JPH0546471B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a rotary oil seal used for sealing between two rotating members concentrically assembled, and particularly to an oil seal having a seal lip with a threaded groove on the seal surface. This invention relates to a seal and its manufacturing method.

(Prior Art) Conventionally, there is an oil seal of this type as shown in FIG. 8 (U.S. Patent No.
3985487 specification). That is, 100 is a seal lip made of plate-shaped polytetrafluoroethylene resin (hereinafter referred to as PTFE), and the base end 101 is assembled to a support member 103 that is fitted to the inner circumference of the housing 102. It is being Seal lip 1
00 extends obliquely toward the rotating shaft 104, and its tip portion slides into contact with the rotating shaft 104 to form a seal portion 105. This seal lip 1
00 is provided with a thread groove 106 of a predetermined width from the tip of the lip on the side surface facing the atmosphere, which seals the fluid leaking from the seal portion 105 to the atmosphere side due to the screw pump action caused by the relative rotation between the rotating shaft 104 and the seal lip 100. It was pushed back to the fluid side to improve sealing performance.

(Problem to be solved by the invention) However, in the case of such a conventional example, the thread groove 106
is provided continuously over the entire length of the sealing surface 107 from the tip of the lip of the seal lip 100 to the atmosphere side, and the sealed fluid side and the atmosphere side are in communication via the thread groove 106, so that the seal lip 100 and the rotating shaft 104 are connected to each other. Although the screw pump action works when the screws rotate relative to each other, there is a problem in that when the screws are stationary, the sealing fluid O leaks to the atmosphere through the screw grooves 106.

The present invention has been made to solve the problems of the prior art described above, and its purpose is to provide an oil seal that can prevent fluid leakage when stationary while maintaining the screw pump function, and Another object of the present invention is to provide a simple manufacturing method.
Another object of the present invention is to provide an oil seal and a method for manufacturing the same, which allow a non-flexible resin plate-shaped seal lip to follow the eccentricity of a rotating member such as a rotating shaft.

(Means for Solving the Problems) In order to achieve the above object, in the oil seal of the present invention, there is no thread on the sealing surface of the seal lip, which is made of resin and has a plate shape and has a thread groove over its entire length. In addition to providing a region, the depth of the thread groove is increased toward the support member side.

In addition, in the method for manufacturing an oil seal of the present invention, the end face of a resin cylinder is formed into a tapered surface by cutting the end face at a predetermined angle with respect to an axis perpendicular to the central axis of the cylinder. , on the tapered surface,
A thread cutting process in which a spiral thread groove is carved by a thread cutting means leaving a part of the threadless area; and a tapered plate-shaped plate having an annular tapered surface is cut by cutting the end of the cylindrical body at a predetermined width. The process consists of a step of forming a seal lip, and a step of assembling the seal lip onto a support member with the threaded side of the sealing lip as a sealing surface. The depth is set to become deeper toward the support member.

(Example) The present invention will be explained below based on the illustrated example. In FIG. 1 showing an oil seal according to an embodiment of the present invention, reference numeral 1 denotes a metal-shaped oil seal having a seal lip 2, and the seal lip 2 is made of a resin plate such as PTFE.
A base end portion 2a thereof is assembled to a support member 4 fixed to the inner periphery of the housing 3. The support member 4 includes, for example, an outer cylinder 5 and an outer cylinder 5 that are fitted into the housing 3.
The base end 2a of the seal lip 2 is pinched between an atmosphere-side flange 5a on the side edge of the outer cylinder 5 and an atmosphere-side flange 6a on the side edge of the inner cylinder 6, and the seal lip 2 is pressed outward. It is assembled by caulking the side edge of the cylinder 5 on the sealed fluid side (right side in the figure).

The sealing lip 2 extends from its base end 2a toward the sealed fluid side, and the tip of the lip is in sealing contact with the surface of the rotating shaft 7, which rotates relative to the housing 3 (in this embodiment, the housing 3 is fixed and the shaft 7 rotates). A seal portion 8 is formed.

That is, the inner diameter of the seal lip 2 is smaller than the outer diameter of the rotating shaft 7, and when it is assembled to the rotating shaft 7, the lip tip 2b is expanded in diameter, and the lip tip 2b is expanded in diameter.
A portion of a predetermined width from the tip contacts the shaft surface and forms a sealing surface 10. The sealing surface 10 of the sealing lip 2 is provided with a threaded groove 9. The starting end of the thread groove 9 on the lip tip side is formed from the atmospheric side by a predetermined width L from the lip tip, and the area from the lip tip to the starting end of the thread groove 9 is a non-threaded area 10a. Therefore, the sealing surface 10 is in close contact with the surface of the rotating shaft 7 over the entire circumference in the non-threaded region 10a without any gaps. The end of the thread groove 9 extends from the sealing surface 10 of the seal lip 2 to the atmosphere-side side surface 1.
0', and the depth of the thread groove 9 becomes deeper toward the support member 4 side, that is, toward the base end portion 2a.

In the case of the oil seal having the above configuration, the rotating shaft 7
When the seal lip 2 and the seal lip 2 rotate relative to each other, the seal part 8
Fluid O leaking from the unthreaded area 10a to the atmosphere side
is pushed back toward the sealed fluid side by the screw pump action of the thread groove 9 following the non-threaded region 10a, thereby preventing fluid leakage. Furthermore, when the rotating shaft 7 and the seal lip 2 are relatively stationary, the atmosphere side and the sealed fluid side are blocked by the unthreaded area 10a, preventing fluid leakage. Since the seal lip 2 is made deeper toward the support member 4, the non-flexible resin seal lip 2 is easily bent, so that it has flexibility and can follow the eccentricity of the rotating shaft 7.

In the above embodiment, the non-threaded region 10a is provided at the tip of the seal lip 2, but it is only necessary that a portion of the sealing surface 10 be the non-threaded region.

Next, a method for manufacturing an oil seal according to the present invention will be explained with reference to FIG. In the figure, 11 is
It is a cylindrical body made of resin such as PTFE, and is attached to a lathe etc. so that it can rotate freely around its central axis. A cutting means 12 for cutting out the end of the resin cylinder 11 into a plate shape, and a thread cutting means 13 for carving a spiral thread groove on the end surface are disposed on the outer periphery of the resin cylinder 11. The cutting by the cutting means 12 cuts the outer periphery of the resin cylindrical body 11 along an A-line direction inclined at an angle α with respect to an axis (hereinafter referred to as the Y-axis) orthogonal to the central axis of the resin cylindrical body 11 (hereinafter referred to as the X-axis). Cutting is performed from the side toward the inside in the radial direction, and the end surface of the resin cylindrical body 11 is a tapered surface that is inclined at an angle α toward the inner diameter. Thread cutting means 1
3 is adapted to move from the inner circumferential side to the outer circumferential side of the resin cylindrical body 11 along the Y-axis direction.

In the thread cutting process by the thread cutting means 13, the cutting edge at the tip of the thread cutting means 13 is positioned between the inner peripheral edge position and the outer peripheral edge position in the central axis direction of the resin cylindrical body 11, and move at a constant speed. As the resin cylindrical body 11 is moved, the cutting edge of the thread cutting means 13 comes into contact with the end face of the resin cylindrical body 11 at a position advanced by a predetermined width from the inner circumferential end of the resin cylindrical body 11 and starts cutting the thread, and the rotation of the resin cylindrical body 11 and the thread cutting means 13 As a result of this movement, a single thread groove 9 is carved in a spiral shape, and after cutting the thread groove 9 by a predetermined width, the thread cutting means 13 is separated from the end surface of the resin cylindrical body 11 to complete thread cutting. As a result, the resin cylindrical body 11
On the end face, there is a non-threaded area 1 by a predetermined width from the inner peripheral edge.
0a is automatically formed, and subsequently a thread groove 9 of a predetermined width is formed. Since the thread groove 9 has a tapered surface inclined by an angle α, it is carved shallowly on the inner diameter side and deeper toward the outer diameter side, as shown in FIG. The width of the non-threaded area 10a is narrower because if the X-axis position of the thread cutting means 13 is brought closer to the end surface of the resin cylindrical body 11, the cutting of the thread groove 9 will start earlier. It's slower, wider, and easier to adjust. Note that if a plurality of thread cutting means 13 are used, a plurality of thread grooves 9 can be formed.

After threading, the end portion of the resin cylindrical body 11 is cut into a plate shape with a predetermined thickness by the cutting means 12. That is, the position of the cutting means 12 in the X-axis direction is set inward by a predetermined thickness from the end surface of the resin cylindrical body 11, and the cutting means 12 is moved along the A-line direction while rotating the resin cylindrical body 11, thereby cutting an annular shape. A tapered plate-shaped seal lip 2 having a tapered surface is cut out. Furthermore, this seal lip 2 is
It is assembled to a support member 4 as shown in the figure. To explain the oil seal shown in FIG. 1, the seal lip 2 is fitted from the sealed fluid side end of the outer cylinder 5, and then the inner cylinder 6 is fitted to the base end 2 of the seal lip 2.
a is the atmosphere side flange 5a of the outer cylinder 5 and the inner cylinder 6,
6a, and the sealing fluid side end edge of the outer cylinder 5 is caulked radially inward to complete the assembly of the oil seal. In this way, by assembling the seal lip 2 in which the thread groove 9 is shallow on the inner diameter side and deeper toward the outer diameter side to the support member 4, the depth of the thread groove 9 becomes deeper toward the support member 4 side. , therefore,
The process of increasing the depth of the thread groove 9 toward the supporting member 4 is performed by attaching the thread cutting means 13 to the tapered surface formed by cutting the thread groove 9 at an angle α as explained above.
This can easily be done by moving only in the Y-axis direction and thread cutting.

In the above embodiment, the seal lip 2 was formed into a tapered shape over the entire width from the inner diameter side to the outer diameter side.
As shown in FIG. 4, only the inner diameter side may be tapered. In this case, the inner diameter side of the end surface of the resin cylindrical body 11 is formed into a tapered surface, and the thread cutting means 1
3, the thread groove 9 is carved in the same manner as in the above embodiment to form the unthreaded region 10a and the thread groove 9, and the depth of the thread groove 9 is set to be shallower on the inner diameter side and deeper toward the outer diameter side. will be established. After providing the thread groove 9, the plate-shaped seal lip 2 is cut out by the cutting means 12, but the cutting direction is not inclined so that the resin cylindrical body 11
Cut in a direction perpendicular to the central axis of the Thereafter, the seal lip 2 is integrally assembled to the support member 4.

In the oil seal having the seal lip 2 formed in this manner, the tip end portion 2b of the lip has a thin shape as shown in FIG. Dynamic resistance is reduced. Furthermore, the tip end portion 2b of the lip is elongated when attached to the rotating shaft 7, but because of its thin wall, it is easy to extend and fits easily with the surface of the rotating shaft 7, so that good sealing performance can be obtained.

In the above embodiment, the seal lip 2 is in sliding contact with the rotating shaft 7, but in the case of an oil seal of the type in which the seal lip 2 is in sliding contact with the inner periphery of the housing 3 as shown in FIG. As shown in the figure, the end face of the resin cylindrical body 11 is formed into a tapered shape in which the inner diameter side protrudes from the outer diameter side, and the thread cutting means 13 is cut in the Y-axis direction from the outer circumference side toward the inner circumference side in the same manner as in the above embodiment. By moving the threaded groove 9 to the inner diameter side, the threadless region 10a can be automatically formed, and the depth of the thread groove 9 is set to be shallower on the outer diameter side and deeper toward the inner diameter side. That is, it becomes deeper toward the support member 4 side.

Regarding the shaping of the non-threaded region 10a, in the above embodiment, the end surface of the resin cylindrical body 11 is tapered and this slope is utilized to form the shape. The movement of the thread cutting means 13 may be controlled such that the thread cutting means 13 is formed by temporarily separating from the end surface of the resin cylindrical body 11.

(Effects of the Invention) The present invention has the above-described structure and operation, and in the oil seal of the present invention, a non-threaded region is provided on the sealing surface of the seal lip provided with a thread groove. The seal lip is closely fitted around the entire circumference of a rotating member such as a rotating shaft without any gaps, and can prevent fluid leakage when the seal lip and rotating member are relatively stationary, and can also prevent fluid leakage when the seal lip and rotating member are relatively stationary. Fluid leaking from the non-threaded area to the atmosphere is pushed back by the thread pump action of the thread groove, resulting in the effect that good sealing performance can be ensured. Since the depth of the thread groove is increased toward the support member, the non-flexible resin seal lip is easily bent and has flexibility. Therefore, the ability to follow the eccentricity of the rotating member can be achieved.

Furthermore, in the method for manufacturing an oil seal of the present invention, the threaded groove and non-threaded area of the seal lip can be easily processed by a thread cutting means, and the threaded groove can be carved deeper toward the supporting member side. At this time, the end surface of the resin cylinder is cut at a predetermined angle such that the thread groove becomes deeper toward the support member with respect to the axis perpendicular to the central axis of the cylinder. It can be easily processed by moving only in the axial direction using the thread cutting means, and the seal lip can be continuously formed by cutting the cylindrical body, resulting in high productivity and low cost. The effect of being able to manufacture oil seals is obtained.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of an oil seal according to an embodiment of the present invention, FIG. 2 is a schematic perspective view of a manufacturing apparatus using the method for manufacturing an oil seal according to an embodiment of the present invention, and FIG. The figure is a vertical sectional view of the main part of the seal lip formed by the device shown in Fig. 2, and Fig. 4 is a longitudinal sectional view of the main part of the seal lip formed by the
FIG. 5 is a vertical cross-sectional view of a main part showing another aspect of the seal lip formed using the apparatus shown in FIG. The figure is a vertical cross-sectional view of a main part of an oil seal according to another embodiment of the present invention, and FIG.
FIG. 8 is a schematic perspective view of a manufacturing apparatus for forming the seal lip of the oil seal shown in FIG. 8, and FIG. Explanation of symbols, 1...Oil seal, 2...Seal lip, 4...Support member, 9...Thread groove, 10
... Sealing surface, 10a ... Threadless area, 11...
... Resin cylindrical body (cylindrical body), 12 ... Cutting means, 1
3... Thread cutting means.

Claims (1)

[Scope of Claims] 1. An oil seal in which a plate-shaped seal lip made of resin and having a thread groove over the entire length of the seal face is assembled to a support member, wherein a non-threaded area is provided on the seal face of the seal lip, and An oil seal characterized in that the depth of the thread groove is increased toward the supporting member side. 2. A tapered surface is formed by cutting the end surface of a resin cylindrical body at a predetermined angle with respect to an axis perpendicular to the central axis of the cylindrical body, and on the tapered surface,
A thread cutting process in which a spiral thread groove is carved by a thread cutting means leaving a part of the threadless area; and a tapered plate-shaped plate having an annular tapered surface is cut by cutting the end of the cylindrical body at a predetermined width. The process consists of a process of forming a seal lip, and a process of assembling the seal lip onto a supporting member using the tapered surface side provided with a thread groove as a sealing surface. A method for manufacturing an oil seal in which the oil seal is set to become deeper toward the supporting member side.