Rotary Draw Bending

Rotary draw bending clamps the tube against a rotating bend die and draws it around a fixed centre-line radius. The bend die sets the radius, the clamp die grips the tube to it, the pressure die supports the trailing straight, the wiper die prevents wrinkles on the inside radius, and — for thin-wall or tight-radius work — a mandrel supports the bore. Together they produce the tightest, most repeatable bends of any bending method.

Because the radius is fixed by the bend die, each centre-line radius needs its own die: changing radius means changing tooling, not just a setting. Every material also springs back slightly after bending, so the CNC over-bends by a calculated compensation angle to land on the target. On a Telhoo machine these motions are servo-driven — bending, feeding and rotating — and stored as a program, which is why a complex multi-bend part repeats exactly.

Rotary Draw Versus Other Methods

• Rotary draw — tight radii, high accuracy, precision tube
• Roll bending — large-radius sweeps and coils
• Compression bending — simple and low cost for larger radii
• Mandrel-assisted rotary draw — thin-wall and cosmetic bends

Rotary draw is the method inside every Telhoo CNC and NC pipe bender. For machine models and specifications see the CNC pipe bending machine range, or send your part and we will advise the tooling and radius.