Bending machine (manufacturing)

A bending machine is a forming machine tool (DIN 8586). Its purpose is to assemble a bend on a workpiece. A bend is manufactured by using a bending tool during a linear or rotating move. The detailed classification can be done with the help of the kinematics.[1]

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Universal bending machine for flat material

CNC bending

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CNC bending machines are developed for high flexibility and low setup times. Those machines are able to bend single pieces as well as small batches with the same precision and efficiency as series-produced parts in an economical way.

Universal bending machines – modular construction

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Universal bending machines consists of a basic machine that can be adjusted with little effort and used for a variety of bends. A simple plug-in system supports quick and easy exchange of tools.

The basic machine consists of a CNC-operated side stop, a work bench, and software for programming and operating. Its modular construction offers an affordable entry into the bending technology, because after an initial investment the machine can be customized and extended later without any conversion. That means the basic machine delivers a bending stroke, and the tool determines the kind of bending.

90' bending tool

In the case of bending tools they are classified by the kind of generated bends. They can be constructed to adjust the bending angle by reference, stroke measurement or angle measurement.

CNC machines usually abstain from a reference part. They grant a high bending accuracy starting with the first work piece.

Standard bends

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Standard bending with a universal bending machine

All bends without an extraordinary geometry belong to standard bends. The distance between a bend and the material end is quite high providing an adequate bearing area. The same with one bend to the next.

Typical tools are a so-called bending former combined with a prisms with electronic angular measurement or an ordinary prism.

For U-bends where tight and narrow bends are necessary, the bending former is replaced by a bending mandrel. A bending mandrel has a narrow geometry.

Offset bending

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Offset bending tools are used to assemble two bends with a small distance between in one step.

Edgewise bending

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Edge bending tools are used if the bending axis is placed parallel to the tight side of the work piece. Tools for bending on edge may include electronic angular measurement allowing a high bending accuracy.

Torsion bending

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Torsion tools are able to rotate the workpiece on the longitudinal axis. Alternatives are complex assembly groups with standard bends.

Angular measurement and spring back compensation

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For producing single pieces as well as small batches with the same precision and efficiency as series-produced parts, a spring back compensation is helpful. A bending accuracy of +/- 0.2° starting from the first work piece is achieved due to calculated spring back compensation and the use of electronic tools.

Operating mode angular measurement

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Bending prisms with electronic angular measurement technology are equipped with two flattened bending bolds. That bold rotate while bending giving a signal to the angle measurement. The measuring accuracy is about 0.1º. The computer then calculates the required final stroke and spring back of every bend is compensated regardless of material type. A high angle accuracy of +/- 0.2º is achieved instantly with the first workpiece without adjustments. Compared to adjustment by reference, material waste amounts are decreased, because even inconsistencies within a single piece of material are automatically adjusted .

Operating mode stroke measurement

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Wherever bending prisms with electronic angular measurement are not suitable, a small distance between the bends might be a reason, bending prisms without electronic angle measurement are applied. In that case the control unit can be switched from angular measurement to stroke measurement. This method allows the pre-selection of the stroke of the bending ram in mm and therefore the immersion depth of the punch into the prism. Setting accuracy is +/- 0.1 mm. A final stroke is usually not required. Further development of the stroke system enables the user to specify an angle from which the stroke is calculated by using stored stroke functions. Bending accuracy in that case is dependent on material properties such as thickness, hardness, etc. which may differ from one work piece to another.

Programming and principle of operation

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Graphical user interface of a bending machine

Programming is done on a PC equipped with dedicated software, which is part of the machine or connected to an external workstation. For generating a new program engineering data can be imported or pasted per mouse and keyboard. Through a graphic and menu-driven user interface previous CNC programming skills are not required. The software asks for all necessary values and checks all figures. Inputs can be corrected at any time and minimum distances are checked instantly to guard against improper inputs. The software automatically calculates the flat length of each part being bent and determines the exact position of the side stop. The part is shown on a screen.

Ideally each program is stored in one database, so it is easy to recover them by search and sort functions.

Networking with the whole production line

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Networking of CNC machines

A lot of organizational effort and interface management is saved, if the CNC bending machine is connected to the previous and subsequent process. For a connection to other machines and external workstations corporate interfaces have to be established.

• One software for programming subsequent production steps at once
• Using a standard industrial PC a variety of machines can be easily networked with among each other
• shared data base for easy integration into existing workflow system and backup at an external server
• import production data from other systems or from construction programs (e.g. DXF files)

Networking with a punching machine

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If a part is bended, in most cases a prior process was inserting holes to mount it in an assembly group. Therefore, a punching machine is an option. Some programs enable the operator to program both step by one software tool.

See also

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References

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• M. Weck: Werkzeugmaschinen Maschinenarten und Anwendungsbereiche (VDI-Buch) Springer Vieweg Verlag, 6. Aufl. 2005 (2. August 2005), ISBN 3540225048

Nowadays, when people talking about press brake, they mainly refer to the bending machine for sheet metal bending. However, do you know why such a sheet metal bending machine is been called press brake? For most people, this question confused them for a long time. Before you understand why it is called the press brake, you must understand the meaning of the terms.

 

The press brake is a pressing machine that is perfect for bending sheets and plate materials. It is most commonly used for sheet metal. The structure of the press brake mainly includes a bracket, a worktable and a clamping plate. The workbench is composed of a base and a pressing plate, and is placed on a support. The base is composed of a seat shell, a coil and a cover plate, and is connected with the clamping plate through a hinge. The coil is placed in the recess of the seat shell, and the top of the recess is covered with a cover plate. When in use, the wire is energized to the coil, and the gravitational force is generated on the pressing plate after being energized, so as to realize the clamping of the thin plate between the pressing plate and the base.

 

The Origin of The Name of Press Brake

From the origin of the name, please note that the term press brake is completely wrong, because nothing has been damaged or broken. A press brake doesn’t “step on the brakes” to bend, so why is it called a press brake? A brief history of a few words reveals the answer.

The term brake, as used in modern sheet metal fabrication, was derived from the Middle English verb breken, which means to break or change the direction of or deflect. A few centuries later, the past participle of "brake" evolved into "broken". This means that when you look at the etymology, "break" and "brake" are closely related.You could also “break” when you drew back the string of a bow to shoot an arrow. You could even break a beam of light by deflecting it with a mirror.

Now we know the verb “brake” refers to a machine that bends. And where does the word “press”—describing the machines we know today—come from?

The word press was derived from the phrase presse in the 1300s. This noun means to crowd or crush. In the 14th century, the press became a machine used to juice olives and grapes and for pressing clothes. Since then, press has evolved into a machine or machine that applies force by pressing. In manufacturers’ applications, punch presses and molds can be called “presses” that apply pressure to metal plates and bend them.

That’s where the “press brake” term comes from. Now that you understand where the name comes from, you know why the tool is called a press brake. You also understand better how it works and how the device shapes the sheet metal.

 

The Development of Metal Sheet Bending Machine

In the past, if you wanted to bend sheet metal, you were forced to attach it to an appropriately sized piece of sheet metal mold, which was filled with lead shots or sand. The T-stake was then used to pound the sheet into the desired shape. This was most common when making breastplates for armor suits. While it is still a method used today, it is manual and taxing on energy and time.

The first press brake was developed in the early 1920s. Today, both electric and mechanical press brakes help make it easier to shape sheet metal. When it was invented, it was a tool for pounding and crushing. Eventually, the name brake because synonymous with the machine, and thus, the device was called a pressing machine.

With the advancement of bending technology, bending machines have evolved from manual bending machines to mechanical bending machines, pneumatic bending machines, hydraulic bending machines and fully automatic bending machines. Senfeng Leiming automatic bending machine is widely used, reducing unnecessary operation procedures and saving manpower and material resources. If you want to know more about metal sheet bending machine, please contact SENFENG LEIMING.

 

E-mail:senfeng@sfcnclaser.com 

Whatsapp:+86-13210546543

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