Deformation Behaviors of Laser Forming of Ring Sheet Metals

Laser forming is a highly flexible sheet metal forming technique. In laser forming along curved irradiation paths, the heated zone is bigger and the effects of the processing parameters on the deformation are complex. The deformation behaviors of laser forming of ring sheet metals have been investigated from the thermal-mechanics analysis by the finite element (FE) simulation based on the proposed finite element method model. The effects of ring central angle and scanning path on deformation of ring sheet metal were investigated. The results are as follows: (1) in comparison with the laser bending along linear path, the marked third point has two peak temperatures during the laser forming process along curved path; (2) the forming process fluctutes continuously and the sheet edge is warped because the rigid-ends effect due to the restriction of sheet; (3) when the ring central angle increases, the displacement difference of the marked three points decreases and then increases, and the warped curvature of sheet edge decreases; (4) when the laser beam diameter increases, the displacement difference of the marked three points decreases and the warped curvature increases.     

国际焊接工程师实践教学中微视频的应用

分析了传统国际焊接工程师实训教学的现状,受学生考研和找工作的影响以及实践场地空间的影响,学生参加实训的积极性不高,出勤率较低,培训效果不理想,通过率较低。为改变目前的状况,将短小精悍、内容新颖、形式多样的实践教学微视频引入实践教学过程中,进而提高实践教学效果。结果表明,实践教学新模式改变了传统的国际焊接工程师实践教学模式,培养了学生的安全意识,提高了学生参加实践教学的积极性和出勤率,实践教学效果和一次性通过率都有了较大的提高。     

复合钎料的研究进展

以复合钎料进行钎焊,对于异种材料的钎焊,特别是陶瓷和金属的钎焊是一种很有潜力的方法。在传统钎料中加入一定比例的各种形态的高温合金、碳纤维和陶瓷颗粒作为增强相所制成的复合钎料,具有合适的热膨胀系数,可有效降低因母材热膨胀系数不同而导致的钎焊接头处的残余应力,同时可提高钎焊接头的综合性能。按照传统复合材料的分类方式,从增强相尺寸的角度将复合钎料分为微米级增强复合钎料和纳米级增强复合钎料,分析复合钎料的特点及研究现状。通过分析不同尺寸增强相复合钎料对钎焊接头组织和力学性能的影响可知:与微米级增强复合钎料相比,纳米级增强复合钎料具有更加均匀且良好的组织结构,并能获得更高的接头强度。目前,有关纳米级增强复合钎料钎焊的增强机理尚未得到充分的研究,将成为今后研究工作的重点。