某型智能柴油机凸轮轴热处理工艺的开发

某型智能柴油机凸轮轴长径比大,热处理技术要求高,生产难度大。为了解决该难点,利用多用炉、真空回火炉、井式渗碳炉、深冷箱、井式回火炉、校直机等设备从技术难点分析、试验摸索等方面进行了研究,认为该凸轮轴通过清洗→防渗→烘干→预热→循环渗碳→高温回火→校直→真空去应力→机加工→淬火→深冷处理→回火等工艺流程,可以生产出硬度高、显微组织好、力学性能高、热处理畸变可控的产品。需要指出的是,多用炉高低碳势多次循环渗碳比传统二段渗碳优势明显,如渗碳速度快、碳化物形态好、硬度高、硬度梯度平缓、渗碳时间短、生产效率高等。采用上述热处理工艺方案,最终加工的样件完全满足用户要求。

Development of heat treatment process of camshaft for a type of intelligent diesel engine

Heat treatment of a camshaft with a large ratio of length and diameter for a type of intelligent diesel engine is difficult to produce, and need special technology to deal with. In order to find a solution for this, a series of equipment including multi-purpose furnace, vacuum tempering furnace, pit type carburizing furnace, cryogenic box, pit type furnace, straightening machines and other equipment was used on the base of key technics analysis. The production practice indicates that the camshaft with a high hardness, good microstructure and high mechanical properties, and less distortion can be produced by the processes of cleaning, stop-off coating and drying, preheating, carburizing and high temperature tempering and alignment, stress relieving in vacuum, machining, hardening, cryogenic treatment, and tempering. It is pointed out that multiple cycle carburizing with high and low carbon potential in turn in multi-purpose furnace has more obvious advantages than the traditional two stages carburizing, such as higher carburizing speed, better carbide morphology, higher hardness, flatter hardness gradient, shorter carburizing time, and higher production efficiency. The heat treatment process scheme of this part is adopted, and the final processed specimens fully meet the requirements of users.