Bag making apparatus and bag making method

A bag making apparatus for cross-cutting at least two continuous sheet panels in a width direction of the sheet panels to successively make bags from the sheet panels, at least one of the sheet panels comprising marks repeatedly printed thereon, the bag making apparatus comprising:

• an intermittent feed device configured to feed the sheet panels in a longitudinal direction of the sheet panels in a state in which the sheet panels are superposed on each other;
• at least one first processing device configured to process the sheet panels during every pause phase of an intermittent feed cycle;
• at least one second processing device configured to process the sheet panels during every pause phase of an intermittent feed cycle;
• and
• an adjustment device disposed downstream of the at least one first processing device and upstream of the at least one second processing device,
• the intermittent feed device comprising:
• a first sensor disposed upstream of the adjustment device to detect the marks;
• a first pair of drive rollers disposed upstream of the adjustment device to feed the sheet panels in the longitudinal direction of the sheet panels;
• a second sensor disposed downstream of the adjustment device to detect the marks;
• and
• a second pair of drive rollers disposed downstream of the adjustment device to feed the sheet panels in the longitudinal direction of the sheet panels, the intermittent feed device being configured to:
• control the first pair of drive rollers based on output of the first sensor to position the sheet panels with respect to the at least one first processing device when pausing the sheet panels;
• and
• control the second pair of drive rollers based on output of the second sensor to position the sheet panels with respect to the at least one second processing device when pausing the sheet panels,
• wherein the adjustment device is configured to detect an upper threshold and a lower threshold for a length of the sheet panels included in a section from the first pair of drive rollers to the second pair of drive rollers,
• wherein the bag making apparatus further comprises a movement device for moving the at least one first processing device and the first sensor together as a movable group in the longitudinal direction of the sheet panels,
• wherein the movement device is configured to move the movable group upstream in response to the adjustment device detecting the upper threshold and to move the movable group downstream in response to the adjustment device detecting the lower threshold, and
• wherein the intermittent feed device is further configured to, if the movable group is moved, determine an intermittent feed distance based on a moving distance of the movable group in addition to the output from the first sensor to feed the sheet panels by the determined intermittent feed distance using the first pair of drive rollers.