Study On Design And Modification Method Of Non-cylindrical Gear

Non-circular gear is a special kind of gear,because of its non-circular pitch curve,it can achieve a lot of special variable transmission requirements.Therefore,non-circular gears are widely used in various fields of machinery industry.For example: planetary gear of differential in high mobility vehicle,oval gears in the liquid flowmeter,gear rack in variable ratio steering,gears in variable gear pump.While,non-circular gear is also widely used in many light industrial machinery such as printing machinery,textile machinery and cigarette machinery.Because of the pitch curve of non-circular gear is complicated and various,non-cylindrical gear has no accurate tooth equation of profile cuve,which leads to the difficulty of the accurate design and modeling method.The modification method of circular gear also can't be used in non-cylindrical gear.For this reason,this paper studies the design and modification method of non-circular gear.In this thesis,first of all,according to the design requirements,the parameters and the pitch curve of non-cylindrical are design and programmed in MATLAB,and the pitch curve is checked in MATLAB as well.After that,we obtained the positional relationship between the gear cutter and the non-cylindrical gear according the principle of non-cylindrical gear and the knowledge of differential geometry.The mathematical model of the tooth profile envelope of the non-cylindrical gear is obtained by using the positional relationship and the gear shaper cutter equation in MATLAB.Secondly,a numerical algorithm is proposed to calculate the tooth profile of non-cylindrical gears based on the tooth profile envelope model.In this algorithm,the polar and polar angles of the tooth profile of the gear cutter are taken as the criterion.We can screened points that located in tooth entity of the gear cutter in the process of cutting non-cylindrical in MATLAB.Then we take these points as the points of non-cylindrical gear tooth and extract the boundary points of gear tooth as the profile points of non-cylindrical.Finally we construct the tooth profile curve and establish the three-dimensional model in Pro/E.We established different types of non-cylindrical gear transmission models by using this general numerical algorithm,then we carried out the motion simulations in ADAMS,which results verified the correctness of the algorithm and the accuracy of the model.Finally,based on the numerical algorithm of the non-cylindrical gear tooth profile,this paper presents a modification method of changing pole diameter and changing polar angle modification.By means of changing pole angle modification method,the cutter of the non-cylindrical gear is modified to realize the modification of the non-cylindrical gear.Then the dynamic simulations of the non-cylindrical gear transmission models before and after modification are carried out in the CAE software ABAQUS,which results verified the correctness of the modification method.