Resistance welding system for thermoplastic resin matrix composite product

Abstract

The utility model provides a resistance welding system for a thermoplastic resin matrix composite product. The resistance welding system comprises a heating wire belt arranged between welding surfaces of a to-be-welded part and a heating mechanism electrically connected with the heating wire belt, and a temperature detection mechanism is arranged on the corresponding welding seam. According to the utility model, the heating wire belt is laid on the welding surface of the thermoplastic resin-based composite material product and pressed on the welding surface of another piece to be welded, and the heating mechanism controls the heating wire belt to heat so as to melt the thermoplastic resin, so that one-time welding of the large thermoplastic resin-based composite material product is realized; the welding efficiency and the welding quality are improved; and the heating wire belt can be bent, so that the welding system is not limited by the shape of the welding part of the to-be-welded part.

Description

Technical Field

[0001] This utility model relates to the field of welding technology, and in particular to a resistance welding system. Background Technology

[0002] Some large thermoplastic resin-based composite products, such as wind turbine blades and ships, require joining technologies due to their manufacturing processes. These large wind turbine blades and ships involve connections between curved surfaces due to their manufacturing processes. For example, large wind turbine blades require separate manufacturing of the windward and leeward sides, which are then joined together to form a complete blade. Current technologies use adhesives for bonding, but adhesive bonding is costly, has low connection strength, and requires high-quality bonding surfaces. Ships, for instance, use mechanical connections, but these are prone to stress concentration and are not conducive to weight reduction. However, for the curved surface welding of large thermoplastic resin-based composite products, such as wind turbine blades and ships, as well as the non-planar welding of various thermoplastic resin-based composite products, existing technologies lack corresponding welding systems.

[0003] Patent application publication date: August 19, 2022, patent publication number: CN 114919197 A, discloses a resistance welding system and method for carbon fiber / polyaryletherketone composite material laminates, including a heating system, a cooling system, a pressure system, a monitoring system, and tooling. The heating system provides the heat required for resin melting on the welding surface; the cooling system prevents overheating at the welding area ends; the pressure system includes a microcomputer-controlled electronic universal testing machine and a pressure block to transfer force to the welding area. This system can solve the problem of high melting point of polyaryletherketone and difficulty in controlling welding quality. However, this system requires molds and tooling and can only weld flat plates. Currently, there are no commercially available welding systems for curved or non-planar surfaces of large thermoplastic resin-based composite material products. Summary of the Invention

[0004] To address the aforementioned technical problems, this utility model proposes a resistance welding system for thermoplastic resin-based composite material products, which solves the problem of the lack of a non-planar welding system for large thermoplastic resin-based composite material products in the prior art.

[0005] To achieve the above objectives, the technical solution of this utility model is implemented as follows:

[0006] A resistance welding system for thermoplastic resin-based composite materials includes a heating wire disposed between the welding surfaces of the parts to be welded and a heating mechanism electrically connected to the heating wire; a temperature detection mechanism is provided on the corresponding weld. This invention achieves one-time welding of large thermoplastic resin-based composite materials by placing the heating wire on the welding surface of the thermoplastic resin-based composite material and pressing it onto the welding surface of another part to be welded. The heating mechanism controls the heating wire to heat up, causing the thermoplastic resin to melt, thus improving welding efficiency and quality. Furthermore, because the heating wire is flexible, this welding system is not limited by the shape of the parts to be welded.

[0007] Furthermore, the welding surface is a curved surface.

[0008] Furthermore, in order to make the heating ribbon lightweight and better fit non-planar welding surfaces such as curved surfaces, the heating ribbon is a carbon fiber heating ribbon.

[0009] Furthermore, the heating mechanism includes a power source and two sets of electrodes connected to the power source, with the two sets of electrodes respectively connected to both ends of the heating ribbon.

[0010] Furthermore, each set of electrodes includes a pair of metal strips, which are clamped to the end of the heating ribbon by fasteners.

[0011] Furthermore, a wire lug is clamped between the fastener and the heating ribbon, and the wire lug is used to connect the power supply terminal via a cable.

[0012] Furthermore, the temperature detection mechanism includes a thermocouple attached to the weld and a temperature detector connected to the thermocouple.

[0013] Furthermore, it also includes a cooling mechanism for cooling the welded area, which is configured in conjunction with a heating wire and / or a heating mechanism.

[0014] Furthermore, the cooling mechanism includes an exhaust pipe and an air supply component connected to the exhaust pipe, with a nozzle on the exhaust pipe facing the weld.

[0015] Furthermore, the exhaust pipe includes a main exhaust pipe and several branch exhaust pipes disposed on the main exhaust pipe. One end of each branch exhaust pipe is connected to the main exhaust pipe, and the branch exhaust pipes are disposed close to the weld. The nozzle is disposed on the branch exhaust pipe.

[0016] The beneficial effects of this utility model are:

[0017] 1. This utility model achieves one-time welding of large thermoplastic resin-based composite products by laying a heating ribbon on the welding surface of a thermoplastic resin-based composite product and pressing it on the welding surface of another part to be welded. The heating ribbon is heated by power supply to melt the resin, thus achieving one-time welding of large thermoplastic resin-based composite products without being affected by the shape of the part.

[0018] 2. This utility model enables temperature detection and real-time control during the welding process of thermoplastic composite materials through a temperature detection mechanism;

[0019] 3. The resistance welding system of this utility model results in good resin melting uniformity, high welding strength, and high welding efficiency;

[0020] 4. This utility model does not require the manufacture of additional molds or tooling, thus saving costs;

[0021] 5. The heating ribbon of this utility model is made of carbon fiber, achieving the goal of lightweight composite materials. Attached Figure Description

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

[0023] Figure 1 This is a schematic diagram of the structure of this utility model.

[0024] Figure 2 This is a schematic diagram of an application scenario for Embodiment 7 of this utility model.

[0025] Figure 3 This is a schematic diagram of an application scenario for Embodiment 8 of this utility model.

[0026] In the diagram: 1. DC power supply; 11. Adjustment knob; 12. Terminal block; 13. Electrode; 14. Wire lug; 15. Fastener; 16. Cable; 2. Heating ribbon; 3. Thermoplastic resin-based composite material product; 4. Temperature detector; 41. Thermocouple; 5. Air compressor; 51. Main exhaust pipe; 52. Branch exhaust pipe; 53. Nozzle; 6. Blade mold; 61. Hinge seat; 7. Half blade one; 71. Half blade two; 8. Hull; 81. Cabin. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] like Figure 1 As shown in Embodiment 1 of this utility model, a resistance welding system for thermoplastic resin-based composite materials includes a heating wire 2 disposed between the welding surfaces of the workpiece 3 to be welded and a heating mechanism electrically connected to the heating wire 2; a temperature detection mechanism is provided on the corresponding weld. In this embodiment, the welding surface is curved. In other embodiments, it can be used for resistance welding of planar or non-planar thermoplastic resin-based composite materials.

[0029] Furthermore, such as Figure 2 As shown, the heating mechanism includes a power supply 1 and two sets of electrodes 13 connected to the power supply 1. The two sets of electrodes 13 are respectively connected to both ends of the heating ribbon 2. Each set of electrodes 13 consists of two metal strips; in this embodiment, copper strips are preferred, with the heating ribbon sandwiched between the two copper strips. The anode and cathode of the power supply 1 are connected to the two pairs of electrodes 13 via cables 16, respectively, to input current to both ends of the heating ribbon for heating. The power supply has an output range of 0–24V and 0–111A, with both constant current and constant voltage output modes. During resistance welding, the constant current output mode is preferred to ensure welding power.

[0030] In one embodiment, screw holes are opened at both ends of the two copper strips, and the two copper strips are fixed by copper bolts, i.e. fasteners 15, and the heating ribbon is clamped between the two copper strips.

[0031] Furthermore, such as Figure 2 As shown, a wire lug 14 is held between the fastener 15 and the heating ribbon 2. The wire lugs 14 at both ends of the heating ribbon 2 are connected to the anode and cathode terminals 12 of the power supply 1 via cables 16.

[0032] Example 2 differs from Example 1 in that the heating ribbon 2 is a carbon fiber ribbon composed of flat carbon fiber bundles. The areal density of the carbon fiber ribbon is 30-150 g / m³. 2 .

[0033] Example 3 differs from Example 2 in that, as Figure 2As shown, the temperature detection mechanism includes thermocouples 41 attached to the weld and a temperature detector 4 connected to the thermocouples 41. Thermocouples 41 are attached to the weld surface at regular intervals, allowing for real-time detection of temperature changes at the weld surface. The thermocouples are type K and are patch-shaped, meaning the thermocouples 41 are thermocouple patches. The temperature detector can display the current temperature and heating time of the thermocouples in real time.

[0034] Example 4 differs from Example 3 in that it further includes a cooling mechanism 5 for cooling the welded area, and the cooling mechanism 5 is configured in conjunction with the heating ribbon 2 and / or the heating mechanism.

[0035] Furthermore, such as Figure 2 As shown, the cooling mechanism includes an exhaust pipe and an air supply component connected to the exhaust pipe. The exhaust pipe is equipped with nozzles 53 facing the weld. The exhaust pipe includes a main exhaust pipe 51 and several branch exhaust pipes 52 disposed on the main exhaust pipe 51. One end of each branch exhaust pipe 52 is connected to the main exhaust pipe 51, and the branch exhaust pipes 52 are positioned close to the weld. The nozzles 53 are disposed on the branch exhaust pipes 52. In this embodiment, the air supply component is an air compressor 5; two branch exhaust pipes 52 are provided. The main exhaust pipe 51 connects the air compressor and the two branch exhaust pipes. The two branch exhaust pipes are arranged parallel to each other along both sides of the weld, with a gas nozzle disposed every 0.5~1.5m. Compressed gas generated by the air compressor is ejected through the exhaust pipes and the nozzles 53, acting on the edge of the weld surface to alleviate overheating during welding and to rapidly cool the weldment.

[0036] Optionally, the air compressor can regulate the compressed gas through a pressure regulating valve, adjusting the compressed gas pressure between 0 MPa and 1 MPa to achieve a stable gas output, with 0.2 to 0.3 MPa preferably used as the cooling gas pressure. The nominal inner diameter of the exhaust pipe ranges from 20 to 32 mm, with a preferred main air path of 32 mm and branch air paths of 25 mm. The nozzle 53 is a fan-shaped gas nozzle with a nozzle diameter ranging from 1 to 5 mm and a fan-shaped nozzle angle ranging from 30° to 140°, with a preferred optimal nozzle diameter of 2 mm and an optimal fan-shaped nozzle angle range of 120°.

[0037] Example 5 differs from Example 4 in that, in order to better bond the heating ribbon with the thermoplastic resin-based composite material product, the heating ribbon 2 can be pre-wrapped with thermoplastic resin.

[0038] In one embodiment, when the thermoplastic resin-based composite material product is a PMMA-based composite material product, PMMA resin is used for encapsulation. In this embodiment, the encapsulating agent is preferably an MMA solution containing PMMA. The product is immersed in an MMA solution containing PMMA with a viscosity between 50 and 300 mPa·s for 5 to 12 hours, followed by drying at 20 to 80°C. The mass of the encapsulated PMMA should account for 5-30 wt% of the mass of the heating ribbon. Then, the encapsulated carbon fiber ribbon is used for resistance welding of the PMMA-based composite material product. In this embodiment, the welding temperature is between 160 and 250°C, and the heating time is between 5 and 20 minutes.

[0039] Example 6: The resistance welding method of the resistance welding system of this utility model includes the following steps:

[0040] 1. Preparation of the heating ribbon for welding: Cut carbon fiber ribbons of appropriate length and width, soak them in an MMA solution containing PMMA with a viscosity between 50 and 300 mPa∙s at room temperature for 5 to 12 hours, and then dry them at 20 to 80°C before use;

[0041] 2. Secure the heating ribbon with a small amount of mesh fiber double-sided tape or cut and overlap the heating ribbon to ensure it is tightly bonded to the welding surface of one of the thermoplastic resin-based composite products to be welded;

[0042] 3. Place another thermoplastic resin-based composite material product to be welded. When the two parts to be welded are placed one above the other, the weight of the upper part to be welded can be used (if the weight is insufficient, an auxiliary mechanism or heavy object can be used to compact it) so that the welding surfaces of the two thermoplastic resin-based composite material products to be welded are in close contact with the heating ribbon.

[0043] 4. At the appropriate location on the weld, attach thermocouple patches and connect a temperature detector with time display function 4;

[0044] 5. Install an exhaust pipe and connect it to an air compressor at a suitable location on the weld seam;

[0045] 6. The heating ribbon connects the electrode and the power supply 1;

[0046] 7. Welding is performed by energizing the circuit. During the process, temperature detector 4 monitors the temperature in real time.

[0047] 8. After a certain period of time, disconnect the power. Use a cooling device to rapidly cool the workpiece by blowing air, thereby accelerating the cooling of the workpiece and allowing the molten material to solidify quickly, completing the welding process.

[0048] Furthermore, when using this resistance welding system, the heating ribbon can be pre-fixed using an adhesive. The adhesive is a double-sided mesh tape. For bends or curved surfaces where the heating ribbon 2 is uneven, the mesh double-sided tape can be used for bonding and fixing, or the uneven heating ribbon 2 can be cut and overlapped. The mesh double-sided tape can also be used to fix the heating ribbon at a certain distance from the bonding surface, allowing the heating ribbon to better adhere to the bonding surface. When the heating ribbon is uneven at the bonding surface, it can also be cut and overlapped.

[0049] Example 7 differs from Example 4 in that the resistance welding system is used for welding PMMA-based composite wind turbine blades. During the process, a blade mold 6 can be used to assist in the welding process. The blade mold 6 has two blades, which are hinged together by a hinged connector 61. The process is as follows:

[0050] like Figure 2 As shown, the wind turbine blade is formed by bonding half a blade 7 on one blade mold 6 and the other half a blade 71 on another blade mold 6. First, the heating ribbon is pre-treated: a suitable area of ​​heating ribbon is cut, soaked in an MMA solution containing PMMA with a viscosity of 100 mPa·s at room temperature for 10 hours, and then dried at 60°C. The welding surface of half blade 7 is cleaned, and the processed heating ribbon 2 is laid on top. Fiber-reinforced double-sided tape is used to fix the curved surfaces of the blade. Then, the upper blade mold 6 is flipped over to flip half blade 71. Using the weight of the mold and the blade, the welding surface of half blade 71 is tightly bonded to the heating ribbon. Figure 2 and Figure 1 Thermocouple patches are attached to the weld seam of the wind turbine blade. A cooling mechanism is installed inside and outside the wind turbine blade near the weld seam, using electrodes 13 and cables 16 to connect the heating wire 2 and the power supply 1. The current is adjusted to 8A using the adjustment knob 11 of the power supply 1, and the power is turned off after the temperature is detected by the temperature detector 4 at 200℃. After the cooling mechanism is used to blow the weld seam of the wind turbine blade for 10 minutes, the welding is completed once the temperature detector 4 displays room temperature.

[0051] Example 8 differs from Example 4 in that this resistance welding system is used for shipbuilding using PMMA-based composite materials. The process is as follows:

[0052] like Figure 3As shown, the hull 8 and cabin 81 of the ship can be welded using this resistance welding system. First, the heating ribbon is pre-treated: a suitable area of ​​heating ribbon is cut, soaked in an MMA solution containing PMMA with a viscosity of 50 mPa·s at room temperature for 6 hours, and then dried at 60°C. The treated heating ribbon 2 is laid on the bonding surface of the hull 8. For bends in the ship, the heating ribbon 2 can be fixed using double-sided tape. Then, the cabin 81 is placed on the hull 8, and a weight is placed on the cabin 81 to ensure the heating ribbon 2 is tightly bonded to the hull 8 and cabin 81. Figure 3 and Figure 1 Thermocouple patches are attached to the weld seam. A cooling mechanism is set up near the upper and lower weld seams of the vessel. Electrode 13 and cable 16 are used to connect the heating wire 2 and power supply 1. The current is adjusted to 6A using knob 11. After the temperature is detected by temperature detector 4 at 180℃, the power is turned off. Then, the cooling mechanism is used to blow the weld seam of the wind turbine blade for 10 minutes. After the temperature detector 4 displays room temperature, the welding is complete.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some or all of the technical features thereof, within the spirit and principles of the present invention, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A resistance welding system for thermoplastic resin-based composite material products, characterized in that, It includes a heating ribbon (2) for setting between the welding surfaces of the workpiece (3) to be welded and a heating mechanism electrically connected to the heating ribbon (2); a temperature detection mechanism is provided on the corresponding weld.

2. The resistance welding system for thermoplastic resin-based composite material products according to claim 1, characterized in that, The welding surface is curved.

3. The resistance welding system for thermoplastic resin-based composite material articles according to claim 1 or 2, characterized in that, The heating ribbon (2) is a carbon fiber heating ribbon.

4. The resistance welding system for thermoplastic resin-based composite material articles according to claim 1 or 2, characterized in that, The heating mechanism includes a power source (1) and two sets of electrodes (13) connected to the power source (1), and the two sets of electrodes (13) are respectively connected to the two ends of the heating ribbon (2).

5. The resistance welding system for thermoplastic resin-based composite material articles according to claim 4, characterized in that, Each set of electrodes (13) includes a pair of metal strips, which are clamped to the end of the heating ribbon (2) by fasteners (15).

6. The resistance welding system for thermoplastic resin-based composite material articles according to claim 5, characterized in that, The fastener (15) holds a wire lug (14) between itself and the heating ribbon (2), and the wire lug (14) is connected to the terminal (12) of the power supply (1) via a cable (16).

7. The resistance welding system for thermoplastic resin-based composite articles according to claim 1, 2, or 6, characterized in that, The temperature detection mechanism includes a thermocouple (41) attached to the weld and a temperature detector (4) connected to the thermocouple (41).

8. The resistance welding system for thermoplastic resin-based composite articles according to claim 1, 2, or 6, characterized in that, It also includes a cooling mechanism for cooling the welded area, which is configured in conjunction with the heating ribbon (2) and / or the heating mechanism.

9. The resistance welding system for thermoplastic resin-based composite material articles according to claim 8, characterized in that, The cooling mechanism (5) includes an exhaust pipe and an air supply component connected to the exhaust pipe, and the exhaust pipe is provided with a nozzle (53) facing the weld.

10. The resistance welding system for thermoplastic resin-based composite material articles according to claim 9, characterized in that, The exhaust pipe includes a main exhaust pipe (51) and several branch exhaust pipes (52) disposed on the main exhaust pipe (51). One end of the branch exhaust pipe (52) is connected to the main exhaust pipe (51), and the branch exhaust pipe (52) is disposed close to the weld. The nozzle (53) is disposed on the branch exhaust pipe (52).

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