JP3555428B2 - Sealing device and method of manufacturing sealing device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sealing device having a function of allowing a fluid to flow or hold by a groove formed on a sliding surface of a lip portion, and a method of manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there have been various types of sealing devices for sealing a fluid such as a lubricating oil (oil). FIG. 5 shows an example of this type of sealing device.
[0003]
As shown in the figure, the sealing device 100 seals an annular gap between the shaft 200 and the cylindrical housing 300, and prevents fluid such as lubricating oil sealed in the sealed fluid side O from leaking to the atmosphere side A. That's what we do.
[0004]
As a schematic configuration of the sealing device 100, a metal ring 101, a sealing member 102 made of a rubber-like elastic material formed integrally with the metal ring 101, and a resin made of resin sandwiched between the metal ring 101 and the sealing member 102. And a seal member 103.
[0005]
The seal member 102 includes an outer peripheral sealing portion 102b that hermetically contacts the inner peripheral surface of the housing 300, a lip portion 102a that slides on and seals the shaft 200, and a radial portion 102c that connects the lip portion 102a and the outer peripheral sealing portion 102b. ing.
[0006]
The seal member 103 supports the root of the lip portion 102a of the rubber-like elastic seal member 102 to suppress excessive deformation of the lip portion 102a, and slides on the shaft 200 to exhibit sealing properties. .
[0007]
Therefore, the sealing member 103 is preferably made of a material having a certain flexural strength, and is a resin material having a predetermined flexibility (meaning that it is not hard), for example, a fluorine-based material such as PTFE (tetrafluoroethylene). It is made of resin material.
[0008]
Further, it is difficult for the sealing member 103 made of such a resin material to apply a uniform and high tension force to the sliding surface over the entire circumference, such as a lip made of a rubber-like elastic body, and it is difficult to apply a fluid. A groove 104 having a pumping action on the sliding surface for suppressing leakage is formed from the lip portion 103a to the bent portion 103b.
[0009]
The groove 104 has a structure that exerts a pump effect such that the fluid flows toward the sealing fluid side O when the sealing device 100 rotates relative to the shaft 200.
[0010]
In addition, when the sealing device 100 is applied to a position where the sealing device 100 normally rotates only in one direction with respect to the shaft 200 and does not rotate much in the other direction, the groove 104 is suitable for rotation in one direction. It is preferable to use a helical thread groove that efficiently exerts a pumping effect, and when applied to a part that rotates in both directions, a moderate pumping effect is exhibited for any rotation. It is also suitable to have a number of annular grooves.
[0011]
With such a configuration, an annular gap between the shaft 200 and the cylindrical housing 300 is sealed.
[0012]
As shown in FIG. 6 (see Japanese Patent Publication No. Sho 60-56618), a method of manufacturing the sealing member 103 made of a resin material includes an end surface of a resin cylindrical body such as PTFE having an inner diameter and an outer shape formed to predetermined dimensions. Next, after the thread groove is cut from the inner diameter side by the screw cutting means, the end of the resin cylindrical body is cut into a predetermined width by the cutting means to manufacture the flat washer-shaped seal member 103 (FIG. 6A). .
[0013]
The thread groove can be formed by pressing with a press in addition to the one formed by machining.
[0014]
Further, the manufactured flat washer-shaped sealing member 103 is formed by inserting a pressing jig 200J having substantially the same diameter as the shaft 200 fitted into the sealing device 100 into the inner diameter side of the sealing member 103 by pressing or the like, and forming the entire circumference. A lip portion 103a which is bent at a predetermined angle to serve as a sliding portion is formed (FIG. 6B).
[0015]
[Problems to be solved by the invention]
However, such a conventional sealing member 103 has the following problems.
[0016]
In other words, the method of manufacturing a sealing member in which a thread is cut into the resin cylinder and the end of the resin cylinder having the thread groove cut out is a one-item production method, and the production efficiency is low.
[0017]
In addition, as the thickness of the molded body of the resin cylinder increases, the production becomes more difficult as the thickness increases, and the cost of the material increases. Therefore, it becomes difficult to manufacture a seal member having a large inner diameter.
[0019]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the related art, and has as its object to achieve shaping of a thread groove without using mechanical processing or press working, and to enable production with high production efficiency. An object of the present invention is to provide a sealing device and a method of manufacturing the sealing device.
[0020]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a sealing device that has a seal member formed of a thermoplastic elastomer as a material and seals an annular gap between a housing and a shaft, wherein the seal member includes a radiation member. A plurality of regions having a plurality of helical regions having different elasticities according to the irradiation, comprising a sliding surface that slides on the shaft, and when the sliding surface bends in the axial direction of the shaft, the plurality of regions having different elasticities is provided. A minute groove is formed in a region having low elasticity in the region.
[0021]
As a result, the physical properties of the material in the specific region of the seal member, that is, the cross-linking state and elasticity can be selectively changed, and by using this characteristic, the deflection of the lip portion can be adjusted or the sliding surface of the lip portion can be adjusted. It is possible to form the fine irregularities to hold the fluid, or to make the fluid flow so as to enclose or discharge the fluid by operating the pump function.
[0022]
Further, it is possible to improve production efficiency without requiring machining to change the physical properties, and without requiring secondary molding due to the elasticity of the seal member itself.
[0027]
It is also preferable that the seal member is a flat washer-shaped annular member, and the inner diameter side is expanded in diameter while being bent in the axial direction to form a lip portion, and the inner peripheral side of the lip portion is used as a sliding surface.
[0028]
It is also preferred that the radiation is ionizing radiation.
[0029]
Further, it is preferable that the thermoplastic elastomer is a fluoroelastomer.
[0030]
In the method for manufacturing a sealing device, in the method for manufacturing a sealing device for sealing an annular gap between a housing and a shaft, a sealing member having a sliding surface that slides on the shaft is formed using a thermoplastic elastomer as a material. A plurality of spiral helical regions having different elasticities according to the irradiation of radiation are formed on the sliding surface, and the sliding surface is bent in the axial direction of the shaft to reduce the elasticity of the plurality of regions having different elasticity. It is characterized in that minute grooves are formed.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments to which the present invention is applied will be illustratively described below with reference to the drawings. However, the materials, shapes, relative arrangements, and the like of the components described do not limit the scope of the present invention to the configurations described in these embodiments unless otherwise specified.
[0032]
(Embodiment 1)
First, a method for manufacturing a seal member 1 to which the present invention is applied will be described with reference to FIG. The seal member 1 according to the first embodiment can be used in place of the seal member 103 of the sealing device 100 described with reference to FIG. Therefore, the same technology can be applied to the configuration and the assembling method of the sealing device other than the sealing member 1, and the description is omitted here.
[0033]
The material of the sealing member 1 uses a thermoplastic elastomer. By utilizing the characteristics of this material and combining the extruder 2 and the sheet die 3, the sheet 4 serving as the base of the seal member 1 is continuously formed (see FIG. 1A).
[0034]
The sheet 4 extruded from the sheet die 3 is punched into a donut shape by press working to form a flat washer-shaped annular member 5 (see FIG. 1B).
[0035]
Next, the annular member 5 is covered with a mask 7 having an opening 6 of a predetermined pattern shape, and is irradiated with radiation 9 by a radiation irradiator 8, so that a gap between the specific region irradiated with the radiation 9 and the other region is obtained. In (2), the physical properties of the materials are changed (see FIG. 1 (c)).
[0036]
As will be described in detail later, the pattern shape can be formed in any shape such as a spiral shape, a plurality of concentric circles, or a screw shape.
[0037]
In this embodiment, the physical properties of the material refer to a crosslinked structure of a thermoplastic elastomer, and the irradiation of the radiation 9 forms a crosslinked structure (crosslink density) higher than other regions.
[0038]
With such a change in the crosslinked structure, the elasticity changes at the same time, and the region irradiated with the radiation 9 has a high elasticity.
[0039]
As the thermoplastic elastomer used as the material of the seal member 1, for example, a block-type fluorine-based thermoplastic elastomer is used. As the soft segment (fluororubber), for example, vinylidene fluoride-hexafluoropropene-tetrafluoroethylene terpolymer, and as the hard segment (fluororesin), polyvinylidene fluoride, tetrafluoroethylene-ethylene copolymer, etc. Is formed. Further, a material in which carbon black is blended with a base polymer can be used.
[0040]
Further, it is preferable to use ionizing radiation in a band capable of efficiently generating a change in physical properties of various materials as the radiation 9 to be irradiated, and for example, an electron beam having an energy of about 150 eV to several MeV is used. In order to allow the electron beam to penetrate deeply, an electron beam having a high energy is required. However, when the electron beam is used for the sealing member 1 having a small thickness, a low energy electron beam of 300 KeV or less can be used.
[0041]
As the emission time, it is also possible to crosslink the material in a required time of 1 second or less by using, for example, an electron beam.
[0042]
Further, it is preferable that the atmosphere when the radiation 9 is irradiated be a vacuum state, a nitrogen gas atmosphere, or the like.
[0043]
The above-described manufacturing method can be formed into a line as a continuous process, and has a very high production efficiency as compared with a manufacturing method using a conventional cutting process.
[0044]
(Embodiment 2)
In the second embodiment, a usage pattern of the sealing member 1 manufactured such that the physical properties of the material are different between the specific area irradiated with the radiation 9 and the other area will be described.
[0045]
FIG. 2 is a diagram showing a groove formed by cross-link density distribution and its use form. FIG. 2A is a perspective view showing the seal member 1 to which the irradiation of radiation has been completed with its irradiation surface facing upward, and FIG. 2B is an enlarged perspective view showing a portion D2 thereof.
[0046]
FIG. 2C is a cross-sectional configuration explanatory view of the sealing device 20 incorporating the sealing member 1 in place of the sealing member 103 of FIG. 5, and FIG. 2D is an enlarged perspective view of a D3 portion thereof.
[0047]
As shown in FIGS. 2A and 2B, the irradiation region R1 irradiated with the radiation and the non-irradiated region R2 not irradiated with the radiation are formed in the sealing member 1, and the bridge formed by patterning is formed. A structure is formed, ie a patterned distribution of elasticity. In this embodiment, the non-irradiation region R2 is a plurality of annular regions arranged concentrically.
[0048]
Then, as shown in FIG. 2 (c), after the seal member 1 is assembled into the sealing device 20, when the sealing device 20 is mounted in the annular gap between the housing 300 and the shaft 200, the elasticity of the seal member 1 itself increases. The inner diameter portion 1a bends in the axial direction while expanding in diameter, and the portion facing the shaft 200 becomes the sliding surface 1b.
[0049]
On the sliding surface 1b, as shown in FIG. 2D, stress in the direction of the arrow (strain due to tensile stress in the axial and circumferential directions) is generated, and the elasticity is lower than that of the irradiation region R1. The deformation in the irradiation area R2 increases, and a minute groove M1 is formed in the non-irradiation area R2.
[0050]
The groove M1 can exert a fluid pumping function to allow a sealing fluid such as lubricating oil to flow or to be retained in the groove M1, thereby improving the sealing performance of the sealing device 20.
[0051]
Incidentally, the stress for generating groove by the distribution of distortion patterned, the other methods of deflecting the sliding surface as in this embodiment, also be formed by the pressing with a predetermined pressure It is possible.
[0052]
Further, since the thread groove is not cut, breakage of the seal member starting from the cut surface of the thread groove can be prevented, and the durability of the sealing device can be further improved.
[0053]
(Embodiment 3)
In the third embodiment, a more specific manufacturing method of the seal member will be described.
[0054]
The seal member was molded from a material based on a fluorine-based thermoplastic elastomer. Daikin Thermoplastic (trade name) manufactured by Daikin Industries, Ltd. was used as the base fluoroelastomer. This fluorine-based thermoplastic elastomer flows by heating, and exhibits rubber elasticity when cooled below the crystallization temperature. Utilizing this material property, a sheet is continuously formed using an extruder and a T-die. The sealing member can be easily obtained from this sheet by a method such as punching.
[0055]
A case where an electron beam is used as ionizing radiation will be described. In order to pattern and irradiate the base member with the electron beam onto the sealing member 21 (FIG. 3A), for example, a metal sheet 22 having a pattern cut out as shown in FIG. 3B can be used. In the metal sheet 22, reference numeral 22a denotes a cutout window portion (plural portions).
[0056]
Since the electron beam hardly penetrates through the metal, the fact that the seal member 21 at the portion shielded by the metal is hardly affected by radiation is used.
[0057]
First, a metal sheet 22 having a spirally cut pattern is placed on a sealing member 21 and an electron beam is irradiated thereon, whereby the electron beam can be easily patterned and irradiated (FIG. 3C). ). In FIG. 3, a cross-hatched region 21a is a high electron beam irradiation portion and has high elasticity, and a region 21b is a non-electron beam (low) irradiation portion and has low elasticity.
[0058]
FIG. 4 shows an example of the tensile properties of the DIELER thermoplastic and the material based on this polymer measured by changing the irradiation dose of the electron beam. With the base polymer alone, there is almost no change in 100% modulus and breaking strength due to electron beam irradiation.
[0059]
However, in the case of a material having a blend based on carbon black, it is possible to greatly change the elasticity of the material by changing the irradiation dose of the electron beam. By increasing the irradiation dose of the electron beam, the 100% modulus is improved. By appropriately combining this characteristic with the irradiation pattern, a sealing member for a sealing device suitable for the intended use can be manufactured.
[0060]
The sealing member 21 manufactured by this method has a groove formed in a portion where the electron beam is not (low) irradiated when the shaft is mounted, and exhibits a sealing (pump) function. The sealing member 21 can be mounted on a metal ring or the like as shown in FIG. 2C and used as a sealing device.
[0061]
【The invention's effect】
As described in the embodiment of the present invention, by selectively changing the physical properties of the material with respect to a specific region of the seal member, for example, the shaping of a thread groove can be achieved without using a mechanical process or a press process. At the same time, a sealing device and a method for manufacturing the sealing device that enable production with high production efficiency are obtained.
[0062]
Further, since the thread groove is not cut, breakage of the seal member starting from the cut surface of the thread groove can be prevented, and the durability of the sealing device can be further improved.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a method for manufacturing a sheet member according to a first embodiment of the present invention.
FIG. 2 is a view of a sheet member according to a second embodiment of the present invention.
FIG. 3 is a view of a sheet member according to a third embodiment of the present invention.
FIG. 4 is a table showing a relationship between an electron beam irradiation amount and material properties.
FIG. 5 is a diagram of a sealing device having a sheet member according to the prior art.
FIG. 6 is a view related to a conventional method for manufacturing a sealing member.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 seal member 2 extruder 3 sheet die 4 sheet 5 annular member 6 opening 7 mask 8 radiation irradiator 9 radiation

Claims (5)

In a sealing device having a sealing member formed of a thermoplastic elastomer as a material, and sealing an annular gap between the housing and the shaft,
The seal member has a plurality of regions having different helical elasticities corresponding to irradiation of radiation, and includes a sliding surface that slides on the shaft.
A sealing device, wherein when the sliding surface is bent in the axial direction of the shaft, a minute groove is formed in a region having low elasticity among the plurality of regions having different elasticities. The seal member is a flat washer-shaped annular member, and is bent in the axial direction while expanding its inner diameter side to form a lip portion, and the inner peripheral side of the lip portion is used as a sliding surface. Item 2. The sealing device according to Item 1. The sealing device according to claim 1, wherein the radiation is ionizing radiation. The sealing device according to any one of claims 1 to 3, wherein the thermoplastic elastomer is a fluoroelastomer. In a method for manufacturing a sealing device for sealing an annular gap between a housing and a shaft,
Forming a seal member having a sliding surface that slides on the shaft using a thermoplastic elastomer as a material,
Form a plurality of regions of different helical elasticity according to the irradiation of radiation on the sliding surface,
A method of manufacturing a sealing device, wherein the sliding surface is bent in the axial direction of the shaft to form a minute groove in a region of low elasticity among the plurality of regions having different elasticities.

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