Influence of spatial welding on the accuracy of working dimensions of drilling chisels of cutting-erasing type

Abstract

The article considers the problem of PDC drill bit quality provided during manufacturing. Schemes of welded joint making are theoretically substantiated based on theoretical research, computer modelling and experimental tests for L-shaped details like PDC drill bit blades. The recommendations to provide welded joints for L-shaped details are developed. Based on the elastic-plastic analysis, means to reduce thermal longitudinal and transverse internal deformations caused by a heat source moving along the weld are theoretically substantiated. Simulation models have been developed to assess the influence of welding thermal action and residual deformations on accuracy of drill bit external diameter for different schemes of welding. Based on the developed models, it is shown that the thermal welding deformations of spatial curved welds are significant, and relate mainly to the blades rather than the body (i.e. less massive parts); there are bends, turns and skews of the blades. Finite-element simulation of the bit body – welded blades stress-strain state was performed sequentially in the environment ANSYS (academic license) – Transient Thermal (determination of heat load) and Static Structural (determination of deformations and stresses). It is established that the smallest deformations of the blade are observed for the welding scheme, which envisages making the weld from the point of cylindrical and ellipse surface pairing. The results obtained by simulations were confirmed by experimental data and this made possible substitution for a rational scheme of drill bit body – blade based on the method of reverse deformation, to ensure the accuracy of the product as a whole. Recommendations for weld joint making for spatial curved welds of complex products with requirements to their accuracy allow increasing the accuracy of the technology by minimizing the thermal load and residual thermal deformation of the joints.