| 摘要 |
PURPOSE:To stabilize a coating state by measuring >=2 wavelengths or the reflection factor of the surface of a strip in the wavelength ranges after coating baking and detecting the baking state of a coating film from >=2 reflection factors. CONSTITUTION:The plate temperature set value of a plate temperature control circuit 18 is made constant and a baking furnace 14 is brought under feedback control accord ing to the temperature measurement result of the strip 10 by a plate thermometer 16. The reflection factor measurement result obtained by a reflection factor measuring instrument 24, on the other hand, is processed by a computing element 26 for every wavelength to calculate values a* and b*. Then, it is decided by a comparator 32 whether they are within a reference range or not and when it is decided that they are not within the range, a plate temperature setting change command is outputted to the circuit 18 according to the current baking state. Further, a film thickness gauge 30 is provided on the output side of the furnace 14 and the thickness of the coating film detected by the film thickness gauge 30 is inputted to the comparator 32 to vary the reference range of the values a* and b*, so the influence of the film thickness upon the values a* and b* is canceled and the coating state is detected with high precision. |
