Device for tempering an object

Abstract

The invention relates to a device (1) for tempering an object (2) comprising a chamber (5) for receiving the object (2), wherein the chamber (5) is surrounded by a chamber casing (7), a base element (4) and a cover element (8), a heating element, a rotor (9) for circulating a first gas, wherein the rotor (9) is arranged in the chamber (5), and a rotor drive (12) with which the rotor (9) is made to rotate. The heating element is formed by the rotor (9) with the rotor drive (12).

Description

[0001] DEVICE FOR CONTROLLING THE TEMPERATURE OF AN OBJECT

[0002] The invention relates to a device for tempering an object, in particular a metallic object, comprising a chamber for receiving the object, wherein the chamber is surrounded by a chamber shell, a floor element and a ceiling element, a heating element, an impeller for circulating a first gas, wherein the impeller is arranged in the chamber, and an impeller drive with which the impeller is set in rotation.

[0003] Furthermore, the invention relates to a method for tempering an object, in particular a metallic object, which is placed in a device, said device comprising a chamber which is surrounded by a chamber jacket, a floor element and a ceiling element, for receiving the object, wherein the temperature in the chamber is changed by a heating element, and wherein a first gas is circulated in the chamber by means of an impeller which is arranged in the chamber, and the impeller is set in rotation by means of an impeller drive.

[0004] In many industrial furnaces used for the heat treatment of various materials, such as aluminum, steel, non-ferrous metals, etc., heat transfer occurs through convection. Air or other protective gases are circulated around or around the material being heated or cooled. This enables uniform and rapid heat treatment of the material being heated or cooled.

[0005] Hydrogen is often used as a shielding gas, especially in the steel industry, because its good thermal conductivity improves heat transfer compared to air. Furthermore, hydrogen also has reducing properties on the surface of the annealed material. Due to hydrogen's low density, the fan motor responsible for convection requires less energy.

[0006] Traditionally, energy is supplied to such systems via separate heating registers, whereby the heating conductor material must be exposed to a certain overcoating temperature to achieve heat transfer. This means that the heating conductor material must always be hotter than the furnace temperature. Controlling a fan motor based on the gas density in a furnace chamber is known from the prior art.For example, DE 35 19 994 CI describes a method for the accelerated cooling of annealing material after an annealing process within an annealing furnace. Cooling gas is circulated through the furnace chamber and outside the furnace chamber through a cooler and a circulation fan. The cooling gas is initially circulated at a largely constant circulation rate. After reaching a predetermined, essentially temperature-dependent mass density of the cooling gas to be accelerated by the circulation fan, its circulation rate is reduced depending on the temperature-dependent increase in mass density. This is intended to reduce the cooling time.

[0007] US4543891 A describes an annealing apparatus comprising: a fan for circulating hot gas within the furnace and an electric motor to which a load is applied by the fan; a load transducer for detecting an electrical load on the motor and capable of generating a load signal; a load change detector responsive to the load signal and capable of generating a load change signal; a frequency reference integrator responsive to the load change signal and capable of generating, storing, and changing a reference signal in response to the load change signal; and an adjustable frequency drive responsive to the reference signal and capable of supplying variable frequency AC power to the motor.

[0008] The object of the present invention is to provide a possibility for tempering an object.

[0009] The object of the invention is achieved in the device mentioned at the outset in that the heating element is formed by the impeller with the impeller drive.

[0010] Furthermore, the problem is solved by the method mentioned at the beginning, according to which the impeller with the impeller drive is used as the heating element.

[0011] The advantage here is that by using the impeller with the impeller drive as a heating element, the thermal energy can be introduced more directly into the circulating gas. Furthermore, this provides simple options for influencing the temperature of an object. According to one embodiment of the invention, it can be provided that the one impeller with the impeller drive is the only heating element, or that several impellers, each with an impeller drive, are arranged, and these are the only heating elements. By omitting additional heating elements, the device can be constructed more simply. Furthermore, the aforementioned effects can be further improved.

[0012] According to another embodiment of the invention, the chamber shell can be surrounded by a supporting shell, and preferably the ceiling element by a supporting ceiling element. This makes it possible to reduce the resistance of the thermally stressed chamber shell to compressive loads, thus creating greater design freedom for this shell, particularly with regard to a more uniform temperature distribution in the chamber through thermal conduction for heating or maintaining a certain temperature and / or a faster heat dissipation through thermal conduction for cooling the object.

[0013] According to another embodiment of the invention, thermal insulation can be arranged between the chamber shell and the support shell, and preferably between the ceiling element and the support ceiling element, in order to reduce the transfer of thermal energy to the support shell or the support ceiling element, whereby the wall thickness of the latter can be reduced. Furthermore, this can reduce the thermal energy that must be introduced into the chamber via the at least one impeller with the at least one impeller drive in order to reach a specific, predefined temperature, since the thermal insulation can improve the thermal efficiency of the device.

[0014] To further improve these effects, according to an embodiment of the invention, the thermal insulation can be provided with several layers, whereby interfaces or transition surfaces can be created within the thermal insulation.

[0015] A further improvement of these effects can be achieved with a further embodiment of the invention, according to which the multiple layers are made of a different material. This also allows for a reduction in costs, as more expensive thermal insulation materials can be used only in areas with higher temperature loads, while more cost-effective insulation materials can be used in areas with already reduced thermal loads. Furthermore, this also allows for better coordination with the thermal behavior of the device, both internally and externally.

[0016] According to a further embodiment of the invention, it can be provided that the fan wheel has a first diameter, that the chamber has a second diameter, and that the first diameter is between 20% and 80% of the second diameter. By enlarging the fan wheel, the power requirement of the electric motor with the fan wheel can be increased, which can also increase the input of thermal energy into the circulating gas. For example, a 10% increase in diameter increases the power requirement by 1.6 times. During the evaluation of the invention, it was determined that fan wheel diameters in this range are advantageous.

[0017] To increase the power consumption of the fan wheel with the impeller drive, another embodiment of the invention can also provide at least one mixing element for admixing at least one second gas to the first gas. The density of the circulating gas can be influenced by the admixture of the second gas. For example, doubling the density of the circulating gas also doubles the power requirement of the impeller drive.

[0018] To further reduce the pressure load on the chamber shell and the chamber lid, i.e., the inner shell of the chamber, another embodiment of the invention can provide for at least one pressure measuring element to be arranged so that the pressure acting on the chamber shell and the ceiling element from the chamber differs by a maximum of 10% from the pressure prevailing between the chamber shell and the supporting shell and between the ceiling element and the supporting ceiling element. The pressure measuring element can thus be used to measure the pressure in the chamber, and the pressure acting on the chamber shell and the chamber lid from the outside can be adjusted accordingly.

[0019] According to one embodiment of the method, in order to change the temperature in the chamber, provision can be made for this to be carried out by changing the power consumption of the impeller with the impeller drive. For this purpose, according to further embodiments of the method, provision can be made for - as already explained - a second gas which is different from the first gas to be mixed with the first gas and the power consumption to be changed by changing the mixing ratio of the two gases and / or that in order to change the power consumption of the impeller with the impeller drive, the pressure in the chamber is changed and / or that in order to change the power consumption of the impeller with the impeller drive, the speed of the impeller drive and, if applicable, the impeller is changed. For example, by doubling the speed of the fan wheel, the power requirement of the impeller drive can be increased by four times.

[0020] According to one embodiment of the method, in order to change the density of the circulating gas, a gas is preferably used as the second gas whose weight is at least 50% greater than the weight of the first gas.

[0021] For a better understanding of the invention, it is explained in more detail using the following figures.

[0022] It shows in a simplified, schematic representation:

[0023] Fig. 1 shows a device for tempering an object.

[0024] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations. The disclosures contained throughout the description can be applied analogously to identical parts with identical reference symbols or component designations. Furthermore, the positional information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and these positional information must be applied analogously to the new position in the event of a change in position.

[0025] Fig. 1 shows a device 1 for tempering an object 2.

[0026] The device 1 is depicted as a so-called hood furnace with a furnace hood 3 and a base element 4. However, the illustrated geometry of the hood furnace is not intended to be limiting. Furthermore, the device 1 may generally also look different from that shown in Fig. 1, as long as it is suitable for tempering the object 2. The term "tempering" within the meaning of the invention encompasses maintaining a temperature, cooling the object 2, and in particular heating the object 2.

[0027] The object 2 can be a product, in particular a metallic one, such as a sheet metal or a circuit board, etc., or a raw material, such as a metal, etc. The process in the device 1 can be, for example, the melting of the object or a specific reaction in or on or with the object 2, such as a phase transformation, hardening of a metallic object 2, tempering of an object, etc. This list is merely exemplary and is not intended to be limiting. In general, the device 1 can be used in a thermal processing plant in order to process an object 2 thermally, i.e. at elevated temperature, in batches or continuously.

[0028] By way of example only, it should also be noted that the device 1 can be used for objects 2 made of aluminum or an aluminum alloy or generally non-ferrous metals (such as light metals or non-ferrous metals) or steel.

[0029] It is further possible that only a single object 2 or several objects 2 are subjected to a thermal treatment in the device at the same time.

[0030] While the device 1 or its components are described in more detail below, this does not mean that the device 1 cannot include other components or components known from the prior art for such devices 1. For example, the device 1 can also include various measuring probes, regulating and / or control devices, etc.

[0031] The device 1 has a chamber 5 for receiving the object 2 for / during treatment in the device 1. As can be seen from Fig. 1, several, possibly different, objects 2 can be subjected to thermal treatment simultaneously in the device 1. If necessary, the objects 2 can be held on a holding device 6, which can be arranged in the chamber 5.

[0032] The chamber 5 is surrounded by the floor element 4, a chamber shell 7, and a ceiling element 8. The chamber shell 7 can be arranged so as to stand on the floor element 4. Furthermore, the ceiling element 8 can be formed integrally with the chamber shell 7, as is known from bell furnaces. However, the floor element 4 can also be formed integrally with the chamber shell 7 and, if appropriate, the ceiling element 8. If appropriate, a closable opening can be formed in the chamber shell 7 and / or in the ceiling element 8 as access to the chamber 5. The chamber shell 7, together with the ceiling element 8 and the floor element 4, can define the volume of the chamber 5.

[0033] The device 1 further comprises an impeller 9 (also referred to as a fan wheel). The impeller 9 is arranged in the chamber 5, in particular below the at least one object 2. The impeller 9 can be arranged above the floor element 4 or at least partially within the floor element 4 in a corresponding recess. The impeller 9 is preferably arranged between the object 2 and the floor element 4.

[0034] The impeller 9 serves to circulate a first gas within the chamber 5 during the thermal treatment of the object 2, as indicated in Fig. 1 by flow arrows 10. The circulation can occur, for example, such that the first gas is guided past the at least one object 2 and flows centrally downwards again towards the impeller 9, as shown in Fig. 1. For the central return flow of the first gas, a central flow channel 11 can be provided in the chamber 5. This can, for example, be arranged or formed in the holding device 6 for the at least one object.

[0035] Hydrogen (H2), for example, can be used as the first gas. Depending on the thermal treatment to be performed on the object, the first gas can also be another gas, for example nitrogen (N2) and / or a carbon donor gas, such as carbon dioxide (CO2), to perform nitriding, carboriding, or carbonitriding. These gases are to be understood only as examples; for the reasons stated above, hydrogen is preferably used as the first gas if no further reaction with the object 2 is to occur during the thermal treatment.

[0036] The first gas can be fed into chamber 5 via a supply line (not shown in detail), optionally after one or more cleaning steps of the chamber atmosphere, for example by evacuating and purging chamber 5 one or more times with a gas, in particular the first gas. The impeller 9 is operatively connected to an impeller drive 12, for example via an axle 13, so that the impeller can be set in rotation by the impeller drive 12. The impeller drive 12 is in particular an electric motor, but can also be formed by another suitable drive. Likewise, the impeller 9 can have another operative connection with the impeller drive 12, for example via one or more gears, or a chain drive, etc.

[0037] The impeller drive 12 and / or the axle 13 or the mentioned operative connection can, for example, be arranged at least partially in a recess in the base element 4, as shown in Fig. 1. The impeller drive 12 can also be arranged below the base element 12.

[0038] Within the scope of the invention, it is possible for the device 1 to have more than one impeller 9 and more than one impeller drive 12, for example two or three, etc. In this case, each impeller 9 is preferably operatively connected to a respective impeller drive 12, for example via a respective axle 13. The plurality of impellers 9 can be arranged next to one another in the region of the base element 4. However, individual or all of the impellers can also be arranged in the region of the chamber shell 7 or the ceiling element 8 in order to be able to create different flow conditions in the chamber 5. The impeller drives 12 assigned to the impellers 9 can be arranged accordingly in the device 1.

[0039] The device 1 further comprises at least one heating element. This heating element is formed by the at least one impeller 9 with the impeller drive 12. In the preferred embodiment of the device 1, it is provided that the one impeller 9 with the impeller drive 12 is the only heating element, or that several impellers 9, each with an impeller drive 12, are arranged in the device 1 and these are the only heating elements. Unlike in such prior art devices 1, the energy input is therefore not via separate heating registers or heating elements. In the latter case, the heat conductor material must be exposed to a certain overcoat temperature in order to achieve heat transfer. This means that the heat conductor material must always be hotter than the temperature in the chamber 5. The invention circumvents this disadvantage by using the at least one impeller 9 with the impeller drive 12 directly as an energy source (heating source).Although preferably no additional heating element is provided in the device 1 for heating the circulating gas in the chamber 5, in a non-preferred embodiment, at least one additional heating element different from the impeller 9 with the impeller drive 12 can be arranged, for example, a resistance heating element or a radiant heating element, with which the energy input into the circulating gas can be supported as needed. This at least one additional heating element can be arranged in the chamber 5, for example, on the chamber shell 7 or on the ceiling element 8.

[0040] The device 1 can be used to perform a method for tempering an object 2, in particular a metallic object 2, after which the object 2 is placed into the device 1, and the temperature in the chamber is changed by at least one impeller 9 with the impeller drive 12. The energy is introduced via the impeller 9 with the impeller drive 12 directly into the circulating gas in the chamber 5.

[0041] To change the temperature in the chamber 5, it can be provided that this is changed by changing the power consumption of the at least one impeller 9 with the at least one impeller drive 12. By increasing the power requirement of the at least one impeller 9 with the at least one impeller drive 12, the temperature of the circulating gas in the chamber 5 can be increased. Conversely, by reducing this power requirement, the temperature of the circulating gas in the chamber 5 can be reduced. Since the circulating gas in the chamber comes into direct contact with the at least one object, a change in the temperature of the object can also be achieved by changing the temperature of the circulating gas.

[0042] To change the power consumption, for example, the density of the circulating gas in chamber 4 can be changed. As explained above, doubling the density of the circulating gas in chamber 5 doubles the power requirement of at least one impeller 9 with at least one impeller drive 12.

[0043] According to one embodiment, the density can be achieved, for example, by admixing at least one second gas to the first gas. The second gas is different from the first gas. In particular, the second gas can have a weight that is at least 50% higher than the first gas. Nitrogen or argon, for example, can be used as the second gas (provided that the first gas is not already nitrogen or argon). Other suitable gases can also be used. The temperature change can be adjusted via the mixing ratio of the two gases, since with an increase in density, i.e. an increase in the volume fraction of the heavy second gas in the chamber 5, the power requirement of the at least one fan wheel 9 with the at least one fan drive 12 increases.Conversely, by reducing the volume fraction of the heavy second gas in the chamber 5, the power requirement of the at least one fan wheel 9 with the at least one fan drive 12 can be reduced.

[0044] The specific mixing ratios of the gases in the individual process steps depend on the object 2 to be treated and the type of thermal treatment of the object. They can be determined by a person skilled in the art with a few experiments without inventive step, so there is no need to specify specific mixing ratios.

[0045] To adjust the desired mixing ratio of the gases used for the recirculating gas, the device 1 can, according to one embodiment, have at least one mixing element for admixing at least one second gas to the first gas. The mixing element can, for example, be a mixing valve, which can in particular be regulated and / or controlled.

[0046] However, separate gas lines can also be provided for the different gases in chamber 5. In this case, the mixing ratio can be regulated and / or controlled, for example, by adjusting and / or measuring the volume flow of the gases.

[0047] Additionally or alternatively, the change in density can also be achieved by increasing or reducing the pressure in the chamber 5. The pressure increase can be achieved by feeding more of the first gas and / or the at least one second gas into the chamber. Thus, by increasing the pressure in the chamber 5, the power consumption of the at least one fan wheel 9 with the at least one fan drive 12 can be increased. Conversely, by reducing the pressure in the chamber 5, the power consumption of the at least one fan wheel 9 with the at least one fan drive 12 can be reduced. With regard to this embodiment, it should also be noted that the person skilled in the art can determine the advantageous extent of the pressure increase for the respective application with just a few experiments and without inventive step, so that specifying a specific pressure is unnecessary. By way of example only, it should be noted that the pressure can be between 30 mbar and 80 mbar.

[0048] To increase the pressure in the chamber 5, it is advantageous if, according to a variant of the device 1, the chamber shell 7 is surrounded by a supporting shell 14 and preferably the ceiling element 8 is surrounded by a supporting ceiling element 15. The supporting shell 14 can also be supported on the floor element 4, if necessary.

[0049] The supporting ceiling element 15 can be formed integrally with the supporting casing 14. However, the floor element 4 can also be formed integrally with the supporting casing 14 and, if appropriate, the supporting ceiling element 15. A closable opening can be formed in the supporting casing 14 and / or the supporting ceiling element 15 as access to the chamber 5.

[0050] This double-shell design of the "shell" of chamber 5 has the advantage that it protects the thermally stressed chamber shell 7 and the ceiling element 8 from compressive loading. For this purpose, a first pressure can be applied to the inside (chamber side) of the chamber shell 7 and the ceiling element 8, and a second pressure can be applied to the outside (support shell side) of the chamber shell 7 and the ceiling element 8.

[0051] According to a further embodiment of the device 1, it can be provided that at least one pressure measuring element (not shown in Fig. 1) is arranged in and / or on it, so that a pressure from the chamber 5 acting on the chamber shell 7 and the ceiling element 8 is not equal to a pressure prevailing between the chamber shell 7 and the support shell 14 and between the ceiling element 8 and the support ceiling element 15 by a maximum of 10%, in particular a maximum of 5%, preferably a maximum of 2.5%. With the at least one pressure measuring element, for example, the differential pressure (the difference between the two pressures) can be determined and, depending on the result, either the pressure prevailing externally between the chamber shell 7 and the support shell 14 and between the ceiling element 8 and the support ceiling element 15 can be reduced or increased. For this purpose, at least one pressure measuring element (not shown in Fig.1 lead a fluid line (not shown) into this intermediate space between the chamber shell 7 and the support shell 14 and between the ceiling element 8 and the support ceiling element 15 and lead at least one fluid line out of this intermediate space.

[0052] For providing the pressure between the chamber shell 7 and the support shell 14 and between the ceiling element 8 and the support ceiling element 15, for example, nitrogen or argon or a gas mixture thereof or therewith can be used.

[0053] It can also be provided that the circulating gas from the chamber 5 is introduced into the space between the chamber shell 7 and the support shell 14 and between the ceiling element 8 and the support ceiling element 15 in order to create pressure equalization. However, this embodiment is not the preferred one, since in the preferred embodiment, the support shell 14 and the support ceiling element 15 are not subject to the same thermal stress as the chamber shell 7 and the ceiling element 8.

[0054] Preferably, the pressures applied to the outside and inside of the chamber shell 7 and the ceiling element 8 are equal.

[0055] This design of the device also allows a reduction in the wall thickness of the chamber shell 7 and, if applicable, the ceiling element 8. For example, the chamber shell 7 and, if applicable, the ceiling element 8 can have a wall thickness between 3 mm and 15 mm.

[0056] The support shell 14 and, if applicable, the support ceiling element 15 can have a wall thickness between 5 mm and 30 mm.

[0057] Of course, other pressure sensors can also be used. Furthermore, multiple sensors can be used to measure the pressures mentioned.

[0058] The data from the pressure sensors can be processed with a data processing system to regulate and / or control at least one of the pressures mentioned.

[0059] A further alternative or additional possibility for changing the power consumption of the at least one impeller 9 with the at least one impeller drive 12 consists in changing the speed of the impeller drive 12 and, if applicable, of the impeller 9. A change in the speed results in a quadratic change in the power consumption and thus, as a consequence, in the generation of thermal energy and its feed into the circulating gas in the chamber 5. For example, doubling the speed of the impeller drive 12 and, if applicable, of the impeller 9 can increase the power requirement fourfold. Thus, the actual value of the temperature in the chamber and its deviation from the target value can be determined via a regulating and / or control device.Depending on the deviation, the speed can then be increased or decreased using the control and / or regulation device or in another suitable manner, so that more or less thermal energy is available for changing the temperature of the circulating gas.

[0060] According to a further embodiment of the device 1, the power consumption of the at least one impeller 9 with the at least one impeller drive 12 can be changed in addition to or alternatively to at least one of the aforementioned possibilities by changing a diameter 16 (maximum outer diameter) of the fan wheel 9. This change is naturally preferably already taken into account in the design of the device 1 and the object 2 to be treated, since the change can only be carried out during ongoing operation of the device with greater effort. This means that depending on the expected requirement for thermal energy for the treatment of the object 2, the diameter 16 of the fan wheel 9 is determined in advance and a fan wheel 9 with the corresponding diameter 16 is installed in the device 1.According to a variant of the device 1, it has proven advantageous if the fan wheel 9 has a diameter 16 which is between 20% and 80%, in particular between 40% and 70%, of a second diameter 17 of the chamber 5 (maximum inner diameter of the chamber 5 viewed in the same direction as the diameter 16 of the fan wheel 9).

[0061] A change in the diameter of the fan wheel (16 mm) results in a fifth-power change in the specified power requirement. For example, a 10% increase in diameter results in a 1.6-fold increase in power requirement.

[0062] As can be seen from Fig. 1, in the double-shell embodiment of the device 1, it can be provided that a thermal insulation 18 is arranged between the chamber shell 7 and the support shell 14, and preferably between the ceiling element 8 and the support ceiling element 15. This thermal insulation 18 preferably extends over the entire volume of this intermediate space. If necessary, the thermal insulation 18 can also be subjected to the aforementioned pressure, which can be applied as needed between the chamber shell 7 and the support shell 14, and preferably between the ceiling element 8 and the support ceiling element 15. For example, the thermal insulation 18 can be pressurized with nitrogen or argon.

[0063] Thermal insulation 18 comprises or consists of a thermal insulating material, such as ceramic fiber materials, mineral wool, graphite, etc.

[0064] According to a further embodiment of the device 1, the thermal insulation 18 can be formed in several layers, for example comprising a first insulating layer 19 and a second insulating layer 20, in particular directly adjacent thereto. The thermal insulation 18 can also have more than two insulating layers.

[0065] According to a further embodiment, the multiple insulating layers 19, 20 can be made of or comprise different materials. This allows the thermal insulation properties to be modified accordingly. For example, the thermal insulation layer 19 located closer to the chamber shell 7 and the ceiling element 8 can be made of a material that has better thermal insulation properties than the material of the thermal insulation layer 20. The thermal insulation effect can thus be designed to decrease from the inside to the outside within the thermal insulation 18.

[0066] If the device 1 is also used to cool the object 2, it can be provided with a fluid connection to an external cooler (heat exchanger) to reduce the cooling time. For this purpose, the circulating gas can be circulated from the chamber 5 via the cooler using appropriate fluid lines.

[0067] The device 1 has the advantage that no flame burners are required for the thermal treatment of the object 2.

[0068] The embodiments show or describe possible embodiments, whereby combinations of the individual embodiments are also possible.

[0069] For the sake of clarity, it should finally be noted that, for a better understanding of the structure of the device 1, it is not necessarily shown to scale.

[0070] device

[0071] Object

[0072] hood

[0073] Floor element

[0074] chamber

[0075] Holding device

[0076] Chamber jacket

[0077] Ceiling element

[0078] balance bike

[0079] Flow arrow

[0080] flow channel

[0081] Impeller drive

[0082] axis

[0083] Support jacket

[0084] Supporting ceiling element

[0085] diameter

[0086] diameter

[0087] insulation

[0088] Insulating layer

[0089] Insulating layer

Claims

Patent claims 1. Device (1) for temperature control of an object (2), in particular a metallic object (2), comprising - a chamber (5) for receiving the object (2), wherein the chamber (5) is surrounded by a chamber shell (7), a bottom element (4) and a top element (8), - a heating element, - an impeller (9) for the circulation of a first gas, wherein the impeller (9) is arranged in the chamber (5), - and an impeller drive (12) with which the impeller (9) is set in rotational motion, characterized in that the heating element is formed by the impeller (9) with the impeller drive (12).

2. Device (1) according to claim 1, characterized in that the one impeller (9) with the impeller drive (12) is the only heating element, or that several impellers (9) are arranged, each with an impeller drive (12), and these are the only heating elements.

3. Device (1) according to claim 1 or 2, characterized in that the chamber shell (7) is surrounded by a support shell (14) and preferably the ceiling element (8) is surrounded by a support ceiling element (15).

4. Device (1) according to claim 3, characterized in that thermal insulation (18) is arranged between the chamber shell (7) and the support shell (14) and preferably between the ceiling element (8) and the supporting ceiling element (15).

5. Device (1) according to claim 4, characterized in that the thermal insulation (18) has several layers.

6. Device (1) according to claim 5, characterized in that the multiple layers consist of a different material.

7. Device (1) according to one of claims 1 to 6, characterized in that the fan wheel (9) has a first diameter (16), that the chamber (5) further has a second diameter (17), and that the first diameter (16) is between 20% and 80% of the second diameter (17).

8. Device (1) according to one of claims 1 to 7, characterized in that it has at least one mixing element for adding at least one second gas to the first gas.

9. Device (1) according to one of claims 3 to 8, characterized in that at least one pressure measuring element is arranged such that a pressure acting on the chamber shell (7) and the ceiling element (8) from the chamber (5) differs by a maximum of 10% from a pressure prevailing between the chamber shell (7) and the support shell (14) and between the ceiling element (8) and the support ceiling element (15).

10. Method for temperature control of an object (2), in particular a metallic object (2), which is placed in a device (1), wherein this device (1) comprises a chamber (5) surrounded by a chamber shell (7), a bottom element (4) and a top element (8) for receiving the object (2), wherein the temperature in the chamber (5) is changed by a heating element, and wherein a first gas is circulated in the chamber (5) by an impeller (9) arranged in the chamber (5), and the impeller (9) is set in rotation by an impeller drive (12), characterized in that the impeller (9) with the impeller drive (12) is used as the heating element.

11. Method according to claim 10, wherein the temperature in the chamber is changed by changing the power consumption of the impeller (9) with the impeller drive (12).

12. Method according to claim 11, characterized in that a second gas, different from the first gas, is mixed with the first gas and the power consumption is changed by changing the mixing ratio of the two gases.

13. Method according to claim 12, characterized in that the second gas used is a gas whose weight is at least 50% greater than the weight of the first gas.

14. Method according to one of claims 11 to 13, characterized in that the pressure in the chamber (5) is changed to change the power consumption of the impeller (9) with the impeller drive (12).

15. Method according to one of claims 11 to 14, characterized in that the rotational speed of the impeller drive (12) and optionally of the impeller (9) is changed to change the power input of the impeller (9) with the impeller drive (12).

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