METHOD OF MANUFACTURING A CONTAINER

Abstract

A method of manufacturing a container includes removing a section of the base web of the outer container so that a section of the base seam of the inner container is exposed to the exterior; raising the exposed section of the base seam into the outer container so that an opening is produced between the base seam of the inner bag and the outer container, introducing a pressure medium into the opening, whereby the inner bag detaches from the outer container on both sides, and supplying a pressure medium into the container opening so that the inner bag again engages the outer container.

Claims

1. A method of manufacturing a container having of a substantially stiff outer container and a readily deformable inner bag of thermoplastic plastic materials which do not form a weld connection with one another, with a container opening and at least one wall opening in the outer container, through which a pressure balance occurs in the gap between the inner bag and the outer container, wherein a preform having at least two tubes is coextruded and is arranged between the open halves of a blow mould and the blow mould is closed, when the preform has the length necessary for the manufacture of the container, wherein excess material is squeezed out in the base region of the container to be manufactured and a weld seam is formed, which has a base web of welded material of the outer container, in which the welded base seam of the inner bag is clamped and is held in the axial direction and the preform is inflated by a pressure medium into engagement with the wall of the blow mould and is removed from the blow mould, the method comprising the following steps: a) removing a section of the base web of the outer container so that a section of the base seam of the inner container is exposed to the exterior; b) raising the exposed section of the base seam into the outer container so that an opening is produced between the base seam of the inner bag and the outer container, c) introducing a pressure medium into the opening, whereby the inner bag detaches from the outer container on both sides, d) supplying a pressure medium into the container opening so that the inner bag again engages the outer container.

2. A method as claimed in claim 1, wherein the section of the base web is cut away.

3. A method as claimed in claim 2, wherein a circular cutter is used for the cutting away of the section of the base web.

4. A method as claimed in claim 1, wherein a central section of the base web is removed or cut away.

5. A method as claimed in claim 1, wherein compressed air is used as the pressure medium.

6. A method as claimed in claim 1, wherein the exposed section of the base seam is raised by a tool.

7. A method as claimed in claim 6, wherein a blow mandrel is used as the tool, through which the pressure medium is blown into the opening.

8. An apparatus for manufacturing a container having of a substantially stiff outer container and a readily deformable inner bag of thermoplastic plastic materials which do not form a weld connection with one another, with a container opening and at least one wall opening in the outer container, through which a pressure balance occurs in the gap between the inner bag and the outer container, wherein a preform having at least two tubes is coextruded and is arranged between the open halves of a blow mould and the blow mould is closed, when the preform has the length necessary for the manufacture of the container, wherein excess material is squeezed out in the base region of the container to be manufactured and a weld seam is formed, which has a base web of welded material of the outer container, in which the welded base seam of the inner bag is clamped and is held in the axial direction and the preform is inflated by a pressure medium into engagement with the wall of the blow mould and is removed from the blow mould, the apparatus for manufacturing comprising: a) a mounting device, in which a container to be processed may be fixed, b) a cutting device with a circular cutter, which is arranged to be advanceable, and c) a detaching device, with a blow mandrel, which is mounted to be advanceable and which is connected to a source of compressed air.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a vertical sectional view through the center of a container;

[0026] FIG. 2 is a sectional view of the container with a base web cut away; and

[0027] FIG. 3 is a vertical sectional view of an exposed section of a base seam that is raised by a mandrel.

DETAILED DESCRIPTION OF THE INVENTION

[0028] FIG. 1 is a central, vertical sectional view through a container, which includes a stiff outer container 1 and an engaging inner bag 2. The vertical section extends in the longitudinal direction centrally through the base weld seam 3, in which the welded base seam 4 of the inner container 2 is clamped in the base web 5 of welded material of the outer container 1.

[0029] In FIG. 2, a section 6 of the base web 5 is cut away with a circular cutter, which is not shown, so that a section 7 of the base seam 4 of the inner bag 2 is exposed to the exterior.

[0030] FIG. 3 shows that the exposed section 7 of the base seam 4 is raised into the container by a mandrel 8, whereby an opening is produced between the base seam 4 of the inner bag 2 and the outer container 1, into which compressed air is introduced, whereby the inner bag 2 detaches from the inner wall of the outer container 1 on both sides of the weld seam 3.

[0031] An apparatus in accordance with the invention for performing the method includes a mounting device for the container to be processed, a cutting device with a circular cutter, which removes a section of the weld seam of the container fixed in position in the mounting device in a single cut and a detaching device, which includes a detaching pin, which is connected to a source of compressed air and is advanced and thereby forces the weld seam into the container.