EE WAS USING HAMMER TO DRIVE OUT BOLT ON BROKEN COUPLING OF SCREW CONVEYOR. EQUIPMENT WAS LOCKED OUT AND SECURED. ACCESS TO BOLT WAS VERY TIGHT & WHEN EE SWUNG HAMMER, IT HIT SIDE OF SCREW CON VEYOR CAUSING IT TO STRIKE HAND RESTING ON EQUIPMENT. 5 STITCHES REQUIRED TO CLOSE WOUND. EE WAS WEARING GLOVES WHICH PROBABLY REDUCED INJURY.