Apparatus for and method of inductively heating at least one workpiece

Abstract

The invention relates to a device for inductively heating at least one workpiece (4), in particular a substantially strip-shaped workpiece (4), comprising at least one furnace shell (6), at least one inductor arrangement (8) arranged in the furnace shell (6), wherein the inductor arrangement (8) is arranged at least partially in an inductor region (10) of the furnace shell (6), at least one heating region (14) for receiving a process gas, the heating region (14) being arranged in the furnace shell (6), and a separating material (12) for separating, in particular thermally separating, the inductor region (10) and the heating region (14). Furthermore, the invention relates to a method for inductively heating at least one workpiece.

Description

Technical Field

[0001] This invention relates to an apparatus for induction heating at least one workpiece, particularly a substantially strip-shaped workpiece, the apparatus comprising: at least one furnace shell; at least one inductor device disposed within the furnace shell, wherein the inductor device is at least partially disposed within an inductor region of the furnace shell; at least one heating zone for receiving process gases, the heating zone being disposed within the furnace shell; and an insulating material for isolating, particularly thermally isolating, the inductor region and the heating zone. The invention also relates to a method for induction heating at least one workpiece, particularly by means of the aforementioned apparatus. Background Technology

[0002] Induction heating equipment is known in the prior art; for example, it may be called a continuous tunnel furnace or an induction tunnel furnace. These devices can be used for induction heating of workpieces. Induction heating methods generally refer to methods of heating the surface of a material, particularly a steel surface, by means of an electromagnetic field induced into the workpiece.

[0003] In this method, the furnace duct can be filled with process gas, but the process gas should not escape from the duct into the surrounding atmosphere. This is because if the process gas escapes from the duct, it will not only pollute the air around the continuous tunnel furnace, but also cause an explosive reaction of the process gas.

[0004] Therefore, traditional continuous tunnel furnaces typically have a basically airtight furnace tunnel, which is airtightly connected to connecting pipes upstream and downstream of the heating section. Here, the inductor device can either surround the workpiece or be positioned above and / or below at least one workpiece.

[0005] However, the problem with this design is that the materials typically used for airtight insulation are at least partially made of metal, which also heats up in the same way as at least one workpiece when the sensor device is used, which is not permissible.

[0006] An induction tunnel furnace is known from EP 2 577 201 B1, which has an airtight barrier chamber surrounding an airtight tunnel region, wherein an airtight isolation surface or airtight isolation material is arranged between the tunnel region and the barrier chamber. To prevent exchange between the barrier gas in the barrier chamber and the process gas in the tunnel region, the induction tunnel furnace also has a barrier gas regulator.

[0007] However, in practice, providing such an airtight barrier presents several challenges: the airtight material must either be metallic, which presents problems with magnetic field penetration (either requiring high energy loss) or only temperature-critical polymers. Another drawback is that a large pressure difference between the barrier chamber and the tunnel region can exert significant forces on the barrier, compromising its integrity. Furthermore, achieving an airtight connection with the connecting pipes requires substantial structural resources. Summary of the Invention

[0008] Based on the above-mentioned prior art, the technical problem to be solved by the present invention is to provide an apparatus and method for induction heating of at least one workpiece, which can achieve reliable and safe operation of the apparatus or the method in a simple manner.

[0009] According to a first aspect of the present invention, the above-mentioned technical problem is solved in the above-mentioned device, namely, the design of the insulating material enables a flow technology connection between the sensor area and the heating area.

[0010] By establishing a flow technology connection between the sensor region and the heating region, flow technology exchange between the medium arranged in the sensor region and the medium arranged in the heating region can be achieved. In particular, each of the respective media is a gas or gas mixture located within the furnace shell.

[0011] For example, it has proven advantageous in practice to purge the entire furnace shell with an inert gas, such as nitrogen or a nitrogen mixture, before starting operation of the equipment for induction heating of at least one workpiece, and then fill the furnace shell with the process gas used during the operation of the equipment, such as hydrogen or a hydrogen mixture. In this way, residual air or residual oxygen in the inductor area can be reliably avoided during the operation of the equipment for induction heating of at least one workpiece, thereby ensuring the reliable operation of at least one inductor device.

[0012] The flow technology connection between the inductor region and the heating region specifically means that the gas medium can flow along a pressure gradient from the inductor region to the heating region or vice versa. The insulating material is preferably designed to be substantially thermally stable, so that its properties remain essentially unchanged even at high temperatures. Furthermore, it is preferable that the heating region is formed as a substantially tunnel-shaped furnace channel.

[0013] In a preferred embodiment of the invention, the insulating material has at least one through-opening for a flow technology connection between the sensor region and the heating region. By providing a through-opening in the insulating material, a flow technology connection can be provided between the sensor region and the heating region in a structurally advantageous manner.

[0014] The at least one through opening preferably has a diameter of at least 1 mm and / or at least 1 mm. 2 The cross-section. Furthermore, the through opening of the at least one is preferably formed as substantially circular.

[0015] According to a preferred embodiment of the invention, at least one through opening can be at least partially closed by at least one baffle, thereby allowing for the regulation of gas or gas mixture exchange between the sensor region and the heating region.

[0016] A preferred embodiment of the invention features an insulating material designed to be at least partially permeable for flow technology connection between the sensor region and the heating region. By designing the insulating material to be at least partially permeable, an advantageous, substantially uniform flow technology connection can be provided across substantially the entire extent of the insulating material. The permeable material is preferably particularly breathable, allowing process gases and / or casing gases to flow from the sensor region into the heating region along a pressure gradient, and vice versa.

[0017] In another preferred embodiment of the invention, the insulating material comprises a fabric, particularly a fabric made of high-temperature fibers. By providing a fabric, a permeable material can be provided for the flow technology connection between the sensor area and the heating area. The fabric is preferably made of high-temperature fibers because these fibers are suitable for the temperatures present inside the furnace shell, particularly within the heating area. High-temperature fibers can be, for example, silicate glass fibers.

[0018] Another preferred embodiment of the invention is characterized in that the sensor region has at least one inlet for inputting the casing gas, and the control device regulates the feed of the casing gas into the sensor region, thereby creating a pressure gradient of the casing gas in the sensor region toward the process gas in the heating region. Since the pressure of the casing gas disposed in the sensor region is higher than the pressure of the process gas disposed in the heating region, the infiltration of process gas from the heating region into the sensor region can be reliably prevented. This prevents hot process gas from entering the sensor region. The inlet can also be used to charge the heating region with process gas. For example, the process gas and the casing gas can also be substantially the same gas and / or a mixture of gases. For example, the temperatures of the casing gas and the process gas can be different, with the temperature of the casing gas preferably being lower than that of the process gas.

[0019] The process gas is, in particular, a flammable gas, especially a flammable mixture, especially when mixed with oxygen. For example, the process gas can be a mixture of hydrogen and / or nitrogen or pure hydrogen. Therefore, by providing a pressure gradient, the process gas can be prevented from flowing from the heating zone into the inductor zone or furnace environment and from mixing with oxygen, thereby creating a flammable gas mixture. The casing gas is preferably an inert gas, such as nitrogen or a nitrogen mixture.

[0020] The aforementioned pressure gradient also allows the casing gas to maintain a substantially constant flow in the direction of the heating zone, thereby enabling continuous purging of the sensor area. The temperature of the process gas is preferably higher than that of the casing gas. For example, the composition of the process gas is the same as that of the casing gas. Alternatively, the composition of the process gas differs from that of the casing gas. The process gas is particularly a hydrogen mixture and / or a nitrogen mixture or pure hydrogen, while the casing gas is an inert gas, preferably nitrogen or a nitrogen mixture.

[0021] In another preferred embodiment of the invention, the inductor region has at least one outlet. By providing an outlet, when the equipment for induction heating of at least one workpiece is started, the furnace shell, including the inductor region and the heating region, can first be purged with a substantially inert gas, such as a shell gas, which is introduced through at least one inlet and discharged through at least one outlet. In this way, the interior of the furnace is free of ambient air. During operation of the equipment for induction heating of at least one workpiece, at least one outlet is preferably closed.

[0022] Another preferred design of the invention features that the device further includes at least one measuring device for measuring the pressure within the inductor region and / or the pressure within the heating region and / or the pressure difference between the inductor region and the heating region. By providing at least one measuring device, the regulation of the control device can be improved to deliver the casing gas into the inductor region. In particular, the casing gas can be used to purge the heating region containing the process gas, thereby reducing the temperature within the heating region and overall reducing the probability of ignition.

[0023] Furthermore, another aspect of the invention is characterized in that the device includes at least one flow measurement device for measuring the flow rate of the fed housing gas, and / or the device further includes at least one dew point measurement device for measuring the dew point of the gas mixture disposed in the sensor region and / or the dew point of the gas mixture disposed in the process region. By providing at least one of the aforementioned measuring devices, the regulation of the control device for feeding the housing gas into the sensor region can be improved.

[0024] In another preferred embodiment of the invention, the control device regulates the feed of the casing gas to the sensor region, creating a pressure gradient between the casing gas in the sensor region and the ambient air surrounding the furnace shell. This also prevents high-temperature and potentially flammable process gases from entering the furnace environment outside the furnace shell from the heating zone through the sensor region.

[0025] Another preferred embodiment of the invention features a transport device for transporting the workpiece to be induction heated along a substantially elongated extension of the heating zone. By providing such a transport device, substantially uniform heating can be provided along the entire length of the workpiece. For example, the speed of the workpiece to be moved can be variably adjusted by the transport device, thereby altering the heat treatment method of the workpiece.

[0026] In another preferred design, a thermal insulation device is provided between the insulating material and the heating area. In addition to the existing insulating material, the thermal insulation device further thermally isolates the sensor area from the heating area. The thermal insulation device is preferably formed similarly to the insulating material, so that a flow-through connection remains between the sensor area and the heating area through the separating surface and the thermal insulation device. The thermal insulation device can also be composed solely of the insulating material.

[0027] According to a second aspect of the present invention, the above-mentioned technical problem is solved in a method for induction heating at least one workpiece, particularly by means of the above-mentioned device, the method comprising the following steps:

[0028] - Guide the workpiece to be heated along the heating zone filled with process gas in the furnace shell;

[0029] - The workpiece is heated by at least one induction device arranged in an induction zone filled with the gas in the casing;

[0030] - Establishing a flow technology connection between the sensing area and the heating area, particularly through an insulating material arranged between the sensing area and the heating area; and

[0031] - Feed the casing gas into the sensor region to create a pressure gradient between the casing gas in the sensor region and the process gas in the heating region.

[0032] Here, the casing gas can be fed into the sensor region, for example, temporarily or continuously. Feeding the casing gas into the sensor region in an advantageous manner ensures that gas exchange only occurs towards the heating region, thus virtually preventing process gas from entering the sensor region from the heating region. Other advantages related to this method are described in conjunction with the aforementioned apparatus.

[0033] In one embodiment of the invention, the amount of housing gas to be fed in is determined based on the pressure difference between the sensor region and the heating region, and / or the amount of housing gas to be fed in is determined based on the housing gas flow rate between the sensor region and the heating region, particularly based on the housing gas volumetric flow rate. This allows for reliable control of the amount of gas or gas mixture to be fed in.

[0034] In another design of the above invention, the casing gas is fed into the sensor region, such that the temperature of the casing gas in the sensor region, particularly the average temperature, is lower than the temperature, particularly the average temperature, of the protective gas in the heating region. This further reduces the probability of ignition of gas that may enter the sensor region.

[0035] Another preferred embodiment of the invention features that, before guiding the workpiece to be heated along the heating zone of the furnace shell, the inductor area and the heating zone are first purged with shell gas; then process gas is fed into the heating zone; preferably, additional shell gas is subsequently introduced into the inductor area. This procedure ensures, in particular, that there is no critical residual air concentration in the furnace environment before the equipment is put into operation. It also helps to prevent the formation of condensate, preferably on the inductor unit.

[0036] Another advantageous design feature of the invention is that the gas mixture fed into the sensor region is obtained such that the dew point of the housing gas in the sensor region is shifted to a lower temperature compared to the dew point of the process gas in the process region, and / or the dew point of the housing gas in the sensor region is monitored substantially continuously, and the housing gas is subsequently fed in based on the dew point. In this way, reliable control of the fed gas mixture can be achieved. The temperature of the gas mixture entering the sensor region is preferably lower than the temperature of the process gas. Attached Figure Description

[0037] More advantageous exemplary embodiments of various aspects of the invention can be found in the detailed description of some exemplary embodiments of the invention below, particularly in conjunction with the accompanying drawings. However, the drawings in this application are for illustrative purposes only and are not intended to define the scope of protection of the invention. The drawings are not necessarily drawn to scale and are intended merely to exemplify the general concept of the invention. In particular, the features included in the drawings should in no way be construed as essential parts of the invention.

[0038] In the picture

[0039] Figure 1 A schematic diagram of a first embodiment of the device according to the invention is shown; and

[0040] Figure 2 A schematic diagram of a second embodiment of the device according to the present invention is shown. Detailed Implementation

[0041] In the following description of various embodiments of the present invention, components and elements having the same function and the same operating mode are referred to by the same reference numerals, even though the components and elements in the various embodiments may differ in size or shape.

[0042] Figure 1 A first embodiment of an apparatus 2 for induction heating of at least one strip workpiece 4 is shown. The apparatus 2 includes a furnace shell 6 and an inductor device 8 disposed inside the furnace shell 6. The inductor device 8 can completely surround the strip workpiece 4.

[0043] Sensor device 8 is arranged in sensor region 10, which is separated from heating region 14 by insulating material 12 (especially thermal insulating material). In addition to insulating material 12, thermal insulation device 16 is provided between insulating material 12 and heating region 14, wherein the design of insulating material 12 and thermal insulation device 16 enables flow technology connection between sensor region 10 and heating region 14.

[0044] For this purpose, the insulating material 12 has at least one through-opening 18 for fluid technology connection between the sensor region 10 and the heating region 14. Furthermore, the insulating material 12 is designed to be at least partially permeable, so that fluid technology exchange between the sensor region 10 and the heating region 14 can also occur away from the through-opening 18.

[0045] The sensor region 10 has an inlet 20 for supplying a gas mixture, particularly the casing gas, to the sensor region 10. Furthermore, a control device 22 is provided at the inlet 20 for regulating the feed rate of the casing gas into the sensor region 10, creating a pressure gradient from the casing gas arranged in the sensor region 10 towards the process gas arranged in the heating region 14. This prevents the process gas in the heating region 14 from flowing out of the sensor region 10 or the furnace shell.

[0046] The sensor area 10 also has an outlet 24. By providing outlet 24, the furnace shell 6 can be purged with a basically inert gas, such as the shell gas, when the device 2 is started.

[0047] In addition, the device has a measuring device 26 within the sensor area 10, a measuring device 28 within the heating area 14, and another measuring device 30 outside the furnace shell. For example, measuring devices 26, 28, and 30 can be used to measure the pressure present in the sensor area 10, the heating area 14, and / or the ambient air. Measuring devices 26 and 28 can also be used to measure the dew point of the gas or gas mixture present in the sensor area 10 and / or the heating area 14. The control device 22 may also have a measuring device for measuring the flow rate of the incoming casing gas.

[0048] Figure 2 A schematic side view of a second embodiment of the device 2 according to the present invention is shown. Figure 1 The embodiment of device 2 shown differs; the insulating material 12 is designed as a heat insulation device and has multiple through openings 18 for establishing a flow technology connection between the sensor region 10 and the heating region 14. At the start of the heating process, air in the furnace shell 6 can be purged, for example, by an inert gas through inlet 20. Therefore, the sensor region 10 and the heating region 14 can be purged. This prevents the process gas subsequently introduced into the sensor region 10 and the heating region 14 from reacting with the residual air in the furnace shell 6.

[0049] Explanation of reference numerals in the attached figures

[0050] 2 Equipment

[0051] 4. Workpiece

[0052] 6 furnace shells

[0053] 8. Sensor device

[0054] 10 Sensor Area

[0055] 12. Insulation materials

[0056] 14 Heating Zone

[0057] 16. Insulation device

[0058] 18 Through opening

[0059] 20 entrances

[0060] 22 Control device

[0061] 24 Exports

[0062] 26. Measuring device for sensor area

[0063] 28 Measuring device for the heating zone

[0064] 30. Ambient air measurement device

Claims

1. An apparatus for induction heating at least one workpiece (4), the apparatus comprising: At least one furnace shell (6); At least one sensor device (8) is arranged in the furnace shell (6), wherein the sensor device (8) is at least partially arranged in the sensor area (10) of the furnace shell (6); At least one heating zone (14) for receiving process gases is arranged inside the furnace shell (6); as well as Insulation material (12) for isolating the sensor area (10) and the heating area (14); Its features are, The insulating material (12) is formed as at least partially permeable material for flow technology connection between the sensor region (10) and the heating region (14). The permeable material is designed to be breathable. A heat insulation device (16) is provided between the insulating material (12) and the heating area (14), and The insulating material (12) and the heat insulation device (16) are formed to create a flow technology connection between the sensor area (10) and the heating area (14).

2. The device according to claim 1, Its features are, - The workpiece is a basically strip-shaped workpiece (4).

3. The device according to claim 1, Its features are, - The insulating material (12) is used to thermally isolate the sensor area (10) and the heating area (14).

4. The device according to claim 1, Its features are, - The insulating material (12) has at least one through opening (18) for flow technology connection between the sensor region (10) and the heating region (14).

5. The device according to any one of claims 1 to 4, Its features are, - Insulation material (12) includes fabric.

6. The device according to claim 5, Its features are, - The fabric is a high-temperature fiber fabric.

7. The device according to claim 1, Its features are, - The sensor region (10) has at least one inlet (20) for feeding housing gas; and - The control device (22) adjusts the feed of the housing gas to the sensor area (10) so that the housing gas in the sensor area (10) forms a pressure gradient in the direction of the process gas in the heating area (14).

8. The device according to claim 7, Its features are, - The sensor area (10) has at least one outlet (24).

9. The device according to any one of claims 7 or 8, Its features are, - The device also includes at least one measuring device (26, 28) for measuring the pressure in the sensor area (10) and / or the pressure in the heating area (14) and / or the pressure difference between the sensor area and the heating area.

10. The device according to claim 7, Its features are, - The device also includes at least one additional measuring device (26, 30) for measuring the pressure within the sensor area (10) and / or the pressure of the ambient air and / or the pressure difference between the sensor area and the ambient air.

11. The device according to claim 7, Its features are, - The device also includes at least one flow measurement device for measuring the flow rate of the feed gas into the housing, and / or - The device also includes at least one dew point measuring device (26, 28) for measuring the dew point of a gas mixture arranged in the sensor area (10) and / or the dew point of a gas mixture arranged in the process area.

12. The device according to claim 7, Its features are, - The control device (22) further adjusts the feed of the outer shell gas into the sensor area (10) so that a pressure gradient is formed from the outer shell gas in the sensor area (10) to the ambient air around the furnace shell (6).

13. The device according to claim 1, Its features are, - The device also includes a transport device for transporting the workpiece (4) to be induction heated along the basic longitudinal extension of the basic elongation of the heating zone (14).

14. A method for induction heating at least one workpiece using the apparatus according to any one of claims 1 to 13, the method comprising the steps of: - Guide the workpiece to be heated along the heating zone filled with process gas in the furnace shell; - The workpiece is heated by at least one induction device arranged in an induction zone filled with the gas in the casing; - Establish a flow technology connection between the sensor area and the heating area; as well as - Feed the casing gas into the sensor region to create a pressure gradient between the casing gas in the sensor region and the process gas in the heating region.

15. The method according to claim 14, Its features are, - The flow technology connection is established by an insulating material arranged between the sensor area and the heating area.

16. The method according to claim 14, Its features are, - The amount of casing gas to be fed in is determined based on the pressure difference between the sensor area and the heating area, and / or - The amount of casing gas to be fed in is determined based on the casing gas flow rate between the sensor area and the heating area, and / or - Feed the casing gas into the sensor area so that the temperature of the casing gas in the sensor area is lower than the temperature of the protective gas in the heating area.

17. The method according to claim 16, Its features are, - The amount of casing gas to be fed in is determined based on the casing gas volume flow rate.

18. The method according to claim 16, Its features are, - Feed the casing gas into the sensor area so that the average temperature of the casing gas in the sensor area is lower than the average temperature of the protective gas in the heating area.

19. The method according to claim 14, Its features are, - Before guiding the workpiece to be heated along the heating zone of the furnace shell, the sensor area and the heating zone are first purged by the outer shell gas; - Then the process gas is fed into the heating zone.

20. The method according to claim 19, Its features are, - Then another layer of outer casing gas is sent into the sensor area.

21. The method according to claim 14, Its features are, - Obtain a gas mixture fed into the sensor region such that the housing gas dew point in the sensor region shifts to a lower temperature compared to the process gas dew point in the process region, and / or - Essentially, it continuously monitors the dew point of the housing gas within the sensor area and feeds in housing gas based on the dew point.

Images