立式储罐倒装法横缝埋弧自动焊接新技术

埋弧自动焊适用于中厚板对接、角接、搭接等各种接头形式的平位置焊接,它是一种众所周知的常用焊接方法。具有焊缝成形美观、质量可靠、探伤合格率高、劳动强度低和生产效率高等优点,可对板厚8～18mm以下的接头实现不开坡口一次焊透成形,因此在焊接工程中得到广泛应用。 但是,埋弧自动焊用于其他位置时,由于熔池要用焊剂敷埋,焊接熔池温度高,铁水容易下垂等因素的限制,所以应用极少。     

全位置熔化极气体保护焊的电弧控制

随着压力容器、管道工程、海洋、舰船和原子能等技术的高速发展,要求采用全位置自动焊接的地方越来越多。采用TIC焊进行全位置焊接可以获得纯净优质的焊缝,但是生产效率太低。熔化极气体保护焊是一种生产效率高、成本低、容易实现自动化的焊接方法,近年来在压力容器、管道工程、舰船生产、机械制造和机车车辆等行业得到广泛的应用。但是,由于熔滴过渡和电弧的特殊性,要能满足全位置焊接的要求,必须对电弧进行控制。     

TIG焊熔池表面流动行为的研究

针对钨极惰性气体保护(Tungsten inert gas,TIG)焊熔池表面流动行为,在确定TIG焊熔池表面可采用粒子示踪的方法来进行其表面流动行为示踪的基础上,在以激光为试验背光光源,通过激光在TIG焊熔池表面镜面反射后,使得熔池及示踪粒子清晰成像于成像屏上。在此基础上,开展对304不锈钢和Q235普通碳钢的熔池表面流动行为的试验研究,对所获得这两种材料的TIG焊熔池试验数据进行处理与对比分析,探究熔池表面流动规律。研究结果表明:在TIG焊过程中,其焊接熔池存在两种运动模式,在304不锈钢焊接过程中熔池表面的液态金属由边缘向熔池中心流动;在Q235碳钢焊接过程中熔池表面的液态金属不定向、不规则地由熔池中心向熔池边缘流动,并测量304不锈钢TIG焊过程中熔池表面的液态金属流动速率为12 mm/s左右,Q235碳钢的熔池表面的流动速率为15 mm/s左右。     

铝合金MIG焊正面熔池图像视觉传感与处理

建立了铝合金脉冲MIG焊熔池图像检测CCD视觉传感系统。应用窄带滤光的方法成功地解决了强弧光干扰，通过大量试验，在获取清晰焊接熔池区图像的基础上，分析了铝合金焊接熔池图像的特征，研究了适合铝合金MIG焊熔池图像处理方法和熔池几何尺寸的边缘检出方法，获得了满意的熔池边缘特征图像，为进一步实现铝合金MIG焊接熔透智能控制奠定了基础。     

TIG焊熔池表面张力的测定及表面活性剂的影响

利用熔池振荡及熔池谐振信号的检测,以熔池自身固有振荡频率与熔池尺寸的内在关系测定熔池金属表面 张力,研究了薄板ＳＵＳ３０４不锈钢ＴＩＧ焊不同熔地尺寸的表面张力变化以及活性剂对熔池表面张力的影响。试验研 究方法为焊接熔池表面张力测定中的最初应用。     

大型钢制球罐的高效自动焊关键技术研究

就大型钢制球罐自动焊的关键技术进行了深入研究,采用CCD光电测控技术解决了球罐多层多道焊的实时跟踪难题,采用柔性磁轮式机构解决了焊车在球罐上无导轨全位置自由行走的难题,并试验研究了用CO2气体保护药芯焊丝焊(FCAW)进行球罐全位置多层多道焊的工艺技术。在此基础上,研制成了一种5自由度的全位置焊接机器人,能对球罐内外纵缝、横缝及仰缝进行无导轨全自动焊接,达到了高效率、高质量、无人实时操作和低劳动强度。     

奥氏体不锈钢管的现场焊接

采用药芯焊丝对奥氏体不锈钢管道进行打底焊接,MAG焊填充及盖面焊,立向上的水平固定全位置焊接.具有工艺性能良好、操作方便和焊接品质稳定等特点,在复杂的工艺管道施工及高空作业时其优点更为突出.     

活性剂焊接技术的研究

活性剂焊接是近十年来发展起来的增大焊接熔深，改善焊缝成形和焊接质量，提高焊接生产效率的新技术。早期主要集中在A—TIG焊，已在碳钢、不锈钢、高温合金、钛合金的焊接中有了成功的应用，对于铝镁合金的活性剂焊接技术也在研究中。目前研究认为活性剂提高熔深的机理一是活性剂可影响电弧特性，提高电弧的能量密度和作用于熔池的电弧力，二是活性剂影响了熔池的表面张力而提高了焊接熔深，或是2种原因兼而有之。随着A—TIG焊应用的成熟，活性剂焊接拓展到MIG焊、等离子弧焊和激光焊中的应用成为活性剂焊接发展的一个方向，在提高熔深，改善焊缝成形方面有了初步的效果。     

立向高速GMAW驼峰焊缝的试验研究

驼峰焊缝的产生严重制约了高速熔化极气体保护焊(Gas metal arc welding,GMAW)在立向焊接上的应用,目前对该技术难点研究甚少,尚无简单有效的抑制措施提出。因此,通过梳理水平高速GMAW驼峰焊缝的形成机理,以此为基础,运用自主研发的爬壁机器人焊接试验平台对立向高速GMAW驼峰焊缝进行试验研究。研究发现:立向上焊时,高速GMAW会产生驼峰焊缝缺陷,熔池中由电弧压力、熔滴冲击力和重力作用下产生的动量很大的后向液体流是形成驼峰焊缝的主要原因。此外,焊接电流和焊接速度显著影响驼峰焊缝的形貌。立向下焊时,因焊接方向和焊枪倾斜位置发生改变,使熔池中由电弧压力和熔滴冲击力作用下产生的后向液体流流向与自身重力方向相反,可有效抑制驼峰焊缝的形成。通过利用金属液体流自身重力来抑制立向高速GMAW焊接过程中驼峰焊缝的形成,大大提高了焊接速度和焊接电流,具有较高应用价值。     

埋弧自动焊在大口径钢卷管焊接上的应用

众所周知,埋弧焊是一种在焊剂层下进行大功率焊接的电弧熔焊方法,这种焊接方法具有生产效率高、焊接质量好、劳劝强度小、焊接变形小、生产成本低等优点。但由于埋弧的特点,一般只能进行平焊或近似平焊位置的焊接,因此使其应用范围受到一定限制。截止到目前为止,埋弧焊方法一般     

TP304不锈钢钢管环焊缝的A-TIG焊接研究

A-TIG焊接技术是基于TIG焊的焊接新工艺,具有大幅增加焊缝熔深、提高焊接生产率,降低成本等优点。本研究采用A-TIG焊接技术对TP304不锈钢50mm×6mm的管子进行全位置焊接,对得到的焊接接头进行射线探伤、显微组织分析以及力学性能测试,结果表明,接头的显微组织优于普通TIG焊接接头、接头质量和力学性能均达到标准要求。     

排布方式对铝合金激光-MIG复合横向焊接特性的影响

采用常规激光-熔化极惰性气体保护电弧(Metal inert gas,MIG)复合横向焊接铝合金过程中,焊缝表面极易出现咬边和下塌等缺陷,由此开展排布方式对激光-MIG电弧复合横向焊接铝合金焊接特性的影响研究。分析二者的排布方式对熔池特征、熔滴过渡形式以及焊缝成形规律的影响。试验结果表明,异面引导复合焊接方式对焊缝成形有明显改善作用,焊缝表面熔宽减少、中心线偏移和咬边缺陷得到有效抑制。采用同面引导复合方式时,熔滴过渡到匙孔后方,熔池下侧熔融金属大量堆积并产生周期性的波动,导致焊缝结晶组织出现了分层现象;而采用异面引导复合方式时,熔滴过渡到匙孔下方,并且熔滴在熔池中的落点位置与同面引导方式相比要偏上,熔滴过渡频率稍低,此时熔池中熔融金属分布较为均匀,熔池下部堆积金属较少,有效抑制了焊缝的下塌和咬边缺陷。     

Welding deviation detection algorithm based on extremum of molten pool image contour

The welding deviation detection is the basis of robotic tracking welding, but the on-line real-time measurement of welding deviation is still not well solved by the existing methods. There is plenty of information in the gas metal arc welding(GMAW) molten pool images that is very important for the control of welding seam tracking. The physical meaning for the curvature extremum of molten pool contour is revealed by researching the molten pool images, that is, the deviation information points of welding wire center and the molten tip center are the maxima and the local maxima of the contour curvature, and the horizontal welding deviation is the position difference of these two extremum points. A new method of weld deviation detection is presented, including the process of preprocessing molten pool images, extracting and segmenting the contours, obtaining the contour extremum points, and calculating the welding deviation, etc. Extracting the contours is the premise, segmenting the contour lines is the foundation, and obtaining the contour extremum points is the key. The contour images can be extracted with the method of discrete dyadic wavelet transform, which is divided into two sub contours including welding wire and molten tip separately. The curvature value of each point of the two sub contour lines is calculated based on the approximate curvature formula of multi-points for plane curve, and the two points of the curvature extremum are the characteristics needed for the welding deviation calculation. The results of the tests and analyses show that the maximum error of the obtained on-line welding deviation is 2 pixels(0.16 mm), and the algorithm is stable enough to meet the requirements of the pipeline in real-time control at a speed of less than 500 mm/min. The method can be applied to the on-line automatic welding deviation detection.     

Nd:YAG激光+脉冲MAG电弧复合热源焊接参数对焊缝熔深的影响

试验研究Nd:YAG激光 脉冲MAG电弧复合热源焊接过程中焊接参数对焊缝熔深的影响.研究结果表明,复合热源焊缝熔深随电弧功率和激光功率的增大而增大,随焊接速度的增大而减小,并且在相同参数下,复合热源焊缝熔深稍大于激光焊缝熔深而显著大于脉冲MAG焊缝熔深.对于不同焊接电流,光丝间距在0～3 mm内复合热源焊缝取得最大熔深,且取得最大熔深的光丝间距与焊接电流大小有关;复合热源焊缝熔深在离焦量为2 mm时取得最大值.试验结果分析表明,在激光 电弧复合热源焊接过程中激光功率不仅决定复合热源焊缝熔深,而且可以极大地提高焊接速度:MAG电弧也可提高Nd:YAG激光焊的热效率.     

Obtaining weld pool vision information during aluminium alloy TIG welding

An image sensing system for the TIG (tungsten inert-gas arc) welding process of aluminium alloy was established. The relationships between the image sensing system and the characteristic of welding current were discussed in detail. Front and back images of the weld pool were obtained with different welding parameters. In order to process the image, the characteristics of an aluminium alloy were analysed. Image processing and pattern recognition were first used to obtain information from the TIG welding process for aluminium alloy. The image of the weld pool was pre-processed using a series of methods: a weighted median filter, a statistical threshold by expectation and the projection method. A neural network method was used to extract the edge of the images of the weld pool. The result of detecting the edge with a BP neural network were excellent. The symmetry of the weld pool for aluminium alloy was studied when the welding current is large. The edge of the image of the whole weld pool is obtained in a single side image and an accurate method for measuring the weld pool geometry parameter is provided. Experiments show that using the image sensing to control the TIG weld width for aluminium alloy is an effective method.     

DETECTION AND ANALYSIS OF WELD POOL SHAPE FOR CO2 SHORT CIRCUITING ARC WELDING

0 INTRODUCTIONIt is well known that skilled welding operatorscan estimate and control beam quality by mainlyobServing the weld POOl. This means the POOl im8gecontains abundant inforTnation during weldprocess. So that, sensing information from POOl imeqedirectly is becoming a new method to control the weldquality.Following the advances in computer vision andM camera tecbnoogy, more and more researchesusing weld opl image for sensing welding processeshave been carried out, usually in T…     

焊缝位姿及焊枪位姿的模型

针对机器人弧焊条件下的特殊要求,建立了焊缝位姿和焊枪位姿模型,以坐标系的形式定量描述焊缝及焊枪的位置和方向,确定了能够准确且严格地描述焊缝的焊接位置和焊枪姿态的参数：焊缝倾角、焊缝转角及焊枪工作角和行走角,并给出了计算方法。上述参数不但计算简便,而且可以直接代表焊接位置和焊枪姿态对焊接质量的影响因素。模型对于焊接工艺的建模与仿真以及机器人焊接的建模与离线编程具有非常重要的意义。     

Light intensity analysis of a passive visual sensing system in GTAW

In manual welding, an experienced welder acquires 80% of the welding process information by vision. Visual sensing has the advantage of supplying abundant information without contact with the workpiece or welding circuit. Visual sensors have been widely used in the field of welding. According to optical imaging principles, the object imaging process depends on the shape, size, position, and angle of the light source; the shape of the object; the reflectance characteristic of the object’s surface; and the position, angle, and inner parameters of the camera. In order better to utilize the image information of a visual sensor and to ascertain the weld shape and size, arc light intensity is calculated from the arc length and the welding current. The visual sensing system is analyzed from the point of the view of light intensity. The function of adjusting the system to the light intensity is formulated in this paper. A relationship between the gray image, arc length, and welding current can be obtained. Welding experiments were implemented. Thus, we can recover the shape and height of the weld pool by SFS (shape from shading) algorithms from the weld pool image.     

Seam Tracking Technology for Hyperbaric Underwater Welding

Automatic weld seam tracking technology to be used in hyperbaric underwater damaged pipeline repair welding is much more important, because of poor bevel preparation and severe working condition. A weld seam tracking system based on digital signal processing(DSP) passive light weld image processing technology has been established. A convenient charge coupled device(CCD) camera system was used in the high pressure environment with the help of an aperture and focus altering mechanism to guarantee overall image visibility in the scope of pressure below 0.7 MPa. The system can be used in the hyperbaric environment to pick up the real welding image of both the welding arc and the welding pool. The newly developed DSP technology was adopted to achieve the goal of system real time characteristics. An effective weld groove edge recognition technique including narrow interesting window opening, middle value wave filtering, Sobel operator weld edge detecting and edge searching in a defined narrow area was proposed to remove the guide error and system accuracy was ensured. The results of tracking simulation and real tracking application with arc striking have proved the validity and the accuracy of the mentioned system and the image processing method.     

Visual sensing and penetration control in aluminum alloy pulsed GTA welding

In this paper, visual sensing and penetration control in aluminum (Al) alloy pulse gas tungsten arc welding were researched. Firstly, a three-optical-route visual sensor was designed. The sensor can capture the weld pool from three directions at the same time. After analyzing the influences of different factors on weld pool image, serials of clear and stable weld pool images were obtained. Then, image processing technologies were developed to compute back topside weld pool geometry parameters. Wavelet transform and Canny operator were synthesized to get all edges in the weld pool image. After noise removal and calibration, the breaking edges of weld pool were obtained, and then piecewise curve fitting based on polynomial function were used to recover the whole weld pool edge. Lastly, proportional–integral–differential and a multiplex controller were designed to control penetration in welding process. Experiments proved that visual-based penetration control can insure welding quality well from weld pool width and reinforcement.