| 摘要 |
PURPOSE:To bend a plate material with high accuracy without avalanche while maintaining the parallel between top and bottom dies by detecting the displacement at the longitudinal center of upper and lower aprons during bending of said material and curving at least one of the top and bottom dies. CONSTITUTION:When a plate material is disposed on a bottom die 5 of a press brake 1 and the pressing between said die and a bottom die 5 is started, the die 13 and an upper apron 11 curve to project upward integrally. An upper apron 11 attached with an automatic length measuring device 25 on the dog 27 at the center of a stretching plate 23 ascends relatively at this time. The displacement is detected and is informed to a control device. A fluid pressure cylinder 29 forces upward the part around the center of a lower apron 5 according to the displacement, then the die 5 curves integrally as well so that the part around the center of said die moves upward. The dies 5 and 13 are thus automatically curved relatively with the curving displacement generated during the working, by which the parallel between the two dies is maintained. |
