Optimal Design And Digital Adjustment Of Double Needle Bar Warp Knitting Machine's Loop Forming System

With the advancement of science and technology,warp knitted fabrics are gradually displaying their unique performance in high-end fields such as aerospace and medical equipment.The application of warp knitting technology in various industries has provided a large market,which further increases the demand of warp knitting machine equipment.Meanwhile,there are also higher requirements for the speed of warp knitting machinery,the reliability of knitting,the high efficiency of type change and the digital control.Therefore,improving the performance of domestic warp knitting machines in terms of weaving reliability,high efficiency of model change and digital control will help improve the efficiency of warp knitting equipment,which is of important engineering application value.This research takes a Raschel double-needle bed warp knitting machine as an example for analysis.On the basis of modeling it,the theory is combined with software simulation for analysis to reduce the weight of the double-needle bed warp knitting machine's loop-forming system.The reliability of the loop system and the realization of knitting pattern change's digital adjustment are studied for the purpose.First,based on the complex vector method and geometric method,the movement research and analysis of double-needle bed warp knitting machine's loop forming system was carried out.The first step was to analyze the movement coordination and movement requirements among the latch needle,sinker and bar.The second step was to use SOILDWORKS software to perform 3D modeling of a Raschel double-needle bed warp knitting machine and perform simulation analysis.Then,draw the motion diagrams and motion vector diagrams of the latch needle,sinker and bar swing mechanism respectively,and use complex vector method and geometric methods to analyze them to obtain the motion curves of latch needle,sinker and bar.Finally,the analysis was further carried out in conjunction with its motion requirements and the theoretical calculation curve,which proved the correctness of the theoretical analysis.Secondly,the lightweight design of the warp knitting machine' connecting rod was carried out.First,through the simulation of the loop-forming system,the force of the latch needle connecting rod was obtained.Then,taking the latch needle connecting rod as the research object,compare the stress,deformation and displacement of the latch needle connecting rod with carbon fiber T700 epoxy resin matrix composite material,AR glass fiber composite material and the original aluminum alloy material under the maximum force.The impact of quality.Finally,a hollow structure was used to replace the solid structure of the latch needle connecting rod,and the inner diameter of the connecting rod was optimized with a uniform distribution,and the influence of the main parameters of the hollow structure on the stress and deformation displacement of the latch needle connecting rod was analyzed.Compared with the original rod,when the carbon fiber T700 epoxy resin-based composite material was used and the hollow diameter of the rod was 6.5mm,its mass,maximum stress and maximum deformation displacement were largely reduced by 47.34%,6.93% and 36.98%,respectively.Then,based on the improved ant colony algorithm,the reliability of the latch needle mechanism was optimized.First,the dead-point stop principle was adopted to replace the latch cam linkage mechanism with a crank linkage mechanism.Then,considering the errors of hinge connection and manufacturing errors,the accuracy and reliability model of the latch needle mechanism was established.Then,the reliability optimization method of warp knitting machine's latch needle mechanism based on the improved ant colony algorithm was proposed,and the mutation operator was designed according to the rod length of the warp knitting machine to carry out optimization design.Finally,a comparative experiment with the existing algorithm was performed to compare the reliability of the optimization.The result showed that the optimized result of the improved ant colony algorithm was excellent.Under the same error conditions,the motion reliability was increased by 4.3% and 2.14% in the x and y directions on average.Finally,based on the analysis of the existing synchronous type changing device and the above analysis of the loop forming system,the digital control type changing device was designed.On the basis of the analysis of the double-needle bed warp knitting machine,the existing double-needle bed warp knitting machine's type-changing synchronization adjustment device was analyzed,and the mechanism diagram and movement vector diagram of each part were made.After analyzing it,the spatial coordination relationship among the latch needle position,the sinker position and the spacing of the knock-off plate when changing the pattern of the warp knitting machine was obtained,based on which a digital typechanging adjustment mechanism was designed.On the basis of the motion analysis of the latch needle mechanism,a digital control mechanism for the latch needle part using a servo motor and a ball screw drive had been designed to achieve maintenance-free operation.