MAIN GIRDER OF CRANE

Abstract

A main girder of a crane for a crane trolley moving in a horizontal direction along the girder includes a cellular structure in a longitudinal direction thereof that has at least two separate, yet interconnected, longitudinal cellular elements, each cellular element including an outer cover structure and at least one outer cover structure having an inside filled with a core.

Claims

1.-8. (canceled)

9. A main girder of a crane for a crane trolley moving in a horizontal direction along at least one travel rail structure to be arranged on the top surface of the girder, the main girder comprising a cellular structure in a longitudinal direction thereof that has at least two separate, yet interconnected, longitudinal cellular elements, wherein the cellular structure comprises at least two parallel cellular elements or a plurality of parallel and superimposed cellular elements, and each cellular element comprises an outer cover structure with vertical sides, that at least one outer cover structure has an inside filled with a core, and the load caused by the travel rail structure is divided to more than one vertical side.

10. The main girder as claimed in claim 9, wherein the core comprises foamed material and/or solid material that may be glued or thermally attached, for example.

11. The main girder as claimed in claim 10, wherein the foamed material is plastic, e.g. polyurethane.

12. The main girder as claimed in claim 11, wherein the plastic is polyurethane.

13. The main girder as claimed in claim 9, wherein at least the selected cellular elements extend substantially on the entire length of the main girder.

14. The main girder as claimed in claim 9, wherein each cellular element is greater in height than in width.

15. The main girder as claimed in claim 9, wherein the cellular structure comprises cellular elements having a substantially rectangular cross-section.

16. The main girder as claimed in claim 9, wherein the cellular structures are attached together in a sealed and rigid manner.

17. The main girder as claimed in claim 9, wherein the travel rail structure is mounted immediately on top of the cellular structure, symmetrically in the middle of the main girder.

Description

LIST OF FIGURES

[0011] The invention is now described in closer detail by means of the preferred embodiments and with reference to the accompanying drawings, in which:

[0012] FIG. 1 shows a cross section of a prior art main girder;

[0013] FIG. 2 is a perspective view of a main girder in accordance with the invention;

[0014] FIG. 3 shows a cross section of the main girder according to FIG. 2;

[0015] FIG. 4 shows a cross section of an alternative main girder of the invention;

[0016] FIG. 5 shows a cross section of a second alternative main girder of the invention;

[0017] FIG. 6 shows a cross section of yet another alternative main girder of the invention; and

[0018] FIG. 7 shows supporting of the main girder according to FIG. 6 to an end support.

DETAILED DESCRIPTION OF THE INVENTION

[0019] FIG. 1 shows a prior art main girder 1′ of a crane for a crane trolley (not shown) moving in a horizontal direction along the girder, which has a travel rail structure 2′ for the trolley fastened on the upper surface thereof, in a longitudinal direction of the main girder. The main girder 1′ is formed of a horizontal top plate 3′ and bottom plate 4′ and web plates 5′ welded between these and provided with longitudinal reinforcements 6′ and intermediate plates that remain inside a casing structure thus formed. The travel rail structure 2′ is mounted on an upper surface of the main girder 1′, on one side thereof, for transferring vertical loads caused by the trolley to a web structure 5′ in an optimal manner. The top and bottom plates 3′ and 4′ in particular are significantly thick and heavy. The reinforcements 6′ have made it possible to reduce the thickness of the web plates 5′ but, on the other hand, they also are one cause of increased robustness of the structure.

[0020] Next, a reference is made to FIGS. 2 and 3 which illustrate a solution according to the invention. The figures show a main girder 1 of a crane for a crane trolley (not shown) moving in a horizontal direction along the girder, which has a travel rail structure 2 for the trolley mounted on the upper surface thereof, in a longitudinal direction of the main girder. Here the main girder 1 comprises, in a longitudinal direction thereof, a cellular structure 3 with separate, yet interconnected, longitudinal cellular elements 4. The minimum number of the cellular elements 4 is two. In this example there are three parallel cellular elements 4 which are attached together in a sealed and rigid manner with longitudinal welding seams (not shown) at top and bottom seam positions.

[0021] In this example, the cellular elements 4 extend substantially on the entire length of the main girder 1, thus replacing the prior art casing structure altogether. The cellular elements 4 are rectangular and greater in height than in width.

[0022] Each cellular element 4 comprises an outer cover structure 5 and a core 6 of solid or foamed material that fills the inside of the outer cover structure 5. The foamed material may be polyurethane, for example, that adheres well to the inner surface of the outer cover structure 5. The outer cover structure 5 has vertical sides 5a that form the actual web structure, but the core 6 serves as an additional reinforcement and thus a considerably thin material may be used in the entire outer cover structure 5 in comparison with a prior art cover structure.

[0023] The travel rail structure 2 has been mounted immediately on top of the cellular structure 3, symmetrically in the middle of the main girder 1, and thus the load caused by the trolley travelling on the travel rail structure 2 is distributed to each vertical side 5a of the cellular structure 3, which form the web structure of the main girder 1 in question.

[0024] In FIG. 4 the cellular structure 30 of the main girder 10 comprises parallel and superimposed cellular elements 40. There may also be more or less of the cellular elements 40 or a different number in different layers, in which case the web structures do not necessarily need to coincide. There are numerous alternatives implementing the invention. In this example all the cellular elements 40 are filled with a core 60.

[0025] FIG. 5 shows a cellular structure 300 of a main girder 100 which is otherwise similar to the one in FIG. 4 except that only the uppermost cellular elements 400 have a core 600 while the lowermost cellular elements 400a are empty. If so desired, some of the cellular elements in any cellular structure of a main girder of the invention may be full, i.e. filled with a core, while others may be empty, i.e. without a core. The drawings illustrate some examples only.

[0026] FIG. 6 shows a cellular structure 330 of a main girder 110 with three superimposed cellular elements 440, one or more of which is also filled with a core (not shown). In this example the trolley is supported to the bottom surface of the main girder 110 and, for this purpose, the bottom surface of the cellular structure 330 is provided with a flange structure 220 in a longitudinal direction of the main girder 110 for the trolley.

[0027] In the cellular structures of the invention, the cellular elements may be of different heights or sizes, the upper and the lower cellular elements may have a “common” flange in the middle, and the cellular elements may be interconnected by an additional plate/plates although these implementations are not separately shown in the drawings.

[0028] FIG. 7 shows how the positioning of the main girder 110 on an end support E may be adjusted in the structure of the invention, the structure of FIG. 6 being used here as an example, in the longitudinal direction of the main girder 110 without a risk of the structure buckling. In the prior art, the main girder is conventionally provided with transverse intermediate plates reinforcing the web at the support between the main girder and an end girder. In that case the point of support is determined already during the manufacture of the main girder. The present invention enables this restriction to be avoided.

[0029] The above description of the invention is only intended to illustrate the basic idea of the invention. A person skilled in the art may thus vary its details within the scope of the attached claims. Hence the number of the cellular elements, their shape and mutual positioning may vary as required and, therefore, the scope of the invention covers numerous other implementation alternatives in addition to the implementations disclosed here merely as examples.