Definition method of valve V-shaped filler structure and installation form based on dimensionless function

Abstract

A valve V-shaped filler structure and installation form definition method based on a dimensionless function belongs to the technical field of filler sealing, and comprises the following steps: selecting V-shaped filler key variable structure parameters, stipulating and analyzing the relationship between shoulder angles c1 and c2 in forward installation and reverse installation forms, selecting the sign of a difference function lambda (c1, c2) by using sign [lambda (c1, c2)], and defining the filler installation form; defining a shoulder angle difference function delta as a difference between a large value and a small value in the shoulder angles c1 and c2, and defining a filler structure by using a maximum and minimum difference function kappa (c1, c2) as a difference between 1 and a ratio of a smaller value to a maximum value of the shoulder angles c1 and c2; defining a packing structure and a mounting form by using a dimensionless function # imgabs0 # as a product of sign [lambda (c1, c2)] and kappa (c1, c2); and the dimensionless function and the shoulder angle difference function are combined, shoulder angles c1 and c2 are solved, and the filler structure and the corresponding installation form are obtained. According to the invention, simultaneous definition of a filler structure and an installation form can be realized, and definition when shoulder angles c1 and c2 change at the same time and a difference relation between the shoulder angles c1 and c2 is considered can also be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of packing seals, and in particular relates to a method for defining a valve V-shaped packing structure and an installation form based on a dimensionless function. Background Art

[0002] Valve packing is a key component to achieve valve sealing. The quality of packing sealing performance directly determines the safety of valve use. Failure of the packing sealing unit will cause medium leakage, threatening the safe operation of the hydraulic system and the safety of life and property of the staff.

[0003] During the valve design process, engineers preliminarily determine the packing sealing elements based on the actual working conditions and valve body structure, and further need to adjust the packing structural parameters and installation form to achieve a good sealing effect. Therefore, when designing packing elements, it is necessary to focus on analyzing the impact of packing structure and packing installation form on packing sealing performance. However, there is currently no definition method for packing structure or packing installation form. When designing packing, it is usually done based on experience, which makes it difficult to accurately define the packing and analyze the sealing performance. It is impossible to consider the impact of simultaneous changes in packing structure and installation form on packing sealing performance, nor is it possible to consider the impact of simultaneous changes in multiple key structural parameters of the packing on packing sealing performance.

[0004] For packing sealing problems with complex influencing factors, it is not reliable to design packing elements based on experience alone. It is urgent to propose a packing definition method that can define both the packing structure and the installation form at the same time, provide technical support for the design and optimization of packing sealing elements, prevent fatigue damage and sealing failure of packing sealing elements, and improve the safety and reliability of valve packing sealing elements. Summary of the invention

[0005] In view of the problem that there is no packing structure definition method and packing installation form definition method in the above packing sealing field, the present invention proposes a valve V-shaped packing structure and installation form definition method based on dimensionless function, using the packing key variable structural parameter c 1 and c 2 The packing installation form function and the packing structure function are constructed respectively, so as to obtain the definition function of the valve V-shaped packing structure and installation form based on the dimensionless function. The positive and negative signs of the definition function are used to define the forward and reverse installation forms, and the value of the definition function is used to define the specific structure of the packing, thus realizing the simultaneous definition of the packing structure and the installation form by one function.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for defining a valve V-shaped packing structure and installation form based on a dimensionless function can be used for defining a V-shaped packing structure and installation form. The method mainly refers to a definition function for a valve V-shaped packing structure and installation form based on a dimensionless function proposed in the present invention. The definition function consists of two parts, one for the packing installation form function and the other for the packing structure function. First, the basic structural parameters of the V-shaped packing are selected, and the shoulder angle c of the key variable structural parameter of the V-shaped packing is selected. 1 and c 2 , specify the forward installation and reverse installation forms; analyze the shoulder angle c when forward installation and reverse installation forms 1 and c 2 The relationship between the difference function and the value of c is defined. 1 and c 2 The size relationship; the sign function is used to select the positive and negative signs of the difference function. The function takes 1 when installed in the forward direction and takes -1 when installed in the reverse direction. This function is used to define the packing installation form; the shoulder angle difference function Δ is defined as the shoulder angle c 1 and c 2 The difference between the larger and smaller values ​​in the equation; define the maximum difference function κ(c 1 ,c 2 ) is 1 and the shoulder angle c 1 、c 2 The difference between the ratio of the smaller value and the larger value is used to define the packing structure; define the dimensionless function is sign[λ(c 1 ,c 2 )] function and κ(c 1 ,c 2 ) functions to simultaneously define the packing structure and installation form; simultaneous dimensionless functions and shoulder angle difference function Δ, solve for the shoulder angle c 1 and c 2 The corresponding packing structure and installation form are obtained by the value of. The details are as follows:

[0008] The installation form function can be expressed as follows:

[0009] Step S1: The valve packing sealing structure is used to seal the gap between the valve stem 6 and the valve body 4. The schematic diagram of the valve packing sealing structure is shown in Figures 1 and 2. The packing gland 3 is connected to the valve body 4 through the stud 2 and the pre-tightening nut 1. Tightening the pre-tightening nut 1 downward can apply a pre-tightening force to the packing through the packing gland 3. Under the action of the pre-tightening force, the packing is deformed toward the valve stem 6 and the inner side of the valve body 4, thereby generating a certain contact pressure on the contact surface. When the contact pressure is greater than the pressure of the liquid medium sealed by the packing, it can play a sealing role.

[0010] Step S2: define the basic structural parameters of the filler, the filler is a V-shaped filler, and the cross-sectional shape of the V-shaped filler is as follows: Figure 3 , Figure 4 As shown, Figure 3 For forward installation, Figure 4 For reverse installation, the two have the same structure; the basic structural parameters of the V-shaped packing are: shoulder angle c 1 and shoulder angle c 2 , side height H and width D, c 1 and c 2 It is always defined as the angle less than 180° formed by the shoulders on both sides of the packing. Once the valve body and valve stem 6 are selected and checked, the parameters of the horizontal width D and the side height H are not easy to change. 1 and shoulder angle c 2 As the main structural variable, in order to ensure good contact between the packing and transmit the axial preload, the convex shoulder angle must be greater than the concave shoulder angle: Figure 3 In the middle, when the shoulder angle c 2 is the shoulder angle, shoulder angle c 1 The concave shoulder angle is used to define the positive installation of stacked packing, as shown in Figure 1. Figure 4 In the middle, when the shoulder angle c 1 is the shoulder angle, shoulder angle c 2 The concave shoulder angle is used to define the installation of stacked packings in this shape as reverse installation, as shown in Figure 2.

[0011] Step S21: For the same packing structure, only the installation form is different when installing in the forward direction and in the reverse direction, and the packing structure is exactly the same. 2 >c 1 , when installed in reverse, there is c 2 <c 1 , define λ(c 1 ,c 2 ) is 1 and c 1 and c 2 The difference in ratios can be expressed as follows:

[0012]

[0013] Step S22: The concepts of "positive sign" and "negative sign" are used to express the "positive" and "reverse" installation forms, that is, "positive sign" represents "positive installation" and "negative sign" represents "reverse installation", so the sign function can be used to express the "positive" and "negative" problems. The expression is as follows:

[0014]

[0015] Step S23: In formula 2, sign[λ(c 1 ,c 2)] is a sign function, which takes the sign of the variable, that is, when the variable of the sign function is positive, it takes 1 (positive sign), and when the difference is negative, it takes -1 (negative sign). The variable here is λ(c 1 ,c 2 ). That is, the “positive sign” and “negative sign” are used to represent “forward installation” and “reverse installation” respectively.

[0016] The filler structure function can be expressed as follows:

[0017] Step S3: For the same installation form (forward installation or reverse installation) of different types of fillers, it is necessary to define the structure of each filler. First, the shoulder angle difference function Δ is defined, where Δ is the difference between the two shoulder angles c 1 、c 2 The difference between the larger and smaller values ​​in can be expressed as follows:

[0018] Δ=max(c 1 ,c 2 )-min(c 1 ,c 2 )(3)

[0019] Step S31: The packing structure is formed by the shoulder angle c 1 and shoulder angle c 2 Joint decision, different c 1 and c 2 The combination of is different packing structure, that is, c 1 and c 2 To express the filler structure, we need to find a c 1 and c 2 The combination of Δ and Δ defines a formula that expresses different packing structures when different values ​​are taken. When Δ takes a fixed value, it means that the difference between the larger and smaller values ​​of the two shoulder angles remains unchanged. When the two angles change but the difference between the two angles remains unchanged, the ratio of the two angles is a variable, and c can be used. 1 and c 2 The ratio form indicates different packing structures. 1 and c 2 After selection, there is c in forward installation 2 >c 1 , when installed in reverse, there is c 2 <c 1 Therefore, the formula defining the packing structure can be expressed as:

[0020]

[0021] Step S4: Combining the packing installation form function and the packing structure function together to obtain a definition function of the valve V-shaped packing structure and installation form based on a dimensionless function, which can be expressed as follows:

[0022]

[0023] Step S5: This function consists of two parts, Used to determine the installation form. A positive value indicates forward installation, and a negative value indicates reverse installation. This part is dimensionless. Used to define the packing structure, the specific structure is determined by c 1 and c 2 The value of is determined by this part, which is dimensionless. That is, the dimensionless function is defined as is sign[λ(c 1 ,c 2 )] function and κ(c 1 ,c 2 ) functions to simultaneously define the packing structure and installation form; simultaneous dimensionless functions and shoulder angle difference function Δ, solve for the shoulder angle c 1 and c 2 The corresponding packing structure and installation form can be obtained by using the value of

[0024] The above definition method can realize the simultaneous definition of packing structure and installation form, and can also realize the definition of shoulder angle c 1 and c 2 The definition when the two change simultaneously and the difference relationship is considered provides a new method for defining the packing structure and the installation form.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) In the field of packing sealing, the commonly used V-shaped packing structure is designed according to experience. So far, there is no suitable method for defining the packing structure, nor is there a method for defining the packing installation form. The definition method proposed in the present invention is simple and clear, and provides technical support for the design, analysis and optimization of the packing structure.

[0027] (2) In the field of packing sealing, when analyzing the influence of packing structural parameters on packing sealing performance, the fixed variable method is used for research, that is, analyzing the change of packing sealing performance when a certain structural parameter changes while other structural parameters are fixed, but the change of packing sealing performance when multiple structural parameters change simultaneously is not considered, and it is impossible to define the packing structure when multiple structural parameters change. On the one hand, the definition method proposed in the present invention takes into account the two key parameters that affect the packing structure at the same time, and can define the packing structure when these two parameters change simultaneously. On the other hand, the shoulder angle difference function Δ is used to take into account the influence of the difference between the two parameters on the packing sealing performance, providing a new definition method under the simultaneous change of two parameters.

[0028] (3) In the field of packing sealing, when analyzing the packing sealing performance, it is necessary to consider both the structure of the packing and the influence of the installation form of the packing on the packing sealing performance. Therefore, it is necessary to explore the sealing performance of packings with different structures under different installation forms. The definition method of the valve V-shaped packing structure and installation form based on the dimensionless function proposed in the present invention takes into account both the packing structure and the installation form. Only the above-mentioned dimensionless function can be used to realize the simultaneous definition of the packing structure and the installation form. This definition method appears for the first time in the field of packing sealing. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1(a) is a schematic diagram of the valve packing seal (forward installation) structure, and Figure 1(b) is a partial enlarged schematic diagram of the packing seal (forward installation). In the figure: 1 is a pre-tightening nut, 2 is a stud, 3 is a packing gland, 4 is a valve body, 5 is a forward-installed V-shaped packing, and 6 is a valve stem.

[0030] Figure 2(a) is a schematic diagram of the valve packing seal (reverse installation) structure, and Figure 2(b) is a partial enlarged schematic diagram of the packing seal (reverse installation). In the figure: 1 is a pre-tightening nut, 2 is a stud, 3 is a packing gland, 4 is a valve body, 5 is a reverse installed V-shaped packing, and 6 is a valve stem.

[0031] Figure 3 This is the cross-sectional structure diagram of the forward-mounted V-shaped packing. 1 is the concave shoulder angle, c 2 is the shoulder angle, D is the horizontal width, and H is the side height.

[0032] Figure 4 This is the cross-sectional structure diagram of the reverse installed V-shaped packing. 1 is the shoulder angle, c 2 is the concave shoulder angle, D is the horizontal width, and H is the side height.

[0033] Figure 5 The different shoulder angle difference functions Δ and different dimensionless functions constructed by the definition method designed by the present invention are Various forward-mounted packing structures for various situations.

[0034] Figure 6 The different shoulder angle difference functions Δ and different dimensionless functions constructed by the definition method designed by the present invention are Various reverse installed packing structures in various situations. Specific implementation methods

[0035] The technical solution of the present invention will be further described below in conjunction with specific embodiments and drawings.

[0036] A method for defining a valve V-shaped packing structure and installation form based on a dimensionless function, the steps are as follows:

[0037] Step S1: The valve packing sealing structure is used to seal the gap between the valve stem 6 and the valve body 4. The schematic diagram of the valve packing sealing structure is shown in Figures 1 and 2. The packing gland 3 is connected to the valve body 4 through the stud 2 and the pre-tightening nut 1. Tightening the pre-tightening nut 1 downward can apply a pre-tightening force to the packing through the packing gland 3. Under the action of the pre-tightening force, the packing is deformed toward the valve stem 6 and the inner side of the valve body 4, thereby generating a certain contact pressure on the contact surface. When the contact pressure is greater than the medium pressure, it can play a sealing role.

[0038] Step S2: define the basic structural parameters of the packing, the cross-sectional shape of the V-shaped packing is as follows: Figure 3-Figure 4 As shown, the basic structural parameter is the shoulder angle c 1 and shoulder angle c 2 , side height H and width D, c 1 and c 2 It is always defined as the angle less than 180° formed by the shoulders on both sides of the packing. Once the stuffing box and valve stem are selected and checked, the horizontal width D and side height H parameters are not easy to change. 1 and shoulder angle c 2 As the main structural variable, in order to ensure good contact between the packing and transmit the axial preload, the convex shoulder angle must be greater than the concave shoulder angle. Figure 3 Medium 2 is the shoulder angle, c 1 The concave shoulder angle is used to define the positive installation of stacked packing, as shown in Figure 1. Figure 4 In, c 1 is the shoulder angle, c 2 The concave shoulder angle is used to define the installation of stacked packings in this shape as reverse installation, as shown in Figure 2.

[0039] Step S21: For the same packing structure, only the installation form is different when installing in the forward direction and in the reverse direction, and the packing structure is exactly the same. 2 >c 1 , when installed in reverse, there is c 2 <c 1 , define λ(c 1 ,c 2 ) is 1 and c 1 and c 2 The difference in ratios can be expressed as follows:

[0040]

[0041] Step S22: The concepts of "positive sign" and "negative sign" are used to express the "positive" and "reverse" installation forms, that is, "positive sign" represents "positive installation" and "negative sign" represents "reverse installation", so the sign function can be used to express the "positive" and "negative" problems. The expression is as follows:

[0042]

[0043] Step S23: In formula 2, sign[λ(c 1 ,c 2 )] is a sign function, which takes the sign of the variable, that is, when the variable of the sign function is positive, it takes 1 (positive sign), and when the difference is negative, it takes -1 (negative sign). The variable here is λ(c 1 ,c 2 ). That is, the “positive sign” and “negative sign” are used to represent “forward installation” and “reverse installation” respectively.

[0044] The packing structure function can be expressed as follows:

[0045] Step S3: For the same installation form (forward installation or reverse installation) of different types of fillers, it is necessary to define the structure of each filler. First, the shoulder angle difference function Δ is defined. Δ is the difference between the larger and smaller values ​​of the two shoulder angles, which can be expressed as follows:

[0046] Δ=max(c 1 ,c 2 )-min(c 1 ,c 2 )(8)

[0047] Step S31: The packing structure is formed by the shoulder angle c 1 and shoulder angle c 2 Joint decision, different c 1 and c 2 The combination of is different packing structure, that is, c 1 and c 2 To express the filler structure, we need to find a c 1 and c 2 The combination of Δ and Δ defines a formula that expresses different packing structures when different values ​​are taken. When Δ takes a fixed value, it means that the difference between the larger and smaller values ​​of the two shoulder angles remains unchanged. When the two angles change but the difference between the two angles remains unchanged, the ratio of the two angles is a variable, and c can be used. 1 and c 2 The ratio form indicates different packing structures. 1 and c 2 After selection, there is c in forward installation 2 >c 1 , when installed in reverse, there is c 2 <c 1 Therefore, the formula defining the packing structure can be expressed as:

[0048]

[0049] Step S4: Combining the packing installation form function and the packing structure function together to obtain a definition function of the valve V-shaped packing structure and installation form based on a dimensionless function, which can be expressed as follows:

[0050]

[0051] Step S5: The dimensionless function consists of two parts: Used to determine the installation form. A positive value indicates forward installation, and a negative value indicates reverse installation. This part is dimensionless. Used to define the packing structure, the specific structure is determined by c 1 and c 2 This part is dimensionless.

[0052] Step S6: Determine c 1 and c 2 The unique dimensionless function can be determined by the value and installation form of Combining equations 8 and 10, we can see that when determining Δ and After that, the corresponding unique packing structure and installation form can be derived.

[0053] Step S7: When installing in the forward direction, Δ and They can be defined as:

[0054]

[0055] Step S8: When installing in reverse, Δ and They can be defined as:

[0056]

[0057] Step S9: Solving equations (11) and (12) to obtain the shoulder angle c for forward installation and reverse installation 1 and c 2 expression.

[0058] Step S10: Shoulder angle c during forward installation 1 and c 2 It can be expressed as follows:

[0059]

[0060] Step S11: Shoulder angle c when installing in reverse 1 and c 2 It can be expressed as follows:

[0061]

[0062] Step S12: According to equations 13 and 14, Δ and c1 and c 2 The corresponding packing structure and installation form can be obtained by the value of . When Δ=10°, 15° and 20°, different The packing structure and installation form under the value condition are as follows Figure 5 and Figure 6 shown.

[0063] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for defining a valve V-shaped packing structure and installation form based on a dimensionless function, characterized in that: The described definition method mainly refers to the definition function of the V-shaped packing structure and installation form of the valve based on dimensionless functions. This definition function consists of two parts. One part is the packing installation form function, and the other part is the packing structure function; First, select the basic structure parameters of the V-shaped packing, and select the key variable structure parameters of the V-shaped packing, the shoulder angles c1 and c2, and specify the forward installation and reverse installation forms; analyze the relationship between the shoulder angles c1 and c2 in the forward installation and reverse installation forms, and define a difference function to judge the size relationship between c1 and c2; use the sign function to select the positive and negative signs of the difference function. This function takes 1 when installed forward and -1 when installed backward. This function is used to define the packing installation form; Secondly, define the shoulder angle difference function Δ as the difference between the larger value and the smaller value of the shoulder angles c1 and c2; define the maximum-minimum difference function κ(c1, c2) as the difference between 1 and the ratio of the smaller value to the larger value of the shoulder angles c1 and c2. This function is used to define the packing structure; Finally, define the dimensionless function It is the product of the sign[λ(c1,c2)] function and the κ(c1,c2) ​​function, which is used to define the packing structure and installation form at the same time; the dimensionless function And the shoulder angle difference function Δ, solve the values ​​of the shoulder angles c1 and c2, and get the corresponding packing structure and the corresponding installation form.

2. A method for defining a valve V-shaped packing structure and installation form based on a dimensionless function according to claim 1, characterized in that: Specifically as follows: The described installation form function is expressed as follows: Step S1: The valve packing seal structure is used to seal the gap between the valve stem 6 and the valve body 4. The packing gland 3 is connected to the valve body 4 through the stud 2 and the pre-tightening nut 1. By turning the pre-tightening nut 1 downward, a pre-tightening force is applied to the packing through the packing gland 3. Under the action of the pre-tightening force, the packing deforms toward the valve stem 6 side and the valve body 4 inner side, and a contact pressure is generated on the contact surface. When the contact pressure is greater than the pressure of the liquid medium sealed by the packing, it plays a sealing role; Step S2: Define the basic structure parameters of the packing. The described packing is a V-shaped packing, and the forward installation and reverse installation structures are the same; the basic structure parameters of the V-shaped packing are: shoulder angle c1 and shoulder angle c2, side height H and transverse width D. c1 and c2 are always defined as the angles less than 180° formed by the shoulders on both sides of the packing; the shoulder angles c1 and c2 are the main structure variables. To ensure good contact of the packing and transfer the axial pre-tightening force, it is specified that the convex shoulder angle must be greater than the concave shoulder angle; The described packing structure function is expressed as follows: Step S3: For the same installation form of different types of packings, it is necessary to define the structure of each packing. First, define the shoulder angle difference function Δ. Δ is the difference between the larger value and the smaller value of the two shoulder angles c1 and c2, and is expressed as follows: Δ = max(c1, c2) - min(c1, c2) (3) Step S31: The packing structure is jointly determined by the shoulder angles c1 and c2; when Δ takes a certain fixed value, it means that the difference between the larger value and the smaller value of the two shoulder angles always remains unchanged. When the two angles change but the difference between the two angles remains unchanged, the ratio of the two angles is a variable. Therefore, different packing structures can be expressed in the form of the ratio of c1 and c2; when c1 and c2 are selected, c2 > c1 in the forward installation and c2 < c1 in the reverse installation; therefore, the formula for defining the packing structure can be expressed as: Step S4: Combine the packing installation form function and the packing structure function to obtain the definition function of the V-shaped packing structure and installation form of the valve based on dimensionless functions, and it is expressed as follows: This function consists of two parts Composed of: Used to determine the installation form. If it is a positive value, it means forward installation. If it is a negative value, it means reverse installation. This part is dimensionless. Used to define the packing structure. The specific structure is determined by the values ​​of c1 and c2. This part is dimensionless. Simultaneous dimensionless functions And the shoulder angle difference function Δ, solve the values ​​of the shoulder angles c1 and c2, and get the corresponding packing structure and the corresponding installation form.

3. A method for defining a valve V-shaped packing structure and installation form based on a dimensionless function according to claim 2, characterized in that: In the described step S2: Step S21: For the same packing structure, only the installation form is different when installed forward and backward, and the packing structure is exactly the same. Since it is specified that the convex shoulder angle is greater than the concave shoulder angle, that is, c2 > c1 when installed forward and c2 < c1 when installed backward. Define λ(c1, c2) as the difference between 1 and the ratio of c1 and c2, which is expressed as follows: Step S22: Use the "plus sign" and "minus sign" to represent the "forward" and "backward" installation forms, that is, the "plus sign" represents "forward installation" and the "minus sign" represents "backward installation". Therefore, the sign function can be used to represent the "plus sign" and "minus sign" problems. The expression is as follows: Step S23: In Equation 2, sign[λ(c1, c2)] is the sign function, which takes the sign of the variable. That is, when the variable of the sign function is a plus sign, it takes 1, and when the difference is a minus sign, it takes -1. Here, the variable is λ(c1, c2).

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