Multifunctional additive manufacturing equipment

Abstract

The utility model discloses multifunctional additive manufacturing equipment, which relates to the technical field of additive manufacturing and comprises a forming bin, an atmosphere adjusting component arranged outside the forming bin and communicated with the forming bin and an adsorption structure arranged in the forming bin and / or the atmosphere adjusting component. The atmosphere adjusting assembly comprises a gas exchange device and a temperature control device, a first through hole and a second through hole which are connected with the atmosphere adjusting assembly and conduct gas are formed in the two opposite sides of the forming bin, and the temperature control device is arranged between the gas exchange device and the first through hole. According to the technical scheme, original air in the forming bin is exhausted, the oxygen content in the forming bin is reduced, and meanwhile the temperature and pressure in the forming bin are controlled, so that additive manufacturing is conducted in the most ideal environment, the problem that material powder is prone to oxidation is solved, the temperature meeting green body curing and degreasing is provided, and the product quality is improved. And the green body curing and degreasing steps can be carried out in the forming bin at the same time, and use is more convenient.

Description

Technical Field

[0001] This utility model relates to the field of additive manufacturing technology, and in particular to a multifunctional additive manufacturing equipment. Background Technology

[0002] Binder spray molding technology can achieve the forming of complex structures of most metals, ceramics and composite materials. Compared with traditional injection molding technology, it can eliminate the need for molds. However, reactive metal materials such as titanium alloys and aluminum alloys are prone to oxidation when they are put into the binder spray molding equipment in powder form for bonding. Even if the oxidized powder forms a green body, the sintered material will still have a lot of voids, which will affect its strength performance.

[0003] Currently, the main technologies for binder spraying forming of reactive metal materials include: altering the powder state to increase its oxidation resistance and reduce its sintering difficulty; and changing the material composition by physically or chemically bonding easily sinterable components to the surface of titanium alloy or aluminum alloy powders. However, these technologies increase the cost of material preparation and, to some extent, alter the material's properties, which may not meet the final application requirements. Furthermore, current upgrades and optimizations of binder spraying forming equipment do not involve technologies for creating low-oxygen environments.

[0004] In conclusion, it is imperative to solve the problem of lack of atmosphere protection in adhesive spray molding equipment. Summary of the Invention

[0005] The main objective of this invention is to propose a multifunctional additive manufacturing equipment that aims to improve the situation where material powder is easily oxidized in binder spray forming technology.

[0006] To achieve the above objectives, the present invention proposes a multifunctional additive manufacturing equipment, including a forming chamber, an atmosphere conditioning component disposed outside the forming chamber and communicating with the forming chamber, and an adsorption structure disposed within the forming chamber and / or the atmosphere conditioning component for adsorbing impurities in the gas.

[0007] The atmosphere conditioning component includes a gas exchange device and a temperature control device. The forming chamber has a first through hole and a second through hole on opposite sides for conducting gas, and the temperature control device is located between the gas exchange device and the first through hole.

[0008] In one embodiment, the atmosphere conditioning assembly further includes a gas guide pipe, which connects the outlet end of the second through hole to the inlet end of the gas exchange device;

[0009] The adsorption structure is disposed at the second through hole and / or on the inner wall of the gas guide tube.

[0010] In one embodiment, the gas guide tube is stacked, including at least one heat insulation layer and at least one structural layer.

[0011] In one embodiment, the gas exchange device includes a gas filter, a gas supply device, and a gas pump connected in sequence, wherein the gas supply device supplies an inert gas.

[0012] In one embodiment, the temperature control device is provided with a heating structure, which consists of multiple heating fins stacked together, and each heating fin has multiple vent holes.

[0013] The heating structure is equipped with a gas flow sensor, a gas temperature sensor, and a gas pressure sensor at opposite ends of the gas flow path. The gas flow sensor, gas temperature sensor, and gas pressure sensor feed back the data to the gas pump to control its operation.

[0014] In one embodiment, the air pump draws gas from the gas supply device and transmits it to the temperature control device, or the air pump draws gas from the temperature control device and discharges it to the external environment.

[0015] In one embodiment, the air pressure inside the forming chamber is 0.8 kPa-10 kPa.

[0016] In one embodiment, the forming chamber is provided with a forming platform, a heatable forming substrate, and a powder press;

[0017] The forming substrate is placed on the plane of the forming platform for heating the material of the contact surface;

[0018] The powder compactor has multiple heating rollers on the side near the forming substrate, which are used to compact the powder while heating the material on the contact surface.

[0019] In one embodiment, the first through hole is a plurality of through holes arranged in an array, and the diameter of the through holes gradually increases from the center to the periphery.

[0020] In one embodiment, the forming chamber is provided with a chamber door and a pressure relief valve on adjacent sides of the sidewall where the first through hole is provided, and the chamber door and the pressure relief valve are provided with at least one layer of sealing and at least one layer of heat insulation structure.

[0021] The technical solution of this utility model combines a gas exchange device with a temperature control device to expel the original air in the forming chamber, reduce the oxygen content in the forming chamber, and control the temperature and pressure in the forming chamber at the same time, so that additive manufacturing can be carried out in the most ideal environment. This solves the problem of easy oxidation of material powder, reduces the impact of environmental factors on product forming, and improves product yield. In addition, the temperature control device provides the temperature required for green curing and degreasing, so that the green curing and degreasing steps can be carried out simultaneously in the forming chamber, making it more convenient to use. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 A schematic diagram of the structure of an embodiment of the multifunctional additive manufacturing equipment provided by this utility model;

[0024] Figure 2 A schematic diagram of the gas exchange device in the multifunctional additive manufacturing equipment provided by this utility model;

[0025] Figure 3 A schematic diagram of the adsorption structure in the multifunctional additive manufacturing equipment provided by this utility model;

[0026] Figure 4 A schematic diagram of the structure of the first through hole in the multifunctional additive manufacturing equipment provided by this utility model;

[0027] Figure 5 A schematic diagram of the heating fins in the multifunctional additive manufacturing equipment provided by this utility model.

[0028] Explanation of icon numbers:

[0029] 1. Multifunctional additive manufacturing equipment;

[0030] 11. Forming chamber; 12. Atmosphere control assembly; 13. Adsorption structure;

[0031] 111. First through hole; 112. Second through hole; 113. Forming platform; 114. Forming substrate; 115. Powder press; 121. Gas exchange device; 122. Temperature control device; 123. Gas guide pipe;

[0032] 1211. Gas filtration device; 1212. Gas supply device; 1213. Air pump; 1221. Heating fins.

[0033] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0035] It should be noted that if any directional indication (such as up, down, left, right, front, back, etc.) is involved in the embodiments of this utility model, such directional indication is only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indication will also change accordingly. Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0036] Furthermore, if the embodiments of this utility model involve descriptions such as "first," "second," etc., these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Furthermore, the use of "and / or" or "and / or" throughout the text includes three parallel options; for example, "A and / or B" includes option A, option B, or options where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0037] Binder spray molding technology can achieve the forming of complex structures of most metals, ceramics and composite materials. Compared with traditional injection molding technology, it can eliminate the need for molds. However, reactive metal materials such as titanium alloys and aluminum alloys are prone to oxidation when they are put into the binder spray molding equipment in powder form for bonding. Even if the oxidized powder forms a green body, the sintered material will still have a lot of voids, which will affect its strength performance.

[0038] Currently, the main technologies for binder spraying forming of reactive metal materials include: altering the powder state to increase its oxidation resistance and reduce its sintering difficulty; and changing the material composition by physically or chemically bonding easily sinterable components to the surface of titanium alloy or aluminum alloy powders. However, these technologies increase the cost of material preparation and, to some extent, alter the material's properties, which may not meet the final application requirements. Furthermore, current upgrades and optimizations of binder spraying forming equipment do not involve technologies for creating low-oxygen environments.

[0039] In conclusion, it is imperative to solve the problem of lack of atmosphere protection in adhesive spray molding equipment.

[0040] This utility model proposes a multifunctional additive manufacturing equipment 1.

[0041] Please combine Figures 1-5In one embodiment of the present invention, the multifunctional additive manufacturing equipment 1 includes a forming chamber 11, an atmosphere conditioning component 12 disposed outside the forming chamber 11 and communicating with the forming chamber 11, and an adsorption structure 13 disposed inside the forming chamber and / or the atmosphere conditioning component 12 for adsorbing impurities in the gas.

[0042] The atmosphere conditioning component 12 includes a gas exchange device 121 and a temperature control device 122. The forming chamber 11 has a first through hole 111 and a second through hole 112 connected to the atmosphere conditioning component 12 for conducting gas. The temperature control device 122 is disposed between the gas exchange device 121 and the first through hole 111.

[0043] It should be noted that the gas exchange device 121 includes a gas supply device 1212 and a gas pump 1213. The gas supplied by the gas supply device 1212 is usually an inert gas.

[0044] Optionally, the gas supplied by the gas supply device 1212 can also be a gas of other properties, as long as it meets the forming conditions of the material in the forming chamber 11. No absolute limitation is made here.

[0045] Understandably, the gas supply device 1212 provides inert gas, which is drawn by the air pump 1213 and transmitted to the forming chamber 11 at a preset pressure and flow rate to reduce the oxygen content in the forming chamber 11, reduce the possibility of material powder oxidation, and the inert gas will not react with the material powder, thereby better protecting the various properties of the material.

[0046] Temperature control device 122 heats or cools the gas output by air pump 1213 to meet the temperature environment required for printing powder material in forming chamber 11.

[0047] In addition, the adsorption structure 13 is mainly used to adsorb the binder vapor that flows with the gas after degreasing in the binder forming process, so that it condenses in the adsorption structure 13, protects the subsequent equipment through which the gas flows, and prevents the binder from clogging.

[0048] In one embodiment of the present invention, the atmosphere conditioning component 12 further includes a gas guide pipe 123, which connects the outlet end of the second through hole 112 to the inlet end of the gas exchange device 121.

[0049] The adsorption structure 13 is disposed at the second through hole 112 and / or on the inner wall of the gas guide tube 123.

[0050] It should be noted that the adsorption structure 13 needs to completely adsorb the binder vapor carried away in the gas flow. Therefore, the number of adsorption structures 13 should be more rather than less. The adsorption structure 13 in the gas guide tube 123 is used to adsorb the remaining binder.

[0051] Specifically, the connection between the gas guide tube 123 and the second through hole 112 is funnel-shaped, with the diameter of the side closer to the forming chamber being larger than that of the side farther away, which facilitates the installation of the adsorption structure 13;

[0052] More specifically, the adsorption structure 13 is detachable, and a new structure can be directly replaced after use, thereby preventing the gas flow channel from being blocked due to excessive adsorption of the adhesive.

[0053] Optionally, one end of the gas guide tube 123 can be partially inserted into the forming chamber 11, and can be detachably connected and sealed with a seal. This detachable connection makes the use and handling of the multifunctional additive manufacturing equipment 1 more convenient.

[0054] Optionally, one end of the gas guide tube 123 can be integrally formed with the side wall of the forming chamber 11 and connected through the second through hole 112 to solve the sealing problem.

[0055] Specifically, in one embodiment of the present invention, the atmosphere conditioning component 12 further includes a gas filter device 1211.

[0056] It should be noted that when the multifunctional additive manufacturing equipment 1 is in use, the air pump 1213 will first draw gas from the gas exchange device 121 and input it into the forming chamber 11, and discharge the original air in the forming chamber 11, thereby reducing the oxygen content in the forming chamber 11. The discharged air returns to the gas exchange device 121 along the gas guide pipe 123. In order to prevent impurities in the air from contaminating the pure gas in the gas exchange device 121, the air needs to be filtered so that the purified gas can enter the gas exchange device 121 to participate in the circulation.

[0057] In one embodiment of this utility model, the gas guide tube 123 is stacked, including at least one heat insulation layer and at least one structural layer.

[0058] Specifically, in a specific embodiment of this utility model, the gas guide tube 123 has a three-layer stacked structure, with a heat insulation layer sandwiched between two structural layers.

[0059] Understandably, the structural layer is used to support the mechanical structure of the gas guide tube 123 and prevent the gas guide tube 123 from being easily damaged, which could lead to leakage during gas flow. The heat insulation layer is used to prevent heat transfer between the gas inside the pipe and the external environment, thereby preventing heat loss. In the case of using the inert gas in a cycle, heat utilization can be greatly improved, thereby reducing the cost of use.

[0060] In one embodiment of the present invention, a heating structure is provided in the temperature control device 122. The heating structure consists of multiple heating fins 1221 stacked together, and each heating fin 1221 has multiple vent holes.

[0061] It should be noted that the vents on each heating fin 1221 are interconnected, forming independent channels within the entire heating structure. This allows the input pure gas to flow and be heated along different independent channels, thereby improving the heating efficiency of the gas.

[0062] Specifically, the heating structure is equipped with a gas flow sensor, a gas temperature sensor, and a gas pressure sensor at both ends of the gas flow path. The gas flow sensor, gas temperature sensor, and gas pressure sensor feed back the data to the air pump 1213 to control the operation of the air pump 1213.

[0063] Optionally, the temperature setting range of the heating fin 1221 is 20℃-200℃.

[0064] Understandably, the gas flow sensor is used to acquire gas flow information. Combined with the gas temperature sensor, it can determine the degree of gas heating at a specified flow rate, thereby controlling the rate at which the gas pump 1213 releases gas, so that the gas can be fully heated in the heating structure.

[0065] When the gas pressure inside the forming chamber 11 is too high, the gas pressure sensor in the temperature control device 122 connected to it can also detect the pressure change, thereby controlling the rate at which the air pump 1213 releases gas or stopping the extraction of gas from the gas exchange device 121 and stopping the release.

[0066] In one embodiment of the present invention, the air pump 1213 draws gas from the gas supply device 1212 and transmits it to the temperature control device 122, or the air pump 1213 draws gas from the temperature control device 122 and discharges it to the external environment.

[0067] It should be noted that the oxygen concentration in the forming chamber 11 needs to be controlled below 10 ppm to reduce the impact of oxygen oxidation on the material powder.

[0068] Specifically, the temperature control device 122 is connected to the forming chamber 11, that is, the air pump 1213 can draw air from the forming chamber 11 through the first through hole 111 connected to the temperature control device 122 and the forming chamber 11 and discharge it, which can reduce the air pressure in the forming chamber 11 or quickly reduce the oxygen content inside the forming chamber 11.

[0069] In one embodiment of this utility model, the air pressure inside the forming chamber 11 is 0.8 kPa-10 kPa.

[0070] It should be noted that the air pressure inside the forming chamber 11 will promote the degree of adhesive wetting during the adhesive spraying process, and the relationship is roughly proportional. That is, the increase in air pressure inside the forming chamber 11 will improve the yield of the finished product to a certain extent.

[0071] In one embodiment of this utility model, a forming platform 113, a heatable forming substrate 114, and a powder press 115 are provided in the forming chamber 11.

[0072] Specifically, the forming substrate 114 is placed on the plane of the forming platform 113, and the material powder is laid on the forming substrate 114 by a powder spreading device. The heatable forming substrate 114 is used to heat the material on the contact surface. After each application of adhesive and the laying of another layer of powder, the material powder needs to be compacted by pressing the powder with a powder press 115. The powder press 115 is equipped with multiple heating rollers on the side near the forming substrate 114, which heat the material powder on the contact surface while pressing the material powder, so that the material is heated more evenly during the forming process.

[0073] Furthermore, after the green body is formed, the gas heated by the temperature control device 122 enables the temperature inside the forming chamber 11 to reach the temperature required for green body curing and degreasing, thereby completing the green body curing and degreasing steps. This allows the multifunctional additive manufacturing equipment 1 to integrate the processing functions of binder spraying, curing and degreasing, making it more convenient to use.

[0074] In one embodiment of this utility model, the first through hole 111 is a plurality of through holes arranged in an array, and the diameter of the through holes gradually increases from the center to the periphery.

[0075] It should be noted that the first through hole 111 is directly opposite each heating channel of the heating fin 1221, so that the inert gas can diffuse directly into the forming chamber 11 after heating. However, because the diameter of the central through hole is too small, it compresses the inert gas to flow to the surrounding area and enter the forming chamber 11. This makes the pressure of the inert gas entering the forming chamber 11 from the first through hole 111 uniform, and there will be no situation where the flow rate in the middle is too fast and the flow rate around the perimeter is too slow, which would cause the inert gas to flow unevenly in the forming chamber 11.

[0076] The pure inert gas that enters at a constant speed diffuses and compresses the original air in the forming chamber 11, making the original air discharge more efficient and more thorough.

[0077] In one embodiment of the present invention, the forming chamber 11 is provided with a chamber door and a pressure relief valve on the adjacent sides of the side wall where the first through hole 111 is provided, and the chamber door and the pressure relief valve are provided with at least one layer of sealing and at least one layer of heat insulation structure.

[0078] It should be noted that the door design makes it easier for users to take out the formed green blanks or processed blanks, making it more convenient to use; the pressure relief valve design prevents the air pressure inside the forming chamber 11 from being too high and damaging other connected equipment, or from posing a certain risk to the user in releasing the pressure. By setting the pressure relief valve and its threshold, the air pressure inside the forming chamber 11 can be better controlled within the required safe threshold range, and the high pressure inside the forming chamber 11 can be easily released, while also removing the binder vapor carried in the gas.

[0079] Specifically, in this embodiment of the present invention, the gas release rate of the air pump 1213 is in the range of 1 m³ / h - 150 m³ / h, and the flow velocity through the first through hole 111 is adjusted in the range of 5 m / s - 35 m / s, so that the multifunctional additive manufacturing equipment 1 can achieve a low oxygen environment of less than 10 ppm within 30 minutes after startup.

[0080] The technical solution of this utility model combines a gas exchange device 121 with a temperature control device 122 to expel the original air in the forming chamber 11, reduce the oxygen content in the forming chamber 11, and control the temperature and pressure in the forming chamber 11 at the same time, so that additive manufacturing can be carried out in the most ideal environment, solving the problem of easy oxidation of material powder, reducing the impact of environmental factors on product forming, improving product yield, and the temperature control device 122 provides the temperature that meets the requirements for green curing and degreasing, so that the green curing and degreasing steps can be carried out simultaneously in the forming chamber 11, making it more convenient to use.

[0081] It should be understood that the terms "one embodiment" or "one example" throughout the specification mean that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the present invention. Therefore, "in one embodiment" or "in one example" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Those skilled in the art should also recognize that the embodiments described in the specification are optional embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0082] In various embodiments of this utility model, it should be understood that the sequence number of each process does not necessarily imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of this utility model embodiment.

[0083] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, or they may sometimes be executed in reverse order, depending on the functions involved. It is particularly important to note that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0084] The above description is merely an exemplary embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the technical concept of the present utility model and the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A multifunctional additive manufacturing equipment, characterized in that: The multifunctional additive manufacturing equipment includes a forming chamber, an atmosphere conditioning component disposed outside the forming chamber and communicating with the forming chamber, and an adsorption structure disposed within the forming chamber and / or the atmosphere conditioning component for adsorbing impurities in the adsorption gas. The atmosphere conditioning component includes a gas exchange device and a temperature control device. The forming chamber has a first through hole and a second through hole on opposite sides for conducting gas, and the temperature control device is located between the gas exchange device and the first through hole.

2. The multifunctional additive manufacturing equipment as described in claim 1, characterized in that: The atmosphere conditioning assembly also includes a gas guide pipe, which connects the outlet end of the second through hole to the inlet end of the gas exchange device; The adsorption structure is disposed at the second through hole and / or on the inner wall of the gas guide tube.

3. The multifunctional additive manufacturing equipment as described in claim 2, characterized in that: The gas guide tube is stacked, including at least one heat insulation layer and at least one structural layer.

4. The multifunctional additive manufacturing equipment as described in claim 2, characterized in that: The gas exchange device includes a gas filter, a gas supply device, and a gas pump connected in sequence, wherein the gas supply device supplies an inert gas.

5. The multifunctional additive manufacturing equipment as described in claim 4, characterized in that: The temperature control device is equipped with a heating structure, which consists of multiple heating fins stacked together, and each heating fin has multiple vent holes. The heating structure is equipped with a gas flow sensor, a gas temperature sensor, and a gas pressure sensor at opposite ends of the gas flow path. The gas flow sensor, gas temperature sensor, and gas pressure sensor feed back the data to the gas pump to control its operation.

6. The multifunctional additive manufacturing equipment as described in claim 4, characterized in that: The air pump draws gas from the gas supply device and transmits it to the temperature control device, or the air pump draws gas from the temperature control device and discharges it to the external environment.

7. The multifunctional additive manufacturing equipment as described in claim 6, characterized in that: The air pressure inside the forming chamber is 0.8 kPa-10 kPa.

8. The multifunctional additive manufacturing equipment as described in claim 1, characterized in that: The forming chamber is equipped with a forming platform, a heatable forming substrate, and a powder press. The forming substrate is placed on the plane of the forming platform for heating the material of the contact surface; The powder compactor has multiple heating rollers on the side near the forming substrate, which are used to compact the powder while heating the material on the contact surface.

9. The multifunctional additive manufacturing equipment as described in claim 1, characterized in that: The first through hole is a plurality of through holes arranged in an array, and the diameter of the through holes gradually increases from the center to the periphery.

10. The multifunctional additive manufacturing equipment as described in claim 1, characterized in that: The forming chamber is provided with a chamber door and a pressure relief valve on the adjacent sides of the side wall where the first through hole is provided, and the chamber door and the pressure relief valve are provided with at least one layer of sealing and at least one layer of heat insulation structure.

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