一前言随着港口机械的发展，门吊减速箱大型齿轮的需求量日益增多，原来采用大锻件制的齿轮往往成本昂贵、生产周期冗长。而采用焊接件制的齿轮具有节约原材料、降低生产成本、缩短生产周期、机件结构轻化等优点，正在为国内外企业所采用，并迅速发展。对于大型焊接齿轮，由于 I. INTRODUCTION With the development of port machinery, there is an increasing demand for large-size gears of door-hanging gear boxes. The gears originally made of large forgings are often expensive and have a long production cycle. The use of welding system gear with raw materials, reduce production costs, shorten the production cycle, the mechanical structure of the advantages of light, is being used by domestic and foreign enterprises, and rapid development. For large welding gears, due