Advanced Materials Research Vols. 538-541

Abstract: According to the components, mechanical properties of difficult-to-process material (26NiCrMoV145)as well as characteristics of high-speed machining, modelling and prediction of cutting force in high-speed milling is studied. Based on geometry model of ball end mill edge line, milling force model of helical ball milling cutter is established by theoretical analysis and empirical coefficient. Then, simulation prediction of cutting forece is conducted under different circumstances. The experimental result shows that the predicted cutting force is consistent with experimental data and the established model is reasonable. The article contributes to the milling of difficult-to-process material, which improves security and productive efficiency in processing.

Abstract: This paper presents a simulation system for the cutting surface roughness based on the feed rate, spindle speed and tool material, shape and other parameters. The reasons affecting the surface quality in machining is explained. Using classic formula and empirical data, the mathematical model of the surface roughness is built to predict surface quality of parts. The paper proposes a method of the simulation system design for the machined surface quality. The simulation results could give a guide to the choice of cutting parameters in CNC machining.

Abstract: This article introduced the Nomex honeycomb composite material, analyzed the insufficient of the traditional milling process in Nomex honeycomb composite processing, and proposed using the characteristics of ultrasonic cutting combined with NC technology to process the honeycomb composites. It analyzed the forming principle of the corresponding curved surface according to the special ultrasonic cutting tool and cutting method, and established a corresponding error.

Abstract: This article focuses on the drilling of carbon fiber reinforced plastics (CFRP) laminate with brazed diamond core drill under no cooling condition. The effect of grit size, wall thickness of core drill and feed speed on machining quality at the hole exit is studied. The experimental results indicate that the grit size has a significant influence on the diameter of the hole exit. The expanding factor of diameter at hole exit increases with the decrease of grit size. Both large wall thickness and high feed speed lead to serious drilling-induced defects of the hole exit. The drilling-induced defects at hole exit are transformed from broken-edge and burr to local tear.

Abstract: The ultrasonic processing to sometimes also call that a Ultrasonic machining, it can not only processing cemented carbide, hardened steel, and other hard-brittle metal materials, and better Co-processing in glass, ceramics, germanium semiconductor, marble, a non-conducting silicon, and other hard-brittle non-metallic materials, but also can be used in cleaning, welding, testing, measurement, metallurgy and other aspects of this paper to study the principles of ultrasonic processing and The application of ultrasound to explore Development, the modern processing technology of the latest trends.

Abstract: An experiment equipment for indentation test on the partial material was designed, which was acted by ultrasonic coupling with the pressure load. In the pressing experiment, the 7050 aluminum alloy and Hastelloy C-276 nickel-based alloy were chosen, and the effect principle and mechanism of energy transmission of ultrasonic vibration pressing on the rheological behavior of the single point of the material were studied. The results show that, ultrasonic energy can reduce the load and promote the efficiency for the plastic deformation process of material, which is performed by a single point load. This work declares that, when ultrasonic field is added to the partial rheological interface, the metal in the deformation zone slides in the form of pulses. Meanwhile, the grains of sliding material perform a resonance response, which is encouraged by the sliding pulse, and the high energy shortwave phonon generated. It spread to the high density dislocation crystal boundary in the deformation zone, leading the energy jump of those grains. Finally, this energy is translated into the plastic distortion energy of the metal.

Abstract: In this paper, the machining properties of Picea spp., compared with Castanopsis hystrix, were tested. Their properties were conducted according to the criteria ASTM D1666-87 and the test on crosscutting is referred to the method established by New Zealand Forest Research Institute. The results show as follow: The machining properties of Picea spp. and Castanopsis hystrix show excellent in the planning, sanding, boring, shaping and crosscutting, but in the mortising properties, Picea spp. which was a bit poor shows fair and Castanopsis hystrix shows good. The properties of Picea spp. were in an all-round way better than Castanopsis hystrix. In the machining performance comprehensive evaluation system for full marks 50 points, their comprehensive marks were separately 45.5 points and 44.4 points.

Abstract: Fuzzy c-means clustering algorithm was introduced in detail to classify a set of original sampling data on drilling wear in this paper. Simulation results by Matlab programming show that drill wear modes can be successfully represented by four fuzzy grades after fuzzy clustering and classification. The analysis result indicates that fuzzy description can properly reflect drill wear, FCM can effectively identify different wear modes. It is suggested that the severe degree of membership of wear be used as a criterion for replacement of a drill. This technique is simple and is adaptable to different environment in automatic manufacturing

Abstract: New technology has been developed to permit repair work on one of the main and most important components of shipboard diesel engines—the crankshaft—without removing it from engine. It is no longer necessary to dismantle the whole engine and as such, this innovative technology significantly reduces repair costs. However, the impact of this novel grinding technology on the surface roughness parameters is not yet clear and requires additional scientific analysis. Machining technology and cutting regimes, as well as the material of the tool being used, all have a direct impact on the surface texture and consequently on the quality of the repair as a whole. Therefore, to realise this innovation, it is necessary to carry out additional research into the impact of grinding technology parameters on the surface formation of the crankshaft main and crankpin bearings (journals). Current roughness research is usually restricted to two-dimensional surface roughness parameters—simple profile analysis. Nevertheless, in practice any surface has three dimensions, which give it a characteristic texture. It is therefore also necessary to create a new theoretical 3-D surface model for crankshaft bearings surfaces. This will allow us to analyse the full-scale impact of technological grinding regimes on the actual three-dimensional surface. This study revealed that optimal 3-D surface roughness (texture) parameters for crankshafts depend upon: the mean arithmetical deviation of the surface, RaT, and two perpendicular surface spacing parameters between the peaks Sm1 and Sm2. Multifactorial research shows individual significance of each technological regime and overall impact on the 3-D parameter RaT, Sm1 and Sm2. The approach and methodology adopted for the experiments enabled us to identify the optimal and most appropriate grinding technology parameters.

Abstract: During mechanized continuous mining, the depth of cut (DOC) of picks on the drum directly affects the forces exerted on the picks, as well as the forces and torque acting on the drum. Therefore, accurate analysis of DOC of individual picks is needed to optimize the design of the drum and the operation of the continuous mining machine. However, the current existing models cannot meet this need, because they only take into account drum advance speed per revolution and the spirals of picks or the picks per cutting line. In this paper, we attempt to improve the accuracy of DOC calculation by considering drum advance speed per revolution, cutting patterns, the interactions between picks and the profiles of picks. Furthermore, the change of DOC of individual pick in a cutting cycle is also analyzed. The proposed models can help calculate pick forces and drum’s reactive forces more accurately. They also enable those empirical force models which are developed based on the experiments with small DOC to be used for force analysis with larger DOC more accurately.