WHAT IS SECTION BENDING?

Section bending, also called profile bending, metal is done in a wide variety of metals in various ways.

HOW TO CHOOSE THE PROFILE BENDING MACHINE

Select the metal profile to bend

Next, you will find relevant information, including the processing capabilities of different profile bending machines manufactured by BIT related to the project you care about.

Description

Section bending, also called profile bending, is done in a wide variety of metals in various ways. There are two main processes – cold bending and induction bending, our machine is cold bending.

Important reading:2021 update:Read before operation of profile bending machine

What Is Section Bending?

Section bending, also called profile bending, metal is done in a wide variety of metals in various ways.

Bending process of profile bending machine
Bending process of profile bending machine

First of all, the curving of profile bending machine (also calledsection bending machine or section bender) shapes—angles, bars, beams, channels, tees, pipe, and tube, are all part of section bending.

Here is a glossary of common bending-rolling terms, taken from Design Guide 33.

Bent metal profile
Bent metal profile

Section bending, therefore, comprises all types of profile bending.

Cold bending

Cold bending is accomplished by passing the steel member back and forth between sets of rolls. The point load applied by the central roller is sufficient to take the steel past its yield point and introduce a permanent set.

Cold rolling is a suitable technique for curving (rolling) structural steel sections, pipe and tube, and flanges where very tight radius bends or ‘elbows’ are generally not required.

More cold bending knowledge

Cold bending is suitable for bending metal profiles

Profile bending machine use a technique called cold rolling, also known as ring rolling to produce quality curved sections in a cost effective way.
Large sweeping curves, varying radius curves, such as ellipses, tight bends, rings and coils, can be achieved for a wide range of sections and material types.

Application


Applications cover a broad spectrum of industry, including; building, tunnels, bridges, civil excavations, architectural features, pipe and mechanical works for materials handling and storage, and machinery etc

Bendable profile

What can BIT provide for profile bending?

BIT section bending machine now have the leading capacity worldwide in section bending and gives customers the confidence to design structures with minimal limitations. BIT can provide bending of standard angles, bars, beams, channels,pipes,tubes and tees and able to bend aluminum extrusions—even if it is a complex shape—in order to meet of customers needs.

Our profile bending machine models and bending dimensions

Our profile bending machine can bend up to the section modulus: 1700 cm3

View our Specification page

Section Bending Process:

To bend sections, there are two main processes – cold bending and induction bending. Cold bending is accomplished by passing the steel member back and forth between sets of rolls. The point load applied by the central roller is sufficient to take the steel past its yield point and introduce a permanent set.

section bending process
Section Bending Process

The bending takes place between three points. As the diagram shows, no bending takes place until the section touches all three points or rollers.

Cold bending takes the material past its yield point which strain hardens the steel to some degree. Some of the yield plateau has to be used, so in general plastic design is not recommended.

The toughness of the steel can also change, particularly at small radii. It is worth emphasising that at most radii found in structural applications, the changes are modest.

section bending curving steel
section bending curving steel

For normal low carbon steels and including structural steel, the strain induced during the bending process produces no real problems, as he material exerts the same elastic characteristics in the elastic range.

Strain curve

As mentioned, during the rolling bending process, the material must have exerted on it a stress greater than its yield strength or elastic limit.

This is the maximum stress that the material can be subjected to and still spring back, or return to its original length.

The yield point or elastic limits is shown as point ‘A’ on the figure below, a typical stress-strain curve. A stress less than the yield strength will not permanently bend the material.

The amount of stress to apply to the material being bent is in area ‘C’, which is the plastic region. These lines show how, when the stress is removed, the material will spring back to a length somewhat smaller than when the stress was being applied.

Section Rolling Process
Section Rolling Process

Ductility

The steel sections become work hardened when using the cold bending process.

The amount of work hardening is dependent on the radius required and the geometry of the section.

The results in a ‘flattened-out’ stress-strain curve as shown in the diagram above.

A tensile test on a sample of steel that has been cold-roller bent will show a small loss in ductility, but a higher Ultimate Tensile Strength, which results in a loss of some ductility.

Even though there is a loss of some ductility, for normal structural applications, the effect is minimal and can be ignored.

Visible distortion

Usually, the most important effect of the bending process is aesthetics, not structure. The steel on the outside of the curve tends to stretch (and therefore thinner), while the steel on the inside of the curve tends to become thicker.

The bending process may produce some visible deformation on the section. For example, the hollow section is thinner, and the bending process will cause visible ripples on a smaller radius. Therefore, our expert team will often suggest when it is better to provide thicker The thickness reduces the impact caused by the bending process of the wall part.

Minimum Radius And Tolerance:

The minimum radius to which a section can be bent without any meaningful distortion depends on the section properties and bending methods being used.

As the years have gone by these minimum radii have been reduced as new techniques have been developed, so the minimum has continued to get smaller

Normal bending tolerances for single radius bends are in line with those specified in the National Structural Steelwork Specification.

List of the BIT profile bending machine bent radii

It is not easy to provide a definitive and comprehensive list of the radii to which every section can be curved.

There are large numbers or standard sections (each with different bending characteristics), there are different methods of bending (hot and cold), and the end-uses vary widely.

Also, with continuing technical developments, ‘minimum radii’ also change.The minimum radius you need to bend is best to view our bending machine specifications before purchase.

View our Specification page

Sections radius curves

In general, sections, tubes and hollow sections can be curved to single radius curves, to multi-radius curves, to parabolic or elliptical curves, or even to co-ordinates.

They can also, within limits, be curved in two places or to form spirals.

There are, however, a number of physical constraints which limits the degree to which three-dimensional curvature is possible in practical terms.

View Tolerance Information page

Applications

Section Bent Parts

Section bending has been used to create a large range of products, including microwave and other antennas.

In microwave, the aluminum extruded profile can be seen in the point-to-point antenna. Other complex aluminum parts are also used as turrets for machine gun mounts on military equipment.

Formed channels can often be seen on the corners of the luggage conveyors at airports.

You can see the curved unistrut inner wing channel that guides the roller to support the curtains around the hospital bed, or the hook that supports the shirt in the laundry room. The curved forming angle can be regarded as the basis of the tank.

Other applications can include roller guides for holding up hospital bed curtains, supporting hooks for laundry or even the base of tanks.