The ornamental design for a cornerbead, as shown and described.
FIG. 1 shows a perspective view of a corner bead, showing my new design;
FIG. 2 is a front view of FIG. 1;
FIG. 3 is a sectional view taken along the plane indicated on FIG. 2;
FIG. 4 is a back view of the corner bead shown in FIG. 1;
FIG. 5 is a left lateral view of FIG. 1;
FIG. 6 is a right lateral view of FIG. 1;
FIG. 7 is a bottom view of FIG. 1;
FIG. 8 is a top view of FIG. 1;
FIG. 9 is a perspective view of a structure with an access-way and window, showing an installed corner bead of FIG. 1; and,
FIG. 10 is a plan view of FIG. 9.
The portions of the design shown in broken lines in FIG. 9 and FIG. 10 are for the purpose of illustrating the environment only and form no part of the claimed design.