As a process, bending a tube requires the tube be loaded into a tube or pipe bender and secured in place between two dies. Mechanical force is then applied to push the stock against a die forcing it to conform to that shape. This was press bending which was probably the first bending process used on cold tubing and pipes.
These are the most popular machines for bending tube or solid pipes for uses such as frames, handrails, handles. The Rotary Draw method creates attractive bends.
Tube bending can be done by passing the tube through rollers which apply pressure. Coils of pipe can be produced using this method and long bends.
A heating coil is wound around a pipe which is heated to as 2,000 degrees Fahrenheit. Pressure is applied to the hot pipe to bend it. The pipe is then cooled with water or air.
Devices Used for Bending
Mandrels are inserted into tubes to add extra support while bending. These might be steel rods or metal balls linked together. Springs can also be inserted into the copper pipe. The spring will have a slightly smaller diameter than the pipe.
Power for Bending
Tube bending machines can be human, hydraulic, pneumatic, or electric powered. Bending tubes in fabrication are done by various methods. In a recent article in the Journal for Cleaner Production, the author notes that a significant energy savings can be achieved by using electricity to power tube bending machines. The efficiency of the process was also found to be increased by up to 50% by using electricity.
This tour around the bend and back again gives a general overview of the processes involved in bending metal tubes using press bending, rotary, roll, or heating methods and the device and power used in bending.