| 摘要 |
PROBLEM TO BE SOLVED: To provide an abrasion member for a drilling unit, formed with reducing faces of an action part and a fitting part in order to minimize resistance related to drilling operation and minimize a driving source required to drive the drilling unit.SOLUTION: An abrasion assembly 10 for a drilling unit comprises a base 12 fixed to the drilling unit, an abrasion member 14 fitted to the base, and a lock 16 for detachably fixing the abrasion member to the base. The abrasion member includes reduced faces for reducing resistance of the unit. Each of the abrasion member and the base includes a hemispherical front end and a trapezoidal rear end. The base includes a nose 18 and a stop projecting from the nose 18, and cooperates with the lock without having an opening required to receive the lock in the nose. The lock has an elongated shape arranged substantially in an axial direction and holding the abrasion member on the base by a compression pressure. |
