Key Engineering Materials Vol. 621

Abstract: Hard cutting technology is a green cutting technology of broad application prospect, but hard cutting is more likely to produce vibration compared with traditional cutting, and the production efficiency, machining quality, environment, cost and machine tools and tool life will be affected by the precision in the process of hard cutting chatter. Turning hardened steel GCr15 cylindrical bar using PCBN inserts on the lathe CAK6150DI analyzed the cutting vibration signal characteristic in the different state of cutting tool; analyzed the related features of dynamic cutting force and cutting vibration signals; and observed the microstructure on the machined surface. Analysis results show that the vibration of smooth cutting state is given mainly with forced vibration and noise, vibration signals are produced with the typical characteristics of high range frequency in frequency zone, disperse frequency domain energy; When the cutting chatter, strong self-excited vibration appeared and occupied the main position of vibration signal energy, frequency domain energy is concentrated in nearly natural frequency of the main vibration system of the lower cutting. The results of the study can provide theoretical guidance for the control of vibration in hardened cutting process.

Abstract: High-speed cutting is an important method for improving the efficiency and quality of machining mold steel, but the wear of tool is one of the key factors restricting the improvement of cutting speed, which brings higher requirement for the material of tools. At present, most of the research is about high-speed cutting for high hardness mold steel, while only a limited research work on the pre-hardened plastic mold steel with hardness between 30 HRC and 42HRC, such as P20 mold steel. To explore the effects of cutting speed on the wear properties of TiAlN PVD coated tool for cutting P20 mold steel, the experiments in different cutting speeds were carried out under dry condition. Wear characterization of the rake and the flank surfaces were investigated by using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). It was revealed that at the low speed (160m/min), adhesion (built-up edge) followed by delamination was found to be the cause of wear damage; at the high speed (320m/min), the dominant wear mechanisms were oxidation wear and diffusion wear, followed by adhesive wear and melt wear; as the cutting speed increased, the proportion of oxidation wear and diffusion wear was gradually increased.

Abstract: High speed cutting is an important means to improve the efficiency and the quality of machining mold steel, but the tool wear is one of the key factors restricting the increase of the cutting speed, leading to higher requirements for cutting tool materials. At present the researches of high-speed cutting of mold steel are mainly on the hardness mold steel, but less on P20 mold steel which hardness is 30-42HRC. This paper mainly studies the effect of cutting speed on wear property of TiAlN PVD coated tools when high-speed milling of P20 mold steels. The experiment was conducted using two different high cutting speeds under dry condition, 320m/min and 500m/min. Wear characterization of the rake and the flank surfaces as well as the collected chips were performed using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). It was found that at high speeds, the dominant wear mechanisms were oxidation wear and diffusion wear, followed by adhesive wear and melt wear; as the cutting speed increased, the wear surface area of rake face will be closer to the main cutting edge.

Abstract: The relationship between N and strain hardening exponent curve are obtained by the tensile test of the stainless steel, low carbon steel, medium manganese steel under the ultrasonic action, it is concluded that hardening exponent n of low carbon steel is constant; Hardening exponent N stainless steel has a certain relation with the strain, show the parabolic variation; Strain index N and strain of high manganese steel is linear change. Establish the constitutive equation of low carbon steel under normal and ultrasonic frequency, This equation provides a theoretical basis for the tensile test of low carbon steel, provided with guiding significance and reference value for the application of low carbon steel in engineering practice.

Abstract: High-gloss injection molding technology is also called rapid cool and heat injection technology which can be used to eliminate weldmark on the surface of plastic parts, and improve the surface glossiness. However, the warpage, sink index and volume shrinkage of the parts are considered difficult to solve by using this technology. Reasons that cause the warpage and sink index of the parts were discussed in this paper firstly. Then, by using a LCD panel produced in practical injection process as an example, through orthogonal experimental design and finite element simulation, this paper discusses the effects of the injection molding parameters such as mold temperature, melt temperature etc. on warpage and sink index of the parts. The results are of great significance to help to set practical process parameters and assure the part quality in injection process.

Abstract: In order to analyze the positional accuracy of the key component of 5-DOF laser cutting machine–laser cutting head a geometry error model was established based on the theory of multi-body system kinematics. The factors resulted in the geometry errors were analyzed and the geometry error of the laser cutting head was computed by the probabilistic method of error budget. The result of the computation gives the evidence that the positional accuracy of the laser cutting head satisfy the requirement of the design.

Abstract: To achieve the processing program and simulation verification on NC Woodworking Curve Band Saw (WCBS) that facilitates the industrialization and practicality of the woodworking machinery, the articles proposes the CAM system modules by the analysis of its composition structure and working principle of the machine and the building-up of its kinematics model. The article also explains the basic functions for each module and develops the CAM systems of MJS1325 WCBS with the use of VC++ and OpenGL. Reading and analyzing the CAD work piece graphics files, the CAM systems is able to generate the NC program and realize the simulation of machining in whole visual process environment including saws, fixtures, belt saw and work piece, etc. The CAM systems pass the prototype test and see a favorable effect.

Abstract: There are a lot of faults in making complex surface parts (especially 3D curved blade) as designing difficultly, processing complexly, low production efficiency and so on. In this paper, it integrates the computer aided design and manufacturing, layered manufacturing and increase material molding technology. They are based on the pro/E 3d surface modeling and rapid prototype technology. The technology can put the blades of irregular surface processing into simple graphic processing. We can make complex plane quickly, make the development cycle of new products shorter and reduce the development cost by selected material curing. Thus it can make the enterprise have higher product development capacity and market competitiveness.

Abstract: Mass finishing processes have widely industrial application, and in most conditions these processes are used with empiricism and trial and error. Based on basic concept of mass finishing, its category is presented. Main aspects of motion and force analysis, material removal model, equipment and consumables, process experiments and industrial application are induced. Finally, development trends are recommended from quantified models, process database, new mass finishing processes and surface integrity. This will provide full investigation and further development and research to improvement part surface integrity.

Abstract: Laminated templates electroforming (LTE) is one kind of metal-parts directly forming technologies which are based on discrete/accumulation theory. This paper introduces the forming principle, equipment configuration and experimental studies. By using templates as auxiliary tool and jet electroforming as filling method, the current density of electroforming was significantly improved and a group of copper parts in specific shape were fabricated. Experimental results show that on-load voltage, nozzle diameter, spray distance, spray flow velocity have direct influence on processing speed and locality. A small diameter of nozzle and short spray distance helps to achieve a precise locality and good dimensional accuracy, after process parameters have been optimized.