A Quantitative Ultrasonic Nondestructive Testing Method for Spot Welding Nugget Diameter

Abstract

The invention discloses a quantification ultrasonic nondestructive detection method of a diameter of a spot weld nugget. The quantification ultrasonic nondestructive detection method of the diameter of the spot weld nugget includes the steps that step 1, a transmitting probe and a receiving probe are installed on the two sides of the spot weld nugget of a spot weld sample; step 2, a relation curve of amplitude B and a displacement x is drawn; step 3, an actual nugget diameter is measured; step 4, a straight line is made in the relation curve, the difference of two horizontal coordinates of the cut curve is the sum of the actual nugget diameter and the effective diameter of the receiving probe, and a corresponding B0 value of the current vertical coordinate of the straight line is recoded and stored; step 5, the transmitting probe and the receiving probe are installed on the two sides of the spot weld nugget of an actual welding spot to be detected, when the receiving probe receives that the amplitude B reaches the B0 for the first time, a displacement Xa is recorded, when the receiving probe receives that the amplitude B reaches the B0 for the second time, a displacement Xb is recorded, Xt=Xb-Xa, and the diameter of the spot weld nugget of the actual welding spot to be detected is Xt-dmin. The quantification ultrasonic nondestructive detection method of the diameter of the spot weld nugget quantitatively detects the nugget diameter of the resistance spot welding quickly and accurately and visually reflects the welding spot quality.

Description

technical field [0001] The invention specifically relates to a quantitative ultrasonic non-destructive testing method for spot welding nugget diameters, which is an ultrasonic nondestructive testing method suitable for spot welding nugget diameters of various metal plates and plate thicknesses, and can accurately measure metal plates The size of the spot welding nugget diameter. Background technique [0002] Resistance spot welding is one of the welding processes widely used in modern industrial manufacturing, especially in the process of automobile body manufacturing. Therefore, ensuring the quality of spot welding has become the key to the quality of automobile body assembly and control of body errors. The quality of the solder joint is characterized by the strength of the solder joint, and the strength of the solder joint mainly depends on the geometry of the solder joint. Experiments have shown that the diameter of the nugget is approximately proportional to the strengt...

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Problems solved by technology

[0003] At present, the inspection of solder joint quality by domestic OEMs is mainly realized by means of destructive sampling inspection. The effect is lagging, time-consuming, high cost, and much waste. Therefore, non-destructive testing technology is urgently hoped to be introduced into the inspection of solder joint quality.

The existing non-destructive testing technology of spot welding nugget diameter generally sets a standard curve first, and then compares the actual detected ultrasonic signal amplitude ratio with the set standard curve. When the nugget diameter is smaller than the set standard value , to determine whether the quality of the solder joint is unqualified. This method can directly reflect whether the quality of the solder joint is qualified or not. However, this method is only qualitative but not quantitative, and cannot quickly and accurately give an accurate measurement of the nugget diameter.

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