小模数齿轮激光熔覆修复工艺试验研究

【作者】 鲍志军；

【导师】 宋光明；

【作者基本信息】 上海海事大学 ， 机械设计及理论， 2007， 硕士

【摘要】 本文研究了激光熔覆技术在小模数斜齿轮修复中的应用。小模数齿轮激光熔覆易产生齿面干涉、齿面裂纹、齿顶塌陷等现象。试验结果表明,合理选择光斑尺寸、扫描位置、扫描方法、工艺参数和熔覆顺序有助于获得平整光滑、齿面无裂纹、齿槽无凹陷、齿顶无塌陷的熔覆层。针对齿面熔覆时易出现裂纹的问题,设计了几种不同的熔覆方案,进行了几种不同方案的熔覆试验,最后确定了齿面熔覆的合理的工艺方法和工艺参数。齿面熔覆时对激光束与齿面的相对位置要求较高,否则易造成干涉,试验中通过合理的位置设计及选择适当的光斑大小解决了此问题。针对齿顶熔覆时易发生塌陷的问题,试验了多种不同的方案。提出了采用激光预置粉末的方法,即通过使用较低的激光能量密度预先扫描,使小部分粉末能熔化或呈微熔状态,依靠这部分粉末使大量的粉末粘结成团附着在齿顶表面,然后进行正式的激光熔覆,试验发现此工艺能解决齿顶塌陷问题。在进行整个轮齿及完整齿轮的熔覆中,面临的主要问题是热量的积累及热量的分布不均匀。在连续扫描过程中,热量的积累会造成后续熔覆时熔池保存时间长,从而造成熔体的流动,即材料的转移;热量分布的不均匀,会造成整个齿轮发生不均匀的变形。通过采用合理的扫描顺序及分齿方法等解决了遇到的热量积累及热量分布问题。更多还原

【Abstract】 It has been researched that laser cladding is appied to the repairing of a close-toothed helical gear in this paper. Laser cladding for a close-toothed gear often meets such problems as the interference between the laser beam and the adjacent tooth flank, the crackings produced on the tooth flank coating,the caved tooth slot and the collapsed tooth tip. The experimental study shows that the smooth, non-cracking,non-caving,non-collapsing coating on the gear tooth can be obtained by the intelligent selection of the beam size, the beam positioning,the scanning technique,the technological parameters and the cladding procedure.For the cracking problem on the tooth flank coating, various coating methods are designed and experienced. Finally reseanable process method and parameter are confirmed. When cladding the tooth flank, the relative position between the laser spot and tooth flank is demanded severely, otherwise it is easy that the interference occurs, in the experiment the problem above is resolved through designing the rational relative position and selecting the appropriate spot size.For collapsing problem on the tooth tip coating, various experiment methods have been carried on. The method of depositing the powder in advance through the laser is proposed, that is, scanning in advance through the lower energy density laser enables the small partial powder to melt or to melt slightly, so that relying on the partial melting a large amounts of powder are felt and joined together into a mass attaching to the surface of tooth tip, then the formal cladding is carried on. Experiment indicates that the collapsing problem can be solved by the process above.During cladding the whole tooth and entire gear, the main problems faced with are the accumulation of heat and the uneven distribution of heat. In continuous scanning process, the thermal accumulation will cause the cladding pool preserve long time during the subsequent scanning, thereby causing the melt flowing, that is, the material is transferred. Uneven distribution of the heat will cause the entire gear uneven deformation. Through utilizing the reasonable scanning sequence and interval number of tooth, the problems of the thermal accumulation and distribution are solved.更多还原