Study on some Effects on Shore Hardness Number : (6th Report) On the Distance between Impact Indentations

Abstract

In this report, the effect of the distance between impact indentations of the diamond hammer of the Shore scleroscope on hardness number was investigated. The experiment was carried out with a Shore scleroscope of D-type and many specimens which were different in hardness or in material. It scarcely need be mentioned that the general requests for testing were satisfied in this experiment. Especially operating conditions of the tester were carefully maintained constant throughout this experiment without being effected by the speed of the operating handle and the force, with which the specimen is pressed. As a result, the effect of the distance between impact indentations on hardness number was made clear. That is, under sufficient pressing force to the specimen, this influence is put in order by the diameter of impact indentation of the hammer generally. Hardness number is not influenced by the neighbouring indentation close up to a half of the diameter of the indentation. Nevertheless, in pratical measuring, it is desirable to measure at a point apart from other indentation as long as possible, and to check the indentation after measuring when measuring is done at a point near to the neighbouring indentations. And also, changing behaviour of hardness number when measuring was repeated at the same point was represented in this report.