TECHNICAL FIELD:

The invention relates to a device for rotational locking of a fastening element, according to the preamble of appended claim 1. In particular, the invention relates to a device which functions as a lock or a shoulder for fastening elements, for example bolts or screws which are arranged in cast or forged materials. The invention also relates to a method for producing such a device, according to the preamble of appended claim 9.

TECHNICAL BACKGROUND OF THE INVENTION:

Construction elements such as forged beams and attachment consoles in, for example, motor vehicles often comprise through-going holes for bolts and similar fastening elements. These fastening elements can be used to attach various components to the beam or the attachment console.

In connection with, for example, heavy cargo vehicles such attachment consoles are often utilized for attaching heavy components, e.g. for attaching the front axle of the vehicle. For this purpose the attachment console can be made from a cast or forged material, for example nodular iron.

Fig. 1 shows a view from above of a section of a previously known construction element in the shape of an attachment console 1, which according to conventional technology is shaped by casting. The attachment console 1 comprises a recess 2, which has been shaped during the casting process. At the bottom of the recess 2, there is a through-going hole 3. The arrangement is also explained by Fig. 2, which shows a view of a cross-section of the attachment console 1. The hole 3 is intended to let through an attachment element in the form of a bolt 4. The inner side walls of

the recess 2 are dimensioned with somewhat larger inner dimensions than the outer dimensions of the head 5 of the bolt 4. In this way, these side walls can serve as a lock or a shoulder for the bolt 4, so that it is not caused to rotate when it, for example, is attached by means of a nut 6 or a similar component at the rear side of the attachment console 1.

Although the above-mentioned, previously known arrangement functions relatively satisfactorily for locking the bolt 4, it has a serious drawback in that the hole 3 in the recess

2 must be positioned and drilled with a very high degree of accuracy. If the position of the hole 3 deviates too much sideways from the line of symmetry in the bottom surface of the recess 2, the head 5 of the bolt 4 cannot be housed in the recess 2, i.e. it will simply not be possible to bring the bolt 4 down into the hole 3. This limitation in turn means that very high demands must be made on the manufacturing and processing of the attachment console 1, where in particular very high tolerances are demanded when drilling the hole 3. This of course leads to time- and cost- consuming measures, which are not desirable.

SUMMARY OF THE INVENTION: The object of the present invention is to obtain an improved device for rotational locking of a fastening element, e.g. a screw, a bolt or a nut in a construction element, which device both provides a secure locking of the fastening element and permits a relatively high tolerance when drilling said hole. This object is achieved by means of a device of the initially mentioned kind, the characteristics of which will become evident from appended claim 1.

A further object of the present invention is to provide a process for manufacturing the above-mentioned arrangement.

This object is achieved by means of a process of the initially mentioned kind, the characteristics of which will become apparent from appended claim 9.

The invention constitutes a device for locking, in the direction of rotation, a rotatable fastening element in a construction element, e.g. a fastening console. The invention comprises a recessed part formed in the construction element, in which part a hole is made and where the recessed part also comprises means for said locking of the fastening element. According to the invention, said means comprise at least one protruding element which has been formed in connection to the bottom surface of the recessed part, which element is shaped with an edge surface which faces the hole and which has been positioned at a predetermined distance from the centre of the hole.

Since the hole can be drilled with a low degree of accuracy, a construction element which comprises the invention can be produced at a low cost.

Advantageous embodiments will become evident from the appended dependent claims.

The term "fastening element" in this context refers to screws, bolts and similar components which are intended for rotatable or screwable positioning through a hole in a construction element, e.g. a fastening console. This term also refers to nuts and similar components which are intended to interact with screws or similar components.

BRIEF DESCRIPTION OF THE FIGURES:

The invention will in the following be described more closely with reference to the appended drawings, where:

Fig. 1 is a view from above of a previously known device for locking a screw,

Fig. 2 is a cross-sectional view from the side of the previously known device of Fig. 1,

Fig. 3 is a perspective view which shows the device according to the present invention after a first manufacturing step,

Fig. 4 is a perspective view which shows the device according to the invention after a further manufacturing step,

Fig. 5 is a view from above which shows the device of

Figs. 3 and 4, in which the positioning of a screw is apparent, and

Fig. 6 is a further view from above of the device according to Figs. 3 and 4.

PREFERRED EMBODIMENT:

Fig. 3 shows a perspective view of a part of a construction element in the form of an essentially longitudinal fastening console 7, which for example has been made from cast nodular iron. The invention is mainly, but not exclusively, intended to be a part of a fastening console 7 for attaching the axis of a wheel of a cargo vehicle. According to the preferred embodiment, the invention is manufactured in three main manufacturing steps. Fig. 3 shows the device according to the invention after the first of these three steps, which preferably consists of a casting process during which the attachment console 7 is shaped with a recessed part 8. Seen from above, the recess part 8 has an essentially circular form. Furthermore, the

recessed part 8 is shaped with a bottom edge 9 and an essentially vertical inner side wall 10.

Furthermore, the recessed part 8 is formed during the casting in such a way that a plurality of protruding elements 11, preferably six, are formed on the bottom surface 9 of the recessed part 8. The protruding elements

11 are shaped as bars or protrusions which have their extension from the side wall 10 and towards the centre of the recessed part 8. The protrusions 11 are preferably arranged at equal distances from each other along the side wall 10. The surface inside the protrusions 11 in this way forms a surface shaped for a fastening element.

When the console 7 has been formed with the protrusions 11, a hole is drilled essentially in the centre of the recessed part 8. Fig. 4 shows a perspective view where this hole 12 can be seen. The hole 12 is intended to admit a bolt or a similar fastening element. Furthermore, according to a third manufacturing step, the end surface 13 of the respective protrusions 11 is processed. In this manner, the respective protrusions 11 are somewhat shortened, by means of which the distance from the centre of the hole 12 to all of the end surfaces 13 of the protrusions 11 becomes essentially equal. This processing can be made using known technology, e.g. by means of a (not shown) milling tool which can comprise a peg which protrudes down into the hole

12 and a part which essentially works in a circular pattern, with a larger radius than the radius of the hole 12 (i.e. a radius corresponding to the distance from the centre of the hole 12 to the respective end surfaces 13). During this process, the end surfaces 13 are shaped so that they become slightly curve-shaped.

The main reason that the protrusions 11 need to be processed separately so that the end surfaces 13 are formed

is that the casting process does not permit sharp edges and similar details to be formed in the console 7.

In a version of the invention, the drilling of the hole 12 and the processing of the protrusions 11 can be carried out in one single step. This can, in this case, be done by means of a suitable tool with a combined drilling and milling function.

If a screw (not shown in Fig. 4) is brought down into the hole 12, each side of the screw head will be positioned in front of one end edge 13 of the respective protrusions 11. If the screw is caused to rotate, e.g. when a nut is screwed onto the screw at the rear side of the console 7, the screw will turn until the respective sides of the screw head are blocked by a protrusion 11. In this way, each end surface 13 serves as a stopping element or a shoulder which prevents further rotation of the screw.

The basic principle of the invention is based on the fact that the drilling of the hole 12 can be carried out with a relatively low degree of accuracy. This is possible since the end surfaces 13 are processed so that their distances to the centre of the hole 12 become essentially equal, which in turn causes the position of a positioned screw to always be related to the end surfaces 13 and not to the side wall 10 of the recessed part 8. This principle of the invention will become apparent from Figs. 5 and 6, which show views from above of the recessed part 8 in which a screw has been positioned.

Fig. 5 shows a case where the hole 12 has been drilled essentially in the centre of the recessed part 8. Furthermore, the six protrusions 11 have been processed so that they have been shaped with one edge surface 13 each. Since the tool which is utilized to process the end

surfaces 13 normally is of a circular shape, the end surfaces 13 become slightly curve-shaped. For reasons of clarity, Fig. 5 also shows - with broken lines - the initial shape of the protrusions 11, i.e. the shape they have after the initial casting process (see Fig. 3).

When positioning a screw through the hole 12, the screw will be brought into place so that its head 14 rests on the bottom surface 9 of the recessed part 8. The six protrusions 11 have a certain vertical extension as seen from the bottom surface 9, which extension is suitably adapted to the height of the screw head 14. The screw defines an axis of rotation through the console 7 which essentially coincides with the extension of the hole 12. When the screw head 14 is rotated, which normally takes place when attaching a nut or the like on the underside of the hole 12, each side of the screw head 14 will be in contact with one protrusion 11. In this way, a locking against rotation of the screw head 14 is obtained.

Fig. 6 shows a case where the drilling of the hole 12 has been carried out with a relatively high degree of inaccuracy. The figure, in similarity to Fig. 5, shows the recessed part 8, however with the difference that the hole 12 in Fig. 6 has been drilled a certain distance from the centre of the recessed part 8. This has caused the hole 12 to here be positioned a distance to the left in the figure relative to the centre of the recessed part 8.

As has been explained above, the processing of each protrusion 11 is carried out in such a way that the radius from the centre of the hole 12 to each end plane 13 is essentially equal for all of the protrusions 11. This means that there will always be enough room for the screw head 14 which can be locked against rotation (provided that said radius is adapted to the dimensions of the screw head 14)

although the drilling of the hole 12 has been carried out with large tolerances.

Each protrusion 11 thus has an edge 13 which faces the screw head 14, which will come into contact with the respective side of the screw head 14 during rotation of the screw. As can be seen in Figs. 5 and 6, the protrusions are shaped in such a manner that the edges 13 are positioned at a predetermined distance to the axis of rotation of the screw, essentially independently of the position of the axis of rotation on the bottom surface 9.

Since the position of the hole 12 is displaced from the centre of the recessed part 8, the protrusion 11' which is shown at the extreme left in Fig. 6 will be processed to a relatively great extent. In a corresponding manner, the protrusion 11' ' which is shown at the extreme right in Fig. 6 will be processed to a relatively small extent. This fact, however, does not affect the locking of the screw head 12 between the protrusions 11, since the distance between the centre of the hole 12 and the respective end surfaces 13 is always essentially equal essentially independently of the position of the hole 12 inside the recessed part 8.

Fig. 6 also shows with broken lines the shape of the protrusions 11 immediately following the casting process. The part of each protrusion 11 which is indicated with broken lines will thus be removed during the above- mentioned processing.

The invention is not limited to the above-described embodiments but can be varied within the scope of the appended claims. For example, the recessed part 8 can be circular but also oval or with some other geometrical shape.

Although Figs. 3-6 show six protrusions 11 with six end surfaces 13, which would indicate that the invention is suitable for hexagonal screw heads, it can also be utilized in connection with fastening elements with more or fewer sides than six. The number of protrusions 11 can also vary. Preferably, the number of protrusions matches the number of sides of the attachment element which is intended to be locked, but the invention can also be utilized in cases where the number of protrusions is not equal to the number of sides of the attachment element in question.

The invention is particularly well suited for cast, forged and sintered materials, e.g. nodular iron or corresponding iron-based materials. The invention is also suitable for light metals, e.g. aluminum or other metals and metal alloys. In principle, the invention can also be utilized together with non-metal materials, e.g. plastic materials.

The protrusions 11 can be shaped in various manners. However, they must be arranged in connection to the surface intended for the fastening element so that they form a stop element which prevents rotation of the fastening element. Although the figures show an embodiment where the protrusions 11 have been positioned in a recessed part 8, the invention can also be utilized in construction elements without a recess part, i.e. where the protrusions 11 are, for example, arranged on top of the construction element. In this case, the protrusions 11 can be arranged in an arbitrary position on the construction element where there is a need to lock a fastening element.

The invention can also be utilized when locking a fastening element when there is no hole made through the console 7.

Finally, the processing of the end surfaces 13 of the protrusions 11 can be made by means of a milling tool or other kinds of tools.