The Development Of Optical Outer Diameter Gauge For Digital Wire Manufacture On Line Measurement With Laser And CCD Technology

The uniformity of digital cable core insulation diameter is one of the important factors influencing the transmission capability. It is necessary for quality control of the digital cable core production line to measure the core insulation diameter precisely on-line. With the increasing of digital cable transmission frequency, SRL (structural return loss) on-line evaluation using diameter data of digital cable core became a method of cable quality control. Higher measuring precision and higher measuring speed of the diameter gauge was required. In this paper, all kinds of diameter gauge were reviewed through extensive reading of the technical papers and reports. An optical diameter gauge using CCD with high speed and high precisely was designed.The relationship between periodical fluctuation of the core diameter and SRL was analyzed. The method predicting SRL using core diameter data FFT transform was found.The formula by shadow's length and shadow's position of two vertical directions to calculate core diameter was found. By means of formula modification, the calculation error was below 10-2μm. Formula itself and the modification arithmetic were suitable for single chip to process.The high speed A/D and DMA system was designed and debugged. The straight line fitting on the data of the shadow edge was introduced, through which the precision of the measuring system was enhanced. Three single chip processors were used simultaneously to acquire, handle, and calculate the data. The measuring speed was enhanced through predicting the edge position by hardware circuit.Because energy of laser can be focused, the exposure time can be decreased to micron second level, the error brought by wire liberation was reduced. Without lens, the scattering pattern caused by the dust particles contamination on the lens surface was avoided.