S32205双相钢管与管板胀接工艺参数确定

主要研究了S32205双相不锈钢管与管板胀接工艺,选取液袋液压胀接的方式进行胀接试验,并对胀管率、拉脱力等进行试验计算来验证胀接工艺的可行性,从而确定了最佳胀管压力.     

双相不锈钢管子与管板胀接工艺研究

主要研究双相不锈钢管子与管板胀接工艺,选取液压胀管的方法进行胀接试验,并对胀前和胀后的管子分别进行尺寸检验、点腐蚀试验、金相观察、硬度测量等试验来验证胀接工艺的可行性,从而确定了最佳的胀管压力。     

核级热交换器液压胀接工艺评定研究

研究了压水堆核电站中某热交换器换热管与管板的胀接工艺,采用液袋式超高压液压胀管机进行胀管试验,胀管后通过对试验件的外观和尺寸检查、接头的密封性试验以及机械强度试验,从而确定最佳的胀接工艺参数,满足RCC-M规范中对胀管工艺评定的相关要求。     

机械加工工艺对螺纹套管胀接结构拉脱力的影响分析

核燃料组件组装过程中,常采用薄壁零件胀接的方法进行装配。基于三种不同的机械加工工艺对螺纹套管进行加工,并对不同机械加工工艺得到的螺纹套管进行胀接。通过胀接试样拉伸试验,确认不同机械加工工艺对螺纹套管胀接结构拉脱力的影响。     

一种小直径管子的深度胀接工艺

介绍了一种小口径管子（φ8mm×1mm）的深度胀接结构、胀接技术要求、胀接工艺难点。提出了一种能够完成这种小口径管的胀接工艺。通过工艺试验、检测结果及生产应用情况，验证了其可行性。     

双管板换热器内管板液压胀接压力的探讨

由于双管板换热器结构的特殊性,内管板的胀接是一个难点,胀接压力的大小直接关系到双管板换热器的可靠性,因此选取合适的胀接压力是关键。运用ANSYS软件对双管板换热器的内管板进行液压胀接模拟,并采用优化设计方法,对胀接压力进行了优化,获得了最佳的液压胀接压力,并通过试验验证了模拟的合理性,为双管板换热器内管板胀接工艺提供参考。     

胀紧度对管子与管板胀接强度影响的试验研究

采用按三角形排列的7管孔试件，进行了胀紧程度对换热器液压胀接和机械胀接接头连接强度影响的试验研究。分别以胀接压力，管子内径增大率表征液压胀接和机械胀接的胀接程度，考虑了管板开槽数目的影响，给出了胀接程度和开槽尺寸及数目选取的参考数据。     

铜管与翅片气压胀接工艺研究

研究换热器中的铜管与翅片在气体介质均匀压力作用下的胀接工艺过程。首先根据理论公式计算出胀接时的最小胀接压力Pimin和最佳胀管压力Pisy,从而确定出合适的气压范围,选择几组气压值进行管板胀接工艺过程数值仿真。通过试验的方法,对数值模拟结果进行验证。研究结果表明,在计算得到的压力范围内,数值模拟结果与试验结果较为接近,同时铜管与翅片发生了过盈配合且胀紧度随着压力值增大而增大。     

核级Incoloy 800合金传热管胀接残余应力试验研究

Incoloy 800合金具有良好的耐腐蚀性能,被用作核电站蒸汽发生器传热管。试验分析了机械胀接工艺对φ22 mm×1. 3 mm核级Incoloy 800合金传热管残余应力的影响,结果表明,管子胀接区域残余应力最大,过渡区域次之,未胀接区域最小;胀接和过渡区域轴向残余应力大于环向残余应力;残余应力随管子胀接变形量的增加而增大。该研究可为蒸汽发生器胀接工艺优化以及胀接接头的可靠性分析提供参考。     

双管板换热器的制造要点

根据双管板换热器的特殊结构,介绍了用模拟管板进行胀接工艺评定的方法以及管板加工、强度胀接、管板组装、压力试验等方面的制造要点,确定了影响双管板强度胀接致密性的关键因素在于管板管孔、胀槽的同心度和槽的粗糙度以及合适的胀接参数。     

基于MATLAB的伺服机械压力机传动机构运动学/动力学仿真研究

以增力较大的肘杆机构为对象,分析了普通直线连杆-等长肘杆和三角连杆-不等长肘杆两种机构的工作特性,建立了它们的动力学和运动学模型。以4000kN伺服压力机为例,采用MATLAB仿真软件对伺服机械压力机传动机构进行了运动学-动力学仿真分析。分析结果表明,三角连杆-不等长肘杆与直线连杆-等长肘杆相比具有更好的动力学和运动学特性:在同等公称压力条件下,三角连杆-不等长肘杆的输入扭矩较直线连杆-等长肘杆的输入扭矩小70.6%,而公称压力行程内前者的平均速度约为后者平均速度的50%。     

Effect of cooling flow on thermal performance of a gas foil bearing floating on a hot rotor

This paper presents the measurements of the thermal behavior of a gas foil bearing (GFB) floating on a hot rotor in a tangential air injection cooling scheme. The cooling air was tangentially injected against rotor spinning into the inlet mixing zone of the test GFB. The hollow rotor was heated by a cartridge heater. The GFB temperatures were measured at intervals of 30 deg along the circumference of the axial center except for at 45 deg, where the cooling flow is injected. The rotor temperatures were measured near the GFB side ends using an infrared thermometer, which was calibrated with a thermocouple. Load cells measure the static load and bearing torque. The baseline rotor temperature was measured without GFB over the axial length at rotor speeds up to 15 krpm and for increasing heater temperatures up to 400 °C. The results showed relatively uniform rotor temperatures at the test journal GFB section, and severe heat convections on the rotor surfaces. The GFB and rotor temperatures were measured under a static load of 80 N for increasing heater temperatures of 100 °C, 200 °C, 300 °C and 400 °C and with increasing cooling flow rates of 100 liter/min, 150 liter/min, and 200 liter/min. The circumferential GFB temperatures showed the maximum temperatures at the loaded zone and the minimum temperatures in the unloaded zone. The increasing cooling flow effectively reduced both the rotor and GFB temperatures, showing a dramatic decrease with the smallest amount of cooling flow. GFB friction torque was measured for two test cases for the static load of 80 N at a rotor speed of 10 krpm: 1) A lift-off and touch-down operating cycle for increasing heater temperatures without the cooling flow, and 2) a continuous operation for the heater temperature of 400 °C with increasing cooling flows. In test case 1, the GFB friction torque decreased for higher heater temperatures due to a larger thermal expansion of the bearing housing than the rotor’s. In test case 2, the GFB friction torque decreased with increasing cooling flows due to strong cooling effects on the rotor temperature. The results imply that the tangential air injection increased the GFB clearance by directly cooling the rotor and effectively alleviating the rotor expansion; hence, the scheme is capable of an effective cooling for high temperature GFB applications, such as micro gas turbines.     

Plugging criteria for thinned high-pressure feedwater heater tubes considering pressure and thermal loading

When heat exchanger tubes have critical thinning which could cause unsafe conditions, it is general practice to plug the tubes so that they are out of service to prevent rupture failure at the thinnest location. Plugging criteria for the high-pressure feedwater heater tubes of fossil power plant were studied. Tubes in the desuperheating zone were considered due to their high internal pressure and the high temperature difference across the tube wall. Theoretical analysis of uniform thinning and eccentric thinning of the tube was conducted to determine the stress conditions at the thinnest location under internal/external pressure and thermal gradient across the tube. The minimum required tube thickness was determined using the maximum shear stress criterion (Tresca theory). Accuracy and effectiveness of the analytic solutions of the stresses were verified by comparing the results obtained with those obtained from finite element analysis. Using finite element analysis, the stresses for eccentric thinning were determined. Thermal loading due to temperature difference across the wall was considered even though the contribution of pressure loading to the stress of the tube was known to be higher than that of the thermal loading. As case studies, the tube plugging criteria of three high pressure feedwater heaters were determined using actual temperature and design pressure industry data. The procedure used in this study can be applied to different pressure and temperature operating conditions, and different tube materials.     

低温环境下材料膨胀系数和润滑对望远镜负载扭矩的影响

为了深入研究望远镜的负载扭矩随着温度降低而增大的机理,提高低温下伺服系统的跟踪精度。首先分析了轴承摩擦扭矩的各种影响因素和低温对负载扭矩的影响,研究了润滑剂黏度随温度的变化规律,试验对比了有无添加润滑脂情况下负载扭矩的变化,结果表明在低温下无润滑脂时负载扭矩的波动减少并且线性度提高。其次分析了轴承摩擦扭矩和间隙的关系,采用电阻应变片法测量不同材料在不同温度下的热膨胀系数,建立起材料膨胀系数和扭矩的相关特性,结果表明低温下负载扭矩是常温下的6.67倍,而材料尺寸的最大缩短量达到960με。通过对低温负载扭矩机理的研究,可为低温环境下望远镜的精确控制提供理论和试验数据。     

内补液增压式THF性能测试装置开发及试验研究

材料性能对液压胀形工艺(THF)及产品质量有重大影响,传统单向拉伸试验所得材料性能不能很好反映管材液压胀形性能。开发了一种简单实用可在单动压力机上使用的试验装置,可用于不同材料及尺寸管材的液压胀形试验,以确定管材胀形性能。该装置不需要复杂的外部供液系统,而是利用其内部的补液腔自动、同步地建立起胀形所需液压力及轴向载荷,两载荷比值可通过合理设计补液腔直径得到。可以实现管材自然胀形、轴向压缩胀形、两端不同约束下的胀形和一定程度的比例加载胀形。一系列胀形对比试验表明：管端约束方式对自然胀形有较大影响,而对轴向压缩胀形影响较小;液压力、轴向载荷及其比值对轴向压缩胀形有较大影响。     

Thermal influence on torque transfer of wet clutches in limited slip differential applications

Wet clutches operating under low velocity and high load are studied with the aim of obtaining reliable models for the torque transfer during boundary lubrication conditions. A friction model which takes temperature, speed and nominal pressure into account is developed and used with temperature calculations to be able to simulate behavior of a wet clutch working in boundary lubrication regime. Predicted torque and temperatures from the model agree well with experimental data.     

高速精密压力机理想驱动转矩研究

建立了高速精密压力机理想驱动转矩的表达式,并对其进行了简化。以研发中的多连杆式高速精密压力机为例,计算了其理想驱动转矩,并与曲柄滑块式的高建精密压力机高速精密压力机进行了比较分析。结果表明:理想驱动转矩不仅与公称力有关,还与驱动形式、曲柄转速、等效运动质量有关;惯性力所引起的转矩在一定速度下可超过公称力所必需的转矩;该多连杆式高速精密压力机不适宜于过高的冲压速度。研究结果有助于高速精密压力机主传动型式的选择及上模质量的确定。     

基于径压胀形确定管材的摩擦因数

摩擦对管材液压成形有极大的影响,管材摩擦因数的确定是一项极其重要的工作。在分析比较现有测试方法的基础上,基于径压胀形原理及其变形规律提出确定管材液压成形胀形区摩擦因数的新模型。该模型以恒定内压力下圆形管材径压胀形成方形断面后,以断面对角线长度差作为确定摩擦因数的测量指标。对比对角线长度差的有限元数值模拟结果及实测结果,以此确定管材液压成形时胀形区的摩擦因数。对低碳钢及不锈钢管的有限元数值模拟分析表明：对角线长度差与摩擦因数及内压力均成指数关系,该长度差对摩擦力很敏感且可方便测量,也可作为针对管材液压成形胀形区润滑剂特性的评定指标。所提出的新模型具有简单、实用等优点。     

扬矿球铰接头的螺纹滑脱及脂密封性能分析

借鉴国内外深海采矿扬矿管接头,结合其作业环境设计了一种球铰接头,使扬矿系统不受弯矩和扭矩,相当于柔性管。采用能量损失法分析了螺纹脂密封性能,并用有限元法分析了螺纹的滑脱失效。分析结果表明,在中试系统矿浆流速下,深海采矿扬矿系统球铰接头部分螺纹机加工产生的自然通道螺纹脂有良好的密封性能。减小扬矿管系统承受的拉力,增大螺纹间的摩擦和螺纹间啮合齿数,可减小扬矿管接头滑脱的可能性,从而提高系统作业的可行性和安全性。     

The effect of tube dimensions on optimized pressure and force loading paths in tube hydroforming process

The precise control of internal pressure and axial force loading paths significantly affects the final product quality. In this study, the effect of tube dimensions on the pressure and force loading paths in tube hydroforming process is investigated by using simulated annealing optimization method linked to a commercial finite element code. The optimized loading paths, obtained for different tube geometries with a constant expansion ratio, are then compared. The effects of initial diameter and wall thickness on shape conformation, optimal internal pressure and axial force (or feed) are discussed on the basis of optimal loading paths. Several guidelines in prediction and determination of tube hydroforming parameters are obtained by optimization analysis.