Key Roles and Application Techniques of Mandrels in Precision Bending with Hydraulic Pipe Bending Machines

A mandrel is a core tool for ensuring the bending quality of thin-walled pipes (with wall thickness/pipe diameter ≤ 5%).

Mandrel Type Selection

Cylindrical Mandrel: Used for simple bending with R ≥ 2D (lowest cost).

Ball-Jointed Mandrel: Suitable for multi-angle bending with R = 1D ~ 2D, featuring higher degrees of freedom.

Flexible Shaft Mandrel: Applied for sharp bending with R ＜ 1D; its flexible structure prevents pipe jamming.

Application Techniques

Lubrication: Apply molybdenum disulfide paste on the mandrel surface, and reapply it every 10 bends.

Positioning: The front end of the mandrel should be 3-5 mm away from the bending starting point (too close causes pipe cracking, while too far leads to pipe wrinkling).

Maintenance: Disassemble and clean the ball-jointed mandrel weekly, and check for wear on its spherical surface.

Data: When bending Φ25×1mm stainless steel pipes using a ball-jointed mandrel, the ovality is improved from 0.72 to 0.92.