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Mi Y.Z.,Shandong University | Zhou Y.Q.,Shandong University | Wang L.,Key Laboratory of High Efficiency and Clean Mechanical Manufacture
Advanced Materials Research | Year: 2014

Acceleration signals at the mounts of an excavator cab are collected and analyzed, on the basis of which causes of peak values in the sound pressure level(SPL) at the driver's right ear(DRE) are discussed. A damping material layer made up of chlorobutyl rubber is arranged to the cab's panels by simulations according to results of panel acoustical contribution analysis, which indicates a great decline of the SPL peak values. © (2014) Trans Tech Publications, Switzerland. Source


Liu R.L.,Shandong University | Liu R.L.,Key Laboratory of High Efficiency and Clean Mechanical Manufacture | Zhu H.G.,Shandong University
Advanced Materials Research | Year: 2014

With STEP-NC (ISO 14649) being gradually accepted as new standard for programming computerized numerical control (CNC) machine tools, new technologies and computer systems in the design and manufacturing process chain are emerging, and conventional systems are reshaping, to support interoperable and intelligent manufacturing. This paper addresses issues and solutions for the adaptation. In the first place, a strategy for adapting legacy CNC turning machine tools to the emerging standard is presented. In the second place, the new data model is analyzed and a practical way to retrieve and extract manufacturing information from the STEP-NC part program for turning process is presented. In the third place a workable approach to calculating the cutting force and chip load in turning operations is presented based on the mechanistic modeling method. Finally the proposed approach is implemented in a prototype system and tested with an example STEP-NC program for turning, which shows not only the feasibility of the proposed approach for information extraction and process evaluation, but also the possibility of using simple transitional systems to bridge the gap between the sophisticated STEP-NC part program and conventional CNC machines. © (2014) Trans Tech Publications, Switzerland. Source


Lv K.,Shandong University | Huo M.,Shandong University | Li F.,Key Laboratory of High Efficiency and Clean Mechanical Manufacture
Applied Mechanics and Materials | Year: 2013

In order to achieve the precise control of the compressed air foam proportioning on the fire engines, in this paper, the PIC microcontroller and the fuzzy control algorithm are used to design the microcontroller-based foam proportioning hybrid fuzzy control system. Taking into account the system cost and ease, we use the software to implement the fuzzy control of DC motor. The controller learns from the experience of skilled operators, and forms fuzzy control rules, finally we identify a number of important control parameters in this paper. The experimental results show that the fuzzy control system can achieve precise control of the mixing ratio. © (2013) Trans Tech Publications, Switzerland. Source


Jin D.,Shandong Polytechnic University | Liu Z.,Shandong University | Liu Z.,Key Laboratory of High Efficiency and Clean Mechanical Manufacture
International Journal of Advanced Manufacturing Technology | Year: 2013

FGH95 is one kind of powder metallurgy (PM) superalloy which has excellent mechanical properties at high temperature. It has been developed for turbine disc applications to improve aeroengine efficiency under higher operating temperatures. However, this kind of superalloy is very difficult to machine because of its poor thermal diffusivity and work-hardening properties during the machining process. The machining process can lead to damage of the machined surface and subsurface. Thus, the purpose of this paper was to investigate damage of the machined surface and subsurface in hard machining of FGH95 PM superalloy. Orthogonal milling experiments using coated carbide inserts were carried out on a CNC machining center. The machined surface was observed and recorded using an optical microscope, white light interferometer, and scanning electron microscope. Machined surface defects were recorded and analyzed. The effects of cutting speed on machined surface roughness, white layer thickness, plastic deformation, and microhardness were investigated. The research results show that better surface roughness can be generated at higher cutting speeds, while several defects appeared on the FGH95 machined surface. White layer thickness and machined surface microhardness increase with the cutting speed. Also, plastic shear strain in the machined surface layer increases with cutting speed. The depth of plastic deformation decreases with the increase of cutting speed. These investigation results are essential for the evaluation of PM superalloy surface integrity and are significant for the prediction of PM superalloy service life. © 2013 Springer-Verlag London. Source


Wang B.,Key Laboratory of High Efficiency and Clean Mechanical Manufacture | Liu Z.,Key Laboratory of High Efficiency and Clean Mechanical Manufacture
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture | Year: 2014

Serrated chip is the frequent chip morphology during high-speed machining of ductile materials, while the mechanism of serrated chip formation still remains some ambiguous aspects. This article presents the investigation of chip morphology from the viewpoint of chip free surface and cross section. Experiments of orthogonal cutting hardened AISI 1045 steel and 7050-T7451 aluminum alloy were carried out. The cutting speed of AISI 1045 steel was varied from 100 to 1000 m/ min, while 7050-T7451 aluminum alloy was machined at the cutting speed of 100-2500 m/min. The feed rate per tooth was varied from 0.025 to 0.20 mm/z corresponding to each experimental cutting speed. The research shows that the microstructure of chip free surface evolves from lamellae to folds and then to dimples. According to the experimental results, a new model of serrated chip formation based on mixed mode of ductile fracture and adiabatic shear is proposed. For the "ductile fracture-adiabatic shear" serrated chips, two distinct zones of ductile fracture and dimples were observed on the slide surface of serrated segments. Through studying chip morphology evolution under different combinations of cutting speed and feed rate, it is found that the degree of chip segmentation has positive correlation with the two parameters. The concept of "critical cutting load" is then proposed to illustrate the conditions under which serrated chips may occur. And the critical cutting load of AISI 1045 steel and 7050-T7451 aluminum alloy is determined by experiments as 0.024 and 0.10 m2/(min z), respectively. © IMechE 2013. Source

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