Derrick Crane

Abstract

A derrick crane comprising a main boom (10) and a derrick boom (20), the tips of which are connected to each other via a main guy wire (11), wherein the main guy wire (11) has a length-variable luffing rigging (21) arranged between the main boom (10) and the derrick boom (20) to change the length of the main guy wire (11) when the main boom (10) is luffed, and with an additional guy wire (12, 13) which connects the main guy wire (11) to the main boom (10), wherein the additional guy wire (12, 13) has a fixed length, characterized in that at least two additional guy wires (12, 13) are provided which connect the main guy wire (11) to the main boom (10), wherein the at least two additional guy wires (12, 13) have a fixed length, that the length of the additional guy wires (12, 13) and the position of the connection points (30, 31, 40, 41) is chosen such that,that at the beginning of the erection process of the main boom (10) at least one of the additional guy wires (12, 13) is not loaded and only transmits a tensile force to the main boom (10) when a certain erection angle is exceeded, and that the additional guy wires (12, 13) are formed by cables of fixed length.

Description

[0001] The present invention relates to a derrick crane with a main boom and a derrick boom, the tips of which are connected to each other via a main guy wire, wherein the main guy wire has a length-variable luffing rigging arranged between the main boom and the derrick boom in order to change the length of the main guy wire when the main boom is luffed.

[0002] When the main boom of a derrick crane is raised, the derrick boom remains in a fixed position, while the length of the main guy wire between the main boom and the derrick boom is changed via the luffing cable. As a result, the geometry of the triangle formed by the main boom, derrick boom, and main guy wire changes continuously as the main boom is raised.

[0003] When the main boom is raised and lowered from an assembly position to a lifting position, a tensile force is introduced into the main bracing (usually tie rods) attached to the outer end of the main boom by the luffing rigging. The main bracing thus compresses the boom by means of a first component, while the main boom is lifted against its own weight by means of a second component of this force. Due to the unfavorable angles, the first component is always significantly larger than the second component. Furthermore, the dead weight of the main boom increases with its length. Therefore, a high bending moment acts on the main boom during raising.

[0004] To reduce this bending moment, it is known to provide an additional bracing between the main boom and the main guy wire, which stabilizes the main boom during erection and thus reduces the bending moments acting on the main boom. However, particularly long booms cannot be erected as described above with only one additional bracing. To erect these particularly long booms, a known solution is to support the main boom with an additional bracing of fixed length and another additional bracing of variable length. The additional bracing located closer to the base of the main boom has a variable length in order to be able to adapt to the changing geometric relationships between the derrick boom, main boom, and main guy wire during erection. In particular, complex cable guides with one or more pulleys for the additional bracing are used.Furthermore, the rope length of the variable additional guying reaches considerable lengths (e.g. over 100 m), which makes handling during assembly more difficult.

[0005] For main booms that are erected during operation with a support frame, several additional guy wires with fixed lengths and fixed connection points are already known. In this situation, however, the main boom, the guy wire frame, and the main guy wire form a triangle that is tilted as a whole when the main boom is tilted, so that the geometric relationships in the triangle are approximately constant.

[0006] In contrast, for derrick cranes with changing geometric conditions during the luffing process, experts have previously assumed that when using more than one additional guy wire, only additional guy wires of variable length are able to ensure sufficient support of the main boom during the erection process.

[0007] Contrary to this prejudice of the experts, the inventors of the present invention have found that, surprisingly, several additional guy wires of a fixed length are also suitable to sufficiently support the main boom of a derrick crane during erection, so that longer booms are possible even without the variable guy wires used previously. These longer booms can nevertheless be erected independently without an auxiliary crane.

[0008] The present invention thus comprises a derrick crane with a main boom and a derrick boom, the tips of which are connected to each other via a main guy wire, wherein the main guy wire has a length-variable luffing rigging arranged between the main boom and the derrick boom in order to change the length of the main guy wire when the main boom is luffed, and wherein at least two additional guy wires are provided which connect the main guy wire to the main boom, wherein the at least two additional guy wires have a fixed length.

[0009] Due to the variable geometry and the different tensile force requirements in the auxiliary stays depending on the main boom angle, auxiliary stays of variable length would be the optimal solution for supporting the main boom. However, such auxiliary stays of variable length are technically complex and complicated to handle. The inventors of the present invention have recognized that auxiliary stays of fixed length ensure sufficient stability of the main boom and are considerably simpler in their technical design and handling than The previously used only variable-length additional guy wires. In particular, the installation of fixed-length additional guy wires is considerably simpler.

[0010] The present invention is advantageously used in derrick cranes with a lattice boom main boom to support it, in particular when erecting from the horizontal and at large radii, at at least two points between the linkage of the boom and the boom tip.

[0011] At least two additional guy wires of fixed length are provided, since particularly long booms cannot be erected as described above with only one additional guy wire. The at least two additional guy wires of fixed length according to the invention thus represent a solution that achieves sufficient stabilization with a minimum of effort and additional weight.

[0012] Furthermore, the additional guy wires are advantageously connected to the main guy wire and the main boom at fixed connection points. The geometry of the main guy wire and the additional guy wire is thus defined solely by the fixed positions of the connection points on the main guy wire and the main boom and the fixed lengths of the additional guy wires between these connection points. This results in particularly simple assembly and extremely low additional weight for the guy wire. Each additional guy wire runs from a connection point with the main guy wire to the connection point with the additional guy wire.

[0013] According to the invention, the length of the at least two additional guy wires and the position of the connection points are advantageously selected such that at the beginning of the erection process of the main boom, both additional guy wires transmit a tensile force to the main boom. As a result, during the erection of the main boom, both additional guy wires absorb a force supporting the main boom. The length and arrangement of the additional guy wires are selected such that the forces introduced into the main boom by the additional guy wires during crane operation in the erected state increase the lifting capacity of the crane or at least only minimally impair it.

[0014] Alternatively or additionally, the length of the auxiliary stays and the position of the connection points can also be selected such that at the beginning of the erection process of the main boom, at least one auxiliary stay is not loaded and only transmits a tensile force to the main boom when a certain erection angle is exceeded. The initially unloaded auxiliary stay thus does not serve to erect the main boom, but rather to increase the load-bearing capacity at certain, particularly shallow, boom angles. In particular, the initially unloaded auxiliary stay can be a third auxiliary stay.

[0015] Advantageously, the additional guy wires are formed by cables of fixed length. These are arranged between the fixed connection points on the main boom and on the main guy wire.

[0016] Advantageously, more than two additional guy wires can also be used, in particular three additional guy wires.

[0017] The present invention will now be described in more detail with reference to exemplary embodiments and drawings. These show:

[0018] Fig. 1: a first embodiment of a derrick crane according to the invention,

[0019] Fig. 2a, Fig. 2b: two different embodiments of a derrick crane according to the invention during the erection of the main boom,

[0020] Fig. 3a–Fig. 3c: the bending moments in the main boom during erection of a derrick crane according to the prior art in comparison to two derrick cranes according to the present invention.

[0021] Fig. 1 shows an embodiment of a derrick crane according to the invention with a main boom 10 and a derrick boom 20, the tips of which are connected to each other via a main guy wire 11. The main boom 10 is shown schematically as a line in the drawing. Advantageously, the main boom is a lattice boom. Likewise, the derrick boom is advantageously a lattice boom. The main guy wire 11 has a length-adjustable luffing rigging 21 to change the length of the main guy wire for luffing the main boom. The luffing rigging 21 is integrated into the main guy wire between the main boom and the derrick boom and typically extends between the derrick boom and a pulley block of the main guy wire 11. The length of the luffing rigging is changed by means of a winch.The derrick crane can also have a derrick ballast attached to the derrick boom. However, the derrick ballast can also be detached from the crane after the boom has been erected. Furthermore, a 50 mm hoist rope is provided for lifting the load, which has a minimum length of... a deflection pulley is guided at the top of the main boom.

[0022] In addition to the main bracing 11, two auxiliary bracings 12 and 13 are provided according to the invention, each having a fixed length. The auxiliary bracings 12 and 13 each run between the main bracing 11 and the main boom. The connection points 30 and 31 with the main bracing 11 are each arranged at fixed positions between the main boom tip and the luffing jib, meaning that the connection points are fixed in their position relative to the main bracing 11. The connection points 40 and 41 with the main boom are each arranged at fixed positions between the main boom tip and the main boom pivot point on the superstructure, meaning that the connection points are fixed in their position relative to the main boom.

[0023] The two additional guy wires 12 and 13 are thus connected to the main guy wire 11 and the main boom 10 at fixed connection points and each has a fixed length. The geometry of the guy wire is therefore defined solely by the position of the connection points and the fixed length of the additional guy wires. The fixed lengths of the additional guy wires and the fixed positions of the connection points are chosen such that the additional guy wires can remain engaged in every boom position and achieve sufficient effect. Although this represents a disadvantage with regard to the guy wire properties compared to a solution with variable lengths of the additional guy wires, as known from the prior art, it is surprisingly still suitable for providing sufficient guy wire and is advantageous with regard to the cost savings, weight savings, and the number of components saved.Advantageously, the crane is designed in such a way that the additional bracing can only be installed in a single defined position within the system consisting of main boom 10 and main bracing 11. This further simplifies the installation of the additional bracing.

[0024] In Fig. 2a, the embodiment shown in Fig. 1 is depicted during the raising of the main boom or with a main boom in a strongly tilted position. Fig. 2b, on the other hand, shows a second embodiment of the present invention in which three additional bracing elements of fixed length and fixed position are used.

[0025] In Figures 3a to 3c, the bending moment distribution in the main boom of two derrick cranes according to the present invention is schematically compared with that of a prior art derrick crane. The magnitude of the bending moment 50, which is schematically shown along the main boom, is represented by the distance of the bending moment curve from the main boom.

[0026] Figure 3a shows a derrick crane according to the prior art, in which only one additional bracing is provided. Particularly long booms cannot be erected at all with only such an additional bracing due to the high bending moments, without external aids. The problem is not tipping over, which could be solved by adding more ballast, but rather the destruction of the main boom. With only one additional bracing, the stresses in the corner legs and the corner leg connections become too great during erection.

[0027] As shown in Figures 3b and 3c, the bending moment in the main boom is reduced by the at least two additional bracing provided according to the invention, thus enabling significantly longer booms. The inventors of the present invention have surprisingly discovered that, contrary to the prevailing opinion in the field, additional bracing of a fixed length can also be used for this purpose. The fixed additional bracing is designed such that it provides sufficient support to the main boom during erection and, at the same time, in steep positions of the main boom, only increases the load-bearing capacity as much as possible or at least impairs it only minimally.

[0028] The present invention makes it possible to save costs, weight and number of components and to significantly simplify assembly.

Claims

[1] Derrick crane with a main boom and a derrick boom, the tips of which are connected to each other by a main guy wire, wherein the main guy wire has a length-variable luffing rigging arranged between the main boom and the derrick boom to change the length of the main guy wire when the main boom is luffed, and wherein at least two auxiliary guy wires are provided which connect the main guy wire to the main boom, wherein the at least two auxiliary guy wires have a fixed length. [2] Derrick crane according to claim 1, wherein the additional guy wires are connected to the main guy wire and the main boom at fixed connection points. [3] Derrick crane according to claim 1 or 2, wherein The length of the at least two additional guy wires and the position of the connection points are chosen so that at the beginning of the erection process of the main boom both additional guy wires transfer a tensile force to the main boom. [4] Derrick crane according to claim 1 or 2, wherein the length of the additional guy wires and the position of the connection points are selected such that at the beginning of the erection process of the main boom at least one additional guy wire is not loaded and only transmits a tensile force to the main boom when a certain erection angle is exceeded. [5] Derrick crane according to one of the preceding claims, wherein the additional stays are formed by ropes of fixed length.

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