The process tests of 9T 34556 speed gear sleeve with different heat treatment methods, different heat treatment process parameters and different charging methods have been carried out Based on the analysis of different deformation conditions, the following conclusions are drawn:
(1) When other process parameters are the same, the deformation of parts by carbonitriding is smaller than that by carburizing. In our test, the average change of spline m value during carbonitriding of 9t 3456 speed gear sleeve parts is 44% of that during carburizing, and the average flatness is 72.7% of that during carburizing.
(2) With the same other process parameters and meeting the quenching performance requirements of parts, the cooling speed is small and the deformation of parts is small. The deformation of 9T 34556 speed gear sleeve parts during slow stirring cooling is smaller than that during fast stirring cooling. The average variation of spline m value during slow stirring is 59.7% of that during fast stirring, and the average flatness during slow stirring is 81.6% of that during fast stirring;
(3) When other process parameters are the same, different charging methods have a great impact on the deformation of parts. For 9T 3456 speed gear sleeve, the deformation of flat installation is smaller than that of hanging installation. The average change of spline m value during flat installation is 27.5% of that during hanging installation, and the average flatness is 93% of that during hanging installation.
(4) For gear sleeve thin-walled parts, the parts with carbonitriding, paperback and slow stirring cooling have the smallest deformation.