Abstract

A method for flat pressing and sticking down of a fillet seam of a roof-shaped folding closure of a package whose outside surface is provided with a thermoplastic material, comprising transporting the package in a direction transverse to the fillet seam, heating a first area of the side surface of the fillet seam rearward of the seam relative to the direction of transport and heating a second area of the outside surface of the package complementary with the first area, and transporting the heated package past a stationary member positioned so as to press the fillet seam and cause it to stick down to the outside surface of the package. A third and fourth area respectively on the side surface and on the package and respectively spaced from the first and second areas can also be heated to form two spaced stuck down areas. By pulling upward therebetween, the seam can be raised for opening the package. A corresponding apparatus is provided and the stationary member may have a leading inclined portion so as to effect the pressing down progressively. Means may also be provided to cool the stationary member and set the sticking down.