The ornamental design for a chairframe, as shown and described.
FIG. 1 is a top, front, right side perspective view of a chair frame according to our new design;
FIG. 2 is a left side elevation view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a rear elevation view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is an enlarged, partial cross-section view thereof, taken along line 8-8 of FIG. 6.
The dash-dash broken lines illustrate portions of the chair frame that form no part of the claimed design. The dot-dash broken lines represent boundaries of the claimed design and form no part of the claimed design. The pattern shown in the cross-sectional view shows internal subject matter that forms no part of the claimed design.