| 摘要 |
PURPOSE:To keep the accuracy of a table from being infuenced by ascillation of a shaft caused by rotation of a male screw and an error in screw machining accuracy by reducing the radial rigidity of a feed screw device. CONSTITUTION:Through air supplied from an air feed groove 5 is about to be jetted from the whole surface of a female screw 2 formed by prous material, filling-up 6 material is applied to the surface 2b of the valey diameter portion and the surface 2e of the inside diameter portion so that the air is not jetted to produce no radial rigidity due to air jetting. The air jetted from the flank surface 2c of the female screw increases the pressure in a gap 7, and then flows into gas 8, 9. Though the pressure in the gaps 8, 9 is about to increase, the gaps 8, 9 are about 0.5-1mm., so that the pressure will not increase. Accordingly, even if radial rigidity is produced, it is a very small amount. Thus, changes in interval of the gaps 8, 9 caused by oscillation of a shaft of a male screw or an error in machining the form of the screw in case of rotating a male screw 1 will not have an effect upon the accuracy of a table. |
