Friction And Wear Property Analysis Of Slotted Sleeve-Bush Friction Pair

In actual production,one of the main reasons why causing the frequent failure of roll in zinc pot of a continuous hot dip galvanized line is that the severe wear problem of sliding bearing which in zinc liquid containing zincilate.Take the advantage of surface texturing technique to dig a serious of spiral groove on the outer cylindrical surface of sleeve and then study the friction and wear property based on a serious of tests in lab.The main contents as follows.Firstly,grooving impact analysis.Spiral grooves are designed on the outer cylindrical surface of sleeve.Parameters of grooves,such as screw pitch,shape and size of the cross section,and number of grooves,are determined.Contact strength of the slotted sleeve is calculated according to the actual working conditions of the production line and it is found that spiral slots have a little influence on the contact strength of the sleeve.Simulation of the flow field of the zinc liquid in the bearing gap is conducted and it is found that the flow of the zinc liquid in axial direction of the sleeve increases linearly along with the increase of the screw pitch(within pitch 160).The greater the axial flow is in the bearing clearance,the stronger the slagging capacity be got.Secondly,testing machine’s transformation.An existing linear reciprocating friction and wear test machine was reformed to study the friction and wear performance of slotted sleeve.A detachable additional mechanism was designed under the premise of retaining the original test machine’s loading system and the friction together with positive pressure testing system.Fasten the detachable additional mechanism on the reciprocating movement platform of the original machine,so,a rotary friction and wear testing machine realized.The property of the new testing machine was verified by experiments.Then the test procedures and data processing methods are determined.The new testing machine can not only simulate the process of rotation friction and wear about ring–ring,ring–block etc.which has different materials and surface structures,but also can conduct rotation friction and wear test research for different contiguous forms and lubrication condition.Thirdly,testing research on friction and wear property of slotted sleeve.Upper and low specimens for rotating wear test are designed based on the actual bush and sleeve.There are 6 kinds of low specimens(i.e.,sleeves).Each kind has a specific screw pitch.6 sleeves with no slotting and 6 slotted sleeves with a specific screw pitch are prepared for tests.Duty parameters(such as tension,line speed and correcting roll engagement)in a real production line are adjusted when a new coil of strip comes.So these parameters jumped from one step to another.Two parallel paths of working condition are designed to simulate the steplike change of load and rotation speed for a series of coming tests,under normal temperature,drip lubrication.One path maintains the revolving speed constant,and let onespecimen undergoes 3 steps of load respectively.The second path maintains a constant load,and let one specimen undergoes 3 steps of revolving speed respectively.The result shows that grooving is undoubted helpful for improving anti-friction and anti-wear performance: i)Keeping the revolving speed constant,in the step of load 108 N and 132 N,average friction coefficient of the slotted sleeve(pitch 160)has the largest decline,and the degree of reduction respectively are 13.3% and 22.4%,as well the wear extent has the largest declines and the degree of reduction respectively are 41.4% and 54.1%,while in the step of load 84 N,the friction coefficient and wear extent of pitch 144 has maximum decline,and the degree of reduction respectively are 31.6%,46.7%.ii)Keeping the load constant,in the step of revolving speed 130 rpm,average friction coefficient and wear extent of the slotted sleeve(pitch 160)have the largest decline,and the degree of reduction respectively are22.4%,33.9%,while in 160 rpm,pitch 144,and the degree of reduction respectively are34.8%,39.9%.In general,the spiral groove structure can obviously improve the friction and wear performance of the friction pair,and the sleeve of pitch 160 or 144 has better performance on anti-friction and anti-wear.