| 摘要 |
PROBLEM TO BE SOLVED: To provide a shield bit which enables effective excavation of a Novel Material Shield-cuttable Tunnel-wall (NOMST). SOLUTION: This shield bit 1 is attached to a cutter face plate 3 of an excavator, and an object 2 to be excavated is excavated by means of an excavating blade tip 6 of a bit body 4. In relation to brazing of the tip 6, its height h is limited to a maximum value of 50 mm with reference to a cutting face in excavation, so that an influence exerted by brazing distortion can be suppressed; and when the height h exceeds 50 mm, the number of steps of receiving seats 5a, 5b and 5c is increased. In terms of a shape of the tip 6, consideration is given to relationships among a thickness t, the height h and a width w so as to suppress the influence exerted by the brazing distortion; and particularly, a t:h:w ratio is set at a range of 1:2.5-3.5:4.0-5.0. COPYRIGHT: (C)2004,JPO |
