| 摘要 |
PURPOSE: To stabilize the advanced direction of a shield device by enabling a rotor to have the rotation axis intersecting with the rotation axis of a shaft so that an element far from a conical outside surface and a rotor forward and backward central part is separated to a shield main body radial outside for the rotation axis of the shaft. CONSTITUTION: A shield device 10 is moved forward by revolving a rotor 18 around the axis 12 as the rotation axis of a shaft 16 and the axis 38 as the rotation axis of the rotor itself. The axis 38 is intersected with the axis 12 of a shaft 16 in a point P0 of the central part so that an element far from a forward and backward central part of the rotor 18 only is separated to a radial outside of a shield main body 14 for the axis 12. As a result, notwithstanding that the front end and rear end of the rotor 18 make a turning movement around the axis 12 and a rotational movement around the axis 38, the forward and backward central part of the rotor 18 makes the rotational movement around the rotation axis 38 of the rotor itself, and the turning movement around the ratation axis 38 of the shaft 16 is not required. Accordingly, even if a cross angleθof the rotation axis 38 against the rotation axis 12 of the shaft 16 is increased, the outside surface corresponding to the forward and backward central part of the rotor 18 is controlled with the surrounding ground, and a zigzag direction of the shield device 10 is controlled. |
