CONTAINER MADE FROM THERMOPLASTIC POLYMER AND METHOD FOR PRODUCING SAID CONTAINER

Abstract

The invention relates to a container made from thermoplastic polymer with at least one inner reinforcing rib in a container wall, wherein the reinforcing rib is formed by at least one linear groove track in a container outer wall, the groove track extends over a length on the container outer wall, the groove track is formed by a multiplicity of depressions in the container outer wall, said depressions being arranged at a distance from one another, and wherein material bridges are provided between each of the depressions, said material bridges each having a smaller depth than the depressions. The invention furthermore relates to a method for producing such a container by extrusion blow molding or thermoforming.

Claims

1-11. (canceled)

12. A container made from thermoplastic polymer with at least one inner reinforcing rib in a container wall, wherein the reinforcing rib is formed by at least one linear groove track in a container outer wall, the groove track extends over a length on the container outer wall, the groove track is formed by a multiplicity of depressions in the container outer wall, said depressions being arranged at a distance from one another, and wherein material bridges are provided between each of the depressions, said material bridges each having a smaller depth than the depressions, wherein the polymer of the container wall is accumulated in the region of the material bridges, and therefore the wall thickness of the container wall is greater in the region of the material bridges than in the region of the depressions.

13. The container as claimed in claim 12, wherein the wall thickness of the container wall is greater in the region of the material bridges than the wall thickness of the container wall outside the groove track.

14. The container as claimed in claim 12, wherein the depressions have a length and a width, and wherein the length is approximately one times to six times, preferably three times the width of the depressions.

15. The container as claimed in claim 14, wherein the material bridges have a length which is 0.3 times to 0.5 times the length of the depressions.

16. The container as claimed in claim 12, wherein the depressions are arranged at regular identical distances from one another.

17. The container as claimed in claim 12, wherein the material bridges have a length which is smaller than or equal to twice the wall thickness of the container outside the groove track.

18. The container as claimed in claim 12, wherein a plurality of reinforcing ribs, preferably in a form of a plurality of rectilinearly extending groove tracks which preferably cross one another or intersect are provided in the container wall.

19. A method for producing a container with the features of claim 12, wherein the container is obtained by extrusion blow molding of at least one preform made from thermoplastic polymer or by thermoforming a semi-finished product made from thermoplastic polymer, wherein the method comprises providing the preform, introducing the plasticized preform into a tool and deforming and shaping the preform within the tool, wherein at least one reinforcing rib in the form of a linear groove track is produced during the shaping of the container within the tool by means of at least one tool insert or a tool slide designed as a rib-shaped strip which protrudes into a cavity of the tool, wherein the strip has a multiplicity of grooves and webs, and wherein the webs produce depressions in the container outer wall and plasticized polymer is accumulated in the grooves, wherein the grooves correspond to the length of the material bridges, and in that the length of the grooves is dimensioned in such a manner that the wall thickness of the shaped container is greater in the region of the material bridges than the wall thickness of the container in the region of the depressions, and is preferably greater than outside the groove track.

20. The method as claimed in claim 19, wherein the length of the grooves is between 0.5 times and 4 times the wall thickness of the preform.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The invention is explained below with reference to an exemplary embodiment which is illustrated in the drawings, in which:

[0038] FIG. 1 shows a perspective illustration of a container according to the invention, which is designed as a fuel tank;

[0039] FIG. 2 shows a schematic illustration of a part of an opened blow molding tool;

[0040] FIG. 3 shows a perspective illustration of a reinforcing rib in the interior of the container;

[0041] FIG. 4 shows a top view of the cavity of a blow molding tool;

[0042] FIG. 5 shows a side view of a tool insert for producing the reinforcing rib; and

[0043] FIG. 6 shows an end side view of the tool insert in the blow molding tool.

DETAILED DESCRIPTION

[0044] FIG. 1 shows a container (1) according to the invention, which is designed, for example, as a fuel tank for a motor vehicle. The container 1 is composed of thermoplastic polymer and has been produced by extrusion blow molding of a preferably multi-layered extrudate on the basis of polyethylene. The invention should basically be understood in such a manner that the container 1 can have also been produced as what is referred to as a monolayer container on the basis of a single-layered extrudate made from thermoplastic polymer. The container 1 comprises a container wall 2 which encloses a filling volume. In the exemplary embodiment illustrated in FIG. 1, the container 1 is designed as what is referred to as a saddle tank with two chambers which communicate with each other, but the invention should be understood in such a manner that the container 1 can have any configuration. The container 1 can have been shaped, for example, as a simple cuboidal or cube-shaped structure.

[0045] The container wall 2 of the container 1 can have relatively extensive wall regions which are provided with reinforcing ribs 3 protruding into the container volume.

[0046] In the example according to FIG. 1, the reinforcing ribs 3 are formed by substantially rectilinearly extending groove tracks 4 in the container outer wall 2a. The groove tracks 4 are in each case of linear and rectilinearly extending design, wherein in each case two groove tracks 4 cross each other approximately at a right angle.

[0047] The groove tracks 4 are formed by a multiplicity of depressions 5 in the container outer wall 2a, which depressions are arranged at a distance from one another, wherein material bridges 6 are provided between each of the depressions 5, said material bridges each having a smaller depth than the depressions 5.

[0048] The depressions 5 have been produced during the production of the container 1 by means of impressions in the container outer wall 2a.

[0049] FIG. 3 shows the design of a reinforcing rib 3 on a container inner wall 2b, at which each depression 5 in the container outer wall 2a produces a corresponding projection 7.

[0050] The method for the production of the container 1 according to the invention is explained below with reference to FIGS. 2 to 6.

[0051] FIG. 2 shows, purely schematically, an open blow mold half 8 of a blow molding tool (not illustrated completely) and a preform 9 which is made from thermoplastic polymer and is placed with respect to the blow mold half 8. The container 1 can have been produced, for example, by conventional extrusion blow molding of a preform 9 of tubular design, wherein the preform 9 can have been extruded suspended in single- or multi-layered form by means of an extrusion head arranged above the blow molding tool. The blow molding tool can comprise, for example, two blow molding halves 8 which can undertake an opening and closing movement on a clamping frame (not illustrated). The term blow molding half 8 comprises a customary mold clamping platen and a tool part 10 which is arranged on the mold clamping platen and has a cavity 11 which defines a part of the outer contour of the container 1 to be manufactured.

[0052] The cavities 11 of two blow molding halves 8 can form, for example, a closed mold cavity, wherein the contour of the mold cavity corresponds to the configuration of the complete container 1 to be manufactured.

[0053] As already mentioned at the beginning, the blow molding tool can comprise more than two tool parts 10, the production method can be configured, for example, as what is referred to as a twin sheet blow molding method in which strip-shaped preforms are deformed in a three-part blow molding tool

[0054] For example, a tool insert which is designed as a rib-shaped strip 12 is provided within the cavity 11 of the tool part 10. The strip 12 comprises a multiplicity of grooves 13 and webs 14, wherein the webs 14 produce the depressions 5 in the container outer wall 2a and the material bridges 6 are formed in the grooves 13.

[0055] The method first of all comprises providing or extruding the preform 9, placing the preform between the open blow molding halves 8 of the blow molding tool or extruding the preform 9 between the open blow molding halves 8 in the direction of gravity. The blow molding halves 8 are closed around the preform 9, the preform 9 is expanded within the mold cavity formed by the cavities 11 and, in the process, is deformed and shaped against the walls of the cavities 11. The preform 9 is placed here against the rib-shaped strip 12 designed as a tool insert and produces a reinforcing rib 3 of the type shown in FIG. 3. The rib-shaped strip 12 has a thickness and a length, wherein the strip 12 is interrupted along the length by the grooves 13, and the webs 14 arranged between the grooves 13 have a length which is dimensioned in such a manner that the preform 9, during the shaping within the blow molding tool or during the expansion thereof, for example by means of blowing air, does not completely enter the grooves 13 of the strip 12 and is connected together on both sides of a web 14, and therefore material bridges 6 in the form of thick points are formed in the container wall 2.

[0056] As can be gathered in particular from the overall view of FIGS. 5 and 6, which shows a strip 12 according to the invention, the thickness of the strip 12 is approximately only one quarter of the length of the grooves 13, and therefore the preform, as it flows around the strip 12 during its shaping, is connected together not only by two sides of a web 14, which sides lie opposite each other in the longitudinal direction of the strip 12, but also a connection of the preform in the direction of the thickness of the strip 12, i.e. transversely with respect thereto, is also obtained.

[0057] FIG. 4 illustrates a view into an open tool part 10 with a strip 12 arranged in the cavity 11 of the tool part 10.

[0058] The contour of the container 1 to be manufactured with the tool part 10 according to FIG. 4 does not correspond to the contour of the container 1 illustrated in FIG. 1.

LIST OF REFERENCE SIGNS

[0059] 1 container [0060] 2 container wall [0061] 2a container outer wall [0062] 2b container inner wall [0063] 3 reinforcing ribs [0064] 4 groove tracks [0065] 5 depressions [0066] 6 material bridges [0067] 7 projection [0068] 8 blow molding halves [0069] 9 preform [0070] 10 tool part [0071] 11 cavity [0072] 12 rib-shaped strip [0073] 13 grooves [0074] 14 webs