CN111677864B - Split type mechanical seal and sealing method for split contact interface thereof - Google Patents

Split type mechanical seal and sealing method for split contact interface thereof Download PDF

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CN111677864B
CN111677864B CN202010600117.9A CN202010600117A CN111677864B CN 111677864 B CN111677864 B CN 111677864B CN 202010600117 A CN202010600117 A CN 202010600117A CN 111677864 B CN111677864 B CN 111677864B
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ring
split
static
movable
mechanical seal
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CN111677864A (en
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孙见君
倪兴雅
马晨波
於秋萍
苏徐辰
蔄志鹏
王琳娜
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Nanjing Forestry University
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Nanjing Forestry University
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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
    • F16J15/30—Sealings between relatively-moving surfaces with stuffing-boxes for rigid sealing rings with sealing rings made of carbon
    • 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
    • F16J15/34—Sealings between relatively-moving surfaces with slip-ring pressed against a more or less radial face on one member
    • F16J15/3436—Pressing means
    • F16J15/3452—Pressing means the pressing force resulting from the action of a spring
    • 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
    • F16J15/34—Sealings between relatively-moving surfaces with slip-ring pressed against a more or less radial face on one member
    • F16J15/3496—Sealings between relatively-moving surfaces with slip-ring pressed against a more or less radial face on one member use of special materials

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  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mechanical Sealing (AREA)

Abstract

The patent discloses a split mechanical seal and a sealing method thereof, wherein the split mechanical seal still has good sealing capability when a gap is generated on a split interface of a sealing ring in a heated or pressure-bearing state. This subdivision formula mechanical seal includes the quiet ring of subdivision formula rotating ring, subdivision formula, the quiet ring of subdivision formula constitute end face dynamic seal, its characterized in that through the sealed end face laminating with the quiet ring of subdivision formula: the split type movable ring and the split type static ring are respectively provided with 2 half rings, 2 split surfaces of each half ring are positioned in the same plane, namely the central angle is 180 degrees, a thin layer of high polymer material is respectively attached to 2 split surfaces of one half ring of each of the movable ring and the static ring, and 2 split surfaces of the other half ring of each of the movable ring and the static ring are smooth substrate split surfaces. The sealing method is characterized in that load is applied to 2 semi-rings, so that the porosity of a split contact interface of the movable ring and the static ring is smaller than a percolation threshold value 0.3116, the axial single-side polymer overflow amount is smaller than 0.223 mu m, and the radial single-side polymer overflow amount is smaller than 0.447 mu m.

Description

Split type mechanical seal and sealing method for split contact interface thereof
Technical Field
The invention belongs to the technical field of sealing, and particularly relates to a split mechanical seal which is suitable for improving and improving the performance of the split mechanical seal for a rotating shaft of rotating mechanical equipment such as various compressors, centrifugal pumps, reaction kettle stirrers and the like and reducing the leakage of media in the mechanical equipment.
Background
The mechanical seal is used as a dynamic seal for a rotating shaft, and is widely applied to devices in the fields of electric power, ships, aerospace, petrochemical industry and the like due to simple structure and stable performance. But the end face friction abrasion generated by the relative rotation between the movable ring and the static ring can cause the failure of the mechanical seal. The relevant data show that 40% to 50% of the workload in the maintenance of the machine equipment is used for the maintenance of the shaft seal, and about 70% of the maintenance cost is spent on dealing with the sealing failure of the relevant machine. However, the quick-wear parts of the mechanical seal, namely the movable ring and the static ring, are closed rings and are sleeved on the rotating shaft in a penetrating way, and when the quick-wear parts are disassembled, repaired or replaced, a matching piece at the shaft end needs to be disassembled, so that the engineering quantity is large, the time consumption is long, and the cost is high. Therefore, since the early 90 s of the last century, research on a split mechanical seal with a simple structure and convenient installation has been started.
As can be seen from the prior art, the sealing method of the split surface of the sealing ring can be divided into three types: one is to separate the brittle whole ring in cross-section (Sato T, Okubo H. split mechanical seal: US,2010/0264597A1[ P ]. 2010-10-21; Nagai Y, Matsushita M, Yamauchi Y. mechanical seal including a porous seal ring: US,5067733[ P ]. 1991-11-26; Sangren J E, potter J S. Rotat-forming seal ring component kit for a mechanical seal ring: US,5913521[ P ].1999-06-22), which can achieve better sealing performance but only one set of mating, with no interchangeability (Bezak R. design and application of porous end seals [ J ] lubricating-sealing, 304, 34 + 9), and low finishing rate (1976, 304 + 319); the split type mechanical seal has the advantages that the split type surface is provided with a groove, an elastic-plastic sealing element (Wupeng, Duokao, Yesudan, Wudao rotation) is arranged in the groove, and an 103388580A [ P ] 2013-11-13 double-screw pump provided with the split type mechanical seal has good sealing performance, but the groove size and the sealing element compression amount are required to be strictly controlled so as to prevent the elastic-plastic sealing element from overflowing the movable and static ring sealing end surfaces or shrinking to the split surface where the movable and static ring sealing end surfaces can not be reached, and the movable and static ring sealing end surfaces and the static ring sealing end surfaces can not be jointed or a radial leakage passage is formed on the split surface close to the sealing end surfaces, as shown in figure 1; the last one is to process the Split surfaces smooth enough to achieve sealing by direct contact of the Split surfaces (Azabert H V. Split mechanical face seal: US 4576384[ P ]. 1986-03-18; Azabert H V. Universal Split mechanical seal: US 5571268[ P ]. 1996-11-05; James B, Harmes K L. Split mechanical face seal: US 6485023B2[ P ]. 2002-11-26; Suffolman, Severum, Severpazu, Pahanan, et al. Split mechanical seal with self-tightening sealing capability: CN 103307284B [ P ].2015-10-21), which is most popular for its simplicity, but when heated or under pressure, the elongation of the connecting bolt results in a reduction in the contact stress of the Split surfaces and results in a large leak rate, which induces a large void.
Disclosure of Invention
The invention aims to overcome the defects and provide the split mechanical seal which still has good sealing capability when a gap is generated on a split interface of the sealing ring in a heated or pressure-bearing state. The specific technical scheme is as follows:
the split mechanical seal comprises a split movable ring and a split static ring, wherein the split movable ring and the split static ring are jointed through a seal end face to form an end face movable seal, and the split mechanical seal is characterized in that: the split type movable ring and the split type static ring are respectively provided with 2 half rings, 2 split surfaces of each half ring are positioned in the same plane, namely the central angle is 180 degrees, a thin layer of high polymer material is respectively attached to the 2 split surfaces of one half ring of each of the movable ring and the static ring, and 2 split surfaces of the other half ring of each of the movable ring and the static ring are smooth substrate split surfaces.
The split mechanical seal is further improved, 2 split surfaces of one half ring of the movable ring and the static ring are respectively provided with 1 half ring stepped hole which is vertical to the split surfaces and has the diameter of first larger and then smaller, the large hole is a smooth hole, and the small hole is a threaded hole; 2 split surfaces of the other half ring of the moving ring and the static ring are provided with 1 smooth stepped hole of the half ring, the diameter of which is vertical to the split surfaces is first larger and then smaller, corresponding to the position of the hole on the split surfaces of the half ring of the moving ring and the half ring of the static ring; the 2 semi-rings of the movable ring and the static ring are respectively inserted into the positioning sleeve in the large hole close to the splitting surface, and then the split surface tensioning bolts are utilized to connect the movable ring and the static ring into a circular ring shape.
The split mechanical seal is further improved, the movable ring and the static ring are respectively provided with 2 semi-rings, 1 blind hole perpendicular to the split surfaces is respectively arranged at the corresponding positions of 2 split surfaces of each semi-ring, a positioning pipe is inserted to be butted by the split surfaces, and a hoop is tightly hooped on the outer diameter side to form the circular movable ring and the circular static ring.
The split mechanical seal is further improved, and the thickness of the attached high polymer material is 5-10 μm.
The split mechanical seal is further improved, the split movable ring and the split stationary ring are made of the same base material, namely SiC or WC, and the high polymer materials attached to the split surfaces are respectively PTFE or PEEK. When the split surface tension bolts are adopted for screwing 2 semi-rings to form the annular moving ring or the annular static ring, the tensile stress at the thread is large, if the moving ring or the static ring is easy to break when the impregnated graphite material is adopted, the moving ring and the static ring adopt the same SiC or WC material, the friction coefficient of the SiC and SiC or WC and WC auxiliary pair is not large, and the friction force between the moving ring and the static ring is reduced.
The split mechanical seal is further improved, the split movable ring base material is SiC or WC, the static ring base material is impregnated graphite, and the high polymer material attached to the split surface is PTFE or PEEK. When the split type movable ring or the static ring is tightly formed by hooping the hooping on the outer diameter side of the split type movable ring or the static ring, the outer surface of the ring is under the pressure action of the hooping structure, the impregnated graphite and SiC or WC materials can bear, the friction coefficient of the impregnated graphite and SiC or WC matched pair is small, the price of the impregnated graphite is low, and the price of the split type mechanical seal can be reduced.
A split contact interface sealing method of split mechanical seal is to couple split surfaces of a moving ring half ring and a static ring half ring adhered with high molecular material with split surfaces of smooth substrates of the moving ring half ring and the static ring half ring respectively, and apply load to 2 half rings of each of the split moving ring and the split static ring, so that the void ratio of the split contact interface of the moving ring and the static ring is smaller than a percolation threshold value 0.3116, the axial single-side polymer overflow amount is smaller than 0.223 mu m, and the radial single-side polymer overflow amount is smaller than 0.447 mu m.
In general, most of the split mechanical seals are of an external type, and in an operating state, a split surface tension bolt is extended under the action of process medium pressure and temperature, so that contact stress of the split surface is reduced to form a large void ratio, and leakage is induced. The PTFE or PEEK film layer is formed on 2 split surfaces of 1 half ring of each of the movable ring and the static ring by adopting PTFE or PEEK dispersion liquid spraying and drying treatment, has good toughness and certain rigidity, and when mechanical seal pressure bearing or heating and split surface tensioning bolts stretch, the PTFE or PEEK layer in a compression state elastically recovers, and the porosity between split contact surfaces is still kept to be less than 0.3116.
The split surface with the PTFE or PEEK film layer and the split surface of the relative semi-ring made of the base material are compressed to form a void ratio of 0-phi (phi is a number smaller than 0.3116) by controlling the split surface tension bolt or the clamping force, so as to ensure that the high molecular overflow amount of the end surface is smaller than 0.223 mu m and the void ratio is smaller than 0.3116, and the end surface sealing of the movable ring and the static ring is not influenced.
The overflow and void control principle is as follows:
dividing the polymer layer between the surfaces into a void ratio and an overflow amount (substrate, polymer base layer, rough layer) in the mounted state (see FIGS. 3 and 4)
Setting the total thickness of the polymer layers attached to 2 splitting surfaces of 1 moving ring semi-ring or static ring semi-ring as H, the maximum rough peak height H, the thickness of the polymer base layer as (H-H), the fractal dimension of the outline of the rough surface as D, and the scale coefficient as G; the split surfaces of 2 pieces of base materials of the other half ring matched with the half ring are smooth surfaces. Split plane bearing pcOn one hand, the micro-convex body of the polymer rough layer deforms under pressure, part of deformation of the micro-convex body is used for filling the gap between the contact interfaces of the splitting surfaces, and part of deformation overflows through the periphery of the splitting surfaces; on the other hand, the polymer base layer is thinned under pressure and overflows along the periphery of the splitting surface.
The rough peak profile before compression deformation can be used
Figure BDA0002558805180000031
Showing the profile of the top before and after compression deformation as shown in figure 5. For a given split interface of machined split and macromolecule-adhering split, it can be assumed that a smooth side is in contact with a rough side, and that the initial porosity φ0And the porosity after loading can be obtained according to the porosity formula in the reanalysis of the mechanical problem of the rough surface contact (report on mechanics, 2018,50(1): 68-77).
Figure BDA0002558805180000032
Wherein h is the maximum roughness peak height, and h ═ GD-1l2-D；
Figure BDA0002558805180000033
Is the sectional area on any section within the height h of the rough peak,
Figure BDA0002558805180000034
Figure BDA0002558805180000041
the area of the maximum rough peak base, and the diameter of the maximum rough peak base;
Figure BDA0002558805180000042
is the distribution density function of the cross section area of each rough peak at a certain height, and x is the radius of a cross section circle on any cross section in the height h of the rough peak.
For certain rough surfaces, the gap h ═ R at the time of plane pairing can be determined according to the rough surfaceσK to find the maximum roughness peak height, RσIs the root-mean-square roughness of the rough surface,
Figure BDA0002558805180000043
Lssample standard length, take L for the ground surfaces0.8mm (GB/T1031-2009); k is the integral coefficient of the contact rough surface, and k is-0.43D by numerical simulation2+ 1.18D-0.5. γ is a constant greater than 1, and for a surface that follows a normal distribution, γ is taken to be 1.5. From this,/, can be calculated.
Contact pressure p at a certain split planecUnder the action, the void ratio of the subdivision interface can be obtained by the following formula
Figure BDA0002558805180000044
Where δ is the compression amount of the maximum asperity peak and is determined by the deformation, i.e., the elastic deformation, the elastoplastic deformation, or the plastic deformation at the contact point.
When in use
Figure BDA0002558805180000045
All contact points of the sealing interface are in an elastic deformation state; when in use
Figure BDA0002558805180000046
The contact point of the sealing interface is in an elastic-plastic deformation state; when in use
Figure BDA0002558805180000047
All contact points of the sealing interface are in a state of plastic deformation.
aLIs the maximum contact area of the roughness peak, aecIs a critical elastic deformation area, apcIs the critical plastic deformation area, σyThe yield limit of the soft material on the rough split surface, and E is the composite elastic modulus of the split surface matrix and the soft material.
For aL＜aecCalculating the elastic deformation state of all contact points on the nominal area, and bearing the contact load fcFor elastic contact load fe
Figure BDA0002558805180000048
a is the asperity contact area, and n (a) is a function of the asperity contact area size distribution density.
For aec<aL<apcCalculating the elastic-plastic deformation state of the contact point on the nominal area, and calculating the real contact area ArFrom the elastic contact area AreAnd the elastic-plastic contact area ArepComposition, load f bornecIs the sum of the elastic contact load and the elastoplastic load, i.e.
Figure BDA0002558805180000051
For aL>apcCalculating the plastic deformation state of the contact point on the nominal area, and calculating the real contact area ArBy elastic contact area AreElastic-plastic contact area ArepAnd plastic contact area ArpComposition, load f bornecIs the sum of elastic load, elastoplastic load and plastic contact load, i.e.
Figure BDA0002558805180000052
In the formula (f)cTo calculate the contact load on the nominal area, fc＝pcAn，AnIn order to calculate the nominal area of the strip,
Figure BDA0002558805180000053
psi is calculated as the ratio A of the real contact area to the maximum contact area of the asperitiesr/aLThe correction coefficient of (2).
As is clear from the formulae (3) to (5), fcMaximum contact area with asperityLAnd (4) correlating. The constant contact pressure p can be obtained by the equations (6), (7) and (8)cThe porosity of (a).
(a)1/2＝(πr2)1/2＝2x (6)
Figure BDA0002558805180000054
Figure BDA0002558805180000055
Wherein r is the radius corresponding to the area of the contact point circle of the rough peak.
The sealing interface can be made leak-free at a void ratio of between 0 and 0.3116. The determination of pc also requires consideration of the condition that the overflow amount of the polymer layer on the split surface is not excessive and the pressure of the split contact interface is less than the allowable stress of the attached polymer material.
The elastoplastic deformation of the polymer layer under pc consists of a rough layer and a base layer.
If a rough layer having a porosity phi and a thickness delta is pressed out and the axial and radial run-out ratios of the split surfaces are respectively n/(m + n) and m/(m + n), then
(m+αm)(n+βn)(h-δ-Δ)＝mn(h-δ) (9)
In the formula, m and n are the axial and radial sizes of the splitting surface respectively; thickness of pressed-out coarse layer with delta being void ratio phi
Δ＝(h-δ)ε (10)
In which epsilon is strain
pc＝Eε (11)
The thickness of the polymer substrate is (H-H), and the deformation amount lambda under pc is
λ＝(H-h)pc/E (12)
Considering that the length and width of the polymer base layer are consistent with those of the rough layer, the axial and radial overflowing amounts of the whole polymer layer are respectively α m and β n.
It can thus be seen that a given pcThere is an ε, α, β. The total deformation corresponding to the axial length of the splitting surface is α m, and the total deformation in the radial direction is β n, so that the overflow amount of each end in the axial direction of the splitting surface is 0.5 α m, and the overflow amount of each end in the radial direction is 0.5 β n.
Considering the machining requirement of the end face of the mechanical seal, namely the end face roughness Ra of the hard ring1Less than or equal to 0.2 mu m, and soft ring end surface roughness Ra2The thickness of the sealing ring is less than or equal to 0.4 mu m, the comprehensive roughness Ra is less than or equal to 0.447 mu m, the pre-tightening load is adjusted, the overflow amount of the high molecular material of the split surface adhesion layer around the split surface is controlled, namely 0.5 alpha m is less than or equal to 0.223 mu m, 0.5 beta n is less than or equal to 0.447 mu m, so that the roughness of the end surface of the split surface joint does not exceed the roughness of other parts of the sealing end surface of the movable ring and the sealing end surface of the stationary ring, and the roughness of the inner cylindrical surface and the outer cylindrical surface of the split surface joint does not exceed the roughness of other parts of the inner diameter cylindrical surface of the movable ring and the outer diameter cylindrical surface of the stationary ring, and the normal work of the O-shaped auxiliary sealing ring in the inner hole of the movable ring and the outer cylindrical surface of the stationary ring is realized. The end faces of the moving ring and the static ring respectively overflow 0.223 mu m, the sum of the end faces is 0.446 mu m, and Ra of the end faces of the moving ring and the static ring which do not exceed other parts is 0.447 μm; and the inner and outer diameter sides only have the split surface with overflow, and the matched shaft or hole is smooth, so the radial overflow can reach 0.447 mu m, and does not exceed the roughness of the periphery.
② void ratio after splitting surface tension bolt elongation to rebound macromolecule layer between splitting surfaces under working state, namely applying medium pressure and temperature (see figure 16)
When the split mechanical seal is operated, the split surface tension bolt is stretched or the diameter of the hoop is increased due to the action of the pressure or temperature of a sealed medium, and the macromolecule layer generates the rebound quantity theta under the condition of reducing the contact stress. In order to ensure that the polymer matte does not leak after rebound, the residual porosity of the matte should be controlled to be still less than 0.3116.
In order to ensure the resilience of the polymer layer between the split surfaces after the split surface tension bolt extends, the pre-tightening load cannot be too large during installation, so that the microprotrusions are in an elastic or elastoplastic deformation state and cannot be deformed due to plastic deformation.
From the above analysis, it is found that when pc makes the void ratio of the polymer rough layer less than 0.3116, the polymer overflow amount of the end face less than 0.223 μm, the polymer overflow amount of the inner and outer diameter sides less than 0.447 μm, and the microprotrusions are in an elastic or elastoplastic deformation state, the split face sealing in the pre-tightening and working states can be realized.
The calculation flow of pc is shown in FIG. 17.
The invention has the beneficial effects that:
firstly, a planar split surface design is adopted, so that the manufacturing and the installation are convenient, and the sealing reliability of the split surface is improved;
secondly, a macromolecule layer is attached to the split surface matrix of the 1 moving and static ring semi-ring, a groove and a rubber pad arranged on the traditional split surface are abandoned, leakage caused by overflow or shrinkage of the rubber pad between the split surfaces is reduced, and the sealing effect of a sealing end surface and an auxiliary sealing ring is ensured;
compared with the traditional split mechanical seal, the split mechanical seal widens the heating or pressure bearing range of the split mechanical seal.
Drawings
Fig. 1 is a front view of a sealing ring made of polymer material shrunk on a sealing end face.
Fig. 2 is a schematic view of the sealing ring made of polymer material shrunk on the split surface (a-a cross section of fig. 1).
Fig. 3 is a front view of the split mechanical seal in a state where the tie bolt is tightened at the split surface.
Fig. 4 is a top view of the split mechanical seal with the tie bolts tightened at the split plane (cross-sectional view a-a of fig. 3).
FIG. 5 is a schematic diagram showing the profile change before and after the top of the maximum roughness peak is pressed.
Fig. 6 is a structure diagram of a half ring (a movable ring half ring or a stationary ring half ring) provided with 1 half ring stepped hole perpendicular to the splitting plane and having a diameter larger first and smaller second, the large hole being a unthreaded hole, the small hole being a threaded hole, and a high polymer material being attached thereto.
Fig. 7 is a structural view of a half ring (movable ring half ring or stationary ring half ring) provided with 1 smooth stepped hole of a half ring having a first larger diameter and a second smaller diameter perpendicular to a split surface.
Fig. 8 is a front view of a split seal ring (a dynamic ring or a static ring) consisting of 2 half rings shown in fig. 6 and 7.
Fig. 9 is a plan view of a split seal ring (a movable ring or a stationary ring) composed of 2 half rings shown in fig. 6 and 7 (a cross-sectional view a-a of fig. 8).
Fig. 10 is a structural view of a half ring (a moving ring half ring or a stationary ring half ring, a split surface of which is attached with a polymer layer) provided with 1 blind hole perpendicular to the split surface.
Fig. 11 is a structural view of a half ring (a moving ring half ring or a stationary ring half ring) provided with 1 blind hole perpendicular to a split surface.
Fig. 12 is a structural view of a sealing ring formed in an annular shape by inserting the 2-piece half rings shown in fig. 10 and 11 into a positioning pipe and tightening the same with a hoop.
Fig. 13 is a schematic view of an externally-mounted split mechanical seal that receives pressure of a fluid medium.
FIG. 14 is a front view of a split mechanical seal hoop in a tightened state.
Fig. 15 is a plan view showing a state where a split mechanical seal hoop is tightened (a cross-sectional view a-a of fig. 14).
Fig. 16 shows the deformation of the split surface polymer layer when the split surface tension bolt is elongated or the diameter of the hoop is increased in the operating state.
FIG. 17 is a pc calculation flow chart.
In the figure: the clamping screw comprises a shaft sleeve clamping screw hole 1, a rotating ring clamping screw hole 2, a split type rotating ring 3, a split type static ring 4, a static ring O-shaped ring 5, an anti-rotation pin 6, a static ring seat 7, a spring 8, an auxiliary sealing ring 9, a machine shell 10, a main shaft 11, a shaft sleeve 12, a rotating ring sealing ring 13, a split surface tensioning bolt 14, a positioning sleeve 15, a high polymer layer 16, a hoop 17, a hoop semi-ring 171, a hoop tensioning bolt 18, a hoop positioning sleeve 19, a semi-ring stepped hole 20, a semi-ring smooth stepped hole 21, a hoop stepped hole 22, a hoop smooth stepped hole 23, a blind hole 24 and a positioning pipe 25.
Detailed Description
The embodiments of the present invention will be described in detail below with reference to the drawings and examples.
Example 1 (dynamic ring half and static ring half are connected to a dynamic ring and a static ring by split surface tie bolts, respectively)
The split mechanical seal shown in fig. 6-9 and 13 comprises a split movable ring 3, a split stationary ring 4, split surface tension bolts 14, a positioning sleeve 15 and a high polymer material 16. The shaft sleeve 12 is connected with the main shaft 11 through a shaft sleeve set screw penetrating through the shaft sleeve set screw hole 1, the split type movable ring 3 is fixed on the shaft sleeve 12 through a movable ring set screw penetrating through the movable ring set screw hole 2, and the split type static ring 4 is arranged on the static ring seat 7 in an axial direction in a movable mode, but cannot rotate relative to the static ring seat due to the fact that the split type static ring 4 is connected through the anti-rotation pin 6 in the circumferential direction. The spring 8 is arranged between the static ring seat and the split static ring 4 and can push the split static ring 4 to move axially to be attached to the split movable ring 3. The split type movable ring 3 and the split type static ring 3 form end face movable seal by the joint of sealing end faces, a movable ring sealing ring 13 is adopted between the split type movable ring 3 and the main shaft 10 for sealing, and a static ring O-shaped ring 5 is adopted between the split type static ring 4 and the static ring seat 7 for sealing. An auxiliary sealing ring 9 is adopted to seal between the machine shell 10 and the static ring seat. The enclosure 10 has a sealed medium therein.
2 split surfaces of 1 half ring of the movable ring and the static ring are respectively adhered with a layer of polymer material 16 with the thickness of 5-10 mu m, and each split surface is provided with 1 half ring stepped hole 20 which is vertical to the split surface and has the diameter of first larger and then smaller, the large hole is a smooth hole, and the small hole is a threaded hole; 2 split surfaces of the other 1 semi-ring are smooth base split surfaces, and 1 semi-ring smooth stepped hole 21 with the diameter first larger and then smaller is formed in the position, corresponding to the holes in the split surfaces of the moving ring semi-ring and the stationary ring semi-ring, on each smooth base split surface; the semi-ring stepped holes 20 on the split surfaces of the movable ring semi-ring and the stationary ring semi-ring attached with the high polymer material 16 and the semi-ring smooth stepped holes 21 on the split surfaces of the smooth basal bodies of the movable ring semi-ring and the stationary ring semi-ring form mounting holes of the split surface tightening bolts 14 respectively.
The 2 semi-rings of the rotating ring and the 2 semi-rings of the static ring are respectively connected into a circular moving ring and a circular static ring by inserting a positioning sleeve 15 into a large hole close to a splitting surface and then utilizing a splitting surface tensioning bolt 14.
The split type movable ring and the static ring are respectively provided with 2 semi-rings, and 2 split surfaces of each semi-ring are in the same plane, namely the circle center angle is 180 degrees.
The split type moving ring and static ring base materials are both elastic modulus 4 multiplied by 105SiC with the MPa and the 2500MPa compressive strength, wherein the high polymer material attached to the splitting surface is PTFE with the elastic modulus of 1400MPa and the yield strength of 23 MPa; the rigidity of the split surface is maintained by the large elastic modulus and compressive strength of SiC, and the small elastic modulus and compressive strength of PTFE are beneficial to compression and elastic recovery of an adhesion layer before and after mechanical seal bearing or heating, so that the void ratio of the split surface is less than 0.3116 when a split surface tension bolt is tensioned or extended.
The split surfaces of the movable ring half ring and the stationary ring half ring which are attached with a layer of polymer material with the thickness of 5-10 mu m are respectively matched with the split surfaces of the smooth basal bodies of the movable ring half ring and the stationary ring half ring, split contact interfaces of the movable ring and the stationary ring are formed under the combined action of pre-tightening load connected by a split surface tightening bolt 14 or the pressure of a sealed medium, and the void ratio of the split contact interfaces of the movable ring and the stationary ring is smaller than the percolation threshold value 0.3116.
The pressure of a contact interface formed on the split surface by the combined action of the pre-tightening load of the split surface tension bolt and the pressure of a sealed medium is less than the allowable stress 23MPa of the attached PTFE, meanwhile, the axial single-side polymer overflow quantity of the polymer layer 16 is less than 0.223 mu m, as shown in figure 3, the overflow point D exceeds the sealing end surface by less than 0.223 mu m, the radial single-side polymer overflow quantity is less than 0.447 mu m, as shown in figure 4, the overflow point E exceeds the periphery of the sealing ring by less than 0.447 mu m. The layer 16 cannot have an axial constriction B as shown in fig. 1 and a radial constriction C as shown in fig. 2.
The pc on the split plane after tightening of the split plane stay bolt can be solved according to the flow shown in fig. 17. The method comprises the following specific steps:
firstly, measuring fractal dimension D and scale coefficient G of rough profile of attachment layer of subdivision surface, and calculating root mean square roughness RσMaximum asperity peak height h and substrate diameter;
② calculating and calculating the nominal area An
Thirdly, setting pc with the split surface tension bolt applied to the split surface and smaller than the allowable stress [ sigma ] of the high polymer material, and calculating the split surface void ratio by using the formulas (2), (3) or (4), (5) and the formulas (6), (7) and (8);
(iv) comparing whether the split surface void ratio is less than 0.3116? If so, the polymer overflow amount of the split surface is calculated according to the formulas (9), (10), (11) and (12). Otherwise, pc is reset.
Comparing whether the axial single-sided polymer overflow is less than 0.223 μm, and whether the radial single-sided polymer overflow is less than 0.447 μm? If so, calculating the contact stress and the void ratio of the split surface in the stretching state of the split surface tension bolt after applying medium pressure and temperature; otherwise, pc is reset.
Sixthly, comparing whether the split surface void ratio is less than 0.3116? If yes, record pc. Otherwise, pc is reset.
Record the void ratio less than 0.3116, axial single-side polymer overflow less than 0.223 μm, and radial single-side polymer overflow less than 0.447 μm pc range.
Example 2 (dynamic ring half and static ring half are tightened by a hoop to form a dynamic ring and a static ring, respectively)
Referring to the split mechanical seal shown in fig. 10-12 and 14-15, the main difference between this embodiment 2 and embodiment 1 is that:
the split type movable ring and the static ring are respectively provided with 2 semi-rings, 1 blind hole 24 vertical to the split surface is respectively arranged at the corresponding position of 2 split surfaces of each semi-ring, a positioning pipe 25 is inserted to be butted with the split surfaces, and a hoop 17 is added on the outer diameter side to hoop the movable ring and the static ring in a circular ring shape.
The hoop 17 includes two hoop half rings 171 around the outer circumference of a split dynamic or static ring. The two hoop half rings are circumferentially opposed but not in contact. 1 hoop stepped hole 22 with the first large diameter and the second small diameter perpendicular to the end face is formed in each of two circumferential end faces of one hoop semi-ring, the large hole is a unthreaded hole, and the small hole is a threaded hole; 1 hoop smooth stepped holes 23 with the diameter first larger and then smaller and then larger vertical to the end surface are arranged on the two circumferential end surfaces of the other hoop half ring corresponding to the hoop stepped holes 22; the hoop stepped bore 22 and the hoop smooth stepped bore 23 form a mounting bore for the hoop tension bolt 18.
The two hoop half rings are connected through inserting a hoop positioning sleeve 19 into a large hole close to the end face and then utilizing a hoop tensioning bolt 18 to clamp a circular movable ring and a circular static ring which are formed by the two movable ring half rings or the static ring half rings.
The split type movable ring base material has an elastic modulus of 6 multiplied by 105WC (grade YG6) with MPa and 4600MPa compressive strength, the static ring base material is elastic modulus of 1.5 multiplied by 105The impregnated furan resin graphite has the MPa and compressive strength of 120MPa, and the high polymer material attached to the splitting surface is PEEK with the elastic modulus of 3600MPa and the yield strength of 95 MPa.
The hoop pre-tightening load or the contact interface pressure formed on the split surface by the combined action of the hoop pre-tightening load and the pressure of the sealed medium is less than the allowable stress of 95MPa of the attached PEEK.
The other structure is similar to that of embodiment 1.
The pc solving procedure on the split plane after hoop tightening is similar to example 1.

Claims (6)

1. The utility model provides a subdivision formula mechanical seal, includes the quiet ring of subdivision formula rotating ring, subdivision formula, the quiet ring of subdivision formula constitute end face dynamic seal, its characterized in that through the laminating of sealed terminal surface: the split type movable ring and the split type static ring are respectively provided with 2 half rings, 2 split surfaces of each half ring are positioned in the same plane, namely the central angle is 180 degrees, a thin layer of high polymer material with the thickness of 5-10 mu m is respectively attached to the 2 split surfaces of one half ring of each of the movable ring and the static ring, and the 2 split surfaces of the other half ring are smooth substrate split surfaces.
2. A split mechanical seal as claimed in claim 1, wherein: 2 splitting surfaces of one half ring of each of the movable ring and the static ring are respectively provided with 1 half ring stepped hole which is vertical to the splitting surfaces and has a diameter which is larger firstly and then smaller, the large hole is a unthreaded hole, and the small hole is a threaded hole; 2 split surfaces of the other half ring of the moving ring and the static ring are provided with 1 smooth stepped hole of the half ring, the diameter of which is vertical to the split surfaces is first larger and then smaller, corresponding to the position of the hole on the split surfaces of the half ring of the moving ring and the half ring of the static ring; the 2 semi-rings of the movable ring and the static ring are respectively inserted into the positioning sleeve in the large hole close to the splitting surface, and then the split surface tensioning bolts are utilized to connect the movable ring and the static ring into a circular ring shape.
3. A split mechanical seal as claimed in claim 1, wherein: the corresponding positions of 2 splitting surfaces of each half ring of the movable ring and the static ring are respectively provided with 1 blind hole vertical to the splitting surfaces, positioning pipes are inserted to be butted with the splitting surfaces, and the hooping hoop on the outer diameter side is tightly connected to form the annular movable ring and the annular static ring.
4. A split mechanical seal as claimed in claim 1 or 2, wherein: the split type moving ring and the split type static ring are made of the same base material, SiC or WC, and the high polymer material attached to the split surface is PTFE or PEEK.
5. A split mechanical seal as claimed in claim 1 or 3, wherein: the split type moving ring is made of SiC or WC as a base material, the static ring is made of carbon graphite as a base material, and the high polymer material attached to the split surface is PTFE or PEEK.
6. A sealing method for a split contact interface of a split mechanical seal is characterized in that: the split surfaces of the movable ring half ring and the stationary ring half ring which are adhered with high polymer materials are respectively matched with the split surfaces of the smooth substrates of the movable ring half ring and the stationary ring half ring, and loads are applied to 2 half rings of each split movable ring and split stationary ring, so that the porosity of the split contact interface of the movable ring and the stationary ring is smaller than a percolation threshold value 0.3116, the axial single-side polymer overflow amount is smaller than 0.223 mu m, and the radial single-side polymer overflow amount is smaller than 0.447 mu m.
CN202010600117.9A 2020-06-28 2020-06-28 Split type mechanical seal and sealing method for split contact interface thereof Active CN111677864B (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07124970A (en) * 1993-10-29 1995-05-16 Kiipaa Kk Manufacture of split seal
CN101469773A (en) * 2007-12-25 2009-07-01 丹东克隆集团有限责任公司 Combined type magnetic mechanical sealing device
CN101910691A (en) * 2008-05-09 2010-12-08 伊格尔工业股份有限公司 Split mechanical seal
CN102829187A (en) * 2012-09-19 2012-12-19 江苏华青流体科技有限公司 Rear shaft sealing device provided with Hough moveable ring
CN208381314U (en) * 2018-07-06 2019-01-15 欧帕工业集团有限公司 Zero leakage apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07124970A (en) * 1993-10-29 1995-05-16 Kiipaa Kk Manufacture of split seal
CN101469773A (en) * 2007-12-25 2009-07-01 丹东克隆集团有限责任公司 Combined type magnetic mechanical sealing device
CN101910691A (en) * 2008-05-09 2010-12-08 伊格尔工业股份有限公司 Split mechanical seal
CN102829187A (en) * 2012-09-19 2012-12-19 江苏华青流体科技有限公司 Rear shaft sealing device provided with Hough moveable ring
CN208381314U (en) * 2018-07-06 2019-01-15 欧帕工业集团有限公司 Zero leakage apparatus

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