FR2773550A1 - BOOM ELEMENT FOR TOWER CRANE - Google Patents

Abstract

This lattice jib element comprises members (1, 2) which define two by two of the planar faces, the members being interconnected, in these faces, by pieces forming a triangulation. According to the invention, these parts are constituted by triangulation modules (9) each made from a cut and optionally bent sheet. Each triangulation module (9) comprises at least two rectilinear segments (10, 11) connected to one another forming an angle (12), the module having for example a "V" configuration. This module (9) is assembled by welding to the frames (1, 2), this to the free ends of its segments (10, 11) as well as to its corner zone (12). The frames (1, 2) are also advantageously made from cut and folded sheets.

Description

The present invention relates to the field of tower cranes and it

  relates more particularly to a

  lattice boom element for tower crane.

  In a generally known manner, a tower crane boom is constituted by a succession of boom elements, aligned and assembled to each other so as to constitute a boom of the desired length. Each jib element is a structure of the truss beam type, of triangular, rectangular or trapezoidal section, which comprises members defining two by two of the planar faces, the members being connected together, in these faces, by pieces of the bar type.

forming a triangulation.

  In the majority of current tower cranes, the lattice boom elements are made from open or closed commercial sections, such as tubes

  of round or square section. This type of embodiment does not allow the boom elements to be optimized, in particular from the point of view of their weight and construction operations.

  Known in certain tower cranes, lattice jib elements of triangular section, the triangulation of which is made from folded round section profiles. In addition to the general drawback

  cited above, this particular embodiment presents a real manufacturing difficulty.

  A tower crane is also known whose lattice jib elements are composed of an upper frame made of folded sheet metal, of lower tubular members made of folded sheet metal, and of diagonals

also in folded sheet.

  Furthermore, there are tower cranes which have mast elements whose members are made of folded sheet metal with variable section over the height of these elements, at least as regards the rear members, the triangulation of the faces of the elements of mast

  being produced by bar diagonals.

  Finally, by French patent application 2478606, another tower crane is known, the mast elements of which have a triangulation produced by solid plates, of polygonal shape and in particular triangular or trapezoidal, these plates being assembled to members also produced in folded sheet. This embodiment has the drawback of an overabundance of material for triangulation, hence an unnecessarily high weight and cost. Note also that the known solutions for tower crane masts cannot be directly transposed to the jibs of the same cranes, because the types of forces15 to which the jibs are subjected do not correspond

to the stresses on the masts.

  In consideration of the known prior techniques for the production of jib elements, and where appropriate mast elements for tower cranes, the present invention aims to provide a jib element for tower crane, the structure and method of obtaining allow an optimization in particular in terms of reduction in the weight of the element, for equal or even improved mechanical characteristics, while simplifying and rationalizing the manufacture

industrial of this element.

  To this end, the present invention essentially relates to a lattice jib element for a tower crane, comprising members defining two by two of the flat faces, and parts connecting the members together in each of these faces to form a triangulation. , the jib element being characterized in that said parts are constituted by triangulation modules each made from a cut sheet and optionally folded, each triangulation module comprising at least two straight segments connected one to the other by forming at least one angle, this triangulation module being designed to be assembled to the frames, in particular by welding, at the free ends of its segments and at its corner area (s). The different segments of the triangulation modules can be of constant section or have, at least for some of them, a section

  variable over the length of the segment concerned.

  Preferably, each triangulation module is produced from a sheet folded in the longitudinal direction of the segments of this module, or at least of some of said segments, so as to constitute

segments shaped into angles.

  Advantageously, each triangulation module can comprise, at the free ends of its segments and in its corner area or areas, a cutout creating a lateral clearance, facilitating access for welding of

  this triangulation module on the members.

  Depending on the number and arrangement of the segments, the triangulation modules can have various configurations. In the simplest embodiment, each triangulation module has a "V" configuration, resulting from two segments connected in one area

single angle.

  According to a variant, each triangulation module has a configuration in "M", resulting from three

  segments connected in a common corner area.

  According to another variant, each triangulation module has a "Z" configuration, resulting from three segments successively connected in two corner zones. Preferably, the members of the jib element are, like the triangulation modules, made from cut and folded sheets. These members are advantageously of variable section over the length of the jib element and, more particularly, of section

  decreasing from one end to the other of the member.

  A jib element is thus obtained resulting from the assembly of at least three members, and series of triangulation modules arranged in the different faces defined by the members. Insofar as the members are, like the triangulation modules, made of cut and folded sheet metal, there is great freedom of design in the choice of the shape of the upper member (s) and lower members, as well as the thickness of

the constituent sheet.

  This design freedom also exists, of course, for the triangulation modules which can thus be adapted to the optimal recovery of forces. In particular, the principle of the invention allows, for the different segments of a triangulation module, the choice of a cross-section of surface and of quadratic moment suitable and possibly variable, for example by producing segments of variable cross-section by a appropriate cutting of the sheet, or by choosing to make segments of folded or unfolded sheet; bending here makes it possible, in particular, to vary the quadratic moment, while the shape of the cut makes it possible in particular to distribute the material of the segments of the triangulation modules so as to eliminate the lateral offset of the neutral fibers of these modules relative to the neutral fiber of the members. The principle of the invention also allows a free choice of the shape of the modules: variable angle between the segments, segments of different lengths and / or sections, "V", "M" 'or "Z" shapes as defined above, adaptation of the shapes and dimensions of the corner zones used for the production of welded connections with the members, this to solve the problems of fatigue and to control

  the eccentricities of the neutral fibers.

  It should also be noted that the entire boom can be produced from a flat product (sheet steel)

  available in all grades, including steels with high elastic limit which is especially important for5 members.

  Finally, the invention makes it possible to optimize the management of the production of the jib elements: by allowing this production from the supply of a single type of material, in the form of a flat product; by bringing10 a significant reduction in the number of parts required, since a single triangulation module achieves the equivalent of two or more traditional diagonals, each segment of a module corresponding to a diagonal; and limiting the operations of

  transformation to three types of operations: cutting, folding and welding, which can be automated.

  The invention will be better understood using the following description, with reference to the schematic drawing

  annexed representing, by way of examples, an embodiment of this jib element for tower crane, as well as some variants: Figure 1 is an overall plan view from above of a jib element in accordance with present invention; Figure 2 is a plan view from below of this boom member; Figure 3 is a side view of the boom member of Figures 1 and 2; Figure 4 is a cross-sectional view of

  the arrow element, according to IV-IV of FIG. 3.

  Figure 5 is a cross-sectional view of the boom member, along V-V of Figure 3; Figure 6 is a front view of a triangulation module of this boom element, shown before folding; Figure 7 is a perspective view of the triangulation module of Figure 6, in its final state; Figure 8 is a perspective view of a variant of the triangulation module; Figure 9 is a perspective view of another

  variant of this triangulation module.

  Figures 1 to 5 show a jib element for tower crane, of triangular section. The boom element comprises an upper member 1, and two lower members 2 and 3, parallel to each other, which define, two by two, two inclined lateral faces, symmetrical with respect to the longitudinal median plane 4 of the boom member, and a lower face, in particular horizontal. The upper chord 1 is made of cut and folded sheet metal, in particular of steel with an elastic limit greater than 360 N / mm2. The upper member 1 has an inverted "V" section, this section being continuously variable over the length of the member and, more particularly, decreasing from one of its ends to the other end (see FIG. 3, and

also compare Figures 4 and 5).

  The two lower members 2 and 3, forming a raceway for a carriage, are also made of cut and folded sheet metal, in particular of steel with an elastic limit greater than 360 N / mm2. Each lower member 2 or 3 has a rectangular section, continuously variable over the length of this member and, more particularly, decreasing in height from one end to the other end (see FIG. 3, and

also compare Figures 4 and 5).

  At the ends of the three frames 1, 2 and 3 are provided connecting ends, for the assembly of the jib element considered with other similar jib elements. The upper frame 1 thus carries, at one end, a connecting end 5 forming a yoke and, at

  the other end, a connecting end piece 6 forming a tenon.

  Likewise, the lower members 2 and 3 each carry, at their respective ends, connecting end pieces 7 and 8. The two lateral faces and the lower face of the jib element are each constituted by a series of modules of triangulation 9. In the example considered, each triangulation module 9 comprises two rectilinear segments 10 and 11 connected to each other at 12 at an angle, so that the module

  triangulation 9 has a "V" configuration.

  Each triangulation module 9 is made of cut sheet metal then folded, Figure 6 showing the shape of the cut sheet before folding, while Figure 7 shows the final configuration of the module

  triangulation 9, as obtained after folding the sheet.

  The sheet metal is folded, on the first segment 10, along a longitudinal fold line 13 and, on the second segment 11, along a longitudinal fold line 14. After folding, the two segments 10 is

  11 thus have an angle conformation.

  At the free ends of the two segments 10 and 11, as well as in the corner area 12, the sheet metal has special cutouts 15, 16, 17 and 18, in the shape of an angle

  re-entering, which define lateral clearances.

  As further shown in FIGS. 6 and 7, more particularly for the second segment 11 near its free end, the segments of the triangulation module 9 can have a variable section (with narrowing

  or widening) along their length.

  Considering more particularly the lateral faces of the jib element (see FIG. 3), the mounting of the triangulation modules 9 is such that the corner area 12 of each module 9 is connected to the upper chord 1, while the ends free of the two segments 10 and 11 of each module 9 are connected to a lower chord, such as chord 2. A number of triangulation modules 9 are thus successively mounted, along the length of the jib element, the end of the second segment 11 of a module 9 being close to the end of the first segment 10 of the

next module 9.

  The fixing of each triangulation module 9 on the members 1, 2, 3 is carried out by welding. In particular, the corner area 12 of each module 9 has a width adapted to the welded connection with one of the two wings of the upper member 1. The lateral clearances 15, 16, 17 and 18, located at the connections of each triangulation module 9 with the members 1, 2, 3, allow easy access for the

welding torch.

  According to the same principle, for the constitution of the underside of the boom element, other triangulation modules 9 are mounted and welded between the two

  lower members 2 and 3 (see Figure 2).

  In the example described so far, referring to Figures 1 to 7, each triangulation module 9 has two segments 10 and 11 of unequal lengths. The length ratios of the two segments 10 and 11 can be modified, and in a variant not shown, these two segments 10 and 11 are of equal length, the module of

  triangulation thus being made symmetrical.

  Figures 8 and 9 illustrate other variants.

  FIG. 8 shows a triangulation module 9 ′ in the general shape of "M", which comprises two rectilinear segments 10 and 11 connected together in a corner area 12, and a third rectilinear segment 19, located between the two preceding segments 10 and 11 and also connected to the corner area 12, here relatively elongated. The third segment 19 is not folded longitudinally, and thus retains a flat configuration. FIG. 9 shows a triangulation module 9 "in the general shape of" Z ", which comprises a first rectilinear segment 20 folded longitudinally, a second rectilinear segment 21 connected to the first in a first corner area 22 and a third rectilinear segment 23 connected

  to the previous one in a second corner area 24.

  The triangulation modules 9 ′ and 9 ", according to these variants, are also produced from sheets

cut and folded.

  As is obvious, and as is clear from the above, the invention is not limited to the sole embodiments of this jib element for tower crane and of its components which have been described above, with title of examples; on the contrary, it embraces all of the variant embodiments and applications respecting the same principle. In particular, one would not depart from the scope of the invention: - by modifications of the shapes of the triangulation modules, such as modification of the angle of modules in "V", or constitution of modules in "W ", or a combination of the forms previously described; - by using the same triangulation modules associated with conventional members (and not made of cut and folded sheet); - by an application of the invention to crane jibs of non-triangular, but rectangular or trapezoidal section, in which case the triangulation modules are arranged on the four faces of each jib element, namely the two lateral faces, the face

upper and lower side.

Claims (7)

CLAIMS i - Lattice boom element for tower crane, comprising members (1,2,3) defining two by two of the plane faces, and parts connecting the members together in each of these faces to form a triangulation, characterized in that said parts are constituted by triangulation modules (9,9'9 ") 10 each made from a cut sheet and optionally folded, each triangulation module comprising at least two straight segments (10,11;, 11.19; 20.21.23) connected to each other by forming at least one angle (12; 22.24), this triangulation module (9, 9 ', 9 ") being provided for being assembled to the members (1,2,3), in particular by welding, to the free ends of its segments (10,11; 10,11,19; 20, 23) as well as to its corner area (s) (12; 22 , 24).   2 - Boom element for tower crane according to claim 1, characterized in that the segments (10,11; 10,11,19; 20,21,23) of the triangulation modules (9,9 ', 9 ") have, at least for some of them,   a variable section along the length of the segment concerned.   3 - Boom element for tower crane according to claim 1 or 2, characterized in that each triangulation module (9,9 ', 9 ") is made from a sheet   folded (in 13,14) in the longitudinal direction of the segments (10, 11) of this module, or of some of said segments (20,23), so as to constitute segments30 shaped as an angle.   4 - Boom element for tower crane according to any one of claims 1 to 3, characterized in that   each triangulation module (9.9 ′, 9 ") comprises, at the free ends of its segments (10,11) and in its ou35 its corner zones (12; 22, 24), a cutout (15,16, 17.18) creating a lateral clearance, facilitating access for welding of this triangulation module (9.9 ', 9 ") on the frames (1,2,3).   - Boom element for tower crane according to one   any one of claims 1 to 4, characterized in that   each triangulation module (9) has a "V" configuration, resulting from two segments (10,11)   connected in a single corner area (12).   6 - Boom element for tower crane according to one   any one of claims 1 to 4, characterized in that   each triangulation module (9 ') has an "M" configuration, resulting from three segments   (10,11,19) connected in a common corner area (12).   7 - Boom element for tower crane according to one   any one of claims 1 to 4, characterized in that   each triangulation module (9 ") has a" Z "configuration, resulting from three segments (20,21,23) successively connected in two corner zones (22.24).   8 - Boom element for tower crane according to one   any one of claims 1 to 7, characterized in that   its members (1,2,3) are, like the triangulation modules (9,9 ', 9 "), made from sheets cut and folded.   9 - Boom element for tower crane according to claim 8, characterized in that the frames (1,2,3) of cut and folded sheet are of variable section over the length of the boom element, and more particularly of decreasing section of one end   (5,7) at the other end (6,8) of the frame (1,2,3).