| 摘要 |
A box tube blank having first, second, third, and fourth panels joined together at first, second, third, and forth creases is broken in starting with the blank oriented in a starting plane with the first and third creases superposed and the second and fourth creases outermost. First the second and fourth creases are pressed toward each other parallel to the starting plane to spread the first and third creases away from each other until the second and fourth creases are juxtaposed and the first and third creases lie outermost and the blank lies generally perpendicular to the starting plane. Then the tube blank passes between an upstream pair of parallel rollers extending perpendicular to the starting plane to compress it parallel to the starting plane. Thereafter the first and third creases are pressed toward each other perpendicular to the starting plane to spread the second and fourth creases away from each other until the first and third creases are juxtaposed and the second and fourth creases lie outermost and the blank lies generally parallel to the starting plane. The tube blank then passes between a downstream pair of parallel rollers extending parallel to the starting plane to compress it perpendicular to the starting plane. |
