Design method of crown curve of tapered roller

Abstract

The present invention discloses a method for designing a tapered roller convexity curve, comprising the following steps: S1, establishing a roller convexity design formula based on a traditional formula as follows: Hc(y)=Zm*f(x), wherein Zm is the convexity value of the roller profile edge, and f(x) is a dimensionless convexity profile curve; S2, calculating the convexity value of the roller profile edge according to the formula Zm=a(Dwe+Lwe)+b, wherein: a=0.3055*3.0175 d Linear regression parameter, b=(2.3303*d) 0.2346 / d ; Where d is the rated dynamic load Cr of the bearing with a certain ratio, Dwe is the large end diameter of the tapered roller, and Lwe is the length of the tapered roller; S3, calculate the f(x) convexity profile curve according to the formula 1 / (-3.47353708848685+4.48386445486252*x^-2.07007866882978), where: where x is the ratio of the distance from a point on the roller contour line to the midpoint of the roller to the effective length of the roller. The calculation method is simple, efficient and convenient, involves few parameters, and has good reliability.

Description

Technical Field

[0001] The invention relates to a method for designing a tapered roller convexity curve. Background Art

[0002] In roller bearing applications, in order to avoid stress concentration problems at both ends of the roller caused by edge effects, which greatly reduces the fatigue life of the bearings, the roller surface is usually designed to be convex in subsequent designs to overcome this problem. The basic method of traditional roller bearing logarithmic convexity design includes the calculation of the maximum load of the rolling element, the calculation of the contact stress, and the logarithmic convexity design calculation. The maximum load calculation method requires looking up the table to calculate the radial load and the combined load separately; the contact stress is calculated according to the Hertz contact theory, and the calculation methods for rollers, cylindrical rollers, and tapered roller bearings are different, and correction factors such as materials are also involved. It can be seen that this design method involves many parameters, the calculation process is cumbersome, and it is easy to make mistakes in the calculation, which affects the reliability of the design scheme. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a method for designing a tapered roller convexity curve, which has a simple calculation method, is efficient and convenient, involves few parameters, and has good reliability in use.

[0004] To achieve the above object, the present invention provides a method for designing a tapered roller crown curve.

[0005] S1. The roller crown design formula is established based on the traditional formula as follows: Hc(y)=Zm*f(x), where Zm is the crown value of the roller profile edge, and f(x) is the dimensionless crown profile curve;

[0006] S2. Calculate the convexity value of the roller profile edge according to the formula Zm=a(Dwe+Lwe)+b, where: a=0.3055*3.0175 d is the linear regression parameter, b=(2.3303*d) 0.2346 / d ; Where d is the rated dynamic load of the bearing of a certain ratio, Dwe is the large end diameter of the tapered roller, and Lwe is the length of the tapered roller;

[0007] S3, according to the formula 1 / (-3.47353708848685 +4.48386445486252*x -2.07007866882978 ) calculates the convexity profile curve f(x), where: x is the ratio of the distance from a point on the roller contour line to the midpoint of the roller to the effective length of the roller.

[0008] As a further configuration of the present invention, wherein d is 0.2-0.5Cr, and Cr is the rated dynamic load of the bearing.

[0009] As a further configuration of the present invention, 0.15Lwe≤x≤0.5Lwe.

[0010] The beneficial effect of such a setting is that, in such a setting, only a certain rated dynamic load ratio d, roller diameter Dwe, and roller length Lwe need to be known, the number of known parameters required for measurement and activity is small, and the calculation steps and calculation formulas are greatly simplified compared with the traditional method, so the present invention avoids tedious calculations. Moreover, the function of the crown shape designed by the crown optimization design method of the present invention is not inferior to that of the traditional method. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The roller profile is calculated by substituting 0.3Cr into the Lundberg formula;

[0012] Figure 2 The roller profile shape diagram obtained by substituting 0.3Cr into the calculation in the embodiment of the present invention;

[0013] Figure 3 The contact stress record diagram of the roller profile calculated by Lundberg formula is simulated and calculated in commercial software;

[0014] Figure 4 The contact stress record diagram of the roller profile calculated by the formula of the embodiment of the present invention is simulated and calculated in commercial software. DETAILED DESCRIPTION

[0015] The present invention provides a roller crown optimization design method, which establishes a roller crown design formula based on a traditional formula as follows: Hc(y)=Zm*f(x).

[0016] In the above formula, Zm is the convexity value of the roller profile edge, which is calculated according to formula (1-1):

[0017] Zm=a(Dwe+Lwe)+b (1-1)

[0018] Where Dwe is the roller diameter and Lwe is the roller length;

[0019] In formula (1-1):

[0020] a=0.3055*3.0175 d (1-2)

[0021] b=(2.3303*d) 0.2346 / d (1-3)

[0022] Where d is the ratio of the design load to the rated dynamic load (Cr), which is usually 0.2Cr~0.5Cr;

[0023] In the above formula, f(x) is the dimensionless convexity profile curve, which is calculated by formula (2-1):

[0024] f(x)=1 / (-3.47353708848685+4.48386445486252*x -2.07007866882978 ) (2-1)

[0025] In formula (2-1), x is the ratio of the distance from a point on the roller contour line to the midpoint of the roller to the effective length of the roller, and is generally taken as [0.15lwe, 0.5lwe]. This value takes into account the roller load condition and the fact that at least 0.3Lwe in the middle of the roller is a straight generatrix in actual processing, so that it can be more effectively packaged and the convexity of the roller obtained is sufficient to overcome the edge effect.

[0026] Bring in data for actual comparison, such as Figures 1 to 4 As shown, a tapered roller bearing 30205: the rated dynamic load Cr is 30.8kN, the roller diameter Dwe is 6.41mm, the roller length Lwe is 12mm, and the chamfer of the roller is 0.34mm.

[0027] Using the above data, the roller profile shape calculated by substituting 0.3Cr into the above formula is as follows: Figure 1 and Figure 2 As shown, the contact stress of the roller profile is simulated and calculated in the commercial software as follows: Figure 3 and Figure 4 shown.

[0028] By comparison, it is found that the roller profile shape provided by this design method and the profile curve obtained by using the Lundberg formula have different performances in the straight segment and the arc segments on both sides of the edge. Under the load of 0.3Cr, the contact stress calculated by the formula of the present invention is more gentle, and the load distribution is evenly distributed along the middle length of the roller. In terms of the overall trend, the contact stress of this method is also more gentle than the profile curve obtained by using the Lundberg formula. From the perspective of contact stress comparison analysis, the formula profile curve of this design method is more effective.

[0029] The above example is only one preferred specific example of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included in the protection scope of the present invention.

Claims

1. A method for designing a tapered roller crown curve, characterized in that: S1. The roller crown design formula is established based on the traditional formula as follows: Hc(y)=Zm*f(x), where Zm is the crown value of the roller profile edge, and f(x) is the dimensionless crown profile curve; S2. Calculate the convexity value of the roller profile edge according to the formula Zm=a(Dwe+Lwe)+b, where: a=0.3055*3.0175 d is the linear regression parameter, b=(2.3303*d) 0.2346 / d ; Where d is the rated dynamic load Cr of the bearing with a certain ratio, Dwe is the large end diameter of the tapered roller, and Lwe is the length of the tapered roller; S3, according to the formula 1 / (-3.47353708848685 +4.48386445486252*x -2.07007866882978 ) calculates the convexity profile curve f(x), where: x is the ratio of the distance from a point on the roller contour line to the midpoint of the roller to the effective length of the roller.

2. The method for designing a tapered roller crown curve according to claim 1, characterized in that: Wherein d is 0.2~0.5Cr, and Cr is the rated dynamic load of the bearing.

3. The method for designing a tapered roller crown curve according to claim 1, characterized in that: 0.15Lwe≤x≤0.5Lwe.

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