The basic principle, internal defects detection method of ultrasonic testing for thin copper bar

1. System skill requirements

(1) Detection speed: less than 10 meters per hour

(2) Detection range: diameter 2.5mm ~ Ф 15mm

(3) Detection mode: ultrasonic automatic detection

(4) The accuracy rate of qualitative identification is 80%, 0.5mm artificial hole is detected

2. Working principle of metal rod system with length of 1.5m ~ 5m

2.1 internal defects detection methods of thin copper strip

The production process of fine copper bar mainly includes two processes. The thick copper strip is formed by liquid copper, the thin copper strip is formed by stretching. In both processes, there are the following main disadvantages in the thin copper rod.

(1) Shrinkage rate

When the molten metal is injected into the rod-shaped film, it starts the bottom side, gradually crystallizes upward toward the center to condense. The volume of the solidified metal is slightly smaller than that of the liquid metal, so the shrinkage cavity will occur in the process of condensation, because the center of the copper bar is the metal that will eventually condense, the larger part of the shrinkage cavity is the cavity formed when it is depressed. The metal liquid is enough to make the rod-shaped membrane overflow continuously, it will form shrinkage cavity after stretching, which has become a potential life-threatening defect affects the function of copper rod.

(2) Crack

The shortening of the copper bath during condensation cooling can cause large surface internal stresses, may cause cracks. Assuming that the crack is inside does enter the air, it can be welded in tension without breaking. If the crack opening is oxidized in air, it cannot be welded exists in the workpiece. The main factors of copper bar workpiece cracking.

(3) Stomata

When molten copper is injected into the rod-shaped film begins to condense, gas is released. When the gas is trapped by the copper rod in the form of bubbles, a hole is formed in the copper rod, the surface of the hole is oxidized to have an oxide film. During the drawing process, a flat hole layer may be formed, which affects the mechanical function of the copper bar.

2.2 overview of detection methods

Ultrasonic testing usually allocates the interaction between the ultrasonic wave the specimen, studies the reflected, transmitted scattered sound waves, performs micro defect detection, measures the characteristic characteristics, arranges the detection characterization of structural mechanical function changes. Review the specific applicability of skills.