Bag making method and bag making apparatus

An apparatus for making plastic bags, the apparatus comprising:

• a panel web feed device configured to superpose a first panel web and a second panel web on each other and to feed the first and second panel webs in a longitudinal direction of the first and second panel webs;
• a side gusset supply device configured to, before superposing of the first and second panel webs, supply a side gusset to the first or second panel web so as to dispose the side gusset in a width direction of the first and second panel webs such that the side gusset is interposed between the first and second panel webs when the first and second panel webs are superposed on each other, the side gusset being folded in halves on opposite sides with respect to a longitudinal centerline thereof;
• a temporary seal device configured to, after the superposing of the first and second panel webs, seal the side gusset to the first and second panel webs so as to form temporary sealed sections;
• a first guide device configured to guide the first panel web as the first and second panel webs are fed, so as to divide the first panel web along a first line of weakness and so as to fold the first panel web on sides of division edges of the first panel web along fold lines, wherein the side gusset is cut open along a second line of weakness by means of the temporary sealed sections and guiding of the first panel web by the first guide device to form open surfaces, the first line of weakness being formed in the first panel web to extend in the longitudinal direction of the first and second panel webs, the fold lines extending in the longitudinal direction of the first and second panel webs, and the second line of weakness being formed in the side gusset to extend in a width direction of the side gusset and aligned with the first line of weakness;
• and
• an end face web supply device configured to supply an end face web to the first panel web as the first and second panel webs are fed, so as to dispose the end face web in the longitudinal direction of the first and second panel webs such that the end face web is superposed on folded parts of the first panel web and the open surfaces,
• the apparatus being configured to form panel parts of bags from the first and second panel webs, side gusset parts of the bags from the side gusset, and end face parts of the bags from the end face web,
• the apparatus further comprising a line-of-weakness forming device disposed downstream of a position where the panel web feed device superposes the first and second webs on each other, and configured to form the first line of weakness and the second line of weakness in the first panel web and the side gusset, respectively, the first line of weakness and the second line of weakness being perforations,
• the line-of-weakness forming device comprising a disk-shaped perforation cutter for forming the perforations, and is configured to allow adjustment of cutting depth of the disk-shaped perforation cutter into the first panel web and the side gusset.