Abstract
Crane girder (1) for a crane (3), wherein the crane girder (1) includes a hollow profile (4) having an outer wall (6) enclosing a cavity (5) and extends longitudinally, and the outer wall (6) of the crane girder (1), as seen in a cross-section through the crane girder (1), has a shape which bulges outwards at least in some regions in order to reduce aerodynamic drag, wherein the outer wall (6), as seen in the cross-section through the crane girder (1), has two sections (10, 11) facing one another with an outwards bulging shape, which are joined together by two straight wall sections (12) of the outer wall (6), these straight wall sections face one another, and the crane girder (1) has at least one running surface (13) for at least one running wheel (14) of a trolley (15) of a lifting tool of the crane (3), wherein the sections (10, 11) facing one another with an outwards bulging shape point upwards and downwards in an operating position of the crane girder and the straight wall sections (12) delimit the crane girder (1) on the sides.
Claims
1. A crane girder for a crane, the crane girder comprising a hollow profile, having an external wall that encloses a cavity, and extends longitudinally, and the external wall, when viewed in a cross section through the crane girder, has at least in regions an outwardly bulging shape for reducing aerodynamic drag, the external wall, when viewed in the cross section through the crane girder, has two mutually opposite portions, having an outwardly bulging shape, which are interconnected by two mutually opposite straight wall portions of the external wall, and at least one running surface adapted to support at least one running wheel of a trolley of a lifting gear of the crane, the mutually opposite portions, having an outwardly bulging shape, in an operating position of the crane girder point upward and downward, and the straight wall portions in the operating position laterally delimit the crane girder, the straight wall portions extend vertically, the running surface is at least one of disposed or supported on one of the straight wall portions of the external wall, and a thickness extent of the external wall in a vertical direction, when viewed in the cross section through the crane girder, is between 50% and 80% of a width extent of the external wall in a horizontal direction.
2. The crane girder as claimed in claim 1, wherein the crane girder is movable in at least one movement direction, and a width extent of the external wall of the crane girder is delimited in parallel with the movement direction by a first end and a second end of the width extent, and when viewed in the cross section through the crane girder a spacing, which is measured orthogonally to the movement direction, between two mutually opposite portions of the external wall at least in regions increases from at least one of the ends of the width extent of the cavity toward a central region of the cavity.
3. The crane girder as claimed in claim 2, wherein the spacing between the two mutually opposite portions of the external wall at least in regions increases from both of the ends of the width extent of the cavity toward a central region of the cavity.
4. The crane girder as claimed in claim 1, wherein the shape of the external wall that at least in regions is outwardly bulging, when viewed in the cross section through the crane girder is configured to be rounded.
5. The crane girder as claimed in claim 1, wherein the shape of the external wall that at least in regions is outwardly bulging, when viewed in the cross section through the crane girder is configured to be polygonal.
6. The crane girder as claimed in claim 1, wherein the running surface is configured as a rail.
7. A crane comprising at least one crane girder as claimed in claim 1.
8. The crane girder as claimed in claim 1, wherein the running surface is at least one of disposed or supported on top of one of the straight wall portions of the external wall.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Further features and details of preferred design embodiments of the invention are illustrated in the appended illustrations in the form of various variants. In the drawing:
(2) FIGS. 1 to 3 show various design embodiments of cranes having crane girders according to the invention;
(3) FIG. 4 shows a cross section through the crane girder shown in FIGS. 1 to 3; and
(4) FIGS. 5 and 6 show alternative design embodiments of the above.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(5) FIG. 1 shows a crane 3 in the form of a gantry crane in which the crane girder 1, configured according to the invention, in the operating position shown is embodied as a main girder which is disposed in a substantially horizontal manner. As is illustrated more clearly in FIG. 4, this main girder 1 has a hollow profile 4 in which the cavity 5 is enclosed by an external wall 6. As can be readily seen in the cross section through the crane girder 1 according to FIG. 4, the external wall 6 of the crane girder is configured having an at least in regions outwardly bulging shape for reducing the aerodynamic drag. In the specific exemplary embodiment, the portions 10 and 11, forming the upper boom and the lower boom, are provided with an outwardly bulging shape. Laterally, the external wall 6 is composed of straight wall portions 12. The main girder 1 according to FIG. 1 supports the trolley 15 to which a lifting gear (not illustrated here), known per se, of the crane is fastened. The trolley 15 is displaceable in the longitudinal direction 27 along the crane girder or main girder 1, respectively. To this end, the crane girder 1 in the first exemplary embodiment shown has two running surfaces 13 along which the two running wheels 14 of the trolley 15 run. As can be particularly readily seen in FIG. 6, the running surfaces 13 here are configured as rails. The running surfaces or rails 13, respectively, are supported on the straight wall portions 12, which may also be referred to as a web or a lateral web, of the external wall 6. Very heavy loads may be brought to bear on the wall portions 12 in particular due to the vertical extent of the latter, without any substantial deformation of the crane girder 1 arising on account thereof. The crane girder 1 in this exemplary embodiment is in any case suspended from the two cross heads 22. In turn, the cross heads 22 by way of supports 21, which are embodied as is the case in the prior art, are supported on the running gears 23. For stabilizing, the supports 21 in the variants shown, are yet again interconnected by horizontal connections 25 above the running gears 23. The horizontal connections 25 may also be referred to as head girders. The crane 3 may be displaced in the movement directions 7 on the running gears 23 which are typically guided on rails. By way of the at least in regions outwardly bulging shape according to the invention of the crane girder 1, the aerodynamic drag of the latter is significantly reduced herein such that drive power for displacing the entire crane 3 including the crane girder 1 may be saved and less drive power is required. The crane girder 1 in the exemplary embodiment shown is elongate in the longitudinal direction 27. In the case of the gantry cranes illustrated here, the movement direction 7 thus runs so as to be orthogonal to the longitudinal extent 27.
(6) FIG. 2 shows an exemplary embodiment of a gantry crane having only one main girder, which in terms of the basic construction is similar to FIG. 1. Only the points of differentiation in relation to FIG. 1 will be discussed here. Otherwise, the narrative of FIG. 1 applies. The substantial point of difference between the exemplary embodiment according to FIG. 1 and that according to FIG. 2 lies in that a bracing known per se is provided by means of the stays 16 in FIG. 2, the crane girder 1 being additionally suspended from said bracing. This is expedient when particularly heavy loads are to be hooked to the trolley 15 and to be transported by the latter, and/or when the crane girder 1, as illustrated here, in the horizontal direction projects very far beyond the intermediate space between the supports 21, that is to say has a very large longitudinal extent in the longitudinal direction 27.
(7) The exemplary embodiment of FIG. 2 is further modified in FIG. 3. Here, the crane girder 1 according to the invention has a crane-girder portion 24 which additionally is pivotable in the vertical direction indicated by the double arrow 31. The drive for pivoting the crane-girder portion 24 in the directions according to the double arrow 31 is not plotted here. This drive may, however, be embodied as is known per se. In this exemplary embodiment according to FIG. 3, the at least one crane-girder portion 24 of the crane girder 1 may thus not only be moved in the movement direction 7, but also in the movement direction according to the double arrow 31. Nevertheless, the crane girder 1 here is also embodied such that the latter during displacement of the crane 3 including the crane girder 1 in the movement directions 7 leads to a corresponding reduction of the aerodynamic drag and thus to a reduction of the required drive power. However, FIG. 3 is also an example for a crane 3 according to the invention not necessarily having to be a gantry crane. Rather, the crane-girder portion 24 is a crane girder of an outrigger crane. The exemplary embodiment according to FIG. 3 is thus a combination of a gantry crane and an outrigger crane.
(8) The invention may of course also be implemented in the case of numerous other crane types, in particular in the case of overhead cranes and other outrigger cranes, without this having to be explicitly illustrated here in more detail.
(9) As mentioned, FIG. 4 now shows the cross section through the crane girder 1 which is employed in the exemplary embodiments according to FIGS. 1 to 3. The illustrated cross section is illustrated in a plane that is disposed so as to be normal to the respective longitudinal extent of the main girder 1. This applies also to the cross sections according to FIGS. 5 and 6, which will be explained hereunder.
(10) In the exemplary embodiment according to FIG. 4, the portions 10 and 11, forming the upper and lower boom, are each provided with an outwardly bulging shape for reducing the aerodynamic drag. The portion 10 of the external wall 6 in the operating position illustrated here points upward and ensures that rain water or any other precipitation may, if at all, only accumulate in a very small region of the crane girder 1 toward the rails or the running surfaces 13, respectively. In order for this water to be discharged too, the main girder 1 may be embodied so as to be slightly inclined in the longitudinal direction 27 thereof. The outwardly bulging shape of the portions 10 and 11, apart from reducing the aerodynamic drag, also ensures a high stability of the main girder 1 such that the latter may absorb high static forces without buckling braces or other reinforcements having to be further provided to this end in the interior of the cavity 5 enclosed by the external wall 6. Moreover, the outwardly bulging portions 10 and 11 also reduce the susceptibility of the crane girder 1 to noise generation by way of excitation of vibrations. The crane girder 1 is configured in the shape of the hollow profile 4. The external wall 6 sheathes the cavity 5. In the exemplary embodiment shown, the external wall 6 is assembled from the two already mentioned portions 10 and 11 and the straight wall portions 12. The straight wall portions 12 here in this exemplary embodiment are embodied as H girders, as are known per se from steel engineering. By way thereof, very large forces that are generated by the load bearing on the trolley 15 may be absorbed by way of the running surface 13. In the exemplary embodiment according to FIG. 4, the outwardly bulging shapes of the external wall 6, that is to say the portions 10 and 11, are configured to be rounded. Both the width extent 17 as well as the thickness extent or the height extent 18, respectively, are plotted. The width extent 17 of the external wall 16, when viewed in the direction parallel with the movement direction 7, is delimited by the first end 8 and by the second end 9. When viewed in the cross section through the crane girder, as is illustrated here, the spacing 19, measured orthogonally to the movement direction 7, between mutually opposite portions of the external wall 6, increases at least in regions from the two ends 8 and 9 of the width extent 17 of the cavity 5 toward the central region 20 of the cavity. In an exemplary manner, a few spacings 19, which are to be measured orthogonally to the width extent 17, are plotted here. The cross section of this crane girder 1 has two symmetry axes 28. One of the latter, namely the horizontal symmetry axis, runs parallel with the movement direction 7 and thus also parallel with the width extent 17.
(11) FIG. 5 shows a first alternative to the cross section according to FIG. 4. Here, the two mutually opposite upper and lower booms, that is to say the portions 10 and 11, in the cross section shown are not configured to be rounded but to be polygonal, so as to implement the outwardly bulging shape according to the invention of the external wall 6. The narrative mentioned in the context of FIG. 4 applies otherwise.
(12) FIG. 6 shows a further variant in the form of a modified embodiment of FIG. 4. Here, a longitudinal groove 29 of the external wall 6 is provided in the lower boom 11. Supply lines or the like may be routed in said longitudinal groove 29 for example. Nevertheless, it applies here too at least in portions, that a spacing 19, measured orthogonally to the movement direction 7, between mutually opposite portions of the external wall 6 increases from the two ends 8 and 9 of the width extent 17 of the cavity 5 toward a central region 20 of the cavity 5.
(13) In the exemplary embodiments according to FIGS. 4 to 6, the cross section through the main girder is embodied so as to be at least primarily approximately lenticular.
LIST OF REFERENCE SIGNS
(14) 1 Crane girder 3 Crane 4 Hollow profile 5 Cavity 6 External wall 7 Movement direction 8 First end 9 Second end 10 Portion 11 Portion 12 Straight wall portion 13 Running surface 14 Running wheel 15 Trolley 16 Stay 17 Width extent 18 Thickness extent 19 Spacing 20 Central region 21 Support 22 Cross head 23 Running gear 24 Crane-girder portion 25 Horizontal connection 26 Horizontal connection 27 Longitudinal direction 28 Symmetry axis 29 Longitudinal groove 31 Double arrow
