GB1571958A

GB1571958A - Panels connected by fasteners

Info

Publication number: GB1571958A
Application number: GB2441877A
Authority: GB
Original assignee: ITW Ateco GmbH
Current assignee: ITW Ateco GmbH
Priority date: 1976-06-11
Filing date: 1977-06-10
Publication date: 1980-07-23
Also published as: DE2626220C2; IT1074899B; FR2354474A1; ES459641A1; DE2626220A1

Description

(54) PANELS CONNECTED BY FASTENERS (71) We, ITW-ATECO G.m.b.H., a corporation organized under the laws of the Federal Republic of Germany, of Stormarnstrasse 43-49, 2 Norderstedt 1, West Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a fastening element for decorative covers, especially front panels of loudspeaker cabinets.

In the case of such decorative covers, it is generally a question of light panels of pressed wood or chipboard covered with fabric or film, which are fastened by an invisible connection to the supporting components, housings, etc. These connections must always be releasable again, to permit a removal of the decorative covers and their replacement.

For satisfying these requirements, it is known to provide double-sided selfadhesive strips or strips with small hooks, mounted by adhesive. These connecting means however have a series of disadvantages set out below. The covers or front panels fastened with self-adhesive strips cannot be used again after any necessary demounting, because the adhesive effect is not fully active any more after release.

Therefore for remounting new adhesive strips must be applied, which is inconvenient and expensive. Moreover, with such a connection the accurate mounting of the cover on the component supporting it is necessary, because a subsequent shifting is no longer possible with an adhesive connection. With the employment of the hooked strips mentioned, it is necessary to apply the strip on both parts.

Just as with the self-adhesive strips, here also the possibility of lateral shifting is very limited, because the individual hooks only shift slightly and spring back. Further disadvantages lie in the fact that the hooked strip wears out very rapidly and is relatively expensive.

Especially with loudspeaker cabinets, it is required to fasten the front pane covering the housing in a floating manner on the housing of the cabinet, so that by means of an aligning operation parallelism between the edges of the front panel and of the cabinet can be produced. To fulfil this requirement, the corresponding fastening means must however permit a relatively great possibility of lateral shifting. The known fastening means do not satisfy these requirements.

The object underlying the invention is to provide a fastening element for decorative covers, especially front panels of loudspeaker cabinets, which is re-usable, makes possible an easy mounting and demounting of the panel, and ensures a relatively great possibility of lateral shifting of the latter with simultaneous secure grip.

This object is solved according to the invention by two panels connected by a fastener, the fastener comprising two bushes and a connecting element; each bush comprising a hollow cylinder which is firmly fitted in a bore in a respective one of the panels, and a cone-shaped elastic gripping means extending into the bush from an end of the bush adjacent to a surface of the panel and converging into the bush to a central hole; and the connecting element being in the form of a central shank and enlarged end portions, with a central flange around the middle of the shank, the maximum cross section of each portion of the connecting element being larger than the unstressed size of the hole in the respective gripping means.

In the mounting of the fastener, the bushes formed of hollow cylinder shape are inserted in matching receiving bores of the parts to be connected, for example of the housing and of the front panel of a loudspeaker cabinet, while sufficient arrangements are found to ensure a firm seating of the latter in the receiving bores. At the same time the end of the bush provided with the elastic gripping means is at the entry end of the receiving bore. Now the connecting element for the bushes is pushed into the gripping means of one of the mounted bushes, while the respective end portion of the connecting element displaces the gripping means so far that it can pass through the central hole. By reason of the contracting cross section of the element in the direction towards the central flange, the cross section of the gripping means can then again contract. The gripping means however remains thereafter under prestress, so that a firm grasp of the connecting element in the bush is ensured. Although consequently the gripping means opposes a sufficiently high resistance with respect to tensile loadings in a direction parallel to the longitudinal axis of the connecting element, it makes possible for the connecting element the performance of limited movements in any desired direction perpendicular to its longitudinal axis. This possibility of movement is brought about by the contact between the edge of the hole in the gripping means and the shank of the connecting element, which contact is substantially only annular. Consequently the connecting element can on the one hand perform tilting movements in desired directions, but however on the other hand it is secured to a sufficient extent against pulling out.

After the connecting element has been inserted at one end either into the bush mounted on the housing or on the front panel, for assembly of the front panel its bush is pressed towards the corresponding housing bush, so that the connecting element secured at one end is introduced with its free end portion into the gripping means of the other bush, and is retained in its central hole. The front panel then lies firmly against the housing, and can according to the magnitude of the angle of inclination of a step on the connecting element and the elasticity of the gripping means - only be pulled apart from the housing upon application of a predetermined force. On the other hand the kind of connection proposed according to the invention permits tilting movements of the connecting element in a certain range, so that housing and front panel can perform movements relatively to one another, parallel to the plane of the front panel, within a predetermined order of magnitude. Thus even after the formation of the connection a certain lateral shifting ability of the front panel, and hence a floating mounting of the latter on the housing, is ensured. This has as consequence that, in contrast to self-adhesive strips, even after the production of the connection, parallelism between the edges of the cover and those of the housing can be produced by an adjusting operation. In addition there is the fact that, with the solution proposed according to the invention, tolerances between the corresponding receiving bores of the panels can be taken up in an exceptional manner. Finally, the mounting of the cover or front panel is substantially facilitated.

The fastener element proposed according to the invention is easy to manufacture, especially because it has two identically shaped bushes. The connection achieved by means of the fastener can -- according to the formation of the gripping means of the bush and of the connecting element - be released at any time with greater or less exertion of force, and used again in desired manner.

According to a particularly preferred embodiment, the gripping means is constituted by several spring elements separated by slots. With this form of construction, which is relatively easy to manufacture, on the one hand full justice is done to the requirements imposed on the elastic properties of the gripping means, and on the other hand the contact surface between gripping means and connecting element is kept so low, that the connecting element can perform rocking movements unhindered. The dimensioning of the individual spring elements should then be carried out in correspondence with the chosen shape of the connecting element, as well as the desired easy or difficult possibility of demounting of the connection.

In order to ensure an exact seating of the bushes, in the respective receiving bores, preferably that bush end, from which the gripping means extends, is enlarged like a flange. The rim formed in this manner, upon insertion of the bush into the receiving bore, lies against a surrounding abutment surface, so that in this way the bush is not driven too far into the bore. To simplify further the mounting of the bush into wood, the end opposite the end of the bush provided with the grip is bevelled at its external edge.

In order to anchor the bush in sufficient manner to the walls of the bore, various constructional possibilities of the bush outer surface are conceivable. In a preferred embodiment, the outer surface of the bush has ratchet teeth which, upon driving of the bush into the bore, dig into the wood. Naturally the bush can also be inserted with a glued or screwed connection into the two components to be connected, while possibly the teeth on the surface of the bush can be omitted.

The embodiments mentioned above with regard to the anchoring of the bush in the receiving bore are preferably suited for larger thicknesses of panel, which exceed the length of the bush. In an embodiment particularly suited for thin panels, the outer surface of the bush is slotted in such a manner that the surface zones disposed between the slots are effective as spring legs. These spring legs are urged inwards for introduction of the bush into a suitable receiving bore, and, when the final position of the bush is reached, they snap outwards, so that the bush is secured in the bore.

With this embodiment, the outer surface of the bush is advantageously formed slightly conical.

In order to assist the possibility of introduction of the connecting element through the central holes of the gripping means, in a preferred embodiment of the invention the connecting element has dome-shaped end zones. Upon pushing of these zones into the gripping means, the ends of the spring elements are pressed outwards and slide along over the surface of the dome, until the widest part of the connecting element end portion is reached. The zone which then follows contracts in the direction towards the central flange, so that the spring elements can snap back, and in this position, in which they remain still under stress, captivate the connecting element.

In order to increase the snapping action upon introduction of the connecting element into the gripping means, according to a special embodiment of the invention, the dome-shaped end zones, via a reentrant circumferentially extending step, connect with shank zones which expand in a direction towards the free ends. According to the magnitude of the angle of inclination of this step, the connecting element can be pulled out of the corresponding bush with more ease or more difficulty, that is to say with an angle of inclination of approximately 900 to the longitudinal axis of the connecting element the connection is scarcely able to be demounted again. The choice of a suitable angle of inclination is controlled according to the requirements imposed on the fastening element.

Advantageously the zones expanding in the direction towards the free end are formed conically or trumpet shaped. The conically expanding zones find employment especially together with the circumferential projecting step. According to a further embodiment of the invention, the expanding zones are connected to the central flange via a zone extending in the form of a trumpet towards the centre of the element. By means of such an intermediate zone the connecting element becomes sufficiently long to permit the presence of covering material applied to the panels.

The covering can at this point also easily form folds or be of double thickness.

The following explanation of preferred embodiments in conjunction with the accompanying drawing serves for better understanding of the invention; in this drawing Figure 1 shows the body of a loudspeaker cabinet with demounted front panel, in perspective view; Figure 2 shows a section through a connection according to the invention; Figure 3 shows a preferred embodiment of the bush in half section; Figure 4 is an elevation of the bush shown in Figure 3; Figure 5 is the side view of a first embodiment of the connecting element; Figure 6 shows a second embodiment of the connecting element in side view; Figure 7 shows a third embodiment of the connecting element in side view; and Figure 8 shows a second embodiment of the bush in half section.

If one refers first to Figure 1, then one recognises the body 11 of a loudspeaker cabinet and the associated demounted front panel 12. On the housing the four places are indicated at which the fastening element 1 formed according to the invention is arranged. With reference to the fastening of the front panel 12 to the housing of the loudspeaker cabinet, it is required that this receives a firm retention on the housing of the cabinet, but at the same time shall be able to shift laterally to a certain extent, in order to make possible a subsequent adjustment of the front panel relatively to the edges of the housing. In addition, with the chosen fastening means it should be possible to take up certain tolerances in the receiving bores of the housing and of the front panel.

Figure 2 shows in section a connection produced between housing and front panel with the fastening element formed according to the invention. The fastening element 1 consists of two identical bushes 2, formed generally in hollow cylindrical shape, which are inserted in corresponding receiving bores 3 of the housing and of the front panel. Fuller details with reference to the insertion of the bushes are described with reference to Figures 3, 4 and 8 explained below. From one end of the bush there extends into the interior of the bush an elastic grip with internal bore, which serves, in conjunction with the elastic grip of the corresponding adjacent bush, for reception of a connecting element 4. Fuller details with reference to the formation of the connecting element are explained in conjunction with Figures 5 to 7.

The function of the fastening element can best be explained with reference to Figure 2. As one can see from the Figure, the connecting element 4 can perform tilting movements within a certain range in all possible directions, so that thereby movements between the front panel 12 and the housing 11 parallel to the plane of the front panel 12 are possible to a predetermined extent. The fastening element thus permits a certain lateral shifting possibility of the cover or front panel and housing relatively to one another, the magnitude of which is indicated as X in Figure 2.

Although this possibility of floating movement exists, the connecting element on the other hand provides a thorough insurance against tension, because on pulling the front panel the cone portions of the element are pulled back into the centre holes of the grips of the bushes, and thus a sufficiently high resistance against tension is given. With a correspondingly high expenditure of force, the connecting element can however be pulled out of the grip, in order to permit the demounting of the front panel.

Furthermore, in Figure 2 is given at Y the thickness measurement of the covering 13, which is bridged by the fastening element. The covering 13 can then easily form folds or be of double thickness, because the zones of the connecting element expanding towards the free ends, as well as their extensions towards the central flange, are formed sufficiently long, and thus certain variations of thickness can also be taken up in the direction of the longitudinal axis of the connecting element.

In Figure 3 is shown in partial section the bush 2 which is only shown schematically in Figure 2. The bush has a generally hollow cylindrical shape, which is enlarged like a flange 21 at the end which is at the rear when driving in. At the end which is forward when driving in, the external edge of the bush is bevelled at 23.

The flange-like enlargement 21 rests against an abutment provided in the receiving bore, and thus ensures the correct seating of the bush as regards depth. The bevelled external edge 23 permits an easy mounting of the bush into wood.

On the exterior, the outside surface 20 of the bush is provided with a plurality of ratchet teeth 24, which, upon driving of the bush into the receiving bore 3, dig into the wood. In Figure 8 is shown another possibility of fastening the bush 2 to the housing or the cover. This kind of fastening is employed especially with thin-walled panels. Then the teeth 24 on the exterior of the surrounding wall of the bush are omitted. The outer surface is provided with slots 29, so that the zones 14 lying between the slots act as spring legs 28 and retain the bush against the panel. The exterior of the surrounding surface of the bush is then cylindrical, while the spring legs 28 extend radially outwards from the surrounding surface.

If one now refers again to Figures 3 and 4, one will see that an elastic grip 22 with a central hole 25 extends from one end of the bush into the interior of the bush; in the embodiment shown in Figures 3 and 4 this grip is provided by three spring segments 27 separated by slots 26 and formed like a cone. Upon introduction of the connecting element into the grip, these spring elements 27 are urged outwards, and by reason of their elasticity they engage closely against the cone-like zone of the connecting element.

In Figures 5 to 7 three preferred embodiments of the connecting element 4 are shown in side view. Common to all embodiments is the central flange 30, from which similar zones extend in both directions, which are formed differently according to the embodiment. In the embodiment shown in Figure 5, the shank zones expanding towards the free ends have a conical shape 31 and merge into end zones 32 formed like a dome, which serve to ease the introduction of the connecting element into the grips. The conically expanding zones 31 are each connected to the central flange 30 via zone 35 of trumpet shape expanding towards the centre of the element.

In the embodiment shown in Figure 6, in place of the conically formed zones 31 of Figure 5, trumpet-shaped expanding zones 33 are present, which likewise merge into rounded end zones 32. In the remaining features, the embodiment of Figure 6 corresponds entirely with that of Figure 5.

With the embodiment of the connecting element 4 shown in Figure 7, particularly favourable results can be obtained. Here the end zones 32 which are formed like a dome are connected to the shank zones expanding in the direction towards the free ends, which in this embodiment are formed conical at 31 via a reentrant circumferentially extending step 34. The step 34 has the advantage that, in consequence of the abrupt change of cross section, a certain snap action is achieved by means of the spring segments 27. In addition the withdrawal of the connecting element out of the grip of the bush is further impeded. By modification of the angles a and p both shown in Figure 7, in which a is the angle of inclination of the zone 31 expanding towards free end, and the angle of inclination of the step 34, the possibility of demounting of the connection can be regulated within a certain range. The greater the angle tends towards zero, the more difficult becomes the demounting of the connecting element, which, depending also on the properties of the spring segments 27, may lead to no possibility of demounting of the connection. The more acute the angle a is shown, the more easily the element can be pulled out of the grip.

The embodiments shown in Figures 5, 6 and 7 can be combined among themselves, so that different demounting forces can be achieved from one side to the other side.

In the mounting of the front panel onto the loudspeaker cabinet, with employment of the fastening element formed according to the invention, one proceeds as follows: The bushes are inserted into the suitably arranged receiving bores in the housing and in the cover, whereupon the corresponding connecting elements are introduced either into the bushes on the housing or the bushes on the front panel. Thereafter, the front panel is pressed towards the housing wall, while the free ends of the connecting elements lock into the grips of the corresponding bushes. The front panel can then be adjusted relatively to the housing edges by reason of the floating support produced.

For production of the fastening element according to the invention, use is preferably made of plastics known in this field of use.

WHAT WE CLAIM IS: 1. Two panels connected by a fastener, the fastener comprising two bushes and a connecting element; each bush comprising a hollow cylinder which is firmly fitted in a bore in a respective one of the panels, and a cone-shaped elastic gripping means extending into the bush from an end of the bush adjacent to a surface of the panel and converging into the bush to a central hole; and the connecting element being in the form of a central shank and enlarged end portions, with a central flange around the middle of the shank, the maximum cross section of each end portion of the connecting element being larger than the unstressed size of the hole in the respective gripping means.

2. A combination in accordance with claim 1, in which each gripping means comprises several spring elements separated by slots.

3. A combination in accordance with claim 1 or claim 2, in which that bush end from which the gripping means extends is enlarged in the form of a flange.

4. A combination in accordance with any one of the preceding claims, in which the end opposite the bush end provided with the grip is bevelled at the outer edge.

5. A combination in accordance with any one of the preceding claims, in which the outer surface of the bush has ratchet teeth.

6. A combination in accordance with any one of the preceding claims, in which the bush surface is slotted in such a manner that the surface zones disposed between the slots are effective as spring legs.

7. A combination in accordance with any one of the preceding claims, in which the connecting element has dome-shaped end zones.

8. A combination in accordance with claim 7, in which the dome-shaped end zones, via a reentrant circumferentially extending step, connect with shank zones which expand in a direction towards the free ends.

9. A combination in accordance with claim 8, in which the zones which expand in a direction towards the free ends are conically shaped.

10. A combination in accordance with claim 8, in which the expanding zones are trumpet-shaped.

11. A combination in accordance with any of claims 8 to 10, in which the expand ing zones are connected to the central flange via a zone extending in the form of a trumpet towards the centre of the element.

12. A combination in accordance with claim 1, substantially as described with reference to Figures 2 to 5 of the accompanying drawings, or modified as in Figure 6, Figure 7, or Figure 8.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. shown in Figure 7, in which a is the angle of inclination of the zone 31 expanding towards free end, and ss the angle of inclination of the step 34, the possibility of demounting of the connection can be regulated within a certain range. The greater the angle ss tends towards zero, the more difficult becomes the demounting of the connecting element, which, depending also on the properties of the spring segments 27, may lead to no possibility of demounting of the connection. The more acute the angle a is shown, the more easily the element can be pulled out of the grip. The embodiments shown in Figures 5, 6 and 7 can be combined among themselves, so that different demounting forces can be achieved from one side to the other side. In the mounting of the front panel onto the loudspeaker cabinet, with employment of the fastening element formed according to the invention, one proceeds as follows: The bushes are inserted into the suitably arranged receiving bores in the housing and in the cover, whereupon the corresponding connecting elements are introduced either into the bushes on the housing or the bushes on the front panel. Thereafter, the front panel is pressed towards the housing wall, while the free ends of the connecting elements lock into the grips of the corresponding bushes. The front panel can then be adjusted relatively to the housing edges by reason of the floating support produced. For production of the fastening element according to the invention, use is preferably made of plastics known in this field of use. WHAT WE CLAIM IS:

1. Two panels connected by a fastener, the fastener comprising two bushes and a connecting element; each bush comprising a hollow cylinder which is firmly fitted in a bore in a respective one of the panels, and a cone-shaped elastic gripping means extending into the bush from an end of the bush adjacent to a surface of the panel and converging into the bush to a central hole; and the connecting element being in the form of a central shank and enlarged end portions, with a central flange around the middle of the shank, the maximum cross section of each end portion of the connecting element being larger than the unstressed size of the hole in the respective gripping means.