Press brake: what it is and how does it work?

A press brake is a specialized tool used in metalworking to bend sheet metal into various shapes and angles. It's an essential piece of equipment for industries ranging from small-scale fabrication shops to large-scale manufacturing plants. The technology on which operation is based is only trivial in appearance, however it hides remarkable developments in the mechanical and technological field. 

• How Does a Press Brake Work?
• Types of Press Brakes: 
  
  • Mechanical Press Brakes
  • Promecam Hydraulic Press Brakes
  • Servo Press Brakes
  • CNC Press Brakes
  • Hybrid Press Brakes
• Benefits of Press Brakes
• Applications of Press Brake
• Limitations of Press Brakes
• Alternatives to Press Brakes
• Conclusion

How Does a Press Brake Work?

Press brakes operate using two essential tools: the punch and the die. The die is a stationary V-shaped tool placed beneath the workpiece, while the punch is a movable component that applies force to bend the metal. The punch's movement is driven by a ram, which can be powered by various mechanisms such as mechanical, servo motors, hydraulic, or pneumatic systems.

To learn more about the different types of press brakes and how they work, check out our comprehensive guide, "A Deep Dive into Press Brake Technology." Inside, you'll find detailed information on components, terminology, and tooling used in the bending process.

Here are some key terms to familiarize yourself with when working with press brakes:

• Tonnage: The maximum bending force a press brake can exert.

• Bending Angle: The angle created between the two sides of the bent metal.

• Bending Length: The maximum length of sheet metal that can be bent with a particular press brake.

When Was Press Brake Invented?

Press brakes, while a relatively modern invention, have a history dating back to 1882 when the first patents were filed. Early press brakes were labor-intensive affairs, relying heavily on manual operations. To create a bend, a mold was first crafted to match the desired shape. Sheet metal was then placed on the mold and surrounded by a mixture of sand and lead shot. Workers would then use a T-stake to pound on the metal, forcing it into the mold's shape. This process, while effective, was slow and often resulted in straight, simple bends.

What are the differences between old press brakes and modern press brakes?

If we compare a modern press brake to one from fifty years ago, on the outside it seems that little has changed. However, the truth is that they are two completely different machines; the external elements may also have remained stationary with the typical design that we all know, but mechanics and electronics have evolved in a silent and inexorable way.

Conceptually, between a bending machine from the past and a modern one, there are no changes in the process; both, in fact, share the same purpose: to bring a punch to a matrix up to a certain altitude in the most precise and repeatable way possible. 

Yet, the modern press brake is the result of constant evolution. Just as happened with cars, which from a simple and almost rudimentary means of transport have become truly high-tech machines, the bending machine is also now a concentration of technological and mechanical innovation. However, both in the case of the car and the press brake, the basic mechanical components have remained the same, but over time they have been improved and refined.

Different types of press brakes

To grasp the intricacies of sheet metal bending and discover the optimal technology that balances efficiency, effectiveness, cost-efficiency, and versatility, it's essential to delve into the rich history of press brakes. Italy, a pioneer in this field, has fostered a thriving industry in the Brianza region, where businesses have consistently elevated the standards of Italian-made bending press brakes.

Renowned worldwide for their tradition and quality, Italian manufacturers, including Mariani and others, have played a pivotal role in shaping the evolution of press brake technology.

Mechanical press brakes

Mechanical press brakes, though still lingering in some workshops for less demanding tasks, are now largely obsolete due to safety regulations. Despite their outdated status, they were once highly regarded for their speed and pressure capability. Brands like Mariani and Omag were particularly renowned for their mechanical press brakes.

These machines operate using a flywheel mechanism that drives the up-and-down movement of the punch. A clutch system controls the gear shaft, resulting in a simple and user-friendly setup. This simplicity extends to maintenance, as components are generally easy to repair or replace. Additionally, mechanical press brakes often have a higher load capacity than their rated tonnage.

However, mechanical press brakes have significant drawbacks. They offer limited control over punch speed, leading to compromised bend quality and accuracy. These limitations, coupled with their safety risks, have made them obsolete in modern manufacturing environments.

Promecam "RG" hydraulic press brakes

Pioneered in France by the Italian-French inventor Roger Giordano, RG Promecam's hydraulic press brakes were known for their compact size and unique low-profile design.

A key feature that set them apart from other press brakes was the movement of the workbench instead of the upper beam. While most machines lower the beam to press the sheet metal, RG Promecam machines raised the workbench using a central hydraulic system. This innovative design offered simplicity and reliability, and it played a significant role in the history of Italian press brake technology.

However, these machines no longer meet modern safety standards. They lack the ability to adjust bending speed and modern safety features. Therefore, they require specific safety upgrades to remain operational.

Despite their outdated safety limitations, RG Promecam press brakes were once widespread and remain in use in some workshops today. In the post-war era, they represented a groundbreaking innovation. Their low-profile design allowed for the bending of large, closed profiles as they could be "embraced" by the upper part of the machine

Hydraulic press brakes with torsion bar

These press brakes are precursors to modern synchronized press brakes, sharing a similar appearance. They function by using a beam that descends via hydraulic pistons.

Typically, these machines have two or three axes:

• X-axis for the rear carriage

• Z-axis for the rear carriage height

• Y-axis for the beam descent

A distinguishing feature of these machines is the mechanical connection between the two hydraulic cylinders via a bar. This linkage ensures synchronized movement up to the lower dead center.

The position of the lower dead center is adjusted using two nuts that can be raised or lowered to modify the end-of-stroke height of the cylinders and beam. These press brakes were often controlled by a simple positioner, lacking internal memory.

Synchronised hydraulic press brakes

Hydraulic press brakes, a significant upgrade from mechanical alternatives, utilize two oil cylinders to precisely control the punch. This hydraulic system enables superior bending capabilities and enhanced accuracy compared to mechanical press brakes.

While offering these advantages, hydraulic press brakes come with increased complexity and require skilled operators. Maintenance costs can be high due to their intricate parts. Additionally, strict adherence to rated tonnage is crucial to prevent machine damage. Fluid leakage from the hydraulic cylinders remains a potential risk.

CNC hydraulic press brakes have emerged as a popular choice in modern manufacturing. These machines feature automated systems that precisely control movement and timing.

Synchronized hydraulic press brakes represent the state-of-the-art in press brake technology. They employ two independent hydraulic cylinders and proportional valves to regulate the upper beam's movement. This configuration offers greater versatility, allowing operators to adjust each cylinder individually to compensate for sheet irregularities.

CNC control in synchronized hydraulic press brakes provides advanced capabilities compared to positioners found in torsion bar press brakes. Operators can fine-tune various parameters, including parking time, lower dead center, bending speed, and decompression.

Electric press brakes or servo press brakes

Electric press brakes, the latest innovation in press brake technology, remain a specialized solution for certain applications. While they offer speed, repeatability, and energy efficiency, they often lack the versatility of synchronized hydraulic press brakes, especially on large formats.

Two primary methods are used to operate electric press brakes: ball screws and special belts.

Servo press brakes utilize servo motors to power the punch. These motors, also known as servo-electric press brakes or electric press brakes, transfer mechanical energy to the punch via a pulley and belt system.

Servo motors offer precise control over punch movement due to their numerous adjustment options. This translates to accurate bends and a quieter workplace. Eliminating hydraulic or pneumatic systems also prevents leakage issues.

However, servo press brakes have a lower force capacity compared to other options. This limitation restricts their use in industries requiring higher tonnage.

CNC press brakes

CNC press brakes, versatile and automated machines, utilize computer numerical control (CNC) systems to deliver exceptional precision and repeatability. By incorporating CNC technology, businesses can significantly boost productivity, efficiency, and accuracy while reducing labor costs.

Ideal for a diverse range of industries, including aerospace, automotive, construction, and electronics, CNC press brakes offer a powerful solution for various applications.

To learn more about the specific benefits and capabilities of CNC press brakes, explore our in-depth article, "CNC Press Brakes: A Comprehensive Guide"

Hybrid press brakes

Hybrid press brakes represent the pinnacle of press brake technology, offering significant advancements over traditional synchronized hydraulic press brakes.

VICLA, a pioneer in this field, specializes in hybrid technology, a solution that optimizes performance by combining the best aspects of different systems. This innovative approach delivers exceptional results in terms of precision, repeatability, energy efficiency, and cost-effectiveness.

VICLA's hybrid press brakes guarantee microscopic precision in beam positioning, ensuring consistent and accurate bends. This precision is achieved through a reduction in oil usage, a hallmark of VICLA's technology. For example, a 110-ton VICLA .SUPERIOR hybrid press requires only 50 liters of oil per chamber, compared to 200 liters in traditional hydraulic press brakes.

Less oil translates to fewer ducts, smaller tubing, reduced heat and expansion, and minimized clearance and wear. This efficiency is further enhanced by two powerful electric motors that operate directly on the minimal oil required.

Repeatability is another key benefit of VICLA's hybrid press brakes. By minimizing oil usage, VICLA reduces the negative effects of oil heating and expansion, which can compromise precision over time. The compact oil circuit and precise construction further contribute to consistent results.

Energy savings are a significant advantage of hybrid technology. Compared to traditional synchronized hydraulic press brakes, VICLA's hybrid machines can achieve up to 78% energy savings in standard conditions. This is made possible by a smart energy consumption philosophy that activates the machine's motors only when necessary.

In contrast to traditional hydraulic press brakes, which keep their motors running continuously, VICLA hybrid press brakes only consume energy during the actual bending process. This reduces energy costs significantly, both in the short and long term.

While hybrid technology offers a compelling cost advantage compared to electric press brakes, it also provides greater versatility. Electric press brakes, especially those using belt systems, can have limitations in bending certain shapes due to their structural design. Hybrid press brakes, on the other hand, offer the flexibility of traditional hydraulic press brakes, allowing for a wider range of applications.

Benefits of Press Brakes

• In-house efficiency: Install a press brake on-site to streamline production and reduce costs.

• Unmatched safety: Modern press brakes prioritize operator safety with features like protective curtains and laser sensors.

• Accelerated production: CNC integration automates operations, leading to significantly faster production times.

• Reduced labor: Press brakes minimize the need for manual labor, especially when equipped with CNC automation.

• Cost optimization: Faster production and reduced labor translate to substantial cost savings.

Applications of Press Brakes

• Machine tool components: Manufacture parts for various machine tools.

• Electrical components: Produce essential parts like junction boxes and enclosures.

• Automotive parts: Fabricate crucial components for vehicles.

• Construction materials: Create frames and duct parts for buildings.

Limitations of Press Brakes

• Ram locking: Improper use or pressure can cause the ram to become locked.

• Limited control: Most press brakes cannot be stopped mid-cycle.

Alternatives to Press Brakes

• Folding machines: suitable for certain applications but generally more complex and slower.
• Panel benders: ideal for thin metal sheets but significantly more expensive.

Conclusion

Press brakes are indispensable tools in any metalworking facility. VICLA offers a comprehensive range of modern electric and hydraulic press brakes designed to meet your specific needs. Contact VICLA today to find the perfect machine for your applications.