Rectangular plastic container

Abstract

The invention relates to a rectangular plastic container 1,2 for the storage, transport and mixing of liquids or liquid-solid mixtures, with a base (1) and four container walls (2) arranged vertically and at right angles to each other, stiffened by reinforcing elements.In order to further develop such a plastic container (1,2) in such a way that the manufacturing costs are significantly reduced while maintaining at least the same stability, and thus also save energy costs for mixing the contents of the container when it is used as a mixing vessel, the invention proposes that the reinforcing elements be designed as one or more stiffening ribs (3) extending helically around the circumference of the plastic container (1,2) and rising from bottom to top, which project inwards into the interior of the plastic container (1,2) and are formed by inwards projecting wall sections of the container walls (2).

Description

[0001] The invention relates to a rectangular plastic container for storing, transporting and mixing liquids or liquid-solid mixtures, comprising a base and four container walls arranged vertically and at right angles to each other, stiffened by reinforcing elements.

[0002] Plastic containers of this type typically have a capacity of 500 to 1500 liters and are primarily used in commercial settings for storing and transporting liquids or liquid-solid mixtures. Furthermore, these containers often also serve as mixing vessels for the liquids or liquid-solid mixtures they contain. In all these applications, it is essential that the plastic containers can be easily cleaned after each use to remove any residue from the contents.

[0003] The rectangular shape (cubic or cuboid) of plastic containers has the advantage over cylindrical containers of requiring less space during transport and / or storage, but has the disadvantage that the container walls deform uncontrollably outwards under the pressure of the container contents and form large bulges.

[0004] To avoid these undesirable deformations, it is common and known in the art to stiffen the walls of such rectangular plastic containers by means of horizontal and / or vertical reinforcing elements that are attached to the outside of the container walls, e.g., in the form of a metal mesh cage (see DE10 2004 039 482 B4) or in the form of horizontal plastic bands applied to the outside of the container walls (see DE 32 48 068 C2). However, such stiffening measures involve considerable material and labor costs and are therefore expensive. Such external reinforcing elements are particularly problematic when used on containers containing aggressive substances that attack the material of the external reinforcing elements, for example, through corrosion. In this case, additional costly corrosion protection measures are usually necessary.

[0005] It is therefore an object of the invention to further develop the rectangular plastic container of the type mentioned above, without the need for additional reinforcing materials, in such a way that the manufacturing costs are significantly reduced while maintaining at least the same stability.

[0006] To solve this problem, the invention proposes, starting from a rectangular plastic container of the type mentioned at the outset, that the reinforcing elements are designed as one or more stiffening ribs extending helically around the circumference of the plastic container and rising from bottom to top, projecting inwards into the interior of the plastic container and formed by inwards projecting wall sections of the container walls.

[0007] The rectangular plastic container according to the invention is characterized, firstly, by the fact that the stiffening ribs used for wall reinforcement, which consist of appropriately shaped wall sections, require neither additional material nor additional labor for their manufacture. Because the stiffening ribs run continuously in a helical pattern from bottom to top around the entire circumference and over the entire height of the rectangular plastic container, increased stability of the plastic container is achieved with minimal material expenditure, not only against horizontally acting forces but also against vertically directed forces.

[0008] This increased stability was demonstrated using FEM calculations.

[0009] Additional advantages arise when the rectangular plastic container is used as a mixing vessel for the liquids or liquid-solid mixtures it contains. This is because, during all stirring movements around a vertical axis, the helically extending stiffening ribs projecting into the interior of the plastic container impart an additional vertical component to the mixture, resulting in faster and more intensive mixing. Furthermore, this significantly reduces the energy required for the mixing tools (circulating pumps or agitators).

[0010] A simple way to increase the stability of the plastic container according to the invention is to thicken the container walls in the area of ​​the stiffening ribs.

[0011] It is particularly advantageous if the stiffening elements in the forming wall sections of the container walls are curved towards the interior of the plastic container. These curves have the advantage that, on the one hand, the stresses occurring in the material under load are better distributed, and on the other hand, the inner walls of the plastic container can be cleaned more easily because there are no sharp angles or dead spaces in the area of ​​the stiffening ribs. Additionally, the rounded stiffening elements ensure a particularly gentle stirring action. This gentle stirring action is necessary, for example, when mixing fibers or flakes into a liquid, because these could get caught on sharp edges and / or be damaged.

[0012] A particularly preferred embodiment of the plastic container according to the invention provides that the wall sections forming the stiffening ribs project into the interior of the plastic container by 1.2 to 1.5 times their wall thickness, and that the radius of curvature of these wall sections corresponds to 1.6 to 1.9 times their wall thickness. The best results with regard to stability and mixing have been achieved with these dimensional ratios.

[0013] A further advantageous embodiment of the rectangular plastic container according to the invention provides a circulation device arranged at the upper edge of the plastic container and extending into the interior of the plastic container, which sets the contents of the plastic container into a circular motion rotating around a vertical axis. This makes the circulation device mentioned above, which can be designed as a stirring device or as a circulation pump, a virtually integral part of the rectangular plastic container.

[0014] A cover, which can be fixed to the upper edge of the container walls and is equipped with mounting interfaces for the circulation device and / or for other auxiliary equipment, is suitable for attaching the circulation device. This other auxiliary equipment could be, for example, cleaning tools or the like.

[0015] Furthermore, it is advantageous to have at least one closable opening in the lower part of the container wall, directly above the bottom, which can serve as a connection opening for a circulation pump and / or as an outlet opening. This closable opening directly above the bottom has the advantage that a particularly simple, non-self-priming pump can be used as a circulation device to mix the contents of the container; this pump is connected to this opening.

[0016] An embodiment of the invention is explained below with reference to the accompanying drawing. The drawing shows: Fig. 1: Schematic transparent view of a rectangular plastic container according to the invention; Fig. 2: a section through the stiffening rib of the container walls; Fig. 3: Schematic perspective view of a rectangular plastic container according to the invention with a lid having mounting interfaces for a circulation device and auxiliary equipment.

[0017] In the embodiment shown in the drawing, the base of the rectangular plastic container is designated by reference numeral 1. This base 1 consists of a rectangular plate resting horizontally on a support surface, which is connected at its four edges to four vertically extending side walls 2, which together with the base form the cuboid body of the container.

[0018] The base 1 and the side walls 2 are joined together in one piece, are made of a suitable plastic (e.g., polyethylene with sufficient UV and chemical resistance), and have a wall thickness that meets the requirements. All angles between the base and the side walls, as well as between the side walls themselves, are rounded to prevent any narrow passages or dead spaces that would be difficult to clean.

[0019] To prevent the container walls 2 from bulging outwards due to the pressure of the liquids or liquid-solid mixtures contained in the container, the side walls 2 are provided with a stiffening rib 3 extending helically around the circumference of the plastic container 1,2 and rising from bottom to top, which projects inwards into the interior of the plastic container 1,2 and is bordered by inwards curved wall sections 2a (see figure). Fig. 3) of the container walls 2 are formed.

[0020] As further from Fig. As can be seen from Figure 2, the container walls 2 are slightly thickened in the area of ​​the stiffening rib 3. This thickening results in a wall thickness in the area of ​​the stiffening rib 3 that is 1.2 to 1.5 times the wall thickness of the container walls 2. Furthermore, the radius of curvature R of the bulge is approximately 1.6 to 1.9 times the wall thickness of the container walls 2. These thickenings and the radius of curvature ensure improved stability and better cleaning of the interior of the container.

[0021] As further from Fig. As shown in Figure 1, the rectangular plastic container 1,2 depicted therein is covered at the top by a lid 4. This lid 4 has a closable filling opening 5 and also an access opening 6 for a circulation device that engages in the interior of the plastic container. This circulation device imparts a circular motion to the contents of the plastic container 1,2 when it is used as a mixing container, rotating it around a vertical axis. This circulation device can, for example, be designed as an agitator or a circulation pump.

[0022] Between this circulation device on the one hand and the helically extending stiffening rib 3 projecting into the interior of the plastic container 1, 2 on the other hand, an advantageous synergistic effect occurs when the plastic container 1, 2 is used as a mixing container, because the helically extending stiffening rib 3 imposes a vertical movement component on the mixture, leading to faster and more intensive mixing. Long-term tests with such circulation devices in rectangular plastic containers 1, 2 according to the invention have shown that energy savings of more than 20% can be achieved during mixing through the interaction of the circularly operating circulation device on the one hand and the helical stiffening ribs 3 on the other.

[0023] In the exemplary embodiment according to Fig.3 is the lid 4 of the plastic container 1,2 additionally provided with mounting interfaces 7 and 8 for the circulation device and other auxiliary equipment.

[0024] Additionally, a closable opening 9 is provided in the lower area of ​​a container wall 2 directly above the bottom 2, which can be used as a connection for a non-self-priming pump as a circulation device or as a simple drain opening. Reference symbol list 1 Underbody 2 Container wall, 2a Wall section 3 stiffening rib 4 lids 5 Filling opening 6 access opening 7 Mounting interface 8 Mounting interface 9 lockable openings QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2004 039 482 B4

[0004] DE 32 48 068 C2

[0004]

Claims

[1] Rectangular plastic container (1, 2) for the storage, transport and mixing of liquids or liquid-solid mixtures, with a bottom (1) and four container walls (2) arranged vertically and at right angles to one another, stiffened by reinforcing elements, characterized in that the reinforcing elements are designed as one or more stiffening ribs (3) running helically around the circumference of the plastic container (1, 2), rising from bottom to top, which are formed by wall sections of the container walls (2) projecting inwards into the interior of the plastic container (1, 2). [2] Plastic container (1,2) according to claim 1, characterized by that the container walls (2) are thickened in the area of ​​the stiffening ribs (3). [3] Plastic container (1,2) according to claims 1 or 2, characterized bythat the wall sections (2a) of the container walls forming the stiffening ribs (3) are curved in the direction of the interior of the plastic container (1,2). [4] Plastic container (1,2) according to claim 3, characterized by that the wall sections (2a) forming the stiffening ribs (3) protrude into the interior of the plastic container (1,2) by 1.2 to 1.5 times their wall thickness and that the radius of curvature (R) of the curvature of these wall sections corresponds to 1.6 to 1.9 times their wall thickness. [5] Plastic container (1,2) according to one or more of claims 1-4, characterized by a circulating device arranged at the upper edge of the plastic container (1,2) and engaging in the interior of the plastic container, which sets the contents of the plastic container (1,2) in motion in a circular movement rotating about a vertical axis. [6] Plastic container (1,2) according to claim 5, characterized bythat the circulation device is designed as a stirring device. [7] Plastic container (1,2) according to claim 5, characterized by that the circulation device is designed as a circulation pump. [8] Plastic container (1,2) according to one of claims 5-7, characterized by a cover (4) which can be fixed to the upper edge of the container walls and which is provided with mounting interfaces (7, 8) for the circulation device and / or for other auxiliary devices. [9] Plastic container (1,2) according to one or more of claims 1-4, characterized by that in at least one container wall (2) in the lower region above the base (1) there is arranged at least one closable opening (9), which serves as a connection opening for a circulation pump and / or as an outlet opening.

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