Design Criteria Study for Underactuated Symmetric Pinching Mechanism of Pinch Roll Machine in High-Speed Wire Rod Product Line

Inspired by the underactuated robotic hand mechanism and its feature of shape adaptive and compliant envelop grasping, the paper proposed underactuated symmetric pinching mechanism to solve the problem of pinch rollers idle and slipped or pinched too tightly. Pinch roll machine is a key device in High-Speed wire rod product line. It is designed with actuated symmetric pinch mechanism. We discuss the possibility of the underactuated symmetric pinch mechanism applied in the pinch roll machine. Three kinds of underactuated symmetric pinch mechanism solutions are presented. When the mechanism implement the synchronous symmetric pinch action, a displacement can occur at the underactuated joint, and the instantaneous clamping force can be buffed by the spring system, so as to reduce the dynamic impact of clamping force. A suitable design criteria is deduced from statics and kinematics research. The design method can keep the contact force do not change when the rod dimension is variable in the passing line. Thus, it can protect the rod not to be damaged while it is pinching and conveying, and avoids the fatigue damaging caused by excessive pinching impact force. The research method is novel and feasible. The design result will be beneficial to improve service life of the pinch roll machine.