High-frequency ultrasonic online monitoring method for internal defects of metal movable molten pool

Abstract

The invention discloses a high-frequency ultrasonic online monitoring method for internal defects of a metal movable molten pool. The high-frequency ultrasonic online monitoring method comprises the following steps: providing N focusing points of different depths along the center line of the molten pool, obtaining the emission angle thetas of an ultrasonic beam according to the relationship between the focusing points and an incident point in order to obtain N groups of fiber array delay rules corresponding to the focusing points of all angles; exciting a laser according to a delay rule corresponding a first focusing point F1 to realize the incidence of the ultrasonic beam focused at a point N1, and sampling; replacing the delay rule, and exciting the laser according to a delay rule corresponding to a next focusing point F2; repeating the previous steps to finally obtain signals of all focusing points Fi; when a spray nozzle moves to a next position, repeating the previous data acquisition and storage step; starting to analyze data of M positions collected on a straight line; performing drawing analysis on a two-dimension matrix, wherein one or more crescentic ultrasonic signals, namely, diffraction signals of slag inclusion or pores are found in an image rating range.

Description

technical field [0001] The invention belongs to the technical field of on-line monitoring of additive manufacturing, and in particular relates to a high-frequency ultrasonic on-line monitoring method for internal defects of a metal moving molten pool. Background technique [0002] Direct Energy Deposition (DED) technology is the mainstream method of metal additive manufacturing. Through heat sources such as lasers, plasmas, and electron beams, a molten pool is generated in the deposition area and moves at a high speed to melt the material powder or wire that is fed synchronously. Layer-by-layer deposition enables net near-shaping of parts with arbitrary complex shapes. However, due to factors such as unreasonable manufacturing process design, long-term operation stability of equipment, and external environment, metal additive parts inevitably have process defects, which restrict the development and application of metal additive manufacturing technology. [0003] At home and...

AI Technical Summary

Problems solved by technology

However, the monitoring of the internal quality of the molten pool is the key to achieving high-quality printing. Typical defects such as pores, cracks, and unmelted are mostly produced during melting and solidification; the flow state inside the molten pool and the liquid-solid interface transition during melting and solidification closely related to printing parameters

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