MIXING BLADE

1 . A mixing blade formed into a spiral shape by disposing blade plates, which are twisted in a predetermined manner in a circumferential direction of the blade, adjacent to each other in the circumferential direction along an inner wall surface of a mixer drum,

wherein each of the blade plates comprises a rib extended in the circumferential direction of the blade.

2 . The mixing blade as defined in claim 1 , wherein the rib is formed by making a recess in a back surface side of the blade plate and making a projection on a front surface side of the blade plate.

3 . The mixing blade as defined in claim 1 , wherein the blade plate further comprises positioning holes engaging with positioning pins of a shaping die in press-forming processing, at both ends in the circumferential direction of the blade.

4 . The mixing blade as defined in claim 1 , wherein the blade plate further comprises a longitudinal rib extended in a radial direction that is perpendicular to the circumferential direction of the blade.

5 . The mixing blade as defined in claim 1 ,

wherein the blade plate has edge areas formed to curve in a radial direction that is perpendicular to the circumferential direction of the blade, and

wherein the rib is provided at a position near the edge area in a central area located between the edge areas that are on an outer side and an inner side in the radial direction.

6 . The mixing blade as defined in claim 1 , wherein the rib is formed to have a height equal to or higher than a thickness of the blade plate and have a width equal to or wider than the thickness of the blade plate.

7 . The mixing blade as defined in claim 4 , wherein the longitudinal rib is formed to have a height equal to or higher than a thickness of the blade plate and have a width equal to or wider than the thickness of the blade plate.