锅炉管子计算——第二讲 空间弯管的空间夹角计算

第一节已知二投影角的空间弯头实际弯曲角度计算锅炉上的管子弯曲形状是十分复杂的,除了平面弯管外,还有不少空间弯管。在作图时,空间弯曲管子至少要用二个主要投影来表示其几何形状。为了适应锅炉布置上的要求,也时常采用空间弯头,如部分下降管、汽水管道等。空间弯曲管子的所有弯头可能都是空间弯头,也可能其中少数是空间弯头。管子上几只弯头中只要有一只弯头是空间的,则这根管子就不能在平面上完全放平。但是,以某一只弯头来看,它总是在某一平面上。如图2-1所示,弯头是由两条直边BE 和CD 及一段圆弧(?)     

关于柔性芯棒在弯管工艺中的应用

１前言 在柴油机制造过程中牵涉到很多管子的 加工，如水管，油管，气管等。其中多数为硬 管（金属管），它们主要的加工难点是：在弯曲 时外侧拉裂，内侧起皱等。按国产普通管子 的要求，弯曲半径：管子直径＞６；１才能保证加工性能，但柴油机的外围空间有限，按厂标Ｑ／ＳＣ３７５规定这个比例要达到 ２：１。为此，制造厂采用了各种各样的工艺方法，如灌黄沙，把空心管子变成实。乙管子，但是费工费时，且工作现场脏乱差。较高档的如飞机制造厂利用低熔点合成金属，熔点８０℃左右，完工后，开水～烫就可以把填料倒出来，但此方法成本较…     

过热器管束胀管的有限元分析

通过利用ANSYS软件对胀管工艺过程、运行工况的具体数值分析，指出了选用何种管子材料和管板材料相匹配能较好地解决胀接和密封性问题。     

排管及管子计算程序开发

在高加设计中，需要确定筒体内部排管的数量、位置，以及管子的重量、有效面积等，由于管子的数量较多，人工计算比较复杂而且易出错，因此开发并利用软件来进行计算，速度快且准确，为高加排管及管子计算、管子订货提供了重要参考。     

180MW空冷汽轮发电机转子风扇座强度及低周疲劳分析

采用ANSYS软件有限元分析方法计算180MW空冷汽轮发电机转子风扇座的应力，并应用Neuber方法计算转子风扇座的低周疲劳寿命。采用ANSYS计算汽轮发电机转子风扇座的应力，克服了经典计算方法对复杂变化曲面应力计算的局限性，是较理想地模拟转子风扇座实际运行工况的计算方法。     

环缝焊接装置

本专利是关于管系是一种管子对接环缝焊接装置,尤其对蛇形管管子对接(如过热器)环缝更为适宜。近年来要求蒸汽发生器的管束增加表面面积,以致在这些管束中将管子布置得相互靠得很紧近,并将管子弯曲成蛇形,以达到在有限的空间尽可能地增加表面面积。制造这样管束的唯一方法是将管子对接接长,再加以弯曲成管束样式。但由于管子的长度关系势必需要很大的工作场地,才能容纳来回     

鉴别临危管子预防锅炉爆管

该文计算分析了锅炉受热面管子热应力松弛，内壁氧化膜生长及管子壁厚损失的进展过程及它们在管子破坏中的作用，并把分析结果用到高参数锅炉管子寿命计算中，得到了合理的结果。     

锅炉管子计算 第三讲 弯管斜势计算

第一节弯管斜势计算的第一种基本方法什么叫做弯管斜势锅炉管子进行弯管时,弯管机的转盘是在水平面上回转的,管子的弯头平面总是和水平面重合。但空间弯曲管子的弯头平面是不在同一平面上的,相连的两个弯头平面间有一个夹角,也就是两弯头平面的两面角,如图3-1所示,∠θ为两面角。对于相连的两个空间弯头,若将第一个弯头平面     

波纹补偿器在蒸汽供热管道设计中应用

在城市蒸汽供热管道补偿设计中最为经济的应该是自然补偿。自然补偿是利用弯曲管段中管子的挠曲来补偿热位移，显然自然补偿的能力是有限的。当自然补偿不能满足要求时，通常选用补偿器来达到吸收热位移目的。常用补偿器有方型补偿器、套筒补偿器、球型补偿器和波纹补偿器。     

EGR冷却器散热面积计算研究

通过冷却器散热面积计算公式,利用某发动机性能参数,计算出发动机废气再循环装置(EGR)冷却器散热面积,利用数值模拟软件ANSYS对发动机冷却器散热效果进行模拟计算,然后对结果进行分析,从而为某发动机EGR冷却器的设计和计算提供理论依据。     

Effect of reinforcement on plastic limit loads of branch junctions

This paper provides effects of reinforcement shape and area on plastic limit loads of branch junctions under internal pressure and in-plane/out-of-plane bending, via detailed three-dimensional finite element limit analysis assuming elastic-perfectly plastic material behaviour. It is found that reinforcement is most effective when (in-plane/out-of-plane) bending is applied to the branch pipe. When bending is applied to the run pipe, reinforcement is less effective when bending is applied to the branch pipe. The reinforcement effect is the least effective for internal pressure.     

Limit moment of local wall thinning in pipe under bending

In engineering practice, pipe containing local wall thinning may be subjected to bending load. The existence of local wall thinning on pipe surface impairs the load-carrying capacity of pipe. In order to maintain the integrity of the pipe containing local wall thinning, it is very important to develop a method to evaluate such a pipe with local wall thinning under bending. In this paper, the limit moment of local wall thinning pipe under pure bending is computed employing 3D elastic–plastic finite element analysis. The results show that the limit moment of pipe is affected not only by the width of defect but also by the longitudinal length of defect. When the longitudinal length of defect overpasses some critical value, the results from net-section collapse criterion (NSC) are in very reasonable agreement with the results from finite element analysis. Therefore, the NSC formula can conservatively be used to assess the limit load-carrying capability of local wall thinning pipe under bending.     

The interaction of pressure and bending on a dented pipe

Results are presented from an FE numerical study of the capacity of a dented pipe to withstand combined pressure and moment loading. The denting process was modelled with internal pressure applied at the design level. The pipe support was modelled by a saddle-type arrangement. The strength of the dented pipe was first assessed under pure bending, applied in such a way that the dent was either on the tension side or the compression side. The strength of the dented pipe was then assessed under internal pressure loading. Finally, the behaviour of the dented pipe under combined bending and pressure loading was assessed and interaction diagrams prepared.     

某大型数控系统弯管机的参数研究与实际应用

计管机数字控制管子弯管自动线的研制成功,是综合国内外先进技术、经验的基础上完成的。该设备具有结构简单、可靠、可弯管子的形状复杂、造价低廉等特点。在国内大、中、小锅炉厂得到了广泛的应用。     

Limit loads for pipe bends under combined pressure and in-plane bending based on finite element limit analysis

Approximate plastic limit load solutions for pipe bends under combined internal pressure and bending are obtained from detailed three-dimensional (3-D) FE limit analyses based on elastic-perfectly plastic materials with the small geometry change option. The FE results show that existing limit load solutions for pipe bends are lower bounds but can be very different from the present FE results in some cases, particularly for bending. Accordingly closed-form approximations are proposed for pipe bends under combined pressure and in-plane bending based on the FE results.     

Limit loads for piping branch junctions under internal pressure and in-plane bending—Extended solutions

The authors have previously proposed plastic limit load solutions for thin-walled branch junctions under internal pressure and in-plane bending, based on finite element (FE) limit loads resulting from three-dimensional (3-D) FE limit analyses using elastic–perfectly plastic materials [Kim YJ, Lee KH, Park CY. Limit loads for thin-walled piping branch junctions under internal pressure and in-plane bending. Int J Press Vessels Piping 2006;83:645–53]. The solutions are valid for ratios of the branch-to-run pipe radius and thickness from 0.4 to 1.0, and for the mean radius-to-thickness ratio of the run pipe from 10.0 to 20.0. Moreover, the solutions considered the case of in-plane bending only on the branch pipe. This paper extends the previous solutions in two aspects. Firstly, plastic limit load solutions are given also for in-plane bending on the run pipe. Secondly, the validity of the proposed solutions is extended to ratios of the branch-to-run pipe radius and thickness from 0.0 to 1.0, and the mean radius-to-thickness ratio of the run pipe from 5.0 to 20.0. Comparisons with FE results show good agreement.     

Buckling analysis of flanged curvilinear pipes in pure bending

The geometrically nonlinear problem of pure bending of a thin-walled elastic curvilinear pipe terminated by totally rigid flanges is studied by the finite-element method. The stiffening effect of the flanges is modeled by imposing special boundary conditions on the end cross sections. The buckling behavior is studied and the values of the critical bending moment are obtained for a wide range of geometrical parameters of the pipe.     

金属管件的弯曲工艺和弯管模结构形式

对管子的弯曲方式、应力分布及方案选用进行了比较、确定。     

锅炉蛇形管自动弯管生产线的介绍

锅炉通过向外输送具有一定热能的蒸汽和高温水实现功效。而蛇形管具有吸收热量的作用，能够提高锅炉的做功能力，并一臣节约能源。，锅炉厂蛇形管自动化生产对于锅炉工业的发展具有非常大的促进作用，因此结合实例，介绍蛇形管自动弯管生产线的特点及各项流程，并且与外国现今的锅炉蛇形管自动弯管生产线进行比较。     

Cross-sectional flattening of pipes subjected to bending

Pipes subjected to bending may fail by cross-sectional flattening due to a plastic hinge mechanism occurring at the mid-section. In this paper the relationship between the applied bending moment and the stresses and strains at the neutral axis is calculated, using a power law stress-strain relationship. As a tentative failure criterion, a critical local bending radius of the pipe wall was selected. It can be expected that failure by the flattening mechanism occurs in the medium range of wall thickness to pipe radius ratio. For smaller ratios buckling on the compressive side—and, for larger ratios, fracture on the tensile side—of the pipe is shown to be the failure mechanism.