A method for solving the specific sealing pressure of a contact type cylindrical-conical sealing structure

Abstract

This invention relates to the field of mechanical seal safety technology, and particularly to a method for calculating the sealing specific pressure of a contact-type cylindrical-conical seal structure. The method includes: Step S1: Designing the geometric parameters of the contact-type cylindrical-conical seal structure and the constraint range of the geometric parameters; Step S2: Calculating the contact width of the contact area of ​​the cylindrical-conical seal structure based on the geometric parameters; Step S3: Calculating the sealing specific pressure of the contact area of ​​the cylindrical-conical seal structure based on the contact width. This invention provides a method for calculating the sealing specific pressure of a contact-type cylindrical-conical seal structure, combining the correlation between the contact area and geometric parameters to obtain the method for calculating the sealing specific pressure of the contact-type cylindrical-conical seal structure. This method provides rapid solutions and can be applied to the design of semi-static seal structures, which is of great significance for improving the service performance of spring-loaded valve components.

Description

Technical Field

[0001] This invention relates to the field of mechanical seal safety technology, and in particular to a method for solving the sealing specific pressure of a contact-type cylindrical-conical sealing structure. Background Technology

[0002] With the rapid development of major engineering fields such as aerospace, energy, automotive, and shipbuilding, spring-loaded valve components with diverse functions are widely used in various high-end equipment. The opening and closing process of these components depends solely on the system pressure. They are simple in structure, reliable in operation, and widely used in demanding conditions such as high pressure, heavy load, and frequent operation. The valve's service life often involves a semi-static sealing structure with an R-shaped stop and a conical or flat surface fitting. The R-shaped-flat fit can be considered a special form of the R-shaped-conical fit structure. When closed, it is in a static state, achieving a seal by compressing the non-metallic material through the sealing pair to induce elastic deformation and block leakage channels, thereby ensuring system safety.

[0003] Currently, most cylindrical-conical sealing structures are designed and optimized through simulation analysis or experimental investigation, which can effectively solve the sealing failure problem of spring-loaded valves. However, the above methods require extensive numerical simulation or experimental research, and they are not universal for sealing pairs with different structural parameters and contact states, making it difficult to quickly and accurately solve the sealing specific pressure of the cylindrical-conical mating pair.

[0004] Therefore, it is necessary to summarize the contact-type cylindrical-conical sealing structure and propose a method for solving the sealing specific pressure of the mating pair, so as to realize the rapid solution and prediction of the sealing specific pressure of the sealing structure, thereby improving the sealing and service performance of spring valve parts. Summary of the Invention

[0005] This invention addresses the limitations and defects of existing technologies by proposing a method for calculating the sealing specific pressure of a contact-type cylindrical-conical sealing structure. Based on the contact-type cylindrical-conical sealing structure and its contact characteristics, this method summarizes the general rules governing the fit between the R-shaped stop and the valve core sealing pair, and designs the geometric parameters of the cylindrical-conical sealing structure. Considering the spring load, sealing pressure difference, and total length of the sealing pair, the load per unit length of the contact area is obtained. Combining this with the correlation between the load and the R-shaped stop structural parameters, the unit load perpendicular to the R-shaped stop surface contact area is obtained. Furthermore, considering the material properties of the sealing structure, the contact width of the cylindrical-conical sealing pair is calculated. Combining the unit load and contact width of the contact-type cylindrical-conical sealing structure, the equivalent sealing specific pressure of the contact area of ​​the cylindrical-conical sealing structure is calculated, and it is determined whether the valve sealing requirements are met. This includes:

[0006] Step S1: Design the geometric parameters of the contact-type cylindrical-conical sealing structure and the constraint range of the geometric parameters;

[0007] Step S2: Based on the geometric parameters, calculate the contact width of the contact area of ​​the cylindrical-conical sealing structure;

[0008] Step S3: Calculate the sealing pressure of the contact area of ​​the cylindrical-conical sealing structure based on the contact width.

[0009] Furthermore, designing the geometric parameters in step S1 includes:

[0010] Design the contact-type cylindrical-conical sealing structure with a nominal diameter of d. In the cross-section of the sealing structure, the inclination angle of the conical surface of the valve core sealing pair is θ. The bottom length of the conical surface of the valve core sealing pair is D, the height of the conical surface is H, and the angle between the R-shaped stop profile of the valve seat sealing pair and the bottom surface of the valve core sealing pair is ξ.

[0011] The center of the R-shaped stop circle on the valve seat sealing pair is designed to be O. i The radius is r i , i = 1, 2, 3... where the R-shaped stop circle is the circle containing the R-shaped stop outline;

[0012] Design point O is the center of the circle enclosed by the center of the R-shaped stop circle, and the radius of the enclosing circle is R. i i = 1, 2, 3...

[0013] Furthermore, in the aforementioned contact-type cylindrical-conical sealing structure, under sealing conditions, the R-shaped circle of the stop must be tangentially fitted to the conical surface of the valve core sealing pair;

[0014] That is, the geometric parameters in the aforementioned contact-type cylindrical-conical sealing structure must satisfy the following constraints:

[0015]

[0016] That is, the constraint range of the geometric parameters should be as follows:

[0017]

[0018] Further, step S2 includes:

[0019] Step S21: Calculate the total length L of the contact area between the R-shaped stop surface and the conical surface and the total load F of the contact cylindrical-conical sealing structure;

[0020] Step S22: Solve for the unit length load f using the calculated total length L of the contact area and the total load F;

[0021] Step S23: Calculate the unit length load f perpendicular to the contact area of ​​the R-shaped stop by combining the force analysis of the R-shaped stop with the unit length load f.N ;

[0022] Step S24: Combine the unit length load f N Equivalent Young's modulus E of sealing structural materials * Solve for the Hertzian contact half-width b of the contact region of the contact-type cylindrical-conical sealing structure.

[0023] Further, step S21 includes: based on the geometric parameters, and assuming the R-shaped stop surface is tangent to the conical surface, the total length L of the contact area is:

[0024]

[0025] The total load F can be obtained by the following formula:

[0026] F = F T -F L =F0+kl-ΔPS (4)

[0027] In the formula, F T =F O +kl is the spring force on the valve core sealing pair, F O The force exerted by the spring on the R-shaped stop surface when it mates with the bottom surface of the valve core sealing conical surface is denoted by k, where k is the spring stiffness coefficient. F represents the relative displacement of the spring. L =ΔPS is the resultant force of the fluid acting on the valve core sealing surface, and ΔP is the sealing pressure difference. The area of ​​the valve core sealing surface where the fluid acts is denoted.

[0028] Further, the unit length load f in step S22 is:

[0029]

[0030] Further, step S23 includes: performing a stress analysis on the R-shaped stop to obtain:

[0031] F N ×coSθ+F f ×sinθ=F (6)

[0032] In the formula, F N F is the normal load perpendicular to the contact area of ​​the R-shaped stop surface. f =μF N denoted as σ, where μ is the frictional force on the R-shaped stop surface.

[0033] The unit length load f perpendicular to the contact area of ​​the R-shaped stop surface N for:

[0034]

[0035] In the formula, f is the load per unit length, and μ is the coefficient of friction.

[0036] Further, step S24 includes:

[0037] The equivalent Young's modulus E of the sealing structure material is known. * It can be obtained from the following formula:

[0038]

[0039] Wherein, E1 and E2 are the Young's modulus of the two sealing structure materials, and V1 and V2 are the Poisson's ratios of the two materials.

[0040] Then, using Hertzian contact theory, the Hertzian contact half-width b of the contact region of the cylindrical-conical sealing structure is:

[0041]

[0042] Among them, f N For the unit length load perpendicular to the contact area of ​​the R-shaped stop surface, E * The equivalent Young's modulus of the sealing structure material.

[0043] Further, step S3 includes:

[0044] For the aforementioned contact-type cylindrical-conical seal structure, the minimum sealing specific pressure q required to maintain the seal is... min It can be obtained from the following formula:

[0045]

[0046] In the formula, C and K are both dimensionless constants related to material properties.

[0047] The equivalent sealing pressure q of the contact-type cylindrical-conical sealing structure is:

[0048]

[0049] The sealing design is checked using the sealing pressure ratio method. The design equivalent sealing pressure must meet the following requirements:

[0050] q min ≤q≤[q] (12)

[0051] In the formula, [q] represents the allowable sealing pressure.

[0052] The significant effects and benefits of this invention are:

[0053] 1. This invention provides a method for solving the sealing specific pressure of a contact-type cylindrical-conical sealing structure. Based on summarizing the contact-type cylindrical-conical sealing structure and its contact characteristics, this method summarizes the general rules of the fit between the R-shaped stop and the conical surface, and designs the geometric parameters of the cylindrical-conical sealing structure; it also reasonably controls the structure and size of the sealing pair, and effectively adjusts the contact width and contact pressure of the sealing pair.

[0054] 2. This invention provides a method for solving the sealing specific pressure of a contact-type cylindrical-conical sealing structure. By combining the correlation between the contact area and geometric parameters, a method for solving the sealing specific pressure of a contact-type cylindrical-conical sealing structure is obtained. This method is fast and can be applied to the design of semi-static sealing structures, which is of great significance for improving the service performance of spring-type valve parts. Attached Figure Description

[0055] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0056] In the attached diagram:

[0057] Figure 1 This is an overall flowchart of the method for solving the sealing specific pressure of a contact-type cylindrical-conical sealing structure according to the present invention;

[0058] Figure 2 This is an algorithm diagram for solving the sealing specific pressure of a contact-type cylindrical-conical sealing structure according to the present invention;

[0059] Figure 3 This is a cross-sectional schematic diagram of a contact-type cylindrical-conical sealing structure according to the present invention;

[0060] Figure 4 This is a schematic diagram of the R-shaped stop structure of a contact-type cylindrical-conical sealing structure according to the present invention;

[0061] Figure 5 This is a schematic diagram of the contact area of ​​a contact-type cylindrical-conical sealing structure according to the present invention;

[0062] Figure 6 This invention presents the variation law of equivalent sealing specific pressure and minimum sealing specific pressure with the radius r of the R-shaped stop in a method for solving the sealing specific pressure of a contact-type cylindrical-conical sealing structure.

[0063] Figure 7 The curves showing the equivalent and minimum sealing pressures of the contact-type cylindrical-conical sealing structure as a function of the conical inclination angle θ of the valve core sealing pair are presented in the present invention.

[0064] Figure 8The graph shows the equivalent sealing pressure and minimum sealing pressure as a function of the sealing pair pressure difference ΔP, representing the sealing pressure solution method for a contact-type cylindrical-conical sealing structure according to the present invention. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0066] Example 1

[0067] Please see Figure 1-8 The technical solution for solving the sealing specific pressure of a contact-type cylindrical-conical sealing structure provided in this embodiment includes the following:

[0068] Step 1

[0069] In practical implementation, this type of cylindrical-conical sealing structure is mostly composed of a metal sealing pair with an R-shaped stop and a non-metallic conical sealing pair. (In this embodiment, its cross-sectional structure is referred to as the R-shaped stop and the conical surface.) Among them, the R-shaped-planar fit can be considered a special form of the R-shaped-conical fit structure. For example... Figure 2 , Figure 3 As shown, assuming the nominal diameter is d = 6 mm, the inclination angle of the valve core sealing conical surface is θ = 30°, the angle between the R-shaped stop profile of the valve seat sealing pair and the bottom surface of the valve core sealing pair is ζ = 60°, and the radius of the R-shaped stop circle is r = 2 mm, then the radius of the envelope circle is... Furthermore, the diameter of the bottom of the cone is D = 8 mm, and the height of the cone is H = 2 mm. Substituting the above structural parameters into equation (2), the range of geometric parameters is determined as follows:

[0070]

[0071] As can be seen from the above formula, the valve core and valve seat will not interfere with each other, and the geometric parameters of the R-shaped surface meet the design requirements.

[0072] Step 2

[0073] In specific implementation, as shown in the appendix Figure 4 As shown, under load F N Under the action of the material, the cylindrical stop and the conical plane are in close contact, and the seal is achieved through the extrusion deformation of the two materials. The actual contact area of ​​the sealing pair is a rectangular area with a contact length of L and a width of 2b. Given that the R-shaped stop surface is in tangential contact with the conical surface, the total length L of the contact area can be solved by equation (3):

[0074]

[0075] Given that the spring force on the R-shaped stop surface when it mates with the bottom surface of the valve core sealing pair is F0 = 50 N, the spring stiffness coefficient is k = 5000 N / m, and the sealing pressure difference is ΔP = 0.3 MPa, and further, the relative displacement of the spring l and the area S of the fluid acting on the surface of the valve core sealing pair are as follows:

[0076]

[0077]

[0078] The total load F of the sealed structure can be obtained from equation (4):

[0079] F = F0 + kl - ΔPS = 24.73 N

[0080] Taking the friction coefficient as μ = 0.3, then the normal load F N It can be obtained from equation (6):

[0081]

[0082] Combining equations (5) and (7), the unit length load f perpendicular to the contact area of ​​the R-shaped stop surface can be obtained. N :

[0083]

[0084] In practical implementation, given that the Young's moduli of the two materials are E1 = 199 GPa and E2 = 0.447 GPa, and their Poisson's ratios are v1 = 0.3 GPa and v2 = 0.4 GPa, the equivalent Young's modulus E* of the materials can be obtained from equation (8):

[0085]

[0086] Then the Hertzian contact half-width b of the contact area can be obtained as:

[0087]

[0088] Step 3

[0089] In practical implementation, for polytetrafluoroethylene propylene Fs-46 material, taking C=16 and K=0.9, the minimum sealing specific pressure q required to maintain the seal of the contact cylindrical-conical seal structure is as follows: min It can be obtained from equation (10):

[0090]

[0091] Furthermore, the equivalent sealing pressure q of the contact-type cylindrical-conical sealing structure can be obtained by solving equation (11):

[0092]

[0093] The sealing design is checked using the sealing pressure ratio method. The design equivalent sealing pressure must satisfy equation (12):

[0094] q min =2.56MPa≤q=11.6MPa≤[q]=20MPa

[0095] In the formula, [q] is the allowable sealing pressure, which is 20-30 MPa for polytetrafluoroethylene propylene Fs-46 material.

[0096] Thus, the equivalent sealing pressure of the contact cylindrical-conical sealing structure was obtained. The design verification results show that the contact cylindrical-conical sealing structure has good sealing performance under the above structural parameters.

[0097] Example 2

[0098] In practical implementation, in order to explore the variation law of the design equivalent sealing pressure q of the cylindrical-conical sealing structure with parameters such as the radius r of the R-shaped stop circle, the inclination angle θ of the conical surface of the valve core sealing pair, and the sealing pressure difference ΔP, the sealing pressure is quickly solved and verified based on the above material properties.

[0099] With other parameters remaining constant, if the radius of the R-shaped stop circle of the valve seat sealing pair varies within the range of r = [1mm, 3mm), then the sealing specific pressure can be calculated using the method shown in the attached figure. Figure 5 The diagram shows the variation of the equivalent sealing pressure and the minimum sealing pressure with the radius r of the R-shaped stop. The design equivalent sealing pressure gradually decreases as the radius r of the R-shaped stop increases, while the minimum sealing pressure first decreases and then increases as the radius r of the R-shaped stop increases. It is worth noting that when the radius r of the R-shaped stop is small, the equivalent sealing pressure may exceed the allowable pressure of the material, which may easily cause material damage and lead to seal failure.

[0100] In practical implementation, when the inclination angle of the valve core sealing conical surface varies within the range of θ = [0, 45°], the variation law of the design equivalent sealing specific pressure and the minimum sealing specific pressure with the inclination angle θ of the valve core sealing conical surface is shown in the appendix. Figure 6 As shown, the design equivalent sealing pressure gradually decreases as the tilt angle θ of the valve core sealing conical surface increases, while the minimum sealing pressure gradually increases as the tilt angle θ of the valve core sealing conical surface increases. However, when the tilt angle varies within the range of θ = [0, 45°], the design equivalent sealing pressure is always greater than the minimum sealing pressure, which can ensure effective sealing of the mating structure.

[0101] In practical implementation, when the internal and external pressure difference varies within the range of ΔP = [0 MPa, 0.5 MPa], the variation patterns of the design equivalent sealing pressure and the minimum sealing pressure with the pressure difference ΔP are shown in the attached figure. Figure 7As shown, the design equivalent sealing pressure gradually decreases with the increase of pressure difference ΔP, while the minimum sealing pressure increases with the increase of pressure difference ΔP. When the pressure difference ΔP > 0.46 MPa, the design equivalent sealing pressure does not meet the minimum sealing pressure, and the seal fails.

[0102] In summary, this method can quickly and accurately solve the equivalent sealing pressure of a contact-type cylindrical-conical structure under given operating conditions, and determine the changing trend and relative relationship between the sealing pressure and the minimum sealing pressure. It can be applied to the optimization design of semi-static sealing structures and has important application significance for improving the service and sealing performance of spring valves.

[0103] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for calculating the sealing specific pressure of a contact-type cylindrical-conical sealing structure, characterized in that, include: Step S1: Design the geometric parameters of the contact-type cylindrical-conical sealing structure and the constraint range of the geometric parameters; Step S2: Based on the geometric parameters, calculate the contact width of the contact area of ​​the cylindrical-conical sealing structure; Step S3: Calculate the sealing specific pressure of the contact area of ​​the cylindrical-conical sealing structure based on the contact width; The design of the geometric parameters in step S1 includes: The design diameter is: d The contact-type cylindrical-conical sealing structure, wherein the inclination angle of the valve core sealing pair conical surface in the cross-section of the sealing structure is . The length of the bottom of the conical surface of the valve core sealing pair is D The height of the cone is H In the valve seat sealing pair The angle between the outline of the shaped stop and the bottom surface of the valve core sealing pair is... ; Design valve seat sealing pair The center of the circle of the stop mouth is , radius is , i =1, 2, 3...... where the... The shape of the stop circle is the described The circle containing the outline of the stop; Design Points O Let be the center of the circle enclosed by the center of the R-shaped stop circle, and let the radius of the enclosing circle be . , i =1, 2, 3... In the aforementioned contact-type cylindrical-conical sealing structure, it is necessary to ensure that the R-shaped stop circle and the conical surface of the valve core sealing pair are tangentially fitted under sealing conditions. That is, the geometric parameters in the aforementioned contact-type cylindrical-conical sealing structure must satisfy the following constraints: That is, the constraint range of the geometric parameters should be as follows: in The angle of inclination of the cone surface. The angle between the R-shaped stop profile of the valve seat sealing pair and the conical surface. r The radius of the R-shaped stop circle, D The length of the bottom of the cone. d The bore diameter is for the contact-type cylindrical-conical sealing structure. H The height of the cone; Step S2 includes: Step S21: Calculate the total length of the contact area between the R-shaped stop surface and the conical surface. L The total load of the contact-type cylindrical-conical sealing structure F ; Step S22: Use the total length of the contact area obtained from the solution. L and the total load F Calculate the load per unit length ; Step S23: Combining the force analysis of the R-shaped stop with the unit length load Solve for the unit length load perpendicular to the R-shaped stop contact area. ; Step S24: Combine the unit length load Equivalent Young's modulus of sealing structural materials Calculate the Hertzian contact half-width of the contact area of ​​the contact-type cylindrical-conical sealing structure. b .

2. The method for calculating the sealing specific pressure of the contact-type cylindrical-conical sealing structure according to claim 1, characterized in that: Step S21 includes: based on the geometric parameters of the sealing structure, and assuming the R-shaped stop surface is tangent to the conical surface, the total length of the contact area is... L for: In the formula, d The bore diameter is for the contact-type cylindrical-conical sealing structure. r The radius of the R-shaped stop circle, The angle of inclination of the cone surface; The total load F can be obtained by the following formula: In the formula, The spring force on the valve core sealing pair, This refers to the spring force exerted when the R-shaped stop surface mates with the bottom surface of the valve core sealing conical surface. This is the spring stiffness coefficient. This represents the relative displacement of the spring. The resultant force of the fluid acting on the valve core sealing surface. To seal the pressure difference, The area of ​​the valve core sealing surface where the fluid acts is denoted.

3. The method for calculating the sealing specific pressure of the contact-type cylindrical-conical sealing structure according to claim 2, characterized in that: The unit length load in step S22 for: In the formula, L The total length of the contact area. F This represents the total load.

4. The method for calculating the sealing specific pressure of the contact-type cylindrical-conical sealing structure according to claim 3, characterized in that: Step S23 includes: performing a stress analysis on the R-shaped stop to obtain: In the formula, The normal load is perpendicular to the contact area of ​​the R-shaped stop surface. The frictional force on the R-shaped stop surface. The coefficient of friction; The unit length load perpendicular to the contact area of ​​the R-shaped stop surface for: In the formula, For unit length load, The coefficient of friction, The angle of inclination of the cone surface.

5. The method for solving the sealing specific pressure of the contact-type cylindrical-conical sealing structure according to claim 4, characterized in that: Step S24 includes: The equivalent Young's modulus of the sealing structure material is known. It can be obtained from the following formula: in, , These are the Young's moduli of the two sealing structure materials. 、 These are the Poisson's ratios of the two materials, respectively. Then, using Hertzian contact theory, the Hertzian contact half-width b of the contact region of the cylindrical-conical sealing structure is: in, The load per unit length is perpendicular to the contact area of ​​the R-shaped stop surface. The equivalent Young's modulus of the sealing structure material.

6. The sealing pressure ratio of the contact-type cylindrical-conical sealing structure according to claim 1 The solution method is characterized by: Step S3 includes: For the aforementioned contact-type cylindrical-conical seal structure, the minimum sealing specific pressure required to maintain the seal is... It can be obtained from the following formula: In the formula, C , K All of these are dimensionless constants related to material properties. To seal the pressure difference, b For Hertzian contact half-width; The equivalent sealing pressure of the contact-type cylindrical-conical sealing structure is then... for: In the formula, The normal load is perpendicular to the contact area of ​​the R-shaped stop surface. b For Hertzian contact half-width, L This represents the total length of the contact area. The sealing design is checked using the sealing pressure ratio method. The design equivalent sealing pressure must meet the following requirements: In the formula, The allowable sealing pressure.

Images