| 摘要 |
PROBLEM TO BE SOLVED: To measure the hardness of a sample with high accuracy without measuring the speed of a hammer just before and just after the collision of the hammer by a method wherein the speed of a collision stroke in a first hammer-speed measuring point which is separated by a prescribed distance from the sample is measured, the speed of a collision stroke and that of a repulsion stroke in a second hammer-speed measuring point which is separated by a prescribed distance from the sample are measured and the hardness is computed by using a specific expression. SOLUTION: In a rebound-type hardness testing apparatus, a hammer 1 is made to collide with a sample 2, and the hardness of the sample is measured. In the rebound-type hardness testing apparatus, a second hammer-speed measuring point 12 is situated in a part which is by a distance of x1 lower than a first hammer-speed measuring point 11, the sample 2 is situated in a part which is lower than the second measuring point 12, and the distance between the first measuring point 11 and the sample 2 is designated as x2 . The speed v0 of the collision stroke of the hammer 1 in the first measuring point 11 as well as the the speed v1 of the collision stroke and the speed v1 ' of the repulsion stroke of the hammer in the second measuring point are measured, and the hardness H of the sample is computed by using Expression I [where (k) represents a factor, andαrepresents an acceleration which is computed by Expression II and which acts on the hammer]. When the testing machine is tilted with reference to the vertical direction, the acceleration which acts on the hammer is corrected, and the measuring accuracy of the testing machine can be enhanced.
|
