Abstract:Aiming at the problem of rope-biting hook under heavier load and serious abrasion of its roller in ropebiting mechanism of knotter, a calculation model of curved surface of cylindrical cam was built up by analyzing the kinematics of ropebiting mechanism in order to make the roller and cylindrical cam keep linecontact as well as ropebiting hook open and close according to sin acceleration law. By carrying out dynamic analysis of ropebiting mechanism and combining with the test of compression amount of compressing spring and tensile test of the rope, the statics model of ropebiting hook on the position of holding on to the rope was solved analytically, and optimum range of holdingon force of ropebiting hook was obtained which value is between 300.64N and 329.89N. The dynamic model of ropebiting hook was also solved analytically, and the contact force of cylindrical cam was between 240N and 330N when holdingon force of ropebiting hook is within optimum range. The peak value of contact force of cylindrical cam may be used to check contact fatigue strength of the roller, and guide material choice of the ropebiting hook and its roller. The field tests showed the roller installed on the rear of ropebiting hook didn’t have obvious abrasion after the kontter prototype finished 5000 bundles of rice and wheat straws according to predetermined preload force of compressing spring and initial pulling force of the rope. The result showed that the holdingon force of ropebiting hook was controlled suitably and linecontact cam improved contact load of the roller, which met the design requirement of impact resistance and antifriction.