Field of the Invention
The present invention relates to a method of manufacturing a sealing device which seals a moving part of a device with a seal lip which is integrally formed in a reinforcing ring.
Description of the Conventional Art
As a sealing means for a bearing portion which rotatably supports a wheel to a wheel suspension device for a motor vehicle, there has been conventionally known a sealing device, for example, as described in Japanese Unexamined Patent Publication No. 2008-281013.
FIG. 7 shows a sealing device which is the same kind as that described in Japanese Unexamined Patent Publication No. 2008-281013 in a used state, reference numeral 110 denotes an outer ring of a bearing which rotatably supports a wheel to a wheel suspension device for a motor vehicle, and reference numeral 120 denotes a hub in which a center shaft portion 122 thereof is inserted to the outer ring 110 and the wheel (not shown) is attached to an attachment flange 121. A plurality of spherical bodies (not shown) arranged at predetermined intervals in a circumferential direction are retained to a bearing internal space S in a lower left side in the drawing so as to freely roll on a track (not shown) which is formed in an outer peripheral surface of the center shaft portion 122 and an inner peripheral surface of the outer ring 110, and a bearing unit is constructed by the center shaft portion 122 of the hub 120, the outer ring 110 and the spherical bodies.
A sealing device 100 is interposed between an inner peripheral surface of an outer end portion of the outer ring 110 and the outer peripheral surface of the center shaft portion 122 in the hub 120. The sealing device 100 is structured such as to prevent a foreign material such as rain water, muddy water or dusts from intruding into the bearing internal space S from an external portion A, and prevent grease filled in the bearing internal space S from leaking to the external portion A.
In detail, the sealing device 100 is constructed by a reinforcing ring 101 made of metal, a labyrinth lip 102, anti-dust lips 103 and 104, and an anti-grease lip 105 as shown in FIG. 8. The labyrinth lip 102, the anti-dust lips 103 and 104 and the anti-grease lip 105 are made of a rubber-like elastic material (a rubber material or a synthetic resin material having a rubber-like elasticity), and is integrally vulcanization bonded to the reinforcing ring 101 via a coating layer 106 which is made of the same rubber-like elastic material.
Further, the labyrinth lip 102 in the outermost diameter side is moved close to and faced to an end surface of the attachment flange 121 of the hub 120 in a non-contact manner, the labyrinth lip 102 in the outermost diameter side being positioned in a back surface side of an outer diameter flange portion 101b which is developed like a disk to an outer peripheral side of the outer ring 110 from an end portion of a fitting tube portion 101a which is pressed into and fitted to an inner peripheral surface of the outer ring 110. As a result, the reinforcing ring 101 serves as a labyrinth seal.