| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a master ring gauge capable of shortening a temperature adaptation time as preparation work by bringing only a bottom face of a ring gauge into direct contact with a surface of a surface plate under temperature control.SOLUTION: A protective ring 3 is disposed in an outer peripheral part of a ring gauge 1 including a reference gauge hole 2 to be a reference for various measuring instruments, and a bottom face 1a of the ring gauge protrudes from a bottom face 3a of the protective ring in such a manner that only the bottom face of the ring gauge is brought into direct contact with a surface of a surface plate under temperature control.</p> |
