Advanced Materials Research Vols. 887-888

Abstract: In the milling process, the dynamic system in the cutting process is composed of the tool, workpiece, and machine tools themselves. Therefore the mill geometric parameter, workpiece material behavior, and the modal parameters of the cutting system all will influence the stability in milling. Using FLN method and convolution force model to predict the chatter stability of milling process, and discussing the effect of milling parameter on the stability in this article. According to the result: with the increase of the tool diameter, stiffness, damping ratio or the reducing of tangential cutting force coefficient and radial width of cut, the stability lobe diagram tends to move upward. With the increase of natural frequency, the stability lobe diagram tends to move to right side. With the increase of the number of tooth, the stability lobe diagram tends to move downward.

Abstract: Continuous cutting experiments of steel 45 were conducted to investigate cutting performance of TiB₂/WC/h-BN micro/nano composite gradient self-lubricating ceramic tool. Influences of cutting speed on flank wear and tool life were analyzed. The results show that flank wear increases slightly when cutting speed V≥80 m/min, tool life increases initially and then decreases with increasing cutting speed. Wear mechanism was studied: the primary pattern of tool wear is abrasive wear and adhesive wear and solid-lubricants in tool have a noticeable wear-resistance effect during machining.

Abstract: Nano electrical discharge machining (nanoEDM) method is an attractive measure to the manufacturing of parts of nanoscale dimension or precision, and is getting more and more interest of researchers, however, due to the incompleteness of EDM theories, the development of more advanced nanoEDM technology is impeded. In this paper, a hybrid simulation model, namely, combination of the molecular dynamics simulation model and two-temperature model of single discharge process in nanoEDM is constructed to study the machining process of nanoEDM from the thermal point of view.

Abstract: A new simulation model on frequency is proposed, to analyze mutual relationship between intrinsic frequency and other factors in system. The study is mainly focused on the axial press effect, inner cutting fluid velocity and its Coriolis inertia effects acting on boring bar. The whole system is assumed to conform to the continuous equal span beam model synthesized with liquid-solid coupling vibration model inner the work and Timoshenko beam model outer the work. Simulations show that system vibration frequency is determined by mechanical properties, axial force, inner cutting fluid velocity and density. Three aspects influence BTA boring bar lateral vibration considering inner cutting fluid velocity and axial force, who are transverse inertial mass, inertia and self-excited vibration on the bar. Inner flowing of the cutting fluids also lead to instability on bar.

Abstract: A table tennis mould with good performance of dimensional precision and fine surface roughness was directly manufactured by HPDM (Hybrid Plasma Deposition & Milling), which synthesizes plasma deposition as an additive technology, and milling as a subtractive technique during the processing. Compared with the existing RP methods using high energy density beams, the HPDM method solved the key problems of insufficient dimensional precision and surface quality caused by the step effect, and puts forward a new access to directly manufacture the metal parts and mould with short-process and high quality.

Abstract: In this paper, we studied the large deformation and the small deformation method based on the research of the existing system of straightening theory and considered the characteristics of copper-clad steel to find a proper straightening scheme for this new composite materials. the advantages and disadvantages of the method are also compared. the straightening scheme for straightening effect and parameters is a decisive role before all kinds of straightening parameter determination. But at present, there isnt a equipment for the straightening of this new material.

Abstract: Effect of the pore size and volume fraction of alumina bubbles on the mechanical properties and microstructure of metal bond for superabrasive grinding wheels were studied by means of single factor test. The results showed that the mechanical strength reduced with the increase of bubble size and volume fraction of alumina bubbles. The morphology of the center section of the binder matrix showed that the higher the volume fraction of alumina bubbles was the less the effective area rate of the matrix was. Additionally, the bigger the bubble size was the more inhomogeneous the bubbles distributed. The pores generated after the fracture of the alumina bubbles had a regular shape and size which satisfied the chip space requirement of the wheels. At last, the failure condition of the bond matrix was established, which indicated that the strength of the bond matrix is mainly related to the effective area rate and the homogeneity of the bubble distribution.

Abstract: Germanium is an anisotropic material. Cutting force varies with the change of crystallographic orientation and crystal plane in the process of turning. According to the effect of germanium crystal anisotropy in cutting force, fluctuation of theoretically calculated cutting force changing with crystallographic orientation and crystal plane and best cutting direction are presented.

Abstract: Single-point diamond turning (SPDT) is a machining process making use of a monocrystal diamond tool which possesses nanometric edge sharpness, form reproducibility and wear resistance. The process is capable of producing components with micrometre to submicrometre form accuracy and surface roughness in the nanometre range. The cutting parameters that can make an effect on surface finish and form accuracy of SPDT such as spindle speedfeed ratedepth of cut and so on.

Abstract: Simulation of hot isostatic pressing (HIP) process with complex castings was rarely referred for its time-consuming and difficulties existed in meshing by commercial software. A fast prediction model was proposed to overcome those limitations in present work. The relationship of holes size, shape, and closure pressure was established by analysing the closed hole in ZTC4 castings with simple structures based on the software. Then the fast prediction model was applied to a complex casting. A relative error of 4.09% was obtained between this model and result calculated by the software, which verified its effectiveness in predicting ZTC4 castings with complicated structures.