TEST CYCLE CALIBRATION SYSTEM FOR ROCKWELL HARDNESS TESTER

摘要

The direct verification of Rockwell testing machines comprises four parts such as test force, indenter, depth measuring device, and testing cycle as seen in ISO 6508-2. Among them, the verification of testing cycle is generally carried out by using a stopwatch on industrial sites, which is not so reliable. In addition to this, most of commercial hardness testing machines produced nowadays are automatically controlled by the embedded software, which makes it much more difficult to calibrate the testing cycle. It implies that even though hardness testing machines are advanced more, the calibration of the testing cycle does not keep up with their advancement. To overcome this problem, an on-site calibration system was developed to calibrate the testing cycle of both the automatically controlled as well as manually controlled Rockwell hardness testing machines. The calibration system is composed of load cell, indentation depth measuring apparatus and embedded clock. Using this system, measurement of test force, application velocity of test force, and indentation depth are possible simultaneously in real time, which enhances the efficiency and reliability of calibration procedure.