed as limited to only one, but instead are used to mean at least one, and do not exclude a plurality. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to an advantage. Many variants will be apparent to the person skilled in the art. All variants are understood to be comprised within the scope of the invention defined in the following claims.
