When cubic boron nitride (CBN) tools are used for hard cutting hardened steel, a large cutting force is generated. This is accompanied by a large amount of cutting heat, resulting in serious tool wear. In this study, we combined surface weaving technology with hard cutting. Design simulations and experiments were performed on three-factor untextured orthogonal cutting by considering parameters such as depth of cut, cutting speed, and feed. Subsequently, the simulation and experimental data were analyzed by using the polar difference, variance, and signal-to-noise ratio methods to determine the best combination of cutting parameters and the degree of influence of each parameter on the cutting force generated during hard cutting. Hardened GCr15 steel with preset surface texture was hard cut using the optimal combination of cutting parameters. Consequently, tool wear was observed, and the cutting forces were measured. The results were compared with those obtained from the equivalent cutting conditions without texture. The results revealed that a minimum cutting force of 71.48 N was obtained in the untextured cutting experiment. Additionally, a minimum cutting force of 44.64 N was measured in the preset surface texture cutting experiment under the same conditions, which was approximately 37.55% lower than the result obtained in the untextured cutting experiment. The tool wear was much higher for untextured cutting than for preset surface texture cutting. The comparative experiments performed, with and without texture, indicated that a combination of surface texture technology and hard cutting can effectively reduce the cutting forces and tool wear and improve tool life.

In order to improve the efficiency of high-speed machining center and shorten its warm-up time, it is realistic and feasible to measure the thermal deformation of the machine tool system and then improve the machining accuracy of the machine by means of compensation. In this paper, a model XKA714B/A CNC milling machine and a 10mm diameter ball-head milling tool are selected. A high-speed camera is used to capture the gray level images of the tool when the machining center spindle speed is working at 1000 r/min. Using MATLAB software, the image edge extraction is coarsely localized by Canny algorithm, and sub-pixel fitting edge detection method is used to precisely locate the tool edge profile. The least-squares method is applied to fit the tool tip circular curve so as to calculate the thermal deformation during the tool preheating process. The results showed that there is a certain connection between the thermal deformation of the tool and the machine running time during the preheating process of the machine tool. That is, in the initial stage of machine operation, the tool axial thermal deformation is larger. In the 6th to 26th min, the tool thermal deformation gradually becomes smaller. At the 26th minute of preheating, the tool deformation reached more than 96% of the total deformation and the deformation rate leveled off. The axial deformation of the tool was measured to be 130.2 um at this time. Inputting the measurement results into the machining center tool holder control system as the compensation value will shorten the machine warm-up and thermal balance time so as to ensure its machining accuracy, which is of practical significance to improve machining efficiency and reduce cost in the actual production process.

Laser cladding technology is used to clad the surface layer of H13 mold steel with Ni60A metal powder coating to solve the failure problem. The study used JMatPro software to extract and fit the thermophysical property parameters of the substrate and the clad material, and then used ANSYS APDL software to qualitatively analyze the distribution of melt pool morphology, nodal temperature versus time course curve and residual stress magnitude during the laser cladding process. Based on the results of the minimum residual stress in the cladding, reasonable scan paths were derived for the preparation of metal coatings on the surface layer of the die steel. The results show that the maximum peak temperature of the cladding process is 2515°C using short path scanning. The cladding layer can form a good metallurgical bond with the substrate at this temperature, with a stress of 406.68 MPa in the scanning direction and 284.45 MPa perpendicular to the scanning direction, which is significantly smaller than the residual stresses of other scanning methods. The residual stress values for the different strategies are from largest to smallest: spiral scan, block scan, long path scan, and short path scan. The results of this study provide theoretical guidance for the selection of paths during cladding processing to reduce the waste of resources and also provide new ideas for exploring the feasibility of metallurgical bonding of materials to substrates.

This paper provides an overview of the commonly used processes and equipment for laser cladding, including pre-set powder feeding, simultaneous powder feeding, wire feeding cladding, and coaxial cladding nozzles. By comparing the above processes and related nozzles, the coating characteristics are summarized for the selection of appropriate methods and equipment in different working environments. Meanwhile, the morphology and properties of the clad layers of shaft parts processed with different process parameters (e.g. laser power, scanning speed, lap rate, powder feed rate) and the influence of the combined parameters are overviewed. The changes and mechanisms of metals, ceramics, and metalceramic composites in terms of hardness, wear resistance, metallurgical bonding, and microstructure are analyzed. In addition, the application of numerical simulation techniques to simulate the temperature and stress fields and to plan the melting trajectory when laser cladding processing is performed on the surface of shaft parts are reviewed. Finally, the problems in the current research on laser cladding of shaft parts are summarized and the development directions are discussed.