EVALUATION METHOD OF COPPER ALLOY AND COPPER ALLOY FOR BEARING CAGE

摘要

PROBLEM TO BE SOLVED: To provide a copper alloy for a bearing cage ensuring the existence number of internal defects and an evaluation method of it.;SOLUTION: Ultrasonic flaw detection using an angle beam method is used for detecting internal defects. Therefore, a round bar 11 formed of copper alloy for a bearing cage as an evaluation object and an ultrasonic probe 12 are dipped in a water tank 13 as an ultrasonic transmit medium to perform ultrasonic flaw detection using the angle beam method. The angle beam method is suitable for detecting a smaller internal defect. The flaw detection frequency of the ultrasonic flaw detection is set to 20 MHz or less, whereby the depth of flaw detection can be increased and the flaw detection time can be shortened. The size of the internal defect is set to square root length of 0.4 mm or more, whereby the detection can be facilitated and the threshold level can be easily obtained. The existence ensuring of internal defects is 10.0 pieces or less per flaw detection volume of 1×10⁶ mm³.;COPYRIGHT: (C)2004,JPO