Screw-nut blank for producing a securing nut, and securing nut

Abstract

The invention relates to a raw bolt nut part for the manufacture of a safety nut (20) and a safety nut (20) having a safety internal thread with a distance from the internal thread hole (9) in the axial direction (A) and having a safety internal thread that is offset from the internal thread hole (9) to an internal thread of the nut body (1) having a concentric advancing internal front surface (11) with an internal thread hole (9) of the nut body (1) having a formed collar (8) formed in one piece with the nut body (1) on one front surface (3) of the bolt nut, where the raw bolt nut part (10) has an axially advancing ring collar (2) used for forming the formed collar (8) by forming, where the ring collar (2) has a contour that remains the same in the circumferential direction and a cross-sectional form that increases with increasing distance from the front surface (3) in the axial direction (A), in particular a conical cross-sectional form,Here, the ratio of the thickness of the ring collar (2) of the (6) in the transition section (3) to the inner facade surface (S1) to the thickness of the ring collar (2) of the free end (7) used to form the inner facade surface (11) is between 0.45 and 0.75, preferably between 0.5 and 0.7.

Description

Screw nut blank for the manufacture of a lock nut

[0001] The present invention relates to screw nut blanks for the manufacture of locking nuts.

[0002] A wide variety of locknuts and their precursors in the form of screw nut blanks are already known from the prior art. Likewise, various methods for manufacturing the screw nut blanks and for further processing them into locknuts are already known.

[0003] One approach involves manufacturing the lock nut in multiple parts from different components or parts. This approach has the disadvantage of requiring a complex and therefore costly manufacturing process. Furthermore, the connection between the components or parts represents a potential weak point or fatigue point for the lock nut.

[0004] Furthermore, various approaches for manufacturing a one-piece lock nut, preferably from a one-piece screw nut blank, already exist in the prior art. For example, cold forming processes such as cold extrusion are used to produce the blanks or locking screws, preferably from a cylindrical metal starting material or cylindrical starting bodies, in a multi-stage forming process.

[0005] Several of these prior art solutions originate from the applicant. The applicant's WO 2010 / 034324 A1 provides a good overview of the prior art and, in particular, of the various known methods and resulting locknuts that are manufactured from a single blank and form a one-piece or single-unit locknut.

[0006] In these generic solutions, the approach was generally taken that in one stage of the screw nut blank, a ring collar was formed on an axial end face, which runs in the axial direction or projects axially from the end face, wherein in a later process stage the said ring collar was formed to form a shaped collar, in particular axially, so that a clamping or clamping effect can be exerted on a screw between an internal threaded bore of the nut body and an inner end face of the shaped collar arranged concentrically at a distance from this internal threaded bore, which then leads to securing the screw or to the self-locking of the screw or a screw bolt.

[0007] For this purpose, a thread is formed or created in the collar, which is axially spaced from the internal threaded bore by a slot or recess, particularly on the inner end face of the collar. This thread has a certain offset from the internal thread of the nut body's internal threaded bore. When the screw is screwed into the internal threaded bore and the internal thread of the collar's inner end face, the offset of the threads, combined with the axially resilient or elastically deformable properties of the collar, creates a spring or clamping effect on the screw, thus securing it.

[0008] Consequently, it is necessary, on the one hand, that the forming collar, and in particular its inner end face, has sufficient axial width or height to allow for the formation of a sufficiently long internal thread or locking thread. However, to facilitate the transformation of the ring collar into the forming collar, it is desirable that the thickness of the ring collar—the end face of which, in an undeformed or axially aligned state, forms the inner end face of the forming collar after axial deformation—is not too great. This ensures that the forming process can be carried out without creating excessive stresses in the material, which could potentially lead to waviness after forming.

[0009] To meet these requirements, in a previously known locking nut and a corresponding manufacturing process, the ring collar is axially formed and simultaneously upset. This allows the ring collar to have a relatively thin wall thickness prior to deformation, enabling the deformation process. At the same time, the inner end face of the formed collar, created during the forming and radial upsetting, has sufficient axial height or width to form or cut the locking thread. However, the radial upsetting of the formed collar is disadvantageous because the upsetting process is not sufficiently controlled, resulting in a relatively imprecise inner surface or end face of the formed collar.

[0010] In a further development of the prior art, various forms of the ring collar were established that allow axial deformation into a shaped collar without requiring radial upsetting. A significant disadvantage of these locking nuts was that the shaped collar had recesses on an axially outer and / or axially inner surface, i.e., on an outer surface facing away from and / or towards the nut body. These recesses were necessary to reshape or redistribute the existing material of the ring collar during the axial deformation, which leads to a reduction in cross-section or diameter, at least in the end regions of the ring collar.

[0011] However, the aforementioned depressions or offset surface sections of the outer and / or inner surface of the molded collar are detrimental to the locking effect of the molded collar, as the corresponding locking thread on the inner face of the molded collar can only be formed incompletely, particularly in sections, and can only be formed with increased effort. Furthermore, the depressions are detrimental to the spring action of the molded collar, which enables the locking effect.

[0012] Furthermore, US Patent 2,289,828 A, which forms the basis for the preamble of claim 1, discloses a self-locking nut and a corresponding nut blank with an axially projecting annular collar, which is formed into a shaped collar by appropriate forming and provided with a locking thread. The annular collar has a widening profile / cross-section.

[0013] US Patent 3,289,724 A already discloses a self-locking nut with a shaped collar made from a ring collar. The shaped collar does not have a cut thread but merely a friction surface that engages with a corresponding thread. Based on this prior art, the object of the present invention is to propose screw nut blanks and locknuts that enable an improved locking effect.

[0014] With regard to the screw nut blank for the manufacture of a locking nut, this problem is solved by the features of claim 1.

[0015] Advantageous embodiments are the subject of the description and the dependent claims.

[0016] In accordance with the invention, the screw nut blank for manufacturing a lock nut, wherein the lock nut has a shaped collar formed integrally with the screw body at an end face of the screw body, the shaped collar having an inner end face extending concentrically to an internal threaded bore of the screw body, the shaped collar being axially spaced from the internal threaded bore and having a locking internal thread offset from an internal thread of the internal threaded bore, the screw nut blank having an axially extending annular collar which serves to form the shaped collar by forming, and wherein the annular collar has a contour that remains constant in the circumferential direction and a cross-sectional shape, in particular a conical cross-sectional shape, that increases with increasing distance from the end face in the axial direction.wherein the ratio of the thickness of the ring collar in the transition section to the end face to the thickness of the ring collar at a free end, which serves to form the inner end face, is between 0.45 and 0.75, preferably between 0.5 and 0.7.

[0017] A screw nut blank with a conical cross-section that widens with increasing distance from the end face of the nut body is already known from the above-mentioned publication as prior art, whereby the shape of the ring collar shown there, in particular in Fig. 16b, and described in the document, did not enable the forming into a shaped collar without the outer surface of the formed shaped collar having depressions or offset surfaces which, as described above, are detrimental to the locking effect of the locking nut.

[0018] However, it has surprisingly turned out that with the inventive design or with the inventive choice of the ratio of the thickness of the otherwise circumferentially uniform or constant ring collar, both radially compression-free forming, in particular axial forming, to a shaped collar is possible and at the same time forming to a shaped collar is possible without the outer surface and / or the inner surface of the shaped collar having to have depressions, offset surfaces or recesses.Rather, the cross-section according to the invention, with the ratio of the ring collar thickness between 0.45 and 0.75, preferably between 0.5 and 0.7 with regard to the ring collar thickness in the transition section to the end face to the ring collar thickness at a free end, enables the resulting outer surface and / or inner surface to form or have a flat contour or surface over the entire circumference, in particular one free of depressions or offsets.

[0019] The locking nut and the screw nut blank according to the invention are preferably a one-piece metal body, which is particularly advantageously treated or manufactured using cold forming processes.

[0020] The invention, through an unforeseen further development of the prior art, makes it possible to form a sufficiently wide or high inner end face of the shaped collar without radial upsetting, and at the same time, the inner end face, through the adjacent flat, in particular recess-free, outer and / or inner surfaces of the shaped collar, enables a simple formation or introduction of the locking internal thread, so that the locking internal thread can be formed easily and, in addition, the shaped collar has an advantageous deformation or spring property which, in conjunction with the offset of the threads between the internal threaded bore and the inner end face, effects the locking action of the locking screw.Likewise, the geometry of the ring collar according to the invention enables a locking nut with particularly good locking properties, since the shaped collar formed from the ring collar can be provided flat or without recesses and thus has an optimized spring or clamping behavior.

[0021] According to a first advantageous embodiment of the screw nut blank, the ratio of the thickness of the annular collar in the transition section to the end face to the thickness of the annular collar at a free end, which serves to form the inner end face, based on the length of the annular collar, between the transition section and the end face is between 0.1 and 0.15 millimeters in length. The length is defined or determined by the free end of the annular collar on the one hand and by the area of ​​minimum thickness of the annular collar on the other. In other words, this means that in the transition section there is a first area in which, based on the cross-sectional shape or the conical cross-section of the annular collar, the thickness of the annular collar decreases in the axial direction.Following this section is a section in which the thickness of the screw nut blank increases gradually or abruptly. The axial position of the smallest thickness of the ring collar before a gradual or abrupt increase in the thickness of the screw nut blank is to be used to define or to determine the length of the ring collar.

[0022] The ratio between the change in the thickness of the conical cross-section of the ring collar to the length of the ring collar, before deformation, in particular axial deformation, particularly advantageously supports the axial deformation of the ring collar, while simultaneously maintaining or forming flat, in particular depression-free, outer surfaces and / or inner surfaces of the formed collar.

[0023] Another particularly advantageous embodiment of the screw nut blank provides that the thickness of the ring collar at the free end is 0.8 to 1.5 times the pitch of a locking thread to be formed on the ring collar formed into a shaped collar.

[0024] This creates a particularly advantageous prerequisite not only for the beneficial design of the forming collar, but also ensures the beneficial effect of a subsequent forming collar for securing or forming a locking thread. This is because the locking effect of the locking thread can only be guaranteed if it can form a sufficient thread section.

[0025] Another particularly preferred embodiment of the screw nut blank provides that the ring collar is arranged radially between two shoulder sections of the nut body's end face that slope downwards on both sides. This means that the ring collar does not transition into or terminate in a flat or horizontal surface of the nut body in the radial direction, particularly radially inwards, but rather that the area of ​​the nut body's end face that is radially inwards with respect to the ring collar also forms a shoulder section sloping downwards inwards.

[0026] It is of course possible for a radially outer shoulder section and a radially inner shoulder section of the frontal surface of the mother body, in relation to the ring collar, to have different inclinations or slopes and / or different lengths. Preferably, the radially inner shoulder section may be less steep but longer than the radially outer shoulder section.

[0027] It can also be advantageously provided that the ring collar has a hollow cylindrical end section adjacent to and / or extending from the free end, which preferably includes an axial extension of up to half of a locking thread to be formed later on the ring collar (2) formed into the shaped collar.

[0028] This advantageously results in improved stability of the ring collar, which in turn ensures that the ring collar does not buckle undesirably when it is transformed into the shaped collar of the locking nut.

[0029] With regard to the locking nut not included in the invention, comprising a shaped collar arranged on an end face of the nut, having an inner end face extending concentrically to an internal threaded bore of the nut body, which is axially spaced from the internal threaded bore and has a locking internal thread offset from an internal thread of the internal threaded bore, and which is preferably manufactured from a nut blank according to the type described above, it may be provided that the shaped collar has an outer surface and / or inner surface that is flat over its entire circumference, in particular free of depressions, at least adjacent to the inner end face.

[0030] As explained above, a flat outer and / or inner surface over the entire circumference of the shaped collar is an essential prerequisite for an effective locking effect of the shaped collar when screwing in a screw or bolt.

[0031] According to a first advantageous embodiment of the lock nut, the inner end face can be formed by a radially compression-free reorientation of the free end of the ring collar, particularly in the end position. This provides the lock nut according to the invention with a shaped collar that has both flat outer and / or inner surfaces over its entire circumference and is also radially compression-free in the area of ​​the inner end face, so that the shaped collar, especially its inner end face, is suitable for forming the internal locking thread. Furthermore, the shaped collar exhibits optimal deformation or spring properties that determine or at least influence the locking effect of the lock nut.

[0032] According to a further particularly preferred embodiment of the lock nut, the space between the shaped collar and the end face can be formed by an internal groove, which is bounded by an inner, radially inward sloping shoulder section of the end face and a lower edge of the shaped collar that is preferably radially flat or horizontal. The design of the internal groove with a flat upper surface, formed by a flat lower edge of the shaped collar, and a radially inward sloping lower surface, formed by the sloping shoulder or shoulder section of the end face, also has surprisingly advantageous effects on the lock nut.

[0033] The present invention and advantageous embodiments are explained below with reference to highly schematic drawings. These show: Fig. 1a, 1b: a screw nut blank according to the invention in a third process stage for the production of a lock nut, Fig. 2a, 2b: a lock nut not encompassed by the invention produced from the screw nut blank according to Fig. 1a, 1b .

[0034] The following terminology refers to a boltless nut blank as long as the annular collar intended for forming the shaped collar is still formed in the axial direction or runs substantially in the axial direction. A locknut is defined as such when the annular collar has been or is being formed into the shaped collar. This classification is, of course, not binding. On the one hand, the actual completion of the locknut may still require the formation of internal threads even after the annular collar has been formed into the shaped collar, so that the finished locknut or the complete machining process for manufacturing a locknut is only completed later. On the other hand, a transition from blank to nut could, in principle, be defined or stipulated at an earlier stage.

[0035] Unless otherwise described, the screw nut blank and the lock nut are one-piece metallic bodies, and the associated process steps preferably involve cold forming processes using appropriate tools and generally known flow forming or cold forming processes.

[0036] In Fig. 1a A cross-section through a blank screw nut is shown. Fig. 1bFigure 1 shows a top view of the screw nut blank. It is already apparent that an axially extending annular collar 2 is integrally formed on an end face 3 of a nut body 1, extending in the axial direction A. The end face 3 of the nut body 1 already has two shoulder sections 4.1, 4.2 adjacent to the annular collar 2, i.e., radially inner and radially outer. The radially inner shoulder or the radially inner shoulder section 4.2 is bounded by an edge 5, which essentially defines the diameter of an internal threaded bore to be formed later in the nut body 1.

[0037] After initial processing and forming steps, which are state-of-the-art and known to the average person skilled in the art, the screw nut blank undergoes cold forming in a forming tool, the result of which is in the Fig. 1a and 1b is shown. The cross-section of the Fig. 1aIt can be seen that the ring collar 2 has a contour that remains constant in the circumferential direction, which in the axial direction has an increasing or widening cross-sectional shape, in particular a conical cross-sectional shape, with increasing distance from the end face 3. The cross-sectional shape according to the invention is designed such that the thickness S1 of the ring collar 2 in the transition section 6 to the end face 3 is between 0.45 and 0.75, preferably between 0.5 and 0.7, and the thickness S2 of the ring collar 2 at a free end 7 of the ring collar 2, which serves to form the inner end face of the shaped collar of the locking nut.

[0038] The outer edge or outer surface 15 of the ring collar 2 extends axially and forms a cylindrical contour. The ring collar 2 is still formed or arranged radially between two shoulder sections 4.1 and 4.2 of the end face 3, which slope outwards and inwards, respectively.

[0039] In the Fig. 1a It is also evident that a solid section still exists in the nut body 1 of the screw nut blank 10, which, among other things, ensures the stability of the screw nut blank 10, but which must be eliminated or removed in a later process step to form the internal thread bore.

[0040] In the Fig. 2a as well as the Fig. 2b A sectional view and a top view of a locking nut 20 according to the invention are shown. In the stage of Fig. 1a, 1bIn the following processing step, the ring collar 2 was formed into a shaped collar 8, this forming being essentially achieved by an axial deformation of the free end 7 of the ring collar 2. Simultaneously, in a common process step, although not at precisely the same time, a hole or punch was made in the nut body 1 to form an internal threaded bore 9. Accordingly, the lock nut 20 has a shaped collar 8 formed integrally on the end face 3 of the nut or nut body 1, with an inner end face 11 extending concentrically to the internal threaded bore 9 of the nut body 1. The inner end face 11 was formed essentially by reorientation and otherwise without upsetting from the free end 7 of the ring collar 2.The inner end face 11 of the shaped collar 8 is spaced axially A away from the internal threaded bore 9. Furthermore, a locking internal thread (not yet shown and possibly not yet formed) can be formed on the inner end face 11, which engages with an internal thread in the internal threaded bore 9, which is located in the... Fig. 2a The offset design is also not yet shown and may not yet be incorporated. The spacing of the inner end face 11 to the upper edge or an upper end of the internal threaded bore 9 is achieved or formed by an internal groove 12, which is bounded by an inner, radially inward sloping shoulder section 4.2 of the end face 3 and a preferably radially flat lower edge or inner surface 13 of the shaped collar 8.

[0041] Like the lock nut 20 of the Fig. 2aThe inner surface 13 adjacent to the inner end face 11, as well as the outer surface 14 adjacent to the inner end face 11, is flat over its entire circumference, in particular free of depressions or offsets, which benefits the deformation or spring effect of the forming collar 8 and thus improves the locking effect of the locking nut.

[0042] A correspondingly flat inner surface 13 and / or outer surface 14 could previously only be achieved in the context of generic cold forming processes of one-piece screw nut blanks 10 or locking nuts if, in the process step, in addition to the axial forming of the forming collar 8 to the ring collar 2, a radially acting upsetting of the free end 7 or the inner end face was also effected. Reference symbol list

[0043] 1 Nut body 2 Ring collar 2.1 Inner surface of the ring collar 3 End face 4.1 Shoulder section 4.2 Shoulder section 5 Edge 6 Transition section 7 Free end of the ring collar 8 Form collar 9 Internal threaded hole 10 Screw nut blank 11 Inner end face 12 Internal groove 13 Inner surface 14 Outer surface of the form collar 15 Outer surface of the ring collar 20 Lock nut Aaxial direction L 1 Length S1, S2 Strength

Claims

1. A screw-nut blank for producing a securing nut (20), the securing nut (20) having a shaped collar (8) formed in one piece with the nut body (1) on an end surface (3) of the screw nut, the shaped collar (8) having an inner end surface (11) concentric with an internally threaded hole (9) of the nut body (1), the shaped collar (8) having a distance from the internally threaded hole (9) in the axial direction (A) and having a securing female thread (22) offset from a female thread (23) of the internally threaded hole (9), the screw-nut blank (10) having an axially extending ring collar (2) serving to form the shaped collar (8) by reshaping, and the ring collar (2) having a constant contour in the circumferential direction and a cross-sectional shape, in particular a conical cross-sectional shape, which increases in the axial direction (A) as the distance from the end surface (3) increases, characterized in that the ratio of a thickness (S1) of the ring collar (2) in the area of transition (6) toward the end surface (3) to a thickness (S2) of the ring collar (2) at a free end (7) serving to form the inner end surface (11) is between 0.45 and 0.75, preferably between 0.5 and 0.7.

2. The screw-nut blank according to claim 1, characterized in that the ratio of the thickness (S1, S2) of the ring collar (2) in the area of transition (6) toward the end surface (3) to a thickness (S1, S2) of the ring collar (2) at a free end (7) serving to form the inner end surface (11) is between 0.1 per millimeter in length to 0.15 per millimeter in length with respect to the length (L1) of the ring collar (2) between the area of transition (6) and the end surface (3).

3. The screw-nut blank according to claim 1 or 2, characterized in that the thickness (S1, S2) of the ring collar (2) at the free end (7) is 0.8 to 1.5 times the pitch of a securing female thread (22) to be formed on the ring collar (2) reshaped into the shaped collar (8).

4. The screw-nut blank according to any one of claims 1 to 3, characterized in that in the radial direction, the ring collar (2) is disposed between two shoulder portions (4.1, 4.2) of the end surface (3) which slope to both sides.