| Summary: | <p>In the last decades the so-called combined machining methods based on parallel, serial or parallelserial combination of different types of energy impacts on the billet are designed and developed. Combination of two or more sources of external energy in one method of machining can be directed to the solution of different technological tasks, such as: improvement of a basic method to enhance technicaland-economic and technological indicators of machining, expansion of technological capabilities of the method, increase of reliability and stability of technological process to produce details, etc. Besides, the combined methods of machining are considered as one of the means, which enables reducing the number of operations in technological process, allows the growth of workforce productivity.</p><p>When developing the combined technologies, one of the main scientific tasks is to define the general regularities of interaction and mutual influence of the energy fluxes brought to the zone of machining. The result of such mutual influence becomes apparent from the forming technological parameters of machining and determines the most rational operating conditions of technological process.</p><p>In the context of conducted in BMSTU researches on the combined cutting method with outstripping plastic deformation (OPD) the mutual influence of the energetic components of machining has been quantitatively assessed. The paper shows a direct relationship between the rational ratio of the two types of the mechanical energy brought in the machining zone, the machining conditions, and the optimum operating conditions.</p><p>The paper offers a physical model of chip formation when machining with OPD. The essence of model is that specific works spent on material deformation of a cut-off layer are quantitatively compared at usual cutting and at cutting with OPD. It is experimentally confirmed that the final strain-deformed material states of a cut-off layer, essentially, coincide in both cases. At the same time, when cutting with OPD, a part of the work spent on plastic deformations, is preliminary carried out by an additional mechanical energy source, i.e. by the device for superficial plastic deformation of material. As a result the cutting tool makes only the rest of the work that can facilitate to decrease of cutting force and temperature. The cutting force and temperature define a stress of machining process. Reduction of these parameters when cutting with OPD allows us to rise the resistance period of the cutting tool (up to 2–6 times) and the workforce productivity (up to 1,1–1,6 times) depending on physic-mechanical properties of processed material.</p><p>However, the maximum efficiency of additional mechanical influence is reached only when there is the optimum relationship between the specific energy of superficial material deformation of a cut-off layer and chip formation process while cutting. Experimental data show that at small specific loads of preliminary material deformation an increase of these loads leads to the increase of a part of additional energy during the cut-off layer removal that enables efficiency increase of cutting process with OPD. At the same time, with increasing extent of preliminary plastic deformation of removable material the microhardness of a cut-off layer increases. It has a negative impact on the interaction conditions of tool contact surfaces with a billet material, increases the stress of cutting process, leads to decrease of technical-andeconomic indicators of machining. As a result at the raised specific loads of preliminary deformation negative factors become prevailing and cause, at first, decreasing process efficiency. The further increase of deformation work leads to a negative effect of additional OPD energy influence.</p><p>Thus, an influence efficiency of additional external energies in the combined methods of machining depends on many factors, and the result of such impact on the billet can change over a wide range.</p><p>The considered approach based on the quantitative comparison of the sum of external energy influences and the assessment of their influence on efficiency of machining can be used at optimization and choice of operating conditions for a lot of modern combined methods and manufacturing techniques of details.</p>
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