Abstract: Based on the importance and difficulties of the calculation of the chucking power of the heavy-duty forging manipulator, it is pointed out that the jaw’s surface is different from the ordinary automatic hand’s clamp face. A thread of the calculation of chucking power has been worked out basing on the simplification of the action between gripping mechanism’s jaw and forging’s contact surface to the action between jaw’s crowned tooth and forging’s extrusion groove. On the basis of the working condition, the operating conditions of the jaw have been separated into the clamping and the gripping condition. After peculiarity and effect of two conditions was discussed, a mechanical model of workpiece under the gripping condition has been formed and the chucking power of the jaw on both horizontal and vertical position are studied. With the gripping force corrected by the amplification factor, the output force of the claw-beam gripping hydro-cylinder can be set to actualize the concave-convex mechanism between the jaw and the workpiece under the clamping condition to make sure the maximum gripping moment can be reached under the gripping condition. Considering the construction peculiarity of the jaw and working piece’s contact surface, the idea and principle of jaw’s crowned tooth design has been worked out. The example calculation and the virtual prototype simulation prove that the calculation method is effective.

Key words: Gripping force, Gripping hydro-cylinder, Gripping mechanism, Heavy-duty forging manipulator