浅谈液压夹具在转向油缸铸造缸盖加工上的应用

随着液压夹具在机械加工中运用推广,该公司引用液压夹具多年来取得一定成效,文章针对转向油缸的铸造缸盖铣、钻序前后加工工装进行对比分析,重点突出应用全自动液压夹具后可提升装夹效率、加工质量以及降低劳动强度等,可以在不添置设备的情况下,满足产能提升的需求。     

常压干燥合成水玻璃基SiO_2气凝胶

以水玻璃和双氧水为原料一步合成二氧化硅湿凝胶,经老化、溶剂置换及三甲基氯硅烷修饰后,并于常压干燥后获得二氧化硅气凝胶。样品经低温N_2吸附-脱附、红外光谱和扫描电镜测试表明所得二氧化硅气凝胶具有三维多孔结构,且其比表面积可达482 m~2·g~(-1)、平均孔径为24.9nm及表观密度为0.12g·cm~(-3)。     

离子液体气体干燥技术的研究进展

离子液体（ionic liquids, ILs）被视为化工中传统溶剂的优良替代物，使用它们作为溶剂吸收可凝性气体时，具有溶剂损失少、无腐蚀和稳定性强等优点。一些ILs具有很强的吸水性，所以在气体干燥领域ILs受到了广泛关注。本文介绍了用于预测气体在ILs中溶解度的预测型分子热力学模型和气体在ILs中的实验测量方法，具体分析了ILs对CH₄、CO₂等气体的干燥机理和工艺，最后对ILs用于气体干燥的基础研究作出展望。     

基于ABAQUS的发动机缸盖工装强度分析

分析计算某型号发动机缸盖及工装的应力与局部位移,基于HyperMesh软件建立缸盖及工装的仿真模型,使用ABAQUS软件进行静力学计算,对处于夹紧状态下的发动机缸盖进行4个典型工位的加工工况分析计算,得出工件加工位置最大位移与工装所受最大应力。通过强度和位移校核,最终结果满足缸盖的加工需求,为工艺制定提供了有效的数据支持。     

手机保护套模内热切模具设计

针对传统冷流道模具需要人工去除浇注系统凝料和冷切浇口技术效果不佳的现状，以某智能手机保护套为例，设计了具有热切浇口功能的手机保护套模具。首先根据产品搭接侧浇口的结构特点，设计了能够将浇口切除干净，且运动准确的切刀装置，并利用有限元分析方法确立了合适的进刀时间和驱动油缸。然后设计了合理的顶出和冷却机构，保证产品和浇注系统凝料在分离冷却后分别被安全顶出。     

Physicochemical characteristics,antioxidant capacity and thermodynamic properties of purple-fleshed potatos dried by radio frequency energy

Abstract

The impacts of using radio frequency (RF) energy to dry purple-fleshed potatoes were investigated and compared to infrared radiation (IR) and microwave (MW) drying techniques. The gelatinization rate, color, flavor, morphological, and structural characteristics, thermodynamic properties, as well as antioxidant capacity were examined. The results indicated that the drying time of RF (70?min) and MW (21?min) were shorter than IR (105?min). The gelatinization ratio of MW, RF, and IR were 94.4?±?2.0, 88.3?±?1.4, and 64.5?±?1.1%, respectively. The degree of crystallization of purple-fleshed potato powder decreased with all three drying methods. RF-dried potatoes were able to retain higher polyphenols (loss rate: 4.3%), total anthocyanin (3.7%), and total flavonoid content (35.1%), whereas IR showed the lowest retention. The content of polyphenols also decreased significantly. Furthermore, after RF heating, the scavenging of free radicals was higher compared to MW and IR.     

Moisture transfer and stress development during high-temperature drying of Chinese fir

Abstract

The knowledge of moisture content (MC) and drying stress are crucial parameters to control the drying process and maintain the quality of dried wood. Herein, we investigated the pattern of moisture transfer and stress development in Chinese fir during the high-temperature drying process. The MC in each layer of lumber was separated into bound water and free water via nuclear magnetic resonance (NMR), and the drying and residual stress were measured using prong test method. There was different MC in each layer along the thickness, resulting in an MC gradient that initially increased and then decreased, which is consistent with the trend of drying stress. The T₂₁ peak indicating bound water shifted to the left especially when MC was below the fiber saturation point, signifying that the discharge of moisture became difficult with prolonged drying time. The ratio of bound water to free water was different in each layer, indicating that the moisture transfer was different along the thickness. Furthermore, the residual stress was greater than the corresponding drying stress though the disparity reduced gradually, which suggests that the MC gradient was the largest affecting factor for drying stress at high MC stages but decreased to some extent as the drying process continued.     

Contribution of the Internal and External Oxygen to the Oxidation of Microencapsulated Fish Oil

Microencapsulation aims to protect polyunsaturated fatty acids against oxidation by embedding oil droplets in a solid matrix. In such a system the internal (dissolved and entrapped) and external (in the environment) oxygen can be differentiated. The study aims to quantify the impact of both oxygen sources on the oxidation of microencapsulated fish oil. The impact of the solubilized oxygen in bulk fish oil is investigated by saturating the oil with nitrogen, synthetic air, and pure oxygen. Even though more dissolved oxygen results in more oxidation products, the difference between the oxidation of the nitrogen and air saturated oil is significant but low. For encapsulated fish oil powders, the internal oxygen is modified by preparing oil‐in‐water emulsions under atmospheric and inert conditions. The feed is atomized and spray dried with either nitrogen or air. Powders are stored under vacuum and in vials and the hydroperoxides and anisidine value are determined in the total‐ and encapsulated oil. The internal oxygen has a minor impact, whereas the external oxygen is the main determinant for autoxidation. Apart from oxidizing the non‐encapsulated oil, the external O₂ penetrates into the particle and reacts with the encapsulated oil. Practical Applications: Comparing the contribution of the internal and external oxygen to the oxidative stability shows that the internal O₂ plays a minor role and can be neglected. This means that the emulsion preparation as well as the spray drying process can be conducted under ambient conditions. An inert production is not extending the shelf life significantly as long as the external O₂ determines oxidation. The focus should be on optimizing the diffusion barrier properties of the wall matrix to reduce the penetration of the external oxygen into the particle system. Alternatively, packaging solution reducing the external O₂ will extend the shelf life of the microencapsulated oil.     

意大利Corefon涂料在中国的应用

分析意大利corefon涂料的特性,研究在不同铸件应用中的典型案例。结果表明,corefon涂料可以提升汽车发动机缸体缸盖内腔清洁度、解决工程液压阀体内腔油道粘砂烧结问题、提高增压器零部件涡轮涡壳气道光洁度。铁型覆膜砂外型喷涂corefon涂料后,浇铸的铸件表面光滑,无粘砂、无烧结,不需要人工打磨和特别抛丸处理。充分体现了corefon涂料在性能上的优越性,可以解决铸造厂铸件内腔粘砂、烧结、表面粗糙的问题。     

Transformation of the reabsorption characteristics of lignite treated by low and high temperature drying process

Abstract

The reabsorption characteristics of the lignite treated by low and high temperature drying process were addressed in the paper. The information about the moisture form, functional groups, effective water-filled porosities and equilibrium moisture content of the lignite before and after the drying process was investigated using Differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and a self-made reabsorption device, respectively. The results show that the low drying temperature (140, 190, 230?°C, 10?min, N₂) has little impact on the effective water-filled porosities of the resulted samples, whereas it has a great influence on the main oxygen-containing functional groups, which amount firstly decreases and then increases with the drying temperature increasing. In the case of the lignite samples dried under high-temperature (600, 700, 800?°C, 30?s, N₂), the amount of the effective water-filled porosity of the sample decreases and the amount of oxygen-containing functional groups increases as the temperature increasing. The reabsorption capability of the high temperature dried sample is much lower than that of the sample treated under low drying temperature. The reabsorption characteristics of the low-temperature dried samples are affected by the amount of the oxygen-containing functional groups, while the effective water-filled porosity is main factor for the lignite samples derived from high temperature drying process. Moreover, the work gives a good evidence that the high-temperature drying process is an effective choose for lignite upgrading.