全焊接球阀焊接工艺的标准研究

本文主要介绍了天然气长输管线、城市输气管线等系统用全焊接管线球阀阀体焊缝要求、焊接接头设计原则,影响焊缝质量的主要因素,焊缝埋弧自动焊焊接工艺以及焊接工艺评定流程,焊缝焊后免热处理安全评估等。     

扁平绕带式压力容器的设计、制造和检验(二)

<正> 四、有关的设计参数选择 1.焊缝系数 焊接接头的焊接变形、几何缺陷和焊缝成形不良等因素都会导致焊接接头区应力水平的提高。焊接接头区存在着组织和性能的不均匀性,会使焊缝中出现气孔、夹渣、裂纹等缺陷。焊缝是容器较薄弱的部位,许多事故的发生都起源于焊缝。因此容器设计时常采用焊缝系数,以补偿焊接时可能产生的强度削弱。焊缝系数的大小,既与钢种、壁     

浅谈学习GB150—89《钢制压力容器》（第十章）之体会（下）

四、焊接焊接是压力容器制造非常重妥的工作。焊接质量决定了容器的质量。因此,本标准对焊接部份提出的内容和要求比原JD741更全面。 1.A,B类焊缝余高焊缝余高对压力容器多道焊焊接的焊缝是不可避免的,而且还有上面焊道对下面焊道起保温和缓冷作用,并对消除最后一层强度焊缝应力和改善组织有好处。但焊缝余高     

不同焊接方法对汽车镀锌钢板焊接的影响

介绍了手工电弧焊(SMAW)、机器人气体保护焊和机器人激光焊等三种焊接方法对汽车镀锌板焊接质量的影响。归纳发现：手工电弧焊的焊接效率低,焊缝热影响区宽,焊缝附近锌层烧损严重,且焊接飞溅多,焊缝抗腐蚀性差。机器人MAG焊的焊接效率高,但焊缝接头变形大,电流密度大,焊丝易焊穿工件;机器人MIG电弧钎焊的焊接热输入低,但是焊接接头强度低。机器人激光焊的焊缝及热影响区的综合性能最好,焊缝附近锌层的蒸发最少,更易实现机械化和自动化。因此,机器人激光焊接在汽车薄板及精密器件的制造领域具有更加广泛的应用前景。     

塑件焊接故障的产生原因及排除方法

塑件焊接故障的排查 焊件沿焊缝长度方向焊接边缘距离不等故障分析及排除方法：（1）焊接边缘未按工艺要求加工。应在焊接前，按图纸尺寸加工好焊接边缘。（2）焊件装配不正确。在装配时，应沿焊缝长度方向，使焊缝间隙相等。     

SAF2205双相不锈钢设备SAW焊接工艺

指出双相不锈钢设备焊接的关键是平衡焊缝金属中的α/γ比以及焊缝、HAZ的低温冲击韧性,分析SAW焊接工艺各因素对α/γ比以及焊缝、HAZ低温冲击韧性的影响,从而确定焊接工艺,并经焊接工艺评定试验,各项指标达到设计图样要求。     

高压容器焊接残余应力的有限元分析

运用有限元软件ANSYS分析了高压容器筒体和球形封头连接处焊接区温度场和残余应力的分布规律.结果表明,焊接过程中焊接区温度分布不均匀,焊缝及熔合区温度最高,焊缝周围区域金属的温度急速下降.焊接区残余应力关于焊缝中心呈对称分布,最大残余应力出现在焊缝及熔合区处,最大残余应力约为1750 MPa,残余应力沿焊缝中心向边缘处...     

基于管壳式换热器换热管与管板焊接工艺研究

换热管与管板焊接是换热器设备制造关键工序,焊缝质量直接影响到产品使用寿命.本次试验研究,通过不同的焊接方法组合,从焊接方法、焊接位置、焊接参数等方面进行组合试验,从中选出第一层采用垂直固定自动焊且自熔的焊接工艺,第二层采用水平固定自动焊增加填充焊丝的焊接工艺,试验结果标明,该种焊接方法,焊缝根部熔合良好,缺陷较少,焊缝...     

浅析高压蒸汽管道的焊接工艺及TOFD检测技术

针对高压蒸汽管焊缝多次裂纹泄漏事件,分析焊接裂纹形成的原因。探讨高压蒸汽管焊缝接头的焊接工艺及热处理、坡口的型式对焊接质量的影响及焊接要点。结果表明:高压蒸汽管焊缝裂纹泄漏主要是管系设计不合理、膨胀量过大,焊缝处应力过大引起蠕变孔洞,加上焊接及热处理不规范、检测手段不先进,没及时检查处理缺陷造成的。裂纹高压蒸汽管在规范焊接后,以TOFD检测方法为主、其他方法为辅,可以有效检测焊缝缺陷,消除安全隐患。检验合格的高压蒸汽管道使用时间由10d延长至8个月。     

热空气老化对橡胶地板布焊接接头性能的影响

研究热空气老化（70 ℃×14 d）对焊接参数不同的Ⅰ和Ⅱ组橡胶地板布焊接接头性能的影响以及进行焊接接头焊缝的差示扫描量热（DSC）和拉曼光谱分析。热空气老化试验得出,Ⅰ组橡胶地板布焊接接头的拉伸试样从焊缝处熔断,Ⅱ组橡胶地板布焊接接头的拉伸强度减小12%;DSC分析得出,Ⅰ组橡胶地板布焊接接头焊缝在65.6 ℃时热流率发生转变,在67.2 ℃时存在明显吸热峰,即焊缝发生粘流态转变,Ⅱ组橡胶地板布焊接接头焊缝和Ⅰ组橡胶地板布焊接接头母材在25～110 ℃中均未见明显吸热峰;拉曼光谱分析得出,Ⅰ组橡胶地板布焊接接头焊缝在1 056 cm-1和1 118 cm^-1处的特征峰强度明显减小。这是热空气老化过程中橡胶分子链发生交联与裂解反应导致的。     

Ultrasonic and impulse welding of polylactic acid films

The weldability of polylactic acid (PLA) is examined in this article. Biaxially oriented PLA films of various thicknesses were joined with impulse and ultrasonic welding techniques. Relatively high weld strengths were achieved with impulse welding over a wide range of welding parameters. Ultrasonic welding produced high weld strengths with relatively short cycle times. In detail, ultrasonic welded samples had a weld factor (weld strength/base material strength) of 1 at cycle times of 0.25 sec. The weld factor was significantly lower at shorter weld times and weld times above 0.35 sec. In contrast, 100‐μm thick samples joined by impulse welding for 2–3 sec had a weld factor of 1 and a standard deviation of only ±5%. The peak temperature during the impulse welding was measured to determine the fusion temperatures of the films. Mechanical, thermal, and optical analysis was used to examine the properties of the PLA at various welding and annealing conditions. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

聚丙烯塑料板搅拌摩擦焊接头缺陷分析

搅拌摩擦焊具有高效、节能、无污染等优点,既能焊接铝合金等低熔点材料,也能焊接聚丙烯塑料板材。各种工艺参数合理匹配时,焊缝美观,质量良好。但是,工艺参数选择不当时,焊缝会存在明显缺陷。本文分析了用搅拌摩擦焊焊接聚丙烯塑料板时所出现的飞边、孔洞等缺陷。     

15MnNbR钢制2000m3球罐的焊接

将CHEJ507RH焊条与PP.J557RH焊条进行对比分析后,认为CHEJ507RH焊条完全能够满足15MnNbR球罐的焊接设计要求,并通过焊接裂纹试验和焊接工艺评定,确定了合理的焊接工艺参数。在长庆石化公司4台2 000m3球罐的实际焊接中,证明CHEJ507RH焊条有效、可靠。     

Hot pin welding of thin poly(vinyl chloride) sheet

This paper develops a method of welding two thin sheets of poly(vinyl chloride) (PVC) with a heated pin, thus allowing construction of a relationship between the weld temperature and weld strength. Constructing a relationship between weld strength and temperature is necessary for modeling many welding processes, including laser transmission welding. An experimental approach to establishing this relationship is required because of the complex melting behavior of PVC. The designed experimental device uses a single heated pin to weld samples by using varying pressure and temperature for one second dwell time. An electro‐mechanical loadframe pulled the welded samples until joint failure occurred, thereby allowing determination of the weld strength. An experiment varying welding pin temperature and joining pressure found the temperature to be a highly significant determiner of weld strength, while the pressure was found to be not significant. A transient numerical heat transfer model was used to calculate the weld interface temperature for each pin temperature. The relationship established in this paper can be used to predict the weld strength from the temperature output from models of alternative welding methods. J. VINYL ADDIT. TECHNOL., 13:110–115, 2007. © 2007 Society of Plastics Engineers.     

换热器管子和管板焊接接头浅见

通过对管板换热器设计参数、介质特性、使用环境以及承载情况的分析研究,比较不同焊缝接头形式以及焊接工艺过程的选择对最终焊接质量的影响,同时阐述了合理的焊缝检验工艺对于确保在焊接前、焊接过程中以及焊接完成之后保证焊接质量的重要意义,总结出管板换热器管子和管板焊接接头在制造过程中的关键控制点。     

Thickness effects in the vibration welding of polycarbonate

In vibration welding of thermoplastics, frictional work done by vibrating two parts under pressure, along their common interface, is used to generate heat to effect a weld. Past work on welding characterized the effects of weld parameters such as the weld frequency, the weld pressure, and the weld time, on the welding process and weld strength, and showed that the most important parameter affecting weld strength Is the weld penetration—the decrease in the distance between the parts being welded that is caused by lateral outflow of material in the molten film. However, those weld studies were based on specimens of constant nominal thickness (6.35 mm, 0.25 in). This paper is concerned with the effects of specimen thickness on the weld process and weld strength.     

塑化度与焊接条件对PVC-U型材焊角强度的影响

通过正交试验对比PVC—U型材塑化度和焊接条件对焊角强度的影响试验得知：焊接温度、加热时间及型材塑化度对焊角强度的影响较大,焊接时间与进给压力对焊角强度影响相对较小。型材塑化度在70％左右时具有较好的可焊性,适当提高焊接温度及延长加热时间有利于提高型材的焊角强度,焊接时间超过一定时间后则对焊角强度影响不大,根据型材截面不同进给压力有一最佳值。     

Structure and mechanical properties of optimized extrusion welds

A knowledge of how welding parameters affect the mechanical properties of welds is important. However, the mechanical properties of welds cannot be characterized by nondestructive testing methods. Because of its sensitivity to process conditions, extrusion welding of polypropylene-homopolymer (PP-H) was used to investigate the effects of welding parameters on the resulting mechanical properties of welds. Overall optimization of the welding process to obtain stable conditions during welding, which required a redesign of the welding shoe and the welding geometry, resulted in improved weld properties through better build-up of critical weld areas and suppression of void formation. Investigation of material heating characteristics led to a new air nozzle design. The effect of air temperature and welding velocity on the temperature and thickness of the molten layer was determined. The effects of individual process parameters on the structure and mechanical behavior of welds were established, thereby making it possible to specify narrow limits on the values of the weld parameters for producing high-quality welds. The quality of these joints cannot be determined by short-time tests because, even with severe testing conditions, cracks occur in the bulk material. Polarized optical microscopy was used to correlate crack behavior with the build-up of a specific multilayer structure in the weld area. Long-term tests demonstrated that, in both the time-to-crack and crack behavior, the joining area is not the weakest link in an extrusion weld when the welding parameters are chosen correctly.     

Ultrasonic welding of thermoplastics in the near-field

Ultrasonic welding is one of the most popular techniques for joining thermoplastics because it is fast, economical, and easily automated. In near-field ultrasonic welding, the distance between the horn and the joint interface is 6 mm or less. This study investigated the near-field ultrasonic welding of amorphous (acrylonitrile-butadiene-styrene and polystyrene) and semicrystalline (polyethylene and polypropylene) polymers. High frequency ultrasonic wave propagation and attenuation measurements were made in order to estimate the dynamic mechanical moduli of the polymers. The estimated moduli were entered into a lumped parameter model in order to predict heating rates and energy dissipation. Experimental results showed that variations in the welding pressure had little effect on energy dissipation or joint strength; Increasing the amplitude of vibration increased the energy dissipation and the weld strength. For the semicrystalline polymers, increasing the weld time improved strength up to weld times greater than 1.5 s, where strength leveled off. For the amorphous polymers, the weld strength increased with Increasing weld time up to times of 0.8 s; for longer weld times, the power required was too high, causing overloading of the welder. Monitoring of the energy dissipation and static displacement or collapse provided valuable information on weld quality.     

全自动氩弧焊技术在 OC反应器蛇管制作上的应用

通过对全自动氩弧焊设备及工艺参数的选择方法的介绍,说明全自动氩弧焊技术是提高焊接质量和效率的最佳方法之一。