GB2474348A

GB2474348A - Adjustable valve seat lapping system

Info

Publication number: GB2474348A
Application number: GB1016746A
Authority: GB
Inventors: Rick J Chilson
Original assignee: Dresser Rand Co
Current assignee: Dresser Rand Co
Priority date: 2009-10-07
Filing date: 2010-10-05
Publication date: 2011-04-13
Also published as: GB201016746D0

Abstract

A lapping system for a valve seat or face (116 fig. 1) in a valve body (100 fig. 1) includes a rotatable shaft 202 spaced along and coupled to which are a stabilizing member or guide 212, a lapping tool 206 and an adjustable force device or spring 218. The adjustable force device 218 may be adjusted to transfer at least some of the weight of the lapping tool 206 to the stabilizing member 212 in use and so vary the force of the tool 206 on the valve face (16 fig. 1). The lapping system may include a further guide or stabiliser bar 208 coaxial with shaft 202 and locating in a valve stem passageway 120. Spring 218 may be adjusted by nut 220 moving along a threaded section of shaft 202. The guide or stabilizing member 212 may be circular with a circumferential lip or channel (212a fig. 2B) and conform to an opening (108 fig. 1) in the valve body. Thrust bushing 216 and guide bushing 214 for the shaft 202 may be provided on stabilizing member 212. The lapping tool 206 may be a disc with a bevelled edge (206b fig. 2B) rotatable by means of a handle 224.

Description

LAPPING SYSTEM

Cross-Reference to Related Applications

[0001] This application claims the benefit of the filing date of US Patent Application Serial No. 12/620,303, filed on November 17, 2009 which claims the benefit of the filing date of US Provisional Patent Application Serial No. 61/249,499, filed on October 7, 2009, the entire disclosure of each of the above-noted applications are incorporated herein by reference.

Background

[0002] This disclosure relates in general to valve assemblies, and in particular to a lapping system for use with a valve assembly.

[0003] Some valve assemblies include a valve body and an internal valve stem that is seated on a valve face of the valve body during valve operation. It is desirable for a tight seal to exist between the internal valve stem and the valve face on which it sits such that no leaks are allowed between the internal valve stem and the valve face.

Traditionally, a lapping process is performed on the valve face in which a lapping tool is positioned adjacent the valve face with a lapping compound between the lapping tool and the valve face. The lapping tool is then moved relative to the valve face, causing the lapping material to smooth the valve face such that a tight seal may be provided between the internal valve stem and the valve face.

[0004] Conventional lapping tools, however, suffer from a number of issues. For example, the lapping tool may become misaligned with the valve face during lapping, creating a surface on the valve face that is uneven and cannot form a tight seal. It is also difficult to control the pressure applied to the valve face using these conventional lapping tools, which can also create a surface on the valve face that is uneven and cannot form a tight seal. Furthermore, with conventional lapping tools that perform the lapping operation by rotating relative to the valve face through the twisting of an arm that extends from the lapping tool, unwanted horizontal forces can be imparted by the lapping tool that can also create a surface on the valve face that is uneven and cannot form a tight seal.

[0005] Therefore, what is needed is an improved lapping system that does not suffer from the drawbacks discussed above.

Summary

[0006] Embodiments of the disclosure may provide a lapping system. The lapping system may include a rotatable shaft, a stabilizing member coupled to the rotatable shaft, and a lapping tool coupled to the rotatable shaft and spaced apart on the rotatable shaft from the stabilizing member. The system may further include an adjustable force device coupled to the rotatable shaft, the stabilizing member, and the lapping tool, wherein the adjustable force device is operable to be adjusted in order to cause the stabilizing member to support at least some of the weight of the lapping tool.

[0007] Embodiments of the disclosure may provide a method for lapping a valve face defined within a valve body. The method may include providing a lapping tool coupled to a stabilizing member via a rotatable shaft, and an adjustable force device coupled to the stabilizing member, the rotatable shaft, and the lapping tool. The method may also include locating a stabilizing bar within a valve stem passageway defined within the valve body, wherein the stabilizing bar extends from the lapping tool co-axial with the rotatable shaft, and disposing the lapping tool within the valve body immediately adjacent the valve face. The method may further include seating the stabilizing member in an opening defined by the valve body, adjusting a force imparted by the lapping tool on the valve face using the adjustable force device, and rotating the rotatable shaft to move the lapping tool relative to the valve face.

Brief Description of the Drawings

[0008] The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

[0009] Figure 1 is a cross-sectional view illustrating an embodiment of a valve body.

[0010] Figure 2a is an exploded view illustrating an embodiment of a lapping system.

[0011] Figure 2b is a front view illustrating an embodiment of the lapping system of Figure 2a.

[0012] Figure 3a is a flow chart illustrating an embodiment of a method for lapping a valve face.

[0013] Figure 3b is a partial cross-sectional view illustrating an embodiment of the lapping system of Figures 2a and 2b located in the valve body of Figure 1.

[0014] Figure 3c is a partial cross-sectional view illustrating an embodiment of a lapping tool of the lapping system of Figures 2a and 2b and a valve face of the valve body of Figure 1 with an abrasive material between them.

[0015] Figure 3d is a partial cross-sectional view illustrating an embodiment of a valve stem located in the valve body of Figure 1.

Detailed Description

[0016] It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure, however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the

disclosure.

(0017] Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Further, in the following discussion and in the claims, the terms "including" and "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to." All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term "or" is intended to encompass both exclusive and inclusive cases, i.e., "A or B" is intended to be synonymous with "at least one of A and B," unless otherwise expressly specified herein.

[0018] Referring now to Figure 1, a valve body 100 is illustrated, The valve body 100 may generally include a base 102 having a top surface 102a, a bottom surface 102b, and a pair of opposing side surfaces 102c and 102d. An inlet 104 may extend from a location on the side surface 102d adjacent the top surface 102a and defines an inlet passageway 104a. An outlet 106 may extend from a location on the side surface 102c adjacent the bottom surface 102b and defines an outlet passageway 106a. An opening 108 may be defined by an opening edge 110 on the base 102 and extends into the base 102 from the top surface 102a. In an embodiment, the opening 108 may be circular in shape. A plurality of cover couplings 112 may be located on the top surface 102a adjacent the opening 108.

[0019] A valve stem housing 114 is defined by the base 102 and is located adjacent the opening 108 and the inlet passageway I 04a. A valve face 116 is located adjacent the valve stem housing 114 and may be generally circular in shape. In an embodiment, the valve face 116 includes a beveled edge or surface on an internal surface of the valve body 100, as illustrated in Figure 1. A valve stem opening 118 may also be defined by the base 102 and located adjacent the valve face 116 and the outlet passageway 106a, A valve stem passageway 120 may be defined by the base 102, located adjacent the valve stem opening 118, and extend to the bottom surface I 02b of the base 102. While a specific valve body 100 has been described above, one of skill in the art will recognize that a variety of valve bodies having different features may be substituted with the valve body 100 without departing from the scope of the present

disclosure.

(0020] Referring now to Figures 2a and 2b, a lapping apparatus or system 200 is illustrated. In one or more embodiments, the lapping system 200 may include a shaft 202 having a first end 202a that is coupled to a lapping tool plate 204, a second distal end 202b located opposite the shaft 202 from the first end 202a, and a circumferential ledge 202c that runs about the circumference of the shaft 202 and is located approximately midway between the first end 202a and the second distal end 202b. A portion of the shaft 202 adjacent the second distal end 202b may be threaded, as illustrated. In the illustrated embodiment, the lapping tool plate 204 is generally circular and defines a plurality of securing apertures 204a and 204b that extend through the lapping tool plate 204. A lapping tool 206 may be coupled to the lapping tool plate 204 and include a stabilizing bar 208 extending from a surface 206a of the lapping tool 206 that is opposite the lapping tool plate 204. As illustrated, the lapping tool 206 may be generally characterized as a rotatable disk having a beveled edge 206b adjacent the surface 206a and defining a plurality of securing apertures 206c and 206d. The lapping tool plate 204 may be coupled to the lapping tool 206 using a plurality of securing members 210 (e.g., screws) that are positioned in the securing apertures 204a, 204b, 206c and 206d. A stabilizing member 212 may be located on the shaft 202 adjacent the circumferential ledge 202c. in one or more embodiments, the stabilizing member 212 may be circular in shape and define a stabilizing channel 212a that is located about the circumference of the stabilizing member 212.

(0021] In an embodiment, the stabilizing member 212, the lapping tool 204, and the shaft 202 each comprise circular cross sections and share an axis of rotation when coupled together, as illustrated in Figure 2b, A guide bushing 214 may be located on the shaft 202 immediately adjacent the stabilizing member 212. A thrust bushing 216 may be located on the shaft 202 immediately adjacent the guide bushing 214. A spring 218 may be located on the shaft 202 immediately adjacent the thrust bushing 216. A pressure adjusting nut 220 may be located on the shaft 202 immediately adjacent the spring 218.

[0022] In at least one embodiment, the spring 218 and the pressure adjusting nut 220, including the adjacent bushings 214, 216, may generally provide an adjustable force device. However, one of skill in the art will recognize a variety of adjustable force devices that may replace the spring 218 and the pressure adjusting nut 220 without departing from the scope of the present disclosure. A first jam nut 222 may be located on the shaft 202 adjacent the pressure adjusting nut 220. A handle 224 may be located on the shaft 202 immediately adjacent the first jam nut 222. A second jam nut 225 may be located on the shaft 202 immediately adjacent the handle 224 and opposite the first jam nut 222. In an embodiment, each of the pressure adjusting nut 220, the first jam nut 222, the handle 224, and the second jam nut 225 may be threaded onto the shaft 202. In an embodiment, the shaft 202 may be operable to move relative to the stabilizing member 212, the guide bushing 214, the thrust bushing 216, and the spring 218 by, for example, sliding through apertures defined by the components. A lifting member 226 may be coupled to the second distal end 202b of the shaft 202 and located immediately adjacent the second jam nut 225.

[0023] Referring now to Figures 1, 2b, 3a, 3b, 3c and 3d, a method 300 for lapping a valve face is illustrated. The method 300 begins by providing a lapping system, as at 302. In an embodiment, the lapping system 200, described above with reference to Figures 2a and 2b, is provided. The lapping system may then be coupled to a valve body, as at 304. The lapping system 200 is positioned adjacent the valve body 100, described above with reference to Figure 1, such that the stabilizing bar 208 is located adjacent the opening 108 defined adjacent the top surface 102a of the valve body 100.

The lapping system 200 is then moved towards the valve body 100. Movement of the lapping system 200 towards the valve body 100 causes the stabilizing bar 208 and the lapping tool 206 to enter the valve stem housing 114. The stabilizing bar 208 and the lapping tool 206 then move through the va've stem housing 114 until the stabilizing bar 208 enters the valve stem passageway 120 and the beveled surface 206b on the lapping tool 206 engages the valve face 116 (illustrated in Figure 1).

[0024] With the lapping tool engaging the valve face 116, the stabilizing member 212 may be configured to engage the valve body 100 such that the opening edge 110 (illustrated in Figure 1) on the valve body 100 becomes located in the stabilizing channel 212a (illustrated in Figure 2b) and the stabilizing member 212 becomes seated in the opening 108, as illustrated in Figure 3b. By positioning the stabilizing bar 208 in the valve stem passageway 120 and seating the stabilizing member 212 in the opening 108 on the valve body 100 (as a result of positioning the opening edge 110 in the stabilizing channel 212a), the lapping tool 200 may be aligned with, or otherwise located substantially adjacent to, the valve face 116 to help ensure that symmetrical and even lapping operations may be conducted on the valve face 116 with the lapping tool 206.

[0025] In one or more embodiments, an abrasive compound or material 304a such as, for example, Clover® brand lapping compounds and/or a variety of other lapping compounds known in the art, may be added between the beveled surface 206b on the lapping tool 206 and the valve face 116, as illustrated in Figure 3c.

[0026] The force imparted by the lapping tool on the valve face may then be adjusted, as at 306 in the method 300. With the lapping system 200 coupled to the valve body as illustrated in Figure 3b, the weight of some or all of the components of the lapping system may provide a force on the valve face 116 through the lapping tool 206.

However, due to the coupling of the lapping tool 206 to the shaft 202, the coupling of the stabilizing member 212 to the shaft 202 and the opening edge 110 on the valve body 100, and the coupling of the adjustable force device (Le, the spring 218 and the pressure adjusting nut 220) to the stabilizing member 212 and the shaft 202, the pressure adjusting nut 220 may be adjusted to compress or decompress the spring 218 in order to adjust the force imparted by the lapping tool 206 on the valve face 116. For example, if the force imparted by the lapping tool 206 on the valve face 116 is too great, the pressure adjusting nut 220 may be adjusted (i.e., rotated) to compress the spring 218, which causes the spring 218 to exert a force on shaft 202 through the pressure adjusting nut 220. The force exerted on the shaft 202 is opposite the force provided by the weight of the components of the lapping system 200, and causes at least some of the weight of the components of the lapping system 200 (e.g, the lapping tool 206, the stabilizing bar 208, etc.) to be transferred through the stabilizing member 212 to the opening edge 110 on the valve body 100 rather than through the lapping tool 206 to the valve face 116. If the force imparted by the lapping tool 206 on the valve face 116 is too little, the pressure adjusting nut 220 may be adjusted (Le., rotated) to decompress the spring 218, which will allow less of the weight of the components of the lapping system (o.g, the lapping tool 206, the stabilizing bar 208, etc.) to be transferred through the stabilizing member 212 to the opening edge 110 on the valve body 100 and instead allow that weight to be transferred from the lapping tool 206 to the valve face 116.

Thus, the force imparted by the lapping tool 206 on the valve face 116 may be precisely controlled in order to optimize lapping operations.

[0027] The method 300 further includes rotating the lapping tool, as at 308. With the lapping system 200 coupled to the valve body 100 as illustrated in Figure 3b, the handle 224 may be turned in order to rotate the shaft 202. Rotation of the shaft 202 causes the lapping tool 206 to rotate relative to the valve face 116 such that the abrasive material 304a located between the beveled surface 20Gb on the lapping tool 206 and the valve face 116 abrades or otherwise polishes the valve face 116. While the handle 224 is being turned, horizontal forces (La, forces in a direction that is radial to the longitudinal axis of the shaft 202) applied to the handle 224 are prevented from being transferred to the lapping tool 206 by the stabilizing member 212. If not properly prevented such horizontal forces can cause the lapping tool 206 to orbit' and create an uneven surface on the valve face 116. However, the stabilizing member 212 as generally described herein ensures that only vertical forces are imparted by the lapping tool 206 to the valve face 116.

[0028] When lapping operations are complete and the valve face 116 has been polished to a desired level, the lapping tool 200 may be removed from the valve stem housing 114, a valve stem 308a may be positioned in the valve stem housing 114, and a cover 308b may be coupled to the valve stem 308a and the valve body 100, as illustrated in Figure 3d. As can be appreciated, by using the lapping system 200 as described above, the valve face 116 may be lapped evenly and completely in order to provide a tight sea' between the va've stem 308a and the valve face 116. Thus, a lapping system is provided that ensures alignment of a lapping tool with the valve face while providing a controlled, vertical force from the lapping toot to the valve face.

[0029] The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the detailed description that follows. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit

and scope of the present disclosure.

Claims

Claims What is claimed is: 1, A lapping system, comprising: a rotatable shaft (202); a stabilizing member (212) coupled to the rotatable shaft (202); a lapping tool (206) coupled to the rotatable shaft (202) and spaced apart on the rotatable shaft (202) from the stabilizing member (212); and an adjustable force device coupled to the rotatable shaft (202), the stabilizing member (212), and the lapping tool (206), wherein the adjustable force device is operable to be adjusted in order to cause the stabilizing member (212) to support at least some of the weight of the lapping tool (206).
2. The system of claim 1, wherein a stabilizing member (212) is radially-offset from the lapping tool (206) along the rotatable shaft (202).
3. The system of claim 2, wherein a stabilizing bar (208) extends from the lapping tool (206) co-axial with the rotatable shaft (202).
4. The system of claim 3, wherein the stabilizing bar (208) is configured to be located within a valve stem passageway (120) defined within a valve body (100).
5. The system of claim 1, wherein the stabilizing member (212), the lapping tool (206), and the rotatable shaft (202) each comprise circular cross sections and share an axis of rotation.
6. The system of claim 1, wherein a stabilizing channel (212a) is defined about an outer edge of the stabilizing member (212).
7. The system of claim 6, wherein the stabilizing channel (212a) is configured to be disposed immediately adjacent an opening edge (110) defined by a valve body (100).
8. The system of claim 1, wherein the adjustable force device comprises: a guide bushing (214) disposed about the rotatable shaft (202) and immediately adjacent the stabilizing member (212); a thrust bushing (216) disposed about the rotatable shaft (202) immediately adjacent the guide bushing (214); a spring (218) disposed about the rotatable shaft (202) and immediately adjacent the thrust bushing (216); and a pressure adjusting nut (220) threadably engaged with the rotatable shaft (202) immediately adjacent the spring (218).
9, The system of claim 1, wherein the lapping tool (206) comprises rotatable disk having a beveled edge (206b).
10. The system of claim 9, wherein the beveled edge (206b) is configured to be disposed immediately adjacent a valve face (116) defined by a valve body (100).
11. The system of claim 10, wherein an abrasive material (304a) is located between the beveled edge (206b) and the valve face (116).
12. A method for lapping a valve face (116) defined within a valve body (100), comprising: providing a lapping tool (206) coupled to a stabilizing member (212) via a rotatable shaft (202), and an adjustable force device coupled to the stabilizing member (212), the rotatable shaft (202), and the lapping tool (206); locating a stabilizing bar (208) within a valve stem passageway (120) defined within the valve body (100), wherein the stabilizing bar extends from the lapping tool (206) co-axial with the rotatable shaft (202); disposing the lapping tool (206) within the valve body (100) immediately adjacent the valve face (116); seating the stabilizing member (212) in an opening (108) defined by the va've body (100); adjusting a force imparted by the lapping tool (206) on the valve face (116) using the adjustable force device; and rotating the rotatable shaft (202) to move the lapping tool (206) relative to the valve face (116).
13. The method of claim 12, wherein seating the stabilizing member (212) in the opening (108) further comprises disposing a stabilizing channel (212a) defined about an outer edge of the stabilizing member (212) immediately adjacent an opening edge (110) defined by the valve body (100).
14. The method of claim 12, further comprising providing an abrasive material (304a) between the lapping tool (206) and the valve face (116).
15. The method of claim 12, wherein adjusting the force imparted by the lapping tool (206) on the valve face (116) using the adjustable force device comprises compressing a spring (218).
16. The method of claim 17, wherein rotating the rotatable shaft (202) comprises turning a handle (224) that is coupled to the rotatable shaft (202).
17. A lapping system substantially as described herein, with reference to, and as shown in, the accompanying drawings.
18. A method of lapping a valve face substantially as described herein, with reference to the accompanying drawings.