JPH02215916A - Exhaust pipe fitting seal body and manufacture thereof - Google Patents

Abstract

PURPOSE:To lower the extent of friction torque with an opposite material as well as to prevent a noise from occurring by forming a lubricating slip layer in a partial projecting spherical part on the outer surface of a seal body. CONSTITUTION:A solid lubricant of graphite, molybdenum disulfide or the like and a mixture 5 consisting of a metallic fiber and a resin bonding material charge meshes of a cylindrical reinforced member 1 consisting of a metallic mesh and cover this reinforced member 1 whereby all are formed into compression molding as one body. Then, a through hole 11, where the reinforced member 11 is exposed, is formed in the inner surface and a partial projecting spherical part 12 on the outer surface, respectively. In addition, a lubricating slip layer 7 being formed by a lubricating composition is formed on this partial projecting spherical part 12 at uniform and minute thickness. A seal body 14 formed like this is low in friction torque at the initial stage of friction with the opposite material because the lubricating slip layer 7 is formed on the partial projecting spherical part 12, thus stable performance is brought into full play without emitting any noise for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a seal body used in a spherical pipe joint of an automobile exhaust pipe and a method for manufacturing the same.

[Conventional technology]

Conventionally, seal bodies used in spherical pipe joints of automobile exhaust pipes have been disclosed, for example, in Japanese Patent Publication No. 5B-21144 (1983).
As disclosed in ``Prior Art I'' (hereinafter referred to as "Prior Art I"), a wire mesh and a sheet-like refractory material such as expanded graphite or mica are overlapped and wound into a cylindrical shape to form a cylindrical body. The body is formed by compression molding in the axial direction of the cylindrical body, or JP-A-59-7432
As disclosed in Publication No. 6 (hereinafter referred to as "Prior Art ■"), a material formed by compression molding a mixture of relatively short (2 mm to 8 mm) fibers and a solid lubricant such as graphite;
There is.

[Problem that the invention seeks to solve]

The sealing body made of the conventional technology (■) described above has the advantage of high strength because the refractory material fills all the holes and gaps in the wire mesh and the two are intertwined with each other to provide structural integrity. Expanded graphite or mica used as a material has a high coefficient of friction (torque) when sliding against the mating material, and has the disadvantage of often generating abnormal noise, so the sliding surface that makes sliding contact with the mating material must be modified. There is a problem that it is difficult to put it into practical use.

Moreover, the seal body made of the prior art (i) is based on the prior art I
Although it has the advantage that it can be manufactured more easily and at a lower cost than a seal body made of During use, due to the disadvantage that the coefficient of friction is high and abnormal noise is often generated before the solid lubricant film is formed on the seal, and there are problems with the material that makes up the seal body and the manufacturing of the seal body. This has the drawback that the strength of the seal body decreases, causing partial breakage and chipping, and drastically reducing its function as a seal body.

That is, since the seal body has a spherical band shape with a through hole on the inner surface and a spherical portion on the outer surface, it is particularly important to remove the small diameter portion (
This means that a part of the material is densely filled (at the tip of the seal body), and even in the subsequent compression molding, sufficient pressure is not applied, resulting in a part lacking in strength. This means that
While the seal body is in use, this part may break or break, leading to a serious problem of leakage of exhaust gas.

Therefore, in view of the above-mentioned problem of the latter (prior art ①) sealing body, especially the strength reduction, the present inventors first filed a patent application in 1983.
No. 2-190155 (hereinafter referred to as "prior art").

In other words, the prior art uses a ring-shaped reinforcing material formed by winding a metal mesh into a cylindrical shape, a solid lubricant such as graphite or molybdenum disulfide, and a diameter of 10 to 200 μm and a length of 100 μm.
This is a sealing body for an exhaust pipe joint, which is made of a mixture with a metal fiber of ~800 μm, and the mixture fills the mesh of the ring-shaped reinforcing material and is integrally compression-molded to cover the reinforcing material. .

The sealing body made of this prior art has a diameter of 1 mm as a metal fiber.
By using fine fibers of 0 to 200 μm and 100 to 800 μm in length, when manufacturing the seal body,
By not creating sparse and dense parts in the mold (by densely filling the mold, and by using a ring-shaped reinforcing material made of metal mesh, we have solved the problem of reduced strength of the seal body made of the prior art (2) above, This significantly improved the strength of the seal body.

However, even in the seal body made of this prior art, another drawback of the seal body made of the prior art is formed as a solid lubricating film on the surface of the mating material, and during the stage where friction between the seal body and the mating material moves through this film, the coefficient of friction is unstable and abnormal noise is often generated. The shortcomings still remain as problems.

The present invention makes full use of the advantages of the above-mentioned prior art, and aims to provide a seal body and a method for manufacturing the same that solves the problem at the initial stage of friction.

[Means for solving problems]

The present invention adopts the following technical means (configuration) in order to achieve the above-mentioned object.

That is, a mixture consisting of a solid lubricant such as graphite or molybdenum disulfide, metal fibers with a diameter of 10 to 200 μm and a length of 100 to 800 μm, and a resin binder fills the mesh of a cylindrical reinforcing material made of metal mesh. A seal body that is integrally compression-molded to cover the reinforcing material and has a through hole in which the reinforcing material is exposed on the inner surface, and a partially convex spherical surface part on the outer surface, and the partially convex spherical surface part on the outer surface of the seal body has a This is a seal body for exhaust pipe joints on which a lubricating sliding layer is formed.

The method for manufacturing the seal body includes the steps of (a) inserting a core holding a cylindrical reinforcing material made of metal mesh on the outer circumferential surface into a mold having a hollow portion on the inner surface; Inside the hollow part of the mold, a solid lubricant such as graphite or molybdenum disulfide and a diameter of 10 to 200 μm and a length of 100 to 800 μm are placed.
(c) loading a mixture of metal fibers and a resin binder and compressing the mixture in the axial direction of the core to obtain a preform having a cylindrical reinforcing material on the inner surface; a step of forming a lubricating sliding layer on the outer circumferential surface; (d) inserting a core holding the preform on which the lubricating sliding layer is formed into a mold having a partially concave spherical surface portion on the inner surface; (
f) A molded seal that is formed by compressing the preform in the core axial direction and having a through hole on the inner surface where the reinforcing material is crushed and exposed, and a partially convex spherical portion on the outer surface with a uniformly formed lubricating sliding layer. This is a method for manufacturing a seal body for an exhaust pipe joint, which comprises the steps of: obtaining a seal body; and (f) placing the molded seal body in a heating furnace to heat and harden a resin binding material.

Hereinafter, the constituent materials of the above-mentioned seal body and its manufacturing method will be explained.

(Cylindrical reinforcement material) The cylindrical reinforcement material is a braided or woven metal mesh formed by weaving or knitting fine wires of stainless steel or iron, or so-called expanded band metal, which is a thin metal plate with a continuous mesh. After wrapping these around the outer circumferential surface of the core at least once, the overlapping part is spun.
These are those that are fixed by welding or clasps and formed into a cylindrical shape, those that are compressed in the axial direction of the core and formed into a cylindrical shape, and furthermore, the braided metal mesh that is woven into a cylindrical shape.

When using braided or woven metal mesh as the metal mesh, the wire diameter of the thin wire is 0.02 to 0°32 mm.
It is preferable to use a material of about 100%. The metal mesh and the expanded metal mesh are preferably about 3 to 6 mm in size.

(Mixture) (A) Metal fibers Metal fibers are iron or iron alloys containing iron as a main component, such as steel, stainless steel, copper or copper alloys containing copper as a main component, such as bronze, phosphor bronze, lead bronze, and brass. , aluminum bronze, etc., by the chatter cutting method or cut wool-like fibers formed by cutting out wire strands.

In particular, when the fiber diameter is 10 to 200 μm and the fiber length is 1
00 to 800 μm, it is possible to form a uniform mixture, it is possible to uniformly fill the mold in the manufacturing of the seal body, it is possible to fill the mesh of the cylindrical reinforcing material, A strong structure-imaging of the cylindrical reinforcing material and the mixture is made possible by intertwining of fibers.

These metal fibers may be used alone or in combination.

(B) Solid lubricant As the solid lubricant, powders such as graphite and molybdenum disulfide are used alone or in combination.

(C) Resin binding material Phenol resin is used as the resin binder.

The above-mentioned (A) metal fibers, (B) solid lubricant, and (C) resin binder are placed in a mixer, stirred and mixed to form a uniform mixture.

The blending ratio of the mixture is 50 to 75% by weight of metal fibers, 15 to 30% by weight of solid lubricant, and 2 to 20% by weight of resin binder.
A preferable range is % heavy background.

In addition, inorganic powders such as calcium carbonate (CaCOz) and boron oxide (B20.1) may be added to the mixture having the above-mentioned composition, either singly or in combination.

These calcium carbonate and boron oxide powders do not exhibit any lubricating properties by themselves, but when added to the above mixture, they particularly promote the formation of a solid lubricant film on the surface of the mating material of the solid lubricant, thereby forming a sealing body. Improves friction and wear characteristics and prevents oxidation of metal fiber wear powder caused by friction.
It functions to suppress the abrasive action of the oxidized wear debris caused by oxidation of the wear debris.

And, these inorganic powders are added to 5-2% of the above mixture.
It can be blended in a proportion of 0% by weight.

(Preformed body) The preformed body is formed by compression molding the above-mentioned cylindrical reinforcing material and the mixture filled to cover the reinforcing material, and its shape matches the inner diameter of the final product, the sealing body. There is no particular restriction as long as it has a dimensional relationship such as an inner diameter larger than that, an outer diameter smaller than the outer diameter, and a height, but a cylindrical shape is preferable in consideration of workability and the like.

(Lubricating sliding layer) The lubricating sliding layer formed on the convex spherical surface of the outer surface of the seal body reduces the friction coefficient (torque) between the seal body and the mating material, especially in the initial stage of friction between the two, thereby reducing abnormal noise. It plays a role in preventing the occurrence.

This lubricating sliding layer is applied to the outer peripheral surface of the preform formed from the cylindrical reinforcing material and mixture by methods such as coating, scattering, or pasting, and is uniformly applied to the convex spherical surface of the sealing body in the final compression process. and is formed to have a minute thickness.

The outer circumferential surface of the preform on which the lubricating sliding layer is formed is relatively rough (uneven surface), and is subjected to strong shearing force between the mold surfaces in the final compression process. The lubricating sliding layer is firmly integrated with the convex spherical outer surface of the seal body.

The lubricating sliding layer is made of polytetrafluoroethylene resin (hereinafter referred to as PTFU J) or PTFE as a main component, and one or more fillers selected from graphite, metal sulfide, metal fluoride, and boron nitride. 2 or more types 4
It is formed by a lubricating composition blended at a ratio of 0 to 50ml1%.

When 1'TFE is used alone, the PTI'E can be used as a fine powder for molding, as an aqueous dispersion for coating, or as a PTI'E.
PTFE with a thickness of about 0.05 to 0.5 mm manufactured by paste extrusion molding of TFE fine powder
In addition to raw tape or raw sheets, a lubricating PTFE powder called "sintered Teflon" is used.

Molybdenum disulfide, tungsten disulfide, antimony trisulfide, etc. are used as metal sulfides that are blended with PTFH to form a lubricating composition, and metal fluorides include calcium fluoride, barium fluoride, lithium fluoride, etc. is used.

This metal fluoride itself is not a very low friction material, but when used in combination with PTFE, graphite, metal sulfide, boron nitride, etc., it prevents oxidative wear and tear at high temperatures and contributes to maintaining lubricity. .

The lubricating composition is a PTFE aqueous dispersion blended with the above-mentioned filler, or a lubricating PTFH blended with a filler and an adhesive (e.g. alkyd resin, phenolic resin, etc.) in a volatile solvent (e.g. xylene). , dichloroethane, trichlorethylene, etc.) and applied to the outer peripheral surface of the preform by applying with a brush or spraying.

Preferred component compositions for this lubricating composition are shown in Table 1.

(Margin below) Table 1 [Examples] Examples of the present invention will be described in detail below with reference to the accompanying drawings.

<Example: I> Using stainless steel wire with a wire diameter of 0.3 mm, a bag-like braided mesh with a mesh size of 5 mm was created. This bag-shaped braided mesh is passed through a pressure roller to form a sheet, which is wound around the outer circumferential surface of the core once.The overlapped portion is fixed by spot welding, and the mesh is compressed in the axial direction of the core to form a braided mesh. A cylindrical reinforcing material 1 was formed.

(Weight %) The cylindrical reinforcing material 1 was fitted and inserted into the outer peripheral surface of a mold core 2 (Fig. 1), and the core 2 was inserted and fixed into a mold 4 having a cylindrical recess 3 on the inner surface. (Figure 2).

On the other hand, graphite is used as a solid lubricant, and the graphite powder and
A metal fiber made of steel with a wire diameter of 100IIa+ and a length of 500 μm and a phenolic resin binding material were placed in a mixer,
Stir and mix to create a homogeneous mixture 5 of the graphite powder, steel fibers, and phenolic resin binder in a mixing ratio of graphite:
The mixture 5 (18% by weight, 3% by weight of steel fiber, 9% by weight of resin binder) was loaded into the cylindrical recess 3 of the mold 4 (FIG. 3).

Then, the mixture 5 is molded in the axial direction of the core 2 under a molding pressure l.
4) to form a cylindrical preformed body 6 integrally equipped with a cylindrical reinforcing material 1 on the inner surface (Fig. 4).
Figure 5).

An aqueous dispersion (solid content 60% by weight, manufactured by Mitsui Fluorochemical Co., Ltd.) in which PTFE solids with an average particle size of 0.1 μm or less is dispersed is applied to the outer cylindrical surface of the cylindrical preform 6 thus obtained. A lubricating sliding layer 7 was formed by coating and impregnating (FIG. 6).

The cylindrical preform 6 provided with the lubricating sliding layer 7 was fitted and held on the outer peripheral surface of a mold core 8, and the core 8 was inserted and fixed into a mold 10 having a partially concave spherical surface portion 9 on the inner surface. (Figure 7)
.

Then, in the mold 10, the cylindrical preform 6 is
is compression molded in the axial direction of the core 8 at a molding pressure of 3):z/cm2, the inner surface is provided with a through hole 11 in which the crushed cylindrical reinforcing material 1 is exposed, and the lubricating sliding layer 7 is uniformly and -
A molded seal body 13 having a partially convex spherical surface portion 12 that was stretched to a very small thickness and formed firmly and integrally was obtained (No. 8).
figure).

Then, the molded seal body 13 is preheated by placing it in a heating furnace set at a temperature of 80°C for 30 minutes, and then the resin binding material in the mixture is heated and hardened at a temperature of 180°C for 2 hours. 14 was obtained (Figure 9).

<Example: ■> A cylindrical reinforcing material 1 made of a braided mesh was formed in the same manner as in the above <Example: ■>, and the cylindrical reinforcing material 1 was fitted onto the outer peripheral surface of the mold core 2. At the same time, the core 2 was inserted and fixed into a mold 4 having a cylindrical recess 3 on the inner surface.

On the other hand, using graphite as a solid lubricant, the graphite powder, a metal fiber made of steel with a wire diameter of 100 μm and a length of 500 μm, calcium carbonate powder as an inorganic powder, and a phenol resin binder were put into a mixer and mixed by stirring. To prepare a homogeneous mixture 5 of the graphite powder, steel fiber, calcium carbonate powder, and phenolic resin binder, the mixing ratio is graphite powder:
The mixture 5 was loaded into the cylindrical recess 3 of the mold 4.

Then, the mixture 5 is applied to the axial direction of the core 2 under a molding pressure of 1
) to form a cylindrical preform 6 integrally provided with a cylindrical reinforcing material 1 on the inner surface.

The outer cylindrical surface of the cylindrical preform 6 has a thickness of 0. In+
m0PTFE raw tape (manufactured by Asahi Glass Co., Ltd.: Fullon CD 1
) was applied each time to form a lubricating sliding layer 7.

The cylindrical preform 6 provided with the lubricating sliding layer 7 was fitted and inserted into the outer peripheral surface of a mold core 8, and the core 8 was inserted and fixed into a mold 10 having a partially concave spherical surface portion 9 on the inner surface. .

In the mold 10, the cylindrical preform 6 is compression molded in the axial direction of the core 8 at a molding pressure 3)://Cl11'', and a through hole is formed in which the crushed cylindrical reinforcing material 1 is exposed on the inner surface. A molded seal body 13 was obtained, which had a hole 11 and a partially convex spherical surface part 12 on the outer surface of which the lubricating slide M7 was stretched to a uniform and -like microscopic thickness and formed firmly and integrally.

Then, after preheating this molded seal body 13 in a heating furnace set at a temperature of 80°C for 30 minutes,
The resin binder in the mixture was heated and cured at a temperature of .degree. C. for 2 hours to obtain a seal body 14.

<Example 2■> A cylindrical preform 6 integrally provided with the cylindrical reinforcing material 1 on the inner surface was formed using the same materials and method as in the above <Example: I>.

Next, PTF is applied to the outer cylindrical surface of the cylindrical preform 6.
Dispersion is a lubricating composition created by mixing tungsten disulfide (WSz) powder and graphite (Gr) powder into E aqueous dispersion (solid content 60%) and stirring and mixing.
Solid content PTFE: 50% by weight, WSz: 40% by weight
, Gr: 10% by weight) to form a lubricating sliding layer 7.

The cylindrical preform 6 provided with the lubricating sliding layer 7 is placed in a mold 8.
The core 8 was inserted and fixed into a mold 10 having a partially concave spherical surface 9 on the inner surface. In the mold IO, the preliminary cylindrical molded body 6 is compression molded in the axial direction of the outer core 8 at a molding pressure of 3 tons/Cll12, and the inner surface is provided with a through hole 11 in which the crushed cylindrical reinforcing material 1 is exposed. A molded seal body 13 having a partially convex spherical surface portion 12 on the outer surface of which the lubricating sliding layer 7 was stretched to a uniform and minuscule thickness and formed firmly and integrally was obtained.

Then, after preheating this molded seal body 13 in a heating furnace set at a temperature of 80°C for 30 minutes,
The resin binder in the mixture was cured by heating at a temperature of °C for 2 hours to obtain a seal body 14.

<Example: ■> A cylindrical preform 6 integrally provided with a cylindrical reinforcing material 1 on the inner surface was formed using the same materials and method as in the above <Example: I>.

Next, PTF is applied to the outer cylindrical surface of the cylindrical preform 6.
E aqueous dispersion (solid content 60%) with graphite (Gr)
) powder, tungsten disulfide (WSz) powder, and calcium fluoride (CaFz) powder, and stirred and mixed the lubricating composition.
: 50% by weight, Gr: 20% by weight, CaFz: 1
0% by weight) to form a lubricating sliding layer 7.

The cylindrical preform 6 provided with the lubricating sliding layer 7 is placed in a mold 8.
The core 8 was inserted and fixed into a mold lO having a partially concave spherical surface portion 9 on the inner surface. In the mold 10, the preliminary cylindrical molded body 6 is compression molded in the axial direction of the outer core 8 at a molding pressure of 3) mm/cm2, and a through hole 11 in which the crushed cylindrical reinforcing material 1 is exposed is formed on the inner surface. A molded seal body 13 having a partially convex spherical surface portion 12 on the outer surface of which the lubricating sliding layer 7 was stretched uniformly and to a minute thickness similar to that of -, and which was formed firmly and integrally, was obtained.

Then, this molded seal body 13 is preheated in a heating furnace set at a temperature of 80°C for 30 minutes, and then heated to 180°C.
The resin binder in the mixture was heated and cured at a temperature of 2 hours to obtain a seal body 14.

<Comparative Example> Using stainless steel wire with a wire diameter of 0.3 am, a bag-like braided mesh with a mesh size of 5 a+m was created. This bag-shaped braided mesh is made into a sheet by passing through a pressure roller, and after being wound around the outer circumferential surface of the core once, the overlapped portion is fixed by spot welding, and the mesh is compressed in the axial direction of the core to create a braided mesh. A cylindrical reinforcement material was formed.

The cylindrical reinforcing material was fitted and inserted into the outer peripheral surface of a mold core, and the core was inserted and fixed into a mold having a partially concave spherical surface portion on the inner surface.

Next, graphite was used as a solid lubricant in the partially concave spherical part of the cough mold, and the graphite powder and a wire with a diameter of 100 μm and a length of 50
A homogeneous mixture of the graphite powder, steel fibers, and phenolic resin binder (mixing ratio of graphite: 18 % by weight, 3% by weight of steel fibers, and 9% by weight of resin binder).

In the mold, the mixture is compression molded in the axial direction of the core at a molding pressure of 3 tons and 7 cm, so that the inner surface has a crushed cylindrical reinforcing material with an exposed through hole and a lubricating sliding layer on the outer surface. A molded seal body having a partially convex spherical surface portion formed to have a uniform and minute thickness was obtained.

After preheating the molded seal body for 30 minutes in a heating furnace set at a temperature of 80°C, the resin binder in the mixture is heated and hardened at a temperature of 180°C for 2 hours, and the seal body I got it.

Next, the friction torque (k
gf/cm), abnormal noise generation, and the sealing function of the seal body.

- One test method for the friction coefficient during the initial friction of the seal body, the generation of abnormal noise, and the sealing function of the seal body was as described in <Example: ■>, <Example: ■>, <Example: ■
> and <Example: ■> Particularly Comparative Example>, a seal body having a convex spherical surface with a radius of curvature of 30 mm on the outer surface was created, the seal body was attached to one tube end, and the other tube end was attached to this. The joint was brought into sliding contact with a concave spherical part of stainless steel provided in the joint part under the following conditions, and the friction torque at the initial stage of friction at the sliding contact part, the generation of abnormal noise, and the amount of gas leaking from the joint part were tested.

The test device (shape B in which the seal body is attached to a spherical pipe joint) is shown in FIG. 11.

In the figure, 20 is a downstream exhaust pipe, and the exhaust pipe 20
At the end of the tube, there is a concave spherical part 21 whose diameter expands in the shape of a morning glory toward the end.
is formed.

30 is an upstream exhaust pipe, and the exhaust pipe 30 has a pipe end 3.
All but one flange 32 is fixed. On the outer peripheral surface of the pipe end 31 of the upstream exhaust pipe 30, a sealing body 14 connects the convex spherical surface portion 12 of the outer surface portion to the concave spherical surface portion 21 of the downstream exhaust pipe 20.
The large-diameter end surface of the convex spherical portion 12 is attached to the flange 32 in sliding contact with the flange 32.

On the nuclear side, the downstream exhaust pipe 20.30 has one end screwed and fixed to a flange 32 fixed to the upstream exhaust pipe 30, and the other end to a flange 22 fixed to the downstream exhaust pipe 20. A pair of headed bolts 40 and the flange 22 are inserted and arranged.
and the head of the bolt 40 are connected by a pair of coil springs 50 which are always biased in the direction of the upstream exhaust pipe 30.

(Test conditions) Pressing force 60kg Swing angle ±3° Vibration frequency IQ to 1L Ambient temperature Room temperature ~ 50
0°C pipe pressure 0.5Kg/cn+” Test method: 1 ±36 oscillation motion at 10 Herf frequency
After repeating the movement 45,000 times at room temperature, the ambient temperature was raised to 500°C while continuing the movement, and the number of rocking movements during heating was 45.
000 times), when the ambient temperature reached 500°C, the rocking movement was performed 115,000 times, and then, while continuing the movement, the ambient temperature was lowered to room temperature (the number of rocking movements during cooling was 45,000 times). 4 cycles are performed, with 250,000 oscillations in total (1 cycle).

Furthermore, the presence or absence of abnormal sounds was evaluated as follows.

Evaluation symbol: I: No abnormal sound was generated.

Evaluation symbol ■: A faint abnormal sound can be heard when the ear is brought close to the test piece.

Evaluation symbol ■: At the fixed position (1.5 m away from the test piece), the sound is muffled by the sounds of the living environment and is generally difficult to distinguish, but the tester can distinguish it as an abnormal sound.

Evaluation symbol ■: A sound that anyone can identify as an abnormal sound (unpleasant sound) in a fixed position.

Table 2 shows the above test results.

(The following is a blank space) From the test results, the seal body of the present invention, that is, <Example:
! 〉, 〈Example: ■〉, 〈Example 2〉, and 〈Example: ■〉 have low friction torque at the initial stage of friction with the mating material, and no abnormal noise was generated during the test period. It showed stable performance throughout.

On the other hand, in the seal body made from Comparative Example, the friction torque was high at the initial stage of friction with the mating material, and the amount of fluctuation was large, and abnormal noise was observed.

When we observed the friction surfaces of each seal body and the mating material of the examples and comparative examples after the test, it was confirmed that a solid lubricant film (graphite film) was formed on the friction surfaces of all of them.
After this solid lubricant film was formed, that is, in the above test, no significant difference in performance between the Examples and Comparative Examples was observed in terms of friction after 750,000 cycles.

From the above test results, the seal body of the present invention, which has a lubricating sliding layer on the convex spherical surface of the outer surface, exhibits excellent performance in the initial stage of friction with the mating material. It was possible to solve the shortcomings of

FIG. 10 shows another embodiment of the seal body 14, in which the cylindrical reinforcing member l is crushed and exposed near the small diameter portion of the outer convex spherical surface portion 12 of the inner surface through hole 11 of the seal body 14. . The seal body made of this embodiment also exhibits the same performance as described above.

〔effect〕

The present invention has the above-described configuration and has the following unique effects.

■Since the seal body of the present invention has a lubricating sliding layer formed on the convex spherical surface of the outer surface, the friction torque is low especially at the initial stage of friction with the mating material, there is no abnormal noise, and it lasts for a long period of time from the initial stage of friction. Demonstrates stable performance over a long period of time without producing abnormal noise.

■The lubricating sliding layer formed on the convex spherical surface of the outer surface of the seal body has a relatively rough (uneven surface) formed by compression molding a mixture of solid lubricant, metal fibers, and resin binder into a cylindrical shape. Since it is applied to the outer circumferential surface of the preformed body and is formed under strong shearing force between the molds in the final compression process, it is firmly integrated with the outer circumferential surface of the seal body.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the cylindrical reinforcing material inserted into the outer peripheral surface of the core, Fig. 2 is a vertical cross-sectional view showing the cylindrical reinforcing material placed inside the mold, and Fig. 3 is shown in Fig. 2. FIG. 4 is a vertical cross-sectional view showing a state in which the mixture shown in FIG. 3 is compression-molded; FIG. 5 is a vertical cross-sectional view showing a preformed body; Fig. 6 is a longitudinal sectional view showing a preformed body with a lubricating sliding layer formed on its outer peripheral surface, and Fig. 7 is a longitudinal sectional view showing the preformed body shown in Fig. 6 placed in a mold. Figure 8 is a vertical cross-sectional view showing a state in which the preform is compression-molded in a mold to form a molded seal body, Figure 9 is a vertical cross-sectional view showing the seal body, and Figure 1O is another embodiment of the seal body. A vertical cross-sectional view showing an example, Figure 11 is a test device (exhaust pipe spherical joint)
FIG. 1. Cylindrical reinforcement 2. Mold core 3. Cylindrical recess 4. Mold 5. Mixture 6. Preformed body 7 ・ 9 ・ 11 13. ・ Lubricating sliding layer/partial concave spherical surface part・Through hole・Molded seal body 8・10・12・14・・Mold core・Mold・Partially convex spherical surface portion・Seal body

Claims (12)

[Claims] (1) A mixture consisting of a solid lubricant such as graphite or molybdenum disulfide, metal fibers with a diameter of 10 to 200 μm and a length of 100 to 800 μm, and a resin binder fills the mesh of a cylindrical reinforcing material made of metal mesh. and a seal body that is integrally compression-molded to cover the reinforcing material and has a through hole in which the reinforcing material is exposed on the inner surface, and a partially convex spherical surface on the outer surface, the partially convex spherical surface of the seal body has a A seal body for an exhaust pipe joint characterized by forming a lubricating sliding layer. (2) The seal body for an exhaust pipe joint according to claim 1, wherein the cylindrical reinforcing material is crushed and exposed over the entire length of the inner surface through-hole of the seal body. (3) The seal body for an exhaust pipe joint according to claim 1, wherein the cylindrical reinforcing material is crushed and exposed near the small diameter portion of the convex spherical surface portion of the outer surface of the inner surface through-hole of the seal body. (4) The seal body for an exhaust pipe joint according to claim 1, wherein the mixture comprises 15 to 30% by weight of solid lubricant, 50 to 70% by weight of metal fibers, and 2 to 20% by weight of resin binder. (5) The seal body for an exhaust pipe joint according to claim 4, wherein the mixture contains an inorganic powder selected from calcium carbonate and boron oxide in a proportion of 2 to 20% by weight. (6) The seal body for an exhaust pipe joint according to claim 1, wherein the lubricating sliding layer is made of tetrafluoroethylene resin. (7) The lubricating sliding layer is made of a lubricating composition containing a tetrafluoroethylene resin as a main component and a filler selected from graphite, metal sulfide, metal fluoride, and boron nitride. Seal body for exhaust pipe joints. (8) (A) A step of inserting a core holding a cylindrical reinforcing material made of metal mesh on the outer peripheral surface into a mold having a hollow part on the inner surface; (B) Inside the hollow part of the mold, Solid lubricants such as graphite and molybdenum disulfide with a diameter of 10 to 200 μm and a length of 100 to
a step of loading a mixture consisting of 800 μm metal fibers and a resin binder and compressing the mixture in the axial direction of the core to obtain a preformed body having a cylindrical reinforcing material on the inner surface; (c) the preformed body; (d) inserting a core holding the preform on which the lubricating sliding layer is formed into a mold having a partially concave spherical surface on the inner surface; (e) The preform is compressed in the core axial direction, and the inner surface is provided with a through hole in which the supply material is crushed and exposed, and the outer surface is provided with a partially convex spherical portion on which a lubricating sliding layer is uniformly formed. A method for manufacturing a seal body for an exhaust pipe joint, comprising the steps of: obtaining a molded seal body; (f) placing the molded seal body in a heating furnace to heat and harden a resin binding material. (9) The method for producing a seal body for an exhaust pipe joint according to claim 8, wherein the mixture comprises 15 to 30% by weight of solid lubricant, 50 to 70% by weight of metal fibers, and 2 to 20% by weight of resin binder. (10) The mixture contains an inorganic powder selected from calcium carbonate and boron oxide in a proportion of 2 to 20% by weight.
The method for manufacturing the seal body for an exhaust pipe joint described above. (11) The method for manufacturing a seal body for an exhaust pipe joint according to claim 8, wherein the lubricating sliding layer is made of tetrafluoroethylene resin. (12) The lubricating sliding layer comprises a lubricating composition containing a tetrafluoroethylene resin as a main component and a filler selected from graphite, metal sulfide, metal fluoride, and boron nitride. A method for manufacturing a seal body for an exhaust pipe joint.