Method for connecting two ends of flat tubular film sheets equipped with side creases

A method for connecting the ends of flat tubular film sheets made of thermoplastic plastic that are equipped with side creases with one another by means of a lateral welding seam in such a manner that the interior creases remain permeable from the exterior even in the connection area. The end of one sheet is equipped with cuts separating the interior edges of the side creases. The end of the other sheet is inserted or placed into the separated area in such a way that both walls of the cut sheet overlie the inserted end, with a layer of each side crease of the end area of the inserted tubular film between the walls. Separating layers are inserted or placed into the side creases of the inserted end area, and the ends of the two sheets are then connected with one another by means of a lateral welding seam.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for connecting two ends of flat tubular film sheets equipped with side creases made of thermoplastic plastic, preferably for connecting the end of a side crease tubular film sheet to the beginning of a new side crease tubular film roll.

2. Description of the Related Art

Sacks are usually produced from continuous and intermittently pre-drawn or conveyed flat side crease tubular film sheets made of thermoplastic plastic. In order not to have to interrupt the continuous production after the side crease tubular film sheet has run out by inserting a new side crease tubular film sheet, it is necessary to connect the end of the side crease tubular film sheet roll that has run out to the beginning of a new side crease tubular film sheet roll in a way that the continuous conveying and production of the sacks is not interrupted. This requires a connection of the ends of the side crease tubular film sheet in such a way that the side creases remain permeable at the connection site, i.e., that the layers of the side creases that are arranged on top of each other are not glued or welded together. This type of permeability of the side creases in the connection area cannot be achieved, for example, if the ends to be connected to one another are arranged on top of each other, and connected by means of a lateral welding seam, which then includes all layers that are welded together.

SUMMARY OF THE INVENTION

It is therefore the task of the invention to recommend a method of the previously mentioned type that enables the welding of the ends of a side crease tubular film sheet in such a way that the layers of the side creases that are arranged on top of each other are not welded together.

According to the invention, this task is solved in a method of the previously mentioned type in that an end is equipped with cuts separating the interior edges of the side creases, and the other end is inserted or placed into the separated area in such a way that both walls each include the other end between a layer of each side crease of the end area of the tubular film, and that separating layers are inserted or placed into the side creases of the included other end area, and the ends are then connected to one another by means of a lateral welding seam.

The method according to the invention enables the connecting of the ends of two side crease tubular film sheets in a way that the walls of the included side creases that are placed on top of each other do not weld together so that the side creases remain permeable from the exterior sides, and a connection of the ends is possible in a way that does not interrupt the continuous production process of, for example, sacks, or carrying bags. A sack containing a connection area can easily be discarded as scrap.

Purposefully, the interior edges of the beginning of a new tubular film sheet are separated, because the resulting connection better integrates with the production process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows the beginning of a side crease tubular film sheet1that is to be connected to the end of a side crease tubular film sheet that is running out by means of a lateral cutting edge. The interior edges of the side creases2are cut open in the end area so that the upper side3of the side crease tubular film sheet1can be lifted with the upper layers4of the side creases2from the lower layer5with the side crease layers6up to a line7, which is defined by the interior ends of the separating cuts separating the side creases.

After opening the end area of the tubular film sheet1by means of lifting the upper and lower sides3,5of the layers4,6of the side creases2that are separated from each other by means of the separating cut up to the lateral line7, the end8to be connected to the second side crease tubular film sheet is inserted into the opened area in a manner illustrated inFIG. 3. Separating layers, such as separating plates9are then inserted from the sides into the beginning area of the side creases of the beginning8of the tubular film sheet to be connected in a manner illustrated inFIG. 2. The opened layers of the sheet to be connected are then congruently placed onto the end of the sheet running out, and the end areas of the sheets to be connected that are inserted in the area of the separating layer9are then connected to each other by means of a lateral welding seam10. The areas between the interior edges11of the side creases of the upper and lower walls of the side crease tubular film sheet ends to be connected are welded together by means of the lateral welding seam10. However, the layers of the inserted ends of the side crease tubular film sheets that are arranged on top of each other do not weld together due to the separating layer9inserted in the connection area so that the interior side crease area remains permeable even in the connection area. Due to the lateral welding seam, however, the layers of the side creases each abutting the exterior and interior sides are welded to these layers, and the end areas cut free from the side creases by means of separating cuts are welded to those of the exterior sides of the inserted ends of the side crease tubular film sheets included by them.