At present, the selection of optimal technological parameters for laser powder bed fusion (LPBF) is determined by the requirements of the fusion process. The main parameters that are commonly varied include laser power (P), scanning speed (v), hatch spacing (h), and layer thickness (t). The productivity of the LPBF process (the increment in the fused volume of the material) is equal to the product of the last three parameters, and the mechanical properties are largely determined by the volumetric fusion energy density, which is equal to the ratio of laser power to productivity. While ensuring maximum process productivity, it is possible to obtain acceptable quality characteristics—mechanical properties, surface roughness, etc.—for a certain range of LPBF technological parameters. In these cases, several quality characteristics act as constraints on the optimization process, and productivity and the key quality characteristics become components of the objective function. Therefore, this article proposes a formalized representation of the optimization problem for the LPBF process, including the derivation of the objective function with the constraint matrix, and provides a solution to the problem using the linear programming (LP) method. The advantages of the proposed method include the guaranteed convergence of the solution with an unlimited number of constraints; the disadvantage concerns the adequacy of the solution, which is limited by a relatively narrow range of parameter changes. The proposed method was tested in determining the optimal LPBF parameters for an HN58MBYu powder LP model that included 13 constraints and an objective function with two target parameters. The obtained results made it possible to increase the productivity by 15% relative to the basic technological parameters.
The possibility of developing a technique for calculating the wear of the fl ank surface of mills is shown on the basis of a generalized friction model, taking into account the entire complex of the main external factors acting and the physical and mechanical characteristics of the materials of the interacting surfaces of the tool and the workpiece. The calculated dependence of the wear values, the infl uence of some hard-to-consider factors is supposed to be taken into account by the experimentally determined proportionality coeffi cients and the index of the calculated ratio, has been proposed. Keywords: generalized model of friction and wear, the teeth of the mill, the calculated dependence.
The paper describes determining the optimal direct laser deposition mode when processing the results of a two-factor experiment by the steep ascent method. The dependence of the ultimate tensile strength on the volumetric energy density and the lateral pitch was chosen as the target function.
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