Advanced Materials Research Vols. 189-193

Abstract: High speed milling hardened mould steel (above HRC50) at pocket corner generates the cutting forces increase and vibration gets fiercely because of the sudden change of cutting direction. It will cause serious wear and possible breakage of cutting tool, and poor quality of parts. Hence, the need to select reasonable cutting parameters and adopt appropriate cutting strategies will help them to achieve their goal. In this paper, the effects cutting parameters including cutting speed, pocket corner angle, feed rate per tooth and radial depth of cut on cutting force and vibration are studied. The results show that sharper pocket corner results in the increase of cutting force and makes vibration strong. Cutting force increase with the increase of cutting speeding, feed per tooth and radial depth of cut. The optimum of cutting speed leads to the decrease of vibration. It is proposed that cutting parameters should be optimized to improve tool life and processing efficiency.

Abstract: The method of anti-hydrated of CaO-MgO was investigated in this paper. Take the magnesium calcium granulated substance as raw material, through studied material granularity, weight and other factors to influence anti-hydration of magnesium calcium. It is discovered that granularity of material influence on the anti-hydration of CaO-MgO, and confirm that this method is reliability and validity.

Abstract: Making processing the surface of special-shaped end socket which is made of zirconium diboride ceramics cost too much by old method.A series of processing experiments were conducted and a advance cnc machining technique was described in this paper. Most reasonable machining parameters were given after orthogonal test and analysis of range.To use these machining parameters in processing the surface, the processing cost can be reduced greatly with a high machining efficiency.

Abstract: SiC ceramics have been widely used in a variety of areas due to the excellent physical and chemical properties. However, the process of SiC ceramics is difficult and high-cost, molecular simulation is an effective and feasible method to study the nano-process of SiC ceramics. In this paper, a molecular model is presented to simulate the stress and energy in the nano-cutting of SiC ceramics. The influences of the cutting depth and cutting speed on the kinetic energy and potential are analyzed. The results show that potential energy increases with the decrease of the cutting depth. Kinetic energy increases with the increase of the cutting speed. The results are very helpful for improvement the level of ultra-precision processing and nano-processing of brittle ceramics.

Abstract: It is widely recognized that the chipless finishing process — the burnishing process can be used efficaciously to reduce the surface roughness of components. But most of previous works published concentrated on the conventional burnishing process and experimental researches in the last few years. There are some limitations on the conventional burnishing process in reducing surface roughness. Ultrasonic elliptical vibration burnishing (UEVB) process is proposed. Theoretical model is established to analyze theoretical surface roughness. Steel 45 was selected as material for making the specimens in the experiments and a new device developed by us was used for the burnishing process. The comparison shows that the surface roughness in describing the burnishing process is better than the conventional burnishing process obviously.

Abstract: Gear form grinding is an efficient finish machining method for the gears with hard face. There are many factors which have an influence on tooth error in grinding process. In addition to the form error of form grinding wheel, the radial feed depth of grinding wheel has large impact on the tooth error. Based on the principle of gear form grinding, the influence of wheel feed depth on tooth error is analyzed theoretically. The magnitude of error is also analyzed quantitatively according to the simulation result obtained by means of tooth error analysis module, which is developed based on VC + +6.0 software analysis. The research result has a certain reference value for preparing CNC form grinding process and setting machine tool properly.

Abstract: High-efficiency abrasive machining is one of the important technology of advanced manufacture. Combined with raw and finishing machining, it can attain high removal rate like turning, milling and planning. The difficult-to-grinding materials can also be ground by means of this method with high performance. In the present paper, development status and latest progresses on high efficiency abrasive machining technologies relate to high speed and super-high speed grinding, high efficiency deep-cut grinding, hard and brittle materials high-efficiency grinding, powerful grinding and belt grinding were summarized. The efficiency and parameters range of these abrasive machining processes were compared. The key technologies of high efficiency abrasive machining, including grinding wheel, spindle and bearing, grinder, coolant supplying, installation and orientation of wheel and workpiece and safety defended, as well as intelligent monitor and NC grinding were investigated.

Abstract: Isoscallop height toolpath planning method is a high-efficient way to generate toolpaths. However, for some sculptured surfaces, the toolpaths generated via this method may be not smooth, e.g. the cutting direction may alter sharply which badly affecting the machining surface quality. If the curvature of toolpaths can be restricted, paths will be smooth and surface quality can be guaranteed. On the other hand, the machining efficiency may decrease comparing with toolpaths generated via Isoscallop height method. To balance efficiency and surface quality, a modified isoscallop height toolpath planning method based on curve fitting is proposed in this paper. Toolpaths generated via the new method can keep smooth and the efficiency is as high as possible under the restriction of the curvature set by users.

Abstract: The aim of this study is to construct a diverse process of electrical discharge machining (EDM) in gas media, and then the new developed machining approach was used to investigate the effects of machining parameters on machining characteristics. Firstly, the feasibility of the EDM in gas media was established with consecutive electrical sparks generated within the machining gap. Moreover, the main machining parameters such as peak current, pulse duration, machining polarity, and gas media supply conditions like air compressed pressure were varied to evaluate the effects on machining characteristics of SKD 61 mold steel in the developed EDM process. The surface morphology of machined surface was observed by a scanning electronic microscope (SEM) to determine the influences of EDM discharge energy on surface integrities. From the result shown in experiments, the material removal rate (MRR) increased with peak current, pulse duration, and air pressure. In addition, the electrode wear rate (EWR) went up with peak current at first, and then attained a peak value with extending the pulse duration and the air pressure, but the EWR declined with further increasing of the pulse duration and the air pressure. Furthermore, the integrities of the machined surface revealed dramatically rough features when the peak current was set at high value. While the pulse duration was further extending, the surface integrities of the machined surface exhibited a smoothened trend obtained by EDM in gas media. Consequently, the developed technique of EDM in gas media possesses the potential of promoting machining performance, reducing environment impact, and extending the EDM applications.

Abstract: In this paper we address a rectangular packing problem (RPP), which is one of the most difficult NP-complete problems. First, greedy biggest space sequencing (GBSS) is presented as a new placement strategy, which is very essential to RPP. Then, borrowing from the respective advantages of the two algorithms, genetic algorithm (GA) and simulated annealing (SA), a hybrid optimization policy is developed. The hybrid GASA is subjected to a test using a set of benchmarks. Compared to other approaches from the literature the hybrid optimization strategy performs better.