Method for producing a blow molded part and blow molded part

Abstract

To provide a method for manufacturing a blow molded article provided with a support structure.SOLUTION: A method in which a support structure (2) is provided and arranged in a blow mold, a preform is introduced into the blow mold in such a way that the support structure (2) is at least partially surrounded by the preform, the blow mold is then closed, a base body (5) surrounding the support structure (2) is produced from the preform by blow molding, and the base body (5) is connected to the support structure (2) in a material-fit and / or form-fit manner during the blow molding. The invention further relates to a method for producing a blow molded article (1), comprising a base body (5) surrounding a cavity and a support structure (2) arranged within the base body (5), wherein the base body (5) and the support structure (2) delimit the cavity (15), and wherein the base body (5) and the support structure (2) are integrally connected to one another.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a blow-molded article provided with a support structure, and further to a blow-molded article produced by such a method.

[0002] In the blow molding process, a tubular or planar preform is placed in a blow mold, which is pressed against the preform from the outside to define the outer contour of the blown part. The blow mold usually contains two blow mold tools with cavities, which are movable relative to each other, and when the blow mold tools are closed, the preform is pressed against the edge area of ​​the cavity of the blow mold tools. A seam is formed in this area of ​​the blown part to be produced, and the blown part is formed in the cavity area, leaving a slug of protruding material outside the cavity. The slug is removed from the blow molded part after the blow molding process is completed.

[0003] Blow-molded articles have a wide range of applications. For example, blow-molded articles are used in electric mobility, particularly in the form of tubing, to guide temperature-regulating media to various components of electric vehicles, such as storage batteries or heat exchangers for temperature regulation in the passenger compartment. Since storage batteries only perform optimally within a limited temperature range, the batteries may need to be heated or cooled depending on the ambient temperature. Similarly, the passenger compartment may need to be cooled or heated depending on the ambient temperature. The tubing allows temperature-regulating media of various temperatures to be distributed and supplied to the various components. Further applications are found in stationary applications, such as temperature regulation applications for heating and cooling circuits in energy storage facilities or building technology.

[0004] The blow-molded article can also be used in the form of a container, in particular as a compensation container for a temperature-regulating medium. Temperature changes can cause the volume of the temperature-regulating medium to change. An increase in the temperature of the temperature-regulating medium causes the temperature-regulating medium to expand. This increases the pressure in the compensation container, and when a certain pressure is exceeded, air escapes from the compensation container via a valve. Then, when the temperature of the temperature-regulating medium returns to normal, the temperature-regulating medium contracts again, creating a negative pressure. As a result, air flows into the compensation container via the valve until pressure compensation is achieved. Therefore, during operation, the compensation container is usually under positive or negative pressure, depending on the situation.

[0005] These positive and negative pressures impose special requirements on the structural strength of the compensation container, particularly on the structural strength and dimensional stability of the interfaces that guide the medium of the compensation container to other components and the mechanical attachment points of the compensation container. These requirements have not been met until now with blow-molded compensation containers. Therefore, separate structural components may have to be provided as interfaces within the compensation container. Additional interface elements, such as a screw cap for the filling opening, a positive or negative pressure valve, a temperature or fill level sensor, or an outlet connection for the electrostatic compensation potential, may also have to be incorporated. In this case, the structural components that enclose the structural space create constraints when forming the blow-molded part.

[0006] From EP 3259110 B1 a method for extrusion blow-molding a container made of thermoplastic plastic is known, in which an insert part with a feed-through is arranged in such a way that after extrusion blow-molding the insert part is located on the outer surface of the container.

[0007] The object of the present invention is to provide a simple method for producing blow-molded articles, which allows for the inexpensive production of blow-molded articles.A further object of the present invention is to provide a blow-molded article that can be inexpensively produced.

[0008] This problem is solved by the features of claim 1. The dependent claims relate to advantageous configurations.

[0009] In the method for producing a blow-molded article according to the present invention, a support structure is prepared and placed in a blow mold, a preform is introduced into the blow mold so that the support structure is at least partially surrounded by the preform, the blow mold is then closed, and a substrate surrounding the support structure is produced from the preform by blow molding, and the substrate is bonded to the support structure in a material- and / or form-fitting manner during blow molding.

[0010] The preform is preferably tubular. When the preform is introduced into the blow mold, it is preferably placed on a support structure, so that the support structure is located inside the preform and is surrounded by the tubular preform. During blow molding, the preform is applied to the support structure from the outside. Alternatively, the preform can be formed flat.

[0011] Blow molding creates a cavity defined by the substrate and the support structure. The cavity can be formed, in particular, to accommodate and / or allow a fluid to flow through it. In this case, the fluid can be a gas or a liquid, such as a temperature-regulating medium.

[0012] The material-bonding connection between the support structure and the substrate can be easily and inexpensively manufactured, particularly if the substrate and the support structure are made of plastic, preferably with similar melting temperatures. This avoids reheating, making the material-bonding connection particularly energy-efficient and therefore inexpensive. Preferably, the substrate and the support structure are made of the same plastic. Polymer materials, particularly polyolefins such as polypropylene and / or polyamide, are considered as plastics for the substrate and the support structure.

[0013] It is also conceivable to construct the substrate and / or the support structure in multiple layers, in which case different plastics are used for each of the layers. This allows the substrate to be provided with additional functions, for example, by incorporating foam, thereby achieving improved thermal insulation. Similarly, by selecting the appropriate materials, it is conceivable to obtain improved chemical properties, such as improved stability, especially improved compatibility with oil media.

[0014] The support structure may include elements that serve to connect the blow-molded article to other components. These elements may have or form a particular interface geometry. The interface geometry for connection is, for example, a screw thread. The screw thread may be covered by a protective cover, which serves to protect the interface geometry during the production of the blow-molded article. Following production, particularly following the blow-molding process, the protective cover can be removed. In this case, it is particularly advantageous to provide a particularly dimensionally stable interface geometry, which can be ensured by the protective cover even during the blow-molding process. The interface geometry can thereby be used to connect a positive pressure function and / or a negative pressure function.

[0015] In principle, it is conceivable to configure the support structure or interface geometry as a material composite of different material classes, for example a combination of plastic and metal or a combination of plastic and ceramic, particularly preferably by a material-bonding connection.

[0016] The base body and the support structure are firmly connected to one another by a material-tight connection. It is particularly advantageous for the material-tight connection to be produced directly by the blow molding process during the shaping of the base body. If the support structure has protruding elements, tube pieces, etc., with connecting elements, the connection between the base body and the support structure can be particularly medium-tight, at least in the region of the protruding elements. In this case, the medium-tight connection can be produced by the material-tight connection during the blow molding process. In this case, there is no need to arrange additional sealing elements, such as flat seals or O-rings, between the base body and the support structure, which reduces the number of individual components. Furthermore, an additional manufacturing step for producing the medium-tight connection between the base body and the support structure can be omitted.

[0017] The support structure can have external welding ribs, which are particularly designed to be bonded to the substrate during blow molding in a material-tight manner. The welding ribs can be arranged on the support structure from the outside, and during blow molding, the welding ribs are welded to the preform by contact and bonded to the substrate in a material-tight manner.

[0018] Furthermore, the welding ribs can achieve a targeted mechanical reinforcement of the blow-molded article. The blow-molded article can be structurally reinforced in the areas where the welding ribs are arranged, so that higher forces can be absorbed and dissipated at least in these areas. Higher forces can occur both in the case of positive and negative pressure inside the blow-molded article. Furthermore, the welding ribs can improve the bond between the structural component and the substrate. The linear configuration of the welding ribs allows them to be fused to the preform in a targeted manner during blow molding. This is advantageous compared to a planar bond between the support structure and the preform. This reduces the tolerance requirements for the component, which is particularly advantageous for support structures that are often configured as injection-molded components, which have higher manufacturing tolerances and thus dimensional deviations that can make an optimal planar bond between the support structure and the preform difficult. In contrast, the welding ribs can advantageously be manufactured with less effort and with fewer manufacturing tolerances, resulting in an improved bond between the welding ribs and the preform. Furthermore, the linear contact allows for greater dimensional deviations to be tolerated. Additionally, mechanical undercut structures can be provided in the support structure or in the interface geometry to further improve the mechanical resistance of the bond.

[0019] The support structure may include at least one connecting tube piece protruding from the support structure, the connecting tube piece having at least one welding rib arranged on its exterior, the welding rib of the connecting tube piece being material-bondably connected to the base material during blow molding.

[0020] The connecting piece can define a passage and can be connected to the cavity of the base body in a flow-guiding manner. In particular, fluids can be introduced into and removed from the blow-molded article through the connecting piece. Particularly preferably, the blow-molded article can be connected in a flow-guiding manner exclusively via the connecting piece. A tight connection between the base body and the connecting piece is achieved by a welded rib on the connecting piece. Depending on the application, the support structure can have multiple connecting pieces, each of which preferably has one welded rib. In this case, it is particularly preferable to produce a particularly dimensionally stable interface geometry in order to provide a particularly pressure- and vacuum-resistant threaded connection in the blow-molding process.

[0021] The connecting piece can have an opening, and the base body forms a cover region covering the opening during blow molding, and the opening can be made accessible by removing the cover region associated with the opening. The cover region forms a protective cover. Depending on the implementation of the blow molding process, after the base body is shaped from the preform and after the material-tight connection between the base body and the support structure is created, the opening in the connecting piece can be covered by the cover region of the base body. Therefore, in a subsequent manufacturing step, material from the base body in the cover region may have to be removed. For this purpose, holes can be made in the base body to create the opening, or the wall of the base body can be cut out in the area of ​​the opening. It is also conceivable that a material weakening portion forming a target break point can be created in the base body during blow molding. After the blow molding process, the opening can be made accessible by tearing the material in the area of ​​the material weakening portion. Furthermore, the opening can be created by punching or heat separation.

[0022] The blow mold may have at least two blow molding tools, with the support structure and preform positioned between them before blow molding, and the blow molding tools pressing the preform against the support structure when the blow molding mold is closed. In this case, the blow molding tools can press the preform so that a separation region is generated in the base during blow molding. Preferably, the separation region surrounds a cover region, and the cover region of the base covers the opening of the connecting tube piece after blow molding. The separation region is an intentional structural weakening of the base, so that after the blow molding process, the base separates at this separation region and the cover region is removed, thereby exposing the opening of the connecting tube piece. In this case, separation at the separation region can be preferably achieved without the use of a tool and with only slight force, for example by tearing, which simplifies the production of blow-molded articles.

[0023] The blow molding tool may be equipped with a press edge, which is applied linearly to the substrate with a preload during blow molding. This allows for particularly easy removal of the cover area after blow molding. The separation area generated by the press edge may be configured as an annular groove. The press edge may be configured in the form of a rib. Depending on the design, the press edge may also form a cutting edge, which allows for particularly easy separation of the separation area. In this case, the cutting edge may be configured in such a way that the separation area is already separated when the blow mold is closed.

[0024] The connecting piece can have a connecting element for connecting to the connecting component. In this case, a protective element is placed in the blow mold before blow molding, so that the protective element is positioned between the connecting element and the substrate after blow molding. In this case, the protective element protects the connecting element, so that the preform does not press against the connecting element and undesired bonding between the connecting element and the substrate is prevented. After the blow molding process, the substrate can be separated at the separation area, allowing the cover area to be removed. This exposes the protective element, which can then be removed. Preferably, the protective element is made of a material having a higher glass transition temperature than the materials of the support structure and the preform. This prevents the protective element from bonding to the support structure and / or the preform during blow molding. Particularly preferably, the protective element is made of plastic. The protective element may be made of a thermoplastic resin, such as polyoxymethylene.

[0025] The support structure may be formed as a rib structure. This allows the support structure to be constructed in a weight- and material-saving manner while maintaining structural stability. Preferably, the rib structure is designed to handle both positive and negative pressure. In the areas between the ribs, the structure of the blow-molded article may be intentionally made structurally weaker. Such structural weaknesses can serve, for example, to provide a defined area for expansion when positive pressure occurs inside the blow-molded article.

[0026] The support structure may have a sensor holder, on which a sensor can be placed before blow molding, and which is then placed and fixed in the blow-molded part after the blow-molding process. In this case, it may be advantageous if the sensor holder formed by the support structure remains in the blow-molded part after blow molding, so that an additional work step for removing the sensor holder is not required. This allows the blow-molded part to be produced particularly inexpensively. Various sensors, in particular a fill level sensor, a temperature sensor, or a pressure sensor, may be attached to the sensor holder.

[0027] The problem underlying the present invention is also solved by a blow-molded article produced by the described method. The blow-molded article according to the present invention has a base body surrounding a cavity and a support structure arranged inside the base body, the base body and the support structure defining the cavity, and the base body and the support structure being materially connected to each other. The blow-molded article according to the present invention is obtained by the above-described method. The blow-molded article may be formed, in particular, as a container or a tube device. If the blow-molded article is formed as a container, the container is closed and is used to contain a fluid. If the blow-molded article is formed as a tube device, the tube device has two tube openings and is used to guide a fluid.

[0028] The support structure may have at least one connecting piece protruding from the support structure and connected to the cavity in a flow-guiding manner. The connecting piece may be configured to connect the blow-molded article to a connection component, so that the blow-molded article can be connected to the connection component in a flow-guiding manner. Preferably, the connecting piece is tubular in shape.

[0029] The connecting piece may have a connecting element for connecting to the connecting component. Preferably, the connecting piece may be connectable to the connecting component by the connecting element in a form-locking or friction-locking manner. For this purpose, the connecting element may preferably be configured as a thread, a bayonet closure, a press-fit thickened section, a clip connection, or a sealing ring profile. This allows for easy assembly.

[0030] Some configurations of the blow-molded article according to the invention and the method according to the invention are explained in more detail below with reference to the drawings, each of which is shown diagrammatically. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a cross-sectional view showing a blow molded article according to the present invention. [Figure 2] FIG. 2 is another cross-sectional view of the blow molded article. [Figure 3] 2 is a cross-sectional view showing a detailed view of the connecting pipe piece of the blow-molded product of FIG. 1 according to the manufacturing method of the present invention. FIG. [Figure 4] 2 shows a support structure inside the preform during production of the blow molded article of FIG. 1.

[0032] FIG. 1 shows a blow-molded article 1 configured as a container. The blow-molded article 1 comprises a base body 5 and a support structure 2 arranged inside the base body 5. The base body 5 and the support structure 2 enclose a cavity 15. The cavity 15 is designed, in particular, to contain a fluid (not shown). In this case, the fluid can be a gas or a liquid, for example a temperature-regulating medium. The base body 5 and the support structure 2 are material-tightly connected. In addition to a material-tight connection, a form-tight connection, produced, for example, by mechanical deformation, is also conceivable as an alternative and / or additional step.

[0033] The support structure 2 has a connecting fitting 7 that protrudes from the support structure 2 and is connected to the cavity 15 in a flow-guiding manner. In particular, fluid is introduced into the blow-molded article 1 and discharged out of the blow-molded article 1 through the connecting fitting 7. The connecting fitting 7 is designed to connect the blow-molded article 1 to a connection component (not shown), so that the blow-molded article 1 can be connected to the connection component in a flow-guiding manner. The connecting fitting 7 is tubular. In this case, the connecting fitting 7 can function as a filling opening or a discharge opening. The connecting fitting 7 can also receive a closure cap with an integrated sensor, in particular a pressure sensor for pressure monitoring.

[0034] The connecting slit 7 includes a connecting element 12 for connection to a connecting component (not shown). The connecting element 12 allows the connecting slit 7 to be connected to the connecting component in a form-locking manner. The connecting element 12 is configured as a thread in this case. Alternatively, it can be configured as a bayonet closure. The connecting element 12 can also be configured as a press-fit thickened section, a clip connection, or a sealing ring molding.

[0035] The substrate 5 and the support structure 2 are made of plastic, and the plastic of the substrate 5 and the plastic of the support structure 2 have the same melting temperature. This allows a material-tight bond to be achieved particularly energy-efficiently and therefore inexpensively. The substrate 5 and the support structure 2 are made of polyolefins, such as polypropylene. Alternatively, other thermoplastic resins or material composites can also be used. The material-tight bond connects the substrate 5 and the support structure 2 firmly and tightly to one another.

[0036] The support structure 2 has on its outer side welding ribs 6, which are materially connected to the base body 5 during blow molding. The welding ribs 6 are arranged on the outer side on the support structure 2 and on the connecting elements 12. During blow molding, the welding ribs 6 are welded to the preform 4. By means of the welding ribs 6, a targeted mechanical reinforcement of the blow molded part 1 can be achieved.

[0037] One of the welding ribs 6 is arranged on the outside of the connecting tube slit 7, so that during blow molding the base body 5 is bonded to the connecting tube slit 7 in a material-tight manner. By means of the welding rib 6 on the connecting tube slit 7, a tight bond between the base body 5 and the connecting tube slit 7 is achieved.

[0038] 2 shows that the support structure 2 of the blow-molded article 1 shown in FIG. 1 has a sensor holder 14. A sensor 16 is arranged in the sensor holder 14, which is arranged and fixed in the blow-molded article 1. In the present example, the sensor 16 is configured as a fill level sensor. Other sensors, in particular a temperature sensor or a pressure sensor, may also be arranged in the sensor holder.

[0039] The blow-molded article 1 shown in Figures 1 and 2 may also be configured as a tube device (not shown). If the blow-molded article 1 is configured as a tube device, the tube device has two tube openings and is used to guide a fluid.

[0040] Figure 3 shows in a detailed view the area of ​​the connecting slit 7 of the blow-molded part 1 of Figure 1 immediately after the blow-molding process. The connecting slit 7 is arranged between two blow-molding tools 9 of the blow-molding mold 3. The connecting slit 7 and the blow-molding mold 3 are only partially illustrated and are therefore shown with broken edges.

[0041] The connecting piece 7 includes an opening 8. After the shaping of the base body 5 from the preform 4 is completed and the material-tight bond between the base body 5 and the support structure 2 is produced, the opening 8 of the connecting piece 7 is covered by a cover area 17 of the base body 5. Therefore, in a subsequent manufacturing step, the material of the base body 5 in the cover area 17 must be removed.

[0042] The blow mold 3 has two blow molding tools 9, between which the support structure 2 and preform 4 are positioned before blow molding. When closed, the blow molding tools 9 of the blow mold 1 abut against the support structure 2 and press the preform 4 so that a separation region 10 is formed in the base body 5 during blow molding. The separation region 10 surrounds a cover region 17, which covers the opening 8 of the connecting fitting 7 after blow molding. The separation region 10 is an intentional structural weakness of the base body 5, so that after the blow molding process, the base body 5 separates at the separation region 10 and the cover region 17 is removed, thereby exposing the opening 8 of the connecting fitting 7. Separation at the separation region 10 can be achieved without the use of a tool, using only a small force, for example by tearing, which further simplifies the production of the blow-molded article 1. However, a tool can also be used to separate the cover region 17, which allows for flash-free separation or separation with very small tolerances.

[0043] Both blow molding tools 9 are equipped with pressing edges 11, which apply linearly with a defined force against the base body 5 during blow molding. This allows particularly easy removal of the cover area 17 after blow molding. The separation area 10 generated by the pressing edges 11 is configured as an annular groove. The pressing edges 11 can also be configured as cutting edges, which result in particularly easy separation of the separation area 10, so that the separation area 10 is already separated when the blow mold 3 is closed.

[0044] The connecting piece 7 has a connecting element 12 for connecting to a connecting component. A protective element 13 is placed in the blow mold 3 before blow molding, so that after blow molding, the protective element 13 is positioned between the connecting element 12 and the substrate 5. The protective element 13 protects the connecting element 12, preventing the preform 4 from pressing against the connecting element 12 and preventing bonding between the connecting element 12 and the substrate 5. After the blow molding process, the substrate 5 is separated at the separation region 10, allowing the cover region 17 to be removed. This exposes the protective element 13, which can then be removed. The protective element 13 is made of a material with a higher melting temperature than the materials of the support structure 2 and the preform 4. This prevents the protective element 13 from bonding to the support structure 2 and / or the preform 4 during blow molding. The protective element 13 is made of polyoxymethylene.

[0045] 4 shows a schematic view of the support structure 2 and preform 4 of the blow-molded article 1 of FIG. 1 during blow molding. The preform 4 is formed in a tubular shape. When the preform 4 is introduced into the blow mold 3, it is placed over the support structure 2, so that the support structure 2 is located inside the preform 4. During blow molding, the preform 4 is applied to the support structure 2 from the outside. The blow mold 3 includes two blow molding tools 9 with cavities, which are movable relative to each other, and when the blow molding tools 9 are closed, the preform 4 is pressed against the edge region of the cavity of the blow molding tools 9.

Claims

1. A method for producing a blow-molded article (1), comprising the steps of: preparing a support structure (2) and placing it in a blow mold (3); introducing a preform (4) into the blow mold (3) so that the support structure (2) is at least partially surrounded by the preform (4); then closing the blow mold (3); and producing a substrate (5) from the preform (4) by blow molding, the substrate (5) surrounding the support structure (2), and bonding the substrate (5) to the support structure (2) in a material- and / or form-locking manner during blow molding.

2. 2. The method according to claim 1, wherein the support structure (2) has on its outer side welding ribs (6), which are materially bonded to the base body (5) during blow molding.

3. 3. The method according to claim 1, wherein the support structure (2) includes at least one connecting tube piece (7) protruding from the support structure (2), and the connecting tube piece (7) has at least one welding rib (6) arranged on its outer side, and the welding rib (6) of the connecting tube piece (7) is material-tightly connected to the base body (5) during blow molding.

4. 4. The method according to claim 3, wherein the connecting piece (7) has an opening (8), the base body (5) is formed by blow molding with a cover area (17) that covers the opening (8), and the opening (8) is made accessible by removing the cover area (17) assigned to the opening (8).

5. 5. The method according to claim 4, wherein the blow mould (3) has at least two blow moulding tools (9), the support structure (2) and the preform (4) are placed between the two blow moulding tools (9) before blow moulding, and the blow moulding tools (9) press the preform (4) against the support structure (2) when the blow mould (3) is closed.

6. 6. The method of claim 5, wherein the blow molding tool (9) presses the preform (4) so ​​that a separation region (10) occurs during blow molding.

7. 7. The method according to claim 6, wherein the blow molding tool (9) is equipped with a press edge (11), which is applied linearly with a preload against the substrate (5) during blow molding.

8. 8. The method according to claim 5, wherein the connecting piece (7) has a connecting element (12) for connecting to a connecting component, and a protective element (13) is arranged in the blow mold (3) before blow molding, so that the protective element (13) is arranged between the connecting element (12) and the base body (5) after blow molding.

9. 9. The method according to any one of claims 1 to 8, wherein the support structure (2) is formed as a rib structure.

10. 10. The method according to any one of claims 1 to 9, wherein the support structure (2) comprises a sensor holder (14).

11. 1. A blow-molded article (1), comprising a base (5) surrounding a hollow space (15) and a support structure (2) disposed inside the base (5), the base (5) and the support structure (2) defining the hollow space (15), the base (5) and the support structure (2) being material-tightly and / or form-tightly connected to each other.

12. 12. The blow-molded article (1) according to claim 11, wherein the support structure (2) has at least one connecting piece (7) protruding from the support structure (2) and connected to the hollow chamber (15) in a flow-guiding manner.

13. 13. The blow-molded article (1) according to claim 12, wherein the connecting piece (7) comprises a connecting element (12) for connection to a connecting component.

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