Press brakes are essential machines in the metalworking industry, designed to bend and shape metal sheets with high precision. There are various types of press brakes, each employing different mechanisms to achieve the desired bend. Among these, electro-hydraulic servo press brakes and torsion bar press brakes are widely used. This article will delve into the key differences between these two types, their structure, and their applications.
Understanding Electro-Hydraulic Servo Press Brakes
Electro-hydraulic servo press brakes utilize a closed-loop control system involving main oil cylinders, proportional electro-hydraulic servo valves, and a grating ruler to ensure precise synchronization and operation. The CNC system independently controls each side, allowing for highly accurate data feedback, which in turn guarantees the precision of the slider movement.
Key Components and Mechanisms
- Hydraulic Management System: The hydraulic system provides the necessary power for the press brake. It includes main oil cylinders on both sides of the machine that are synchronized by proportional electro-hydraulic servo valves.
- Closed-Loop Control: This system uses a grating ruler for feedback, creating a closed-loop that continuously monitors and adjusts the position of the slider for precise movement.
- CNC Control: Each side of the press brake is controlled by an independent CNC system, which ensures high precision and repeatability.
Advantages of Electro-Hydraulic Servo Press Brakes
1. High Precision: The closed-loop control system allows for highly accurate positioning, ensuring consistent and precise bending operations.
2. Flexibility: CNC control systems can store multiple bending programs, making it easy to switch between different operations.
3. Efficiency: Faster setup times and high repeatability reduce downtime and increase productivity.
Understanding Torsion Bar Press Brakes
Torsion bar press brakes rely on a mechanical system involving a torsion shaft and connecting rods to synchronize the movement of the left and right oil cylinders. This mechanical synchronization ensures that both sides of the machine move uniformly, maintaining the balance and symmetry of the bend.
Key Components and Mechanisms
- Torsion Shaft: A central torsion shaft connects to the left and right oil cylinders, ensuring synchronized movement.
- Connecting Rods: These rods link the torsion shaft to the bending mechanism, translating the shaft's torsional force into uniform movement on both sides of the press brake.
Advantages of Torsion Bar Press Brakes
1. Mechanical Simplicity: The torsion bar system is mechanically straightforward, making it easier to maintain and repair.
2. Cost-Effective: Generally, torsion bar press brakes are less expensive than their electro-hydraulic counterparts.
3. Reliability: The mechanical synchronization system is robust and reliable for many bending applications.
Cost of Steel Plate Bending
The cost of bending steel plates varies based on several factors, including the thickness and size of the steel, the complexity of the bend, and the type of press brake used. Typically, hydraulic press brakes are more expensive due to their advanced control systems and precision capabilities.
Structural Components of Press Brakes
Press brakes are primarily composed of three critical parts: the left and right columns, the workbench, and the slider. These components constitute 70% to 80% of the total weight of the machine, directly influencing its operational precision, lifespan, and the accuracy of the workpieces produced.
- Left and Right Columns: These vertical structures support the machine and house the oil cylinders.
- Workbench: The fixed lower die is mounted on the workbench, while the upper die is attached to the slider.
- Slider: Connected to the pistons of the oil cylinders, the slider moves up and down to press the upper die against the lower die, bending the metal sheet.
Classification of Press Brakes
Press brakes are classified into manual, hydraulic, and CNC types. Manual press brakes are further divided into mechanical and electric manual press brakes. Hydraulic press brakes are categorized based on their synchronization method, including torsion bar synchronization, hydraulic synchronization, and electro-hydraulic synchronization. Additionally, hydraulic press brakes can be classified by their movement mode, such as top-moving and bottom-moving types.
Electro-Hydraulic Press Brake Speed Control Loop
The speed control loop in an electro-hydraulic press brake manages the motor speed. This loop consists of a speed control unit, a servo motor, and a speed detection device. The speed control unit is crucial as it adjusts the motor speed to ensure the precise movement of the press brake's slider.
FAQs
What is the primary difference between electro-hydraulic servo press brakes and torsion bar press brakes?
Electro-hydraulic servo press brakes use a closed-loop system with independent CNC control for high precision, while torsion bar press brakes rely on a mechanical synchronization system involving a torsion shaft and connecting rods.
How does a closed-loop control system enhance the accuracy of a press brake?
A closed-loop control system continuously monitors and adjusts the slider's position using feedback from a grating ruler, ensuring precise and consistent movement.
What are the cost implications of using hydraulic press brakes compared to torsion bar press brakes?
Hydraulic press brakes, particularly electro-hydraulic servo types, are generally more expensive due to their advanced control systems and higher precision capabilities.
Why is the structural integrity of the columns, workbench, and slider crucial in press brakes?
The strength and rigidity of these components directly affect the machine's operational precision, lifespan, and the accuracy of the bent workpieces.
How do CNC systems improve the functionality of electro-hydraulic servo press brakes?
CNC systems allow for the storage and retrieval of multiple bending programs, facilitating quick setup changes and high repeatability in bending operations.
What are the advantages of using a torsion bar synchronization system in press brakes?
Torsion bar synchronization systems are mechanically simple, cost-effective, and reliable, making them suitable for many bending applications.
Conclusion
Both electro-hydraulic servo press brakes and torsion bar press brakes have their unique advantages and are suited for different applications in the metalworking industry. Electro-hydraulic servo press brakes offer high precision and flexibility with advanced CNC controls, while torsion bar press brakes provide mechanical simplicity and cost-effectiveness. Understanding the differences between these two types of press brakes can help in selecting the appropriate machine for specific bending tasks.
