Ball Screw Nut Grinding Machine Greatly Cuts Processing Time

Mitsui Seiki’s (Franklin Lakes, N.J.) VGi20A Ball Screw Nut Grinding Multitasking Machine grinds and machines in a single chucking, reducing nut processing time by 66%. With five axes of motion and storage for 40 tools, the machine can grind thread grooves and machine the nut circumference, end surface, key grooves and return tube holes in a single setup. This elimination of setup changeovers reduces manufacturing time and assures exact phase alignment of thread grooves and return tube holes. A standard touch probe enables automatic pre-processing phase alignment of the thread groove and wheel.

The machine produces threads via simultaneous interpolation of the C-, Y- and Z-axes. Users can automatically generate optimal grinding programs by entering data on the grinding screen of the machine’s FANUC 31i-B5 control, with canned measurement cycles available for setup. A rotating dresser shapes wheels for grinding thread profiles, and a single-point dresser prepares wheels for grinding nut circumferences and end surfaces. An optional three-dimensionally-designed automatic coolant nozzle changer provides coolant to an optimal point based on the profile of the workpiece, grinding wheel and quill.

The VGi20A’s X-, Y- and Z-axis strokes are 550 mm, 600 mm and 500 mm respectively. A-axis trunnion movement ranges from +15 degrees to -105 degrees, and C-axis rotation is 360 degrees. Maximum workpiece diameter is 250 mm, height 300 mm and weight 120 kg. The machine spindle is capable of speeds from 15 rpm to 30,000 rpm and is fitted with an HSK-A63 taper. The machine accommodates tools up to 250mm in length and 90mm in diameter and has a footprint of approximately 3200 mm x 3000 mm.

Bill Malanche, Mitsui Seiki USA’s chief operating officer, says, “By combining grinding, multitask machining, and automation strategies, the VGi20A minimizes production time while maximizing accuracy and repeatability.”