Induction welding method and device for induction welding

Abstract

This invention relates to an induction welding method, comprising the following steps: arranging a first connecting portion (11) and a second connecting portion (12); and using a first inductor (3) to bring the joint (17) of the first connecting portion (11) and the second connecting portion (12) from an initial temperature (T). A Induction preheating to below the specified welding temperature (T) S The preheating temperature (T) V ), of which, the preheating temperature (T) V ) and welding temperature (T) S The difference between the two is less than the initial temperature (T). A ) and preheating temperature (T) V The difference between the two; determine the preheated joint (17) of the first connecting part (11) and the second connecting part (12) to the welding temperature (T). S The required process parameters are based on the time and / or space temperature distribution of the preheated first connection part (11) and / or second connection part (12) and the specified welding temperature (T). S The process parameters are used to determine the welding temperature of the joint (17); the joint (17) is inductively heated to the welding temperature by means of the first sensor (3) or the second sensor (4) which is different from the first sensor; and the first connecting portion (3) is welded to the second connecting portion (4) at the joint (17).

Description

Technical Field

[0001] The present invention relates to an induction welding method for joining connection portions, preferably fiber reinforced plastic (FRP) connection portions, particularly FRP connection portions for aircraft components.

[0002] Furthermore, the present invention also relates to an apparatus for induction welding of joints, preferably fiber-reinforced plastic composite (FRP) joints, particularly FRP joints for aircraft components. Background Technology

[0003] Induction welding allows conductive and / or magnetic joints to be bonded together using a material-bonded method. In induction welding of conductive joints, an alternating magnetic field generated by an inductor induces eddy currents in the joints to be welded. These eddy currents dissipate due to electrical losses, heating the joints to the welding temperature. In the case of magnetic joints, hysteresis losses occur due to the alternating magnetic field until the Curie temperature is reached. These hysteresis losses also cause internal heating in the joints. Because the heating is non-contact and internal, the bonding pressure required for welding can be applied throughout the heating process. By heating, applying bonding pressure, and then cooling, a permanent bond is established between the joints.

[0004] Unlike most non-positive (also known as press fit) and positive (also known as tight fit) connection methods (e.g., connecting parts with screws, rivets, or bolts), induction welding better preserves the integrity of the material and the load-bearing capacity of the joint, and is not adversely affected by voids, etc. Furthermore, in mechanical connection methods, significant stress concentration occurs due to the precise application of force at the joint, which can lead to problems under subsequent loads, especially in thin-walled joints. Therefore, induction welding is often used in fields where high load-bearing capacity of the joint is particularly important, such as aerospace. Components made of fiber-reinforced plastic composites (FRP) are also commonly used in the aerospace industry due to their excellent physical properties associated with low density.

[0005] Besides system technology and component geometry, induction heating performance is significantly dependent on the material being heated. Compared to materials with homogeneous structures and isotropic material properties (such as metals), the induction heating performance of FRP materials is highly complex due to their non-uniform structure and anisotropic material properties. In this class of materials, induction heating performance typically depends on the thickness of the laminate, the type of reinforcing fibers, the type of semi-finished fibers, the lamination structure, the relative orientation and contact conditions between reinforcing fibers in adjacent layers, fiber volume and porosity, and the matrix polymer. All of these material parameters fluctuate more or less within permissible tolerances within the component. Even in the aerospace industry, where tolerances for material properties are typically very narrow, runaway or unpredictable induction heating performance cannot be prevented.

[0006] EP 3 802 072 B1 discloses an induction welding method in which a weak electromagnetic field of low strength is generated using a measuring inductor to induce eddy currents in fiber-reinforced plastic (FRP) joints. The eddy currents generated by the measuring inductor should only slightly heat the FRP joints. The electromagnetic field of the induced eddy currents is measured using a measuring coil of the measuring inductor, and the difference between the measured electromagnetic field strength and the field strength required for melting is determined. Then, a strong electromagnetic field of high strength is generated, taking into account the previously determined difference, and melts the FRP joints.

[0007] However, EP 3 802 072 B1 does not disclose how to determine the electric field strength required for melting the FRP joint. Another drawback of the induction welding method in EP3 802 072 B1 is its inability to account for deeper local inhomogeneities or material property deviations within the FRP joint. However, to achieve stable weld quality, it is desirable to be able to more precisely adjust the electromagnetic field used to melt the material based on the actual characteristics of the FRP joint. Furthermore, the method disclosed in EP 3 802 072 B1 suffers from insufficient precision in control or adjustment and is prone to overshooting.

[0008] EP 3 772 406 A1 discloses an induction welding method or apparatus in which an FRP portion to be welded to an end effector is preheated by one or more coils before welding. Preheating can be performed in a furnace or by induction heating. After preheating, the welding process is executed to weld the FRP portions together.

[0009] US 2003 / 0062118 A1 discloses an apparatus and method for welding fiber reinforced plastic (FRP) parts, wherein preheating is performed. The preheating is not performed by induction.

[0010] Both of the above methods employ only a controlled preheating process to shorten the heating time, thereby reducing the process time required to heat to the welding temperature in the downstream phase. Summary of the Invention

[0011] In view of the foregoing, the object of the present invention is to eliminate or at least mitigate the disadvantages of the prior art. Preferably, the object of the present invention is to provide an induction welding method and an apparatus for induction welding, which can better account for deviations in local material properties, inhomogeneities, transient effects (e.g., those occurring at the beginning and end of the weld), and variations in the geometry of the joint portion (e.g., the thickness of the joint portion). Preferably, the present invention also aims to adjust the temperature gradient present in the thickness direction of the joint portion. Furthermore, the present invention preferably aims to increase the process speed.

[0012] This objective is achieved by the induction welding method according to claim 1 and the apparatus for induction welding according to claim 13.

[0013] According to the present invention, the induction welding method of the type mentioned at the beginning provides the following steps:

[0014] Arrange the first connecting part and the second connecting part;

[0015] The first sensor preheats the joint between the first connecting portion and the second connecting portion from the starting temperature to a preheating temperature lower than the specified welding temperature, wherein the difference between the preheating temperature and the welding temperature is less than the difference between the starting temperature and the preheating temperature.

[0016] At least one process parameter is determined, particularly an induction generator setting parameter, which is the parameter required to heat the preheated joint of the first and second connecting parts to the welding temperature, wherein the at least one process parameter is determined based on the time and / or spatial temperature distribution of the preheated first and / or second connecting parts and a specified welding temperature, wherein the time and / or spatial temperature distribution is measured by a sensor device;

[0017] Using at least one process parameter, the joint between the first and second connecting portions is inductively heated to the welding temperature via a first sensor or a second sensor different from the first sensor; and

[0018] The first connecting part is welded to the second connecting part at the joint.

[0019] The method of the present invention heats the joint of the first and second connecting portions to a preheating temperature, which is closer to the specified welding temperature than the difference from the starting temperature. Therefore, even before welding, the joint reaches a relatively high temperature, allowing for better detection of deviations and inhomogeneities in material properties that only appear or become visible at higher temperatures, or those located deeper within the joint. Because the first and / or second connecting portions are preheated to a preheating temperature at the joint, which is closer to the welding temperature than the starting temperature, the accuracy of feedforward or feedback control in the induction welding method is also improved, as the joint only needs to reach the welding temperature from a relatively high preheating temperature. This also reduces the risk of overshooting in feedforward or feedback control. In the method according to the invention, a welding temperature is defined as the temperature at which the connecting portions can be welded to each other at the joint. Specifically, the welding temperature is a material-dependent temperature at which the connecting portions transition to a viscous state at the joint and are thus able to be joined to each other by material adhesive bonding. The polymer matrix of the joining portion is heated to the welding temperature, thereby melting the crystalline components of the amorphous and semi-crystalline polymers and forming a polymer melt. The viscosity of the polymer melt must be low enough to allow adjustment of the surface of the joining portion, particularly by applying bonding pressure, and to form an interface. The polymer chains can then diffuse through the interface, causing it to continuously dissolve. The degree of freedom of movement of the polymer chains increases with increasing temperature. In the case of a semi-crystalline thermoplastic joining portion, the welding temperature is higher than the melting temperature, preferably at least 20 K, at least 35 K, at least 50 K, at least 70 K, or at least 100 K higher. In the case of an amorphous thermoplastic joining portion, the welding temperature is higher than the glass transition temperature, for example, at least 80 K or at least 90 K higher. The first and / or second joining portion is preferably a fiber-reinforced plastic composite (FRP) joining portion, which is at least partially composed of FRP material. The FRP material has loose or woven fibers that are bonded to resin or other bonding methods. The bonding method can be, in particular, a thermoplastic material. The FRP material can be, for example, glass fiber reinforced plastic (GRP) or carbon fiber reinforced plastic (CRP). Steel fiber reinforced plastic can also be used. If the FRP material is GRP, it is advantageous to arrange one or more conductive elements, especially susceptors, at the joints.Examples of materials for the connecting portions include fiber-reinforced plastics, such as carbon fiber reinforced, glass fiber reinforced, and / or steel fiber reinforced plastics, with a matrix of polyamide (PA), polypropylene (PP), polyethylene (PE), polyphenylene sulfide (PPS), polyetherimide (PEI), polyethersulfone (PES), and thermoplastics from the polyaryletherketone (PAEK) group, such as LM-PAEK, polyetheretherketone (PEEK), or polyetherketoneketone (PEKK). Particularly preferably, the first and / or second FRP connecting portions are both for the production of aircraft components, such as aircraft control surfaces, particularly ailerons. However, the first and / or second connecting portions can also generally be used to produce aerospace components. Aerospace components can be, for example, components for spacecraft, satellites, drones, or other flying objects. FRP connecting portions can also be used to produce components for the automotive industry, particularly components for motor vehicles. For preheating and welding, the first and / or second connecting portions can be arranged on a support. The support can be formed from, for example, the surface of a workbench. According to one embodiment of the invention, the workbench may have a conveyor belt for conveying the connecting portions in one direction. To better secure the connecting portions, a support may be adapted to the shape of the first and / or second connecting portions. After arrangement, the joint of the first and second connecting portions is preheated from an initial temperature to a preheating temperature, which is lower than the welding temperature and closer to the welding temperature than the initial temperature. The initial temperature of the joint is preferably between 10°C and 40°C, particularly preferably approximately 24°C. The initial temperature refers to the temperature of the joint before preheating and welding. For FRP connecting portions containing semi-crystalline thermoplastics, the preheating temperature at the joint is preferably higher than the recrystallization temperature of the material. For FRP connecting portions containing amorphous thermoplastics, the preheating temperature is preferably higher than the glass transition temperature of the material used. For FRP connecting portions containing semi-crystalline thermoplastics, the preheating temperature is preferably between 90°C and 350°C. For FRP connecting portions containing amorphous thermoplastics, the preheating temperature is preferably between 175°C and 320°C. Due to preheating, heat energy is introduced into the first and / or second connection portions, and this heat energy is distributed in the first and / or second connection portions according to material properties. Preheating is performed using a first inductor. Multiple first inductors may also be used for preheating. The first inductor may be designed, for example, as a coil with at least one turn, preferably multiple turns. However, the shape of the inductor is not critical to the invention. Alternatively, a line inductor, particularly a wire with a preferably straight conductor segment, may also be used as the inductor. The first inductor is arranged such that the electromagnetic field it generates can penetrate the first and / or second connection portions and induce eddy currents.The first sensor generates an alternating electromagnetic field, the frequency of which is selected according to the material of the first and / or second connection portion, to induce eddy currents in at least one conductive loop composed of CF (carbon fiber). Preferably, the first sensor generates an alternating field for preheating, which has a constant magnetic field strength amplitude and a constant frequency. Therefore, the preheating temperature of the first and / or second connection portion after preheating is not spatially constant, but depends on the connection portion and its material properties, thus allowing conclusions about local material properties. The preheating process parameters, such as the amplitude and frequency of the alternating field and the exposure duration, can be determined empirically beforehand to achieve the preheating temperature at the joint of the first and / or second connection portions. The first sensor can be moved relative to the first and / or second connection portion, particularly relative to the joint. For this purpose, a conveyor belt can be used, for example, to move the first and / or second connection portion. As an alternative or additional option, the first sensor can be moved, for example, by a robot. The relative speed of the first sensor relative to the joint can also be used as a process parameter. The preheating temperature reached at the joint by the first and / or second connecting parts through preheating by the first inductor does not correspond to a precisely specified value, nor does it need to be constant in time and space. The precise preheating temperature and its distribution depend on the material properties of the first or second connecting parts. After the first and / or second connecting parts are preheated to the preheating temperature at the joint, at least one process parameter required to heat the joint to the specified welding temperature is determined, preferably based on the temperature of the first and / or second connecting parts, particularly the temporal and / or spatial distribution of the temperature. The process parameter may be determined based on local and / or temporal deviations or variations in temperature. The process parameter is preferably determined based on the deviation of the measured temperature from the target temperature. The temperature may be the preheating temperature itself or the surface temperature of the first and / or second connecting parts associated with the joint. A relationship between the surface temperature and the joint temperature can be established, for example, using mathematical models and simulations or empirical data. For example, empirical data can be obtained from experiments with connecting parts of different geometries and thicknesses. In this way, non-uniformity and other material properties can be taken into account and compensated for during welding. The goal is to compensate for deviations in material properties so that all joints are heated to the welding temperature. Process parameters can be represented, for example, induction generator setting parameters for the first or second sensor. For instance, if the temperature at a point on the first and / or second connection is lower than the temperature at an adjacent point, the amplitude of the electromagnetic field generated by the first or second sensor at that point can be increased accordingly to heat the joint to the welding temperature. As an additional or alternative, the relative moving speed of the first or second sensor and / or the distance between the first or second sensor and the first and / or second connection can be reduced at that point. Process parameters may include, for example, the magnetic field strength amplitude, frequency, current intensity, exposure duration, coupling distance, or moving speed of the sensor or the first or second connection.Process parameters can affect the heat generated at the joint, particularly increasing or decreasing the heat. Multiple process parameters can also be determined. By utilizing at least one process parameter, corresponding sensors are used to bring the joint of the first and second connecting portions to the welding temperature and compensate for deviations in material properties. Specifically, after determining the at least one process parameter, the first and second connecting portions are heated to the welding temperature. The at least one process parameter can be determined for each joint, and therefore these parameters can vary, in particular, with time and / or location. In other words, the process parameters can vary along the seam or the joining path formed by the joints. For FRP joints with semi-crystalline thermoplastics, the joint preferably reaches a welding temperature at least 20°C higher than the melting temperature of the corresponding connecting portion's material. For FRP joints with amorphous thermoplastics, the joint preferably reaches a welding temperature at least 80°C higher than the glass transition temperature of the corresponding connecting portion's material. During the execution of the method, the first and / or second sensors can be moved by a robot, particularly along the joint. The second sensor is a different sensor from the first sensor, wherein, in this context, "different" does not mean that the two sensors cannot be identical or similar. "Different" means that they are not the same sensor. Therefore, in one embodiment of the invention, the first and second sensors can be designed to be the same or similar. Preferably, the steps of the method are performed in the order shown.

[0020] In a preferred embodiment of the invention, the first sensor is deactivated or the joint is removed from the operating area of ​​the first sensor after induction preheating. Therefore, the heat energy introduced by preheating can be distributed in the first and / or second connection portions. The operating area of ​​the first sensor refers to the region where the alternating field of the first sensor causes the joint to heat. To remove the joint from the operating area, the first and / or second FRP connection portions or the first sensor can be moved.

[0021] In order to disperse the heat introduced after preheating and to detect material properties, it is advantageous to have an interval of at least 0.1 seconds between the end of induction preheating of the joint and the start of induction heating of the joint to the welding temperature.

[0022] In order to detect more material defects and inhomogeneities in the joint, the ratio of the difference between the preheating temperature and the welding temperature to the difference between the starting temperature and the preheating temperature should be at least 1:1.5, preferably at least 1:2, at least 1:2.5 or at least 1:3, and particularly at least 1:3.5 or at least 1:4, which is advantageous.

[0023] Advantageously, the at least one process parameter is determined based on the temporal and / or spatial temperature distribution of the preheated first and / or second connecting portions and a specified welding temperature, the temperature being measured by a sensor device. This temperature can be the surface temperature of the first and / or second connecting portions. The detected surface may deviate from the joint. As previously mentioned, the heating of the connecting portions depends on their material properties, including fiber reinforcement, fiber volume content, and the resistivity of the fibers used. When the first and / or second connecting portions are heated to the preheating temperature, the introduced heat diffuses in all spatial directions of the first and / or second connecting portions. However, because the characteristics of the connecting portions may differ locally, the electromagnetic field may cause locally different heating performance, resulting in different preheating temperatures at the joint. Therefore, the at least one process parameter for the corresponding joint can be determined based on the temperature of the first and / or second connecting portions or their temporal and / or spatial distribution. The process parameter is preferably determined based on the deviation between the measured temperature and the target temperature. In a particularly preferred embodiment, the surface temperature of the first and / or second connecting portions is measured, and the at least one process parameter is determined based on the deviation between the measured surface temperature and the desired surface temperature. The target temperature, particularly the surface target temperature, can be calculated using mathematical calculations, simulations, or empirical data, based on a specified welding temperature at the joint. If the determined process parameters are applied, after preheating, the surface is heated to the desired surface temperature using a first or second inductor, thereby bringing the joint to the welding temperature. In one example, if there are deviations in material properties resulting in poor heating performance, the amplitude of the magnetic field strength used to induce heating to the welding temperature will increase, causing a decrease in the relative movement of the inductor at the corresponding location and / or its distance from the first and / or second connection portions.

[0024] In a particularly preferred embodiment of the invention, the sensor device is formed of an optical temperature sensor, particularly a thermal imaging camera. Multiple sensor devices may also be provided. With the aid of the optical temperature sensor, particularly the thermal imaging camera, the temporal and / or spatial temperature distribution of the first and / or second connecting portions can be detected. The temperature or temperature distribution can be a surface temperature or a surface temperature profile. As heat diffuses through the first and / or second connecting portions, the preheating temperature at the joint can be inferred, for example, using a mathematical model or simulation.

[0025] A particularly efficient embodiment of the invention is achieved by using a second sensor, different from the first sensor, for induction heating, and by arranging the first and second sensors spaced apart from each other along the process path. In this way, the joint can be preheated by the first sensor, the first and / or second connecting portions can be further conveyed to the second sensor, and then the joint can be heated to the welding temperature by the second sensor. The induction welding method is performed along the process path. The process path may include a conveyor belt. However, one or more robots may also be used to transport the first and / or second connecting portions from the first sensor to the second sensor. One or more robots may also be used to move the first and / or second sensors to the joint.

[0026] It is particularly advantageous if the sensor device is arranged between the first and second sensors. In this way, after preheating by the first sensor, the sensor device can be used to determine the at least one process parameter for the second sensor, and then the second sensor can be used to heat the joint to the welding temperature.

[0027] Before, during, and / or after welding the first connection to the second connection, cooling the first and / or second connection with a fluid flow, particularly an airflow, can promote the concentration of heat at the joint. Cooling of the first and / or second connection can also be arranged before, during, and / or after preheating. Cooling of the first and / or second connection can also be arranged using a sensor device before, during, and / or after measuring the temperature of the first and / or second connection. Cooling is preferably performed by a fluid. Compressed air or water-based aerosol is preferred as the fluid flow. The fluid, particularly gas, can be brought to the joint by a fan and preferably guided to the joint by a nozzle. A constant fluid flow can be used. The fluid flow can also be regulated and / or controlled. As an additional or alternative, cooling can be performed using a sliding shoe or by a cooling plate, particularly a fixed cooling plate.

[0028] To form an adhesive bond between the connecting parts, it may be advantageous to press the first and second connecting parts together after induction heating to the welding temperature by a first or second inductor. The pressing element can be designed as a pressing roller to press the first and / or second connecting parts with an adjustable pressing force. The consolidation pressure generated at the joint is preferably between 1 bar and 100 bar.

[0029] The preheating and welding temperatures depend on the materials used. The initial temperature can be between 10°C and 40°C. If the first and / or second joining portion comprises a semi-crystalline thermoplastic material, the preheating temperature can be between 90°C and 350°C. If the first and / or second joining portion comprises an amorphous thermoplastic material, the preheating temperature can be between 175°C and 320°C. If the first and / or second joining portion comprises a semi-crystalline thermoplastic material, the welding temperature can be between 140°C and 460°C. If the first and / or second joining portion comprises an amorphous thermoplastic material, the welding temperature can be between 250°C and 380°C.

[0030] In an exemplary embodiment, the following preheating temperature and welding temperature are used for the following materials:

[0031] Fiber-reinforced plastics, the matrix of which is:

[0032] Polyethylene (PE):

[0033] Preheating temperature: 90℃ to 130℃

[0034] Welding temperature: 140℃ to 190℃

[0035] Polypropylene (PP):

[0036] Preheating temperature: 120℃ to 150℃

[0037] Welding temperature: 180℃ to 210℃

[0038] Polyamide 6 (PA6):

[0039] Preheating temperature: 160℃ to 210℃

[0040] Welding temperature: 240℃ to 290℃

[0041] Polyamide 6.6 (PA66):

[0042] Preheating temperature: 180℃ to 250℃

[0043] Welding temperature: 280℃ to 320℃

[0044] Polyamide 12 (PA12):

[0045] Preheating temperature: 120℃ to 165℃

[0046] Welding temperature: 200℃ to 250℃

[0047] Polyphenylene sulfide (PPS):

[0048] Preheating temperature: 200℃ to 285℃

[0049] Welding temperature: 310℃ to 370℃

[0050] Polyetherimide (PEI):

[0051] Preheating temperature: 220℃ to 320℃

[0052] Welding temperature: 300℃ to 380℃

[0053] Polyethersulfone (PES):

[0054] Preheating temperature: 220℃ to 320℃

[0055] Welding temperature: 300℃ to 380℃

[0056] Low melting point polyaryletherketone (LM-PAEK):

[0057] Preheating temperature: 210℃ to 300℃

[0058] Welding temperature: 330℃ to 430℃

[0059] Polyetheretherketone (PEEK):

[0060] Preheating temperature: 235℃ to 330℃

[0061] Welding temperature: 360℃ to 460℃

[0062] Polyetherketoneketone (PEKK):

[0063] Preheating temperature: 200℃ to 350℃

[0064] Welding temperature: 320℃ to 450℃

[0065] For all the materials mentioned, the starting temperature can be between 10°C and 40°C.

[0066] In one embodiment of the invention, the first and / or second connecting portions are designed as laminates and are preferably arranged to be stacked vertically.

[0067] The aforementioned objective is also achieved by the apparatus for induction welding according to claim 13. According to the invention, the apparatus comprises:

[0068] A first sensor is used to sense heating of the first connection portion and / or the second connection portion;

[0069] Optionally, a second sensor, different from the first sensor;

[0070] The control unit is configured to perform the following steps:

[0071] - Feedforward control and / or feedback control are applied to the first sensor so that the first sensor preheats the joint between the first connection portion and the second connection portion from the starting temperature to a preheating temperature below the specified welding temperature, wherein the difference between the preheating temperature and the welding temperature is less than the difference between the starting temperature and the preheating temperature.

[0072] - Determine at least one process parameter, particularly an induction generator setting parameter, which is the parameter required to heat the preheated joint to the welding temperature, wherein the at least one process parameter is determined based on the temporal and / or spatial temperature distribution of the preheated first and / or second joint portions and a specified welding temperature, wherein the temperature distribution is measured by a sensor device; and

[0073] - Feedforward and / or feedback control is applied to the first sensor or an optional second sensor to heat the joint to the welding temperature using the at least one process parameter, so that the first connection portion can be welded to the second connection portion at the joint.

[0074] An induction welding apparatus is designed to perform the aforementioned induction welding method. The advantages and features associated with the induction welding method described above can also be transferred to the apparatus used for induction welding. The apparatus may be equipped with a support, particularly a workbench, on which the connecting portion may be arranged. In one embodiment of the invention, a first sensor and an optional second sensor may be arranged above the support. The support may be equipped with a conveying device, particularly a conveyor belt, to move the connecting portion relative to the first sensor and the optional second sensor. At least one robot may also be provided, capable of moving the connecting portion or one or more sensors. The second sensor is a different sensor from the first sensor, wherein, in this context, "different" does not mean that the two sensors cannot be the same or similar. "Different" means that they are not the same sensor. Therefore, the first and second sensors may be designed to be the same or similar.

[0075] To determine the at least one process parameter, it is advantageous to configure the sensor device to detect the temporal and / or spatial temperature distribution of the first and / or second connection portions. The sensor device can be arranged, for example, above a support member. In particular, the surface temperature of the first and / or second connection portions can be detected using the sensor device.

[0076] It is preferable to provide a second sensor and arrange the sensor device between the first and second sensors. In this embodiment, the joint is preheated by the first sensor, and then the temperature of the joint, particularly the time and / or spatial temperature distribution, is detected by the sensor device (preferably a thermal imaging camera). Then, using the at least one determined process parameter, the joint is heated to the welding temperature by the second sensor.

[0077] The directional indications in this disclosure relate to the intended use of the apparatus for induction welding.

[0078] The present invention can also be described based on the following exemplary embodiments:

[0079] Exemplary Example 1: An induction welding method for joining connection portions, preferably fiber-reinforced plastic composite (FRP) connection portions, particularly FRP connection portions for aircraft components, the method comprising the following steps:

[0080] Arrange the first connecting part and the second connecting part;

[0081] The first sensor preheats the joint between the first connecting portion and the second connecting portion from the starting temperature to a preheating temperature lower than the specified welding temperature, wherein the difference between the preheating temperature and the welding temperature is less than the difference between the starting temperature and the preheating temperature.

[0082] Determine at least one process parameter, particularly the induction generator setting parameter, which is the parameter required to heat the preheated joint of the first and second connecting parts to the welding temperature;

[0083] Using at least one process parameter, the joint between the first and second connecting portions is inductively heated to the welding temperature via a first sensor or a second sensor different from the first sensor; and

[0084] The first connecting part is welded to the second connecting part at the joint.

[0085] Exemplary Example 2: The induction welding method according to Exemplary Example 1 is characterized in that, after induction preheating, the first inductor is deactivated or the joint is removed from the working area of ​​the first inductor.

[0086] Exemplary Example 3: The induction welding method according to Exemplary Example 1 or 2 is characterized in that there is a time interval of at least 0.1 seconds between the end of induction preheating of the joint using the first inductor and the start of induction heating of the joint to the welding temperature.

[0087] Exemplary Example 4: The induction welding method according to any one of Exemplary Examples 1 to 3 is characterized in that the ratio of the difference between the preheating temperature and the welding temperature to the difference between the starting temperature and the preheating temperature is at least 1:1.5, preferably at least 1:2, at least 1:2.5 or at least 1:3, particularly at least 1:3.5 or at least 1:4.

[0088] Exemplary Example 5: The induction welding method according to any one of Exemplary Examples 1 to 4, characterized in that the at least one process parameter is determined based on the temperature T (particularly the time and / or spatial temperature distribution) of the first and / or second connection portions after preheating and a specified welding temperature, wherein the temperature T is measured by a sensor device.

[0089] Exemplary Example 6: The induction welding method according to Exemplary Example 5 is characterized in that the sensor device is formed of an optical temperature sensor, particularly a thermal imaging camera.

[0090] Exemplary Example 7: The induction welding method according to any one of Exemplary Examples 1 to 6 is characterized in that a second inductor, different from the first inductor, is used for induction heating, and the first inductor and the second inductor are arranged at intervals from each other along the process path.

[0091] Exemplary Example 8: The induction welding method according to Exemplary Example 7 and Exemplary Example 5 or 6, characterized in that the sensor device is arranged between the first sensor and the second sensor.

[0092] Exemplary Example 9: The induction welding method according to any one of Exemplary Examples 1 to 8 is characterized in that, before, during and / or after welding the first connecting portion to the second connecting portion, the first connecting portion and / or the second connecting portion are preferably cooled by a fluid flow, particularly an airflow.

[0093] Exemplary Example 10: The induction welding method according to any one of Exemplary Examples 1 to 9 is characterized in that, after being heated to the welding temperature by induction heating through the first or second inductor, an extrusion element, particularly an extrusion roller, presses the first connecting portion and the second connecting portion together.

[0094] Exemplary Example 11: The induction welding method according to any one of Exemplary Examples 1 to 10, characterized in that,

[0095] - The initial temperature is between 10°C and 40°C; and

[0096] - If the first and / or second connecting portions comprise a semi-crystalline thermoplastic material, the preheating temperature is in the range of 90°C to 350°C; or, if the first and / or second connecting portions comprise an amorphous thermoplastic material, the preheating temperature is in the range of 175°C to 320°C; and

[0097] - If the first and / or second connecting portions comprise a semi-crystalline thermoplastic material, the welding temperature is in the range of 140°C to 460°C; or, if the first and / or second connecting portions comprise an amorphous thermoplastic material, the welding temperature is in the range of 250°C to 380°C.

[0098] Exemplary Example 12: The induction welding method according to any one of Exemplary Examples 1 to 11, characterized in that the first connecting portion and / or the second connecting portion is designed as a laminate, wherein the laminate is preferably arranged to be stacked vertically.

[0099] Exemplary Example 13: An apparatus for induction welding of a joint portion, preferably a fiber-reinforced plastic composite (FRP) joint portion, particularly an FRP joint portion for aircraft components, the apparatus comprising:

[0100] A first sensor is used to sense heating of the first connection portion and / or the second connection portion;

[0101] Optional, a second sensor different from the first sensor;

[0102] The control unit is configured to perform the following steps:

[0103] - Feedforward control and / or feedback control are applied to the first sensor so that the first sensor preheats the joint between the first connection portion and the second connection portion from the starting temperature to a preheating temperature below the specified welding temperature, wherein the difference between the preheating temperature and the welding temperature is less than the difference between the starting temperature and the preheating temperature.

[0104] - Determine at least one process parameter, particularly the setting parameters of the induction generator, which are the parameters required to heat the preheated joint to the welding temperature; and

[0105] - Feedforward and / or feedback control is applied to the first sensor or an optional second sensor to heat the joint to the welding temperature using the at least one process parameter, so that the first connection portion can be welded to the second connection portion at the joint.

[0106] Exemplary Example 14: The apparatus according to Exemplary Example 13 is characterized in that it includes a sensor device configured to detect the temperature of the first and / or second connection portions, particularly the time-temperature distribution.

[0107] Exemplary Example 15: The apparatus according to Exemplary Example 14 is characterized in that a second sensor is provided, and a sensor device is arranged between the first sensor and the second sensor. Attached Figure Description

[0108] The invention will now be described in more detail with reference to the accompanying drawings, but the invention is not limited to these drawings. In the drawings:

[0109] Figure 1 A schematic side view of an apparatus for induction welding is shown;

[0110] Figure 2A -C illustrates a schematic temperature distribution across the thickness of the connecting portion at different process times according to the first embodiment;

[0111] Figure 3A -C illustrates a schematic temperature distribution across the thickness of the connecting portion at different process times according to the second embodiment;

[0112] Figure 4A -C illustrates a schematic temperature distribution across the thickness of the connecting portion at different process times according to the third embodiment; and

[0113] Figure 5A -C illustrates a schematic temperature distribution across the thickness of the connecting portion at different process times according to the first embodiment;

[0114] Figure 6 The temperature distribution of a welding method from the prior art is shown;

[0115] Figure 7 The temperature distribution of a welding method from the prior art is shown; and

[0116] Figure 8 The temperature distribution of the welding method according to the present invention is shown. Specific Implementation

[0117] Figure 1 An apparatus 1 is shown for inductively welding connecting portions 11 and 12 to form a component 2, such as a component 2 for an aircraft (not shown). The apparatus 1 includes a first sensor 3 and a second sensor 4, which are spaced apart from each other along a process path 5 when viewed from the process direction 6. Multiple first sensors 3 and / or multiple second sensors 4 may also be provided. In the exemplary embodiment shown, the first sensors 3 and the second sensors 4 are identically designed. Both sensors 3 and 4 have a current supply section 7 and a coil section 8 with at least one winding 9. The coil sections 8 of the sensors 3 and 4 are aligned such that the alternating electromagnetic field 10 generated by the respective sensors 3 and 4 can penetrate into the first connecting portion 11 and the second connecting portion 12, generating eddy currents 50 therein, thereby heating the first connecting portion 11 and the second connecting portion 12. In the figure shown, the sensors 3 and 4 are arranged above the first connecting portion 11 and the second connecting portion 12.

[0118] exist Figure 1 In this embodiment, a sensor device 13 in the form of a thermal imaging camera 14 is arranged between the first sensor 3 and the second sensor 4. This sensor device is capable of detecting the temperature T of the first connecting portion 11 and the second connecting portion 12, and particularly the temporal and / or spatial profile of the temperature of the first connecting portion 11 and / or the second connecting portion 12. The temperature T or temperature profile can be a surface temperature or a surface temperature distribution. In the exemplary embodiment shown, the thermal imaging camera 14 is also arranged above the first connecting portion 11 and the second connecting portion 12 and points downwards. The sensor device 13 and the sensors 3 and 4 can be connected to the control unit 51.

[0119] In the exemplary embodiment shown in this invention, both the first connecting portion 11 and the second connecting portion 12 are designed as flat laminates 15a and 15b, and are arranged stacked vertically. The connecting portions 11 and 12 can be welded to form component 2, particularly for aircraft (not shown). Using the induction welding apparatus 1, the two connecting portions 11 and 12 can be welded together along a joining path 16, which can also be called a seam, consisting of continuously converging joints 17 located between the laminates of the connecting portions 11 and 12. For this purpose, the connecting portions 11 and 12 are placed on a support (not shown), which may have a conveyor belt (also not shown) for transporting the connecting portions 11 and 12 in the process direction 6. Alternatively, the sensors 3 and 4 can be moved along the connecting portions 11 and 12 while the connecting portions 11 and 12 remain in place. Using the first sensor 3, the joint 17 is moved from an initial temperature T... A (For example, this could correspond to a room temperature between 10°C and 40°C, such as 24°C) Preheat to a preheating temperature T V The preheating temperature T V Not specified as an exact value. To ensure that the joint 17 reaches the preheating temperature T... V The first sensor 3 generates an alternating electromagnetic field 10 with a constant magnetic field strength amplitude and a constant frequency. When the connecting portions 11 and 12 are conveyed at a relative speed v in the process direction 6, passing beneath the first sensor 3, this electromagnetic field induces eddy currents 50 in the connecting portions 11 and 12. The values ​​of frequency, amplitude, and conveying speed v (all of which can be referred to as process parameters) can be predetermined for the materials of the connecting portions 11 and 12 through empirical methods, mathematical models, or simulations, so that the joint reaches a preheating temperature T. V For example, the first sensor 3 can operate at a frequency between 100 kHz and 1 MHz. The relative speed between the first sensor and the connection portion can be between 50 mm / min and 2000 mm / min. Process parameters are selected such that the preheating temperature T...V Below welding temperature T S However, the preheating temperature T V With welding temperature T S The difference between them is less than the initial temperature T. A With preheating temperature T V The difference between them. In other words, the joint of connecting parts 11 and 12 is heated to a preheating temperature T. V Compared to the initial temperature T A The difference is that the preheating temperature is closer to the welding temperature.

[0120] As mentioned earlier, the preheating temperature T V It does not correspond to a specific value. The only important thing is that the temperature to which the first sensor 3 heats the joint 17 is different from the starting temperature T. A The difference is closer to the welding temperature T. Advantageously, the preheating temperature T... V With welding temperature T S The difference between them and the initial temperature T A With preheating temperature T V The ratio of the differences is at least 1:1.5, preferably at least 1:2, 1:2.5, or 1:3, and particularly at least 1:3.5 or 1:4. For the connecting portions 11 and 12 containing semi-crystalline thermoplastic, the preheating temperature T at the joint is... V Preferably, the preheating temperature is higher than the recrystallization temperature of the material. For the connecting parts 11 and 12 containing amorphous thermoplastic, the preheating temperature T is... V Preferably, it is higher than the glass transition temperature of the material used.

[0121] When the connecting parts 11 and 12 are heated, the introduced heat energy diffuses in all spatial directions within the connecting parts 11 and 12. However, due to the potential local differences in the characteristics of the connecting parts 11 and 12 (fiber volume content, resistivity, etc.), such as due to inhomogeneity or small material defects, this may lead to different heating performances in different areas, resulting in different preheating temperatures T at different points in the connecting parts 11 and 12. V .

[0122] If not counteracted, the varying local heating properties could also lead to different local temperatures during welding, altering the weld quality. However, the goal is to achieve a uniform welding temperature T at the joint 17. STo achieve uniform welding quality, the varying heating properties in different areas should be compensated for during the welding process. To this end, at least one process parameter is determined for each welding point 17, which is determined by heating the preheated joint 17 of the first connecting portion 11 and the second connecting portion 12 to a specified welding temperature T using the second inductor 4. S The required parameters. Therefore, compared to the joint 17 with better heating performance, the joint 17 with poorer heating performance is heated with a relatively higher electric field strength. This is achieved by heating to a relatively high preheating temperature T. V Furthermore, deviations in material properties, as well as non-uniformity that occurs or is visible only at higher temperatures or is located deeper in the connection parts 11 and 12, can also be taken into account.

[0123] To determine the at least one process parameter, a sensor device 13, designed as a thermal imaging camera 14 in the illustrated example, is disposed between the first sensor 3 and the second sensor 4. The sensor device 13, like the sensors 3 and 4, is positioned above the connecting portions 11 and 12. The sensor device 13 is designed to detect the temperature T, particularly the temporal and / or spatial distribution of the surface temperature of the connecting portions 11 and 12. The sensor device 13 can be used to detect deviations in material properties that lead to different heating performances and to determine at least one process parameter for the second sensor 4. This process parameter can be used to compensate for localized deviations in heating performance and to bring the corresponding joint 17 to the welding temperature T. S In a particularly preferred embodiment, the surface temperature of the first connecting portion 11 and / or the second connecting portion 12 is measured, and the at least one process parameter is determined based on the deviation between the measured surface temperature and the desired surface temperature. The desired surface temperature can be determined through mathematical calculations, simulations, or empirical data, based on a specified welding temperature T at the joint. S Calculations show that at least one process parameter can be determined for each joint 17. This process parameter can be, for example, the amplitude and frequency of the magnetic field strength, the distance between the second sensor 4 and the joint 17, or the relative velocity between the second sensor 4 and the joint. Alternatively, it can be based on the preheating temperature T. V Multiple process parameters can be determined. Alternatively, it can be configured to determine only one or more process parameters, such as the amplitude and frequency of the magnetic field strength, while other process parameters—such as the relative velocity and distance between the second inductor 4 and the joint 17—remain fixed. For example, if there is a deviation in heating performance at a certain point, the amplitude of the magnetic field strength used at that point can be adjusted accordingly, i.e., decreased or increased. Through simulation, mathematical models, or empirical data, process parameters can be selected to achieve the welding temperature T at the joint 17. S .

[0124] After preheating and determining the at least one process parameter, the joint 17 is heated to the welding temperature T along the joining path 16 using the at least one process parameter previously determined for the joint 17. S Welding temperature T S This is specified and depends on the materials of the connecting parts 11 and 12. For connecting parts 11 and 12 containing semi-crystalline thermoplastic materials, a welding temperature T of, for example, 400°C can be specified. S When heated to welding temperature T S When the connecting parts 11 and 12 are heated to the point that the material at the joint 17 becomes viscous, a material bonding connection can be formed between the connecting parts 11 and 12.

[0125] In order to connect the connecting portions 11 and 12, in the illustration of process direction 6, an extrusion element 20 is arranged downstream of the second sensor 4. The extrusion element takes the form of a rotatably mounted extrusion roller 21, which can apply extrusion pressure or consolidation pressure to the connecting portions 11 and 12 at the joint 17 to promote the material bonding of the connecting portions 11 and 12.

[0126] To promote heat distribution within the connecting portions 11 and 12 and concentrate heat energy particularly on the joint 17, the device 1 may include a cooling device 22. The cooling device 22 may be configured to superficially cool the connecting portions 11 and 12 before, during, and / or after preheating. Furthermore, the cooling device 22 may be configured to superficially cool the connecting portions 11 and 12 before, during, and / or after temperature T is detected by the sensor device 13. Additionally, the cooling device 22 may be configured to cool the surfaces of the connecting portions 11 and 12 to the welding temperature T before, during, and / or after heating the connecting portions 11 and 12. S Cooling device 22 can be used, for example, to guide gas 23 (especially air) from above onto the connecting portions 11, 12. As an additional or alternative, cooling device can be used to dissipate heat from the laminate through heat conduction in the form of a radiator.

[0127] In the illustrations, connecting portions 11 and 12 are FRP connecting portions, and are at least partially composed of a semi-crystalline thermoplastic material (particularly CRP). In this exemplary embodiment, the preheating temperature T... V T is the melting temperature of the material. M (i.e., 310℃) 20℃ to 60℃ below. The welding temperature is the melting temperature T. M The temperature ranges from 40°C to 120°C.

[0128] Figure 2A -C、 Figure 3A -C、 Figure 4A -C and Figure 5A -C shows schematic temperature profiles along the cross-section of the upper laminate 15a (first connecting portion 11) at different times during the induction welding process, illustrated in three figures (denoted by letters A, B, and C). Figures A, B, and C constitute a set of figures. The horizontal axis represents the normalized thickness d of the upper laminate 15a, based on its maximum thickness. Position "0" corresponds to the upper side of the upper laminate 15a facing the inductors 3 and 4. Position "1" represents the lower side of the upper laminate 15a facing the lower laminate 15b (second connecting portion 12) and thus the joint 17 of the joining path 16. The vertical axis represents the temperature T. d This temperature represents the temperature at each thickness position in the upper platen 15a.

[0129] In the group of pictures Figure 2A -C、 Figure 3A -C、 Figure 4A -C and Figure 5A -C relates to different embodiments of device 1, the difference being that the connecting portions 11, 12 are cooled by the cooling device 22 at different locations in device 1. Figures bearing the same letters A, B, and C correspond to the same time points during the induction welding method.

[0130] Figure 2A -C shows a diagram where cooling via cooling device 22 is not performed. (See diagram 22.) Figure 2A As shown, the temperature T at the top of the upper platen 15a during preheating d Slightly below the material's melting temperature T M After the joint 17 is transferred out of the working area of ​​the first sensor 3, the introduced heat energy is dispersed, so that a basically constant temperature T is established within the thickness d range of the upper platen 15a. d (See Figure 2B This temperature is approximately the melting temperature T. M The preheating temperature T at the joint 17 located at the bottom of the upper laminate 15a is 20℃ - 100℃. V exist Figure 2B The temperature T corresponding to the top of the laminate 15a d Then, using the second sensor 4 and the process parameters, the joint 17 is heated to the welding temperature T. S For semi-crystalline thermoplastic materials, the welding temperature is typically higher than the material's melting temperature, T. M The temperature is approximately 40°C to 100°C higher. Figure 2C The joint 17 is shown at the start of heating to the welding temperature T. S The initial temperature Td. After a period of time (not shown), the introduced heat energy penetrates the connection portion 11, causing the joint 17 to reach the welding temperature T. SHowever, as Figure 3A-5C As shown, it is advantageous to cool the connecting portion 11 to prevent the temperature Td at the top from rising too high.

[0131] Figure 3A -C shows a set of graphs, where heating to welding temperature T S During the process, the area of ​​the second sensor 4 is cooled by the cooling device 22. Figure 3A and 3B Temperature distribution and Figure 2A and 2B The corresponding one. However, from Figure 3C It can be seen that the upper side of the upper laminate 15a has a lower temperature Td compared to the lower side of the upper laminate 15a where the joint 17 is located. In the region of the joint 17, the temperature of the laminate 15 is the welding temperature T. S Cooling prevents the top of the laminate 15a from melting and concentrates heat on the joint 17 at the bottom of the laminate 15a.

[0132] Figure 4A -C shows a diagram where the cooling device 22 cools the area between the first inductor 3 and the second inductor 4 after preheating, while cooling is performed after heating to the welding temperature T. S During the process, cooling is carried out in the area of ​​the second sensor 4. 。 Figure 4A Temperature distribution and Figure 2A and Figure 3A Corresponding to the distribution curve. From Figure 4B It can be seen that after the joint 17 is transferred out of the working area of ​​the first sensor 3, it is cooled on the upper side of the upper platen 15a, and the temperature T d Reduced to recrystallization temperature T K Below. On the lower side, i.e., on the side of the joint 17, the laminate 15 has a preheating temperature T. V The preheating temperature is higher than the melting temperature T. M Temperatures are approximately 20°C to 60°C lower, but higher than the recrystallization temperature T. K . Figure 4C The laminate 15a is shown to have a welding temperature T at the bottom where the joint 17 is located. S The top is cooler. Cooling prevents the top of the upper platen 15a from melting and concentrates heat on the joint 17.

[0133] Figure 5A -C shows a set of figures in which the cooling device 22 cools the region of the first inductor 3 during preheating, cools the region between the first inductor 3 and the second inductor 4 after preheating, and cools the region between the first inductor 3 and the second inductor 4 after heating to the welding temperature T. S Cooling is carried out in the area of ​​the second sensor 4 during the process.。 During the preheating process (see...) Figure 5A ) and after preheating ( Figure 5B Cooling reduces the temperature T at the top of the upper platen 15a. d Reduce. When the joint 17 is heated to the welding temperature T S At that time, the temperature T on the upper side is reduced by cooling the upper platen 15a. d Reduced to recrystallization temperature T K The following is the welding temperature T. S It appears on the underside of the joint 17 of the laminate 15a.

[0134] like Figure 2A-5C As shown, by means of the method of the present invention, especially when combined with the cooling device 22, a defined temperature distribution can be generated at the joint 17.

[0135] Figure 6 , Figure 7 and Figure 8 The spatial temperature distribution T along the bonding path 16 in process direction 6 is shown. x Here, x represents the relative distance traveled in the process direction. At the start of joining path 16, the value of x is 0, and at the end of joining path 16, the value of x is 1. "B" indicates heating to the preheating temperature T. V “C” indicates heating to welding temperature T. S .

[0136] Figure 6 This illustrates heating C to the welding temperature T via an induction heater, as is known in the prior art. S Instead of preheating via another inductor, this method differs from the present invention in that only one heating process is performed, through which the welding temperature T at the joint 17 is determined. S This was achieved. Due to localized non-uniformity and defects in the first connecting portion 11 and the second connecting portion 12, the welding temperature T... S Deviations can occur. These deviations lead to poor welding quality.

[0137] Figure 7 Heating B and subsequent heating C are shown, wherein in heating B, the engagement path 16 is brought to a preheating temperature T by the first sensor 3. V In the subsequent heating C, the second inductor 4 brings the bonding path 16 to the welding temperature, regardless of the preheating temperature T. V The final distribution. The first sensor 3 and the second sensor 4 both operate with different but constant process parameters. Figure 7 In, with Figure 6 The temperature distribution in C is similar to that in B, but the temperature distribution during heating reveals localized inhomogeneities and defects in the material. Because... Figure 7 Since there is no adjustment for heating C based on the previous heating B, local non-uniformity and defects will also cause deviations from the welding temperature T after heating C. S .

[0138] Figure 8 The method of the present invention is illustrated, and local non-uniformity and defects along the bonding path 16 during heating B are shown. However, heating C is adjusted here by determining or adjusting process parameters based on the temperature distribution of heating B, so that the welding temperature T is continuously reached along the bonding path 16. S Therefore, very good welding quality can be obtained.

Claims

1. An induction welding method for joining connection portions, the method comprising the following steps: Arrange the first connecting part (11) and the second connecting part (12); The first sensor (3) connects the joint (17) of the first connecting part (11) and the second connecting part (12) from the starting temperature (T). A Induction preheating to below the specified welding temperature (T) S The preheating temperature (T) V ), wherein the preheating temperature (T) V ) and the welding temperature (T) S The difference between the two is less than the initial temperature (T). A ) and the preheating temperature (T) V The difference between ) Determine at least one process parameter, which is to heat the preheated joint (17) of the first connecting portion (11) and the second connecting portion (12) to the welding temperature (T). S The required parameters, wherein the at least one process parameter is based on the time and / or spatial temperature distribution of the preheated first connection portion (11) and / or second connection portion (12) and the specified welding temperature (T). S The time and / or spatial temperature distribution is determined by means of a sensor device (13), wherein the sensor device (13) is formed of an optical temperature sensor; Using the first sensor (3) or a second sensor (4) different from the first sensor, and with the at least one process parameter, the joint (17) of the first connecting portion (11) and the second connecting portion (12) is inductively heated to the welding temperature (T). S ), wherein the deviation in material properties between the first connecting portion (11) and the second connecting portion (12) is compensated by utilizing at least one process parameter; and The first connecting portion (11) is welded to the second connecting portion (12) at the joint (17).

2. The induction welding method according to claim 1, characterized in that, After the induction preheating, the first sensor (3) is deactivated or the joint (17) is removed from the working area of ​​the first sensor (3).

3. The induction welding method according to claim 1 or 2, characterized in that, After the induction preheating of the joint (17) using the first sensor (3) ends and the induction heating of the joint (17) to the welding temperature (T) begins, the process is complete. S There is a time interval of at least 0.1 seconds between them.

4. The induction welding method according to any one of claims 1 to 3, characterized in that, The preheating temperature (T) V ) and the welding temperature (T) S The difference between the initial temperature (T) and the initial temperature (T) A ) and the preheating temperature (T) V The ratio of the differences between them should be at least 1:1.

5.

5. The induction welding method according to any one of claims 1 to 4, characterized in that, The optical temperature sensor is a thermal imaging camera (14).

6. The induction welding method according to any one of claims 1 to 5, characterized in that, Induction heating is performed using a second sensor (4) that is different from the first sensor (3), and the first sensor (3) and the second sensor (4) are arranged at intervals from each other along the process path (5).

7. The induction welding method according to claim 6, characterized in that, The sensor device (13) is arranged between the first sensor (3) and the second sensor (4).

8. The induction welding method according to any one of claims 1 to 7, characterized in that, Before, during and / or after welding the first connecting portion (11) to the second connecting portion (12), the first connecting portion (11) and / or the second connecting portion (12) are cooled.

9. The induction welding method according to any one of claims 1 to 8, characterized in that, The welding temperature (T) is reached by induction heating through the first sensor (3) or the second sensor (4). S After that, the pressing element (20) presses the first connecting part (11) and the second connecting part (12) together.

10. The induction welding method according to any one of claims 1 to 9, characterized in that: - The initial temperature (T) A The temperature ranges from 10°C to 40°C; and - If the first connecting portion (11) and / or the second connecting portion (12) comprises a semi-crystalline thermoplastic material, then the preheating temperature (T) V The preheating temperature (T) is in the range of 90°C to 350°C, or if the first connecting portion (11) and / or the second connecting portion (12) comprises an amorphous thermoplastic material. V The temperature range is between 175°C and 320°C; and - If the first connecting portion (11) and / or the second connecting portion (12) comprises a semi-crystalline thermoplastic material, then the welding temperature (T) S The welding temperature is in the range of 140°C to 460°C, or if the first connecting portion (11) and / or the second connecting portion (12) comprises an amorphous thermoplastic material, the welding temperature is in the range of 250°C to 380°C.

11. The induction welding method according to any one of claims 1 to 10, characterized in that, The first connecting portion (11) and / or the second connecting portion (12) are designed as laminates (15).

12. The induction welding method according to claim 1, characterized in that, The connecting part is a fiber reinforced plastic (FRP) composite material connecting part.

13. The induction welding method according to claim 12, characterized in that, The connecting part is an FRP connecting part for the aircraft component (2).

14. The induction welding method according to claim 1, characterized in that, The process parameters are the settings parameters for the induction generator.

15. The induction welding method according to claim 4, characterized in that, The preheating temperature (T) V ) and the welding temperature (T) S The difference between the initial temperature (T) and the initial temperature (T) A ) and the preheating temperature (T) V The ratio of the differences between them is at least 1:

2.

16. The induction welding method according to claim 15, characterized in that, The preheating temperature (T) V ) and the welding temperature (T) S The difference between the initial temperature (T) and the initial temperature (T) A ) and the preheating temperature (T) V The ratio of the differences between them should be at least 1:2.

5.

17. The induction welding method according to claim 16, characterized in that, The preheating temperature (T) V ) and the welding temperature (T) S The difference between the initial temperature (T) and the initial temperature (T) A ) and the preheating temperature (T) V The ratio of the differences between them is at least 1:

3.

18. The induction welding method according to claim 16, characterized in that, The preheating temperature (T) V ) and the welding temperature (T) S The difference between the initial temperature (T) and the initial temperature (T) A ) and the preheating temperature (T) V The ratio of the differences between them should be at least 1:3.

5.

19. The induction welding method according to claim 18, characterized in that, The preheating temperature (T) V ) and the welding temperature (T) S The difference between the initial temperature (T) and the initial temperature (T) A ) and the preheating temperature (T) V The ratio of the differences between them is at least 1:

4.

20. The induction welding method according to claim 8, characterized in that, The first connecting portion (11) and / or the second connecting portion (12) are cooled by a fluid flow.

21. The induction welding method according to claim 20, characterized in that, The fluid flow is an airflow.

22. The induction welding method according to claim 9, characterized in that, The extrusion element (20) is an extrusion roller (21).

23. The induction welding method according to claim 11, characterized in that, The laminate (15) is arranged to be stacked vertically.

24. An apparatus (1) for induction welding of a joint, the apparatus comprising: A first sensor (3) is used to sense and heat the first connecting part (11) and / or the second connecting part (12). A sensor device (13) is configured to detect the temporal and / or spatial temperature distribution of the first connecting portion (11) and / or the second connecting portion (12), wherein the sensor device (13) is formed of an optical temperature sensor. The control unit (51) is configured to perform the following steps: - Feedforward control and / or feedback control are applied to the first sensor (3) so that the first sensor (3) moves the junction (17) of the first connecting portion (11) and the second connecting portion (12) from the initial temperature (T). A Preheat to below the specified welding temperature (T) S The preheating temperature (T) V ), wherein the preheating temperature (T) V ) and the welding temperature (T) S The difference between the two is less than the initial temperature (T). A ) and the preheating temperature (T) V The difference between ) - Determine at least one process parameter, which is to heat the preheated joint (17) to the welding temperature (T). S The required parameters, wherein the at least one process parameter is based on the time and / or spatial temperature distribution of the preheated first connection portion (11) and / or second connection portion (12) and the specified welding temperature (T). S The temperature distribution is determined by means of a sensor device (13); and - Feedforward control and / or feedback control are applied to the first sensor (3) to heat the joint (17) to the welding temperature (T) using the at least one process parameter. S This allows the first connecting portion (11) to be welded to the second connecting portion (12) at the joint (17), wherein the deviation of the material properties of the first connecting portion (11) and the second connecting portion (12) is compensated by utilizing the at least one process parameter.

25. The apparatus according to claim 24, characterized in that, A second sensor (4) is provided, and the sensor device (13) is arranged between the first sensor (3) and the second sensor (4).

26. The apparatus according to claim 24, characterized in that, The connecting part is a fiber reinforced plastic (FRP) composite material connecting part.

27. The apparatus according to claim 26, characterized in that, The connecting part is an FRP connecting part for the aircraft component (2).

28. The apparatus according to claim 24, characterized in that, The process parameters are the settings parameters for the induction generator.

29. An apparatus (1) for induction welding of a joint, the apparatus comprising: A first sensor (3) is used to sense and heat the first connecting part (11) and / or the second connecting part (12). A second sensor (4) that is different from the first sensor (3); A sensor device (13) is configured to detect the temporal and / or spatial temperature distribution of the first connecting portion (11) and / or the second connecting portion (12), wherein the sensor device (13) is formed of an optical temperature sensor. The control unit (51) is configured to perform the following steps: - Feedforward control and / or feedback control are applied to the first sensor (3) so that the first sensor (3) moves the junction (17) of the first connecting portion (11) and the second connecting portion (12) from the initial temperature (T). A Preheat to below the specified welding temperature (T) S The preheating temperature (T) V ), wherein the preheating temperature (T) V ) and the welding temperature (T) S The difference between the two is less than the initial temperature (T). A ) and the preheating temperature (T) V The difference between ) - Determine at least one process parameter, which is to heat the preheated joint (17) to the welding temperature (T). S The required parameters, wherein the at least one process parameter is based on the time and / or spatial temperature distribution of the preheated first connection portion (11) and / or second connection portion (12) and the specified welding temperature (T). S The temperature distribution is determined by means of a sensor device (13); and - Feedforward control and / or feedback control are applied to the first sensor (3) or the second sensor (4) to heat the joint (17) to the welding temperature (T) using the at least one process parameter. S This allows the first connecting portion (11) to be welded to the second connecting portion (12) at the joint (17), wherein the deviation of the material properties of the first connecting portion (11) and the second connecting portion (12) is compensated by utilizing the at least one process parameter.

30. The apparatus according to claim 29, characterized in that, The sensor device (13) is arranged between the first sensor (3) and the second sensor (4).

31. The apparatus according to claim 29, characterized in that, The connecting part is a fiber reinforced plastic (FRP) composite material connecting part.

32. The apparatus according to claim 31, characterized in that, The connecting part is an FRP connecting part for the aircraft component (2).

33. The apparatus according to claim 29, characterized in that, The process parameters are the settings parameters for the induction generator.

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