Design And Analysis Of Lower Hook Mechanism Of Weaving Machine With Trajectory And Attitude

Netting machine is an important production equipment for fisheries, aquaculture and fishing industry. There are three main interacting components of netting machine to fulfill the weaving process, which are the upper hook mechanism, the lower hook mechanism and the orifice plate mechanism. The lower hook mechanism as an important part of netting machine carries out the movements of line-hooking, line-drawing and line-dropping and cooperates with other components to complete the whole weaving process. The movement of the hook mechanism is complex, and the requirement is high. At present, the design of such domestic weaving machine copies the early foreign related products by using simple motion and small reel capacity fastback shuttle. There are problems of slow speed, low efficiency and poor stability. According to the requirements of a company in Jiangsu to apply the large capacity disk with arc type shuttle back, the lower hook mechanism of the weaving machine is designed and analyzed based on the design method of mechanism parallel combination and the virtual prototyping technology, so that the production efficiency of netting machine can be improved. The main research emphases of this paper are as follows:First, according to the trajectory and posture requirements of the lower hook mechanism of netting machine, we describe a mechanism design method which is based on mechanism combination and can simultaneously satisfy the specific requirements of trajectory and orientation. By selecting the double cam linkage combination mechanism, the working principle of the lower hook mechanism has been analyzed and by using complex number vector method, the mathematical model of the linkage mechanism has been established and the mathematical expressions of the trajectory and attitude have been determined as well as the affecting factors on the position and posture of the lower hook have been analyzed.Secondly, the work cycle diagram of the lower mechanism has been designed, and the phase interval as well as the time and axial angle distribution of the movement cycle about the two cam connecting rod systems have been determined. According to the working conditions of the hook mechanism, the motion law of the cam follower is reasonably selected, and the theoretical and actual contours of the cam have been designed by the analytic method, and the pressure angles of the cams have been checked.Finally, by using CATIA software, the 3D model of netting machine has been created. The virtual prototype of the lower hook mechanism of netting machine has been created in the software ADAMS, where the dynamic characteristics have been researched. That includes the working cycle diagram, the lower hook on the trajectory, attitude, velocity and acceleration curve. Finally, the physical prototype has been manufactured and debugged. The movement trajectory and posture of the lower hook mechanism has been verified, which is in accordance with the expected requirements. The operating speed of the netting machine have been improved and the netting workpieces have very good quality.