IE904010A1

IE904010A1 - Self-locking fastening device

Info

Publication number: IE904010A1
Application number: IE401090A
Authority: IE
Inventors: Dipl-Ing Dietrich Blume; Dipl-Ing Josef Esser; Dipl-Ing Friedrich W Grossmann; Dipl-Ing Norbert Peukes; Franz Ludwig Schmittmann
Original assignee: Bauer & Schaurte Karcher Gmbh
Priority date: 1989-11-08
Filing date: 1990-11-07
Publication date: 1991-05-08
Also published as: ATE93303T1; ES2042940T3; IE64954B1; DE58905334D1; EP0426895B1; PT8465U; EP0426895A1; PT8465T

Abstract

The invention relates to a self-locking fastening device having a screw or nut for fastening at least one first component to another component, the locking effect being obtained by means of ribs on surfaces that engage with one another, which ribs are chamfered in such a manner that a smooth roller effect is achieved. The fastening device has a disc (1) which is constructed on its surface facing the first component (B) such that, when the fastening device is tightened, said disc is held on the first component such that it cannot rotate and the surface opposite it has ribs (2) which are chamfered in such a manner that, when the screw or nut is tightened, a smooth roller effect is achieved on the surface of the screw or nut as a result of relative rotation between the surface of the screw or nut facing the disc (1) and the opposite surface of the disc. <IMAGE>

Description

The invention relates to a self-locking fastening device having a screw or nut for fastening at least one first component to another component, the locking effect being obtained on surfaces coming into engagement with one another by means of ribs which are rounded in such a way that a burnishing effect is achieved. The fastening device has a disk (1) which is constructed on its surface facing the first component (B) in such a way that it is held non-rotatably on the first component when the fastening device is tightened, and which has on its opposite surface ribs (2) which are rounded in such a way that a burnishing effect is achieved on the surface of the screw or nut when the screw or nut is tightened by relative rotation between the surface of the screw or nut facing the disk (1) and the opposite surface of the disk. • i PATENTS ACT 1964 COMPLETE SPECIFICATION T.'>W T .3 '1- £ *?’' it ·' Λ λ S; 1/¼ V. £ * ’ A ϋ Λ?- U L «ι s ' *·· SELF-LOCKING FASTENING DEVICE Γ',’ BAUER & SCHAURTE KARCHER GmbH, A Gesellschaft mit beschrankter Haftung organised and existing under the laws of the Federal Republic of Germany, of Further Strasse 24/26, D-4040 Neuss/Rhein, Federal Republic of Germany 6015 Self-locking fastening device The invention relates to a self-locking fastening device having a screw or nut for fastening at least one first component to another component, the locking effect being maintained on surfaces coming into engagement with one another by means of ribs which are rounded in such a way that a burnishing effect is achieved.

A self-locking fastening element such as, for 10 example, a screw or nut is disclosed in German Patent Specification 2,556,985, the end face of which interacts with one component and has a number of ribs which are rounded in such a way that, when the fastening element is rotated relative to the component, a burnishing effect is achieved on its1 surface. The burnishing effect leads to an even compacting of the contact surface of the component under the head of the fastening element. The locking effect arises due to the fact that the elastic-plastic deformations occurring when the fastening element is tightened lead to bulges between the ribs on completion of the tightening operation, which bulges provide adequate resistance to self-acting detachment.

When using the known fastening element, an adequate locking effect can be obtained when the material of the component allows a burnishing effect to be achieved with the above effect. However, components are increasingly used which are made of a material which cannot be adequately compacted, for example various plastics, inter alia fibre-reinforced plastics.

There is therefore a need to obtain a fastening device which produces a locking effect by means of the burnishing effect mentioned even when fastening components made of not adequately compactable material.

A fastening device with which this is achieved has a disk which is constructed on its surface facing the first component in such a way that it is held nonrotatably on the first component when the fastening device is tightened, and which has on its opposite surface ribs which are rounded in such a way that a burnishing effect is achieved on the surface of the screw - 2 or nut when the screw or nut is tightened by relative rotation between the surface of the screw or nut facing the disk and the opposite surface of the disk.

A disk for a fastening device is known from 5 German Offenlegungsschrift 2,811,108, which has a construction in the form of a toothing on its surface facing the component to be fastened, which construction has the effect that the disk is held non-rotatably during tightening on the component to be fastened. On its other surface which is facing the contact surface of the screw or nut, the known disk likewise has a toothing with sharp edges. When using such a disk, when the screw or nut is tightened catching results between the toothing of the disk and the contact surface of the screw or nut, due to which damage to the contact surface of the screw or nut is caused. This is undesirable because, for example, the service life of the screw or nut can be reduced in an inappropriate manner. Additionally, there are produced chippings which can pass onto places at which they are undesired and at which they can constitute a source of danger.

Further features of the invention are specified in the sub-claims.

The invention is explained below with reference to the drawing by way of example.

Figure 1 is a diagrammatic illustration of a fastening device according to the invention.

Figures 2 to 8 show preferred embodiments of the design of the ribs formed on that surface of the disk which faces the contact surface of the screw head or the nut.

Figure 1 illustrates a fastening device which has a screw S by means of which a first component B is to be fastened to another component (not illustrated). It should be noted that, instead of a single first component B, several first components may also be present which are to be fastened to each other and to another component.

Furthermore, the fastening device has a disk 1 which has constructions on its surface facing component - 3 B, which constructions guarantee that, during tightening, the disk 1 is held non-rotatably on the relevant surface of component B. The constructions can be of any desired type known per se as long as the effect described above is achieved, namely that the disk 1 is held non-rotatably on component B during tightening.

On its surface facing the contact surface 3 of the screw head, the disk 1 has ribs 2 which are rounded in such a way that a burnishing effect is achieved on the surface of the contact surface 3 of the screw head on relative rotation between the contact surface 3 of the screw head and the disk 1.

Burnishing is understood to be a presspolishing process also described in precision mechanics as rolling, by means of which smooth and compacted surfaces are produced on metal workpieces without cutting. Accordingly, when using a fastening device according to the invention, an essentially even compacting of the entire contact surface 3 of the screw head results during tightening.

In contrast to the above, when using known selflocking fastening devices, an uneven compacting of the relevant contact surface results, compacting being obtained at the points, at which the teeth (German Offenlegungsschrift 2,811,108) come to rest after tightening, which compacting is substantially higher than the compacting at the points between the teeth. If a known self-locking’'fastening device of this type is loaded with an external force above the assembly prestressing force, the teeth are pushed in even further since the hitherto only slightly compacted regions under the tooth gaps are now called into use. The connection becomes seated. By comparison, the fastening device according to the invention has the advantage that the entire contact surface of the screw head is essentially evenly compacted so that consequently correspondingly higher loads are required to produce a seating. Accordingly, the risk of seating is correspondingly lower. Seating is understood here to be the phenomenon that a loss of prestress results after - 4 completion of the tightening operation as a result of subsequent material flow in the screw head.

It is understood that the effects described above occur in the same manner when, instead of the screw S according to Figure 1, a nut is used which is screwed onto a thread.

Figures 2 to 6 represent various cross-sectional shapes of the ribs 2. These ribs are represented in a partially rolled back illustration.

The ribs 2a according to Figure 2 have an essentially rectangular shape, the free edges, however, being so greatly rounded that, when a screw or nut is tightened, the ribs virtually slide over the material of the contact surface 3 with a rolling effect without penetrat15 ing it, but in this case, with increasing prestress, produce an increasing and evenly effected compacting of the material of the screw head. Nevertheless, when used with ribs 2a according to the cross-sectional shape represented in Figure 2, adequate locking against self20 acting detachment is obtained.

In the embodiment according to Figure 3, the ribs 2b have an essentially semicircular outline and the transitions on the disk 1 are also constructed with a comparatively large radius .

In the embodiment according to Figure 4, the ribs 2c have an essentially trapezoidal cross-section, the free edges obviously again being provided with an adequately large rounding radius so that the effect described above occurs.

In the embodiment according to Figure 5, the ribs 2d have a cross-section in the form of a greatly rounded asymmetrical trapezium.

In the embodiment according to Figure 6, the ribs 2e have a cross-section which is bounded by a permanently asymmetrical contour altering at each point of its rise.

The ribs illustrated in Figures 2 to 6 can project from a flat surface, but they can also be connected to the surface and/or to each other by any desired curved contours .

In Figures 7 and 8, ribs 2f and 2g respectively are illustrated which have a symmetrical profile and the shape of an isosceles triangle with a rounded tip according to the invention.

It has been established in practical tests that the desired effect similar to the effect of rolling elements was obtained, for example in rib shapes according to Figures 7 and 8, if a rounding radius in the range of 0.15 to 0.17 nun was used on the part of the ribs coming into engagement with the contact surface 3 of the screw or nut S. In this case, different side angles in the range of 50 to 120° and a rib height of, for example, I 0.17 mm were used.

It should be established that the rounding radius of the ribs is only critical to the extent that the abovementioned effect similar to the effect of a rolling element is guaranteed to be maintained when the fastening element is rotated relative to the disk 1. There may thus be deviations from the values specified above for the rounding radius as long as the desired effect is maintained. The same applies to the values specified in respect of the side angle and the rib height. Here, too, the relevant values specified merely constitute values applied by way of example in practical tests.

It should be established further that the number of ribs used in each case depends on particular applications, particular requirements and the like. It can be stated in general that the number of ribs provided is within the range customarily used. Furthermore, the ribs may be present in an even distribution and arrangement.

However, they may also be present in certain cases in an uneven distribution and arrangement.

It is furthermore to be understood that the ribs 2 may extend radially over a part of the surface of the disk 1 facing the screw head or over the entire surface.

Furthermore, the ribs 2 may be of curved construction and extend, in turn, over a part or over the entire surface of the disk 1 which faces the contact surface 3 of the screw head. - 6 In this case, it is possible to provide on the surface of the disk 1 facing the screw head ribs extending solely in the radial direction or curved ribs which extend over the entire surface of the disk 1. It is likewise possible to provide on this surface of the disk radially extending or curved ribs which extend only over a part of this disk surface. It is finally also possible to provide on the surface of the disk 1 facing the screw head ribs in regular or irregular patterns which extend over the entire surface of the disk 1 and ribs which extend only over a part of this disk surface.

It is also within the framework of the invention to provide flat surfaces, for example on the outer circumference of the surface of the disk 1 facing the screw head or between certain ribs or groups of ribs, by means of which flat surfaces, for example, a sealing off effect can be achieved, or which bound the height of the bulges. The latter bounding effect can be advantageous, for example, in the case of screws or nuts made of relatively soft material.

In a further preferred embodiment which is not illustrated in the drawing, the disk has ribs on both surfaces which are rounded in such a way that the explained burnishing effect is achieved. A disk of this type is simpler to manufacture than a disk which has different constructions on its two surfaces. Nevertheless, it is guaranteed even when using a disk of this type that, when the fastening device is tightened, the disk is held against rotation on the component to be fastened. At the same time, the advantage results that, when using this disk, attention does not have to be paid to the fact that the disk is situated in its correct position.

Virtually all known forms and shapes can be used for the form of the disk.

Self-locking fastening device

Claims

1. Patent Claims

1. Self-locking fastening device having a screw or nut for fastening at least one first component to another component, the locking effect being maintained on surfaces coming into engagement with one another by means of ribs which are rounded in such a way that a burnishing effect is achieved, characterized in that the fastening device has a disk (1) which is constructed on its surface facing the first component (B) in such a way that it is held non-rotatably on the first component when the fastening device is tightened, and which has on its opposite surface ribs (2) which are rounded in such a way that a burnishing effect is achieved on the surface of the screw or nut when the screw or nut is tightened by relative rotation between the surface of the screw or nut facing the disk (1) and the opposite surface of the disk.

2. Fastening device according to Claim 1, characterized in that the surface (3) of the screw or nut opposite the disk (1) is smooth. 3. Fastening device according to Claim 1 or 2, characterized in that the disk (1) is provided so • as to be removable. 4. Fastening device according to Claim 1 or 2, characterized in that the disk (1) is connected to the screw or nut so as to be freely rotatable but captive.

3. 5. Fastening device according to one of Claims 1 to 4, characterized in that the ribs (2) extend radially over a part of the surface of the disk (1) facing the screw or nut (S) or over the entire surface.

4. 6. Fastening device according to one of Claims 1 to 4, characterized in that the ribs (2) are of curved construction and extend over a part or the whole of the surface of the disk (1) facing the screw or nut (S).

5. 7. Fastening device according to one of Claims 1 to 6, characterized in that the rounded ribs are provided on both surfaces of the disk (1).

6. 8. Fastening device according to one of Claims 1 to 7, characterized in that flat surfaces are formed on the outer circumference of the surface of the disk (1) facing the screw or nut or between individual ribs or groups of ribs, which flat surfaces have a sealing-off effect or bound the height of the curves arising in the burnishing effect.

7. 9. A fastening device substantially as described herein with reference to and as shown in Figure 1 of the accompanying drawings, or Figure 1 taken together with any one of more of Figures 2 to

8. Dated this 7th day of November, 1990.