Thermomultiplying ruler shear precision optimizing method for bar production

The present invention relates to a thermal multiple-length shearing accuracy optimization method in production of rod material, belengting to the field of pressure processing technology for raising rod material shearing accuracy. Said invention uses two rotating speed pulse coders and two hot-metal detectors as speed-measuring sensor and uses a programmable controller as speed-measuring controller. Its optimization method includes the following steps: firstly, utilizing shearing point of thermal multiple length shears and two hot-metal detectors after shearing operation to detect out the line speed of every thermal multiple length steel; then utilizing sail line speed to calculate the 'virtual roll diameter' value which can be used to reach said line speed under the rotating speed of said finished product rolling mill; transferring the 'virtual roll diameter' value into tength-measuring program and substituting original inputted roll diameter value; after every shearing operation repeating the above-mentioned steps. The invented shearing accuracy can be up to plus or minus 50mm.