EP2228503A1 - Paneel - Google Patents

Abstract

The panel (1) has an elongate locking element located within a groove on a connection area and moved relative to the groove. A protrusion is provided at another connection area for interacting with the locking element, such that the protrusion acts against or onto the locking element. The locking element engages an undercut of the latter connection area, such that the undercut is locked in horizontal- and/or vertical directions. A strip-type stop element (17) is provided in an area of the groove, for clamping the locking element in the longitudinal direction.

Description

The invention relates to panels according to the preambles of claims 1, 5, 8 and 9.

Panels of the aforementioned type are for use in the floor, wall or ceiling area. The known panels are provided with complementary first and second connecting portions provided on opposite sides for connection to adjacent panels. In this case, a groove and at least one in the groove, with the groove unconnected, opposite the groove movable and elongated locking element is provided, wherein on the second connection portion a projection for cooperation with the locking element are provided such that upon assembly of the projection against or acts on the locking element and the locking element engages behind an undercut of the second locking portion, so that there is a locking in the horizontal and / or vertical direction. The aforementioned edge profiling can be provided on both the long and the short sides in a panel, which usually has an elongated rectangular shape in plan view. Usually, the aforementioned first and second connection areas with the locking element are provided on the short sides of the panel. Examples of panels of the aforementioned type with locking elements are in the present text in the Fig. 1 to 10 (from the WO 2007/008139 ) Fig. 11 (from the DE 101 38 285 A1 ) FIGS. 12 and 13 (from the US 2007/0028547 A1 ) or FIGS. 14 and 15 (from the DE 20 2006 019869 U1 ).

With regard to the manner of the design of the panels with the locking elements and the mode of operation for locking is specifically made to avoid repetition of the above prior art and this insofar made the subject of the present application.

In the known panels, it is so that the locking elements inserted into the groove of the first connection region after insertion of the respective locking element in the groove can move out of the groove again. This can already happen during the manufacturing process, but especially during handling for laying the panels.

Object of the present invention is therefore to remedy this situation.

In a first alternative according to the invention is provided to solve the above problem that in the region of the groove at least one stop for locking the locking element in the longitudinal direction of the groove is provided, Preferably, the stopper is formed so that the locking element on neither one nor the other End of the groove in the longitudinal direction of the groove can escape from this. In a structurally very simple embodiment, two stops are ultimately provided within the groove in each case at the ends of the groove, which prevent the exit of the locking element from the groove.

In a preferred embodiment of the present invention, it is provided that the locking element extends only over a partial region of the length of the groove. In the partial region in which the locking element is located, the groove has a cross section complementary to the cross section of the locking element. As a result, the necessary locking movement of the locking element is ensured when joining two complementary connection areas.

The groove of the first connection region is usually realized in that corresponding milling tools are guided along the relevant front side of the panel. The stop can now be formed in a particularly simple manner in that the groove has a reduced cross-section at its two ends to form the stop in the longitudinal direction of the groove. Manufacturing technology, it is only necessary that an area of the milling tool is moved away from the relevant end face, so that there is the reduced groove cross-section in this area. This embodiment has the significant advantage that it can be easily integrated into the production process and no additional components for the end-side closure of the groove are required. Nevertheless, alternatively or be provided in addition that the groove has at least one end of a closure element to form a stop in the longitudinal direction of the groove. The closure element is then a separate component, which is preferably inserted into the groove at both ends.

As an alternative or in addition to the aforementioned embodiments, it can also be provided that at least one slot extending transversely to the longitudinal direction of the elongate locking element is formed on the locking element, wherein a locking means held in the first connection region and projecting through the slot is provided. The locking means may be, for example, a nail, pin, screw or a bolt. In the manufacture of the panels, the locking element is inserted into the groove and then the locking means introduced through the transverse slot in the groove (or vice versa), wherein the locking means ultimately represents a stop in the longitudinal direction, but allows movement of the locking element in the locking direction.

In an alternative embodiment it is provided that the locking element is held frictionally engaged in the groove to its locking in the longitudinal direction of the groove. In a preferred embodiment of this inventive concept it can be provided that in the groove of the first connecting portion at least partially a covering with a relation to the surface of the groove increased friction coefficient is provided. In principle, the covering can also project beyond the complementary cross-section of the groove, which results from the shape of the locking element.

In an alternative embodiment of the aforementioned inventive concept, a force acting on a part of the surface of the groove spring leg is provided on the locking element, so that results in increased movement of the locking element in the longitudinal direction of the groove. Moreover, it goes without saying that it is also possible in principle, in the sense of a "kinetic reversal" to provide a corresponding possibly resilient projection in the groove, which cooperates with the locking element accordingly.

In a further alternative embodiment it is provided that the locking element has on its groove facing the outside at least one projection for engagement in a corresponding slot in the groove, wherein the slot is aligned at least substantially transversely to the longitudinal direction of the groove. Slot and projection are designed such that the locking movement is easily possible when inserting corresponding panels.

In another alternative, the invention provides that the locking element with at least one locking means provided on the first connection area is releasably connectable. After the connection with the locking means ultimately results in this embodiment, a locking of the locking element in the longitudinal direction of the groove. Incidentally, in this embodiment, however, for the first time allows a lock, wherein the locking takes place via two separate components, namely on the one hand on the locking element, which realizes the locking when joining two panels, and on the other via the provided on or in the first connection region locking means , In a preferred embodiment of the aforementioned alternative, the locking means extends over at least a portion of the length of the groove. Preferably, the length of the locking means corresponds at least substantially to the length of the locking element, in which case a plurality of connection points can then be provided on the locking means, which interact with a plurality of corresponding connection points on the locking element. Finally, the locking means is a kind of elongated strip which cooperates with the elongated locking element accordingly.

In order to securely fasten the locking means in the region of the groove of the first connecting region, the locking means has a plug-in region for insertion into a slot in the groove and a coupling region for detachable connection to the locking element. The slot in the groove is ultimately a slot extending in the longitudinal direction of the groove, which can be realized in the production of the groove. Subsequently, the locking means is inserted with the insertion in the groove, so that the coupling region protrudes beyond the groove, with the coupling region then the connecting element is to be releasably connected.

To achieve a good connection of the locking means with the panel element, the insertion region has a plug-in leg with at least one outside projection, in particular in the form of a lamella. Preferably, a multiplicity of lamellae are provided which ensure good frictional engagement after the insertion region has been inserted. Alternatively or in addition to the aforementioned embodiment, the insertion region can also be adhesively bonded or glued to the longitudinal slot.

To realize the detachable connection between the locking means and the locking element, the coupling region has at least one coupling projection for engagement in a corresponding slot running transversely to the longitudinal direction of the locking element on the locking element. Through the transverse slot in the locking element ensures that the locking movement is easily possible when joining panels together. Moreover, in this connection, it is preferable for the coupling projection to have a head which engages over the slot, wherein the transverse slot has a broadened head opening for insertion of the head, in particular at the end. Ultimately, it can first be ensured by the aforementioned opening that the head of the coupling projection can be inserted into the slot. The widened head opening then ensures that the locking element is securely held on the locking means.

Preferably, the locking means is strip-shaped and in particular made of flat material, so that a cost-effective production is possible.

In a particularly simple embodiment, in particular in conjunction with a locking means made of flat material, it makes sense to form the coupling projection T-shaped, wherein the transverse slot is then formed accordingly and in this case has a transverse insertion slot as the head opening. It is understood that in a different kind Training the head of the coupling projection of the insertion slot is designed adapted accordingly.

The aforementioned alternative according to the invention with locking means and locking element can in principle be realized in all panel elements, regardless of the cross-sectional shape of the groove. Due to the detachable connection of the locking element with the locking means, a different type of groove cross-sectional shape can now be realized for the first time. According to the invention it is provided in a preferred embodiment that the groove has such a stop-free for the locking element cross-sectional shape such that the locking element without connection to the locking means can be removed transversely to the longitudinal direction of the groove from the groove. It is understood that with the removability, a process is meant in which the locking element without damage and in its original form, so not pressed or compressed, the groove can be removed. The aforementioned embodiment is particularly suitable for an embodiment in which the groove has a circular cross section and extends over an arc angle of less than 180 °. This is an essential difference from the prior art, since there are usually groove sections are provided with an arc angle of more than 180 ° to hold the locking element in the groove. With regard to the locking means, this is not required in the present invention.

Fig. 1 bis 15

bekannte Paneelen mit Verriegelungselementen,

Fig. 16 bis 25

Ansichten mehrerer Ausüthrungsformen von Paneelen mit unterschiedlich ausgebildeten Verbindungsbereichen und Verriegelungselementen,

Fig. 26

eine schematische Ansicht eines Teils einer erfindungsgemäßen Paneele,

Fig. 27

eine Ansicht entlang des Schnitts A aus Fig. 26

Fig. 28

eine Ansicht entlang des Schnitts B aus Fig. 26

Fig. 29 bis 31

Ansichten einer weiteren Ausführungsform entsprechend der Darstellung gemäß den Fig. 26 bis 28,

Fig. 32 bis 34

Ansichten einer weiteren Ausführungsform entsprechend der Darstellung gemäß den Fig. 26 bis 28,

Fig. 35 bis 37

Ansichten einer weiteren Ausführungsform,

Fig. 38 bis 39

Ansichten einer weiteren Ausführungsform,

Fig. 40

eine Ansicht eines Arretierelementes,

Fig. 41

eine Seitenansicht des Arretierelementes aus Fig. 40,

Fig. 42

eine schematische Querschnittsansicht eines ersten Verbindungsbereichs eines Paneels,

Fig. 43

eine der Fig. 42 entsprechende Ansicht mit eingesetztem Arretierelement und

Fig. 44

eine schematische perspektivische Ansicht eines Verriegelungselementes zum Einsetzen in einen Verbindungsbereich gemäß Fig. 43.

Further features, advantages and possible applications of the present invention will become apparent from the following description of embodiments with reference to the drawings and the drawing itself. All described and / or illustrated features alone or in any combination form the subject matter of the present invention, regardless of their Summary in the claims or their dependency. It shows

Fig. 1 to 15

known panels with locking elements,

Fig. 16 to 25

Views of several embodiments of panels with differently formed connecting areas and locking elements,

Fig. 26

a schematic view of a part of a panel according to the invention,

Fig. 27

a view along the section A from Fig. 26

Fig. 28

a view along the section B from Fig. 26

Fig. 29 to 31

Views of a further embodiment as shown in the FIGS. 26 to 28 .

FIGS. 32 to 34

Views of a further embodiment as shown in the FIGS. 26 to 28 .

Fig. 35 to 37

Views of a further embodiment,

Fig. 38 to 39

Views of a further embodiment,

Fig. 40

a view of a locking element,

Fig. 41

a side view of the locking element Fig. 40 .

Fig. 42

a schematic cross-sectional view of a first connecting portion of a panel,

Fig. 43

one of the Fig. 42 corresponding view with inserted locking element and

Fig. 44

a schematic perspective view of a locking element for insertion into a connecting region according to Fig. 43 ,

In the Fig. 1 to 15 various connections of panels with locking elements are shown. Although this is state of the art from the publications WO 2007/008139 A1 . DE 101 38 285 A1 . US 2007/0028547 A1 and DE 20 2006 019 869 U1 It should be noted that in particular in the FIGS. 26 to 39 illustrated embodiments and the relevant inventive concept can also be realized in the aforementioned prior art. For the rest, but on the Fig. 1 to 15 not discussed further. The relevant disclosure content is hereby expressly made the subject of the present application.

In Fig. 16 two panels 1 are shown, which are intended for use in the floor, wall or ceiling area. Each of the panels 1 has a panel element 2 as a basic body, which usually consists of a wood material. In the presentation according to Fig. 16 a first connection region 3 of the one panel 1 and a second connection region 4 of the other panel 1 are shown. Finally, in each case a first connection region 3 and a second connection region 4 are provided on a panel 1 on opposite sides or on opposite edges. The connecting regions 3, 4 are thus basically located on a panel 1 on opposite sides, in the present case on the respective short sides of the panel element 2, which is otherwise in the form of an elongate rectangle.

At the first connection region 3, a groove 5 is provided, in which a locking element 6 is located. The locking element 6 is not connected to the groove and in principle movable relative to the groove. In any case, a movement of the locking element 6 in and counterclockwise is possible. The locking element 6 has a circular outer contour which extends over more than 180 °. The inner contour of the groove 5 is also circular and the outer contour of the locking element 6 adapted at least substantially. Moreover, the locking element 6 has a locking portion 7 and an engaging portion 8. The dimensions the locking element 6 and the groove 5 are such that the locking element 6 could basically be moved in the longitudinal direction of the groove. Moreover, the first connection region 1 at its lower end still on a protruding projection 9.

The second connection region 4 is formed, on the one hand, corresponding to the first connection section 3 and, moreover, to interact with the locking element 6. In detail, the second locking portion has a projection 10 which is provided for acting on the engaging portion 8. If the two panels 1 joined together, the attachment of the projection 10 on the engaging portion 8 causes the locking member 6 rotates clockwise in the illustrated embodiment and the locking portion 7 engages behind an undercut 11 on the second connection portion 4. Moreover, the projection 10 of the second connecting portion 4 engages behind the projection 9 of the first connecting portion, so that in the assembled state, the in Fig. 17 is shown, a positive connection in the horizontal and vertical direction results.

The Fig. 18 to 25 show alternative embodiments, wherein the respective locking elements 6 each have a different shape. The same applies to the contour formation of the first and second connecting region 3, 4. Functionally, however, there are no differences from the previously described embodiment.

It should be noted that the following in the FIGS. 26 to 39 described alternatives in the embodiments of Fig. 16 to 25 may also be provided.

In Fig. 26 a first alternative of a panel 1 according to the invention is shown. From a comparison of FIGS. 27 and 28 , each having a section A or B off Fig. 26 show that the groove 5 in the area A has a larger cross section than in the area B. The locking element, not shown, is located only in the region of the groove 5 with the enlarged cross section. The area B with the reduced cross-section acts as a stop and prevents it from moving out of the locking element out of the groove 5.

In the Fig. 29 to 31 illustrated embodiment substantially corresponds to the embodiment according to the FIGS. 26 to 28 , wherein in the end region, that is in the region of the section B, in each case a closure element 12 is provided as a stop. In this embodiment, the groove 5 has the same cross-section over its entire length.

The embodiment according to the FIGS. 32 to 34 corresponds substantially to the embodiment according to the Fig. 29 to 31 , wherein also in this case the groove 5 over the entire width of the panel element 2 and over the length of the first connecting portion 3 has the same cross-section. However, it is in the area of the cuts B so that there is a respective pin 13 is provided as a locking means, which projects into the groove 5, not shown, that on the locking element 6 a transversely to the longitudinal direction of the locking element 6 and thus also transversely to the longitudinal direction Groove 5 extending slot is provided, through which the pin 13 protrudes. The slot allows movement of the locking element 6 in the locking and unlocking in and counterclockwise

In Fig. 35 is a representation accordingly Fig. 32 shown, The FIGS. 36 and 37 show two sections with possible alternative embodiments in which the locking element 6 is held in its frictional locking in the groove 5 to its locking in the longitudinal direction of the groove 5. This is in the in Fig. 36 shown embodiment in the groove 5 regions - in relation to the circumference or the cross section of the groove 5 - a covering 14 provided with a relative to the surface of the groove 5 increased coefficient of friction. In the embodiment according to Fig. 37 a corresponding pad 14 is also provided, but this is located at approximately opposite locations within the groove. It is understood that it is also possible in principle to provide corresponding coverings at locations other than those shown.

In the FIGS. 38 and 39 an alternative embodiment of the frictional locking is shown in which the locking element 6 is provided on a part of the surface of the groove 5 acting spring leg 15 so that upon movement of the locking element 6 in the longitudinal direction of the groove 5 results in an increased frictional force. In the case shown, the spring force of the spring leg 15 is generated or increased by a projection 16 which pushes the spring leg 15 further away from the surface of the groove 5. For the sake of clarity, it should be noted that in the rebound state, the locking element 6 has a larger cross-section than the groove 5, so it can only be absorbed by the latter when the locking element 6 is compressed accordingly.

In an alternative embodiment, not shown, the locking element 6 on its groove 5 facing the outside at least one projection on which may correspond in cross-sectional view of the projection 16, which, however, has hardly any longitudinal extension. This projection is provided for engagement in a corresponding slot in the groove 5, wherein the slot is aligned at least substantially transversely to the longitudinal direction of the groove 5. In the inserted state of the locking element 6, the projection engaging in the slot prevents movement of the locking element 6 in the longitudinal direction, but allows movement in and counterclockwise for locking the locking element 6.

In the FIGS. 40 to 44 Parts of another alternative embodiment are shown. In this embodiment, it is such that the locking element 6, the example in Fig. 44 is shown, with a provided on the first connection portion 3 locking means 17 is detachably connectable. The locking element 6 may have a relatively simple circular cross-sectional shape. It is understood, however, that deviating cross-sectional shapes are also possible. The locking means 17 is a component that extends over at least a portion of the length of the groove 5. Preferably, the locking means extends at least substantially over the entire length of the groove. 5

The locking means 17 is in detail in the FIGS. 40 and 41 shown. In the present case, it has an insertion region 18 for insertion into a slot 19 in the groove 5 and, moreover, a coupling region 20 for detachable connection to the locking element 6. The slot 19 is a longitudinal slot whose length may correspond to the length of the groove 5. In the present case, the insertion region 18 has an insertable limb 21 on which a plurality of lamellae 22 are provided on the outside. Instead of the slats and projections can be provided. As it turned out Fig. 43 results, the insertion portion 18 is inserted into the slot 19. He can also be glued in it.

For the rest, the Fig. 40 in that the coupling region 20 has a plurality of coupling projections 23 which are provided on the locking element 6 for engagement in corresponding slots 24 extending transversely to the longitudinal direction of the locking element 6. Each of the coupling projections 23 has a head 25 whose width is greater than the width of the slot 24, so that the head 25 engages over the slot 24 in the coupled state. So that the individual heads 25 can be inserted into the slots 24 at all, each of the slots 24 has a widened head opening 26 at the end. The head opening 26 corresponds to the dimensions of the head 25. In the illustrated embodiment, the individual heads of the coupling projections 23 are formed T-shaped, while the head openings 26 are formed as to the slots 24 transverse insertion slots.

Furthermore clarifies the Fig. 41 in that the locking means 17 is a strip-shaped component which is made of a flat plastic material such as the locking element 6 as well.

The manufacture of the panel 1 according to the embodiment according to the FIGS. 40 to 44 takes place such that after appropriate profiling of the first and second connecting portion 3, 4 with creation of the groove 5 and the slot 19, the locking means 17 is inserted into the slot 19. Subsequently, the locking element 6 is connected to the locking means 17, wherein the heads 25 are inserted through the head openings 26. Subsequently, the locking element 6 can be pivoted accordingly.

A significant advantage, which results in the last-mentioned embodiment is not dargstellt drawing. Due to the connection of the locking element 6 with the locking means 17, it is possible that the groove. 5 Although in principle has a circular cross-section, the arc angle, however, may be less than 180 °, so that it is possible in principle, the locking element, if it is not connected to the locking means 17, transverse to the longitudinal direction of the groove of the groove 5 without that it requires a deformation of the locking element 6.

LIST OF REFERENCE NUMBERS

1

panels

2

panel member

3

first connection area

4

second connection area

5

groove

6

locking element

7

locking portion

8th

engaging portion

9

head Start

10

head Start

11

undercut

12

closure element

13

pen

14

covering

15

spring leg

16

head Start

17

locking

18

insertion

19

slot

20

coupling region

21

leg

22

lamella

23

coupling projection

24

slot

25

head

26

head opening

Claims (15)

Panel (1) for use in floor, wall and ceiling areas, with complementary first and second connecting areas (3, 4) for connection to adjacent panels (1) provided at opposite edges, wherein at the first connecting area (3) a groove (5 ) and at least one in the groove (5) located, with the groove (5) unconnected, with respect to the groove (5) movable and elongated locking element (6) is provided, wherein at the second connection region (4) has a projection (10) for cooperation with the locking element (6) is provided such that during assembly of the projection (10) against or on the locking element (6) acts and the locking element (6) engages behind an undercut (11) of the second locking portion (4), so that a Locking in the horizontal and / or vertical direction results, characterized in that in the region of the groove (5) at least one stop for locking the locking element (6) in Längsr direction of the groove (5) is provided. Panel according to Claim 1, characterized in that the locking element (6) extends over only a partial region of the length of the groove (5) and in that the groove (5) has a cross section complementary to the cross section of the locking element (6) in the partial region. Panel according to claim 1 or 2, characterized in that the groove (5) has at its two ends a reduced cross section for forming a stop in the longitudinal direction of the groove (5) and / or that the groove (5) at least one end of a closure element (12) for forming a stop in the longitudinal direction of the groove (5). Panel according to one of the preceding claims, characterized in that at least one transverse to the longitudinal direction of the locking element (6) extending slot is provided on the locking element (6) and that in the first connection region (3) held, projecting through the slot, in particular as a nail, Pin (13), screw or bolt trained locking. Panel (1) for use in floor, wall and ceiling areas, with complementary first and second connecting areas (3, 4) for connection to adjacent panels (1) provided at opposite edges, wherein at the first connecting area (3) a groove (5 ) and at least one in the groove (5) located, with the groove (5) unconnected, with respect to the groove (5) movable and elongated locking element (6) is provided, wherein at the second connection region (4) has a projection (10) for cooperation with the locking element (6) is provided such that during assembly of the projection (10) against or on the locking element (6) acts and the locking element (6) engages behind an undercut (11) of the second locking portion (4), so that a Locking in the horizontal and / or vertical direction results, in particular according to one of the preceding claims, characterized in that the locking element (6) to its Arretierun g in the longitudinal direction of the groove (5) is frictionally held in the groove (5). Panel according to one of the preceding claims, characterized in that in the groove (5) at least partially a covering (14) with a respect to the surface of the groove (5) increased friction coefficient is provided and / or that the covering (14) via the complementary Cross section of the groove (5) protrudes. Panel according to one of the preceding claims, characterized in that a spring leg (15) acting on a part of the surface of the groove (5) is provided on the locking element (6) so that, when the locking element (6) is moved in the longitudinal direction of the groove ( 5) gives an increased frictional force. Panel (1) for use in floor, wall and ceiling areas, with complementary first and second connecting areas (3, 4) for connection to adjacent panels (1) provided at opposite edges, wherein at the first connecting area (3) a groove (5 ) and at least one in the groove (5) located, with the groove (5) unconnected, relative to the groove (5) movable and elongated locking element (6) is provided, wherein at the second connection region (4) has a projection (10) for cooperation with the locking element (6) is provided such that when joining the projection (10) against or on the locking element (6) acts and the locking element (6) engages behind an undercut (11) of the second locking portion (4), so that A locking in the horizontal and / or vertical direction results, in particular according to one of the preceding claims, characterized in that the locking element (6) on its groove (5) facing the outside at least one projection for engaging in a corresponding slot in the groove ( 5), wherein the slot is aligned at least substantially transversely to the longitudinal direction of the groove (5). Panel (1) for use in the floor, wall or ceiling area, with complementary first and second connecting areas (3, 4) for connection to adjacent panels (1) provided at opposite edges, wherein at the first connecting area (3) a groove (5 ) and at least one in the groove (5) befindliches, with respect to the groove (5) movable and elongated locking element (6) is provided, wherein the second connection region (4) has a projection (10) for cooperation with the locking element (6) provided in that, during assembly, the projection (10) acts against or on the locking element (6) and the locking element engages behind an undercut (II) of the second locking area (4) so that a locking occurs in the horizontal and / or vertical direction, in particular according to one of the preceding claims, characterized in that the locking element (6) with at least one at the first connection region ( 3) provided locking means (17) is detachably connectable. Panel according to claim 9, characterized in that extending in particular strip-shaped and preferably made of flat material locking means (17) extends over at least a portion of the length of the groove (5). Panel according to claim 9 or 10, characterized in that the locking means (17) has an insertion region (18) for insertion into a slot (19) in the groove (5) and a coupling region (20) for detachable connection to the locking element (6). and / or the insertion region (18) a plug-in leg (21) having at least one outer side projection, in particular in the form of a lamella (22) and / or the insertion region (18) is glued into the slot (19). Panel according to one of claims 9 to 11, characterized in that the coupling region (20) has at least one coupling projection (23) for engagement in a corresponding, transversely to the longitudinal direction of the locking element (6) extending slot (24) on the locking element (6). Panel according to one of claims 9 to 12, characterized in that the coupling projection (23) has a slot (24) cross-head (25) and in that the slot (24) in particular end a widened head opening (26) for inserting the head (26). 25). Panel according to one of claims 9 to 13, characterized in that the coupling projection (23) is T-shaped and the slot (24) has a transverse insertion slot as a head opening (26). Panel according to one of claims 9 to 14, characterized in that the groove (5) has such a stop-free cross-sectional shape for the locking element (6), that the locking element (6) without connection to the locking means (17) transversely to the longitudinal direction of the groove ( 5) is removable from the groove (5) and / or that the groove (5) has a circular cross section and extends over an arc angle of less than 80 °.

Images