歯科用切削工具の切削性に関する研究 (第3報)

Abstract

The life of machinability of commercial round type burs produced in Japan, Germany, America and Denmark were measured by vertical drilling methylmethacryllic resin blocks and aluminium: alloy plate reciprocally. Aluminium alloy plate has the Rockwell hardness number 84.0 to 88.2 in B; scale and 3 mm thickness.From results of this work, this report might be concluded as follows.1. Relation between thrust (T) and number of drilling of Al-alloy plates (N) is classified as follows.i) The more N increases, the more T increases gradually.ii) As N increases, T increases extremely periodically. This type burs' lives are bad.iii) T increases parabolically as N increases. This type burs indicate not so good lives.2. From the minimum N giving be the product of initial thrust Ti and arbitrary constant K, the degree of fall of machinability can be compared with.3. From the microscopic inspection, the form of blades are classified as follows, i) No changes are observed.ii) Dull of the edges are observed partially.iii) Dull and wear of the blades and edges are observed in all.4. There is no relation between the initial thrust and life.