How does a CNC press brake work?

A CNC press brake is a modern machine for sheet metal bending. Modern press brakes are operated and controlled by a computer that helps quickly set the specifications of a job and perform production cycles according to different needs, both short and long term.

Importance of CNC Press Brakes in Manufacturing

CNC press brakes are highly versatile machines capable of handling a wide range of metalworking tasks. Their programmability allows for precise control over bending operations, ensuring accurate and repeatable results. From simple bends to complex geometries, these machines can efficiently process various materials, including steel, aluminum, and stainless steel. This versatility makes CNC press brakes indispensable in industries requiring high-quality, customized metal components.

Types of CNC Press Brakes

Hydraulic Press Brakes

Hydraulic press brakes, known for their precision and power, utilize oil cylinders to control the bending process. While offering superior performance, they can be complex to maintain and may have higher operating costs.

CNC hydraulic press brakes automate many functions, improving efficiency and accuracy. Synchronized hydraulic press brakes, a more advanced version, use two independent cylinders for precise control and greater versatility.

Electric Press Brakes

Electric press brakes are a newer technology, offering speed, repeatability, and energy efficiency. However, they may have limitations in force capacity and versatility compared to hydraulic press brakes.

Servo press brakes, a type of electric press brake, use servo motors for precise control and quieter operation. They are suitable for applications requiring high accuracy and low noise levels.

Hybrid Press Brakes

Hybrid press brakes combine the best aspects of hydraulic and electric press brakes, offering exceptional performance. VICLA, a leader in hybrid technology, provides machines with:

• Microscopic precision: Ensures consistent and accurate bends.

• Energy efficiency: Up to 78% energy savings compared to traditional hydraulic press brakes.

• Versatility: Handles a wider range of applications than electric press brakes.

Key Considerations:

• Force capacity: Hydraulic press brakes generally offer higher force than electric or hybrid options.

• Versatility: Hybrid press brakes are more versatile than electric press brakes.

• Maintenance: Hydraulic press brakes require more maintenance due to their complex systems.

• Energy efficiency: Electric and hybrid press brakes are more energy-efficient than traditional hydraulic press brakes.

• Noise: Electric press brakes, especially servo press brakes, are generally quieter than hydraulic press brakes.

CNC Press Brakes Main Components: Bed, Ram, Punch and Die, Back Gauge

Frame

Also called beam, which is the movable part on which the punches are installed.

It runs vertically along the Y axis and is positioned by numerical control at specific positions according to the operation to be performed. There are independent Y1 and Y2 axes that regulate the possible unbalance of the machine’s main ram (in a hydraulic press these are the different strokes that the cylinders can perform).

The bench or bed

Is the fixed part under the beam where the dies are installed. It can contain a centering (or crowning) system to compensate for the crossbar deformation, especially in machines two meters/6’ wide and up.

Such a system can be found in a variety of versions which embrace different design philosophies among manufacturers or are based on specific machine types or families.

Excellent results are possible through the use of a hydraulic crowning system. In this case, a number of high pressure and low flow rate cylinders are inserted within the machine bench to compensate for the frame deformation during the pressing phase by producing a counterforce from underneath.

The lateral frames

Lateral frames represent the side plates or shoulders that define the width of the machine frame. These can also be different: for example, machines with synchronized hydraulics almost always have a gap, called throat, so a sheet that is wider than the distance between the shoulders or columns can be inserted into the machine frame.

Rear Backgauge

Tthis device ensures that the bend is positioned correctly in the part to be produced. It usually consists of a beam on which two or more "finger stops" (backgauges) are mounted. They are able to move sideways to find the correct position.

The axes, on the other hand, are:

• x: "Forward and backward", sets the length of the bend (flange) from the center of the die to the tip of the fingers.

• r: "up and down", adjusts the height of the stops/fingers to allow the fingers to reach the part better and so that dies of different heights can be mounted.

• z: "left and right", adjusts the position of the stop/s on the table, to ensure that the back fingers are in the correct support position towards the punch and die.

CNC Control System: How it Works

A CNC press brake's brain is its sophisticated CNC system. This system interprets instructions and controls the machine's movements for precise, automated bending. Key components include Control System, Programming and Axis Control.

Control System

Hardware and software that processes commands and controls machine movements.

Programming

Operators create programs using specialized software to define bending parameters. The CNC system then translates these instructions into machine-readable code, specific to the press brake manufacturer.

Axis Control

The CNC system manages the vertical movement of the ram and the horizontal positioning of the backgauge. Additionally, some press brakes feature a crowning system that adjusts the bed's curvature to ensure uniform bending.

• Ram: The ram applies force to the metal sheet, creating the bend.

• Backgauge: The backgauge positions the sheet metal accurately before bending.

• Crowning: This optional feature helps prevent uneven bending by adjusting the bed's shape.

All mechanical components of the press brakes are integrated with numerical control, which is responsible for setting the bending parameters. The most important parameters in the bending process are:

• thickness of the sheet;

• dimensions of the sheet;

• bending angle;

One of the many advantages of numerical control lies in the possibility of implementing bend simulations, during which the machine verifies if there are any collisions or overloads.

What are the benefits of using a press brake with numerical control?

There are many benefits obtained from numerical control programming on CNC press brakes:

• Speed

• Precision

• Repeatability

• Adaptation

• Flexibility

• Agility

The main technologies of ESA numerical control

ESA 650 and 660 numerical control

This version, with colour graphics and multilingual function, allows the automatic calculation of the PMI according to the type of tool and the required angle, and the automatic calculation of the bending force. Optimisation options include optimal bending sequence, and display of any collisions in the sequence proposed by the operator, also carrying out anti-collision checks between the axes and the matrix in the automatic phase.

ESA 675 numerical control

It is equipped with an ultra-large 21” LCD HD Multi-touch colour screen and integrated Windows PC, which allows drawings to be opened in PDF format or in another format directly on the machine. Furthermore, it allows optimal management of all Cad-Cam 3D. It is equipped with RAM 8 Gb, 4 USB ports 2.0 + 4 USB ports 3.0.

Delem numerical control

It is a simple and intuitive Numerical Touch Screen control, with a high level of functionality and a user-friendly and modern graphic environment. It is available with screens of different sizes and features customised to your needs.

Press brake programming: management of 3D projects

Modern press brakes can be equipped with programming software for the preparation and processing of 3D projects that guarantees multiple advantages.

The programming software available on VICLA sheet metal bending brakes, for example, guarantee maximum efficiency in tool selection, based on bend radius, maximum force of the press brake, collision control, and the availability of different types of tools and splits.

It is also able to recognise and automatically manage the flattened bend thanks to definition of the angles of the pre-bend and the inner counter-bends, calculating the best bending sequence, avoiding collisions and taking into account the availability of splits and skids.

Although automatic management almost always finds a solution, the operator also has the possibility to intervene manually and change the data set by the software.

For positioning of the stops, the software available on VICLA press brakes provides automatic and manual control options for the back gauge, thanks to the 3D simulation that allows you to view all the moving elements, including the tools, the part to bend and the machine structure.

Finally, the software provides the complete tooling report, from the 3D bending sequence, including detailed information bend by bend. The report can be printed or displayed directly on the numerical control.

Industry 4.0 and Smart Manufacturing

CNC press brakes are increasingly integrating with Industry 4.0 technologies, transforming them into smart manufacturing assets. This involves connecting machines to networks and equipping them with sensors and data analytics capabilities.

Key benefits of Industry 4.0 integration include:

Predictive maintenance: Using data analytics to predict equipment failures and schedule maintenance proactively.

Real-time monitoring: Tracking machine performance and identifying bottlenecks in the production process.

Improved quality control: Implementing automated inspection systems to ensure consistent product quality.

Enhanced connectivity: Seamless integration with other manufacturing systems for streamlined workflows.

Automation and Robotics

Automation and robotics are playing an increasingly important role in CNC press brake operations.

Sheet metal bending automation has advanced significantly in recent years. Collaborative robots (cobots) and anthropomorphic robots have revolutionized the industry, replacing traditional Cartesian robots. These automated solutions not only speed up the bending process but also reduce human error.

Benefits of automated bending cells include:

• Increased efficiency: Faster bending cycles and reduced downtime.

• Improved quality: Reduced human error and more consistent results.

• Ergonomics: Relieves operators from repetitive tasks.

VICLA has developed advanced solutions for automated bending cells. These solutions can help you streamline your production process and improve your bottom line.

To learn more about how robotic bending solutions can transform your sheet metal fabrication, read our comprehensive guide “Robotic bending: advantages and limits”.

As technology continues to advance, we can expect to see even greater levels of automation and robotics in CNC press brake applications.