February 20th, 2019
Induction pipe bending is a relatively new technology that originated in Eastern Europe in the 1960’s, and all the way through until the 1970’s the machines were only used for bending large diameter pipes, upwards of 60” (1524mm) outside diameter in some cases. It wasn’t until the mid-late 1970’s that the first commercial induction pipe bending machines were manufactured to cover smaller diameter pipes of around 6”-28”, these were produced in either the USA, UK or Japan.
The Induction heating operation itself has been used to heat metals for many years and was typically used for the hardening of metal parts. The process involves the use of a high frequency current, which concentrates on the surface of the material therefore in typical applications only the surface is hardened.
To apply the same process to pipe bending, the heat generated through the use of medium frequency inductive power (approximately 1000 cycles per second) is required to be transferred through the full thickness of the pipe in order to temporarily reduce the yield strength to a point at which the material can be bent.
The pipe is contained in the body of the induction pipe bending machine and clamped at the front end, with a pusher bar or clamp at the back end. The clamp is mounted on a bending arm, which pivots up to 180ᵒ around a fixed point. The machine operator can set the required radius on the pipe bending machine by adjusting the distance between the pivot point and the centre of the clamp.
The major difference between induction pipe bending, and other pipe bending methods is that the pipe is pushed rather than pulled around a radius, thus, the vast majority of the forces are in the compressive mode, which allows for bending without the need for internal or external dies. Ovalities are much improved when compared with other pipe bending methods where internal dies are not used when bending to small radii.
Barnshaws offer induction pipe bending of pipes from 4”-32” and radii from 2D through to an infinite radii. We recommend an initial consultation with our sales team before design as dimensional control can be obtained by using the correct proportion of pipe outside diameter (D) vs wall thickness (T). This is generally referred to in pipe bending as the D/T ratio where a figure of 50 or below will almost guarantee all the dimensional tolerances are met, and pipe bending with D/T ratios over 50 can be met by adjusting other parameters such as the tightness of the bend (R/D).
To learn more about induction bending and the services Barnshaws can offer, click here: Induction Bending
