Key Engineering Materials Vols. 589-590

Abstract: Stress analysis on wedge zone is an important step for micro-cutting tool design. The effect of stress borne by the cutting tool upon the radius of its blunt edge was analyzed, when the tool machines with minimum cutting thickness which is confined within 10-4-10-2mm. It shows that the minimal extreme value of the radius of blunt edge is existed in the process of micro-cutting tool design.

Abstract: The substrate temperature distribution in hot filament chemical vapor deposition (HFCVD) diamond films growth on drill tools in large quantities are simulated by the finite volume method (FVM), adopting a detailed 3-D computational model corresponding with the actual reactor. Firstly, the correctness of the simulation model is verified by comparing the temperature data obtained from the simulation with that measured in an actual depositing process, and the results show that the error between them is less than 3%. Thereafter, the influences of several parameters are studied, including the filament separation (D), the length of the filament (L) and the filament-substrate distance (H). The simulation results show the three parameters have different effects on the distribution of temperature field. The influence of D is the greatest, L is followed and then H. The simulation has important theoretical guidance on both the development of HFCVD deposition equipment using for the diamond coating on tools with complex shapes in large quantities and the research of related production process.

Abstract: The tribo-map of typical CVD diamond film exhibiting the interaction between the wear rate, friction coefficient and friction conditions would help optimize the working parameters of CVD diamond film coated tools and wear-resistance components. The tribological behaviors of CVD diamond films sliding against Si₃N₄ balls were studied by conducting a group of tests on the ball-on-plate type reciprocating friction tester under several sliding speeds and normal loads in the ambient air. The examined MCD films and NCD films were deposited on square flat WC-Co substrates. The worn surfaces on the diamond films were observed by SEM and the wear volumes of diamond films were measured by surface profilometer. The results indicated that the influences of the sliding speeds and normal loads on the friction coefficients for both MCD films and NCD films were obvious. When the load was 6 N, MCD film obtained the lowest friction coefficient of 0.11 at the sliding velocity of 0.2 m/s, while for NCD film the minimum value was 0.07 as the sliding speed was 0.13 m/s. The wear rate of the MCD film decreased as the load improved, while for the NCD film, the tendency was just the opposite. The influence of sliding speed on the wear rate of the MCD films was not distinct, while for the NCD films, the sliding velocity greatly affects their wear rate. The wear rates of most NCD films were around 0.2×10^-7 mm³/Nm, while those of the MCD films fluctuated from 0.6×10^-7~1.6×10^-7 mm³/Nm. To elucidate the effect of operating environment on wear mechanism of diamond/ Si₃N₄ tribo-pair, the tribo-map was developed.

Abstract: Samples of DLC thin films with different Cu concentration were prepared by using a Cu target and different number of graphite target，or adding a grid before the Cu target. The results show that the hardness and stress decreases with an increase of Cu concentration (below 6.3 at.%). When Cu concentration increases from 6.3 at.% to 17.8 at.%, the hardness and stress keep almost constant, and the friction coefficient increases gradually and slowly, as well as the wear loss.

Abstract: This paper presents the mathematical model of helical groove of the end mill according to the differential geometry and meshing principle based on the grinding wheel attitude. The profile of the helical groove can be precisely calculated using a given wheel attitude and the relative motion between the workpiece and the grinding wheel.The relation between the grinding wheel attitude and the rake angle can be obtained through adjusting the grinding wheel attitude angle.And the accurate 3D model of helical groove was generated in the SolidWorks.The research shows that the grinding wheel attitude is the main factor that affects the rake angle of end mill.There is a linear relationship between the rake angle and the grinding wheel attitude. The smooth and accurate 3D model of helical groove lay the foundation for studying the cutting performance and dynamic characteristics of end mill.

Abstract: For the low efficiency and poor surface quality problem of finishing ruled surface blade in the traditional method, tapered ball end mill cutter location optimization methods had been proposed to ensure that the envelope surface of tapered ball end mill is close to intractable ruled surface blade as much as possible. First, the tapered ball end mill initial cutter location was obtained based on the improved two point offset algorithm. Then to realize the cutter location optimization calculation, selected three point in tool axis to slide for the target of the minimum range between cutter envelope surface and blade surface. Finally, the blades instance was calculated according to the obtained tool center point and optimized tool axis vector. Simulation and experiments verified the effectiveness of cutter location optimization method proposed in this paper.

Abstract: Titanium alloy materials are widely used in the field of aero-engine, the complex surface forming of key parts usually use the ball end mill. First, optimized and designed tool based on the main geometric parameters of the tool, the experimental researching on solid carbide ball end mill milling TC4 titanium alloy was performed based on orthogonal combination of geometric parameters. Second, made a concrete analysis of the milling force collected in the experiment, tool geometry parameters were optimized based on the theoretical and practical. Then analyzed the optimized tool milling force changing rules under finite element milling simulation. Influence of milling parameters on milling force was analyzed with the single factor experiment for the optimized tool, milling parameters were optimized by drawing the force curve. The above studies provide a reference for the actual production of titanium alloy semi-finishing and finishing in tool design and milling parameters selection.

Abstract: Cutting database; Image processing; Large cylinder section; Tool life evaluationAbstract. This paper builds the optimization database system of cutting parameters for large cylinder section. The system is based on Browser/Server mode (B/S). The system can optimize cutting parameters, store knowledge, query information, maintain system, assess tool life and design tool. It completes the optimization of cutting parameters, according to the cutting parameters to design and evaluate the properties of cutting tools. It introduces tool life evaluation, data analysis and storage model. This paper also points out the method of tool life evaluation to achieve the collection of data of the tool cutting performance and the accurate and scientific evaluation of tool life.

Abstract: Because of the influence of tool geometry, when the fine slotting cutter is cutting, the cutting condition at every point of the type line cutting edge varies, which will lead to uneven loading on the whole cutting edge. Finally, partial earlier failure of the cutter would be initiated. To solve this problem, this paper presented a cutting simulation of the slotting cutter with zero rake angle, which could draw the variation law of cutting force at different locations on the type line. On the basis of micro-elemental milling force model, this paper established mathematical models of different sections along the turning axis of cutting tool, in which the relief angle changed to adapt to the variation of cutting force. The variation law of relief angle could be found by utilizing liner regression analysis. Then the 3D model of tool could be reconstructed. According to cutting experiment analysis of the reconstructed model, the distribution of cutting force at every point of the cutting edge tended to be reasonable, and the rationality of the optimal model was proved. This will offer a new idea to improve the level of slotting cutter design as well as a reference of complex forming cutter design that was completed by using the modern design method.

Abstract: The surface quality of cylindrical rollers has a great influence on the working life of rolling bearings. In the paper, double-side lapping machine and flannelette pads are applied to polish the cylindrical surface of rollers. After 20 min polishing, rollers with smooth surface are obtained and the roundness of the rollers have a improvement of about 0.3 μm, which means that the polishing process based on double-side lapping method can effectively improve the surface quality and geometric accuracy of cylindrical rollers.