What is the difference between CNC Press Brake Mechanical Crowning and Hydraulic Crowning?

The difference between Mechanical Crowning and Hydraulic Crowning. How to choose the right Press Brake Crowning?

Mechanical or Hydraulic Press Brake Crowning
1. The difference between Mechanical Crowning and Mechanical Crowning

——Mechanical Crowning Technology

——Hydralic Crowning Technology

2. How to choose the right Press Brake Crowning?

During the bending process, when the CNC Press Brake bends the sheet, the sheet will also have a reaction force on the machine tool. This reaction force can deform the machine, which affects the bending accuracy. Therefore, in order to improve the bending accuracy, Mechanical Crowning and Hydraulic Crowning widely use the secondary bending machine camber compensation in the sheet bending process.

The difference between Mechanical Crowning and Hydraulic Crowning

1. Mechanical Crowning technology:

A convex wedge consists of a set of convex wedges with bevels. Each protruding wedge is designed through finite element analysis based on the deflection curves of the slider and table.

The CNC controller system calculates the required compensation amount according to the load force. This force causes deflection and deformation of the slide and the vertical plate of the table. And automatically control the relative movement of the convex wedge, so as to effectively compensate the deflection and deformation of the sliding block and the vertical plate of the worktable, and obtain an ideal bending workpiece.

The actual deflection curves overlap, so that the upper and lower tool gaps are consistent during bending, and the angles in the length direction of the bending workpiece are consistent.

Mechanical convexity allows accurate deflection compensation over the full length of the table. Mechanical deflection compensation provides long-lasting stability, reduces maintenance frequency (such as oil leaks) for Hydraulic Crowning, and is maintenance-free for the life of the machine.

Mechanical deflection compensation Because there are many compensation points, the bending machine can achieve linear compensation when bending the workpiece during work, which can improve the bending effect of the workpiece. Mechanical Crowning is driven by a motor as a CNC control axis, enabling CNC control to make the compensation more accurate.

Hydraulic Crowning Technology:

The automatic hydraulic deflection compensation of the worktable consists of a group of oil cylinders installed on the lower worktable. The position and size of each compensation cylinder are designed according to the deflection compensation curve of the slider and the finite element analysis of the worktable.

The hydraulic pressure is to realize the convex compensation of the neutral version through the relative displacement between the front, middle and rear vertical plates. The principle is to realize the bulge through the elastic deformation of the steel plate itself, so the compensation amount can be adjusted within the elastic range of the workbench.

2. How to choose the right Press Brake Crowning?

Since the two compensation methods of CNC Press Brake have different requirements for operators and product accuracy, it is very important to choose the correct bending compensation.

Hydraulic Crowning uses small cylinders to compensate the workbench, and Mechanical Crowning uses wedges to compensate the workbench. The wedge block can be divided into single wedge block and multiple groups of wedge block. Mechanical Crowning composed of multiple sets of wedge blocks has more compensation points, more than 3 compensation points of ordinary Hydraulic Crowning, there is no compensation blind area, the precision of the folded workpiece is high, and the difference between each processing plate is small, which is suitable for mass production.

CNC Control Hydraulic Crowning: We set the bending parameters in the CNC controller, such as plate thickness, plate length, material. The CNC controller automatically calculates the required compensation value, and then transmits the command to the compensation amplifier. The compensation amplifier sends the signal to the Hydraulic Crowning proportional valve, which controls the small cylinder under the table to bulge to reduce the deflection of the sheet.

However, the Hydraulic Crowning value is affected by various factors, such as whether the hydraulic oil leaks, whether the joint is loose, etc., which will affect the amount of Hydraulic Crowning each time, resulting in inconsistencies and differences in the processing of each plate. time.

The hydraulic system is more complex, and there may be problems such as oil leakage and loose sealing rings. The advantage of hydraulics is that the machine does not suffer from wear issues over time as Mechanical Crowning does.

Compared with Mechanical Crowning, Hydraulic Crowning’s machine is easy to operate, so it can help with higher bending accuracy. In addition, the machine has higher durability.

Hydraulic Crowning uses a small cylinder compensation table, and Mechanical Crowning uses a wedge compensation table. Wedges can be further divided into single wedges and multi-group wedges.

Mechanical Crowning with multiple sets of wedges has more compensation points than Hydraulic Crowning. Ordinary Hydraulic Crowning has only 3 compensation points, no compensation blind area, higher precision of folding workpieces, and small plates per processing, which is suitable for mass production.

Compared with the Hydraulic Crowning system, the Mechanical Crowning system is simpler, does not cause oil leakage, has a low failure rate, and is environmentally friendly.

However, after long-term use, the mechanical convex wedge will wear and affect the compensation effect. Mechanical Crowning places higher demands on the operation. If the workpiece needs to be bent in multiple steps, workers need to make real-time adjustments.

If the workpiece only needs to be bent in one step, our workers are highly skilled. We can choose Mechanical Crowning from the perspective of workpiece accuracy. In actual production, we have to consider the ability of workers, the cost of high-skilled workers, etc.