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The tribological behavior of tool wear is closely related to its dynamics during turning large-pitch screws. Under the action of nonlinear multi-strong field coupling, the chatter between the tool and the workpiece changes the contact relationship between the tool and the friction pair. This leads to the dynamic change of the tribological system and the change of the tool wear morphology. Through the cross-correlation analysis of the contour curve of tool vibration signal and tool wear over the time, the nonlinear relationship equation was established. By the simulation model of large-pitch screw turning under vibration, the causes of vibration frequency and amplitude affecting temperature field, stress field, and tool wear were analyzed. The tool wear model of large-pitch screw turning under the influence of vibration was constructed, and the coupling mechanism of tool vibration and wear was clarified. The error is less than15%. By optimizing the cutting parameters, the influence of vibration on tool wear was restrained, and a tool wear control method was proposed. Eventually, with this tool wear control method, edge wear becomes more uniform and tool life increases. [ABSTRACT FROM AUTHOR]

The machining error of heavy-duty vertical lathes is significantly affected by geometric errors. Thus, this paper investigates the measurement and modeling of heavy-duty vertical lathes for error tracing. Specifically, the heavy-duty vertical lathe geometric error is measured by a laser interferometer, its error value is identified, and the polynomial model of the error value is established using a polynomial high-order fitting method. After that, based on the multi-body system theory, the heavy-duty vertical lathe bed and cutting tool topology is created to describe the pose relationship of each component of the heavy-duty vertical lathe. Then, the geometric error model of the heavy-duty vertical lathe is established using a homogeneous transformation matrix, and the virtual machined rotary surface model is constructed by combining the cutting tool trajectory and the eccentric installation of the workpiece. Each geometric error is input into the virtual model to compare its effect on the machining error of the workpiece. Among the 19 errors traced, the X-direction positioning error of the horizontal slide, the X-direction straightness error of the vertical slide, the X-direction straightness error of the workbench spindle, the X-direction installation eccentricity error of the workpiece, the rotation angle error of the horizontal slide around the Y-axis, and the rotation angle error of the workbench spindle around the Y-axis are the key errors heavily impacting the machining error of the heavy-duty vertical lathe. According to the influence of each key error term, the mapping relationship between the error term and the machining error of the workpiece is established to complete the error tracing. [ABSTRACT FROM AUTHOR]

Cutting vibration has become a major problem to the limited high-efficiency and high-quality machining. The non-equal tooth effect of the variable pitch end mill can better adjust the phase mechanism of the system and suppress chatter. Therefore, an in-depth study is required to make full use of the vibration reduction property of the milling cutter. Considering the regenerative chatter mechanism, a nonlinear milling force model for the variable pitch end mill is analyzed first, then the time-varying coefficient matrix of the cutting force is developed, and finally, a dynamic model with multiple delays is proposed. The developed model is evaluated from the perspective of chatter stability, and the limiting cutting depth is determined by using the frequency domain and semi-discretization methods. Combining with the system dynamic detection tests, the dynamic model parameters and cutting coefficients are determined for predicting stability. The analytical solutions of stability are benchmarked against the results of the time domain digital simulation, and both predictions are validated through cutting tests. The relationship between the limiting cutting depth and pitch parameters is proposed by assessing the effect of multiple delays. A method for optimal pitch parameters is developed to maximize the stability limit. It is shown that the proposed method can improve the chatter stability of milling cutters and alleviate cutting vibration, which can play an important role in improving the machining efficiency and surface quality of workpieces, and enhancing the technological level of main components. [ABSTRACT FROM AUTHOR]

As a typical vibration-damping tool, the variable pitch end mill changes the dynamic characteristics of the system as the material is removed, which alters the cutting vibration response and affects the workpiece's quality. In this paper, first, a cutting force model for the variable pitch end mill is established, while the cutting force coefficients are determined through the cutting experiment. The accuracy of the cutting force model is revealed by comparing the simulation with the experimental results, and then the frequency spectrum characteristics of the cutting force are analyzed in the presence of various spindle speeds and interdental angles. Second, the dynamic characteristics of the machining system are analyzed by the modal test and the finite-element analysis. In continuing, amplitude–frequency characteristic curves are carefully examined to get the modal parameters of a variable pitch end mill and aircraft aluminum alloy workpieces of different thicknesses, and subsequently, the mode shapes are determined by modal analysis. Finally, based on the above cutting force model and the system modal parameters, the free and forced vibration responses of the workpieces with various thicknesses are analyzed by employing dynamic system modeling simulations. The relationship between material removal and vibration response is obtained, which indicates that the vibration amplitude of the machining system gradually increases as the workpiece's thickness lessens. The obtained results of forced vibration response analysis for thin-walled workpieces machined with various interdental angles reveal that the fourth type of end mill has the best vibration damping effect. [ABSTRACT FROM AUTHOR]

The surface quality of the workpiece has a great impact on the performance of the product. It has always been a key issue of the manufacturing discipline. The different wear levels of cutting tools determine the surface quality of the workpiece. Therefore, the work of this article is to establish a model for calculate the surface quality of the workpiece after milling. First, by defining the tool wear area S and the wear position angle ψ, the cutting edge line model of the tool is determined. Based on the tool motion trajectory and roughness calculation principle, a milling topography simulation roughness model considering tool wear is obtained. Secondly, the tool wear parameters were calibrated with the help of image detection methods, and the predicted values obtained by the model were compared with the experimental values. The law of the influence of the tool wear area S and the wear position angle ψ on the roughness parameters was obtained. Finally, the least squares support vector machine LS-SVM was used to verify the error of the roughness model of the milling topography simulation, and the result showed that the average error of the model was 8.68%. [ABSTRACT FROM AUTHOR]

Elements in the carbide tool and workpiece material will diffuse during the cutting process, thus affecting tool life. To address the problem of diffusion wear on the rake face of the carbide tool, a cutting test scheme was proposed to analyze the heat and force conditions of element diffusion. A static clamping diffusion experiment of the tool and workpiece material was conducted to obtain diffusion data on the tool-chip element. Based on the analysis of element diffusion in the contact area of the tool-chip during the cutting process, the theoretical model of element diffusion in the tool was established using the Gaussian solution of Fick’s second law to determine the threshold value of the element concentration when the tool was damaged. The hardness of the tool surface was also measured and analyzed. The results showed that the wear depth of the rake face can be predicted using the established element diffusion model, whose results are consistent with the experimental findings. The element concentration on the crescent surface at the tool rake face remained constant under different cutting time, while the loss of W was more obvious. The experiments of the diffusion couple verified that element diffusion causes a decrease in the hardness of the tool surface, and tool hardness increases with greater distance from the bonding surface, which eventually reaches the hardness of the tool substrate. The research results lay a theoretical foundation for investigating the failure process of carbide cutting tools and predicting their service life. [ABSTRACT FROM AUTHOR]

In machining operation, the surface quality is one of the most important requirements for many workpieces. Because of the special physical and chemical properties, good-machined surface quality becomes a key issue to solve in machining Inconel 718. In this paper, PVD-TiAlN-coated carbide tools were used to turn Inconel 718. Based on observing the tool wear and machined surface morphology, the main factors affecting surface quality at different cutting speeds were analyzed. The optimal cutting temperature was calculated, according to the above analysis and Archard adhesion wear model, and further cutting parameters optimization was conducted, on the basis of the proposed optimal cutting temperature. The optimized cutting parameters based on optimal cutting temperature can be considered to improve surface quality. [ABSTRACT FROM AUTHOR]