JP4484000B2 - Manufacturing method of lip seal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing method of a lip seal which is a kind of sealing device.
[0002]
[Prior art]
For example, when manufacturing the lip seal 51 shown in FIG. 2 , conventionally, the mold 71 shown in FIG. 3 is used to mold it.
[0003]
2 is a plug tube seal (also referred to as a plug tube gasket) that seals between the cylinder head cover 61 and the plug tube 62, and includes a mounting portion 52 in which a reinforcing ring 53 is embedded. The connecting portion 54 and the seal lip 55 provided with the garter spring 56 are integrally molded in a staggered cross section or a substantially s-shaped cross section using rubber as a molding material.
[0004]
On the other hand, the mold 71 in FIG. 3 is a combination of a plurality of divided molds, and includes a spru 72, a runner 73, an injection gate 74, and a cavity 75, and is a garter incorporated in the cavity 75 in advance prior to molding. The injection gate 74 is formed on the inner wall of the cavity 75 so as not to deviate from the fixed position even when the spring 56 is pushed by the injection pressure of the molding material 76, and a portion 75a that forms the inner peripheral portion of the seal lip base end portion 55a. It opens between the part 75b which forms the inner peripheral part of seal lip tip 55b.
[0005]
Therefore, when the lip seal 51 of FIG. 2 is formed, the lip seal 51 is first formed using the mold 71 of FIG. 3 , and then the mold is opened and released to remove the lip seal 51 from the mold 71. Then, the lip seal 51 is cut with a knife at its injection gate to remove the burr.
[0006]
However, in this prior art, as shown in FIG. 3 , a flat portion 75d is provided on the upper surface portion of the injection gate 74 of the mold 71, and the inner peripheral point of the seal lip 55 is formed from the flat portion 75d. Since the knife cut C is performed toward the portion 75c to be performed, there are the following disadvantages.
[0007]
That is, when the flat portion 75d is provided, a predetermined gap is provided between the inner peripheral portion of the seal lip base end portion 55a and the inner peripheral portion of the seal lip distal end portion 55b in the lip seal 51 that is a molded product. An annular step 55c having a width w (see FIG. 2 ) is formed, and this step 55c is a hindrance when the lip seal 51 and the plug tube 62 are assembled. That is, when the plug tube 62 is inserted into the inner peripheral side of the lip seal 51 during assembly, the tip end portion of the plug tube 62 is caught by the step 55c and a part of the connecting portion 54 of the lip seal 51 is bent. In such a case, a seal failure may occur due to poor assembly, and oil leakage may occur.
[0008]
[Problems to be solved by the invention]
In view of the above points, the present invention prevents a step from being formed between the inner peripheral portion of the seal lip base end portion and the inner peripheral portion of the seal lip distal end portion, so that assembly failure and seal failure do not occur. It is an object of the present invention to provide a manufacturing method for a lip seal.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a manufacturing method of a lip seal according to the present invention is a method for manufacturing a lip seal in which a lip seal is molded with a mold and then the inner periphery of the seal lip tip is cut with a knife. A taper shape having a linear cross section is formed between the inner peripheral portion of the seal lip and the inner peripheral portion of the seal lip tip portion, and a knife cut is performed aiming at the taper shape. the does this towards the tapered into portions comprising an inner peripheral tip of the seal lip, the inclination angle theta ₂ with respect to the central axis of the tapered in the tapered shape, the tapered at the inner peripheral portion of the seal lip proximal portion It is set larger than the inclination angle theta ₁ with respect to the central axis (θ _2> θ _1), and the inclined angle theta ₃ with respect to the center axis of the Mesukatto Is listening set (θ _2> θ _3), the rear Mesukatto C, larger cross-section straight inclination angle than those between the inner peripheral portion of the inner peripheral portion of the seal lip proximal seal lip end portion A tapered shape is formed , and the lip seal is a plug tube seal that seals between the cylinder head cover and the plug tube .
[0010]
According to the manufacturing method of the lip seal of the present invention having the above configuration, the knife cut is performed aiming at the taper shape formed between the inner peripheral portion of the seal lip base end portion and the inner peripheral portion of the seal lip distal end portion. That is, in order to perform a knife cut with this tapered shape as the starting end, a step is formed between the inner peripheral portion of the seal lip base end portion and the inner peripheral portion of the seal lip distal end portion as in the prior art. It becomes possible to prevent. In addition, the metal mold | die which manufactures the said lip seal is provided with the part provided with the shape corresponding to this instead of the plane part in the said prior art for shape | molding a taper shape .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0012]
[0013]
[0014]
[0015]
First embodiment
Manufacturing method of a lip seal according to this embodiment is a method of manufacturing the lip seal 1 shown in FIG. 1 (A), the after molding the lip seal 1 Using a mold (not shown) FIG. (B ), When the knife cut C is made at the injection gate portion, a taper shape is formed in advance between the inner peripheral portion 5c of the seal lip base end portion 5a and the inner peripheral portion 5e of the seal lip distal end portion 5b at the molding stage. 5 g (also referred to as a taper portion) is formed, and a knife cut (C) is performed from the taper shape 5 g toward the inner peripheral sharp end portion 5 d of the seal lip 5, so that the inside of the seal lip base end portion 5 a Between the peripheral portion 5c and the inner peripheral portion 5e of the seal lip distal end portion 5b, there is no flat or end step difference that becomes a hook during assembly.
[0016]
The lip seal 1 is specifically a plug tube seal (also referred to as a plug tube gasket) that seals between the cylinder head cover and the plug tube, and is connected to a mounting portion 2 in which a reinforcing ring 3 is embedded. The part 4 and the seal lip 5 provided with the garter spring 6 are integrally molded in a staggered cross section or a substantially s-shaped cross section using rubber as a molding material.
[0017]
The tapered shape 5g is and a cyclic comprises a predetermined length L, a sectional shape is linear, the inclination angle theta ₂ with respect to the center axis of the taper, of the seal lip base end portion 5a It is set to be larger than the inclination angle θ _{1 with} respect to the central axis of the taper at the peripheral portion 5 c (θ ₂ > θ ₁ ). In addition, the inclination angle θ _{3 with} respect to the central axis of the knife cut C is set to be smaller than the inclination angle θ _{2 with} respect to the central axis of the taper shape 5g (θ ₂ > θ ₃ ), and further, the inner circumference of the seal lip base end 5a It is set smaller than the inclination angle θ _{1 with} respect to the central axis of the taper in the portion 5 c (θ ₂ > θ ₁ > θ ₃ ).
[0018]
In the first embodiment , the female cut C is performed aiming at the taper shape 5g formed between the inner peripheral portion 5c of the seal lip base end portion 5a and the inner peripheral portion 5e of the seal lip distal end portion 5b. Since the knife cut C is performed from the tapered shape 5g toward the inner peripheral sharp end 5d of the seal lip 5, the inner peripheral portion 5c of the seal lip base end 5a and the inner peripheral portion of the seal lip distal end 5b It is possible to prevent the formation of a flat or end step difference between 5e and 5e, which becomes a hook during assembly. Therefore, when the lip seal 1 and the plug tube are assembled, the insertion of the plug tube can be facilitated, and it is possible to prevent the assembly failure and the seal failure from occurring. Further, this effect is maintained as long as the knife cut C is performed within the range of the tapered shape 5g even if the knife cut C position varies in the radial direction.
[0019]
【The invention's effect】
The present invention has the following effects.
[0020]
That is, in the manufacturing method of the lip seal of the present invention having the above-described configuration, the knife cut is performed aiming at the tapered shape formed between the inner peripheral portion of the seal lip base end portion and the inner peripheral portion of the seal lip distal end portion. In other words, since the knife cut is performed with this tapered shape as the starting end portion, it is caught between the inner peripheral portion of the seal lip base end portion and the inner peripheral portion of the seal lip distal end portion during assembly as in the prior art. It is possible to prevent the formation of a flat or end face level difference. Therefore, when the lip seal and the plug tube are assembled, the insertion of the plug tube can be facilitated, and it is possible to prevent the assembly failure and the seal failure from occurring. Furthermore, even if the knife cut position varies in the radial direction, this effect can be maintained as long as the knife cut is performed within the range of the tapered shape .
[Brief description of the drawings]
1 (A) is a fragmentary cross-sectional view of a lip seal manufactured by the manufacturing method according to a first embodiment of the present invention, (B) is a lip of the process explanatory view [2] Conventional Examples of the method Cross-sectional view showing the state of the seal installation [FIG. 3] Explanatory drawing of the manufacturing method according to the conventional example [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lip seal 2 Mounting part 3 Reinforcement ring 4 Connection part 5 Seal lip 5a Seal lip base end part 5b Seal lip tip part 5c, 5e Inner peripheral part 5d Inner peripheral point 5g Taper shape 6 Garter spring C Female cut

Claims (1)

In the manufacturing method of the lip seal, after forming the lip seal (1) with a mold, the inner peripheral part (5e) of the seal lip tip part (5b) is cut with a knife (C).
A taper shape (5g) having a linear cross section is formed between the inner peripheral portion (5c) of the seal lip base end portion (5a) and the inner peripheral portion (5e) of the seal lip distal end portion (5b) and the taper. Make a knife cut (C) aiming at the shape (5g),
The female cut (C) is performed from the taper shape (5g) to the portion that becomes the inner peripheral point (5d) of the seal lip (5), with the taper shape (5g) as a start end,
The inclination angle (θ ₂ ) of the taper shape (5g) with respect to the central axis of the taper is larger than the inclination angle (θ ₁ ) of the inner peripheral portion (5c) of the seal lip base end portion (5a) with respect to the central axis of the taper. Is set larger (θ ₂ > θ ₁ ) and larger than the inclination angle (θ ₃ ) with respect to the central axis of the knife cut (C) (θ ₂ > θ ₃ ), and after the knife cut (C), the seal lip Between the inner peripheral portion (5c) of the base end portion (5a) and the inner peripheral portion (5e) of the seal lip distal end portion (5b), a taper shape (5g) having a linear cross section having a larger inclination angle than these. Formed ,
The lip seal (1) is a plug tube seal that seals between the cylinder head cover and the plug tube .

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