轴流转桨式水轮机转轮缸体排油阀密封结构改进

某轴流转桨式水轮机转轮缸体排油阀密封形式和丝堵结构设计不合理,导致安装后出现漏油现象。通过对排油阀与丝堵的密封形式和丝堵结构的改进,解决了丝堵无法达到预紧力和密封断裂等问题。实际应用表明,改进后的密封结构解决了缸体漏油问题,排油阀丝堵可以容易地紧固到设计扭矩,并且拆装方便。     

凸轮精冲复合模设计

分析比较了凸轮的新旧加工工艺。在普通压力机上采用改进后的精冲技术 ,可提高工件的尺寸精度及降低表面粗糙度值 ,减少机械加工 ,从而提高生产效率及降低产品成本。介绍了凸轮零件的排样、精冲压力计算及模具结构设计。     

精冲过程的计算机模拟及工艺参数优化

本文根据精冲工艺的工况，采用计算机仿真技术分析了精冲成形过程，并对工艺参数进行了优化设计。     

Ф400mm自动轧管机有限元模拟及工艺优化

为提高包钢钢联股份有限公司Ф400mm自动轧管机轧制的钢管壁厚精度．进行了轧卡试验及有限元模拟分析，获得了钢管在孔型中的应变分布状况，经过优化孔型参数和改进轧辊孔型，使轧制的钢管横向和纵向壁厚偏差大大减小。     

冲孔落料折弯复合模设计

介绍了在冲孔落料后用可滑动折弯凹模与可滑动折弯凸模相结合对薄片形件进行弯边，模具结构简单、巧妙，对同类产品具有一定的借鉴作用。     

聚氨酯橡胶冲裁模具的设计探讨

在冲裁薄料时，通常要用的是无间隙的冲模。以聚氨酯橡胶代替通常钢模中的凹模或凸模是比较有效的方法之一。在了解聚氨酯橡胶冲裁的过程和聚氨酯橡胶冲裁的工艺性的基础上，必须掌握聚氨酯橡胶；中裁模具主要零件的设计要领。     

T91毛管穿孔工艺的研究

针对热轧穿孔T91管坯生产过程中产生的顶头耗损严重,毛管内折和毛管端部外表面裂纹等问题,通过采取重新制定合理的加热参数、调整穿孔参数和改进工模具,有效解决了穿孔顶头损耗大,毛管内、外表面质量波动较大的问题,使顶头的小时穿孔支数达到125支,平均每个顶头的穿孔支数达到400支左右,大大提高了生产效率,成本下降显著。     

电机冲片分离模改进

通过对电机冲片生产过程中,制件尺寸超差现象进行分析,研究冲裁过程中产生变形的原因,对模具尺寸进行修正,解决了生产过程中冲片尺寸超差的问题。     

Method for calculating dynamic yield stress of fresh cement pastes using a coaxial cylinder system

The calculation of the rheological parameters of fresh cement pastes plays a key role in understanding the rheology of cement-based mixes. Because cement paste is not a simple Bingham fluid, a suitable nonlinear model must be found for characterizing its flow. A test system in which the rotational speed or shear rate can be changed in multiple steps is regarded as a suitable rheological test protocol because the paste reaches a steady state. Furthermore, theoretical derivations show that the solution of the Couette inverse problem corresponding to the modified Bingham model and the Herschel–Bulkley (H-B) model is complex. However, a comparative analysis revealed that the yield stress of fresh paste could easily be obtained through a calculation process based on a Parabolic model. This study presents the complete calculation procedure for this model. The influence of the plug flow is considered, and test points with low minimum shear stress (τ_min) are excluded. Finally, the accuracy of the proposed method is verified through comparisons with the results obtained using mini-cone slump tests. These results show that the dynamic yield stress calculated using the expression of the Couette inverse problem based on the Parabolic model in consideration of the plug flow is very close to the yield stress obtained using the mini-cone slump flow test. This proves that the proposed method could precisely characterize the dynamic yield stress of cement pastes.     

穿孔顶头使用寿命浅析

分析了顶头的各种失效形式及产生的原因,提出了提高顶头使用寿命的措施。即应根据顶头的具体工作条件,制定合理的热处理工艺;采用复合处理工艺,解决好顶头单纯氧化处理热强性不高的问题等。