| 摘要 |
A plurality of toothed molds are formed on the respective outer peripheral surfaces of first and second rolls for shaping a fin material, each of the toothed molds having ridges extending parallel to the respective axes of the rolls. Each toothed mold includes a plurality of sets of shaping blades, each including a shaping recess, a flat portion adjoining the shaping recess, and a shaping projection adjoining the flat portion, extending at right angles to the extending direction of the ridges and arranged along the ridges. In this case, the fin material is shaped so that the shaping recesses of the first roll individually face the shaping projections of the second roll, and that the shaping projections of the first roll individually face the shaping recesses of the second roll, and louvers are formed by shearing. Draft grooves are formed in the respective opposite surfaces of the shaping projections on which the respective toothed molds of the first and second rolls engagedly adjoin one another.
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