Bag making apparatus and method for making plastic bag

A bag making apparatus comprising:

• a sheet panel feed device configured to superpose a first sheet panel and a second sheet panel on each other and to intermittently feed the first and second sheet panels in a longitudinal direction of the first and second sheet panels;
• a side gusset supply device configured to supply a side gusset to the first or second sheet panel to dispose the side gusset in a width direction of the first and second sheet panels during every intermittent feed cycle of the first and second sheet panels before superposing of the first and second sheet panels such that the side gusset is interposed between the first and second sheet panels when the first and second sheet panels are superposed on each other;
• a sheet panel guide device configured to guide the first and second sheet panels as the first and second sheet panels are fed, such that the first sheet panel is folded along a first fold line on a side of a side edge thereof to form a first folded part therein, such that the second sheet panel is folded along a second fold line on a side of a corresponding side edge thereof to form a second folded part therein, such that the first folded part is superposed on the second folded part, and such that the first and second folded parts are folded back along the second fold line to form a folded-back part in the first sheet panel;
• and
• a corner cut device configured to cut the second sheet panel and the folded-back part to form corner cut parts during every intermittent feed cycle of the first and second sheet panels after folding back of the first and second folded parts, the corner cut device being further configured to prevent cutting a base part of the first sheet panel and the first folded part when cutting the second sheet panel and the folded-back part,
• wherein the corner cut device comprises:
• a cutter which reciprocates in a vertical direction;
• a baffle plate opposed to the cutter in the vertical direction and located between the first folded part and the folded-back part to receive the cutter when the second sheet panel and the folded-back part are cut with the cutter;
• and
• a pair of plate springs opposed to each other in the vertical direction and extending in a horizontal direction,
• wherein the pair of the plate springs is attached at one end thereof to a fixing block with the fixing block sandwiched therebetween, and attached at the opposite end thereof to an attachment block with the attachment block sandwiched therebetween, and
• wherein the baffle plate is attached to the attachment block to be movable in the vertical direction with a flat surface thereof kept horizontal.