Patent ID: 8579560

Claim:
An index device for a machine tool, the index device comprising: a rotary shaft ( 40 ) to which a rotation object is secured at one end of the rotary shaft ( 40 ); a housing ( 30 ) which surrounds at least an outer periphery of the rotary shaft ( 40 ) to support the rotary shaft ( 40 ); a bearing (B 1 , B 2 ) provided between the housing ( 30 ) and the rotary shaft ( 40 ); drive means (M) provided between the housing ( 30 ) and the rotary shaft ( 40 ) and including a first drive motor (M 1 , M 2 ) including a motor rotor (M 1 a , M 2 a ) and a motor stator (M 1 b , M 2 b ) arranged concentrically around the rotary shaft ( 40 ) to rotate the rotary shaft ( 40 ) and the rotation object about a first axis, the motor stator (M 1 b , M 2 b ) being secured to the housing ( 30 ), the motor rotor (M 1 a , M 2 a ) being secured to the rotary shaft ( 40 ), and an actuatable clamp mechanism ( 50 ) that fixes the rotary shaft ( 40 ) in a non-rotatable manner; wherein the housing ( 30 ) includes a casing member ( 30 a , 31 a ) and a securing member ( 30 b ), the motor stator (M 1 b , M 2 b ) being secured to the casing member ( 30 a , 31 a ), the bearing (B 1 , B 2 ) being interposed between the securing member ( 30 b ) and the rotary shaft ( 40 ), the casing member ( 30 a , 31 a ) being detachably connected to the securing member ( 30 b ), wherein a built-in unit sub-assembly ( 22 ) is constituted by assembling the rotary shaft ( 40 ), the bearing (B 1 , B 2 ), the motor rotor (M 1 a , M 2 a ), and the securing member ( 30 b ) together, and wherein an enclosure unit ( 21 ) is constituted by assembling the motor stator (M 1 b , M 2 b ) and the casing member ( 30 a , 31 a ) together and placing a cable (c 11 , c 21 ) connected to the motor stator (M 1 b , M 2 b ) such that the cable (c 11 , c 21 ) extends from the motor stator to outside the housing from a side of the housing that is opposite a side of the housing where the rotation object is located, and wherein the built-in unit sub-assembly ( 22 ) is connected to the enclosure unit ( 21 ) such that the built-in unit sub-assembly ( 22 ) is capable of being inserted into and extracted from the enclosure unit ( 21 ) from a side of the index device where the rotation-object is located; and wherein the rotation object is a machining head having a support head and a tool spindle that is pivotably mounted to the support head so as to be pivotable about a second axis that is transverse with respect to the first axis.