In the machining industry, thin-walled workpiece is prone to vibration and deformation during turning due to its poor rigidity, and its geometric tolerance and dimensional tolerance cannot be guaranteed. If the solution is not appropriate, it will even make the processing impossible.

1. Putting forward processing problems

The processing of thin-walled parts is a difficult problem in turning. The reason is that thin-walled parts have poor rigidity and weak strength, and are very easy to deform during processing, which increases the shape and position error of parts, and is not easy to ensure the processing quality of parts.

Therefore, strict requirements are put forward for the clamping of thin-walled parts, the reasonable selection of tools and the selection of cutting parameters in turning.

The thin-walled stainless steel pipe processed by us is the nozzle heat-shock sleeve of a product. This workpiece is a large-diameter thin-walled workpiece, with an outer diameter of 292mm, and the material Z2CND17-12 nitrogen controlled stainless steel. The wall thickness is required to be 4mm. The total length of the workpiece is more than 550mm (with clamping allowance). The roundness is required to be 0.05mm. All surface roughness values Ra=6.3 μ m. It determines that the precision coefficient of this workpiece is very high.

2. Preparation of processing technology

(1) Increase the process chuck to lengthen the length from 550 mm to 610 mm

(2) Divide processing stages:

① Rough machining stage. Use rough turning and rough boring to remove the allowance. During rough machining, the back feed and feed can be larger; During finishing, the back feed is generally 0.2~0.5mm, the feed is generally 0.1~0.2mm/r, or even smaller, and the cutting speed is 6~120m/min. During finishing, the cutting speed should be as high as possible, but not too high.

② Semi-processing stage. Prepare for the finishing of the main surface, complete the processing of some secondary surfaces, and use semi-finishing turning to achieve the necessary accuracy and machining allowance before finishing. If the pipe is clamped on the chuck with too much force, the thin-walled parts will be deformed, resulting in roundness error of the parts. If the chuck is not clamped tightly, the parts may be loose and scrapped during turning. We adopt the method of clamping when rough turning and loosening when fine turning to control the deformation of parts. In the semi-finishing stage, the back cut is smaller, which releases the internal stress of the thin-walled stainless steel pipe and reduces the deformation of the finishing process.