Characteristics of the part and processing difficulties.
The number of gear teeth is 400, the modulus is 0.5mm, and the gear accuracy grade is 6. This part length-diameter ratio of up to 1:67, belong to the thin-walled parts, it has the following characteristics.
(1) the part wall thickness is not enough, poor rigidity, under the action of clamping force or cutting force, the part thickness is not enough to resist the action of clamping force, very easy to produce deformation, can not reach the dimensional accuracy, form accuracy, gear accuracy requirements.
(2) the mass of the part is heavy, the outer diameter is large and thin, there are a variety of mitigation grooves on both sides, positioning, support, force points are small, positioning clamping difficulties.
(3) under the action of cutting force, especially axial force, it is easy to produce vibration and deformation, affecting the dimensional accuracy of the part, form accuracy, gear accuracy and surface roughness.
Process measures and precautions
Analysis of the design drawings of the disc-shaped gear parts, the rough machining to the finished parts, the material removal rate of 60% or more, a larger material removal rate, if not well handled residual stress relief problems, easy to cause the parts during and after processing deformation, so as not to meet the design requirements.
In order to reduce the impact of part deformation on machining accuracy, the process is divided into roughing → aging → finishing → machining. Roughing is mainly to remove the large residuals on each surface. Aging is to remove the residual stress of finishing. The finishing process of the positioning surface is the key process, which prepares the process for the subsequent finishing and gear machining. Gear machining is arranged after finishing.
Each process of the process flow should consider the release of stress and control of part processing deformation, regardless of which stage, control of deformation is analyzed and considered as an important element of part processing to ensure the machining accuracy of the part.
After the rough machining retains the finishing margin, the basic structure of the part has been fully processed into shape. Roughing for finishing retained margin, in order to ensure that the requirements of finishing, minimize the margin left to ensure that finishing will not cause large deformation after the removal of the margin.
