PURPOSE: To form a segment ring by reducing the necessary tail clearance.
CONSTITUTION: The first and the second rectangular segments 9a and 9b are arranged at a specific position in the segment ring shaping, and the end surface 20a of the third rectangular segment 9c is abutted with the end surface 18b of the first rectangular segment 9a. The outer end edge 20d of the rest end surface 20b is temporary-approach-fixed with the inner peripheral surface of a skin plate by turning the third rectangular segment 9c, and the end surface 21b of the fourth rectangular segment 9d is abutted with the end surface 19a of the second rectangular segment 9b, deflected outward in the radial direction of a tunnel. The fourth rectangular segment 9d is turned, and the outer end edge 21c of the rest end surface 21a is temporarily approach-fixed with the inner peripheral surface of the skin plate. and the end surface 21b of the fourth rectangular segment 9d which is abutted through deflection is shifted inward in the tunnel radial direction up to the coincidence position with the end surface 19a of the second rectangular segment 9b, and the rest end surfaces of the third and the fourth rectangular segments 9c and 9d are closed to form a segment ring.
DAINIPPON DOBOKU KK
YAMAMOTO MINORU