| 摘要 |
PURPOSE:To eliminate the danger of damage and degrading of the surface of a steel pipe in polishing the surface by making the surface in the peripheral direction as well as the axial direction smooth curvature through the movement in the radial direction of a rotary grindstone and oscillations of a specified radius of curvature thereof and through the movement in the axial direction of a steel pipe to be machined. CONSTITUTION:An ascending/descending base 5 descends together with a grindstone support 6 to a steel pipe 1 to be machined which is arranged on a turning roller 2, and the polishing peripheral face of a rotary grindstone 18 is brought into contact with the steel pipe 1, then grinding is started. At the same time under the condition that the grindstone 18 is brought into pressure-contact with the surface of the steel pipe 1, an oscillation motor 14 gives oscillations of a specified angle in the radial direction to the grindstone support 6 so that flaws on the surface of the steel pipe 1 is polished or ground. In this case, as the oscillating center of the support 6 is on the radial line pependicularly below the center of the minimum radius of the steel pipe 1, the oscillating radius of the grindstone 18 is larger than the radius curvature of the steel pipe 1. Therefore, there is no possibility of partial polishing, and smooth polishing along the peripheral face of the steel pipe 1 is thus attained. Further, for the peripheral face of the steel pipe 1 in the axial direction, it is sequentially polished in order to put the flaws in the deepest lever by controlling the feeding, advancing and returning actions of the steel pipe 1 and the pressuring force applied thereto. |
