Spot welding technological method for aluminum alloy workpiece

Abstract

The invention discloses a spot welding technological method for an aluminum alloy workpiece. The spot welding technological method comprises the following steps: pretreating the aluminum alloy workpiece to be subjected to spot welding; welding the pretreated aluminum alloy workpiece under the current of 15.2 KA and the pressure of 5.0 KN for 120 ms; then adjusting the welding current to 25.5 KA and the welding pressure to 4.2 KN, and welding the workpiece under the current and the pressure for 430 ms; further adjusting the welding current to 18 KA and the pressure to 6.7 KN, and welding the workpiece under the current and the pressure for 280 ms; naturally cooling the welded workpiece in air. According to the method disclosed by the invention, no splashing is generated in the welding process, and the diameter of a welded nugget can be greater than or equal to 6 mm, and the shear strength of the nugget is 0 to 5.4 KN; the surface hardness of the nugget is 0 to 50 HV; no obvious indentions are formed on the surface of the welded workpiece, and the offset of the nugget is extremely small (0 micron to 1 mm).

Description

technical field [0001] The invention relates to a spot welding process for an aluminum alloy workpiece, belonging to the field of welding technology. Background technique [0002] The aluminum element is very active, and it is very easy to form an oxide film on the surface of the aluminum alloy material. This layer of oxide film has a dense structure, a high melting point, and extremely poor electrical conductivity. It is prone to splashing and splashing, and it is easy to cause harm to personnel. Aluminum and copper alloys are easy to form a low melting point (547°C) eutectic, and the resistivity of this low melting point eutectic is relatively large, and the large heat generation on the contact surface causes local melting on the contact surface between the electrode and the workpiece, and A relatively violent eutectic reaction occurs, so that the adhesion between the electrode and the workpiece occurs, which deteriorates the surface quality of the solder joint. 2. The lo...

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Problems solved by technology

[0002] The aluminum element is very active, and it is very easy to form an oxide film on the surface of the aluminum alloy material. This layer of oxide film has a dense structure, a high melting point, and extremely poor electrical conductivity. It is prone to splashing and splashing, which is easy to cause harm to personnel.

Aluminum and copper alloys are easy to form a low melting point (547°C) eutectic, and the resistivity of this low melting point eutectic is relatively large, and the large heat generation on the contact surface causes local melting on the contact surface between the electrode and the workpiece, and A relatively violent eutectic reaction occurs, so that the adhesion between the electrode and the workpiece occurs, which deteriorates the surface quality of the solder joint

2. The local melting, splashing and adhesion of the electrode and the workpiece on the contact surface of the electrode and the workpiece destroy the continuity of the electrode surface

In the process of continuous spot welding, the discontinuity of the electrode surface has strong randomness, which makes the contact state between the electrode and the workpiece and between the workpieces very unstable.

In addition, affected by the surface state of the workpiece, electrode pressure, welding current and other factors, the nugget diameter fluctuates greatly in continuous spot welding

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