FR2781535A1 - ASSEMBLY DEVICE FOR METAL STRUCTURE MEMBERS - Google Patents

Abstract

The device carries out the dismountable assembly, "end to end", of members (2) of hollow configuration, belonging to two superimposable frame elements (1). This device comprises splints (5), the lower part of which forms base (7) is welded to the top of a frame (2) belonging to a lower frame element (1), the upper part of which in the shape of a stud (6) is introduced into the lower part of a frame (2) ) belonging to an upper frame element (1). The post (6) has two orthogonal transverse bores (10, 11), crossed by removable connecting pins (25, 26) .Application to the connection of mast elements (1) of a tower crane.

Description

The present invention relates to a removable assembly device,

  intended to ensure the "end-to-end" connection between members of steel truss elements. This invention applies, preferably, to the connection of mast elements of a tower crane, usable on building construction sites. The tower of such a crane is often made up of stackable mast elements, called to be frequently assembled together, or separated from each other, depending on whether one wishes to mount or raise the crane, or disassemble it. The mast elements, usually of square horizontal section, each consist of four vertical corner members, joined in pairs by a triangulation composed of horizontal and diagonal cross members. When the crane is mounted, the mast elements are arranged vertically one above the other, and they are rigidly connected to each other by their corner members. The "end to end" connections made between these corner members must ensure the continuity of the mast uprights, as well as the transmission of the longitudinal and transverse forces from the

various requests.

  The assembly between the members of two consecutive mast elements is most often carried out by splicing devices, which use connecting pieces forming double tenons, connected by axes to the lower part of the member of the element upper mast, and to the upper part of the corresponding chord of the lower mast element. A particular assembly device, described in French patent application N 2 680 813 in the name of the Applicant, uses, for the "end to end" assembly of hollow configuration members, an internal splice of suitable cross section, in particular square . The fixing of the splint on each member is ensured by two orthogonal connecting axes, which pass through bores made in the splint and in the member. The fixing of the splint to the lower part of the frame of the upper mast element is thus carried out by two removable orthogonal connecting pins. On the other hand, the fixing of the splint to the upper part of the frame of the lower mast element is carried out by two other orthogonal connecting axes which are permanently mounted, each connecting axis having a head held by a plate d 'stop, welded to a mating plate itself previously welded to the outside of the frame of the lower mast element, at a bore through which the considered connection axis. The splint is thus permanently fixed to the top of the chord of the lower mast element, by a prior assembly carried out in the factory, and the removable fixing, to be carried out on the site of use of the tower crane, relates only the connection between the splint and the member of the element

upper mast.

  This known embodiment remains relatively complex, taking into account the number of parts (connecting pins, pin stop plates, masting plates), and consequently the number of operations, necessary for the connection of the lower part of the splits with the chord of the lower mast element, when it is a question of making only a permanent rigid connection. The reliability of this link with multiple parts remains perfectible because, each part having its own reliability rate, the overall reliability of such an assembly which combines several parts is less than the reliability of each part. The axis holes, formed in the fishplate and the frame, as well as the welded matting plates, induce a heterogeneity of the stress gradient in the upper part of the frame linked to the fishplate. The connection made between the fishplate and the top of this frame is also a cause of wear and play, due to the phenomenon of "fretting corrosion". The connecting axes, and the body of the splint, are also subject to

corrosion.

  Thus, the known assembly device, mentioned here, still retains various drawbacks, which the present invention proposes to eliminate. The invention therefore aims to simplify this assembly device and make it more reliable, by reducing the number of component parts and operations to be performed, while improving the

  quality and longevity of the assembly.

  To this end, the invention relates to a dismountable assembly device intended to ensure the "end-to-end" connection between frames of lattice frame elements, the frames being of hollow configuration, the device essentially consisting of fishplates each comprising an upper part in the shape of a tenon, and a lower part in the form of a base, the upper part forming a tenon having a cross section adapted to the hollow internal section of the members, and comprising at least two offset transverse bores, and produced in orthogonal directions, which are intended to be crossed by removable connecting pins, also introduced through bores made in the lower part of a frame belonging to an upper frame element, and fitted onto the tenon, while the bottom portion in the form of a base, with a cross section larger than that of the tenon, is intended to be welded, by its underside, to the upper part of a member belonging

  to a lower frame element.

  o10 The proposed assembly device thus comprises fishplates, which on the one hand are permanently fixed, by welding, to the tops of the members of the lower frame member, and on which, on the other hand, fit the lower parts of the corresponding members of the upper frame member, removable pins ensuring a rigid, but not permanent, connection between the lower parts of the members of the upper frame member and

  the studs of the corresponding fishplates.

  In the case of the application of the invention to the connection of mast elements of a tower crane, the fishplates are welded by their caps onto the tops of the corner members of a lower mast element, and the studs of these fishplates are intended to be introduced into the lower parts of the corner members of an upper mast element. Of course, the upper mast element also plays the role of lower mast element, vis-à-vis another mast element which is attached to it.

superimposed.

  Advantageously, each splint is a molded or forged piece of weldable mechanical steel. The base of this splint can in particular be welded to the upper part of the member,

  belonging to the lower frame element, by flash welding.

  According to a preferred embodiment of the invention, the base of the splint has a central recess, in the form of a truncated warhead, which opens at the base of the base, so that this base has a section of material which decreases from continuously from its top to its base, the lateral faces of the base thus having a decreasing thickness, from top to bottom. The recess in the form of a truncated warhead makes it possible to obtain a uniform stress gradient, between the smallest section, at the base of the base,

  and the strongest section, at the top of the base.

  In a particular embodiment, the lateral faces of the splint comprise two external lateral faces, the minimum thickness of which, measured at the base of the base, is identical to that of the corresponding wings of the member, belonging to the member of the lower frame element, on which this base is welded, and two internal lateral faces, the minimum thickness of which, measured at the base of the base, is greater than that of the wings of the same member. Thus, the two outer faces constitute reference faces, intended to ensure perfect continuity with those of the frame of the lower frame element, while the two inner faces, of greater thickness, are provided to compensate for the dispersion of the transverse dimensions of the frame, in particular in the case where it is produced by welding two angles along their longitudinal edges; the inner faces of greater thickness thus guarantee an optimal welding section, in particular for sparking welding of the base on the top of the frame. The expressions “external face” and “internal faces” designate here, respectively, the two lateral faces of the base which appear on the external side of the frame element concerned (such as mast element), and the two other lateral faces of the base which appear on the inner side of the frame element concerned, the base having a total of four lateral faces, corresponding to the four sides

of its square horizontal section.

  The upper face of the base of the splint advantageously forms, for the inner wings of the member belonging to the upper frame element, a bearing surface of width

  greater than the thickness of the inner wings of said member.

  According to an advantageous additional arrangement, the lug of the splint comprises, in its zone of connection to the base, a peripheral groove of rounded profile, connecting to the upper face of the base which serves to support the terminal lower face of the frame belonging to the lower frame element. This peripheral groove makes it possible to reduce the stress concentration coefficient, in the connection zone between the lower part of the post and the part

upper side of the splint.

  Overall, the invention thus provides an "optimized" assembly device, which comprises in particular, compared to the known devices mentioned above, the following advantages: - Simplification of the structure of the lower part of the splint , by reducing the number of component parts (elimination of connecting pins, masting plates, pin stop pieces), and consequently reducing the number

  required manufacturing and binding operations.

  - Securing the assembly, due to the reduction in

number of component parts.

  - More homogeneous stress gradient in the upper part of the frame belonging to the lower frame element, on which the splint is welded, by

  elimination of axle holes and matting plates.

  - Excellent recovery of compression forces by the machined upper face of the base, in particular because it has, on the inside, a width greater than the thickness of the inner wings of the upper member, this

  which mitigates any risk of dispersion.

  - Possibility of welding the fishplates on steel frames of heterogeneous characteristics, by the spark welding process which does not require any particular preparation of the surfaces to be welded, this welding process can also be automated so as to obtain a quality

constant and reproducible.

  - Reduction of wear and play by "fretting corrosion", by elimination of the connection by axes of the lower part of the splint with the upper part of the member belonging

  to the lower frame member.

  - Elimination of corrosion of the lower part of the splint.

  - Possibility of surface treatment (painting) of the part

  interior of the frame in a single operation.

  In any case, the invention will be better understood using the

  description which follows, with reference to the attached schematic drawing

  showing, by way of example, an embodiment of this device for assembling steel truss frame members, applied to the connection of mast elements of a tower crane: Figure 1 is a perspective view showing two mast elements of a tower crane (one being shown partially), the members of which are assembled by the device of the present invention; Figure 2 is a perspective view showing, on a larger scale, the splice of this assembly device; Figure 3 is a vertical sectional view of the junction area

  of two frames, assembled by the device of the present invention.

  Figure 1 shows two consecutive elements 1, superimposed, belonging to a tower crane mast. Each mast element i has a horizontal section of generally square shape, and it comprises four corner members 2, arranged vertically and joined in pairs, on the four lateral faces of the mast element 1, by a

  triangulation composed of horizontal crosspieces 3 and diagonals 4.

  Each frame 2 is advantageously formed by two angles joined by welding, along their longitudinal edges, so as to constitute a tubular profile of substantially square horizontal section, the orientation of which is similar to that of the square section of the element of

mast 1.

  The members 2 of the mast elements 1 thus have open upper and lower ends, and they are assembled by means of fishplates 5, belonging to the removable assembly device forming the subject of the invention. Each splint 5, shown in detail in FIG. 2, is a molded or forged piece of weldable mechanical steel, which comprises an upper part 6 in the shape of a stud, and a part

lower 7 in the form of a base.

  The upper part 6 forming a tenon has a horizontal section of generally square shape, its upper end having a central tip 8 and chamfers 9. This upper part 6 of the splint 5 has two identical and superimposed bores 10 and 11, produced in two orthogonal horizontal directions. The geometric axis of the lower bore 10 intersects the two opposite vertical faces 12 of the stud 6 perpendicularly, from one face to the other, and the geometric axis of the upper bore 11 intersects the other two opposite lateral faces perpendicularly. 13, from one side to the other. The geometric axes of the two bores 10 and 11 are vertically offset, one relative to the other, by a height greater than the diameter of these bores. Each of the bores 10 and 11 has, in the direction of its geometric axis, two successive parts of slightly distinct diameters, separated from each other by an inner annular shoulder,

14 and 15 respectively.

  The tenon 6 has, on one of its vertical edges, a clearance forming a flat 16, intended to receive identification inscriptions of the joint 5 and its characteristics, with a view to its

"traceability".

  Finally, the pin 6 has at its base, in its zone of connection to the base 7, a peripheral groove 17 of rounded profile, whose shape and dimensions make it possible to reduce the stress concentration coefficient at the connection between the lower part of the

  tenon 6 and the upper part of the base 7.

  The base 7 has a horizontal section of generally square shape, larger than the section of the stud 6, and it has a central recess 18, which opens at the base of this base 7. The recess 18 of the base 7 has the form d 'A truncated warhead, so that this base 7 has a horizontal section of material which progressively passes from a maximum value, at the top of said base 7, to a minimum value,

the base of this base 7.

  The horizontal upper face 19 of the base 7, surrounding the groove 17, is erected and constitutes a perfectly flat bearing surface for the terminal lower face of the frame 2 of the upper mast element 1, itself erected (see also figure 3). It will be noted that, on the side of the two inner wings of this frame 2, the upper face 19 of the base 7 has a width L greater than the thickness of the inner wings

of said member 2.

  The horizontal lower face 20 of the base 7 is welded, in particular by sparking, to the upper upper face of the frame

  2 of the lower mast element 1.

  The four lateral faces of the base 7 comprise two external faces 21 (that is to say the faces which appear on the external side of the mast element 1), and two internal faces 22. Taking into account the ogive shape of the recess 18, all of these side faces 21 and 22 have a

  decreasing thickness, from top to bottom.

  The two outer faces 21 of the base 7 have, at their base, a thickness e identical to that of the corresponding outer wings of the frame 2 of the mast element 1. These outer faces 21 constitute reference surfaces, arranged in perfect continuity with the

  corresponding surfaces of the frame 2 of the mast element 1.

  The two internal faces 22 of the base 7 have, at their base, a thickness E greater than that of the corresponding internal wings of the frame 2 of the mast element 1. This greater thickness E makes it possible to compensate for the dispersion of the transverse dimensions of the membrane 2, in particular in the case where it is formed by the union of two angles, and it guarantees an optimal welding section for sparking welding of the base 7 on the upper end face of the

  frame 2 of the lower mast element 1.

  Four fishplates 5 thus being welded by their caps 7 to the tops of the members 2 of the lower mast element 1, a mast element 1 is obtained provided, at its top, with four tenons 6 facing towards

the top.

  When mounting the crane, the upper mast element 1 is brought above the lower mast element 1, so that the four studs 6 of this lower mast element 1 engage in the lower ends of the four 2 corresponding frames of the upper mast element 1. The lower end face of each frame 2 of the upper mast element 1 is supported on the upper face 19 of the base 7 of the corresponding splint 5, welded to a

  frame 2 of the lower mast element 1.

  When the lower ends of the members 2 of the upper mast element 1 are thus fitted onto the tenons 6 of the ribs 5 of the lower mast element 1, the bores 10 and 11 of these tenons 6 are aligned with corresponding bores 23 formed in the wings of the members 2 of the upper mast element 1, towards the lower end of these members 2, o mating plates 24

  serving as reinforcements are still welded around the bores 23.

  The connection between the tenon 6 of a splint 5, and the lower end of the corresponding frame 2 of the upper mast element 1, is produced by means of two connecting pins 25 and 26 (see also Figure 1) . The first connecting axis 25 is introduced into the lower bore 10 of the stud 6, and it also passes through the bores 23 of the membrane 2, then aligned with the bore 10. The second connecting axis 26, orthogonal to the first, is introduced into the upper bore 11 of the stud 6, and it also passes through the

  bores 23 of frame 2, then aligned with bore 10.

  Each connecting axis 25 or 26 successively comprises, from one end to the other: an enlarged head, a cylindrical part of larger diameter (corresponding to the part of larger diameter of the bore 10 or 11 of the stud 6) , a cylindrical part of smaller diameter (corresponding to the part of smaller diameter of the bore 10 or 11), and a frustoconical end part. Removable members are also provided for immobilization in translation and possibly in

  rotation of each connecting axis 10 or 11. A more detailed description

  of these provisions can be found in the French patent application

cited above NO 2 680 813.

  Once the assembly has been carried out, the recess in the form of a truncated warhead 18 of the base 7 makes it possible to obtain a uniform stress gradient, between the smallest horizontal section (at the base of the base) and

  the strongest horizontal section (at the top of the base).

  Of course, in the context of mounting a tower crane, the same assembly operations are repeated for all the elements of

  superimposed mast, each mast element 1 comprising, as described above

  above, four fishplates 5 whose bases 7 are welded to the tops of the

  four members 2 of this mast element 1.

  To separate two superimposed mast elements 1 on the site, the connecting pins 25 and 26 are dismantled, after removal of their immobilization means, which allows the lifting of the members 2 belonging to the upper mast element 1, and their dislocation relative to the pins 6 of the fishplates 5, which remain in place at

  tops of the members 2 of the lower mast element 1.

  It goes without saying that the invention is not limited to the sole embodiment of this device for assembling lattice steel frame members, which has been described above by way of example; on the contrary, it embraces all of the variant embodiments and applications respecting the same principle. In particular, we would not depart from the scope of the invention: - by modifying the detail of the shapes of the splint - by carrying out the welding of the base of the splint on the upper part of the frame of the lower mast element by any other suitable welding method, such as electric arc welding, resistance welding or laser welding; - by applying the device to any assembly of frames of steel truss elements, in

  technical fields other than that of tower cranes.

Claims (7)

  1 - Removable assembly device, intended to ensure the "end to end" connection between members (2) of steel truss elements (1), the members (2) being of hollow configuration, characterized in that '' consists essentially of fishplates (5) each comprising an upper part (6) in the shape of a stud, and a lower part (7) in the form of a base, the upper part forming a stud (6) having a cross section adapted the hollow internal section of the members (2), and comprising at least two transverse bores (10,11) offset, and produced in orthogonal directions, which are intended to be crossed by removable connecting pins (25,26), also introduced through bores (23) formed in the lower part of a frame (2) belonging to an upper frame element (1), and fitted on the stud (6), while the lower part in the form of a base (7), of cross section larger than that of the stud (6), is intended to be welded, by its lower face (20), on the upper part of a frame (2) belonging to an element of lower frame (1).   2- A device for assembling lattice steel frame members according to claim 1, characterized in that the base (7) of the splint (5) has a central recess (18), in the form of a truncated warhead, which opens at the base of the base (7), so that this base (7) has a section of material which decreases from its top to its base, the lateral faces (21, 22) of the base (7) thus having a thickness decreasing, from top to bottom.   3 - Device for assembling lattice steel frame members according to claim 2, characterized in that the lateral faces of the base (7) of the splint (5) comprise two external lateral faces (21), the thickness of which minimum (e), measured at the base of the base (7), is identical to that of the corresponding wings of the frame (2), belonging to the lower frame element (1), on which this base (7) is welded , and two inner side faces (22), the minimum thickness (E), measured at the base of the base (7), is   greater than that of the wings of the same member (2).   4- Device for assembling structural members   metallic according to any one of claims 1 to 3, characterized in   that the upper face (19) of the base (7) of the splint (5) forms, for the inner wings of the frame (2) belonging to the upper frame element (1), a bearing surface of width (L) greater than thickness   (e) inner wings of said member (2).   - Device for assembling structural members   wire mesh according to any one of claims 1 to 4,   characterized in that the lug (6) of the splint (5) comprises, in its zone of connection to the base (7), a peripheral groove (17) of rounded profile, connecting to the upper face (19) of the base (7) which is used to support the terminal lower face of the frame (2) belonging to   the upper frame element (1).   6 - Device for assembling structural members   metallic lattice according to any one of claims 1 to 5,   characterized in that the splint (5) is a molded or forged piece of steel mechanical weldable.   7 - Device for assembling a frame member   wire mesh according to any one of claims 1 to 6,   characterized in that the base (7) of the splint (5) is welded to the upper part of the frame (2), belonging to the structural element (1)   lower, by flash welding.   8 - Device for assembling structural members   wire mesh according to any one of claims 1 to 7,   characterized in that it is applied to the connection of mast elements (1) of a tower crane, the ribs (5) being welded by their caps (7) to the tops of the corner members (2) of a lower mast element (1), and the studs (6) of these ribs (5) being designed to be introduced into the lower parts of the corner members (2) of a mast element (1) superior.