WO2000003146A1

WO2000003146A1 - Connecting device and connecting fitting

Info

Publication number: WO2000003146A1
Application number: PCT/NO1999/000223
Authority: WO
Inventors: Bror Fries
Original assignee: NEW IDEAS AS
Current assignee: NEW IDEAS AS
Priority date: 1998-07-08
Filing date: 1999-07-02
Publication date: 2000-01-20
Anticipated expiration: 2001-01-08
Also published as: NO983159L; JP2002520547A; EP1093547A1; AU4805399A

Abstract

A device for detachably joining structural members such as furniture components, a door leaf and a door frame, a window sash and a window frame, wherein the device has connecting parts made in the form of a male part and a female part respectively. The device is characterised in that at least one of the connecting parts is designed to be capable of insertion with at least one portion thereof into a hole adapted to the circumference thereof in the associated structural member; that at least one sector of the circumference of the connecting part is made having projecting gripping flanges; and that said hole is so designed that when the connecting part is turned in the hole through an angle equal to the angular extent of the gripping flanges, the gripping flanges will cut their way into the material of the structural member and thus secure the connecting part in the structural member.

Description

CONNECTING DEVICE AND CONNECTING FITTING.

The present invention relates to a device for detachably joining structural members, such as, e.g., furniture components, a door leaf and a door frame, a window sash and a window frame, wherein the device has connecting parts made in the form of a male part and a female part respectively.

Furthermore, the invention relates to a fastener for releasable connection to a structural member, such as, e.g., a furniture component, door leaf, door frame, window sash, window frame, wall, ceiling, floor wherein the fastener is designed to be capable of insertion with at least one portion thereof into a hole adapted to the circumference thereof in the structural member.

A feature common to the screws and clamping fixtures which are found on the market today for assembling so-called flat-pack furniture, cupboards etc. is that they are all plainly visible. Moreover, they are delivered, with a few exception exceptions, in multiple parts, as a rule loose in a bag, so that the consumer can assemble the structural members himself.

Generally, joining devices or fasteners of this kind are apt to be visible and require a certain technique if they are to be fitted correctly.

The object of the present invention is to provide a far simpler device, and a fastener, wherein the functional parts of the device or fastener are barely visible after they have been fitted and wherein the fitting is simple to carry out.

The device and the fastener are characterised by the distinctive features which are set forth in the attached patent claims and in the description which now follows with reference to the attached drawings.

Fig. 1 shows a first embodiment of the device according to the invention, where Fig. la shows the female part of the device and Fig. lb shows the male part of the device, and wherein these connecting parts have been installed in respective structural members, and where Fig. lc shows an end view of that shown in Fig. lb.

Fig. 2 shows the device indicated in Figs, la and lb once the two parts have been connected.

Fig. 3 is a fragmentary view of a structural member in which the male connecting part is to be fitted.

Fig. 4 is the view taken along the line IV-IV in Fig. 3.

Fig. 5 is a large-scale illustration of the male connecting part shown in Fig. lb.

Figs. 6, 7, 8, 9, 10 and 11 show views taken along the lines VI-VI, VII-VII, VIII-VIII, IX-IX, X-X and XI-XI in Fig. 5.

Fig. 12 shows a structural member with an insertion hole for the female connecting part.

Fig. 13 is a sectional view taken along the line XIII-XIII in Fig. 12.

Fig. 14 is a side view of the female connecting part.

Figs. 15 and 16 show respectively the views taken along the lines XV-XV and XVI-XVI in Fig. 14.

Fig. 17 is a sectional view taken along the line XVII-XVII in Fig. 16.

Fig. 18 shows the female connecting part inserted into the hole in the associated structural member, and where rotary motion of the female part relative to the hole is indicated. Fig. 19 shows the female part with gripping flanges which have cut their way into the wall of the hole in the associated structural member.

Fig. 20 shows the view taken along the line XX-XX in Fig. 18.

Figs. 21-27 show an alternative embodiment of the device according to the invention, where Fig. 21 shows a connecting bolt which partly constitutes the male part of the device; where Fig. 22 shows the view taken along the line XXII-XXII; where Fig. 23 shows a sleeve for mounting the part shown in Fig. 21 in a structural member, as is shown in more detail in Fig. 26b; and where Fig. 24 and Fig. 25 show respectively the views taken along the lines XXIV-XXIV and XXV-XXV in Fig. 23; and where Fig. 26a shows the female connecting part secured in the associated structural member; and Fig. 27 shows the view taken along the line XXVII-XXVII in Fig. 26b.

Figs. 28 and 29 show respectively a side view and a view from the underside of a female part of a joining device, or an embodiment of a fastener according to the invention.

Fig. 30 shows the mode of assembly of the device or fastener; Fig. 31 shows the view taken along the line XXXI-XXXI in Fig. 30; and Fig. 32 shows the view taken along the line XXXII-XXXII in Fig. 30.

Fig. 33 shows a modification of the device according to the invention used as a hinge.

Figs. 34a and b show a further modification of the device according to the invention used in connection with a hinge construction.

Figs. 35 and 36 show the use of the invention for forming fasteners.

Fig. 37 shows a further modification of the device according to the invention. In the solution shown in Figs. 1-3 two structural members 1, 2 are to be joined together. These structural members may, e.g., be furniture components, such as the top or bottom 1 of a cupboard and side walls 2. For this purpose it is proposed to use as connecting parts a female part 3 and a male part 4 in the form of a bolt which is insertable in a hole 5 in the structural member 1. The bolt 4 has, at a distance from the end 6 thereof which is to engage the female part 3, a collar or shoulder 8 designed for engagement with a tool 7 for turning the bolt and shaped to fit into a correspondingly shaped recess 9 in the structural member 1. The tool 7 for turning the bolt is adapted to be capable of engaging with holes or recesses 10 in said collar or shoulder 8. The collar or shoulder 8 has a flange portion 8' which on insertion into the material of the structural member 1 is designed to prevent cracking therein. A groove 9' is thus produced in the said recess.

As can be seen from Fig. 4, the recess 9 is essentially circular, optionally made having a truncated chord portion 11 that extends over an angle α which is less than 90°, preferably 20-60°. The collar or shoulder 8 may optionally have gripping flanges (not shown) for engaging with the recess 9 walls when the male part or bolt 4 is turned.

The bolt 4 has gripping flanges 12 which, when the bolt 4 is turned in the hole 5, are designed to cut into and firmly grip into the structural member 1, i.e.. the wall of the hole 5. To facilitate the insertion of the bolt 4 into the hole 5, the bolt 4 is equipped with a chisel device 13 and adjacent to this device there is arranged a constriction 14 in the periphery of the bolt 4 for receiving the particles of the hole wall 5 which are cut away by the chisel device 13 when the bolt 4 is introduced into the hole 5. For a somewhat more detailed understanding of the design of the male part or the bolt 4, reference is also made to that shown in Figs. 5-10.

The male part 4 at the end 6 thereof that is to be inserted into the female connecting part is equipped with a male bayonet connecting means 15, as is also indicated in Fig. 9.

As is evident from Fig. lb and also from Fig. 5, the gripping flanges 12 are on in an axial direction different peripheral portions of the bolt 4. If gripping flanges are also provided on the collar or shoulder 8, this will mean that there are gripping flanges on peripheral portions having different diameters. Additional details of this solution can be seen from that shown and described in connection with Figs. 28-32.

Thus when the male part or bolt 4 is inserted into the hole 5 the chisel device 13 will shave away the material of the hole wall, thereby enabling the gripping flanges to sweep along that portion of the hole 5 wall. When the male part or bolt 4 is turned, e.g., 90°, with the aid of the tool 7 which engages with the collar or shoulder 8, the gripping flanges 12 will cut their way into the non-shaven portion of the hole wall, thereby axially securing the bolt 4 in the hole 5. Should it be desirable to release the bolt from the structural member 1 , the bolt can either be turned back 90° or turned on 90° so as to be rendered capable of being drawn out of the hole 5.

The female connecting part in the present device will be described in more detail with reference to Figs. 12-20.

Figs. 12 and 13 show the structural member 2 with a hole 16 for insertion of the female part 3. It will be seen that the hole 16 has cut-out grooves 16' to allow the female part 3 with its gripping flanges 17 to be inserted into the hole. The female part 3 has an insertion hole 18 for the portion 6 of the bolt or the male part 4 which is to be inserted into the female part 3. At the bottom the wall of the female part 3 transforms into bayonet gripping flanges 19 which form a female bayonet connecting part for engagement with the male bayonet connecting part 15 on the insertion portion 6 of the male part 4. These bayonet connecting means 19 have an inclined face of contact, in conformity with the inclination of the male bayonet connecting means 15.

When the female part 18 with its gripping flanges 17 is inserted into the hole 16, 16', it will have the appearance as shown in Fig. 18. When the female part 3 is to be fastened to the structural member 2 by engaging with the hole 16 walls, the female part 3 is turned, e.g., 90°, as shown in Fig. 18 to take up a position as shown in Fig. 19, where the gripping or cutting in of the gripping flanges in the hole 16 wall is indicated by means of the reference numeral 17'.

Normally the female part will be pre-mounted in the structural member 2, e.g., factory- mounted. When the portion of the male part 4 having gripping flanges 12 is inserted into the hole 5 at the same time as the insertion portion 6 is inserted into the hole 16 in the female part 3, there will be an engagement between the hole 5 wall and the gripping flanges 12 when the collar or shoulder 8 is turned, whilst the bayonet connection 15, 19 engages, and because of the inclined engaging faces causes the structural member 2 to be drawn positively towards the structural member 1. In this way a secure locking or joining of the two structural members 1, 2 is obtained.

A modification of the device described thus far for detachably joining together structural members will now be described with reference to Figs. 21-27.

In the illustrated case, the female connecting part is indicated by means of the reference numeral 20 and is made having circumferential gripping flanges 21 , although a female part of the type shown in Fig. la and Figs. 14-17 could of course be used. The male connecting part consists of a split sleeve 22 equipped with gripping flanges 23, these gripping flanges either being circumferential or extending over a part of the periphery of the split sleeve 22. The split sleeve 22 is placed in a hole 24 made for this purpose in the structural member 1 by press fitting, the gripping flanges 23 being so designed that withdrawal of the split sleeve from the hole 24 is prevented once the sleeve has been inserted. The male connecting part consists in addition of a bolt 25 which with a first axial portion 25' is insertable in the sleeve 22 and by one end thereof 25" is retainable in the sleeve at its end portion 22' by means of snap engagement, the bolt 25 being rotatable about its axis relative to the sleeve 22. A second opposite end portion 26 of the bolt is made having a means 27, e.g., a male bayonet connecting means which, when the portion 26 is inserted into the female part 20 and the bolt is turned relative to the female part 20, is designed to engage with the female bayonet connecting means in the female part 20, whereby owing to the inclined engaging faces on the bayonet connecting means the structural members 1 and 2 are drawn towards one another when the bolt is turned when engaged by a tool 7 which engages with hole 28 on the collar or shoulder 29 on the bolt or male part 25, as also shown and explained in connection with Figs. 1 and 2.

The split sleeve 22 has a collar 22" which abuts against the bottom of a recess 30 in connection with the mouth of the hole 24. This embodiment which is shown in Figs. 21-27 may be especially suitable when the material in, e.g., the structural member 1 has thin walls or is brittle, or the quality of which is such that there is little point in allowing gripping flanges 12, as shown in Fig. lb and Figs. 5 and 7, to cut their way into the material of the structural member 1. Thus any cracking in the material of the structural member 1 is prevented.

Figs. 28-32 show a solution of the present invention wherein the connecting part is indicated by means of the reference numeral 31. The connecting part 31 has two sets of gripping flanges 32, 33 which are on in an axial direction different peripheral portions of the connecting part, and wherein the peripheral portions have different diameters, the gripping flanges 32 being on a portion of the connecting part 31 which has a greater diameter than the portion of the connecting part 31 wherein the gripping flanges 33 are located.

The connecting part 31 , which is shown in Fig. 28 when seen from the side and in Fig. 29 when seen from the underside, is secured in a recess 35 in a structural member 34 and is turned, e.g., 90°, as indicated in Fig. 30, whereby the gripping flanges 32, 33 will cut their way into the walls of the recess or the hole 35, as indicated by means of the reference numerals 32 ' , 33 ' .

The connecting part 31 shown in Figs. 28-32 may conceivably be used, e.g., to receive a hinge leaf of a hinge that is designed for insertion into a hole 36 in the connecting part 31 and for forming therein snap engagement with a snap-in tongue 37 provided in the connecting part 31. It will be appreciated, however, that other uses of the connecting part 31 are also conceivable within the scope of the invention. Of course, it is also conceivable to have, e.g., gripping flanges on only one of the peripheral portions.

As shown in the preceding figures, Figs. 1, 2, 5, 7, 14-16 and 20, and also Figs. 28 and 29, the circumference of the connecting part has at least one sector equipped with the projecting gripping flanges, and according to the present invention at least one sector thus spans an angle of the circumference of the connecting part portion which is less than 180°. A sector of this kind preferably spans an angle which is equal to or less than 90°.

Although it is shown and described in connection with Figures 1 -27 that the connecting parts are designed to be connected by means of bayonet engagement, it will however be appreciated that alternative locking principles can be applied, e.g., thread locking or gripping flange engagement. However, the illustrated bayonet connection is at present the most preferred embodiment.

As can be seen from Figures 1-27 and Fig. 37, the adjacent structural members form an angle of 90° with one another. Figs. 1-27 indicate that the male connecting part has its axis parallel to the plane of the associated structural member, whilst the female connecting part has its axis perpendicular to the plane of the associated structural member.

However, a solution as shown in Fig. 37 is conceivable, wherein the structural member for the male connecting part 38 is indicated by means of the reference numeral 39 and wherein the structural member for the female connecting part 40 is indicated by means of the reference numeral 41. The male part 38 has gripping flanges 42, and similarly the female part 40 has gripping flanges 43 for engaging with respective structural members 39, 41. The male part 38 has in addition a turning collar 44, which allows the male part 38 whilst engaging with the female part 40 also to cut its way into the material of the structural member 39 for securement there. Thus, as described previously, by turning the turning collar 44 the two structural members will be drawn towards each other, so that the adjacent edge faces of the structural members, which form an angle of 45° with respective planes of the structural members, will abut firmly against one another. The common axis of the connecting parts 38, 40, 42, 43, 44, as can be seen from Fig. 37, is perpendicular to the edge faces.

Optionally, the device according to the present invention could serve as a hinge between structural members 45, 46. As can be seen from Fig. 33, both of the connecting parts may consist of a bolt 47, 48 which in one portion is equipped with gripping flanges 49, 50 so that when turned about its respective axis relative to its respective structural member 45, 46, e.g., on the actuation of a turning collar 51 , 52 on the bolt 47, 48, it becomes fixed in the structural member 45 of the respective bolt, as is explained inter alia in connection with Figs. 1 and 5. The free end 53, 54 of the bolt 47, 48 has a pivot hole, and the two bolts 47, 48 will thus be capable of being rotatably interconnected by means of a pin 55 which engages with the pivot holes.

In the solution shown in Fig. 34, the female connecting part, indicated here by means of reference numeral 56, can be configured in the same way as shown and described in connection with Fig. la and Figs. 14-17. The bolt or male part is indicated in this figure by means of the reference numeral 57 and is secured in its structural member 58 in the same way as shown and described in connection with Fig. lb and Fig. 5. The free end of the bolt may be hinged by means of a hinge pin 59 so that when the insertion end 60 of the bolt 57 is inserted into the female part 56 and is locked in place there by bayonet engagement, the bolt 57 is simultaneously brought into engagement with the material of the structural member 58, whilst the two structural members 58 and 61 can be moved relative to each other.

In the embodiment illustrated in Fig. 35 there is shown a fastener consisting of a female part 62 which is secured in a structural member 63, e.g., a wall, and wherein a male part 64 can be inserted into the female part 62 to form bayonet engagement therewith on the actuation of a gripping collar 65. The engaging faces of the bayonet connections are preferably inclined as indicated in Fig. 35 and also shown and described in connection with the preceding figures, to ensure that a good locking is provided.

The part 64 of the fastener forms thus an additional fastener for the fastener 62 which is shown in Fig. 35.

Fig. 36 shows an alternative embodiment of that shown in Fig. 35, wherein a bolt 66 is used which when inserted into a hole 67 in a structural member 68 and when turned, e.g., 90°, relative to the hole ensures that the gripping flanges 69 on the bolt cut their way into the wall of the hole 67, and thus axially secure the bolt 66 relative to the structural member 68. The bolt 66 may have a projecting portion 70, optionally provided with a flange 71 , so that this portion 70 can serve as suspension for some article or other. Like that shown and described in connection with inter alia Fig. lb and Fig. 5, the bolt 66 is equipped with plane or chisel device 72 and constriction 73 for collecting the shaved-off material. In terms of function and installation this embodiment is otherwise the same as that shown and described in connection with Fig. lb and Fig. 5.

In accordance with customary technique when making holes in structural members for the fitting of joining devices, first a round hole is made, and then using the technique of cutting out the hole is made rectangular. In the present invention the hole 16 in the structural member 2 is enlarged over, e.g., two arcuate sectors 16', so that the female part 3 with its gripping flanges 17 can be introduced into the hole 16 and with the flanges 17 in the sectors 16', whereafter the female part when turned, e.g., through 90°, is secured in the member 2. In the case of the male part, the provision of corresponding sectors for the gripping flanges 12 carried out in that the chisel device shaves out these sectors when the bolt is introduced into the hole 5 in the structural member 1.

Claims

P a t e n t c l a i m s

1.

A device for detachably joining structural members such as, e.g., furniture components, a door leaf and a door frame, a window sash and a window frame, wherein the device has connecting parts made in the form of a male part and a female part respectively, characterised in

- that at least one of the connecting parts is designed to be capable of insertion with at least one portion thereof into a hole adapted to the circumference thereof in the associated structural member;

- that at least one sector of the circumference of the connecting part is made having projecting gripping flanges; and

- that said hole is so designed that when the connecting part is turned in the hole through an angle equal to the angular extent of the gripping flanges, the gripping flanges will cut their way into the material of the structural member and thus secure the connecting part in the structural member.

2.

A device for detachably joining structural members such as furniture components, a door leaf and a door frame, a window sash and a window frame, wherein the device has connecting parts made in the form of a male part and a female part respectively, characterised in

- that the periphery of the connecting part is made having projecting gripping flanges; and

- that said hole is so designed that when the connecting part is inserted into the hole the gripping flanges on press fitting will cut their way into the material of the structural member, prevent the connecting part from being drawn out of the hole, and thus secure the connecting part in the structural member.

3.

A device as disclosed in claim 1 or 2, characterised in

- that one of the connecting parts consists of a split sleeve equipped with gripping flanges and placed in a hole made for this purpose in an associated structural member, and a bolt which with a first axial portion is insertable into the sleeve and at one end thereof is axially securable in the sleeve by snap engagement and rotatable relative to the sleeve, and at a second, opposite end portion, when the bolt is turned, is made having a means for being secured in a second structural member when the bolt is turned.

4.

A device as disclosed in claim 3, characterised in

- that the securing in the second structural member takes place in that the second end portion of the bolt over a part of its periphery is made having a male bayonet connecting means for engagement with a female bayonet connecting means in a connecting part which is secured in the material of the second structural member.

5.

A device as disclosed in one or more of claims 1-4, characterised in - that the male connecting part consists of a hinge having two hinge leaves which are pivotal relative to one another, wherein one of the hinge leaves is adapted for securement to one of the structural members, and wherein the second hinge leaf is adapted to form snap engagement with the female connecting part.

6.

A device as disclosed in claim 1 , characterised in

- that said at least one sector spans over an angle of the circumference of the connecting part portion which is less than 180°.

7.

A device as disclosed in claim 1, 2 or 3, characterised in - that the connecting parts are designed to be connected to each other by means of bayonet engagement, wherein the male part and the female part of the bayonet connection have engaging faces which are inclined relative to their axial direction.

8.

A device as disclosed in claim 1 , characterised in

- that one of the connecting parts consists of a male part in the form of a bolt which has a free end for insertion into a female connecting part which when turned about its axis relative to the female part, e.g., by actuating a turning collar on the bolt, is designed to be axially locked to the female part, e.g., by bayonet locking, thread locking or gripping flange engagement in the female part, whilst being secured in the associated structural member of the male part by means of the gripping flanges on the male part.

9. A device as disclosed in claim 8, characterised in

- that the bolt which by means of its gripping flanges grips into its associated structural member at one end portion thereof is made having a chisel device, and

-that behind this end portion there is arranged a constriction in the periphery of the bolt for receiving the particles from said structural member which are shaved away by the chisel device when the bolt is inserted into a hole in the structural member.

10.

A device as disclosed in one or more of the preceding claims, characterised in - that the male connecting part, which is in the form of a bolt, has at a distance from the end which is to grip into the opposing structural member, a collar or shoulder designed for engagement with a tool for turning the bolt and shaped to fit into a correspondingly shaped recess in the associated structural member of the male part.

11.

A device as disclosed in claim 10, characterised in - that the collar or shoulder has a flange which on insertion into the material of the structural member is designed to prevent cracking therein.

12. A device as disclosed in claim 10, characterised in

- that the recess is essentially circular, optionally made having a truncated chord portion that extends across an angle of less than 90°, preferably 20-60°.

13. A device as disclosed in claim 10, characterised in

- that the collar or shoulder has gripping flanges which when the male part is turned are designed to engage in said recess.

14. A device as disclosed in claim 1 or 2, characterised in

- that the connecting parts together form a hinge between the structural members.

15. A device as disclosed in claim 14, characterised in

-that both of the connecting parts consist of a bolt which at one end portion thereof is equipped with gripping flanges so that when turned about its axis relative to its structural member, e.g., on actuating a turning collar on the bolt, it becomes fixed in the associated structural member of the respective bolt, and wherein the free end of the bolt has a pivot hole, the two bolts being pivotally interconnected by means of a pin which engages with said pivot holes.

16.

A device as disclosed in claim 1 or 2, characterised in - that the gripping flanges are on in an axial direction different peripheral portions of the connecting part.

17.

A device as disclosed in claim 16, characterised in

- that at least two of the different peripheral portions have different diameters.

18.

A device as disclosed in one or more of claims 1-4, 6-13, 16-17, characterised in

- that the adjacent structural members form an angle of 90° with each other.

19.

A device as disclosed in claim 18, characterised in

- that one of the connecting parts has its axis parallel to the plane of the associated structural member, whilst the other of the connecting parts has its axis peφendicular to the plane of the associated structural member.

20.

A device as disclosed in claim 18, characterised in

- that the adjacent edge faces of the structural members form an angle of 45° with the plane of the respective structural member; and

- that the common axis of the connecting parts is peφendicular to the said edge faces.

21.

A fastener for releasable connection to a structural member, such as a furniture component, door leaf, door frame, window sash, window frame, wall, ceiling, floor, wherein the fastener is designed to be capable of insertion with at least one portion thereof into a hole in the structural member that is adapted to the circumference thereof, characterised in

- that at least one sector of the said circumference of the fastener is made having projecting gripping flanges; and

- that said hole is so designed that when said portion of the fastener is turned in the hole through an angle equal to the angular extent of the gripping flanges, the gripping flanges will cut their way into the material of the structural member and thus secure the fastener in the structural member.

22.

A fastener as disclosed in claim 21, characterised in

- that the fastener has a central, axial hole which, preferably at its bottom portion, has a female connecting means for connection with an additional fastener formed at its insertable end to have a male connecting means.

23.

A fastener as disclosed in claim 21, characterised in - that said at least one sector spans an angle of the circumference of the portion of the connecting part which is less than 180°.

24.

A fastener as disclosed in claim 22, characterised in - that the female and male connecting means have engaging faces which are inclined relative to their axial direction.

25.

A fastener as disclosed in claim 22 or 24, characterised in - that the supplementary fastener consists of a bolt which has a free end for insertion into said central hole which when turned about its axis relative to the fastener, e.g., by actuating a turning collar on the bolt, is designed to be axially locked to the fastener, e.g., by bayonet locking, thread locking or gripping flange engagement.

26. A fastener as disclosed in claim 21 or 23, characterised in

- that the fastener is made in the form of a bolt which with the aid of its gripping flanges grips into the structural member,

- that the bolt at an end portion thereof is made having a chisel device; and - that behind this end portion there is arranged a constriction in the periphery of the bolt for receiving the particles from said structural member which are cut away by the chisel device when the bolt is introduced into the hole in the structural member.

27. A fastener as disclosed in one or more of claims 21, 23 and 26, characterised in

- that the fastener, which is made in the form of a bolt, has, at a distance from its free end which projects from the structural member, a collar or shoulder designed for engagement with a tool for turning the bolt and shaped to fit into a correspondingly shaped recess in the structural member.

28.

A fastener as disclosed in claim 27, characterised in

- that the collar or shoulder has a flange which on insertion into the material of the structural member is designed to prevent cracking therein.

29.

A fastener as disclosed in claim 27, characterised in

- that the recess is essentially circular, optionally provided with a truncated chord portion which extends over an angle of less than 90°, preferably 20-60°.

30.

A fastener as disclosed in claim 27, characterised in

- that the collar or shoulder has gripping flanges which when the bolt is turned are designed to engage with said recess.

31. A device as disclosed in claim 21, characterised in

- that the gripping flanges are on in an axial direction different peripheral portions of the fastener.

32.

A device as disclosed in claim 31 , characterised in