A method for calculating compression rate of shaft sealing ring

Abstract

The present application belongs to the technical field of shaft seal, and particularly relates to a kind of shaft groove sealing ring compression rate calculation method.The shaft groove sealing ring compression rate calculation method of the present application obtains assembly eccentricity and machining eccentricity, calculates the depth parameter of the radial groove formed after assembly, adds the assembly eccentricity and the machining eccentricity to the depth parameter of the radial groove when calculating the sealing ring compression rate, obtains the actual depth of the radial groove, and calculates the sealing ring compression rate using the actual depth of the radial groove and the radial dimension of the sealing ring cross section.The method proposed by the present application can better reflect the limit condition of assembly, the calculated minimum compression rate is more accurate, can provide important reference for the design of sealing structure, and reduce the oil leakage rate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of shaft seal, and particularly relates to a method for calculating compression rate of a shaft seal ring. BACKGROUND

[0002] The seal ring is a commonly used sealing device and is widely used in various sealing occasions. However, in order to ensure the sealing effect, the performance of the seal ring needs to be researched, and thus the calculation of the compression rate of the seal ring is involved. In the existing engineering design process, the standard HB / Z 4-95 “Design Requirements for O-shaped Seal Ring and Sealing Structure” is used to calculate the compression rate of the seal ring for the shaft groove sealing structure. Figure 1

[0003] (1) The specific method for calculating the minimum compression rate is as follows:

[0004] 1) Calculate the tensile rate of the O-shaped seal ring after being assembled into the shaft groove

[0005] 2) Radial size of the cross section of the seal ring

[0006] 3) Groove depth

[0007] 4) Calculate the minimum compression rate of the shaft with the O-shaped seal ring assembled into the hole

[0008] (2) The specific method for calculating the maximum compression rate is as follows:

[0009] 1) Calculate the tensile rate of the O-shaped seal ring after being assembled into the shaft groove

[0010] 2) Radial size of the cross section of the seal ring

[0011] 3) Groove depth

[0012] 4) Calculate the maximum compression rate of the shaft with the O-shaped seal ring assembled into the hole

[0013] ​Obviously, for the groove depth h, the hole inner diameter is subtracted from the shaft groove outer diameter and then divided by 2 to obtain, this formula considers that the upper and lower groove depths are equal, and is obtained under the premise that the shaft groove is coaxial with the hole, without considering the eccentricity condition, in addition, like the comparative file process technology 2018 19 period "O type sealing ring compression rate calculation method and example verification", the calculation of the sealing ring compression rate also does not consider the eccentricity problem. However, in fact, the shaft outer diameter and the hole exist assembly eccentricity, and the shaft outer diameter and the shaft groove exist machining eccentricity, the assembly eccentricity and the machining eccentricity are both radial eccentricity, which affects the groove depth which is also radially arranged, thereby affecting the minimum elongation rate and the maximum elongation rate, and affecting the sealing ring compression rate, so that the calculation results are inconsistent in actual application, affecting the calculation of the sealing ring compression amount, and finally affecting the sealing performance of the product. SUMMARY

[0014] The purpose of the present application is to provide a shaft groove sealing ring compression rate calculation method considering the eccentricity problem, so as to more accurately calculate the shaft groove sealing ring compression rate, and provide basis and reference for sealing structure design.

[0015] The technical scheme of the present application is a shaft groove sealing ring compression rate calculation method, which obtains assembly eccentricity and machining eccentricity, calculates the depth parameter of the radial groove formed after assembly, adds the assembly eccentricity and the machining eccentricity to the depth parameter of the radial groove when calculating the sealing ring compression rate, obtains the actual depth of the radial groove, and calculates the sealing ring compression rate by using the actual depth of the radial groove and the radial dimension of the sealing ring cross section.

[0016] The machining eccentricity is the eccentricity of the groove bottom diameter axis relative to the shaft outer diameter axis, which is obtained by measuring the coaxiality e between the groove bottom diameter axis and the shaft outer diameter axis with the shaft outer diameter axis as the reference.

[0017] Specifically, the coaxiality e is obtained by finding the corresponding axis of the shaft outer diameter by measuring three points on the two cross sections of the shaft outer diameter along the circumference with a three-coordinate measuring machine, finding the corresponding axis of the shaft groove bottom diameter by using the same method, and obtaining the cylindrical diameter of the cylindrical envelope of the shaft bottom diameter axis relative to the shaft outer diameter axis, and the half of the coaxiality is the machining eccentricity.

[0018] When the sealing ring compression rate is the minimum, the sealing ring assembly eccentricity is calculated by the difference between the maximum hole diameter of the shaft assembly hole and the minimum outer diameter of the shaft.

[0019] When the sealing ring compression rate is the maximum, the sealing ring assembly eccentricity is calculated by the difference between the minimum hole diameter of the shaft assembly hole and the minimum outer diameter of the shaft.

[0020] The elongation rate of the sealing ring after being assembled into the shaft groove is calculated respectively under the maximum compression state and the minimum compression state of the sealing ring, wherein,

[0021] The tensile rate of the sealing ring after being assembled into the shaft groove in the minimum compression state Wherein, D 1min is the minimum value of the shaft groove bottom diameter, d min is the minimum value of the sealing ring cross section diameter, D min is the minimum value of the sealing ring inner diameter, the values of the three parameters are considered the integrity and consistency of the compression rate calculation process and the parameter influence degree, not simply applying the basic size into the formula, and there is no maximum value of the molecule, compared with, the calculated tensile rate is larger, and is closer to the real limit state.

[0022] The tensile rate of the sealing ring after being assembled into the shaft groove in the maximum compression state Wherein, D 1max is the maximum value of the shaft groove bottom diameter, d max is the maximum value of the sealing ring cross section diameter, D max is the maximum value of the sealing ring inner diameter, the values of the three parameters are considered the integrity and consistency of the compression rate calculation process and the parameter influence degree, not simply applying the basic size into the formula, and there is no minimum value of the molecule, compared with, the calculated tensile rate is smaller, and is closer to the real limit state.

[0023] The minimum compression rate of the sealing ring when the shaft is assembled into the hole Wherein, b min is the cross section radial size of the sealing ring in the minimum compression state, h max is the actual groove depth.

[0024] The maximum compression rate of the sealing ring when the shaft is assembled into the hole Wherein, b max is the cross section radial size of the sealing ring in the maximum compression state, h min is the actual groove depth.

[0025] The beneficial effects of the present application are that the new method for calculating the compression rate of the shaft groove sealing ring of the present application clearly defines the specific steps and formula when calculating the minimum compression rate and the maximum compression rate. For the calculation of the sealing groove depth h, the assembly eccentricity e1 and the machining eccentricity e2 (i.e. one half of the coaxiality e of the shaft groove bottom diameter to the installation shaft outer diameter) are considered, compared with the calculation method in the existing navigation mark, in the limit case of the minimum compression rate, the sealing groove depth h value is larger, and the compression rate is smaller, in engineering application, the sealing structure is designed with the minimum compression rate being greater than the minimum allowable compression rate, the method proposed in the present application can better reflect the limit case of assembly, the calculated minimum compression rate is more accurate, can provide an important reference for the design of the sealing structure, and reduce the oil leakage rate. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1is a structural schematic diagram of the prior art;

[0027] Figure 2 is a structural schematic diagram of the minimum compression state of embodiment 1 of the present application;

[0028] Figure 3 is a structural schematic diagram of the maximum compression state of embodiment 1 of the present application;

[0029] Figure 4 is a structural schematic diagram of the minimum compression state of embodiment 2 of the present application;

[0030] Figure 5 is a structural schematic diagram of the maximum compression state of embodiment 2 of the present application;

[0031] wherein d is the seal ring cross-sectional diameter, D is the seal ring nominal inner diameter, D D is the nominal inner diameter of the hole, D d is the nominal outer diameter of the shaft, D1 is the bottom diameter of the shaft groove, D2 is the bottom diameter of the hole groove, b is the radial dimension of the seal ring cross-section after stretching, h is the depth of the seal groove, e1 is the eccentricity of the shaft and hole assembly, and e2 is the machining eccentricity of the bottom diameter of the shaft groove relative to the shaft or the machining eccentricity of the bottom diameter of the hole groove relative to the hole. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and specific embodiments.

[0033] Embodiment 1:

[0034] A certain shaft groove sealing structure is as shown in Figure 2 , wherein the seal ring cross-sectional diameter d = φ2.1 ± 0.08, the seal ring nominal inner diameter D is the nominal inner diameter of the hole, is the nominal outer diameter of the shaft, the bottom diameter of the shaft groove D1 = φ8.2 ± 0.07, and the coaxiality e of the shaft groove center line relative to the shaft center line is φ0.05.

[0035] wherein the following steps involve parameters: D 1min , D 1max represent the minimum and maximum values of the bottom diameter of the shaft groove, d min , d max represent the minimum and maximum values of the seal ring cross-sectional diameter, D min , D max represent the minimum and maximum values of the seal ring inner diameter, D Dmin , D Dmax are the minimum and maximum values of the assembly hole inner diameter, and D dmin is the minimum value of the shaft outer diameter.

[0036] The sealing ring in this embodiment is in the minimum compression state, and the minimum compression rate is calculated as follows:

[0037] 1) Calculate the tensile rate of the O-ring after being assembled into the shaft groove

[0038] 2) Radial size of the sealing ring cross section

[0039] 3) Assembly eccentricity

[0040] 4) Machining eccentricity

[0041] 5) Groove depth

[0042] Substitute the formulas of 3) and 4) to obtain

[0043]

[0044] 6) Calculate the minimum compression rate of the shaft with the O-ring assembled into the hole

[0045]

[0046] Unlike the conventional sealing ring, the minimum compression rate of the same sealing ring without considering eccentricity is 17.0%, so the minimum compression rate of the present application is reduced by 7% compared to that without considering eccentricity, which has a large difference and can directly affect the sealing performance of the sealing ring.

[0047] As shown in Figure 3 , the sealing ring is in the maximum compression state, and the maximum compression rate of the present application is calculated as follows:

[0048] 1) Calculate the tensile rate of the O-ring after being assembled into the shaft groove

[0049] 2) Radial size of the sealing ring cross section

[0050] 3) Assembly eccentricity

[0051] 4) Machining eccentricity

[0052] 5) Groove depth

[0053] Substitute the formulas of 3) and 4) to obtain

[0054]

[0055] 6) Calculate the maximum compression rate of the shaft with the O-ring assembled into the hole

[0056]

[0057] Similarly, in this embodiment, if eccentricity is not considered, the maximum compression rate of the seal ring is 20.8%, which is four-fifths of the compression rate when eccentricity is considered.

[0058] Example 2. This example is similar to Example 1, except that the seal ring is installed in a hole groove inside the housing, the hole groove sealing structure is as shown in Figure 4 、 Figure 5 The known seal ring cross-sectional diameter d = φ 1.9 ± 0.1, the nominal inner diameter of the seal ring The nominal inner diameter of the hole The nominal outer diameter of the shaft The bottom diameter of the hole groove The coaxiality of the hole groove center line relative to the hole center line e = φ 0.08.

[0059] Where the following steps involve parameters: D dmin , D dmax is the minimum and maximum value of the outer diameter of the sealing shaft, d min , d max is the minimum and maximum value of the cross-sectional diameter of the seal ring, D min , D max is the minimum and maximum value of the inner diameter of the seal ring, D 2min , D 2max is the minimum and maximum value of the bottom diameter of the hole groove, D Dmax is the maximum value of the inner diameter of the mounting hole.

[0060] As shown in Figure 4 , which gives the minimum compression state of the seal ring of this embodiment, the minimum compression rate is calculated as follows:

[0061] 1) Calculate the tensile rate of the O-ring seal mounted on the shaft

[0062] 2) The radial dimension of the cross section of the seal ring

[0063] 3) Assembly eccentricity

[0064] 4) Machining eccentricity

[0065] 5) Groove depth

[0066] Substitute 3) 4) into the formula to get

[0067]

[0068] 6) Calculate the minimum compression rate of the shaft assembled into the hole with O-ring

[0069]

[0070] In the same structure, the minimum compression rate without considering eccentricity is 16.0%, and the result in the application is 3.3%, which is quite different. The sealing ring fixed sealing in the aviation standard requires a compression rate range of 18% to 22%, and the minimum allowable compression rate is 7%. It can be seen that the minimum compression rate without considering eccentricity meets the requirements, while the result of the application shows that the sealing may be poor and oil leakage may occur. That is, the application can better test the rationality of the design size of the sealing structure.

[0071] As Figure 5 mentioned, it gives the limit case of the maximum compression rate of the hole groove sealing structure, and the specific calculation method is as follows:

[0072] 1) Calculate the tensile rate of the O-ring assembled on the shaft

[0073] 2) Sealing ring cross-sectional radial dimension

[0074] 3) Assembly eccentricity

[0075] 4) Machining eccentricity

[0076] 5) Groove depth

[0077] Substitute the formulas of 3) and 4) to get

[0078]

[0079] 6) Calculate the maximum compression rate of the shaft assembled into the hole with O-ring

[0080]

[0081] Similar to the minimum compression rate calculation, the maximum compression rate without considering eccentricity is 18.6%, which is smaller than the eccentricity considered in the application, and does not reflect the compression rate of the maximum compression state of the sealing ring. The compression rate calculated by the application is larger, and can better reflect the limit case of the sealing.

[0082] The above only describes the preferred embodiments of the application and is not intended to limit the application. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application. In addition, the parts not described in the application are conventional techniques.

Claims

1. A method of calculating a compression ratio of a shaft groove seal ring, characterized by, The assembly eccentricity and the machining eccentricity are obtained, the depth parameter of the radial groove formed after assembly is calculated, the assembly eccentricity and the machining eccentricity are added to the depth parameter of the radial groove when calculating the compression rate of the sealing ring, the actual depth of the radial groove is obtained, and the compression rate of the sealing ring is calculated by using the actual depth of the radial groove and the radial dimension of the cross section of the sealing ring; The stretching rate of the sealing ring after assembly into the shaft groove is calculated respectively in the maximum compression state and the minimum compression state of the sealing ring, wherein, Tensile ratio of seal ring after assembled into shaft groove under minimum compression state Tensile ratio of sealing ring after assembled into shaft groove in maximum compression state wherein D 1min is the minimum value of the shaft groove bottom diameter, d min is the minimum value of the seal ring cross-sectional diameter, D min is the minimum value of the seal ring inner diameter; D 1max is the maximum value of the shaft groove bottom diameter, d max is the maximum value of the seal ring cross-sectional diameter, D max is the maximum value of the seal ring inner diameter; Minimum compression ratio of shaft assembly of sealing ring into hole wherein b min is the cross-sectional radial dimension of the sealing ring in the minimum compressed state, h max is the actual groove depth, Assembly eccentricity Processing eccentricity Maximum compression of the seal ring's shaft into the bore wherein b max is the cross-sectional radial dimension of the sealing ring in the maximum compressed state, h min is the actual groove depth, 2. The method of claim 1, wherein, The machining eccentricity is the eccentricity of the groove bottom diameter axis relative to the shaft outer diameter axis, and the coaxiality between the groove bottom diameter axis and the shaft outer diameter axis is measured by taking the shaft outer diameter axis as a reference.

3. The method of claim 2, wherein, The coaxiality is obtained by using a three-coordinate measuring machine to find corresponding axes by measuring three points along the circumference of two cross sections of the shaft outer diameter respectively, and the same method is used to find corresponding axes of the shaft groove bottom diameter. The cylindrical diameter obtained by taking the shaft outer diameter axis as a cylindrical envelope of the shaft bottom diameter axis is the coaxiality of the shaft groove bottom diameter relative to the shaft outer diameter, and half of the coaxiality is the machining eccentricity.

4. The method of claim 1, wherein, When the compression rate of the sealing ring is the minimum, the sealing ring assembly eccentricity is calculated by the difference between the maximum hole diameter of the shaft assembly hole and the minimum outer diameter of the shaft.

5. The method of claim 1, wherein, When the compression rate of the sealing ring is the maximum, the sealing ring assembly eccentricity is calculated by the difference between the minimum hole diameter of the shaft assembly hole and the minimum outer diameter of the shaft.

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