CN112413129B - Method for preparing water-lubricated mechanical sealing surface in ultra-smooth state - Google Patents
Method for preparing water-lubricated mechanical sealing surface in ultra-smooth state Download PDFInfo
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- CN112413129B CN112413129B CN202011246993.2A CN202011246993A CN112413129B CN 112413129 B CN112413129 B CN 112413129B CN 202011246993 A CN202011246993 A CN 202011246993A CN 112413129 B CN112413129 B CN 112413129B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/26—Sealings between relatively-moving surfaces with stuffing-boxes for rigid sealing rings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/162—Special parts or details relating to lubrication or cooling of the sealing itself
Abstract
A method for preparing a water-lubricated mechanical sealing surface in an ultra-smooth state comprises the steps of preparing a pair of sealing rings, assembling friction surfaces of the pair of sealing rings serving as sealing surfaces oppositely to form a mechanical sealing assembly, completely covering the sealing surfaces of the mechanical sealing assembly by guide liquid, pressurizing the mechanical sealing assembly in the guide liquid and water environment to operate, and forming the water-lubricated mechanical sealing surface in the ultra-smooth state after running-in process under the action of a friction chemical principle. The invention can greatly reduce the leakage rate flowing through the sealing clearance under the condition of no abrasion.
Description
Technical Field
The invention relates to a method for preparing a water-lubricated mechanical sealing surface in an ultra-smooth state.
Background
The mechanical seal belongs to the class of rotary shaft seals, and has wide application in various industries such as chemical industry, petroleum, textile, transportation, electric power, agriculture and the like. The mechanical seal comprises two sealing rings which mate at an annular surface, one of which is rigidly mounted, commonly referred to as an uncompensated ring, and the other of which is flexibly mounted, commonly referred to as a compensated ring.
During the operation of the mechanical seal, one of the two sealing rings rotates along with the rotating shaft, and the other sealing ring is kept static. The compensating ring is pressed against the non-compensating ring surface by the elastic means and the hydrostatic pressure, and there is a liquid, usually a medium to be sealed, in the gap between the two sealing rings, forming a very thin liquid film.
The thickness of the liquid film is different according to different working states of the mechanical seal: the liquid film thickness of a typical non-contact type seal surface is about 10 μm, and the liquid film thickness of a contact type seal is usually less than 1 μm. In general, too large a thickness of the liquid film results in poor sealing effect and large leakage, while too small a thickness of the liquid film results in contact between the sealing surfaces and wear.
The thickness of the sealing liquid film is determined by the surface topography profile of the sealing surface. As shown in fig. 1, the sealing surface of the seal ring is usually ground and polished before assembly to remove local protrusions on the surface, so that the sealing surface is as smooth as possible to achieve a low roughness (Ra <0.2 μm) to prevent contact, collision and abrasion due to the local protrusions on the surface. And then the two sealing rings are precisely assembled to form a sealing pair. The lower limit of the sealing liquid film thickness is limited by the machining and assembling accuracy. Normally, the friction state of the seal surface is in a state of "full film lubrication + partial boundary lubrication", and the partial boundary lubrication state restricts further reduction in the seal liquid film thickness. For example, in a water-lubricated mechanical seal, the thickness of the seal liquid film cannot be less than 0.45 μm between seal faces having a surface roughness Ra =0.1 μm, otherwise large-area surface local contact and wear will occur.
In the above-described background, the leakage rate of the mechanical seal cannot be further reduced on the premise of ensuring that the seal surface is not worn to a large extent, because the thickness of the seal liquid film cannot be further reduced.
Disclosure of Invention
The invention aims to provide a method for preparing a water-lubricated mechanical sealing surface in an ultra-smooth state, which can greatly reduce the leakage rate flowing through a sealing gap under the condition of no abrasion.
In order to achieve the above object, the present invention provides a method for preparing a water-lubricated mechanical seal surface in an ultra-smooth state, comprising the steps of:
s1, preparing a pair of sealing rings, wherein one sealing ring is used as a non-compensation ring, and the other sealing ring is used as a compensation ring;
s2, taking the friction surfaces of the pair of sealing rings as sealing surfaces to be oppositely assembled to form a mechanical sealing assembly, wherein the sealing surface of the mechanical sealing assembly is completely covered by guide liquid;
and S3, pressurizing and operating the mechanical sealing assembly in a guide liquid and water environment, and forming the water-lubricated mechanical sealing surface in an ultra-smooth state after running-in process under the action of a tribochemical principle.
The sealing ring is made of silicon carbide ceramic or silicon nitride ceramic.
The guiding liquid is a suspension containing silicon dioxide nano-particles.
The step S1 includes the steps of:
preparing a pair of seal rings which are not subjected to grinding and polishing, and grinding opposite surfaces of friction surfaces of the two seal rings;
and (3) cleaning the friction surface of the sealing ring by using an organic solution with a volatilization characteristic and an ultrasonic cleaning device, and standing and naturally drying.
The organic solution adopts ethanol or acetone.
In the step S2, firstly, a guide liquid is dripped on the sealing surface of the sealing ring, and then the sealing ring is assembled;
dripping guide liquid on the friction surface of one sealing ring, so that the guide liquid covers the friction surface by 100%;
and the friction surfaces of the two sealing rings are assembled oppositely to form a mechanical sealing assembly, a friction gap is formed between local protrusions on the surfaces of the friction surfaces of the two sealing rings, and after the assembly is finished, guide liquid is filled in the friction gap.
In the step S2, the sealing ring is assembled firstly, and then the guiding liquid is dripped into the sealing surface of the sealing ring;
assembling the friction surfaces of the two sealing rings oppositely to form a mechanical sealing assembly, wherein a friction gap is formed between local surface bulges on the friction surfaces of the two sealing rings;
and injecting the guide liquid into the mechanical seal assembly, so that the guide liquid covers the friction surface of the seal ring by 100% and fills the friction gap.
In step S3, the method for performing pressurized operation on the mechanical seal assembly in the guide fluid and water environment includes the following steps:
applying water flow back pressure to the mechanical sealing assembly to a basic pressure value, starting the rotating shaft to reach a rated rotating speed, driving one sealing ring in the mechanical sealing assembly to rotate along with the rotating shaft, and keeping the friction surfaces of the two sealing rings in a mutual pressing state;
keeping the rated rotating speed of the rotating shaft, and gradually boosting the water flow back pressure to the highest pressure value by fixed pressure steps;
and (4) keeping the rated rotating speed of the rotating shaft at the highest pressure value until the fluctuation range of the detected friction coefficient, the detected leakage rate and the detected power loss is simultaneously less than 0.1%, and stopping rotating.
The base pressure value is 0.1-0.2 MPa, and the highest pressure value is 125-130% of the base pressure value.
And taking 5-25% of the basic pressure value as a pressure step, gradually increasing the water flow back pressure, and keeping the rotation of the rotating shaft on each pressure platform for more than or equal to 2 minutes until the pressure is increased to the highest pressure value.
The water-lubricated mechanical sealing surface in the super-slippery state prepared by the invention can reach the super-slippery state in water environment, the thickness of a liquid film is in the order of magnitude of 0.1 mu m, the friction coefficient is far lower than 0.01, and the friction surface has no observable abrasion. Such a mechanical seal in an ultra-smooth state can greatly reduce the rate of leakage through the seal gap without wear.
Drawings
Fig. 1 is a schematic view showing the processing history and the operating state of a conventional mechanical seal.
Fig. 2 is a schematic diagram of a method for preparing a water-lubricated mechanical sealing surface in an ultra-smooth state provided by the invention.
Fig. 3 is a schematic structural view of a water lubricated mechanical seal surface in a super-slippery state.
Detailed Description
The preferred embodiment of the present invention will be described in detail below with reference to fig. 2 to 3.
The present invention applies the "super-slip" phenomenon in tribology to water lubricated mechanical seals. The phenomenon of "ultra-slip" means that when two objects are in contact and move relatively, the friction force between the two objects is extremely small and negligible, and the friction coefficient is usually required to be in the order of one thousandth to one ten thousandth. In the "super-slip" phenomenon of water lubrication, the friction pair material is silicon carbide ceramic or silicon nitride ceramic, the liquid film thickness is in the order of 0.1 μm, the friction coefficient is far lower than 0.01, and the friction surface has no observable wear. Such mechanical seals in an "over-run" condition can substantially reduce the rate of leakage through the seal gap without wear. This is because the thickness of the liquid film is extremely small, 10 times smaller than usual.
In one embodiment of the present invention, as shown in fig. 2, there is provided a method of preparing a water-lubricated mechanical seal surface in an ultra-slippery condition, comprising the steps of:
s1, preparing a pair of sealing rings made of silicon carbide materials, wherein one sealing ring is used as a non-compensation ring, and the other sealing ring is used as a compensation ring;
s2, taking the friction surfaces of the pair of sealing rings as sealing surfaces to be oppositely assembled to form a mechanical sealing assembly, wherein the sealing surface of the mechanical sealing assembly is completely covered by guide liquid;
and S3, pressurizing the mechanical seal assembly in guide liquid and water environment, and forming a water-lubricated mechanical seal surface in an ultra-smooth state after running-in process under the action of a friction chemical principle.
Further, the step S1 includes the steps of:
s1.1, preparing a pair of sealing rings made of silicon carbide materials, wherein the friction surfaces of the two sealing rings keep the original rough state (no grinding and polishing) after sintering, and grinding the opposite surfaces (namely the supporting surfaces of the circular rings) of the friction surfaces of the two sealing rings to enable the surface profile degree to reach 5 mu m;
and S1.2, cleaning the friction surface of the sealing ring by using an organic solution which has a volatile characteristic and is commonly used for surface cleaning, such as ethanol or acetone, and standing for natural air drying.
In the step S2, the guiding liquid may be dropped on the sealing surface of the sealing ring first, and then the sealing ring is assembled, or the sealing ring may be assembled first, and then the guiding liquid is dropped on the sealing surface of the sealing ring.
When the guiding liquid is dropped first, the step S2 includes the steps of:
s2-1.1, dripping guide liquid on the surface of the friction surface of one sealing ring to enable the guide liquid to cover the friction surface by 100%; the guiding liquid is a suspension containing silicon dioxide nanoparticles, can be used as a buffer layer between the contact surfaces of the two sealing rings, and can provide necessary silicon dioxide for achieving an ultra-smooth state;
s2-1.2, assembling the friction surfaces of the two sealing rings oppositely to form a mechanical sealing assembly, wherein the friction surfaces of the two sealing rings form a friction pair, namely a sealing pair; a friction gap is formed between local surface bulges on the friction surfaces of the two sealing rings; need prevent in the assembling process that guide liquid from flowing out the sealed face of sealing ring, after the sealing ring installation, guide liquid should be full of in the friction clearance of mutually supporting.
When the seal ring is first assembled, step S2 includes the steps of:
s2-2.1, assembling the friction surfaces of the two sealing rings relatively to form a mechanical sealing assembly, wherein the friction surfaces of the two sealing rings form a friction pair, namely a sealing pair;
and S2-2.2, injecting guiding liquid into the mechanical seal assembly, so that the guiding liquid can cover the friction surface of the seal ring by 100% and fill the friction gap.
The step S3 includes the steps of:
s3.1, mounting the mechanical seal assembly into a mechanical seal test loop or a pump product;
s3.2, a water injection loop is injected into a mechanical seal test loop or a mechanical seal of a pump product to pressurize to a basic pressure value of 0.1-0.2 MPa, a rotating shaft is started to reach a rated rotating speed, one sealing ring in a mechanical seal assembly is driven to rotate along with the rotating shaft, and friction surfaces of the two sealing rings are kept in a mutually compressed state under the action of water flow backpressure;
s3.3, under the condition of keeping the rated rotating speed of the rotating shaft, gradually boosting the pressure to the highest pressure value by fixed pressure steps;
taking 5% -25% of a basic pressure value as a pressure step, increasing water flow back pressure step by step, and keeping the rotating shaft on each pressure platform to rotate for more than or equal to 2 minutes until the pressure is increased to a highest pressure value, wherein the highest pressure value is 125% -130% of the basic pressure value;
and S3.4, the rotation of the rotating shaft is kept at the highest pressure value until the detected fluctuation range of the friction coefficient, the leakage rate and the power loss is less than 0.1 percent at the same time, the rotation is stopped, and the sealing surface of the mechanical sealing assembly reaches an ultra-smooth state under the water lubrication condition.
As shown in fig. 3, when the mechanical seal assembly is pressurized to operate in water environment, one sealing ring in the mechanical seal assembly rotates along with the rotating shaft, the friction pair formed by the friction surfaces of the two sealing rings undergoes a running-in process in guide fluid and water environment, and local protrusions on the surface of the friction surface of the sealing ring are gradually ground flat under the action of the tribochemical principle to form a flat surface based on the tribochemical principle. Meanwhile, the guiding liquid, the water and the abrasive dust product formed in the friction chemical process generate sol, the sol is filled in local pits on the friction surface, and an oxygen-rich adhesion layer is formed through dehydration. The flat surface and the adhesion layer jointly form a water-lubricated mechanical sealing surface in an ultra-smooth state. The flat surface is mainly composed of a silicon carbide base material, and an extremely thin oxide layer having a thickness of about 20nm is present on the surface. In the ultra-slippery state, the flat surface, this "plateau" structure, acts as the main body support structure to carry normal loads. The "plateau" structures of the two friction surfaces are in close contact, the gap width between them being of the order of magnitude of 0.1 μm. The pits are distributed between the flat surfaces, the height of the pits is lower than that of the flat surfaces, the adhesion layer filled in the pits is the original surface of the silicon carbide parent material, and the adhesion layer is formed by dehydrating and curing silica sol and has higher oxygen content. In the super-slippery state, the pits bear only a small amount of normal load due to the low altitude, the silicon oxide compounds in the adhesion layer can be slowly hydrolyzed in water environment to generate silicic acid locally, and the normal load borne by the hard flat surface structure can be reduced by the pit structure filled with the soft sol, so that the abrasion life of the friction surface is prolonged.
The water-lubricated mechanical sealing surface in the super-slippery state prepared by the invention can reach the super-slippery state in water environment, the thickness of a liquid film is in the order of magnitude of 0.1 mu m, the friction coefficient is far lower than 0.01, and the friction surface has no observable abrasion. The mechanical seal in the ultra-smooth state can greatly reduce the leakage rate flowing through the sealing clearance without abrasion.
It should be noted that in the embodiments of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for convenience of describing the embodiments, and do not indicate or imply that the referred device or element must have a specific orientation, be configured and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.
Claims (9)
1. A method of preparing a water lubricated mechanical seal surface in a super-slippery condition, comprising the steps of:
s1, preparing a pair of sealing rings which are not ground and polished, grinding the opposite surfaces of the friction surfaces of the two sealing rings by using one sealing ring as a non-compensation ring and the other sealing ring as a compensation ring, cleaning the friction surfaces of the sealing rings by using an organic solution with a volatilization characteristic by using an ultrasonic cleaning device, and standing and naturally air-drying;
s2, taking the friction surfaces of the pair of sealing rings as sealing surfaces to be oppositely assembled to form a mechanical sealing assembly, wherein the sealing surface of the mechanical sealing assembly is completely covered by guide liquid;
and S3, pressurizing and operating the mechanical sealing assembly in a guide liquid and water environment, and forming the water-lubricated mechanical sealing surface in an ultra-smooth state after running-in process under the action of a tribochemical principle.
2. The method for preparing a water-lubricated mechanical seal surface in a super-lubricious condition of claim 1 wherein the material of the seal ring is silicon carbide ceramic or silicon nitride ceramic.
3. The method for preparing a water-lubricated mechanical seal surface in a super-slippery state according to claim 1, wherein the guiding liquid is a suspension containing silica nanoparticles.
4. A method of preparing a water-lubricated mechanical seal surface in a super-slippery state according to claim 2 or 3, wherein the organic solution is ethanol or acetone.
5. The method for preparing a water-lubricated mechanical sealing surface in a super-slippery state according to claim 4, wherein in the step S2, a guiding liquid is dropped on the sealing surface of the sealing ring, and then the sealing ring is assembled;
dripping guide liquid on the friction surface of one sealing ring, so that the guide liquid covers the friction surface by 100%;
and the friction surfaces of the two sealing rings are assembled oppositely to form a mechanical sealing assembly, a friction gap is formed between local surface bulges on the friction surfaces of the two sealing rings, and after the assembly is finished, guide liquid is filled in the friction gap.
6. The method for preparing a water-lubricated mechanical seal surface in a super-slippery state according to claim 4, wherein in the step S2, the seal ring is assembled, and then the pilot liquid is dripped into the seal surface of the seal ring;
assembling the friction surfaces of the two sealing rings oppositely to form a mechanical sealing assembly, wherein a friction gap is formed between local surface bulges on the friction surfaces of the two sealing rings;
and injecting the guide liquid into the mechanical seal assembly, so that the guide liquid covers the friction surface of the seal ring by 100% and fills the friction gap.
7. The method for preparing a water-lubricated mechanical seal surface in a super-slippery state according to claim 5 or 6, wherein in the step S3, the method for performing pressurized operation on the mechanical seal assembly in a pilot fluid and water environment comprises the following steps:
applying water flow back pressure to the mechanical sealing assembly to a basic pressure value, starting the rotating shaft to reach a rated rotating speed, driving one sealing ring in the mechanical sealing assembly to rotate along with the rotating shaft, and keeping the friction surfaces of the two sealing rings in a mutual pressing state;
keeping the rated rotating speed of the rotating shaft, and gradually boosting the water flow back pressure to the highest pressure value by fixed pressure steps;
and (4) keeping the rated rotating speed of the rotating shaft at the highest pressure value until the fluctuation range of the detected friction coefficient, leakage rate and power loss is less than 0.1 percent at the same time, and stopping rotating.
8. The method for preparing a water-lubricated mechanical seal surface in an ultra-smooth state according to claim 7, wherein the base pressure value is 0.1 to 0.2MPa, and the maximum pressure value is 125 to 130% of the base pressure value.
9. The method for preparing a water-lubricated mechanical seal surface in an ultra-smooth state according to claim 7, wherein the water flow back pressure is increased step by step with a pressure step of 5% to 25% of a base pressure value, and the rotation of the rotary shaft is maintained at each pressure platform for 2 minutes or more until the pressure is raised to a maximum pressure value.
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| CN202011246993.2A CN112413129B (en) | 2020-11-10 | 2020-11-10 | Method for preparing water-lubricated mechanical sealing surface in ultra-smooth state |
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| CN112413129B true CN112413129B (en) | 2023-03-14 |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101663495A (en) * | 2007-04-20 | 2010-03-03 | 株式会社荏原制作所 | Bearing or seal using carbon-based sliding member |
| JP2010173927A (en) * | 2009-02-02 | 2010-08-12 | Toshiba Corp | SiC-BASED SINTERED COMPACT RING FOR MECHANICAL SEAL DEVICE, METHOD FOR MANUFACTURING THE SAME, AND MECHANICAL SEAL DEVICE AND LIGHT-WATER REACTOR PLANT |
| CN106483032A (en) * | 2016-09-18 | 2017-03-08 | 清华大学 | A kind of realize the break-in method that water lubrication joins secondary ultra-low friction |
| CN107407421A (en) * | 2015-03-20 | 2017-11-28 | 伊格尔工业股份有限公司 | The mechanically-sealing apparatus and its slip ring used in water environment |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20130209777A1 (en) * | 2007-04-25 | 2013-08-15 | Nippon Pillar Packing Co., Ltd. | Ceramics sliding member for use in pure water |
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- 2020-11-10 CN CN202011246993.2A patent/CN112413129B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101663495A (en) * | 2007-04-20 | 2010-03-03 | 株式会社荏原制作所 | Bearing or seal using carbon-based sliding member |
| JP2010173927A (en) * | 2009-02-02 | 2010-08-12 | Toshiba Corp | SiC-BASED SINTERED COMPACT RING FOR MECHANICAL SEAL DEVICE, METHOD FOR MANUFACTURING THE SAME, AND MECHANICAL SEAL DEVICE AND LIGHT-WATER REACTOR PLANT |
| CN107407421A (en) * | 2015-03-20 | 2017-11-28 | 伊格尔工业股份有限公司 | The mechanically-sealing apparatus and its slip ring used in water environment |
| CN106483032A (en) * | 2016-09-18 | 2017-03-08 | 清华大学 | A kind of realize the break-in method that water lubrication joins secondary ultra-low friction |
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