Plastic bag making apparatus

An apparatus for successively making plastic bags each of which includes panel portions, side gusset portions and a bottom gusset portion, each of the side gusset portions having opposite end portions at one of which an auxiliary gusset portion is formed, the bottom gusset portion being combined with the auxiliary gusset portion, the apparatus comprising:

• panel material feeding means by which webs of panel material are superposed on each other and fed longitudinally thereof and intermittently, the panel portions being formed by the webs of panel material;
• side gusset material supply means by which a sheet of side gusset material is folded into halves, superposed into two layers and then supplied to and interposed between the webs of panel material to extend widthwise thereof whenever the webs of panel material are fed intermittently, the sheet of side gusset material having opposite end portions, the side gusset portion being formed by the sheet of side gusset material;
• temporarily fixing means by which one of the webs of panel material is temporarily fixed to one of the layers of side gusset material while the other web of panel material is temporarily fixed to the other layer of side gusset material at one of the end portions of side gusset material after the sheet of side gusset material is interposed;
• panel material guide means by which one of the webs of panel material is guided to be folded along a longitudinal folded line at one of the end portions of side gusset material when being fed to make the webs of panel material open and make an open surface formed on the webs of panel material, one of the layers of side gusset material being pulled by one of the webs of panel material to be folded along the longitudinal folded line to make the layers of side gusset material open along with the auxiliary gusset portion and make an open surface formed on the layers of the auxilary gusset portion;
• bottom gusset portion forming means by which a web of bottom gusset material is superposed on the open surfaces of panel material and the auxiliary gusset portion to extend longitudinally of the webs of panel material, the bottom gusset portion being formed by the web of bottom gusset material;
• cross seal means by which the web of bottom gusset material and the auxiliary gusset portion are heat sealed with each other while the webs of panel material and the sheet of side gusset material are heat sealed with each other widthwise of the webs of panel material whenever the webs of panel material are fed intermittently and with the open surfaces kept being formed;
• and
• longitudinal seal means by which the web of bottom gusset material and at least one of the webs of panel material are heat sealed with each other longitudinally of the webs of panel material whenever the webs of panel material are fed intermittently and with the open surfaces kept being formed,
• wherein one of the webs of panel material has opposite side edges, the other web of panel material having opposite side edges one of which protrudes beyond the corresponding side edge of one of the webs of panel material at a distance widthwise of the webs of panel material when the webs of panel material are superposed on each other, the bottom gusset portion forming means comprising additional guide means by which the other web of panel material is guided to be folded along a longitudinal folded line when being fed to make a folded portion formed in the other web of panel material and superposed on the open surfaces of panel material and the auxiliary gusset portion, the web of bottom gusset material comprising the folded portion.