JPS5920056B2 - Oil seal and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oil seal and a method for manufacturing the same, and more particularly to a structure and method for manufacturing an oil seal that has low frictional resistance on the sliding surface of its lip and maintains sufficient sealing performance. It is.

In oil seals, the seal lip is pressed against the shaft surface in order to maintain seal performance, but in these types of machines, it is required to keep the sliding friction resistance caused by the pressure contact force as low as possible. Ru.

As a countermeasure against this problem, an oil seal is known in which a sheet-like fluororesin material is attached to the sliding surface of the lip portion that slides on the outer peripheral surface of the shaft.

The sliding friction between a fluororesin material and a metal surface is smaller than that of the rubber material normally used as an oil seal material against a metal surface. The attached oil seal exhibits lower sliding friction resistance than an oil seal made only of rubber material.

However, since fluororesin materials are inferior in flexibility to ordinary rubber materials, oil seals with fluororesin sheets pasted all around the sliding surface have poor followability to the shaft circumferential surface, and rubber materials It has the disadvantage of being inferior in sealing performance compared to ordinary oil seals made of chisel.

The present invention aims to eliminate the drawbacks of the conventional oil seal in which a fluororesin sheet is attached to the lip sliding surface as described above. Production method? This is what we present.

In the oil seal of the present invention, a plurality of small pieces of fluororesin sheets are arranged circumferentially on the sliding surface of the lip portion.
The surface of the rubber parts arranged alternately in the circumferential direction and the surface of the fluororesin sheet slide against the shaft circumferential surface. In addition to reducing resistance, due to the flexibility of the rubber material,
This ensures that the lip portion can follow the circumferential surface of the shaft.

The production of the oil seal in which a plurality of small pieces of fluororesin sheets are arranged and buried in the circumferential direction on the lip sliding surface is manufactured by attaching a whole inside for cutting off the oil seal at the tip of the main lip part. When molding the seal material, for example, by punching a fluororesin sheet material, the annular portion and the annular portion 75 are formed.
A fluororesin sheet with multiple tongue-like pieces that extend and are arranged in the circumferential direction? Prepare an annular fluororesin sheet and attach it to the sliding surface side of the seal lip so that the annular part is located on the side of the excess material for cutting off to form an oil seal material. The main lip portion is formed by cutting off the excess wall portion and the annular portion of the fluororesin sheet.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a conventional example of an oil seal having a fluororesin sheet attached to a sliding portion, and an oil seal and manufacturing method of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a low-torque oil seal according to the prior art, in which an annular and band-shaped fluororesin sheet 3 is pasted on the sliding surface 2 side of the main lip portion 1, and the surface of the fluororesin sheet 30 rotates around the axis during movement. Since it is configured to slide on the circumferential surface, the frictional resistance at the sliding part is kept low, but since the fluororesin sheet 3 is continuous over the entire circumference, the ability to follow the shaft circumferential surface is weak. , sufficient sealing performance cannot be expected.

FIG. 2 shows an embodiment of an oil seal according to the present invention.

On the sliding surface 2 side, a plurality of small pieces 5 of fluororesin sheets arranged on the circumference & the surface 51 of the small sheet pieces and the rubber portion 4
0 surface 41 form the same surface, and the ridge edge 52 of the sheet small piece and the seal lip ridge edge 42 of the rubber portion are buried in a line.

In mechanical devices using this oil seal, since the fluororesin sheet is not formed into a continuous annular body over the entire circumference, the flexibility of the rubber portion maintains the ability of the lip portion to follow the circumferential surface of the shaft. Sliding frictional resistance is reduced due to the low friction properties of fluororesin materials.

In the embodiment shown in Fig. 2, the planar shape of the fluororesin sheet is approximately an equilateral triangle, but it can also be shaped into a narrow strip or other suitable shape, and the axial and circumferential dimensions can also be changed. It can be selected as appropriate.

In another embodiment of the present invention shown in FIGS. 3 and 4, the small piece 5 of the fluororesin sheet has a relatively narrow triangular shape and has an axis of rotation indicated by an arrow in the figure. With respect to the direction, the front edge 53 of the small piece 5 of the fluororesin sheet is inclined so that it recedes in the circumferential direction from the atmosphere side A to the liquid side B in the axial direction and in the rotation direction, and the 1y knob slides. It is buried in surface 2.

That is, as shown in the 4th i-minute enlarged view, -153-, 54 of the small piece 5 of the fluororesin sheet are located at the edge 52 of the same small piece.
One of the angles α and β between the two is an obtuse angle.

When this oil seal is used, due to the difference in flexibility between the non-fluorine resin part 5 and the rubber part 4Q, the edge 53 of the small piece of the fluororesin sheet exhibits the function of the thread in a threaded oil seal, preventing it from leaking to the atmosphere. It has the effect of forcing the moisturizing agent back toward the liquid side.

That is, by embedding small pieces of the fluororesin sheet, the sealing performance can be further improved.

5 and 6 illustrate a method of manufacturing an oil seal according to the present invention.

In the first stage of manufacturing, a triangular tongue-like shape extending outward from the outer periphery 62 of the annular portion 61 is formed by punching or other methods from a fluororesin sheet having a predetermined thickness, as shown in FIG. The pieces 63 are formed into a shape in which a plurality of pieces 63 are tightly arranged on the outer periphery 62.

The diameter of the outer periphery 62 of the annular portion is smaller than the diameter of the tip of the lip in the product shown by the chain line in FIG. The slope 64 is appropriately set to match the shape and size of the small piece of fluororesin sheet in the product and the slope of the edge.

In the next step of the molding process, the fluororesin sheet molded as described above is placed on the part of the oil seal mold (not shown) where the sliding surface part 2 is to be molded, and compression molding is performed simultaneously with the rubber material. , the product in the state shown in FIG. 6 is molded, and in the subsequent cutting process, the part indicated by the arrow in FIG.
is removed, and a lip edge 71 shown with a chain line in the figure is formed to complete the fabrication.

Thus, it is shown in Figure 2 or Figure 3! An oil seal is obtained in which a plurality of small pieces 5 of fluororesin sheets are arranged and embedded on the circumference in the sliding surface of the lip portion.

As described above, according to the present invention, it is possible to easily and accurately obtain an oil seal material that has low sliding frictional resistance during use and has excellent sealing performance.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an example of a low-friction torque oil seal according to the prior art, FIG. 2 is a vertical cross-sectional view showing an example of an oil seal according to the present invention, and FIG. 3 is a vertical cross-sectional view showing an example of an oil seal according to the present invention. A vertical sectional view showing another embodiment, FIG.
FIG. 5 is a plan view showing the shape of the fluororesin sheet used in manufacturing the oil seal according to the present invention, and FIG. 6 is a partially enlarged view of the embodiment shown in the figure. FIG. FIG. 3 is a longitudinal cross-sectional view showing the processing situation. 1... Main lip part, 2... Sliding surface, 3
...Fluororesin annular sheet, 4...Sliding surface rubber part, 41...Rubber part surface, 42...
... Edge of rubber part, 5 ... Small piece of fluororesin sheet, 51 ... Surface of small sheet piece, 52 ...
... Edge edge of sheet small piece, 53 ... Front edge of sheet small piece, 61 ... Fluororesin sheet ring part, 62
...... Annular part outer periphery, 63 ...... Tongue-shaped piece, 6
4...Front edge of tongue, I...Cut-off part, A...Atmospheric side, B...Liquid side, α, β
...Angle between the edge and the edge of a small piece of fluororesin.

Claims (1)

[Scope of Claims] 1. An oil seal in which a plurality of small pieces 5 of fluororesin sheets are embedded in the lip sliding surface 2 including the tip of the lip of the main lip portion 1 in a circumferential direction. 2. The oil seal according to claim 1, wherein at least one of the angles α and β formed between the ridge 52 of the small piece 5 of the fluororesin sheet and each of both edges 53 is an obtuse angle. 3. A fluororesin sheet having a cutout 1 at the tip of the main lip 1, an annular portion 61, and a plurality of tongue-like pieces 63 extending outward from the annular portion 61 and arranged in the circumferential direction. An oil seal material is formed so that the annular portion 61 is located on the cut-out portion r side and is embedded on the lip sliding surface 2 side of the main lip portion 1, and then the cut-out portion 7 is cut. A method of manufacturing an oil seal in which a plurality of small pieces 5 of fluororesin sheets are arranged in the circumferential direction and form the main lip part 1 embedded in the lip sliding surface 2 side.