3D bends are pipe bends whose radius is three times the outside diameter of the pipe. A tube can be bent in several angels and directions. However, some of the most common and simple bends include the formation of an elbow that ranges from two degrees 90 degrees. Others are the U-bends that have a bend of 180 degrees.
Creating 3D Bends
The process involves the use of machines and mechanical force. Normally, pipe or tube bending machines are human powered, hydraulic assisted, or even pneumatic powered. The following are some of the most commonly used pipe bending processes.
Three-Roll Push Bending
This is one of the most commonly used processes. It is used to come up with bending geometrics that include multiple plane bending curves. Normally, the profile is led through a bending roll and the supporting roll or even rolls, while at the same time being pushed through the tool. The bending radius is normally determined by the position of the forming radius. This is one of the most flexible processes used in the creation of bends, for multiple radii can be actually obtained.
Rotary Draw Bending
This is one of the most precise technologies used to create 3D bends. It uses a feature called ‘die sets’ that has a constant center line radius. Rotary draw benders can be programmed to store several bend works with different degrees when it comes to bending. Technically, an IDX (positioning index table) is at all times attached to the rotary bender. This enables the operator to create complex bends that have varying planes. Rotary benders are largely used in tube bending.
When it comes to this bend tubing process, an induction coil is normally placed at the bend point of the pipe. Thereafter, the area is subjected to temperatures ranging from 800 to 2200 degrees Celsius. When it is hot, pressure is actually applied to bend the pipe. Finally, the pipe can be passed through cold air or water. Normally, this process is used in extremely large pipes such as gas pipes lines
Hot-Slab/Sand Packing Forming
In this process, the pipe is filled with sand and the ends caped. The pipe is then passed through a furnace with temperature of 870 degrees Celsius. Thereafter, the pipe is placed on the slab and the pins set in it. You can then bent the pipe around the pins using a tool such as the winch, or you can even apply some mechanical force. The sand that is normally put in the pipe minimizes any distortion in the cross section of the pipe.
This will probably be one of the first processes used on cold tubing and even pipes. Normally, a die is pressed against the pipe. This will force the pipe to fit the shapes. However, this process comes with its own drawbacks since the internal area is not supported. It results in some kind of deformation and perfect 3D bends and 5D bends will not be achieved.