Design And Optimization Of Small-diameter Turbodrill Reducer

In the drilling of small hole and deep well,the formation structure is very complex and the rock drillability is poor.In order to ensure the rock breaking efficiency of the bit,the output of turbodrill reducer is needed to be large enough torque.However,due to the influence of the well hole,the radial size of the turbodrill reducer is small,and the working life of the reducer is easily reduced due to insufficient strength under heavy load conditions.Therefore,a 127 mm small diameter turbodrill reducer was designed and trial-produced,and the strength of the asymmetrical tooth gear was studied around the load bearing optimization problem of the reducer.In view of the technical difficulties of "small outer diameter and large torque" of the turbodrill reducer,this paper gives an effective design scheme,and provides a new idea for the load-bearing optimization of the turbodrill reducer.In order to realize the large torque transmission of the small diameter turbodrill reducer,a series planetary gear reducer was designed,which split the load through the series structure of multiple NWG planetary transmission units.This transmission scheme not only ensured the radial dimension of the reducer,but also greatly increased the output torque.Through the strength analysis and structural optimization of key bearing parts such as gear and transmission shaft,the stress of bearing parts is within the allowable range,which verifies the feasibility of the design scheme.In addition,in order to test the output performance of the turbodrill reducer,the hardware module of the reducer test bed is designed,and the corresponding performance test scheme is drawn up.In order to further optimize the loading capacity of the 127 mm turbodrill reducer,the strength influence mechanism of the asymmetric gear was studied.By means of theoretical analysis and ANSYS finite element method,the influence law of the tooth profile parameters on the contact strength and bending strength of the asymmetric gear was investigated.The main research results are as follows:(1)Increasing the working side pressure Angle of the asymmetric gear can increase the radius of curvature of the gear meshing point,thus effectively optimizing the contact strength of the gear,and avoiding the thinning of the tooth tip caused by the symmetric high pressure Angle gear;(2)The working side pressure Angle,modulus,tooth root fillet radius and other tooth profile parameters all have influences on the bending strength of the asymmetric gear.The detailed rules are shown in the paper.Reasonable selection of the above tooth profile parameters can effectively enhance the bending strength of the tooth root.(3)The influence of the working side pressure Angle on the contact strength and bending strength of the gear can be divided into a significant decline stage of 20°～30° and a gentle stage after 30°,indicating that the working side pressure Angle of the asymmetric gear should be selected reasonably during optimization.If the pressure Angle exceeds 30°,the strength optimization effect of the gear will be weakened.A multi-objective optimization model was established,which took the contact strength and bending strength of the asymmetric gear as the optimization objectives,and the gear matching,transmission ratio and radial dimension as the constraint conditions.By using the Matlab genetic optimization algorithm,the optimal design scheme of the asymmetric gear tooth profile of the turbodrill reducer was obtained.The finite element analysis verifies that the optimization results accord with the strength influence law of the asymmetric gear,which provides effective data support for the gear optimization of the reducer.