The Design And Dynamic Characteristics Of The Parallel Beating-up Mechanism Of The Three-dimensional Loom For Weaving Carbon Fiber

The beating-up mechanism of carbon fiber stereoscopic loom is an important part of the whole loom.It plays an important role in the weaving of stereoscopic carbon fiber fabric.Beating-up is the key for the fabric formation.Carbon fiber three-dimensional fabric has complex structure and various types,among which the most prominent feature is that its fabric thickness is often much greater than that of traditional woven products.The reed of the traditional loom beating-up mechanism wiggles around a rotating center.The reed applies beating force to only one layer of filling.Carbon fiber three-dimensional fabric is very thick with many layers of fillings and they are arranged longitudinally on the cross section of the fabric.Therefore,the reed of traditional beating mechanism cannot make every layer of filling of carbon fiber three-dimensional fabric subject to the same beating force.The reed needs to beat-up horizontally.The parallel weft beating mechanism of "The research and-development of multilayer angular joint weaving carbon fiber" in the scientific support project of national "the 12th five-year plan" undertaken by Tianjin Polytechnic University is connecting rod-sliding block beating-up mechanism.The project has made significant progress in the field of carbon fiber three-dimensional fabric weaving in China.However,the beating-up mechanism has insufficient in beating force and response when weaving carbon fiber three-dimensional fabric.Friction between slider and guide rail wastes a lot of energy.Now,the relevant research work is carried out to solve these urgent problems:(1)A combined parallel beating-up mechanism of combining conjugate cam and four linkages is put forward,which can realize parallel beating with large beating force,fast response and high energy efficiency.(2)A general calculation method of weft beating resistance for complex and changeable carbon fiber three-dimensional fabric is presented.(3)According to the beating-up tec hnology o f carbon fiber stereoscopic loom,the acceleration characteristic of bea ting-up mechanism should meet the requirement of reducing loom vibration as much as possible.Acceleration curve should be zero at the beginning and end and continuously differentiable.The reed acceleration is negative at the end of filling beating.The reed exerts a inertial force on the fabric.The maximum negative acceleration of reed is determined according to the maximum beating-up resistance of carbon fiber three-dimensional fabric.Solve out the motion law of sine-cosine combination function.Based on the motion law of sine-cosine combination,the profile of conjugate cam is solved by analytical method.Conjugate cam's pushing and return process total Angle is 154 °.Conjugate cam has no rapid return characteristic.(4)In order to making the reed beat the weft parallelly,scale synthesis of four linkages is carried out.The kinematics analysis and optimization of the combined parallel beating-up mechanism are carried out by using the two-stage bar group method.The rectangular coordinate system is established with the pivot point of the swing arm as the origin.The transverse and vertical coordinate ratio of hinge fulcrum of rocker rod is 19/15.When the swing arm length is taken as 398mm,the angle of dead center position of the link at the beating end is basically zero.The reed realizes beat weft parallelly.At this point conj ugate the cam angle is 77 °.In order to simplify the design process of combined parallel beating-up mechanism,parametric design and motio n simulation analysis of parallel beating-up mec hanism of co nj ugate cam with four-link combination are carried out to improve the design efficiency.(5)Modal and vibration analysis of reed are carried out for vibration of reed caused by the impact of beating-up resistance.The reed vibration is mainly the first order oscillation.The reed will not resonate because the external excitation frequency is far away from the natural freq ue nc ies of each order.In order to red uce the vibration and deformation of reed due to the beating-up resistance impact,the reed with high elastic modulus should be selected appropriately.