Washer and fastener

The present invention relates to a washer for a fastening element with a peripheral flange, with an annular, apertured disc body and at least one holding web. The invention further relates to a fastening element with a such washer.

A generic washer is known from EP 1091135 A2. This washer has a disk member having at least two integrally formed retaining tabs, to the one provided on the fastener circumferential flange are reversible. To this Way as to maintain the washer to the fastener captive.

When tightening a nut and washer on a fixed bolt should not turn the disc over the strained component. To this end the coefficient of friction between the washer and a component is increased in that at the are provided disc body of the washer notches. These cause the Washer during tightening of a screw bolt on the surface of the component stops, even if the coefficient of friction between washer body and structural se is low.

The German utility model DE 94 00 671 U1 describes a washer instead of Retaining tabs one circulating around the disc body annular web having. measures Increase the coefficient of friction between washer body and structural are not disclosed. At this Embodiment there is also the risk of sticking of nut and washer in order of surface coatings.

The US 2,151,919 A ​​also relates to a nut with a washer whose disk body having on the top and bottom notches, which both with the surface of the component and also interact with the underside of the nut. The notches serve only as a safeguard against the release of the connection.

is When using fasteners generic washers always the risk of damaging the surface of the component by the tilting or pressing of the notches in the component. The preparation of the previously known washers with the modifications of their disk bodies is also complicated to manufacture, because the notches or other surface changes following the manufacture the washer must be additionally attached.

The object of the present invention is a generic washer provide that is easier to manufacture and is formed with a comparable function, in their use damage on the surface of the component are avoided and is at least reduces the risk of sticking of fastener and washer.

The solution consists in a washer having the features of claim 1. According to is therefore provided that arranged on the inner surface of the opening at least two claws are, which protrude radially into the opening.

The advantage of the inventive washer is that it in every phase of the fastening operation, ie, during the screwing and tightening of the fastener acting on a bolt, regardless of the size of this are always forces on the surface of the applied and the fixture remains. This effect is mainly due to two mechanisms.

At the beginning of the fastening operation are two different sized friction radii to distinguish. The first, smaller friction radius r1 defined by the diameter of the bearing region of the Fastener on the claws. The second, larger friction radius r2 defined about the diameter of the effective friction surface of the washer on the component. Since the effective Friction torque is proportional to the friction radius is, the friction torque between washer body and component is greater than the friction torque between fastening element and claws.

It follows that the washer at the beginning of the fastening operation, and also in its further course stops and does not rotate with the fastener. This effect can possibly be enhanced if the contact surface slightly curved inwards is, so that it rests only with its outer edge on the component. The washer so can have a cup-spring-like configuration.

In a later phase of the fastening operation is the claws from the underside of Fastener exercised is so much pressure that they are of downwardly toward Component and simultaneously move inwards in the opening of the disk body inside. The means that the claws are pressed into the thread of the screw bolt and wedged therein. This causes on the one hand, that the washer also at a later stage the fastening operation stops and on the other hand, that the strength of the connection increases between fastener and bolt.

Du RCH the pressing the claws into the thread of the screw bolt deforms the free End of the claws so that a thread is created. This means that upon release of the Fastener washer rotates.

This configuration also causes an associated with the washer according to the invention Fastener resting on the claws in disassembled condition. Thereby remains a gap between the underside of the fastening element and the disc body. When the fastener, for example. With varnish, oil or wax is coated, can during the subsequent spinning off the coating material, the excess material better run. is the risk of sticking of fastener and washer characterized at least reduced.

The washer according to the invention is suitable for any type of fasteners, especially for different nut types, eg. standard hexagon nuts. You can to easily be produced by stamping and forming the holding web and the claws, said holding web and claws can be formed in a single operation.

The present invention is also a fastener having such a Washer.

Advantageous developments emerge from the dependent claims.

A particularly preferred embodiment of the washer has three or four claws, which are preferably arranged offset from one another. The effects described above are particularly effective in this embodiment.

Another advantageous development provides that the free ends of the claws towards the fastener above the washer body are so that they at fixing operation particularly far pushed downwardly and inwardly and thus particularly firmly into the thread the bolt are pressed.

Advantageously, the claws are on their side facing the fastener side each provided with a support surface for the underside of the fastening element, so that the friction radius r1 concerned to define precisely. This support surface may, for example. Characterized are formed so that the claws in cross section have an approximate S-shape or Z-shape. However, the claws can be made straight. The height of the claws above the washer body is preferably as large as the material thickness equally to double.

The claws can further comprise at their free end a circular-segment-shaped recess, which facilitates the pressing of the claws into the thread of the screw bolt. there the shape and size of the indentation adapted to the circumference of the screw bolt be. Instead, the claws may at its free end and a straight edge , such that they are pressed particularly far into the thread of the bolt, even be more deformed and wedged even more effective.

The claws can, depending on the design of the washer and the fastening element, be about 1 to 3 mm long. Preferably, their length corresponding to about twice the thickness the material used for the manufacture of the washer (eg. of the sheet). Important is that the length of the claws is dimensioned such that after screwing the of them defined diameter d1 is less than the core diameter of the bolt being used. So that means that it has a relation to the core diameter of the screw bolt have excess. Finally, it is of advantage, the diameter d2 of the opening in the washer body tune to the nominal diameter of the thread of the fastening element, thus resulting in an optimal, force-bearing surface.

The at least one holding web of the washer can be used as closed circumferential annular web or in the form of a singly or multiply radially slotted annular web or in the form of be formed at least two retaining tabs. A closed annular web simplifies Punching tool for the manufacture of the washer, while the divided retaining webs facilitate forming.

In the following the invention with reference to an embodiment shown in the accompanying figures described in detail. Show it:<dl tsize="7"><dt>figure 1</dt><dd>a plan view of an embodiment of a washer according to the invention in schematic, not true to scale;</dd><dt>figure 2</dt><dd>a sectional view of the washer taken along the line II - II in Figure 1;</dd><dt>figure 3</dt><dd>is a partially sectioned view of a fastening element with the Washer according to Figure 1 after screwing components.</dd></dl>

Figures 1 and 2 show an embodiment of a washer according to the invention 10, which in Figure 2, the fastener 30, in the example a standard hexagon nut, is indicated by dash-dotted lines. The nut 30 has a nut body 31 with a circumferential outer flange 32. The flange 32 is formed integrally with the nut body 31st

The washer 10 includes a washer body 11 having a circumferential annular web 12 on. The disk body 11 is provided with an opening 13, which in one embodiment has diameter D2 to the diameter of the fastening element used tuned. The annular web 12 surmounted axially the flange 32 of the nut body 31 and is bent at its upper end 14 radially inwardly over the flange 32nd Of course, a single or multiple takes a circumferential annular web slotted annular web may be formed. Finally, individual (at least be two) holding lugs.

The washer 10 is held on the fastening element 30 loosely rotatable. to this Purpose is both axially and radially, at least a slight clearance between the flange 32 the nut body 31 and the annular rib 12 of the washer 10.

From the inner surface 15 of opening 13 project in the exemplary embodiment four by the same Angle offset claws 16 radially into the opening 13 inside. There may also be more than four or less than four claws 16 can be provided. The claws 16 need not to the same Angle be offset each other.

In the exemplary embodiment, the ends 17 of the claws 16 are in the direction on the fastener 30 disposed above the disk body eleventh The distance from the disk body 11 in the exemplary embodiment twice the thickness of the used for washer Sheet, or about 2 mm. The distance can, however, also be chosen larger or smaller. The claws are further bent in cross-section approximately S-shaped. Thereby forming the upper part of S is a support surface 18 for the bottom of the fastener 30th

The length of the claws 16 in the embodiment corresponds to about twice the thickness of the for the manufacture of the washer plate 10 used and is about 2 mm at 1 mm thickness. With their free ends 17, the claws 16 define a diameter d1 within the opening 13 of the disc body 11. The diameter d1 is smaller therefore than the diameter d2 of the opening 13 itself. The length of the claws 16 is dimensioned in a particular case, that the diameter d1 after screwing is less than the core diameter of the Bolt used in each case. The claws 16 therefore have relative to the core diameter the screw bolt to an excess.

The ends 17 of the claws 16 are formed in the embodiment linear. In Figure 1 is a Another variation indicated by dash-dotted lines, in which the ends 17 circular segmental indentations 19 exhibit. The curvature of the indentations 19 may further to the diameter be adapted to a later screwed in bolt.

The washers 10 of the invention is in a conventional manner by punching a blank and then molding the annular web 12 and the claws 16 are made. Here, the annular web 12 and the claws 16 may be formed in a single operation.

Figure 3 shows the fastener 30 with the washer 10 of Figure 1 after the Assembly of two parts 21, 22 by a bolt 33. The Figure 3 is to found that the acting by the screw bolt 33 forces when pulling down the fastener 30 toward the disk body 11, the claws 16 downwardly and pressed inwards and thereby pressed into the thread 34 of the screw bolt and have keyed in.

The washer according to the invention therefore does not require subsequent modifications of Disk body 11 and causes yet reliable that the washer during the fastening operation does not rotate.