1.What are the detection principles and capabilities of machine vision surface inspection systems?
Principle: High-speed linear/area array cameras are installed at key locations on the production line (e.g., after finishing rolling, before oiling) and paired with a high-brightness, uniform light source to continuously scan and image the strip surface. AI algorithms analyze the images in real time, identifying the grayscale, shape, and texture features of the stripes.
Detection Capabilities:
Bright/Dark Stripes: Differences in light reflection caused by uneven roughness or slight thickness variations.
Roll Marks (Periodic Stripes): Equally spaced defects caused by roll damage.
Scratches: Longitudinal linear defects.
Advantages: 100% full coverage, real-time alarm, automatic classification, precise marking of positions (coil length and width directions), and real-time process or sorting adjustment through linkage with the production system.
Representative Systems: Professional strip surface inspection systems provided by ISRA VISION, Cognex, Baosteel Technology, etc.
2.What are the principles and capabilities of laser profilometers/roughness testers?
Principle: Utilizing laser triangulation or confocal chromatography, this non-contact method measures the three-dimensional morphology and roughness (Ra value) of the strip surface.
Detection Capability: Specifically designed to detect microscopic roughness streaks that are difficult to detect with the naked eye due to roll wear or vibration. It can plot roughness distribution curves along the width direction, visually displaying the location and amplitude of the streaks.
Advantages: Quantitative measurement, crucial for research analysis and process optimization.
3.What are the testing principles and capabilities of plate shape gauges and thickness gauges?
Principle: Although primarily measuring macroscopic shape, high-precision instruments can indirectly reflect the causes of certain stripes.
Detection Capability: Fine thickness stripes (≤1%) caused by rolling force fluctuations or uneven cooling may appear as bright or dark stripes. The strip shape analyzer can detect periodic tension fluctuations related to the rolls.
4.What is the function of a surface roughness and morphology analyzer?
Equipment: Contact roughness meter (e.g., Taylor Hobson), white light interferometer, atomic force microscope (AFM).
Purpose: To measure the surface roughness at both fringe and non-fringe locations, obtaining precise comparisons of parameters such as Ra, Rz, and Rpc to quantify differences. This is crucial for determining whether the fringe is an "appearance issue" or a "functional issue" (such as affecting coating).
5.What is the role of microstructure and composition analysis?
Equipment: Metallurgical microscope, scanning electron microscope (SEM) combined with energy dispersive spectroscopy (EDS).
Functions:
To determine if there are oxide streaks: by observing the thickness and composition of the surface oxide film.
To determine if there are structural streaks: martensite/bainite bands caused by differences in local cooling rates (common in advanced high-strength steels).
To determine if there is foreign matter intrusion: by analyzing whether there are foreign elements (such as Al, Ca, Si, etc.) at the streaks.