Corrosion-resistant threaded stop disc

Abstract

The invention relates to a corrosion-resistant screw stop disc, having an annular stainless steel disc body for arrangement between a screw head and a flat base (5), the disc body having a disc upper side (6) and a disc lower side (1). The surfaces of the disc upper side (6) and the disc lower side (1) of the disc body are compressed by a stamping process, wherein the disc body has a material thickness of at least 1.5 mm and is configured convex.

Description

TECHNICAL FIELD

[0001] The present application relates to a corrosion-resistant screw securing disc having an annular stainless steel disc body for arrangement between a screw head and a flat base. BACKGROUND

[0002] The screw securing disc has the purpose of counteracting a loosening process in a threaded connection. Such a loosening process occurs in mutually screwed components as a result of a loss of pretension in the threaded connection, as a result of a settling process and / or a creep process.

[0003] In order to counteract such a loosening process, the screw securing disc has an elastic effect, the spring force of which should be dimensioned such that it can compensate the loss of pretension caused by the settling process and / or the creep process to such an extent that the clamping force required for the operational reliability of the threaded connection is maintained.

[0004] In the case of high requirements for corrosion protection, in particular also in the food sector, threaded connections are used which are made of stainless steel. The screw securing element is also made of stainless steel in the case of threaded connections with stainless steel screws. In addition to the good corrosion protection properties of stainless steel, contact corrosion is also avoided by the same potential of the screw securing element.

[0005] In principle, stainless steel has only a very low elastic effect. In the case of special stainless steel alloys, an increased elastic effect can be achieved by means of a heat treatment process. On the one hand, these special stainless steel alloys and also the heat treatment process are very expensive, on the other hand, the corrosion properties are negatively influenced by the heat treatment process. Last but not least, the spring properties ultimately achievable are often not sufficient to meet the requirements set. In this context, heat-treated stainless steel materials are only rarely used in practice for screw securing elements.

[0006] Stainless steel according to material number 1.4301 or 1.4401 according to DIN EN 10027-2:2015-07 (X5CrNi18-10 or X5CrNiMo17-12-2) is often used as an elastic stainless steel with good or very good corrosion properties. In this stainless steel, hardening of the surface is caused by cold work hardening when rolling. This hardening leads to a limited elastic effect at a sheet thickness of up to 1 mm, wherein the elastic effect increases with decreasing sheet thickness. This material is remarkable in that it has only a very limited elastic effect in the case of greater thickness when cold work hardened, which is not sufficient for the matching compensation in threaded connections. After cold work hardening, the material can only be further processed or formed in a limited range. SUMMARY

[0007] This is the starting point of the present application. The object of the present application is to provide a corrosion-resistant screw stop disc with a stainless steel disc body, which can be used even in cases of high requirements for corrosion protection, for example in the food sector, which has a high elastic effect and can be produced cost-effectively. According to the present application, this object is achieved by a screw stop disc having the features of the characterizing part of patent claim 1.

[0008] A corrosion-resistant screw stop disc with a stainless steel disc body is provided by the present application, which can be used even in cases of high requirements for corrosion protection, for example in the food sector, which has a high elastic effect and can be produced cost-effectively. Due to the surface compression of the disc upper side and the disc lower side of the disc body, wherein the disc body has a material thickness of at least 1.5 mm, and wherein the disc body is configured convex, a high elastic effect is achieved to compensate for the Setzwirkung in order to achieve a pretension of the screw connection. The material thickness, which is dimensioned sufficiently large, in combination with the hardening of the edge layer in the shaped state and the surface stresses occurring upon tensioning, leads to the desired elastic effect. It has surprisingly been found here that the elastic effect increases with increasing material thickness. The screw stop disc is preferably configured in one piece. The disc body preferably has a material thickness of at least 2 mm, particularly preferably at least 2.5 mm, in particular at least 3.0 mm.

[0009] In an improvement of the present application, at least one of the surfaces of the upper side and the lower side of the disc body is provided with knurling. Here, a line profile is stamped into the surface, whereby a point-like additional compression of the surface is achieved. Thereby, the surface stresses of the screw stop disc and thus the occurring elastic effect are adjustable. Preferably, both surfaces of the upper side and the lower side of the disc body of the screw stop disc are provided with knurling. Here, both surfaces can be provided with knurling which differs from one another in terms of knurling depth and / or knurling pattern, whereby the elastic effect can be maximized.

[0010] In a design of the present application, the stainless steel disc body is made of stainless steel of material number 1.4401 or 1.4301 according to DIN EN 10027-2:2015-7. Here, they are cost-effective materials with excellent corrosion properties. By using such a market- common and formable raw material, it is easily possible to stamp knurling and to achieve a good hardening of the surface of the screw stop disc. The hardening of the soft raw material is combined in this process with the shaping by surface compression and the point-like additional compression in the form of knurling on one or both sides of the screw stop disc by the stamping process.

[0011] In a further design of the application, at the underside of the thread stop disc facing the base, the outer and inner annular segment faces are arranged angularly to each other, wherein the outer edge of the outer annular segment face rests on the base in the untensioned state of the disc, and wherein the two annular segment faces each sandwich an acute angle with the base, and wherein the angle a formed between the outer annular segment face and the base is greater than the angle β formed between the inner annular segment face and the base. Thereby, the force is set to act at a steeper angle on the flat base, i.e. the force component in the vertical direction is higher than the force component in the horizontal direction. Thereby, the outer edge of the face of the outer ring segment is pressed more forcefully into the flat base when the thread is tightened, so that an improved stop effect is achieved. Furthermore, the outer diameter of the disc can be kept relatively small with a higher stop effect.

[0012] In a refinement of the application, the acute angle between the outer annular segment face and the base is between 10° and 20°, preferably between 12° and 15°, in the untensioned state. These values provide good elastic properties and stop properties of the disc. Preferably, the acute angle between the inner annular segment face and the base is between 3° and 15°, preferably between 5° and 10°, in the untensioned state.

[0013] Advantageously, the angle γ between the two annular segment faces facing the flat base is obtuse. Preferably, the acute angle β between the inner annular segment face and the flat base is about half as large as the acute angle a between the outer annular segment face and the flat base, in the untensioned state. BRIEF DESCRIPTION OF DRAWINGS

[0014] In a further design of the application, the surfaces of the at least one bearing face, preferably of the two abutment faces, are implemented polished. Thereby, the overall very good corrosion resistance of the stainless steel material of the thread stop disc is additionally increased. Further refinements and designs of the application are specified in the remaining dependent claims. One embodiment of the application is shown in the drawings and will be described in detail below. Therein:

[0015] Figure 1 a schematic view of a stainless steel thread stop disc is shown;

[0016] Figure 2 a schematic half-section view of a thread stop disc in Figure 1 is shown; and

[0017] Figure 3 a schematic view of a stainless steel threaded connection with a stop disc according to Figure 1 is shown, wherein the left side of the figure shows the stop disc in the untensioned state, while the right side of the figure shows the stop disc in the clamped state. DETAILED DESCRIPTION

[0018] The thread stop disc chosen as an example is made of V4A stainless steel of material number 1.4401 (X5CrNiMo 17-12-2) and comprises a convex disc body in the form of a ring with a material thickness of 2.5 mm. The thread stop disc has a disc upper side 6 and a disc lower side 1, the surfaces of which are compressed by means of a stamping process, respectively.

[0019] The disc lower side 1 is configured convexly and is divided into two annular segment faces 2, 3 (outer annular segment face 2 and inner annular segment face 3), which are positioned angularly to one another.

[0020] The stop disc is designed such that it rests with its outer edge 4 of the outer annular segment face 2 on a flat base 5 in the untensioned state. Here, the outer annular segment face 2 is clamped at an angle a with the flat base 5 in the untensioned state and the inner annular segment face 3 is clamped at an angle β with the flat base 5 (see Figure 3 ). The angles a, β are implemented here as acute angles, wherein the angle β always has a value less than the angle a. In this example, the angle a is 14° and the angle β is 6°.

[0021] The thread stop disc is configured arched on its upper side 6 facing away from the base 5. In the context of the stamping process, knurls 7 are introduced into the surface of the upper side 6 in a ring shape, whereby an additional hardening is achieved. In this example, the knurls 7 are implemented by means of an arrangement of line segments (Linienzug) (see Figure 1 ). Depending on the desired surface portion hardening, other knurl patterns can also be introduced. In this example, both the upper side 6 and the lower side 1 are provided with knurls 7. In order to improve the corrosion resistance, the surfaces of the upper side 6 and the lower side 1 are polished.

Claims

1. A corrosion-resistant screw stop disc having a ring-shaped stainless steel disc body for arrangement between a screw head and a flat base (5), the disc body having a disc upper side (6) and a disc lower side (1) facing the base, characterized in that The surfaces of the upper disc side (6) and the lower disc side (1) of the disc body are compressed by a stamping process, wherein the disc body has a material thickness of at least 1.5 mm and is configured convex, wherein the two surfaces of the upper disc side (6) and the lower disc side (1) of the disc body are provided with knurlings (7) which differ from each other in terms of knurling depth and / or knurling pattern.

2. The thread stop disc of claim 1, wherein The disc body has a material thickness of at least 2.0 mm.

3. Thread stop disc according to any of the preceding claims, characterized in that The stainless steel disc body is made of stainless steel of material number 1.4401 or 1.4301 according to DIN EN 10027-2:2015-7.

4. A thread stop disc according to claim 1 or 2, characterised in that At the lower disc side (1) of the screw stop disc facing the base (5), the outer annular segment face (2) and the inner annular segment face (3) are arranged angularly to each other, wherein the outer edge of the outer annular segment face (2) rests on the base (5) in an untensioned state of the screw stop disc, and wherein the outer annular segment face (2) and the inner annular segment face (3) respectively enclose an acute angle with the base (5).

5. A thread stop disc according to claim 1 or 2, characterised in that At least one of the two surfaces of the upper disc side (6) and the lower disc side (1) of the disc body is polished.

6. The thread stop disc of claim 4, wherein, The acute angle a between the outer annular segment face (2) and the base (5) is between 10° and 20° in the untensioned state, wherein the acute angle b between the inner annular segment face (3) and the base (5) is between 3° and 15° in the untensioned state.

7. The thread stop disc of claim 4, wherein, The angle y between the outer annular segment face (2) and the inner annular segment face (3) facing the flat base (5) is an obtuse angle.

8. The threaded member stop disk of claim 4, wherein, In the untensioned state, the acute angle b between the inner annular segment face (3) and the flat base (5) is about half as large as the acute angle a between the outer annular segment face (2) and the flat base (5).

9. The thread stop disc of claim 1, wherein, The disc body has a material thickness of at least 2.5 mm.

10. The threaded member stop disk of claim 4, wherein, The angle a formed by the outer annular segment face (2) and the base (5) is greater than the angle b formed between the inner annular segment face (3) and the base (5).

11. The thread stop disc of claim 4, wherein, The acute angle a between the outer annular segment face (2) and the base (5) is between 12° and 15° in the untensioned state, wherein the acute angle b between the inner annular segment face (3) and the base (5) is between 5° and 10° in the untensioned state.

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