Carriage structure of NC lathe

A carriage structure of an NC lathe comprising a bed, a headstock mounted on said bed for rotating a work around C-axis, a tailstock slidably mounted on a first guide surface formed on said bed, and a carriage slidably mounted on a second guide surface formed on said bed in a direction of Z-axis parallel to said C-axis and juxtaposed with said first guide surface, said carriage including:

• a saddle having a first slide surface for contacting said second guide surface of said bed and a second slide surface inclined at a predetermined angle with respect to said first slide surface;
• a slide base slidably mounted on the second slide surface of said saddle for movement in a direction of Y-axis perpendicular to the Z-axis;
• a column extending from said slide base substantially perpendicular thereto and having a column body which includes a guide surface in a direction of X-axis perpendicular to the Z-axis and to the Y-axis;
• a cross slide slidably mounted on said guide surface of said column body in the direction of the X-axis;
• a tool spindle rotatably mounted on said cross slide around B-axis perpendicular to the X-axis and to the Z-axis;
• a spindle rotatably supported by said tool spindle around an axis perpendicular to the B-axis for mounting a cutting tool thereon;
• said cross slide including a drive shaft and a rotary shaft for rotating said spindle and said tool spindle, respectively, said drive shaft and said rotary shaft being rotatably mounted on said cross slide, and said cross slide further including a driving device for driving said drive shaft and said rotary shaft;
• said drive shaft and said rotary shaft being coaxially disposed with each other and rotatably around the B-axis, said driving device including a first driving device for rotating said drive shaft and a second driving device for rotating said rotary shaft, and said second driving device being operable to index the position of said tool spindle around the B-axis;
• said tool spindle includes a lock device for fixing the position of said spindle relative to said tool spindle;
• and
• said lock device being operable to selectively fix the position of said spindle at two positions between 0.degree. and 180.degree. around an axis of said spindle where a cutting edge of the cutting tool is directed to opposite directions, so that said tool spindle can be operated in a turning mode with said spindle fixed to the position 0.degree. and can be operated in a rotary cutting mode with said spindle permitted to rotate, and can be operated in a right- and left-hand cutting mode with said spindle fixed to either of the two positions between 0.degree. and 180.degree..