职业教育"1+X"证书制度与工程造价专业高度融合的新思路

文章在介绍1+X证书制度的概念和必要性的基础上,深入剖析了当前职业教育面临的难点和热点,从不同的侧面阐述了职业教育改革的紧迫性和重要性;针对工程造价专业如何在该制度下更好更快地转变教学思路,培养更多的复合型技能人才,提出了具有指导性的意见和建议,为相关专业的职业教育改革提供了新思路.     

等离子——熔化极气体保护焊设备及其应用

介绍了等离子-熔化极气体保护焊接的工艺过程,并与常规熔化极气体保护焊相比较分析了焊接过程的优缺点。对等离子-熔化极气体保护焊接的应用及焊枪的发展作了简要的描述。     

遥控焊接中立体视觉系统标定

为了提高遥控焊接智能化水平,设计了一套立体视觉系统进行焊接机器人环境的三维重建.对立体视觉系统参数标定分两步完成,首先使用基于平面模板的方法离线标定摄像机的内参数和两个CCD摄像机之间的位置关系等不变参数.然后使用线性方法对摄像机坐标系和焊接机器人工作坐标系之间的关系进行在线标定.标定试验重建结果的平均误差小于1 mm,最大误差小于3 mm.     

Numerical simulation of small section rectangular tube in parallel welding

The welding temperature field and deformation of parallel arrangement small-section rectangular tubes is calculated by using a non-contact model. After comparing the computed results with the experimentally measured results, it shows that there exist big errors when applying this model to the numerical simulation of small-section rectangular tube＇ s welding temperature field and deformation. Based on a simple analysis of the errors, a contact model is presented. The heat transfer and stress analysis between small-section rectangular tubes and clamping fixture are simulated by using direct constraints method, and then the laws of the temperature distribution, which coincide with experiment, are obtained. A further numerical analysis of the stress and deformation are made, it shows that a ＂T＂ shaped stress-field is formed in the vicinity of the weld. As the stress-field departs from the centroid of tubes＇, this leads to the small rectangular tubes not only have a longitudinal deflection, but also have a transverse bending and deformation.     

复杂薄壁空间曲线焊缝的变形控制

根据某产品空间曲线焊缝壁薄、密集、受热易变形,对管间隙及错边量要求高的特点,对其结构及其受力受热情况,及弧焊变形机理进行了深入地研究,并提出了抑制其变形的"分段线性控制"策略.依据焊缝间隙与焊接电流的对应关系,配合机器人虚拟ARC-ON/OFF信号与PLC电流分段线性控制信号,实现了连续焊接时电流的分段线性控制.结果表明,该控制策略行之有效,成功地应用于该焊件的实际生产,提高了产品的质量及生产效率.     

双钨极氩弧焊焊缝成形的数值模拟

采用数值模拟方法对双钨极氩弧焊的焊缝成形规律进行研究.考虑到两个电弧的相互吸引作用导致电弧偏转,仿真时采用倾斜热源模型.对比分析了单、双钨极氩弧焊的焊缝成形特点,研究了双钨极氩弧焊焊接过程中钨极间距、电流大小和匹配形式对熔池形状的影响.结果表明,相对于单钨极氩弧焊,双钨极氩弧焊的熔宽窄,熔深略小;随着钨极间距的增加,熔宽增加,熔深减小;随着电流的增大,熔深和熔宽都有一定程度的增加;两钨极上焊接电流的不同匹配形式会对焊缝成形产生影响.     

基于力觉遥示教曲线焊缝位置辨识方法

在遥控焊接环境中,时常碰到具有一定曲率的曲线焊缝,曲线焊缝精确辨识是保证遥示教精度前提条件之一.针对曲线焊缝的特点,提出了焊缝拐点和方向系数概念,并建立了曲线焊缝辨识方向系数智能控制模型,结合焊缝拐点识别算法,进行曲线焊缝辨识试验.结果表明,实现了曲线焊缝拐点自动识别,为遥示教曲线焊缝拐点识别提供了一种新方法.将力觉曲线焊缝辩识试验曲线上传给离线编程系统,由离线编程系统对焊缝拐点进行优化处理后,非常接近实际焊缝曲线,最大误差不超过±0.5mm,能够满足遥控焊接遥示教要求.     

Kalman filter of the force signal of identifying weld seam in remote teaching

For reasons of the vibration of robot, the rough surface of weld seam and electromagnetic disturbance of welding machine, the force signals of identifying weld seam become unstable. The position error of remote teaching point is too big to meet teaching requirements in remote welding. The force signals of identifying weld seam can be filtered by Kalman. The force signals of identifying weld seam of next teaching point is accurately predicted according to predicting algorithms, such as the equation of the state, the equation of the observation, the gain matrix of the filter and the covariance matrix of predicting state. The experimental results show that the precision of identifying weld seam is improved by Kalman filter.     

计算机控制管道焊接机器人屏蔽技术

在电弧强干扰下管道焊接机器人抗干扰设计成为管道焊接过程稳定性关键,其中管道焊接机器人屏蔽技术是主要影响因素之一。通过对管道焊接机器人电磁场屏蔽、屏蔽线、双绞线和屏蔽双绞线屏蔽原理分析,提出屏蔽完整性,面板孔、电连接器、电路板屏蔽和多层屏蔽等措施。提高屏蔽材料的屏蔽效能要考虑金属平板材料性质、电磁场源性质、电磁场源与金属平板的距离、屏蔽体接地等状况。以上研究成果可为管道焊接机器人制造提供理论和实践上参考依据。     

Modelling of the plasma-MIG welding temperature field

A three-dimensional simulation model for the plasma-MIG welding process, which takes the interaction between the plasma arc and MIG arc into account, is presented and the quasi-steady temperature fields on the workpiece are calculated with the model. The 10 mm-5A06 aluminum alloy is welded and the temperature fields are measured with the thermoelectric couple. The simulation results and measured results show that the biggest deviation of peak temperature between them is below 20 ℃, which indicates good coincidence between the simulation and measurement.