JPS6323426B2 - - Google Patents

Description

Detailed Description of the Invention (a) Object of the Invention [Technical Field of the Invention] The present invention particularly relates to a sealing method for sealing a fluid with a seal packing in a sliding part, and more specifically, a sealing method for sealing a fluid with a seal packing on an inner or outer periphery. This invention relates to a sealing method using a seal packing having multiple stages of lips.

[Prior art and its problems]

Generally speaking, seal packing for pressure fluids is
Seal packings having a seal lip and having a Y-shaped or U-shaped cross section are superior to O-rings and the like in terms of sliding resistance and sealing performance. However, since it has a flexible lip, it is necessary to increase the rubber hardness to a certain degree in order to improve pressure resistance, but when the rubber hardness increases, it becomes difficult to mold it into a complex shape with excellent sealing properties. becomes difficult.

That is, when multiple stages of seal lips are formed on a seal packing for the purpose of improving sealing performance, there is a portion between each lip where the draft angle is reversed, making it impossible to separate the seal packing from the molding die.
Figure 1 is a cross-sectional view explaining the action of a seal packing with multiple stages of lips.
An internal sliding type having L ₁ and L ₂ is illustrated. 1
3 is a housing that holds the seal packing 2, and 3 is a shaft inserted into the lips L ₁ and L ₂ of the seal packing 2, such as a piston rod.

Regarding sealing performance, since the surface of the piston rod 3 has irregularities from a microscopic perspective, it is not possible to completely seal it with an O-ring or a lip ring with one lip. However, if there are lips in the second and third stages, any leakage in the first lip will be sealed in the second lip, so the more lips there are, the more reliable the seal will be.

Next, regarding durability, initially when the fluid pressure P is applied to the seal packing 2, the lip L ₁
is pressed against the piston 3 with pressure P, and the lip
Seal is done at L ₁ . The pressure P ₁ in the space between the lips L ₁ and L ₂ becomes equal to the pressure P ₂ outside the lip L ₂ , that is, the atmospheric pressure. As the piston rod 3 slides and the number of uses increases, the pressure P leaks little by little from the lip _L1 , and the pressure _P1 between the lips _L1 and _L2 gradually approaches the pressure P. And finally, P ₂
When only the pressure is atmospheric pressure and P ₁ =P, the beam of lip L ₁ becomes less and the sealing force by lip L ₂ becomes stronger.

As the number of uses continues, the pressure _P1 between the lips _L1 and _L2 leaks to the atmosphere due to wear of the lip _L2 , and _P1 gradually approaches atmospheric pressure _P2 . Then, a pressure difference is created again between the pressure P and the pressure _P1 , which has become atmospheric pressure, and sealing is performed again by the lip _L1 . That is, since sealing is performed alternately with the two lips L ₁ and L ₂ , the sealing period can be approximately doubled in terms of durability.

In this way, the lip packing has multiple stages of lips, which greatly improves its sealing performance and durability. By the way, in order to maintain the pressure resistance of the lip,
It is necessary to increase the rubber hardness to some extent, but if multiple stages of lips are formed, there will be a part between each lip L ₁ and L ₂ where the draft angle is opposite, making it impossible to separate the seal packing from the molding die. For this reason, although it was known that multiple stages of lips would provide better sealing performance and durability, they were not adopted.

[Technical problem of the present invention]

The technical problem of the present invention is to realize a sealing method that can easily produce a seal packing having multiple stages of lips even with a material with high rubber hardness, and that also has the same functionality as a seal packing. be.

(b) Structure of the Invention [Technical Means of the Invention] The technical means of the present invention taken to achieve this technical problem is that, in a seal packing having multiple stages of lips on the inner or outer periphery, In addition to tapering the reference surface on the side, the height of each lip is higher on the atmospheric side than on the pressure fluid side, and there is almost no depression between each lip, so there is almost no draft in the opposite direction. This seal packing is forcibly deformed in the direction in which the slope of the tape on the reference surface becomes gentler and then mounted on the device, thereby making the diameters of each lip more equal.

[Effect of technical means]

According to the technical means, the shape of the seal gasket is different before and after the gasket is installed on the device. That is, before it is installed in equipment, the diameter is gradually changed to make it tapered, and the height of the lip on the pressure fluid side of the multiple seal packings is lowered, so that there is a draft angle in the opposite direction between each lip. This eliminates the dents. After molding the seal gasket with no draft angle, when installing it on the equipment,
By compressing the large diameter part of the tapered seal packing or pushing out the small diameter part, the diameters of each part are made equal. Therefore, in the installed state, each lip has the same height, and a depression is also formed between each lip. Therefore, when the device is operated, the function of the seal packing with multiple lips is no different from that of the conventional seal packing with multiple lips. Moreover, since there is almost no reverse draft angle, the pressure resistance of the seal packing can be improved by molding it with a rubber with high hardness, and a seal packing having multiple lips can be put to practical use.

(c) Effects of the Invention As described above, according to the present invention, a seal packing with almost no reverse draft angle is manufactured, and by correcting it into the same shape as a regular seal packing during use, it is possible to manufacture a seal packing with a high hardness rubber. A seal packing with multiple lips can be realized. Therefore, the only difference from conventional seal packings is that they require correction when attached to equipment, and correction can be done by modifying the diameter of the seal packing's holding part or by attaching a correction ring. Since it can be done by just one person, the configuration does not need to be particularly complicated.

(d) Examples of the invention Next, examples will explain how the sealing method according to the invention is actually implemented. FIG. 2 shows an example in which the present invention is applied to an internal sliding seal packing, in which A is a sectional view of the seal packing before it is attached to a device, and B is a sectional view of the seal packing after it is attached to the device. The substantially cylindrical seal packing 5 has two parts on the inner circumference.
It has two lips L ₁ and L ₂ , but the inner diameter of the first lip L ₁ from the pressure acting part is larger than the inner diameter of the second lip L ₂ . That is, the lip _L2 on the atmospheric side is higher than the lip _L1 on the pressure fluid side. By increasing the inner diameter of the first lip L ₁ in this way, there is a gap between the two lips L ₁ and L ₂ .
The formation of a depression 4 as shown in FIG. 1 is avoided. That is, there is no part between the lips _L1 and _L2 that has an inner diameter larger than the tip of the lip _L1 .

The surface opposite to the lips L ₁ and L ₂ , that is, the outer peripheral surface 6, is
The reference surface 6 serves as a reference surface when attached to a device, and the reference surface ₆ is tapered so that the lip _L1 side is larger than the lip _L2 side, corresponding to the lip L1 on the side with a larger inner diameter.

With such a shape, there is almost no reverse draft during molding, and even materials with high rubber hardness can be easily separated from the mold. FIG. 6 is a sectional view showing the seal packing 5 being molded with a metal mold. The mold is 1
It consists of a pair of split molds a and b. In mold a,
The outer circumferential surface 6, end surface 7, and inner circumferential surface on the side of the end surface 7 from the tip of the lip _L2 are shaped.
In mold b, the end surface 8 of the seal packing 5 and the lip
The inner peripheral surface on the end face 8 side from the tip of _L2 is shaped. Therefore, the seal packing 5 is molded by combining the two split molds a and b and filling the cavity with hard rubber. Seal packing 5 is
As mentioned above, there is almost no recess between the two lips L ₁ and L ₂ with an inner diameter larger than the tip of the large-diameter lip L ₁ , so in the mold b for molding the part between the lips L and L ₂ , There is almost no need to provide a draft angle in the opposite direction, and the seal packing 5 can be easily released from the split molds a and b after molding. Therefore, even when molding from hard rubber with poor flexibility, it is possible to easily mold a complex seal packing having a plurality of lips.

The thus molded seal packing 5 as shown in FIG. 2A is attached to each lip L ₁ ,
Correct the inner diameter of _L2 to be equal. That is, as shown in FIG. 2B, the inner diameter of the housing 1 is all the same size, and is approximately the same size as the smallest part of the outer diameter of the seal packing 5 shown in A. Therefore, when the seal packing 5 is forcibly inserted into the housing 1, the outer diameter of the seal packing 5 becomes the same size as the inner diameter of the housing 1, as shown in B, and the inner diameter of the seal packing 5 also becomes the same size as the inner diameter of the housing 1. 8 side is reduced. As a result, the lips _L1 and _L2 have the same inner diameter at their tip ends, and the sealing action is performed under the same conditions as the seal packing 2 in FIG.

FIG. 3 shows an example in which the present invention is applied to a seal packing for external sliding, in which (a) shows the state before it is installed on the equipment, and (b) shows the state that it is installed in the equipment. In this case, the outer diameter of the lip L ₁ on the pressure fluid side is equal to the lip L ₂ on the atmosphere side.
By making it smaller than that of the two lips L ₁ ,
It is ensured that almost no depression with an outer diameter smaller than the tip of lip _L1 is formed between _L2 . Therefore, the seal packing for external sliding can also be shaped so that there is almost no draft in the opposite direction. The inner diameter is formed into a tapered surface 14 such that the outer diameter is smaller on the lip _L1 side where the outer diameter is previously reduced. When such a seal packing 9 is attached to the piston 10 as shown in (B), the outer diameters of the two lips L ₁ and L ₂ become equal, and a depression 4 is generated between the lips L ₁ and L ₂ .
In the case of external sliding, the piston 10 is installed by inserting it into the seal packing 9, but the outer diameter of the insertion part 11 into the seal packing 9 should be adjusted to match the larger inner diameter of the seal packing 9. be. Therefore, in the installed state, the lip L ₁ side of the seal packing 9 is spread out, and the two lips L ₁ ,
The outer diameters of L ₂ are equal, and both lips L ₁ and L ₂ come into sliding contact with the inner surface of the cylinder 15.

FIGS. 4 and 5 are cross-sectional views showing another embodiment of the sealing method according to the present invention, in which A is a cross-sectional view before the sealing method is installed on a device, and B is a cross-sectional view of the sealing method before it is installed on the device. The inner sliding seal packing 5 in Fig. 2 has a reduced diameter on the lip _L1 side of the housing 1;
Figure 4 shows the end face 7 on the lip _L2 side of the expansion ring 12.
By inserting it into the inner surface of the side, the inner diameter of the lip L ₂ is expanded, thereby making the inner diameters of the two lips L ₁ and L ₂ the same.

In addition, the seal packing 9 for external sliding shown in Fig. 3 is
The diameter on the lip _L1 side is expanded by the piston shaft 11, but in Fig. 5, the reduction ring 13 is
By fitting it to the outer periphery of the end face 7 side on the L ₂ side, the lip
By reducing the outer diameter of L ₂ , two lip
The outer diameters of L ₁ and L ₂ are the same.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional seal packing, Figure 2 is a cross-sectional view of a conventional seal packing.
5 to 5 show each embodiment of the sealing method according to the present invention. In each figure, A shows the state of the seal packing before it is attached to the equipment, B shows the state that it is attached to the equipment, and FIG. 6 shows the state of the seal packing according to the present invention. FIG. 3 is a cross-sectional view showing a method of molding a seal packing according to the method of the present invention. In the figure, 4 is a recess, 5 is an inner sliding seal packing, L ₁ and L ₂ are lips, 9 is an outer sliding seal packing, 6 is an outer peripheral surface (reference surface), and 14 is an inner peripheral surface (reference surface). Each is shown below.

Claims (1)

[Claims] 1 In a seal packing that has multiple stages of lips on the inner or outer periphery, the reference surface on the opposite side to the lip has a taper, and the height of each lip is higher on the atmosphere side than on the pressure fluid side, and the height between each lip is higher than on the pressure fluid side. By creating a shape with almost no depressions, the shape has almost no draft in the opposite direction,
A sealing method characterized by forcibly deforming this seal packing in a direction in which the taper of the reference surface becomes gentler and mounting it on a device so that the diameters of each lip become more equal.