Alternatively, if your part requires a CLR smaller than 8 times the pipe or tube OD, roll bending isnвЂ™t the right choice. Roll bending may be best if parts require only large radii. For all of these applications, it would be impractical or simply impossible to build the large bend die for other bending methods. This method is ideal for large-radius bends, coils, and large-radius sweeps. Although the rollers need to match the workpiece outside diameter (OD), they donвЂ™t need to conform to the desired radius like a bend die (see Figure 3). Pipe or tube is passed through three rollers configured in a pyramid, and the rollers apply varying amounts of pressure to form the desired CLR. Roll bending is typically used for large-radius bending.

The part is complex and has multiple bend radii.

Bend roundness and cosmetics are important.

Bend appearance or roundness is not critical.Д¬ompression bending is not right for your part if:.The CLR does not need to be very tight.Low-cost, high-speed production is important.

Handles, furniture, and frames of many varieties are typical applications for this type of bending (see Figure 2).Д¬ompression bending may be right for your part if: Dual bending heads are especially suited for (but not limited to) producing symmetrical parts. Therefore, compression bending can compromise tube roundness, and tight radii cannot be bent.Д¬ompression bending equipment has advanced to include CNCs, and some machines have two heads that can produce two bends simultaneously, cutting production time in half.

The bend die radius must match the desired radius for the part. Compression BendingДuring compression bending, a counter die bends, or compresses, the material around a stationary bend die (see Figure 1). Understanding the basic tube bending methods, including their capabilities and limitations, can help you uncover the best and most economical way to achieve a quality bend. Each is simply different and best suited for specific applications. No method is better or worse than the other. In roll bending and freeform bending, the CLR is determined not by the toolingвЂ™s size, but by how the tooling moves. In both compression and rotary draw bending, the size of the bend die determines the workpiece CLR. Mandrel bending excels when it comes to forming tight radii in thin-walled tubes and pipes. In rotary drawing, a mandrel can be inserted inside the tube, a process called mandrel bending, to help prevent defects while the material is being formed around the bend die. In compression bending and rotary draw bending, the pipe or tube is formed around a bend die, though each forms the tube around the die in a very different way. And each bending method involves different variables to create the desired product with the required CLR. The CLR is the radius of the neutral axis, where there is no material compression or expansion. Tube and pipe bending operations use various methods-including compression bending, roll bending, freeform bending, and (the most common type) rotary draw bending-to achieve the desired result.Д®very bend has an inside bend radius, outside bend radius, and centerline radius, or CLR. There is no вЂњone-size-fits-allвЂќ process that can produce a quality pipe or tube bend for every application.

Large radius tube bending