Radio frequency welding method and system for thermoplastic composites

Abstract

The application provides a radio frequency welding method and system of thermoplastic composite material, the radio frequency heating device includes a radio frequency generating module, a signal amplifier module and a radio frequency heating module, the radio frequency heating module includes a first electrode plate, a second electrode plate and a temperature sampling unit, the radio frequency generating module is used to determine the target frequency according to the current temperature, generate the first signal with the target frequency and send to the signal amplifier, the signal amplifier module is used to determine the target power according to the current temperature and the target temperature, adjust the first signal according to the target power, obtain the second signal, and send the second signal to the first electrode plate and the second electrode plate, the first electrode plate and the second electrode plate form an electromagnetic field based on the second signal, the frequency and power of the signal are adjusted in real time to uniformly and efficiently heat the heated part, so that the welding and / or shaping of the heated part are realized.

Description

Technical Field

[0001] This application relates to the field of materials heating technology, and more specifically, to a radio frequency welding method and system for thermoplastic composite materials. Background Technology

[0002] Composite materials, due to their advantages such as high specific strength, high specific stiffness, corrosion resistance, fatigue resistance, and customizable properties, have enormous application potential in high-precision fields such as aerospace and weaponry. Depending on the resin matrix, carbon fiber composites are divided into thermoplastic and thermosetting types. Thermoplastic composites, with their superior toughness and impact resistance, as well as their ability to be repeatedly processed, easily welded and repaired, and more environmentally friendly, have a wider range of applications.

[0003] Thermoplastic composites can be joined and deformed by heating and melting, with welding being the primary method of joining. Welding techniques include ultrasonic welding, resistance welding, and laser welding.

[0004] However, ultrasonic welding cannot weld thicker samples and has poor processing results. Resistance welding has a narrow process window and is not suitable for welding complex interfaces. Laser welding has high equipment costs and requires high laser absorption efficiency from both the solder and the sample. Summary of the Invention

[0005] The purpose of this application is to provide a radio frequency welding method and system for thermoplastic composite materials to address the shortcomings of the prior art, thereby solving the problems of poor processing effect and complex welding process in the prior art.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a radio frequency heating device, which includes a radio frequency generation module, a signal amplification module, and a radio frequency heating module. The radio frequency heating module includes a first electrode plate, a second electrode plate, and a temperature sampling unit.

[0008] One end of the radio frequency generation module is grounded, and the other end of the radio frequency generation module is connected to one end of the signal amplifier. The radio frequency generation module is also connected to the temperature sampling unit. The radio frequency generation module is used to determine the target frequency based on the current temperature sent by the temperature sampling unit, and generate a first signal with the target frequency and send it to the signal amplifier.

[0009] The other end of the signal amplification module is connected to the first electrode plate and the second electrode plate. The signal amplification module is also connected to the temperature sampling unit. The signal amplification module is used to determine the target power based on the current temperature sent by the temperature sampling unit and the target temperature of the heating element, and adjust the first signal according to the target power to obtain a second signal with the target power, and send the second signal to the first electrode plate and the second electrode plate.

[0010] The first electrode plate and the second electrode plate form an electromagnetic field based on the second signal. The electromagnetic field passes through the element to be heated in order to heat the element.

[0011] Optionally, the first electrode plate is disposed on one side of the first heating surface of the workpiece to be heated, and the second electrode plate is disposed on one side of the second heating surface of the workpiece to be heated.

[0012] Optionally, both the first electrode plate and the second electrode plate are disposed on one side of the target heating surface of the workpiece to be heated.

[0013] Optionally, the radio frequency heating module further includes: a third electrode plate and a fourth electrode plate;

[0014] The third and fourth electrode plates are used to connect to the signal amplification module to receive the signal sent by the signal amplification module and to heat the component to be heated.

[0015] Optionally, the radio frequency heating module further includes: a connection component;

[0016] The connecting component is fixedly connected to the first electrode plate and the second electrode plate;

[0017] The connection component is used to connect the robotic arm.

[0018] Optionally, the radio frequency generation module includes: a signal source unit, a reverse coupling unit, and an adaptive impedance matching unit, wherein the adaptive impedance matching unit includes: at least one capacitor and at least one inductor;

[0019] The signal source unit is connected to the reverse coupling unit, the reverse coupling unit is also connected to the adaptive impedance matching unit, and the adaptive impedance matching unit is also connected to the signal amplification module.

[0020] The signal source unit is used to generate the first signal based on the target frequency and output it to the reverse coupling unit;

[0021] The reverse coupling unit is used to receive the first signal and the standing wave signal reflected by the adaptive impedance matching unit, and based on the standing wave signal and a preset standing wave threshold, generate a control signal and send the control signal and the first signal to the adaptive impedance matching unit.

[0022] The adaptive impedance matching unit is used to adjust the capacitance value of the capacitor and the inductance value of the inductor based on the control signal, so that the standing wave value in the standing wave signal is less than a preset standing wave threshold, and sends the first signal to the signal amplification module.

[0023] Optionally, the process by which the radio frequency generation module determines the target frequency based on the current temperature sent by the temperature sampling unit includes:

[0024] The radio frequency generation module determines the target frequency of the component to be heated based on the current temperature and a pre-determined temperature-frequency mapping relationship.

[0025] Optionally, the process for determining the temperature-frequency mapping relationship is as follows:

[0026] Test the electromagnetic parameters of the heating element at multiple preset temperatures;

[0027] Based on the electromagnetic parameters of the heating element corresponding to each preset temperature, the signal absorption parameters corresponding to each preset temperature are determined. The signal absorption parameters are used to represent the signal absorption values ​​corresponding to different frequencies at the preset temperature.

[0028] The frequency corresponding to the highest signal absorption value among the preset temperatures is taken as the adjustment frequency corresponding to each preset temperature.

[0029] Secondly, this application provides a radio frequency heating system, which includes: a radio frequency heating device as described in the first aspect and a robotic arm.

[0030] Optionally, the radio frequency heating system further includes: a pressure roller device;

[0031] The robotic arm is also used to grip the pressure roller device and drive the pressure roller device to move along with the radio frequency heating device, so that the pressure roller device heats and / or compacts the workpiece to be heated after the radio frequency heating module heats the workpiece to be heated.

[0032] The beneficial effects of this application are as follows: In the radio frequency heating device, the radio frequency generation module generates a first signal with a target frequency based on the current temperature and sends it to the signal amplification module. The signal amplification module adjusts the frequency of the first signal based on the current temperature and the target temperature to obtain a second signal with the target frequency, and sends this signal to the first electrode plate and the second electrode plate, thereby using the generated electromagnetic field to heat the workpiece. By adjusting the frequency of the signal, the heating efficiency of the workpiece is automatically adjusted, and by adjusting the power of the signal, the temperature of the workpiece is adjusted in real time. By adjusting the heating efficiency and temperature of the workpiece, the progress of welding or shaping of the workpiece can be precisely controlled, and the heating process is simple. Furthermore, the electromagnetic field formed by the first and second electrode plates directly heats the workpiece. This heating method has strong penetration and uniform heating, and can handle thick workpieces, achieving efficient and uniform heating. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of a radio frequency heating device provided in an embodiment of this application;

[0035] Figure 2 This is a schematic diagram showing the arrangement position of an electrode plate according to an embodiment of this application;

[0036] Figure 3 This is a schematic diagram showing another electrode plate placement provided in an embodiment of this application;

[0037] Figure 4 This is a schematic diagram of an electrode plate arrangement provided in an embodiment of this application;

[0038] Figure 5 This is a schematic diagram of another electrode plate arrangement provided in an embodiment of this application;

[0039] Figure 6 This is a schematic diagram of another radio frequency heating module provided in an embodiment of this application;

[0040] Figure 7 This is a schematic diagram of another radio frequency heating module provided in an embodiment of this application;

[0041] Figure 8 This is a schematic diagram of the structure of a radio frequency generation module provided in an embodiment of this application;

[0042] Figure 9 This is a schematic flowchart of an adaptive impedance matching method provided in an embodiment of this application;

[0043] Figure 10 This is a schematic diagram of the structure of an adaptive impedance matching unit provided in an embodiment of this application;

[0044] Figure 11 This is a schematic diagram of a process for determining a temperature-frequency mapping relationship provided in an embodiment of this application;

[0045] Figure 12 This is a schematic diagram of the structure of a radio frequency heating system provided in an embodiment of this application;

[0046] Figure 13 This is a schematic diagram illustrating the effect of radio frequency heating provided in an embodiment of this application. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the accompanying drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0048] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0049] It should be noted that the term "comprising" will be used in the embodiments of this application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0050] Thermoplastic composites undergo secondary processing and bonding through heating and melting. Bonding can be achieved through welding, while secondary processing can involve deformation.

[0051] Specifically, welding techniques include ultrasonic welding, resistance welding, and laser welding. However, ultrasonic welding cannot weld thicker samples and has poor processing results; resistance welding has a narrow process window and is not suitable for welding complex interfaces; and laser welding has high equipment costs and requires high laser absorption efficiency from both the solder and the sample.

[0052] During processing, thermoplastic composites may experience structural warping due to the shrinkage of the resin matrix during crystallization and uneven temperature distribution. Existing methods for restoring deformed materials typically involve placing the material in an oven, hot molding press, or vacuum autoclave, providing a high-temperature environment, and then slowly cooling it to the material's glass transition temperature, thus heat-treating the material under high temperature and pressure. However, this method is time-consuming, has high equipment costs, and is difficult to operate, limiting the widespread adoption of warping techniques.

[0053] Based on this, this application proposes a radio frequency (RF) heating device, which includes an RF generation module, a signal amplification module, and an RF heating module. The RF generation module and the signal amplification module output signals to the first and second electrode plates of the RF heating module according to the target frequency and target power, so as to form an electromagnetic field between the two electrode plates. The electromagnetic field passes through the workpiece to be heated, thereby heating the workpiece and realizing the welding of the workpiece. In addition, the heating of the workpiece to be heated also achieves the shaping of the workpiece. With this RF heating method, on the one hand, the long wavelength of RF heating gives it an ideal penetration effect, avoiding uneven heating phenomena such as surface overheating. On the other hand, for materials with different dielectric constants and loss factors, the RF generation module and the signal amplification module can adjust the signal frequency and power, thereby achieving the optimal heating effect for the workpiece to be heated, realizing efficient and uniform heating. In addition, this efficient and uniform heating method also achieves the shaping of the workpiece to be heated.

[0054] Compared to existing induction heating technologies, the above method can meet the heating requirements of thick workpieces. Induction heating is an indirect heating method that uses a high-frequency alternating current passing through an induction coil to create an alternating magnetic field around the coil. When the workpiece is placed in this magnetic field, an induced current is generated on its surface, thus achieving heating. However, this heating method concentrates heat on the surface layer of the material, making it impossible to uniformly heat thick workpieces.

[0055] Next, refer to Figure 1 The structure of the radio frequency heating device is described. For example... Figure 1 As shown, the radio frequency heating device includes a radio frequency generation module, a signal amplification module, and a radio frequency heating module. The radio frequency heating module includes a first electrode plate, a second electrode plate, and a temperature sampling unit.

[0056] Optionally, the radio frequency generation module is the signal source of the radio frequency heating device, used to generate a first signal and send the generated first signal to the signal amplifier through the other end, thereby providing a radio frequency field for heating the first electrode plate and the second electrode plate to the workpiece to be heated.

[0057] The component to be heated can be either a welding object or a shaping object. Its material can be a thermoplastic composite material, such as a polyetheretherketone (PEEK) film material with carbon nanotubes, which possesses suitable dielectric properties and can absorb electromagnetic field energy and convert it into heat energy. In a welding scenario, the component to be heated can include multiple components to be welded together by heating. It is worth noting that the component to be heated is not limited to thermoplastic materials; it can also be a semiconductor material or a metal material, etc., and this application does not impose any limitations on this.

[0058] Optionally, the signal amplification module is used to amplify or reduce the power of the first signal sent by the radio frequency generation module based on the current temperature to obtain a second signal, and send the second signal to the first electrode plate and the second electrode plate to heat the workpiece to be heated.

[0059] Optionally, the first and second electrode plates can be, for example, copper plates, and their size, thickness, and spacing can be adjusted according to actual needs. Furthermore, the first and second electrode plates can be disassembled and replaced as needed.

[0060] Optionally, the temperature sampling unit can be an infrared temperature probe, which can be installed above the part to be heated to detect the current temperature of the part to be heated and feed it back to the radio frequency generation module and the signal amplification module.

[0061] Optionally, the temperature sampling unit can feed back the current temperature to the radio frequency generation module and the signal amplification module via wired or wireless means.

[0062] Optionally, one end of the RF generation module is grounded, and the other end of the RF generation module is connected to one end of the signal amplifier. The RF generation module is also connected to the temperature sampling unit. The RF generation module is used to determine the target frequency based on the current temperature sent by the temperature sampling unit and generate a first signal with the target frequency, which is then sent to the signal amplifier.

[0063] As an optional implementation, the process of determining the target frequency can be as follows: based on a preset curve and the current temperature sent by the temperature sampling unit, the target frequency is determined. The preset curve is a curve showing the relationship between temperature and frequency.

[0064] As an alternative implementation, the process of determining the target frequency can also be as follows: First, calculate the signal absorption value corresponding to each temperature based on multiple temperatures and their corresponding electromagnetic parameters, and then determine the mapping relationship between temperature and frequency based on the signal absorption value. Then, based on the current temperature sent by the temperature sampling unit and the mapping relationship between temperature and frequency, determine the frequency corresponding to the current temperature in the temperature-frequency mapping relationship, and use this frequency as the target frequency.

[0065] Optionally, a higher frequency of the first signal allows for a greater temperature adjustment rate of the component to be heated. Conversely, a lower frequency of the first signal allows for a smaller temperature adjustment rate of the component to be heated.

[0066] Optionally, the other end of the signal amplification module is connected to the first electrode plate and the second electrode plate. The signal amplification module is also connected to the temperature sampling unit. The signal amplification module is used to determine the target power based on the current temperature sent by the temperature sampling unit and the target temperature of the element to be heated, and adjust the first signal according to the target power to obtain a second signal with the target power, and send the second signal to the first electrode plate and the second electrode plate.

[0067] Because the amplitude of the first signal is low, for example, a voltage peak-to-peak value of 5 volts, in order to ensure that the heating element is heated at the target temperature, the signal amplification module receives the first signal and amplifies its amplitude, that is, increases its power, so that the current temperature of the heating element approaches the target temperature.

[0068] The target temperature can be the pre-measured optimal temperature at which the workpiece to be heated can be welded or shaped.

[0069] Optionally, the signal amplification module has a power adjustment range, for example, 1-500 watts, and a power amplification range of 0-69 dB-mW.

[0070] As an optional implementation, the signal amplification module can adjust the signal power based on an embedded negative feedback model. Specifically, it receives the current temperature sent by the temperature sampling unit and performs real-time negative feedback adjustment based on the current temperature and the target temperature, outputting the target power. This ensures that after the first and second electrode plates receive a second signal with the target power, they heat the element to be heated, making the current temperature of the element approach or equal to the target temperature.

[0071] Optionally, the first electrode plate and the second electrode plate form an electromagnetic field based on the second signal, and the electromagnetic field passes through the workpiece to be heated in order to heat the workpiece.

[0072] Optionally, the first and second electrode plates can heat the workpiece based on the generated electromagnetic field. Specifically, when the second signal is transmitted to the first and second electrode plates, a strong magnetic field is generated around the plates. The energy of this magnetic field is concentrated in the area of ​​the workpiece to be heated, thereby generating sufficient heat to continuously raise the temperature of the workpiece. When the workpiece reaches the target temperature, it softens, thus enabling welding or shaping operations to be performed.

[0073] It is worth noting that when an electromagnetic field passes through the component to be heated, it causes rapid vibration and friction of the polar molecules inside the component, thereby achieving directional radio frequency heating through the selection of different materials. If the first electrode plate and the second electrode plate are arranged on the same plane, the power of the second signal may be too low, which may prevent the electromagnetic field from passing through the component to be heated, thus preventing the component from being heated.

[0074] Optionally, during the initial heating of the component to be heated, the component can be heated based on a preset frequency and a preset power. During the heating process, the target frequency and target power can be adjusted in real time based on the current temperature.

[0075] In this embodiment, the radio frequency (RF) heating device uses an RF generation module to generate a first signal at a target frequency based on the current temperature and sends it to a signal amplification module. The signal amplification module adjusts the frequency of the first signal based on the current and target temperatures to obtain a second signal with the target frequency, and sends this signal to the first and second electrode plates. This generates an electromagnetic field to heat the workpiece. By adjusting the signal frequency, the heating efficiency of the workpiece is automatically adjusted, and by adjusting the signal power, the temperature of the workpiece is adjusted in real time. By adjusting the heating efficiency and temperature of the workpiece, the progress of welding or shaping can be precisely controlled, and the heating process is simple. Furthermore, the electromagnetic field formed by the first and second electrode plates directly heats the workpiece. This heating method has strong penetration and uniform heating, and can handle thick workpieces, achieving efficient and uniform heating.

[0076] In radio frequency heating devices, the heating method may differ depending on the placement of the electrode plates. Next, refer to... Figure 2 The first possible placement of the electrode plate is described. Figure 2 This is a schematic diagram of the electrode plate's mounting position provided in an embodiment of this application.

[0077] Optionally, the first electrode plate is disposed on one side of the first heating surface of the workpiece to be heated, and the second electrode plate is disposed on one side of the second heating surface of the workpiece to be heated.

[0078] Optionally, if the distance between the first electrode plate and the workpiece to be heated is a first distance, and the distance between the second electrode plate and the workpiece to be heated is a second distance, then the first distance can be equal to the second distance. As an optional implementation, the second distance can also be 0, in which case the second electrode plate provides support for the workpiece to be heated.

[0079] Optionally, the first heating surface and the second heating surface can be opposite surfaces of the workpiece to be heated. In this case, the first electrode plate and the second electrode plate are arranged parallel to each other on both sides of the workpiece to be heated, so that the two electrode plates can serve as positive and negative poles and form parallel magnetic field lines that penetrate the workpiece to be heated, thereby uniformly heating the workpiece.

[0080] It is worth noting that the first heating surface and the second heating surface may not be opposite to the workpiece to be heated, but rather adjacent to each other. In this case, the magnetic field lines formed by the electromagnetic field are arc-shaped and penetrate through the workpiece to be heated, so the workpiece can still be heated uniformly.

[0081] In this embodiment, by placing the first electrode plate and the second electrode plate on the first heating surface side and the second heating surface side of the workpiece to be heated, the workpiece to be heated is heated uniformly.

[0082] Optionally, the electrode plate setting position in this embodiment can be used for welding heating elements. Since this method can heat the elements to be heated evenly, the elements to be heated can be welded together evenly.

[0083] Next, refer to Figure 3 The second possible placement of the electrode plates is described below. Figure 3 This is a schematic diagram showing another electrode plate placement provided in an embodiment of this application.

[0084] Optionally, both the first electrode plate and the second electrode plate are disposed on one side of the target heating surface of the workpiece to be heated.

[0085] The target heating surface of the part to be heated is one of the heating surfaces of the part to be heated.

[0086] Optionally, the first electrode plate and the second electrode plate can be arranged on the same plane, so as to concentrate the heating of a local area of ​​the element to be heated.

[0087] Optionally, the electrode plate setting position in this embodiment can be used to correct the shape of the heating element. Since this method can locally heat the heating element, the local area of ​​the heating element can be heated and corrected.

[0088] It is worth noting that the closer the first and second electrode plates are to the target heating surface of the workpiece, the higher the heating efficiency.

[0089] In this embodiment, the first electrode plate and the second electrode plate are disposed on one side of the target heating surface of the workpiece to be heated, thereby locally heating the workpiece and effectively suppressing the warping deformation problem of the workpiece to be heated.

[0090] Next, two parallel heating methods are provided based on the two electrode plate structures. One of these methods can be selected to perform the heating operation according to actual needs.

[0091] As an optional implementation, the radio frequency heating module includes only two electrode plates: a first electrode plate and a second electrode plate. The relative positions of the first electrode plate and the second electrode plate can be as follows: Figure 2 or Figure 3 The settings are configured as shown. If the part to be heated is larger or longer than the electrode plate, the radio frequency heating module can be moved to heat the next part after the first and second electrode plates have been used to heat one area, until all areas of the parts to be heated have been heated.

[0092] Based on this heating method, there are two other parallel electrode plate configurations for heating. One configuration involves the first and second electrode plates being the same size; when heating the next area to be heated, both the first and second electrode plates are moved simultaneously. The second configuration... Figure 4 As shown, Figure 4 This is a schematic diagram illustrating the arrangement of an electrode plate according to an embodiment of this application. Figure 4 As shown, the first electrode plate and the second electrode plate are different in size, with the second electrode plate being larger than the first electrode plate. When heating the next area to be heated, only the first electrode plate is moved, thereby heating the area covered by the first electrode plate.

[0093] As another alternative implementation method, such as Figure 5 As shown, the radio frequency heating module also includes a third electrode plate and a fourth electrode plate. Among them, Figure 5 This is a schematic diagram of another electrode plate arrangement provided in an embodiment of this application.

[0094] The third and fourth electrode plates are used to connect to the signal amplification module to receive signals sent by the signal amplification module and to heat the component to be heated.

[0095] Optionally, the first and second electrode plates can be used as one heating group, and the third and fourth electrode plates can be used as another heating group. Multiple heating groups are connected in parallel to the signal amplification module and receive signals sent by the signal amplification module, thereby heating multiple areas of the workpiece to be heated simultaneously.

[0096] In this design, the first, second, third, and fourth electrode plates are all smaller than the heating surface of the workpiece. This allows for localized heating and welding or deformation of specific areas of the workpiece, reducing energy consumption compared to using a larger pair of electrode plates.

[0097] Based on this, by moving each heating group to simultaneously and sequentially heat multiple areas to be heated, welding and shaping actions can be performed on the parts to be heated efficiently.

[0098] It is worth noting that this embodiment is illustrated by taking the radio frequency heating module as an example, which also includes a third electrode plate and a fourth electrode plate. In actual use, multiple sets of electrode plates can be added to heat multiple areas to be heated at the same time, thereby improving the efficiency of the heating process.

[0099] Next, refer to Figure 6 The specific structure of the radio frequency heating module will continue to be described. For example... Figure 6 As shown, the radio frequency heating module also includes a connection component. Among them, Figure 6 This is a schematic diagram of another radio frequency heating module provided in an embodiment of this application.

[0100] Optionally, the connecting component is fixedly connected to the first electrode plate and the second electrode plate.

[0101] Optionally, the connecting component is used to connect the robotic arm.

[0102] The connecting component can be an adapter flange, and the robotic arm can be the end effector of a 6-axis industrial robot or the end effector of a gantry frame.

[0103] Optionally, the connecting component can also be fixedly connected to the temperature acquisition unit so that the temperature acquisition unit can be moved while the first electrode plate and the second electrode plate are moved.

[0104] Optionally, the connecting component is fixedly connected to the first electrode plate and the second electrode plate, thereby moving the first electrode plate and the second electrode plate based on the drive of the robotic arm, thereby moving and heating the workpiece to be heated.

[0105] The robotic arm can drive the connecting components to move based on the current heating progress.

[0106] As an optional implementation method, continue to refer to Figure 6 The radio frequency heating module may also include multiple heat dissipation components. Each heat dissipation component has one side in close contact with the side of the electrode plate furthest from the part to be heated. Figure 6 The positions of the first and second electrode plates shown are as follows: Figure 2As shown in the diagram, one heat dissipation component is attached to the side of the first electrode plate away from the element to be heated, and the other heat dissipation component is attached to the side of the second electrode plate away from the element to be heated.

[0107] The heat dissipation component can be a ceramic heat sink, made of highly thermally conductive ceramic, and can have built-in water cooling pipes to prevent the radio frequency heating module from overheating.

[0108] As another alternative implementation method, Figure 7 This is a schematic diagram of another radio frequency heating module provided in an embodiment of this application, including a front view and a left view. Figure 7 As shown, the radio frequency heating module may also include a heat dissipation component, a laser positioner, a protective shell, and rubber. Figure 7 The positions of the first and second electrode plates shown are as follows: Figure 3 The setting location is shown in the figure.

[0109] The heat dissipation component can be disposed on the side of the first electrode plate and the second electrode plate away from the object to be heated. The first electrode plate and the second electrode plate can be disposed on the support component, which is located between the first electrode plate, the second electrode plate and the target heating surface of the object to be heated, and its material can be a polyimide plate.

[0110] The laser positioner can be set on both sides of the first electrode plate and the second electrode plate to determine the current moving position of the radio frequency heating module and send the current position to the robotic arm control module so that the robotic arm control module can control the robotic arm based on the current position and the target position, thereby driving the radio frequency heating module to move and heat.

[0111] The protective shell, made of metal such as copper, surrounds the electrode plates and heat dissipation components, and is connected to a compressible rubber of the same thickness. The side of the rubber away from the protective shell is used to press and secure the component to be heated. The protective shell and rubber enclose multiple electrode plates in a sealed space, preventing electromagnetic wave leakage, reducing the impact on the surrounding environment and equipment, minimizing energy loss, and ensuring the safety of personnel and equipment.

[0112] In this embodiment, the connecting component is connected to the robotic arm and fixedly connected to the first electrode plate and the second electrode plate, thereby driving the first electrode plate and the second electrode plate to move and heat the workpiece based on the drive of the robotic arm.

[0113] Next, refer to Figure 8 The structure of the RF generation module is described below. The RF generation module includes: a signal source unit, a reverse coupling unit, and an adaptive impedance matching unit. The adaptive impedance matching unit includes at least one capacitor and at least one inductor. Figure 8 This is a schematic diagram of the structure of a radio frequency generation module provided in an embodiment of this application.

[0114] Optionally, the signal source unit is connected to the reverse coupling unit, the reverse coupling unit is also connected to the adaptive impedance matching unit, and the adaptive impedance matching unit is also connected to the signal amplification module.

[0115] Optionally, the signal source unit is used to generate a first signal based on the target frequency and output it to the reverse coupling unit.

[0116] Specifically, the signal source unit can determine the target frequency based on the current temperature and generate a first signal based on the target frequency to output to the reverse coupling unit.

[0117] Optionally, the reverse coupling unit receives the first signal and the standing wave signal reflected by the adaptive impedance matching unit, and generates a control signal based on the standing wave signal and a preset standing wave threshold, and sends the control signal and the first signal to the adaptive impedance matching unit. Optionally, the adaptive impedance matching unit adjusts the capacitance value of the capacitor and the inductance value of the inductor based on the control signal, so that the standing wave value in the standing wave signal is less than the preset standing wave threshold, and sends the first signal to the signal amplification module.

[0118] Optionally, changes in the dielectric properties of the element to be heated with increasing temperature, as well as changes in the size and position of the electrode plates, may lead to instability in the load impedance formed by the first and second electrode plates. To ensure efficient operation of the RF heating module, negative feedback adjustment is used to match the source impedance and load impedance. The source impedance can be the impedance in the RF generation module, signal amplification module, or transmission lines.

[0119] For example, the impedance of the RF generation module, signal amplification module, and transmission line can be reduced in advance to avoid signal loss. For example, the impedance of the RF generation module, signal amplification module, and transmission line can be set to 50 ohms.

[0120] Specifically, the reverse coupling unit is responsible for receiving two parts of the signal: one part is the first signal, which is the signal output by the signal source unit, and the other part is the standing wave signal reflected back by the adaptive impedance matching unit. The standing wave signal is generated because when the load impedance and the source impedance are mismatched, part of the signal will be reflected back.

[0121] Optionally, the reverse coupling unit can compare and judge based on the received standing wave signal and a preset standing wave threshold. If the standing wave value in the standing wave signal exceeds the preset standing wave threshold, it indicates that the impedance mismatch is already significant and needs to be adjusted. Therefore, the reverse coupling unit can generate a corresponding control signal based on this comparison result to guide subsequent impedance adjustment operations. Additionally, the reverse coupling unit can also determine the standing wave ratio, standing wave phase, and signal reflection ratio based on the standing wave signal. The standing wave threshold can be, for example, 5.

[0122] Optionally, after receiving a control signal, the adaptive impedance matching unit can adjust the capacitance and inductance values ​​of its internal capacitors and inductors according to the instructions contained in the signal. This adjustment is the core impedance matching regulation method, which changes the impedance characteristics of the entire matching unit by altering the parameters of the capacitors and inductors. For example, increasing the capacitance value may affect the capacitive reactance, and decreasing the inductance value may affect the inductive reactance, thereby changing the input impedance of the matching unit. The purpose of adjusting the capacitance and inductance values ​​is to make the standing wave (SWR) value in the standing wave signal less than a preset SWR threshold. The SWR value is an important indicator of the degree of impedance matching; the smaller the SWR value, the better the impedance matching. When the SWR value is below the threshold, it means that the source impedance and load impedance have reached a good matching state, and the energy transfer efficiency is high. After completing the impedance adjustment and improving the impedance matching, the adaptive impedance matching unit sends the first signal to the signal amplification module. In this way, the impedance-matched signal can be amplified more effectively, thereby improving the performance and efficiency of the entire heating system.

[0123] For example, the source impedance is adjusted by using a reverse coupling unit and an adaptive impedance matching unit so that the final standing wave ratio is below 1.2.

[0124] Optionally, Figure 9 This is a schematic flowchart of an adaptive impedance matching method provided in an embodiment of this application. Figure 9 As shown, the reverse coupling unit executes S901, which is to receive the first signal in real time, and executes S902, which is to determine the standing wave size based on the standing wave signal and the preset standing wave threshold, and executes S903, which is to generate a control signal according to the standing wave size, so that the adaptive impedance matching unit executes S904, which performs impedance matching based on the control signal, that is, adjusts the capacitance value of the capacitor and the inductance value of the inductor to adjust the standing wave, and executes S905, which sends the signal to the load through the signal amplification module, and executes S906 in real time, which is to detect the standing wave signal, and continues to execute S902 and subsequent steps.

[0125] As an example, the circuit of the adaptive impedance matching unit can be a π-type circuit, such as... Figure 10 As shown. Among them, Figure 10This is a schematic diagram of the structure of an adaptive impedance matching unit provided in an embodiment of this application. Figure 10 As shown, the adaptive impedance matching unit includes a first capacitor C1, a second capacitor C2, and a first inductor L1.

[0126] The first terminal of the first capacitor C1 is connected to both the reverse coupling unit and one terminal of the first inductor L1, while the other terminal of the first capacitor C1 is grounded. The other terminal of the first inductor L1 is connected to both the signal amplification module and one terminal of the second capacitor C2. The other terminal of the second capacitor C2 is grounded. Optionally, the capacitance value can be adjusted by adjusting the substrate spacing and substrate area. As a parallel solution, a varactor diode is also used instead of the first capacitor C1 and the second capacitor C2, and the capacitance value is adjusted by adjusting the bias voltage of the varactor diode. The magnetic core in the first inductor L1 is adjustable, and the inductance value is adjusted by adjusting the position of the magnetic core.

[0127] In this embodiment, the reverse coupling unit outputs a control signal based on the standing wave signal and the preset standing wave threshold, so that the adaptive impedance matching unit adjusts the capacitance value of the capacitor and the inductance value of the inductor based on the control signal, so that the standing wave value in the standing wave signal is less than the preset standing wave threshold, thereby realizing the control of the load impedance, balancing the source impedance and the load impedance, improving the heating efficiency, and avoiding damage to the device caused by reflected standing waves.

[0128] Next, we will introduce the process by which the radio frequency generation module determines the target frequency based on the current temperature sent by the temperature sampling unit.

[0129] Optionally, the radio frequency generation module determines the target frequency of the component to be heated based on the current temperature and a pre-determined temperature-frequency mapping relationship.

[0130] Optionally, determining the target frequency corresponding to the current temperature in real time and heating according to the target frequency can maximize the signal absorption rate of the component to be heated at the current temperature, thereby improving the heating efficiency of the component to be heated.

[0131] Among them, the temperature-frequency mapping relationship is used to characterize the mapping relationship between temperature and the frequency with the highest signal absorption rate.

[0132] Optionally, the radio frequency generation module can determine a target frequency within a preset frequency range and generate a first signal. For example, the preset frequency range may be 1-200 MHz.

[0133] In this embodiment, the target frequency of the component to be heated is determined based on the current temperature and a predetermined temperature-frequency mapping relationship, thereby improving the heating efficiency at the current temperature.

[0134] Furthermore, the following refers to Figure 11The process of determining the temperature-frequency mapping relationship is introduced. Among other things, Figure 11 This is a schematic diagram of a process for determining a temperature-frequency mapping relationship provided in an embodiment of this application.

[0135] S1101. Test the electromagnetic parameters of the heating element corresponding to multiple preset temperatures.

[0136] Specifically, a vector network analysis device can be used to test the electromagnetic parameters of the component to be heated at multiple preset temperatures, thereby establishing a model relating the electromagnetic parameters to temperature. For example, linear models, polynomial models, or exponential models can be used to fit the data.

[0137] It should be understood that the electromagnetic parameters of a component to be heated may differ at different temperatures. These electromagnetic parameters typically include dielectric constant, permeability, and conductivity, which determine the behavior of the component in an electromagnetic field. Temperature changes can cause alterations in the crystal structure of the component. For example, as the temperature increases, the thermal motion of atoms or molecules intensifies, increasing the amplitude of lattice vibrations, which may lead to lattice expansion or contraction, thus affecting the material's electromagnetic parameters.

[0138] S1102. Based on the electromagnetic parameters of the component to be heated corresponding to each preset temperature, determine the signal absorption parameters corresponding to each preset temperature. The signal absorption parameters are used to represent the signal absorption values ​​corresponding to different frequencies at the preset temperature.

[0139] Specifically, the electromagnetic parameters of the component to be heated determine its ability to absorb electromagnetic signals, i.e., the signal absorption parameters.

[0140] Specifically, the electromagnetic parameters at different temperatures are substituted into the absorption coefficient formula to calculate the signal absorption parameters corresponding to each temperature.

[0141] S1103. The frequency corresponding to the highest signal absorption value among the preset temperatures is taken as the adjustment frequency corresponding to each preset temperature.

[0142] For example, if at 300 degrees Celsius, the signal absorption coefficient represents a signal absorption value of 1 for 120 MHz, 2 for 130 MHz, 2.5 for 140 MHz, and 1.5 for 150 MHz, then 140 MHz is taken as the adjustment frequency corresponding to 300 degrees Celsius.

[0143] Optionally, after determining each preset temperature and its corresponding adjustment frequency, the resulting correspondence is used as a temperature-frequency mapping relationship.

[0144] In this embodiment, the electromagnetic parameters of the heating element corresponding to multiple preset temperatures are tested in advance to determine the signal absorption parameters corresponding to each preset temperature. The frequency corresponding to the highest signal absorption value is taken as the adjustment frequency corresponding to the preset temperature, thereby determining the temperature-frequency mapping relationship. Then, the frequency of the signal is adjusted according to the temperature-frequency mapping relationship so that the signal absorption efficiency of the heating element is optimal at the current temperature.

[0145] This application also provides a radio frequency heating system, which includes the above-mentioned radio frequency heating device and a robotic arm.

[0146] Specifically, the robotic arm and the radio frequency heating device can be mechanically connected through a connecting component. By driving the radio frequency heating device to move, the radio frequency heating module can move and heat the workpiece.

[0147] As an optional implementation method, refer to Figure 12 The radio frequency heating system also includes a pressure roller device. Among them, Figure 12 This is a schematic diagram of the structure of a radio frequency heating system provided in an embodiment of this application.

[0148] Optionally, the robotic arm is also used to grip the pressure roller device and drive the pressure roller device to move along with the radio frequency heating device, so that the pressure roller device heats and / or compacts the workpiece to be heated after the radio frequency heating module heats the workpiece to be heated.

[0149] Optionally, the pressure roller device may include a control component, which can control the pressure roller device to heat the workpiece and drive a robotic arm to control the movement of the pressure roller device. Specifically, the control component may include a heating unit, a moving unit, and a pressure unit.

[0150] The heating unit controls the built-in heating assembly of the pressure roller device. The heating assembly can be a resistance wire, which, for example, can be heated to 30-300 degrees Celsius. The heating unit controls the heating assembly based on the current temperature, so that heating continues simultaneously with the pressure roller device pressing the workpiece after the radio frequency heating module has finished heating it. The purpose of this heating is to ensure that the workpiece cools down slowly after heating, preventing welding or shaping failure due to a sudden temperature drop. For example, the radio frequency heating module can heat the workpiece to 300 degrees Celsius, and the pressure roller device can continue heating the workpiece at 200 degrees Celsius to avoid a sudden temperature drop.

[0151] The moving unit is used to control the movement position of the pressure roller. Specifically, it can drive a robotic arm according to target coordinates to control the displacement of the pressure roller assembly.

[0152] The pressure unit is used to control the pressure of the rollers pressing the workpiece to be heated. Specifically, the target coordinates of the roller assembly can be determined based on the target pressure, and then the robotic arm can be driven according to the target coordinates to control the displacement of the roller assembly.

[0153] Optionally, the pressure roller module can heat the workpiece and apply pressure. In a welding scenario, this allows multiple workpieces to be welded tightly, eliminating porosity. The welding process is as follows: When the second signal propagates to the first and second electrode plates, an electromagnetic field is formed between them. The electromagnetic field energy is concentrated in the area to be welded, generating a large amount of heat that gradually raises the temperature of the area to be welded. When the workpiece reaches the target temperature, it softens and begins to flow and cross-link. After a preset time following the arrival of the target temperature, heating is complete. The pressure roller module then applies pressure to the workpiece, for example, by applying a pressure of 1 MPa, causing the individual workpieces to be welded together.

[0154] In the shaping scenario, when the workpiece to be heated reaches the target temperature, it softens. After a preset time following the arrival of the target temperature, heating is complete. The pressure roller module then presses the workpiece to release residual stress during the crystallization process, thereby controlling warpage deformation.

[0155] Figure 13 This is a schematic diagram illustrating the effect of radio frequency heating provided in an embodiment of this application. For example... Figure 13 As shown, the first electrode plate and the second electrode plate heat a local area of ​​the workpiece to be heated, so that the temperature of the local area increases, thereby achieving welding or shaping.

[0156] This application also provides a radio frequency (RF) welding method for thermoplastic composite materials. The method is applied to an RF heating device, which includes an RF generation module, a signal amplification module, and an RF heating module. The RF heating module includes a first electrode plate, a second electrode plate, a workpiece to be heated, and a temperature sampling unit. The method specifically includes: the RF generation module generating an initial signal and sending the initial signal to the signal amplification module; the signal amplification module sending the initial signal to the first electrode plate and the second electrode plate to heat the workpiece; the temperature sampling unit sending the current temperature of the workpiece to be heated sampled to the signal amplification module and the RF generation module; the RF generation module generating a first signal with a target power based on the current temperature and the current frequency of the initial signal, and sending the first signal to the signal amplifier; the signal amplifier determining the target power based on the current temperature and the target temperature, adjusting the first signal according to the target power to obtain a second signal with the target power, and sending the second signal to the first electrode plate and the second electrode plate; the first electrode plate and the second electrode plate forming an electromagnetic field based on the second signal; the electromagnetic field passing through the workpiece to be heated to heat the workpiece.

[0157] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A radio frequency heating apparatus, characterized by, The radio frequency heating device comprises a radio frequency generating module, a signal amplification module and a radio frequency heating module, the radio frequency heating module comprises a first electrode plate, a second electrode plate and a temperature sampling unit; One end of the radio frequency generating module is grounded, the other end of the radio frequency generating module is connected with one end of the signal amplifier, the radio frequency generating module is also connected with the temperature sampling unit, and the radio frequency generating module is used for determining a target frequency according to the current temperature sent by the temperature sampling unit, and generating a first signal with the target frequency and sending the first signal to the signal amplifier; The other end of the signal amplification module is connected with the first electrode plate and the second electrode plate, and the signal amplification module is also connected with the temperature sampling unit; the signal amplification module is used for determining a target power according to the current temperature sent by the temperature sampling unit and the target temperature of the to-be-heated part, adjusting the first signal according to the target power to obtain a second signal with the target power, and sending the second signal to the first electrode plate and the second electrode plate; The first electrode plate and the second electrode plate form an electromagnetic field based on the second signal, and the electromagnetic field passes through the to-be-heated part to heat the to-be-heated part; The radio frequency generating module comprises a signal source unit, a reverse coupling unit and an adaptive impedance matching unit, the adaptive impedance matching unit comprises at least one capacitor and at least one inductor; The signal source unit is connected with the reverse coupling unit, the reverse coupling unit is also connected with the adaptive impedance matching unit, and the adaptive impedance matching unit is also connected with the signal amplification module; The signal source unit is used for generating the first signal based on the target frequency and outputting the first signal to the reverse coupling unit; The reverse coupling unit is used for receiving the first signal and a standing wave signal reflected by the adaptive impedance matching unit, generating a control signal based on the standing wave signal and a preset standing wave threshold, and sending the control signal and the first signal to the adaptive impedance matching unit; The adaptive impedance matching unit is used for adjusting the capacitance value of the capacitor and the inductance value of the inductor based on the control signal, so that the standing wave value in the standing wave signal is less than the preset standing wave threshold, and the first signal is sent to the signal amplification module.

2. The radio frequency heating apparatus of claim 1, wherein The first electrode plate is arranged on one side of a first heating surface of the to-be-heated part, and the second electrode plate is arranged on one side of a second heating surface of the to-be-heated part.

3. The radio frequency heating apparatus of claim 1, wherein, The first electrode plate and the second electrode plate are arranged on one side of a target heating surface of the to-be-heated part.

4. The radio frequency heating apparatus of claim 1, wherein The radio frequency heating module further comprises a third electrode plate and a fourth electrode plate; The third electrode plate and the fourth electrode plate are used for connecting the signal amplification module to receive the signal sent by the signal amplification module and heat the to-be-heated part.

5. The radio frequency heating apparatus as defined in claim 1, wherein, The radio frequency heating module further comprises a connecting assembly; The connecting assembly is fixedly connected with the first electrode plate and the second electrode plate; The connecting assembly is used for connecting a mechanical arm.

6. The radio frequency heating apparatus as defined in claim 1, wherein, The process that the radio frequency generating module determines the target frequency according to the current temperature sent by the temperature sampling unit comprises: The radio frequency generating module determines a target frequency of the to-be-heated object according to the current temperature and a predetermined temperature-frequency mapping relationship.

7. The radio frequency heating apparatus of claim 6, wherein, The determination process of the temperature-frequency mapping relationship is as follows: Test electromagnetic parameters of the to-be-heated object corresponding to multiple preset temperatures. Determine signal absorption parameters corresponding to each preset temperature according to the electromagnetic parameters of the to-be-heated object corresponding to each preset temperature, the signal absorption parameters being used to represent signal absorption values corresponding to different frequencies at a preset temperature. Take a frequency corresponding to a highest signal absorption value in each preset temperature as an adjustment frequency corresponding to each preset temperature.

8. A radio frequency heating system characterized by, The radio frequency heating system comprises the radio frequency heating device according to any one of claims 1-7 and a mechanical arm.

9. The radio frequency heating system of claim 8, wherein, The radio frequency heating system further comprises a compression roller device. The mechanical arm is further used to grip the compression roller device and drive the compression roller device to move along with the radio frequency heating device, so that the compression roller device heats and / or compacts the to-be-heated object after the radio frequency heating module heats the to-be-heated object.

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