耐热粉末铝合金筒体热旋成形试验

介绍了喷射沉积耐热铝合金管坯经挤压变形 ,变薄旋压筒体的研制过程 ;重点论述了热旋成形筒体的工艺路线。试验探讨了耐热铝合金的旋压温度为 35 0～ 45 0℃ ,道次变薄率约为2 0 % ,累计变薄率约 5 0 % ,需中间退火 ,退火温度宜取 35 0℃。热旋结果认为 ,喷射沉积耐热粉末铝合金铸坯直接热旋成形困难 ,需经挤压比大于 4的变形致密 ,有助于热旋成形。耐热粉末铝合金挤压坯加热变薄旋压 ,应采用小压下量多道次的变形过程 ,逐渐细化晶粒组织 ,才能旋出综合性能良好的筒形件。     

旋轮形状对杯形件单道次拉深旋压成形的影响

对杯形件单道次拉深旋压成形过程进行了分析,重点讨论了具有两个圆弧工作面的旋轮形状对成形过程的影响.研究结果表明,不同的旋轮形状不仅改变了旋压力p的大小,并且由于其对厚度应变ε的分布影响较大而造成整个旋压过程变形特征的改变,从而导致在工件的不同部位产生破裂.     

碟形封头冷旋压成形时的数值分析及旋压力计算

建立了碟形封头冷旋压的三维有限元数学模型 ,分析了封头在冷旋压成形过程中应力应变的分布规律 ,计算了旋压力并分析了其变化的原因 ,为更有效地进行旋压加工前的科学预测、工艺优化和进一步定量控制提供了可靠方法和依据     

大中型风机叶轮前盘的简易旋压成形

提出了一种适用于单件或小批量生产大中型风机叶轮前盘的新工艺——滚轮芯模简易旋压成形工艺,这种工艺经济实用,简便易行,可在一定范围内推广应用。     

滤料的应用及其发展

重点介绍原材料和纺织工艺对滤料发展的影响、国内外滤料发展的最新动向和最新的成果，指出了滤料发展存在的问题和今后发展的方向。     

Melt Processing of a New Biodegradable Synthetic Polymer in High-Speed Spinning and Underpressure Spunbonding Process

A new biodegradable synthetic polyesteramid (PEA) was characterized by means of thermogravimetry (TG) differential scanning calorimetry (DSC) and dynamic rheological measurements. Two glass transition ranges at about –33 and 38°C and a melting enthalpy of 33 J/g were measured, indicating that PEA is an immiscible blend of two components with a small crystalline part. The material was spun in a high-speed spinning process within the range of 2,000–6,000 M/min and an underpressure spunbonding process within the range of 3,600–7,700 M/min. The textile physical properties of the fibers were 100 MPa tenacity at an elongation at break of 30%, and an E-modulus of 0.5 GPa. The mass per unit area of the spunbonded nonwovens ranged from 70–159 g/M ². The strength of the spunbonded nonwovens was 28–51 N and 42–74 N in machine and cross direction, respectively. The air permeability of the nonwovens decreased at high air velocities and more fineness of the filaments from 1240–380 l/M ² s.     

大直径薄壁钢筒变薄旋压成形工艺研究

论述大径比高精钢筒变薄旋压成形试验过程 ,通过确定合理工艺过程 ,选择最佳工艺参数 ,从而旋出了合格筒体。结果表明 ,D40 6A钢退火状态变薄旋压性能良好 ,旋压塑性变形稳定 ;有效控制扩径量和壁厚差是变薄旋压成形和获取高精钢筒的关键     

导布辊辊筒加工用辘头、辘模和辘床

分析了导布辊辊筒加工中的一个重要工艺辘圆工艺。论述了完成这个工艺的装备 ,辘头、辘模和辘床的一些设计方法     

AB工艺处理毛纺废水的探讨

对AB工艺处理毛纺废水进行了系统研究 ,在预处理和生物吸附处理阶段作了一些技术改进。并结合江苏箭鹿集团第一毛纺厂处理毛纺废水的工程实例 ,对其工作原理、工艺流程、设计参数以及效益等作了详细的分析     

Studying soil organic matter using 13C CP-MAS NMR: the effect of soil chemical pre-treatments on spectra quality and representativity

¹³C CP-MAS NMR spectroscopy is a technique that has proved to be useful in studying soil organic matter (SOM). Nevertheless, NMR spectra exhibit a weak signal and have very low resolution due to: the low natural abundance of ¹³C (1.1 % of C) in SOM, the generally low SOM content of soils, and the presence of paramagnetic impurities. This paper studies the effects of soil chemical pre-treatments on ¹³CP-MAS NMR spectra quality and spectra representativity i.e. soil C mass balance.

After chemical pre-treatment to increase total organic carbon (TOC) content and C/Fe ratio, eight soils characterized by different levels of organic carbon content and C/Fe ratios were studied using ¹³CP-MAS NMR. Moreover, where chemical treatments were not applicable due to high carbon losses, the number of ¹³CP-MAS NMR scans was increased in order to obtain satisfactory spectra.

Results show that chemical pre-treatment of soils with C/Fe > 1 caused high C losses. Bulk soils were therefore studied by increasing the number of ¹³CP-MAS NMR scans. Acceptable spectra were obtained from 8K scans (1K = 1024 transient). On the other hand, even when a large number of scan (32K) are used, soil with C/Fe < 1 cannot be studied. As these soils are characterized by low C losses after HCl treatments (range of 2.9–25.4%), a pre-treatment of at least 1.39 mol l⁻¹ HCl removes excess Fe and at the same time increases C/Fe ratio resulting in 32K scans providing good spectra.