Method for forming a sealing element

Abstract

A system and method for forming sealing elements for a mechanical seal, the sealing elements being shaped to substantially completely fill the grooves in which they are mounted. The mechanical seal includes a rotating or stationary component, such as a holder assembly, a sleeve assembly, or a balance piston, having one or more grooves formed therein, and a sealing element mounted within the groove.

Description

Technical Field

[0001] Related Applications This patent application claims priority to U.S. Provisional Patent Application No. 62 / 832,206, filed Apr. 10, 2019, entitled “Method for Forming an Elastomeric Ring of a Mechanical Seal,” which is incorporated herein by reference in its entirety.

Background Art

[0002] In conventional mechanical seals, generally, the holder portion of the mechanical seal is fixed, for example, by tightening between the impeller and the shaft of a commercially available device such as a pump, reducing the number of crevices in the seal. This has the effect of reducing unwanted leakage of process fluid from the pump. However, with this fixing method, on-site personnel need to modify the design of the mechanical seal by introducing this fixing mechanism. As a result, the overall seal integrity of the mechanical seal may be impaired.

[0003] In other known techniques, mechanical seals use additional sealing elements such as annular O-rings to assist in sealing the process fluid within the mechanical seal. One drawback of such conventional annular sealing elements is that they cannot completely seal the fluid or completely fill the space or groove where the sealing element is attached. This is unacceptable in a commercial environment where it is extremely important to prevent the growth of microbacteria. To address this drawback, specially designed sealing elements have been formed using conventional molding techniques. For example, the sealing element is manufactured by molding a liquid raw material in a rigid frame called a mold. However, with these conventional molding techniques, the production of suitable sealing elements is expensive and time-consuming.

Summary of the Invention

[0004] The present invention relates to a system and method for forming a sealing element of a mechanical seal, wherein the sealing element is shaped to substantially completely fill a groove in which the sealing element is mounted. The mechanical seal includes a holder assembly having one or more grooves formed therein and a sealing element mounted in the grooves.

[0005] Furthermore, the present invention also relates to a mechanical seal using a sealing cover element configured to overlap or cover an attachment-receiving opening formed in the holder assembly, thereby forming a fluid-tight seal. The sealing cover element includes legs mounted in grooves disposed on both sides of the attachment-receiving opening for fixing the sealing cover element to the holder assembly.

[0006] The present invention relates to a method for forming a sealing element of a mechanical seal, the method including winding a source of elastomeric material, heating the elastomeric material to form a homogeneous elastomeric material, coating the homogeneous elastomeric material with a resin material, disposing the resin-coated elastomeric material in a lathe, forming an outer contour and shape of the sealing element in the shaped resin-coated elastomeric material, and cutting the sealing element from the shaped resin-coated elastomeric material.

[0007] The elastomeric material can include ethylene propylene (EP), ethylene propylene diene methylene (EPDM), fluoroelastomers including FKM and FPM defined in ASTM International Standard D1418, perfluoroelastomers including FFKM, and tetrafluoroethylene propylene rubber including FEPM. Furthermore, the elastomeric material has a hardness between about 70 Shore A and about 90 Shore A.

[0008] The present invention relates to a system for forming a sealing element of a mechanical seal, the system comprising a source of elastomeric material, a winder for winding the elastomeric material, a heating unit comprising one or more heating elements for heating the elastomeric material to form a homogeneous elastomeric material, a coating unit for coating the homogeneous elastomeric material with a resin material, a turning machine for forming the outer contour and shape of the sealing element in the shaped resin-coated elastomeric material, and a cutting unit for cutting the sealing element from the shaped resin-coated elastomeric material. The system further comprises an electronic device for communicating with and controlling one or more of the winder, the heating unit, the coating unit, the turning machine, and the cutting unit. The electronic device comprises a processor and a memory element.

[0009] The turning machine can include one or more cutting elements for forming the contour in the shaped resin-coated elastomeric material.

[0010] In another aspect, the present invention relates to a mechanical seal mounted around a shaft, the mechanical seal comprising a holder assembly having a body with an inner surface and an opposing outer surface, the holder assembly including a first groove formed in the inner surface of the holder assembly and a second groove formed in the outer groove of the holder assembly, a rotating seal ring coupled to the holder assembly, a stationary seal ring disposed adjacent to the rotating seal ring, a first sealing element mounted in the first groove and configured to substantially completely fill the first groove, and a second sealing element mounted in the second groove and configured to substantially completely fill the second groove.

[0011] The first sealing element has a shape complementary to the shape of the first groove, and the second sealing element has a shape complementary to the shape of the second groove. Further, the body of the holder assembly has one or more fastener receiving openings formed therein and extending between the inner surface and the outer surface, the one or more fastener receiving openings being sized and configured to receive a fastener.

[0012] Regarding the holder assembly, the assembly further includes a sealing cover element having a body with first and second cover grooves formed in the outer surface of the holder assembly, the first cover groove being formed on one side of the fastener receiving opening and the second cover groove being formed on the other side of the fastener receiving opening, a first leg, an opposing second leg, and an intermediate portion disposed between the first leg and the second leg and coupled to the first and second legs. The first leg of the sealing cover element is sized and configured to be mounted within the first groove, the second leg of the sealing cover element is sized and configured to be mounted within the second groove, and the intermediate portion of the sealing cover element covers the fastener receiving opening. The first leg is sized and configured to substantially completely fill the first cover groove, the second leg is sized and configured to substantially completely fill the second cover groove, the intermediate portion of the sealing cover element has an upper surface and an opposing bottom surface, and the first and second legs each have an upper surface and an opposing bottom surface. The upper surface of the intermediate portion is radially spaced from the upper surfaces of the first and second legs. Also, the bottom surfaces of the first and second legs are radially spaced from the bottom surface of the intermediate portion.

Brief Description of the Drawings

[0013] The above and other features and advantages of the present invention should be more fully understood with reference to the following detailed description and the accompanying drawings, in which like reference symbols in the drawings indicate like members throughout the several views. These drawings represent the principles of the present invention and, although not to scale, show relative dimensions.

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BEST MODE FOR CARRYING OUT THE INVENTION

[0014] The present invention provides, in addition to a sealing cover element that realizes sealing of a set screw opening formed within a holder assembly of a mechanical seal, an additional sealing element that realizes a fluid-tight seal at a selected sealing position. The present invention will be described below in connection with the illustrated embodiments. Those skilled in the art should understand that the present invention is realizable in numerous different applications and embodiments and is not particularly limited to the specific embodiments described herein.

[0015] As used herein, the term "shaft" is intended to refer to any suitable device to which a seal can be attached in a mechanical system and includes shafts, rods, and other known devices.

[0016] As used herein, the terms "axial" and "axially" refer to a direction generally parallel to the axis of any shaft. As used herein, the terms "radial" and "radially" refer to a direction generally perpendicular to the axis of any shaft. The terms "fluid" and "fluids" refer to liquids, gases, and combinations thereof.

[0017] As used herein, the term "axially inner" refers to a portion of a stationary device and / or a component of a mechanical seal that is disposed in proximity to a stationary device (e.g., a machine system) in which the mechanical seal is used. Thus, the term refers to a component of a mechanical seal that is mounted on or within a stationary device, or a component of a mechanical seal that is disposed deep within or closest to (inboard of) the interior of the device. Conversely, as used herein, the term "axially outer" refers to a portion of a stationary device and a mechanical seal that is distal (outboard of) the mechanical seal.

[0018] As used herein, the term "radially inner" refers to a portion of a mechanical seal or an associated component that is in proximity to any shaft. Conversely, as used herein, the term "radially outer" refers to a portion of a mechanical seal or an associated component that is distal from that shaft.

[0019] As used herein, the terms "stationary device" and / or "stationary surface" are intended to include any suitable stationary structure that houses a shaft or rod to which a seal with a gland is secured. One of ordinary skill in the art should also understand that a gland assembly can form part of a mechanical seal or part of a stationary device.

[0020] As used herein, the terms "process media" and / or "process fluid" generally refer to a media or fluid that is being transferred through a stationary device. In a pump application, for example, the process media is the fluid being pumped through the pump housing.

[0021] As used herein, the term "gland" is intended to include any suitable structure that enables, facilitates, and aids in the securing of a mechanical seal to a stationary device, and that simultaneously at least partially surrounds or houses one or more seal components. Optionally, the gland can also provide fluid access to the mechanical seal.

[0022] As used herein, the term "mechanical seal" is intended to include various types of mechanical seals, including single seals, split seals, tandem seals, double seals, concentric seals, gas seals, spiral seals, solid seals, split seals, and other known seal types and configurations.

[0023] As shown in FIGS. 1-3, the mechanical seal 10 of the present invention includes an annular holder assembly 20, an annular rotating seal ring 90, an annular stationary seal ring 100, and additional annular sealing elements, all of which are disposed around a shaft 12. The holder assembly 20 is typically disposed within an annular gland (not shown) that is fixed to a stationary device, as is known in the technical field of the present invention. The rotating seal ring 90 has a seal face 92 configured to be disposed in sealing contact with the seal face 102 of the stationary seal ring 100. Further, the mechanical seal 10 includes one or more biasing elements, such as a spring 84, that is attached between the rear side or rear portion of the rotating seal ring 90 and the inner radial stepped surface of the holder assembly 20, and that applies a biasing force to the rear portion of the rotating seal ring 90.

[0024] The illustrated holder assembly 20 includes a body 22 having an inner surface 24 and an outer surface 26. The inner surface 24 has an inner fastener or screw opening 28 for attaching a fastener such as a pin or screw 30. The pin or screw 30 serves to couple the rotary seal ring 90 to the holder assembly 20. The inner surface 24 has an innermost seal groove 32 sized and configured for attaching a sealing element 80. The sealing element 80 provides a fluid-tight seal between the innermost portion in the axial direction of the holder assembly 20 and the shaft 12. The inner surface 24 also includes an outermost axial seal groove 34 for attaching a sealing element 82. The sealing element 82 provides a seal between the holder assembly 20 and the radially outer surface of the rotary seal ring 90. An additional sealing element 88 may be employed to effect a seal around the upper portion of the stationary seal ring 100.

[0025] Also, the body 22 of the holder assembly 20 includes a fastener receiving opening 36 formed between its outer surface 26 and inner surface 24. Specifically, the fastener receiving opening 38 extends completely between the inner and outer surfaces of the holder assembly 20. The fastener receiving opening 36 is sized and configured for attaching a fastener such as a screw 38. The outer surface 26 of the body 22 is disposed on both sides of the fastener receiving opening 36 and thus further includes a pair of seal element grooves 40 and 50 axially spaced along the outer surface 26. The grooves 40 and 50 are preferably disposed relatively adjacent to the fastener receiving opening 36. These grooves are sized and configured for attaching a part of an annular seal cover element 110. According to one embodiment, a plurality of fastener receiving openings 36 can be formed in the holder assembly 20. The screw 38 serves to position and attach the mechanical seal 10 at one or more selected locations and mechanically couple the holder assembly 20 to the shaft 12. The seal cover element 110 serves to minimize or prevent process fluid from leaking through the opening 36 past the screw 38.

[0026] As shown in FIG. 1-2, the groove 40 includes a groove bottom or floor surface 42 and a pair of opposing groove sidewalls 44A, 44B. Similarly, the groove 50 includes a groove floor surface 52 and a pair of opposing sidewalls 54A, 54B. The sidewalls of the grooves 40, 50 may be configured to be generally linear (i.e., generally extending perpendicular or radially), or may be angled with respect to the longitudinal axis of the holder assembly 20. The grooves 40, 50 may have the same size and shape, or may have different configurations.

[0027] As shown in FIG. 3, the seal cover element 110 comprises a body 112 having a pair of opposing legs 116, 118 joined to each other by an intermediate portion 114. The legs 116, 118 are formed at opposite ends of the seal cover element 110. The intermediate portion 114 has an upper surface 120 spaced both axially and radially (e.g., horizontally and vertically) from the upper surfaces 122 of the legs 116, 118. Similarly, the bottom surface 126 of the intermediate portion 114 is spaced both axially and radially (e.g., both horizontally and radially) from the bottom surfaces 128 of the leg portions 116, 118. Also, each of the legs 116, 188 includes sidewalls. For example, the leg 116 includes opposing sidewalls 132A, 132B, and the leg 118 includes opposing sidewalls 134A, 134B. These opposing sidewalls contact the bottom surface 128 and form relatively straight (e.g., 90-degree angle), rounded or curved corners or edges. The legs 118, 118 can have dimensions slightly larger than the dimensions of the grooves 40, 50 such that the legs form a friction or mechanical fit when received within the grooves. Further, the intermediate portion 114 has a length corresponding to the axial distance between the grooves 40 and 50. The seal cover element 110 can be made of any suitable elastic material and can be formed from an elastomeric material.

[0028] In operation, the mechanical seal 10 of the present invention may be assembled and then attached to a fixing device (not shown). During assembly, the rotating seal ring 90 is coupled to the holder assembly 20 by pins or set screws 30. The holder assembly 20 is axially positioned along the shaft 12 of the fixing device and tightened against it using set screws 38. To avoid leakage through the set screws 38, a sealing cover element 110 is placed over the set screws 38 and the corresponding fastener receiving opening 36, thereby forming a fluid-tight seal. To prevent the sealing cover element 110 from accidentally coming off or being shaken off from the mechanical seal 10 when the shaft rotates at a higher speed, the sealing cover element 110 can be stretched over the set screws 38. Specifically, the leg 116 is attached within the groove 50, and the leg 118 is attached within the groove 40. When the legs 116, 118 are attached or pressed within the grooves 40, 50, the intermediate portion 114 of the sealing cover element 110 will straddle or extend between the grooves 40, 50, covering the fastener receiving opening 36 and the set screws 38 attached thereto. That is, the bottom surface 128 of the leg 116 contacts the floor surface 52 of the groove 50, and the side walls 132A, 132B of the leg 116 contact the side walls 54A, 54B of the groove 50, respectively. Similarly, the bottom surface 128 of the leg 118 contacts the floor surface 42 of the groove 40, and the side walls 134A, 134B of the leg 118 contact the side walls 44A, 44B of the groove 40, respectively. This mounting or fitting mechanism of the sealing cover element 110 helps prevent fluid from passing through or leaking beyond the threaded holes of the set screw opening 36 and the associated set screws 38. The legs 116, 188 of the sealing cover element 110 are axially compressed when attached within the grooves 40, 50, eliminating the possibility of leakage from the set screws, and thus achieving a substantially fluid-tight and gap-free design.

[0029] Furthermore, the holder assembly 20 can be configured such that, as shown, the sealing cover element 110 is attached to the inner surface 24 rather than the outer surface 26 of its body 22. In this embodiment, the grooves 40, 50 are formed in the inner surface 24 on both sides of the fastener receiving opening 36. The grooves 40, 50 can be configured such that the legs 116, 188 of the sealing cover element 110 are axially pushed into the grooves. The side walls of the grooves 40, 50 can be configured to be generally linear (i.e., generally perpendicular or radially extending), or angled with respect to the longitudinal axis of the holder.

[0030] Based on the design and configuration of the sealing cover element 110, the sealing cover element can meet the spatial constraint requirements of the mechanical seal 10 and related fixing devices. Furthermore, by combining the sealing cover element 110 with other sealing elements, it contributes to the formation of a gap-free environment. This is essential for applications where the growth of microbacteria is not allowed.

[0031] The present invention also relates to a system and method for forming or fabricating a sealing element to create a design with substantially no gaps. That is, the sealing elements can be formed so as to substantially completely fill the grooves or channels that house them. In one example, the term "substantially completely" is intended to mean filling the grooves or channels with the sealing elements such that more than 95%, preferably more than 97%, of the grooves or channels are filled only with the sealing elements. A person skilled in the art should be able to easily determine the proportion of grooves or channels that need to be filled with the sealing elements in order to reduce the unfilled portion of the grooves as much as possible, based on the teachings herein and the use and environment of the mechanical seal. Furthermore, the sealing elements can have any selected shape and size, preferably not circular or elliptical.

[0032] In order to employ sealing elements 80 and 88 that fully correspond to each channel and groove and are mounted therein, and optionally a sealing cover element 110 and the like to form a gapless design, these elements usually need to be specially formed and configured. Such specially configured sealing elements are preferably configured or shaped (e.g., with complementary shapes) to fit the selected shape and outer profile of the corresponding groove. According to the present invention, in addition to the annular sealing elements 80 and 88, any other sealing elements of the mechanical seal 10, if desired, can be formed from an elastomeric material. The annular sealing element is preferably machined from an elastomeric raw material including, for example, an elastomeric tube. The forming process of the present invention enables very high flexibility, responsiveness, and reduction of tooling costs.

[0033] The mechanical seal 10 of the present invention employs specially designed and configured sealing elements such as sealing elements 80 and 88, which have various outer shapes and forms designed to greatly reduce or eliminate potential spaces or gaps in the channels or grooves where the sealing elements are installed. These specially formed and shaped sealing elements are installed in places where conventional O-rings or sealing elements have been used. When using conventional sealing elements, there may be undesired-sized spaces or gaps in the channel, making the conventional sealing elements unsuitable for their purpose. The sealing elements of the present invention are machined from a sealing raw material such as an elastomeric tube to ensure maximum manufacturing flexibility. The sealing elements of the present invention are configured to be substantially the same as the shape and size of the channel or groove, and further, depending on the shape and outer form of these sealing elements, the shape of the embedding groove, and / or the device design, they are designed to be compressed radially and / or axially within each groove. Therefore, these sealing elements serve to minimize, reduce, or eliminate potential gaps so that microbacteria cannot multiply. Also, this gapless design makes it easier and more thorough to clean the mechanical seal 10.

[0034] The sealing element 80 of the present invention is sized and configured to be substantially fully installed within a corresponding groove or channel 32, and the sealing element 82 is dimensioned and configured to be substantially fully installed within the groove 34. The seal elements 80, 82, and 88 can be made from a relatively soft or elastic elastomeric material. Specifically, the typical hardness of the elastomeric material is between about 70 Shore A and about 90 Shore A. Typical elastomeric materials suitable for use herein include, for example, synthetic elastomers including ethylene propylene (EP) and ethylene propylene diene methylene (EPDM), a type of synthetic rubber; fluoroelastomers including FKM and FPM as defined by ASTM International Standard D1418; perfluoroelastomers including FFKM; and tetrafluoroethylene propylene rubber including FEPM.

[0035] As shown in FIG. 4, the present invention includes a seal element forming system 140 for forming or fabricating an annular seal element for use with a mechanical seal 10. The forming system 140 includes a material source 142 that includes a source of elastomeric material. The elastomeric material is then conveyed or transferred to a winding machine 144 such that the raw material can be wound into any suitable shape and can include a generally elongated tube shape having a circular, oval, square, or rectangular cross-section. Such a tube preferably has a rectangular cross-section before machining. The winding machine 144 can be any conventional winding machine known in the art of the present invention. Next, the tube made of the raw material is exposed to heat from a heating unit 146 for heating the tube made of the raw material to a selected temperature over a selected time. The heating unit 146 can be a known type of heating unit that uses one or more heating elements. For example, the heating unit 146 can be a resistance heating unit or any other suitable known type of heating unit. The raw material tube is heated to a selected temperature or temperature range by the heating unit, and a generally substantially homogeneous product is formed. Not only the temperature or temperature range, but also the duration of heating can vary depending on the type of raw material employed by the system 140 and the type of mechanical seal 10. Next, the heated raw material tube can be coated with a suitable coating material by a coating unit 148. The coating material can be any suitable material, such as a resin material, such that when the heated raw material is coated, the coated material has sufficient rigidity for subsequent machining on any conventional chipping machine.

[0036] In this way, this coated material then has an outer resin layer that can be fixed, such as by clamping, to a conventional turning or lathe machine 150. Turning machines are standard machines in the relevant industry and do not require further explanation here. A turning machine can include a relatively sharp and hard metal turning or cutting tool (not shown), which can be used to machine or cut any kind of outer shape on a generally rectangular elastomeric tube. This turning preferably involves cutting or shaving material from the tube until the dimensions and outer shape of the tube meet the requirements of the sealing element necessary for a particular channel design. In addition to the lathe machine 150, any part of the other relevant parts of the forming system 140 can be coupled to an electronic device 160 that can be used to control the operation of any selected part of the forming system 140. For example, the electronic device can be used to control one or more of the winder 144, the heating unit 146, the coating unit 148, and / or the lathe machine 150. The electronic device 160 can be a computer, a server, a tablet, a smartphone, etc. As is known in the technical field of the present invention, the electronic device 160 can include a processor 162 and a storage or memory element 164 in addition to other elements such as a display, a user interface, and input elements (e.g., a keyboard, a mouse, etc.). The memory element 164 can store any selected application and software suitable for communicating with and / or operating one or more components of the system 140. For example, the lathe machine 150 can communicate with an electronic device 160 that can store software instructions for operating the lathe machine to cut or turn the material into any predetermined pre-stored shape.

[0037] In addition, the illustrated forming system 140 includes a cutting unit 152 that can include one or more cutting elements suitable for cutting the material. The cutting unit 152 is used to cut the turned material into individual annular or ring-shaped sealing elements. The cutting of the turned material by the cutting unit 152 can be performed in a chipless process using a relatively sharp cutting tool. The cutting unit using the cutting tool may form part of the lathe 150 or may be a separate component forming part of the cutting unit 152.

[0038] In operation, as shown in FIGS. 4-5, in step 170, the seal element forming system 140 can provide raw material via the material source unit 142. The material is preferably an elastomeric material that can be provided or supplied in any selected shape, such as a sheet. The elastomeric raw material is then wound, in step 174, by the winder 144 into a long structure or tube. Next, in step 174, the elastomeric tube is heated over a selected period of time to form a substantially homogeneous product.

[0039] Next, in step 176, the heated raw material tube can be coated with a suitable coating material by the coating unit 148. The coating material can be any suitable material, such as a resin material, such that when the heated raw material is coated, the coated material has sufficient rigidity for subsequent machining on any conventional chipping machine or lathe.

[0040] The outer resin layer enables the fixation and processing of the coating material by a turning machine or a lathe 150. Using the lathe 150, any type of outer shape can be processed or cut on a generally rectangular elastomer raw material. In step 178, in this turning, it is preferable to remove material from the tube by machining, engraving, cutting, or chipping until the outer dimensions and outer shape (e.g., contour) of the tube are geometrically consistent with or complementary to the dimensions of the channel or groove. For example, the coated material can be treated or machined along the outer surface to form the cross-sectional contours of the sealing elements 80, 82, and 88.

[0041] Also, the illustrated forming system 140 can include a cutting unit 152 including one or more cutting elements suitable for cutting the material, and this cutting unit may be incorporated into the lathe 150 or may be a separate and different unit 152. In step 180, the turned material is cut using the cutting unit 152 to become individual annular or ring-shaped sealing elements.

[0042] Therefore, it should be understood that the present invention can effectively achieve the above-described objectives, which are included in the objectives made clear from the foregoing description. Since certain changes can be made to the above configuration without departing from the scope of the present invention, all matters included in this description or shown in the accompanying drawings are intended to be construed as illustrative and not in a limiting sense.

[0043] Furthermore, the following claims are to be understood as covering all general and specific features of the present invention described herein, as well as all statements regarding the scope of the present invention.

Claims

1. A method for forming a sealing element of a mechanical seal, comprising the following sequential steps: wrapping a source of elastomeric material into a long tubular shape; heating the elastomeric material to form a homogeneous elastomeric material; coating the homogeneous elastomeric material with a resin material; placing the homogeneous elastomeric material coated with the resin material on a lathe to rotate the homogeneous elastomeric material coated with the resin material; forming the outer contour and shape of the sealing element in the shaped resin-coated elastomeric material by removing the resin material from the homogeneous elastomeric material coated with the resin material to form a shaped resin-coated elastomeric material; a method for forming a sealing element of a mechanical seal, comprising cutting the sealing element from the shaped resin-coated elastomeric material.

2. The method according to claim 1, wherein the elastomeric material comprises ethylene propylene (EP), ethylene propylene diene methylene (EPDM), fluoroelastomers including FKM and FPM defined in ASTM International Standard D1418, perfluoroelastomers including FFKM, and tetrafluoroethylene propylene rubber including FEPM.

3. The method according to claim 2, wherein the elastomeric material has a hardness between 70 Shore A and 90 Shore A.

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