Tube Bending and Pipe Bending Rules


Tube bending is among the elementary processes in steel fabrication. Industrial pipes and tubes are an important merchandise in manufacturing for each development and the transportation of different supplies. The vast majority of bent tubes are used as structural elements reminiscent of handrails, as components of steel furnishings frames and automobile roll cages, whereas piping is used for oil and water merchandise, hydraulic techniques and exhaust strains.

Tube Bending Processes

There are a number of steel fabrication methods for bending tubes and pipes, together with draw, press, ram and roll bending. They every apply pressure to bend the steel and there are frequent ideas to all of them, together with elongation and bend radius. There are additionally instrument capabilities that even have particular methods of affecting the bend reminiscent of mandrels and wipers. The right utility of all of the ideas affect the standard of the pipe and tube manufacture.

Bending Forces

When a tube is bent, the wall of the tube on the level it’s bent modifications in a mixture of how. The outside wall stretches and turns into thinner, whereas the interior part turns into thicker and compressed. It is a vital a part of the pipe bending course of to manage this deformation to verify a clean bend is achieved.

The bigger the tube, and the broader the radius of the bend, the much less seemingly deformation is an issue. It’s the thinner tubes and tighter bends that are inclined to create issues. Deciding how a tube needs to be handled is gauged by figuring out the wall issue, which is the ratio of the tubes wall thickness to its diameter. An identical comparability is then made between the centreline radius of the pipe and the exterior diameter to find out if the bending radius is inside manageable limits. Combining the 2 components permits the producer to outline the complexity of the bend, and due to this fact the proper bending method to make use of.

The place the partitions of the tube is not going to be significantly compromised, a primary die set can be utilized, reminiscent of bend, clamp and strain die array. The place the bend could have a extra pronounced impact on the fabric of the tube, a mandrel will likely be extra acceptable.


The place a primary die set is just not appropriate, a madrel will likely be used. It’s a system that may be inserted contained in the pipe on the level of the bend to supply assist for the pipe whereas it undergoes the bending course of. The place a bend will produced important thinning of the tube wall, and an elevated danger of a flattening of the pipe on the level of the bend the mandrel will defend towards this weak point.

Mandrels might be constructed in a number of methods, together with a single plug or a sequence of related balls that flex and alter themselves whereas the bend is utilized to the tube. In addition to offering this inner assist, a plug mandrel can assist to use further bending pressure on thicker pipes that may be harder to form.

Wiper Dies

When a tube is positioned underneath important stress throughout bending, reminiscent of when a skinny pipe is bent to a decent radius, inner wall compressions can happen leading to wrinkling of the pipe wall. A wiper die reduces the possibility of wrinkling occurring. The wiper is designed to be wedged into the groove between the tube and the bending die. This makes for a tighter match between the die and the pipe and leaves no house for the wrinkle to develop. Wiper Dies are sometimes used together with a mandrel to offer the pipe a most diploma of assist.


Elongation describes the diploma to which the fabric a pipe is produced from might be stretched earlier than struggling structural failure. As stretching of the fabric will all the time happen to some extent throughout pipe bending, this is a vital concern for producers. The overall rule is that because the bending radius grows smaller, the extra the fabric will stretch.

In lots of circumstances the collection of the correct steel or materials for a specific utility is dictated by the quantity of elongation that may be anticipated throughout bending and fabrication. For instance, chrome steel might be an costly possibility to provide a tube from, nevertheless it additionally has a better most elongation than different grades of metal, so it may be chosen as essentially the most acceptable materials if the pipe requires bends with a decent radius.


Source by Jerry Saddington