WO2023001877A1

WO2023001877A1 - Mould for moulding a container

Info

Publication number: WO2023001877A1
Application number: PCT/EP2022/070320
Authority: WO
Inventors: Michael Linke; Frank HAESANDONCKX; Hartwig Müller; Matthias Kruse; Dieter Klatt; Dirk Reimer
Original assignee: Khs Gmbh
Priority date: 2021-07-22
Filing date: 2022-07-20
Publication date: 2023-01-26
Also published as: DE102021119052A1

Abstract

The invention relates to a mould (12) for moulding a container (28), wherein the mould (12) has at least two mould halves (16, 18), in which an inserted preform (32) made of thermoplastic material can be expanded and which, in a moulding position, have an inner contour (25) for the purpose of moulding an outer contour (29) of a container (28), wherein, in a separation position of the mould halves (16, 18), the inner contour (25) is interrupted along at least one parting plane (34), wherein, in a direction perpendicular to the parting plane (34), an outer-contour diameter (26) of a mould drawing for the container (28) to be moulded defines the outer contour (29), wherein, in the moulding position, the inner contour (25) has an inner-contour diameter (24) in a direction perpendicular to the parting plane (34), this inner-contour diameter being smaller than the outer-contour diameter (26) of the mould drawing for the container (28) to be moulded. The invention makes available a further-improved, cost-effective mould (12) which is of simple design.

Description

Forming tool for forming a container

The invention relates to a mold for molding a container.

For the production of containers from thermoplastic material, thermally conditioned preforms are placed in molds and stretched biaxially. The forms can be multi-part, e.g. B. from Formhälf th be formed. The stretching is carried out, among other things, by a fluid that is pressed into the preform at high pressure. This expands the parison and presses its walls against the inside of the mould. This means that the pressure of the fluid also acts on the mold halves. These can therefore be pushed apart when the preform is stretched.

In order to avoid that the mold halves are ge opens by the pressure of the fluid, it is z. B. from DE 102016006066 Al known to use a tumbler, with which the mold halves are held closed against the pressure of the fluid. When using gaseous fluids to expand the preforms, air cushions can be used to hold the mold halves closed, in which case the gaseous fluid is also used for the air cushions.

The object of the invention is to provide a further improved mold that is simpler in design and less expensive.

The object is solved by the features of the independent claims. Advantageous developments are the subject of the dependent claims and the following description.

In a molding tool for molding a container, the molding tool having at least two mold shells, in which an inserted preform made of thermoplastic material can be expanded and which, in one molding position, have an inner contour for molding an outer contour of a container, with the mold shells in a separating position the inner contour along at least one parting surface is interrupted, with an outer contour diameter of a drawing of the container to be formed defining the outer contour in a direction perpendicular to the parting surface, the invention provides that the inner contour in the mold position in a direction perpendicular to the parting surface has an inner contour diameter that is smaller than is the outer contour diameter of the mold drawing of the container to be molded.

According to the invention, an inner contour for forming the outer contour of a container is thus provided with the mold shells, in which the deformation of the inner contour by the expansion of the preform is taken into account. For this purpose, the molding tool has at least two mold shells which, in the molding position, provide the inner contour for molding the outer contour of a container. In the mold position, the mold shells rest against one another at a parting surface. The inner contour is interrupted along this parting surface when the shell molds are separated from one another. The inner contour has an inner contour diameter perpendicular to the parting surface. At the same position, an outline diameter of a mold drawing defines a diameter of the outline of the container to be molded. The outer contour diameter of the mold drawing is thereby larger than the diameter of the outer contour of the container to be formed, since the latter, particularly if it is made of plastic material, shrinks after it has been formed. The inner contour diameter is smaller than the outer contour diameter of the drawing of the container to be formed. When the parison is expanded by means of the fluid under molding pressure, the mold halves are separated from one another along the parting surface, with the distance between the mold shells resulting from the separation being added perpendicularly to the parting surface to the inner contour diameter. It is therefore not necessary to hold the mold shells in the mold position with a force that is greater than the force exerted by the mold pressure of the fluid. A dedicated tumbler is therefore not required, so that the mold has a simpler structure and is less expensive. It is conceivable that the shell molds can be pivoted and lined in order to reduce or avoid bearing play of the shell molds in the mold position.

It is conceivable that a difference between the inner contour diameter and the outer contour diameter of the mold drawing of the container to be molded can correspond, for example, to a distance perpendicular to the parting surface between the mold shells, while a preform with a fluid that is under a molding pressure in the mold is expanded.

The inner contour diameter can thus be selected in such a way that the addition of the distance resulting from the separation of the shell molds results in the outer contour diameter of the drawing of the container to be formed.

According to a further example, each shell mold perpendicular to the parting surface can have a contour with half the inner contour diameter.

The inner contour diameter, which is smaller than the outer contour diameter of the form drawing of the container to be formed, can be provided by first producing the mold shells of the mold tool with an initial inner contour diameter that corresponds to the outer contour diameter of the form drawing of the to for corresponding container. The initial inner contour diameter can then be reduced by removing the same amount of material from the parting surface on both shell molds. A mold can thus be provided in a simple manner which has an inner contour diameter which is smaller than the outer contour diameter of the mold drawing of the container to be molded.

It is also conceivable that the outer contour can be circular or oval, for example. In the molding position, the shell molds can then initially provide an oval cross-sectional shape for the container to be molded, with the inner contour diameter perpendicular to the parting surface being smaller than a diameter of the inner contour parallel to the parting surface. Due to the molding pressure during the expansion of the parison, the cross-sectional shape of the container to be molded becomes circular, since there is a distance between the mold halves perpendicular to the parting plane.

The invention further relates to a device for producing containers from preforms, which has at least one molding device with a large number of molding tools, wherein at least one of the large number of molding tools is designed according to the preceding description. The device can e.g. B. a feed unit for inserting thermally conditioned preforms into the mold shells of the molds arranged in the separation position and an expansion device for expanding thermally conditioned preforms, which are arranged in a mold arranged in the mold position.

Advantages and effects as well as further developments of the device result from the advantages and effects as well as further developments of the molding tool described above. In order to avoid repetition, reference is therefore made to the previous description in this regard.

The invention is described below using an exemplary embodiment with the accompanying drawing. Show it:

Figure 1 is a schematic representation of a device for

molding containers with a variety of molding tools;

Figure 2a, b is a schematic representation of a mold; and Figure 3a, b is a schematic cross-sectional view of a

molding tool.

FIG. 1 shows an apparatus for manufacturing a container made of thermoplastic material, which is referenced in its entirety by the reference numeral 10.

In this example, the device 10 has a shaping device 11 in the form of a wheel, on the circumference of which a plurality of shaping tools 12 are fastened. The forming device 11 can e.g. B. be a blow wheel that expands the preforms pneumatically, or work with a hydraulic fluid. Furthermore, the device 10 has a stretching rod 14 on each mold 12, with which thermally conditioned preforms can be stretched in a mold 12 along their longitudinal axis.

FIG. 2a shows a schematic representation of a mold 12. The mold 12 has two mold shells 16, 18 and a base element 22, which are shown in FIG. 2 in their open position. The shell mold 16 has one half 20 of an inner contour, with the shell mold 18 having a corresponding half 21 of the inner contour.

In this example, the mold shells 16, 18 are arranged such that they can be pivoted relative to one another. They can be pivoted from the open position shown in FIG. 2a into a form position shown in FIG. 2b. In the mold position, the two shell molds 16, 18 with the halves 20, 21 and the base element 22 provide a mold with an inner contour 25 for forming an outer contour of a container.

The shell molds 16, 18 touch at the parting surface 34. In the molding position, a thermally conditioned preform 32 is also inserted into the mold 12 and is biaxially expanded in the mold 12.

The mold shells 16, 18 can be lined and have a bearing clearance of 0 in the mold position. Figures 3a and 3b show a cross-sectional view of the mold shells 16, 18 of the mold 12 in the molding position, the cross section running approximately along the plane 27 of Figure 2b.

Also shown in FIG. 3a are the preform 32, which is arranged between the two shell molds 16, 18, the parting surface 34, at which the two shell molds 16, 18 touch, the inner contour 25, which is composed of the two halves 20, 21 , and a desired outer contour 29 of the container to be formed.

The inner contour 25 deviates from the outer contour 29. If the outer contour 29 has a circular cross-section, the inner contour 25 may have an oval cross-section.

Perpendicular to the parting surface 34, the inner contour 25 has an inner contour diameter 24 which is smaller than an outer contour diameter 26, a drawing of the shape of the container to be formed.

Upon expanding the parison 32 with a fluid under molding pressure, a container 28 is formed as shown in Figure 3b. The walls of the container 28 are pressed against the inner contour 25 . The mold shells 16, 18 are pushed away from each other perpendicularly to the parting surface 34 by the molding pressure of the container 28.

The drawing of the shape of the container to be formed indicates the contour of the container when it is formed in the mould, i. i.e. when the walls of the container are pressed against the inner walls of the mold shells 16, 18 by a fluid. In particular, when the container is made of a plastic material, the outer contour diameter of the final container is smaller than the outer contour diameter of the mold drawing because of the shrinkage of the material.

During this phase, the mold shells 16, 18 are in a separating position in which they are separated from one another perpendicularly to the separating surface 34. stands are arranged. The mold shells 16, 18 then have a distance 30 from each other.

The sum of the distance 30 and the inner contour diameter 24 corresponds to the outer contour diameter 26. The distance 30 thus corresponds to a difference between the inner contour diameter 24 and the outer contour diameter 26 perpendicular to the parting surface 34 before the preform 32 expands in the mold 12 will.

The inner contour diameter 24 can be divided equally between the halves 20, 21. Alternatively, one half 20 , 21 can contribute half the outer contour diameter 26 to the inner contour diameter 24 . The other half 20, 21 then contributes half the outer contour diameter 26 minus the distance 30 to the inner contour diameter 24. All gradations between the two alternatives can also be formed.

The distance 30 can, for. B. between 0.05 mm and 1 mm, preferably between 0.2 mm and 0.7 mm, more preferably 0.4 mm to 0.5 mm wear be.

If the outer contour diameter 26 perpendicular to the parting surface 34 z. B. should be 100 mm and the distance is 300.4 mm, the inner contour diameter 24 perpendicular to the parting surface 34 z. B. be 99.6 mm.

For this purpose, the shell molds 16 , 18 can initially be designed in such a way that they provide an initial inner contour which has the outer contour diameter 26 perpendicular to the parting surface 34 . At the parting surface 34 can then at each mold shell 16, 18 z. B. 0.2 mm of material can be removed, so that the inner contour diameter is reduced to 99.6 mm. Alternatively, 0.4 mm of material can be removed from a mold shell 16, 18, or any desired distribution between the two alternatives can be selected. The example described above is in no way intended to limit the invention. Rather, the invention can be modified in many different ways. All of the features of the inventions described above can be essential to the invention alone or in combination with one another.

Reference List

10 device for manufacturing containers

11 forming device

12 forming tool 14 horizontal bar

16 shell mold 18 shell mold 20 half 21 half 22 base element

24 inner contour diameter

25 inner contour

26 outer contour diameter 27 cutting plane 28 container

29 outer contour

30 clearance 32 preform

34 interface

Claims

Expectations

1. Mold for molding a container (28), wherein the mold (12) has at least two mold shells (16, 18), in which an inserted preform (32) made of thermoplastic material is expandable and in a mold position an inner contour ( 25) for forming an outer contour (29) of a container (28), wherein the inner contour (25) is interrupted along at least one parting surface (34) when the mold shells (16, 18) are in a separating position, wherein in a direction perpendicular to the parting surface (34) an outer contour diameter (26) of a mold drawing of the container (28) to be molded defines the outer contour (29), characterized in that the inner contour (25) in the mold position has an inner contour in a direction perpendicular to the parting surface (34). - Has a diameter (24) which is smaller than the outer contour diameter (26) of the mold drawing of the container (28) to be moulded.

2. Mold according to claim 1, characterized in that a difference between the inner contour diameter (24) and the outer contour diameter (26) is a distance (30) perpendicular to the parting surface (34) between the mold shells (16, 18 ) while a preform (32) is being expanded in the mold (12) with a fluid that is under a molding pressure.

3. Mold according to claim 1 or 2, characterized in that each mold shell (16, 18) has a contour perpendicular to the parting surface (34) with half the inner contour diameter (24).

4. Mold according to one of claims 1 to 3, characterized in that the outer contour (29) is circular or oval.

5. Device for producing containers from preforms (32), the at least one molding device (11) with a plurality of Molds (12), wherein at least one of the plurality of molds (12) is formed according to any one of claims 1 to 4.