| 摘要 |
<p>The frame (1), having a rectangular inverted U-shaped crosssection with one or more thrust surfaces (3, 4) to receive the sole of a boot, and one or more side flanges (2), is made from a cut-out sheet metal shape, stamped to form curved reinforcing ribs (8) in the flange(s), and then folded. The flanges have fixing holes (6) for blade, wheels or rollers, and the frame can be made from a number of components joined by screws, rivets or welding.</p> |
