Patent ID: 7731645

Claim:
A method for forming a container blank made of a material web, said container blank comprising a first elongate section with four layers of material, wherein a bottom section of said container blank is formed from said first elongate section, said bottom section including a bottom wall folded into a double-walled shape, and a second elongate section with two layers of material, wherein a body section of said container blank is formed from said second elongate section, at least one of said layers of material being included in both the first and the second elongate sections, the method comprising: providing a seal extending across a portion of the container blank having an extent that intersects a transition from the first elongate section to the second elongate section of the material web by connecting, in said portion, opposite surfaces of the layers of material of the material web to each other, said transition having an elongated length and the portion comprising less than the entire elongated length of the transition, said connecting including: arranging said portion of the material web between an abutment and a sealing tool, whereby at least one of the abutment or the sealing tool comprises recesses, and whereby a surface of the abutment facing the sealing tool is non-complementary to a surface of the sealing tool facing the abutment, bringing together said abutment and said sealing tool for forming ridges and valleys by moving material in said portion into said recesses, and orienting said ridges and valleys in such a manner that said ridges and valleys have an extent intersecting said transition.