JP2001165313A - Manufacturing method of synthetic resin seal ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic resin seal ring with both ends, excellent in fittability and sealability, which eliminates the need for increasing manufacturing man-hours. SOLUTION: The cylinder 1 is rotated as a center at the shaft center 0, he dinking work is processed towards outside from inner side of the cylinder by the cutting off tool 2, the part of direction of the circumference of the annular object acquired by this is cut perpendicularly to the side of an end and then the synthetic resin seal ring 3 with end is obtained in the direction of the circumference, in the process of the dinking work the internal stress is imposed towards the shrinking diameter by the shearing, since this internal stress is uniformly distributed to the direction of the circumference, this seal ring 3 is installed in the ring groove by the proper tightening force since the reduction of tightening force by expansion is compensated, at that time of installing in the ring groove of the perimeter side of the shaft and, etc., by expansion both ends 31, 32 to be opened, so that the fittability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end-shaped synthetic resin seal ring which is mounted on a rotating shaft, a reciprocating shaft, a piston, or the like in an automobile or the like to perform sealing and is divided at one place in a circumferential direction. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as a seal ring mounted on the outer periphery of a rotating shaft, a reciprocating shaft or a piston, FIG.
As shown in FIG. 1A, there is known an end-shaped ring in which one portion in the circumferential direction is divided. This type of seal ring 100 is made of a synthetic resin material such as PTFE (tetrafluoroethylene resin) having excellent slidability and appropriate flexibility.
1 and 102 have a substantially perfect circular shape in close contact with each other, and have an inner diameter substantially equal to a diameter of a groove bottom of a ring groove formed on an outer peripheral surface of a shaft portion or the like to be mounted. Therefore, the mounting of the seal ring 100 is performed by
This is performed by fitting into the ring groove from the outer peripheral side with the restoring force due to its elasticity while expanding and deforming the diameter so as to increase the interval.

However, a seal ring 10 made of synthetic resin is used.
If the two ends 101 and 102 are expanded and deformed so as to open each other, the ring does not completely return to the perfect circular shape before mounting. Therefore, the ring of the shaft is kept open while the ends 101 and 102 remain open. Partially protrudes from the inside of the groove. Therefore, when inserting the shaft portion on which the seal ring 100 is mounted into the inner peripheral hole of the mating housing, the outer peripheral portion of the seal ring 100 interferes with the opening of the inner peripheral hole, and a large load is applied to the seal ring 100. Problems such as hanging are pointed out.

A technique for solving such a problem is as follows.
For example, it is disclosed in Japanese Patent No. 2729886.
The synthetic resin seal ring 100 'disclosed in this publication
Is also made of a tetrafluoroethylene resin or the like, and is previously held at a smaller diameter than the inner diameter by a heat treatment, so that both end portions 10 are formed as shown in FIG.
The parts 103, 104 inside the parts 1, 102 are habited to intersect. For this reason, when it is mounted in a ring groove such as a shaft portion while widening the interval between the two end portions 101 and 102, it is fixed to the groove bottom of the ring groove by a tightening force given by a habit, so that incorporation is improved. Is what you do.

[0005]

However, the conventional seal ring 100 'disclosed in the above-mentioned publication requires a step of forming a habit after processing into an end ring shape in the manufacture thereof, which increases man-hours. And there is a problem that the cost rises. In addition, since the seal ring 100 'is fixed in an elliptical shape and deformed in the habit forming step, it is difficult for the seal ring 100' to be restored to a substantially perfect circular shape in the mounted state. Therefore, there is a problem in that the entire surface does not adhere to the groove bottom of the ring groove to be mounted, and the sealing performance is reduced as compared with a seal ring having no habit.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its main technical problem is to provide a terminal having excellent incorporation and sealing properties without increasing the number of steps in manufacturing. An object of the present invention is to provide a seal ring made of synthetic resin having a shape.

[0007]

In order to eliminate the opening between the circumferential ends due to a decrease in the tightening force in the process of mounting the seal ring and the deformation to a non-circular shape due to the habit, etc. Without applying partial external force to the ring,
It is necessary to compensate the restoring force against the expanding deformation. Therefore, as a means for effectively solving such a technical problem, a method of manufacturing a synthetic resin seal ring according to the present invention includes a method of manufacturing a synthetic resin seal ring having a circumferential end. The parting off of both ends in the axial direction of the ring is performed from the inner diameter side to the outer diameter side.

The parting-off process for obtaining an annular body from a cylindrical material is usually performed by sending a parting-off cutting tool from the outer diameter side to the inner diameter side of the rotated cylindrical body to perform cutting.
In the present invention, the internal stress in the direction of reducing the diameter of the seal ring is generated by performing the parting-off process from the inner diameter side to the outer diameter side. This internal stress is caused by a shearing action given as a result of cutting from the inner diameter side by the parting-off blade. For this reason, the internal stress is uniformly distributed in the circumferential direction, so that the seal ring manufactured by this method does not partially deform in a part in the circumferential direction.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows one embodiment of a method for manufacturing a synthetic resin seal ring according to the present invention, and reference numeral 1 in FIG. It is a cylinder obtained by molding and firing.

The material of the synthetic resin material used for the cylindrical body 1 is not particularly limited, but as a preferable example, typically, a PTFE material having a remarkably low coefficient of friction (tetrafluoroethylene alone or tetrafluoroethylene and Copolymers with hexafluoropropylene, perfluoropropylvinylether, etc.), PEEK (polyetheretherketone), and the like.

The filler mixed with the synthetic resin material is not particularly limited. For example, glass fiber, glass powder, carbon fiber, carbon powder, inorganic whisker (silicon carbide, silicon nitride, alumina powder, etc.), metal Powders (copper, zinc, nickel, aluminum, brass, bronze, etc.), metal compounds (aluminum hydroxide, magnesium hydroxide, etc.),
Synthetic resin powder (polyphenylene sulfide, polyimide, polyparaoxybenzoyl, etc.) and the like can be mentioned.

The cylindrical body 1 is parted off by turning using a parting blade 2. That is, the cylindrical body 1 is rotated around the axis O, the cutting edge 2 is applied to the inner peripheral surface thereof at a predetermined position in the axial direction, and the cylindrical body 1 is fed in the outer radial direction. While being cut from the inner diameter side to the outer diameter side, it is cut with a predetermined axial thickness t. Then, as shown in FIG. 1 (B), a part of the obtained annular body in the circumferential direction is cut C perpendicularly to the cut-off axial end faces 3a, 3b. A seal ring 3 made of synthetic resin having an end in the circumferential direction is obtained.

In the seal ring 3 obtained by the above-described process, the internal stress in the diameter decreasing direction due to the shearing action from the inner diameter side is caused by the parting-off process being performed from the inner diameter side to the outer diameter side. Is provided uniformly in the circumferential direction. Therefore, unlike the conventional case where the external force is applied by applying a partial external force, the seal ring 3 has a substantially perfect circular shape, and the opposing surfaces of the circumferential end portions 31 and 32 are opposed to each other. , With appropriate surface pressure. FIG. 1 (B)
In this state, the inner diameter φ of the seal ring 3 is formed to be substantially equal to the diameter of the groove bottom surface of a ring groove (not shown) formed on the outer peripheral surface of the shaft portion or the like to be mounted.

Therefore, the seal ring 3 is forcibly expanded and deformed in the process of mounting the seal ring 3 in a ring groove such as a shaft portion while opening the circumferential end portions 31 and 32 of the seal ring 3 while opening. The reduction in the tightening force due to this is compensated for by the internal stress in the radial direction given in the above-mentioned parting-off process. For this reason, after mounting in the ring groove, the shape is easily restored to the shape before mounting shown in FIG. 1 (B), and itself is fixed to the groove bottom of the ring groove with an appropriate tightening force. Is improved.
In addition, since the internal stress is uniformly distributed in the circumferential direction, the inner stress is restored to a substantially perfect circle in the mounted state, and the entire circumference is in a good close contact state with the mating member.
Excellent sealing performance can be exhibited.

The above-mentioned effect can be obtained by any method if an internal stress in the radially reduced direction is applied to the axial end faces 3a and 3b by the shearing action from the inner diameter side. Since the internal stress is obtained by parting off from the inner diameter side in the manufacturing process, a special process for applying the internal stress is not required after the processing into the end ring shape. This does not increase the manufacturing cost.

As shown in FIG. 1 (A), by cutting off the cylindrical body 1 from the inner diameter side, any seal ring having a circumferential end shape made of a synthetic resin material can be used. Although the above-mentioned effects can be obtained even with such a material, in particular, the smaller the crystallinity of the synthetic resin material, in other words, the greater the proportion of the amorphous portion that contributes to elasticity, impact resistance, fatigue resistance, etc. It has been confirmed by Examples described later that the more remarkable effect is realized.

In the illustrated embodiment, the cut portion formed at one circumferential position of the seal ring 3 forms a plane perpendicular to the axial end faces 3a and 3b and extending in the radial direction. However, the cut shape is not particularly limited to the illustrated shape, that is, the above effects can be obtained irrespective of the cut shape.

[Embodiment] Each of the PTFE materials having a crystallinity of 56%, 51% and 43% mixed with a carbon powder having a particle size of 1 to 100 μm was used, and the inside diameter was 94.5 m.
m, cylindrical bodies having an outer diameter of 103.5 mm were produced, and these cylindrical bodies were cut off from the inner diameter side to the outer diameter side so that the axial thickness became 3.0 mm. Next, a part of the annular body in the circumferential direction obtained by the parting-off process is cut perpendicularly to both end faces in the axial direction to form an end ring shape, and the cut surface is intentionally set in the axial direction. As shown in FIG. 2 (A), since the diameter was reduced so that both ends in the circumferential direction crossed each other, the crossed dimension was measured as a negative clearance dimension of the cut portion. The measurement results were as shown in Table 1 below. As the crystallinity, a numerical value obtained by DSC (differential scanning calorimeter) was used.

[Table 1]

[Comparative Example] Each cylindrical body made of a PTFE material having a different degree of crystallinity similar to that used in the above-mentioned embodiment was placed on the outer diameter side so that the axial thickness became 3.0 mm. The part was cut off toward the inner diameter side. Next, a part of each annular body in the circumferential direction obtained by the parting-off process was cut perpendicularly to both end faces in the axial direction to form an end ring shape, as shown in FIG. 2 (B). Since the cut portions (both circumferential end portions) were open to each other, the clearance dimension was measured as a positive value. The measurement results were as shown in Table 2 below.

[Table 2]

As is clear from the above measurement results, Comparative Examples 1 to 3 obtained by cutting off from the outer diameter side to the inner diameter side show that the shearing action during cutting acts on the outer peripheral side. Examples 1 to 3 obtained by cutting off from the inner diameter side to the outer diameter side, while the diameter increased when cutting a part in the circumferential direction and a gap occurred in the cut portion.
It was confirmed by the generation of negative clearance that the shearing action at the time of cutting acts on the inner peripheral side to apply a diameter reducing force.

According to Tables 1 and 2, the smaller the crystallinity of the PTFE, the larger the absolute value of the cut portion clearance dimension. Therefore, it was confirmed that the effect of the present invention was more remarkable as the ratio of the amorphous portion was larger.

[0022]

According to the method of manufacturing a synthetic resin seal ring according to the present invention, by cutting off both end faces in the axial direction from the inner diameter side to the outer diameter side, it is possible to reduce the diameter of the seal ring. Since an internal stress is applied, it is possible to provide a synthetic resin seal ring having excellent incorporation into a ring groove such as a shaft portion. Further, in the seal ring obtained by the manufacturing method of the present invention, since the internal stress is uniformly distributed in the circumferential direction, a substantially perfect circular state where partial deformation does not occur in a part of the circumferential direction. Can be used to improve the sealing performance.
This can be realized without increasing the number of steps.

[Brief description of the drawings]

FIG. 1 shows one embodiment of a method for manufacturing a synthetic resin seal ring according to the present invention, in which (A) is a schematic explanatory view showing a parting-off step, and (B) is a perspective view of the seal ring. is there.

FIG. 2 is an explanatory view showing measurement of a clearance dimension of a cut portion in Examples and Comparative Examples.

FIG. 3 is an explanatory diagram showing two types of synthetic resin seal rings according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical material 2 Cutting-off tool 3 Seal ring made of synthetic resin 3a, 3b Both end surfaces in axial direction 31, 32 Both end portions in circumferential direction

Continued on the front page F term (reference) 3J043 AA02 AA12 AA16 BA05 CA12 CB13 DA10 DA11 3J044 AA14 AA18 BA06 BC06 DA09 EA02

Claims (1)

[Claims] 1. In the manufacture of a synthetic resin seal ring (3) having ends in the circumferential direction, parting off of both end surfaces (3a, 3b) in the axial direction of the seal ring (3) is performed from the inside diameter to the outside diameter. A method for producing a synthetic resin seal ring, wherein the method is performed toward a side.