Pressing equipment

Abstract

A pressing apparatus (100) is disclosed. The pressing apparatus includes a pressure vessel (1, 8, 9) arranged therein to contain a pressure medium during use of the pressing apparatus. The pressure vessel includes a top closure (8) and a bottom closure (9). A furnace chamber (18) is arranged in the pressure vessel such that a pressure medium can enter and exit the furnace chamber, the furnace chamber at least partially defining a processing space (19) arranged to accommodate at least one article of work (5). The pressing apparatus includes at least one external convection loop pressure medium guiding passage (10, 11) in fluid communication with the furnace chamber and arranged to form an external convection loop within the pressure vessel. The external convection loop is arranged to guide the pressure medium, after it has exited the furnace chamber, near the inner surface (23) of the (multiple) walls (22) of the pressure vessel to a space (16) between the furnace chamber and the bottom closure. At least one pressure medium guide passage (21) is arranged inside the pressure vessel, such that the pressure medium can be introduced from the furnace cavity into the space between the furnace cavity and the bottom closure via only at least one pressure medium guide passage, and vice versa.

Description

Technical Field

[0001] This invention generally relates to the field of high pressure technology, and particularly to pressure processing. More specifically, this invention relates to a pressing apparatus for processing articles by, for example, hot isostatic pressing (HIP). Background Technology

[0002] Hot isostatic pressing (HIP) uses a pressure medium in the form of pressurized heated gas to achieve, for example, the consolidation, densification, or bonding of high-performance components and materials. For instance, HIP can be used to reduce or even eliminate porosity in processed articles to achieve 100% of the maximum theoretical density in processed articles, such as castings (e.g., turbine blades), resulting in excellent fatigue resistance, impact resistance, wear resistance, and abrasion resistance. Furthermore, HIP can be used to manufacture products by compressing powders (which may be called powder metallurgy HIP or PM HIP), where it is desired or necessary that these products be completely or substantially completely dense and have non-porous or substantially non-porous outer surfaces. Products obtained through HIP processing can be used in applications such as aircraft fuselages, aero engines, automotive engines, implants, and the marine industry. HIP offers numerous benefits and has become a viable and high-performance alternative and / or complement to traditional processes such as forging, casting, and machining. Articles to be pressure-treated by HIP can be positioned in the load compartment or chamber of an insulated pressure vessel. The treatment cycle can include loading, processing, and unloading the article. Several products can be processed simultaneously. The processing cycle can be divided into several parts or stages, such as a pressing stage, a heating stage, and a cooling stage. After the products are loaded into the pressure vessel, the pressure vessel can be sealed, and then a pressure medium (e.g., including an inert gas such as argon) is introduced into the pressure vessel and its load compartment. The pressure and temperature of the pressure medium are then increased, causing the products to be subjected to the increased pressure and temperature for a selected time period. The temperature of the pressure medium is increased by heating elements or a furnace arranged in the furnace chamber of the pressure vessel, which in turn increases the temperature of the products. The pressure, temperature, and processing time can, for example, depend on the desired or required material properties of the products being processed, the specific application, and the required quality of the products being processed. The pressure in the HIP can, for example, be in the range of 200 bar to 5000 bar (e.g., from 800 bar to 2000 bar). The temperature in the HIP can, for example, be in the range of 300°C to 3000°C (e.g., from 800°C to 2000°C).

[0003] When pressure treatment of a workpiece is complete, it may need to be cooled before removal from or unloading from the pressure vessel. The cooling characteristics of the workpiece (e.g., its cooling rate) can affect the metallurgical properties of the treated workpiece. It is generally desirable to cool the workpiece uniformly and, where possible, to control the cooling rate. Efforts have been made to reduce the time required for cooling workpieces undergoing HIP. For example, during the cooling phase, it may be necessary or desirable to rapidly reduce the temperature of the pressure medium (and thus the workpiece temperature) in a controlled manner without causing any large temperature changes within the load compartment (e.g., to reduce the temperature within the load compartment uniformly), and to maintain the temperature at a certain temperature level or within a certain temperature range for a selected time period with little or no temperature fluctuations during that selected time period. By ensuring that there are no large average temperature changes within the load compartment during the cooling of the workpiece, there may be little or no temperature changes within different parts of the workpiece during the cooling period. Therefore, internal stresses in the treated workpiece can be reduced. In some HIP applications, even relatively high cooling rates may be desired or required. Summary of the Invention

[0004] A pressing device (e.g., configured to perform HIP) generally includes multiple pressure medium passages within the pressure vessel of the pressing device. Some of these pressure medium passages may form forced convection loops within the pressure vessel to provide the ability to controllably cool the pressure medium in load compartments within the pressure vessel. Others may form natural convection loops within the pressure vessel.

[0005] The inventors have discovered that, particularly at relatively high cooling rates, at least a portion of the flow of the pressure medium in the forced convection loop during the cooling phase may not be directed (at least not entirely or nearly entirely) within the forced convection loop, but may instead be directed, at least to some extent, in the pressure medium guiding pathway rather than in a portion of the forced convection loop. This may reduce the cooling efficiency of the pressure medium in the load compartment, and consequently, may reduce the cooling rate, which is potentially undesirable.

[0006] In view of the above, the present invention is concerned with providing a pressing device that has the ability to effectively cool a pressure medium in the pressure vessel of the pressing device, for example, in the load compartment of the pressure vessel, during changes in the operating state of the pressing device, and especially during cooling phases at relatively high cooling rates.

[0007] To address this concern and at least one of other concerns, a pressing apparatus and a method within the pressing apparatus are provided according to the independent claim. Preferred embodiments are defined by the dependent claims.

[0008] According to a first aspect of the invention, a pressing apparatus is provided. The pressing apparatus may alternatively be referred to as a pressing device, or simply a pressing machine, or a hot isostatic press.

[0009] A pressing apparatus according to a first aspect of the invention includes a pressure vessel arranged to contain a pressure medium during use of the pressing apparatus. The pressure vessel includes a top closure and a bottom closure. The pressing apparatus includes a furnace chamber arranged within the pressure vessel and configured such that a pressure medium can enter and exit the furnace chamber. The furnace chamber at least partially defines a processing space arranged to accommodate articles (or more than one article). The pressing apparatus is configured to subject the articles(s) to a processing cycle including a cooling phase. The pressing apparatus includes at least one external convection loop pressure medium guiding passage in fluid communication with the furnace chamber and arranged to form an external convection loop (which may alternatively be referred to as an external cooling loop) within the pressure vessel. The external convection loop is arranged to guide the pressure medium, after exiting the furnace chamber, near the inner surfaces of the plurality of walls of the pressure vessel to a space between the furnace chamber and the bottom closure. The pressing apparatus includes a pressure medium flow generator arranged within the pressure vessel and in fluid communication with the furnace chamber. At least during the cooling phase of the processing cycle, the pressure medium flow generator is arranged to deliver pressure medium from at least the space between the furnace cavity and the bottom closure into the furnace cavity in order to cool the pressure medium in the processing space.

[0010] By guiding the pressure medium near the inner surface of the pressure vessel wall, heat transfer can occur from the pressure medium to the outside of the pressure vessel via the pressure vessel wall. Therefore, the temperature of the pressure medium in the external convection loop can be lower than the temperature of the pressure medium in the processing area. The external convection loop and the flow of the pressure medium generated by the pressure medium flow generator from at least the space between the furnace cavity and the bottom closure into the furnace cavity can form a forced convection loop inside the pressure vessel.

[0011] The pressing apparatus according to a first aspect of the invention includes at least one pressure medium guiding passage arranged within a pressure vessel, such that the pressure medium can be introduced from the furnace cavity into the space between the furnace cavity and the bottom closure member via only the at least one pressure medium guiding passage, and vice versa.

[0012] Since the pressure medium can flow from the furnace cavity into the space between the furnace cavity and the bottom closure via only at least one pressure medium guide passage, and vice versa, this means that if the pressure medium flows through at least one pressure medium guide passage, it does not need to pass through an external convection loop to enter the space between the furnace cavity and the bottom closure, and vice versa. Therefore, at least one pressure medium guide passage can be arranged within the pressure vessel such that the pressure medium can flow directly from the furnace cavity into the space between the furnace cavity and the bottom closure via at least one pressure medium guide passage, without needing to pass through an external convection loop. The external convection loop and at least one pressure medium guide passage can form a natural convection loop within the pressure vessel.

[0013] Each of at least one pressure medium guiding passage in the pressing device according to the first aspect of the invention is arranged such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage forms a gap (alternatively referred to as a slot) having a width, wherein each of the at least one pressure medium guiding passage has a corresponding width, and wherein the sum of the (multiple) widths (the (multiple) widths may be referred to as the corresponding (multiple) cross-sectional widths) is less than 4 mm.

[0014] Only one pressure medium guiding passage may be provided. In this case, the pressure medium guiding passage can be arranged such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage forms a gap with a width of less than 4 mm. If several pressure medium guiding passages exist, the total width of the corresponding cross-sections (i.e., the sum of the corresponding cross-sectional widths) can be less than 4 mm. If several pressure medium guiding passages exist, they can be arranged in parallel, allowing the pressure medium to flow directly from the furnace cavity into the space between the furnace cavity and the bottom closure via any one of the pressure medium guiding passages, without needing to pass through the external convection loop or through another (or some) of the pressure medium guiding passages.

[0015] The processing cycle may include loading the article into the pressing equipment, processing the article, and unloading the article from the pressing equipment. The processing cycle may include other parts or stages besides the cooling stage, such as a pressing stage and / or a heating stage (which may potentially be combined into one stage), which may precede the cooling stage.

[0016] During the cooling phase, the pressure medium, after leaving the furnace cavity, is typically guided in an external convection loop, where heat transfer from the pressure medium to the outside of the pressure vessel usually occurs via the walls of the pressure vessel and also via the pressure vessel's end closures(e.g., top closures). Therefore, the pressure medium is cooled before being re-entered into the furnace cavity by being conveyed through a pressure medium flow generator from at least the space between the furnace cavity and the bottom end closures. Thus, the pressure medium in the processing space can be effectively cooled.

[0017] The inventors have discovered that when the cooling rate is relatively high during the cooling phase (e.g., 100°C / min or higher in certain types of hot isostatic presses), there is a tendency for the pressure medium, after leaving the furnace cavity, to flow directly from the furnace cavity to the space between the furnace cavity and the bottom end closure via at least one pressure medium guide passage, without passing through the external convection loop, and then the pressure medium re-enters the furnace cavity through the space between the furnace cavity and the bottom end. This can reduce the cooling efficiency of the pressure medium in the processing space because, in this case, the pressure medium may not be guided near the inner surfaces(s) of the pressure vessel wall(s) and possibly the end closure(s), where a significant amount of heat transfer from the pressure medium to the outside of the pressure vessel can occur via the pressure vessel wall(s) and possibly the end closure(s). This, in turn, reduces the cooling rate of the pressure medium in the processing space, which may be undesirable.

[0018] The inventors have discovered that during the cooling phase at very high cooling rates (e.g., 100°C / min or higher in some types of hot isostatic presses), the flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity can become higher than the flow resistance of the pressure medium guided in at least one pressure medium guiding path into the space between the furnace cavity and the bottom closure (i.e., without passing through the external convection loop to enter the space between the furnace cavity and the bottom closure) just after leaving the furnace cavity. The higher the cooling rate of the pressure medium in the processing space, the higher the flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity. The increase in flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity can be proportional (or approximately proportional) to the increase in the cooling rate of the pressure medium in the processing space (i.e., the increase in the flow rate or velocity of the pressure medium in the external convection loop). However, by arranging each of at least one pressure medium guiding passages such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage is formed as a gap with a width, wherein each of the at least one pressure medium guiding passages has a corresponding width, and wherein the sum of the widths (of the plurality) is less than 4 mm, it is advantageous or ensured that even during the cooling phase at very high cooling rates (e.g., 100 °C / min or higher in some types of hot isostatic presses), the flow resistance of the pressure medium guided in at least one pressure medium guiding passage to the space between the furnace cavity and the bottom closure immediately after leaving the furnace cavity becomes higher than the flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity. Therefore, even at very high cooling rates, the cooling efficiency of the pressure medium in the processing space can be kept relatively high, and any undesirable reduction in the cooling rate of the pressure medium in the processing space can be mitigated or avoided. Therefore, a relatively high cooling rate can be achieved by arranging each of at least one pressure medium guiding passage such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage is formed as a gap with a width, wherein each of at least one pressure medium guiding passage has a corresponding width, and wherein the sum of the widths is less than 4 mm.

[0019] Furthermore, the product can be cooled while being subjected to relatively high pressure, which can be beneficial to the metallurgical properties of the treated product.

[0020] It can be noted that at least one pressure medium guiding passage will be completely restricted so that no pressure medium flow is allowed through it, and the tendency for the pressure medium, after leaving the furnace cavity, to flow directly from the furnace cavity to the space between the furnace cavity and the bottom closure via at least one pressure medium guiding passage without passing through the external convection loop, and then for the pressure medium to re-enter the furnace cavity into the space between the furnace cavity and the bottom closure, will not exist. However, completely restricting at least one pressure medium guiding passage is generally undesirable because this may completely or partially restrict the natural convection loop within the pressure vessel, which in turn may lead to an increase in moisture content within the pressure vessel, for example, in or on the components forming the furnace cavity, after the vacuum phase(s) of the processing cycle. Completely restricting at least one pressure medium guiding passage may result in a reduction in the performance of any vacuum system that can be used in the pressing equipment. Having a natural convection loop within the pressure vessel during the vacuum phase is beneficial because if the natural convection loop is closed during the vacuum phase, the efficiency of transporting any moisture out of the pressure vessel's interior may be reduced. It is also desirable for the pressure vessel to have a natural convection loop during the heating or loading phase of the processing cycle.

[0021] In the context of this application, the vacuum phase of a processing cycle refers to the initial phase of a processing cycle, which includes, after the articles(s) to be processed have been inserted into the pressure vessel, venting air and / or any other gas from the interior of the pressure vessel by one or more vacuum pumps.

[0022] It is important to note that in applications where only a relatively low cooling rate (e.g., significantly below 100°C / min) is required during the cooling phase, or where this is sufficient, the pressing equipment can be configured such that at least one pressure medium guide passage has a relatively large size. For example, if the pressing equipment is to be constructed as a relatively large hot isostatic press, and the anticipated operation involves cooling at a relatively low rate, the pressure medium guide passage can be arranged such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guide passage forms a gap typically 50-100 mm wide. Considering the tolerable tolerances, using such a large-sized pressure medium guide passage will likely also make the assembly of the pressing equipment components easier during the construction of the pressing equipment (different components of the pressing equipment may have little flexibility to accommodate variations in adjacent components).

[0023] The pressure medium may include, for example, a gas, such as an inert gas, like argon.

[0024] Pressure vessels may include, for example, a pressure cylinder (which may be simply referred to as a cylinder). The walls of the pressure vessel may include or be composed of the cylindrical walls of the pressure cylinder.

[0025] As described above, the pressure medium is guided on the inner surface of the pressure vessel wall and, possibly, near the end closures(s), allowing heat transfer from the pressure medium to the outside of the pressure vessel via the pressure vessel wall and, possibly, the end closures(s). During the passage of the pressure medium through the external convection loop, heat can be transferred from the pressure medium to other components or portions of the pressure vessel, such as those near the pressure vessel wall or the end closures(s), via which heat can be transferred from the pressure medium to the outside of the pressure vessel. Therefore, the temperature of the pressure medium in the external convection loop can be lower than the temperature of the pressure medium in the processing area.

[0026] For heat transfer from the pressure medium guided near the inner surface of the pressure vessel wall to the outside of the pressure vessel, the outer surface of the pressure vessel wall may be provided with channels, conduits, or fittings. These channels, conduits, or fittings may be arranged to connect to the outer surface of the pressure vessel wall and may extend parallel to the axial direction of the pressure vessel or extend coiled or spirally around the outer surface of the pressure vessel wall. A coolant for cooling the pressure vessel wall can be provided in the channels, conduits, or fittings, thereby cooling the pressure vessel wall and protecting it from harmful heat buildup during operation. The coolant in the channels, conduits, or fittings may include, for example, water, but other types or types of coolants are possible.

[0027] A prestressing device may be provided on the outer surface of the outer wall of the pressure vessel, and possibly on any channels, conduits, and / or fittings for coolant as described above. The prestressing device may be provided, for example, in the form of wires (e.g., made of steel), wound in multiple turns to form one or more bands around the outer surface of the outer wall of the pressure vessel and possibly also around any channels, conduits, and / or fittings for coolant that may be provided thereon, and preferably formed in several layers. The prestressing device can be arranged to apply radial compressive force to the pressure vessel.

[0028] In any of the disclosed embodiments of the invention, each of at least one pressure medium guiding passage may be arranged, for example, such that it has a specific cross-sectional area in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage, wherein the sum of the cross-sectional areas is less than 25% of the cross-sectional area of ​​the passage forming the external convection loop in the plane perpendicular to the flow direction of the pressure medium through the external convection loop (e.g., the cross-sectional area of ​​the passage forming the external convection loop is minimized in the plane perpendicular to the flow direction of the pressure medium through the external convection loop if the cross-sectional area varies along the length of the passage forming the external convection loop).

[0029] Each of at least one pressure medium guiding passage can, for example, be arranged such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage forms a gap with a width, wherein each of the at least one pressure medium guiding passage has a corresponding width, and wherein the sum of the widths(multiple) is in the range of 0.1 mm to 3.5 mm, or in the range of 0.1 mm to 2.5 mm, or in the range of 0.1 mm to 1.5 mm. Therefore, each of at least one pressure medium guiding passage can, for example, be arranged such that the sum of the corresponding cross-sectional widths(multiple) is in the range of 0.1 mm to 3.5 mm, or in the range of 0.1 mm to 2.5 mm, or in the range of 0.1 mm to 1.5 mm.

[0030] Each of at least one pressure medium guiding passage can be arranged such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage forms a gap with a width, wherein each of the at least one pressure medium guiding passage has a corresponding width, and wherein the sum of the widths(multiple) is 0.5 mm or less, for example 0.4 mm, 0.3 mm, 0.2 mm, or 0.1 mm. Therefore, each of the at least one pressure medium guiding passage can, for example, be arranged such that the sum of the widths of the corresponding(multiple) cross-sections is 0.5 mm or less, for example 0.4 mm, 0.3 mm, 0.2 mm, or 0.1 mm.

[0031] The pressure medium flow generator may include, for example, one or more fans, ejectors, and / or circulation devices. The pressure medium flow generator can control the flow rate of the pressure medium supplied to the furnace cavity from at least the space between the furnace cavity and the bottom closure. The cooling rate of the pressure medium in the processing space can be controlled at least partially by the flow rate of the pressure medium supplied to the furnace cavity from at least the space between the furnace cavity and the bottom closure.

[0032] Each of at least one pressure medium guiding passage can be arranged such that the sum of the respective cross-sectional widths, based on the estimated (or calculated, or determined) flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity at a cooling rate exceeding a selected cooling rate threshold, causes (or requires, or provides) the flow resistance of the pressure medium guided in the pressure medium guiding passage to the space between the furnace cavity and the bottom closure just after leaving the furnace cavity (i.e., before passing through the external convection loop) to become greater than the estimated flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity.

[0033] Therefore, the size of at least one pressure medium guiding passage can be selected based on the estimated flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity at a cooling rate exceeding a selected cooling rate threshold. As mentioned above, the higher the cooling rate of the pressure medium in the processing space, the higher the flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity. The increase in flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity can be proportional (or approximately proportional) to the increase in the cooling rate of the pressure medium in the processing space.

[0034] The selected cooling rate threshold can be, for example, 100°C / min or higher, such as 150°C / min, 200°C / min, or 500°C / min or higher.

[0035] The flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity is typically caused by friction between the outer layer of the pressure medium and the inner walls of the pipes, piping systems, channels, and / or passages that constitute (or include) the external convection loop, as well as friction between the pressure medium layers within the pressure medium. This results in increased flow rate in turbulent flow compared to laminar flow where there is no interlayer mixing. Resistance from the flow itself and friction at the inner walls lead to pressure drops in the external convection loop.

[0036] To estimate (or calculate, or determine) the flow resistance to the pressure medium guided in the external convection loop after leaving the furnace cavity, the pressure drop in the external convection loop can be determined, for example, using a Moody diagram. Assuming the inner walls of the pipes, piping systems, channels, and / or passages constituting (or included in) the external convection loop can be considered as piping systems, a Moody diagram can be used to correlate the Darcy-Weisbach friction coefficient f, the Reynolds number Re, and the surface roughness of the inner walls of the pipes, piping systems, channels, and / or passages constituting (or included in) the external convection loop. The pressure drop in the external convection loop is proportional to f. For laminar flow, f = 64 / Re, but for turbulent flow (typically the cooling stage), the relationship between f, Re, and surface roughness is more complex. Different models can be used to model the relationship between f, Re, and surface roughness in turbulent flow.

[0037] If the cooling rate of the pressure medium in the processing space increases, the flow rate of the pressure medium in the external convection loop will increase, while the density and flow rate (f) of the pressure medium will generally decrease. The increase in the flow rate of the pressure medium in the external convection loop will typically have a greater impact on the pressure drop in the external convection loop than changes in other quantities such as f and the density of the pressure medium.

[0038] (Multiple) gaps can be straight and / or curved. For example, at least one pressure medium guiding passage may have one or more bends, bends, twists, etc., along its length. Providing one or more bends, bends, twists, etc., to at least one pressure medium guiding passage facilitates achieving a larger pressure drop in at least one pressure medium guiding passage. Increasing the length of at least one pressure medium guiding passage will generally result in an increase in the pressure drop in at least one pressure medium guiding passage.

[0039] Each of at least one pressure medium guiding passage can be arranged such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage forms a gap having at least a portion of a ring (e.g., at least a portion of a circular ring, at least a portion of an elliptical ring), or a rectangle. In principle, different portions of the gap can have different shapes. Different shapes may include a portion of a ring (e.g., a portion of a circular ring, a portion of an elliptical ring), or a rectangle.

[0040] The pressure medium flow generator can be arranged to deliver pressure medium from another space in the pressing device, at least during the cooling phase of the processing cycle. During at least a portion of the cooling phase, the temperature of the pressure medium in the other space can be lower than the temperature of the pressure medium in the processing space, such that by delivering pressure medium from the other space to the processing space during the cooling phase, the temperature of the pressure medium in the processing space decreases.

[0041] The other space in the aforementioned pressing equipment may or may not be a space within the pressure vessel. This other space may be defined, for example, by a space or area within the pressure vessel that is different from the processing space and may be located at a distance. As mentioned above, the other space does not necessarily have to be a space within the pressure vessel; it can be a space outside the pressure vessel within the pressing equipment, such as a space or area defined by a pressure medium source arranged outside the pressure vessel. The other space in the aforementioned pressing equipment may include at least a portion of the external convection loop.

[0042] The external convection loop can be arranged to guide the pressure medium into the space between the top closure and the furnace cavity after it has left the furnace cavity. The external convection loop can be further arranged to guide the pressure medium from the space between the top closure and the furnace cavity near the inner surface of the pressure vessel wall into the space between the furnace cavity and the bottom closure.

[0043] The pressing equipment may include multiple external convection loop pressure medium guiding passages, which are in fluid communication with the furnace cavity and are arranged to form external convection loops.

[0044] The furnace cavity may be at least partially surrounded by an insulating shell, which may be arranged to allow pressure medium to enter and exit the furnace cavity. The insulating shell may include an insulating portion, a shell that may at least partially surround the insulating portion, and possibly a bottom insulating portion.

[0045] A portion of the external convection loop may include a first external convection loop pressure medium guiding passage, which may be formed between at least a portion of the housing and the insulation portion, and the first external convection loop pressure medium guiding passage may be arranged to guide the pressure medium to the space between the top closure and the furnace cavity after it has left the furnace cavity.

[0046] Another portion of the external convection loop may include a second external convection loop pressure medium guiding passage, which may be arranged to guide the pressure medium from the space between the top closure and the furnace cavity near the inner surface of the pressure vessel wall to the space between the bottom insulation portion and the bottom closure. The space between the bottom insulation portion and the bottom closure may constitute or be included within the space between the furnace cavity and the bottom closure.

[0047] At least one pressure medium guiding passage can be arranged such that the pressure medium can be introduced from the furnace cavity into the space between the bottom insulation portion and the bottom closure portion only through at least one pressure medium guiding passage, and vice versa.

[0048] At least one pressure medium guiding passage may be defined at least partially by at least one gap formed between the bottom insulation portion and the housing. The at least one gap formed between the bottom insulation portion and the housing may be realized or implemented, for example, by one or more components arranged between the bottom insulation portion and the housing. The one or more components may include, for example, one or more discs, rings, and / or gaskets. For example, each or any of the one or more components may be attached only to the bottom insulation portion or only to the housing, or possibly to both the bottom insulation portion and the housing.

[0049] For example, the bottom insulation portion may include a plate-like component.

[0050] At least one pressure medium guiding passage may be defined at least partially by at least one gap formed between the edge of the plate-like member and the surface of the housing.

[0051] The plate-like member may include a first outer surface, a second outer surface opposite to the first outer surface, and an edge surface extending between the first and second outer surfaces. The bottom insulating portion may include a disc or annulus attached to one of the first and second outer surfaces, wherein the size of the disc or annulus may be determined such that the disc or annulus extends beyond at least a portion of the boundary of the first or second outer surface, possibly beyond the entire boundary of the first or second outer surface. At least one pressure medium guiding passage may be defined at least partially by a gap formed between the edge of the disc or annulus and the surface of the housing.

[0052] The disc or ring and the plate-like component can be separate parts. However, the disc or ring can be an integral part of the plate-like component.

[0053] The pressing device may include a ring that can be attached to the surface of the housing. The ring may be attached to the surface of the housing, and its dimensions are determined such that at least one pressure medium guiding passage is at least partially defined by a gap formed between the ring (e.g., its edge) and the bottom insulation portion.

[0054] The pressing device may include a gasket, which may be, for example, annular in shape. The gasket may be disposed between the surface of the housing and the bottom insulation portion. The outer edge of the gasket may be connected to the surface of the housing. The inner edge of the gasket may be connected to the bottom insulation portion. At least one pressure medium guiding passage may be defined at least partially by a gap formed in the gasket. Possibly, the gasket may not be connected to both the housing and the bottom insulation portion. For example, the outer edge of the gasket may be connected to the surface of the housing, but the inner edge of the gasket may not be connected to the bottom insulation portion. According to another example, the inner edge of the gasket may be connected to the bottom insulation portion, but the outer edge of the gasket may not be connected to the surface of the housing.

[0055] According to a second aspect of the invention, a pressing apparatus is provided. The pressing apparatus includes a pressure vessel arranged to contain a pressure medium during use of the pressing apparatus. The pressure vessel includes a top closure and a bottom closure. The pressing apparatus includes a furnace chamber arranged within the pressure vessel, allowing the pressure medium to enter and exit the furnace chamber. The furnace chamber at least partially defines a processing space arranged to accommodate at least one article of work. The pressing apparatus is configured to subject the at least one article of work to a processing cycle including a cooling phase. The pressing apparatus includes at least one external convection loop pressure medium guiding passage, which is in fluid communication with the furnace chamber and arranged to form an external convection loop within the pressure vessel. The external convection loop is arranged to guide the pressure medium, after exiting the furnace chamber, near the inner surface of one or more walls of the pressure vessel to a space between the furnace chamber and the bottom closure. The pressing apparatus includes a pressure medium flow generator arranged within the pressure vessel and in fluid communication with the furnace chamber. At least during the cooling phase of the processing cycle, a pressure medium flow generator is arranged to deliver pressure medium from at least the space between the furnace cavity and the bottom closure into the furnace cavity to cool the pressure medium in the processing space. The pressing apparatus includes at least one pressure medium guide passage arranged within the pressure vessel, such that pressure medium can flow from the furnace cavity into the space between the furnace cavity and the bottom closure solely through the at least one pressure medium guide passage, and vice versa.

[0056] A pressing apparatus according to a second aspect of the invention includes one or more controllable pressure medium flow restrictors arranged to selectively and controllably prevent or impede the flow of pressure medium in at least one pressure medium passage. The pressing apparatus includes a control unit communicatively connected to the one or more controllable pressure medium flow restrictors for controlling their operation. The control unit is configured to control the one or more controllable pressure medium flow restrictors to prevent or impede the flow of pressure medium in at least one pressure medium guide passage during a cooling phase of a processing cycle, and not to prevent or impede the flow of pressure medium in at least one pressure medium guide passage during another or more phases of the processing cycle, the other or more phases including at least one of a heating phase, a containing phase, a pumping phase (e.g., a pressure medium pumping phase), and a vacuum phase, or any combination thereof (where two or possibly more phases occur simultaneously, e.g., a combined pumping and heating phase, wherein pumping and heating occur simultaneously).

[0057] By preventing or impeding the flow of the pressure medium in at least one pressure medium guide passage during the cooling phase (e.g., completely or substantially completely preventing or impeding the flow of the pressure medium in at least one pressure medium guide passage), the following situation can be significantly mitigated or avoided: the pressure medium, after leaving the furnace cavity, flows directly from the furnace cavity to the space between the furnace cavity and the bottom closure via at least one pressure medium guide passage without passing through the external convection loop, and then the pressure medium re-enters the furnace cavity into the space between the furnace cavity and the bottom. Furthermore, by not preventing or impeding the flow of the pressure medium in at least one pressure medium guide passage during another phase (including at least one of the heating phase and the vacuum phase), it can be ensured that a natural convection loop exists within the pressure vessel during, for example, the heating phase, the filling phase, the pumping phase, and / or the vacuum phase.

[0058] Multiple controllable pressure medium flow restrictors may, for example, include one or more adjustable flow valves. These adjustable flow valves may, for example, be arranged in or on at least one pressure medium guide passage. For instance, adjustable flow valves may be arranged in or on each of at least one pressure medium guide passage. Alternatively or additionally, multiple controllable pressure medium flow restrictors may include one or more adjustable valves, such as one or more solenoid valves. Alternatively or additionally, another type of valve may be used, for example, pneumatic valves and / or electric valves. The use of multiple adjustable valves (or other types of multiple controllable pressure medium flow restrictors) is desirable because it facilitates uniform flow of the pressure medium through at least one pressure medium guide passage.

[0059] The control unit may include, for example, any suitable central processing unit (CPU), microcontroller, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), etc., or any combination thereof. The control unit may optionally be capable of executing software stored in a computer program product, for example, in the form of memory. The memory may be, for example, any combination of read-write memory (RAM) and read-only memory (ROM). The memory may include permanent storage devices, such as magnetic storage, optical storage, solid-state storage, or remotely mounted memory, or any combination thereof.

[0060] The communication connection between the control unit and one or more controllable pressure medium flow restrictors can be realized or implemented, for example, by any suitable wired and / or wireless communication device or technology known in the art.

[0061] According to a third aspect of the invention, a method in a pressing apparatus is provided. The pressing apparatus includes a pressure vessel arranged to contain a pressure medium during use of the pressing apparatus. The pressure vessel includes a top closure and a bottom closure. The pressing apparatus includes a furnace chamber arranged within the pressure vessel, allowing the pressure medium to enter and exit the furnace chamber. The furnace chamber at least partially defines a processing space arranged to accommodate at least one article of work. The pressing apparatus is configured to subject the at least one article of work to a processing cycle including a cooling phase. The pressing apparatus includes at least one external convection loop pressure medium guiding passage in fluid communication with the furnace chamber and arranged to form an external convection loop within the pressure vessel. The external convection loop is arranged to guide the pressure medium, after exiting the furnace chamber, near the inner surface of one or more walls of the pressure vessel to a space between the furnace chamber and the bottom closure. The pressing apparatus includes a pressure medium flow generator arranged within the pressure vessel and in fluid communication with the furnace chamber. At least during the cooling phase of the processing cycle, a pressure medium flow generator is arranged to deliver pressure medium from at least the space between the furnace cavity and the bottom closure into the furnace cavity to cool the pressure medium in the processing space. The pressing apparatus includes at least one pressure medium guide passage arranged within the pressure vessel, such that pressure medium can flow from the furnace cavity into the space between the furnace cavity and the bottom closure solely via the at least one pressure medium guide passage, and vice versa. The pressing apparatus includes one or more controllable pressure medium flow restrictors arranged to selectively and controllably prevent or impede the flow of pressure medium in at least one pressure medium passage.

[0062] The method according to a third aspect of the invention includes controlling one or more controllable pressure medium flow restrictors to prevent or impede the flow of pressure medium in at least one pressure medium guide passage during a cooling phase of a processing cycle, and not preventing or impeding the flow of pressure medium in at least one pressure medium guide passage during another or more phases of the processing cycle, the other or more phases including at least one of a heating phase, a containment phase, a pumping phase, and a vacuum phase, or any combination thereof (wherein, two or possibly more phases occur simultaneously, for example, a combined pumping and heating phase, wherein pumping and heating occur simultaneously).

[0063] According to a fourth aspect of the invention, a computer program is provided. The computer program includes instructions that, when executed by one or more processors included in a control unit, cause the control unit to perform the method according to a third aspect of the invention.

[0064] According to a fifth aspect of the invention, a processor-readable medium is provided. The processor-readable medium has a computer program loaded thereon, wherein the computer program includes instructions that, when executed by one or more processors included in a control unit, cause the control unit to perform a method according to a third aspect of the invention.

[0065] Each or any of the one or more processors may include, for example, a CPU, a microcontroller, a DSP, an ASIC, an FPGA, or any combination thereof. Processor-readable media may include, for example, a digital versatile disc (DVD), or a floppy disk, or any other suitable type of processor-readable device or processor-readable (digital) medium, such as, but not limited to, memory (e.g., non-volatile memory), hard disk drive, optical disc (CD), flash memory, magnetic tape, universal serial bus (USB) storage device, Zip drive, etc.

[0066] Further objects and advantages of the invention are described below by way of illustrative embodiments. It should be noted that the invention relates to all possible combinations of the features referenced in the claims. Further features and advantages of the invention will become clear when examined in conjunction with the appended claims and the description herein. Those skilled in the art will recognize that different features of the invention can be combined to create embodiments other than those described herein. Attached Figure Description

[0067] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings.

[0068] Figures 1 to 4 Each of these is a schematic partial cross-sectional side view of a pressing device according to an embodiment of the present invention.

[0069] These figures are schematic, not necessarily drawn to scale, and generally only show the parts necessary to illustrate embodiments of the invention, where other parts may be omitted or are merely suggested. Detailed Implementation

[0070] The invention will now be described below with reference to the accompanying drawings, in which exemplary embodiments of the invention are illustrated. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will convey the scope of the invention to those skilled in the art.

[0071] Figure 1 This is a schematic partial cross-sectional side view of a pressing apparatus 100 according to an embodiment of the present invention. The pressing apparatus 100 is arranged to process at least one article by pressing, for example by hot pressing such as hot isostatic pressing (HIP).

[0072] The pressing device 100 includes a pressure vessel comprising a pressure cylinder 1 and a top closure 8 and a bottom closure 9, or more generally, a first end closure and a second end closure, respectively. It should be understood that the pressure vessel (hereinafter collectively referred to by reference numerals 1, 8, and 9) may include components not in... Figure 1 Additional parts, components, or elements shown in the diagram. Pressure vessels 1, 8, and 9 are arranged to contain pressure media during use of the pressing equipment 100.

[0073] Pressure vessels 1, 8, and 9 include a furnace chamber 18. The furnace chamber 18 is arranged within pressure vessels 1, 8, and 9 such that a pressure medium can enter and exit the furnace chamber 18. The furnace chamber 18 may include a furnace, or a heater or heating element, for heating the pressure medium in the pressure vessel, for example, during a pressing phase of a processing cycle. Figure 1 The furnace is schematically indicated by reference numeral 14 in the accompanying drawings. The components of furnace 14 are... Figure 1 The two identical elements are shown in the accompanying drawing, indicated by reference numeral 14. However, it should be understood that furnace 14 can, in principle, be supplied in any number of parts, and not only as shown in the drawing. Figure 1 The two components shown, or fewer or less than two components. According to... Figure 1 In the embodiment of the invention shown, furnace 14 is arranged in the lower portion of furnace cavity 18. It should be understood that different configurations and arrangements of furnace 14 relative to furnace cavity 18 (e.g., within it) are possible. For example, as... Figure 1 As an alternative or addition to the arrangement of the furnace 14 shown, the furnace 14 may be arranged in the upper portion of the furnace cavity 18, for example, in... Figure 1 The pressure medium guiding passage 32 shown herein will be further described below. In any embodiment of the invention disclosed herein, the furnace 14 can be used in any manner in its arrangement relative to the furnace cavity 18 (e.g., within it). In the context of this application, the term "furnace" refers to an element or device for providing heating, while the term "furnace cavity" refers to the furnace, possibly also the load compartment and any area or zone where articles are located. Figure 1 As shown, the furnace cavity 18 may not occupy the entire internal space of pressure vessels 1, 8, and 9. Instead, an intermediate space 10 can be left around the furnace cavity 18, forming an internal passage 10 for the pressure vessels 1, 8, and 9. The intermediate space 10 forms a pressure medium guiding passage 10. During the operation of the pressing equipment 100, the temperature inside the intermediate space 10 may be lower than the temperature inside the furnace cavity 18, but the intermediate space 10 and the furnace cavity 18 may be at equal or substantially equal pressures.

[0074] Pressure vessels 1, 8, and 9 include a processing space. The processing space may be defined, for example, at least partially by a furnace cavity 18. For instance, the processing space may include or be constituted by the interior of the furnace cavity 18. The processing space is arranged to accommodate articles 5 (or possibly several articles). Figure 1 In the illustrated embodiment of the invention, a load compartment 19 contained in a furnace cavity 18 is arranged to accommodate a product 5. The processing space may include or be constituted by the interior of the load compartment 19. The pressing apparatus 100 is configured to subject the product 5 to a processing cycle that includes a cooling phase.

[0075] The outer surfaces of the outer walls of pressure vessels 1, 8, and 9 may be provided with channels, conduits, or fittings, etc. Figure 1 (Not shown), these channels, conduits, or fittings may, for example, be arranged to connect to the outer surface of the outer wall of pressure vessels 1, 8, 9, and may be arranged to extend parallel to the axial direction of pressure vessels 1, 8, 9, or to extend coiled or spirally around the outer surface of the outer wall of pressure vessels 1, 8, 9. A coolant for cooling the walls of pressure vessels 1, 8, 9 may be provided in the channels, conduits, or fittings, thereby cooling the walls of pressure vessels 1, 8, 9 to protect them from harmful heat buildup during operation. The coolant in the channels, conduits, or fittings may include, for example, water, but other types or types of coolants are possible. Figure 1 The arrows on the outside of pressure vessels 1, 8, and 9 indicate exemplary flow of coolant in channels, conduits, or fittings provided on the outer surface of the outer wall of pressure vessels 1, 8, and 9.

[0076] A prestressing device may be provided on the outer surface of the outer wall of the pressure cylinder 1, and possibly on any channels, conduits, and / or fittings for coolant as described above. The prestressing device may be provided, for example, in the form of a wire (e.g., made of steel). Figure 1 (Not shown in the image), these lines are wound multiple times around the outer surface of the outer wall of the pressure cylinder 1, and may also be wrapped around it, forming one or more zones, preferably divided into several layers, for any channels, conduits and / or fittings that may be provided for the coolant. The prestressing device can be arranged to apply radial compressive force to the pressure cylinder 1.

[0077] Even in Figure 1 Although not explicitly stated, pressure vessels 1, 8, and 9 can also be arranged such that they can be opened and closed, allowing any article of art to be inserted into or removed from pressure vessels 1, 8, and 9. The arrangement of pressure vessels 1, 8, and 9 to enable their opening and closing can be achieved in a variety of different ways known in the art. Although in Figure 1 It is not explicitly stated, but one or both of the top closure 8 and the bottom closure 9 may be arranged such that it or they can be opened and closed.

[0078] As will be described in more detail below, the pressing apparatus 100 includes external convection loop pressure medium guiding passages 10, 11, which are in fluid communication with the furnace cavity 18 and are arranged to form an external convection loop within the pressure vessels 1, 8, 9. The external convection loop is arranged to guide the pressure medium, after it has left the furnace cavity 18, near the inner surface 23 of the plurality of walls 22 of the pressure vessels 1, 8, 9, into the space 16 between the furnace cavity 18 and the bottom closure 9. Figure 1 As indicated in the document, the (multiple) walls 22 of pressure vessels 1, 8, and 9 may be the (multiple) outer walls of pressure vessels 1, 8, and 9.

[0079] according to Figure 1 In the illustrated embodiment of the invention, the furnace chamber 18 is surrounded by an insulated outer shell (hereinafter referred to by reference numerals 2, 4, and 7), which is arranged to allow a pressure medium to enter and exit the furnace chamber 18. Further according to... Figure 1 In the embodiment of the invention shown, the heat-insulating shells 2, 4, and 7 include a heat-insulating portion 7, a housing 2 partially surrounding the heat-insulating portion 7, and a bottom heat-insulating portion 4. Not all elements of the heat-insulating shells 2, 4, and 7 can be arranged to be heat-insulated or have heat-insulating properties. For example, the housing 2 may not need to be arranged to be heat-insulated or have heat-insulating properties. The heat-insulating shells 2, 4, and 7 surrounding the furnace cavity 18 may save energy during the heating phase of the processing cycle, through which the pressing equipment 100 can be configured to subject the articles 5. The heat-insulating shells 2, 4, and 7 may also promote or ensure that convection occurs in a more orderly manner. Because the furnace cavity 18 has a vertically elongated shape in the illustrated embodiment of the invention, the heat-insulating shells 2, 4, and 7 can prevent the formation of temperature gradients (e.g., horizontal temperature gradients) that may be difficult to monitor and control.

[0080] according to Figure 1 The illustrated embodiment of the invention includes a portion of the external convection loop comprising a first external convection loop pressure medium guiding passage 11 formed between a portion of the housing 2 and the insulation portion 7, respectively. This first external convection loop pressure medium guiding passage is arranged to guide the pressure medium, after it has left the furnace cavity 18, into the space 17 between the top closure 8 and the furnace cavity 18. Further according to... Figure 1In the illustrated embodiment of the invention, another portion of the external convection loop includes a second external convection loop pressure medium guiding passage, which, according to the illustrated embodiment, is constituted by a pressure medium guiding passage 10. The second external convection loop pressure medium guiding passage 10 is arranged to guide the pressure medium from the space 17 between the top closure 8 and the furnace cavity 18 near the inner surface 23 of the (plural) walls 22 of the pressure vessels 1, 8, 9 to the space between the bottom insulation portion 4 and the bottom closure 9. Figure 1 In the embodiment of the present invention shown, the space between the bottom heat insulation portion 4 and the bottom end seal 9 constitutes the aforementioned space 16 between the furnace cavity 18 and the bottom end seal 9.

[0081] The pressure medium used in pressure vessels 1, 8, 9 or pressing equipment 100 may, for example, comprise or consist of a liquid or gaseous medium having a relatively low chemical affinity to the articles(s) to be processed in pressure vessels 1, 8, 9. The pressure medium may, for example, comprise a gas, such as an inert gas like argon.

[0082] like Figure 1 As indicated, the pressure medium can exit the load compartment 19 at the top portion and then be guided in the pressure medium guiding passage 32 between the wall of the load compartment 19 and the wall of the insulation portion 7. Afterward, the pressure medium can enter the pressure medium guiding passage 11 through the plurality of openings 6 between the insulation portion 7 and the housing 2. The plurality of openings 6 between the insulation portion 7 and the housing 2 can be at or approximately at the level of the bottom insulation portion 4, such as... Figure 1 As shown in the diagram. However, it should be understood that the multiple openings 6 between the insulation portion 7 and the housing 2 can be positioned relative to... Figure 1 The different locations shown in the figures. This applies to any disclosed embodiment of the invention, such as the embodiment shown in the figures. The openings 6 between the insulation portion 7 and the housing 2 may be provided with one or more valves or any other type of adjustable flow valve or controllable pressure medium flow restriction device.

[0083] like Figure 1 As shown, the pressure medium entering the pressure medium guiding passage 11 through the (multiple) openings between the heat insulation portion 7 and the housing 2 is guided to the top closure 8 in the pressure medium guiding passage 11. At the top closure, the pressure medium can leave the pressure medium guiding passage 11 and the heat insulation housings 2, 4, and 7 through an opening in the housing 2 (e.g., the central opening in the housing 2).

[0084] The pressure medium guiding passage, defined by the inner surface of the top closure 8 and the space 17 partially defined by the pressure medium guiding passage 10, is arranged to allow the pressure medium to pass near the top closure 8 after exiting the opening in the housing 2 and in the (multiple) walls 22 of the pressure vessels 1, 8, 9 (e.g., respectively as shown in the image). Figure 1 The pressure cylinder 1 shown in the figure is guided to the space 16 between the furnace cavity 18 and the bottom closure 9 near the inner surface 23 of the (multiple) walls.

[0085] What will be understood is... Figure 1 Exemplary embodiments of the invention are shown, and variations may be made, for example, regarding how the pressure medium is guided within the pressure vessels 1, 8, and 9. For instance, a heat-absorbing element, as disclosed in WO 2018 / 171884 A1, indicated by reference numeral 20 and shown in the drawings of WO 2018 / 171884 A1, may be provided between the opening in the housing 2 and the upper portion of the insulation portion 7. Alternatively or additionally, a heat exchange element, as disclosed in WO 2019 / 149379 A1, arranged in the top closure 8, may be provided, for example, a heat exchange element indicated by reference numeral 170 and shown in the drawings of WO 2019 / 149379 A1.

[0086] Thus, an external convection loop can be formed by at least the pressure medium guiding passage 10 and the pressure medium guiding passage 11. In a part of the external convection loop, the pressure medium is guided near the inner surface of the top closure 8 and the inner surface 23 of the inner surface of the walls 22 of the pressure vessels 1, 8, 9 or the pressure cylinder 1. The amount of heat energy transferred from the pressure medium as it passes through its inner surface near the top closure 8 and the inner surface 23 of the wall 22 of the pressure vessel 1, 8, 9 or pressure cylinder 1 can depend on at least one of the following: the velocity of the pressure medium; the amount of pressure medium in direct contact with the inner surface 8 and the inner surface 23 of the wall 22 of the pressure vessel 1, 8, 9 or pressure cylinder 1; the relative temperature difference between the pressure medium and the inner surface 23 of the wall 22 of the top closure 8 and pressure vessel 1, 8, 9 or pressure cylinder 1; the thickness of the top closure 8 and the thickness of the wall 22 of the pressure vessel 1, 8, 9 or pressure cylinder 1; and any coolant flow (in) the channels, conduits or fittings provided on the outer surface of the wall 22 of the pressure vessel 1, 8, 9 or pressure cylinder 1. Figure 1 The temperature is indicated by the arrow on the outside of pressure cylinder 1.

[0087] In the pressure medium guiding passage 10, the pressure medium, guided back towards the furnace cavity 18, enters the space 16 between the furnace cavity 18 (or the bottom insulation portion 4) and the bottom closure 9. The furnace cavity 18 can be arranged such that the pressure medium can enter the furnace cavity 18 from the space 16 and exit the furnace cavity 18 into the space. For example, and according to Figure 1 In the illustrated embodiment of the invention, the furnace cavity 18 may have an opening in the bottom heat insulation portion 4, thereby allowing pressure medium to flow into (or out of) the furnace cavity 18. Further according to... Figure 1 In the illustrated embodiment of the invention, a pressure medium guiding passage 12 (e.g., including a conduit 12) is arranged to extend through the bottom insulation portion 4, wherein the lower (or first) opening of the pressure medium guiding passage or conduit 12 is below the bottom insulation portion 4 (and possibly within space 16, according to the illustrated embodiment), and the upper (or second) opening of the pressure medium guiding passage or conduit 12 is at the upper surface of the bottom insulation portion 4 (and possibly aligned with an opening in the load compartment 19, according to the illustrated embodiment). The lower (or first) opening of the pressure medium guiding passage or conduit 12 may, for example, be provided with an adjustable pressure medium flow restriction device, such as one or more adjustable flow valves or valves. Possibly, the upper (or second) opening of the pressure medium guiding passage or conduit 12 may be spaced a distance from the upper surface of the bottom insulation portion 4.

[0088] The pressure medium guiding passage 32 of the furnace cavity 18 and the pressure medium guiding passage formed between the load compartment 19 and the bottom insulation portion 4 are in fluid communication with the load compartment 19 to partially form an internal convection loop, wherein the pressure medium in the internal convection loop is guided through the load compartment 19 and the pressure medium guiding passage 32 of the furnace cavity 18 and the pressure medium guiding passage formed between the load compartment 19 and the bottom insulation portion 4 and returns to the load compartment 19, or vice versa.

[0089] according to Figure 1 The embodiment of the invention shown in the figure includes a pressure medium circulation generator 15 configured to circulate the pressure medium within pressure vessels 1, 8, and 9, wherein the pressure medium passes through a furnace cavity 18 during circulation. The pressure medium circulation generator 15 is optional and may be omitted. Figure 1 The illustrated embodiment of the invention shows a pressure medium circulation generator 15 including a fan 15, etc., for circulating the pressure medium within the furnace chamber 18. Alternatively or additionally, the pressure medium circulation generator 15 may include another or other type of pressure medium circulation generator besides a fan, such as one or more injectors. Further according to Figure 1In the illustrated embodiment of the invention, the pressure medium circulation generator 15 may be arranged, for example, at an opening in the load compartment 19, above the bottom insulation portion 4, allowing the pressure medium to flow into or out of the load compartment 19. The pressure medium circulation generator 15 may be controllable at least with respect to its operating rate. The operating rate of the pressure medium circulation generator 15 may include, for example, the revolutions per minute (rpm) of the pressure medium circulation generator 15, such as if the pressure medium circulation generator includes or is constituted by one or more fans, but another or other types of operating rates are contemplated depending on the nature of a particular embodiment of the pressure medium circulation generator 15. The pressure medium circulation generator 15 may be configured to selectively control the flow rate of the pressure medium in the aforementioned internal convection loop.

[0090] The pressing apparatus 100 may include a pressure medium flow generator 13 disposed in pressure vessels 1, 8, 9 and in fluid communication with the furnace cavity 18. At least during the cooling phase of the processing cycle, the pressure medium flow generator 13 may be arranged to deliver pressure medium from at least the space 16 between the furnace cavity 18 and the bottom closure 4 into the furnace cavity 18 to cool the pressure medium in the processing space.

[0091] according to Figure 1 The illustrated embodiment of the invention shows a pressure medium flow generator 13 including an ejector device 13, which in... Figure 1 This is only shown illustratively. For example... Figure 1As shown, pressure medium from pressure medium guide passage 10 entering space 16 can be drawn into pressure medium flow generator 13, and then injected from flow generator 13 into pressure medium guide passage or conduit 12, which then delivers the pressure medium to furnace chamber 18. For example, pressure medium flow generator 13, including injector device 13, can include a single-stage injector or a multi-stage injector (e.g., a two-stage injector). A single-stage injector means that pressure medium flow generator 13 or injector device 13 includes one flow generator or injector. A multi-stage injector means that pressure medium flow generator 13 or injector device 13 includes multiple flow generators or injectors arranged such that the output of at least one flow generator or injector is input to another flow generator or injector. Multiple flow generators or injectors can be arranged, for example, in series. For example, the pressure medium flow generator 13 or ejector device 13 may include a primary flow generator or ejector and a secondary flow generator or ejector, wherein the primary flow generator or ejector is arranged to draw pressure medium from the pressure medium guide passage 10 into the entry space 16. The output of the primary flow generator or ejector may be input to the secondary flow generator or ejector, and the output of the secondary flow generator or ejector may be ejected into the pressure medium guide passage or conduit 12. Alternatively or additionally, the pressure medium flow generator 13 may, for example, include one or more fans, pumps, etc., that may be arranged to allow pressure medium to flow into the pressure medium guide passage or conduit 12.

[0092] The pressing device 100 includes at least one pressure medium guiding passage 21 arranged within pressure vessels 1, 8, and 9, such that pressure medium can flow from furnace cavity 18 into space 16 between furnace cavity 18 and bottom closure member 9 via only at least one pressure medium guiding passage 21, and vice versa. Each of the at least one pressure medium guiding passage 21 is arranged such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage 21 forms a gap with width W, wherein each of the at least one pressure medium guiding passage 21 has a corresponding width, and wherein the sum of the widths is less than 4 mm.

[0093] according to Figure 1The illustrated embodiment of the invention includes a single pressure medium guiding passage 21 arranged in pressure vessels 1, 8, and 9. (Note that pressure vessels 1, 8, and 9 have a cylindrical geometry.) In this case, the pressure medium guiding passage 21 is arranged such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage 21 forms a gap with a width of less than 4 mm. If several such pressure medium guiding passages are arranged in pressure vessels 1, 8, and 9, the total width of the corresponding cross-sections (i.e., the sum of the corresponding cross-sectional widths) can be less than 4 mm.

[0094] The dimensions of other parts of the pressing device 100 can vary and can depend on the specific type of pressing device. Figure 1 The pressure vessels 1, 8, and 9 shown have a cylindrical geometry. According to a non-limiting example, the inner diameter of pressure cylinder 1 can be approximately 600 mm. The width of pressure medium guiding passage 11 can be approximately 10 mm, and the width of pressure medium guiding passage 10 can also be approximately 10 mm. The inner diameter of the heat insulation portion 7 can be approximately 500 mm. It should be understood that these dimensions are exemplary and non-limiting, and can vary between different types of pressing equipment.

[0095] like Figure 1 As shown, the pressure medium guiding passage 21 is arranged such that the pressure medium can flow from the furnace cavity 18 into the space 16 between the bottom insulation portion 4 and the bottom end closure 9 solely through the pressure medium guiding passage 21, and vice versa. The fact that the pressure medium can flow from the furnace cavity 18 into the space 16 solely through the pressure medium guiding passage 21, and vice versa, means that if the pressure medium passes through the pressure medium guiding passage 21, the pressure medium does not need to pass through an external convection loop to enter the space 16 from the furnace cavity 18, and vice versa.

[0096] according to Figure 1 The illustrated embodiment of the invention shows that the bottom heat insulation portion 4 includes a plate-like member comprising a first outer surface 25, a second outer surface 26 opposite to the first outer surface, an edge surface 27 extending between the first and second outer surfaces 25, and a disc 20 attached to the second outer surface 26 (or possibly alternatively to the first outer surface 25). The disc 20 may be attached to the second outer surface 26 (or possibly alternatively to the first outer surface 25), for example, by welding. The dimensions of the disc 20 are determined such that the disc extends beyond at least a portion of the boundary of the second outer surface 26 (or possibly alternatively the first outer surface 25). Figure 1As shown, the pressure medium guiding passage 21 is defined by the gap formed between the edge of the disc 20 and the surface of the housing 2. Instead of the disc 20, an annulus may be provided. Furthermore, the disc (or annulus) and the plate-like member may not be separate components, but rather the disc (or annulus) may be an integral part of the plate-like member. Figure 1 As shown, the disc 20 (or ring) may not be attached to the housing 2 or the insulation portion 7.

[0097] It should be understood that Figure 1 The pressure medium guiding passage 21 shown is exemplary, and it can be implemented in different ways. For example, the pressure medium guiding passage 21 may be defined by a gap formed between the bottom heat insulation portion 4 and the housing 2. More specifically, the bottom heat insulation portion 4 may include a plate-like member, and the pressure medium guiding passage 21 may be defined by a gap formed between the edge of the plate-like member and the surface of the housing 2. (See reference...) Figure 2 and Figure 3 Other exemplary implementations of the pressure medium guiding passage 21 are shown and described.

[0098] Figure 2 This is a schematic partial cross-sectional side view of the pressing device 100 according to an embodiment of the present invention. Figure 2 The pressing equipment 100 shown in the image is similar to... Figure 1 The pressing equipment 100 shown in the image, and Figure 1 and Figure 2 The same reference numerals in the accompanying drawings indicate the same or similar elements having the same or similar functions. Figure 1 Compared to the pressing equipment 100 shown in the video, Figure 2 The pressing device 100 shown in the image has different implementations of the pressure medium guiding passage 21. Figure 2 The pressing device 100 shown includes a ring 28 attached to the surface of a housing 2. The ring 28 is attached to the surface of the housing 2 (e.g., by threaded connection or welding), and its dimensions are determined such that a pressure medium guiding passage 21 is defined by the gap formed between the ring 28 and the bottom heat insulation portion 4. Figure 2 As shown in the image, the ring 28 may not be attached to the bottom insulation portion 4.

[0099] Figure 3 This is a schematic partial cross-sectional side view of the pressing device 100 according to an embodiment of the present invention. Figure 3 The pressing equipment 100 shown in the image is similar to... Figure 1 The pressing equipment 100 shown in the image, and Figure 1 and Figure 3 The same reference numerals in the accompanying drawings indicate the same or similar elements having the same or similar functions. Figure 1 The pressing equipment 100 shown in the middle (and Figure 2 Compared to the pressing equipment shown in the video, Figure 3 The pressing device 100 shown has different implementations of the pressure medium guiding passage 21. The pressing device 100 includes a gasket 29 disposed between the surface of the housing 2 and the bottom heat insulation portion 4. The outer edge of the gasket 29 is connected to (possibly attached to) the surface of the housing 2, and the inner edge of the gasket 29 is connected to (possibly attached to) the bottom heat insulation portion 4. The pressure medium guiding passage 21 is defined by a gap formed in the gasket 29.

[0100] Figure 4 This is a schematic partial cross-sectional side view of the pressing device 100 according to an embodiment of the present invention. Figure 4 The pressing equipment 100 shown in the image is similar to... Figure 1 The pressing equipment 100 shown in the image, and Figure 1 and Figure 4 The same reference numerals in the figures indicate the same or similar elements having the same or similar functions.

[0101] Figure 4 The pressing device 100 shown includes a ring 33 disposed between the surface of the housing 2 and the bottom heat insulation portion 4. The ring 33 is attached to both the surface of the housing 2 and the bottom heat insulation portion 4. The ring 33 can be connected to the surface of the housing 2 and the bottom heat insulation portion 4 by means of, for example, screws or welding. A pressure medium guiding passage 21 is disposed in the ring 33. It should be understood that the pressure medium guiding passage 21 can be implemented in other ways. For example, the ring 33 can be attached to only one of the surface of the housing 2 and the bottom heat insulation portion 4, and sealed to the other.

[0102] and Figure 1 Compared to the pressing equipment 100 shown in the video, Figure 4 The pressing device 100 shown in the image additionally includes a controllable pressure medium flow restrictor, schematically indicated by 34, which is arranged to selectively and controllably prevent or impede the flow of pressure medium in the pressure medium guide passage 21. The pressing device 100 includes a control unit 35, which is communicatively connected to the controllable pressure medium flow restrictor 34 for controlling its operation. Figure 4 The arrangement of the control unit 35 relative to pressure vessels 1, 8, and 9 shown is exemplary and serves to illustrate the principles of embodiments of the invention. The controllable pressure medium flow restrictor 34 may, for example, include one or more adjustable valves, such as one or more solenoid valves, pneumatic valves, and / or electric valves.

[0103] Multiple pressure medium guiding passages may be provided, for example, arranged in annulus 33. These multiple pressure medium guiding passages may be radially distributed regularly or irregularly within annulus 33. Each pressure medium guiding passage may be equipped with one or more corresponding controllable pressure medium flow restrictors.

[0104] The control unit 35 is configured to control the controllable pressure medium flow restrictor 34 to prevent or impede the flow of pressure medium in the pressure medium guide passage 21 during the cooling phase of the processing cycle (e.g., to completely or substantially completely prevent or impede the flow of pressure medium in the pressure medium guide passage 21), and not to prevent or impede the flow of pressure medium in the pressure medium guide passage 21 during another or several phases of the processing cycle (including at least one of the heating phase and the vacuum phase).

[0105] In summary, a pressing apparatus is disclosed. The pressing apparatus includes a pressure vessel arranged to contain a pressure medium during use of the pressing apparatus. The pressure vessel includes a top closure and a bottom closure. A furnace chamber is arranged within the pressure vessel such that the pressure medium can enter and exit the furnace chamber, the furnace chamber at least partially defining a processing space arranged to contain articles of art. The pressing apparatus includes at least one external convection loop pressure medium guiding passage, which is in fluid communication with the furnace chamber and arranged to form an external convection loop within the pressure vessel. The external convection loop is arranged to guide the pressure medium, after exiting the furnace chamber, near the inner surface of one or more walls of the pressure vessel to the space between the furnace chamber and the bottom closure. At least one pressure medium guiding passage is arranged within the pressure vessel such that the pressure medium can flow from the furnace chamber into the space between the furnace chamber and the bottom closure solely through the at least one pressure medium guiding passage, and vice versa.

[0106] Although the invention has been described in the accompanying drawings and the foregoing description, such description should be considered illustrative or exemplary rather than restrictive; the invention is not limited to the disclosed embodiments. From a study of the drawings, this disclosure, and the appended claims, those skilled in the art will understand and implement other variations of the disclosed embodiments in practicing the claimed invention. In the appended claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that specific measures are recited in mutually different dependent claims does not indicate that combinations of these measures cannot be used advantageously. No reference numerals in the claims should be construed as limiting the scope.

Claims

1. A pressing device (100), comprising: Pressure vessel (1, 8, 9) arranged to contain pressure medium therein during use of the pressing equipment, the pressure vessel including a top closure (8) and a bottom closure (9). A furnace chamber (18) is arranged within the pressure vessel such that a pressure medium can enter and exit the furnace chamber, the furnace chamber at least partially defining a processing space arranged to accommodate at least one article (5), wherein the pressing device is configured to subject the at least one article to a processing cycle including a cooling phase. At least one external convection loop pressure medium guiding passage (10, 11) is in fluid communication with the furnace cavity and is arranged to form an external convection loop within the pressure vessel, wherein the external convection loop is arranged to guide the pressure medium, after it has left the furnace cavity, into the space (16) between the furnace cavity and the bottom closure near the inner surface (23) of at least one wall (22) of the pressure vessel. A pressure medium flow generator (13) is disposed within the pressure vessel and in fluid communication with the furnace chamber, wherein, at least during the cooling phase of the processing cycle, the pressure medium flow generator is arranged to deliver pressure medium from at least the space between the furnace chamber and the bottom closure into the furnace chamber to cool the pressure medium in the processing space; and At least one pressure medium guiding passage (21) is arranged within the pressure vessel such that pressure medium can be introduced from the furnace cavity into the space between the furnace cavity and the bottom closure solely through the at least one pressure medium guiding passage, and vice versa. Each of the at least one pressure medium guiding passage is arranged such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage forms a gap with a width (W). Each of the at least one pressure medium guiding passage has a corresponding width, and the sum of these widths is less than 4 mm.

2. The press apparatus of claim 1, wherein, Each of the at least one pressure medium guiding passage is arranged such that the sum of the widths of these respective cross sections is in the range of 0.1 mm to 3.5 mm.

3. The press apparatus of claim 1, wherein, Each of the at least one pressure medium guiding passage is arranged such that the sum of the widths of these respective cross sections is in the range of 0.1 mm to 2.5 mm.

4. The press apparatus of claim 1, wherein, The pressure medium flow generator is controllable at least with respect to the flow rate of the pressure medium delivered from the space between at least the furnace cavity and the bottom closure to the furnace cavity, wherein the cooling rate of the pressure medium in the processing space is at least partially controlled by the flow rate of the pressure medium delivered from the space between at least the furnace cavity and the bottom closure to the furnace cavity; Each of the at least one pressure medium guiding passage is arranged such that the sum of these respective cross-sectional widths, based on the estimated flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity at a cooling rate exceeding a selected cooling rate threshold, causes at least one of these respective cross-sectional widths to cause a flow resistance of the pressure medium guided in the pressure medium guiding passage to the space between the furnace cavity and the bottom closure after just leaving the furnace cavity to become greater than the estimated flow resistance of the pressure medium guided in the external convection loop after leaving the furnace cavity.

5. The press apparatus of claim 1, wherein, Each of the at least one pressure medium guiding passage is arranged such that its cross-section in a plane perpendicular to the flow direction of the pressure medium through the pressure medium guiding passage forms a gap having the following shape: at least a portion of a circular ring, at least a portion of an elliptical ring, or a rectangle.

6. The press apparatus of claim 1, wherein, At least during the cooling phase of the processing cycle, the pressure medium flow generator is arranged to deliver pressure medium from another space in the pressing device, wherein, during at least a portion of the cooling phase, the temperature of the pressure medium in the other space is lower than the temperature of the pressure medium in the processing space, such that the temperature of the pressure medium in the processing space decreases as pressure medium is delivered from the other space to the processing space during the cooling phase.

7. The press apparatus of claim 1, wherein, The external convection loop is arranged to guide the pressure medium to the space (17) between the top closure and the furnace cavity after it has left the furnace cavity, and further guides the pressure medium from the space between the top closure and the furnace cavity near the inner surface of the wall of the pressure vessel to the space between the furnace cavity and the bottom closure.

8. The pressing device according to claim 1, comprising: Multiple external convection loop pressure medium guiding passages (10, 11) are in fluid communication with the furnace cavity and are arranged to form the external convection loop; wherein The furnace cavity is at least partially surrounded by an insulating shell (2, 4, 7) arranged to allow a pressure medium to enter and exit the furnace cavity. The insulating shell includes an insulating portion (7), a shell (2) that at least partially surrounds the insulating portion, and a bottom insulating portion (4). A portion of the external convection loop includes a first external convection loop pressure medium guiding passage (11), which is formed between at least a portion of the housing and the insulation portion and is arranged to guide the pressure medium to the space (17) between the top closure and the furnace cavity after it has left the furnace cavity. Another portion of the external convection loop includes a second external convection loop pressure medium guiding passage (10), which is arranged to guide the pressure medium from the space between the top closure and the furnace cavity near the inner surface of the wall of the pressure vessel to the space between the bottom insulation portion and the bottom closure portion. The space between the bottom insulation portion and the bottom closure portion constitutes or is included in the space between the furnace cavity and the bottom closure portion. The at least one pressure medium guiding passage is arranged such that the pressure medium can be introduced from the furnace cavity into the space between the bottom insulation portion and the bottom end closure only through the at least one pressure medium guiding passage, and vice versa.

9. The press apparatus of claim 8, wherein, The at least one pressure medium guiding passage is defined at least partially by at least one gap formed between the bottom insulation portion and the housing.

10. The press apparatus of claim 8, wherein, The bottom insulation portion includes a plate-like member, wherein the at least one pressure medium guiding passage is defined at least partially by at least one gap formed between the edge of the plate-like member and the surface of the housing.

11. The press apparatus of claim 8, wherein, The bottom insulation portion includes a plate-like member comprising a first outer surface (25), a second outer surface (26) opposite to the first outer surface, an edge surface (27) extending between the first outer surface and the second outer surface, and a disc (20) or annulus attached to one of the first outer surface and the second outer surface, wherein the size of the disc or annulus is determined such that the disc or annulus extends beyond at least a portion of the boundary of the first outer surface or the second outer surface, and wherein the at least one pressure medium guiding passage is defined at least partially by a gap formed between the edge of the disc or annulus and the surface of the housing.

12. The pressing device according to claim 8, further comprising an annulus (28) attached to the surface of the housing, the annulus being sized such that the at least one pressure medium guiding passage is at least partially defined by the gap formed between the annulus and the bottom heat insulation portion.

13. The press apparatus according to claim 8, further comprising a gasket (29) disposed intermediate the surface of the housing and the bottom heat insulating portion, a gasket outer edge connected to the surface of the housing and a gasket inner edge connected to the bottom heat insulating portion, wherein, The at least one pressure medium guiding passage is defined at least partially by the gap formed in the gasket.

14. The pressing device according to claim 1, wherein, At least one pressure medium guiding passage is curved.

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