Key Engineering Materials Vol. 667

Abstract: On the basis of uneven copper surface roughness during lathering in common CNC lather, analyze the cutting ways of copper spherical surface and the cutting layer different from cylindrical surface lathing. The cutting direction of cylindrical surface lathing is constant, and its cutting layer is too. However, the direction of spherical surface lathing varies along the tangent of its cutting point continually, and the working cutting edge angle and the working minor cutting edge angle of the cutting tool vary too, so the theoretical surface roughness is affected. The cutting layer of spherical surface lathing varies continually, so does the cutting depth of its every cutting point. Through analysis and experiments, prove that cutting force variety is caused by the gradient variety of cutting depth, which leads to increase of the surface rough and its unevenness. Based on the research result, design some new cutting path to improve the surface roughness of copper spherical surface lathing, and obtain good effect.

Abstract: The cutting vibration has a great influence on the processing quality of Hardened steel. The research conducted in this paper is about how the cutting parameters influence the cutting vibration amplitude when the hardened steel is cut. The experiments were performed on CNC lathe CAK4085 with PCBN tool, where the cutting speed, feed rate, cutting depth and corner radius had been orthogonally combined. The cutting materials were hardened steel Cr12MoV and GCr15 whose hardness is HRC50-52 and HRC62-64. The cutting vibration amplitude under different group parameters was collected by electric eddy current sensors. An analysis about the influence rule of cutting parameters on cutting vibration amplitude had been made. With the increase of cutting speed, vibration amplitude will increase first, and then decrease. With the appropriate increase of feed rate, vibration amplitude will be reduced. With the increase of cutting depth and corner radius, vibration amplitude will both increase. This research can provide reference for improving cutting quality.

Abstract: Micro-arc oxidation technology is a new type of metal surface treatment technology. With a large area of die casting magnesium alloy wheel surface treatment as an example, the practical production and application of micro-arc oxidation technology of magnesium alloy is discussed, Surface treatment technology production line is designed, The main equipment and process piping required for production line is introduced in detail. By the study of current and voltage which have a large effect on the craft of micro-arc to magnesium alloy, in the end a kind of electric parameters of micro-arc oxidation about magnesium alloy was optimized and film quality for testing. The micro-arc oxidation technology has been proved practically an appropriate technology for Mg alloy wheel hub and reference for the mass production used for a large area of magnesium alloy surface treatment technology and equipment design.

Abstract: Aiming at the problem that the machining accuracy of 45 steel rectangular thin-walled parts are difficult to ensure because of poor rigidity, poor manufacturability and easy machining deformation, it used the three-dimensional finite element method, determined the material model of 45 steel and established a prediction model of 45 steel rectangular thin-walled parts milling deformation. The prediction results display that the deformation of the workpiece shows obvious parabola in length direction and a linear decreasing trend in width direction. It verifies the correctness of the prediction model through milling experiments and provides the method and basis for the prediction and control of machining deformation of 45 steel thin-walled parts.

Abstract: Orthogonal experiments of ultrasonic deep rolling with Longitudinal-torsional vibration (UDR-LTV) and conventional deep rolling (CDR) Q235 steel were carried out to study the effects of processing parameters on surface roughness. The orthogonal experiments results show that the influence laws of processing parameters on surface roughness are the same, and the values of surface roughness obtained by UDR-LTV are smaller than that of CDR with the same processing parameters. The values of surface roughness obtained by UDR-LTV and CDR increase and then decrease with the increment of the static pressure; and increase with the increment of the feed-rate, and change a little along with the increment of the rolling speed. Meanwhile, the feed-rate has a marked effect on the surface roughness, while the rolling speed has a little effect on the surface roughness. The quadratic regression method is used to construct the mathematic model to predict surface roughness based on the experimental results. The effects of parameter interactions on surface roughness are studied. The research shows that the interaction effects of the rolling speed and the feed-rate, the static pressure and the feed-rate on surface roughness are obvious, but the interaction effect of the static pressure and the rolling speed on surface roughness is not significant. The optimal parameters for the lowest surface roughness are given by the result of orthogonal design and prediction model, which has guiding significance for the application of ultrasonic surface strengthening technology with complex vibration mode.

Abstract: For the purpose of acquiring thorough understanding of the characteristics of cutting force in high and ultra-high-speed face milling of hardened steel, experimental investigations on face milling of AISI H13 steel (46-47 HRC) are conducted in the present study. The cutting speed of 1400 m/min, at which relatively low cutting force and relatively low surface roughness can be obtained at the same time, is considered as a critical value for both mechanical load and surface finish. The Taguchi method is applied to investigate the effects of cutting parameters on cutting force in different speed ranges (below and above 1400 m/min). In different speed ranges, the contribution order of the cutting parameters for the resultant cutting force is the same, namely axial depth of cut, cutting speed and feed per tooth. However, the contributions of cutting speed and feed per tooth increase substantially as the cutting speed surpasses 1400 m/min. Within the range of cutting parameters used in the present study, the optimum cutting conditions for the cutting force are cutting speed 200 m/min, feed per tooth 0.02 mm/tooth and axial depth of cut 0.1 mm.

Abstract: Nanomachining technology has broad application prospects and molecular dynamics method is an important research tools for studying nanoscale material removal mechanism. This paper is focused on the analysis of basic principle of molecular dynamics method and the progress of nanomachining model. The nanomachining mechanism of single crystalline brittle materials and plastic materials are investigated completely, micro-nanomachining mechanism of polycrystalline material is also summarized, The challenges and future development of the nanometric machining mechanism study are also discussed.

Abstract: Abstract. The mathematical model of cylindrical compact simulation is established by using the mathematical model of the net pressure P1 and the loss pressure P2 in AMESim environment, basing on the physical model of the powder metallurgical cylindrical blank. The simulation model of multi-step P/M parts is established by disassembling and transformation of parts, which is successfully introduced to the hydraulic system simulation. The corresponding velocity and displacement curves are obtained by running batch the three parts of B, C, A, following the principle that the speed of different height step mode is equal to the pressing rate. When the piston reaches a certain equilibrium displacement, , , and respectively range from 20 to 100, from 20 to 50, and from 50 to 2000. According to the corresponding suppression curve obtained, corresponding optimized parameters could be got to meet the requirements of the pressing speed with the AMESim optimization function.

Abstract: Joining between polyamides (PA) and metals has potential applications in the industry. Based on PA66GF and AISI304, the experimental study of laser transmission joining of the dissimilar materials is conducted in this article. Firstly, comprehensive experiments of laser transmission joining between PA66GF and AISI304 are carried out by Nd: YAG pulsed laser source according to the central composite rotatable design method (CCRD). Secondly, the effects of the process parameters like voltage, joining speed and stand-off distance on the joint quality are analyzed by response surface methodology (RSM). Finally, mathematical models between the process parameters and the lap-shear strength and the joint width are established and based on which, the optimization of the joining process is done and the optimized results are predicted. The results show that the process parameters of laser transmission joining play a significant role in determining the joint quality; the predicted data of the models are in good agreement with the experimental results and can be of great help for the optimization of the joining process. As a result, this study could provide an effective instruction about how to choose the reasonable process parameters for enhancing the joining efficiency.