Simulation design of negative cam shedding based on spring return

QIU Hai-fei, DANG Bo
(College of Mechanical Engineering, Xijing University , Xi'an 710123, China)

Abstract: Aiming at the problem of force transmission through wire-steel and pulley in previous cam lifting, a new type of negative cam shedding mechanism with spring return was designed and developed on the basis of plane bar group, gear drive, tension spring and disk-cam mechanism with swinging roller follower. The stiffness and initial tension of the spring for coarse cotton fabric were determined through mechanism analysis, derivation of mechanical model and warp tension calculation. Functional simulation prototype of the mechanism was established on ADAMS/View platform. In view of real work situation on the mechanism, dynamic warp tension simulated by Step function was loaded into the heald frame which effectively improved dynamic design accuracy and reliability for lifting process of the heald frame. Based on that, the feasibility of cam lifting and spring return were verified by kinematic and dynamic simulation analysis. The results indicate that in the process of opening and closing ,the travel range of heald frame is about 14.5 mm and angular range of swing bar on the cam is 12.4°, which can meet the technological requirements of negative cam shedding.
Key words: cam; spring; shedding mechanism; Step function; heald frame