How to properly solve the problem of abnormal vibration in a pipe bending machine

When the pipe bending machine starts shaking, it becomes unusable. Fish-scale patterns appear on the pipe surface, the angle fluctuates wildly, and the bearings and guide rails suffer damage—you might think it's due to outdated equipment, but often it's just a few small problems that went undetected. Don't rush to adjust the parameters; check the following steps in order, and in most cases, the problem will be solved.

I. First, check if the machine is stable.

If the anchor bolts are loose, the machine will wobble, and the bending arm will shake. Use a level to check if the machine body is level. If the equipment has been moved recently or the ground has been modified, pay extra attention to this. Tighten the anchor bolts to the standard with a torque wrench; placing rubber shock-absorbing pads underneath will improve the effect.

II. Listen to the oil pump.

Air ingress into the hydraulic system is the most common source of vibration. If the oil level is too low or the suction pipe joint is loose, the pump will suck in air, causing the pressure gauge needle to swing back and forth, and the bending arm to tremble. Listen for a hissing sound from the oil pump sucking in air, and check for foam in the oil level window. Fill the oil tank to the mark, open the vent valve on top of the cylinder, and repeatedly increase and decrease the pressure several times to purge the air. Also, check if the suction pipe joint is loose.

III. Check if the die clearance is appropriate.

If the clearance between the anti-wrinkle die and the bending die is too large, the inner side of the pipe will "clunk" and create an impact when bending. Try inserting an A4 sheet of paper—if it goes in but with some resistance, it's about right. If the gap is so large that the paper slides through easily, then it's too big. After adjusting, try bending one to see the effect.

IV. Check if the speed is too high

If the speed is set too high, the material deformation cannot keep up, and the bending arm will jerk like a brake. Try reducing the bending speed to 30%-50% of the rated value. If the vibration disappears, then it's a speed issue. Small radius bending especially needs to be slow; going too fast not only causes shaking but also makes the pipe prone to wrinkling.

V. Check for loose connections

Pipe bending machines vibrate daily, so bolts will eventually loosen. The locking nuts on the bending arm spindle, the key connections between gears and shafts, the lead screw coupling, and the die fixing bolts—these are all key suspects. After stopping the machine, use a wrench to check all the fasteners, especially the encoder coupling; if that's loose, the angle will be unstable, and adjusting the program won't help.

VI. Check if the mandrel is being forcibly ground

If the mandrel ball end is stuck or protrudes too much, it will be pressing against the inner wall of the pipe, causing periodic frictional vibration during bending. Check if the mandrel joint can rotate freely. Adjust the extension to 0.5-1.5mm before the tangent point and apply more bending lubricant. Rotate the mandrel by hand to feel for any sticking or uneven resistance.

VII. Confirm if the oil pump and motor themselves are faulty.

Sometimes the problem isn't with the bending arm, but with the power source itself vibrating. Run the oil pump alone without bending the tube, and listen for any "clunking" metallic sounds from the pump and any abnormal humming sounds from the motor. If the power unit itself is vibrating, changing the mold won't help. Use a stethoscope or screwdriver to listen to the pump housing; abnormal bearing noise is easy to identify.

Recommended troubleshooting order: External to internal, simple to complex

Don't start disassembling immediately. First, check the anchor bolts and mounting surfaces, then vent the hydraulic system, next check the mold clearances and lubrication, and finally the mechanical connections and mandrel. Following this order will help pinpoint the root cause of most vibration problems.

Vibration issues, if left unresolved, will eventually require replacing gears and bearings. Spend half an hour checking it today to save money on major replacements tomorrow. Have you ever encountered a particularly difficult vibration problem? Feel free to share how you solved it.