Tapered roller wheel bearing assembly

1. A tapered roller wheel bearing assembly comprising:

a hub provided with a hub flange for mounting a wheel formed radial outwardly at an end portion thereof and a hub raceway formed at a side portion close to the hub flange;

an outer ring enclosing the hub and provided with an outer raceway corresponding to the hub raceway on an interior circumference thereof;

a tapered roller disposed between the hub raceway and the outer raceway and allowing a relative rotation of the hub and the outer ring;

a first sealing member for preventing inflow of foreign material, the first sealing member mounted between the hub flange and an end of the outer ring; and

a second sealing member for preventing inflow of foreign material, the second sealing member mounted between an interior circumference of the other end portion of the outer ring,

wherein a flange base is formed between the hub flange and the hub raceway and a first undercut for grinding the hub raceway is formed at the flange base,

wherein a second undercut for dispersing stress concentrated on the first undercut is further formed at the flange base, and

wherein the first undercut and the second undercut formed at the flange base are located in between the first sealing member and the second sealing member.

2. The tapered roller wheel bearing assembly of claim 1 , wherein the second undercut is formed at a radial outside of the first undercut and spaced apart from the first undercut by a predetermined distance.

3. The tapered roller wheel bearing assembly of claim 1 , wherein a size of the second undercut is larger than a size of the first undercut.

4. The tapered roller wheel bearing assembly of claim 1 , wherein a pilot for supporting the wheel is protruded in an axial direction at a side surface of the hub and the second undercut is formed at the same radial position as the pilot substantially.

5. A tapered roller wheel bearing assembly comprising:

a hub provided with a hub flange for mounting a wheel formed radial outwardly at an end portion thereof, a stepped portion formed at an exterior circumference of the other end portion thereof, and a hub raceway formed at an exterior circumference between the hub flange and the stepped portion;

an inner ring press-fitted on the stepped portion of the hub and provided with an inner raceway formed at an exterior circumference thereof;

an outer ring enclosing the hub and the inner ring and provided with first and second outer raceways corresponding to the hub raceway and the inner raceway and formed at an interior circumference thereof;

a first tapered roller disposed between the hub raceway and the first outer raceway and allowing a relative rotation of the hub or the inner ring and the outer ring;

a second tapered roller disposed between the inner raceway and the second outer raceway and allowing the relative rotation of the hub or the inner ring and the outer ring;

a first sealing member for preventing inflow of foreign material, the first sealing member mounted between the hub flange and an end of the outer ring; and

a second sealing member for preventing inflow of foreign material, the second sealing member mounted between an interior circumference of the other end portion of the outer ring and an exterior circumference of the inner ring,

wherein a flange base is formed between the hub flange and the hub raceway and a first undercut for grinding the hub raceway is formed at the flange base,

wherein a second undercut for dispersing stress concentrated on the first undercut is further formed at the flange base, and

wherein the first undercut and the second undercut formed at the flange base are located in between the first sealing member and the second sealing member.

6. The tapered roller wheel bearing assembly of claim 5 , wherein the second undercut is formed at a radial outside of the first undercut and spaced apart from the first undercut by a predetermined distance.

7. The tapered roller wheel bearing assembly of claim 5 , wherein size of the second undercut is larger than that of the first undercut.

8. The tapered roller wheel bearing assembly of claim 5 , wherein a pilot for supporting the wheel is protruded in an axial direction at a side surface of the hub and the second undercut is formed at the same radial position as the pilot substantially.

9. The tapered roller wheel bearing assembly of claim 5 , wherein the second undercut is positioned at a radial inside from the first sealing member.