Patent ID: 7771145
Filing Date: 2010-08-10
Classification: B23B,Y10S,Y10T

Abstract:
1. A method for machining a deep hole in a workpiece by means of a machine tool having a gun drill mounted to a spindle, said method comprising: connecting a coolant supply system to the spindle, the system comprising a spindle normal pressure coolant supply line for supplying a coolant at a normal pressure to a coolant passage passing in the interior of the spindle and extending to the tip of the gun drill, an external normal pressure coolant supply line for supplying a coolant at a normal pressure to a nozzle provided outside the spindle, and a high-pressure coolant supply line which joins the coolant passage in the spindle and supplies a coolant, whose pressure is higher than the normal pressure, to the coolant passage; feeding the spindle to a deep hole machining start position while jetting the coolant toward the workpiece from the external normal pressure coolant supply line; closing the external normal pressure coolant supply line and opening the spindle normal pressure coolant supply line at the start of machining of the deep hole, and machining the deep hole to a predetermined intermediate depth while supplying the coolant to a machining point; and closing the spindle normal pressure coolant supply line and opening the high-pressure coolant supply line when the depth of the hole machined has reached the intermediate depth, and machining the deep hole to the final depth while supplying the high-pressure coolant to a machining point.