The Optimization Design And Analysis Of Light Yarder Friction Roll Structure

With the change of forestry policy and strengthen of state environmental protection policy in China,the forest cutting target has changed fundamentally,which in the past dominated by the natural forest or natural secondary forest,and now dominated by artificial forest.At the same time,the majority of cutting is small diameter wood while the large diameter wood reduced.Light yarder friction roll has replaced the previous large and medium yarder friction gradually.The light yarder friction runs by friction caused by fiction roll and wire rope pulling the wire rope.In the past,the friction roll used structural steel as the material with low friction coefficient and the cumbersome structure.It is an important subject that how to improve the friction pull caused by forestry yard friction roll and reduce its weight.By choosing different materials as the manufacturing materials of friction roll,the pull force caused by fiction roll and wire rope and its weight are different.The weight of friction roll can be reduced by optimizing the shape and size of friction roll.Therefore,it is an important content of promoting yarder fiction roll working performance and reducing device weight to optimum structural design for fiction roll.The light yarder friction roll is taken as the research object in this paper.The friction and wear tests are carried out for the three materials of structural steel,Buna-N rubber and MC nylon,respectively,and their service life is calculated according to the results of test analysis.The finite element analysis software is adopted to verify strength and stiffness,and the friction roll of optimum combination materials is selected.Then,the structural design of friction roll is carried out by finite element topology optimization and dimension optimization.The specific study contents and results as follows:Aiming at the light yarder fiction roll designed by the project of"Multi-function Light Yarder Fiction Roll System Development",the friction pull of light yarder fiction roll is calculated and analyzed theoretically.By analyzing the main factors affecting the friction pull of the friction roll,it is proposed that selecting suitable friction pair and the improving the structure are the main ways to improve the friction roll.By MMS-2A microcomputer controlling friction and wear tester,the friction and wear test and analysis are carried out to the three materials of Buna-N rubber,MC nylon and structural steel.It is concluded as the fiction roll materials,the service life of Buna-N rubber,MC nylon and structural steel are 1.5 year,3.5 years and 16 years,respectively.Based on this and combined with materials characteristic and fiction roll operating requirement,the friction rolls of rubber + structural steel,rubber + nylon and structural steel + nylon are selected,and the strength and stiffness are tested by finite element analysis software.Finally,the best combination of friction roll structure material is determined:Buna-N rubber(rim)+structural steel or structural steel(rim)+ MC nylon,it provides a reference for the improvement of friction roll material.By finite element topology optimization,the structure design on Buna-N rubber(rim)+ structure steel friction roll wheel hub are carried out.The optimization results are spoke structure,with the weight reducing by 49.6%;on this basis,finite element simulated analysis to optimization structure is carried out further.It shows the optimization results meet the performance requirements,providing a reference for the design of portable winch fiction roll.