Mechanical fastening method for valve plug with carbide tip
By employing a mechanically fixed structure for the plug base, spacer, and plug tip in the control valve, the problem of premature failure of the plug tip due to stress rise is solved, resulting in greater manufacturing convenience, component quality, and excellent performance over a wide temperature range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- EMERSON PROCESS MANAGEMENT TIANJIN VALVES
- Filing Date
- 2018-08-31
- Publication Date
- 2026-07-14
AI Technical Summary
Under harsh service conditions, the plug tip of a control valve is prone to premature failure due to increased stress. Existing technologies such as shrink fitting and brazing processes may lead to crack formation and vibration problems.
It adopts a combination structure of plug base, spacer and plug tip, and achieves mechanical fixation by headed screw. It combines appropriate materials such as carbide, tungsten carbide or ceramic materials, uses the conical shape of spacer and plug tip to fit in the center, and forms a stable mechanical connection by threading the headed screw with the plug base.
It improves manufacturing convenience and component quality, suppresses the development of internal stress, provides superior performance and lifespan over a wider temperature range, reduces manufacturing costs, and supports easier maintenance and retrofitting.
Smart Images
Figure CN109424749B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates generally to control valves, and more specifically to valve plugs having mechanically retaining tips such as carbide tips. Background Technology
[0002] In many control valve applications, particularly those involving harsh service conditions, the internal components of the control valve may be subjected to three-phase flow, which may include flashing, cavitation, and particles, all of which can potentially lead to severe corrosion and / or vibration. Therefore, such valves are typically equipped with a valve plug with a corrosion-resistant tip, which may be made of ceramic material, such as carbide, tungsten carbide, or other suitable materials.
[0003] In the construction of such valve components, the plug tip is typically attached to the plug base using a shrink-fit step, where the relevant components are heated, assembled, and then cooled. Alternatively, a brazing process can be used to attach the plug tip to the plug base. In either process, stress buildup may occur at the joint between the plug tip and the underlying base. This stress buildup can, and sometimes can, cause premature failure of the plug tip by leading to the formation and / or propagation of cracks in the plug tip. Summary of the Invention
[0004] According to a first exemplary aspect, a valve plug assembly is disclosed for use in a control valve having a valve stem, a flow passage, and a valve seat disposed in the flow passage. The valve plug assembly includes a plug base defining a longitudinal axis and having a first end and a second end. The first end of the plug base is arranged for attachment to the valve stem of the control valve, and the second end of the plug base includes a bore extending along the longitudinal axis, the bore including a first portion extending into the plug base by a first distance, and a second portion extending into the plug base by a second distance less than the first distance. The first portion of the bore has a first diameter, the second portion of the bore has a second diameter greater than the first diameter, and the second portion of the bore extends from the second end of the plug base to a tapered end, wherein the tapered end forms a first seat. A spacer includes a through-hole, a first end, and a second end, the spacer being sized to be inserted into the second portion of the bore of the plug base. The first end of the spacer has a tapered shape arranged to engage with the first seat, and the second end of the spacer has a tapered end forming a second seat. The plug tip includes a through-hole and a first end having a tapered shape arranged to engage with a second seat of a spacer, and also includes a second end shaped to engage with a valve seat of a valve. A headed screw is sized to be inserted through the through-hole of the plug tip and the spacer, and is arranged to thread into a first portion of a hole in the plug base, such that the headed screw mechanically secures the plug tip to the plug base.
[0005] According to a second exemplary aspect, a method of forming a valve plug assembly for use in a control valve, the control valve having a valve stem, a flow passage, and a valve seat, the method comprising providing a plug base defining a longitudinal axis and having a first end and a second end, the first end of the plug base being disposed for attachment to a valve stem of the control valve, and providing a hole extending along the longitudinal axis to the second end of the plug base, the hole including a first portion extending into the plug base by a first distance, and a second portion extending into the plug base by a second distance less than the first distance. The method includes providing a first diameter for the first portion of the hole and providing a second diameter for the second portion of the hole greater than the first diameter, providing a first forming seat for the second portion of the hole extending from the second end of the plug base, and providing a spacer having a through hole, a first end, and a second end, the spacer being sized to be inserted into the second portion of the hole of the plug base, the first end of the spacer having a forming portion to mate with the first forming seat, and providing a second forming seat to the second end of the spacer. The method further includes providing a plug tip having a through hole, a first end having a tapered shape arranged to engage with a second forming seat, and a second end formed to engage with a valve seat of a valve, and providing a headed screw sized to be inserted through the through hole of the plug tip and the spacer, and the headed screw being arranged to be threaded into a first portion of a hole in the plug base, thereby mechanically securing the plug tip to the plug base.
[0006] According to a third exemplary aspect, a valve plug assembly for use in a control valve, the control valve having a valve stem, a flow passage, and a valve seat disposed in the flow passage, the valve plug assembly includes a plug base defining a longitudinal axis and having a first end and a second end, the first end of the plug base being arranged for attachment to the valve stem of the control valve, the second end of the plug base having a bore extending along the longitudinal axis, the bore including a first portion extending into the plug base by a first distance, and a second portion extending into the plug base by a second distance less than the first distance, the inner end of the second portion of the bore terminating in a first shaped seat, and a spacer having a through hole, a first end, and a second end, the spacer being sized to be inserted into the second portion of the bore of the plug base, the first end of the spacer having a shaped end for engaging with the first shaped seat, and the second end of the spacer having a second shaped seat. A plug tip has a through hole, a first end, and a second end, the first end being shaped and arranged to engage with the second shaped seat, and the second end being shaped to engage with the valve seat of the valve. The headed screw is sized to be inserted through a hole passing through the plug tip and the spacer. The headed screw is arranged to engage with the first part of the hole in the plug base, and the headed screw secures the plug tip to the plug base.
[0007] Furthermore, according to the foregoing first and / or second aspects, the valve plug assembly and / or method may also include any one or more of the following preferred forms.
[0008] According to a preferred embodiment, the plug base includes a side hole sized to receive a pin, wherein the pin engages internally with a headed screw.
[0009] According to another preferred embodiment, the tip of the plug may comprise a carbide or a tungsten carbide or ceramic material.
[0010] According to another preferred embodiment, the plug tip may include a countersunk hole, and the headed screw may include a screw head sized to fit within the countersunk hole.
[0011] According to another preferred embodiment, the tapered shape of the spacer and the first seat mate to center the spacer relative to the longitudinal axis, and the tapered shape of the plug tip and the second seat mate to center the plug tip relative to the longitudinal axis.
[0012] According to another preferred embodiment, the seat and the plug tip can be suitably shaped such that the shaped portion of the spacer mates with the first seat to center the spacer relative to the longitudinal axis, and the shaped portion of the plug tip mates with the second seat to center the plug tip relative to the longitudinal axis.
[0013] According to another preferred embodiment, the shaped end of the spacer and the first seat cooperate to center the spacer relative to the longitudinal axis, and the shaped first end of the plug tip and the second shaped seat cooperate to center the plug tip relative to the longitudinal axis. Attached Figure Description
[0014] Figure 1 This is a cross-sectional view of a control valve with a plug assembly assembled according to the teachings of the first disclosed example of the present invention.
[0015] Figure 2 This is a partial cross-sectional enlarged view of a traditional plug with a carbide tip, showing details of the traditional cold-shrink fitting design.
[0016] Figure 3 This is an enlarged cross-sectional view of a valve plug with a carbide tip assembled according to an exemplary aspect of the present invention. Detailed Implementation
[0017] Although the following text sets forth a detailed description of one or more exemplary embodiments of the invention, it should be understood that the legal scope of the invention is defined by the words of the claims set forth at the end of this patent. Therefore, the following detailed description is to be interpreted as exemplary only and does not describe every possible embodiment of the invention, as describing every possible embodiment would be impractical, if not impossible. Many alternative embodiments can be implemented using current technology or technology developed after the date of this patent application. It is contemplated that these alternative embodiments will still fall within the scope of the invention as defined by the claims.
[0018] Now refer to the attached diagram, Figure 1 A valve plug assembly 10, assembled according to an exemplary embodiment of the invention, is shown for use in a control valve 12 having a valve stem 14, a flow passage 16, and a valve seat 18. Those skilled in the art will readily understand that the control valve 12 includes an inlet 15 and an outlet 17 connected via the flow passage 16. The valve plug assembly 10 is connected to the valve stem 14 and is movable between an open position and a closed position by any suitable actuator (not shown). In the open position, the valve plug assembly 10 is spaced apart from the valve seat 18, thereby allowing flow through the control valve 12; in the closed position, the valve plug assembly 10 is seated against the valve seat 18, thereby preventing flow through the control valve 12.
[0019] Reference Figure 3 The plug assembly 10 includes a plug base 20 defining a longitudinal axis X and having a first end 22 and a second end 24. The first end 22 of the plug base 20 is arranged for attachment to a valve stem 14 of a control valve 12. The second end 24 of the plug base 20 includes a hole 26 extending along the longitudinal axis L, wherein the hole 26 includes a first portion 28 extending into the plug base 20 at a first distance L1 and a second portion 30 extending into the plug base 20 at a second distance L2, wherein the second distance L2 is less than the first distance L1. The first portion 28 of the hole 26 has a first diameter D1, and the second portion 30 of the hole 26 has a second diameter D2, wherein the second diameter D2 is greater than the first diameter D1. The second portion 30 of the hole 26 extends from the second end 24 of the plug base 20 to an end or distal end 32. In the disclosed example, the distal end 32 is a tapered end and forms a first seat 34.
[0020] The spacer 36 has a through-hole 38 and also includes a first end 40 and a second end 42. The spacer 36 is sized to be inserted into a second portion 30 of the hole 26 of the plug base 20, and in the disclosed embodiment, the first end 40 of the spacer 36 includes a tapered portion 44. The tapered portion 44 is arranged to engage a first seat 34 at the end 32 of the second portion 30 of the hole 26 of the plug base. The second end 42 of the spacer 36 has a tapered end 46 forming a second seat 48. The plug tip 50 includes a through-hole 52, and the first end 54 having the tapered portion 56 is arranged to engage the second seat 48 of the spacer 36. The plug tip 50 also includes a second end 58, which is shaped to engage a valve seat 18 of the control valve 12.
[0021] The headed screw 60 includes ends 62 and 64, and is sized to be inserted through a hole 52 through the plug tip 50 and a through hole 38 through the spacer 36. End 64 of the headed screw 60 is shaped to engage the plug tip 50, while end 62 includes threads 66 to allow threaded engagement with mating threads 68 in the first portion 28 of the hole 26 in the plug base 20. Thus, the headed screw 60 mechanically secures the plug tip 50 to the plug base 20.
[0022] The base 20 may include, for example Figure 3 The side hole 70 is shown. The side hole 70 is sized to receive a pin 72, which is sized to be inserted into a position within the side hole 70 where the pin 72 engages the inner portion 74 of the headed screw 60. The inner portion 74 of the headed screw 60 is disposed within a first portion 28 of the hole 26. The pin 72 may include a threaded portion 76 arranged to engage a mating thread 78 on the side hole, thereby allowing the end 80 of the pin 72 to engage the inner portion 74 of the headed screw 60 by an interference fit. Alternatively, the inner portion 74 of the headed screw 60 may have a side hole 82 such that the end 80 of the pin 72 engages with the side hole 82 of the headed screw. As another alternative, the end 80 of the pin 72 and the side hole 82 of the headed screw 60 may have mating threads. In any of the aforementioned arrangements, the pin 72 is secured with a head screw 60 to prevent rotation, thereby securing the plug tip 50 against the second seat 48 of the spacer 36, and further securing the first end 40 of the spacer 36 against the first seat 34. According to an exemplary embodiment, the outer portion of the pin 72 for anti-rotation purposes may be embedded in the plug body 20 and may be covered by a gasket, thus protecting the pin 72 from the influence of surrounding components.
[0023] The plug tip 50 may be selected from ceramic materials, and may be carbide or tungsten carbide, or may be any other suitable material. The plug tip 50 may be provided with a countersunk hole 84, the size of which is configured to receive the screw head 86 of the head screw 60, such that all or part of the screw head 86 is recessed into the plug tip 50, and thus completely or at least partially disengaged from the path of fluid flow.
[0024] The first seat 34 and the first end 40 of the spacer 36 can be suitably shaped to mate with each other so that the spacer is centered relative to the longitudinal axis L. Similarly, the second seat 48 on the second end 42 of the spacer 36 can also be suitably shaped to mate with each other so that the plug tip is centered relative to the longitudinal axis L. In the disclosed examples, these shapes are primarily tapered or truncated tapered. However, other shapes can prove suitable. For example, the shapes of these mating parts can be hemispherical or other curved forms. In summary, tapered or other shapes are advantageous or otherwise facilitate the self-centering of the spacer and plug tip relative to the longitudinal axis L.
[0025] The headed screw 60 can be constructed from Inconel 718, which has shown advantageous strength properties in testing. Upon reading this disclosure and appreciating its benefits, those skilled in the art can obtain other shapes for the spacer 36 and plug tip 50 to promote self-centering and / or service life. The spacer 36 can be constructed from austenitic stainless steel, which offers a greater coefficient of thermal expansion, although other materials may prove suitable. This material can be used to compensate for the difference in thermal expansion between the carbide tip and the headed screw in the mechanical fastening component and to maintain appropriate clamping stress for the connection. When constructed from austenitic stainless steel or other suitable and relatively soft materials, the spacer 36 can act as a buffer for the relatively hard ceramic or carbide plug tip 50 and can be used to absorb impact forces, thereby inhibiting crack formation in high-vibration applications.
[0026] The plug tip 50 is hollow and has a relatively uniform thickness, thus avoiding internal defects and stresses during manufacturing and providing advantages over solid plug tips.
[0027] When constructed, valve plug assemblies assembled according to the exemplary teachings outlined herein can provide one or more technical advantages that cannot be achieved by prior art teachings. For example, the valve plug assembly employs mechanically fastened structures and methods, which improves ease of manufacture and enhances the quality of the resulting assembly. Furthermore, the disclosed structures and methods facilitate low-cost or cost-effective designs, thus potentially offering commercial advantages. Moreover, the use of materials outlined herein, by allowing the use of lower-cost, readily available, and standard materials, frees manufacturers from the stringent requirements of shrink-fit or brazed constructions.
[0028] Another potential technical advantage is that the disclosed aspect facilitates easier maintenance by allowing end users to modify worn plug tips rather than replace the entire valve plug assembly.
[0029] When compared with existing structures and components, one or more aspects of the present invention suppress the development of harmful and uncontrollable internal stresses generated by previous constructions, such as those that may be found during shrinkage fits.
[0030] When compared with existing structures and components, one or more aspects of the present invention produce components that offer better performance and lifespan over a wider temperature range, providing advantages over existing brazing component structures and methods. This is especially true for larger valve internals.
[0031] Compared to conventional mechanical fastening and clamping, one or more aspects of this disclosure facilitate stress control on the plug tip and other components, again contributing to better performance over a wider temperature range.
[0032] Although certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes can be made to the methods and apparatus disclosed herein without departing from the scope of the invention.
Claims
1. A valve plug assembly for use in a control valve, the control valve having a valve stem, a flow passage, and a valve seat disposed in the flow passage, the valve plug assembly comprising: The base of the plug defines a longitudinal axis and has a first end and a second end; The first end of the plug base is arranged for attachment to the valve stem of the control valve; The second end of the plug base includes a hole extending along the longitudinal axis, the hole comprising: a first portion extending into the plug base by a first distance; and a second portion extending into the plug base by a second distance, the second distance being less than the first distance; The first portion of the hole has a first diameter, and the second portion of the hole has a second diameter that is larger than the first diameter; The second portion of the hole extends from the second end of the plug base to the tapered end, the tapered end forming the first seat; A spacer having a through hole, a first end, and a second end, the spacer being sized to be inserted into the second portion of the hole of the plug base, the first end of the spacer having a tapered shape arranged to engage with a first seat, and the second end of the spacer having a tapered end forming a second seat; A plug tip having a through hole, the plug tip further comprising a first end having a tapered shape having been disposed within the second portion of the hole in the plug base and arranged to engage with the second seat of the spacer, and the plug tip further having a second end shaped to engage with the valve seat of the valve; and A headed screw, sized to be inserted through the through hole of the plug tip and the spacer, and arranged to be threaded into the first portion of the hole in the plug base; The headed screw mechanically secures the tip of the plug to the base of the plug.
2. The valve plug assembly of claim 1, wherein the plug base includes a side hole sized to receive a pin, and wherein the pin engages with the inner portion of the headed screw.
3. The valve plug assembly according to claim 1, wherein the plug tip is selected from a ceramic material.
4. The valve plug assembly of claim 1, wherein the plug tip comprises carbide.
5. The valve plug assembly of claim 4, wherein the plug tip comprises tungsten carbide.
6. The valve plug assembly of claim 2, wherein the plug tip includes a countersunk hole, and the headed screw includes a screw head sized to be located within the countersunk hole.
7. The valve plug assembly of claim 1, wherein the tapered shape of the spacer engages with the first seat to center the spacer relative to the longitudinal axis, and wherein the tapered shape of the plug tip engages with the second seat to center the plug tip relative to the longitudinal axis.
8. A method of forming a valve plug assembly for use in a control valve, the control valve having a rigid valve stem, a flow passage, and a valve seat disposed in the flow passage, the method comprising: A plug base is provided, the plug base defining a longitudinal axis and having a first end and a second end; The first end of the plug base is arranged for attachment to the valve stem of the control valve, such that the plug base moves together with the valve stem; A hole extending along the longitudinal axis is provided at the second end of the plug base, the hole comprising: a first portion extending into the plug base by a first distance; and a second portion extending into the plug base by a second distance, the second distance being less than the first distance; A first diameter is provided for the first portion of the hole, and a second diameter larger than the first diameter is provided for the second portion of the hole; A first forming seat is provided for the second portion of the hole extending from the second end of the plug base; A spacer is provided having a through hole, a first end, and a second end. The spacer is sized to be inserted into the second portion of the hole in the plug base. The first end of the spacer has a shaped portion to mate with a first shaped seat, and a second shaped seat is provided for the second end of the spacer. A plug tip is provided, the plug tip having a through hole, defining an internal portion having a first end arranged in a tapered shape to engage with the second forming seat, and a second end formed to engage with the valve seat of the valve; A headed screw is provided, sized to be inserted through the through hole of the plug tip and the spacer, and the headed screw is arranged to be threaded into the first portion of the hole of the plug base, thereby mechanically securing the plug tip to the plug base.
9. The method of claim 8, further comprising providing a side hole for the plug base, the side hole being sized to receive a pin, and inserting the pin into the side hole to engage the headed screw, thereby locking the headed screw to prevent rotation.
10. The method of claim 8, further comprising selecting the plug tip from a ceramic material.
11. The method of claim 8, further comprising forming the plug tip from a carbide.
12. The method of claim 11, further comprising forming the plug tip with tungsten carbide.
13. The method of claim 8, further comprising providing a countersunk hole for the plug tip and providing a screw head sized to be located within the countersunk hole for the headed screw.
14. The method of claim 8, further comprising arranging the shaped portion of the spacer and the first shaped seat to engage such that the spacer is centered relative to the longitudinal axis, and arranging the shaped portion of the plug tip and the second shaped seat to engage such that the plug tip is centered relative to the longitudinal axis.
15. A valve plug assembly for use in a control valve, the control valve having a valve stem, a flow passage, and a valve seat disposed in the flow passage, the valve plug assembly comprising: The base of the plug defines a longitudinal axis and has a first end and a second end; The first end of the plug base is arranged for direct attachment to the valve stem of the control valve; The second end of the plug base has a hole extending along the longitudinal axis, the hole comprising: a first portion extending into the plug base by a first distance; and a second portion extending into the plug base by a second distance, the second distance being less than the first distance, the inner end of the second portion of the hole terminating in a first forming seat; A spacer having a through hole, a first end, and a second end, the spacer being sized to be inserted into the second portion of the hole of the plug base, the first end of the spacer having a shaped end to mate with a first shaped seat, and the second end of the spacer having a second shaped seat; A plug tip has a through hole, a first end, and a second end, the first end being disposed within a second portion of the hole in the plug base and shaped and arranged to engage with a second shaped seat, and the second end being shaped to engage with the valve seat of the valve; and A headed screw, sized to be inserted through the through-hole of the plug tip and the spacer, is arranged to engage with the first portion of the hole in the plug base, the headed screw securing the plug tip to the plug base.
16. The valve plug assembly of claim 15, wherein the plug base has a side hole sized to receive a pin arranged in the side hole to interfere with the headed screw, thereby locking the headed screw to prevent rotation.
17. The valve plug assembly of claim 15, wherein the plug tip comprises ceramic or carbide.
18. The valve plug assembly of claim 17, wherein the plug tip comprises tungsten carbide.
19. The valve plug assembly of claim 15, wherein the plug tip includes a countersunk hole, and the headed screw includes a screw head sized to be located within the countersunk hole.
20. The valve plug assembly of claim 15, wherein the shaped end of the spacer engages with the first shaped seat to center the spacer relative to the longitudinal axis, and wherein the shaped first end of the plug tip engages with the second shaped seat to center the plug tip relative to the longitudinal axis.
21. The valve plug assembly of claim 15, wherein the spacer includes a first coefficient of thermal expansion, the plug tip includes a second coefficient of thermal expansion, and the headed screw includes a third coefficient of thermal expansion, wherein the first coefficient of thermal expansion is greater than the second coefficient of thermal expansion and the third coefficient of thermal expansion, and wherein the second coefficient of thermal expansion and the third coefficient of thermal expansion are different.
22. The valve plug assembly of claim 21, wherein the spacer is constructed of austenitic stainless steel and is softer than the plug tip, such that the spacer is arranged to absorb impact forces and / or thermal expansion forces from the plug tip.