A trimming method for a rectangular container, which is to be used for a trimming device for a rectangular container, the trimming device being configured to cut a rectangular container along a plane including a predetermined trim line parallel to a bottom surface, the rectangular container having one end opened and a bottom portion at the other end and having a transverse cross-sectional shape parallel to the bottom surface being a rectangular shape, the trimming device including:
- a die, which is integrally supported on a trimming device main body, accommodates an outer periphery of the rectangular container, and is arranged along the trim line;
- a punch, which is accommodated inside the rectangular container with a predetermined gap with the transverse cross-sectional shape inside the rectangular container, and is supported on the trimming device main body so as to be movable within a plane parallel to the bottom surface;
- a long-axis direction drive unit, which is configured to move the punch along a long-axis direction in the transverse cross-sectional shape of the rectangular container;
- a first short-axis direction drive unit, which is configured to move the punch along a short-axis direction in the transverse cross-sectional shape of the rectangular container;
- and
- a second short-axis direction drive unit, which is arranged side by side with the first short-axis direction drive unit along the long-axis direction, and is configured to move the punch along the short-axis direction in the transverse cross-sectional shape of the rectangular container,
- the trimming method comprising:
- driving the long-axis direction drive unit and moving the punch along the long-axis direction to trim one short side of a rectangular container along the trim line in cooperation with the die;
- driving one of the first short-axis direction drive unit and the second short-axis direction drive unit, which is on a side closer to the one short side, and moving the punch in the short-axis direction from a state of the punch that has ended the trimming, to incline the punch and to trim a side of one long side on the one short side of the rectangular container that is connected to the one short side along the trim line, in cooperation with the die;
- driving one of the first short-axis direction drive unit and the second short-axis direction drive unit, which is on a side farther from the one short side, and moving the punch in the short-axis direction from a state of the punch that has ended the trimming, to return the punch from the inclined state to a state of being parallel to the long-axis direction, and trim an uncut portion of the one long side along the trim line in cooperation with the die;
- reversely driving the long-axis direction drive unit and moving the punch in the long-axis direction from a state of the punch that has ended the trimming, to trim the other short side of the rectangular container along the trim line in cooperation with the die;
- driving the first short-axis direction drive unit and the second short-axis direction drive unit and move the punch in parallel toward the other long side of the rectangular container from a state of the punch that has ended the trimming, to trim an uncut portion of the other short side along the trim line in cooperation with the die;
- driving one of the first short-axis direction drive unit and the second short-axis direction drive unit, which is on a side closer to the other short side, and moving the punch in the short-axis direction from a state of the punch that has ended the trimming, to incline the punch and trim a side of the other long side on the other short side along the trim line in cooperation with the die;
- driving one of the first short-axis direction drive unit and the second short-axis direction drive unit, which is on a side farther from the other short side, and moving the punch in the short-axis direction from a state of the punch that has ended the trimming, to return the punch from the inclined state to a state of being parallel to the long-axis direction, and trim an uncut portion of the other long side along the trim line in cooperation with the die;
- and
- driving the long-axis direction drive unit and moving the punch in the long-axis direction from a state of the punch that has ended the trimming, to trim an uncut portion of the one short side along the trim line in cooperation with the die.