Machining method of strong-sealing energy-saving type butterfly valve plate

Abstract

The invention provides a machining method for a strong-sealing energy-saving type butterfly valve plate, and relates to the technical field of butterfly valve structure machining. A valve plate raw material is subjected to one-time machining to form a valve plate body; a plurality of parallel grooves are directly formed in the peripheral surface of the valve plate body through machining; filling the grooves in the top area and the bottom area of the valve plate body, and drilling a middle shaft part area of the valve plate body to form a through hole; a plurality of concentric circular grooves are formed in the top area and the bottom area of the valve plate body; the sealing strips are embedded in the grooves, the sealing rings are embedded in the circular grooves, a sealing structure is formed, and on the premise that the high sealing performance is guaranteed, the using amount of sealant is reduced, and the cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of butterfly valve structure processing, and in particular to a processing method for a valve plate of a strongly sealed and energy-saving butterfly valve. Background Art

[0002] Valves are common control components in pipeline fluid delivery systems, which play the role of opening and closing, controlling flow direction, and adjusting the parameters of the conveying medium. The valve mainly includes a valve body, a valve seat, a valve core, and a drive assembly. The valve seat is set inside the valve body to support the fully closed position of the valve core and form a sealing pair. The drive assembly is used to control the opening and closing of the valve core. Common valve types include ball valves, butterfly valves, diaphragm valves, gate valves, check valves, etc. Among them, the butterfly valve, that is, the valve core is a circular butterfly plate, which is opened and closed by rotating with the valve stem as the axis.

[0003] The most important technical performance indicator of a valve is its sealing performance, which refers to the ability of each sealing part of the valve to prevent leakage of the medium. The contact between the valve seat and the valve core is one of the sealing parts of the valve. The contact between the valve seat and the valve core of an ordinary butterfly valve is generally a one-way sealing structure, which has a sealing effect when under positive pressure, but is prone to medium leakage when under reverse pressure.

[0004] In the field of valve design, especially centerline clamp, clamp and lug fire butterfly valves, among which the centerline fire butterfly valves with valve body cavity sealing surface sprayed and valve plate rubber coated, the existing valve body sealing pair designs mainly have two shapes: 1. The inner cavity diameter sealing belt adopts a cylindrical plane sealing surface shape. 2. The inner cavity diameter sealing belt adopts a spherical shape; The valve plate also has two types of sealing: 1. The valve plate adopts the combined shape design of end cut and single waterline. 2. The valve plate adopts a spherical shape design.

[0005] The sealing of the center line butterfly valve is mainly achieved by the interference fit between the butterfly plate and the rubber valve seat, relying on the elasticity of the rubber. The above technology is the design structure most commonly used by domestic center line rubber sealing butterfly valve manufacturers. It has a simple structure and low product cost. However, due to the high sealing requirements of the butterfly valve, the sealing pressure is more than twice the design pressure. In particular, the international UL / FM fire butterfly valve certification requires strict high-pressure life sealing tests. In the sealing pair design of the valve plate and the valve body in the prior art, the interference is increased, especially at the ends of the upper and lower shaft holes of the valve plate to ensure the sealing in the high-pressure test. In actual use and certification tests, leakage is prone to occur at the ends of the upper and lower shafts of the valve plate and leakage caused by fatigue aging of the rubber seals on both sides, thereby reducing the sealing effect of the butterfly valve and shortening the service life of the butterfly valve product.

[0006] At present, butterfly valves are used to adjust flow, cut off or connect fluids in pipelines with different media. They are mainly composed of valve plate assembly, valve body assembly and bottom cover assembly. The seal between the sealing surface of the valve plate and the valve seat is achieved by the torque of the transmission device to press the valve plate against the valve seat. In the positive flow state, the higher the medium pressure, the tighter the seal is squeezed. When the flow channel medium flows in reverse, as the medium pressure increases, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, and the seal begins to leak. Due to the limitation of structural conditions, this structure is not suitable for valves with a diameter below DN100, because the overall structure of the valve plate is too thick and the flow resistance is large.

[0007] In summary, the current center line fire butterfly valve has certain defects in the design of the sealing pair of the valve plate and valve body, mainly because the sealing interference design of the valve plate rubber is large, resulting in insufficient life of the valve plate. The existing butterfly valve has high production costs, is difficult to repair leakage, the sealing structure is easy to wear, and has a large opening torque. Summary of the invention

[0008] In order to solve the above technical problems, the present invention proposes a method for processing a strong-seal energy-saving butterfly valve plate, comprising the following steps: Step 1: Process the valve plate raw material once to form the valve plate body; determine the size and shape of the valve plate body in the 2D drawing, and process the valve plate raw material into the valve plate body by casting, forging, and milling, wherein the two side surfaces of the valve plate body are arc surfaces protruding outward in the middle shaft area; fix the valve plate body on the fixture of the lathe, ensure that the workpiece is concentric with the lathe spindle, and process the outer periphery of the valve plate body into a curved surface by a tool; Step 2: Use a lathe to directly process a plurality of parallel grooves on the outer peripheral surface of the valve plate body, each groove is continuous, and the cross-sectional shape of the groove is wide inside and narrow outside; Step 3: Fill the grooves in the top and bottom areas of the valve plate body, and drill holes in the middle shaft area of ​​the valve plate body to form through holes; Step 4: Processing a plurality of concentric circular grooves on the top and bottom areas of the valve plate body; the cross-sectional shape of the grooves is wide inside and narrow outside; Step 5: embed sealing strips in the multiple grooves, embed sealing rings in the multiple circular grooves, and the sealing strips and sealing rings form a sealing structure.

[0009] Furthermore, a plurality of sealing rings and a plurality of grooves form a top-bottom sealing structure, and the mathematical expression of the actual sealing pressure q2 of the top-bottom sealing structure is: , Wherein: C and K are constants, which are determined based on empirical values; B is the thickness of a circular sealing ring; and n is the number of circular sealing rings.

[0010] Furthermore, a plurality of sealing strips and a plurality of grooves form a side sealing structure, and the mathematical expression of the actual sealing pressure q1 of the side sealing structure is: , Where: C and K are constants, determined based on empirical values, b is the thickness of a single sealing strip, N is the number of sealing strips, and δ is the sealing coefficient.

[0011] Furthermore, the valve plate thickness H satisfies the following relationship: , Q is the flow rate of the fluid that impacts the valve plate per unit time, P is the fluid pressure on the valve plate, ρ is the density of the fluid medium, g is the acceleration of gravity, and μ is the resistance coefficient of the valve plate.

[0012] Furthermore, in step one, the valve plate body is formed into the valve plate body through one-time processing, and the outer contour of the valve plate body is circular.

[0013] Furthermore, the cross-sectional shapes of the grooves and recesses are both wide inside and narrow outside.

[0014] Furthermore, the plurality of sealing strips and the plurality of sealing rings are an integrated structure, and are integrally embedded in the grooves and circular grooves after the grooves and circular grooves are processed.

[0015] Furthermore, in step three, the radius R of the filling area is larger than the inner wall radius R2 of the outermost circular groove, and smaller than the outer wall radius R1 of the outermost circular groove.

[0016] Furthermore, the radial height of the sealing strip is higher than the depth of the groove, and the axial height of the sealing ring is higher than the height of the circular groove.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: The valve body of a conventional butterfly valve is usually entirely rubber-coated, but the present invention eliminates the conventional soft-sealing valve seat structure provided on the inner wall of the valve body; the structure is simplified, costs are saved, and there is no friction between the butterfly plate and the valve seat sealing surface on the valve body during opening and closing, which reduces the wear of the sealing pair and improves the sealing performance.

[0018] A multi-layer sealing structure is arranged axially on the circumferential surface of the butterfly plate of the butterfly valve to improve the sealing performance. A petal-shaped sealant structure is directly arranged on the valve plate, with the petals being high in the middle and low on both sides.

[0019] The present invention directly processes grooves and protrusions on the valve plate, and sets sealant in the grooves. The shape of the grooves is narrow inside and wide outside to prevent the sealant from flowing out or falling off. The multi-pass seal can buffer the impact of the fluid on the valve plate and extend the service life. Under the premise of ensuring the sealing performance, the amount of sealant used is reduced and the cost is reduced. The specific shape of the groove is set to reduce the deposition of impurities in the groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0021] Figure 1 It is a flow chart of the method for processing the valve plate of the strong-seal energy-saving butterfly valve of the present invention; Figure 2 A schematic diagram of the structure of the valve plate body formed by one-time processing of the present invention; Figure 3 Schematic diagram of the valve plate diameter D1, the intermediate shaft portion outer diameter D2 and the valve plate thickness H; Figure 4 A schematic diagram of a plurality of parallel grooves formed on the outer peripheral surface of the valve plate body; Figure 5 is a schematic diagram of the groove cross section; Figure 6 A schematic diagram of the trench filling and through-hole status in the top and bottom regions; Figure 7 A schematic diagram of a plurality of circular grooves formed by machining the top and bottom areas of the valve plate body; Figure 8 Schematic diagram of the inner wall radius R2 and the outer wall radius R1 of the outermost circular groove; Fig. 9 Schematic diagram of the state after the sealing strip is embedded in the groove and recess. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] In the drawings of the specific embodiments of the present invention, in order to better and more clearly describe the working principles of the various components in the system, the connection relationship of the various parts in the device is shown, which only clearly divides the relative position relationship between the various components, and cannot constitute a limitation on the signal transmission direction, connection sequence and size, dimensions and shape of the components or structures.

[0024] like Figure 1FIG. 1 is a flow chart of a method for processing a strong-seal energy-saving butterfly valve plate of the present invention, comprising the following steps: Step 1: Process the valve plate raw material once to form the valve plate body.

[0025] Determine the size and shape of the valve plate body in the 2D drawing, and process the valve plate raw material into the valve plate body through casting, forging, milling machine and other processing methods. The two sides of the valve plate body are arc surfaces that bulge outward in the middle shaft area. Fix the valve plate body on the fixture of the lathe to ensure that the workpiece is stable and concentric with the lathe spindle. Use the tool to process the periphery of the valve plate body into a curved surface with a certain amplitude, which is high in the middle and low on both sides.

[0026] like Figure 2 The figure shows a schematic diagram of the valve plate body structure formed by one-time processing. The upper and lower ends of the middle shaft area of ​​the valve plate body are defined as the top area and the bottom area of ​​the valve plate body. The top area and the bottom area of ​​the valve plate body are matched with the top and the bottom of the valve body respectively.

[0027] In this step, the valve plate body is formed into a valve plate body through one-time processing. The outer contour of the valve plate body is circular, and the top and bottom of the valve plate do not need to be processed into planes according to the prior art. This step of the present invention can reduce processing steps and reduce costs by directly forming the valve plate through one-time processing.

[0028] like Figure 3 FIG. 1 is a schematic diagram of the diameter D1 of the valve plate, the outer diameter D2 of the intermediate shaft portion, and the thickness H of the valve plate. In a preferred embodiment, the diameter D1 of the valve plate and the outer diameter D2 of the intermediate shaft portion satisfy the following relationship: , As the main moving part of the butterfly valve, the thickness of the valve plate directly affects the structural strength and pressure resistance of the butterfly valve. As the fluid pressure increases, the requirements for the valve plate will also increase accordingly to ensure that it can maintain a stable structure and performance under high pressure.

[0029] In a preferred embodiment, the thickness H of the valve plate satisfies the following relationship: , Q is the flow rate of the fluid that impacts the valve plate per unit time, P is the fluid pressure on the valve plate, ρ is the density of the fluid medium, g is the acceleration of gravity, and μ is the resistance coefficient of the valve plate.

[0030] Step 2: Directly process a plurality of parallel grooves on the outer peripheral surface of the valve plate body.

[0031] like Figure 4 As shown, a plurality of parallel grooves can be formed on the outer peripheral surface of the valve plate body by a lathe, and each groove is continuous. Preferably, during the processing, the tool is tilted at a certain angle, so that the cross-sectional shape of the groove is wide inside and narrow outside, such as Figure 5 As shown, in order to prevent the sealant from flowing out or falling off, the deposition of impurities in the groove can be reduced by reasonably setting the specific cross-sectional shape of the groove.

[0032] Step 3: Fill the grooves in the top and bottom areas of the valve plate body, and drill holes in the middle shaft area of ​​the valve plate body to form through holes.

[0033] The grooves in the top and bottom areas of the valve plate body are filled with the same material as the valve plate body, and the filling material is heated and welded to restore the top and bottom grooves to be flat. The upper and lower ends of the middle shaft area of ​​the valve plate body are drilled by lathe processing to form a hole coaxial with the middle shaft area. The final processing is completed as shown in FIG. Figure 6 shown.

[0034] It should be emphasized that filling the grooves in the top and bottom areas of the valve plate body first and then drilling can effectively ensure the smoothness of the inner wall of the through hole and reduce rotational friction. You can also drill the holes first and then fill them, but the filled material will overflow into the hole, and the inner wall of the hole still needs to be polished, which increases the processing steps and processing time.

[0035] Furthermore, in order to match the angular structure of the periphery of the driving rod, the inner surface of the lower end of the through hole in the middle shaft area has a small aperture in the area where the driving rod is inserted, and a large aperture in the area where the driving rod is not inserted, when the hole is processed on a lathe. A certain boss is formed at the junction of the area with large aperture and the area with small aperture. The boss is processed by a hydraulic punch to form a raised structure with equal spacing. Common raised structures may be four or six. The processed valve plate body is tested for matching with the driving rod to ensure that the raised structure matches the angular structure of the periphery of the driving rod to achieve the switching control of the valve.

[0036] The depth of the protruding structure is designed according to the rotational force of the driving rod to avoid the driving rod being inserted too deeply, resulting in waste of materials.

[0037] Step 4: Processing a plurality of concentric circular grooves on the top and bottom areas of the valve plate body.

[0038] FIG7 is a schematic diagram of multiple circular grooves formed in the top and bottom areas of the valve plate body by lathe processing or the like. The valve plate is clamped by an angle, so that the valve plate rotates around the middle shaft area, and the top or bottom grooves are processed by lathe tools. Preferably, the cross-sectional shape of the groove is wide inside and narrow outside to prevent the sealant from flowing out or falling off. By reasonably setting the cross-sectional shape of the groove, the deposition of impurities in the groove can be reduced.

[0039] In particular, the radius of the fill area must meet the following size requirements, such as Figure 8As shown, the radius R of the filling area is greater than the inner wall radius R2 of the outermost circular groove and smaller than the outer wall radius R1 of the outermost circular groove. Preferably: .

[0040] Step 5: Embed sealing strips in the plurality of grooves, embed sealing rings in the plurality of grooves, and the sealing strips and sealing rings form a sealing structure.

[0041] A plurality of sealing strips are embedded in the plurality of grooves, and the plurality of sealing strips and the plurality of grooves together form a sealing structure. The sealing strips have a radial height higher than a depth of the grooves and protrude outward from the outer peripheral surface of the valve plate body.

[0042] Similarly, multiple grooves in the top area and the bottom area are embedded with sealing rings, multiple sealing rings and multiple grooves form a top and bottom sealing structure, and multiple sealing strips and multiple grooves form a side sealing structure. The height of the sealing ring in the axial direction is higher than the height of the groove, and it protrudes outward from the outer peripheral surface of the valve plate body.

[0043] Preferably, the plurality of sealing strips and the plurality of sealing rings are an integrated structure, and after the grooves and recesses are processed, they are integrally embedded therein, thereby improving processing efficiency and sealing performance.

[0044] like Fig. 9 The figure shows the state after the sealing strip is embedded in the groove and the circular groove.

[0045] In a preferred embodiment, the number and depth of the sealing strips vary according to the different calibers of the valve plate, as well as the different fluid pressures and fluid densities. The thickness of the sealing strips and the number of sealing strips on the periphery of the valve plate are designed by calculating the sealing pressure. The sealing pressure refers to the force per unit area of ​​the sealing surface on the sealing structure of the butterfly valve, and is an important indicator for judging the sealing performance. In the closed state, the sealing surface on the sealing structure will exert a certain pressure on the inner circumference of the valve body to achieve the purpose of sealing. The sealing pressure of the butterfly valve is a key factor affecting the sealing performance of the valve. When designing the sealing structure of the butterfly valve, it is necessary to ensure that the actual sealing pressure q on the sealing surface is within the range defined by the following relationship to ensure that the sealing performance of the butterfly valve meets the requirements: q M ﹤q﹤q D ; Among them, the minimum sealing pressure is q M The pressure acting on the butterfly valve sealing surface is not the greater the better. If it is too large and exceeds the bearing range of the valve body or the sealing ring, it will cause irreversible wear to the valve body or the sealing structure, seriously affecting the sealing performance of subsequent use. Therefore, the maximum sealing pressure q is required. D To limit the maximum pressure value on the sealing surface, it can be obtained by looking up the material sealing pressure table.

[0046] The mathematical expression of the actual sealing pressure q1 of the side sealing structure is: , Where: C and K are constants, determined based on empirical values, b is the thickness of a single sealing strip, N is the number of sealing strips, δ is the sealing coefficient, and P is the fluid pressure on the valve plate.

[0047] In a preferred embodiment, the number and depth of the sealing rings are different according to different diameters of the valve plate, and according to different fluid pressures and fluid densities.

[0048] The mathematical expression of the actual sealing pressure q2 of the top and bottom sealing structure is: , Where: P is the fluid pressure on the valve plate, δ is the sealing coefficient, C and K are constants determined based on empirical values, B is the thickness of a circular sealing ring, and n is the number of circular sealing rings. Since a cross-sectional view is made from the direction of the water flow, one circle of sealing rings is equivalent to blocking the water flow twice, the width of the groove is doubled, and the number of sealing rings is also doubled. Therefore, in the formula, n and B in the denominator are multiplied by a multiple of 2. Since the materials of the sealing ring and the sealing strip are the same, the sealing coefficient δ remains unchanged.

[0049] Example 2 For the sealing method used for small sizes, after the valve plate body is formed in step 1, the first outer surface and the second outer surface on both sides of the valve plate body are coated with sealing materials to form the first sealing layer and the second sealing layer, and the outer periphery of the valve plate body is directly coated with glue, and a sealing structure consisting of multiple sealing strips and multiple sealing rings is directly hung on the outer periphery of the valve plate body. In this case, the sealing structure consists of a sealing structure and two sealing layers. By setting the sealing layer, the corrosion of the material by the fluid can be avoided, the surface of the valve plate can be protected, and the service life of the valve plate can be increased. The sealing layer and the sealing ring can be completed together through a one-time coating process, which reduces the processing steps and reduces the production cost.

[0050] In the actual design process, in addition to the pressure resistance, the fluid pressure will also affect the sealing performance of the butterfly valve. High fluid pressure will increase the contact stress between the valve plate and the valve seat, thereby improving the sealing effect. However, too high pressure may also cause the valve plate to deform or damage, thereby reducing the sealing performance. Therefore, when designing a butterfly valve, it is necessary to comprehensively consider the balance between fluid pressure and sealing performance.

[0051] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for processing a strong-seal energy-saving butterfly valve plate, characterized in that: The steps include: Step 1: Process the valve plate raw material once to form the valve plate body; determine the size and shape of the valve plate body in the 2D drawing, and process the valve plate raw material into the valve plate body by casting, forging, and milling, wherein the two side surfaces of the valve plate body are arc surfaces protruding outward in the middle shaft area; fix the valve plate body on the fixture of the lathe, ensure that the workpiece is concentric with the lathe spindle, and process the outer periphery of the valve plate body into a curved surface by a tool; Step 2: Use a lathe to directly process a plurality of parallel grooves on the outer peripheral surface of the valve plate body, each groove is continuous, and the cross-sectional shape of the groove is wide inside and narrow outside; Step 3: Fill the grooves in the top and bottom areas of the valve plate body, and drill holes in the middle shaft area of ​​the valve plate body to form through holes; Step 4: Form a plurality of concentric circular grooves on the top and bottom areas of the valve plate body, wherein the cross-sectional shape of the grooves is wide inside and narrow outside; Step 5: embed sealing strips in the multiple grooves, embed sealing rings in the multiple circular grooves, and the sealing strips and sealing rings form a sealing structure.

2. The method for processing the valve plate of a strong sealing energy-saving butterfly valve according to claim 1 is characterized in that: Multiple sealing rings and multiple grooves form a top-bottom sealing structure. The mathematical expression of the actual sealing pressure q2 of the top-bottom sealing structure is: ， Where: C and K are constants, determined based on empirical values, B is the thickness of a single circular seal ring, n is the number of circular seal rings, P is the fluid pressure on the valve plate, and δ is the sealing coefficient.

3. The method for processing a strong-seal energy-saving butterfly valve plate according to claim 1 is characterized in that: Multiple sealing strips and multiple grooves form a side sealing structure. The mathematical expression of the actual sealing pressure q1 of the side sealing structure is: ， Where: C and K are constants, determined based on empirical values, b is the thickness of a single sealing strip, N is the number of sealing strips, P is the fluid pressure on the valve plate, and δ is the sealing coefficient.

4. The method for processing a strong-seal energy-saving butterfly valve plate according to claim 1 is characterized in that: The valve plate thickness H satisfies the following relationship: ， Q is the flow rate of the fluid that impacts the valve plate per unit time, P is the fluid pressure on the valve plate, ρ is the density of the fluid medium, g is the acceleration of gravity, and μ is the resistance coefficient of the valve plate.

5. The method for processing a strong-seal energy-saving butterfly valve plate according to claim 1 is characterized in that: In the step 1, the valve plate body is formed by one-time processing, and the outer contour of the valve plate body is circular.

6. The method for processing a strong-seal energy-saving butterfly valve plate according to claim 1 is characterized in that: The plurality of sealing strips and the plurality of sealing rings are an integrated structure, and are integrally embedded in the grooves and the circular grooves after the grooves and the circular grooves are processed.

7. The method for processing a strong-seal energy-saving butterfly valve plate according to claim 1, characterized in that: In the step three, the radius R of the filling area is larger than the inner wall radius R2 of the outermost circular groove, and smaller than the outer wall radius R1 of the outermost circular groove.

8. The method for processing a strong-seal energy-saving butterfly valve plate according to claim 1, characterized in that: The radial height of the sealing strip is higher than the depth of the groove, and the axial height of the sealing ring is higher than the height of the circular groove.

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