| 摘要 |
Apparatus for forming generally triangular hollow ribs in a metal sheet including first roller die means having complementary roll surfaces defining an opening provided with a base forming section, a generally flat sheet receiving section disposed in a plane parallel to the base section and a pair of diverging sidewalls extending from opposite sides of the base section to the sheet section. Second roller die forming means having complementary roll surfaces defining an opening having a generally flat base forming section, a generally flat sheet receiving section disposed in a plane parallel to the base section and a pair of diverging sidewall sections having an included angle of less than the first die means diverging sidewall sections but greater than zero. Third roller die means having a pair of work surfaces adapted to engage the outer surfaces of the upper portions of the sidewalls of the sheet and urge the same transversely inwardly to establish a gap between the upper surfaces which is less than the transverse width of the base. Non-rotating fourth die means disposed generally transversely inwardly with respect to the third roller die means and adapted to be in supporting contact with the lower inner surfaces of the rib sidewalls and the rib base as the sheet passes through the third roller die means.
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