Scientific bases of the simulation of the process of strengthening the bottom of thread of drill pipes by deep roll

Mikhail V. Pesin PKNM Perm, Russian Federation
Performed computer simulations of the hardening of the hollow carving deep roll. Provides conceptual and mathematical formulation of the problem. As a result of a series of numerical experiments using ABAQUS package evaluation of residual stresses distributions are obtained depending on the degree mounting of the roll.
Materials and methods
Methods of mathematical modelling are used.
From the point of view of the mechanics solid of body being deformed is made setting the three-dimensional nonstationary contact problem of elastic-plastic deformation.
It is possible to conclude that in the process of deep roll thread by roller in the near-surface layers of the material of interturn bottom of thread the regions of the compressive stresses are formed. This circumstance undoubtedly leads to strengthening of near-surface layer and it prevents the appearance of microscopic cracks. From other side, as a result this process in the sub-surface layers of the material of thread can be formed the regions of significant tensile stresses, which can lead to the appearance of the internal micro - and of the macrofissures, which lead to the structural failure. Selecting the optimum parameters of process (geometry of roller and the force of its pressing), it is possible to obtain the favorable for the given construction distributions of residual stresses.
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