TOOL ABNORMALITY DETECTION DEVICE AND NUMERICAL CONTROL DEVICE FURNISHED WITH IT

摘要

PROBLEM TO BE SOLVED: To discriminate tool abnormality with a threshold value set constant concerning a cutting load even in the case of working feeding speed of which changes every moment. SOLUTION: This device is provided with a cutting load detection means 8 to detect a cutting load in accordance with a driving electric current to be output to a feeding driving system 14 and/or a driving electric current to be output to a main spindle system 15, a feeding load estimating means 12 to assume a feeding load depending on feeding speed in accordance with the feeding speed, a tool load detection means 11 to extract a load component depending on a tool by removing a feeding load data estimated by the feeding load estimating means 12 from a cutting load data detected by the cutting load detection means 8 and an abnormality judgment means 13 to judge whether the tool is abnormal or not in accordance with a load data extracted by the tool load detection means 11. Consequently, as it is based on the tool load provided by removing the feeding load fluctuating in accordance with the feeding speed, it is possible to judge tool abnormality by a threshold value set constant.