JPH0234590A - seal mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a seal mechanism used in a mechanical seal or a floating seal, and a seal member for the seal mechanism. More specifically, the present invention is used in mechanical seals or floating seals, etc.
The present invention relates to a seal mechanism with stable friction characteristics during load fluctuations and a seal member for the seal mechanism.

[Prior art] A mechanism that is fixed to a shaft and used as a mechanism to prevent leakage from the shaft that rotates at high speed under high temperature and high pressure, as well as to prevent foreign matter such as water, mud, and sand from entering from outside. Sealing mechanisms such as mechanical seals and floating seals that prevent leakage by sliding the meeting surfaces of a rotating ring (driven ring) that rotates with the pump and a stationary ring (seat ring) that opposes it It is widely used in internal combustion engine-driven transmissions, upper and lower guide rollers that guide the belly band of tracked vehicles, guide wheels, traveling speed reducers, etc.

As an example of such a conventional seal mechanism, a floating seal used in a downstream wheel of a hydraulic excavator or the like will be described with reference to FIG.

In the figure, reference numeral 1 denotes a cylindrical stationary casing that is fixed to a frame 3 of a hydraulic shovel or the like with bolts 7 through screw holes 5. A rotating side casing 9 is disposed on the other end side of the stationary side casing 1, and a track link 11 of a crawler belt is brought into contact with the outer peripheral surface of the rotating side casing. When the track is driven, the rotating casing 9 moves around the axis 13. Lubricating oil 15 is inside the rotating side casing 9.
A space 16 is provided for storing. Further, a wear-resistant sleeve F is inserted at the interface between the rotating side casing 9 and the shaft 13.

Further, reference numeral 19 denotes a floating seal attached to the inner peripheral side of the opposing ends IB and 9B of each of the casings 1 and 9, and this seal 19 prevents the lubricating oil in each of the casings 1 and 9 from leaking to the outside. This also prevents dirt, mud, rainwater, etc. from entering into each of the casings 1 and 9.

The present inventors previously devised a sealing device as shown in FIG. 5 and filed an application (see Utility Application No. 0-140577).

In the figure, 21.21 is the end I of each casing 1, 9.
B, 9B are seal rings disposed on the inner surface side, and each seal ring 21 is formed of a corrosion-resistant light alloy material such as an aluminum alloy or a zinc alloy, and the seal rings 21 are located closer to the outer circumferential side on the surfaces facing each other in the axial direction. Ring grooves 21A, 21A each having a U-shaped cross section are provided. In each annular groove 21A, SiC, AJ2203. ZrO, Si3N
A sliding member 22 made of a ceramic material having corrosion resistance and wear resistance such as No. 4 is bonded with an elastic adhesive 23 to form a sliding sealing surface. Further, the outer peripheral surface 21B of each seal ring 21 has a concave curved shape,
and is formed to be inclined outward in the axial direction, and each casing 1
．． When each O-ring 25 is sandwiched between the inner circumferential surfaces IC and 9C of 9, the elastic force of each O-ring 25 applies a pressing force to each sliding seal surface to provide sealing performance. ing. This O-ring also has the function of buffering the transmission of shaft vibration to the sliding sealing surface that is brought into close contact with the O-ring.

Seal rings with sliding members made of ceramics are cheaper to manufacture than conventional seal rings made of special cast iron material with added high-grade materials such as molybdenum and vanadium, and the sliding surface is It has the advantage of being able to maintain constant surface contact.

[Problems to be Solved by the Invention] However, ceramic sliding members are susceptible to high load fluctuations, impact loads, heat generation due to constant friction during initial loading, seizure, localized loss of the sliding surface, damage to mating members, etc. The scope of use is limited.

Ceramic is a sintered body of fine particles with high hardness, low elasticity, and low toughness, and has a cross-sectional shape as shown in FIG. As shown in the figure, the surface of the ceramic is a non-smooth surface with many microscopic voids and irregularities, and is also wavy.

Therefore, when the sliding members are brought into sliding contact, as shown in FIG. This may result in the device fitting into the recess. For this reason, the coefficient of friction changes depending on the load, so the initial friction characteristics and the friction characteristics when the load changes are unstable, and high frictional force is generated locally, causing uneven rotation.

Furthermore, due to the low toughness of ceramics, small chipped particles may occur during localized loading, and when these particles enter the sliding sealing surface, the localized load increases significantly, sometimes causing damage to the mating component. Become.

Additionally, since ceramics are generally low thermal conductors, it is difficult for the heat generated due to localized high friction to diffuse or dissipate, which not only causes deterioration of sliding characteristics and seizure, but also causes the O-ring to thermally age and become deformed. be.

Therefore, an object of the present invention is to provide a seal member and a seal mechanism that have stable friction characteristics during load fluctuations.

[Means for Solving the Problems] In order to achieve the above object, the seal member of the present invention includes a seal ring having a sealing surface that rotates and slides relative to each other, and the sealing surface is made of a ceramic wear-resistant material. It is formed from a metal film plated on the sliding member.

The metal film is preferably plated on the wear-resistant material by electroless plating.

Further, the seal mechanism of the present invention includes a pair of seal rings, each of which is disposed on the inner surface of a relatively rotating casing, and whose surfaces facing each other in the axial direction serve as sliding seal surfaces, and at least one of the seal rings. In the seal mechanism, at least one sliding sealing surface of the seal ring is formed of a metal film plated on a ceramic wear-resistant sliding member.

The sealing mechanism of the present invention is preferably used for mechanical seals and/or floating seals.

[Function] As mentioned above, the seal member of the present invention has a metal film plated on the sliding surface of the ceramic wear-resistant sliding member, so
While fully demonstrating the basic characteristics inherent in ceramic sliding members that serve as fracture substrates, such as high load resistance, high wear resistance, low friction, and high corrosion resistance, The corrosion-resistant and highly thermally conductive metal film dramatically improves sliding properties, seal resistance, durability, and reliability.

[Example 1] Hereinafter, an example of the sealing member and sealing mechanism of the present invention will be explained in more detail with reference to the drawings. In the following embodiments, the same reference numerals are used for the same components as in the prior art shown in FIGS. 4 and 5 described above.

FIG. 1 is a schematic sectional view of an example of the seal member of the present invention.

As shown in the figure, an annular groove 2LA having a substantially U-shaped cross section is provided opposite to each other in the axial direction of the annular seal ring 21, and an elastic adhesive 2LA is provided in this groove.
3, a flat ring-shaped sliding member 22 is joined. A metal film 27 is plated on the sliding sealing surface of this sliding member.

Further, the outer peripheral surface 21B of the seal ring 21 has a concave curved shape,
Moreover, it is formed to be inclined outward in the axial direction.

The material of the seal ring itself is not an essential requirement of the present invention.

It can be constructed from commonly used corrosion-resistant metal materials such as aluminum alloy, zinc alloy, die-casting, and stainless steel. Special cast iron and steel, which are conventional seal ring forming materials, can also be used. In addition, reinforced plastics, engineering plastics, etc. can also be used.

Sliding members are SiC+ Al103w ZrO+ Si3
N4. It is made of a ceramic material with corrosion resistance and wear resistance, such as Sialon. Although not only ceramic materials but also other wear-resistant materials can be used, ceramics are most preferred in terms of cost and ease of manufacture.

As the adhesive for joining the sliding member to the seal ring, for example, a silicone-based elastic adhesive or the like can be used. This adhesive can be elastically deformed in response to the load stress that the sliding member receives. Naturally, elastic adhesives other than silicone-based adhesives can also be used. Such adhesives are well known to those skilled in the art. In addition to elasticity, the adhesive used in the present invention preferably also has oil resistance and heat resistance. The effects of using an elastic adhesive are explained in detail in the above-mentioned Japanese Utility Model Application No. 140577/1983.

Preferably, the metal film is deposited on the surface of the sliding member by electroless plating. The electroless plating method is a method in which metal ions in an aqueous metal salt solution are deposited on the surface of a support by a substitution reaction or an oxidation-reduction reaction without using electrical energy. For example, adding a reducing agent to an aqueous Ni salt solution,
Ni can be precipitated by its reducing power. Ni
In addition, 00% PdlAulAglSnlCLl% Z
Metals such as n can also be precipitated.

When metal is deposited using reduction electroless plating, a film with no pinholes, almost uniform thickness, and excellent corrosion and wear resistance is formed, regardless of the shape of the base material or substrate. Ru. It is also possible to bond to non-conducting materials such as ceramics and powder metallurgy products. Not only the above-mentioned single metals but also alloys can be plated.

The bath composition for reduction electroless plating consists of three types: metal salt, reducing agent, and buffering agent. As the metal salt, metal chlorides, sulfates, carbonates, nitrates, cyanides, etc. can be used. As the reducing agent, sodium hypophosphite, sodium hyposulfite, anhydrous sodium sulfite, hydrazine chloride, hydroquinone, formalin, etc. are used. Buffers include acetic acid, propionic acid, butyric acid, valeric acid, lactic acid,
Combinations of alkali salts such as glycolic acid, tartaric acid, citric acid, succinic acid, malonic acid, glutaric acid, adipic acid, formic acid are used. Since these concentrations depend on the operating conditions of the bath and the material to be plated, it is necessary to determine the optimum concentration on a case-by-case basis.

The optimal thickness of the bonded metal film is determined by the conditions of use, but - for boat fishing, the sliding surface roughness Rma of the sliding member used is
The thickness is preferably within the range of 0.5 to 3 times x. If the thickness of the bonded metal film is 0.5 times Rmax, the temperature will rise during sliding and the film will become sticky, which is not preferable.

On the other hand, if the thickness of the broken metal film is more than three times Rmax, the durability of the metal film decreases.

The seal member of the present invention is used in a pair of left and right seals, for example, in a seal mechanism as shown in FIG. 2(a). As shown in the figure, the bonded metal films 27 and 27 are in sliding contact with each other to ensure sealing performance. The O-ring 25 as a suppressing means is manufactured from metal, plastic, asbestos, synthetic rubber, tetrafluoroethylene resin, or the like. In the illustrated example, both seal rings have a rupture metal film, but depending on usage conditions, a seal mechanism may be implemented in which only one of the rings on the stationary side or the rotating side has a rupture metal film.

The seal ring suppression means is not limited to the O-ring type shown in FIG. 2(a). for example.

It is also possible to press the driven ring 31 with a spring 30 as shown in FIG. 2(b). For this reason, the rotating shaft 3
A stopper 33 for a spring 30 is screwed onto 2. In the figure, 34 is a casing, 35 is a fixed seat ring, and 38 and 37 are packings.

Further, as shown in FIG. 2(C), the bellows 38 can also press the driven ring 31.

A ring spring 40 is inserted between the bellows 38 and the stopper 39.
Fixed by The material of the bellows is synthetic rubber, tetrafluoroethylene resin, metal, etc. Although the one shown in FIGS. 2(b) and 2(C) presses the driven ring, it is also possible to press the seat ring 35 on the fixed side. In addition, magnetic collar fluid pressure or the like can be used as the pressing means.

As shown in FIGS. 2(a) to 2(C), the shape of the sealing member of the present invention can be changed as appropriate depending on the application and/or the specific configuration of the sealing mechanism. Regarding the classification of mechanical seals, see "New Mechanical Seals" by Akira Washida, 2, Nikkan Kogyo Shimbun, published December 25, 1980.
p, 6-p.

Please refer to 27 for details.

The temperature change of the sliding portion of the seal mechanism of the present invention shown in FIG. 2(a) was measured.

AJ! Ring-shaped ceramic plate consisting of 203 (thickness:
1.5+u+) Four sheets were electrolessly plated with Ni.

The composition of the plating bath is Ni sulfate 30g/λ9 sodium hypophosphite 12g/J! , Sodium acetate Bog/J, iQ degree 95
The temperature was ~98°C and the pH was 5.8. The plating results are summarized in Table 1 below.

and 1 (Note) The thickness of the broken metal film was measured at 4 points at 90° intervals.
It is shown as the average value.

The thickness of the metal film plated on the ceramic plates No. 1 and 2 is approximately 2.15 times the sliding surface roughness (Rmax) to 0.
．． 93 times, which is within the scope of the present invention.

On the other hand, the thickness of the metal film plated on the ceramic plates No. 3 and 4 is approximately 0.38 to 0.32 times the sliding surface roughness (Rmax), which is within the scope of the present invention. It's outside. Therefore, the seal mechanism of the present invention as shown in FIG. 2(a) is constructed by combining the ceramic plates No. 1 and 2, and the seal of the comparative example is constructed by combining the ceramic plates No. 3 and 4. The mechanism was constructed. Gap between casings is 4.0 + n1 Load surface pressure is 0.4 to 0.5 NPa,
The seal test was carried out for 18 hours under test conditions with a relative rotational speed of 1.3 m/s. By drilling a hole that reaches the ceramic plate from the outer peripheral side of the seal ring and inserting the thermocouple into this hole so that the tip of the thermocouple is in contact with the ceramic plate, the rotation of the sliding surface is controlled. Temperature changes were measured. The measurement results are summarized in Table 2 below.

(Note) The units of temperature, temperature rise, and initial temperature fluctuation are all in units, and the unit of maximum surface roughness after the test is μm.

As is clear from the results shown in Table 2, the seal member of the present invention has a plating thickness of 8 and 14 μm, a plating surface roughness Rmax of 8.6 and 8.9 μm, and a flatness of the sliding surface of 40 μm. Although the thickness was quite poor at 18 μm, there was no oil leakage, seizure, or other damage at the end of the test, and the plating film remained over the entire sliding surface.

Further, there was no rapid temperature rise immediately after the start of the test, and the temperature rose stably with a maximum fluctuation of 3.0°C, reaching a steady state in only 2 hours and 40 minutes. On the other hand, the sealing member of the comparative example has a thin plating film of 1.5 μm and cannot cover the unevenness of the surface of the ceramic sliding base material. In addition to the temperature increase, a long-term (1-1.5 hour) temperature change is observed. However, rapid temperature changes (approximately 150 to 200 degrees
), and the fluctuations remain relatively small. Although it is 1.5 μm thick, it is plated almost uniformly over the entire surface of the uneven surface of the ceramic sliding base material.
This seems to be because local contact is prevented and heat is diffused, and the contact surface changes due to load. It is thought that the plated metal on the contact surface of the convex portion was worn out at the beginning of the test and entered the concave portion. It is estimated that the abrasion metal powder was small and relatively soft, which prevented damage to the contact surface, expanded the contact surface as the test time progressed, and reached a stable state in about 6 hours.

Although the load conditions were constant in the above test, it is expected that high blood pressure on local sliding surfaces cannot be prevented in the event of sudden high blood pressure or rotational motion, so it is assumed that a certain plating thickness is required. However, in order to take advantage of the characteristics of ceramics for average high surface pressure and high-speed sliding, it is preferable that the plating thickness be as thin as possible.

A sealing mechanism consisting of the sealing member of the present invention No. I and No. 2 described above, and A JI20 without a plating film
A seal mechanism using a seal member made of three ceramic sliding members was used as a floating seal as shown in FIG. 4, and temperature changes on the sliding surface were measured. The temperature was measured using the same method as in the above test. The standard spacing of the casing is 31■, and the seal set load is 8
The rotation speed for 0 to 100 kg was 240 rpm. This was repeated for 10 hours in a cycle of forward rotation for 5 minutes, stop for 5 seconds, reverse rotation for 5 minutes, stop for 5 seconds, and forward rotation for 5 minutes.

The measurement results are shown in Figure 3.

As is clear from the figure, in the case of the floating seal with 11 seal members of the present invention, after the start of the test, the saturated temperature (
97.5℃). On the other hand, in the case of the floating seal made of the seal member of the control example without the plating film, a frictional sound started to be produced immediately after the start of the test, and a rapid temperature rise occurred, reaching 145°C.

During this time, the fricative sound continued, and as the temperature decreased, this fricative sound disappeared. after that,
The saturation temperature (97.5°C) was gradually reached.

In the above embodiments, the explanation has focused on applying electroless plating to the seal ring, but it is also possible to apply electroless plating to the ceramic bearing to improve the sliding characteristics.

[Effects of the Invention] As explained above, the sealing member of the present invention is produced by bonding a metal film to the surface of a sliding member made of a wear-resistant material such as ceramics by electroless plating, and removing the broken metal. The membrane is used as a sliding sealing surface.

For this reason, while fully demonstrating the basic characteristics inherent in the ceramic sliding member that serves as the fracture substrate, such as high load resistance, high wear resistance, low friction, and high corrosion resistance, it has high toughness and
The highly lubricious, highly corrosion resistant, and highly thermally conductive metal film dramatically improves sliding properties, sealing resistance, durability, and reliability.

A sealing member having such an electroless plated metal film can significantly improve sliding characteristics even if its surface has poor flatness.

The surface of a ceramic sliding member has many microscopic voids and irregularities. Conventional seal members made only of ceramic sliding members have deteriorated sliding characteristics due to voids and irregularities on the ceramic surface. In the present invention, the voids on the ceramic surface are filled by electroless plating, and the convex portions are further buried in the plating film.

For this reason, the seal member of the present invention is preferably used as a mechanical seal or a floating seal in places where usage conditions are severe, such as in muddy water. In particular, floating seals are susceptible to foreign matter entering through gaps in the casing. - Foreign matter that enters the sliding surface will damage the sliding surface for a long period of time. In contrast, with the seal member of the present invention, even if a minute foreign object were to enter the sliding sealing surface of the plating film through the gap in the casing, the plating film is softer than the foreign object. This reduces the risk of foreign matter becoming embedded in the plating film and damaging the sliding surface.

Although it has not been specifically confirmed through experiments, the seal member of the present invention has excellent lubricity, so it may be optimally used for non-lubricated sliding surfaces in outer space.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of the sealing member of the present invention, FIG. 2(a) is a schematic cross-sectional view showing an example of the sealing mechanism of the present invention, and FIG. Figure (C) is a schematic sectional view showing another example of the seal mechanism of the present invention, and Fig. 3 shows temperature changes on each sliding surface when the seal member of the present invention and the seal member of the control example slide. FIG. 4 is a partially cutaway sectional view showing an example of a device using a floating seal, and FIG. 5 is a schematic sectional view showing an example of a sealing device previously devised by the inventor. 6 is an enlarged schematic cross-sectional view of the ceramic sliding member,
FIG. 7 is an enlarged schematic sectional view showing the sliding contact state of each sliding surface of the ceramic sliding member. 1.9...Casing, IC, 9C...Inner peripheral surface, 2
5...0 ring, 21...Seal ring, 21A・
... Annular groove, 21B ... Outer peripheral surface, 22 ... Ceramic sliding member, 23 ... Elastic adhesive, 27 ... Broken metal film

Claims (6)

[Claims] (1) A seal comprising a seal ring having a sealing surface that rotates and slides relative to each other, the sealing surface being formed of a metal film plated on a ceramic wear-resistant sliding member. Element. (2) The sealing member according to claim 1, wherein the metal film is plated on the wear-resistant material by electroless plating. (3) A pair of seal rings, each of which is disposed on the inner surface of a relatively rotating casing, and whose surfaces facing each other in the axial direction serve as sliding seal surfaces, and applying a pressing force to at least one of the seal rings. 2. A sealing mechanism comprising: a sliding sealing surface of at least one of said sealing rings, wherein at least one sliding sealing surface of said sealing ring is formed of a metal film plated on a ceramic wear-resistant sliding member. (4) The sealing mechanism according to claim 3, wherein the metal film is plated on the wear-resistant material by electroless plating. (5) The sealing mechanism according to claim 3 or 4, wherein the sealing mechanism is used as a mechanical seal. (6) The seal mechanism according to any one of claims 3 to 5, characterized in that it is used as a floating seal.