Research And Application Of Merchant Cutting Model Based On The Unequal Division Shear Zone

Metal cutting has a dominant position in the machinery manufacturing andprocessing. Mechanism analysis of cutting provides a theoretical basis for theoptimization of cutting parameters, prediction of vibration in the cutting system,monitoring tool wear and analysis of machining error in the production.As two key parameters in the research of cutting, shear angle and cutting force havean impact on each other. Almost all various calculations related to cutting are associatedwith them. Classic Merchant cutting model ignored the effect of shear angle on yieldshear stress and friction angle between tool and chip so that Calculation results are ofteninconsistent with the actual.Firstly, The Merchant analysis model of shear angle was improved well by buildingthe functional relationship of the shear angle for shear yielding stress by using of theunequal shear zone model and Johnson-Cook constitutive model,and for friction anglebetween tool and chip by Schulz empirical formula. The comparisons with results ofclassic shear angle analysis models and foreign scholar’s cutting experimental data, fullyverified the improvements of Merchant cutting theory.Secondly, the model of orthogonal cutting force is theoretically established. Thecomparisons with foreign scholar’s cutting experimental data fully verified the rationalityof the model and the error of results was also fully analyzed. The effects of cuttingelements and tool geometry on cutting force and temperature have been researched by thesimulation of orthogonal cutting made in finite element simulation software. Comparisonand analysis of simulation results verify the validity of finite element simulation model ofcutting and the prediction model of orthogonal cutting force.Finally, the modified merchant cutting model was applied to prediction of turningforce by establishing the theoretical calculation model of turning force. Experimental dataand the empirical formula results of the turning force in the domestic literature verifiedthe validity of the prediction model of turning force proposed in this thesis.Based on the effective improvements of Merchant cutting theory, the theory waswell applied to predict the cutting force of orthogonal cutting and turning. And the resultsfully verified the effectiveness of the modified theory. The scope of application of the Merchant cutting theory has been broadened greatly to a certain extent in this thesis; thefoundation for further in-depth study of the Merchant theory has been laid by this thesis.