Headstock assembly for machine tool

A headstock assembly for a machine tool which is used for machining a workpiece, and which includes a machine base, and a guide rail unit mounted on the machine base and extending along a longitudinal direction, said headstock assembly comprising:

• a mount secured to the machine base, and having a female threaded bore;
• a headstock which is mounted slidably on the guide rail unit, and which is spaced apart from said mount in the longitudinal direction;
• a drive member mounted on said headstock;
• a spindle which extends along a spindle axis in the longitudinal direction, and which is rotatably mounted to said headstock, said spindle being coupled to be driven by said drive member to rotate about the spindle axis;
• and
• a spindle extension extending along the spindle axis, and coupled to be rotatable with said spindle, said spindle extension having a male threaded segment which is configured to be in threaded engagement with said female threaded bore so as to permit said headstock to be linearly moved relative to said mount in the longitudinal direction, wherein
• said headstock has a left end wall and a right end wall which is spaced apart from said left end wall in the longitudinal direction to define a chamber, said left end wall having a left inner bearing surface which defines a left bore extending to be communicated with said chamber, said right end wall having a right inner bearing surface which defines a right bore extending to be communicated with said chamber,
• said spindle extends along the spindle axis to terminate at a left end and a right end, and has
• an intermediate segment disposed between said left and right ends in said chamber, and having a main region and a juncture region proximate to said right end,
• a left journal region which is disposed between said left end and said main region, and which is journaled on said left inner bearing surface, and
• a right journal region which is disposed between said right end and said juncture region, and which is journaled on said right inner bearing surface,
• said drive member has an output shaft which is rotatable about a shaft axis, and which is coupled to said intermediate segment in said chamber so as to drive said spindle to rotate about the spindle axis,
• said mount is disposed leftwardly of the guide rail unit, and said female threaded bore extends along the spindle axis, and
• said spindle extension extends along the spindle axis to terminate at a proximate end which is coupled to said left end of said spindle to permit said spindle extension to rotate with said spindle, and a distal end opposite to said proximate end in the longitudinal direction, said male threaded segment being disposed between said proximate and distal ends.