Large CNC lathe solutions for slender shafts and large pipes

As the manufacturing industry develops towards high precision and high efficiency, the demand for processing slender shafts (length-to-diameter ratio L/d>25) and large pipe parts is increasing. Due to problems such as poor rigidity, easy deformation, and difficult to control processing accuracy, these parts put forward higher requirements for the process design, clamping method and cutting parameters of CNC lathes. DONGS CNC proposes a set of efficient CNC lathe solutions for slender shafts and large pipes.

1. Processing challenges of slender shafts and large pipes

Deformation caused by insufficient rigidity

Slender shafts and large pipes are susceptible to cutting force, thermal deformation and clamping stress during processing, resulting in bending, vibration or dimensional deviation, especially in the middle section. "Bamboo-shaped" or "concave" defects are prone to occur.

Thermal deformation and precision control

Cutting heat accumulation will cause the workpiece to expand. If the clamping method is improper (such as excessive top tightening force), it may cause axial extrusion deformation, affecting coaxiality and surface quality.

Balance between processing efficiency and cost

Traditional processing requires frequent adjustment of process steps, which is time-consuming and causes high tool wear, making it difficult to meet the needs of mass production.

2. Core solutions

1. Optimize clamping methods

Reverse cutting method and elastic center: The reverse cutting method in which the tool is fed from the spindle to the tailstock direction converts the axial cutting force into a tensile force to reduce the compression deformation of the workpiece; the elastic center compensates for thermal expansion to prevent the workpiece from bending due to thermal elongation46.

Multi-support point clamping: Use a tool rest, center rest or bearing support system to increase the radial stiffness of the workpiece. For example, a bearing center rest is used to provide strong support during rough machining, and a bearing tool rest is used during fine machining to achieve dynamic follow-up cutting and reduce vibration67.

Axial clamping technology: Axial tension is applied to the workpiece through a clamping head to offset the bending effect of the cutting force and compensate for thermal deformation, which is suitable for ultra-long and slender shaft machining4.

2. Tool and cutting parameter design

Tool geometry optimization: increase the rake angle (γ=13°~17°) to reduce cutting force; main rake angle (kr>60°) to reduce radial force; positive edge inclination angle (λs=0°~+10°) to guide the chips to the surface to be processed to avoid scratching the processed surface47.

Cutting parameter control:

Cutting depth (t): use a small cutting depth (0.1~0.3mm) to reduce cutting force;

Feed rate (f): appropriately increase the feed rate (0.1~0.2mm/r) to improve efficiency;

Cutting speed (v): medium and low speed (80~150m/min) to balance the influence of thermal deformation and centrifugal force

3. Process auxiliary measures

Cutting fluid cooling system: use high-pressure emulsion or cutting oil to reduce the temperature of the cutting zone, reduce thermal deformation and extend tool life.

Segmented turning and process planning: Divide the slender shaft into multiple segments for processing, use a center stand for support in the roughing stage, gradually increase the cutting parameters during semi-finishing and finishing, and adjust the process in real time with online detection technology.

Intelligent compensation technology: Compensate for tool wear and thermal errors through the built-in algorithm of the CNC system, such as using the FANUC OI system to achieve dynamic path correction and improve dimensional stability.

In order to solve the processing problems of slender shafts and large pipes, it is necessary to comprehensively optimize the clamping method, tool parameters and auxiliary processes. The integration of reverse cutting, multi-support clamping, intelligent compensation and other technologies can significantly improve the processing accuracy and efficiency. DONGS Solutions provides you with the best solution