The invention relates to a method for creating a bracket for a fastening element on a beam according to the preamble to patent claim 1 , and a device on a beam according to the preamble to patent claim 5.

State of the art.

Fastening of components to a load-bearing beam structure often means that the beam is subject to the action of relatively large forces and that strong and stable fastening is therefore necessary. This often occurs in heavy vehicles, e.g. buses, in which various components have to be fastened to beams which form part of the load-bearing body structure of the vehicle.

On l-section or U-section beams it is relatively easy to create brackets by making holes in the beams into which bolts are pressed or screwed firmly, sometimes using locknuts.

On hollow beams, usually rectangular beams, it is more difficult to create simple brackets because these beams have relatively small wall thicknesses which do not tolerate large clamping forces. Subjecting such a beam to large clamping forces may well cause the whole beam to collapse. One way of arranging a bracket on such a beam is to arrange a clip around the beam so that it forms the actual bracket, but if the clip is tightened with too much force it may well constrict the whole beam at the bracket point. A further disadvantage is that it is difficult to arrange the bracket at a predetermined position without resorting to special arrangements for the purpose.

Another commonly used method is to drill two mutually concentric holes in opposite sides of the beam, followed by inserting a sleeve through the the holes and welding it firmly to each to both walls of the beam. A bolt or the like can then be pressed or screwed in firmly, sometimes using locknuts. Here again there is

unfavourable transmission of forces to the rectangular beam, since bending stresses may well occur in the walls of the beam in a region where they are relatively weak.

An alternative solution is to weld the sleeve at only one end and let the other end abut against the inside of the opposite wall of the beam, but this may lead to manufacturing problems, since it is difficult to check that the sleeve has not been inserted obliquely or has been inserted not far enough to abut against the opposite wall, which may lead to still less favourable fastenings from the force transmission point of view.

Such force transmission is of course undesirable in applications where the connection is subject to large loads, as in fastenings of heavy components in an environment subject to vibration, e.g. in heavy vehicles.

Objects of the invention.

One object of the invention is to provide a method for creating a bracket for a fastening element on a beam according to the preamble to patent claim 1 , which method provides a relatively inexpensive, easy and safe way of creating a bracket which is favourable from the force transmission point of view, is stable and lacks the abovementioned disadvantages. The bracket has also to be capable of being positioned at a predetermined location on the beam.

Accordingly the method according to the invention is distinguished by the features indicated in the characterising part of patent claim 1. Removing part of the beam and welding a sleeve firmly into the resulting recess makes it possible for a bolt or similar fastening element to be arranged with its central axis in the surface plane of the beam. This means that the walls of the beam can absorb the forces from the bolt without risk of the beam collapsing.

Patent claims 2-4 indicate advantageous detailed embodiments of the method including inter alia the use of a rectangular beam and methods for arranging a number of brackets on the same beam.

Another object of the invention is to create a device on a beam according to the preamble to patent claim 5, which device constitutes a bracket with the characteristics and advantages mentioned above.

Accordingly the device according to the invention is distinguished by the features indicated in the characterising part of patent claim.

Patent claims 6-10 indicate advantageous detailed embodiments including inter alia the use of a rectangular beam and devices with a number of brackets on the same beam.

Further features and advantages of the invention are indicated by the accompanying description of an embodiment with reference to the attached drawings.

List of drawings

Figure 1 shows a cross-section l-l according to Figure 2 of a rectangular beam. Figure 2 shows a side view of the beam according to Figure 1. Figure 3 shows a view from above of the beam according to Figure 1. Figure 4 shows a cross-section IV-IV according to Figure 5 of the beam after the bracket has been arranged.

Figure 5 shows a view according to Figure 2 after the bracket has been arranged. Figure 6 shows a view according to Figure 3 after the bracket has been arranged.

Description of an embodiment.

The beam depicted in the drawings may for example form part of a load-bearing frame or body for a heavy vehicle, e.g. a bus, in which it is desired to fasten components by bolted connections. The beam is a rectangular beam 1 which incorporates four walls 2-5 which surround an internal space 6. Each wall 2-5 has substantially planar outside surfaces 7-10 and inside surfaces.

The beam has to be provided with brackets for bolts. The method according to the invention for providing the beam 1 with such brackets is described below. The drawings show a section of the beam incorporating two brackets.

The first step is to remove, preferably by milling or some other cutting form of machining, a fragment of the beam 1 so as to form an aperture 11 to the internal space 6. The aperture 11 consists of a transverse section 12 across the beam 1 , i.e. across the whole width of a first wall 2

(see Fig. 3). The fragment cut away also includes parts of the adjacent walls 3,5 so that semicircular recesses 13,14 are formed in the latter (see Fig. 2).

The next step is to apply a sleeve 15, preferably cylindrical with a hole 17 running through it, so that the aperture 11 is completely covered (see Figs. 5,6). The sleeve 15 is placed so that its central axis 16 lies in the same plane as the outside surface 7 of the first wall 2. The sleeve 15 is then welded firmly to the beam 1. It is advantageous for the material thickness of the sleeve 15 to be of the same order of magnitude as that of the wall 2.

A bolt can then be fixed in the hole 17 of the sleeve 15. It is advantageous for the component which is to be fastened to the beam to be provided with a corresponding hole running through it. This will make it possible to use an ordinary bolted connection with locknuts. This means that relatively long bolts can be used, thereby allowing the bolted connection to be tightened with corresponding large clamping forces. In alternative embodiments the hole 17

may be threaded inside or a locknut may be used, and further possible alternatives are to use contact adhesive or press fitting. The sleeve 15 may also be of some other shape.

If it is desired to fix the component at a predetermined distance from the beam 1 , the sleeve 15 may be made longer than the width of the beam 1 (see Figs. 4,6) where the component is intended to be fastened against the end plane 18 of the sleeve. This is advantageous for ensuring that the component abuts only against the sleeve 15 and not against the wall 5 of the beam, thereby ensuring that the adjacent walls 2,4 are not subject to the action of any unfavourable forces which might constrict the beam.

As the longitudinal axis of the fastening element is thus arranged in the same plane as the outside surface 7 of the wall 2, no bending stresses are imposed on the adjacent walls 3,5 which are perpendicular to the longitudinal axis of the fastening element, so the result is a strong and robust solution.

The invention also makes it possible to use threaded connections at certain fastening points where welded connections were used previously. This is advantageous in applications where components for a product are shipped to another location for final assembly, since the assembly of a threaded connection requires no special comprehensive training or complicated assembly equipment in the form of welding units. The beam need not be of the rectangular type but may of a number of different shapes. It also need not be uniform in the longitudinal direction, and not all the walls need be planar. What is essential to being able to achieve a favourable force configuration is that the bracket is arranged on a relatively planar wall or section of wall. Two or more brackets may of course be arranged on the same beam and on different walls. If two or more walls are used, it is advantageous for them to be in parallel planes, e.g. on opposite sides of a rectangular beam, otherwise there will be forces in different directions resulting in a less favourable force configuration. Brackets may with advantage be arranged on opposite sides

at the same location in the longitudinal direction of the beam. On beams with two or more brackets it is advantageous to create all the apertures first and only thereafter to fasten the sleeves. Here too, two or more brackets for the same component should be arranged so that the respective sleeve end planes all lie in the same plane so as to form one fastening plane for the component.

It is also possible to fix the fastening element to the sleeve before the latter is welded to the beam, although in most cases this is probably impractical from the assembly point of view.

A beam provided with brackets by the method described above forms the device according to the invention, whose features are indicated in the above description