Ultrasound-assisted resistance spot-welding device and method used for sheet metal materials

A resistance spot welding and ultrasonic-assisted technology, applied in the field of welding manufacturing, can solve problems such as large changes, electrode wear, and complicated devices, and achieve the effects of small ultrasonic vibration resistance, promotion of mass transfer and heat transfer, and high method adaptability.

Inactive Publication Date: 2019-07-19

INST OF METAL RESEARCH - CHINESE ACAD OF SCI

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AI-Extracted Technical Summary

Problems solved by technology

At present, there have been reports on the introduction of ultrasound into resistance spot welding: Chinese patent application number 201510096036.9, coaxial ultrasonic-assisted resistance spot welding device and method, using an annular ultrasonic tool head coaxial with the resistance spot welding electrode to achieve ultrasonic-resistance points Welding combination, the original resistance spot welding equipment has been greatly changed, which increases the complexity of the device, and the ultrasonic vibration can only be applied vertically or parallel to the workpiece to be welded

The Chinese patent with the application number 201510357883.6 is an ultrasonic-resistance hybrid welding method, which achie...

Method used

Keep the vibration of upper electrode 1 pressure and ultrasonic tool head 6, open the DC current of resistance spot welding power supply 9 output 20kA, power-on time 100ms. The contact points on the overlapping surfaces of the workpieces to be welded are melted under the action of resistance heat. At this stage, ultrasound produces cavitation and acoustic flow effects in the nugget metal, promoting heat and mass transfer in the melt.

Keep the vibration of upper electrode 1 pressure and ultrasonic tool head 6, open the DC current of resistance spot welding power supply 9 output 30kA, power-on time 150ms. The contact points on the overlapping surfaces of the workpieces to be welded are melted under the action of resistance heat. At this stage, ultrasound produces cavitation and acoustic fl...

Abstract

The invention discloses an ultrasound-assisted resistance spot-welding device and method used for sheet metal materials, and belongs to the technical field of welding manufacturing. The ultrasound-assisted resistance spot-welding device comprises a resistance spot-welding electrode and an ultrasonic tool head located on one side of the resistance spot-welding electrode. The distance from the axisof the ultrasonic tool head to the axis of the spot-welding electrode is 2-15cm. The ultrasound-assisted resistance spot-welding method comprises the steps that (1) an electrode pressure is applied toclamp a welded workpiece, and the ultrasonic tool head is closely attached to the welded workpiece through a pressurization device, and an ultrasonic generator is started; (2) a resistance spot-welding power supply is turned on to output currents to form a spot-welding nugget; (3) output of the currents is stopped, and the welded workpiece is cooled and crystallized under the combined effect of the electrode pressure and ultrasonic vibration; and (4) after output of the currents is stopped for 50-200s, the ultrasonic generator is stopped. According to the ultrasound-assisted resistance spot-welding device and method, original resistance spot-welding equipment is not changed, and ultrasounds are directly applied to the welded workpiece; and after welding, the structure of the nugget is refined, and the porosity is reduced; and high-quality spot-welding connection of lightweight metal materials such as aluminum alloy is achieved.

Application Domain

Welding apparatus

Technology Topic

Ultrasonic generatorPower flow +12

Image

Examples

Experimental program(2)
Comparison scheme(2)

Example Embodiment

[0034] Example 1

[0035] In the ultrasonic-assisted resistance spot welding device of this embodiment, the diameters of the upper electrode 1 and the lower electrode 4 are both 8 mm. The ultrasonic tool head 6 has a diameter of 5 mm, and is in contact with the workpiece at a position 10 cm away from the axis of the lower electrode 4 . The distance between the ultrasonic tool head 6 and the lower electrode 4 can effectively ensure that the ultrasonic energy acts on the nugget without interference between the ultrasonic tool head 6 and the lower electrode 4 . According to different welding materials, the end face of the ultrasonic tool head 6 can be flat or provided with patterns or micro-teeth, so as to ensure effective transmission of ultrasonic vibrations. The angle between the ultrasonic tool head 6 and the workpiece to be welded can be between 0° and 90°.

[0036] The ultrasonic generator 8 and the transducer 7 are commonly used devices in the field of ultrasonic waves, which generate resonance through the acoustic system and transmit ultrasonic vibration energy to the workpiece to be welded through the ultrasonic tool head 6 . In order to prevent the thin plate workpiece from being displaced and deformed under the pressure of the tool head, a limiting device 5 needs to be provided.

[0037] Resistance spot welding power supply 9 can select direct current, alternating current or pulse power supply for use. The resistance spot welding power supply 9 connects the upper electrode 1 and the lower electrode 4, and outputs direct current, alternating current or pulse current to them.

[0038] Use the above ultrasonic-assisted resistance spot welding device to spot weld two 2.5mm thick 5083 aluminum alloy plates. The specific operation steps are as follows:

[0039] 1) Preloading stage:

[0040] The upper electrode 1 exerts a pressure of 1.2kN on the upper plate 2 of the workpiece to be welded under the control of the pressure device Ⅰ, adjust the limit device 5 to make it contact the upper plate 2, and the ultrasonic tool head 6 exerts pressure on the welded workpiece under the control of the pressure device II. A pressure of 100N is applied to the lower plate 3 of the workpiece, so that the resistance spot welding electrode and the ultrasonic tool head are in close contact with the workpiece to be welded. Keeping the pressure of the upper electrode 1 and the ultrasonic tool head 6, turn on the ultrasonic generator 8 to make the ultrasonic tool head 6 vibrate, the ultrasonic vibration frequency is 38 kHz, and the amplitude is 50 μm.

[0041] 2) Power-on nucleation stage

[0042] Maintain the pressure of the upper electrode 1 and the vibration of the ultrasonic tool head 6, turn on the resistance spot welding power supply 9 to output a DC current of 30 kA, and the power-on time is 150 ms. The contact points on the overlapping surfaces of the workpieces to be welded are melted under the action of resistance heat. At this stage, ultrasound produces cavitation and acoustic flow effects in the nugget metal, promoting heat and mass transfer in the melt.

[0043] 3) cooling crystallization stage

[0044]Maintain the pressure of the upper electrode 1 and the vibration of the ultrasonic tool head 6, the resistance spot welding power supply 9 stops the output current, the metal in the nugget area of the workpiece to be welded is cooled and crystallized under the joint action of the electrode pressure and ultrasonic vibration, and the solidified nugget structure is refined , Porosity defects are reduced.

[0045] 4) Separation stage

[0046] After the resistance spot welding power supply 9 stops outputting the current for 100 ms, the vibration of the ultrasonic tool head 6 is stopped, the electrode pressure and the ultrasonic tool head pressure are unloaded, the workpiece to be welded is separated from the spot welding electrode and the ultrasonic tool head 6, and the spot welding process is completed. figure 2 It is the macro- and micro-morphology of the longitudinal section of the nugget in Example 1.

Example Embodiment

[0047] Example 2

[0048] In this embodiment, the same ultrasonic-assisted resistance spot welding device as in Embodiment 1 is used to spot weld two 6061 aluminum alloy plates with a thickness of 1 mm. The specific operation steps are as follows:

[0049] 1) Preloading stage:

[0050] The upper electrode 1 exerts a pressure of 1.2kN on the upper plate 2 of the workpiece to be welded under the control of the pressure device Ⅰ, adjust the limit device 5 to make it contact the upper plate 2, and the ultrasonic tool head 6 exerts pressure on the welded workpiece under the control of the pressure device II. The lower plate 3 of the part applies a pressure of 50N, so that the resistance spot welding electrode and the ultrasonic tool head are in close contact with the workpiece to be welded. Keeping the pressure of the upper resistance spot welding electrode 1 and the ultrasonic tool head 6, turn on the ultrasonic generator 8 to make the ultrasonic tool head 6 vibrate, the ultrasonic vibration frequency is 38 kHz, and the amplitude is 30 μm.

[0051] 2) Power-on nucleation stage

[0052] Maintain the pressure of the upper electrode 1 and the vibration of the ultrasonic tool head 6, turn on the resistance spot welding power supply 9 to output a DC current of 20 kA, and the power-on time is 100 ms. The contact points on the overlapping surfaces of the workpieces to be welded are melted under the action of resistance heat. At this stage, ultrasound produces cavitation and acoustic flow effects in the nugget metal, promoting heat and mass transfer in the melt.

[0053] 3) cooling crystallization stage

[0054] Maintain the pressure of the upper electrode 1 and the vibration of the ultrasonic tool head 6, the resistance spot welding power supply 9 stops the output current, the metal in the nugget area of the workpiece to be welded is cooled and crystallized under the joint action of the electrode pressure and ultrasonic vibration, and the solidified nugget structure is refined , Porosity defects are reduced.

[0055] 4) Separation stage

[0056] After the resistance spot welding power supply 9 stops outputting the current for 50 ms, stop the vibration of the ultrasonic tool head 6, unload the electrode pressure and the ultrasonic tool head pressure, separate the welded workpiece from the spot welding electrode and the ultrasonic tool head 6, and complete the spot welding process. Figure 4 It is the macro- and micro-morphology of the longitudinal section of the nugget in Example 2.

PUM

Property	Measurement	Unit
Diameter	8.0	mm

Description & Claims & Application Information

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Ultrasound-assisted resistance spot-welding device and method used for sheet metal materials

AI-Extracted Technical Summary

Problems solved by technology

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Abstract

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Examples

Example Embodiment

Example Embodiment

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Description & Claims & Application Information

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