ALGORITHM AND IMPLEMENTATION OF AUTO-SEARCHING WELD LINE FOR WELDING MOBILE ROBOT

为焊接活动机器人的寻找汽车的焊接线的一个算法被介绍。寻找汽车的焊接线是机器人罐头自动地在焊接前根据焊接沟的特征认出一条焊接沟，然后以准备的需要的地位调整自己姿势因为也就是，焊接它是机器人独立地自己排列到焊接缝接的中心的一个过程。第一，与寻找汽车的焊接线的功能焊接活动机器人的配置被介绍，然后，算法和实现寻找 ofauto 焊接线根据机器人的 kinematics 模型被介绍，最后，轨道在寻找汽车的焊接线之中计划详细被调查。发达焊接活动机器人成功地装的实验结果 hows 在焊接前实现 auto-searchingweld 线的任务，追踪错误精确能被控制到近似± 1 .5 公里，并且满足实际焊接的要求工程。

Numerical simulation method for weld line development in micro injection molding process

In order to reduce the "trial-mold" risk and cost,numerical simulation method was applied to micro injection molding weld line development investigation. The micro tensile specimen which has the size of 0.1 mm(depth) ×0.4 mm(width) ×12 mm(length) in test area was selected as the objective part,and polypropylene(PP) as the experimental material. Respectively with specific commercial software(Mold Flow) and general computational fluid dynamic(CFD) software(Comsol Multiphysics) ,the simulation experiments for development of weld line in micro injection molding process were executed and the real comparison experiments were also carried out. The results show that during micro injection molding process,the specific commercial software for normal injection molding process is not valid to describe the micro flow process,the shape of flow front in micro cavity flowing which is important in weld line developing study and the contact angle due to surface tension are not able to be simulated. In order to improve the simulation results for micro weld line development,the general CFD software,which is more flexible in user defining function,is applied. The results show better effects in describing micro fluid flow behavior. As a conclusion,as for weld line forming process,the numerical simulation method can give a characteristic analysis results for processing parameters optimizing in micro injection molding process;but for both kinds of softwares quantitative analysis cannot be obtained unless the boundary condition and micro fluid mathematic model are improved in the future.

Study on intelligent welding mobile robot with the function of auto-searching weld line

The development of welding robots suitable for specially unstructured working enviroments has been become an important development direction of industrial robot application because large-scale welding structures have been used more and more widely in modern industry. In this paper,an intelligent mobile robot for welding of ship deck with the function of auto-searching weld line was presented. A wheeled motion mechanism and a cross adjustment slider are used for the welding robot body. A sensing system based on laser-PSD(position sensitive detector) displacement sensor was developed to obtain two dimensional deviation signals during seam tracking. A full-digital control system based on DSP and CPLD has also been realized to implement complex and high-performance control algorithms. Furthermore,the system has still the function of auto-searching weld line according to the characteristics information of weld groove and adjusting posture itself to the desired status preparing for welding. The experiment of auto-searching welding line shows that the robot has high tracing accuracy,and can satisfy the requirement of practical welding project.

Numerical Study on Welding Line Behavior of Deep Drawing TWB Process

The FEM technology is used to analyze the welding line movement behavior of deep drawing TWB sheet with different thickness. It is found that high stress fields are concentrated around the welding line and large residual stresses are left. The effect of the welding line movement is like a rigid string and the selected nodes of the thin part near the welding line show the related larger strain.

Study on general inverse kinematics of rotating/tilting positioner for robotic arc welding off-line programming

Off line programming provides an essential link between CAD and CAM, whose development will result in greater use of robotic arc welding. An arc welding system with a robot and a rotating/tilting positioner is one of the most typical workcells. The inverse kinematics of robot and positioner is the foundation of the off line programming system. The previous researchers only focused on a special solution of the positioner inverse kinematics, which is the solution at down hand welding position. In this paper, we introduce a method for representing welding position. Then a general algorithm of rotating/tilting positioner inverse kinematics is presented, and an approach to find the unique solution of the inverse kinematics is discussed. The simulation experiment results show that the general algorithm can improve the ability of robotic arc welding off line programming system to program all types of welding positions.

Mechanism of weld-line movement within hydroforming of tailor-welded tube

To reveal the reason of weld-line movement in hydroforming of a tailor-welded tube (TWT) with dissimilar thickness,the stress ratio of axial stress to circumferential stress is derived by mechanical analysis and analyzed between the thicker and thinner tubes,as well as the property of the axial strain. During TWT hydroforming,tensile strain along axial direction happens on the thinner tube. On the contrary,compressive strain happens on the thicker tube. Experiments are conducted to varify the weld-line movement regularity and strain distribution. It indicates that the weld-line moves from the thinner part to the thicker during TWT hydroforming. The thinning ratio of the thinner tube is bigger than that of the thicker tube,especially in the zone near weldline. Stress ratio difference between the thicker tube and the thinner tube is the main reason of weld-line movement and non-uniform thinning ratio distribution.

Off-line simulation of robot welding of radar pedestal

A study of the interference simulation based on robot welding of the radar pedestal was carried out by using the KUKA Sim Pro simulation software and off-line program technology. Compared with the actual robot welding process, it was found that the trajectory of the simulated robot welding process in line with that recorded in the actual welding process, and the actual limit and interference appeared at the same place as the simulation process. There was no interference phenomenon on the outside weld-seam; on the internal weld-seam, especially on the weld-joint of support plate connected to the cylinder, a phenomenon of interference appeared. It was helpful to use the simulation method to guide the actual robot welding so as to protect robot from impacting and reduce the weld defects.

Study of fractal character of the fusion line in dissimilar welded joint

The fractal dimension of the fusion line in different dissimilar welded joints is measured with Box Dimension Method.The non scale region of the fusion line with fractal character is calculated. The fusion line in the dissimilar welded joint is proved to be a fractal structure. The change and influence factors of the fractal dimension of the fusion line are studied.

Generalized CAPP and synthetic evaluation strategy for production line of accuracy welding

This paper presents generalized CAPP(G-CAPP) method which deals with macro process planning for multi-objective in the planning stage of production line of accuracy welding (PLAW) based on the features of accuracy welding production (AWP). G-CAPP offers foundations for prototype design and general equipment sorting, production capacity predication and production analysis by means of simulation and optimization. A synthetic hierarchy evaluation (SHE) model for G-CAPP established according to the planning objective is utilized to estimate the alternate processing plans by using membership function and analytic hierarchy process (AHP) of operational theory. The assembly welding line of hydraulic torque converter (HTC) is as an example of typical AWP to explicate G-CAPP and synthetic evaluating strategy of PLAW. The feasible and rational process configuration strategies of HTC assembly welding line are pointed out under different planning objective.

On-line measurement of electrical variables of the transducer during ultrasonic welding and cutting

A measurement system for high power electrical variables with ultrasonic frequency was established. It can measure the effective values of the voltage and the current, the active power, the phase difference of voltage and current, the frequency of the transducer during ultrasonic welding and cutting. In sampling circuits of the system, the measured current is sensed by using a no capacitance and no inductance precision resistor and is treated with a difference amplifier, the measured voltage is processed by using a proportional amplifier. For achieving good amplitude frequency characteristics and rapid measurement of high frequency signals, the resistors, capacitors and amplifiers used in the system are rationally selected. Calibrating experiments show that relative errors are less than 1% for voltage and current effective values and less than 2.5% for active power, and absolute errors are ±1 Hz for frequency and ±1.7° for phase difference of voltage and current in the range of 17～23 kHz .

Path Planning of Planar Kinked Line Seam by Visual Servoing for Robotic Welding

Welding path planning can substitute for the manual teaching process of the robot and can promote the autonomous level of the robotic welding. A path planning method by visual servoing was presented, in which the optimal angle of charge-coupled device (CCD) camera was also planned. Aiming at planning two forms of kinked line seams, obtuse angle seam and right angle seam, a practicable solution was put forward. In this solution, the intersection of two adjacent straight segments is detected in each local seam image, and if intersection is found, the seam errors are calculated using the next straight segment. The experimental results show that kinked line seam can be well planned using this solution.

Welding technique and quality of large diameter X70 line pipe for gas transmission of China

X70 grade large diameter line pipe with helical and longitudinal seam SAW was developed and used in West-East Pipeline Project of Petrochina. The operation pressure of the pipeline was designed as 10 MPa, with diameter of 1016 mm OD. This project represents the first high-pressure, large diameter and high strength grade gas pipeline in China. All the factors affecting the safety of the pipeline shall be considered. The welds quality of line pipe is very important for safety of the pipeline. Acicular ferrite type X70 grade pipeline steel was adopted for the base material. The welds performances of X70 line pipes with 1016mm OD and 14.6-21.0 mm WT has reached a very high level, especially of low temperature Charpy V impact toughness of welds metal. Welding technique and quality status of X70 line pipe of China are investigated in this paper.

Development of the High Toughness Spirally Submerged Arc Welded Pipe Line

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Automatic girth welding and performance evaluation of the joints of hot-induction-bend and line pipes with different wall thickness

During the process of laying long-distance oil and gas transmission pipelines,the hot-induction-bend method is extensively used when the direction has to be changed.By considering the pipeline's ongoing processing and loading states during service,the pipeline that is generally used exhibits thicker walls than those that are observed in the line pipe.As such,during pipeline construction,hot-induction-bend and line pipes with different wall thickness are girth-welded.The chemical composition of hot-induction-bend and line pipes differs,with the carbon content being particularly higher in the hot-induction-bend pipe;it also depicts a higher carbon equivalent,which makes it possible to modify the girth of the pipe.In this study,using Baosteel's standard X70 MUOE hotinductionbend and line pipes,solid-wire automatic gas-metal-arc girth welding was performed and the performance of the girth-welded joint was evaluated.Furthermore,the weldability of the pipeline girth and the microstructure of the girth-welded joint were analyzed.The results reveal that Baosteel's standard UOE hot-induction-bend and line pipes exhibit good girth weldability,and their technical quality can be guaranteed in case of consumer fieldconstruction applications.

基于响应曲面的卡盖双浇口工艺参数优化与模具设计

车用电源卡盖结构复杂与多加强筋的结构特征,在其注塑成型过程可能会阻碍了材料的流动诱发熔接线、翘曲变形等问题,影响产品的表面质量和结构强度。因此,本文将理论算法与有限元仿真相结合开展卡盖制品注塑成型工艺优化与模具设计研究。研究结果如下:首先,根据产品特征确定了点浇口及位置,进而结合Moldflow开展单浇口和双浇口的对比分析并确定了双浇口;其次,以熔接线长度为优化目标,建立响应曲面法实验方案并开展仿真分析;然后,利用最小二乘法、方差分析、回归分析等,确定了以熔接线为优化目标的最优工艺组合,即塑料制品的熔体温度(A)为260℃、模具温度(B)为65℃、注射时间(C)为1.5 s、保压压力(D)70 MPa及保压时间(E)10 s,此时的熔接线最大长度约为5.8 mm,相比于初始分析方案的31.5 mm降低了81.6%;最后,采用UG进行了卡盖的注塑模具设计并进行生产验证,产品填充完整且表面质量良好,为生产提供指导意义。

含氢环境中X80管线钢焊接接头氢脆敏感性研究

为了探究管线钢焊接接头在氢气环境下断裂力学性能的变化,采用缺口拉伸原位充氢方法对X80钢母材、焊缝和热影响区进行12 MPa总压,0.36 MPa氢分压下的氢脆敏感性研究,采用高压慢应变速率拉伸试验机进行缺口拉伸测试,采用高压断裂韧性试验机和高压腐蚀疲劳试验机对X80钢分别进行断裂韧性试验和疲劳裂纹扩展速率试验。结合断裂韧性试验和疲劳裂纹扩展速率试验对X80钢的裂纹扩展行为进行研究。结果表明:在相同条件下,相比母材和热影响区,焊缝位置的断面收缩率明显下降,表现出较高的氢脆敏感性;与常温常压空气中的原始数据相比,在0.36 MPa氢分压环境中焊缝位置的裂纹尖端张开位移(CTOD)值变化较小,断裂表面未出现二次裂纹;与在空气环境中相比,X80钢焊缝在0.36 MPa氢分压环境中的疲劳裂纹扩展速率增加了1个数量级,说明氢气能够增大材料的疲劳裂纹扩展速率,但根据实际管道压力波动情况,在0.36 MPa氢分压条件下X80钢的氢脆敏感性较小。

基于SYSWELD的预热温度对焊接热输入影响的有限元模拟

采用数值模拟方法在有限元软件SYSWELD中建立了焊接三维有限元模型,利用非线性材料热物性参数和双椭球移动热源作为热传递方程的边界条件,得到了在不同预热温度条件下能熔透母材的最低焊接线能量。采用材料为API X65钢进行实验验证,表明模拟结果和实验结果基本吻合,为预热条件下采用合适的焊接工艺提供了科学的指导依据。

火电厂锅炉水冷壁焊缝泄漏失效分析

某12Cr1MoV水冷壁对接焊缝中部出现周向裂纹导致泄漏失效,为调查泄漏失效原因,对焊缝进行了宏观检查、磁粉检测、硬度检验、金相分析、全元素分析和能谱分析,并建立模型分四个阶段讨论了水冷壁焊缝泄漏失效的原因。研究表明:焊缝中夹杂的S元素是焊缝泄漏失效的主要因素,收缩拉应力为偏析在晶界的低熔点共晶物提供了形成沿晶热裂纹的条件,氧气的介入造成热裂纹的局部氧化,实际运行的综合应力使氧化的沿晶热裂纹多点扩展、融合,形成宏观裂纹,最终导致焊缝泄漏失效。