Problems :
It will seen that the NC on-the-fl y rotary shear represents a harsh environment for the machine in that the acceleration and the deceleration is severe. As a consequence, an increased magnitude of mechanical impacts is applied, and a repeated application of such impact has a signifi cant infl uence upon the useful life of the machine. Oscillations caused by the impact may become external disturbances which frequently causes a variation in the cut length or degrade the quality of cut end. In addition, a difficulty may be experienced in achieving an alignment between the cutting edges or the useful life of the cutting edges may be reduced.

Solution :
An acceleration is established in the design which satisfy the L-V curve, provided as the machine specification required. However, during an actual operation, the line speed V is not always equal to Vmax or Vm but is lower than these values in almost all cases. "G-mode" fi nds a extra setting time and shift it to positioning control to realize smooth acceleration and reduced Vm.