I claim the ornamental design for a grating device, as shown and described.
FIG. 1 is a left side view of my design for a grating device, the right side view being identical;
FIG. 2 is a front view of the design for the grating device shown in FIG. 1;
FIG. 3 is a rear view of the design for the grating device shown in FIG. 1;
FIG. 4 is a top view of the design for the grating device shown in FIG. 1; and,
FIG. 5 is a bottom view of the design for the grating device shown in FIG. 1.
A magnified view of the grating surface pattern of the grating device shown in FIGS. 1-5 is shown in FIG. 1. The broken lines in FIGS. 1-5 are for illustrative purposes only and form no part of the claimed design.