WO2008125576A2

WO2008125576A2 - Plug for fastening a dashboard

Info

Publication number: WO2008125576A2
Application number: PCT/EP2008/054313
Authority: WO
Inventors: Martin Völker
Original assignee: Basf Se
Priority date: 2007-04-11
Filing date: 2008-04-10
Publication date: 2008-10-23
Also published as: WO2008125576A3

Abstract

The invention relates to a plug (116) which can be inserted in a flat element (110, 112), especially in a dashboard (110) of a motor vehicle. The plug comprises a plug dome (118) for insertion in a bore (114) having a non-circular cross-section, said plug dome (118) having a substantially circular cross-section. The plug also comprises a plug top (120) which radially projects from the plug dome (118) in at least some sections. A radial clamping zone (124) is arranged between the plug dome (118) and the plug top (120) and has at least one radially flared portion (126). The plug (116) is clamped with a radial clamping force by rotating the plug in the bore (114).

Description

Dowel for instrument panel attachment

description

The invention relates to a dowel according to the preamble of claim 1 and a method for fixing a dowel according to claim 13. Such dowels and fixing methods are used in particular in the automotive industry.

Numerous different types of dowels are known in the prior art, which have been designed for a wide variety of applications. Such dowels usually have a Dübeldom for introduction into a bore, wherein the dowel dome usually has a circular cross-section. Furthermore, the dowels on a dowel head, which usually remains outside the bore.

In the body of the dowel is usually introduced along the dowel axis a threaded bore, which tapers to the dowel tip (i.e., towards the dowel head end facing away), which may also be cylindrical. When screwing a screw into this threaded hole, the dowel spreads in the radial direction and causes in this way a radial clamping in the bore.

In the field of automotive engineering, for example, dowels are used to fix dashboards. An example of such a fixation by a dowel is shown schematically in Figure 1.

In this known fixation, a dashboard 110 is arranged overlapping a sheet 1 12, wherein the dashboard 1 10 and the plate 112 have congruent holes 1 14. The bore 114 are configured square in these exemplary embodiments and can be produced, for example, by drilling, milling, punching or by suitable plastics engineering methods, for example corresponding cores in an injection molding tool, or by combinations of the methods mentioned or by other methods.

To fix the dashboard 1 10 and the plate 1 12 against each other, a dowel 1 16 is introduced into the holes 1 14. Corresponding to the bore cross-section, the dowel has a dowel dome 1 18 with a square cross-section and a dowel head 120 dish-shaped in this embodiment. The dowel dome 1 18 tapers towards its tip slightly, whereas the dowel head 120 facing the end of the dowel dome 118 substantially corresponds to the dimensions of the holes 1 14. Alternatively to the tapered version of the dowel doms 1 18 but also dowels 116 are known with non-tapered Dübeldom 1 18.

After the dowel 1 18 is inserted into the holes 1 14, this is there prevented by the square shape, which is the holes 1 14, from twisting. A screw (not shown in Figure 1) is in a threaded hole

122, which extends axially in the dowel 116, screwed. This spreads due to its deformable properties of the dowel dome 1 18, which is a clamping of the

Sheet metal 112 and the instrument panel 110 and thus causes a fixation of these elements against each other.

The application shown in Figure 1 makes very critical and partially conflicting requirements for the selection of the material of the anchor 1 16. On the one hand, the material should be deformable and tough to ensure an elongation of the dowel dome 118 and thus the above-described clamping. On the other hand, the material of the anchor 116 should, however, be hard and brittle in order to avoid destruction of the anchor 116 in the region of the threaded bore 122 even at high insertion torque of the screw into the threaded bore 122 or deformation of the anchor 16 in the region of the bores 14 in which, for example, the dowel 1 16 would rotate within the holes 1 14.

Such conflicting requirements for the material of the anchor represent a constructive and material technology is a high challenge.

The object of the invention is therefore to provide a dowel, which is particularly suitable for automotive applications such as the applications described above and which ensures both a high spread and thus a high clamping, which, however, can be loaded simultaneously with a high insertion torque of a screw.

A basic idea of the present invention is to bring about a design separation of functional separation of clamping and high insertion torque. For this purpose, in particular on the basis of the application described above for instrument panels, a dowel is proposed, which is in principle suitable for use in a plate-shaped element.

Like the known dowels, the proposed dowel also includes a dowel dome for insertion into a bore (reference being made to the above description for the bore), the dowel dome having a substantially circular cross-section. Under "essentially" can also be a slight deviation from the circular shape, preferably a deviation in the diameter of not more than 5%. For example, the cross section may thus be slightly elliptical.

Furthermore, the plug has a relative to the dowel dome at least partially radially projecting dowel head. For example, this dowel head turn, as described above, dish-shaped, but may also have other shapes, such as a square or rectangular shape. This dowel head essentially serves to prevent too deep penetration of the dowel into the bore.

In that regard, the proposed dowel essentially corresponds to known dowel shapes, such as, for example, known wall dowels. In contrast to the anchor described above with square cross-section, however, the anchor with the previous features no rotation for fixation in a dashboard.

It is therefore proposed to provide a radial clamping region between the dowel dome and the dowel head, which has at least one radial widening. This radial widening should be designed such that by rotation of the dowel in the bore, a clamping with radial clamping force is effected. For example, the radial clamping region may have a substantially circular cross-section, wherein the at least one radial expansion is formed as protruding from the circumference of the circular cross-section projection. In particular, this projection can be one or more projections with a rounded shape, for example a shape which follows at least in sections substantially in the form of a circular arc.

It is preferred if this at least one projection has a thickness of not more than 40% of the diameter of the circular cross section of the radial clamping area, preferably a thickness between 5 and 20% of the diameter.

By providing the radial clamping region between the actual dowel dome and the dowel head, in the region in which later the plate-shaped element is penetrated (the thickness of this radial clamping region can accordingly be matched to the thickness of the plate-shaped element) achieves the functional separation of clamping and high torque described above. The material selection can be achieved solely due to the required torque. In contrast to the dowels with square cross-section described above, the dowel dome can be configured circular, so in total have a substantially cylindrical shape. As a result, an optimal material utilization is achieved, and it is ensured a uniform expansion of the dowel dome or the entire anchor when screwing the screw.

For fixing, the dowel with the dowel dome and the clamping area is inserted into the bore until the clamping area is arranged within the bore. Then, by screwing in a screw, the dowel is slightly rotated within the bore. As a result, the radial widening of the radial clamping area in the bore clamps firmly, so that a clamping is effected. In this case, the radial expansion can also deform, so that in addition to a radial adhesion and a positive connection can occur. Further rotation of the dowel within the bore is prevented by the radial clamping.

This separation of functions considerably increases the freedom in material selection. As a result, in particular less expensive materials can be selected and / or plastics which are adapted to other material requirements. For example, these material requirements may be in the field of environmental compatibility, color, fire resistance or similar requirements. Typical plastics which can be used for the anchor according to the invention are polyamide (with or without fillers, such as glass fiber fillings), PBT, POM, PSU, PES, PP, PE, ABS, ASA or other plastics or mixtures of said and / or other plastics.

The substantially cylindrical configuration of the dowel dome leads, as described above, to an optimal material utilization. Moreover, as a result of this configuration, which is now possible due to the functional separation of the clamping and the guarantee of high torque, fractures due to stress concentrations in the plug are also avoided. This reduces the scrap rate in the production of the dowels, and costly reworking can be largely avoided.

The radial clamping region can be adapted to the shape of the bore in terms of the number and configuration of the widenings, in particular of the projections. It is preferred if a hole in the form of a polygon is used, in particular a hole in the form of a (preferably equilateral) triangle or a square. This hole or the dowel should be designed such that the dowel with the radial clamping area in this hole can be inserted, oh- ne that larger game occurs, so with a precision fit, which still allows a comfortable insertion.

In this case, if, for example, the radial clamping area has a substantially circular cross section (apart from the widenings), the circle of the radial clamping area is inscribed in the polygon of the bore. Accordingly, the number of expansions of the number of corners of the polygon is preferably adjusted. When inserting these projections then point in the direction of the corners, which can always be ensured during insertion by slight rotation of the anchor, so that insertion is always possible. If then, as described above, the dowel slightly rotated (for example, when screwing the screw into the threaded bore) within the bore, the widening wander into the region of the sides or edges of the polygon and clamp there.

Accordingly, the dowel, for example, have three radial widenings, for example in the form of circular widenings, ie widening with increased diameter, for use preferably in a triangular bore. Alternatively, four expansions may be provided, preferably for use in a square bore. Other configurations of the widenings are also conceivable.

The previous design allows a radial clamping of the anchor within the bore and prevents in this way a rotation of the anchor. In many cases, however, it is additionally necessary to ensure axial clamping. For example, this axial clamping may be required in the example described above to press the sheet and the dashboard against each other.

For this purpose, in a preferred development of the invention, it is proposed to additionally provide an axial clamping element between the radial clamping region and the dowel dome. This axial clamping element should be used in such a way that it can be pushed completely through the bore, in order then to be arranged on the dowel head on the side of the plate-shaped element facing away therefrom. Subsequently, by a slight rotation of the dowel, by which the above-described radial clamping is effected, a clamping force in the axial direction on the plate-shaped element between dowel head and axial clamping element are exerted by this axial clamping element.

For this purpose, the axial clamping element can have an axial clamping projection, which protrudes beyond the radial clamping area. Thus, the dowel in the Area of the axial clamping projection on the whole a non-circular cross-section, such that can be pushed over the plate-shaped element by the above-described slight rotation of the clamping projection. In this respect, the effect of the axial clamping projection can be compared with a bayonet closure.

The axial clamping projection can in particular be designed in such a way that it has a clamping surface facing the dowel head. The clamping surface should have a smaller distance to the plug head in at least one area than in another area. As a result, the above-described clamping force between the dowel head and the axial clamping element can increase with increasing rotation of the dowel by rotation of the dowel. The clamping surface may in particular have a flat surface which is inclined to a plane perpendicular to the dowel axis.

The dowel may have a polygonal cross-section, in particular in the region of the axial clamping element. In this case, this cross-section should be designed such that this allows a push-through of the axial clamping element through the bore. In this respect, the cross section may, for example, in turn be triangular (in particular equilateral) or square, corresponding to the preferred bore shape.

In addition to the described elements for radial and axial clamping, the dowel may further comprise a tether in the form of a barb. This captive can ensure, for example, that the dowel can first be easily inserted through the hole without turning the dowel it. The hook prevents (for example, on a conveyor belt or in a production line) that the plugged only, but not yet clamped dowel slides out of the hole again, which can occur, for example, as a result of shocks. The captive can be arranged in particular in the region of the axial clamping region.

In a further preferred embodiment of the invention, the dowel head may have an opening, which causes an easier demolding in the manufacture of the anchor. In particular, this breakthrough can be designed such that it allows the use of a simple open-to-tool, in spite of the above-described embodiment of the anchor with the axial clamping projection. In particular, this axial clamping projection would require the use of more complex tools with corresponding cores to allow the undercut between the axial clamping projection and the dowel head. The embodiment according to the invention with the aperture should therefore be designed in particular such that the aperture comprises at least the surface of an axial projection of the axial clamping projection on the dowel head. In this way, considerable investment costs can be saved in the production of the tool, which in turn can significantly reduce the unit prices of the dowels.

embodiments

Further details and features of the invention will become apparent from the following description of a preferred embodiment in conjunction with the subclaims. In this case, the respective features can be implemented on their own or in combination with one another. The invention is not limited to the embodiment.

In detail shows:

1 shows a prior art clamping of a dashboard with a dowel with square cross-section;

Figure 2 is a first view of a dowel according to the invention in a perspective view with a view towards the dowel head;

Figure 3 shows a further perspective view of the anchor according to Figure 2 with

Looking towards the dowel dome;

Figure 4 is a perspective view of the anchor according to Figures 2 and 3 with plugged through a hole in a plate plug;

FIG. 5 shows the arrangement according to FIG. 4 in a perspective view with a view towards the dowel head; and

Figure 6 is a plan view of a dowel head with plugged into a hole dowel with a view parallel to the dowel axis.

FIGS. 2 to 5 show a preferred exemplary embodiment of an anchor 116 according to the invention. In each case, a quarter segment of the otherwise symmetrical dowel 1 16 is shown in these perspective views.

The dowel 1 16 has in this embodiment a total square dowel head 120 and a dowel dome 118 with a substantially circular Cross-section on. Inside, the dowel 116 has a threaded bore 122, which in this example is essentially a cylindrical threaded bore.

Between the dowel dome 1 18 and the dowel head 120, a radial clamping region 124 is arranged next to the dowel head 120. For the embodiment of this radial clamping region 124, reference should be made in particular to the illustration in FIG. It can be seen that, in the radial clamping region 124, the dowel 116 in turn essentially has a circular cross section which corresponds to the circular cross section in the dowel dome 118.

In contrast to this, however, the radial clamping region 124 has radial widenings 126 in the form of four projections 128. These projections 128 have substantially the shape of circular segments, which are applied to the otherwise circular surface of the dowel 16 in the region of the radial clamping region 126. Overall, four equidistant, distributed over the circumference of the dowel in the region of the radial clamping region 124, four such projections 128 are provided, corresponding to an insert in a square bore 1 14 (see Figures 4 and 5). To insert the dowel 116 into these holes 1 14, the projections 128 in the corners of the square of this bore 1 14. With a slight rotation of the dowel 1 16 in the bore 1 14 (for example, when screwing a screw into the threaded hole 122) rotate the projections 128 towards the sides of the square and cause the axial clamping.

An axial clamping element 130 adjoins the radial clamping region 124, towards the dowel mandrel 118, in this exemplary embodiment. This axial clamping element 130 in this case comprises an axial clamping projection 132. This axial clamping projection 132, 130 is formed in this example as a rectangular projection and has on its the dowel head 120 facing side a clamping surface 134 (see Figure 2). This clamping surface is inclined relative to the plane of the dowel head 120, which is indicated in Figure 3 by the angle α.

On the axial clamping projection 132, a captive 136 is disposed on one side, which has the shape of a barb. As can be seen in particular in FIG. 4, this captive device serves to prevent the plug 116 from falling out when the plug 116 is inserted into the bore 114.

Furthermore, in the embodiment illustrated in FIGS. 2 to 5, an aperture 138 is provided in the dowel head 120. This opening 138 is designed such that it is slightly larger than the projection of the axial clamping projection 132 on the dowel head 120. This ensures that parts of the tool, wel- che the undercut between the axial clamping projection 132 and the dowel head 120, through the opening 138 can reach through. In this way, by means of a simple on-to-tool and the complex structure of the dowel 1 16 can be made.

With reference to the figure 6, in conjunction with the embodiments according to Figures 4 and 5, the insertion of a dowel according to the invention 1 16 are explained in a bore 114. Here, Figure 6 shows a plan view of the dowel head 120 when inserted into the bore 114 dowel 1 16, so a view similar to the view shown in Figure 5, but with a view parallel to the dowel axis.

The hole 1 14 is a square hole in one or more plate-shaped elements, for example, it can be assumed again that these plate-shaped elements can be an instrument panel 110 and a sheet 1 12. This makes it clear that the plate-shaped element may comprise one or more such elements, which are fixed by the dowel 116 and in which the dowel 16 is fixed.

FIG. 6 shows a position corresponding to the position in FIGS. 4 and 5, in which the dowel 16 is merely inserted into the bore 114, without hitherto causing a rotation. As described above, both the axial clamping projection 132 and the radial widening 126 or the projection 128 point in the direction of the corner of the square bore 114. It should be noted that in FIG. 6 again only one quadrant of the anchor 116 is shown is, which is due to the symmetry of the anchor 116 is easy to complete a full dowel. However, non-symmetrically constructed dowels 16 are also conceivable in which, for example, there is no mirror symmetry or axial symmetry with regard to the radial widenings 126, the axial clamping projections 132 and / or with regard to captive securing.

Subsequently, which is not shown in FIG. 6, a screw is screwed into the threaded bore 122. As a result, the dowel 116 is acted upon by a torque pointing into the plane of the drawing in FIG.

This torque causes a slight rotation of the plug 116 in the bore 114 in a clockwise direction. There are several effects. First, the radial expansion 126 is pressed against the edge of the opening 114. There may be a slight plastic or elastic deformation of the projection 128 and / or the bore wall occur. In any case, an axial clamping of the plug 116 is effected in the bore 114, and further rotation is prevented. Furthermore, the axial clamping projection 132, as can be seen, for example, from FIG. 4, is arranged on the side of the plate-shaped element 110, 112 opposite the dowel head 120. Upon rotation of the plug 1 16 in the bore 1 14, therefore, the corner of the axial clamping projection 132 is rotated in Figure 5 in the clockwise direction behind the opening 114 so that the corner with the plate-shaped element 1 10, 1 12 overlaps.

For example, as can be seen from Figure 2, due to the inclined arrangement of the clamping surface 134, the distance between the dowel head 120 and the axial clamping projection 132 is not constant. Therefore, the further the corner of the axial clamping projection 132 is rotated beyond the edge of the opening 114, the closer the distance between the axial clamping projection 132 and the dowel head 120 becomes, so that the plate-shaped element 110, 112 in FIGS 5 is acted upon with an axial clamping force. As a result, both elements 110, 1 12 firmly pressed together and firmly connected to the dowel 1 10. In addition, this axial clamping further inhibits rotation of the plug 116 in the bore 114.

LIST OF REFERENCES

110 dashboard

112 sheet metal

114 holes

116 dowels

118 dowel dome

120 dowel head

122 threaded hole

124 radial clamping area

126 radial expansions

128 protrusions

130 axial clamping element

132 axial clamping projection

134 clamping surface

136 captive

138 breakthrough

Claims

claims

1. dowel (116) for use in a plate-shaped element (110, 112), in particular for fixing a dashboard (1 10) of a motor vehicle, comprising a dowel dome (1 18) for insertion into a bore (114) having a non-circular cross-section , wherein the dowel dome (1 18) has a substantially circular cross-section, further comprising a relative to the dowel dome (1 18) at least partially radially projecting dowel head (120), characterized by a between the Dübeldom (1 18) and the Dübel head ( 120) arranged radial clamping region (124), wherein the radial

Clamping region (124) at least one radial expansion (126), such that by rotation of the dowel (116) in the bore (114) a clamping with radial clamping force is effected.

2. dowel (116) according to the preceding claim, wherein the radial clamping region (124) has a substantially circular cross-section, wherein the at least one radial expansion (126) is formed as projecting from the circumference of the circular cross-section projection (128).

3. dowel (1 16) according to the preceding claim, wherein the projection (128) has a rounded shape, in particular at least partially substantially a circular arc shape.

4. dowel (116) according to one of the two preceding claims, wherein the projection (128) has a thickness of not more than 40% of the diameter of the circular cross-section of the radial clamping portion (124), and preferably a thickness between 5% and 20 % of the diameter of the circular cross section of the radial clamping area (124).

5. dowel (116) according to any one of the preceding claims, wherein the radial clamping portion (124) has three or four radial widenings (126), in particular projections (128).

6. dowel (116) according to any one of the preceding claims, wherein the dowel (1 16) additionally between the radial clamping portion (124) and the Dübeldom (118) has an axial clamping element (130), wherein the axial clamping element (130) at least one axial clamping projection (132), such that the dowel (116) in the region of the axial clamping projection (132) protrudes beyond the radial clamping region (124) and in the region of the axial clamping projection (132) has a non-circular cross-section.

7. dowel (1 16) according to the preceding claim, wherein the axial clamping projection (132) has a dowel head (120) facing clamping surface (134), wherein the clamping surface (134) in at least one area a smaller distance to the dowel head (120) as in another area, such that a between the dowel head (120) and the axial clamping element (130) arranged plate-shaped element (1 10, 112) by rotation of the dowel (1 16) can be clamped with an axial clamping force.

8. dowel (1 16) according to the preceding claim, wherein the clamping surface (134) is a flat surface which is inclined to a plane perpendicular to the dowel axis.

9. dowel (116) according to one of the three preceding claims, wherein the dowel (1 16) in the region of the axial clamping element (130) has a polygonal cross-section, in particular a triangular or square cross-section.

10. dowel (116) according to any one of the preceding claims, wherein the dowel (1 16) additionally comprises a captive (136).

1 1. Anchor (116) according to claim 10 and according to one of claims 6 to 9, wherein the captive (136) in the axial clamping region (124) is arranged.

12. dowel (116) according to any one of claims 6 to 9, wherein the dowel head (120) for demolding an opening (138), wherein the opening (138) at least the surface of an axial projection of the axial clamping projection (132) on the dowel head (120).

13. A method for fixing a dowel (116) in a bore (1 14) having a non-circular cross-section, wherein the dowel (116) has a dowel head (120), a

Dowel dome (118) and one between the dowel head (120) and the dowel dome (1 18) arranged radial clamping portion (124), wherein the radial clamping portion (124) at least one radial expansion (126), wherein the dowel (116) the dowel dome (1 18) through the bore (1 14) is pushed until the axial clamping portion (124) within the bore (114) is arranged, wherein then the dowel (116) is rotated about its axis, in particular by Screwing a screw into a threaded bore (122) of the plug (1 16), wherein by the radial expansion (126) clamping with radial clamping force in the bore (114) is effected.

14. The method according to the preceding claim, wherein the bore (1 14) has a bore (114) in a plate-shaped element (110, 1 12), wherein the dowel (1 16) additionally comprises an axial clamping element (130), wherein the axial clamping element (130) has at least one axial clamping projection (132), wherein upon insertion of the dowel (1 16) of the axial clamping projection (132) is completely pushed through the plate-shaped element (110, 1 12), wherein upon rotation of the dowel (1 16) the axial clamping projection (132) is pushed over the plate-shaped element (110, 1 12) and a clamp with axial clamping force of the plate-shaped element (110, 1 12) between the Dübel head (120) and the axial clamping projection ( 132) is effected.