Analysis And Synthesis Of Eccentric Conjugate Non-circular Gear&Crank-rocker&Gears Train Weft Insertion Mechanism

As one of the most important components of a rapier loom, the function of weft insertionmechanism is to transform the uniform rotary motion of the loom’s spindle into reciprocatingrectilinear motion with variable velocity of the rapier head, by which the weft is led into the shedand then weaved with the warp yarn to be textiles. At present, there are several kinds of weftinsertion mechanisms used on rapier looms, such as the conjugate cam type, the differential geartrain linkage type, and the spatial four-linkage type weft insertion mechanisms. These weftinsertion mechanisms are difficult to manufacture and ensure accuracy. And the originalinnovations and patents of these weft insertion mechanisms are authorized by foreign countries,so the lack of independent innovation restricts the development of domestic loom industry.The paper presents a novel weft insertion mechanism researched for rapier looms namedeccentric conjugate non-circular gear&crank-rocker&gears train weft insertion mechanism,which is based on summarizing and analyzing advantages and disadvantages of weft insertionmechanisms used on rapier looms. The kinematic and dynamic model of this new-type weftinsertion mechanism has been established, as well as analysis, optimization and experimentationof this mechanism are conducted. This research will reduce the diffculty of manufacturing andimprove the research and development of domestic rapier looms.The research contents and results of this paper are shown as bellow:1) Synthesized the creating mechanism of high-order non-circular gear and deformednon-circular gear, a novel non-circular gear form named high-order deformed eccentricconjugate non-circular gears is proposed. The pitch curves equations of high-order deformedeccentric conjugate non-circular gears are established. The concavity distinguished conditionsreferred to pitch curves of driving gear and driven gear are deduced. And the relationshipbetween the gear modulus and minimal radius of curvature in pitch curve was obtained on toothundercutting in the process. The design and simulation software of high-order deformedeccentric conjugate non-circular gears is compiled and the influences of several structuralparameters on the kinematic characteristics of the gears are analyzed. 2) The kinematical mathematic models of eccentric conjugate non-circular gear&crank-rocker&gears train weft insertion mechanism are established and an aided analysis andsimulation software is compiled based on VB. The influences of several structural parameters onthe kinematic characteristics of the mechanism are analyzed by applying this software,as well ascalculating the parameters and simulating movement. A group of preferable parameters whichcould meet the requirements of weft insertion technology is obtained by means ofhuman-computer interactive optimization method. This set of parameters can ensure thismechanism to meet the requirements of weft insertion.3) Dynamic models of the eccentric conjugate non-circular gear&crank-rocker&gearstrain weft insertion mechanism are established. The tooth contact force as well as the force ateach hinge point is calculated and the dynamic analytical software is compiled. Applying thissoftware, analyse the dynamic properties of the tooth contact force and the force at each hingepoint. Finally a set of preferable parameters are obtained with the requirements of weft insertionand better dynamic characteristic.4) Transmission arrangement and structure design of eccentric conjugate non-circular gear&crank-rocker&gears train weft insertion mechanism is conducted according to the optimizedparameters. And three-dimensional modeling, virtual assembly and interference checking of thismechanism are conducted. Virtual prototype technology based on ADAMS is applied to simulatethe motion of this mechanism and the law of motion of rapier head which is obtained bysimulation analysis is basically identical with that of theoretical calculation, which indicates thatthe results of theoretical analysis are correct.5) Basic on structure design and virtual experimentation, a test-bed of weft insertionmechanism of eccentric conjugate non-circular gear&crank-rocker&gears train is developed.Kinematic characteristic is tested on the test-bed and the correctness of kinematics model isverified.