Selecting the right press brake is crucial for optimizing production, minimizing costs, and ensuring the machine meets expected returns. Making an informed decision involves evaluating several factors to match your specific needs.
1. Bending Pressure
Calculating the required bending pressure is fundamental. The formula for bending pressure is:
P = (650 S^2 L) / V
Where:
- P = Bending pressure (tons)
- S = Sheet thickness (mm)
- L = Sheet length (mm)
- V = Die opening width (mm)
For Q235 steel, the free bending pressure required is approximately 48 tons. For stainless steel, due to its higher tensile strength, the bending pressure should be multiplied by a factor of 2, resulting in approximately 96 tons.
2. Choosing the Press Brake Model
Based on the calculated bending pressure, you can select an appropriate press brake model. For a bending pressure of 96 tons, the suitable models are typically a 100-ton press brake with either a 2500mm or 3200mm bed length.
3. Selecting the Die Opening
The choice of die opening is crucial for bending quality. The selection rules are as follows:
- CNC Press Brake: V = S 6
- Conventional Press Brake: V = S 8
4. Special Requirements for Stainless Steel
Stainless steel requires adjustments due to its higher hardness. The bending pressure for stainless steel should be multiplied by a factor of 1.5. The formula for calculating the bending pressure for stainless steel is:
P = (650 (S 1.5)^2 L) / V
5. Using a Hydraulic Press Brake
Here are the general steps for using a hydraulic press brake:
1. Power On: Connect the power supply, turn on the key switch, and start the oil pump.
2. Adjust Stroke: Ensure that when the upper die descends to its lowest point, there is a gap equivalent to the thickness of the sheet.
3. Select Appropriate Die Opening: The width should typically be eight times the sheet thickness.
4. Adjust Back Gauge: Ensure accurate positioning of the sheet metal.
5. Start Bending: Depress the foot switch to begin bending, and release the switch to stop.
6. Understanding VBRS in Press Brakes
- V: Die opening width
- B: Minimum bending dimension
- R: Bending radius
- S: Bending pressure machine
7. Summary
Choosing a press brake involves a comprehensive consideration of factors such as bending pressure, material type, and bending requirements. This guide provides essential information on selecting and using a press brake, helping you to choose the right equipment for your needs.
Practical Example
To better illustrate these concepts, let's consider an example:
Problem: Bending a stainless steel sheet with a thickness of 3mm and a length of 1000mm using a die opening of 24mm.
Solution:
1. Calculate Bending Pressure for Stainless Steel:
P = (650 (3 1.5)^2 1000) / 24
P = (650 6.75^2 1000) / 24
P = (650 45.5625 1000) / 24
P = 29640625 / 24
P ≈ 1235 tons
In this scenario, you would need a press brake with a capacity of at least 1235 tons to bend the stainless steel sheet.
Detailed Steps for Use
1. Power On: After connecting the power supply and starting the oil pump, you can hear the pump operating.
2. Stroke Adjustment: Adjust the machine so that the upper die leaves a gap equal to the sheet thickness at the lowest point.
3. Die Opening Selection: Choose a die with an opening width appropriate for the sheet thickness, following the formula V = S 8.
4. Back Gauge Adjustment: Precisely adjust the back gauge to ensure the sheet is positioned correctly for bending.
5. Bending Process: Step on the foot switch to start the bending operation, and release it to stop.
Conclusion
Selecting the right press brake requires careful consideration of multiple factors, including bending pressure, machine type, die selection, and material requirements. By following the guidelines outlined in this article, you can ensure optimal performance and efficiency in your metalworking operations.
