Support structure for a crane, a crane comprising the support structure, and a ship comprising such a crane

Abstract

A support structure for a crane, the support structure having a lower end portion with a circular shape for connection to a slewing bearing, an upper end portion with a polygonal shape for supporting a boom of the crane and / or a support frame of the crane, and an outer portion connecting an outer edge portion of the upper end portion to an outer edge portion of the lower end portion, wherein the upper end portion is provided with a pair of boom hinge connection portions for hinge - type connection of the boom of the crane and at least a support frame connection portion for supporting the support frame of the crane, and the outer portion at least partially includes a plate portion forming a wall section for transitioning from the polygonal shape of the upper end portion to the circular shape of the lower end portion, the plate portion including a flat plate portion and a curved plate portion, the support structure.

Description

Technical Field

[0001] The present invention relates to a support structure for a crane, particularly for an offshore crane.

[0002] Offshore cranes are widely known and are typically mounted on floating structures such as ships, pontoons, or jack-ups. Offshore cranes can be used for various purposes, for example, for lifting heavy objects at offshore locations such as installing and dismantling heavy structures such as wind turbines, the foundations of wind turbines, platforms, and the top sides of platforms.

[0003] An offshore crane typically includes a boom pivotally mounted on a support structure. At the boom tip, a load can be lifted. The support structure is rotatably mounted on a foundation structure. The foundation structure is connected to a floating structure. A bearing is provided between the foundation structure and the support structure to enable a rotational movement, also referred to as a slewing movement of the support structure relative to the foundation structure. The bearing is often referred to as a slewing bearing that adapts to the slewing movement of the support structure relative to the foundation structure. The support structure, also known as a slewing platform, supports at least the crane boom. The support structure may further support an A-frame or other support frames on which a lifting and / or luffing system can be provided. In a so-called pedestal crane, the foundation structure may be referred to as a pedestal and is fixedly mounted on the floating structure.

[0004] The load of the crane is transmitted to the floating structure via the support structure, the slewing bearing, and the foundation structure. Offshore cranes are becoming larger and heavier, similar to the loads lifted and handled by these offshore cranes. To guide these loads towards the floating structure via the support structure, the bearing, and the foundation structure, these structures are becoming larger and thus heavier. This has an adverse effect on, for example, the weight of the ship or the loading capacity of the ship. A slewing bearing with a diameter of 15 meters or more, or a maximum of 30 meters, is assumed. Also, cranes with a lifting capacity of about 1000 metric tons (10 6 kg) to 10000 metric tons (10 7 kg) are known.

[0005] There is a need to transmit these loads to the foundation structure and the floating structure in an efficient manner to accommodate such large cranes and the lifting loads of such heavy objects.

[0006] An object of the present invention is to provide a support structure that transmits the load of the crane more efficiently, preferably effectively, by the foundation structure.

[0007] In contrast, the present invention provides a support structure for a crane, the support structure having a lower end portion having a circular shape for connection to a slewing bearing, an upper end portion having a polygonal shape for supporting a boom of the crane and / or a support frame of the crane, and an outer portion connecting an outer edge portion of the upper end portion to an outer edge portion of the lower end portion, the upper end portion being provided with a pair of boom hinge connection portions for hinge-connecting the boom of the crane and at least a support frame connection portion for supporting the support frame of the crane. The outer portion at least partially includes a plate portion forming a wall section for transitioning from the polygonal shape of the upper end portion to the circular shape of the lower end portion, the plate portion including a flat plate portion and a curved plate portion. The curved plate portion may include a single curved plate portion and / or a double curved plate portion.

[0008] The support structure has a circular lower end corresponding to the shape of the bearing to which it is connected. Thus, the load from the support structure can be directly transmitted to the bearing. Also, the support structure has an upper end with a polygonal shape. The upper end is typically the side where a boom, support frame, and / or other equipment can be mounted. The boom hinge connection and at least one support frame connection are mounted directly or indirectly on the upper end. Usually, the boom hinge connection can be provided with a pad eye structure that allows the boom to hinge about a horizontal axis. The support frame connection can be a fixed structure or, for example, a hinge connection if it is necessary to make the support frame foldable. By providing a polygonal shape, for example, a rectangle, hexagon, heptagon, or octagon, the connections of the boom and support frame can be positioned in an optimal manner to lift the large loads of the boom and support frame. By at least partially connecting the upper end and the lower end by a plate portion, efficient load transfer from the polygonal upper end to the circular lower end can be obtained, and thus the load can be optimally guided towards the bearing. Accordingly, stress peaks or stress nodes can be reduced.

[0009] As used herein, it should be recognized that the term "connection" in the boom hinge connection, support frame connection, etc. can be understood as a connection structure or fitting, i.e., arranged and configured to connect to another structure, such as a boom or support frame.

[0010] Furthermore, as used herein, "polygonal shape" simply refers to a shape that corresponds to a polygon in the overall or general sense, and thus it should be recognized that this term does not necessarily imply that the shape has any sharp corners or contains no curvature at all. For example, as used herein, a polygonal shape may have so-called rounded corners at one or more of its vertices, while a pure polygon has sharp corners. It should also be recognized that a polygon can take many different forms, including regular and irregular polygons, and can, for example, have one or more concave portions. A polygon generally has a limited number of sides joined at vertices, and in this context, a polygonal shape can correspond to a polygon having up to 16 such sides, preferably up to 12 such sides, more preferably up to 10 such sides, for example about 5, 6, 7, or 8 such sides.

[0011] The outer portion connects the upper end portion to the lower end portion, and in particular, connects the edge of the upper end portion to the edge of the lower end portion, and thus the outer portion provides a transition from the polygonal shape of the upper end portion to the circular shape of the lower end portion. Thus, a smooth transition and load path can be provided from the polygonal upper end portion to the circular lower end portion and to a circular swivel bearing connected to the lower end portion during use. Thus, the outer portion can have a complex geometric shape that provides a transition from the circular lower end portion to the polygonal upper end portion. Often, the diameter of the circular end can be smaller than the maximum diagonal dimension of the polygonal shape, and it is necessary to expand the outer portion in the upward direction. Contrary to a conventional support structure consisting of a circular portion having an additional structure thereon, such as a rectangular platform or beam structure, the outer portion of the support structure of the present invention is of a more complex shape that makes the transition from circular to polygonal in a smooth and / or continuous manner without a discontinuous or abrupt step in the outer portion.

[0012] On the outer part, optionally, a plate part can be provided at least partially that allows a part of the outer part to remain open without being closed by the plate part. In the closed part, a wall section connecting the lower end part to the upper end part is formed. In the optionally open part, a truss structure can be provided to connect the upper end part to the lower end part. The truss members of such a truss structure can be truss members having a cylindrical shape or truss members having a rectangular shape, for example. Alternatively, the truss members can be beam members.

[0013] The plate part that at least partially forms the outer part includes a flat plate part and a curved plate part, and the curved plate part can include a single curved plate part and / or a double curved plate part. Advantageously, the flat plate part and the curved plate part are arranged adjacent to each other. For example, these plate parts can be arranged adjacent to each other in a lateral pattern such that the flat plate part and the curved plate part alternate along the circumference of the outer part. Alternatively, these plate parts can be arranged in an adjacent pattern in the vertical direction such that the curved plate part is below the flat plate part in the upward direction. Thus, a smooth transition can be obtained between a circular-shaped lower end part and a polygonal-shaped upper end part without a sharp or stepped transition between the lower end part and the upper end part.

[0014] Advantageously, a part of the outer part closed by the plate part includes flat plate parts and curved plate parts alternately. For example, the plate part can be a plate part having a substantially triangular shape, and subsequent plate parts can have triangular vertices at their upper and lower ends. Thus, the plate parts having a triangular shape can face alternately upward and downward. Of course, it is understood that the flat plate parts and the curved plate parts can be alternately arranged in different patterns. For example, the plate part facing downward can be a flat plate part, and the plate part facing upward can be a curved plate part. Instead of or in addition to the plate parts having a triangular shape, plate parts having a trapezoidal and / or kite shape can be used. Part or all of the curved plate parts can be curved two-dimensionally, so-called doubly curved plate parts or doubly arched plate parts. On the other hand, singly curved plate parts can also be used. The flat plate part extends substantially in a planar manner. The flat plate part is a straight plate part or a planar plate part, that is, the flat plate part is not curved. By alternating the flat plate parts with the curved plate parts, a state with suppressed manufacturing costs can be maintained while adapting to the transition from the circular-shaped lower end to the polygonal-shaped upper end.

[0015] Advantageously, the entire outer part is closed by the plate part, and thus a single wall section can be formed that provides a closed wall. For example, at the vertices or corners of a polygonal shape, flat plate parts and curved plate parts can alternate, but between the corners, for example, more flat plate parts or larger flat plate parts can be used. It is understood that all the plate parts, i.e., the flat plate parts or the curved plate parts, do not have to be the same. By providing an overall closed outer part, the plate part can support the load and also enable the transmission of the force from the upper end to the lower end and thus towards the bearing. In an alternative manner, the entire outer part is not closed, and in particular, a part of the outer part can remain open between the corners of the polygon. There, a truss structure can be provided to transmit the load between the upper end and the lower end. Advantageously, at the corners of the polygon, plate parts are provided for the transition from the polygonal shape to the circular shape and for transmitting the load. By providing plate parts at the corners of the polygonal shape where the forces can be expected to be higher, the plate parts can provide an efficient and effective load transmission of the load towards the circular-shaped lower end. Additionally, a part of the plate part itself can have a varying thickness to enable the most efficient load path.

[0016] Advantageously, at least one connection part of the boom connection part of the crane and / or the support frame of the crane is provided at a vertex or a corner part of a polygonal shape. Therefore, the connection part may define a polygonal shape. It can be understood that a pair of boom hinge connection parts can be integrated into a pair of support frame connection parts, for example, with a single pair of pad eyes. Also, for example, it can be understood that a pair of boom hinge connection parts can be mounted on the corner part of the upper end part, and the support frame connection part can be mounted more inwardly, or vice versa. This provides an efficient structure because, at the position where the load is generated, the load is directly transmitted not only in the direction towards the lower end part having a circular shape corresponding to the slewing bearing, preferably to the support structure. Therefore, the force can be efficiently transmitted from the position entering the support structure towards the slewing bearing. This enables the force to be transmitted to the slewing bearing in an effective manner and effectively limits the -peak- load on the slewing bearing. This may enable a more efficient and / or more compact design of the slewing bearing.

[0017] Alternatively, the flat plate part can be arranged on a single curved plate part and / or a double curved plate part. Therefore, the lower wall section of the outer part can be made conical, while the upper wall section of the outer part can be made polygonal. In that case, the intersection line between the lower section and the upper section includes an arc line. This is contrary to the conventional support structure having a cylindrical lower section and a rectangular upper section superimposed thereon, with a sudden discontinuous transition between the cylindrical section and the rectangular section. According to the present invention, simply, the upper section is coupled to the lower section to result in the arc line of the intersection line. By providing an upper wall section having a polygonal shape simply connected instead of superimposed on a conical-shaped lower wall so that the arc line forms the intersection line, a smooth transition from the circular-shaped lower end part to the polygonal-shaped upper end part is possible. Such a smooth transition provides a more effective load transfer from the boom hinge connection part and / or the support frame connection part to the slewing bearing while reducing stress nodes or stress spikes.

[0018] Advantageously, below each connection of the boom or support frame to the support structure, a box structure is provided to enable load transfer from the associated connection to the outer and / or lower end portions of the support structure. In practice, a box structure is provided below each connection, boom hinge connection, and / or support frame connection. This box structure supports each connection and provides for the introduction of loads from the connection into the support structure, particularly into the outer portion of the support structure and ultimately into the lower end portion of the support structure. It should be recognized that such box structures can be joined and / or integrated with each other, as further described elsewhere in this specification. In other words, such box structures need not be spaced apart from each other, or otherwise structurally separate or different. The top side of the box structure can provide a deck area at the upper end of the support structure. The boom hinge connection and / or support frame connection can be mounted on the top side of the box structure. The box structure can also be joined on its inner side to the outer portion of the support structure. Thus, the box structure below each of the connections can form a polygonal vertex or corner at the upper end of the support structure. Advantageously, the box structure is joined to the outer portion and thus reinforces the outer portion and provides an efficient load path towards the outer portion.

[0019] The box structure height of the box structure can be higher at the hinge connection than at the support frame connection spaced from the boom hinge connection. Thereby, a higher load transfer capacity and / or higher rigidity can be provided in the region where the load from the boom is mainly transmitted, and weight and materials can be saved in other regions.

[0020] Advantageously, at least two of the box structures below those associated connection parts can be joined to each other, and thus, an elongated box structure that supports at least two connection parts can be formed. Thus, such an elongated box structure can form a side part of a polygonal shape that extends, for example, between two adjacent vertices or corner parts of a polygonal shape. This can provide a rigid structure and also provide some deck areas at the upper end of the support structure between the connection parts. Advantageously, all the box structures are joined to each other to form a box frame that defines the outer edge of a polygon. Thus, the joined box structures provide an overall box structure of a polygon that defines the polygonal shape at the upper end of the support structure and supports the connection parts that form the surrounding box structures. This provides some deck areas at the outer edge of the upper end, for example, to receive equipment or the legs of a jack-up, while allowing the center of the inner upper end of the polygonal shape to be open. Also, the joined box structures that define such a box frame provide a relatively rigid and strong frame at the outer edge of the upper end, enabling efficient load transfer to the support structure. In one example, there may be a pair of hinge boom connection parts and a first pair of support frame connection parts. The hinge boom connection parts can be integrated into the second pair of support frame connection parts, and thus, a polygon with four corner parts, a quadrilateral, can be obtained. Such integration can take various forms, for example, by sharing the same pad eye and / or the same shaft that connects to such a pad eye. Each connection part is supported by a box structure. The box structures are joined to each other and can thus form a box frame along the outer edge of a quadrilateral. This quadrilateral box frame can provide a strong and rigid frame that supports the connection parts and provides effective load transfer to the support structure. In another example, there are a pair of boom hinge connection parts and two pairs of support frame connection parts, and thus, six corner parts are provided, resulting in an upper end with a hexagonal shape. When the adjacent box structures below the associated connection parts are joined to each other, a hexagonal box frame is obtained, providing a rigid and strong edge at the upper end of the support structure.In these examples, although all vertices or corner portions of the polygon are associated with at least one connection portion, it should be recognized that one or more additional vertices or corner portions without such connection portions may be provided to enable a smoother overall transition towards, for example, a circular shape.

[0021] In one example, below the box structure, a pyramid-shaped structure may be provided to further facilitate the transmission of load to the outer part and further to the lower end. Alternatively, such a pyramid-shaped structure can also be integrated into the box structure.

[0022] At least one circumferential ring structure may be further provided inside the outer part of the support structure. Such a circumferential ring structure is preferably substantially parallel to the lower end and / or upper end of the support structure and circumscribes along the circumference of the outer part. Such a ring structure provides additional rigidity and strength. Alternatively, such a ring structure can be provided outside the outer part. However, providing the ring structure inside may be advantageous as it can additionally provide some protection from environmental influences and thereby extend the lifespan.

[0023] Furthermore, on the outer part of the support structure, supplementary stiffeners extending upward may be provided inside or outside the outer part of the outer part. The supplementary stiffeners may pass through the circumferential ring via the opening of the ring structure.

[0024] The present invention further relates to a crane comprising such a support structure, and to a ship provided with such a crane.

[0025] Even more advantageous embodiments are provided by the features of the dependent claims.

Brief Description of the Drawings

[0026] These and other aspects will become even more apparent by referring to the drawings, including the figures of the exemplary embodiments. The drawings show the following.

Figure 1

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[0027] Note that the figures are given as exemplary examples and are not limited to the present disclosure. The drawings may not be to scale. Corresponding elements are indicated by corresponding reference numerals.

[0028] Figure 1 shows a general arrangement of an offshore crane 1. The crane 1 comprises a boom 2 having a boom tip 3 for lifting loads. The crane 1 further comprises a support frame 4, which is embodied here as an A-frame. The support frame 4 is arranged to support lifting wires and / or luffing wires for lifting the boom 2 and / or for lifting loads. For reasons of simplicity, the lifting system and the luffing system are not shown. A drive system for driving the lifting system and / or the luffing system can be provided in a winch house 5, which can surround, for example, a winch for driving the system. The support frame 4 and the boom 2 are mounted on a support structure 10. The support structure 10 is rotatably mounted on a foundation structure 6. The foundation structure 6 is mounted on an offshore structure, for example, on a ship's deck or on a jack-up. The foundation structure 6 is also known as a pedestal. Between the foundation structure 6 and the support structure 10, a slewing bearing 7 is arranged, which enables the support structure 10 to perform a rotational movement about a vertical axis relative to the foundation structure 6. Here, the support frame 4 has four legs, each of which is mounted on the support structure 10 via a support frame connection. The support frame connection is mounted on the support structure 10. It can be understood that other support frame configurations can include three legs having three support frame connections. Here, the boom 2 has two boom legs mounted on the support frame via a boom hinge connection. The boom is hingedly arranged at the boom hinge connection and can rotate about a horizontal rotation axis passing through the boom hinge connection. Here, an equipment box 9 is shown inside the support structure 10. Alternatively, the support structure 10 can be closed, or the equipment can be mounted anywhere on the offshore structure.

[0029] Figure 2 shows an alternative arrangement of the offshore crane 1. In Figure 2, the crane 1 is the leg 8 of a so-called leg crane mounted around the offshore structure. The offshore structure such as a jack-up is provided with three or more legs whose height is adjustable with respect to the outer shell of the offshore structure. The offshore crane 1 can be mounted around such legs. In that case, the support frame 4 and the boom hinge connection are arranged to enable adjustment of the legs upward and downward. Here too, the support frame 4 and the legs 2 are mounted on the support structure 10. The support structure 10 is mounted on a foundation structure 6 that can be mounted on the deck of the offshore structure. A slewing bearing is arranged between the foundation structure 6 and the support structure 10 so as to enable the support structure 10 to rotate about the vertical axis with respect to the foundation structure.

[0030] As also shown in FIG. 3, the support structure 10 has a lower end portion 11 arranged to be mounted on a slewing bearing, and an upper end portion 12 for supporting the support frame 4 and the boom 2 of the crane 1. The upper end portion 12 has a polygonal shape so as to adapt to the positions of the boom hinge connections 20a, 20b and the support frame connections 40a, 40b, 41a, 41b. In the examples of FIGS. 1 and 2, the support frame connections 41a, 41b and the boom hinge connections 20a, 20b are separate connections. It is understood that these connections can likewise be integrated. For example, the support frame connection 41a and the boom hinge connection 20a can be integrated into a single connection mounted on the support structure 10. Typically, such a connection can be embodied as a pad eye, as shown for example in FIG. 3. The lower end portion of the support structure 10 has a circular shape corresponding to the shape and size of the slewing bearing. Thus, since the lower end portion 11 of the support structure 10 corresponds to the slewing bearing, the load transmission to the slewing bearing can be performed in a more effective manner. The lower end portion 11 has a circular edge portion 11a including a flange extending inwardly and / or outwardly for mounting on the slewing bearing. The upper end portion 12 has a polygonal shape. An outer portion 30 is provided between the upper end portion and the lower end portion to connect the circular lower end portion 11 and the polygonal upper end portion 12. In particular, the outer portion 30 connects the outer edge portion 120 of the upper end portion 12 to the outer edge portion 110 of the lower end portion 11. The outer portion 30 at least partially includes a plate portion 300 to form wall sections 31, 32 of the outer portion 30 that connect the upper end portion 12 to the lower end portion 11 in a smooth and / or continuous manner. The plate portion 300 can be a flat plate portion 300f and a curved plate portion 300c. In the example of FIG. 3, plates are provided only in two portions of the outer portion 30, thus forming two wall sections 31, 32. Between the two wall sections 31, 32, the outer portion 30 is open and a truss structure 33 is provided to connect the upper end portion 12 to the lower end portion 11. Preferably, most of the curved plate portion is a single curved plate portion, i.e., having a curvature in only one dimension. On the other hand, at least a part of the curved plate portion, in particular at least a part of the relatively sharp vertices or corner portions of the polygonal shape, can be a doubly curved plate portion.By providing such a curved plate portion, it becomes possible to easily adapt to the transition from the circular shape at the lower end of the support structure to the polygonal shape at the upper end. It should be recognized that the curvature of the curved plate portion can vary and can generally be selected to contribute to a gradual transition from a circular shape to a polygonal shape. Since a single curved plate portion is generally more economical than a double-curved plate portion, a single curved plate portion is suitable when such a single curve is sufficient.

[0031] In wall sections 31, 32 including plate portions 300f, 300c, the flat plate portion 300f and the curved plate portion 300c are arranged adjacent to each other in an alternating pattern. The flat plate portion 300f is adjacent to the curved plate portion 300c adjacent to the flat plate portion 300f etc. when viewed in the circumferential direction. In the horizontal pattern, the flat plate portion 300f and the curved plate portion 300c are positioned adjacent to each other side by side. By providing the flat plate portion 300f and the curved plate portion 300c alternately, wall sections 31, 32 are formed that connect the circular-shaped lower end 11 to the polygonal-shaped upper end 12 in a smooth manner, removing any discontinuous or abrupt transitions.

[0032] Advantageously, the plate portion 300 is substantially triangular in shape. The flat plate portions 300f can have their triangular-shaped vertices oriented downward, and the curved plate portions 300c can have their substantially triangular-shaped vertices oriented upward. Thus, the curved plate portion 300c can connect to the circular-shaped lower end and extend upward. The flat plate portion can connect to the polygonal-shaped upper end and extend downward. Adjacent flat plate portions and curved plate portions are joined at their matching long sides of the triangular shape, for example, by welding.

[0033] In the example of FIG. 3, the two wall sections 31, 32 are provided with an opening space where the truss structure 33 connects the upper end portion 11 and the lower end portion 12. Alternatively, the opening space can be closed by a plate portion, and thus, as shown in FIG. 4, a completely closed outer portion 30 forming a single wall section is obtained. Over the circumference of the outer portion 30, flat plate portions 300f and curved plate portions 300c alternate with each other to form a smooth transition from the circular-shaped lower end portion 11 to the polygonal-shaped upper end portion 12.

[0034] It can be seen that at the vertices or corner portions of the polygonal-shaped upper end portion, the curved plate portions 300c terminate, and between the corner portions, flat plate portions 300f are preferably provided. Thus, an optimal use of the flat plate portions and the curved plate portions is made to limit the use of the curved plate portions, which are more expensive to manufacture than the flat plate portions.

[0035] From both FIGS. 3 and 4, it can be seen that the boom hinge connections 20a, 20b and the support frame connections 40a, 40b, 41a, 41b are separate connections attached to the upper end portion 12. Here, the upper end portion 12 is formed, and connections are provided at the polygonal corner portions, thus obtaining a hexagon. In an example where a pair of boom hinge connections 20a, 20b are integrated with a pair of support frame connections 41a, 41b, an upper end portion having a square or heptagonal shape with connections attached to each corner portion can be obtained.

[0036] It can be seen that a box structure is provided below each of the connection parts 40a, 40b, 41a, 41b, 20a, and 20b. The box structure provides support to the connection parts and also enables force to enter the outer part 30 and transmit the force to the lower end part and further to the swivel bearing. In the embodiments of FIGS. 3 and 4, the respective box structures of the related connection parts 40a, 40b, 41a, 41b, 20a, and 20b are joined to each other to form a joined box structure 50 in which the connection parts are arranged. The joined box structure 50 forms a peripheral box frame whose top side part 51 provides a deck area. The peripheral box frame 50 forms the outer edge of the upper end part 12 having a polygonal shape, and thus defines the polygonal shape of the upper end part 12 of the support structure. The peripheral box frame 50 allows an opening 52, for example, where equipment can be positioned or the legs of a jack-up can be accommodated. By providing such a peripheral box frame 50, additional strength and rigidity that may be beneficial for load transmission can be added to the support structure. The box structure has a top side part 51 that forms the deck area of the support structure 10, and a lower side part 54 parallel to the top side part 51, and an inner part 55 and an outer part 56 provided by the outer part 30 of the support structure. Thus, a box shape that optimally supports the related connection parts is obtained.

[0037] In the cross-section of FIG. 5, the box configuration of the box structure 50 can be seen. The top side part 51 of the box structure provides a deck area, and the outer part 56 of the box structure 50 is joined to the outer part 30 so as to optimize the transmission of force. Further, the box structure is a hollow box and can have ribs 53 for rigidity and / or strength. Also, in the cross-sectional view of FIG. 5, a circular edge part 11a joined to the outer part 30 is shown. The edge part 11a is mounted on the swivel bearing.

[0038] In the cross-sectional view of FIG. 5, it can be seen that a pyramid-shaped structure 60 is further provided below the box structure 50 under the connection part 20a. Such a pyramid-shaped structure 60 is optional, but can provide additional strength and / or rigidity, and similarly, the force from the connection part can be further transmitted toward the lower end part 11. In this sense, the further structure 60 can be regarded as an auxiliary load transmission structure. This further structure 60 has a pyramid shape in this example, but it should be recognized that different shapes are possible for such a structure.

[0039] As can be seen from the cross-sectional view of FIG. 5 or the perspective views of FIGS. 3 or 4, a circumferential ring structure 70 is provided on the inner side 310 of the outer part 30. The ring structure 70 is arranged substantially horizontally, or in other words, is substantially parallel to the lower end part 11 of the support structure 10. The circumferential ring 70 preferably covers the entire circumference on the inner side of the outer part 30. From FIG. 3, it can be seen that the ring structure 70 is intermittent between the wall sections 31, 32. However, in the example of FIG. 3, also in the opening space between the wall sections 31, 32, the ring structure 70 is provided to cover the entire circumference of the outer part 30, and thus it is preferably connected to the truss structure 33 there. At least one ring structure 70 provides additional strength and rigidity to the support structure, particularly rotational or torsional rigidity as well. Further, as can be seen from the cross-sectional view of FIG. 5, the outer part 30 can also be provided with a supplementary stiffener 80 that is at least partially oriented upward. The supplementary stiffener 80 passes through an opening of the ring structure 70 that allows the supplementary stiffener to pass through. The supplementary stiffener 80 can additionally reinforce, for example, the curved plate part 300c. It should be noted that the ring structure 70 and / or the supplementary stiffener 80 can also be provided on the outside of the outer part 30. However, providing the ring structure 70 and / or the supplementary stiffener 80 on the inside can provide higher protection from environmental influences, as well as easier accessibility for maintenance and / or repair.

[0040] FIG. 6 shows a top view of a support structure 10 having a hexagonal shape with boom hinge connections 20a, 20b and support frame connections 40a, 40b, 41a, 41b on respective vertices or corner portions of the hexagon. Also shown is a circle identifying the circular lower end portion 11 of the support structure 10. Since the connections 40a, 40b, 41a, 41b, 20a, 20b are positioned outwardly of the circle of the lower end portion 11, it can be seen that forces are transmitted to the lower end portion in the radial as well as axial directions, in other words, in the horizontal as well as vertical directions. The support structure 10 according to the present invention, which provides a smooth transition from the polygonal upper end portion 12 to the circular lower end portion 11 of the plate portion 300, transmits forces to the swivel bearing in an effective and efficient manner while making it possible to reduce and / or minimize stress peaks. By providing the support structure 10 according to the present invention, which enables effective and efficient force transmission, less material can be used as compared with conventional support structures. The less material results in a lighter support structure, which increases the payload of the ocean-going ship while assisting in adapting to such super-large cranes.

[0041] FIG. 7 shows an alternative embodiment of the support structure 10. Here, the flat plate portion 300f and the curved plate portion 300c are positioned on top of each other in an adjacent manner. The flat plate portion 300f is positioned on top of the curved plate portion 300c. Thus, the curved plate portion 300c can form a lower wall section 30l having a conical shape that extends outwardly from the lower end portion 11. The flat plate portion 300f forms an upper wall section 30u having a polygonal shape that extends downwardly from the upper end portion 12. At the location where the upper wall section 30u contacts the lower wall section 30l, an intersection line 34 is formed where the upper wall section 30u is joined to the lower wall section 30l. The intersection line 34 here includes arc line portions 35a, 35b, etc. In other examples, for example, referring to FIGS. 9 and 10, such an intersection line 34 can be straight. Contrary to a conventional support structure in which a rectangular upper portion is superimposed on a cylindrical lower portion, here, simply the upper wall section is joined to the lower wall section, resulting in an intersection line that is neither parallel nor perpendicular to the upper and lower end portions.

[0042] Here too, below each of the connection parts 20a, 20b, 40a, 40b, 41a, 41b, a box structure 50 is provided, and in this example, the connection parts are joined to a single joined box structure 50 to form a peripheral box frame 50 that forms the upper end portion 12 of the support structure. Thus, as shown previously, it can be considered that each connection part is provided with its own box structure, but such box structures do not actually have to be separate or different. Instead, they can form part of a larger combined structure such as the peripheral box frame 50, and various connection parts can actually all be arranged on the same frame. Here, a pair of support frame connection parts 41a, 41b are integrated with the boom hinge connection parts 20a, 20b at a single connection part. Thus, the integrated connection part is positioned at the corner of the upper end portion 12 having a polygonal shape. The other pair of support frame connection parts 40a, 40b are positioned at two other corners of the upper end portion 12 having a polygonal shape. Thus, in one example, the polygon can be a quadrilateral. However, in the example shown in FIG. 7, a segmented side portion is arranged between the integrated connection parts 41a, 20a, 41b, 20b, resulting in a polygonal shape having four or more vertices or corners so as to fit around, for example, a jack-up leg portion. It is understood that the boom hinge connection part and the support frame connection part can also be attached to the support structure separately. The top side portion 51 of the support structure 50 provides a deck area. In the examples of FIGS. 7 and 8, the support frame connection parts 40a, 40b are positioned somewhat higher than the connection parts 41a, 20a, 41b, 20b respectively so that the top side portion 51 slopes upward from the connection parts 41a, 20a, 41b, 20b to the connection parts 40a, 40b. Alternatively, all the connection parts can be attached at the same level. In the cross-sectional view of FIG. 8, corresponding to the same example as in FIG. 7, it can be seen that the box structure 50 has a box shape in a manner similar to FIGS. 3 and 4. Here, the box structure 50 has a top side portion 51 that forms a deck area, an inner side portion 55, a bottom side portion 54, and an outer side portion 56 formed by the outer side portion 30. A circumferential ring structure 70 is not shown here but can be provided for rigidity.The circular edge portion 11a extends downward and is configured to be mounted on a swivel bearing. Further, as in the examples of FIGS. 3 and 4, an upwardly oriented stiffening member 80 can be provided. The peripheral box frame 50 defines the polygonal shape of the upper end portion 12 and allows a central opening 52 that can accommodate equipment or jack-up legs. The lower end portion 11 can be closed by a bottom as shown in FIG. 3 or FIG. 4, or can be open as in FIG. 7 or FIG. 8.

[0043] FIGS. 9 to 14 show a particularly advantageous fourth embodiment of the support structure 10. Unless the figures and / or the specification indicate otherwise or imply otherwise, this fourth embodiment generally corresponds to the other embodiments disclosed herein, as can be understood particularly from the corresponding reference numerals in the figures.

[0044] In the fourth embodiment, as best seen in FIG. 13 and further as shown in FIG. 11, the height of the box frame 50 varies between a lower first height h1 at the support frame connections 40a, 40b and a higher height h2 at the support frame connections 41a, 41b and the boom hinge connections 20a, 20b. Thereby, the strength of the box frame 50 can be higher on the side of the boom 2 where a greater load can be expected, while other weights can be minimized by keeping the box frame height lower elsewhere. Here, the various heights are essentially realized by the variable level of the lower side portion 54 of the box frame 50 (shown by the dashed line 54 in FIG. 13), while the top side portion 51 of the box frame 50 is here horizontal and thus forms a horizontal deck area. The gradual change in the box frame height between the first height h1 and the second height h2 avoids high stress areas and promotes a gradual distribution of forces through the support structure 10.

[0045] In the fourth embodiment, it can be seen that the upper end portion 12 having a polygonal shape is a heptagon, that is, it has seven sides. It has been found that such a large number of sides generally contribute to advantageous load transfer efficiency between different positions of the connecting portion at the upper end portion 12 and the circular swivel bearing 7 at the lower end portion 11. Nevertheless, it should also be understood that a large number of sides can also be somewhat different, for example, six or eight, with substantially the same advantageous effect.

[0046] Furthermore, compared with other embodiments disclosed herein, the outer portion 30 is particularly smoothly formed in the fourth embodiment so as to correspond to a particularly gradual transition between the polygonal shape of the upper end portion 12 and the circular shape of the lower end portion 11. This can be particularly well seen from FIG. 12, which shows a horizontal cross-sectional view in which the box frame 50 is not shown. Thereby, the efficient distribution of the load through the support structure 10 is further optimized, in particular, the efficiency with respect to the weight of the support structure 10 is optimized. As part of the increased smoothness, the upper end portion 12 has rounded corner portions at the vertices of its polygonal shape, in particular at those vertices where the connecting portions 20a, 20b, 40a, 40b, 41a, 41b are arranged. Specifically, the rounded corner portions at some or all of the vertices can be in an arc shape. The level of rounding is such that the overall polygonal shape is maintained. At the rounded corner portions of the connecting portions, the curved plate portion 300c can be doubly curved so as to adapt to both rounding and spreading, while further away from the rounded corner portions, the curved plate portion 300c can be singly curved. Thus, in the fourth embodiment (FIGS. 9 to 14), apart from near the vertices of the connecting portions 20a, 20b, 40a, 40b, 41a, 41b where a singly curved plate portion or some doubly curved plate portions may be required at each vertex, the relatively complex three-dimensional shape of the outer portion 30 can generally be realized by the flat plate portion 300f and the singly curved plate portion 300c.

[0047] Furthermore, compared with the third embodiment, the three full-height wall portions 30k are provided at intermediate positions in the circumferential direction along each of the three upper wall portions 30u, whereby, compared with the third embodiment, they can be regarded as being divided into two halves. Here, the full-height wall portion 30k includes a curved plate portion 300c that is a single curve and essentially follows the arcuate curvature of the lower end portion 11 up to the upper end portion 12 in this case. In FIGS. 9, 10, and 12, these full-height wall portions 30k are provided with checkerboard hatching simply to more clearly distinguish them from the halves in the vicinity of the upper wall portion 30u. The positions of the full-height wall portions 30k along the polygonal shape of the upper end portion 12 correspond here to three relatively blunt vertices as compared with the four sharper vertices where at least the connection portions are arranged. When viewed from above, these blunt vertices of the upper end portion 12 can coincide with the circular shape of the lower end portion 11, and the full-height wall portions 30k do not require the spread as the lower wall portion 30l has. Furthermore, the bluntness of these vertices means that the arcuate curvature of the lower end portion 11 is locally followed at the upper end portion 12 by rounding without losing the overall polygonal shape of the upper end portion since the vertices can be rounded.

[0048] FIG. 14 shows how the support structure 10 according to the fourth embodiment can be mounted on the offshore crane 1 with the boom 2 and the support frame 4 mounted as shown via the connection portion of the upper end portion 12. It should be recognized that the boom 2 and the support frame 4 can each be of various designs and are therefore only shown schematically here. It can be seen that the base structure 6 is positioned below the support structure 10 with the slewing bearing 7 making the support structure 10 rotatable with respect to the base structure 6.

[0049] For the purpose of making the specification clear and concise, although features are described herein as part of the same or separate embodiments, it will be recognized that the claims and the present disclosure may include embodiments having combinations of all or some of the features described. It will be understood that the embodiments shown may have the same or similar components, unless they are described as being different.

[0050] 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. Further, the words "a" and "an" should not be construed as limiting to "only one", but rather are used to mean "at least one" and do not exclude a plurality. The mere fact that certain means are recited in mutually different claims does not indicate that a combination of these means cannot be used to advantage. Many variations will be apparent to those skilled in the art, provided that the variations are within the scope of the invention as defined in the following claims.

Claims

1. A support structure for a crane, wherein the support structure has: - a lower end portion having a circular shape for connection to a slewing bearing; - an upper end portion having a polygonal shape for supporting the boom of the crane and / or the support frame of the crane; - an outer portion connecting the outer edge of the upper end portion to the outer edge of the lower end portion, and comprising: - at the upper end portion, a pair of boom hinge connection portions for hingedly connecting the boom of the crane, and at least a support frame connection portion for supporting the support frame of the crane; - the outer portion at least partially includes a plate portion forming a wall section for transitioning from the polygonal shape of the upper end portion to the circular shape of the lower end portion, the plate portion including a flat plate portion and a curved plate portion, the support structure.

2. Below each one of the boom hinge connection portions and / or the support frame connection portions, a box structure is provided to enable load transfer from the associated connection portion to the outer portion and / or the lower end portion, the support structure according to claim 1.

3. At least the box structures of the pair of boom hinge connection portions are joined to each other to form a joined box structure, and / or the box structures of the pair of support frame connection portions are joined to each other to form a joined box structure, the support structure according to claim 2.

4. The box structures of the boom hinge connection portions and the support frame connection portions are joined to each other to form a joined box structure, the support structure according to claim 2 or 3.

5. The joined box structure defines at least a part of the polygonal shape of the upper end portion of the support structure, the support structure according to claim 3 or 4.

6. When the box structures of the boom hinge connection portions and the box structures of the support frame connection portions are joined to each other, the joined box structure provides a polygonal box structure defining the polygonal shape of the upper end portion of the support structure, the support structure according to any one of claims 3 to 5.

7. The joined box structure forms the outer edge structure of the upper end portion, the support structure according to claim 6.

8. The support structure according to claim 7, wherein the joined box structure forming the outer edge structure of the upper end portion is a circumferential outer edge structure having a central opening for receiving, for example, a device.

9. The support structure according to any one of claims 2 to 8, wherein an upper side portion of the box structure provides a deck surface for mounting a boom hinge connection portion and / or a support frame connection portion.

10. The support structure according to any one of claims 2 to 9, wherein a box structure height of the box structure is higher at the boom hinge connection portion as compared to a height at a support frame connection portion spaced apart from the boom hinge connection portion.

11. The support structure according to any one of the preceding claims, wherein an entire outer side portion is closed by a plate portion forming a wall connecting a lower end portion having a circular shape and an upper end portion having a polygonal shape.

12. The support structure according to any one of the preceding claims, wherein at least one boom hinge connection portion and / or at least one support frame connection portion is provided at the corner portion having the polygonal shape.

13. The support structure according to any one of the preceding claims, wherein at least one circumferential ring structure is provided inside the outer side portion.

14. The support structure according to any one of the preceding claims, wherein a plurality of supplementary stiffening members extending in an upward direction are provided inside the outer side portion.

15. The support structure according to claim 13 or 14, wherein the ring structure is provided with an opening to enable a supplementary stiffening member to pass through.

16. The support structure according to any one of the preceding claims, wherein the polygonal shape of the upper end portion is a hexagon, a heptagon, or an octagon.

17. The support structure according to any one of the preceding claims, wherein the upper end portion has a central opening for receiving a further object such as a device.

18. The support structure according to any one of the preceding claims, wherein the pair of boom hinge connection portions and at least a pair of support frame hinge connection portions are mounted directly on the upper end portion, particularly on a deck surface of the upper end portion.

19. The support structure according to any one of the preceding claims, wherein the polygonal shape has rounded corner portions at at least some, preferably all, of its vertices, particularly at the vertices where the boom hinge connection portion and / or the support frame connection portion are arranged.

20. The support structure according to any one of the preceding claims, wherein the flat plate portion and the curved plate portion are arranged adjacent to each other.

21. The support structure according to claim 20, wherein the flat plate portion and the adjacent curved plate portion alternate with each other when viewed in the circumferential direction.

22. A crane comprising a foundation structure for mounting on a ship or barge or jack-up, and the support structure according to any one of claims 1 to 21, the crane having a slewing bearing between the foundation structure and the support structure.

23. A ship or barge or jack-up provided with the crane according to claim 22.

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