Back support frame for chair

FIG. 1 is a perspective view of back support frame for chair showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a back elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof; and,

FIG. 8 is a perspective view showing a chair with the back support frame for chair.

The broken lines shown in FIG. 8 is for the purpose of illustrating environmental structure and forms no part of the claimed design.