Steam turbine rotor blade assembly

1. A steam turbine rotor blade assembly comprising:

an airfoil;

a shroud provided at a tip of the airfoil;

a blade root projecting toward a radially internal circumferential side of a turbine rotor and fitted to a root attachment provided on an outer circumferential portion of the turbine rotor;

a platform provided between the airfoil and the blade root;

a pin provided between the blade root and the root attachment;

a bore formed between respective surfaces of the shrouds facing each other and included in the respective adjacent rotor blades; and

a bar-like member provided in the bore with a clearance formed between the bore and the bar-like member;

wherein a clearance between the bore and the bar-like member during assembly is made smaller than a difference of displacement in the radial direction between respective bores of the shroud surfaces adjacent to each other, during rotation of a turbine.

2. The steam turbine rotor blade assembly according to claim 1 , wherein a seal fin is formed on a tip of the shroud.

3. The steam turbine rotor blade assembly according to claim 1 , wherein the clearance between the bore and the bar-like member is made equal to or greater than clearances between the pin and the blade root and between the pin and the root attachment.

4. The steam turbine rotor blade assembly according to claim 1 , wherein the bore is not passed through in the axial direction of the turbine rotor.

5. The steam turbine rotor blade assembly according to claim 4 , wherein a portion that is not pass through by the bore is located at respective positions, on the right and left of the shroud, anteroposteriorly facing a steam-flowing direction.

6. The steam turbine rotor blade assembly according to claim 1 , wherein the shroud has a portion circumferentially overlapping another shroud adjacent thereto.

7. The steam turbine rotor blade assembly according to claim 6 , wherein the shroud whose overlapping portion is located on the downstream side of a steam-flowing direction is bored to receive the bar-like member inserted thereinto.

8. The steam turbine rotor blade assembly according to claim 1 , the bar-like member has lower density than that of a blade material forming the shroud.

9. The steam turbine rotor blade assembly according to claim 1 , wherein the bar-like member is made of material that is liable to be worn away compared with a blade material forming the shroud.

10. A steam turbine rotor blade assembly comprising:

an airfoil;

a shroud provided at a tip of the airfoil;

a blade root projecting toward a radially internal circumferential side of a turbine rotor and fitted to a root attachment provided on an outer circumferential portion of the turbine rotor;

a platform provided between the airfoil and the blade root;

a bore formed between respective surfaces of the shrouds facing each other and included in the respective adjacent rotor blades; and

a bar-like member provided in the bore with a clearance formed between the bore and the bar-like member;

wherein the clearance between the bore and the bar-like member during assembly is made smaller than a difference of displacement in the radial direction between respective bores of the shroud surfaces adjacent to each other, during rotation of a turbine.

11. The steam turbine rotor assembly according to claim 10 , wherein after being inserted into the bore, the bar-like member is sealed into the bore by caulking a shroud portion at an end of the bore.