A hybrid algorithm for predicting chip form/chip breakability in machining

Prediction of chip breakability for a wide range of machining conditions is a difficult task. Currently available predictive machining theories are not suitable for use in the shop floor environment. The methodology presented in this paper provides a new and viable means to predict chip breakability and chip shapes/sizes in machining process planning systems. Due to the extreme difficulty involved in developing a numerical model for predicting chip breakability for a wide range of machining conditions, including work materials, tool geometry, chip-breakers and cutting conditions, this paper presents a hybrid algorithm-based model to characterize various chip shapes and sizes, and to quantify the chip form/chip breakability based on a chip control reference database developed through a set of systematic machining experiments. The chip form and chip breakability could then be predicted with reasonable accuracy for a given set of machining conditions using this new algorithm in conjunction with the chip control reference database.     

感应加热钢包炉的电磁与结构分析

通过电磁场数值计算，对国外感应加热钢包炉的电磁设计及包壳结构进行分析，为国内开发、应用和优化感应加热钢包炉提供基础。     

Nanoscale Friction Behavior of the Ni-Film/Substrate System Under Scratching Using MD Simulation

The friction behavior of the nanoscratching process is investigated using molecular dynamic simulations by considering a sphere indenter sliding against a nickel nanofilm structure. In the film/substrate system, the interface-dominated friction process is studied during the nanoscratch process. The results indicate that the interface accommodates deformation during the scratch by absorbing plastic deformation (such as stacking faults and partial dislocations) and by allowing locally interface slip. The observed local material shuffling beneath the tip that was strongly affected by the interface and friction mechanisms, including material ploughing along the track, filling in of the track, and piling up of the chip in front of the tip, are discussed. The combination effects of both scratching depths and film thicknesses were also investigated.     

A novel approach to measure slip-length of thin lubricant films under high pressures

Abundant evidence of boundary slip at liquid/solid interfaces has been presented by experiments and theoretical analyses. Recent research reveals that the boundary slip effect of lubricants can be obvious in small confined gaps, even with simple Newtonian fluids. Therefore, it is appropriate to ask if there is boundary slip of thin highly pressurized lubricant films in EHL contacts, and, if so, how to quantify it. This paper proposes a method for measuring the slip-length of lubricant films within a small gap under high pressure. Measurement principles have been addressed in details in the paper. The idea makes use of the phenomenon whereby a tiny quantity of lubricant can be entrapped and forms a dimple film by impacting a steel ball against a lubricated glass plate. The slip-length can be extracted from the relative movement of the dimple against the solid surfaces. Case experiments are also presented to validate the feasibility of the method.     

Fast magneto-optical spectrometry by spectrometer

Time efficient measurement of the spectroscopic magneto-optical (MO) activity of materials has always been desirable. In conventional MO systems, the monochromator produces quasi-monochromatic light in a narrow wavelength window. Therefore, to measure the spectroscopic MO activity, a large number of measurements over the full spectra is required to obtain satisfactory wavelength resolution and thus is very time consuming. Here, we develop a novel system that is capable of fast measurement of the MO activity by only one white light source, two polarizers, one achromatic quarter-wave plate, and one spectrometer. This system is flexible from UV to IR region, only depending on the power spectra of light source and sensitivity of the detector at the corresponding wavelengths. As examples, we measured the intriguing optic and MO activity in glass, ferromagnetic thin film, and bulk GaAs in the visible to near infrared region. The results of glass demonstrated a minimum resolvable Faraday rotation angle of 0.004° by the currently equipped system.     

A very low energy compact electron beam ion trap for spectroscopic research in Shanghai

In this paper, a new compact low energy electron beam ion trap, SH-PermEBIT, is reported. This electron beam ion trap (EBIT) can operate in the electron energy range of 60-5000 eV, with a current density of up to 100 A/cm(2). The low energy limit of this machine sets the record among the reported works so far. The magnetic field in the central drift tube region of this EBIT is around 0.5 T, produced by permanent magnets and soft iron. The design of this EBIT allows adjustment of the electron gun's axial position in the fringe field of the central magnetic field. This turned out to be very important for optimizing the magnetic field in the region of the electron gun and particularly important for low electron beam energy operation, since the magnetic field strength is not tunable with permanent magnets. In this work, transmission of the electron beam as well as the upper limit of the electron beam width under several conditions are measured. Spectral results from test operation of this EBIT at the electron energies of 60, 315, 2800, and 4100 eV are also reported.     

Development of DRAGON electron cyclotron resonance ion source at Institute of Modern Physics

A new room temperature electron cyclotron resonance (ECR) ion source, DRAGON, is under construction at IMP. DRAGON is designed to operate at microwaves of frequencies of 14.5-18 GHz. Its axial solenoid coils are cooled with evaporative medium to provide an axial magnetic mirror field of 2.5 T at the injection and 1.4 T at the extraction, respectively. In comparison to other conventional room temperature ECR ion sources, DRAGON has so far the largest bore plasma chamber of inner diameter of 126 mm with maximum radial fields of 1.4-1.5 T produced by a non-Halbach permanent sextupole magnet.     

Status of the laser ion source at IMP

A laser (Nd:YAG laser, 3 J, 1064 nm, 8-10 ns) ion source has been built and under development at IMP to provide pulsed high-charge-state heavy ion beams to a radio frequency quadrupole (RFQ) for upgrading the IMP accelerators with a new low-energy beam injector. The laser ion source currently operates in a direct plasma injection scheme to inject the high charge state ions produced from a solid target into the RFQ. The maximum power density on the target was about 8.4 × 10(12) W∕cm(2). The preliminary experimental results will be presented and discussed in this paper.     

不同宽度和夹角的微米交叉凹槽表面图形的摩擦学性能研究

采用销-盘摩擦副接触方式在流体润滑下,对SKD11模具钢表面不同宽度和夹角的微米交叉凹槽表面图形进行摩擦试验,利用Stribeck曲线分析在不同试验条件下,微米交叉凹槽表面图形的滑动摩擦特性,并考察不同宽度和夹角的微米交叉凹槽表面图形的摩擦行为。结果表明:微米凹槽宽度为40,70及100μm时,微米交叉凹槽表面图形分别在其基准夹角为60°、40°及10°时显示出最佳的滑动摩擦特性;微米交叉凹槽基准夹角为20°～40°时,摩擦因数主要依赖于凹槽宽度的变化;确定基准长度和摩擦因数之间的关系,即基准长度为0.1时具有最佳的摩擦特性。     

Accurate spiral tool path generation of ultraprecision three-axis turning for non-zero rake angle using symbolic computation

An accurate spiral tool path generation method of ultraprecision three-axis turning free form surface is proposed based on symbolic computation in this paper. Many analytic optical free form surfaces often need to be machined to submicron in form error, such as optical nonaxisymmetric aspheric surfaces, but current mainstream CAM systems usually use nonuniform rational basis spline (NURBS) to describe the designed surface and generate tool path. If we want to use these systems, the analytical optical surfaces must be approximated using NURBS surfaces, but it will introduce approximation error and may be difficult to achieve the approximation error less than submicron. More importantly, there is no effective tool path generation method for the special three-axis turning machine tool in current mainstream CAM systems. In this context, we propose to calculate the tool path directly from these analytic surfaces by using symbolic math. The proposed method can be used to generate accurate spiral tool paths for zero/negative/positive rake angle in a unified way. Finally, several examples are given to prove its effectiveness.