It can be seen from the cross-section of the straight shaft that the cutting speed of the straight shaft tends to be faster than that of the neutral shaft, and the straight gear decreases first; When the thickness of material removal reaches 20mm, the decline speed of neutral shaft starts to slow down. At this time, the decline speed of neutral shaft of spur gear blank becomes slower and slower until the processing is completed; When the spur gear split wheel blank processing is completed, the position of the neutral shaft decreases to the lowest. In the whole processing process, the position of the neutral shaft of the spur gear blank decreases from the initial 40mm to 37.35mm.
In the process of gear cutting, different additional stresses will be generated when each layer of material is removed from the tooth groove. It is the superposition of the additional stress and the initial residual stress in the spur gear blank material that leads to the bending deformation of the spur gear blank. Therefore, in order to calculate the deformation of spur gear blank in the machining process, the change law of additional stress must be clear, and the influence of the change of neutral axis on the bending deformation of spur gear blank must be considered.
The bending additional stress and its distribution of the gear cutting part during the processing of spur gear blank are shown in the figure. Referring to the calculation formula of deformation curvature in material mechanics, the curvature relationship of spur gear blank before and after gear cutting can be deduced:
When the spur gear blank is processed to m layer, the deflection of the spur gear blank after gear cutting is:
Where, l is the length of the split spur gear blank.