Fuzzy adaptive networks in machining process modeling: surface roughness prediction for turning operations

Due to the complexity of the machine tool structure and the cutting process, the dynamics of machining processes are still not completely understood. This is especially true due to the demand of high-speed machining to increase productivity. In order to model and control these complex processes, new approaches, which can represent complex phenomenon combined with learning ability, are needed. The combined neural–fuzzy approach appears to be ideally suited for this purpose. In this paper, the recently developed fuzzy adaptive network (FAN) is used to model surface roughness in turning operations. The FAN network has both the learning ability of neural network and linguistic representation of complex, not well-understood, vague phenomenon. Furthermore, it can continuously improve the initially obtained rough model based on the daily operating data. To illustrate this approach, a model representing the influences of machining parameters on surface roughness is established and then the model is verified by the use of the results of pilot experiments. Finally, a comparison with the results based on statistical regression is provided.     

Numerical simulation on magnetic flux leakage evaluation at high speed

High-speed non-destructive inspection (NDI) systems using magnetic flux leakage method (MFL) is in great demand in online metal inspection and defect characterisation, especially in pipeline and rail track inspection. For MFL systems at high speed measurement, in addition to magnetic flux, eddy currents exist in metal specimen because of the relative movement between the probe and specimen. These currents alter the profile of electromagnetic field, which increases difficulty in signal interpretation and defect characterization. In this paper, eddy currents generated by high speed movement and their characterisation in high-speed MFL inspection systems were investigated by using numerical simulations. Besides, the MFL signals from high speed MFL measurement against defect depth were examined.     

Effects of anodizing voltage on the anodized and hydrothermally treated titanium surface

Anodic oxidation is the process of creating a titanium oxide layer with various defects more dense and stable. In this study, a dense, stable and porous oxide layer was formed using anodic spark oxidation on pure titanium surface and hydroxyapatite crystals were formed on its surface via a hydrothermal treatment. A mixture of 0.02M−GP (Glycerolphosphate disodium salt) and 0.2M-CA (Calcium acetate) was used as an electrolyte. By increasing the anodizing voltage to 220, 260, 300, and 360 V, the effects of the anodizing voltage were examined by evaluating the film properties after anodization and a hydrothermal treatment. Breakdown occurred around 230 V. As the voltage increased after breakdown, the pore size increased. After the hydrothermal treatment, the amount of HA crystal precipitation was also increased as the voltage increased. The mean surface roughness (Ra) of the anodizing surface was also increased as the voltage increased. The Ra value was larger in the hydrothermally treated group compared with the group treated with anodization as a result of the HA crystals present on the surface after the hydrothermal treatment. Corrosion resistance of the surface modified by anodization was significantly increased in a saline solution compared to that for the non-treated group; this increased further after the hydrothermal treatment. These increases were most likely due to a thick stable oxide layer formed through anodization. Thus, it is believed that titanium with its surface modified through anodic spark oxidation would be a suitable biomaterial due to its corrosion resistance and biocompatibility.     

金刚石薄膜涂层钻头加工高硬度钢的实验研究

为提高金刚石薄膜涂层的韧性，避免金刚石薄膜涂层脆性断裂，以自贡硬质合金厂生产ZK-10型号硬质合金钻头为基体，采用厚度大约为3μmTiC作为过渡层，在表面涂覆4μm～5μm厚度的金刚石薄膜制成金刚石薄膜涂层钻头。用于加工硬度为HRC61的经热处理的GCrl5钢板，分别与未涂层硬质合金钻头、TiC-TiN涂层钻头对比，结果表明，金刚石薄膜涂层钻头由于加工速率高，摩擦发热量少，有效地避免了铁元素在高温下将金刚石转化石墨的作用，结果使用寿命比未涂层硬质合金钻头提高10倍以上，同TiC-TiN涂层钻头相比，初期加工性能明显优越，加工速率成倍数提高．但使用过程中，性能衰减更快，导致总体使用寿命同TiC-TiN涂层钻头相差不大。在表面喷砂处理中，金刚石薄膜涂层大部分易于脱落，剩余部分呈岛状分布，说明金刚石薄膜与基体的结合力分布很不均匀，这可能与金刚石薄膜的形核过程密切相关。     

基于开放式控制器的六轴数控系统的研究与开发

本文提出以IPC和多轴运动控制器为基础构成开放式数控系统，重点介绍了基于多轴运动控制器数控系统的硬件构成、系统应用软件和用户界面开发以及系统的连接和调试。     

Superplasticity of fine-grained 7475 Al alloy and a proposed new deformation mechanism

A study has been made to investigate the superplastic deformation mechanisms of 7475 Al alloy in relation to the variation of grain size ranging between 5.5 μm and 13 μm. The strain-rate sensitivity (m) was increased with decreasing grain size in the superplastic deformation regime. Microstructural investigation after tension tests revealed that the dispersoid free zones were produced mostly at the grain boundaries normal to the tensile direction. A new model for describing the deformation behavior of the 7475 Al alloy has been proposed based on the assumption that the grain boundary sliding was accommodated by both diffusional flow and slip. This new model well predicts many aspects of experimental results.     

��ﯵ�̼������ּ�������о�

 含锆夹杂物与基体间的缝隙，不是在轧制时形成的，而是在轧后由相变后的组织决定的：有铁素体等软质相组织的钢中，夹杂物与基体的缝隙较小；主要由板条等硬质相组成的钢中，夹杂物与基体的缝隙较大。对夹杂物形貌及尺寸观察后发现：直径大于5 μm的复合夹杂物，ZrO2是夹杂物的核心；直径小于3 μm复合夹杂物的核心则是ZrO，而TiO2、Al2O3、MnS等包围并依附着含锆氧化物析出并长大。     

Characterization of the microstructure and hardness of the HAZ in a 800 MPa grade RPC steel

The microstructure and hardness of the HAZ in a 800 MPa grade ultra-low-carbon microalloyed steel were studied.The results indicate that the heat affected zone (HAZ) of the RPC (Relaxation- Precipitation- Controlling) steel possesses a continuous gradient structure, and can be classified into three zones, i. e. CGHAZ ( coarse-grain HAZ ) , FGHAZ (fine-grain HAZ ) and ICHAZ ( intercritical temperature HAZ ). The microstructures in the HAZ are all composed of bainite-like structure.The microstructare in the CGHAZ mainly consists of lath-like bainite and granular bainite . The influences of heat input and t8/5 on the hardness in the HAZ of RPC steel are notable. With the increase of heat input and t8/5, the softening tendency of HAZ becomes obvious. The hardening phenomenon that normally occurs in the CGHAZ does not take place with this steel in the range of experimental conditions. The softening in the ICHAZ is bound to occur. Hence appropriate welding technologies need to be selected.     

Metastable eutectic formation in Ni- Al alloys

Directional solidification experiments have been carried out at low rates in alloys near the N13AI composition in the Ni-AI binary alloy system. Results confirm an earlier study at high rates showing that the eutectic in this system occurs between the β and γ′ phases. It is shown that under certain composition and growth conditions a metastable eutectic between the β and γ phases forms in these alloys. Analysis of the decomposition of this metastable eutectic into the γ′ phase and additional composition measurements are used to provide an improved version of the phase diagram near the N13AI composition.     

The form error prediction in side wall machining considering tool deflection

In this research, an effective method for the form error prediction in side wall machining with a flat end mill is suggested. The form error is predicted directly from the tool deflection without surface generation by cutting edge locus with time simulation. The developed model can predict the surface form error accurately about 300 times faster than the previous method. Cutting forces and tool deflection are calculated considering tool geometry, tool setting error and machine tool stiffness. The characteristics and the difference of generated surface shape in up milling and down milling are discussed. The usefulness of the presented method is verified from a set of experiments under various cutting conditions generally used in die and mold manufacturing. This study contributes to real time surface shape estimation and cutting process planning for the improvement of form accuracy.