| 摘要 |
A rotary cutting apparatus for forming serially connected envelope blanks from a longitudinally advancing web of sheet material is provided with two rotary knives, both of which rotate into cutting relationship with the same stationary knife but at different times. The web of sheet material is advanced over the stationary knife so that at least one side of the web is positioned between the stationary knife and each of the rotary knives to remove a section at the side of the web. With two sets of rotary and stationary knives operating respectively on the two sides of the web, a series of interconnected envelope blanks can be formed by feeding the web through the cutting apparatus at a speed coordinated with the rotations of the knives. By adjusting the angular relationship of the two rotary knives with respect to one another about the axis of rotation, the section of sheet material removed from the advancing web can be varied correspondingly. Such adjustment in conjunction with a change in the feed rate of the web permits envelope blanks, and resulting envelopes, of different sizes to be formed with the same cutting apparatus.
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