Electromagnetic heating-ultrasonic assisted dissimilar material friction welding method and device

Abstract

The invention relates to the technical field of welding of dissimilar materials such as titanium alloy and high-temperature alloy in aero-engines, in particular to an electromagnetic heating-ultrasonic assisted dissimilar material friction welding method and device. The device comprises a main shaft system, a tailstock system, an electromagnetic heating device and an ultrasonic loading system. The main shaft system comprises a main shaft side box body, a main shaft side clamp, a main shaft and a flywheel; the tailstock system comprises a tailstock sliding table, a tailstock fixing base and a tailstock side clamp. The electromagnetic heating device integrates an annular induction coil, a heat insulation layer and a temperature sensor and is used for preheating a welding interface to be lower than the material recrystallization temperature. The ultrasonic loading system is integrated in the tailstock side clamp, and high-frequency vibration is applied to an interface through a top forging press head. The welding method comprises the steps that after a workpiece is clamped, a joint face is electromagnetically preheated to 150-200 DEG C, a coil is dismantled, friction welding is started, ultrasonic waves are applied at the moment when a main shaft stops rotating, the coil is reinstalled, pressure maintaining is conducted, and stepped cooling is conducted; the connector performance is improved, and the residual stress is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of welding dissimilar materials such as titanium alloys and high-temperature alloys in aircraft engines, and in particular to a method and device for friction welding dissimilar materials assisted by electromagnetic heating and ultrasonic waves. Background Art

[0002] Inertia friction welding, a solid-phase welding technology, involves the following process: the workpieces to be welded are secured to the spindle and tailstock, respectively. When the spindle speed reaches the set value, the spindle's drive motor separates from the spindle, and the tailstock, driven by a hydraulic servo, moves toward the spindle. Frictional heat is generated at the contact interface, and friction gradually raises the material temperature, causing plastic deformation at the weld interface. The weld is then welded under the action of the forging pressure, which simultaneously consumes flywheel energy and attenuates the workpiece's rotational speed. When the spindle speed drops to zero, the forging pressure is maintained for a specified period, completing the weld and allowing the tailstock to withdraw.

[0003] Inertia friction welding technology is widely used in the connection of similar or dissimilar materials in aircraft engine rotor components (such as discs, drums, and turbine shafts). However, due to the differences in the thermophysical properties of dissimilar materials (such as thermal expansion coefficient and thermal conductivity), they are prone to problems such as stress concentration at the welding interface, residual oxide film, and insufficient dynamic recrystallization. In traditional processes, fusion welding methods such as electron beam welding have been gradually replaced due to their sensitivity to thermal cracks and poor compatibility with dissimilar materials. Existing inertia friction welding still has some shortcomings in the welding of dissimilar materials: First, insufficient preheating: the initial temperature gradient of dissimilar materials is large, resulting in uneven heat input during the friction stage and uncoordinated plastic deformation of the interface. Second, the oxide layer is not completely removed: oxides are easily retained at the interface of dissimilar materials, affecting metallurgical bonding. Third, the grain refinement in the upset stage is limited: it is difficult to fully promote dynamic recrystallization by relying solely on the upset force, and the mechanical properties of the joint are difficult to meet the design requirements. Fourth, the temperature will drop sharply after welding, resulting in stress concentration at the weld and unstable flash formation after welding. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a method and device for electromagnetic heating-ultrasonic wave-assisted friction welding of dissimilar materials; the specific technical solutions are as follows:

[0005] Electromagnetic heating-ultrasonic assisted dissimilar material friction welding device, including a spindle system, a tailstock system, an electromagnetic heating device and an ultrasonic loading system;

[0006] The spindle system comprises a spindle side housing, a spindle side fixture, a spindle and a spindle side flywheel;

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

[0008] The flywheel is fixed to the end journal of the main shaft through a keyway, and the motor is fixed to the outside of the main shaft side box and is coaxially connected to the main shaft to drive the main shaft to rotate; the other end of the main shaft is fixed to the main shaft side clamp, and the workpiece to be welded on the main shaft side is clamped and fixed by the main shaft side clamp;

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

[0010] The electromagnetic heating device includes a temperature control system, an annular induction coil, a thermal insulation layer, and a temperature sensor; the thermal insulation layer is coated on the outside of the annular 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 be inserted into the surface of the workpiece, and the temperature control system is electrically connected to the annular induction coil and the temperature sensor; the workpiece is heated by setting a heating temperature through the temperature control system;

[0011] The ultrasonic loading system includes an ultrasonic generator, an ultrasonic transducer, an ultrasonic horn, and an upsetting ram; the ultrasonic generator, ultrasonic transducer, and ultrasonic horn are sequentially connected and integrated inside the tailstock side fixture, the end of the ultrasonic horn is connected to the upsetting ram, and the end of the upsetting ram acts to apply high-frequency vibration to the welding interface;

[0012] The spindle side box and the tailstock slide are arranged opposite to each other so that the joint 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 joint surface temperature in real time through a temperature sensor and adjusts the heating power of the annular induction coil so that the interface temperature rises uniformly to a preset value, which is lower than the recrystallization temperature of the material.

[0014] The preferred embodiment of the electromagnetic heating-ultrasonic-assisted dissimilar material friction welding device is that, in the ultrasonic loading system, the ultrasonic generator converts the mains electricity into an ultrasonic frequency AC signal, the ultrasonic transducer converts the electrical signal into mechanical vibration, the ultrasonic horn amplifies the vibration amplitude and transmits it to the welding interface through the upset forging head.

[0015] The welding method of the electromagnetic heating-ultrasonic assisted dissimilar material friction welding device has the following steps:

[0016] The welding method of the electromagnetic heating-ultrasonic assisted dissimilar material friction welding device has the following steps:

[0017] Step 1: Workpiece clamping: Use the spindle side fixture to clamp and fix the workpiece to be welded on the spindle side, and use the tailstock side fixture to clamp and fix the workpiece to be welded on the tailstock side;

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

[0019] Step 3: Remove the induction coil: After preheating is completed, remove the annular induction coil;

[0020] Step 4, friction welding: Start the motor to drive the spindle to rotate. When the speed reaches the set value, the motor disengages and the tailstock slide moves toward the spindle side to make the two parts to be welded contact and start friction welding.

[0021] Step 5: Begin welding: Frictional heat generates and the joint surface reaches a plastic state;

[0022] Step 6, ultrasonic assistance: When the spindle stops rotating, start the ultrasonic loading system and apply high-frequency ultrasonic vibration to the welding interface through the forging head;

[0023] Step 7: Reinstall the coil and maintain pressure: Rewind the annular induction coil to the outside of the joint surface and maintain pressure;

[0024] Step 8, post-weld temperature control: Start the electromagnetic heating device and perform a step-by-step cooling of the welding area: first keep the temperature above the brittle zone temperature 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 annular induction coil, release the weldment from the tailstock side clamp, and return the tailstock slide to its initial position.

[0026] The preferred embodiment of the electromagnetic heating-ultrasonic assisted dissimilar material friction welding method is as follows: in step 2, the preheating temperature ranges from 150°C to 200°C, and the heating time is ≤10s.

[0027] The preferred embodiment of the electromagnetic heating-ultrasonic assisted dissimilar material friction welding method is as follows: in step 4, the flywheel inertia is 2500-3500 kg·m 2 , the rotation speed is 300–400rpm, and the upsetting pressure is 350–450MPa.

[0028] The welding method of the electromagnetic heating-ultrasonic-assisted dissimilar material friction welding device is preferably 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 interface oxide layer and promote dynamic recrystallization.

[0029] The preferred embodiment of the electromagnetic heating-ultrasonic assisted dissimilar material friction welding method is as follows: in step eight, the step-by-step cooling is specifically as follows: the weld temperature is maintained above the brittle zone temperature of the material during the insulation stage, and then cooled to room temperature in stages at a rate of 50-150°C per 5 minutes.

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

[0031] Compared to existing inertia friction welding methods and devices for dissimilar materials, this technical solution solves the problem of insufficient preheating during inertia friction welding, which leads to large initial temperature gradients, uneven heat input, and inconsistent plastic deformation at the interface. It thoroughly removes the oxide layer, reducing metallurgical bonding defects between the dissimilar materials. It also promotes dynamic recrystallization of grains during the upset forging phase, improving the mechanical properties of the joint. The temperature gradually decreases after welding, reducing stress concentration in the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the structure of the inertia friction welding device for dissimilar materials assisted by electromagnetic heating and ultrasonic waves;

[0033] Figure 2 Schematic diagram of the structure of the electromagnetic heating device;

[0034] Figure 3 Schematic diagram of the ultrasonic loading system structure.

[0035] In the figure: 1-spindle side box, 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 fixed seat, 10-tailstock side fixture, 11-tailstock side workpiece to be welded, 12-temperature control system, 13-annular induction coil, 14-thermal insulation layer, 15-temperature sensor, 16-ultrasonic generator, 17-ultrasonic transducer, 18-ultrasonic horn, 19-upsetting ram, 20-ultrasonic loading system. DETAILED DESCRIPTION

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

[0037] An electromagnetic heating-ultrasonic assisted dissimilar material friction welding device comprises a spindle system, a tailstock system, an electromagnetic heating device 7 and an ultrasonic loading system 20;

[0038] The spindle system comprises a spindle side housing 1, a spindle side fixture 3, a spindle 4 and a spindle side flywheel 5;

[0039] The spindle side box body 1 is fixedly installed on the left reference surface of the bed; the spindle 4 horizontally passes through the inside of the spindle side box body 1;

[0040] The flywheel 5 is fixed to the end journal of the main shaft 4 through a keyway. The motor 2 is fixed to the outside of the main shaft housing 1 and is 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 to the main shaft fixture 3, and the main shaft side welded workpiece 6 is clamped and fixed by the main shaft fixture 3.

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

[0042] The electromagnetic heating device 7 includes a temperature control system 12, an annular induction coil 13, a heat insulation layer 14, and a temperature sensor 15; the heat insulation layer 14 is coated on the outside of the annular induction coil 13 and 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 be inserted into the surface of the workpiece, and the temperature control system 12 is electrically connected to the annular induction coil 13 and the temperature sensor 15; the workpiece is heated by setting the heating temperature through the temperature control system;

[0043] The ultrasonic loading system includes an ultrasonic generator 16, an ultrasonic transducer 17, an ultrasonic horn 18, and an upset forging head 19; the ultrasonic generator 16, the ultrasonic transducer 17, and the ultrasonic horn 18 are sequentially connected and integrated inside the tailstock side fixture 10, and the end of the ultrasonic horn 18 is connected to the upset forging head 19, and the end of the upset forging head 19 acts to apply high-frequency vibration to the welding interface;

[0044] The spindle side housing 1 and the tailstock slide 8 are arranged opposite to each other so that the joint surfaces of the spindle side workpiece 6 to be welded and the tailstock side workpiece 11 to be welded are aligned.

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

[0046] The electromagnetic heating-ultrasonic-assisted friction welding device for dissimilar materials has a preferred embodiment in which, in the ultrasonic loading system, the ultrasonic generator 16 converts the mains electricity into an ultrasonic frequency AC signal, the ultrasonic transducer 17 converts the electrical signal into mechanical vibration, and the ultrasonic horn 18 amplifies the vibration amplitude and transmits it to the welding interface through the forging head 19.

[0047] Example 1

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

[0049] Step 1: Workpiece clamping: Use the spindle side fixture 3 to clamp and fix the TC4 weldment, and use the tailstock side fixture 10 to clamp and fix the IN718 weldment;

[0050] Step 2: Electromagnetic preheating: Wrap an annular induction coil 13 around the outside of the joint surface of the TC4 weldment and the IN718 weldment, start the electromagnetic heating device 7, set the electromagnetic coil frequency to 10 kHz, set the TC4 preheating temperature parameters to 150°C and the heating time to ≤10 seconds; set the IN718 preheating temperature parameters to 200°C and the heating time to ≤10 seconds; the temperature sensor 15 monitors in real time, and the temperature control system 12 dynamically adjusts the power to ensure that the temperature is uniform and below the recrystallization temperature of the material;

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

[0052] Step 4, friction welding: start motor 2 to drive spindle 4 to rotate TC4 weldment to the set speed of 350rpm; the motor is disengaged, and the inertia of flywheel 5 is 3000kg·m 2 , maintain rotation; the tailstock slide 8 drives the IN718 weldment to move toward the spindle side box 1, so that the two workpieces contact; the joint surfaces of the TC4 weldment and the IN718 weldment contact and start friction welding, applying a forging pressure of 400MPa;

[0053] Step 5: Begin welding: Frictional heat generates and the joint surface reaches a plastic state;

[0054] Step 6, ultrasonic assistance: When the spindle 4 stops rotating, start the ultrasonic loading system; the forging head 19 applies vibration to the welding interface at a frequency of 30kHz, an amplitude of 20μm, and a duration of 3s to break the interface oxide layer and promote dynamic recrystallization;

[0055] Step 7, coil reassembly and pressure maintenance: the annular induction coil 13 is rewound around the outside of the joint surface and pressure maintained for 60 seconds;

[0056] Step 8, post-weld temperature control: start the electromagnetic heating device 7 and perform step-by-step cooling: 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, disassembling the workpiece: After welding is completed, remove the induction coil 13; loosen the tailstock side clamp 10; and return the tailstock slide 8 to its initial position.

Claims

1. 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 comprises a spindle side housing (1), a spindle side fixture (3), a spindle (4) and a spindle side flywheel (5); The spindle side box (1) is fixedly mounted on the left reference surface of the bed; the spindle (4) horizontally passes through the interior of the spindle side box (1); The flywheel (5) is fixed to the end journal of the main shaft (4) through a keyway, and the motor (2) is fixed to the outside of the main shaft side housing (1) and is 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 to the main shaft side fixture (3), and the main shaft side welded part (6) is clamped and fixed by the main shaft side fixture (3); The tailstock system comprises a tailstock slide (8) mounted on the other side of the bed via a movable slide rail, the tailstock slide (8) being mounted in the movable slide box via a tailstock fixing seat (9), a tailstock side clamp (10) being mounted on the tailstock fixing seat (9), and a workpiece to be welded (11) on the tailstock side being clamped and fixed by the tailstock side clamp (10); The electromagnetic heating device (7) comprises a temperature control system (12), an annular induction coil (13), a heat insulation layer (14), and a temperature sensor (15); the heat insulation layer (14) is coated on the outside of the annular 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 be inserted into the surface of the workpiece, and the temperature control system (12) is electrically connected to the annular induction coil (13) and the temperature sensor (15); the workpiece is heated by setting a heating temperature through the temperature control system; The ultrasonic loading system comprises an ultrasonic generator (16), an ultrasonic transducer (17), an ultrasonic horn (18), and an upsetting ram (19); the ultrasonic generator (16), the ultrasonic transducer (17), and the ultrasonic horn (18) are sequentially connected and integrated inside the tailstock side fixture (10); the end of the ultrasonic horn (18) is connected to the upsetting ram (19); and the end of the upsetting ram (19) acts to apply high-frequency vibration to the welding interface; The spindle side box (1) and the tailstock slide (8) are arranged relative to each other so that the joining surfaces of the spindle side part to be welded (6) and the tailstock side part to be welded (11) are aligned.

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

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

4. The welding method of the electromagnetic heating-ultrasonic assisted dissimilar material friction welding device according to any one of claims 1 to 3, characterized in that: The welding steps are as follows: Step 1: clamping the workpiece: clamping and fixing the workpiece to be welded (6) on the spindle side by the spindle side clamp (5), and clamping and fixing the workpiece to be welded (9) on the tailstock side by the tailstock side clamp (8); Step 2, electromagnetic preheating: winding a ring-shaped induction coil (13) around the outer side of the joint surface between the spindle side workpiece (6) and the tailstock side workpiece (11), starting the electromagnetic heating device (7), and setting the preheating temperature through the temperature control system (12) so that the joint surface temperature is uniformly raised to a preset value and lower than the recrystallization temperature of the material; Step 3: Remove the induction coil: After preheating is completed, remove the annular induction coil (13); Step 4, friction welding: start the motor (3) to drive the spindle (4) to rotate, and when the speed reaches the set value, the motor is disengaged, and the tailstock slide (8) moves toward the spindle side, so that the two parts to be welded contact and friction welding begins; Step 5: Begin welding: Frictional heat generates and the joint surface reaches a plastic state; Step 6, ultrasonic assistance: when the main shaft stops rotating, start the ultrasonic loading system and apply high-frequency ultrasonic vibration to the welding interface through the forging head (17); Step 7, coil reassembly and pressure maintenance: rewind the annular induction coil (10) to the outside of the joint surface and maintain the pressure; Step 8, post-weld temperature control: start the electromagnetic heating device (7) and perform step-by-step cooling of the welding area: first keep the temperature above the brittle zone temperature of the material, and then cool it down to room temperature in a step-by-step manner; Step 9: Dismantle the workpiece: remove the annular induction coil (10), release the weldment from the tailstock side fixture, and return the tailstock slide (8) to its initial position.

5. The welding method of the electromagnetic heating-ultrasonic assisted dissimilar material friction welding device according to claim 4, characterized in that: In step 2, the preheating temperature ranges from 150° C. to 200° C., and the heating time is ≤10 s.

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

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

8. The welding method of the electromagnetic heating-ultrasonic assisted dissimilar material friction welding device according to claim 4, characterized in that: In step eight, the step-by-step cooling is as follows: during the insulation stage, the weld temperature is maintained above the temperature of the brittle zone of the material, and then the weld is cooled to room temperature in stages at a rate of 50-150°C per 5 minutes.

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