Electromagnetic heating-ultrasonic assisted friction welding of dissimilar materials

Abstract

The present application relates to the technical field of dissimilar material welding of titanium alloy, high-temperature alloy and other dissimilar materials in an aero-engine, and particularly relates to a dissimilar material friction welding method and device with electromagnetic heating and ultrasonic assistance. The device comprises a spindle system, a tailstock system, an electromagnetic heating device and an ultrasonic loading system. The spindle system comprises a spindle side box, a spindle side clamp, a spindle and a flywheel; the tailstock system comprises a tailstock slide, a tailstock fixed seat and a tailstock side clamp. The electromagnetic heating device integrates a ring-shaped induction coil, a heat insulation layer and a temperature sensor, and is used for preheating the welding interface to below the material recrystallization temperature. The ultrasonic loading system is integrated in the tailstock side clamp, and high-frequency vibration is applied to the interface by a top forging head. The welding method comprises the following steps: after clamping the workpiece, the joint surface is preheated to 150-200 DEG C by electricity, the coil is removed, friction welding is started, ultrasonic waves are applied at the moment when the spindle stops rotating, the coil is reassembled and pressure is maintained, and the temperature is lowered in stages; the present application improves the joint performance and reduces residual stress.

Description

Technical Field

[0001] This invention relates to the field of welding technology for dissimilar materials such as titanium alloys and high-temperature alloys in aero-engines, and specifically to a method and apparatus for friction welding dissimilar materials using electromagnetic heating and ultrasonic assistance. Background Technology

[0002] Inertial friction welding, a solid-state welding technology, involves the following process: The workpieces to be welded are fixed to the spindle end and the sliding tailstock end, respectively. When the spindle speed reaches a set value, the spindle drive motor disengages from the spindle. The tailstock end, driven by a hydraulic servo, moves towards the spindle end. Frictional heat is generated at the contact interface, and under the action of friction, the material temperature gradually increases. Plastic deformation occurs at the welding interface, and welding takes place under the action of upsetting pressure. Simultaneously, flywheel energy is consumed, and the workpiece rotation speed decreases. When the spindle speed drops to zero, the upsetting pressure is maintained for a certain period, welding is completed, and the tailstock end retracts.

[0003] Inertial friction welding (IFW) technology is widely used in joining similar or dissimilar materials in aero-engine rotor components (such as rotor discs and turbine shafts). However, due to differences in thermophysical properties (such as coefficients of thermal expansion and thermal conductivity), dissimilar materials are prone to problems such as stress concentration at the weld interface, residual oxide film, and insufficient dynamic recrystallization. In traditional processes, fusion welding methods such as electron beam welding are gradually being replaced due to their susceptibility to hot cracking and poor compatibility with dissimilar materials. Existing IFW still has some shortcomings in welding dissimilar materials: First, insufficient preheating: the large initial temperature gradient of dissimilar materials leads to uneven heat input during the friction stage and inconsistent plastic deformation at the interface. Second, incomplete removal of the oxide layer: oxides easily remain at the interface of dissimilar materials, affecting metallurgical bonding. Third, limited grain refinement during the upsetting stage: relying solely on upsetting force is insufficient to fully promote dynamic recrystallization, and the mechanical properties of the joint are difficult to meet design requirements. Fourth, the temperature drops sharply after welding, leading to stress concentration at the weld and unstable flash formation after welding. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method and apparatus for electromagnetic heating-ultrasonic assisted friction welding of dissimilar materials; the specific technical solution is as follows:

[0005] An electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials includes a spindle system, a tailstock system, an electromagnetic heating device, and an ultrasonic loading system;

[0006] The spindle system includes a spindle-side housing, a spindle-side clamp, a spindle, and a spindle-side flywheel;

[0007] The spindle side housing is fixedly installed on the left reference surface of the bed; the spindle horizontally passes through the interior of the spindle side housing.

[0008] The flywheel is fixed to the end journal of the spindle via a keyway. The motor is fixed to the outside of the spindle side housing and coaxially connected to the spindle to drive the spindle to rotate. A spindle side clamp is fixed to the other end of the spindle, and the workpiece to be welded on the spindle side is clamped and fixed by the spindle side clamp.

[0009] The tailstock system includes a tailstock slide mounted on the other side of the bed via a movable slide rail. The tailstock slide is mounted in the movable slide box via a tailstock fixing seat. A tailstock side clamp is mounted on the tailstock fixing seat, and the tailstock side workpiece to be welded is clamped and fixed by the tailstock side clamp.

[0010] The electromagnetic heating device includes a temperature control system, a ring induction coil, a heat insulation layer, and a temperature sensor. The heat insulation layer covers the outside of the ring induction coil and is wound around the outside of the joint surface between the workpiece to be welded on the spindle side and the workpiece to be welded on the tailstock side. The temperature sensor is used to insert into the workpiece surface. The temperature control system is electrically connected to the ring induction coil and the temperature sensor. The workpiece is heated by setting the heating temperature through the temperature control system.

[0011] The ultrasonic loading system includes an ultrasonic generator, an ultrasonic transducer, an ultrasonic amplitude transformer, and an upsetting head; the ultrasonic generator, ultrasonic transducer, and ultrasonic amplitude transformer are sequentially connected and integrated inside the tailstock side fixture, and the end of the ultrasonic amplitude transformer is connected to the upsetting head, the end of which applies high-frequency vibration to the welding interface.

[0012] The spindle-side housing and the tailstock slide are arranged opposite each other, so that the mating surfaces of the spindle-side workpiece to be welded and the tailstock-side workpiece to be welded are aligned.

[0013] The preferred embodiment of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials is that, in the electromagnetic heating device, the temperature control system monitors the temperature of the joint surface in real time through a temperature sensor and adjusts the heating power of the annular induction coil to make the interface temperature rise uniformly to a preset value, which is lower than the material recrystallization temperature.

[0014] The preferred embodiment of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials is as follows: in the ultrasonic loading system, the ultrasonic generator converts the mains power into an ultrasonic frequency AC signal, the ultrasonic transducer converts the electrical signal into mechanical vibration, the ultrasonic amplitude transformer amplifies the vibration amplitude and transmits it to the welding interface through the upsetting head.

[0015] The welding method of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials, the welding steps are as follows:

[0016] The welding method of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials, the welding steps are as follows:

[0017] Step 1, workpiece clamping: The workpiece to be welded on the spindle side is clamped and fixed by the spindle-side fixture, and the workpiece to be welded on the tailstock side is clamped and fixed by the tailstock-side fixture;

[0018] Step 2, Electromagnetic preheating: Wrap the ring induction coil around the outside of the joint surface between the workpiece to be welded on the spindle side and the workpiece to be welded on the tailstock side, start the electromagnetic heating device, and set the preheating temperature through the temperature control system so that the temperature of the joint surface rises uniformly to the preset value and is lower than the material recrystallization temperature.

[0019] Step 3, Remove the induction coil: After preheating, remove the ring induction coil;

[0020] Step 4, Friction Welding: Start the motor to drive the spindle to rotate. After the speed reaches the set value, the motor disengages and the tailstock slide moves towards the spindle side, so that the two parts to be welded come into contact and friction welding begins.

[0021] Step 5: Begin welding: Friction generates heat to bring the joint surface to a plastic state;

[0022] Step 6, Ultrasonic Assistance: At the instant the spindle stops rotating, the ultrasonic loading system is activated, and high-frequency ultrasonic vibration is applied to the welding interface through the upsetting head;

[0023] Step 7, Coil Reinstallation and Pressure Holding: Rewind the ring-shaped induction coil to the outside of the mating surface and hold pressure;

[0024] Step 8, Post-weld temperature control: Activate the electromagnetic heating device to cool the welding area in a step-by-step manner: first keep it warm to a temperature higher than the brittle zone of the material, and then cool it down to room temperature in a step-by-step manner.

[0025] Step 9: Disassemble the workpiece: Remove the ring induction coil, loosen the welded part from the tailstock side clamp, and return the tailstock slide to its initial position.

[0026] The preferred embodiment of the welding method of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials is that, in step two, the preheating temperature ranges from 150℃ to 200℃, and the heating time is ≤10s.

[0027] The preferred embodiment of the welding method of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials is that, in step four, the flywheel inertia is 2500–3500 kg·m. 2 The rotation speed is 300–400 rpm, and the upsetting pressure is 350–450 MPa.

[0028] The preferred embodiment of the welding method of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials is as follows: in step six, the frequency of the ultrasonic vibration is 15–40 kHz, the amplitude is 10–30 μm, and the action time is 2–5 s, which is used to break the oxide layer at the interface and promote dynamic recrystallization.

[0029] The preferred embodiment of the welding method of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials is as follows: in step eight, the stepped cooling specifically involves maintaining the weld temperature above the temperature of the brittle zone of the material during the heat preservation stage, and then cooling to room temperature in stages at a rate of 50–150°C every 5 minutes.

[0030] Compared with the prior art, the present invention has the following beneficial technical effects:

[0031] Compared with existing methods and apparatus for inertial friction welding of dissimilar materials, this technical solution solves the problems of insufficient preheating during the current process, which leads to large initial temperature gradients, uneven heat input, and inconsistent interfacial plastic deformation. It thoroughly removes the oxide layer, reducing metallurgical bonding defects in dissimilar materials. It promotes dynamic recrystallization of grains during the upsetting stage, improving the mechanical properties of the joint. The post-weld temperature decreases slowly, reducing stress concentration at the weld. Attached Figure Description

[0032] Figure 1 A schematic diagram of a device for inertial friction welding of dissimilar materials using electromagnetic heating and ultrasonic assistance.

[0033] Figure 2 This is a schematic diagram of the electromagnetic heating device.

[0034] Figure 3 This is a schematic diagram of the ultrasonic loading system.

[0035] In the diagram: 1-Spindle side housing, 2-Motor, 3-Spindle side fixture, 4-Spindle, 5-Spindle side flywheel, 6-Spindle side workpiece to be welded, 7-Electromagnetic heating device, 8-Tailstock slide, 9-Tailstock fixing seat, 10-Tailstock side fixture, 11-Tailstock side workpiece to be welded, 12-Temperature control system, 13-Ring induction coil, 14-Insulation layer, 15-Temperature sensor, 16-Ultrasonic generator, 17-Ultrasonic transducer, 18-Ultrasonic amplitude transformer, 19-Upsetting head, 20-Ultrasonic loading system. Detailed Implementation

[0036] The following is in conjunction with the appendix Figure 1-3 The present invention will be described in detail, but the scope of protection of the present invention is not limited by the accompanying drawings.

[0037] An electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials includes a spindle system, a tailstock system, an electromagnetic heating device 7, and an ultrasonic loading system 20.

[0038] The spindle system includes a spindle-side housing 1, a spindle-side clamp 3, a spindle 4, and a spindle-side flywheel 5;

[0039] The spindle-side housing 1 is fixedly installed on the left reference surface of the bed; the spindle 4 horizontally penetrates the interior of the spindle-side housing 1.

[0040] The flywheel 5 is fixed to the end journal of the main shaft 4 via a keyway. The motor 2 is fixed to the outside of the main shaft side housing 1 and coaxially connected to the main shaft 4 to drive the main shaft 4 to rotate. The other end of the main shaft 4 is fixed with a main shaft side clamp 3, and the main shaft side workpiece 6 to be welded is clamped and fixed by the main shaft side clamp 3.

[0041] The tailstock system includes a tailstock slide 8 installed on the other side of the bed via a movable slide rail. The tailstock slide 8 is installed in the movable slide box via a tailstock fixing seat 9. The tailstock side clamp 10 is installed on the tailstock fixing seat 9. The tailstock side workpiece 11 to be welded is clamped and fixed by the tailstock side clamp 10.

[0042] The electromagnetic heating device 7 includes a temperature control system 12, a ring induction coil 13, a heat insulation layer 14, and a temperature sensor 15. The heat insulation layer 14 covers the outside of the ring induction coil 13 and is wound around the outside of the joint surface between the workpiece 6 on the spindle side and the workpiece 11 on the tailstock side. The temperature sensor 15 is used to insert into the surface of the workpiece. The temperature control system 12 is electrically connected to the ring induction coil 13 and the temperature sensor 15. The heating temperature is set by the temperature control system to heat the workpiece.

[0043] The ultrasonic loading system includes an ultrasonic generator 16, an ultrasonic transducer 17, an ultrasonic amplitude transformer 18, and an upsetting head 19. The ultrasonic generator 16, ultrasonic transducer 17, and ultrasonic amplitude transformer 18 are sequentially connected and integrated inside the tailstock side clamp 10. The end of the ultrasonic amplitude transformer 18 is connected to the upsetting head 19, and the end of the upsetting head 19 applies high-frequency vibration to the welding interface.

[0044] The spindle-side housing 1 and the tailstock slide 8 are arranged opposite each other so that the mating surfaces of the spindle-side weldment 6 and the tailstock-side weldment 11 are aligned.

[0045] In the preferred embodiment of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials, the temperature control system 12 in the electromagnetic heating device 7 monitors the temperature of the joint surface in real time through the temperature sensor 15 and adjusts the heating power of the annular induction coil 13 so that the interface temperature rises uniformly to a preset value, which is lower than the material recrystallization temperature.

[0046] In the preferred embodiment of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials, the ultrasonic generator 16 converts mains power into an ultrasonic frequency AC signal in the ultrasonic loading system, the ultrasonic transducer 17 converts the electrical signal into mechanical vibration, and the ultrasonic amplitude transformer 18 amplifies the vibration amplitude and transmits it to the welding interface through the upsetting head 19.

[0047] Example 1

[0048] Taking the welding of dissimilar materials, TC4 titanium alloy and IN718 nickel-based superalloy, as an example, the specific steps are as follows:

[0049] Step 1, workpiece clamping: The TC4 weldment is clamped and fixed by the spindle-side clamp 3, and the IN718 weldment is clamped and fixed by the tailstock-side clamp 10;

[0050] Step 2, Electromagnetic preheating: The ring induction coil 13 is wound around the outside of the joint surface between the TC4 and IN718 weldments. The electromagnetic heating device 7 is started, with an electromagnetic coil frequency of 10kHz. The preheating temperature parameters for TC4 are set to 150℃ and the heating time is ≤10s. The preheating temperature parameters for IN718 are set to 200℃ and the heating time is ≤10s. The temperature sensor 15 monitors the temperature in real time, and the temperature control system 12 dynamically adjusts the power to ensure that the temperature is uniform and below the material recrystallization temperature.

[0051] Step 3, Remove the ring induction coil: After preheating, remove the ring induction coil 13;

[0052] Step 4, Friction Welding: Start motor 2 to drive spindle 4, which in turn rotates the TC4 workpiece to the set speed of 350 rpm; disengage the motor, and the flywheel 5 has a moment of inertia of 3000 kg·m. 2 Maintain rotation; the tailstock slide 8 drives the IN718 weldment to move towards the spindle side box 1, so that the two workpieces come into contact; make the joint surfaces of the TC4 weldment and the IN718 weldment come into contact and start friction welding, and apply an upsetting pressure of 400MPa.

[0053] Step 5: Begin welding: Friction generates heat to bring the joint surface to a plastic state;

[0054] Step 6, Ultrasonic Assistance: At the instant the spindle 4 stops rotating, the ultrasonic loading system is activated; the forging head 19 applies vibration to the welding interface at a frequency of 30kHz, an amplitude of 20μm, and a duration of 3s; this breaks up the oxide layer at the interface and promotes dynamic recrystallization.

[0055] Step 7, coil reloading and pressure holding: The ring induction coil 13 is rewound around the outside of the joint surface and pressure held for 60 seconds;

[0056] Step 8, Post-weld temperature control: Start the electromagnetic heating device 7 and cool down in stages: First, keep the welding area at 800°C, which is higher than the temperature of the brittle zone of the material; then cool it down to room temperature in stages at a rate of 100°C every 5 minutes.

[0057] Step 9, Disassemble the workpiece: After welding, remove the induction coil 13; release the tailstock side clamp 10; return the tailstock slide 8 to the initial position.

Claims

1. An electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials, characterized in that, It includes a spindle system, a tailstock system, an electromagnetic heating device (7), and an ultrasonic loading system (20); The spindle system includes a spindle-side housing (1), a spindle-side clamp (3), a spindle (4), and a spindle-side flywheel (5); The spindle side housing (1) is fixedly installed on the left reference surface of the bed; the spindle (4) horizontally penetrates the interior of the spindle side housing (1); The flywheel (5) is fixed to the end journal of the main shaft (4) by keyway engagement. The motor (2) is fixed to the outside of the main shaft side housing (1) and coaxially connected with the main shaft (4) to drive the main shaft (4) to rotate. The other end of the main shaft (4) is fixed with a main shaft side clamp (3), and the main shaft side workpiece (6) to be welded is clamped and fixed by the main shaft side clamp (3). The tailstock system includes a tailstock slide (8) installed on the other side of the bed via a movable slide rail. The tailstock slide (8) is installed in the movable slide box via a tailstock fixing seat (9). The tailstock side clamp (10) is installed on the tailstock fixing seat (9). The tailstock side workpiece (11) to be welded is clamped and fixed by the tailstock side clamp (10). The electromagnetic heating device (7) includes a temperature control system (12), a ring induction coil (13), a heat insulation layer (14), and a temperature sensor (15). The heat insulation layer (14) covers the outside of the ring induction coil (13) and is wound around the outside of the joint surface between the spindle-side workpiece (6) and the tailstock-side workpiece (11). The temperature sensor (15) is used to insert into the workpiece surface. The temperature control system (12) is electrically connected to the ring induction coil (13) and the temperature sensor (15). The workpiece is heated by setting the heating temperature through the temperature control system. The ultrasonic loading system includes an ultrasonic generator (16), an ultrasonic transducer (17), an ultrasonic amplitude transformer (18), and an upsetting head (19); the ultrasonic generator (16), the ultrasonic transducer (17), and the ultrasonic amplitude transformer (18) are connected in sequence and integrated inside the tailstock side clamp (10), and the end of the ultrasonic amplitude transformer (18) is connected to the upsetting head (19), and the end of the upsetting head (19) acts to apply high-frequency vibration to the welding interface. The main spindle side housing (1) is arranged opposite to the tailstock slide (8) so that the mating surfaces of the main spindle side workpiece (6) and the tailstock side workpiece (11) are aligned.

2. The electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials according to claim 1, characterized in that: In the electromagnetic heating device (7), the temperature control system (12) monitors the temperature of the joint surface in real time through the temperature sensor (15) and adjusts the heating power of the ring induction coil (13) so that the interface temperature rises uniformly to the preset value, which is lower than the material recrystallization temperature.

3. The electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials according to claim 1, characterized in that: In the ultrasonic loading system, the ultrasonic generator (16) converts the mains power into an ultrasonic frequency AC signal, the ultrasonic transducer (17) converts the electrical signal into mechanical vibration, and the ultrasonic amplitude transformer (18) amplifies the vibration amplitude and transmits it to the welding interface through the upsetting head (19).

4. The welding method of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials according to any one of claims 1-3, characterized in that: The welding steps are as follows: Step 1, workpiece clamping: The spindle-side workpiece to be welded (6) is clamped and fixed by the spindle-side clamp (3), and the tailstock-side workpiece to be welded (11) is clamped and fixed by the tailstock-side clamp (10); Step 2, electromagnetic preheating: The ring induction coil (13) is wound around the outside of the joint surface of the workpiece (6) to be welded on the main shaft side and the workpiece (11) to be welded on the tailstock side. The electromagnetic heating device (7) is started and the preheating temperature is set through the temperature control system (12) so that the temperature of the joint surface rises uniformly to the preset value and is lower than the material recrystallization temperature. Step 3, Remove the induction coil: After preheating, remove the ring induction coil (13); Step 4, Friction Welding: Start the motor (2) to drive the spindle (4) to rotate. After the speed reaches the set value, the motor disengages and the tailstock slide (8) moves towards the spindle side, so that the two parts to be welded come into contact and friction welding begins. Step 5: Begin welding: Friction generates heat to bring the joint surface to a plastic state; Step 6, Ultrasonic Assistance: At the instant the spindle stops rotating, the ultrasonic loading system is started, and high-frequency ultrasonic vibration is applied to the welding interface through the upsetting head (19); Step 7, coil rewinding and pressure holding: rewind the annular induction coil (13) to the outside of the mating surface and hold pressure; Step 8, post-weld temperature control: Start the electromagnetic heating device (7) to cool the welding area in a step-by-step manner: first keep it warm to a temperature higher than the brittle zone of the material, and then cool it down to room temperature in a step-by-step manner; Step 9: Disassemble the workpiece: Remove the ring induction coil (13), loosen the welded part from the tailstock side clamp, and return the tailstock slide (8) to the initial position.

5. The welding method of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials according to claim 4, characterized in that: In step two, the preheating temperature ranges from 150℃ to 200℃, and the heating time is ≤10s.

6. The welding method of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials according to claim 4, characterized in that: In step four, the flywheel moment of inertia is 2500–3500 kg·m. 2 The rotation speed is 300–400 rpm, and the upsetting pressure is 350–450 MPa.

7. The welding method of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials according to claim 4, characterized in that: In step six, the frequency of the ultrasonic vibration is 15–40 kHz, the amplitude is 10–30 μm, and the duration is 2–5 s, which is used to break the oxide layer at the interface and promote dynamic recrystallization.

8. The welding method of the electromagnetic heating-ultrasonic assisted friction welding device for dissimilar materials according to claim 4, characterized in that: In step eight, the stepped cooling specifically involves maintaining the weld temperature above the brittle zone temperature during the heat preservation stage, and then cooling it to room temperature in stages at a rate of 50–150°C every 5 minutes.

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