1000吨冷剪改造

轧钢工区对一轧冷剪安装后存在的以下四个问题：1．1000T冷剪压辊压钢位置距离剪刃较远,剪切时压钢效果不好,剪切后的钢材有额头弯降低钢材等级．2．原冷剪上剪刃是V型剪刃,剪切大规格材时剪体震动偏大,对剪体使用寿命构成很大危害。3．冷剪润滑系统存在缺陷t4．冷剪主传动为皮带传动,极易出现皮带断裂伤人,进行了有针对性的改造,通过对1000吨冷剪改造,大大减少冷剪的故障时间,提高了冷剪得作业率,为轧钢生产顺序提供了强有利的保证。     

圆盘剪剪切中板间隙值浅析

圆盘剪剪切钢板过程中,如果能采用合理适合的方法来调整剪切时的间隙,可以保证切过质量,又能使剪刃承受适合的剪切力避免崩刀的风险和减小磨损。因此对剪切中板的间隙值进行攻关优化,确定调整间隙值的规律。     

中厚板圆盘剪剪切力能参数测试及最佳剪刃间隙数学模型的建立

针对中厚板圆盘剪剪切质量差、剪切力理论计算偏差大等问题开展了生产实测、数据采集、回归拟合处理,得出现有的剪切力理论公式计算结果和实测结果相比误差在-9.56%～+56.5%之间.这些理论公式求解中未考虑随着厚度的增加剪切抗力和抗剪面积的非线性变化,导致剪切力计算结果大幅减小.这些公式适宜于薄规格钢板的剪切力计算,但用于厚板剪切力计算还要进一步完善.同时,建立了一个综合剪切钢板厚度、材料属性、累积剪切面积的圆盘剪剪刃间隙调整模型,并且考虑了刀盘装置在剪切受力过程中的变形对剪刃间隙影响.因此,针对不同的圆盘剪设备,要在该模型中考虑刀轴载荷-变形值的影响,对模型进行修正完善,就可获得适合于自己的间隙调整工艺参数.     

加热卷烟再造烟叶切丝机结构优化设计

截面尺寸小的加热卷烟再造烟叶细丝在剪切过程中易出现质量问题。通过对切丝工艺及设备结构进行优化，设计并研制了一种新型加热卷烟再造烟叶切丝机。纵切辊剪刃侧隙的设计和调整是控制剪切质量的关键。建立了加热卷烟再造烟叶剪切动力学有限元仿真模型，分析了剪切间隙对剪切断面质量的影响，对纵切辊剪刃侧隙进行了优化。优化后剪切间隙为0.25 mm，剪出的加热卷烟再造烟叶丝断面光滑，宽度控制在1mm。通过改进切丝机结构与调整剪切间隙，解决了断裂、毛边等问题，提高了制丝断面质量。     

中厚板切边圆盘剪的设计与结构分析

本文利用计算机辅助系统,借鉴国外的先进技术,自主设计了国产化的中厚板切边圆盘剪,主要阐述了其结构特征及工作原理,并对主要结构件进行了参数制定分析,剪刃重叠量及侧隙对剪切质量的影响。     

基于定尺剪钢板撞击剪刃盒故障浅析与对策

定尺剪是莱钢4300宽厚板剪切线中重要剪切设备,在设备调试试生产期间,定尺剪先后出现不同程度的钢板撞击剪刃盒的问题,严重影响了设备的正常运行,本文主要介绍了问题产生的原因与解决办法。     

螺杆真空泵转子热形变分析及转子优化

建立180L/s螺杆真空泵转子温度场有限元模型,得到其温度场和热形变分布情况,结合热形变结果推导出泵腔内各点冷配合间隙。利用分析结果对螺杆真空泵转子形状进行优化设计。分析结果显示:180L/s螺杆真空泵两转子之间间隙应大于0.28mm,泵腔和转子之间间隙应大于0.20mm。结合所述分析结果对转子形状进行优化,优化后的转子可以减少原有22%冷配合间隙,一定程度上降低泵工作过程中返流量。     

不同构造措施的冷弯薄壁型钢混凝土剪力墙抗剪性能试验研究

研究了一种新型钢-混凝土组合墙体,即冷弯薄壁型钢增强的混凝土剪力墙的抗剪性能。通过5个冷弯薄壁型钢混凝土剪力墙和1个钢筋混凝土剪力墙的拟静力试验,研究了边缘构件纵筋类型及数量、表面钢模网、冷弯薄壁型钢底部锚固等构造措施对剪力墙抗剪性能的影响。研究表明：配筋合适的冷弯薄壁型钢混凝土剪力墙的受剪性能和破坏模式与传统钢筋混凝...     

基于ADAMS的IHI摆式飞剪剪切机构特性分析与优化

为探究IHI摆式飞剪剪切机构特性及优化方法,分析了IHI摆式飞剪剪切机构的结构组成和工作原理, 通过数值方法推导了剪切机构几何位置的解析法公式,计算出剪切机构初始位置.基于ADAMS动力学分析软件,建立飞剪剪切机构的机构杆件模型.仿真分析再现了飞剪的运动过程,得到剪切机构上、下剪刃的运动轨迹,速度变化曲线,剪刃开口度变化曲线和剪切过程中详细数据值.针对分析结果,利用ADAMS进行结构优化设计.优化结果改进了飞剪剪切过程中的速度超前和滞后问题,有利于剪切过程以及轧制工艺.基于ADAMS的分析方法与优化结果对IHI飞剪剪切机构的结构设计与改造具有实际运用价值.     

630吨冷剪机故障分析与处理

冷剪机是棒材生产线的关键设备,它的正常运行直接关系到轧钢生产。针对轧钢二轧棒材线冷剪机运行过程中出现的故障,从其结构形式和受力状态进行分析,找出了故障产生的原因和解决办法。     

旋转叶片在测试陶瓷浆料固化过程流变特性的应用

将旋转叶片应用于应力控制流变仪,测量陶瓷浆料固化过程中的流变特性.在数据处理上,可将添满陶瓷浆料的旋转叶片等效为一个同心圆筒,并按照同心圆筒进行测试参数的设置.我们采用四叶片的旋转叶片测试不同浓度的聚丙烯酰胺溶液的复数模量G*,并与平行板测试数据比较.结果表明旋转叶片存在有效直径.这个有效直径小于叶片直径.确定了在测试陶瓷浆料固化过程流变特性时的有效直径D_eff.并得到陶瓷浆料固化过程的流变曲线.     

Further observation of content uniformity of d-alpha-tocopheryl acetate as an oily drug in granules obtained by wet granulation with a high-shear mixer.

Using d-alpha-tocopheryl acetate (VE) as a model drug, we investigated the effects of the amount of binder solution on content uniformity of oily drugs in granules obtained by, wet granulation with a high-shear mixer. When the amount of binder solution was below the water volume for the plastic limit, the content of VE was less than 50% in the fractionated fine granules, but was more than 200% in the fractionated large granules. Large variations were seen in the contents of VE even if the granulation time was extended up to 30 min. This large variation was not decreased by the milling process. On the other hand, when the amount of binder solution was at or above the water volume for the plastic limit, less variation was observed in the content of VE throughout the granules, and the content of VE was fairly uniform. Nuclei rich in VE were formed when VE was adsorbed with the powder before granulation. When the amount of binder solution was below the water volume for the plastic limit, the shearing force of mixer blades to the granules was low, so that the nuclei rich in VE were not fragmented. This led to the nonuniformity of VE content throughout the granules. On the other hand, when amount of binder solution was at or above the water volume for the plastic limit, the shearing force of mixer blades against the granules increased and became sufficient to fragment the nuclei. This led to the uniformity of VE content throughout the granules. This study showed that content uniformity of VE in the granules can be achieved by controlling the physical shearing force of mixer blades by regulating the amount of binder solution.     

Further Observation of Content Uniformity of d-α-Tocopheryl Acetate as an Oily Drug in Granules Obtained by Wet Granulation with a High-Shear Mixer

Using d-α-tocopheryl acetate (VE) as a model drug, we investigated the effects of the amount of binder solution on content uniformity of oily drugs in granules obtained by wet granulation with a high-shear mixer. When the amount of binder solution was below the water volume for the plastic limit, the content of VE was less than 50% in the fractionated fine granules, but was more than 200% in the fractionated large granules. Large variations were seen in the contents of VE even if the granulation time was extended up to 30 min. This large variation was not decreased by the milling process. On the other hand, when the amount of binder solution was at or above the water volume for the plastic limit, less variation was observed in the content of VE throughout the granules, and the content of VE was fairly uniform. Nuclei rich in VE were formed when VE was adsorbed with the powder before granulation. When the amount of binder solution was below the water volume for the plastic limit, the shearing force of mixer blades to the granules was low, so that the nuclei rich in VE were not fragmented. This led to the nonuniformity of VE content throughout the granules. On the other hand, when amount of binder solution was at or above the water volume for the plastic limit, the shearing force of mixer blades against the granules increased and became sufficient to fragment the nuclei. This led to the uniformity of VE content throughout the granules. This study showed that content uniformity of VE in the granules can be achieved by controlling the physical shearing force of mixer blades by regulating the amount of binder solution.     

基于LuGre摩擦模型的叶片碰撞摩擦特性研究

建立了基于LuGre摩擦模型的叶片冠间碰撞摩擦模型,研究了叶片冠间接触碰撞和摩擦的动力学特性和减振机理。并研究了冠间间隙、动静摩擦系数对成组自带冠叶片碰撞摩擦减振效果的影响。通过分析摩擦过程中鬃毛的变形,对LuGre模型进行有条件的简化,研究了带冠叶片接触碰撞运动和摩擦运动的分岔特性。研究结果表明,LuGre摩擦模型可以更加完善的描述预滑动阶段叶片冠间的摩擦特性。     

Carbon Diffusion Between the Layers in Modern Pattern-Welded Damascus Blades

Pattern-welded Damascus steel blades are made by forge welding together pairs of steels having low- and high-carbon compositions. It is often assumed that these blades consist of hard and soft layers owing to the carbon variations of the original steels and that it is this difference in hardness that produces the etching characteristics that give the surface patterns. Theoretical arguments are presented that show that, with the modern forging techniques used to make these blades, carbon diffusion should be adequate to homogenize the C level between the layers of the blades, which predicts no hardness difference between layers. Experiments are presented on several modern blades, showing that there are no hardness differences found between layers. Arguments are presented for a theory that it is the difference in alloying elements between the layers that produces the differential etching characteristics that give rise to the visual surface patterns of most contemporary pattern-welded Damascus steels.     

Design of Compound Die for Production of Cutting Blades for Nonactive Rotary Paddy Weeder

Press working is a chip-less manufacturing process on sheet metal through the application of immense force with the help of press tools for short interval and hence results in shearing or deformation of the work material. It is a chip-less manufacturing process by which various components are made from sheet metal. A compound die is one that is used for cutting operations only, and the operation is completed by a single-press stroke. In this article, a die was designed to serve the purpose of cutting down the blades for paddy weeder and clearances to be provided in the die were calculated so as to reduce the material consumption with reduction in production cycle time. The die thus designed served for the purpose with 73% reduction in production time, with enhanced quality and helped in enabling mass production by eliminating several processes such as marking, cutting done with the help of a cutter, shaping, and so on.     

直九型直升机基准桨叶共锥度校准技术研究

研究了桨叶对激光斩波标定算法,采用高速的CPLD逻辑阵列、36位计数器和高速DSP嵌入式信号处理系统以及通过算法程序引入非线性误差补偿来校准基准桨叶的共锥度参数;建立了直九型基准桨叶共锥度参数校准装置标定系统,其机理为利用模拟桨叶切割激光束,通过光电器件探测这一周期性的光电信号,从而对激光器定位参数进行标定;通过这套系统实现了基准桨叶共锥度参数的校准和溯源。     

航空发动机自带冠叶片减振特性研究

摘 要：将自带冠叶片模化为质量弹簧模型。自带冠叶片减振主要是由于冠间碰撞和摩擦的组合运动来实现的,因此本文将冠间的接触简化为带对称间隙的弹簧阻尼模型,摩擦模型采用Sgn模型,从而建立该系统的动力学方程,进而采用Runge-Kutta数值方法求解系统的动力学方程。本文主要探讨了冠间间隙、刚度比、接触角度、摩擦系数等多种参数对减振效果的影响。结果表明：叶片的振动能量与冠间间隙、刚度比、接触角度、摩擦系数等参数有关,参数选取要考虑工作转速的范围。冠间的碰摩组合运动为硬式分段线性的非线性振动,因此本文同时采用Poincaré映射图和频谱图等方法对系统的非线性特性进行了一定的研究。
     

Improving reliability and lifetime of rejuvenated turbine blades

Abstract

A programme is reported of the rejuvenation of diffusion-coated turbine blades. These blades are usually assessed for consumption of creep life by a metallographic procedure on a sample basis after service and reassembled according to the results. This procedure can result in unsatisfactory reliability levels because of scatter. The objectives of this programme, therefore, are to improve the reliability of sets of reassembled turbine blades by increasing the minimum remaining creep strength, i.e. of blades in the initial stages of tertiary creep, and to eliminate heavily damaged blades with creep cracks concealed by the coating, as well as to improve the life of blades with an assessed remaining service life lower than the time between overhauls. Different rejuvenation treatments have been investigated and checked against the criteria essential for the service behaviour of the blades and the integrity of the material, microstructure, strength, and coating. All these factors were demonstrated to be satisfied by a suitable hot isostatic pressing treatment. The most important result is the evidence that blades with a creep–life consumption of more than 50% can be rejuvenated. Thus, the minimum creep life of used blades can be improved by more than 100%, as tested on a hot–gas rig.

MST/98     

Dislocation network formation during creep in Ni-base superalloy GTD-111

The Ni-base superalloy GTD-111 is used as a blading material in the first stage blades of high power gas turbines. The creep-rupture properties of the cast superalloy were studied over a wide range of temperatures and stresses. The observations of dislocation structures during steady-state creep confirmed that the creep mechanism was different in the high and low stress regions. The results showed that in the high stress region, shear mechanisms including stacking fault formation and anti-phase boundary creation were operative and in the low stress region, a by-passing mechanism occurred by either looping or dislocation climb and glide. With increasing exposure time in the high-temperature low-stress region, dislocations formed networks at γ–γ′ interfaces, as well as inside γ′ particles. The transition in the mode of dislocation–γ′ precipitate interaction from shearing to by-passing was found to depend on creep conditions (stress and temperature) and microstructural characteristic of the alloy. The present paper provides microstructural evidence by means of transmission electron microscopy for a high temperature by-passing mechanism operating in the superalloy GTD-111.