Key Engineering Materials Vols. 589-590

Abstract: This article develops the design and evaluation function block of inserts on the basis of the optimization database system of cutting parameters for large cylinder section. The function block completes the development combining 3D graphics software called SolidWorks with programming language called VB. This article achieves the design and evaluation functions which are inserts shape selection, inserts parameter design, inserts geometric characteristics design and finite element simulation of inserts. Finally, this paper proves the reliability of the result which is achieved from the design and evaluation function block of inserts by comparing with traditional inserts.

Abstract: Drilling is frequently used in machining of carbon fiber reinforced materials. Twist drill is mostly used in drilling composite materials and some other drills with special drill bits are also needed. Drilling induced delamination is considered one of the most serious problems during machining while drilling force plays a decisive role in delamination. This paper presents the analysis of critical thrust force with special drill bit theoretically. The method of simulation to study the critical thrust force is also introduced. In addition, effect of cutting parameters on delamination by comparing experimental results and mathematical model of twist drill is studied.

Abstract: Carbon Fiber Reinforced Plastic (CFRP) is widely used in aerospace field as an advanced composite material. Recently, more and more studies are focused on milling of CFRP with its increasing applications. In this paper, three different milling tools were chosen, and a systematic analysis on cutting force, surface quality and tool wear has been carried out to evaluate the tools. Experimental results indicate that the multi-flute tool with diamond coating has a better performance than the double spiral compression tool and the multi-tooth tool with AlTiN coating, with a lower cutting force, a better surface quality and a higher tool life than others, which would be a better tool for cutting of CFRP.

Abstract: A temperature model was advanced based on a parabolic heat flux distribution in sawing contact zone in the present paper. It is found that the maximum temperature for parabolic distribution is more higher than that for triangular distribution in the sawing contact zone, and the location point of the maximum temperature for parabolic distribution in the sawing contact zone is much nearer the entrance than that for triangular distribution.

Abstract: Grinding process can be considered as micro-cutting processes with a lot of irregular abrasive grits on the surface of grinding wheel. The study of the grit-workpiece interaction through single grit cutting is an important contribution to describe the material removal processes in the grinding process. In this study, single grit cutting processes with different process parameters (depth of cut, cutting speed) were modeled by FEM software AdvantEdge. The critical depth of cut from plowing t cutting was investigated. The simulated tangential and radial cutting forces increase sharply due to the pile-up of workpiece material in the front of single grit when the depth of cut reached to some value. And the increase extent of cutting forces at low cutting speed is larger than that at high cutting speed due to the thermal softening of workpiece material. The simulated highest cutting temperature increase first, and then decrease, finally increase again with the increase of depth of cut. And the peak value of simulated highest cutting temperature occurs near the critical depth of cut. The simulated material removal rate increases with the increase of cutting speed and depth of cut.

Abstract: For the technology of diamond cutting of optical glass, the machinability of glass is poor, which hindering the practical application of this technology. In order to investigate and ameliorate the machinability of glass, and achieve optical parts with the satisfied surface quality and dimensional accuracy, this paper first conducted SF6 indentation experiment by Vickers microhardness instrument, and then the scratching tests with increasing depths of cut were conducted on glass SF6 to evaluate the influence of the cutting fluid properties on the machinability of glass. Based on this, turning tests were carried out, and the surface quality of SF6 was assessed based on the detections of the machined surfaces roughness. Experimental results indicated that compared with the process of dry cutting, the machinability of glass SF6 can be improved by using the cutting fluid

Abstract: The goal of this study is to analyze the material deformation behavior in the micron level by quasi-static and dynamic impact tests of hat shaped specimen. Three type of specimen with different shear ring thicknesses (800μm, 400μm, 50μm) were designed. The quasi-static and dynamic impact tests were performed by electronic universal testing machine and split Hopkinson pressure bar (SHPB) respectively. During the material deformation in the SHPB test, the value scope of strain is 0 to 9 while the value scope of strain rate is 0.001s-1 to 400000s-1. The size effect phenomenon on shear stress and failure strain with different shear ring thickness was investigated. The shear stress and failure strain of material increases with the decrease of shear ring thickness. And the size effect phenomenon was weakened with the increase of strain rate.

Abstract: The stability of the process systems has an obvious impact on the cutting quality, seeking cutting process stability region is an important aspect of the cutting mechanism. In this paper, establishing cutting process dynamic analysis model is based on the tool wear and creating the evaluation model about the influence of tool wear on the cutting system stability by power spectral RMS method. Root locus plot of non-uniform load distribution is obtained and the minimum stiffness ratio in the root locus plot is determined. So as to arrive the limit plot in different tool wear cutting system stability domain and determine the flank wear limit in the stable cutting quantitatively and offer the parameter of design and evaluation indicators to cutting system. The results found that with the increase in cutting speed and tool wear intensifies, the system stability is sharp in decline and tool wear is more intense. Obtaining limit diagram of cutting stability domain is suitable for providing a theoretical basis for processing in the different tool wear conditions.

Abstract: Single-grain grinding test plays an important part in studying the high speed grinding mechanism of materials. In this paper, a new experimental system for high speed grinding test with single diamond grain is presented. The differences of surface topography and chip morphology of Inconel 718 machined by single diamond grain and single CBN grain were evaluated. The grinding forces and corresponding maximum undeformed chip thickness were measured under different grinding speeds. The chips, characterized by crack and segment band feature like the cutting segmented chips, were collected to study the high speed grinding mechanism of nickel-based superalloy. The results show that the grinding speed has an important effect on the forces and chip formation, partly due to the temperature variation. As the speed increases, the groove surface becomes smoother.

Abstract: The single layer superabrasive wheels are made by joining all abrasive grains onto the wheel hub by electroplating or brazing. Recently, the attention has risen to acquire better grinding quality through more stringent grain size control. For the size grain control process, the abrasive grains are re-meshed for smaller dimensional derivation after outsourced from external grain manufacturers. Therefore, the understanding of correlation between the grain dimensional deviations with the wheel performances will be critical for the wheel design and optimization. In this paper, the ‘through the process’ grinding wheel model is developed for single layer CBN wheels by simulating each wheel fabrication procedure numerically. The effectiveness of the wheel model is verified by comparing with the experimental measurement, which proves the efficacy of the wheel model and could further provide the quantitative basis for grinding wheel quality control and process design.