Method for producing a molded body enclosing a cavity by welding two components and mold for welding two components

Abstract

The invention relates to a method for producing a molded body enclosing a cavity by welding two components (1a, 1b), and also to a mold (5) by means of which the method for producing the molded body can be carried out. The invention also relates to a molded body obtainable by the method according to the invention.

Description

[0001] The present invention relates to a method for welding two components The invention relates to a method for producing a molded body having a closed cavity according to the invention and to a mold (5) with which the method for producing the molded body can be carried out. The invention also relates to a molded body obtainable by the method according to the invention.

[0002] In order to produce complex molded bodies, for example hollow molded bodies, two or more components must be welded to one another. Various methods for this purpose have been described in the prior art.

[0003] EP 1 415 789 describes a mold which is introduced between two plastic parts to be joined and which can heat the areas to be welded of the plastic parts to be joined by using radiant heat and a hot inert gas flow in a contact-free process.

[0004] A disadvantage of the method described in EP 1 415 789 is that the gas discharge orifices are nozzle orifices which provide only local heating of the welding region. It is therefore not possible to achieve uniform heating of the welding region. Instead of uniform heating, local overheating can occur, leading to local degradation of the polymer contained in the plastic part; at the same time, there are welding regions in which the plastic part or the polymer contained therein is not sufficiently melted, resulting in a weakening of the weld formed at these locations. The inhomogeneity of the heating is further increased if the molded body to be welded also exhibits warping. The resulting temperature variations along the welding region lead to different degrees of melting of the polymer; this leads to quality variations along the weld seam.

[0005] WO 2017 / 198483 discloses a method for welding molded bodies, wherein an end region (2a) of a first molded body (1a) is melted by means of a channel (7a) through a device (11a) for introducing hot gases, and wherein a joining surface (2b) of a second molded body (1b) is likewise melted by means of a channel (7b), the channel (7b) comprising a device (11b) for introducing hot gases, and wherein the heated end region (2a) of the first molded body (1a) is connected to the heated joining surface (2b) of the second molded body (1b). The method described in WO 2017 / 198483 results in uniform melting of the joining surface (2a) and the joining surface (2b), so that a uniform weld seam is generally obtained.

[0006] If the method described in WO 2017 / 198483 is used to weld a component having a hole adjacent to which there is a continuous outer surface, the weld obtained is in some cases asymmetrical. In some cases, this can lead to a reduced weld strength.

[0007] The object of the present invention is therefore to provide a method for producing a molded body enclosing a cavity by welding two components, which method does not have the above-mentioned disadvantages of the methods of the prior art, or has them only to a reduced extent. Another object is to allow the method to be carried out as simply as possible and at the lowest possible cost.

[0008] The object is achieved by a method for producing a molded body enclosing a cavity by welding two components (1a, 1b).

[0009] The method comprises steps a), b), c), d) and e):

[0010] a) providing a first component (1a), wherein the first component (1a) comprises a continuously welded web (2a),

[0011] b) providing a mold (5) comprising a continuous channel (7a), wherein the path of the channel (7a) corresponds substantially to the path of the welding web (2a), wherein the channel (7a) comprises means (11a) for introducing hot gases, and wherein the mold (5) comprises means (30a) for actively regulating the pressure,

[0012] c) positioning the welding web (2a) of the first component (1a) in the region of the channel (7a) of the mould (5), thereby forming a first inner space (20a) between the first component (1a) and the mould (5),

[0013] d) introducing hot gas through the channel (7a) to melt the weld web (2a) of the first component (1a) and actively regulating the pressure in the first inner space (20a) by means (30a), and

[0014] e) Bringing the molten welding web (2a) of the first component into contact with the welding web (2b) of the second component (1b), wherein the trajectory of the welding web (2b) substantially corresponds to the trajectory of the welding web (2a).

[0015] Surprisingly, it has been found that with the method according to the invention, a more uniform heating of the welding web (2a) of the first component (1a) can be achieved, thereby improving the quality of the weld. In a preferred embodiment, the above also applies to the welding web (2b) of the second component (1b), which according to a preferred embodiment of the invention can also be heated more uniformly. The better weld quality is due to a more uniform melting of the welding web (2a) and / or the welding web (2b), which results in a particularly uniform weld thickness and a better weld symmetry.

[0016] Furthermore, the method according to the invention can sometimes be carried out faster than the methods described in the prior art, resulting in shorter cycle times than the methods described in the prior art. For the purposes of the present invention, the expression "cycle time" means the period of time from the positioning of the first component (1a) and the second component (1b) in step c) to the production of the molded body with the closed cavity in step e).

[0017] The present invention is explained in more detail below.

[0018] Step a)

[0019] In step a), a first component (1a) is provided.

[0020] According to the invention, the first component (1a) comprises a continuous welded web (2a). In a preferred embodiment, the first component (1a) comprises a hole defined by the welded web (2a). In a preferred embodiment, a substantially continuous outer surface (3a) is adjacent to the welded web (2a). The outer surface (3a) externally defines the component (1a).

[0021] According to the invention, the expression "substantially continuous" means that the outer surface (3a) has a hole area of ​​less than 10%, preferably less than 5% and particularly preferably less than 2.5%, based on the total area of ​​the outer surface (3a). In a particularly preferred embodiment, the outer surface (3a) has no holes. The first inner space (20a) of the first component (1a) is defined by the area between the inner surface (4a) of the first component (1a) and the area enclosed by the welding web (2a). Figure 3a A plan view of a hemispherical component (1a) with a welding web (2a) is shown by way of example. The welding web (2a) defines the end region of the first component (1a).

[0022] The welding web (2a) can be designed in any shape known to those skilled in the art. For example, the welding web (2a) can be designed in a flat shape, a ridge shape, a step shape or a rib shape. In a preferred embodiment, the welding web (2a) is designed in a rib shape, wherein the rib has a rectangular cross section. The width of the welding web (2a) is generally 0.5 to 16 mm, preferably 1 to 10 mm and particularly preferably 2 to 8 mm.

[0023] If the width of the end region of the first component (1a) is 1 to 6 mm, the end region of the first component (1a) itself can form the welding web (2a). Figure (3b) shows a perspective view of a hemispherical component (1a) by way of example, in which the end region of the component (1a) forms the welding web (2a).

[0024] In a preferred embodiment, the welding web (2a) comprises a first thermoplastic polymer.

[0025] For the purposes of the present invention, the expression "first thermoplastic polymer" means exactly one first thermoplastic polymer or a mixture of two or more first thermoplastic polymers.

[0026] Any thermoplastic polymer known to the skilled person is suitable as the first thermoplastic polymer.The first thermoplastic polymer is preferably selected from amorphous thermoplastic polymers and semi-crystalline thermoplastic polymers.

[0027] Thus, the first thermoplastic polymer is, for example, selected from polyamide, polyoxymethylene, polyphthalamide (PPA), polysulfone (PSU), polyethersulfone (PESU), polyphenylsulfone (PPSU), polyethylene terephthalate and polybutylene terephthalate.

[0028] Therefore, the present invention also provides a method, wherein the first thermoplastic polymer contained in the welding web (2a) is selected from polyamide, polyoxymethylene, polyphthalamide (PPA), polysulfone (PSU), polyethersulfone (PESU), polyphenylsulfone (PPSU), polyethylene terephthalate and polybutylene terephthalate.

[0029] The first thermoplastic polymer generally has a glass transition temperature (T G1 For example, the glass transition temperature (T G1 ) is from 50 to 350° C., preferably from 150 to 270° C., particularly preferably from 170 to 240° C., as determined by differential scanning calorimetry (DSC).

[0030] Therefore, the present invention also provides a method, wherein the first thermoplastic polymer has a glass transition temperature (T G1 ).

[0031] If the first thermoplastic polymer is a semi-crystalline thermoplastic polymer, the first thermoplastic polymer also typically has a melting point (T M1 For example, the melting point (T M1 ) is from 80 to 400° C., preferably from 140 to 320° C., particularly preferably from 160 to 300° C., as determined by differential scanning calorimetry (DSC).

[0032] Therefore, the present invention also provides a method, wherein if the first thermoplastic polymer is a semi-crystalline thermoplastic polymer, the melting point (T M1 ) is 80 to 400°C.

[0033] The welding web (2a) of the first component (1a) may not only comprise the first thermoplastic polymer but also further components which are known to the person skilled in the art and are selected, for example, from fillers and additives.

[0034] Materials suitable as fillers are any fillers known to the person skilled in the art for thermoplastic polymers. Such fillers are selected, for example, from glass spheres, glass fibers, carbon fibers, carbon nanotubes and chalk.

[0035] Suitable additives are likewise known to the person skilled in the art and are selected, for example, from antinucleating agents, stabilizers, end-group functionalizing agents and dyes.

[0036] Preferably, the first component (1a) contains a first thermoplastic polymer. Particularly preferably, the first component (1a) comprises the same components as the welding web (2a). Therefore, if the welding web (2a) comprises not only the first thermoplastic polymer but also further components, it is preferred that the first component (1a) also comprises not only the first thermoplastic polymer but also further components.

[0037] The first component (1a) can have any shape known to a person skilled in the art. The first component (1a) preferably has a shape that complies with the above-mentioned conditions preferred according to the invention. The molded body preferably has the shape of a shell or box, wherein the shape defined by the trajectory of the welding web (2a) and the shapes of the outer surface (3a) and the inner surface (4a) can have a complex shape of the type required, for example, in automobile construction.

[0038] In a preferred embodiment, a second component (1b) is also provided in step a), wherein the second component (1b) comprises a continuous welded web (2b). The description and preferred embodiments provided above regarding the first component (1a) are correspondingly applicable to the second component (1b).

[0039] Therefore, the present invention provides a method, wherein step a) further comprises providing a second component (1b), wherein the second component (1b) comprises a continuous welded web (2b).

[0040] Providing the first component (1a) and the second component (2b) may be achieved by any method known to a person skilled in the art, for example by injection moulding, extrusion or blow moulding. Figures 5a to 5d The end region of the first component (1a) is shown as an example. The end region of the second component (1b) can have a corresponding shape. It goes without saying that when Figures 5a to 5d When the first component (1a) is welded to the second component (1b), the trajectory of the welding web (2b) of the second component (1b) is preferably a mirror image of the trajectory of the welding web (2a) of the first component (1a).

[0041] For the purposes of the present invention, the expressions "welding web (2a) of the first component (1a)" and "welding web (2a)" are used synonymously and therefore have the same meaning. The same also applies to the expressions "welding web (2b) of the second component (1b)" and "welding web (2b)". For the purposes of this document, these expressions are likewise used synonymously and therefore likewise have the same meaning.

[0042] Furthermore, it goes without saying that the welding web (2a) and the welding web (2b) are different welding webs. In a preferred embodiment, the welding web (2a) and the welding web (2b) have substantially identical trajectories, so that the two welding webs (2a; 2b) can be welded in method step e) to form a weld seam.

[0043] The above also applies accordingly to the expressions "outer surface (3a) of the first component (1a)" and "outer surface (3a)". For the purposes of this document, these expressions are used synonymously and therefore also have the same meaning. For the purposes of the present invention, the expressions "outer surface (3b) of the second component (1b)" and "outer surface (3b)" are also used synonymously and therefore have the same meaning.

[0044] Furthermore, for the purpose of the present invention, the expressions "inner surface (4a) of the first component (1a)" and "inner surface (4a)" are used synonymously. Therefore, these expressions also have the same meaning. Furthermore, for the purpose of the present invention, the expressions "inner surface (4b) of the second component (1b)" and "inner surface (4b)" are used synonymously. Therefore, these expressions also have the same meaning.

[0045] Step b)

[0046] In step b), a mould (5) is provided.

[0047] In a preferred embodiment, the mold (5) provided in step b) comprises a first side (6a) and a second side (6b), wherein the channel (7a) is arranged on the first side (6a) and wherein the continuous channel (7b) is arranged on the second side (6b), wherein the channel (7b) comprises a device (11b) for introducing hot gas and wherein the device (30b) for actively regulating the pressure is arranged on the second side (6b).

[0048] Therefore, the present invention provides a method, wherein the mold (5) provided in step b) comprises a first side (6a) and a second side (6b), wherein the channel (7a) is arranged on the first side (6a) and wherein the continuous channel (7b) is arranged on the second side (6b), wherein the channel (7b) comprises a device (11b) for introducing hot gas and wherein the device (30b) for actively regulating the pressure is arranged on the second side (6b).

[0049] Figure 1 and Figure 2 A cross section of a mold (5) is shown by way of example, on which a first welding body (1a) or a first component (1a) and a second component (1b) are positioned.

[0050] Suitable means as means (11a) for introducing hot gas into the channel (7a) are any means (11a) known to the person skilled in the art and suitable for introducing gas, such as nozzles, holes and / or slots. The same applies to means (11b).

[0051] Furthermore, the mold (5) comprises a device (30a) for actively regulating the pressure. Suitable devices (30a) as devices (30a) are any devices known to a person skilled in the art and which can be used for actively regulating the pressure. Suitable devices (30a) for actively regulating the pressure are, for example, pumps which can convey gas. Suitable pumps are, for example, vacuum pumps or ejectors or compressors. A vacuum pump or ejector can be used to reduce the pressure; a compressor can be used to increase the pressure. The above description of the device (30a) applies accordingly to the device (30b).

[0052] In a preferred embodiment, the device (30a) is positioned in the area surrounded by the trajectory of the channel (7a).Preferably, the device (30a) on the first side (6a) of the mold (5) is positioned in the area surrounded by the trajectory of the channel (7a).

[0053] Thus, the present invention provides a method wherein the device (30a) is positioned in the area enclosed by the trajectory of the channel (7a).

[0054] In a preferred embodiment, the device (30b) is positioned in a region surrounded by the trajectory of the channel (7b). In another preferred embodiment, the device (30b) on the second side (6b) of the mold (5) is positioned in a region surrounded by the channel (7b).

[0055] In a preferred embodiment, the path of the channel (7a) corresponds substantially to the path of the welding web (2a). This means that in the projection of the path of the welding web (2a) onto the mold (5), preferably onto the first side (6a) of the mold (5), at least 80% of the projected area of ​​the welding web (2a) is within the channel (7a). At least 90% of the projected area of ​​the welding web (2a), particularly preferably at least 95% of the projected area, is located within the path of the channel (7a), and most preferably the projection of the welding web (2a) is entirely located within the channel (7a).

[0056] In another preferred embodiment, the area of ​​the channel (7a) is therefore preferably larger than the area of ​​the trajectory of the welding web (2a) (based on the end face of the welding web (2a)). In this embodiment, the welding web (2a) can be introduced into the channel (7a).

[0057] The above description and preferred embodiments apply accordingly to the trajectory of the welding web (2b) and also to the trajectory of the channel (7b).

[0058] In a particularly preferred embodiment, the device (30a) comprises a hole in the mould (5); a vacuum pump and / or a compressor can be connected to the mould (5) through said hole. The same applies to the device (30b).

[0059] For the purposes of the present invention, the expressions "first side (6a) of the mold (5)" and "first side (6a)" are used synonymously and therefore have the same meaning. The same also applies to the expressions "second side (6b) of the mold (5)" and "second side (6b)". For the purposes of the present invention, these expressions are likewise used synonymously and therefore likewise have the same meaning.

[0060] Furthermore, it goes without saying that the first side (6a) and the second side (6b) are different sides of the mold (5). Preferably, the first side (6a) and the second side (6b) are located on opposite sides of the mold (5).

[0061] It goes without saying that channel (7a) and channel (7b) are different channels. The same applies to the device for introducing hot gases (11a) and the device for introducing hot gases (11b). These are also different devices. For the purposes of the present invention, moreover, the expressions "device for introducing hot gases (11a)" and "device 11 (a)" are used synonymously and therefore have the same meaning. The same applies to the expressions "device for introducing hot gases (11b)" and "device (11b)". These expressions are also used synonymously and have the same meaning for the purposes of the present invention.

[0062] Furthermore, it goes without saying that the channel inlet plane (14a) and the channel inlet plane (14b) are different channel inlet planes. The same applies to the device for actively regulating pressure (30a) and the device for actively regulating pressure (30b). These are different devices for actively regulating pressure.

[0063] Furthermore, for the purposes of the present invention, the expressions "device (30a) for actively regulating pressure" and "device (30a)" are used synonymously and therefore have the same meaning. The same applies to the expressions "device (30b) for actively regulating pressure" and "device (30b)". For the purposes of the present invention, these expressions are also used synonymously and therefore have the same meaning.

[0064] The channel (7a) is preferably arranged on the first side (6a) of the mold (5). Furthermore, the channel (7a) arranged on the first side (6a) of the mold (5) preferably comprises means (11a) for introducing hot gases. The channel (7b) is preferably arranged on the second side (6b) of the mold (5). Furthermore, the channel (7b) arranged on the second side (6b) of the mold (5) preferably has means (11b) for introducing hot gases.

[0065] Hot gases are introduced by means (11a) and (11b). The means (11a) and (11b) are suitable for heating the welding webs (2a; 2b) in order to subsequently weld them in step e), preferably to form a weld. The means (11a; 11b) for introducing hot gases are different from the means (30a; 30b) for actively regulating the pressure. The means (30a; 30b) for actively regulating the pressure are not suitable for melting the welding webs (2a; 2b).

[0066] Step c)

[0067] In step c), the welding web ( 2a ) of the first component ( 1a ) is positioned in the region of the channel ( 7a ) of the mold ( 5 ).

[0068] As in Figure 1 and 2 As exemplarily depicted in FIG, a first internal space (20a) is formed between the first component (1a) and the mold (5). Preferably, the first internal space (20a) is formed between the first component (1a) and the first side (6a) of the mold (5). In a preferred embodiment of step c), the welding web (2b) of the second component (1b) is additionally positioned in the region of the channel (7b) of the mold (5), thereby forming a second internal space (20b) between the second component (1b) and the mold (5). Preferably, the second internal space (20b) is formed between the second side (6b) of the mold (5) and the second component (1b).

[0069] Therefore, the present invention provides a method, wherein step c) also includes positioning the welding web (2b) of the second component (1b) in the area of ​​the channel (7b) of the mold (5), thereby forming a second internal space (20b) between the second component (1b) and the mold (5), and step d) further includes introducing hot gas through the channel (7b) to melt the welding web (2b) of the second component, and actively adjusting the pressure in the second internal space (20b) by means of a device (30b).

[0070] In a preferred embodiment, in step c), the welding web (2a) is positioned in the region of the channel (7a), wherein the distance (Xa) between the end face of the welding web (2a) facing the mold (5) and the channel inlet plane (14a) is >0 to 3 mm outside the channel (7a) or 0 to 10 mm inside the channel (7a). Preferably, the distance (Xa) is 0.5 to 8 mm inside the channel. It goes without saying that the distance (Xa) inside the channel (7a) is always smaller than the channel depth of the channel (7a). If the distance (Xa) is >0 to 3 mm outside the channel (7a), the position of the welding web (2a) is outside the channel region.

[0071] In another preferred embodiment, in step c), the welding web (2b) is positioned in the region of the channel (7b), wherein the distance (Xb) between the end face of the welding web (2b) facing the mold (5) and the channel inlet plane (14) is >0 to 3 mm outside the channel (7b) or 0 to 10 mm inside the channel (7b). Preferably, the distance (Xb) is 0.5 to 8 mm inside the channel (7b).

[0072] Furthermore, the descriptions and preferred solutions provided above regarding the positioning of the welding web ( 2 b ) apply correspondingly to the positioning of the welding web ( 2 b ) in step c).

[0073] Therefore, the present invention provides a method, wherein in step c), the welding web (2a) is positioned in the area of ​​the channel (7a), wherein the distance (Xa) between the end face of the welding web (2a) facing the mold (5) and the channel inlet plane (14a) is >0 to 3 mm outside the channel (7a) or 0 to 10 mm inside the channel (7a).

[0074] Therefore, the present invention provides a method, wherein in step c), the welding web (2b) is positioned in the area of ​​the channel (7b), wherein the distance (Xb) between the end face of the welding web (2b) facing the mold (5) and the channel inlet plane (14b) is >0 to 3 mm outside the channel (7b) or 0 to 10 mm inside the channel (7b).

[0075] The welding webs (2a, 2b) are preferably positioned in the region of the channels (7a, 7b) Figure 6a and 6b This is shown by way of example. Figure 6a In FIG. 1 , the end face of the welding web (2a) is positioned in the channel (7a). The distance (Xa) between the end face of the welding web (2a) and the channel inlet plane (14a) is also depicted. Figure 6b In the embodiment, the end face of the welding web (2a) is located outside the channel (7a), and therefore above the channel inlet plane (14a).

[0076] Step d)

[0077] In step d), hot gas is introduced into the channel (7a) by means (11a). In this step, the welding web (2a) of the first component (1a) is heated and the first thermoplastic polymer contained in the welding web (2a) is melted.

[0078] For the purposes of the present invention, the expression "hot gas" means either exactly one hot gas or a mixture of two or more hot gases.

[0079] It goes without saying that in step d) the area surrounding the welding web (2a) can also be heated. This is particularly true when the welding web (2a) is designed in a linear, ridge-like or rib-like manner.

[0080] In this embodiment, it is preferred that the first component (1a) comprises a first thermoplastic polymer and then the first thermoplastic polymer contained in the region around the welding web (2a) is also melted.

[0081] The hot gas may be introduced into the means (11a) for introducing gas into the channel (7a) by any method known to a person skilled in the art.

[0082] Gases suitable as hot gases are any gases known to those skilled in the art. Such gases are, for example, selected from CO2, N2 and air.

[0083] Therefore, the present invention also provides a process, wherein the hot gas introduced in step d) is selected from CO2, N2 and air.

[0084] For the purposes of the present invention, the term "air" means the gaseous mixture of the Earth's atmosphere. This is known to those skilled in the art.

[0085] The hot gas can be heated by any method known to those skilled in the art. For example, it can be heated by a heat exchanger. In addition, for example, if the hot gas is CO2, the hot gas is generated on-site by burning hydrocarbons and is therefore hot.

[0086] The temperature of the hot gas is, for example, 100 to 600°C, preferably 250 to 500°C, and particularly preferably 300 to 500°C.

[0087] Therefore, the present invention also provides a process wherein the temperature of the hot gas introduced in step d) is from 100°C to 600°C.

[0088] It goes without saying that the temperature of the hot gas introduced in step d) is based on the temperature of the hot gas at the outlet of the means ( 11 a ) for introducing gas into the channel ( 7 a ), ie on the temperature of the hot gas in the channel ( 7 a ).

[0089] In step d), the welding web (2a) of the first component (1a) can be heated to any desired temperature (T 1a ). The temperature (T 1a ) is generally below the decomposition temperature of the first thermoplastic polymer contained in the welding web (2a). If the first thermoplastic polymer is an amorphous thermoplastic polymer, the welding web (2a) of the first component (1a) is preferably heated to a temperature (T 1a ) is higher than the glass transition temperature (T G1 ), and if the first thermoplastic polymer is a semi-crystalline thermoplastic polymer, higher than the melting point (T M1 ).

[0090] Therefore, the present invention also provides a method, wherein in step d), if the first thermoplastic polymer is an amorphous thermoplastic polymer, the temperature of the welding web (2a) of the first component (1a) is increased to a temperature (T 1a ) is higher than the glass transition temperature (T G1 ), and if the first thermoplastic polymer is a semi-crystalline thermoplastic polymer, higher than the melting point (T M1 ).

[0091] For example, if the first thermoplastic polymer is an amorphous thermoplastic polymer, the temperature of the welding web (2a) of the first component (1a) is raised to a temperature (T 1a ) is lower than the glass transition temperature (T G1 ) is 0 to 300° C., preferably 30 to 250° C., particularly preferably 60 to 200° C., and if the first thermoplastic polymer is a semi-crystalline thermoplastic polymer, is higher than the melting point (T M1) is from 0 to 300°C, preferably from 30 to 250°C and particularly preferably from 60 to 200°C.

[0092] Therefore, the present invention also provides a method, wherein in step d), if the first thermoplastic polymer is an amorphous thermoplastic polymer, the temperature of the welding web (2a) of the first component (1a) is increased to a temperature (T 1a ) is lower than the glass transition temperature (T G1 ) is 0 to 300°C higher than the melting point (T M1 )0 to 300℃.

[0093] For example, the temperature of the welding web (2a) of the first component (1a) is increased to a temperature (T 1a ).

[0094] Therefore, the present invention also provides a method, wherein in step d), the temperature of the welding web (2a) of the first component (1a) is increased to a temperature (T 1a ).

[0095] The first thermoplastic polymer is melted or softened in step d).

[0096] For the purposes of the present invention, the expression "melt or soften" in relation to the first thermoplastic polymer and in relation to the second thermoplastic polymer means that the first thermoplastic polymer or the second thermoplastic polymer is plastically deformable, preferably flowable.

[0097] The pressure in the first inner space (20a) is actively regulated in step d) by means (30a). The active regulation of the pressure can be carried out during the entire period of step d). In other words, this means that the active regulation of the pressure is carried out while the hot gas is introduced through the channel (7a). In this embodiment, the active regulation of the pressure is carried out as long as the hot gas is introduced through the channel (7a). This embodiment is preferred.

[0098] Furthermore, during the entire period of the introduction of hot gas through the channel (7a), no active pressure regulation is performed. Thus, for example, the hot gas can be initially introduced through the channel (7a), and then the active pressure regulation can be started after a certain time delay (i.e., after the start of the introduction of the hot gas).

[0099] In a preferred embodiment, the gas is discharged from the first interior space (20a) and / or the second interior space (20b) by means (30a) and / or means (30b). The gas is preferably actively discharged by pumping or suction. This is preferably carried out during step d).

[0100] In another preferred embodiment, the gas is introduced into the first interior space (20a) and / or the second interior space (20b) by means (30a) and / or means (30b). Preferably, the gas is actively introduced into the space by injection or pumping. This is preferably carried out during method step d).

[0101] During method step d), hot gas is introduced through the channel (7a). Without the active pressure regulation of the present invention, this results in the internal pressure (pI) in the first internal space (20a) being higher than the external pressure (pA). Since the internal pressure (pI) is higher than the external pressure (pA), the amount of hot gas flowing through the side of the welding web (2a) facing away from the first internal space (20a) without active pressure regulation during method step d) is greater than the amount flowing through the side of the welding web (2a) facing the first internal space (20a). Therefore, the side of the welding web (2a) facing away from the first internal space (20a) is heated to a greater extent than the side of the welding web (2a) facing the first internal space (20a). The above also applies to the heating of the second welding web (2b) accordingly.

[0102] Without the pressure regulation according to the invention, in method step e), when the welding webs (2a), (2b) come into contact, the different degrees of melting lead to an asymmetric weld. In method step d), an asymmetric weld is obtained if the internal pressure (pI) in the first interior space (20a) is greater than the external pressure (pA). In method step d), the higher internal pressure (pI) produces a weld that is bent outwards relative to the first interior space (20a).

[0103] According to the invention, due to the active pressure regulation by the device (30a), method step d) can and preferably is carried out in such a way that the internal pressure (pI) and the external pressure (pA) in the first internal space (30a) are substantially balanced. Preferably, the pressure difference between the internal pressure (pI) and the external pressure (pA) is at most 50%, preferably at most 30%, more preferably at most 10%, particularly preferably at most 5%. Thus, a pressure difference of at most 50% is obtained. Figure 7 and Figure 8 Symmetrical weld type depicted as an example in FIG.

[0104] In one embodiment, therefore, the internal pressure (pI) is at most 50%, preferably at most 30%, more preferably at most 10% and particularly preferably at most 5% higher than the external pressure (pA).

[0105] In a further preferred embodiment, the maximum extent to which the internal pressure (pI) is lower than the external pressure (pA) is at most 50%, preferably at most 30%, more preferably at most 10%, particularly preferably at most 5%.

[0106] Due to the active pressure control, according to the invention, it is possible to actively influence the symmetry of the weld seam.

[0107] In a preferred embodiment, the pressure is actively adjusted in such a way that a symmetrical weld seam is produced.

[0108] Therefore, the present invention provides a method, wherein gas is exhausted from the first interior space (20a) and / or the second interior space (20b) by means of a device (30a) and / or a device (30b).

[0109] In another embodiment, the symmetry of the weld seam can be controlled by actively increasing the internal pressure (pI) relative to the external pressure (pA) in such a way that the weld seam has a weld bead on the side facing away from the first interior space (20a). For this purpose, in method step d), the internal pressure (pI) is preferably adjusted to be at least 10%, preferably at least 30%, and particularly preferably at least 50% higher than the external pressure.

[0110] Therefore, the present invention provides a method, wherein the gas is introduced into the first inner space (20a) and / or the second inner space (20b) by means of the device (30a) and / or the device (30b).

[0111] In another embodiment, the symmetry of the weld seam is controlled in such a way that it has a weld bead on the side facing the first interior space (20a). To this end, in method step d), the internal pressure (pI) is preferably adjusted to be at least 10%, preferably at least 30%, and particularly preferably at least 50% lower than the external pressure.

[0112] The description and preferred scheme provided above regarding the melting of the welding web (2a) and the active regulation of the pressure in the first internal space (20a) by the device (30a) are correspondingly applicable to a preferred embodiment according to the present invention, wherein in step d), the welding web (2b) of the second component (1b) is also melted, wherein the pressure in the second internal space (20b) is actively regulated by the device (30b).

[0113] Step e)

[0114] In step e), the molten welding web (2a) of the first component (1a) is brought into contact with the welding web (2b) of the second component (1b), wherein the trajectory of the welding web (2b) substantially corresponds to the trajectory of the welding web (2a). In a preferred embodiment, the trajectory of the welding web (2b) is a mirror image of the trajectory of the welding web (2a).

[0115] Herein, the expression "contact" means physical contact of the heated welding web (2a) of the first component (1a) and the heated welding web (2b) of the second component (1b).

[0116] The heated welding web (2a) of the first component (1a) can be brought into contact with the heated welding web (2b) of the second component (1b) under pressure so that the heated welding web (2a) of the first component (1a) and the heated welding web (2b) of the second component (1b) are pressed against each other. Methods for this purpose are known to those skilled in the art.

[0117] For example, the pressure at which the heated welding web (2a) of the first component (1a) contacts the welding web (2b) of the second component (1b) is 0.1 to 10 MPa, preferably 0.5 to 6 MPa.

[0118] Bringing a heated welding web (2a) into contact with a heated welding web (2b) results in the thermoplastic polymer contained in the welding webs (2a, 2b) being joined. After the heated welding webs (2a, 2b) have been brought into contact, they are cooled, thereby producing a welded joint product. The expressions "heated welding webs (2a, 2b)" and "molten welding webs (2a, 2b)" and "softened welding webs (2a, 2b)" are used synonymously herein.

[0119] In step e), the cooling of the heated weld web (2a) of the first component (1a) and the heated weld web (2b) of the second component (1b) can be achieved by any method known to those skilled in the art. For example, cooling can be achieved in air.

[0120] In step e), a weld is formed between the first component (1a) and the second component (1b). The weld is located in the area where the welding web (2a) of the first component (1a) and the welding web (2b) of the second component (1b) originally existed.

[0121] Weld seams are known to those skilled in the art.

[0122] The thickness of the weld between the first component (1a) and the second component (1b) is, for example, 20 to 1000 μm, preferably 30 to 400 μm, most preferably 30 to 300 μm, as determined by micrographs.

[0123] Therefore, the present invention also provides a method, wherein the thickness of the weld formed between the first component (1a) and the second component (1b) in step e) is 20 to 1000 μm.

[0124] Thus, a molded body enclosing a cavity is obtained in step e). Such a molded body has a particularly uniform weld seam and good mechanical properties. The cavity is formed by a first interior space (20a) and a second interior space (20b).

[0125] The invention therefore provides a molded body enclosing a cavity, obtainable by the method of the invention, wherein the difference between the internal pressure (pI) and the external pressure (pA) in the first and second interior spaces (20a; 20b) is at most 5%.

[0126] Mould(5)

[0127] The present invention also provides a mold (5) provided in method step b). The above description and preferred embodiments of the method also apply to the mold (5) accordingly.

[0128] According to the present invention, a mold (5) is preferably used for welding two components (1a, 1b), which comprises a continuous channel (7a), wherein the channel (7a) comprises a device (11a) for introducing hot gases, and wherein a welding web (2a) of the first component (1a) can be positioned in the area of ​​the channel (7a), wherein the trajectory of the welding web (2a) substantially corresponds to the trajectory of the channel (7a), wherein a first inner space (20a) can be formed between the first component (1a) and the mold (5), and wherein the mold (5) comprises a device (30a) for actively adjusting the pressure.

[0129] The present invention therefore provides a mould (5) for welding two components (1a, 1b), comprising a continuous channel (7a), wherein the channel (7a) comprises a device (11a) for introducing hot gases, and wherein a welding web (2a) of the first component (1a) can be positioned in the region of the channel (7a), wherein the trajectory of the welding web (2a) substantially corresponds to the trajectory of the channel (7a), wherein a first inner space (20a) can be formed between the first component (1a) and the mould (5), and wherein the mould (5) comprises a device (30a) for actively regulating the pressure.

[0130] In a particularly preferred embodiment, the device ( 30 a ) for actively regulating the pressure is located in the region enclosed by the trajectory of the channel ( 7 a ).

[0131] The invention therefore provides a mould (5) in which the device (30a) is located in the area enclosed by the trajectory of the channel (7a).

[0132] Particularly preferred is a mold (5) comprising a first side (6a) and a second side (6b), wherein the channel (7a) is arranged on the first side (6a), and wherein the mold (5) comprises a continuous channel (7b), wherein the channel (7b) comprises a device (11b) for introducing hot gases, and wherein the welding web (2b) of the second component (1b) can be positioned in the area of ​​the channel (7b), wherein the trajectory of the welding web (2b) substantially corresponds to the trajectory of the channel (7b), wherein a second inner space (20b) can be formed between the second component (1b) and the mold (5), and wherein the mold (5) comprises a device (30b) for actively adjusting the pressure, and wherein the channel (7b) is arranged on the second side (6b) of the mold (5).

[0133] Therefore, the present invention provides a mold (5) comprising a first side (6a) and a second side (6b), wherein a channel (7a) is arranged on the first side (6a), and wherein the mold (5) comprises a continuous channel (7b), wherein the channel (7b) comprises a device (11b) for introducing hot gas, and wherein a welding web (2b) of a second component (1b) can be positioned in the area of ​​the channel (7b), wherein the trajectory of the welding web (2b) substantially corresponds to the trajectory of the channel (7b), wherein a second inner space (20b) can be formed between the second component (1b) and the mold (5), and wherein the mold (5) comprises a device (30b) for actively adjusting the pressure, and wherein the channel (7b) is arranged on the second side (6b) of the mold (5).

[0134] Particularly preferred is a mold (5) in which the device (30b) is positioned in the area enclosed by the trajectory of the channel (7b).

[0135] The invention therefore provides a mould (5) in which the device (30b) is located in the area enclosed by the trajectory of the channel (7b).

[0136] Therefore, the present invention provides a method, wherein the device (30a) is positioned in the first component (1a) and / or the device (30b) is positioned in the second component (1b).

[0137] Reference numerals list

[0138] 1a First Component

[0139] 1b Second component

[0140] 2a Welded web of first component 1a

[0141] 2b Welded web of second component 1b

[0142] 3a The outer surface of the first component 1a

[0143] 3b The outer surface of the second component 1b

[0144] 4a Inner surface of the first component 1a

[0145] 4b Inner surface of the second component 1b

[0146] 5. Mould

[0147] 6a First side of mold 5

[0148] 6b The second side of the mold 5

[0149] Channel 7a

[0150] Channel 7b

[0151] 11a Device for introducing hot gases

[0152] 11b Device for introducing hot gases

[0153] 14a Channel entrance plane

[0154] 14b Channel entrance plane

[0155] 20a First interior space

[0156] 20b Second internal space

[0157] 30a Device for active pressure regulation

[0158] 30b Device for active pressure regulation

[0159] Xa distance

Claims

1. A method for producing a molded body enclosing a cavity by welding two components (1a, 1b), The method comprises steps a), b), c), d) and e): a) providing a first component (1a), wherein the first component (1a) comprises a continuous welded web (2a), b) providing a mould (5) comprising a continuous channel (7a), wherein the trajectory of the channel (7a) corresponds to the trajectory of the welding web (2a), wherein the channel (7a) comprises means (11a) for introducing hot gases, and wherein the mould (5) comprises means (30a) for actively regulating the pressure, c) positioning the welding web (2a) of the first component (1a) in the region of the channel (7a) of the mould (5), thereby forming a first inner space (20a) between the first component (1a) and the mould (5), d) introducing hot gas through the channel (7a) to melt the weld web (2a) of the first component (1a) and actively regulating the pressure in the first inner space (20a) by means (30a), and e) bringing the molten welding web (2a) of the first component into contact with the welding web (2b) of the second component (1b), wherein the trajectory of the welding web (2b) corresponds to the trajectory of the welding web (2a).

2. A method according to claim 1, wherein the device (30a) is located in a region enclosed by the trajectory of the channel (7a).

3. The method according to claim 1 or 2, wherein step a) further comprises providing a second component (1b), wherein the second component (1b) comprises a continuous welded web (2b).

4. A method according to claim 1 or 2, wherein the mold (5) provided in step b) comprises a first side (6a) and a second side (6b), wherein the channel (7a) is arranged on the first side (6a), and wherein a continuous channel (7b) is arranged on the second side (6b), wherein the channel (7b) comprises a device (11b) for introducing hot gas, and wherein the device (30b) for actively regulating the pressure is arranged on the second side (6b).

5. A method according to claim 1 or 2, wherein step c) also includes positioning the welding web (2b) of the second component (1b) in the area of ​​the channel (7b) of the mold (5), thereby forming a second internal space (20b) between the second component (1b) and the mold (5), and step d) also includes introducing hot gas through the channel (7b) to melt the welding web (2b) of the second component (1b), and actively adjusting the pressure in the second internal space (20b) by the device (30b).

6. The method according to claim 1 or 2, wherein gas is exhausted from the first interior space (20a) and / or the second interior space (20b) by means of the device (30a) and / or the device (30b).

7. The method according to claim 1 or 2, wherein the gas is introduced into the first inner space (20a) and / or the second inner space (20b) by means of the device (30a) and / or the device (30b).

8. The method according to claim 1 or 2, wherein in step c), the welding web (2a) is located in the region of the channel (7a), wherein the distance (Xa) between the end face of the welding web (2a) facing the mold (5) and the channel inlet plane (14a) is >0 to 3 mm outside the channel (7a) or 0 to 10 mm inside the channel (7a).

9. The method according to claim 1 or 2, wherein in step c), the welding web (2b) is located in the area of ​​the channel (7b), wherein the distance (Xb) between the end surface of the welding web (2b) facing the mold (5) and the channel inlet plane (14b) is >0 to 3 mm outside the channel (7b) or 0 to 10 mm inside the channel (7b).

10. The method according to claim 1, wherein the device (30a) is located in the first component (1a) and / or the device (30b) is located in the second component (1b).

11. A molded body enclosed with a cavity, obtainable by a method according to any one of claims 5 to 9, wherein the difference between the internal pressure (pI) and the external pressure (pA) in the first and second interior spaces (20a; 20b) is at most 5%.

12. A mould (5) for welding two components (1a, 1b), the mould comprising a continuous channel (7a), wherein the channel (7a) comprises a device (11a) for introducing hot gas, and wherein a welding web (2a) of the first component (1a) can be positioned in the region of the channel (7a), wherein the trajectory of the welding web (2a) corresponds to the trajectory of the channel (7a), wherein a first inner space (20a) can be formed between the first component (1a) and the mould (5), and wherein the mould (5) comprises a device (30a) for actively regulating the pressure.

13. Mould (5) according to claim 12, wherein said means (30a) are positioned in the area surrounded by the trajectory of said channel (7a).

14. A mould (5) according to claim 12 or 13, wherein the mould comprises a first side (6a) and a second side (6b), wherein the channel (7a) is arranged on the first side (6a), and wherein the mould (5) comprises a continuous channel (7b), wherein the channel (7b) comprises a device (11b) for introducing hot gas, and wherein a welding web (2b) of a second component (1b) can be positioned in the region of the channel (7b), wherein the trajectory of the welding web (2b) corresponds to the trajectory of the channel (7b), wherein a second internal space (20b) can be formed between the second component (1b) and the mould (5), wherein the mould (5) comprises a device (30b) for actively adjusting the pressure, and wherein the channel (7b) is arranged on the second side (6b) of the mould (5).

15. Mould (5) according to claim 14, wherein said means (30b) are positioned in the area surrounded by the trajectory of said channel (7b).

Images