Venting device for a primary-shaping tool and method for cleaning a venting device

Abstract

The invention relates to a venting device for a primary-shaping tool (2) which has a cavity, wherein the venting device (1) comprises a venting section (5) in which a vent channel (4) is provided, wherein the venting section (5) comprises at least one gas-permeable region (5.1) which is designed to allow gas present in the primary-shaping tool (2) to escape into the vent channel (4) in an outflow direction (AR), while forming a barrier to a material to be shaped in the primary-shaping tool (2), wherein a heating device (6) is provided which is thermally coupled to the venting section (5), wherein the heating device (6) is designed to heat at least the gas-permeable region (5.1) of the venting section (5) to a temperature of at least 300°C and thereby cause a decomposition process.

Description

[0001] Deggendorf Institute of Technology, March 16, 2026, representing the Free State of Bavaria

[0002] Non-profit KIMW Research GmbH THD005PWO

[0003] Venting device for a primary forming tool and method for cleaning a venting device

[0004] The invention relates to a venting device for a primary forming tool and a method for cleaning a venting device.

[0005] Primary forming processes, such as injection molding or foaming, are well known. These processes utilize primary forming tools. Such tools have cavities into which a formless material is introduced. After the material hardens, a solid body is formed, which, due to the cavity, has a geometrically defined shape.

[0006] The formless, flowable material is introduced through one or more inlet openings. The flowable material then spreads within the mold (the so-called mold filling phase). A challenge here is that during the mold filling phase, the air present in the cavity must be expelled by the flowable material. If some of the air does not escape from the cavity in time or becomes trapped, this leads to undesirable effects, such as incomplete filling of the mold cavity, excessive heating of the compressed air and charring on the finished part (also known as the burner or diesel effect), air inclusions, weld lines, air pockets, and / or streaking on the plastic part.

[0007] To solve the problem of inadequate venting, various methods are known in the prior art, for example, generating a negative pressure in the cavity, flooding the cavity with nitrogen, or channels for tool venting, which can be formed by suitable dimensioning of the closing surfaces or special venting devices in the original tool, for example sintered metal vent plugs.

[0008] Venting devices with gas-permeable structures have the disadvantage that their pores or channels become increasingly clogged by the flowable material and / or volatile components that outgas from the flowable material during the mold filling phase. As a result, the effectiveness of these venting devices diminishes significantly or ceases entirely after only a few operating cycles. For example, sintered metal vent plugs then have to be removed and cleaned outside the mold. This is time-consuming and causes undesirable machine downtime due to setup procedures, leading to high overall maintenance costs.

[0009] Based on this, the object of the invention is to provide a venting device that can be easily cleaned in the installed state with minimal time expenditure, thus enabling reliable primary forming tool venting while simultaneously keeping operating costs low.

[0010] The problem is solved by a venting device with the features of independent claim 1. A system for venting a primary forming tool is the subject of dependent claim 13, and a method for operating a venting device for a primary forming tool is the subject of further dependent claim 14. Preferred embodiments are the subject of the dependent claims. According to a first aspect, the invention relates to a venting device for a primary forming tool.

[0011] The venting device is, in particular, a venting insert, wherein the housing of the venting device can be inserted with a free end into an opening of the primary forming tool. The free end of the venting device closes the opening of the primary forming tool, but gas contained in the cavity of the primary forming tool can escape via a vent channel provided in the venting device.

[0012] The venting device has a venting section comprising at least one gas-permeable area, in particular a gas-permeable layer. The gas-permeable area is designed to allow gas contained in the mold to escape into the vent channel in an outflow direction, while simultaneously forming a barrier to any material being formed in the mold. "Barrier" in this context means that the material being formed is at least substantially prevented from entering the gas-permeable area. However, completely preventing any ingress is not possible in most cases.

[0013] The venting device includes a heating element that is thermally coupled to the venting section. The heating element is designed to heat at least the gas-permeable area of ​​the venting section to a temperature of at least 300 °C, thereby causing decomposition. "Decomposition" in this context means either a purely thermal decomposition process without oxygen (i.e., pyrolysis), a chemical reaction with oxygen from the environment (i.e., combustion), or a combination of both processes. This decomposition allows the material to be formed and / or its components, as well as any primary forming process aids present, to be advantageously removed from the venting section.

[0014] The technical advantage of the venting device lies in its ability to ensure effective and reliable venting of the molding tool. Residues of the material being formed are thermochemically decomposed and / or burned off in the gas-permeable area of ​​the venting device by the heat input, thus guaranteeing continuous venting. It should be noted that the venting insert can be cleaned while installed, i.e., without removing the venting device for cleaning and subsequent reinstallation.

[0015] According to one embodiment, a compressed air connection and / or vacuum connection is provided in fluid communication with the venting channel. This connection allows for the application of overpressure or underpressure in the venting channel to remove decomposition products and / or combustion products generated during the decomposition process from the gas-permeable area of ​​the venting section. Overpressure can be applied to the venting channel via the compressed air connection, causing the decomposition products and / or combustion products to be blown into the cavity of the mold against the outflow direction (the direction of the gas during a venting process, i.e., from the cavity of the mold into the venting channel).In the case of a vacuum connection, a vacuum can be created in the vent channel, causing the decomposition products and / or combustion products to be drawn into the vent channel in the outflow direction and removed from the venting device via the vacuum connection. The compressed air connection and / or vacuum connection ensures that the decomposition products and / or combustion products are removed from the gas-permeable area, thus guaranteeing sufficiently effective venting of the primary forming tool even over numerous production cycles.

[0016] Alternatively or additionally, the removal of combustion products from the gas-permeable area of ​​the venting section can also be achieved via the internal pressure that arises in the primary mold tool when the material to be formed is introduced.

[0017] According to one embodiment, the gas-permeable area comprises a porous material or channels. The channels can be formed by drilling, particularly laser drilling. Alternatively, they can be formed by an additive manufacturing process. The porous material or the channels have openings in the range of 10 pm to 200 pm at the interface between the gas-permeable area and the cavity of the original mold. An equivalent diameter is used to determine the size of these openings (opening size). This equivalent diameter is determined by calculating the diameter of a sphere that would fit through the opening to be specified or the subsequent channel structure. This ensures that the gas-permeable area forms a sufficiently good barrier for the material to be molded.if it does not penetrate, or substantially does not penetrate, the gas-permeable area, but gas can escape from the original tool via the gas-permeable area.

[0018] According to one embodiment, the porosity of the gas-permeable area is constant or substantially constant in the outflow direction. Alternatively, the porosity of the gas-permeable area can exhibit inhomogeneous porosity in the outflow direction, with the porosity increasing in this direction. For cleaning the gas-permeable area, it is necessary that the pressure drop within the gas-permeable area be as low as possible, so that a sufficiently high positive or negative pressure is present even at the surface of the gas-permeable area, which forms the interface with the cavity of the mold. With a very thin gas-permeable area, this can also be achieved by a constant or substantially constant porosity.To avoid excessive pressure drop at greater layer thicknesses, the porosity can be inhomogeneous, such that the pore size decreases towards the surface of the gas-permeable area, which forms the interface to the cavity of the original tool, and thus the porosity also decreases.

[0019] According to one embodiment, an inhomogeneous porosity is formed, at least section by section, by several individual layers arranged one above the other in the outflow direction and bonded together materially, wherein the porosity in each individual layer is the same or substantially the same when viewed in the outflow direction, and wherein there is a difference in porosity between directly successive individual layers. Such a layering of layers with different porosities can be achieved, for example, by an additive manufacturing process in which a metal powder is selectively melted by means of a laser beam (selective laser melting).

[0020] As an alternative to the layered structure, the inhomogeneous porosity can also have a continuous or essentially continuous porosity profile. According to one embodiment, the venting section has a support structure located downstream of the gas-permeable area in the outflow direction. Channels larger than 200 pm in the gas-permeable area are specifically referred to as support structures. Compared to the gas-permeable area, the support structure has a higher gas permeability and sufficient mechanical stability to withstand the forces acting during the primary forming process without permanent deformation. Viewed in the outflow direction, the support structure borders directly on the gas-permeable area, so that the gas-permeable area is supported by the support structure. This is particularly advantageous in injection molding or foaming processes where high pressures are present in the primary forming tool.The high mechanical stability of the support structure prevents undesirable deformation and destruction of the gas-permeable area caused by the high material pressure during the filling process of the mold cavity. The support structure can, for example, have outflow channels with an opening width larger than the largest pore size of the gas-permeable area. The support structure can also have a grid-like structure. In particular, it can have a greater thickness, measured in the outflow direction, than the gas-permeable area.

[0021] According to one embodiment, the venting section is made of a metallic material and is manufactured using additive manufacturing. This allows the venting section to be inhomogeneous in the outflow direction, meaning, for example, that the gas-permeable area has inhomogeneous porosity in the outflow direction. Furthermore, it is possible to construct the venting section from two directly adjacent and materially bonded sub-areas: a gas-permeable area that forms the barrier for the material being molded, and a support structure that mechanically supports the gas-permeable area on its rear side, opposite the surface of the gas-permeable area facing the cavity.

[0022] According to one embodiment, the venting device has a housing. The housing can have a tube-like section in which the venting section is provided. The venting channel runs through the venting section inside the housing.

[0023] According to one embodiment, the venting section and the housing are formed in one piece from a metallic material. This achieves high mechanical stability of the venting device, which can absorb the forces acting during the primary forming process without permanent deformation.

[0024] According to one embodiment, the vent section and the housing are manufactured in one piece using additive manufacturing. This makes it possible for both the vent section and the housing to be structured or permeated with channels, pores, or other structures that ensure the functionality of the venting device with regard to its venting properties, cleanability, and / or thermal properties. For example, a one-piece housing with an integrated vent section can be created in which the gas-permeable area has a predetermined porosity or...a predetermined porosity profile, a support layer with a predetermined channel structure behind the gas-permeable area, and channels in the housing wall for the passage of a cooling fluid and / or other thermal barriers that reduce the transfer of heat during the thermal cleaning process from the venting device to the primary forming tool.

[0025] According to one embodiment, the heating device comprises an electric heating element that is inserted section by section into a recess of the venting section. This ensures good heat transfer into the venting section. Heat transfer can occur through direct contact between the heating element and the venting section of the venting device. Alternatively, heat transfer can also occur without contact through thermal radiation from the heating element to the venting section and / or by means of convective transfer through gas present in the venting channel and / or the cavity, or through a generated gas flow. An inductor can also be installed, which is designed to inductively heat the gas-permeable area.

[0026] Preferably, a free end of the heating element is inserted into the recess and at least partially contacts the inner wall of the recess, so that a high heat transfer from the heating device to the venting section, in particular to the gas-permeable area of ​​the venting section, takes place. The recess can be shaped to conform to the outer contour of the heating element.

[0027] According to one embodiment, the heating element is arranged centrally to the venting section. The gas-permeable layer is, for example, ring-shaped and extends around the heating element, particularly the recess into which a section of the heating element can be inserted. This ensures good heat transfer between the heating element and the gas-permeable area. It is understood that more than one heating element can also be provided. In this case, the heating elements are spaced apart from each other and distributed throughout the venting section.

[0028] In particular, several recesses are provided distributed across the venting section, into each of which a heating element is inserted at the free end.

[0029] According to one embodiment, the heating element is rod-shaped and its free end is inserted into the recess of the vent section. The heating element is, for example, made of an electrically conductive ceramic, in particular a silicon nitride ceramic, and is configured to be heated to a temperature of up to 1000°C. Preferably, the heating element is connected to the vent section in such a way that the gas-permeable area can be heated to a temperature in the range of 300°C to 950°C, in particular in the range of 500°C to 700°C. The heating device is further preferably configured such that the gas-permeable area can be heated to a temperature in the range between 400°C and 800°C, in particular between 500°C and 700°C, for example 600°C, in a period of less than 60s, preferably less than 30s, in particular between 10s and 20s, for example 15s.

[0030] According to one embodiment, the heating element inserted into a recess of the vent section is spring-loaded. The spring load can be achieved, for example, by means of a tongue-shaped spring element that mechanically presses a flat side of the heating element against the inner wall of the recess. This ensures good heat transfer from the heating element to the vent section. Furthermore, the spring element can achieve a clamping fixation of the heating element in the recess, thus preventing it from being pulled out.

[0031] According to one embodiment, the housing of the venting device has cooling channels, at least in the area surrounding the venting section, through which a cooling medium can flow. The cooling medium comprises a substance that dissipates heat in the transition zone between the venting section and the forming tool. The substance can be gaseous or liquid. Alternatively or additionally, a thermal barrier can be provided in the housing to reduce the heat input from the venting device into the forming tool. This reduces the heat loss that occurs during the thermal cleaning of the venting section, allowing higher temperatures to be achieved in the gas-permeable area for a given heating power. Furthermore, it prevents undesirable overheating of the forming tool area surrounding the venting device.

[0032] According to another aspect, a system for venting a cavity of a primary mold is disclosed. The system comprises a venting device and a control unit for controlling the operating sequences of the venting device. The control unit is configured to activate the heating element of the venting device during a cleaning cycle, so that a decomposition process and thus cleaning takes place in the gas-permeable area of ​​the venting section.The control unit is configured to activate a pressurization unit during the cleaning cycle. This unit is coupled to the vent channel of the venting device and is designed to generate overpressure and / or underpressure in the vent channel. The overpressure or underpressure generated by the pressurization unit in the vent channel removes decomposition products and / or combustion products generated during the decomposition process from the gas-permeable area of ​​the vent section. Activation of the heating device can occur based on communication with the plant control system to indicate the open or closed state of the primary mold and / or the number of injection molding cycles since the last cleaning cycle.

[0033] The system offers the technical advantage that effective cleaning of the venting device is possible, since the portion of the fluid introduced into the gas-permeable area is first decomposed and then the resulting decomposition products are removed from the gas-permeable area by overpressure or underpressure.

[0034] According to a further aspect, a method for operating a venting device for a primary forming tool is disclosed. The venting device is installed in an opening of the primary forming tool. The venting device comprises a venting section that forms a venting channel. The venting section includes a gas-permeable area through which gas contained in the primary forming tool can escape. A heating device is also provided, which is thermally coupled to the gas-permeable area. The method comprises the following steps:

[0035] - Heating the heating element in such a way that the gas-permeable area of ​​the venting section has a temperature of at least 300°C and thereby a decomposition process is carried out; - simultaneously or sequentially with the heating, generating an overpressure or underpressure, wherein the overpressure or underpressure is selected in such a way that material residues of the substance used in the primary forming process and / or decomposition products resulting from the decomposition process are removed from the gas-permeable area of ​​the venting section.

[0036] According to one embodiment of the method, a test cycle is performed to determine whether a cleaning cycle of the venting device is necessary. In this test cycle, an overpressure or underpressure is built up in the venting channel, and the time it takes for the overpressure or underpressure to fall below a predetermined threshold value due to pressure equalization through the gas-permeable area of ​​the venting section. Depending on the time required for pressure equalization, the cleaning cycle of the venting device is activated. This test has the advantage that the degree of blockage of the gas-permeable area can be determined, and the cleaning cycle can be activated based on this degree of blockage. This enables situation-dependent cleaning of the venting device.

[0037] The "gas-permeable area" forms a barrier for a [missing information] in [missing information].

[0038] The term "primary forming tool for the material to be formed" as used in this disclosure is understood to mean that the gas-permeable area has a structure that allows gaseous substances to escape through this layer, but presents a barrier to flowable substances that are to be formed in the primary forming tool. However, "barrier" does not mean that all penetration of the material to be formed is completely prevented. The primary forming tool can, in particular, be a plastic injection mold or be designed for forming foams.

[0039] The terms “approximately”, “essentially” or “about” mean, within the meaning of the invention, deviations from the respective exact value by + / - 10%, preferably by + / - 5% and / or deviations in the form of changes that are insignificant for the function.

[0040] Further developments, advantages, and possible applications of the invention will also become apparent from the following description of exemplary embodiments and from the figures. All features described and / or illustrated are, individually or in any combination, fundamentally the subject matter of the invention, irrespective of their compilation in the claims or their cross-reference. The content of the claims is also incorporated into the description.

[0041] The invention will be explained in more detail below with reference to several figures illustrating exemplary embodiments. The figures show:

[0042] Fig. 1 shows an exemplary and schematic sketch to explain the functioning of a venting device for venting a cavity of a primary forming tool;

[0043] Fig. 2 shows an exemplary and schematic longitudinal section view of an embodiment of a venting device;

[0044] Fig. 3 shows an exemplary sectional, perspective view of an embodiment of the venting device; Fig. 4 shows an exemplary and schematic representation of an inhomogeneously porous, gas-permeable area composed of several layers;

[0045] Fig. 5 shows an exemplary and schematic system for operating the venting device;

[0046] Fig. 6 shows an example of a diagram with pressure curves for testing the degree of closure of the venting device;

[0047] Fig. 7 shows an example of a diagram with pressure and temperature profiles for cleaning the venting device;

[0048] Fig. 8 shows, by way of example and schematically, a longitudinal sectional view of another embodiment of a venting device; and

[0049] Fig. 9 is a schematic block diagram illustrating the steps of a method for operating a venting device of a primary forming tool.

[0050] Figure 1 shows, by way of example and in a rough schematic, a section of a primary forming tool 2 into which a venting device 1 is inserted. The primary forming tool 2 has an opening 2.1 in its wall, into which the venting device 1 is inserted. The interface 5.1.1 provided at the free end of the venting device 1 lies flush or substantially flush with the inner surface of the tool, which defines a cavity 2.2 of the primary forming tool 2.

[0051] The venting device 1 is designed to form a venting path for a gas located in the cavity 2.2 of the primary forming tool 2. When the cavity 2.2 is filled with a flowable substance S to be formed, as indicated by arrows P1 in Fig. 1, the air in the cavity 2.2 is increasingly displaced by the substance S and can escape from the cavity 2.2 through the venting device 1, as indicated by the dashed arrows in Fig. 1.

[0052] The construction of the venting device 1 is explained in more detail below with reference to Figures 2 and 3.

[0053] The venting device 1 comprises a housing 3, in the interior of which a venting channel 4 is provided. In particular, the housing 3 has a wall, which is, for example, sleeve-like and circumferentially encloses the venting channel 4. The venting device 1 has a free end, which is designed to be inserted into a wall opening 2.1 of the primary forming tool 2. The free end of the housing 3 is designed with respect to shape and size such that the wall opening of the primary forming tool 2 is closed.

[0054] At the free end of the housing 3, which is designed to close the wall opening of the primary forming tool 2, a venting section 5 is provided. The venting section 5 comprises at least one gas-permeable area 5.1, the underside of which, facing the cavity 2.2 of the primary forming tool 2, forms an interface 5.1.1 by means of which the opening 2.1 of the primary forming tool 2 is closed and which therefore comes into contact with the material S to be formed.

[0055] The gas-permeable region 5.1 is designed to allow the gas present in the cavity 2.2 to transmit in the outflow direction AR into the vent channel 4, but to prevent the fluid S from flowing into the vent channel 4. In other words, the gas-permeable region 5.1 forms a barrier for the fluid S, but not for gases present in the cavity. The gas-permeable region 5.1 can, for example, be formed by a porous layer. Alternatively, the gas-permeable region 5.1 can have a multitude of microbores extending in the outflow direction AR. The gas-permeable region 5.1 allows gas to flow in the outflow direction AR from the interface 5.1.1 towards the vent channel 4. The gas-permeable region 5.1 has openings located in the region of the interface 5.1.1. The opening has a maximum width in the range between 10 pm and 200 pm, preferably between 20 pm and 50 pm, particularly 40 pm or substantially 40 pm. At this opening width, depending on the specific flowable substance used, gas can escape from the cavity 2.2, but a substance flowing into the cavity cannot penetrate into the gas-permeable area 5.1, or can only do so to a very limited extent.

[0056] The gas-permeable area 5.1 can have a layer thickness in the range of 1mm to 5mm, preferably between 2mm and 4mm, particularly 3mm.

[0057] High pressures can occur in the primary forming tool 2. To increase the stability of the venting device 1, the venting section 5 has a support structure 5.2, which is arranged downstream of the gas-permeable area 5.1 in the outflow direction AR and mechanically supports the gas-permeable area 5.1. The support structure 5.2 preferably has a greater thickness, measured in the outflow direction AR, than the gas-permeable area 5.1. The gas permeability and mechanical stability of the support structure 5.2 are greater than those of the gas permeability and mechanical stability of the gas-permeable area 5.1, so that the forces acting during the primary forming process can be absorbed without permanent deformation. As can be seen in Fig. 3, the support structure 5.2 can, for example, have a lattice-like structure with a plurality of intersecting wall sections.This allows for mechanical stability to absorb the forces generated during the primary forming process while maintaining high gas permeability.

[0058] The venting device 1 has a heating element 6. The heating element 6 is, in particular, an electric heating element. In the illustrated embodiment, the heating element 6 is rod-shaped and comprises a plate-shaped heating element with a rectangular cross-section.

[0059] The heating device 6 is provided centrally in the venting device 1 and its longitudinal axis runs parallel or substantially parallel to the longitudinal axis LA of the venting duct 4.

[0060] The vent section 5 has a recess 5.3 designed to receive the free end of the heating element 6. The recess 5.3 is preferably centered in the vent section 5, for example, such that the gas-permeable area 5.1 and the support structure 5.2 extend ring-like around the recess 5.3. The shape of the recess 5.3 is preferably adapted to the shape of the free end of the heating element 6 such that at least half of the outer surface of the heating element 6 rests against the inner surface of the recess 5.3, thus ensuring good heat transfer between the heating element 6 and the vent section 5. Preferably, heating takes place only in the area of ​​the free end of the heating element 6, and in particular in the area that is inserted into the recess 5.3. To ensure contact between the heating element 6 and the inner surface of the recess 5.3,3. To ensure and / or improve heat transfer permanently, a pressure element 5.4 can be provided, which exerts a lateral contact pressure transverse to the longitudinal axis of the heating device 6. In the illustrated embodiment, the pressure element 5.4 is formed by a leaf spring-like pressure element. The pressure element 5.4 projects beyond the support structure 5.2 onto the side facing away from the gas-permeable layer 5.1 and is designed to exert a lateral contact pressure on the heating device 6 when it is inserted into the recess 5.3, thereby ensuring that the heating device 6 is securely seated against the inner surface of the recess 5.3.

[0061] As can be seen in Fig. 2, the heating device 6 can be subjected to force in the direction of its longitudinal axis by means of an elastic element 6.1, so that the heating device 6 is secured in the state in which it is inserted into the recess 5.3. The elastic element 6.1 can, for example, be a spring. It is understood that other forms of elastic elements are also conceivable.

[0062] The heating device 6 is designed to heat the gas-permeable area 5.1 to a temperature of at least 300°C, in particular a temperature in the range between 400°C and 800°C, for example 500°C, 550°C, 600°C, 650°C, 700°C or 750°C. Depending on the material being formed, this ensures that any residues of the material that have penetrated the gas-permeable area 5.1 are thermochemically decomposed and / or incinerated.

[0063] The heating device 6 comprises, in particular, a ceramic heating element, which is formed, for example, from a hot-pressed silicon nitride ceramic. The heating device 6 can preferably be heated to temperatures of up to 1000°C within a short time, for example, <2 s. The heating capacity enables, for example, the heating of the gas-permeable area 5.1 to temperatures of at least 300°C within a time span of between 5 s and 60 s. This allows the temperatures necessary for decomposition to be reached quickly, thereby reducing the time required for cleaning.

[0064] The venting device 1 has a gas connection 7 through which the vent channel 4 can be pressurized or depressurized. In particular, compressed air can be introduced into the vent channel 4 via the gas connection 7, or a vacuum can be created in the vent channel 4 via the gas connection 7. The overpressure or vacuum allows residues resulting from decomposition to be expelled from the gas-permeable area 5.1. When overpressure is created, this occurs by blowing the residues out against the outflow direction AR towards the primary forming tool 2. When a vacuum is created, the residues are drawn into the vent channel 4 in the outflow direction AR and discharged via the gas connection 7.

[0065] The housing 3 of the venting device 1 preferably has at least one cooling channel 3.1 or a thermal barrier. The cooling channel 3.1 is provided in the wall of the housing 3, specifically in the region of the free end where the venting section 5 is located and which is inserted into the primary forming tool 2. The cooling channel 3.1 is in fluidic communication with a cooling medium connection. A cooling medium can be supplied to the venting device 1 via this cooling medium connection. This cooling medium flows through the at least one cooling channel 3.1 and thereby cools the housing 3 of the venting device 1 in the region where the venting section 5 is located. This reduces the heat input from the venting device 1 to the primary forming tool 2.

[0066] Alternatively or additionally to the cooling channel 3.1, the housing 3 can have a thermal barrier in the area of ​​the free end where the vent section 5 is provided and which is inserted into the primary forming tool 2. The thermal barrier can be formed by a material (in particular also by a gas inclusion) that is provided in the housing wall and that has thermally insulating properties.

[0067] Fig. 4 shows, by way of example and in a rough schematic representation, a gas-permeable region 5.1 which has an inhomogeneous porosity. The inhomogeneous porosity is specifically such that the porosity increases from the interface 5.1.1 in the outflow direction AR, i.e., the pore size and thus also the gas permeability increases in the outflow direction AR.

[0068] The gas-permeable region 5.1 preferably comprises several porous individual layers 5.1.2, which have different porosities but are bonded together in a materially bonded manner. For example, a first porous layer immediately adjacent to the interface 5.1.1 can have a pore size in the range of 10 pm to 50 pm, in particular 20 pm, 30 pm, or 40 pm. The pore size increases with each porous layer in the outflow direction AR and reaches, for example, a porosity in the range of 150 pm to 250 pm, in particular 200 pm, at the last porous layer, which is located away from the interface 5.1.1. The inhomogeneous porosity ensures that the gas-permeable area 5.1 has a very small pore size only in a very thin region, so that the pressure loss through the gas-permeable area 5.1 is as low as possible. Preferably, the venting section 5, i.e., the gas-permeable area 5.1, is connected to the supporting structure 5.2 formed in one piece. The vent section 5 can be manufactured in particular by means of additive manufacturing processes, for example by means of an LPBF process (LPBF: Laser Powder Bed Fusion), in which a metallic powder is selectively melted by a laser. This makes it possible to manufacture a pressure-resistant vent section 5 that has both the gas-permeable area 5.1 with the desired gas permeability and the supporting structure 5.2.

[0069] Preferably, the vent section 5 and the housing 3 of the venting device 1 are manufactured as a single component. In particular, the vent section 5 and the housing 3 can be manufactured using additive manufacturing processes, for example, using an LPBF process (LPBF: Laser Powder Bed Fusion), in which a metallic powder is selectively melted by a laser. This makes it possible to manufacture a pressure-resistant venting device 1 that includes both the vent section 5 and the housing 3 with their respective structures.

[0070] Fig. 5 shows, in a rough schematic block diagram, an embodiment of a system 10 for operating a venting device 1 of a primary forming tool 2. The system 10 comprises at least one venting device 1, which is equipped with a

[0071] The original tool 2 is coupled to vent its cavity 2.2 during the inflow of the fluid. The system 10 also includes a control unit 11, a manipulation unit 12, and a supply unit 13.

[0072] The control unit 11 is configured to control the venting process and other processes of the system 10. The control unit 11 can, in particular, be a control computer that, for example, receives sensor information Sl provided by the supply unit 13 and, based on this, transmits switching or control information ST to the supply unit 13.

[0073] The supply unit 13 is designed to supply the venting device 1 with the operating resources required for its operation. These include, for example, electrical energy for the heating device 6, a cooling medium (arrow PK), compressed air (arrow PL) and / or negative pressure, etc.

[0074] Furthermore, control information and / or sensor information can be exchanged between the supply unit 13 and the venting device 1 (arrow P). sThe supply unit 13 can include one or more power supplies for providing electrical energy to the venting device 1, one or more switching valves for applying compressed air and / or vacuum to the venting device 1, and one or more switching valves for venting gases, etc. The supply unit 13 can also have a vent outlet E through which venting gases can be released into the environment. Communication takes place between the system that performs the primary forming process and the control unit 11 to inform the control unit 11 of the number of primary forming cycles completed, as well as the open / closed state of the primary forming tool. Conversely, the control unit 11 informs the system that performs the primary forming process whether the testing or cleaning process is complete and the next production intervals can be started.This communication is indicated by the double arrow SGZ. The pressurization unit 12 is designed to provide compressed air and / or negative pressure. The pressurization unit 12 is coupled to the supply unit 13, via which compressed air and / or negative pressure is supplied to the venting device 1 in a controlled manner.

[0075] Fig. 6 shows, by way of example and schematically, two pressure curves P in the vent channel 4 over time t. Here, P can denote either an overpressure or a negative pressure. In this specific example, pressure curves under overpressure are shown. Using the pressure curves shown in Fig. 6, a method for checking the degree of closure of the gas-permeable area 5.1 of the vent section 5 is described below. The method utilizes the fact that the time required for an overpressure or negative pressure built up in the vent channel 4 to drop to a predetermined pressure threshold Po through pressure equalization with the environment depends on the degree of closure of the gas-permeable area 5.1.

[0076] First, a reference curve Pref for the pressure drop is determined, and based on this, a reference time interval to is calculated, within which the overpressure or underpressure in the venting channel has dropped from the starting value Pstart to the pressure threshold Po. This reference curve Pref can be recorded, in particular, before the initial commissioning of the venting device 1. Alternatively, the reference curve Pref can also be recorded at a production start after initial commissioning. This reference time interval to is stored in a memory unit of the system 10.

[0077] Subsequently, after several venting cycles, a closure test is performed in which an overpressure or underpressure with a starting value Pstart is again built up in the venting channel 4, and the time it takes for the overpressure or underpressure to drop to the pressure threshold Po is determined. The time until the pressure threshold Po is reached is a measure of the degree of closure of the gas-permeable layer 5.1. If the time exceeds a predefined threshold, it can be concluded that the gas-permeable area 5.1 does not provide reliable venting of the

[0078] Urform Tool 2 allows for more frequent use, and a cleaning cycle is necessary to ensure adequate venting. The frequency of the closure test can be freely defined. The closure test can be performed during the tool opening phases and therefore has no impact on production processes. Furthermore, this test has an additional cleaning effect.

[0079] The cleaning cycle comprises heating the gas-permeable area 5.1 to decompose the residues contained therein into decomposition products. Preferably, the decomposition products are then discharged from the gas-permeable area 5.1 by pressurizing or underpressuring the vent channel 4.

[0080] Fig. 7 shows, by way of example and schematically, a course of the temperature T and the overpressure or underpressure P generated in the vent channel 4 over time.

[0081] At the beginning of the cleaning cycle, the gas-permeable area 5.1 is heated to a temperature T of at least 300°C, in particular a temperature T between 400°C and 800°C. After heating, the temperature is preferably kept constant or substantially constant for a predetermined period. This period can, for example, be in the range of 30 s to 300 s, in particular in the range of 50 s to 70 s, and most preferably 60 s or approximately 60 s. The temperature of the heating device 6 can be controlled via the PTC behavior of the heating device 6. That is, the heating device 6 is subjected to a controlled current such that its resistance has a constant or substantially constant value, the resistance value used for control being selected to correspond to the desired temperature of the heating device 6. Alternatively, a separate measuring instrument, such as a PTC thermistor, can be used.A thermocouple can be used to detect or determine the temperature in the gas-permeable area 5.1.

[0082] Simultaneously with the heating, or possibly at a later time, the vent channel 4 is subjected to overpressure or underpressure, so that decomposition products formed by the heating of the gas-permeable area 5.1 are carried out of the gas-permeable area 5.1. As indicated in Fig. 7, the application of overpressure or underpressure to the vent channel 4 can last longer than the heating cycle. For example, the application of overpressure or underpressure to the vent channel 4 can last for a period of 60 s to 120 s and, for example, at least 10 s, preferably 20 s or 30 s longer than the phase in which the heating device 6 is activated. This ensures that the decomposition products formed are carried out sufficiently effectively from the gas-permeable area 5.1.

[0083] The cleaning cycle described above is carried out while the venting device 1 remains installed in the original tool 2.

[0084] Fig. 8 shows a further embodiment of a venting device 1. The differences between this embodiment and the previously described embodiment are explained below. Otherwise, the preceding statements also apply to this second embodiment.

[0085] The essential difference between the two embodiments is that this venting device 1 has no housing and is inserted directly into an opening 2.1 of the original tool 2 without a housing.

[0086] The venting device 1 comprises the venting section 5 and the heating device 6. The venting section 5 is inserted directly into the opening 2.1 of the primary forming tool 2 and fixed in the primary forming tool 2.

[0087] The venting section 5 preferably has the same structure as previously described. The venting channel 4 is formed by the gas-open structure of the venting section 5.

[0088] In this embodiment, the decomposition products generated by the decomposition process are preferably discharged by means of an overpressure applied in the cavity of the primary forming tool 2. This overpressure can be generated either by actively pressurizing the cavity with a gas or, alternatively, by the inflow of the material to be formed. In both cases, the decomposition products are blown out of the gas-permeable area by means of the overpressure, thereby improving the gas permeability of the venting section 5.

[0089] Fig. 9 shows a block diagram illustrating the process steps of a method for operating a venting device of a

[0090] The original form of the tool is illustrated. First, the heating element is heated in such a way that the gas-permeable area of ​​the venting section has a temperature of at least 300°C and a decomposition process is thereby carried out (S10).

[0091] Simultaneously or sequentially with heating, an overpressure or underpressure is generated in the venting channel. The overpressure or underpressure is selected such that any material residues present in the gas-permeable area from the material used in the primary forming process and / or decomposition products resulting from the decomposition process are removed from the gas-permeable area of ​​the venting section (S11).

[0092] The invention has been described above using exemplary embodiments. It is understood that numerous modifications and adaptations are possible without thereby departing from the scope of protection defined by the patent claims. List of reference numerals

[0093] 1 venting device

[0094] 2 Primary Form Tool

[0095] 2.1 Opening

[0096] 2.2 Cavity

[0097] 3 Housing of the venting device 3.1 Cooling channel

[0098] 4. Venting channel

[0099] 5. Ventilation section

[0100] 5.1 Gas-permeable area

[0101] 5.1.1 Interface

[0102] 5.1.2 porous single layers

[0103] 5.2 Supporting structure

[0104] 5.3 Exclusion

[0105] 5.4 Pressure element

[0106] 6 Heating system

[0107] 6.1 elastic element

[0108] 7 Gas connection

[0109] 10 System

[0110] 11 Control unit

[0111] 12 operating units

[0112] 13 supply unit

[0113] AR outflow direction

[0114] E Vent outlet

[0115] LA Longitudinal axis

[0116] P Overpressure / Underpressure

[0117] Po pressure threshold

[0118] Pmeasured measured pressure; Pref reference curve of pressure; Pstart starting value of pressure

[0119] S fabric

[0120] Sl sensor information

[0121] ST Tax Information

[0122] to reference time period

Claims

Patent claims 1) Venting device for a primary forming tool (2) having a cavity, wherein the venting device (1) has a venting section (5) with a venting channel (4), wherein the venting section (5) comprises at least one gas-permeable area (5.1) configured to allow gas contained in the cavity of the primary forming tool (2) to escape in the outflow direction (AR) into the venting channel (4), but forming a barrier to a material to be formed in the primary forming tool (2), wherein a heating device (6) is provided which is thermally coupled to the venting section (5), wherein the heating device (6) is configured to heat at least the gas-permeable area (5.1) of the venting section (5) to a temperature of at least 300 °C and thereby cause a decomposition process. 2) Venting device according to claim 1, characterized in that a compressed air connection and / or vacuum connection (7) is provided which is in fluid communication with the venting channel (4), via which an overpressure or a vacuum can be effected in the venting channel (4) in order to remove decomposition products resulting from the decomposition process from the gas-permeable area (5.1) of the venting section (5). 3) Venting device according to claim 1 or 2, characterized in that the gas-permeable area (5.1) has a porous material or passage channels formed by means of microbores, wherein the porous material or the passage channels have openings in the area of ​​the interface (5.1.1) of the gas-permeable area (5.1) towards the cavity of the primary forming tool (2) with a maximum opening size in the range between 10pm and 200pm. 4) Venting device according to claim 3, characterized in that the porosity of the gas-permeable area (5.1) in the outflow direction (AR) is constant or substantially constant or that the gas-permeable area (5.1) has an inhomogeneous porosity as seen in the outflow direction (AR), wherein the porosity increases in the outflow direction (AR). 5) Venting device according to claim 4, characterized in that the inhomogeneous porosity is formed at least sectionally by several individual layers (5.1.2) arranged one above the other in the outflow direction (AR) and connected to each other in a materially bonded manner, wherein the porosity in an individual layer (5.1.2) is the same or substantially the same when viewed in the outflow direction (AR) and wherein there is a difference in porosity between directly successive individual layers (5.1.2). 6) Venting device according to one of the preceding claims, characterized in that the venting section (5) has a support structure (5.2) which is arranged in the outflow direction (AR) behind the gas-permeable area (5.1), wherein the support structure (5.2) has a higher gas permeability and mechanical stability compared to the gas-permeable area (5.1) in order to be able to absorb the forces acting during the primary forming process without permanent deformation. 7) Venting device according to one of the preceding claims, characterized in that the venting section (5) is made of a metallic material and is manufactured by additive manufacturing. 8) Venting device according to one of the preceding claims, characterized in that the venting device (1) has a housing (3) and the venting section (5) and the housing (3) are formed in one piece from a metallic material. 9) Venting device according to claim 8, characterized in that the venting section (5) and the housing (3) are manufactured in one piece by additive manufacturing. 10) Venting device according to one of the preceding claims, characterized in that the heating device (6) comprises an electric heating element which is inserted section by section into a recess (5.3) of the venting section (5). 11) Venting device according to one of the preceding claims, characterized in that the heating device (6) is arranged centrally and / or in an annular manner in the venting section (5) and that the gas-permeable area (5.1) is annular in shape and extends around the heating device (6). 12) Venting device according to one of the preceding claims, characterized in that the venting device (1) has a housing (3) and that the housing (3) has, at least in the area enclosing the venting section (5), cooling channels (3.1) through which a cooling medium can flow, and / or a thermal barrier which reduces the heat input from the venting device (1) into the primary forming tool (2). 13) System comprising a venting device (1) according to one of the preceding claims and a control unit (11) for controlling the operating sequences of the venting device (1), wherein the control unit (11) is configured to activate the heating device (6) of the venting device (1) in a cleaning cycle, so that in the gas-permeable area (5.1) of the venting section (5) a decomposition process is carried out and wherein the control unit (11) is configured to activate in a cleaning cycle an actuation unit (12) which is coupled to the venting channel (4) of the venting device (1) and is designed to generate an overpressure and / or underpressure in the venting channel (4), so that by means of the overpressure or underpressure generated by the actuation unit (12) in the venting channel (4) the decomposition products resulting from the decomposition process are removed from the gas-permeable layer of the venting section. 14) Method for operating a venting device (1) of a primary forming tool (2), wherein the venting device (1) is inserted in an opening (2.1) of the primary forming tool (2), wherein the venting device (1) has a venting section (5) with a venting channel (4), wherein the venting section (5) comprises a gas-permeable area (5.1) through which gas contained in a cavity of the primary forming tool (2) can escape, wherein a heating device (6) is provided which is thermally coupled to the gas-permeable area (5.1), wherein the method comprises the following steps: - Heating the heating element (6) such that the gas-permeable area (5.1) of the venting section has a temperature of at least 300°C and thereby a decomposition process is carried out (S10); - simultaneously or sequentially with the heating, generating an overpressure or underpressure, wherein the overpressure or underpressure is selected such that material residues of the material used in the primary forming process and / or decomposition products resulting from the decomposition process are removed from the gas-permeable area (5.1) of the venting section (5) present in the gas-permeable area (5.1) (S11 ). Method according to claim 14, characterized in that a test cycle is performed to determine whether a cleaning cycle of the venting device (1) is necessary, wherein in the test cycle an overpressure or underpressure is built up in the venting channel (4), the time period is determined until the overpressure or underpressure has fallen below a predetermined threshold value through the pressure equalization via the gas-permeable area (5.1) of the venting section (5), and that the cleaning cycle of the venting device (1) is activated depending on the time period for the pressure equalization.

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