The ornamental design for a multi-head floor-grinding machine with pivoting heads, as shown and described.
FIG. 1 is a top plan view of a multi-head floor-grinding machine with pivoting heads, showing my new design.
FIG. 2 is a front perspective view of my new design.
FIG. 3 is a front elevation of my new design.
FIG. 4 is detail view of the center power head showing the unit tilted at an angle.
FIG. 5 is a right side elevation view of the new design, showing one of the power heads being tilted.
FIG. 6 is a left side elevation view of the new design; and,
FIG. 7 is a rear elevation view of the new design.
The dashed lines showing the drive heads in FIGS. 1-7 and the planetary floor grinder in FIGS. 1, 2, 3, 4 and 7 are for illustrative purposes only and form no part of the claimed design.