TECHNICAL FIELD OF THE INVENTION

The invention relates to an assembly of a thin sheet metal part and a substrate part to which the sheet metal part is mechanically and/or electrically connected, the connection being provided by a screw with countersunk head from which a threaded shank emanates that is received and tightened in a cavity of the substrate part. Such an assembly is typically used in a housing for accommodating devices such as electrical, electronic and optical devices.

The invention further relates to such housing for accommodating devices comprising electrical, electronic and optical devices, wherein the housing comprises at least one assembly in accordance with the invention.

The invention also relates to a screw for use in the invented assembly, as well as to a thin sheet metal part for use in said assembly.

The invention relates to an assembly of a thin sheet metal part and a substrate part. A thin sheet metal part is defined as a sheet metal part having a thickness that does not exceed 2.1 mm.

BACKGROUND OF THE INVENTION

Housings for accommodating devices such as electrical, electronic and optical equipment, in particular computer equipment, have been known for some time. Non-limiting examples of applicable electronic equipment comprise servers, network hardware and sound technology equipment. Housings that may be used in business applications for instance, may comprise racks that are typically open-walled, apart from a roof, and cabinets that typically comprise side walls as well. Such housings comprise a load bearing frame of interconnected frame members, which include floor frame members, vertically oriented side frame members, and roof frame members. Vertically oriented mounting rails for suspending equipment may be provided against and/or in between side frame members. Each mounting rail may be connected to a floor and a roof frame member. One example of such housing is a so-called 19 inch housing, which comprises a number of vertically oriented mounting rails that extend parallel to each other at a mutual standardized distance of typically 17.7 inches. Each mounting rail is provided with a plurality of openings or other receivers, extending along a longitudinal direction of each mounting rail and provided at equal height between mounting rails. Standardized, optionally modular, equipment may be typically 17.7 inches wide at most, and may further be provided with fixation lips to be connected to the openings or receivers, for instance by screws. In this way, multiple units of equipment may be suspended on top of each other in the same housing.

It should be noted that a housing comprising the invented assembly is not limited to the above-described 19 inch housing, and the invention is equally applicable to other housings, preferably with standardized dimensions, such as 23 inch housings, that are for instance used in telecommunication.

There is a continuous drive in the art to improve the housings with respect to strength, stiffness, cooling, prevention of rattle and other sounds, and weight and cost reduction. In that context, thin sheet metal wall parts with a wall thickness that does not exceed 2.1 mm are increasingly used. Such thin sheet metal wall parts may be mechanically connected to a frame member of the housing to provide roof parts or side walls of the housing, or walls for any other purpose. For connection, the thin sheet metal wall parts may be provided with a number of openings, and the connection may be established by a screw with a head from which a threaded shank emanates that is provided through the openings of the thin metal sheet part and received and tightened in a cavity of the frame member, which serves as substrate part for the thin metal sheet part.

In order to avoid collisions with screws that stick out, the use of screws with a countersunk head is preferred. These screws allow providing a countersunk connection between the thin metal sheet part and the substrate part. However, providing openings in a thin metal sheet part that allow such a countersunk connection is problematic since the connection generally lacks sufficient strength, and the connection is not reliable. A second problem relates to providing an electrical connection between the screw with countersunk head and the sheet metal part for grounding purposes. Indeed, sheet metal parts may be provided with a protective electrically insulating layer on a side facing the countersunk head of the screw, and such electrically insulating layer prevents establishing an electrical connection between the sheet metal part and a substrate part to which it is connected.

It is an object of the present invention to prevent or at least partially obviate the above stated prior art drawbacks.

SUMMARY OF THE INVENTION

These and other objects are achieved by providing an assembly in accordance with claim 1. The invented assembly in particular comprises of a sheet metal part with a wall thickness not exceeding 2.1 mm and a substrate part to which the sheet metal part is mechanically and/or electrically connected, wherein the connection is provided by a screw with countersunk head from which a threaded shank emanates that is received and tightened in a cavity of the substrate part, wherein the sheet metal part comprises a penetrable opening through which the shank of the screw is provided, wherein an outer diameter of the opening is slightly larger than the diameter of the head, an inner diameter of the opening is slightly larger than the diameter of the shank, and wall parts of the sheet metal part extend from the outer diameter towards the inner diameter, which wall parts are deformed by the countersunk head upon tightening the screw and are each received in a receiving space of the substrate part.

An outer diameter of the penetrable opening is slightly larger than the diameter of the countersunk screw head, by which is meant that the countersunk screw head is able to enter the penetrable opening such that a top surface of the countersunk head facing away from the shank may be flush or even lie below an outer surface of the sheet metal part when connected. An inner diameter of the penetrable opening is slightly larger than the diameter of the screw shank, by which is meant that the screw shank may be provided unhindered into that part of the opening covered by the inner diameter.

The threaded shank of the screw with countersunk head is received and tightened in a cavity of the substrate part. To this end, the cavity of the substrate part may at least partly be threaded as well and the substrate part threads cooperate with the countersunk screw threads to provide the connection. In another option, the cavity of the substrate part is not threaded but threads are produced in the substrate part cavity when providing and tightening the countersunk screw shank into the substrate part cavity. The screw is then referred to as “self tapping”. It should be noted that the invention does not require a substrate having a countersink or conical hole into which the countersunk head precisely fits. Indeed, the receiving space of the substrate part may be larger than the countersunk head in order to be able to receive the deformable wall parts.

The substrate part may be made of metal but may also be made of any other suitable material that is able to conduct electricity. A suitable material other than metal may be a polymer provided with electrically conducting fibers, such as carbon fibers for instance.

Another embodiment of the invention provides an assembly wherein the sheet metal part comprises a protective electrically insulating layer on a side facing the countersunk head, and the countersunk head is at a shank side thereof provided with a cutting edge that cuts through the electrically insulating layer when tightening the screw, thereby providing an electrical connection between the screw and the sheet metal part for grounding purposes. The optional electrical connection between the countersunk screw, the sheet metal part and the substrate part is instrumental in providing an earthing or grounding connection. In an electrical installation, an earthing system or grounding system connects specific parts of said installation with the earth's conductive surface for safety and functional purposes.

According to the invention, wall parts of the sheet metal part extend from the outer diameter towards the inner diameter and are deformed by the countersunk head upon tightening the screw and the deformed wall parts are received in a receiving space of the substrate part. In this process, the countersunk head at the shank side thereof contacts the wall parts and, upon further tightening of the countersunk screw into the cavity of the substrate part, deforms the wall parts towards the substrate part cavity such that, in the deformed state, they are received in a receiving space of the substrate part. The deformed wall parts that are received in the receiving space of the substrate part provide a strong and reliable connection between the thin sheet metal part and the substrate part, and further allow providing a countersunk connection between the substrate part and a thin sheet metal part.

The deformation of the wall parts when tightening the countersunk screw into the substrate part cavity may be of any type. In an embodiment, the wall parts are elastically deformed by the countersunk head upon tightening the screw. In this embodiment, untightening the screw and undoing the connection between the thin sheet metal part and the substrate part may result in recovering the deformation of the wall parts to their original state. In another embodiment, the wall parts are plastically deformed by the countersunk head upon tightening the screw. In this embodiment, untightening the screw will leave the wall parts in their deformed state. In other words, in this embodiment the deformation of the wall parts of the penetrable openings in the thin sheet metal part is permanent, once deformed.

The thin sheet metal part may have any shape. It may for instance be strip- or plate-shaped, or may have a profiled cross-section. The thin sheet metal part may be preferably used as part of an enclosure or housing for accommodating devices such as electrical, electronic and optical equipment, in particular computer equipment. A useful embodiment of the invention then provides an assembly wherein the sheet metal part comprises a plurality of the invented openings arranged along a side edge of the sheet metal part. Preferably, the side edge of the sheet metal part is linear, and the openings are aligned along a line parallel to the linear side edge of the sheet metal part. The or said openings refer to the penetrable openings through which the shank of the screw is provided, wherein an outer diameter of the openings is slightly larger than the diameter of the head, an inner diameter of the openings is slightly larger than the diameter of the shank, and wall parts of the sheet metal part extend from the outer diameter towards the inner diameter, which wall parts are deformed by the countersunk head upon tightening the screw and are each received in a receiving space of the substrate part. It will be understood that the sheet metal part may also comprise a plurality of other openings, optionally arranged along a side edge of the sheet metal part. The other openings are not penetrable and provided with deformable wall parts.

The substrate part may also have any shape, as long as it comprises a cavity for receiving the threaded shank of the countersunk screw, and a receiving space for receiving the deformable wall parts of the thin sheet metal part in their deformed state (also referred to as “the deformed wall parts”).

A practical embodiment is provided by an assembly wherein the substrate part comprises a nut or female screw, a central cavity of which is threaded and also provides the receiving space for the deformable wall parts. The receiving space may be threaded as well, or may not be provided with threads.

In another embodiment, the substrate part comprises a frame member of the housing, more preferably an extruded frame member, and the cavity of the substrate part comprises a, optionally threaded, groove extending in a longitudinal direction of the frame member, wherein the groove also provides the receiving space for the deformable wall parts. The receiving space may be threaded as well, or may not be provided with threads. In the latter embodiment, the groove is threaded over part of its surface only. A frame member preferably represents a linear structure that extends in the longitudinal direction.

The invention provides a solution to the problem of providing a strong and reliable countersunk connection between a thin sheet metal part and a substrate part. The thin metal sheet part has a wall thickness not exceeding 2.1 mm. In other more preferred embodiments, the wall thickness of the sheet metal part does not exceed 1.8 mm, more preferably does not exceed 1.6 mm, more preferably does not exceed 1.4 mm, even more preferably does not exceed 1.1 mm, and most preferably does not exceed 0.9 mm. The advantages of the invention become more prominent with smaller sheet metal part wall thickness. In most embodiments, the thin sheet metal part will have a constant wall thickness. If not, the wall thickness of the sheet metal part corresponds to its wall thickness at the position of the penetrable opening(s). In other words, the sheet metal part may be thicker at positions other than the penetrable opening position(s), for instance between penetrable opening positions.

The object of the invention is particularly achieved in an embodiment wherein a top surface of the countersunk head facing away from the shank is flush with or lies below an outer surface of the sheet metal part. The countersunk screw in this embodiment is tightened into the cavity of the substrate part sufficiently far to achieve the countersunk effect. One skilled in the art will be able to select the dimensions of the screw and of the substrate part cavity and/or receiving space to achieve this.

According to the invention, wall parts of the penetrable opening of the thin metal sheet part are deformed by the countersunk head upon tightening the screw and are each received in a receiving space of the substrate part. As already elucidated above, the deformation may be elastic (recoverable) or may be plastic (permanent). In order to facilitate deformation of the deformable wall parts, an embodiment is provided wherein the wall of the sheet metal part comprises one or more weakened areas in the vicinity of the deformable wall parts to facilitate their deformation by the countersunk head upon tightening the screw. Providing the weakened areas not only facilitates deformation of the penetrable opening wall parts but may also initiate a particular deformation mechanism, such as bending of the wall parts around a line formed in the weakened area(s).

Weakening the sheet metal part in a weakened area may be achieved in many ways. In one embodiment, a weakened area is formed by reducing the wall thickness of the sheet metal part in the weakened area. In another embodiment, the sheet metal part may be weakened in a weakened area by (additionally) removing parts of the sheet metal part, such as by drilling through-the-thickness holes in the sheet metal part. A weakened area may thus be defined as an area of the thin sheet metal part that has reduced mechanical properties, such as stiffness and/or strength.

Yet another embodiment is provided by an assembly wherein the deformable wall parts are movable, preferably relative to each other. A suitable embodiment for instance provides a number of wall parts that together form a diaphragm. By movement of the wall parts relative to each other, the diaphragm may be opened or closed. Movement of the wall parts may facilitate their deformation by the countersunk screw head.

Another practical embodiment relates to an assembly wherein the deformable wall parts comprise lips that extend between the inner and the outer diameter. Such lips may have a free edge at the inner diameter’ s side to provide an opening defined by the inner diameter. The lips, in an embodiment, may be deformed by bending them around the outer diameter under the action of a penetrating countersunk screw head. The number of deformable wall parts, or lips in some embodiments, may be chosen at will and can be 1, 2, 3, 4, 5, 6, 7, 8 and more, depending on practical considerations. The wall parts may be separate before providing the screw head into the substrate part cavity, or they may be separated when providing the screw head into the substrate part cavity.

An embodiment of the assembly in which the deformable wall parts comprise a plurality of lips arranged in a geometrical configuration, is preferred. The lips may for instance be configured to be arranged around the perimeter formed by the penetrable opening. When an even number of wall parts or lips is used, the wall parts or lips may in an embodiment be provided diametrically opposite to each other.

According to a preferred embodiment of the invention, the sheet metal part comprises a protective electrically insulating layer on a side facing the countersunk head, and the countersunk head is at a shank side thereof provided with a cutting edge that cuts through the electrically insulating layer when tightening the screw, thereby providing an electrical connection between the screw and the sheet metal part for grounding purposes. The cutting edge may be embodied in several ways. In a embodiment, the cutting edge of the countersunk head of the screw extends along a substantially complete circumference of the countersunk head of the screw. However, the cutting edge may also extend over a part of the circumference of the countersunk screw head only, or may be embodied as a number of cutting pins, arranged along the circumference of the countersunk screw. It is also possible to provide an embodiment wherein more than one cutting edge is provided on different radial distances from a center line of the countersunk screw head.

The invented assembly is preferably used in an enclosure for accommodating devices such as electrical, electronic and optical equipment, in particular computer equipment. Another aspect of the invention therefore relates to a housing for accommodating devices such as electrical, electronic and optical devices, comprising at least one assembly in accordance with the present disclosure. The sheet metal part may for instance comprise a wall of the housing, selected from an airtight wall, an air blocking wall, a bottom wall or a roof wall of the housing. In an embodiment, the substrate part may comprise a frame member of the housing, selected from an upstanding frame member, a floor frame member, or a roof frame member of the housing. Other substrate parts may relate to strips, or to a mounting rail, preferably an extruded mounting rail, provided with a number of cavities or holes. These examples are only given for illustrative purposes and should not be construed as limiting the invention.

Another aspect of the invention relates to a screw for use in an assembly according to the present disclosure. The screw comprises a countersunk head from which a threaded shank emanates that is adapted to be received and tightened in a cavity of a substrate part, wherein the countersunk head is at a shank side thereof provided with a cutting edge adapted to cut through an electrically insulating layer of a sheet metal part for grounding purposes when tightening the screw.

A preferred embodiment provides a screw wherein a cross-section of the cutting edge is triangle-shaped, a first leg of the triangle extending under an angle of between 30 and 60° with respect to a longitudinal direction of the shank, and a second leg of the triangle extending under an angle of between 0 and 30° with respect to the longitudinal direction of the shank. This embodiment is particularly successful in providing an electrical connection between the screw, the thin sheet metal part and the substrate part.

Yet another improved embodiment provides a screw wherein the first leg extends at a side facing the shank, and the second leg extends at a side facing away from the shank.

Another aspect of the invention relates to a sheet metal part for use in an assembly according to the present disclosure. The sheet metal part comprises an opening through which a shank of a screw may be provided, wherein an outer diameter of the opening is slightly larger than the diameter of a countersunk head of the screw, an inner diameter of the opening is slightly larger than the diameter of the shank, and wall parts of the sheet metal part extend from the outer diameter towards the inner diameter, which wall parts are deformed by the countersunk head of the screw upon tightening the screw. The invented thin sheet metal part permits providing a strong and reliable mechanical and/or electrical connection with a substrate part wherein the connection is countersunk, and preferably electrically conducting for grounding purposes. The embodiments of the invention described in the present disclosure may be combined in any possible combination of these embodiments, and each embodiment can individually form the subject-matter of a divisional patent application.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be further elucidated on the basis of several non-limitative embodiments, as shown in the attached schematic figures. In the figures:

Figure 1 represents a perspective view of a housing or rack according to an embodiment of the invention;

Figure 2 represents a detail of the rack shown in figure 1 comprising an assembly according to an embodiment of the invention;

Figure 3A represents a top view of an assembly comprising a sheet metal substrate according to an embodiment of the invention;

Figure 3B represents a cross-sectional view of the assembly shown in figure 3A;

Figure 3C represents a cross-sectional view of an assembly comprising a nut as substrate according to an embodiment of the invention;

Figure 3D represents a cross-sectional view of an assembly comprising a sheet metal substrate of which deformable wall parts have a reduced wall thickness, according to an embodiment of the invention;

Figure 4A represents a top view of a thin sheet metal part comprising an opening according to an embodiment of the invention;

Figure 4B represents a cross-sectional view of an assembly comprising a grooved frame part as substrate according to an embodiment of the invention;

Figure 4C represents a cross-sectional view of the assembly shown in figure 4B with a screw applied in accordance with an embodiment of the invention;

Figure 4D represents a cross-sectional view of the assembly shown in figure 4C after a screw has been removed in accordance with an embodiment of the invention;

Figure 5 represents a cross-sectional detailed view of an assembly wherein the screw is provided with a cutting edge, in accordance with an embodiment of the invention;

Figure 6 represents a top view of a thin sheet metal part comprising openings according to several embodiments of the invention; Figure 7 represents a perspective view of an assembly according to an embodiment of the invention in a connected state;

Figure 8 represents a perspective view of an assembly according to an embodiment of the invention in an unconnected state; and

Figures 9A and 9B finally represent a perspective view from below and from above of an embodiment of a screw for use in the invented assembly.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring to figure 1, a rack 1 according to an embodiment of the invention is shown. The rack 1 may be used for accommodating devices such as electrical, electronic and optical equipment (not shown). The rack comprises a rectangular floor 10 comprising four interconnected floor frame members 10a that extend between four floor corner elements 10b. Likewise, a rectangular roof 11 is provided, which comprises four interconnected roof frame members 11a that extend between four roof corner elements lib. The floor 10 and roof 11 are held at a vertical distance 13 from each other by vertically extending side frame members 12, each side frame member 12 being provided between a floor corner element 10b and a roof comer element 1 lb. The frame members 10a, 1 la and 12, and the corner elements (10b, 1 lb) together form a load bearing structure for accommodating equipment.

The roof 11 in the embodiment shown is provided with three contiguous roof plates 1 lc made from a thin sheet metal, preferably steel. The thin sheet metal plates 1 lc have a thickness of 1.0 mm, but may have another thickness not exceeding 2.1 mm. In the embodiment shown in figure 1, two vertically oriented mounting rails 14 are provided in between each pair of side frame members 12, at least in two side planes 15 of the rack 1. Each mounting rail 14 is at an end thereof connected to a floor frame member 10a, and a roof frame member 11a, according to known practice. The 19 inch mounting rails 14 extend parallel to each other at a mutual standardized distance 16 of typically 17.7 inches. Each mounting rail 14 is further provided with a plurality of square openings 14a, extending along a longitudinal direction 14b of each mounting rail 14, and provided at equal height between mounting rails 14. Standardized, suitable equipment may be provided with fixation lips to be connected to the openings 14a, for instance by screws. In this way, multiple units of equipment (not shown) may be suspended on top of each other in the rack 1. The mounting rails 14 may be provided with other openings 14c for the same purpose, or for connecting to auxiliary parts of the rack 1, such as stiffening brackets, side walls (not shown) and the like. The rack 1 may, apart from the roof plates 1 lc that together form a roof wall part, be provided with other wall parts, such as side wall parts or floor wall parts to form a substantially closed cabinet. Surfaces of the roof plates 1 lc may be provided with a protective electrically insulating layer, such as a powder coating layer 111, as specifically shown in figure 5. Such a layer 111 protects the roof plates 1 lc but, on the other hand, electrically insulates the roof plates 11c, which may not be desirable for grounding purposes.

Referring now to figure 2, a detail of a roof corner of the rack 1 is schematically shown. Each thin-walled roof plate 1 lc is provided with a plurality of openings 3 arranged along a side edge 110 of the roof plate 1 lc. Some of the openings are penetrable openings 5 having a shape in accordance with embodiments of the invention. Possible shapes of these penetrable openings 5 will be elucidated further below, for instance with reference to figure 6. A horizontal roof frame member 1 la forms a substrate for the thin-walled roof plate 1 lc to which it is mechanically and electrically connected by a screw 4.

As shown in more detail in figures 9A and 9B, a suitable screw 4 comprises a countersunk head 40 from which a threaded shank 41. The head 40 may be provided with a recess 42 for receiving a screw driver. The countersunk head 40 is at a shank 41 side thereof provided with a cutting edge 43 that cuts through an electrically insulating layer 111 of the thin-walled roof plate 11c when tightening the screw 4, as for instance shown in figure 5. This providing an electrical connection between the screw 4 and the thin-walled roof plate 1 lc for grounding purposes. In the embodiment shown, the cutting edge 43 of the countersunk head 40 of the screw 4 extends along a substantially complete circumference of the countersunk head 40 of the screw 4. In other embodiments (not shown), the cutting edge 43 may extend along a part of the circumference of the countersunk head 40 only, or may be provided as one or more cutting pins. Two or more cutting edges 43 or cutting pins may also be provided on different radii. As shown in figure 5, a cross-section of the cutting edge 43 is triangle- shaped, wherein a first leg of the triangle extends under an angle between 30 and 60° (about 45°) with respect to a longitudinal direction of the shank 41, and a second leg of the triangle extends under an angle of between 0 and 30° (about 15°) with respect to the longitudinal direction of the shank 41. The first leg extends at a side facing the shank 41, whereas the second leg extends at a side facing away from the shank 41.

As best shown in figure 7, the thin-walled roof plate 1 lc or another vertically extending wall plate 1 Id of the rack 1, may be connected to a roof frame member 1 la or another frame member (10a, 12) by providing the threaded shank 41 in a cavity of the substrate part, which in the embodiment shown is an, optionally threaded, groove 120 that extends in a longitudinal direction 12b of the side frame member 12. The shank 43 is received and tightened in the groove 120 to establish the connection between the vertically extending wall plate 1 Id and frame member 12. The frame member 12 mat also be provided with other grooves 121 that extend in the longitudinal direction 12b, for instance to attach a mounting rail 14 thereto.

Referring now to figure 6, top views of thin sheet metal parts, such as the thin-walled roof plate 1 lc, are shown whereby each thin-walled roof plate 1 lc comprises a penetrable opening 5 according to another embodiment of the invention. As schematically shown in figure 6X at the top right, each penetrable opening 5 is defined by an outer diameter 50 of the opening 5 which is slightly larger than a diameter 44 (see figure 9A) of the screw head 40, and an inner diameter 51 of the opening 5 which is slightly larger than a diameter 45 (see figure 9A) of the screw shank 41. The outer and inner diameters (50, 51) are easily selected when the diameter 44 of the screw head 40 and the diameter 45 of the screw shank 41 are known. In the embodiments shown in figures 6(A) to 6(M), the inner and outer diameters (50, 51) are reproduced without the numbering, for reasons of clarity. The shank 41 of the screw 4 is provided through the opening defined by the inner diameter 51. As shown in figures 6(A) to 6(M) for all the embodiments, wall parts 52 of the thin-walled roof plate 11c extend from the outer diameter 50 towards the inner diameter 51. Since these wall parts 52 occupy part of the area between the outer diameter 50 and the inner diameter 51, these wall parts will contact the countersunk screw head 40 and will be deformed by the countersunk screw head 40 upon tightening the screw 4 in the groove 120, or other cavity of the substrate. This deformation is shown in more detail in figures 3, 4, and 5 and will be elucidated further below. The deformable wall parts 52 may comprise lips that extend between the outer diameter 50 and the inner diameter 51. In the embodiment of figure 6(D), the deformable wall part 52 consists of one lip on a left side of the opening 5. Figures 6(A), 6(B), 6(C), 6(E), 6(H),

6(1), 6(J), and 6(K) show deformable wall parts 52 in the form of lips that are provided diametrically opposite to each other. The embodiments of figures 6(F) and 6(L) have three deformable wall parts 52, regularly arranged along the circumference of the penetrable opening 5. Figure 6(G) shows four deformable wall parts 52, regularly arranged along the circumference of the penetrable opening 5, while figure 6(M) shows a total number of eight deformable wall parts 52, regularly arranged along the circumference of the penetrable opening 5.

In some embodiments, such as those shown in figures 6(H) and 6(1), the wall of the sheet metal part, such as the thin-walled plate 1 lc, comprises weakened areas 54 in the form of removed wall parts, such as through-the-thickness holes. The weakened areas 54 facilitate the deformation of the adjacent deformable wall parts 52.

Referring now to figure 3A, a top view of an assembly is shown that comprises a sheet metal part such as the thin-walled plate 11c connected with a screw 4 to a substrate 6 which, in the present embodiment, is also a thin-walled sheet metal part 6. As shown in the cross-sectional view of figure 3B, the wall-parts 52 have been deformed while tightening the screw 4 in an, optionally threaded, cavity 60 provided in the sheet metal substrate 6. Please note that the thin-walled sheet metal substrate 6 is formed such that it comprises a a receiving space 61 in which the deformed wall parts 52 may be received when the screw 4 is tightened in the in opening 60.

Figure 3B shows yet another embodiment in which the substrate part comprises a nut 7, a central cavity 70 of which may be threaded to receive the shank 41 of the screw 4. A conically shaped upper part 71 of the cavity 70 provides a receiving space for the deformable wall parts 52.

The embodiment shown in figure 3D is similar to the embodiment of figure 3B, but differs therefrom in that the wall of the sheet metal part such as the thin- walled plate 11c comprises weakened areas 53 in the vicinity of the deformable wall parts 52, wherein the weakened areas 53 comprise a reduced wall thickness of the thin-walled plate 1 lc. The reduced wall thickness facilitates the deformation of the adjacent deformable wall parts 52 by the countersunk head 40 upon tightening the screw 4.

Figure 4 A represents a top view of the thin- walled plate 11c comprising a penetrable opening 5 according to one embodiment of the invention. As shown in figure 4B, this embodiment comprises an assembly that comprises a grooved frame part 12 as substrate part, such as the one also shown in figure 7. Please note that the groove 120 (see figure 7) is not visible in the side view of figures 4B to 4D, since it extends in the longitudinal direction 12b of the frame member 12. In figure 4A, the thin-walled plate 1 lc is shown to be positioned onto or against the grooved frame part 12. The deformable wall parts 52 are still not deformed and extend in a plane of the thin-walled plate 11c. In the situation shown in figure 4C, a screw 4 has been driven into the groove 120 which caused the deformable wall parts 52 to actually deform under the action of the screw head 40. The deformation is seen to approximately follow the shape of a shank- side face of the screw head 40, which may be conical for instance. The deformed wall parts 52 are received in the groove 120 which extends from left to right in figures 4B to 4D.

Figure 5 represents a situation in which the screw 4 was removed from the groove 120 to for instance release the thin-walled plate 1 lc from the grooved frame part 12. As shown, the deformed wall parts 52 have been plastically (or permanently) deformed by the countersunk head 40 when the screw 4 was tightened in the groove 120. This deformation may be described as a bending of the deformable wall parts 52 around the outer diameter 50 of the penetrable opening 5.

It will be apparent that many variations of the above described embodiments may be envisaged by one skilled in the art within the scope of the invention as determined by the attached claims.