Relationships between the surface quality of a single crystal copper ingot and the process parameters of a heated mould continuous casting method

The relationships between the surface quality of a single crystal copper ingot and the process parameters of heated mould continuous casting method were studied experimentally using our own design of horizontal heated mould continuous casting apparatus, and the mechanism by which process parameters affect the surface quality of a single crystal copper ingot is analyzed in the present paper. The results show that the process parameters affect the surface quality of a pure copper ingot by affecting the position of the liquid-solid interface in the mould. The position of the liquid-solid interface in the mould must be controlled carefully within an appropriate range, which is determined through a series of experiments, in order to gain a single crystal copper ingot with good surface quality.

Postmastectomy Scar Boost Irradiation Using HDR Surface Mould Brachytherapy by 3D Image-Based Volume Optimization

Introduction: During postmastectomy radiotherapy (PMRT), it is recommended to boost the postmastectomy surgical scar with additional 10 Gy in 5 fractions in the patients with close or positive surgical margins. The electron beam therapy, though cumbersome, is usually preferred since it has the desired rapid fall of a dose beyond R85. An alternative but easier and reproducible treatment method for PMRT surgical scar boost using 3D CT image-based HDR surface mould brachytherapy is introduced and analyses of the target coverage and dose nearby organs-at-risk (OARs) using this method are evaluated in this study. Methods and Materials: This study includes twelve patients (five left-sided and seven right-sided chest wall), who were planned and treated with CT-image based surface mould HDR brachytherapy for chest wall scar boost (CWB) using Catheter Flap SetTM (Varian Medical Systems, USA) that were given concurrently during external beam radiotherapy (EBRT) treatments. Since no guidelines are available for delineating clinical target volume (CTV) structure to be used for postmastectomy scar boost, the CTV in this study was a uniform 5-mm thick volume drawn at 5 mm beneath the skin (CTVhdr_evl) and its extent was made conforming to the boost area marked on the skin and made visible in CT images by radiopaque wires. Results: Prescribed dose (PD) to CTVhdr_evl is 7.5 Gy in 3 fractions, and 2.5 Gy per fraction. The CTVhdr_evl volume receives the PD with mean V100%, V98% and V95% values which are 98.57%, 99.63% and 100% respectively. The mean dose for heart (MHD) is 2.71 Gy in left-sided CWB and 1.80 Gy in right-sided CWB plans. Mean lung dose (MLD) is 2.48 Gy for ipsilateral lung and 0.76 Gy for contralateral lung. Maximum dose to contralateral breast is 4.93 Gy and the mean dose is 0.79 Gy. The mean percent dose to the skin volume overlying the CTVhdr_evl is 138.6% and 3.7% of skin volume received 200% of the PD. Conclusion: The 3D image-based HDR surface mould achieved good CTV coverage with acceptable doses to OARs. Patient preparation, treatment planning, and execution in this method are less cumbersome and reproducible. Thus surface mould using flap applicator can be used whenever postmastectomy surgical scar boost is required.

Surface Waviness in Grinding of Thin Mould Insert Using Chilled Air as Coolant

On going trend of miniaturization in electronic rel at ed parts, which is an average of two times in every 5～7 years introduce grindin g challenges. In grinding process, the surface waviness control of thin parts is an ardent task due to its warpage, induced by the high specific grinding energy (2～10 J/mm 3). Therefore, coolant is often used to avoid thermal damage, obtai n better surface integrity and to prolong wheel life. However coolant, the incomp ressibility media introduce high forces at the grinding zone creating dimensiona l as well as shape instability. In view of these situations chilled air was ap plied in place of conventional coolant. The chilled air is produced using a two -stage vapor compression refrigeration cycle with characteristics of: temperatu re -35 ℃, pressure 0.2～0.3 MPa and flow rate 0.4 m 3/min. Also traces of eco - oil mist that encompass the chilled air are supplied to the grinding zone. B oth chilled air and eco-oil mist are applied through two independent paths of a specially designed twin compartment nozzle for maximizing the penetration. This paper investigates the grinding characteristics of mold insert which is closer to M2 tool steel (component widely used in connector industries) when using chil led air as coolant media. Grinding experiments were conducted using a vitrified bond CBN wheel (B91N100V) and a surface grinder. Initial study was focussed on establishing the most suita ble clamping method for the thin mold insert. FEM analysis and grinding experime nt studies were performed to quantitatively analyze the clamping induced deflect ion. Waviness value (W t) of (24～62) μm was achieved for resin clampi n g whereas (4～8) μm, (4～6) μm were achieved for magnetic and wax clamping res pe ctively. Wax clamping is predominantly used in all the grinding experiments that characterize the grinding process, which use chilled air as the coolant media. Between 0.15 to 0.9 mm 3/mm.s of specific material removal rate, ground sur face temperature of mold insert was increased from 0.3 ℃ to 59.7 ℃ for chi lled air. For the similar grinding conditions with the coolant fluid an increase from 0.9 ℃ to 14.4 ℃ was recorded. With increase of specific material removal rate from 0.15 to 0.65 mm 3/mm.s, F t/F n ratio was increased from (0.2 to 0.4), (0.6 to 1.67) for wet coolant and chilled air respectively. Despite of high F t/F n ratio and ground surface temperature, chilled air method has shown a surface waviness, W t from (2 to 5.6) μm. Microstructure examination of chilled air produced ground surface was comparable to those of using coolant fluids. Surface finish, R a of (0.45～0.7) μm was achieved for mold insert . This work will enable to have clear understanding about the quantitative influe nce of chilled air as well as the clamping method against the surface waviness o f thin mold insert.

Hardening Effect on Machined Surface for Precise Hard Cutting Process with Consideration of Tool Wear

During hard cutting process there is severe thermodynamic coupling effect between cutting tool and workpiece, which causes quenching effect on finished surfaces under certain conditions. However, material phase transformation mechanism of heat treatment in cutting process is different from the one in traditional process, which leads to changes of the formation mechanism of damaged layer on machined workpiece surface. This paper researches on the generation mechanism of damaged layer on machined surface in the process of PCBN tool hard cutting hardened steel Cr12MoV. Rules of temperature change on machined surface and subsurface are got by means of finite element simulation. In phase transformation temperature experiments rapid transformation instrument is employed, and the effect of quenching under cutting conditions on generation of damaged layer is revealed. Based on that, the phase transformation points of temperature under cutting conditions are determined. By experiment, the effects of cutting speed and tool wear on white layer thickness in damaged layer are revealed. The temperature distribution law of third deformation zone is got by establishing the numerical prediction model, and thickness of white layer in damaged layer is predicted, taking the tool wear effect into consideration. The experimental results show that the model prediction is accurate, and the establishment of prediction model provides a reference for wise selection of parameters in precise hard cutting process. For the machining process with high demanding on surface integrity, the generation of damaged layer on machined surface can be controlled precisely by using the prediction model.

Diamond machining of sinusoidal grid surface using fast tool servo system for fabrication of hydrophobic surface

Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room temperature which transfers the FTS fabricated sinusoidal grid surface to the flat film with UV-moulding process was described.A piezoelectric-assisted FTS with high band width of 2 kHz,travel range up to 16 μm and the compact mechanism structure was designed for the sinusoidal grid surface machining and the dynamic performance testing of FTS was described in detail.Machining results indicate that the dimensions of sinusoidal grid change with the variation of the FTS machining condition.Wetting properties of UV-moulded surface were evaluated,the best contact angle was measured to be 120.5° on the sinusoidal grid surface with profile wavelength of 350 μm and peak-to-valley amplitude of about 16 μm.

倒角结晶器铜板镀层崩边原因分析及控制

针对倒角结晶器窄面铜板镀层崩边问题,从结晶器传热、铜板结构、镀层性能等角度分析原因,提出采用激光熔覆技术对铜板表面进行强化的解决方案,并开展了工业试验进行验证。研究结果表明:铜板角部温度高、镀层厚度大、镀层与铜板热变形差异大、在线调宽状态下铜板侧面清渣不彻底是影响镀层发生崩边的重要原因。采用激光熔覆技术后,倒角窄面铜板的过钢量由5万t提高到10万t以上,当过钢量达到8.7万t时,熔覆层仍未出现角部崩边、剥落及因磨损过大引起的局部露铜现象。

减少冷轧低碳钢轧材表面夹杂缺陷实践

针对冷轧低碳钢轧材表面夹杂缺陷问题,分析主要原因是结晶器保护渣卷入钢水导致,采取优化保护渣理化性能,优化铸机拉速、水口浸入深度和氩气流量等措施后,降低了卷渣风险,冷轧低碳钢表面夹杂缺陷指数由4降至1,提高了产品表面质量。

宽厚板结晶器电磁搅拌的设计与运用

由于宽厚板对结晶器稳定性的高要求,原有结晶器电磁搅拌技术已难以满足生产宽厚板的要求。为此在宽厚板上采用分段式铁芯磁路设计能增强结晶器水箱的强度和使用稳定性要求。通过数值模拟的方法,对宽厚板铁芯分段式结晶器电磁搅拌的磁路结构进行计算和设计,考察了铁芯饱和尺寸和最大电流作用下的结晶器内磁场分布特征。通过一年的使用数据,使用宽厚板电磁搅拌、厚板探伤降级率、厚板夹渣降级率、厚板气泡降级率及热轧卷渣封锁率都有显著的下降,表面质量改善较好。

门套用复杂截面表面结皮UPVC微发泡挤出模具研制

以门套为例,在65锥形双螺杆UPVC微发泡配方体系条件下,通过仿真设计和生产线调试验证,研制了复杂截面表面结皮微发泡挤出模具。其中,间隙式外放发泡的水冷口模结构,通过调整水冷口模板间隙的大小和流道的长短来控制物料的流动速度,进而调节结皮厚度和制品密度;干湿定型结合的定型模中,干式定型采用反向弧度补偿发泡材料的不均匀收缩,在湿式定型段,采用浸浴式真空涡流水箱对发泡制品进行充分冷却和定型。

激光加工技术在模具制造中的应用与展望

阐述了激光切割、激光焊接、激光表面处理等加工技术在模具制造中的应用现状,通过案例和实践经验,展示了激光加工技术在提高模具制造效率、降低生产成本、改善模具质量等方面的优势和成果,并展望了激光加工技术在模具制造领域的发展方向。

易切削非调质汽车用钢表面裂纹形成机理及工艺优化

易切削非调质汽车用钢采用410 mm×530 mm大断面连铸坯轧制成规格Φ130~220 mm的钢材,表面探伤合格率较低,钢材表面出现裂纹缺陷,通过对钢轧全流程系统分析发现为连铸坯表面角部横裂纹和星状裂纹所导致,其与结晶器铜管倒锥度及R角不合理、钢中硫化物形态及偏析聚集、保护渣理化指标适配性差、二次冷却系统工艺有待优化等方面原因有关。通过改进结晶器铜管倒锥度及R角、微钙化处理工艺改善钢中硫化物形态、调整结晶器保护渣的理化性能指标、优化二次冷却系统,酸洗试样表面质量合格率提高了近30%,铸坯表面磁粉探伤合格率提高至99.2%,连铸坯所对应轧材的表面探伤最高炉次达98.6%、最低炉次达92.4%,铸坯纵剖酸洗试样V型偏析改善明显,且碳、硫的中心偏析指数分别为1.04、0.97,符合±0.05的高标准均质化要求。

Iron casting skin management in no-bake mould – Effects of magnesium residual level and mould coating

The relative performance of coatings for furan resin sand moulds [P-toluol sulphonic acid(PTSA) as hardener] [FRS-PTSA moulds], was compared by analyzing the surface layer for degenerated graphite in Mg treated iron with 0.020 wt.% to 0.054 wt.% Mgres. It was found that the iron nodularising potential(Mg, Ce, La content) and whether the mould coatings contained S, or were capable of desulphurizing were important factors. These moulds have S in the PTSA binder, which aggravates graphite degeneration in the surface layer, depending strongly on the Mgres with lower Mgres increasing the layer thickness. The application of a mould coating strongly influenced graphite deterioration in the surface layer of castings. It either promoted graphite degeneration to less compact morphologies when using S-bearing coatings, or conversely, limited the surface layer thickness using desulphurization type coatings. Independently of the S-source at the metal – mould interface, the presence of sulphur had an adverse effect on graphite quality at the surface of Mg-treated irons, but its negative effect could also reach the graphite phase within the casting section. If the coatings employed desulphurization materials, such as Mg O, or a mixture(Ca O + Mg O + Talc) or Mgbearing Fe Si, they protected the graphite shape, improving graphite nodularity, at the metal – mould interface, and so decreased the average layer thickness in FRS-PTSA moulds. Fe Si Mg was highly efficient in minimizing the casting skin by improving graphite nodularity. It is presumed that the Mg O or(Mg O + Ca O + Talc) based coatings acted to remove any S released by the mould media. The Mg-Fe Si coatings also reacted with S from the mould but additionally supplemented the Mg nodularising potential prior to solidification. This dual activity is achievable with coatings containing active magnesium derived from fine Mg-Fe Si materials.

<i>Stachybotrys chartarum</i>(<i>atra</i>) spore extract alters surfactant protein expression and surfactant function in isolated fetal rat lung epithelial cells, fibroblasts and human A549 cells

Moulds, notably Stachybotrys chartarum (atra), are constant contributors to air pollution particularly to air quality in buildings. The spores themselves or their volatile organic products are present in variable amounts in almost all environments, particularly in buildings affected by flooding. These moulds and products can account for the sick building syndrome and have been tied to such occurrences as the outbreak of pulmonary hemosiderosis and hemorrhage in infants in Cleveland, Ohio. The present study was designed to investigate the effects of S. chartarum extracts on surfactant protein expression, surfactant quality and cell survival in the developing lung. S. chartarum extracts were incubated with cultures of several cell types;isolated fetal lung type II cells and fetal lung fibroblasts, and human lung A549 cells, a continuously growing cell line derived from surfactant producing type II alveolar cells. MTT formazan assays were employed to test cell viability. The synthesis and release of the predominant surfactant protein A (SP-A), which is involved in the regulation of surfactant turnover and metabolism, and surfactant protein B (SP-B) involved in shuttling phospholipids between surfactant subcompartments was also assessed. Antibodies to these proteins and western blotting results were used to assess the quantity of protein produced by the various cell types. A novel approach utilizing captive bubble surfactometry was employed to investigate the quality of surfactant in terms of surface tension and bubble volume measurements. Electron microscopy was used to examine changes in cellular structure of control and S. chartarum-treated cells. Results of the study showed that exposure to the S. chartarum extracts had deleterious effects on fetal lung epithelial cell viability and their ability to produce pulmonary surfactant. S. chartarum extracts also induced deleterious changes to the developing fetal lung cells in terms of expression of SP-A and SP-B as well as to the surface tension reducing abilities of the pulmonary surfactant. Ultrastructurally, spore toxin associated changes were apparent in the isolated lung cells most notably in the lamellar bodies of fetal rat lung alveolar type II and human A549 cells. This study has demonstrated the potential damage to surfactant production and function which may be induced by inhaling S. chartarum toxins.

《材料加工工艺学》研究生课堂教学改革研究与实践

鉴于研究生课堂知识教育与课题研究教育之间不能有机衔接,以《材料加工工艺学》课程中模具零件表面强化及修复内容为例,实践课堂教学改革。教学模式由教师、学生共同完成,小组协作完成大作业,考核方式综合教师评价与学生评价,激发了研究生对课程内容的兴趣及主动学习的积极性,同时培养了学生自学、研究的热情,锻炼了研究生表达、交流、协作的能力,为较好地从课堂教学教育过渡到科研阶段打下基础。

汽车玻璃窗导轨注射模设计

分析了汽车玻璃窗导轨的结构以及其在汽车中的主要作用,并指出其内表面的3个扣位应采用不同的脱模结构,为了消除玻璃窗导轨外表面的注射缺陷,采用2个扇形浇口从待成型塑件内表面进浇,还分析了成型塑件内表面向外翻边扣位嵌套滑块结构、向内翻边扣位组合斜推结构。模具经实际生产证明:结构设计合理,生产效率高,使用寿命长,能保证正常生产。

复合材料成型模具补偿及构件自适应调整方法研究

复合材料构件固化变形后进行模具补偿需要对构件有限元模型进行重新建模,效率低,工作量大且缺乏验证,针对复合材料成型模具型面补偿后需要调整对应的复合材料构件有限元模型的问题,提出了一种复合材料成型模具型面补偿及构件自适应调整的方法,采用虚拟材料模型实现了构件网格与补偿后模具网格相互贴合。使用典型件验证了方法的正确性,并依据T形加筋壁板构件实例讨论了在此方法下的试验结果。结果表明:(1)通过模具型面补偿,能够使T形加筋壁板和复杂筒形壁板构件固化变形量明显降低;(2)使用本文提出的方法进行T形加筋壁板固化试验,可得试验偏差测量值与数值模拟偏差值的最大相对误差为17.20%,满足工程验收标准;(3)使用本文复合材料固化成型模具型面补偿及构件有限元自适应调整方法能够避免模具补偿后构件有限元模型重构操作,提升模具补偿效率,提高结果准确性。

电子产品表面涂层用防霉剂对霉菌生长影响的研究

针对生产过程中遇到的一系列霉菌问题,首先对某电子产品表面涂层的霉菌等级进行测试并分析归纳,其次制定了相应的试验方案,通过试验验证获得了具备更高霉菌等级的改善途径,提高了产品表面涂层的抗霉菌能力。

运载火箭栅格舵舵面铸造成型技术研究

栅格舵是一种运载火箭气动控制机构,在火箭子级回收阶段发挥重要作用。针对栅格舵舵面需求量大,分析现有拼焊加工方法存在的问题,从提高栅格舵舵面加工可靠性出发,提出舵面铸造成型方案,对舵面结构实施优化,开展铸造成型技术攻关,进行了工艺设计、铸造数值模拟仿真、试件生产及检测,获得了满足技术指标要求的产品。研究表明:与拼焊工艺相比,采用整体铸造成型技术可有效解决栅格舵装配变形、焊接缺陷等问题,可提高产品可靠性,对设计制造可重复使用火箭具有一定指导意义。

非球面模具斜轴磨削工艺参数优化与试验研究

针对纳米加工中碳化钨模具表面波纹度对非球面玻璃成像性能影响的问题,通过对单点斜轴磨削中的磨削刀具振动分析和磨削理论残余误差分析,阐述磨削工艺参数对表面波纹度的影响机理。结合磨削试验对磨削工艺参数进行优化,得到理想的磨削工艺参数:主轴转速40000~45000 r/min,工件转速为200 r/min,工作台轴向进给速度为0.1 mm/min,磨削深度为0.1μm以下时,表面波纹度可达到理想的均匀交叉状态且表面波纹度wz值可控制在30 nm以内。

真空浇注过程中高温合金锭表面气孔产生原因分析

通过对真空感应熔炼工艺生产的高温合金锭表面气孔缺陷进行组织观察,对钢锭模内附着物进行热重分析,研究了真空感应熔炼高温合金锭表面气孔缺陷的形成机理。结果表明,真空浇注期间,钢锭模内壁附着的少量铁锈(Fe_(2)O_(3))会在高温作用下分解为Fe3O4,并在此过程中发生放气,产生的气体在高温下膨胀是导致合金锭表面孔洞缺陷的主要原因。