| Line gear(LG)is a new type of gear transmission mechanism,which is based on the theory of space curve meshing.It has the characteristics of large transmission ratio,small volume and no root cutting.In the earlier research,LG has been made remarkable achievements about meshing principle,design theory,manufacturing technology and lubrication design.During the meshing process,the tooth surface has high contact stress due to the point contact state of the LG’s contact area,so the tooth surface is easy to be worn,and the life span of the LG is reduced.In addition,the transmission efficiency of the LG pair decreases in the case of poor lubrication;Besides,for LG used in micro-transmission,due to space limitations,sometimes it is impossible to establish complete oil or grease lubrication,which seriously restrict the industrialization of the LG.Based on the ion plating technology,this paper discusses the coatings method for the surface of the LG.It explores the process of depositing TiAlN coatings and DLC coatings on the surface of LG as well as the influence on the tribological properties of the LG through experiment and theoretical analysis of related results.It can provides guidance for the preparation of effective and reliable solid lubricat coatings on the surface of the LG.Therefore,it can provide theoretical and application tools for good performance of solid gear lubrication technology for LG under special working conditions,such as oil or grease lubrication failure.Specifically,the main research contents of this paper include as the following aspects:1.It takes the simplified model of the LG as research object,the TiAlN coatings was deposited on the surface of the simplified model made of 45 steel by multi-arc ion plating.The effects of different process parameters on the properties of TiAlN coatings was studied by orthogonal experiment.The results shows that: on the condition that DC voltage is 100 V,the pulse bias is 400 V,the duty ratio is 30%,the arc current is 50 A and the nitrogen flow is 40 sccm,the coating had relatively better comprehensive performance.Among them,the pulse bias has the greatest influence on the bonding force of the coatings,and the factors impacting according to descending order cover duty ratio,arc current,nitrogen gas flow and DC bias.The factors impacting on the micro-hardness of the TiAlN coatings according to descending order cover duty ratio,pulse bias,arc current,nitrogen gas flow,DC bias.Meanwhile,the factors impacting on the surface roughness of the TiAlN coatings according to descending order include nitrogen gas flow,arc current,DC bias,duty ratio,pulse bias.2.According to the experimental study results of preparation of TiAlN coatings by multiarc ion plating.Further study to prepare high quality TiAlN coatings on the surface of the sample by heat-treating the substrate material to increase its hardness.In addition,using the method of depositing the transition layer and doping Ti element,the DLC coatings was successfully deposited on the surface of the 45 steel.The basic properties of the TiAlN coatings and the DLC coatings tested were,the surface roughness of the TiAlN coatings was Ra=0.05μm,the film thickness was 1.29μm,the bond strength was 43 N and the hardness was 1741 HV.While the surface roughness of DLC coatings was Ra=0.12μm,,the bonding force was 23.2N,and the hardness was 2950 HV,and the film thickness was 2.95μm.After coated treatment,the hardness was significantly improved.The friction and wear performance were studies under the condition of same load and speed,using five pairs of diferents friction pairs: uncoated-uncoated,TiAlN coatings-uncoated,TiAlN coatings-TIAlN coatings,DLC coatings-uncoated,DLC coatings-DLC coatings.Among the various counterbodies,the group A sample of 45 steel substrate and the ball have experienced very serious abrasive wear and oxidative wear,displaying the largest wear volume and the most serious wear;the coated treatment can reduce the friction and wear.Compared with the TiAlN coatings substrate-uncoated ball,the TiAlN coatings on both the substrate and the ball possesses a lower friction coefficient and better friction and wear performance.Compared with DLC coatings substrate-uncoated ball,after the substrate and the ball are deposited by DLC coatings,the friction coefficient is basically not affected,and the wear volume is reduced.3.Based on the design theory of the concave and convex arc LG,the authors has designed a pair of concave and convex arc LG pairs with a transmission ratio of 4.The samples of LG were processed by CNC milling machine for LG.In addition,the transmission performance test was completed on the LG drive test rig.In combination with the process of depositing TiAlN coatings and DLC coatings,the TiAlN coatings and DLC coatings were successfully deposited on the surface of the LG by the means of overall heat treatment of the LG substrate,depositing transition layer and doping metal elements.Through measurement,it turns out that the tooth surface roughness of the LG declined after coated.The transmission efficiency of coated LG is about 2.23%-8.67% higher than that of uncoated LG under the condition of dry friction or oil lubrication;The coated LG can reduce the temperature rising of the lubricating oil,as the coated LG reduces the temperature of the lubricating oil by 3.9°C-6° C in contrast with the uncoated LG.What’s more,the coated LG shows better wear-resistance than uncoated LG. |
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