JP2002022019A - Seal material, seal member using the same, and seal using the seal member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain excellent sealing performance, by being good in sealing performance, excellent in abrasion resistance and extrusion resistance in a long time usage under a condition of high pressure. SOLUTION: This seal member contains a polyethylene of ultrahigh molecular weight more than one million of average molecular weight of viscosity. The polyethylene of ultrahigh molecular weight has a Shore D hardness of 60 to 75, tensile strength of more than 30 MPa, and elongation percentage of 250% or more. This seal is a combination of a ring-shape seal member formed by using the seal material, the seal member, and a ring shape elastic member arranged at an outer periphery of the seal member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sealing material, a sealing member using the same, and a seal using the same.
More specifically, a sealing material, a seal material using the same, which is excellent in sealing performance, has good wear resistance and protruding resistance even when used for a long time under high pressure conditions, and thus maintains excellent sealing performance. The present invention relates to a member and a seal using the same.

[0002]

2. Description of the Related Art FIG. 8 is a partial sectional view of a swivel joint of a power shovel or the like, wherein 1 is a cylindrical housing, and 2 is a cylinder which rotates, reciprocates and swings in close contact with an inner wall 11 of the housing 1. It is an axis of shape. A ring-shaped recess 12 for sealing is provided on the inner wall 11 of the housing 1 at regular intervals, and a ring-shaped elastic body 13 and a ring-shaped seal member are provided on the inner peripheral side in the recess 12. 14
Is arranged. The housing 1 and the shaft 2 are hermetically sealed by the seal member 14.

[0003] Incidentally, the sealing member 14 is
Thus, the high hydraulic pressure P is applied to the interface between the housing 1 and the shaft 2 while the swivel joint is operating. Conventionally, the sealing member 1
Although a member made of a fluororesin is used as 4, in such a sealing member, a high pressure applied to the seal during the operation of the swivel joint during a long-time use causes the seal member 14 to be in contact with the shaft 2. As shown in FIG. 9, the contact surface is worn or deformed, and a part of the seal member 14 penetrates into the interface between the housing 1 and the shaft 2 to cause a so-called protrusion phenomenon. There is a problem that the sealing performance is reduced and oil leaks from between the housing 1 and the shaft 2.

In order to solve this problem, a seal member in which bronze or a special filler is blended with a fluororesin such as PTFE has been proposed, but the seal member still has abrasion resistance and protrusion resistance. The fact is that sex has not been sufficiently improved.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an excellent sealing performance and abrasion resistance and resistance to long-term use under high pressure conditions. An object of the present invention is to provide a sealing material, a sealing member using the same, and a seal using the same, which have good protrusion properties and therefore maintain excellent sealing performance.

[0006]

SUMMARY OF THE INVENTION The present invention is as follows. (1) A sealing material containing ultrahigh molecular weight polyethylene having a viscosity average molecular weight of 1,000,000 or more. (2) Shore D hardness of ultra high molecular weight polyethylene is 60
The seal material according to the above (1), which is from 75 to 75. (3) Tensile strength of ultra high molecular weight polyethylene is 30MPa
The sealing material according to (1) above. (4) The sealing material according to (1), wherein the ultra-high molecular weight polyethylene has an elongation of 250% or more. (5) A ring-shaped seal member using the seal material according to any one of (1) to (4). (6) The seal member according to the above (5), which is for a swivel joint. (7) A seal obtained by combining the seal member according to the above (5) with a ring-shaped elastic body disposed on the outer peripheral side of the seal member. (8) The seal according to the above (7), which is for a swivel joint.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The sealing material of the present invention contains ultra high molecular weight polyethylene.

The ultrahigh molecular weight polyethylene used in the present invention has a viscosity average molecular weight of 1,000,000 or more, preferably 3,000,000 or more, more preferably 5,000,000 or more. It has suitable hardness, tensile strength and elongation as a member. When the viscosity average molecular weight is less than 1,000,000,
Since the hardness and the tensile strength are small, the abrasion resistance is poor, and the deformation under a high pressure condition is large. Therefore, when the sealing member obtained therefrom is used as a sealing member of a swivel joint as shown in FIG. For a long period of time, abrasion and protrusion occur, and the sealing performance is reduced. As a result, oil leaks from between the housing 1 and the shaft 2. In addition, since the elongation is small, the sealing member obtained therefrom has a large damage to the local tension when the shaft 2 swings.

In the present invention, the viscosity average molecular weight is measured by a solution viscosity method according to ASTM D 4020 (solvent: decalin, temperature: 150 ° C.).

[0010] The ultrahigh molecular weight polyethylene preferably has a Shore D hardness of 60 to 75, more preferably 65 to 70. When the Shore D hardness is less than 60,
Since the abrasion resistance tends to be inferior and the deformation under high pressure conditions tends to be large, the sealing member obtained therefrom, due to prolonged use under high pressure conditions, abrasion and protrusion phenomenon occurs, The sealing performance is reduced, and as a result, oil leakage may occur between the housing and the shaft, which is not preferable. Conversely, if the Shore D hardness exceeds 75, it is too hard, and the elasticity of the ring-shaped elastic body disposed on the outer peripheral side may not be transmitted to the sealing member obtained therefrom, which is not preferable. In the present invention, Shore D hardness is measured at 24 ° C. by a method based on JIS K 7215.

[0011] Further, the above ultra high molecular weight polyethylene is
Preferably 30 MPa or more, more preferably 40 MPa
It has the above tensile strength. If the tensile strength is less than 30 MPa, deformation under high-pressure conditions tends to increase, so that the sealing member obtained therefrom protrudes due to prolonged use under high-pressure conditions, and the sealing performance deteriorates. As a result, oil leakage may occur between the housing and the shaft, which is not preferable. The upper limit of the tensile strength is not particularly limited, but is preferably 70 MPa, more preferably 60 MPa. In the present invention, the tensile strength is measured by a method according to ASTM D 1457.

Further, the ultra high molecular weight polyethylene is preferably at least 250%, more preferably at least 300%.
It has the above elongation. If the elongation is less than 250%, the sealing member obtained therefrom is likely to have a large damage to the local tension when the shaft swings, which is not preferable. In the present invention, the elongation is ASTM.
It is measured by a method according to D1457.

Specific examples of the ultra-high molecular weight polyethylene include, for example, HIZEX Million 240M (trade name, manufactured by Mitsui Chemicals, Inc., viscosity average molecular weight 3,000,000, Shore D hardness 66, tensile strength 40 MPa, elongation 350).
%), HIEXX Million 340M (Mitsui Chemicals, Inc.)
Brand name, viscosity average molecular weight 5 million, Shore D hardness 66, tensile strength 50 MPa, elongation 250%), Newlite NL-W (brand name made by Sakushin Kogyo Co., Ltd., viscosity average molecular weight 5.5 million, Shore D hardness) 67-69, tensile strength 45
MPa, elongation of 300 to 450%). These ultrahigh molecular weight polyethylenes may be used alone or in combination of two or more.

The sealing material of the present invention may contain various additives as necessary in addition to the above ultrahigh molecular weight polyethylene. Examples of additives that can be blended include glass fiber, carbon fiber, graphite powder, ethylene tetrafluoride resin, copper alloy, and molybdenum disulfide. The content of these additives is from 0 to 50 in the composition of the sealing material.
% By weight, especially 0 to 30% by weight. If the content exceeds 50% by weight, the composition becomes brittle and moldability may deteriorate, which is not preferable.

The sealing member of the present invention is obtained by molding the above sealing material into a desired ring shape by a method such as hot pressing or cutting. For example, when used for a swivel joint as shown in FIG.
The housing 1 and the shaft 2 are formed into a shape and a size that allow the housing 1 and the shaft 2 to be hermetically sealed when the shaft 2 rotates, reciprocates, and swings. The shape of the outer circumference and the inner circumference is the shape of the outer circumference of the shaft 2 and the ring-shaped elastic body 1 disposed on the outer circumference side of the seal member 14.
3 is selected depending on the shape of the inner circumference. Specific examples of the cross-sectional shape include, for example, a circular shape (O-ring) and a square shape (a square ring such as a square or a rectangle). Also, FIG.
Square rings with an inner periphery tapered, such as 2, are also exemplified, and these have the advantage of low cost. Further, as shown in FIG. 3, a shape having a concave portion on the outer periphery of which the elastic body 13 can be arranged is exemplified.
By reducing the thickness of the elastic member 13, the elasticity of the elastic
To the contact surface of the elastic member 13, the mounting property is good, and the displacement of the elastic body 13 can be prevented. Further, a ring having a plurality of grooves on its outer periphery and / or inner periphery as shown in FIG. 4 is also exemplified. By providing grooves on the inner periphery, oil can be held on the sealing surface, thereby reducing frictional resistance and abrasion. By providing a groove on the outer periphery, sliding between the elastic body 13 and the seal member 14 can be prevented.

The seal member of the present invention can also be used for a piston as shown in FIG. 5. In this case, a seal ring-shaped recess 12 on the outer wall of the piston 15 is provided.
A ring-shaped elastic body 13 and a ring-shaped seal member 14 are arranged on the outer peripheral side thereof. The shape of the inner periphery of the seal member 14 is selected depending on the shape of the outer periphery of the elastic body 13, and the cross-sectional shape is, for example, a square (a square ring such as a square or a rectangle) as illustrated in FIG. 6.

The seal member of the present invention is preferably used in combination with a ring-shaped elastic body because it generates a surface pressure on the seal surface. The elastic body used in the present invention preferably contains a rubber material. As the rubber material that can be used in the present invention, a conventionally known rubber material can be used. For example, nitrile rubber (acrylonitrile-butadiene rubber) , Hydrogenated nitrile rubber, fluorine rubber, silicone rubber, acrylic rubber, ethylene-propylene rubber, olefin rubber, and the like.

The elastic body used in the present invention can be obtained by molding the above rubber material into a desired ring shape by a method such as press molding. For example, when it is used for a swivel joint as shown in FIG. 8, it can be arranged in the recess 12 and molded into a shape and size that can transmit the elasticity of the elastic body 13 to the seal member 14 well. The shape of the inner circumference is selected according to the shape of the outer circumference of the seal member 14. As a specific example of the cross-sectional shape, for example, a square (a square ring such as a square or a rectangle) as illustrated in FIGS. ,
This can make the sealing surface pressure uniform, so that the frictional resistance can be reduced. Further, a circular shape (O-ring) as shown in FIGS. 2 and 3 is also exemplified, and this can generate a peak pressure in the seal surface pressure, so that the sealing performance is improved.

When the elastic member 13 is used for a piston as shown in FIG. 5, the elastic member 13 can be disposed in the recess 12 so that the elasticity of the elastic member 13 can be transmitted to the seal member 14 in a good shape and size. Molded into. The shape of the outer periphery is selected depending on the shape of the inner periphery of the seal member 14, and a specific example of the cross-sectional shape is a shape having a convex portion on the outer periphery as shown in FIG.

If necessary, as shown in FIG. 6, for example, as shown in FIG. 6, when the elastic body 13 has a shape having a convex portion on its outer periphery, the sealing member 14 is fixed in the recess 12 when the piston reciprocates. In such a case, backup rings 17 may be arranged above and below the seal member 14. Examples of the material of the backup ring 17 include PTFE (polytetrafluoroethylene), nylon, ultra-high molecular weight polyethylene, and polyether ether ketone. The shape is not particularly limited as long as the seal member 14 is shaped to be fixed in the recess 12 when the piston reciprocates.

The sealing member 14 and the elastic body 1 according to the present invention
As a combination of the three, for a swivel joint, a square ring-shaped seal member having an inner periphery tapered and a square ring-shaped elastic body (FIG. 1), and a square ring-shaped seal member having an inner periphery tapered. An O-ring-shaped elastic body (FIG. 2), a sealing member having a concave portion on the outer periphery where the elastic body 13 can be arranged, and an O-ring-shaped elastic body (FIG. 3), and a square ring having a plurality of grooves on the outer and inner circumference And a ring-shaped elastic body (FIG. 4).
The inner periphery was tapered because of its particularly excellent resistance to protrusion under high pressure conditions, excellent stability of sealing performance, stable surface pressure generated at the contact surface with the shaft 2, and low cost. A combination of a square ring-shaped sealing member and a square ring-shaped elastic body (FIG. 1) is particularly preferable. Further, for a piston, an elastic body 13 having a shape having a convex portion on the outer periphery, a seal member 14 having a square ring shape, and two backup rings 17 disposed above and below the seal member 14 are provided.
(FIG. 6) is illustrated.

[0022]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these.

Example 1 Ultra high molecular weight polyethylene (manufactured by Sakushin Kogyo Co., Ltd., trade name Newlite NL-W, viscosity average molecular weight 5.5 million, Shore D)
Hardness 67-69, tensile strength 45 MPa, elongation 300-4
50%) was formed into a square ring-shaped seal member having a predetermined dimension and having a tapered inner periphery shown in FIG. 1 by machining.

COMPARATIVE EXAMPLE 1 The procedure of Example 1 was repeated, except that bronze-containing (40% by weight) PTFE was used in place of the ultrahigh molecular weight polyethylene. It was molded into a processed square ring-shaped seal member.

The sealing members obtained in Example 1 and Comparative Example 1 were subjected to the following high-temperature durability test (abrasion resistance and extrusion resistance) and actual machine durability test (abrasion resistance, extrusion resistance and oil leakage). With or without).

1. High-temperature endurance test The seal member of Example 1 or Comparative Example 1 and the square ring-shaped elastic body (material: nitrile rubber) shown in FIG. 1 are applied to the swivel joint shown in FIG. Was operated to evaluate abrasion resistance and run-out resistance by the following methods. Table 1 shows the results. Hydraulic oil: Turbine # 56 Operating temperature: 120 ° C (oil temperature) Operating pressure: 35 MPa Operating angle: + 960 ° to -960 ° Operating speed: 15 rpm Operating time: 4 hours

2. Actual Machine Endurance Test The seal member of Example 1 or Comparative Example 1 and the square ring-shaped elastic body (material: nitrile rubber) shown in FIG. 1 are applied to the swivel joint shown in FIG. Was operated to evaluate abrasion resistance and run-out resistance by the following methods. Table 2 shows the results. Hydraulic oil: Turbine # 56 Operating temperature: Room temperature (24 ° C.) Operating pressure fluctuation range: 0 to 35 MPa Operating speed: 30 cpm Operating speed: 15 rpm Number of operations: 700,000 times

<Abrasion Resistance> As shown in FIG. 7, the height W ₁ of the seal member before the durability test and the height W ₂ after the durability test were measured, and the amount of wear W ₁ -W ₂ was determined. It was calculated and used as a measure of abrasion resistance. <Protrusion Resistance> As shown in FIG. 7, the amount of protrusion t of the seal member after the durability test was measured, and this was used as a measure of the resistance to protrusion.

[0029]

[Table 1]

[0030]

[Table 2]

From Tables 1 and 2, the sealing member of Example 1 is
It can be seen that even when used for a long time under high pressure conditions, the abrasion resistance and the anti-extrusion property are good, no oil leaks from between the housing 1 and the shaft 2, and the sealing performance is maintained.

[0032]

As is clear from the above description, since the sealing material of the present invention contains ultra-high molecular weight polyethylene having a molecular weight of 1,000,000 or more, it has suitable hardness and tensile strength as a sealing member. Therefore, a sealing member using such a sealing material has excellent sealing performance, and also has good abrasion resistance and protruding resistance even when used for a long time under high pressure conditions, and therefore, has excellent sealing performance. Is maintained. When such a sealing member is applied to, for example, a swivel joint, the housing 1 and the shaft 2 are hermetically sealed without oil leakage. Particularly good sealing can be obtained when used in combination with an elastic body. Further, the seal material of the present invention has a suitable elongation as a seal member, and can reduce damage to the seal member due to local tension when the shaft swings.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a specific example of a combination of a seal member and an elastic body according to the present invention.

FIG. 2 is a cross-sectional view showing a specific example of a combination of a seal member and an elastic body of the present invention.

FIG. 3 is a sectional view showing a specific example of a combination of a seal member and an elastic body according to the present invention.

FIG. 4 is a cross-sectional view showing a specific example of a combination of a seal member and an elastic body of the present invention.

FIG. 5 is a partial sectional view of a normal piston.

FIG. 6 is a sectional view showing a specific example of a combination of a seal member and an elastic body according to the present invention.

FIG. 7 is a diagram showing measurement sites of a seal member when evaluating abrasion resistance and run-out resistance in a durability test.

FIG. 8 is a partial cross-sectional view of a normal swivel joint in a power shovel.

FIG. 9 is an explanatory diagram of a protrusion phenomenon of a seal member in a swivel joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical housing 2 Shaft 11 Inner wall 12 Ring-shaped recess for sealing 13 Elastic body 14 Sealing member 15 Piston 16 Cylinder 17 Backup ring

Continued on the front page (72) Inventor Hideo Nagaoka 663 Minoshima, Arita-shi, Wakayama Prefecture F-term in Mishima Works of Mitsubishi Cable Industries, Ltd. (reference) 3J040 AA17 BA01 EA01 EA16 FA06 FA07 HA09 HA15 3J043 AA11 BA05 BA08 CA06 CB13 CB14 DA02 4H017 AA04 AB07 AC16 AC19 AE02 AE05 4J002 BB031 BD152 DA026 DA036 DC006 DG026 DL006 FA046 FA086 FD016

Claims (8)

[Claims] 1. A sealing material containing ultrahigh molecular weight polyethylene having a viscosity average molecular weight of 1,000,000 or more. 2. The sealing material according to claim 1, wherein the ultra high molecular weight polyethylene has a Shore D hardness of 60 to 75. 3. The ultrahigh molecular weight polyethylene having a tensile strength of 3
2. The sealing material according to claim 1, which has a pressure of 0 MPa or more. 4. An ultrahigh molecular weight polyethylene having an elongation of 250
%. 5. A ring-shaped sealing member using the sealing material according to claim 1. 6. The swivel joint according to claim 5, wherein:
The sealing member according to any one of the preceding claims. 7. A seal comprising a combination of the seal member according to claim 5 and a ring-shaped elastic body disposed on an outer peripheral side of the seal member. 8. The swivel joint according to claim 7, wherein:
The seal described.