| 摘要 |
The frame is U-shaped with parallel arms (13), being made from a steel strip (12) whose length is equal to the sum of the lengths of the frame sections. Where the corners are to be formed, coaxial 90 deg. notches (14,15) are cut in the opposite edges, their depth being equal to that of the flanges to be formed at each edge. Between the notches in each pair, the strip is further weakened by punching out one or more holes (16), after which the strip edges are bent over into flanges forming travel tracks. The strip sections are finally bent at the notches to form the U-shaped frame. |
