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Aeroengine blades are the power components most relevant to the energy conversion process. Due to the harsh working environment, the blades are seriously damaged after service, which affects their dynamic performance. The regrinding of damaged blades can extend their service life. However, the machining flexibility of the traditional grinding machine tool is insufficient to meet the needs of damaged blade repair, and the regrinding track of the blade cannot be directly generated by its theoretical geometric model. In order to solve the above problems, a robot regrinding scheme and trajectory planning method for damaged blades has been put forward. Based on the morphology measurement results of damaged blades, the point cloud reconstruction and regrinding trajectory research were carried out. The precision regrinding of damaged blades was realized. The comparison results of damaged blade morphology before and after regrinding indicate that the surface quality of the blade was improved significantly after regrinding. There are no obvious scratches, deep grooves, and large area adhesion on the repaired surface. The fractal dimension of the surface after regrinding is increased in different directions, which indicates that the surface structure characteristics after grinding are more fine. The average surface roughness of blades after robot regrinding is reduced from 2.67 to 1.59 μm. The profile error after robot regrinding is reduced from 0.35 to 0.16 mm. The research results provide a reference for the repair and manufacturing of blades. [ABSTRACT FROM AUTHOR]

Carbon fiber-reinforced silicon carbide matrix (C/SiC) composites are typical difficult-to-cut materials due to high hardness and brittleness. Aiming at the problem of the serious high cutting force and poor surface quality in conventional milling (CM) C/SiC composite process, ultrasonic vibration-assisted milling (UVAM) and conventional milling tests with a diamond-coated milling cutter were conducted. The results showed that reducing the feed per tooth, cutting depth, or increasing the cutting speed can reduce the average cutting force, and increasing the ultrasonic amplitude, the average cutting force decreases first and then increases. With the assistance of ultrasonic vibration, the maximum reduction rates of average cutting forces Fx, Fy, and Fz were 43.7%, 29.16%, and 68.09%.The ultrasonic vibration assisting effect does not significantly improve the damage of materials such as fiber breakage during processing. The ultrasonic vibration assisting effect improves the quality of processing edges. It is found that reducing feed per tooth, cutting depth, or increasing cutting speed can reduce surface roughness and increasing the ultrasonic amplitude reduces the surface roughness first and then increases. On the whole, the surface roughness of C/SiC ultrasonic vibration milling is slightly smaller than that of conventional machining. [ABSTRACT FROM AUTHOR]

A novel micro-flank milling force prediction model is developed in this study by considering the deflection of tool and workpiece, tool run-out, and material strengthening effects during the flank milling of thin-walled parts. The model of the cutting tool applied in this study is closer to the actual structure and its deflection model is established based on Euler Bernoulli cantilever beam theory under mesoscale. The values of the workpiece deflection are obtained with an online Keyence LK-H020 laser sensor. The Johnson-Cook constitutive model is adopted to estimate the flow stress sJC, which takes in consideration the effects that strain-hardening, strain-rate, and thermal softening have on the flow stress. The mechanistic model is validated by a series of micro-thin-wall experiments with a two-flute KENNA micro-milling cutter as tool and Ti-6Al-4V titanium alloy as workpiece material. Experimental results illustrate that the proposed model performs well for the micro-flank milling forces in the x-direction, with an average error of 4.153%, while the error in the ydirection is slightly larger at 4.458%. [ABSTRACT FROM AUTHOR]

This paper developed a novel, simple-to-use method for detecting tool failure in cutting. An EEMD filtering and restructuring method is launched according to entropy and correlation of cutting force signal in turning high-strength and high-hardness materials using carbide cutting tools. Then, friction coefficient and mean power theories are adopted to characterize tool failure status using restructured cutting force signal. Finally, an automatic detector is proposed using CUSUM control chart to monitor tool chipping and tool wear failure in real time based on previous analysis and can be verified by semi-finishing experiment. Without any need of other sensor equipment and long computing time, the method can be reliable and simple to operate in detecting tool failure in real time. [ABSTRACT FROM AUTHOR]

Chatter is undesirable self-excited vibrations, which always lead to adverse effects during milling process. Selecting a reasonable combination of cutting parameters is an effective way to avoid chatter. Based on the mathematical model of milling process and the Floquet theory, the stable cutting area can be determined. The stability lobe diagrams (SLD) could be obtained by different interpolationmethods. To study the effect of higher order interpolation methods on the accuracy and efficiency of milling stability prediction, the state item, the time-delayed item, and the periodic-coefficient item of the state-space equation are approximated by different higher order interpolation methods, respectively. The calculations show that when the state item is approximated by the third-order Hermite interpolation polynomial, third-order Newton interpolation of the time-delayed item can improve the accuracy of SLD, while higher order interpolation of periodic-coefficient item has negative effect on improving effectiveness and efficiency compared to high-order interpolation of the state item and the time-delayed item. In order to obtain the SLD of milling process more accurately, an updated full-discretization milling stability prediction method which based on the third-order Hermite-Newton interpolation polynomial approximation is proposed in this paper. By dividing the tooth passing period equally into a finite set of time intervals, the third-order Hermite interpolation polynomial and the third-order Newton interpolation polynomial are utilized in each time interval to estimate the state item and the time-delayed item, respectively. The comparison of convergence rate of the critical eigenvalues and the SLD of the proposed method between the existing methods is carried out. The results indicate that the proposed method show a faster convergence rate than that of other methods, and its SLD is more close to the ideal ones with small number of time intervals. [ABSTRACT FROM AUTHOR]

A new machining method for lens molds using tilt electrical discharge milling (ED milling) has been experimentally investigated. Compared with the conventional ED milling, the tilt ED milling enables efficient enlargement of discharge gap by adjusting the tilt angles of the workpiece which results in efficient chip removal and burnish surface quality. On account of this method, micro lens craters were fabricated on the tungsten carbide (WC) and silicon carbide particulate reinforced aluminum metal matrix composite (SiCp/Al) at the optimized machining parameters under various tilt angles of the workpiece. The surface morphology and material removal rate were determined with a laser scanning microscope VK-X100 (KEYENCE, Japan). Experimental results present a 60% rise in surface quality at 25° in tilt ED milling. On the basis of electromagnetic effect, the machining mechanism is analyzed in detail in tilt ED milling for lens molds. [ABSTRACT FROM AUTHOR]

n view of the influence of cutting heat and cutting force on the machining precision of micro-machining, this paper carries out micro-milling temperature measurements and deformation measurement tests based on the theoretical model of temperature field distribution of workpiece and the simulation model of workpiece deformation, providing technical basis for the high-precision machining of precision micro-parts. A theoretical model for the description of the increase in the cutting temperature of the workpiece is established prior to using an inverse evaluation method for solving the heat source intensity iteratively. During the finite element analysis of the distribution of the temperature field and heat distortion, the process of the heat transfer is simplified as a process of applying a series surface heat source to workpiece. Besides, this paper carried on a series of micromilling experiments, used a fast-response thermocouple which has a property of self-renewal for the measurement of the change of the workpiece temperature, the response time of the applied thermocouple is within the magnitude of microsecond, and then, a high-frequency amplifier and an electric potential acquisition equipment were used to gain the transient temperature in the cutting area; meanwhile, a dynamometer is applied to measure the three-directional forces, and finally, the workpiece deformation would be measured by the Keyence microscope. Through the comparison of the simulated temperature and deformation with the experimental results, the simulation model showed considerable reliability. [ABSTRACT FROM AUTHOR]

Single-point diamond cutting is an efficient method to generate the V-shape microgrooves, but the burr forms easily at the microgroove edge when cutting ductile material, especially at small (micron level) cutting depth, and the burr increases with the reduction in the cutting depth. In this paper, the effects of plastic side flow in micro cutting are taken into account to explain the formation of burrs in ultraprecision machining process. The edge radius of diamond tool is measured by scanning probe microscope (SPM), and the mechanism of the burr formation is revealed with considering the edge radius of diamond tool and the cutting depth in machining nickel phosphide (Ni-P). In this way, an approach to restrain the burr formation is established so as to generate fine microgrooves. [ABSTRACT FROM AUTHOR]

In order to promote the integrated application of the Internet of Things and cloud platform computing technology in intelligent manufacturing system, a cloud platform of cutting database was established in this paper. With the help of multi-sensor and distributed storage technology, mathematics model and data mining algorithm, functions of fast accessing and storing cutting data, intelligent modeling and analysis, efficient mining and optimizing processing parameters can be realized in the system, solving the key problems of analyzing cutting force and controlling surface quality in turning difficult-to-cut materials. Data equipment and users in the system were connected as a whole through wireless network, which can provide intelligent service of data querying, modeling, and optimizing through the cloud server. The study made up for the drawbacks in current intelligent database system such as oversimplified platform architecture, low level of intelligence, and low utilization of historical data, providing an efficient method of managing and applying big data in cutting process for the production system. [ABSTRACT FROM AUTHOR]