| 摘要 |
PURPOSE:To prevent heat by a simple mechanism from being transmitted to a machine body, by forming helical grooves in the outer circumferential surface of a main unit, and allowing a cooling medium to pass through the helical groove. CONSTITUTION:In a case a selected drill 10a of the main units 4a-4d is used, by lowering a lifting mechanism through a drive unit 2 the main unit 4a, that is, a bearing case 6a, in a slide hole 3a is lowered. When a driving unit 5a is actuated, the drill 10a is rotated through a straight spline shaft 13a. The high pressure air pumped from an air pump 23 is led via a dispenser 22 into a feed hole 19, and is allowed to flow into the helical groove 17, and then to the top of the groove 17, and after it reaches a ring groove 21, it flows into the other helical groove 18a, and is discharged through a discharge hole 20. Accordingly, by the thus flowing air, the heat that will be generated by the sliding of the bearing cases 6a-6d in the holes 3a-3d can be effectively suppressed. |
