The ornamental design for a beltcore, as shown and described.
FIG. 1 is a front perspective view of a belt core;
FIG. 2 is a rear perspective view of the belt core of FIG. 1;
FIG. 3 is a top plan view of the belt core of FIGS. 1 and 2, the bottom view being a mirror image thereof;
FIG. 4 is a right side view of the belt core of FIGS. 1 and 2, the left side being a mirror image thereof;
FIG. 5 is a rear elevation view of the belt core; and,
FIG. 6 is a front elevation view of the belt core.
The article is shown with a symbolic break in its length. The appearance of any portion of the article between the break lines forms no part of the claimed design.
The broken lines in the drawings depict unclaimed environmental subject matter.