An ever-present challenge in hot rolling operations is to ensure that the material being produced conforms to required dimensional specifications. Rather than contact-based measurement, it is preferred to measure the material optically from a standoff position.
In some instances, this has been accomplished using two ganged analog optical lasers, each detecting opposite sides of the material being measured. Through mathematical subtraction, the difference representing thickness could be determined. One difficulty of the approach is the need to put a sensor both above and below the material under inspection. The sensor mounted below could be subjected to falling dirt and debris. Further, only a single point on the surface could be measured.
A new approach uses a scanning laser to create a band of light that is used to directly measure the thickness of the material. An analog or digital IO-Link signal represents the measured thickness to a resolution of 0.01mm with a repeat accuracy between 10μm to 40μm depending on distance between emitter and receiver. What’s more, the measurement can be taken even on red-hot metals. The illustration above shows a flat slab but the concept works equally well or better on products with a round profile.
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