WO2015028059A1

WO2015028059A1 - Method for producing a hollow body, and hollow body

Info

Publication number: WO2015028059A1
Application number: PCT/EP2013/067865
Authority: WO
Inventors: Laurent Deloux; Emin GUENER; Gérard LEGOFF; Aude METAIREAU
Original assignee: Promens Hockenheim Gmbh
Priority date: 2013-08-29
Filing date: 2013-08-29
Publication date: 2015-03-05
Also published as: EP3038807A1

Abstract

The invention relates to a method for producing a hollow body (10) which comprises at least one insert element (34, 36, 38, 40). The method is characterized by the following steps: arranging the at least one insert element (34, 36, 38, 40) at a specified point in the interior of a hollow body mold of a rotational molding system; filling the hollow body mold with a plastic raw material; at least biaxially rotating the hollow body mold; heating the hollow body mold at least to a melting temperature of the plastic raw material while constantly at least biaxially rotating said hollow body mold; cooling the hollow body mold to a temperature below the crystallization temperature of the plastic raw material in order to produce a bonded connection between the at least one insert element (34, 36, 38, 40) and the hollow body wall (12) formed by the plastic raw material; and removing the hollow body (10) from the hollow body mold. The invention further relates to a hollow body (10), comprising the following: at least one first cavity (18), a hollow body wall (12) which delimits the at least first cavity (18) of the hollow body (10) to a large extent, said hollow body wall (12) comprising a plastic material; and at least one insert element (34, 36, 38, 40) which has at least one region (42) freely facing the first cavity (18) and which is bonded to the hollow body wall (12). In the process, the hollow body wall (12) is produced as a single piece in a seamless manner.

Description

description

title

Process for producing a hollow body and hollow body

The present invention relates to a method for producing such a hollow body according to the preamble of claim 1 and a hollow body having a hollow body wall, which comprises a plastic material, according to the preamble of claim 5.

State of the art

Rotomoulding is a known method for producing a hollow body having a hollow body wall comprising a plastic material. In the process, a tool mold is filled with powdered plastic raw material and then heated with constant rotation about two different axes. Under the effect of heat melts the plastic raw material and applies evenly to an inner wall of the mold, whereby a wall thickness of the hollow body wall is built up during a cooling phase.

Areas of application for hollow bodies made by rotational molding process include i.a.

Industrial containers and drip pans

Fuel Tanks

- Device housing

Canoes, kayaks, boats and other floats

Lamp housing for indoor and outdoor use

Garden furniture and other plastic furniture

mobile toilet cabins

- kennels

Wheel aprons for trucks and other commercial vehicle parts

Sports and games equipment In these applications, it is often necessary or desirable to provide the hollow body with internals that can not be retrofitted because of their size in the finished hollow body, without at least temporarily destroying its integrity, which also entails a loss of mechanical strength.

US Pat. No. 4,952,347 describes as an alternative method of production a blow-molding method for producing a fuel tank from a plastic material, in which a carrier plate is arranged inside the fuel tank. The finished support plate is fixed during the Aufblasverfahrens so together with a surrounding plastic tube in a tool that during the Aufblasvorgangs an externa ßerer edge of the support plate is materially connected to an inner surface of the plastic tube.

The patent EP 1 557 251 B1 describes a method for producing a double-walled container by means of rotational molding, in which an outer container provided with outer ribs is enclosed in a rotational mold without mechanical play. By introducing, melting and subsequent cooling of plastic material into the rotational shape, an outer wall of the double-walled container is formed.

It is therefore an object of the present invention, in particular, to provide a method for producing hollow bodies with the aforementioned internals which has improvements in design freedom.

Disclosure of the invention

The present invention is a method for producing a hollow body, in particular for use as an industrial container or fuel tank having a hollow body wall comprising a plastic material, and at least a first cavity which is bounded by the hollow body wall to a major part, wherein the Hollow body wall includes a first cavity facing the wall surface and an outer space facing outer surface. In this context, a "cavity" is to be understood as meaning, in particular, a volume which is provided for receiving a quantity of liquid and the quantity of liquid in at least one spatial orientation of the liquid

Hollow body can absorb completely and permanently. In particular, all limitations of the cavity should be formed by the hollow body.

In this context, "predominantly" is to be understood as meaning, in particular, a proportion of more than 50%.

The hollow body also comprises at least one mounting element, which has at least one free-facing region of the first cavity.

The method comprises the following steps:

Arranging the at least one mounting element at a predetermined location in the interior of a hollow body mold of a rotary molding plant;

Filling the hollow body mold with plastic raw material;

at least biaxially rotating the hollow body shape;

Heating the hollow body mold during continuous, at least biaxial, rotation thereof to a temperature which corresponds at least to the melting temperature of the plastic raw material;

Cooling the hollow body mold to a temperature which is below the crystallization temperature of the plastic raw material, for producing a cohesive connection between the at least one built-in element and the hollow body wall formed by the plastic raw material; and

- Removal of the hollow body from the hollow body shape.

It is well known to those skilled in the art that plastics can be present both in amorphous form and in crystalline form, and usually in a mixture of both forms. The temperature to which the hollow body mold is applied in the step of heating should therefore be understood as a temperature which is sufficiently high to at least partially bring the plastic raw material into a viscous or liquid form, as is the case for carrying out a rotational molding process necessary is. The temperature to which the hollow body mold is brought in the step of cooling should be understood as a temperature which is sufficiently low to bring the hollow body wall formed by the plastic raw material into a non-liquid form. A "biaxial turning" is to be understood in this context in particular that the rotational movement of the hollow body mold includes a first component about a first axis of rotation and a second component about a second axis of rotation, wherein the first component and the second component simultaneously or, alternatively , can occur in chronological succession or in a combination.

The method can enable the production of hollow bodies with a wide range of fixtures with very little restriction on their design. In a suitable embodiment, a desired level externa ßere surface of the hollow body can be achieved.

The unpressurized hollow body is virtually free of mechanical stresses. Depending on the raw material used, the hollow body is mechanically robust, light, flexible, dyeable (dry blend or compounding process), UV-resistant and resistant to many chemicals.

Another advantage of the method lies in the enabled production of hollow bodies with hollow body walls, which are formed integrally and seamlessly, whereby the formation of mechanical weak points by material transitions or material seams in the production of the hollow body can be largely avoided.

In an advantageous embodiment of the method, the arrangement of the at least one mounting element in the interior of the hollow body shape by means of at least one fixing element takes place. As a result, a relative arrangement of the at least one component with respect to the hollow body wall to be produced can be ensured in a structurally simple manner during the entire production process.

The fixing element may be formed, for example, as a bead in an inner surface of the hollow body shape. Furthermore, the fixing element may be formed as a pin which can be received by a continuous recess in the tool mold and projects into the interior of the hollow body shape and into a corresponding recess in the arranged installation element. Except as a pin, the fixing element can also be configured in any other equivalent embodiment which appears to be suitable for the person skilled in the art. Most preferably, the plastic raw material is selected from the group consisting of polymers of monoolefins, diolefins, cycloolefins, polyesters, the group of polyurethanes, and the group of polyamides or comprising a mixture of these polymers. It should also be included in particular that the plastic raw material consists of one of the polymers or a mixture of polymers, which is provided with a proportion of additives, wherein the proportion of additives less than 40 wt.% And, particularly advantageous, lower than 30% by weight. Examples of additives are in particular stabilizers, pigments, processing aids, antistatic agents, color pigments, fillers and flame retardants.

Of the plastic raw materials mentioned in particular the thermoplastics are advantageously used. The plastic raw material may also comprise a reactive polymer which in particular has multiple bonds and / or functional groups and can be reacted by polymer-specific processes known to those skilled in the art during the performance of the process. As a result, hollow bodies with built-in elements with different, specific material properties can be produced for a variety of applications. In particular, the production of hollow bodies can be made possible, which at the same time have a high resistance to liquids received in the cavity in the aforementioned advantages.

In a preferred embodiment of the method, the strength of the hollow body wall at the location of the at least one installed mounting element is designed to be larger than deformation by a force acting perpendicular to the hollow body wall greater than the strength of the mounting element against deformation by acting perpendicular to the hollow body wall force.

This can advantageously be achieved that is deformed by a during the step of cooling the hollow body shape due to the shrinkage at the connection between the hollow body wall and the at least one mounting element occurring, acting perpendicular to the hollow body wall force the at least one mounting element is deformed while the Au ßenfläche the Hohlkörperwandung their shape, apart from the change in geometry by the Shrinking process, essentially retains. In this way, tighter manufacturing tolerances can be achieved with respect to externa ßere dimensions of the hollow body. The strength of the hollow body wall results from specific mechanical material properties (eg modulus of elasticity) and from a cross-sectional geometry of the hollow body wall. The force occurring during the cooling of the hollow body form results from the specific mechanical material properties of the hollow body wall (modulus of elasticity, coefficient of thermal expansion) and the temperature difference passed through during the cooling process.

The strength of the at least one built-in element results from its specific mechanical material properties and cross-sectional geometry, so that the skilled person can meet the abovementioned condition with regard to the strengths of the hollow body wall and of the at least one built-in element by material selection and design of the geometric dimensions.

In particular, the at least one mounting element may be preformed in order to achieve a preferred direction of deformation by the force acting perpendicular to the hollow body wall. For example, a built-in plate as a mounting element may have a substantially uniform curvature, which is greater when exposed to the force acting perpendicular to the hollow body wall, the direction of deformation is determined by the initial curvature. Another object of the present invention is a hollow body, comprising:

at least a first cavity,

a hollow body wall which limits the at least first hollow space of the hollow body to a predominant part, wherein the hollow body wall comprises a plastic material and has a wall surface facing the first hollow space and an outer surface facing an outer space; and

at least one installation element which has at least one free cavity facing the first cavity and which is connected materially with the hollow body wall.

The hollow body wall is integrally formed and seamless. Such hollow bodies can be advantageously used as a starting material in many fields of application, in particular for the production of reservoirs for liquids, wherein the mounting elements can be used for a variety of functions.

In an advantageous, further developed embodiment, the at least one installation element is designed as a plate. As a result, in a suitable embodiment, for example, an improvement in the mechanical strength of the hollow body can be achieved. In another suitable embodiment, an undesired movement of a liquid located in the first cavity may be restricted or prevented, the plate serving as a baffle to prevent or limit an amplitude of slosh vibrations of the liquid. In order to improve the mechanical stability with respect to a deformation perpendicular to the plane of the plate, the surfaces of the at least one built-in element designed as a plate can be deviated from a plane parallelism. For example, the plate may be provided for reinforcement with at least one profile element which is rod-shaped and integrally formed on the plate or releasably fixedly connected thereto.

Particularly preferably, the profile element is designed as a frame element, which is connected to at least two adjacent side edges of the plate.

An improved mechanical stability with respect to a deformation perpendicular to the plane of the plate can also be achieved for the plate-formed at least one mounting element, when a cross-sectional shape of the plate perpendicular to the plate plane and perpendicular to a maximum extension direction of the plate has a profile shape. In particular, the profile shape may have a substantially undulating or zigzagging centerline.

If the plate is arranged substantially perpendicular to the hollow body wall, undesired movement of the liquid located in the first cavity can be particularly effectively restricted or prevented. By "

Substantially perpendicular "should in this context, in particular an angle formed by the hollow body wall and the plate of advantageously more than 70 ° and less than 1 10 ° and, particularly advantageously, of more than 80 ° and less than 100 °.

In a further advantageous, further developed embodiment, the plate is equipped with a number of through recesses. As a result, with a suitable design, the efficient prevention or restriction of a movement of the liquid present in the first cavity can be achieved with a simultaneously particularly high mechanical stability of the hollow body.

Furthermore, it is proposed that the hollow body comprises at least one arranged in the interior of the first cavity plate, wherein the at least one mounting element is provided for holding the at least one plate.

Thereby, a simple and secure mounting of the at least one plate in the interior of the first cavity can be achieved, wherein the plate may consist of any material. With particular advantage, the at least one mounting element may include a spring element, which is at least partially tensioned before and after the production of the material connection between the mounting element and the hollow body wall, so that the at least one plate is acted upon by the spring force of the spring element. As a result, a movement of the at least one plate arranged in the interior of the first cavity relative to the hollow body wall can at least be reduced or prevented, and undesired noise during movement of the hollow body can be avoided.

In a further advantageous embodiment, the cohesive connection is designed in the manner of a partial casing, by which the at least one installation element and the hollow body wall are connected in one piece. In a suitable embodiment can thus be achieved that the at least one mounting element with the hollow body wall is reliably mechanically connected in a simple manner.

In a particularly advantageous embodiment, the hollow body to a second cavity, which is limited to a predominant part of the hollow body wall, wherein the first cavity and the second cavity of a

Partition wall are liquid-tightly separated from each other and the partition comprises the at least one mounting element. Such hollow bodies can be advantageous to be used separately for liquids intended for combination or used together in a system. For example, the first cavity for receiving a fuel and the second cavity may be provided for receiving a urea solution.

If the partition wall comprises at least a second mounting element, wherein the first mounting element and the second mounting element form at least part of a wall of a third cavity, which is liquid-tightly separated from the first cavity and the second cavity, a particularly high stability against mechanical stress can be achieved , In addition, increased separation between two different liquids accommodated in the first cavity or the second cavity can be achieved by improved separation. In an alternative use, the third cavity may advantageously also serve to receive a third, different from the other two different liquid.

In an embodiment in which the third cavity is provided to receive a filler material selected from a group consisting of foamed plastics and porous, substantially inorganic materials, the mechanical stability can be further improved. Examples of suitable, foamed plastics are PE foam and PUR foam. An example of a suitable, porous, inorganic material are clay minerals, by means of which a liquid, which is absorbed by the first cavity and due to leakage into the third cavity, or a liquid, which is received by the second cavity and due to a further leakage in exceeds the third cavity, can be safely absorbed.

In an alternative, advantageous embodiment, the third cavity can also be provided for receiving a leakage sensor, by means of which leaks which occur between the first cavity and the third cavity or between the second cavity and the third cavity can be detected.

Furthermore, it is proposed that the at least one installation element made of a plastic material or of metal or of a plastic / metal

Composite material exists. In particular, the plastic material may correspond to the plastic material of the hollow body wall, whereby a particularly inniv ge cohesive connection can be achieved. By using metal, a particularly high mechanical strength of the mounting element can be achieved.

Advantageously, a wall thickness of the hollow body wall is at least 1 mm and at most 25 mm and in particular, particularly advantageously at least 2 mm and at most 10 mm, whereby a balanced compromise between weight and mechanical strength of the hollow body can be achieved. In this context, a "wall thickness" should be understood as meaning, in particular, a local next distance between the wall surface facing the cavity and the outer surface facing the outer space.

A further aspect of the invention is the use of one of the disclosed embodiments and further developments of the method or a combination thereof for the production of one of the disclosed embodiments and / or a combination thereof of a hollow body.

drawing

Further advantages emerge from the following description of the drawing. In the drawing, an embodiment of the invention is shown. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

Show it:

1 shows a hollow body according to the invention, comprising two cavities, in a schematic representation,

2a an alternative possibility for arranging the installation element of the hollow body according to FIG. 1,

2b shows a further alternative possibility for arranging the installation element of the hollow body according to FIG. 1,

3 shows an alternative embodiment of a hollow body according to the invention, 4 shows a detail of a further alternative embodiment of a hollow body according to the invention,

5 shows a detailed view of the installation element of the hollow body according to FIG. 4, FIG.

6 shows an alternative embodiment of a built-in element,

7 is a partially sectioned, perspective partial view of the finished hollow body according to FIG. 4,

8 shows partial and detailed views of a further alternative embodiment of a hollow body according to the invention, comprising three cavities, and

Fig. 9 shows a further alternative embodiment of a mounting element.

Description of the embodiments

This description contains several embodiments of the invention. The individual embodiments are described with reference to a particular group of figures and designated by a first digit. Features whose function is identical or fundamentally identical in each embodiment are indicated by reference numerals consisting of the number of the embodiment and the number of the feature common to all the embodiments, thus constituting a single number. A description of the function of a feature of an embodiment may therefore also be included in a description of one of the preceding embodiments.

Fig. 1 shows a hollow body 1 10 in cuboid shape, comprising a first cavity 1 18 and a second cavity 120. The hollow body 1 10 has a hollow body wall 1 12, which forms five of six side surfaces of the formed as a partial cuboid first cavity 1 18 and thus limits the first cavity 1 18 of the hollow body 1 10 to a predominant part. Furthermore, the hollow body wall 1 12 forms five of six side surfaces of the second cavity 120, which is likewise designed as a partial cuboid, and delimits the second cavity 120 of the hollow body 110 to a predominant extent. Furthermore, the hollow body wall 1 12 has an inner wall surface 124, which with a first part of the first cavity 1 18 and with a second part of the second cavity cavities 120 facing, and a Au ßenraum 128 facing Au ßenfläche 126 on.

The hollow body wall comprises as a plastic material linear low-pressure polyethylene (PE-LLD) with a density of 0.935 g / cm ³ , from which it consists to more than 90 wt.%. A wall thickness 1 16 (FIG. 2 a) of the hollow body wall 1 12 is 8 mm and the total volume of the first cavity 1 18 and of the second cavity 120 amounts to a total of approximately 120 I.

Alternatively, a plastic raw material selected from a group consisting of polymers of monoolefins (alkenes), of diols, of cycloolefins (cycloalkenes), of polyesters, of the group of polyurethanes and of the group of polyamides may be used is formed or which comprises a mixture of these polymers.

Furthermore, the hollow body 1 10 has a mounting element 134. The mounting element 134 is formed as a plate, which consists of PE-LLD and parallel to end faces 1 14, 1 14 'of the cuboid hollow body 1 10 and to both end faces 1 14, 1 14' spaced between them. The installation element 134 has, in the form of one of the plate surfaces 152, a region facing the first cavity 1 18 and, in the form of the opposing plate surface 152 ', a region freely facing the second cavity 120. The mounting member 134 is connected to Au ßenkanten 154 of the plate with the hollow body wall 1 12 by applying a rotational molding process cohesively.

The first cavity 1 18 and the second cavity 120 of the hollow body 1 10 are liquid-tightly separated from each other by a partition wall 158, wherein the partition wall 158 includes the mounting member 134 such that the mounting member 134 forms the entire partition wall 158.

The hollow body wall 1 12 is integrally formed and seamless and includes both the first cavity 1 18 and the second cavity 120 of the hollow body 1 10 liquid-tight against the Au ßenraum 128 from.

The illustrated in Fig. 1 hollow body 1 10 serves as a starting product for the preparation of a reservoir for two different liquids (not shown). The access to the first cavity 1 18 (shown in dashed lines in FIG. is) by a first continuous recess 130 in a above the first cavity 1 18 arranged portion of the hollow body wall 1 12 allows. The access to the second cavity 120 (likewise shown in dashed lines in FIG. 1) is produced by a second through-cut recess 132 in a region of the hollow body wall 12 arranged above the second cavity 120.

The first recess 130 and the second recess 132 in the hollow body wall 12 1 can subsequently be equipped with sealing closure elements.

The use of the rotational molding method for producing the hollow body 10 according to FIG. 1 will be explained below.

In a known manner, there is initially a metallic hollow body mold 170 (FIG. 2 a), the cavity of which corresponds essentially to the outer contours of the hollow body 1 10 in a closed state of the hollow body mold 170 and which is intended for use in a rotational molding installation. Device-technical details of the rotary molding plant are familiar to the person skilled in the art. They are therefore reproduced in the figures only insofar as it is necessary for understanding the invention.

In a first step, the built-in plate 134 mounting element is disposed at a predetermined location in the interior of the hollow body mold 170. Various possibilities of arrangement will be described in detail below.

In a next step, the hollow body mold 170 is filled with a predetermined amount of the plastic raw material low-pressure polyethylene (PE-LLD) in the form of PE powder or micro-pellets.

Subsequently, the hollow body mold 170 is held in a rotatable holder of the rotary molding plant and simultaneously rotated about two different axes of rotation (not shown). In continuous, biaxial turning, the hollow body mold 170 is heated by a heating device of the rotary molding plant to a temperature of 190 ° C, in which the low-pressure polyethylene is at least partially in viscous form. Under the influence of the ruling center By centrifugal force, the low-pressure polyethylene attaches to the inner wall of the hollow body mold 170 and builds the hollow body wall 1 12 with increasing wall thickness 1 16. The predetermined amount of PE-LLD is such that the desired wall thickness 1 16 is reached when substantially all of the filled plastic raw material rests against the inner wall of the hollow body mold 170. The desired wall thickness 1 16 is designed so that the hollow body wall 1 12 formed forms a cohesive connection with the mounting element 134 arranged in the interior of the hollow body mold 170 (FIG. 2 a, bottom). In a further step, the hollow body mold 170 is cooled during continuous biaxial turning to a temperature which is below the crystallization temperature of the plastic raw material. In a final step, the hollow body 1 10 can be removed from the hollow body mold 170. FIGS. 2 a and 2 b show alternative possibilities for arranging the mounting element 134 at the predetermined location in the interior of the hollow body mold 170, in which the mounting element 134 is arranged by means of at least one fixing element 144. FIG. 2 a shows a detail of a hollow body mold 170 which is equipped with a fixing element 144 in the form of a bead. When arranging the installation element 134 in the interior of the hollow body mold 170, an outer edge 154 of the installation element 134 and the bead form a positive connection, by means of which the installation element 134 is held in the hollow body mold 170.

The upper part of Fig. 2a shows the mounting element 134 before an arrangement in the hollow body mold 170. The lower part of Fig. 2a shows a partial view of the hollow body 1 10 after completion of the rotational molding process. The mounting element 134 and the hollow body wall 12 form a material connection.

In the embodiment shown in FIG. 2b, the fixing element 244 is formed by a cylindrical pin which is arranged to arrange a mounting element 234 formed as a plate from the direction of the outer space 228 through a continuous recess in the hollow body shape 270 into a corresponding cylindrical recess in an end face 256 of the mounting element 234 is displaceable. An alternative embodiment of a hollow body 310 is shown in FIG. 3. The hollow body 310 is embodied in a cuboid shape and has a cavity 318 which is provided for receiving a liquid (not shown) formed by diesel fuel. The hollow body 310 has a hollow body wall 312, which forms all six side surfaces of the cavity 318 and thus limits this to a predominant part. Furthermore, the hollow body wall 312 has an inner wall surface 324, which faces the cavity 318, and an outer surface 328 facing the outer surface 326. The hollow body 310 comprises a built-in element 334, which is formed as a plate which consists of PE-LLD and within the cavity 318 parallel to end faces 314, 314 'of the cuboid hollow body 310 and to both end faces 314, 314' spaced therebetween, so that the cavity 318 is divided by the plate into two subspaces. The mounting member 334 has the cavity 318 freely facing portions 342 through which

Plate surfaces 352, 352 'are formed. The mounting member 334 is integrally bonded to outer edge 354 of the plate with the hollow body wall 312 by using a rotational molding process, whereby a transition of gas and liquid between the partial cavities ensured by recesses 364 at both lower corners of the plate and a recess 366 at the upper edge of the plate is, and even at a low liquid level within the cavity 318, an exchange of liquid between the two partial cavities can take place. The plate is arranged perpendicular to the hollow body wall 312 and has four continuous, circular recesses 346, wherein the circle centers form corner points of a square. When using the hollow body 310 as a diesel fuel tank of a motor vehicle, a dynamic load due to the movement of the motor vehicle, which transmits to the liquid content, can be greatly reduced because the plate movement of the liquid depending on

Liquid level only through the through recesses 346, the recesses 364 allows at the two lower corners and the recess 366 at the upper edge, so that a potentially excited slosh vibration of the liquid would be greatly attenuated.

Another alternative embodiment of a hollow body 410 is shown in FIG. The hollow body 410 is other than those described below Differences identical to the embodiment of the hollow body 310 shown in FIG. 3 executed.

The hollow body 410 is made entirely of polypropylene (PP) and comprises a plate 450 arranged inside the cavity 418, which likewise consists of polypropylene and is equipped with a number of continuous, circular recesses 446. Alternatively, the plate could also be made of metal, for example aluminum or steel sheet. The hollow body 410 further has four mounting elements 438, 440, which are provided for holding the plate. Two of the four mounting elements 438, 440 are shown in FIG. 4, the other two of the four mounting elements 438, 440 are arranged on the opposite side of the plate 450. Alternatively, the other two of the four mounting elements 438, 440 could be disposed on the adjacent lower side of the plate 450. In principle, more than the mentioned four mounting elements 438, 440 may be provided for holding the plate 450.

7 shows a detailed view of the plate 450, which is respectively supported on each side with two of the four mounting elements 438, 440, in a finished state of the hollow body 410. Each of the mounting elements 438, 440 is designed as a metal bolt (FIG. 5), FIG. which essentially has a cylindrical symmetry about a longitudinal axis and comprises a plate-near end and a plate-distal end. The plate-near end is provided with a groove whose width is adapted to a thickness of the plate 450. The plate-distal end has a threaded blind hole 448. The installation element 438, 440 can be detachably fastened to the hollow body mold 470 by means of the threaded blind hole 448 and a fastening screw (not illustrated) which engages in the threaded blind hole 448 at a predetermined location in the interior of the hollow body mold 470 through a continuous recess. To prepare for manufacture, the four mounting elements 438, 440 are fastened to the predetermined locations of the hollow body mold 470, the plate 450 engaging in the grooves of the mounting elements 438, 440 and forming a form-locking connection. The positive connection between the plate 450 and the mounting element 438, 440 can also be designed as a transition fit or interference fit. In principle, it is also possible to use other forms of form-fit connections between the plate 450 and each of the installation elements 438, 440 which appear suitable to the person skilled in the art. In Fig. 6, for example, a mounting element 568 is shown, the plate-near end of the metal bolt is designed as a spherical or cylindrical thickening 568 which is guided through a corresponding circular recess 560 in a plate 550, but after a brief downward movement of the plate 550 of a formed on the recess 560 elongated hole 562 is retained. A corresponding embodiment is shown in FIG. 6. In the lower part of FIG. 6 it is shown that the mounting element 568 includes a spring element 572, which is at least partially tensioned after a production of the positive connection between the plate 550 and the mounting elements 538, 540. As a result, the plate 550 is acted upon by the spring elements 572 of the mounting elements 538, 540 with a spring force which at least reduces or prevents movement of the plate 550 relative to the hollow body wall 512, whereby an undesired noise during movement of the hollow body 510 can be avoided.

From Fig. 4 it can be seen that each mounting element 438, 440 has a cross-sectional thickening in the vicinity of the plate-distal end, which is formed in the shape of a regular hexagon.

As shown in FIGS. 4 and 5, the cohesive connection between the mounting elements 438, 440 and the hollow body wall 412 is formed in the manner of a partial casing, through which each of the mounting elements 438, 440 and the hollow body wall 412 are connected in one piece. Each of the mounting elements 438, 440 has a region 442 which faces the cavity 418 freely. The cohesive connection includes the cross-sectional thickening of the mounting elements 438, 440 in a hexagonal shape, so that a mechanically particularly stable connection is achieved. As will be readily apparent to those skilled in the art, the cross-sectional thickening of the mounting members 438, 440 may be in a different shape, e.g., in the hexagonal shape shown, e.g. a square shape or a star shape, be formed.

In Fig. 7 the relative arrangement of the hollow body wall 412, the plate 450 and the mounting elements 438, 440 is shown in a partially sectioned, perspective partial view of the finished hollow body 410. FIG. 8 shows a detail of a further embodiment of a hollow body 610 which, with the exception of the dimensions and the deviations described below, corresponds to the embodiment according to FIG. 1. In contrast to the embodiment according to FIG. 1, the partition wall

658 between the first cavity 618 and the second cavity 620 in addition to the mounting member 634 still a second, designed as a plate Einbeins- element 636, wherein the partition 658 the mounting elements 634, 636 such summarized that the mounting elements 634, 636 the entire Form partition 658. The first installation element 634 and the second installation element 636 are characterized by

Connected to a double-walled plate and form part of a wall of a third cavity 622 which is liquid-tight from the first cavity 618 and the second cavity 620 is separated. The third cavity 622 is provided to receive, prior to manufacture of the hollow body 610, a filler material formed of foamed polyurethane (PUR) which serves to mechanically strengthen the partition wall 658 with only a slight increase in weight. Alternatively, the third cavity 622 may also be filled with a suitable porous clay mineral to receive liquids passing from the first cavity 618 or the second cavity 620 into the third cavity 622. In a further alternative, the third cavity 622 may be provided to receive a leakage sensor (not shown) intended to provide fluid leakage between the first cavity 618 and the third cavity 622 and between the second cavity 620, respectively and the third cavity 622.

In a not shown, slightly modified embodiment of the embodiment according to FIG. 8, the hollow body wall 612 at the location of the mounting elements 634, 636 rectilinear, i. without beading, be executed. The wall thickness 616 of the hollow body wall 612 is selected so that the strength of the

Hollow body wall 612 against deformation by a perpendicular to the hollow body wall 612 acting force is greater than the strength of the mounting elements 634, 636 against deformation by this force. By the shape of the mounting elements 634, 636 indicated in FIG. 8, in which a plate surface 624 of the mounting element 634 faces the cavity 618 and a plate surface 624 'faces the cavity 620 in a convex manner, and by the strengths described above results from the occurring during the cooling of the hollow body mold 670 by the shrinkage of the hollow body wall 612 force deformation of the mounting elements 634, 636 such that their convex curvature increases, while the Au ßenfläche 626 of the hollow body wall 612 at the place of Built-in elements 634, 636 essentially retains its shape. As a result, a design of the outer surface 626 of the hollow body wall 612 with narrow manufacturing tolerances is possible.

A further alternative embodiment of a mounting of a metallic plate 750 by means of mounting elements 738, 740 in a cavity 718 of a hollow body 710 is shown in FIG. The two constructed as a metal bolt mounting elements 738, 740 are connected to each other by means of a metal rail 776 made of spring steel. The mounting elements 738, 740 are intended to be releasably secured in the manner described in the embodiment of Figures 4 and 5 on a hollow body mold 770. On the opposite side of the hollow body mold 770 identical mounting elements 738 ', 740', connected to a metal rail 776 'of identical design, arranged to support an opposite side of the metallic plate 750 (not shown). The metal rail 776 has two unwound end pieces 778, 778 ', each provided with a slot, each of the slots being adapted to form a positive connection with the plate 750. Further, the metal rail 776 includes a spring member 772 which is formed as a metal tongue, which has a spring action due to the spring steel properties. As can be seen from the left part of FIG. 9, the spring element 772 and a corresponding spring element 772 'on the opposite side of the plate 750 in a fitted state of the plate 750 are partially tensioned, so that the plate 750 with the spring force of the spring elements 772 and 772' acted upon and held in position, wherein in each case a stop element 774, 774 'of the metal rail 776, 776' limits a lateral movement of the plate 750. LIST OF REFERENCE NUMBERS

10 hollow body 72 spring element

12 hollow body wall 74 stop element

14 end face 76 metal rail

16 wall thickness

18 first cavity

20 second cavity

22 third cavity

24 inner wall surface

26 Outer surface

28 outdoor space

30 recess access

32 recess access

34 built-in element (plate)

36 built-in element (plate)

38 installation element (bolt)

40 installation element (bolt)

42 freely facing area

44 fixing element

46 through recess

48 threaded blind hole

50 plate

52 plate area

54 outside edge

56 front side

58 partition

60 circular recess

62 long hole

64 recess

66 recess

68 cylindrical thickening

70 hollow body shape

Claims

claims

1 . Method for producing a hollow body (10), which comprises a hollow body wall (12) which comprises a plastic material, at least one first cavity (18) which is delimited to a predominant part by the hollow body wall (12), wherein the hollow body wall (12) a wall surface (24) facing the first cavity (18) and an outer surface (26) facing an outer space (28), and at least one mounting element (34, 36, 38, 40) comprising at least one first cavity (18) having a freely facing region (42), characterized by the following steps:

- arranging the at least one mounting element (34, 36, 38, 40) at a predetermined location in the interior of a hollow body mold of a rotary molding plant;

Filling the hollow body mold with plastic raw material;

at least biaxially rotating the hollow body shape;

Heating the hollow body mold with continuous, at least biaxial rotation of the same to a temperature which corresponds at least to the melting temperature of the plastic raw material;

Cooling the hollow body mold to a temperature which is below the crystallization temperature of the plastic raw material, for producing a material connection between the at least one mounting element (34, 36, 38, 40) and the hollow body wall (12) formed by the plastic raw material; and

Removal of the hollow body (10) from the hollow body shape.

2. The method according to claim 1, characterized in that the arranging of the at least one mounting element (34, 36, 38, 40) by means of at least one fixing element (44).

3. The method according to claim 1 or 2, characterized in that the plastic raw material is selected from a group consisting of polymers of monools, from diolefins, from cycloolefins, from polyester, from the group of polyurethanes and from the group of Polyamide is formed or that it comprises a mixture of these polymers.

4. The method according to any one of the preceding claims, characterized in that the strength of the hollow body wall at the location of the at least one arranged mounting element against deformation by a force acting perpendicular to the hollow body wall force is designed to be greater than the strength of the mounting element against deformation by the perpendicular to the hollow body wall attacking force.

5. hollow body (10), comprising:

at least a first cavity (18),

a hollow body wall (12) which limits the at least first cavity (18) of the hollow body (10) to a predominant part, the hollow body wall (12) comprising a plastic material and a first cavity (18) facing wall surface (24) and a Au ßenraum (28) facing Au ßenfläche (26);

at least one installation element (34, 36, 38, 40) which has at least one region (42) which faces freely the first cavity (18) and which is connected in a materially bonded manner to the hollow body wall (12);

characterized in that

the hollow body wall (12) is integrally formed and seamless.

6. hollow body (10) according to claim 5, characterized in that the at least one mounting element (34, 36, 38, 40) is formed as a plate.

7. Hollow body according to claim 6, characterized in that the plate is arranged substantially perpendicular to the hollow body wall (12).

8. A hollow body according to claim 6 or 7, characterized in that the plate is equipped with a number of through recesses (60).

9. A hollow body according to claim 5, characterized by at least one inside the first cavity (18) arranged plate (50), wherein the at least one mounting element (38, 40) for holding the at least one plate (50) is provided.

10. Hollow body according to one of claims 5 to 9, characterized in that the cohesive connection formed in the manner of a partial casing is, by which the at least one mounting element (34, 36, 38, 40) and the hollow body wall (12) are connected in one piece.

1 1. Hollow body according to one of claims 5 to 10, characterized by a second cavity (20), which is delimited to a predominant part of the hollow body wall (12), wherein the first cavity (18) and the second cavity (20) of a partition ( 58) are liquid-tightly separated from each other and the partition wall (58) comprises the at least one mounting element (34, 36).

12. Hollow body according to claim 1 1, characterized in that the partition wall (58) has at least one second mounting element (36), wherein the first mounting element (34) and the second mounting element (36) at least part of a wall of a third cavity (22 ) which is liquid-tightly separated from the first cavity (18) and the second cavity (20).

13. A hollow body according to claim 12, characterized in that the third cavity (22) is provided to receive a filling material selected from a group consisting of foamed plastics and porous, substantially inorganic materials.

14. Hollow body according to one of claims 5 to 13, characterized in that the at least one mounting element (34, 36, 38, 40) consists of a plastic material or of metal or of a plastic / metal composite material.

15. Hollow body according to one of claims 5 to 14, characterized in that a wall thickness (16) of the hollow body wall (12) is at least 1 mm and at most 25 mm.

16. Use of a method according to one of claims 1 to 4 for producing a hollow body (10) according to one of claims 5 to 15.