电冰箱的除霜方法及装置

文章介绍了电冰箱结霜的原因 ,霜层的影响 ,以及除霜的方式方法及设备 .     

静压刚性小桩复合地基的施工效应研究

静压刚性桩复合地基具有挤土效应,在桩周一定范围内土体受到侧向挤压,土体孔隙比降低、抗剪强度增强,本文考虑弹塑性土体的侧挤作用,采用小孔扩张理论分析静压预制砼小桩的施工效应问题。     

The Effect of Variable Blank-Holder Forces on the Formability of Aluminum Alloy Sheets during Sheet Metal Forming

In this paper, the effect of variable Blank-holder forces (VBHF) on the strain path during sheet metal forming has been investigated by numerical simulation and experiments. The formability of select aluminum alloy sheet was evaluated by theory prediction of forming limit curve based on the M-K method. The effect of different VBHF on the formability was presented. In order to verify the predictions of strain path, experiments are being carried out using a recently-built multi-points variable blank-holder forces hydraulic press. The results show that large side BHF with small comer BHF during rectangular box deep drawing can improve the formability of the selected aluminum alloy sheet     

超塑性锌铝共晶合金成形工艺的研究

根据超塑性锌铝共晶合金的力学性能和超塑性变形特点的试验研究结果,分析制定了锌铝共晶合金塑料模成型镶件的成形工艺参数.发现在300℃及小于40MPa的成形温度和成形压力下,可获得形状符合要求的超塑成形模具镶块,同时其镶块具有较高的力学性能:HB100,σb>370MPa,σ0.2>300MPa.     

薄材多点成形中回弹的预测

多点成形技术是三维曲面板类件柔性成形的新技术.在薄板边多点成形中,回弹是一个必须解决的问题.论文中采用显-隐式算法分析了板材厚度、曲率半径对柱面、球面等典型曲面的多点成形回弹的影响,得到了回弹趋势和回弹分布规律,这些结果对多点成形技术具有一定的参考价值.     

Numerical Simulation of Peen Forming

Peen forming is the most important process for the manufacturing of integral wing skin panels. In order to determine peening parameters, an equivalent deformation theory was proposed in which peening parameters are transformed into equivalent nodal forces. In this study, a linear elastic shell finite element method is adopted. Other related problems such as wing skin panel modeling and peening scheme analysis were also outlined. The method has been applied to manufacturing panels of a certain Chinese aircraft and was proved to be effective in reducing peening experimental tests and improving products quality.     

H3PO4-CuO粘结剂在金刚石磨具制备中的应用

采用无机粘结剂H3PO4-CuO取代酚醛树脂粘结剂，制作树脂磨具．CuO粉在890-910℃下灼烧，灼烘后经球磨机破碎，加入H3PO4．AI(OH)3混合液，以及金刚石微粉、白刚玉、填料和其它添加剂等，搅拌均匀．于热压机上加热至140℃．热压成型．脱模后．磨块放置1～2h，于80℃烘干3h．用环氧树脂胶接种在酚醛树脂磨盘上．制作成锋利、耐磨的树脂磨具．     

热连轧精轧工作辊不均匀磨损的产生及对策

文章通过对热连轧精轧工作辊不均匀磨损产生原因的分析 ,制定了有针对性的改进措施 ,在实践中取得了较好的效果     

方以智"光肥影瘦"说的实验研究

文章通过模拟实验指出 ,方以智在“光肥影瘦”说中所做的实验并不是描述光的衍射现象 ,而仅涉及了小孔成像和光的散射现象     

硅钙渣作为水泥原料的研究

本文对硅钙渣作为水泥原料的应用进行了研究.结果表明,在实验室条件下采用90%左右的硅钙渣和10%左右的石灰石两种原料配料,在1350～1400℃下煅烧,可以生产性能合格的625号硅酸盐水泥.硅钙渣主要矿物是r-C_2S,与通常粘土配料的熟料形成热比较,采用硅钙渣配料,约可降低熟料形成热6.3×10~5～8.4×10~5J/kg;与同类型生产方式比较,约可节省能耗20%左右.同时,生产1t熟料可利用400～500kg的粉煤灰.