Title: Mounting/assembly element for assembling workpieces, particularly overlapping plates and/or components.

The present invention relates to a mounting/assembly element for use in the assembly of items, particularly overlapping plate parts and/or components, and comprising a rivet bush with a first end and a second end, and where the first end comprises a deformable zone for insertion through holes lying over each other in the items, and where in the rivet bush there is housed a draw-rod, the first end of which comprises a draw-head with a larger diameter than the draw-rod and a break zone above the draw-head which is housed in the deformable zone of the rivet bush, and where the second end of which extends up over the second end of the rivet bush, and where the second end of the rivet bush comprises an external thread on which there is provided a cooperating nut, said mounting/assembly element being intended for fastening by use of a drawing tool engaged in the draw- rod for breakage in the break zone.

Such a mounting/assembly element is known from DE 39 02 226 A1 , where there is disclosed a mounting/assembly element comprising a rivet bush, the insertion end of which comprises a deformation zone, in which rivet bush there is provided a draw-rod comprising a break zone, where the draw-rod by being drawn upon by a drawing tool carries out a deformation of the rivet bush ^' s deformation zone, and with continued traction a breakage occurs in the break zone, so that the pointed end of the draw-rod remains housed inside the rivet bush, the outer walls of which are pressed against the walls of the parts which the mounting element holds assembled. When the mounting/assembly element is mounted, i.e. after the draw-rod has broken in the break zone, the break zone of that part of the draw-rod which is connected to the draw-head will be placed in the rivet bush, outside the end of the rivet bush opposite the deformation zone.

The special aspect of said mounting element is that the end of the rivet bush, opposite the deformation zone, extending from the surface of the parts in which the fastening element is mounted, has an external thread on which there is provided a cooperating nut which constitutes the element ^' s contact surface against a surface of a relevant item. The nut can thus be loosened, whereby the item which is fastened by means of one or more of said fastening elements, can be dismounted and mounted with a commonly-known hand tool, without the necessity of having to remove/drill-out the rivet bush, and without the necessity of having access to that part of the rivet bush which is fastened in the underlying construction i

part. Furthermore, the advantage is that the bolt can be used as a form of security- sealing, in that an attempt to loosen the bolt will leave score/scratch marks in the surface of the item fastening by the mounting element.

However, the fastening element disclosed in DE 39 02 226 A1 has the weakness that the rivet bush, in the dismounting and mounting of the nut, can sometimes not withstand the turning moment which is applied to the nut, in that the rivet bush simply turns around with the nut when the turning moment exceeds the fric- tional force which is established by the fastening of the rivet bush in a relevant hole in the construction in which the mounting element forms part. To counter this, the external side of the rivet bush ^' s deformation zone has been provided with a grooving with the object of improving the anchoring of the rivet bush in a hole arranged in a relevant item/plate part, so that the ability of the rivet bush to withstand the turning moment is increased.

This, however, has proved to be inadequate, and in the use of said known mounting element it has thus not been possible to establish sufficient resisting moment to be able to dismount and remount the nut on the element without the rivet bush turning around in its seating in the lowermost construction part. Nor has the said mounting element found application with more strength-demanding fastenings. Moreover, said mounting element will not be suitable for fastening/mounting of parts on locations where vibrations arise, e.g. on machine parts where use is sometimes made of locking fluid to ensure that the nut remains in the preferred position.

From US 4 560 312 B (James H. Grady) there is known a fastening element comprising a threaded draw-rod, the end of which opposite the thread comprises a draw-bar and a bush comprising a deformable zone in the one end and a contact flange in the other end, for inserting through overlapping holes in construction elements which are to be assembled, where the flange is intended for contact respectively with a facing surface of the construction elements, and a nut on the threaded draw-rod, arranged for the tightening of the draw-bar so that the deformation zone of the bush is deformed by the draw-bar, whereby the flange is pressed against the facing surface of the construction elements which are hereby assembled. In order to carry out the tightening of the nut, it is necessary to be able to secure the draw-rod, wherefore in the threaded end of the draw-rod there is a recess to accommodate a cooperating insertion too, intended as a counter-hold for turning moments which arise with the tightening of the nut on the draw-rod against

the flange on the bush, for deformation of the bush ^' s deformable zone, on the opposite side of the construction elements. The nut can be dismounted by use of the insertion tool.

It is important to understand that the mounting element disclosed in US 4 560 312 B only permits its utilisation for the assembly or fastening on construction elements providing that a deformation of the bush ^' s deformation zone is carried out by a regular tightening of the nut on the threaded end of the draw-rod, so that the nut is brought into contact with the flange on the bush, whereby the draw-head on the draw-rod with continued tightening of the nut effects a deformation of the bush ^' s deformable zone, and the drawing of this into contact with the side of the construction elements facing away from the flange. This means that in the mounting of the mounting element, use must be made of a tightening tool for the nut, and also an insertion tool cooperating with the recess for creating the counter-hold necessary for the tightening of the nut. Other things being equal, this will involve a slow, time-consuming and difficult mounting procedure for the mounting element, which will hardly be attractive with the demands for efficiency which are made today in connection with the assembly of construction elements. Moreover, said mounting elements hardly find application in connection with an automated assembly of construction elements, for example in connection with assembly robots.

It is the object of the invention to provide a mounting/assembly element of the kind disclosed which makes possible a harder tightening of the nut on the threaded part of the rivet bush, and herewith a more stable fastening, and which also allows the use of locking fluids, without the anchored part of the rivet bush turning around during the dismounting of the nut.

A further object of the invention is to disclose a fastening element which makes quick mounting possible, for example with known mounting tools, or with robots, at the same time that the above-mentioned object is achieved.

This object is achieved with a mounting/assembly element as disclosed in the preamble to claim 1 , which is characterised in that the second end of the rivet bush also has a non-cylindrical inside cross-section, and that in the element's firmly-mounted state the part of the break zone connected with the draw-head is lying in the first end of the rivet bush, alternatively that in the element ^' s firmly- mounted state the break zone is lying in the lower half-part of the second end of the rivet bush facing towards the draw-head.

The possibility is hereby achieved of the insertion of a tool in that part of the rivet bush where its outer side comprises thread and nut, and said tool can be used as counter-hold for neutralising of the torsion moment on the rivet bush during the dismounting of the nut. The insertion end of the tool shall naturally be adapted to the internal non-circular cross-section of the rivet bush, and can therefore consist of a special tool for safeguarding against unauthorised dismounting of the nut. Moreover, the element allows itself to be mounted with the use of a traction tool, for example commonly-known drawing pliers, which provides the possibility for the implementation of a quick mounting of the element. The quick mounting can be made further effective with use of robot tools comprising the necessary traction tool, the fastening element being mounted as an insertion part which is introduced through two overlapping holes in a construction. The draw rod is hereafter influenced by traction for deformation of the deformable part of the rivet bush until breakage, so that the remaining part of the draw-rod connected with the draw- head will be localised in the rivet bush ^' s deformable zone, alternatively in the lower end of the threaded end of the rivet bush, so that there is room for introduction of an insertion tool cooperating with the non-cylindrical inside cross-section for establishing of counter-hold in connection with the dismounting and mounting of the nut.

Attempts to dismount the nut will be revealed by the formation of scratches in the surface/the paint on the side of the item facing the nut. Therefore, the need for the use of specially-made tools will be small. This characteristic is not offered with the use of the fastening element which is known from US 4 560 312 B, where tightening of the nut will leave scratch marks on the facing side of a relevant construction element.

With the object of making the use of the mounting/assembly element more universal, the inside non-cylindrical cross-section in the second end of the rivet bush can have a cross-section which is suitable for cooperating engagement with an insertion tool, chiefly a standard insertion tool.

It is hereby achieved that the nut can be loosened by use of standard tools which can be obtained on the general market. For example, the non-cylindrical cross-section could be hexagonal, so that it provides for cooperating engagement with a corresponding hexagonal key, e.g. of the Unbraco® type. The nut is thus loosened by first inserting a suitable standard hexagon key in the rivet bush's

opening, and thereafter the application of a suitable open-ended/adjustable spanner corresponding with the outer geometry of the nut, after which the nut is removed by turning the open-ended/adjustable spanner while at the same time holding the hexagon key in the initial position, whereby the rivet bush is held in its position without turning around in its seating in the underlying item.

With the object of ensuring a quick insertion of the assembly element in connection with use, the free end of the draw-head can have a pointed, conical extent. There is hereby achieved a quick centring and introduction of an assembly element in overlapping holes in items which are to be joined together with the assembly element.

With the object of ensuring an effective contact surface between the first end (deformation zone) of the rivet bush and the draw-head, and to ensure a uniform deformation of the deformation zone during traction on the draw-rod, over the conical extent between this and the break zone there can be a recess against which the first end of the rivet bush is in contact. Contact is hereby achieved against the whole periphery of the rivet bush, which will thus be deformed uniformly during the deformation procedure during the drawing/displacement of the head.

With the object of ensuring a large as possible contact surface between the rivet bush and the side of the item against which the external side of the rivet bush ^' s deformation zone is in contact, the draw-head between the recess and the break zone on the draw-rod can have a conical extent which corresponds to an internal conical extent in the transition between the first and the second end of the rivet bush.

With the object of ensuring a better friction between the outer side of the rivet bush and the facing side of the item, the outside surface of the rivet bush's deformation zone can be grooved. In the fastening of the rivet bush, the grooving will grip more firmly in the facing side of the item, which will counteract rotation of the rivet bush along with the nut during the dismounting of the nut. Moreover, the rivet bush will hereby also better withstand vibrations.

In a first special configuration of the grooving it is preferred that the grooving on the outside surface of rivet bush ^' s deformation zone consists of serrations.

In a second special configuration of the grooving it is preferred that the grooving on the outside surface of rivet bush ^' s deformation zone consists of zigzag grooving.

In a third special configuration of the grooving it is preferred that the grooving on the outside surface of rivet bush's deformation zone consists of helical grooving, with the pitch oriented towards the thread on the outside of the second side of the rivet bush.

With the object of providing good engagement facilities for the draw toot which is used for the fastening of the assembly element, the outside surface of the draw-rod in the end opposite the break zone can comprise grooving or corrugations. The possibility is hereby achieved for establishing a better grip as a result of the greater friction between the elements of the draw tool and the draw-rod.

With the object of ensuring that unauthorised attempts to dismount the nut on the assembly element are revealed, also on relatively hard surfaces, the side surface of the nut facing towards the deformation zone of the rivet bush can be corrugated or grooved. There is hereby achieved a greater probability that in the turning of the nut in connection with attempts at dismounting, scratch marks are formed on item surfaces facing towards the grooving/corrugations, also even though the surface of the item is relatively hard, whereby unauthorised dismounting of the nut, or attempts to dismount the nut, are revealed with greater probability.

In the following, the invention is explained in more detail with reference to the drawing, where

Ftg.1 is a perspective view of a mounting/assembly element according to the invention, immediately before insertion through overlapping holes in two overlaid plate items which shall be joined together by means of the assembly element.

Fig. 2 is a perspective view of the mounting/assembly element shown in fig. 1 , inserted into overlapping holes in two overlaid plate items.

Fig. 3 is a perspective view of the mounting/assembly element shown in fig. 1 and fig. 2, where the assembly element's rivet bush is fastened/anchored in the lowermost plate item.

Fig.4 is a perspective view of the mounting/assembly element shown in fig. 1 , fig. 2 and fig. 3, where the nut has been dismounted.

Fig. 5 is a perspective view of the mounting/assembly element shown in fig. 4, where the nut and the upper plate item are removed, ready for mounting.

Fig. 6 is a perspective sectional view of the mounting/assembly element according to the invention shown in fig. 1.

Fig. 7 is a perspective sectional view of that shown in fig. 2 Fig. 8 is a perspective sectional view of that shown in fig. 3 Fig. 9 is a perspective sectional view of that shown in fig. 4 Fig. 10 is a perspective sectional view of that shown in fig. 5 Fig. 11 is a perspective sectional view of the example embodiment of the mounting/assembly element shown in figs. 1-10 during the insertion of tools for the dismounting of the nut, and

Fig. 12 shows the same as in fig. 10, but where the tools are applied for the dismounting/mounting of the nut.

In fig. 1 there is shown a first embodiment of the mounting/assembly element 2 for use in the assembly of items, particularly overlapping plate parts 4, 6 and components.

The mounting/assembly element 2 comprises a rivet bush 7 with a first end 8 and second end 10. As will be seen more clearly in fig. 6-10, the first end 8 comprises a deformable zone 12 for insertion through coincident holes 14, 16 in the items 4, 6, and in the rivet bush 7 there is housed a draw-rod 18, the first end 20 of which comprises a draw-head 22 with a greater diameter than the draw-rod 18 and a break zone 24 above the draw-head 22.

The draw-head 22 is housed in the deformable zone 8, 12 of the rivet bush. The second end 26 of the draw-rod 18 extends up over the second end 10 of the rivet bush 7, and in the shown embodiment comprises a corrugation 28 which serves to provide a better grip for the draw tool which is used for the mounting/fastening of the element 2 in the lowermost plate item 6.

The second end 10 of the rivet bush also comprises an external thread 30 on which there is provided a cooperating nut 32, which in the mounting of the element 2 serves as a counter-hold for fastening of the uppermost plate part 4, as will appear from fig. 4 and fig. 8. The nut 32 can be loosened with the use of commonly- known tools, as will appear from fig. 11 and fig. 12. The tool can consist of an open-ended or adjustable spanner 34, a box spanner or similar tools which are able to engage with the external geometry of the nut 32.

As already mentioned, the second end 10 also comprises a non-cylindrical internal cross-section 36, as indicated in fig. 3, fig. 4 and fig. 5, and fig. 8, fig. 9 and fig. 10, but which appears more clearly in fig. 11. In the shown embodiment, the non-cylindrical internal cross-section consists of a hexagonal profile 36, the geometry of which cooperates with the insertion end 38 of a hexagonal key 40, for example of the Unbraco® type, which as indicated in fig. 12 can be used as counter-hold arrangement in connection with the mounting and dismounting of the nut 32.

The turning moments (both directions) which should otherwise be absorbed by the frictional forces between the outside of the first end of the rivet bush and the sides of the holes 24, 16 in the plate items 4, 6 and the rear side of the lower plate item 6, will thus be taken up by the counter-hold established by the hexagonal key 40 inserted in the second end 10 of the rivet bush, whereby the co-turning of the first end of the rivet bush with the turning of the nut is avoided, both in the dismounting as well as the mounting of the nut 32. The advantage herewith is significant, in that the mounting/assembly element 2 according to the invention can be tightened considerably harder during the mounting than is possible with the known technique, since regard does not have to be paid to torsion forces on the end 8 of the rivet bush anchored in the lower plate item 6, and since the dismounting of the nut 32 can take place without applying turning moment to the first end 8 of the rivet bush, in that a counter-hold can be established for absorbing the moment by means of an insertion tool, for example a hexagonal key in the shown embodiment of the mounting/assembly element 2 according to the invention, so that the rivet bush does not turn around together with the nut 32 during the mounting and dismounting of the nut 32.

Since with the use of the mounting/assembly element according to the invention there can be established a counte-rhold during the dismounting of the nut 32, it will also be possible to use locking fluids in connection with the element according to the invention, which makes it particularly suitable for use in the mounting of cover plates on machines and other places where vibrations arise, and where experience has shown that with time such mounting elements can work loose, and where protection against unauthorised access is desired.

As will appear from fig. 1 , the first end 8 of the rivet bush 8 can on the external side 41 comprise a grooving 42 which serves to establish a better engagement in the hole 16 and the lower item 6 in the mounting of the mounting/assembly element 2 according to the invention.

As will appear from fig. 6-10, between the recess 46 and the break zone 24 on the draw-rod 28, the draw-head 22 also comprises a conical section 48 which corresponds to an internal conical section 50 in the transition between the first end 8 and second end 10 of the rivet bush.

As will further appear from fig. 1 - fig. 10, the draw-head has an external conical extent 44 which will ease the introduction of the mounting element into overlapping holes 14, 16 in plate items 4, 6, or other items which shall be assembled with the mounting/assembly element 2 according to the invention. This means, among other things, that the element will more easily be able to be mounted in a mechanical manner, i.e. with robots or other automated tools.

As wiil further appear from fig. 6 - fig. 10, above the external conical section 44 there is a recess 46 against which the first end of the rivet bush 7 is in contact. With this configuration of the draw-head, there is achieved a uniform deformation of the deformabte zone 12 of the rivet bush, so that this is drawn uniformly against relevant parts of the mounting element or the plate in which it is mounted.

The mounting/assembly element 2 is used as follows, where reference is made to fig. 1 - fig. 10:

Two overlapping plates 4, 6 comprising holes 14, 16 with diameters suitable for the mounting element 2, are placed so that said holes 14, 16 are coincident. A mounting element 2 is inserted into the holes 14, 16, as will appear from fig. 2 and fig. 7, with the first end 8 of the rivet bush inserted in the holes 14, 16, and with the nut 32 in contact with the facing side of the uppermost item 4, after which traction is applied to the draw-rod 18 by a not-shown tool, which will result in a deformation of the deformable zone 12 of the rivet bush, so that the rivet bush is hereby fastened to the lower plate item 6. By the continued application of traction on the draw-rod 18, this will break in the break zone 24, which also after full deformation of the deformable zone 12 is lying in the first end of the now deformed zone of the rivet bush. The mounting/assembly element 2 is now anchored in the lower plate item 6, and the upper plate item 4 is hereafter fixed by the nut 32, the surface of which facing the surface of the plate 4 is drawn into contact against the plate 4. With the removal of the now broken-off part of the draw-rod 18, there is now free access to the non-cylindrical cross-section 36 on the inside of the second end 10 of the rivet bush 7, the external side of which comprises a thread 30 on which the nut 32 is mounted, as will appear from fig. 3 and fig. 8.

The dismounting/mounting of the nut 32 from the second end 10 of the rivet bush, as will appear from fig. 4, fig, 5 and fig, 9 and fig. 10 takes place by inserting the free end 38 of a suitable insertion tool 40 with a non-cylindrical internal cross- section 36 into the opening 36, and bringing a suitable adjustable/open-ended spanner into engagement with the nut 32, after which and at the same time that a force is applied to the spanner 34 a corresponding force is applied on the insertion tool 40, whereby the nut 32 can be dismounted without the rivet bush turning around together with the nut, and after dismounting of the nut 32 the upper plate item can be removed. As a consequence of the friction between the nut 32 and the surface of the upper plate item 4, the turning of the nut will result in the formation of score marks in the surface of the plate, which will reveal that the plate has been removed.

The remounting of the nut 32 takes place in the same way as described above, though merely in the opposite order, but such that the nut 32 is turned with the key 34 at the same time that the insertion tool 40 secures the rivet bush 7 in its position.