Press Brake and Bending Services

Press Brakes in Depth

 

A press brake is a tool to bend sheet and plate materials.  

Two C-frames form the sides of the press brake along with a table at the bottom and a movable beam at the top.

The tool has two pieces one mounted on the table, and the other tool mounted on the upper beam.

Press Brakes are typically defined by their force, tonnage and maximum length of material.

Other parameters include the stroke length the distance between frame uprights or side housings, distance between side housings and frame uprights, distance to the back gauge, and the working height of the machine.

They can apply force to bend materials with mechanical, pneumatic, hydraulic, and servo-electric means.

Mechanical presses add energy to a flywheel with an electric motor, with a clutch engaging the flywheel to power a crank mechanism that creates vertical ram movement.

This method of powering a press brake leads back to the 1920’s.

In the 1970’s hydro mechanical and hydraulic power became available for press brakes.

These use two synchronized cylinders to move the upper beam.

They can be stopped at any time, unlike a mechanical press brake.

Electric press brakes are commonly used in lighter applications, making smaller parts.

They have a significant advantage in acceleration factor and speed, increasing their efficiency with small parts that have many bends.

Backgauge devices, where a piece of metal is placed with the device to accurately position the bend, allowing for more efficient processes.

They are able to speed up the time-consuming repositioning process, where traditionally the part has to be moved and placed by hand to set up the next bend.

Repositioning can take enough time that only around 20 percent of a shift is spent bending the parts.

Backgauges can also be programmed to move from bend to bend to easily make complex parts.

The die used can allow the press brake to make many kinds of bends and can even allow for multiple bends at once.

Why aren’t they called a metal bender, or metal former?

 

An old root word in archaic languages from before the year 900, in Old English brecan, in Germain brechen, in Gothic brikan, in Middle English breken, in Dutch broken, and in French brac.

The French term meant a lever, arm, or handle.  

The more general term of brake was “an instrument for crushing or pounding”, and brake eventually became machine.  

This was inherited from machines used to crush grain and plant fibers, so pressing machine and brake essentially mean the same thing.

As Old English brecan changed to break, and shifted meaning to destroy or divide solid objects into fragments the machine name became more confusing.

Middle English comes closer to the meaning of the word brake (as in press brake), with its verb breken.

Breken meant bend, change direction, or deflect.  

This meaning even included breaking light by deflecting it with a mirror, and breaking a bow while drawing back its string to notch an arrow.

Press is simpler to define, as the words presse “to crush or to crowd” essentially kept its meaning and became the modern press.

Essentially meaning a machine that exerts force by squeezing, fabricators often refer to the punches and dies as presses.

Pipe Benders

 

Creating curves in metal piping is the purpose of a pipe bender.

Some pipe bending processes include:

• Press Bending
• Rotary Draw Bending
• Roll Bending
• Induction Bending
• Packing

Press bending produces an oval cross section as it deforms the pipe as it is bent.

It is commonly used on cold pipes and tubing.

Bending pipe without the tool often results in buckling in the metal, creating crimping and flattening.

These malformed pipes break more frequently under pressure, can crack and generally look horrible.

Pipe benders have a curved piece called a die or former that forces the pipe to take its shape when pressure is exerted by an arm that pushes the pipe into the shoe.

The die must match the size and radius of the tube size, but can produce a variety of shapes.

Rotary draw bending focuses on a constant center line radius, and is programmable to allow for complex bends with differing planes.

It is the most popular for use in manufacturing handrails, frames, vehicle roll cages, lines, and handles.

Their bends are aesthetically pleasing and can be CNC machines for even more precision.

Roll bending uses three or more rollers to gradually apply the bend, decreasing the radius of the pipe in steps.

There is little deformation in the cross section of the pipe.

This method produces good results in coils of pipe and long gentle bends like in truss systems.

Induction coils are placed around a section of pipe for induction bending.

This heats the pipe somewhere between 800 and 2200 degrees fahrenheit.

Then pressure is applied to the heated pipe to bend it.

Afterwards it is quenched with air or water spray, or sometimes with ambient air.

Thick walled or large radius pipe is easier to bend with this method.

Industries that benefit from this process are petrochemical, construction, power generation, and city heating.

Packing fills the pipe with various materials prior to bending.

Water in a solute solution can be frozen into a pipe and then bent while the ice is cold and flexible due to the solute (sometimes soap), trombones, for example, are made this way.

Pitch was used in the past, but the difficult cleanup process made it less and less appealing.

Sand is another method, where the pipe is filled with fine sand capped at the ends and heated in a furnace to 1,600 F or higher.

A slab with pins set into it is then used along with a winch, crane, or mechanical force to bend the pipe.

This minimizes, but does not prevent, distortion in the cross section of the pipe.

Article refrences:

https://en.wikipedia.org/wiki/Press_brake

https://www.thefabricator.com/article/bending/why-is-it-called-a-press-brake-

https://en.wikipedia.org/wiki/Tube_bending