Understanding Upstroke and Downstroke Press Brakes: Differences and Applications

 What are Downstroke Press Brakes?

Downstroke press brakes, often referred to simply as "press brakes," are machines used in metalworking and fabrication processes to bend sheet metal and other materials. It uses a downward force to shape the workpiece.

Here's how they work:

 

1. Frame and Bed: The machine has strong frames and a flatbed. It is the place where the material is laid for bending purposes.  

 

2. Upper Beam (Ram): It is the moving part of the press brake resting above the bed. It exerts a downward force on the workpiece to bend it.

 

3. Tooling: It is the component of the Downstroke Press Brake machine to shape the material. It typically includes a punch and die. The configuration and shape of the punch and die influence the bend angle and the final shape of the workpiece.

 

4. Hydraulics or Mechanical Power: Press brakes are of two types: hydraulic or mechanical. Hydraulic type uses a hydraulic cylinder to generate the downward force, while mechanical press brakes depend on mechanical mechanisms like flywheel and crankshaft.

 

5. Control System: Modern press brakes often feature CNC(computer numerical control) systems for precise control of the bending process. CNC press brakes allow operators to input parameters such as bend angle, bend length, and material thickness, resulting in accurate and repeatable bends.

 

Press brakes are commonly used in industries such as automotive, aerospace, construction, and manufacturing, where sheet metal bending is a critical part of the production process.

 

What are Upstroke Press Brakes?

Upstroke Press Brakes are traditional press brakes that are not commonly seen nowadays. However, Upstroke Press Brakes are a type of press brake where the bending force is applied from the bottom upward.

In the hypothetical scenario:

 

1. Frame and Bed: Similar to traditional press brakes, an up-press brake would have a sturdy frame and a flatbed where the material to be bent is placed.

 

2. Lower Beam (Ram): Instead of the upper beam being the moving part, in an up-press brake, the lower beam (or ram) would move upwards to apply force onto the workpiece.

 

3. Tooling: Tooling would still be used to shape the material. The punch would typically be attached to the lower beam, while the die would be mounted onto the upper part of the machine.

 

4. Power Source: The up press brake could be powered hydraulically or mechanically, similar to traditional press brakes.

 

5. Control System: Like modern press brakes, Upstroke Press Brakes could also feature CNC systems for precise control over the bending process.

 

Advantages of  Downstroke Press Brakes:

 

• Part stays fixed during the approach process
• Most common Design
• Available in all tonnages

 

Disadvantage of Downstroke Press Brakes:

 

• Ram can Drop during a power outage creating an unsafe environment.
• Ram must commonly be “blocked” at night to take pressure off of the hydraulic system.
• Design Necessities need for “crowning” devices.

 

Advantage Upstroke Press Brakes:

 

• Hydraulically driven from the center of the ram reduces the need for crowning devices
• Hydraulics are located down low so maintenance is easier.
• Machine height is typically shorter for low clearance needs.

 

Disadvantages Upstroke Press Brakes:

 

• Part moves during the approach process require careful handling to keep on gauge points.
• Bending Tonnage is limited (typically 35-150 Tons Max).
• The machine is typically slower on approach speeds
• Bending must be performed only in the middle of the ram
• Less common design.

 

Accurpress, Amada, Bystronic, Cincinnati, Durma, Ermaksan, Hydropower, LVD, Pacific, Standard-Industrial, Trumpf, and others are the leading manufacturers of Downstroke Press Brakes.

 

World Machinery is the licensed supplier of press brakes having a range of machines from various manufacturers including GBHM Press Brakes 

Call us today at 01746 780154 .