CNC machine tool for rotating a workpiece by a preset angle per one-revolution rotation of a rotating shaft on a worktable

A CNC machine tool comprising:

• a machine bed;
• a worktable disposed movably on said machine bed and movable on said machine bed under CNC control, said worktable being provided with a first engaging element fixed thereon;
• a rotating unit including
• a vertical rotating shaft journalled on and disposed axially and movably on said worktable, and
• a guiding wheel sleeved fixedly on said rotating shaft and having an annular outer surface that is formed with a guiding slot, which has an entrance slot portion that extends along a circumferential direction of said guiding wheel and that has a leading end and a tail end, a helical slot portion that has a leading end coupled with said tail end of said entrance slot portion and a tail end, and an exit slot portion that extends along the circumferential direction of said guiding wheel and that has a leading end coupled with said tail end of said helical slot portion, and a tail end;
• a driven unit including
• a horizontal central shaft journalled on said worktable, said central shaft being movable on said worktable between a connecting position and a disconnecting position,
• a second engaging element disposed fixedly on said central shaft,
• a spring member for biasing said second engaging element to engage said first engaging element of said worktable so as to prevent rotation of said central shaft on said worktable, and
• a plurality of angularly equidistant driven elements connected fixedly to and extending radially and outwardly from said central shaft and arranged along a circumferential direction of said central shaft, said driven elements being rotatable about said central shaft to engage said guiding slot in said guiding wheel of said rotating unit in turn when said rotating unit rotates so that an end of each of said driven elements can move along said entrance slot portion, said helical slot portion, and said exit slot portion and can subsequently exit from said tail end of said exit slot portion of said guiding slot, the number of said driven elements being N, said driven elements cooperating with said guiding slot in said guiding wheel such that said central shaft can rotate by an angle of 360/N degrees per one revolution of said rotating shaft, thereby permitting intermittent rotation of said central shaft on said worktable;
• and
• a clutch unit connected between said rotating unit and said driven unit, said clutch unit being driven by said rotating unit to move said central shaft to said disconnecting position when said end of each of said driven elements moves along said helical slot portion so as to separate said second engaging element of said driven unit from said first engaging element of said worktable, thereby permitting rotation of said central shaft on said worktable, said clutch unit being driven by said rotating unit to move said central shaft to said connecting position when said end of each of said driven elements moves along said entrance slot portion and said exit slot portion so as to permit engagement of said second engaging element of said driven unit with said first engaging element of said worktable, thereby preventing rotation of said central shaft on said worktable.