Mast element for a construction machine, a construction machine and a method of manufacturing the mast element

Abstract

An elongated mast element for a construction machine has a polygonal cross-section including a first wall (10) and a second wall (12), a first guide rail (18) and a second guide rail (20) extending in the longitudinal direction of the mast element, at least one first reinforcing element (26) and at least one second reinforcing element (28) inside the mast element. The first reinforcing element has a first edge connected the first wall and a second edge connected to the first side of the first guide rail, the first wall and the first side of the first guide rail forming a first angle A, and the second reinforcing element has a first edge connected the second wall and a second edge connected to the first side of the second guide rail, the second wall and the first side of the second guide rail forming a second angle B. The construction machine has a leader containing at least one aforementioned mast element.

Description

[0001] Mast element for a construction machine, a construction machine and a method of manufacturing the mast element

[0002] Technical Field

[0003] The invention is related to an elongated mast element for a construction machine, which mast element has a polygonal cross-section including a first wall, a second wall, a first guide rail and a second guide rail extending in the longitudinal direction of the mast element, and at least one first and second reinforcing elements inside the mast element. The invention is further related to a construction machine and a method of manufacturing a mast element.

[0004] Background Art

[0005] Construction and earthwork machines, such as pile driving rigs and drilling rigs may comprise an uppercarriage, an undercarriage carrying the uppercamage and a mast connected to an uppercarriage via a pivot. The mast, also referred to as a leader, is provided with guides along which a carriage for a tool, such as a hammer or rotary head, is configured to move in the longitudinal direction of the mast. The mast may have a length up to 30 meters. During operation of the machine the mast is usually in vertical or slightly slanted position. For transporting the machine the mast is tilted to near horizontal position about the pivot. Because the mast is very long, it is usually made of two or three sections, which are hingedly connected together. For example, the leader of a pile driving rig typically comprises a lower section, a middle section and an upper section, wherein the lower and the middle sections are connected together with a first hinge and the middle and the upper sections are connected together with a second hinge. The second hinge allows the upper section of the mast to be turned next to and parallel to the middle section and the first hinge allows the lower section to be tilted to point slightly downwards.

[0006] The mast sections must be highly rigid and as light as possible in order to ensure reliable guidance for the tool carriage on the one hand and to keep the center of gravity of the entire machine as low as possible for good overturning stability on the other. It is known to use a substantially rectangular hollow profile for such mast elements. To stiffen such mast profiles, it is known to divide the mast profile into segments of a few meters in length and to weld a transverse stiffening plate, also called a mast stiffener, between the segments. The elongated guide rails on the outer surface of the mast also act as an additional stiffening element of the mast. Still there is need for improving especially the torsional resistance and bulking resistance of the mast.

[0007] Document EP 4092195 A1 discloses a mast element, in particular a leader element, for a construction machine with an elongated hollow mast profile with a substantially rectangular cross-section. Inside the hollow mast profile there is a reinforcing element extending diagonally from one side to the mast profile to the opposing side of the mast profile. These kind of large reinforcing elements are heavy, whereby they have a detrimental effect to stability of the machine against overturning. Further, the diagonal reinforcing elements connecting the opposing sides of the mast profile have a modest improving effect to the torsional strength of the mast.

[0008] An object of the invention is to provide mast element for a construction machine, a construction machine and a method of manufacturing a mast element in which drawbacks relating to the prior art are reduced.

[0009] The object of the invention is achieved with the mast element, construction machine and method which are characterized in what is disclosed in the independent patent claims. Some preferred embodiments of the invention are disclosed in the dependent claims.

[0010] Summary of the invention

[0011] The invention is related to an elongated mast element for a construction machine, which mast element has a polygonal cross-section including a first wall and a second wall, a first guide rail and a second guide rail extending in the longitudinal direction of the mast element, said first and second guide rails having a first side, and at least one first reinforcing element and at least one second reinforcing element inside the mast element. The at least one first reinforcing element has a first edge connected the first wall and a second edge connected to the first side of the first guide rail, the first wall and the first side of the first guide rail forming a first angle, and the at least one second reinforcing element has a first edge connected the second wall and a second edge connected to the first side of the second guide rail, the second wall and the first side of the second guide rail forming a second angle. Between the first reinforcing element and the first wall and between the second reinforcing element and the second wall there is an acute angle, which is preferably 15-75 degrees, more preferably 30-60 degrees, most preferably substantially 45 degrees. Preferably, the cross-section of the mast element has a substantially rectangular shape. In some embodiments of the mast element according to the invention the first and second guide rails have a second side forming a corner with the first side and the second edges of the first and second reinforcing elements are connected at said respective corners.

[0012] In some embodiments of the mast element according to the invention the crosssection of the mast element has a third wall, which has a first edge connected to the second side of the first guide rail and a second edge connected to the second side of the second guide rail.

[0013] Some embodiments of the mast element according to the invention further comprise a third guide rail and a fourth guide rail extending in the longitudinal direction of the mast element, said third and fourth guide rails having a first side, and at least one third reinforcing element and at least one fourth reinforcing element inside the mast element and the at least one third reinforcing elements has a first edge connected the first wall and a second edge connected to the first side of the third guide rail, the first wall and the first side of the third guide rail forming a third angle, and the at least one fourth reinforcing element has a first edge connected the second wall and a second edge connected to the first side of the fourth guide rail, the second wall and the first side of the fourth guide rail forming a fourth angle.

[0014] In some embodiments of the mast element according to the invention between the third reinforcing element and the first wall and between the fourth reinforcing element and the second wall there is an acute angle, which is preferably 15-75 degrees, more preferably 30-60 degrees, most preferably substantially 45 degrees.

[0015] In some embodiments of the mast element according to the invention the third and fourth guide rails have a second side forming a corner with the first side and the second edges of the third and fourth reinforcing elements are connected at said respective corners.

[0016] In some embodiments of the mast element according to the invention the crosssection of the mast element has a fourth wall, which has a first edge connected to the second side of the third guide rail and a second edge connected to the second side of the fourth guide rail.

[0017] In some embodiments of the mast element according to the invention the first wall has a first edge connected to the first side of the first guide rail and a second edge connected to the first side of the third guide rail and the second wall has a first edge connected to the first side of the second guide rail and a second edge connected to the first side of the fourth guide rail.

[0018] Some embodiments of the mast element according to the invention has at least two stiffeners inside the mast element, the stiffener having four side edges connected to the respective first, second, third and fourth walls, the adjacent stiffeners being apart from each other in the longitudinal direction of the mast element and the first, second, third and fourth reinforcing elements are connected to the at least two stiffeners.

[0019] In some embodiments of the mast element according to the invention the first, second, third and fourth guide rails have substantially identical, symmetrical cross sections.

[0020] In some embodiments of the mast element according to the invention there is a track on at least one wall of the mast element, the track extending in the longitudinal direction of the mast element.

[0021] The invention is further related to a construction machine comprising a leader. The leader contains at least one mast element explained above. Preferably, the construction machine is a pile driving rig or a drilling rig.

[0022] The invention is further related to method of manufacturing a mast explained above. The method comprises steps of

[0023] - forming a skeleton of the mast element by attaching the first, second, third and fourth guide rails to the stiffeners,

[0024] - supporting one or more of the first, second, third and fourth walls by the first, second, third or fourth reinforcing elements,

[0025] - attaching one or more of the first, second, third and fourth walls supported by the first, second, third or fourth reinforcing elements to the skeleton in a first phase and - attaching one or more of the first, second, third and fourth walls not supported by the first, second, third or fourth reinforcing elements to the skeleton in a second phase.

[0026] In some embodiments of the method according to the invention supporting one or more of the first, second, third and fourth walls by the first, second, third or fourth reinforcing elements in the first phase comprises - attaching the first edge of the first wall to the first guide rail,

[0027] - attaching the second edge of the first wall to the third guide rail,

[0028] - attaching the first reinforcing element to the first wall and to the first side of the first guide rail, and

[0029] - attaching the third reinforcing element to the first wall and to the first side of the third guide rail.

[0030] In some embodiments of the method according to the invention supporting one or more of the first, second, third and fourth walls by the first, second, third or fourth reinforcing elements in the first phase further comprises

[0031] - attaching the first edge of the second wall to the second guide rail,

[0032] - attaching the second edge of the second wall to the fourth guide rail,

[0033] - attaching the second reinforcing element to the second wall and to the first side of the second guide rail and

[0034] - attaching the fourth reinforcing element to the second wall and to the first side of the fourth guide rail.

[0035] In some embodiments of the method according to the invention attaching one or more of the first, second, third and fourth walls not supported by the first, second, third or fourth reinforcing elements to the skeleton in the second phase comprises - attaching the first edge of the third wall to the second side of the first guide rail, - attaching the second edge of the third wall to the second side of the second guide rail,

[0036] - attaching the first edge of the fourth wall to the second side of the third guide rail and

[0037] -attaching the second edge of the fourth wall to the second side of the fourth guide rail. An advantage of the invention is, that the mast element has a high bending strength, high torsional strength and high buckling resistance, although the mass of the mast element is relatively low.

[0038] A further advantage of the invention is, that the mast element is easy to manufacture.

[0039] Brief Description of the Drawings

[0040] In the following the invention will be described in detail, by way of examples, with reference to the accompanying drawings in which,

[0041] Fig. 1a depicts an example of a mast element according to the invention as a cross-section in the transverse direction of the mast element, Figs. 1b depicts the mast element shown in fig. 1a as a cross-section in the longitudinal direction of the mast element,

[0042] Fig. 1c depicts an example of an embodiment of the mast element as a crosssection in the transverse direction of the mast element and

[0043] Fig. 2 depicts an example of a construction machine according to the invention seen from the side.

[0044] Detailed Description

[0045] In figure 1a an example of a mast element according to the invention is shown as a cross-section in the transverse direction of the mast element and in in fig. 1 b part of the same mast element is shown as a cross-section in the longitudinal direction of the mast element.

[0046] The mast element according to the invention is an elongated element, which can be used in a construction or earthwork machine, in particular in a pile driving rig or drilling rig, where the mast element forms the leader or part of the leader of the machine.

[0047] The mast element has a hollow polygonal cross-section including a first wall 10, a second wall 12, a third wall 14 and a fourth wall 16. All walls are metal plates, preferably steel plates, having first and second longitudinal edges. Thickness of the wall can be 3-6 mm, for example 3mm, 4mm, 5mm or 6mm. The first wall is parallel to the opposing second wall and the third wall is parallel to the opposing fourth wall and the neighboring walls are perpendicular to each other, whereby the cross-section of the mast element shown in fig. 1a is substantially rectangular. The distance between the opposing walls of the mast element, i.e. the vertical and lateral dimensions of the cross section can be for example, 500X600 mm, 800x800 or 800x900 mm. The mast element further comprises four guide rails 18, 20, 22, 24 extending in the longitudinal direction of the mast element and placed in the comers of the cross-section. In fig. 1a all guide rails have an identical square cross-section having four sides, including a first side 34 and a second side 36 forming a corner, which corner defines the first border of the first and second sides. The guide rails act as steering / guiding elements for a carriage of a tool, such as a hammer device or rotary head, configured to move along the mast element.

[0048] The first edge of the first wall 10 is connected to first side 34 of the first guide rail 18, the first wall and the first side of the first guide rail forming a first angle A. The second edge of the first wall is connected to the first side 34 of the third guide rail 22, the first wall and the first side of the third guide rail forming a third angle C. Similarly, the first edge of the second wall 12 is connected to the first side 34 of the second guide rail 20, the second wall and the first side of the second guide forming a second angle B and the second edge of the second wall 12 is connected to the first side 34 of the fourth guide rail 24, the second wall and the first side of the fourth guide rail forming a fourth angle D. The edges of the first and second walls are connected near the second border of the first side.

[0049] The first edge of the third wall 14 is connected to the second side 36 of the first guide rail 18 and the second edge of the third wall is connected to the second side 36 of the second guide rail 20. Similarly, the first edge of the fourth wall 16 is connected to the second side 36 of the third guide rail 22 and a second edge of the fourth wall is connected to the second side 36 of the fourth guide rail 24. The edges of the third and fourth walls are connected near the first border of the second side. Inside the mast element there are four reinforcing elements; a first reinforcing element 26, a second reinforcing element 28, a third reinforcing element 30 and a fourth reinforcing element 32. The reinforcing elements are rectangular metal plates, preferably steel plates, having first and second edges in the longitudinal direction of the element. The first edge of the first reinforcing element 26 is connected to the first wall and the second edge of the first reinforcing element is connected to the first side 34 of the first guide rail 18 next to the first border of the first side. The first edge of the second reinforcing element 28 is connected to the second wall and the second edge is connected to the first side 34 of the second guide rail. The second edges of the reinforcing elements are connected near the first border of the first sides of the guide rails. Similarly, the first edge of the third reinforcing element 30 is connected the first wall and the second edge of the third reinforcing element is connected to the first side 34 of the third guide rail 22 next to the first border of the first side and the first edge of the fourth reinforcing element 32 is connected the second wall and the second edge is connected to the first side of the fourth guide rail 24 near the first border of the first side.

[0050] In the embodiment of mast element shown in fig. 1a, the acute angles between the first reinforcing element 26 and the first wall 10, between the second reinforcing element 28 and the second wall 12, between the third reinforcing element 30 and the first wall 10 and between the fourth reinforcing element 32 and the second wall are equal and substantially 45 degrees. Thus, the reinforcing elements “round off” the inner comers between the walls, creating a polygon resembling a closed circle or closed ellipse inside the mast element. It is well known, that a closed tubular structure having a circular cross-section has a better resistance against torsional forces compared to a rectangular cross-section. Therefore, the inventive placement of the reinforcing elements inside mast element greatly improves the torsional resistance of the mast element.

[0051] Further, placement of the reinforcing elements only in the corner areas of the crosssection, whereby they lie near the outer surfaces of the cross section, greatly improves the bending strength of the mast element in all bending directions. Concentration of the reinforcing element in the corner areas of the cross section also increases the stability on the mast element, i.e. the resistance against buckling. The improvements to the torsional and bending strengths and resistance against buckling are all achieved with a minimum amount of reinforcing material, whereby the increase of weigh of the mast element is modest and the stability of the machine carrying the mast element in vertical position is not compromised.

[0052] Inside the mast element there are at least two, preferably several stiffeners 38 at regular intervals. The stiffeners are metal plates, preferably steel plates, having four side edges connected to the respective first, second, third and fourth walls 10, 12, 14, 16. The purpose of the stiffeners is to prevent the buckling of the first, second, third and fourth walls by providing additional supports for the walls in the longitudinal direction of the mast element. The distance between adjacent stiffeners in the longitudinal direction of the mast element can be 500mm - 600mm. In the middle of the stiffeners there is an aperture 44 for reducing the weight of the stiffener. Further, on the inner surfaces of the first, second, third and fourth walls 10, 12, 14, 16 there are ribs 42 extending in the longitudinal direction of the mast elements. The purpose of the ribs is to increase the buckling resistance of the walls.

[0053] The first, second, third and fourth reinforcing elements 26, 28, 30, 32 are connected to the stiffeners inside the mast element. The stiffeners may extend into comers of the mast element, whereby each reinforcing element extends between two adjacent stiffeners and the end edges of the reinforcing elements abutting the stiffeners are connected to the surfaces of the stiffener, preferably by welding. Alternatively, at least some of the stiffeners may be adapted for letting one or more of the reinforcing elements to extend past the stiffeners. In an example, at least some of the stiffeners may be shaped to one or more reinforcing elements positioned at the comers of the mast element. In this way the one or more reinforcing elements may extend inside the mast element past one or more stiffeners, and even over the whole length of the mast element. It should be noted that each reinforcing element, whether it extends between two adjacent stiffeners or past one or more stiffeners may be bordering a channel 46 inside the mast element extending in the longitudinal direction of the mast element. The channels may have a triangular cross-section. In an example, at least some of the stiffeners may be shaped at each four comers of the mast element to one or more reinforcing elements positioned at the comers of the mast element, whereby the stiffeners are octagons, and the short edges of the stiffeners abutting the surfaces of the reinforcing elements are connected to the reinforcing elements, preferably by welding.

[0054] On the second wall 12 of the mast element there is a track 40 extending in the longitudinal direction of the mast element and acting as are steering / guiding element for a tool carriage or a slide connecting the mast element to a support element, such as a cylinder for supporting the mast element. In an example, the track may be formed to the second wall by a support plate. The support plate is at an intermediate portion of the second wall and the support plate runs in the longitudinal direction of the mast element. In this way the second wall may be reinforced against buckling of the mast element. In an example, the intermediate portion of the second wall, and the support plate, is connected to the guide rails 20, 24 by edge portions of the second wall. The support plate may have a higher material strength, e.g. by having a larger thickness, than the edge portions. In an example, the support plate may extend between the stiffeners for distributing forces acting on the second wall, whereby resistance of the mast element against buckling may be improved at the second wall. In an example, the track 40 may serve for supporting a head element of cylinder slidably to the second wall of the mast element. The cylinder may be a lifting cylinder for lifting several mast elements that have been attached together in a leader.

[0055] In figure 1c an example of an embodiment of the mast element according to the invention is shown as a cross-section in the transverse direction of the mast element. The embodiment of fig. 1c contains all the features of the mast element shown in fig. 1a and the features common to both embodiments are referred to with same reference numerals.

[0056] The embodiment shown in fic. 1c differs from the mast element shown in fig. 1a in that the first, second, third and fourth reinforcing elements 26, 28, 30, 32 are wider than in fig. 1a. The the acute angles between the first reinforcing element 26 and the first wall 10, between the second reinforcing element 28 and the second wall 12, between the third reinforcing element 30 and the first wall 10 and between the fourth reinforcing element 32 and the second wall are equal, but significantly less than 45 degrees. The reinforcing elements still “round off” the inner comers between the walls, but the created polygon has now a slightly a different shape resembling a closed circle or closed ellipse inside the mast element. In the claimed invention the acute ancle between the reinforcing elements and the walls can vary depending on constructional requirements of the mast element. Further, the acute ancle between the reinforcing element and the wall does not have to be equal with all reinforcing elements. The acute ancle between the reinforcing element and the wall to which its element is attached to, can vary between 15-75 degrees, although substantially 45 degrees is the most preferable.

[0057] The method of manufacturing the mast element according to the invention comprises steps of forming a skeleton of the mast element by attaching the guide rails 18, 20, 22, 24 to the stiffeners 38. Then, the walls 10, 12, 14, 16 are attached to the skeleton in at least two phases comprising a first phase of attaching one or more walls that are supported by the reinforcing elements 26, 28, 30, 32 and a second phase of attaching one or more walls that are not supported by the reinforcing elements. In this way the reinforcing elements may be enclosed inside the mast element.

[0058] In an example, the first phase may comprise that the first edge of the first wall 10 is attached to the first guide rail 18, the second edge of the first wall 10 is attached to the third guide rail 22, the first reinforcing element 26 is attached to the first wall and to the first side 34 of the first guide rail, and the third reinforcing element 30 is attached to the first wall and to the first side of the third guide rail. In this way the first wall may be supported by the reinforcing elements.

[0059] In an example, the first phase may further comprise that the first edge of the second wall 12 is attached to the second guide rail 20, the second edge of the second wall 12 is attached to the fourth guide rail 24, the second reinforcing element 28 is attached to the second wall and to the first side 34 of the second guide rail, and the fourth guide rail 24 is attached to the second edge of the second wall and to the first side 34 of the fourth guide rail. In this way the second wall may be supported by the reinforcing elements.

[0060] In an example, the second phase may comprise attaching the first edge of the third wall to the second side of the first guide rail and the second edge of the third wall the second side of the second guide rail and attaching the first edge of the fourth wall to the second side of the third guide rail and a second edge of the fourth wall to the second side of the fourth guide rail.

[0061] It should be noted for improving strength of the mast element against crinkling the first phase may be preceded by a preparatory phase of attaching ribs 42 to the walls. Preferably all parts of the mast element are attached by welding e.g. by butt welds. Thanks to the inventive placement of the reinforcing elements inside the mast element manufacturing of the mast element is simple.

[0062] In fig. 2 an example of a construction machine according to the invention in seen from the side. The construction machine shown in fig. 2 is pile driving rig or a drilling comprising an undercarriage 50, an uppercarriage 52 and a leader 60 connected to the uppercarriage via a pivot 62. A carriage 54 for carrying a tool 56, such as a hammer device or rotary head, is configured to move along the leader. In fig. 2 the leader is in an upright working position. Preferably, leader contains a first hinge 64 and a second hinge 66 dividing the leader into three sections; a lower section 68, a middle section 70 and an upper section 72. Fortransporting the machine, the middle section of the leader can be turned to a horizontal position about the pivot 62, the upper section 72 can be turned next to and in parallel to the middle section 70 about the first hinge 64 and the lower section 68 of the leader can be tilted to a downwards slanting position about the second hinge 66. At least one section of the leader, preferably all sections of the leader, contain at least one mast element according to the invention. Some preferred embodiments of the mast element, construction machine and method of manufacturing the mast element have been disclosed above. The invention is not limited to the solutions explained above, but the invention can be applied in different ways within the limits set by the patent claims. Reference Signs:

[0063] 10 first wall

[0064] 12 second wall

[0065] 14 third wall

[0066] 16 fourth wall

[0067] 18 first guide rail

[0068] 20 second guide rail

[0069] 22 third guide rail

[0070] 24 fourth guide rail

[0071] 26 first reinforcing element 28 second reinforcing element 30 third reinforcing element 32 fourth reinforcing element 34 first side

[0072] 36 second side

[0073] 37 shape

[0074] 38 stiffener

[0075] 40 track

[0076] 42 rib

[0077] 44 aperture

[0078] 46 channel

[0079] 50 undercarriage

[0080] 52 uppercarriage

[0081] 54 carriage

[0082] 56 tool

[0083] 60 leader

[0084] 62 pivot

[0085] 64 first hinge

[0086] 66 second hinge

[0087] 68 lower section

[0088] 70 middle section

[0089] 72 upper section

[0090] A first angle

[0091] B second angle

[0092] C third angle

[0093] D fourth angle

Claims

Claims1. An elongated mast element for a construction machine, which mast element has a polygonal cross-section including a first wall (10) and a second wall (12), a first guide rail (18) and a second guide rail (20) extending in the longitudinal direction of the mast element, said first and second guide rails (18, 20) having a first side (34), and at least one first reinforcing element (26) and at least one second reinforcing element (28) inside the mast element, the at least one first reinforcing element (26) has a first edge connected to the first wall (10) and a second edge connected to the first side (34) of the first guide rail (18), the first wall (10) and the first side (34) of the first guide rail (18) forming a first angle (A), and the at least one second reinforcing element (28) has a first edge connected the second wall (12) and a second edge connected to the first side (34) of the second guide rail (20), the second wall (12) and the first side (34) of the second guide rail (20) forming a second angle (B), characterised in that between the first reinforcing element (26) and the first wall (10) and between the second reinforcing element (28) and the second wall (12) there is an acute angle, which is preferably 15-75 degrees, more preferably 30-60 degrees, most preferably substantially 45 degrees.

2. A mast element according to claim 1 , characterised in that the first and second guide rails (18, 20) have a second side (36) forming a corner with the first side (34), and the second edges of the first and second reinforcing elements (26, 28) are connected at said respective comers.

3. A mast element according to claim 2, characterised in that the cross-section of the mast element has a third wall (14), which has a first edge connected to the second side (36) of the first guide rail (18) and a second edge connected to the second side (36) of the second guide rail (20).

4. A mast element according to any of the claims 1 to 3, characterised in that the mast element further comprises a third guide rail (22) and a fourth guide rail (24) extending in the longitudinal direction of the mast element, said third and fourth guide rails (22, 24) having a first side (34), and at least one third reinforcing element (30) and at least one fourth reinforcing element (32) inside the mast element and the at least one third reinforcing element (30) has a first edge connected the first wall (10) and a second edge connected to the first side (34) of the third guide rail (22), the first wall (10) and the first side (34) of the third guide rail (22) forming a third angle (C), and the at least one fourth reinforcing element (32) has a first edge connected the second wall (12) and a second edge connected to the first side (34)of the fourth guide rail (24), the second wall (12) and the first side (34) of the fourth guide rail (24) forming a fourth angle (D).

5. A mast element according to claim 4, characterised in that between the third reinforcing element (30) and the first wall (10) and between the fourth reinforcing element (32) and the second wall (12) there is an acute angle, which is preferably 15-75 degrees, more preferably 30-60 degrees, most preferably substantially 45 degrees.

6. A mast element according to claim 4 or 5, characterised in that the third and fourth guide rails (22, 24) have a second side (36) forming a corner with the first side (34), and the second edges of the third and fourth reinforcing elements (30, 32) are connected at said respective comers.

7. A mast element according to claim 6, characterised in that the cross-section of the mast element has a fourth wall (16), which has a first edge connected to the second side (36) of the third guide rail (22) and a second edge connected to the second side (36) of the fourth guide rail (24).

8. A mast element according to any of the claims 4 to 7, characterized in that the first wall (10) has a first edge connected to the first side (34) of the first guide rail (18) and a second edge connected to the first side (34) of the third guide rail (22) and the second wall (12) has a first edge connected to the first side (34) of the second guide rail (20) and a second edge connected to the first side (34) of the fourth guide rail (24).

9. A mast element according to claim 7 or 8, characterized in that the mast element has at least two stiffeners (38) inside the mast element, the stiffener having four side edges connected to the respective first, second, third and fourth walls (10, 12, 14, 16), the adjacent stiffeners (38) being apart from each other in the longitudinal direction of the mast element and the first, second, third and fourth reinforcing elements (26, 28, 30, 32) are connected to the at least two stiffeners (38).

10. A mast element according to any of the claims 4 to 9, characterized in that the first, second, third and fourth guide rails (18, 20, 22, 24) have substantially identical, symmetrical cross sections.

11. A mast element according to any of the claims 1 to 10, characterized in that there is a track (40) on at least one wall (10, 12, 14, 16) of the mast element, the track (40) extending in the longitudinal direction of the mast element.

12. A mast element according to any of the claims 1 to 11 , characterized in that the cross-section of the mast element has a substantially rectangular shape.

13. A construction machine comprising a leader (60), characterized in that the leader contains at least one mast element according to any of the claims 1 to 12.

14. A method of manufacturing a mast element according to any of the claims 9 to 12, characterized in that the method comprises steps of- forming a skeleton of the mast element by attaching the first, second, third and fourth guide rails (18, 20, 22, 24) to the stiffeners (38),- supporting one or more of the first, second, third and fourth walls (10, 12, 14, 16) by the first, second, third or fourth reinforcing elements (26, 28, 30, 32),- attaching one or more of the first, second, third and fourth walls (10, 12, 14, 16) supported by the first, second, third or fourth reinforcing elements (26, 28, 30, 32) to the skeleton in a first phase and- attaching one or more of the first, second, third and fourth walls (10, 12, 14, 16) not supported by the first, second, third or fourth reinforcing elements (26, 28, 30, 32) to the skeleton in a second phase.

15. A method according to claim 14, characterised in that supporting one or more of the first, second, third and fourth walls (10, 12, 14, 16) by the first, second, third or fourth reinforcing elements (26, 28, 30, 32) in the first phase comprises- attaching the first edge of the first wall (10) to the first guide rail (18),- attaching the second edge of the first wall (10) to the third guide rail (22),- attaching the first reinforcing element (26) to the first wall (10) and to the first side (34) of the first guide rail (18), and- attaching the third reinforcing element (30) to the first wall (10) and to the first side (34) of the third guide rail (22).

16. A method according to claim 14 or 15, characterised in that supporting one or more of the first, second, third and fourth walls (10, 12, 14, 16) by the first, second, third or fourth reinforcing elements (26, 28, 30, 32) in the first phase further comprises- attaching the first edge of the second wall (12) to the second guide rail (20), - attaching the second edge of the second wall (12) to the fourth guide rail (24), - attaching the second reinforcing element (28) to the second wall (12) and to the first side (34) of the second guide rail (20) and- attaching the fourth reinforcing element (32) to the second wall (12) and to the first side (34) of the fourth guide rail (24).

17. A method according to any of the claims 14-16, characterised in that attaching one or more of the first, second, third and fourth walls (10, 12, 14, 16) not supported by the first, second, third or fourth reinforcing elements (26, 28, 30, 32) to the skel-eton in the second phase comprises- attaching the first edge of the third wall (14) to the second side (36) of the first guide rail (18),- attaching the second edge of the third wall (14) to the second side (36) of the second guide rail (20),- attaching the first edge of the fourth wall (16) to the second side (36) of the third guide rail (22) and-attaching the second edge of the fourth wall (16) to the second side (36) of the fourth guide rail (24).

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