HK1028301B - A device for contacting in particular elongated, illustratively substantially cylindrical bodies such as cables or pipes/tubes - Google Patents

Description

Device for contacting, in particular, oblong cylindrical objects such as cables or pipes/tubes

The invention relates to a device for contacting especially long, for example cylindrical, objects such as cables or pipes or tubes, hereinafter the term "pipe" also includes the meaning of "tube".

Such devices are used, for example, to connect the bare outer conductor of a metal pipe or coaxial cable to a ground cable.

European patent document No. 0,744,788 discloses a device of the above type, which comprises a basic structure for abutting against an object to be contacted and a contact element for making an electrically conductive connection with the object to be connected, which contact element is mounted on the side of the basic structure facing the object to be contacted in the mounted position. In this known device, the basic structure comprises a band-shaped metal clip embedded in an elastic material, leaving a contact surface for receiving the contact element on the side facing the object to be contacted in the assembled position. The contact element of this known device is a copper braid which is manually attached or spot welded to the contact surface of the base structure using an adhesive. The contact elements are substantially rectangular in top view and have longitudinal edges which are substantially parallel to adjacent edges of the basic structure in the desired position of arrangement.

A disadvantage of this known device is that the contact piece may slide during its arrangement, in which position on the basic structure its longitudinal edge will not be parallel to the edge of the basic structure but inclined with respect thereto, which is disadvantageous, so that the contact piece projects laterally from the basic structure. The required contact between the contact and the contacted object may not be achieved as desired when assembling the prior art device. In this case, the contact must be released from the base structure and then fixed again in the desired position. This repeated work is time consuming and costly.

The object of the present invention is to provide a device of the kind described in the preamble of claim 1 which does not have the disadvantages of the known devices and facilitates the arrangement of the contact elements in a desired fixed position on the basic structure.

The above object is achieved by means of the solution according to claim 1.

The basic idea of the invention is to provide an adjustment device which can adjust the position of the contact piece with respect to the edge of the basic structure. In this way, it is possible to reliably prevent the contact pieces from sliding and protruding beyond the edge of the base structure when the contact body is fixed to the base structure in the production of the device according to the invention, thus facilitating production, saving time and saving costs for the repair work.

The device of the invention has simple structure, easy manufacture, low cost and wide applicability.

The above-mentioned adjusting means can be designed in a number of ways. For example, the adjustment means can be optical, for example markings on the basic structure, but it is also possible to suitably arrange at least one abutment edge or at least one abutment surface, which in the fixing mode is inclined to the fixing surface of the contact on the basic structure. The abutment edge or surface can adjust the position of the contact piece relative to the edge of the basic structure and thus make it easier to fix it in a desired fixed position.

In principle, the adjusting device is provided with only one abutment edge or abutment surface, so that it is sufficient for only a part of the edge of the contact piece to abut against the abutment edge or abutment surface. In an advantageous embodiment, however, at least two mutually spaced abutment edges or surfaces are provided in order to support the contact piece in the mutually spaced regions of its edges. For example, for a contact that is substantially rectangular in top view, two abutting edges that are substantially parallel to and spaced apart from each other may be used. The contact piece in the fixed position has two opposite regions of its edge abutting against one abutment edge, respectively. Alternatively, abutting edges forming an angle therebetween, such as a right angle, may be used. In this case, adjacent regions of the edge of the contact abut against the abutment edge. It is also possible to use four abutment edges, supporting the contact on opposite regions of its edge.

In a particularly advantageous embodiment of the invention, the adjusting device is a centering device for centering the contact piece between the opposite edges of the basic structure. In this way, the contact is centered between the edges of the basic structure, the centering of the contact being further simplified.

In another variant of the above embodiment, the centering means are provided with abutment edges spaced from each other, substantially parallel to each other and to adjacent edges of the basic structure. In this variant, the substantially rectangular contact piece is fixed in position in a top view substantially parallel to the edges of the basic structure and is thus centered.

In another embodiment, the centering device is provided with oppositely inclined abutment surfaces spaced apart from each other, extending in the longitudinal direction and in the circumferential direction of the basic structure, supporting the fixing element in a fixed position. In this embodiment, the centering of the contact piece is also carried out in the desired manner.

In a variant of the above embodiment, the abutment surfaces are inclined away from each other. In this way a groove is formed in the abutment surface which receives the contact. However, in another variant, the abutment surfaces may also be inclined towards each other. In such a variant, the abutment surfaces may, for example, straddle opposite edges of the contact.

The shape, size or number of abutting edges or surfaces may be selected within a wide range. The or each abutment edge is adapted to be formed on a projection, particularly a stud or rib, on the primary structure. This variant is simple and inexpensive.

In principle the or each post or rib may be formed from a separate piece attached to the base structure. In an advantageous variant, however, the basic structure is made of an elastic material, preferably an elastomer, into which the or each stud or rib is incorporated. Thus, the or each post or rib is integral with a part of the basic structure. This feature simplifies the manufacture of the device of the invention. In this variant, if two mutually spaced abutment edges are provided, the contact can be clamped between the elastically deformed abutment edges and elastically fixed in position when the spacing between the abutment edges of the contact is appropriately selected. Therefore, additional fixing means such as adhesive or welding for fixing the contact are no longer required.

In another embodiment the basic structure is provided with a recess, the edge of which constitutes the or each abutment edge, or the slope of which constitutes the or each abutment surface. This embodiment also ensures a precise adjustment of the contacts. In addition, the embodiment has simple structure and low manufacturing cost.

In principle, it is sufficient that a section of the contact edge is abutted by the abutment edge or surface. In a particularly advantageous variant of the invention, the shape of the recess substantially corresponds to the shape of the contact piece, so that the contact piece is held in the recess in a snug manner. In this variant, the contact piece eliminates the sliding phenomenon in a particularly reliable manner.

The material of the basic structure can be selected within wide limits. The basic structure may also consist of several materials. In one embodiment, the base structure comprises a strip-shaped metal part. The strip-shaped metal part improves the dimensional stability of the basic structure. With the above-described embodiment, the concave portion may be formed on the side of the metal portion that faces the contacted object when in the assembled position. For example, the metal part can be made of sheet metal, while the recess only has to be pressed out, making the manufacture simpler.

In a variation of the above embodiment, the recess is in the form of a ring or a recessed area. Such recesses can be pressed into the metal parts of the basic structure by means of a stamping tool in any shape and size.

In principle, it is sufficient if the basic structure is formed by a strip-shaped metal part. However, in embodiment variants comprising a resilient part, the metal part is at least partially covered with a resilient material, in particular on the side facing the contacted object in the assembled position, or the metal part is embedded in a resilient material, leaving a contact area on the side facing the contacted object in the assembled position of the metal part. The use of elastomeric materials can provide a better appearance to the device of the present invention or protect or insulate the metal parts from environmental elements.

The shape and size of the contact can be selected within wide limits. The contacts are suitably constructed from flat twisted wires or flat tapes or braids of metal. The contact is easy and inexpensive to manufacture.

The shape and dimensions of the basic structure can be chosen within wide limits. For example, the base structure may be a plate that contacts a planar object, or it may be curved to contact a curved object.

A particularly advantageous embodiment of the contacting conduit or cable of any cross-section provides a basic structure which, when in the assembled position, encloses the contacted object in an annular or sleeve-like manner. In this embodiment the basic structure is reliably fixed to the contacted object.

The basic structure is in principle rigid, but it is preferably made flexible to facilitate assembly.

The basic structure can be divided into several parts. For example, the means for contacting the conduit may be constituted by several, for example two, portions which are continuous along the circumference of the conduit to be contacted. However, the basic structure is preferably integral and open in the circumferential direction, the free ends of which are provided with brackets which are preferably connected to each other in the assembled position using screws or clips. The device of the invention is simple to assemble due to the monolithic design of the basic structure of this embodiment.

In another variant of the invention, the basic structure is in the form of a band which can be fastened around the contacted object. This feature also facilitates assembly.

With respect to embodiments comprising several studs or ribs provided with abutting edges or surfaces, it is basically sufficient that all studs or ribs extend from one edge of the basic structure to the other. In an advantageous variant, however, at least one stub or rib respectively extends from one edge to the other in two opposite edge regions, so that the contact piece abuts against the stub or rib with the two opposite regions of its edge in the fixing position. In this variant, the contact piece is centered between the studs or ribs.

In the embodiment variants of the invention using stubs or ribs, the stubs or ribs which are continuous in the longitudinal and circumferential directions of the basic structure are respectively arranged on different lines extending in the longitudinal direction of the basic structure or respectively on different lines extending in the circumferential direction of the basic structure. In this variant, a stub or rib continuous in the longitudinal or circumferential direction of the basic structure secures the contact piece on the opposite area of the edge of the contact piece, so that centering is achieved.

In a variant of the above-described embodiment, at least two stubs or ribs are respectively arranged along a line perpendicular to the longitudinal direction of the basic structure or on a line extending in the axial direction. In this embodiment, the contact piece rests with its edge regions perpendicular to its longitudinal direction against the studs or ribs, so that the centering is further improved.

In a particularly advantageous embodiment of the invention, at least two of the stubs or ribs of the support contact are provided with undercuts in the assembled position, with the abutment surfaces formed being inclined towards one another, with the stubs or ribs overlapping the opposite edge regions of the contact in the secured position by means of said abutment surfaces. In this embodiment, the contact piece is fixed in a geometrically locked manner by means of the abutment surfaces of the studs or ribs, so that no further fixing means, such as adhesive, are required. This feature simplifies manufacturing and reduces costs.

Finally, with regard to the embodiment involving a metal part, a variant provides that the metal part is provided with at least one hole, preferably with a resilient material passing through on each side of the contact, so that the resilient material on the side of the metal part facing the contact is connected to the resilient material on the side of the metal part facing away from the contact. In this way, the resilient material on the side of the metal part facing the contact is protected from detaching from the metal part. If the contact is simply secured to the metal portion by an elastic material, such disengagement may compromise the electrical contact between the contact and the metal portion.

The invention will now be described with reference to the accompanying drawings, which illustrate embodiments.

Fig. 1 is a schematic perspective view of a first embodiment of the device of the present invention in the form of a clip.

Fig. 2 is a view of the radially inner surface of the device of fig. 1 without the contact member.

Fig. 3 is a view similar to fig. 2 of the device of fig. 2, with the contacts fixed in a basic configuration.

Fig. 4 is a cross-sectional view along line IV-IV of the device of fig. 3 in an assembled position.

Fig. 5 is a schematic perspective view of the device of fig. 1 in an assembled position.

Fig. 6 is the same view as fig. 3 of a second embodiment of the apparatus of the present invention.

Fig. 7 is the same view as fig. 3 of a third embodiment of the apparatus of the present invention.

Fig. 8 is the same view as fig. 4 of a fourth embodiment of the apparatus of the present invention.

Fig. 9 is a cross-sectional view of the inventive device of fig. 8 taken along line IX-IX.

Fig. 10 is the same view as fig. 3 of a fifth embodiment of the device of the present invention.

Fig. 11 is the same view as fig. 3 of a sixth embodiment of the device of the invention without the contact.

Fig. 12 is a sectional view taken along line XII-XII in fig. 11.

FIG. 13 is the same view as FIG. 11 of the device of FIG. 11 with the contacts secured against the base structure.

Fig. 14 is a sectional view taken along the line XIV-XIV in fig. 13.

Fig. 15 is the same view as fig. 12 of a seventh embodiment of the device of the present invention.

The same reference numbers are used in the drawings for the same or corresponding parts.

Fig. 1 shows a first embodiment of the device 2 according to the invention, which comprises a flexible basic structure 4 in the form of a clip, which basic structure is in this embodiment one-piece, open in the circumferential direction, and is provided at its free ends with substantially vertical brackets 6, 8, which can be connected in the manner described below when in the assembled position.

The basic structure 4 comprises a strip-shaped metal part 10 and a resilient part 12, which in this case is made of elastomer, which embeds the metal part 10 with its axial edges and in this way connects the metal part 10 with the resilient part 12 (fig. 4).

The side of the resilient part 12 facing the contacted object in the assembled position forms sealing lips 14, 16, and additional sealing lips 18, 20 are formed outside the sealing lips 14, 16. In the assembled position, the basic structure 4 bears in a sealing manner against the outer surface of the contacted object by means of the sealing lips 14, 16 and the additional sealing lips 18, 20, so that the space formed between the contacted object and the basic structure 4 in the assembled position is sealed against the ingress of air and/or moisture.

The device 2 further comprises a contact piece, not shown in fig. 1, for electrically conductive connection with the object to be contacted, which contact piece, not shown, when in the assembled position, is fixed, for example by gluing, on the side of the contact position facing the object to be contacted (with respect to the embodiment shown in fig. 1), on a radially inner surface 22 of the basic structure 4 forming the fixing zone.

The device 2 also comprises adjustment means for adjusting the position of the contact piece relative to the axial edges 24, 26 of the basic structure 4, which in this case are constituted by abutment edges 28, 30, 32 formed on stubs 34, 36, 38 which are integral with the sealing lips 14, 16 of the resilient part 12.

The studs 34, 36 extend axially inwardly from an axial edge of the basic structure 4, while the stud 38 extends axially inwardly from the opposite axial edge 26, the studs 34, 36 being formed on a circumferential line 33, the stud 38 being formed on a circumferential line 35 which is axially offset from the circumferential line 33.

Fig. 2 is a view of the radially inner surface 22 of the device 2.

Fig. 3 shows the device 2 with a contact 40, which in this case is made of electrically conductive graphite and is rectangular in top view. The contact member 40 is glued to the radially inner surface 22 of the basic structure 4.

As shown in fig. 3, the contact element abuts, by means of opposite regions of its edge, against the abutment edges 28, 30, 32 of the stubs 34, 36, 38, which form centering means in order to center the contact element 40 between the opposite axial edges 24, 26 of the basic structure 4. The abutment edges 28, 30, 32 ensure that the contact is held in the desired position against the basic structure, with its longitudinal edges extending substantially perpendicularly to the axial edges 24, 26 of the basic structure 4 and ensure that the contact does not protrude laterally. In this way, time waste and increased finishing costs can be avoided, which can occur if the contact piece 40 is no longer in the desired fixed position.

Fig. 4 shows a section along the line IV-IV in fig. 3, in which the basic structure 4 abuts against the contacted object, which in fig. 4 is a coaxial cable, by means of the sealing lips 14, 16 and the additional sealing lips 18, 20 in the assembled position of the device 2. In order to make contact with the exposed outer conductor 44 of the coaxial cable 42 in the contact region 46, the contact piece 40 projects radially towards the coaxial cable 42, which abuts the exposed outer conductor 44 when the sealing lips 14, 16 and the additional sealing lips 18, 20 abut the outer jacket 48 of the coaxial cable, thus forming an electrically conductive connection therewith.

As shown in fig. 4, the contact 40 is held snugly by the stubs 34, 38 at the opposite regions of its edges and is thus centered in the desired fixed position between the axial edges 24, 26 of the basic structure 4.

As shown in fig. 5, the device 2 of fig. 1 is in the assembled position, the basic structure 4 surrounding the contacted coaxial cable 42 like a sleeve. To secure the device 2 to the coaxial cable 42, the basic structure 4 in the form of a clip is tensioned around the coaxial cable 42 by means of metal screws 50, 52, which screws 50, 52 pass through holes in the bracket 8 and engage with threaded holes in the bracket 6. When the basic structure 4 is tensioned, the sealing lips 14, 16 and the additional sealing lips 18, 20 bear in a sealing manner against the outer jacket 48 of the coaxial cable 42, thereby sealing the space formed between the coaxial cable 42 and the basic structure 4 in the assembled position against the ingress of air and/or moisture.

When the basic structure 4 is tensioned, the contact 40 abuts against the bare outer conductor 44 of the coaxial cable 42, whereby the contact 40 completes the electrically conductive connection between the outer conductor 44 and the metal part 10 of the basic structure 4. The metal part 10 projecting into the brackets 6, 8 makes an electrically conductive connection with a conductor, such as the grounding cable 54 shown in fig. 5. For this purpose, the ground cable 54 can be connected to the screw 50 by means of a connecting sleeve. Thus, an electrically conductive connection is made between the ground cable 54 and the outer conductor 44 of the coaxial cable 42 in a desired manner to ground the outer conductor 44.

Fig. 6 shows a second embodiment of the device 2 of the invention, which differs from the embodiment shown in fig. 1 to 5 in that: the abutment edges 28, 32 are formed on ribs 56, 58 which are substantially parallel to the adjacent axial edges 24, 26 of the basic structure 4. As shown, the resilient portion 12 may be disposed about the axial edges 24, 26 of the base structure 4 to form ribs 56, 58. As shown, the contact 40 is centered between the axial edges 24, 26 of the basic structure 4 by the opposing regions of its edges abutting the ribs 56, 58 over its entire length.

Fig. 7 shows a third embodiment of the device 2 of the invention, which differs from the embodiment shown in fig. 6 in that: a rib 60, which is substantially U-shaped in top view, is formed on the radially inner surface 22 of the basic structure 4 in the region of the carrier 6, the rib surface facing the contact element 40 constituting an abutment edge 62, 64, 66 for receiving the contact element 40 in the assembled position, the contact element 40 being centered between the opposite axial edge 24, 26 and the opposite circumferential edge 68, 70 of the basic structure 4.

Fig. 8 shows a fourth embodiment of the device 2 according to the invention, which differs from the previous embodiments in that: the adjustment means comprise abutment surfaces constituted by the ramps 74, 76 of the collar 72, the collar 72 extending in the circumferential direction of the basic structure 4.

Fig. 9 shows that the mutually facing ramps 74, 76 of the ring 72 constitute abutment surfaces for the contact element 40 and are spaced apart from one another in the axial direction of the basic structure, so that the contact element 40 abuts tightly against the ramps 74, 76 in such a way that the contact element 40 is centered between the axial edges 24, 26 of the basic structure 4. A recessed area shaped to substantially match the contact 40 may be substituted for the collar 72 so that the edge of the contact 40 is closely received in the recessed area and thereby centered.

Fig. 10 shows a fifth embodiment of the device 2 of the invention, which differs mainly from the embodiment shown in fig. 6 in that: it includes a rib 56 with which the abutment edge 28 abuts against the contact member. In order to fix it in place, the contact piece 40 can be glued to the radially inner surface of the base structure 4 in its edge region remote from the rib 56 by means of a linearly applied adhesive, which is indicated by the broken line 77 in fig. 10. Instead of a linear adhesive, one or more adhesive dots may be used as the adhesive means.

Fig. 11 shows a sixth embodiment of the device 2 according to the invention, which differs from the embodiment shown in fig. 3 in that: it comprises two stubs 80, 78, the stub 80 extending from the axial edge 26 of the basic structure 4 to the opposite axial edge 24, and the stub 78 extending from the axial edge 24 to the axial edge 26. The struts 80, 78 are formed substantially along a straight line extending in the axial direction of the base structure 4.

Fig. 12 shows that the stubs 80, 78 are provided with undercuts (undercuts) 81, 82, with oppositely inclined abutment surfaces 84, 86 being formed on the stubs 80, 78, with which the stubs overlap the opposite areas of the edge of the contact element 40 when in the secured position, as is also shown in fig. 13 and 14. In order to fix the contact element 40 (which in the present embodiment is a flat flexible metal braid) on the basic structure 4, the structure is inserted with its edges 88, 90 and possible elastic deformation of the stubs 80, 78 into the area of the undercuts 81, 82, so that the stubs 80, 78 overlap the edges 88, 90 of the contact element 40 and the abutment surfaces 84, 86 abut against the contact element 40. In this way, the contact 40 can be reliably held on the basic structure 4 and centered between the axial edges 24, 26 of the basic structure 4 without additional fixing means, such as adhesive.

Fig. 15 shows a seventh embodiment of the device 2 according to the invention, which differs essentially from the embodiment shown in fig. 12 in that: the metal part 10 on both sides of the contact 40 (not shown in fig. 15) comprises holes 88, 90 through which the elastic material of the part 12 passes, so that the elastic material on the side of the metal part 10 facing the contact 40 is connected to the elastic material on the side of the metal part 10 facing away from the contact 40. In this way, a permanent electrically conductive connection between the metal part 10 and the contact 40 can be ensured even when the contact is fixed to the metal part 10 without additional fixing means.

Claims (25)

1. Device for electrically contacting, in particular, an elongated, for example substantially cylindrical, object, such as a pipe or a cable, comprising a basic structure (4) for abutting against the object (42) to be contacted, a contact element (40) being fixed to the side of the basic structure (4) facing the object (42) to be contacted for electrically conductive connection to the object (42) to be contacted, characterized in that: the adjustment device adjusts the position of the contact piece (40) relative to the edges (24, 26) of the basic structure (4).

2. The apparatus of claim 1, wherein: the adjusting device comprises at least one abutment edge (28, 30, 32) or at least one abutment surface inclined with respect to a fixing surface on which the contact piece (40) is fixed to the base structure (4), the contact piece (40) abutting against the at least one abutment edge or the at least one abutment surface.

3. The apparatus of any of claims 1 and 2, wherein: at least two mutually spaced abutment edges (28, 30, 32) or abutment surfaces (84, 86) are used, against which the contact piece (40) abuts by means of mutually spaced-apart regions of its edges.

4. The apparatus of claim 1, wherein: the adjustment device comprises a centering device for centering the contact piece (40) between the opposite edges (24, 26) of the basic structure (4).

5. The apparatus of claim 4, wherein: the centering device comprises mutually spaced abutment edges (28, 32) which extend substantially parallel to each other and to adjacent edges (24, 26) of the basic structure (4).

6. The apparatus of claim 4, wherein: the centering device comprises mutually spaced abutment surfaces (84, 86) which are inclined relative to each other and extend in the longitudinal or circumferential direction of the basic structure (4) and against which the contact piece (40) is to be brought into abutment in a fixed position.

7. The apparatus of claim 6, wherein: the abutment surfaces are inclined away from each other or the abutment surfaces (84, 86) are inclined towards each other.

8. The apparatus of claim 2, wherein: each of said abutment edges (28, 30, 32) or abutment surfaces is formed on a projection, in particular a stud (34, 36, 38) or a rib (56, 58, 60), on the basic structure (4).

9. The apparatus of claim 8, wherein: the basic structure (4) comprises a portion (12) of elastic material, preferably elastomer, with which each of said studs (34, 36, 38) or ribs (56, 58; 60) is integral.

10. The apparatus of claim 2, wherein: the basic structure (4) comprises a recess whose edge constitutes the or each abutment edge (28, 30, 32) or whose slope constitutes the or each abutment surface (62, 64, 66).

11. The apparatus of claim 10, wherein: the shape of the recess substantially matches the shape of the contact (40), so that the contact (40) is snugly secured in the recess.

12. The apparatus of claim 10, wherein: the basic structure (4) comprises a metal part (10) in the form of a strip.

13. The apparatus of claim 12, wherein: the recess is formed on the side of the metal part (10) facing the contacted object (42) in the assembling position.

14. The apparatus of claim 13, wherein: the recess is formed by a ring (68) or by a recessed area.

15. The apparatus of any one of claims 12 to 14, wherein: the metal part (10) is at least partially covered with an elastic material, in particular on its side facing away from the contacted object (42), or the metal part (10) is embedded in an elastic material, leaving a contact area of the contact piece (40) on the side of the metal part (10) facing the contacted object (42) in the assembled position.

16. The apparatus of any preceding claim, wherein: the contact (40) is formed from a flat twisted wire or flat ribbon or braid of metal.

17. The apparatus of any preceding claim, wherein: the basic structure (4) is configured such that, in its assembled position, it encloses the object (42) to be contacted, in particular in an annular or sleeve-like manner.

18. The apparatus of claim 1, wherein: the basic structure (4) is flexible.

19. The apparatus of claim 1, wherein: the basic structure (4) is integral, open in the circumferential direction and comprises brackets (6, 8) at its free ends, which brackets can be connected to each other in the assembled position, preferably by means of screws or clips.

20. The apparatus of claim 1, wherein: the basic structure (4) is a clamp which can be tensioned around the contacted object.

21. The apparatus of claim 8, wherein: at least one stud (34, 36; 38) extends from the region of one of the two opposite edges (24; 26) of the basic structure to the other edge (26; 24) so that the contact, in the assembled position, abuts against the stud (34, 36, 38) by means of the two opposite regions (88, 90) of its edge.

22. The apparatus of claim 8, wherein: the stubs (34, 36, 38) which continue in the longitudinal or circumferential direction of the basic structure (4) are arranged on different lines or on different circumferential lines (33, 35) of the longitudinal extension of the basic structure.

23. The apparatus of claim 21, wherein: at least two stubs (76, 78) are arranged on a line perpendicular to the longitudinal direction of the basic structure (4), i.e. on an axial line.

24. The apparatus of claim 21, wherein: at least two of the stubs (76, 78) against which the contact piece (40) abuts by means of regions (88, 90) of opposite edges thereof in the assembled position comprise undercuts, abutment surfaces (84, 86) which are inclined towards one another being formed on the relevant stub (76, 78), by means of which the stub (76, 78) overlaps an opposite region (88, 90) of an edge of the contact piece (40) when in the assembled position.

25. The apparatus of claim 12, wherein: the metal part comprises at least one hole (88), preferably on both sides of the contact piece (40), at least one hole (88, 90) being penetrated by the elastic material, so that the elastic material on the side of the metal part (10) facing the contact piece (40) is connected to the elastic material on the side of the metal part (10) facing away from the contact piece (40).