WO2014195266A1

WO2014195266A1 - Shaft

Info

Publication number: WO2014195266A1
Application number: PCT/EP2014/061377
Authority: WO
Inventors: Florian LUBOS; Andreas KAMPS
Original assignee: Voith Patent Gmbh
Priority date: 2013-06-05
Filing date: 2014-06-02
Publication date: 2014-12-11
Also published as: DE102013009376A1

Abstract

The invention relates to a shaft (1) having • - at least two shaft sections (2, 3) with different diameters (d1, d2); • - a transition contour (4) between the shaft section (2) with the larger diameter (d1) and the shaft section (3) with the smaller diameter (d2), wherein • - the transition contour (4) is in the form of a Bezier curve (B), and wherein • - the Bezier curve transitions in a tangentially constant manner into the contour (6) of the shaft section with the smaller diameter. The invention is characterized in that • - the Bezier curve transitions in a tangentially constant manner into an auxiliary tangent (t _h) which touches a point of intersection between the Bezier curve and a contour (5) of the shaft section with the larger diameter, wherein • - the auxiliary tangent runs at an angle (φ) of 15 - 60° to the radial direction (R).

Description

wave

The invention relates to a shaft with at least two shaft sections of different diameter according to the closer defined in the preamble of claim 1. The invention also relates to the use of such a shaft.

Shafts with at least two shaft sections with different

Diameters are well known in the art. It is a so-called wave shoulder or a wave with a wave heel. For example, such a shaft can be used to receive a wheel, for example the wheel hub of a rail wheel for a rail vehicle. Typically, the shaft portion is formed with the larger diameter than wheel seat and receives the rail wheel, for example via a press fit and / or a composite with a feather key or the like. The shaft portion with the smaller diameter is referred to in this case as a shaft shaft and can be accommodated for example in a storage. The transition between the shaft portion of larger diameter and the shaft portion of smaller diameter is mechanically highly loaded, especially in the above-mentioned use for receiving a wheel. For this case, a structure is known for the transition between the press fit and the shaft shank according to DIN EN 13103/13104, which consists of composite radii. By the jump in the radii or their

Curvatures occur, however, elevated voltages, so that a high

Material loading occurs, which must be counteracted accordingly by the use of more material or more expensive material with improved strength properties. Also an appropriate treatment of

Material, such as a surface treatment in chemical or mechanical type, can help to increase the strength. All this is correspondingly complicated and expensive.

Furthermore, it is known from the general state of the art that with shaft shoulders the transition contour can be achieved by smoothed train triangles, which are smoothed for example via Bezier curves, an improvement in the stress distribution of the rotationally symmetrical shaft shoulder under axial load. In this context, reference is made as state of the art to section 4.2 of the final report on the BMBF-funded joint project: Development of Efficient, Easy-to-Use Design Principles for Technical Components Following the Model of Nature (Grant No. 01 RI 0638) from October 2010. Therein a corresponding transition for a wave shoulder is described, which shows a clear improvement in terms of the stress concentrations in the region of the smaller diameter.

The object of the present invention is now to provide a shaft according to the preamble of claim 1, which based on these

Considerations a further improvement in terms of mechanical

Resilience of the shaft achieved.

According to the invention this object is achieved by a shaft having the features in the characterizing part of claim 1. Advantageous embodiments and further developments emerge from the subclaims dependent thereon. In claim 9, a particularly preferred use is also indicated. An advantageous development thereof can be found in the dependent subclaim.

The inventors have shown in the further investigation of the results of the aforementioned final report that a particularly high strength in a wave with at least two shaft sections with different diameters can be achieved in particular when the Bezier curve tangent-continuous in an auxiliary tangent passes, which rests at the intersection between the Bezier curve and a contour of the shaft section with the larger diameter. The auxiliary tangent runs at an angle of 15-60 ° to the radial direction. Not as you would expect in a tangentenstetigen transition of

Bezier curve in the radially extending portion or possibly even in parallel to the contour of the shaft portion of smaller diameter extending contour of the shaft portion of larger diameter results in the optimum strength, but especially when the transition of the Bezier curve in the contour of the shaft portion with larger Diameter discontinuous. This is achieved by assuming an auxiliary virtual tangent which abuts the point of intersection between the contour and the Bezier curve and which runs in the said angle of 15-60 ° with respect to the radial direction, ie in the typical view with respect to the vertical. This structure allows a very high strength of the shaft with the at least two

Shaft sections.

The use of the Bezier curve per se allows a very simple and efficient construction, since these are calculated comparatively easily and according to the type of Bezier curve with two main points and a few control points

Accordingly, it can be easily programmed for production.

In a very advantageous development thereof, it may be provided that the auxiliary tangent extends at an angle of 30-45 ° to the radial direction. From the angular range given above, angles between 30 and 45 ° have proved to be particularly advantageous. As a result, the strength of the shaft can be increased again.

In a further very favorable embodiment of the shaft according to the invention, it can now also be provided that the Bezier curve is designed as a second or third-order Bezier curve. Such a square or cubic Bezier curve has the advantage that it only needs three or four points (main and control points) and therefore is particularly simple and efficient in the calculation. By a higher degree of the Bezier curve, the results in terms of mechanical strength are not or only

insignificantly improved, so that a quadratic or cubic Bezier curve with the corresponding reduced calculation effort for the wheel disc according to the invention is of particular advantage.

In an advantageous development of the shaft according to the invention, it can also be provided that the Bezier curve has two main points and one or two control points, wherein the main points lie in the area in which the Bezier curve tangent in the contour of the shaft portion with the smaller diameter and the auxiliary tangent and wherein the control points lie on the auxiliary tangent on the one hand and a tangent in the tangent-continuous transition to the smaller diameter shaft portion on the other hand. Such a cubic Bezier curve is comparatively simple and efficient in its calculation, because the control points on the respective tangents, ie the auxiliary tangent and the tangent on the contour of the shaft section with the smaller diameter, are simple and simple

can be moved until an optimal shape is found.

In a further very favorable embodiment of this it can now further be provided that the two control points on the auxiliary tangent and the tangent at the transition between the Bezier curve and the shaft portion with the smaller diameter at an intersection of the tangents to a

Control point coincide. Such a constructive structure, which ultimately reduces the Bezier curve to a quadratic Bezier curve, is particularly simple and efficient, since the auxiliary tangent is required anyway and a tangent to the contour of the shaft section with the smaller diameter, especially if this is defined by a straight line, very easily can be determined. Thus, the arrangement of then only one control point in the

Intersection of the tangents is a particularly simple and efficient structure, which allows the calculation of an optimized Bezier curve very easily and quickly.

In a further very favorable embodiment of the shaft according to the invention, it can now also be provided that the shaft section with the smaller diameter runs conically with a pitch of less than 1:20, in particular less than 1: 100. Such a conical course of the shaft section with a smaller diameter is possible in principle, so that the tangent at the point in which the Bezier curve merges into this shaft section, not in the axial direction, but at a certain angle to the axial direction. The slopes are rather small, for example in the order of 1: 300 to 1: 500.

A further advantageous embodiment of the shaft according to the invention provides in this case that the shaft portion is formed with the larger diameter with a constant diameter. The shaft section with the larger diameter may in particular be a wheel seat on which, for example, a rail wheel is pressed. Accordingly, it is designed according to an advantageous development of this idea as a press fit. It will then typically be of constant diameter, possibly with a small chamfer at its beginning, to facilitate press-fitting of the rail wheel. As already mentioned, the particularly preferred use of the shaft in one of the described embodiments is its use as an axle, wherein on the

Shaft section with the larger diameter of a wheel, in particular a rail wheel, is arranged. Such a rail wheel, which according to an advantageous embodiment of this use can be pressed onto the shaft section with the larger diameter, typically causes a high load in the shaft, in particular in the shaft shoulder, so the area between the shaft portion with the larger diameter and the

Shaft section with the smaller diameter, which is also referred to as shaft shaft. Characterized in that the shaft according to the invention by the

Optimization with the Bezier curve and the auxiliary tangent with minimal

Material use ensures the maximum strength of the structure, it is ideal for the highly stressed use as an axle for wheels, especially rail wheels. Further advantageous embodiments of the shaft according to the invention will become apparent from the remaining dependent claims and are based on the

Embodiment clear, which is described below with reference to the figure. The single attached figure shows a section of a shaft according to the invention.

In the single attached figure, a section of a shaft 1 in a possible embodiment according to the invention can be seen. The representation in the figure raises no claim to scale and mathematically correct representation of the curves, but should only help explain the structure underlying the underlying principle.

The illustrated section of the shaft 1 comprises a first shaft section 2 with a larger diameter di and a second shaft section 3 with a smaller one

Diameter d ₂ . According to the preferred use of the shaft 1 as an axle for receiving a wheel, in particular a rail wheel, the shaft portion 2 with the larger diameter di hereinafter referred to as wheel seat or press fit. The shaft section 3 with the lower

Diameter di is accordingly hereinafter referred to as shaft shaft. The axis of rotation of the shaft 1 is indicated by the axis A. This simultaneously specifies the axial direction in the sense of the present description. Perpendicular to this axial direction A is a radial direction R drawn, for example in the area in which the larger diameter di of the wheel seat 2 merges into a transition contour 4. This transition contour 4 is formed as Bezier curve B.

Basically and independently of a specific embodiment shown in Figure 4, the Bezier curve B can be as follows by means of

Amber polynomial mathematically represent:

Where P _; the direction vectors to the interpolation points (H

Control Points)

For example, for cubic Bezier curves

Χ (ί) = (-Ρ ₀ + 3 · Ρ ₁ -3 · Ρ ₂ + Ρ ₃ ) · ί ³ + (3 · Ρ ₀ -6 · Ρ ₁ + 3 · Ρ ₂ ) · ί ² + (-3 · Ρ ₀ + 3 · Ρ ^

With the introduction of vectorial factors: Thus the parameter form of the Bezier curve B results:

X (t) = D - t ³ + C - t ² + B - t + A If all the points x are calculated for te [0; l], the Bezier curve B results between P ₀ and P ₃ with the control points P _t and P ₂ ,

The wheel seat 2 is completed in the radial direction by a straight line 5, which over the approximately largest axial length of the wheel seat 2 the same

Diameter di has. Only in the transition to the transition contour 4, a chamfer can be provided so that, for example, a rail wheel can be easily pressed onto the wheel seat 2. In the area of the shaft shaft 3 whose contour is also determined by a designated 6 straight. This runs in the embodiment shown here parallel to the axis of rotation A, the shaft shaft 3 thus has a constant diameter d ₂ . Here it would also be conceivable, the contour completely or partially with a slope, typically in the

Magnitude of 1: 100 up to 1: 500, form.

Trained as Bezier curve B transition contour 4 has its first

Main point Po now at just this transition of the Bezier curve B in the straight line 6 of the shaft shaft 3. The straight line 6 is also extended tangentially over a tangent ti. At the same time, this tangent ti forms the tangent for the tangent-continuous transition of the Bezier curve B into the straight line 6 in the main point P ₀ . The second principal point P3 of the Bezier curve B now lies in the region in which the Bezier curve B merges into the straight line 5 of the wheel seat 2, or in which it merges into a chamfer of this wheel seat 2. The transition from the Bezier curve B in the straight line 5 is discontinuous, in such a way that a tangentenstetiger

Transition of the Bezier curve B is guaranteed in an auxiliary pole tH. This auxiliary tangent tH, shown in dotted lines in the figure, runs at an angle φ to the radial direction R, which lies between 15 ° and 60 °, preferably between 30 ° and 45 °. This angle φ can in the construction of the shaft. 1 preferably in the angular range between 30 ° and 45 ° relative to the radial

Direction R are selected. By this construction with a tangentenstetigen transition of Bezier curve B in the Hilfstangente tH can be achieved in terms of strength very good construction of the transition contour 4.

To form the Bezier curve B, two further control points can now be used, so that ultimately there is a cubic Bezier curve with the two main points P ₀ , P ₃ and the two control points Pi, P ₂ . Preferably, these control points Pi, P _{2 are} on the tangent ti on the one hand and the auxiliary tangent tH on the other hand. They can be moved according to the design on the tangent ti, or the auxiliary pole tH.

In order to further optimize the calculation effort for the Bezier curve B, it can also be provided in a favorable development that the two

Control points Pi, P ₂ coincide to a single control point, which is then preferably located in an intersection S of the auxiliary tenth and tangency ti. The Bezier Curve B, which is square in this special case, can be calculated particularly simply and efficiently, and accordingly can be easily designed and easily implemented in production, for example by programming corresponding production machines.

All in all, this results in a very simple and efficient construction, which allows a high strength of the shaft in the region of the transition contour 4. The effort in terms of construction and manufacturing is minimal, so that the shaft 1 can be made very simple and efficient.

Overall, the structure allows by harmonizing the

Stress distributions a very high strength with minimal use of materials and without complex procedures such as solidification of the material in the transition area are necessary. Regardless, can the strength can be further increased by such surface strengthening methods. The methods can be formed both mechanically (shot peening, rolling, etc.) and material technology / chemical (case hardening, nitriding, etc.).

Claims

claims

1st wave (1) with

1.1 at least two shaft sections (2, 3) with different

Diameters (di, d ₂ );

1.2 a transition contour (4) between the shaft portion (2) with the

larger diameter (di) and the shaft portion (3) with the smaller diameter (d ₂ ), wherein

1.3, the transition contour (4) is formed as a Bezier curve (B), and wherein

1.4 merges the Bezier curve (B) tangentially into the contour (6) of the shaft section (3) with the smaller diameter (d ₂ ),

characterized in that

1.5, the Bezier curve (B) tangentially merges into an auxiliary tangent (tn) which abuts an intersection between the Bezier curve (B) and a contour (5) of the larger-diameter shaft section (2)

1.6 the auxiliary tangent (tn) at an angle (cp) of 15 - 60 ° to the radial

Direction (R) runs.

2. shaft (1) according to claim 1, characterized in that the auxiliary tangent (th at an angle (cp) of 30 - 45 ° to the radial direction (R).

3. shaft (1) according to claim 1 or 2, characterized in that the

Bezier curve (B) as a Bezier curve (B) second or third degree is formed.

4. wave (1) according to claim 1, 2 or 3, characterized in that the Bezier curve (B) has two main points (Po, P3) and one or two

Has control points (Pi, P ₂ ), wherein the principal points (P ₀ , P ₃ ) lie in the region in which the Bezier curve (B) tangentially into the contour (6) of the shaft section (3) with the smaller diameter (d ₂ ) and into the auxiliary tangent (t _H ), and wherein the control points (Pi, P ₂ ) on the auxiliary tangent (t _H ) on the one hand and a tangent (ti) in the

Tangentenstetigen transition to the contour (6) of the shaft portion (2) with the smaller diameter (d ₂ ) on the other hand lie.

5. shaft (1) according to claim 4, characterized in that the two

Control points (Pi, P ₂ ) on the auxiliary tangent (t _H ) and the tangent (ti) at the transition between the Bezier curve (B) and the contour (6) of the

Shaft section (2) with the smaller diameter (d ₂ ) in one

Intersection (S) of the tangent (ti) and the auxiliary tangent (t _H ) to a control point (Pi = P ₂ ) coincide.

6. shaft (1) according to one of claims 1 to 5, characterized in that the shaft portion (3) with the smaller diameter (d ₂ ) conically with a pitch of less than 1:20, in particular less than 1: 100, runs ,

7. shaft (1) according to one of claims 1 to 6, characterized in that the shaft portion (2) with the larger diameter (di) with

constant diameter (di) is formed.

8. shaft (1) according to one of claims 1 to 7, characterized in that the shaft portion (2) with the larger diameter (di) is formed as a press fit.

9. Use of the shaft (1) according to one of claims 1 to 8 as an axle, wherein on the shaft portion (2) with the larger diameter (di) a wheel, in particular a rail wheel, is arranged. Use according to claim 9, characterized in that the wheel is pressed onto the shaft section (2) with the larger diameter (di).