How to Fine-Tune Your Press Brake Stroke: Failure Analysis and Disposal Method | MachineMFG

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How to Fine-Tune Your Press Brake Stroke: Failure Analysis and Disposal Method


When manually adjusting the stroke of a WC67Y30T-1600 hydraulic bending machine, it is important to ensure that the hand wheel on the worm drive is not idle. Failure to do so will result in an inability to adjust the ram stroke, which will prevent the sheet metal from being processed according to the designed bending angle.

Manually Fine-Tuning Of The Press Brake Stroke (Failure Analysis & Disposal Method)

1. The composition and working principle of the ram stroke part.

The ram stroke mechanism comprises a ram, a hydraulic cylinder, a worm drive, and a screw drive.

The left and right hydraulic cylinders are fixed to the frame.

One end of the screw is connected to the worm gear, and the other end is linked to the adjusting nut positioned in the middle of the piston, which is integrated with the hydraulic cylinder.

The working principle of the ram stroke mechanism involves hydraulic transmission, enabling the piston to move the ram up and down.

To fine-tune the working stroke of the hydraulic cylinder, the stroke fine-tuning mechanism employs worm gear transmission, which drives the screw shaft and adjusting nut to move relative to the axial direction of the screw.

During the sheet metal bending process, the ram can move up and down slightly to alter the bending gap between the upper and lower dies of the bending machine, satisfying the working requirements of different bending angles for the sheet metal.

2. Fault cause analysis and emergency disposal method

(1) Check the hydraulic system

To check the hydraulic system, first, turn on the power and press the start switch on the control panel to verify whether the pressure gauge indicates normal readings.

Next, press the down switch to ensure that the ram drops quickly and smoothly as expected.

Then, press the down switch again to verify if the operation is normal.

Finally, press the up switch to confirm that the ram rises quickly and smoothly.

By conducting these checks, we can conclude that there are no faults in the hydraulic transmission system.

(2) Check the mechanical drive

Inspect the hydraulic cylinder in order of increasing difficulty, following the principle of starting with the easiest task and progressing to the most challenging one.

① Remove the outer part of the hydraulic cylinder.

To check for faults in the worm drive, first, remove the upper cover and worm part. Then, inspect the outer surface of both the worm and worm gear for signs of wear or other abnormalities during rotation. If there are no such issues and the rotation appears normal, it indicates that the worm drive is functioning correctly.

② Remove the inner part of the hydraulic cylinder.

First, remove the piston, screw, and nut, and then check the threads of the screw and nut for any signs of wear.

If wear is detected, the clearance of the screw pair may be too large, resulting in an air return error where the screw changes direction but the nut does not move.

Clearly, the wear of the screw and nut in the screw drive is the reason why the ram stroke cannot be finely tuned.

(3) The emergency disposal method

Acquiring new screws and nuts has become a challenging task due to the lack of recognition of the equipment brand within the industry. This raises the question of whether it is worth scrapping the equipment that costs tens of thousands of dollars.

After conducting multiple analyses and tests, the author has discovered an emergency solution to fix this issue, enabling the equipment to continue operating.

The author has identified the primary theoretical basis for fixing the issue by examining the internal structure of the hydraulic cylinder. The principle of eliminating the air return error is to eliminate clearance. By using hydraulic transmission to drive the piston upward, the axial force of the oil in the piston can decrease the clearance between the nut and screw. Thus, compensating for the clearance caused by wear and tear.

The specific disposal methods are as follows:

To start the process, press the down switch which activates the hydraulic transmission and makes the ram quickly drop to its lowest point.

Next, press the up switch to make the ram rise about 3mm (Note: the rise should not be too high, just move upward slightly).

In the third step, try turning the hand wheel. If it feels a little tight and does not turn smoothly, it indicates that the ram stroke can be adjusted manually.

Once you have conducted a test with small pieces of sheet metal, you can adjust the bending angle of the sheet metal to the desired level, and production can resume as normal.

3. Conclusion

After being used for over a year, it has been proven that the emergency disposal method mentioned above is an effective solution to fine-tune the ram stroke. It is simple, practical, and efficient.

By employing this emergency method, not only can the equipment continue to function, but it can also self-manage without incurring any maintenance costs.

Furthermore, this method can serve as an emergency solution for other press brake brands without requiring any parts replacement or after-sales service.

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