retaining washer

Abstract

The invention relates to a fixing washer for arrangement on a flat base (4), having a ring-shaped washer body (1) which has a convex course from an inner edge to an outer edge, wherein the washer has a cross-section which is formed by at least two mutually transitioning circular arcs (13, 14) having different radii (r1, r2).

Description

Technical Field

[0001] The present invention relates to a fixing washer for placement on a flat substrate as described in the preamble of claim 1. Background Technology

[0002] The purpose of these retaining washers is to counteract the loosening process in screw connections. This loosening process is caused by the loss of preload in the screw connection, which is due to settlement and / or creep processes in the screwed components.

[0003] To prevent loosening, the retaining washer must have sufficient spring force over a certain spring travel to compensate for the loss of preload due to settlement and / or creep, thereby maintaining the clamping force required for the safe operation of the screw connection.

[0004] To achieve sufficient spring force over a given spring travel, various washer structures have been proposed; the simplest of these structures is the tension washer according to DIN 6796:2009-08. In this known structure, with the same washer body thickness, the outer ring section transitions directly to the inner ring section without any visible dividing lines.

[0005] For example, DE-B 2061297 discloses another type of structure. In this structure, the underside of the washer is divided into an outer ring section and an inner ring section by a step. Therefore, when tightening the screw connection, the outer ring section is first pressed against the base, thereby generating an initial spring force with a certain spring travel. Upon further tightening, the force is introduced through the relatively rigid step, resulting in a relatively high spring force with a very small spring travel. However, due to the leverage effect of the step, there is a risk that during further tightening, the outer edge of the outer ring section may lift off the base, so that ultimately all the load is concentrated in the stepped area. Therefore, this area also bears the load to the maximum extent. This type of washer structure is therefore only suitable for fixing tasks that allow for relatively high pressure per unit area in the area supported below the step.

[0006] DE-A 40 25 146 discloses another washer structure. In this known structure, the outer ring section's surface transitions continuously (i.e., without steps or the like) to the inner ring section's surface. However, in this washer structure, the transition region has a smaller cross-section than the rest of the washer body. This smaller cross-section in the transition region is achieved by an annular groove arranged on the upper side of the washer. Due to this annular groove on the upper side of the washer, this type of washer structure tends to "open up," particularly when the washer body thickness is small and the tightening force is too high, thus preventing tilting in the outer edge region or in the outer ring section's surface. By constructing the portion of the washer body with the outer ring section's surface to be relatively large, this "opening up" in this type of washer structure can be mitigated in terms of its effect. This means that this type of washer structure produces its complete fixing effect, especially with large outer diameters.

[0007] EP2287477A1 describes a retaining washer with a frustoconical shape, in which the outer and inner ring segments are arranged at an angle to each other on the underside facing the substrate, with the two ring segments forming an acute angle with the substrate. This retaining washer, known as a "locking washer (Sperrkantscheibe)," has been proven in practice because it can be easily manufactured with low material usage and exhibits good spring and retaining properties. Its outstanding feature is particularly due to the angle between the two ring segments, resulting in a small residual spring travel, three support points—below the helical head, inside the ring segments, and outside the surrounding edge—leading to a high residual spring force compared to known tension washers. With this locking washer, planar support is not possible because it would lead to excessive stretching of the material, eventually causing the washer to break in the transition region between the two ring segments.

[0008] Components made of non-ferrous metals (such as cast aluminum) possess strength nearly as high as that of steel. For this reason, a preload similar to that used when tensioning steel components is employed. Therefore, steel spiral connections are typically used for tensioning components made of non-ferrous metals due to the preload and lower cost. However, the limiting flow stress of non-ferrous metal materials (such as cast aluminum) is significantly lower than that of steel, making it important to achieve the most uniform support surface possible, and thus the most uniform surface pressure. For this purpose, an additional flat washer is typically used between the retaining washer and the substrate to counteract pressure spikes. Summary of the Invention

[0009] This invention begins here. The object of this invention is to provide a retaining washer of the type described above, which, while possessing at least the same retaining properties, enables planar support on a corresponding object. According to the invention, this object is achieved by a retaining washer having the features of the characteristic portion of claim 1.

[0010] The present invention provides a retaining washer that achieves planar support on a substrate while maintaining at least the same retaining properties. Because the washer has a cross-section formed by at least two mutually transitional arcs of different radii, the retaining washer can fully support the substrate upon reaching the preload, given the desired residual spring travel. Surprisingly, it has been found that a significantly increased residual spring force can be achieved by using the cross-section according to the invention, which has at least two mutually transitional arcs of different radii. Preferably, the retaining washer is made of spring steel.

[0011] By changing the position of the radius center point and the radius ratio, the height of the fixing washer and the trend of the residual spring force can be set. In the fixing washer according to the present invention, the spring action and the trend of the residual spring force are generated not only by the compressive and tensile stresses on the upper or lower side of the washer and the circumferential stress on the outer diameter, but also by the arc-shaped cross-section of the washer.

[0012] In an improved embodiment of the invention, the radius of the arcs converging at the inner edges is smaller than the radius of the arcs converging at the outer edges. This allows the outer region of the retaining washer to abut against the substrate in a ground-like manner earlier.

[0013] In one design of the present invention, the material thickness of the fixing washer in the inner edge region is greater than the material thickness in the outer edge region. This further improves the residual spring force.

[0014] In another embodiment of the invention, the underside of the washer facing the substrate has teeth. This prevents the retaining washer from rotating and keeps it firmly on the substrate.

[0015] In an improved embodiment of the invention, a coding structure is provided on the upper side of the washer, opposite to the lower side of the washer. This achieves an improved fixing effect. The coding structure can be confined to the inner ring region and is designed, for example, in a knurled form.

[0016] In one design of the present invention, the outer edge is constructed with sharp edges. This assists the outer annular surface in cutting into the substrate. Attached Figure Description

[0017] Other improvements and designs of the present invention are given in the remaining dependent claims. Embodiments of the present invention are shown in the accompanying drawings and described in detail below. Wherein: Figure 1 A schematic diagram of the retaining washer is shown; Figure 2 Showing from Figure 1 A schematic diagram showing the retaining washer before tightening the screw. Figure 3 Showing from Figure 1A detailed view of the retaining washer located between the screw head and the base in cross-section; Figure 4 Showing from Figure 3 A schematic diagram of a connection arrangement structure with a tightening screw. Detailed Implementation

[0018] The retaining washer selected for this embodiment is made of C60 spring steel and includes a washer body 1 that is substantially annular in construction, having an upper washer side 11 and a lower washer side 12. The upper washer side 11 is provided with a coding structure (not shown), which in this embodiment is implemented in the form of embossing. The washer body 1 is arched in construction. Here, its cross-sectional profile is formed by two mutually transitional arcuate segments 13 and 14, wherein the radius r1 of the first inner arcuate segment 13 is smaller than the radius r2 of the second outer arcuate segment 14.

[0019] Figure 2 The arrangement of the retaining washer according to the invention is schematically depicted. Here, the screw 5 guides the washer body 1 through the retaining washer and the hole 41 in the base 4. Figure 2 In this configuration, the screw 5 is not tightened, meaning the retaining washer is in an untensioned state. Here, it is supported on the base 4 by the inner edge 2 of the arched inner section and the outer edge 3 of the washer body 1. The outer edge 3 is constructed with sharp edges. As a result, the retaining washer cuts more strongly into the base 4 when in the tensioned state.

[0020] When the screw 5 is tightened, the washer body 1 is pressed against the corresponding object 4, wherein the two arc-shaped sections 13 and 14 of the washer body 1 gradually flatten. Due to the different radii r1 and r2 of the two arc-shaped sections 13 and 14, the surface of the lower side 12 of the washer moves outward until the washer body 1 is supported on the base 4 in a planar manner, thereby causing residual spring tension. By selecting the radii r1 and r2 of the two sections 13 and 14, the residual spring tension of the fixing washer can be set.

Claims

1. A fixing washer for placement on a flat substrate (4), the fixing washer having an annular washer body (1) having a convex shape from an inner edge to an outer edge, characterized in that, The washer has a cross-section formed by at least two intercontinental arcs (13, 14) with different radii (r1, r2).

2. The fixing washer according to claim 1, characterized in that, The radius (r1) of the arc (13) that meets at the inner edge (2) is smaller than the radius (r2) of the arc (14) that meets at the outer edge (3).

3. The fixing washer according to claim 1 or 2, characterized in that, The material thickness of the retaining washer in the region of the inner edge (2) is greater than the material thickness in the region of the outer edge (3).

4. The retaining washer according to any one of the preceding claims, characterized in that, The washer (12) facing the base (4) has teeth.

5. The retaining washer according to any one of the preceding claims, characterized in that, The upper side (11) of the washer, which is opposite to the lower side (12) of the washer, is provided with a coding structure.

6. The retaining washer according to any one of the preceding claims, characterized in that, The outer edge (3) has a sharp edge structure.

7. The retaining washer according to any one of the preceding claims, characterized in that, The retaining washer is made of spring steel.

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