Mechanical Study On Assemblage Of The Commutator In Locomotive DC Motor

Commutator is a key component of the DC motor. It represents in fact most of the failures because of its mechanical complexity. In the present thesis, the assembling processes of ZD105 locomotive motor are analyzed and simulated systematically by finite element methods (FEM). Variety of the factors in real working conditions is taken into account. It constitutes a helpful reference for the design of commutator in suitable configuration, materials and manufacturing processes.The tests on different materials are carried out to calibrate the material behaviors for FEM analysis. Five metal materials and three mica materials are tested. The curves of strain-tress relationship of mica appear to be the concave ones. The usual numerical integration methods for metal constitutive law are no longer available. The hyperelastic constitutive law provided by ABAQUS is hence adopted for the simulation of mechanical behaviors of mica materials.The main operating component in commutator is a layered structure in ring shape, pilled repeated by 372 mica sheets and 372 copper bars. Such a configuration in hundreds of the thin chips is not realistic to mesh in the local details. The equivalent properties of the layered ring structure is then determined and used for global simulation of the commutator. In the present work,. the layered structure is regarded as a homogeneous material in analysis of the whole commutator. Equivalent constitutive law is determined by the analysis on detailed compositions. As the copper and mica materials in layered structure represent both the non-linear behaviors, the FEM method is used by ABAQUS software to determine their global response. The Ogden N3 hyperelastic law is finally adopted to describe the equivalent behaviors. The further work is conducted to investigate the effect of thickness proportion of the copper bars and mica chips on the equivalent behaviors. The assemblage of commutator in DC motor is a very complicated manufacturing process. In the present analysis and simulation, it is divided into three processes according to the assembling sequence: compaction of the layers in initial shape by circular clampers and lathing the compaction in exact shape, assembling the whole commutator on the shaft with all the components, rotational aging under periodic high temperature and regulation of the relaxation. The results obtained by simulation of the compaction and lathing are assigned to be the boundary conditions for the simulation of layered structure in whole assemblage process, for the purpose to analyze the effect and removal of clamping apparatus. The simulation of rotational aging and regulation is based on the results of assembling simulation. It determines the maximum rotational speed for commutator under the condition that there exists still the compaction in layered structure.