The deformation of thin-walled parts during turning is multifaceted. The clamping force when clamping the workpiece, the cutting force when cutting the workpiece, and the elastic deformation and plastic deformation generated when the workpiece blocks the tool cutting make the temperature of the cutting area rise and generate thermal deformation.
The cutting force is closely related to the cutting parameters. From the Metal Cutting Principle, we can know that the back cutting amount ap, the feed rate f and the cutting speed V are the three elements of the cutting parameters. During the test, it was found that:
1) With the increase of back cut and feed, the cutting force and deformation are also increased, which is extremely unfavorable for turning thin-walled parts.
2) Reduce the back cut and increase the feed rate. Although the cutting force decreases, the residual area of the workpiece surface increases and the surface roughness value is large, which increases the internal stress of the thin-walled parts with poor strength and also leads to the deformation of the parts.
Therefore, during rough machining, the back cutting amount and feed amount can be larger; During finishing, the back cut is generally 0.2-0.5 mm, the feed is generally 0.1-0.2 mm/r, or even less, and the cutting speed is 6-120 m/min. The cutting speed shall be as high as possible during fine turning, but not too high. Reasonable selection of the three elements can reduce cutting force and thus reduce deformation.