A systematic solution for CNC double-spindle resonance
Youdaoplaceholder0 I. Resonance root cause diagnosis
Youdaoplaceholder0 mechanical level
Main shaft dynamic balance failure : vibration is caused by centrifugal force during high-speed rotation (such as when the main shaft speed exceeds the first-order critical speed and enters a flexible state).
Youdaoplaceholder0 drive chain failure : belt looseness, large coupling error or bearing wear causing periodic impact.
Youdaoplaceholder0 Insufficient structural rigidity : unreasonable setting of the distance between the two spindles, loose base or deviation of the verticality of the column (affecting G4 accuracy).
Youdaoplaceholder0 electrical level
Servo parameter mismatch : the gain of the position loop/speed loop is too high or too low, causing low-frequency vibration (e.g., PG=100/S→16Hz vibration).
Youdaoplaceholder0 Electromagnetic interference : power phase loss, driver regeneration circuit failure or encoder signal interference.
Youdaoplaceholder0 process level
Youdaoplaceholder0 Improper cutting parameters : The fluctuation of cutting force coincides with the natural frequency of the spindle (for example, the self-excited vibration frequency of a milling machine at 35-55Hz is prone to resonance with the driving force).
Youdaoplaceholder0 tool system imbalance : unbalanced movement of the tool holder or eccentric clamping of the tool.
Youdaoplaceholder0 2. Innovative inhibition strategies
Youdaoplaceholder0 dynamic parameter adaptive adjustment
Vibration prediction model : By real-time collection of data such as spindle speed, cutting force, and vibration spectrum through sensors, the network predicts resonance risk and automatically adjusts servo gain (such as reducing the speed loop gain to the vibration disappearance point).
Youdaoplaceholder0 Case : An aviation parts processing factory adopted a system, and the model reduced the scrap rate caused by resonance from 12% to 2%.
Youdaoplaceholder0 Virtual debugging : During the NC code generation stage, the dual-spindle machining process is simulated through digital twins to identify the resonance frequency band and optimize the tool path (such as avoiding the 35-55Hz self-excited vibration range).
Youdaoplaceholder0 intelligent active damping control
Youdaoplaceholder0 HRV filter upgrade : For high-frequency resonance (>200Hz), the resonance point is dynamically identified through AI algorithm and the HRV2 function is activated to suppress vibration in real time (servo software version ≥90B0 is required).
Youdaoplaceholder0 Mechanical speed feedback enhancement : In a fully closed-loop system, the position feedback error between the mechanical side and the motor side is analyzed, and the mechanical speed feedback gain (parameter 2088) is automatically adjusted to reduce vibration by approximately 50Hz.
Youdaoplaceholder0 III. Traditional mechanical optimization methods
Youdaoplaceholder0 dynamic balance correction of the main shaft
On-site correction of the double spindles was carried out using a laser dynamic balancing instrument to ensure that the unbalance was ≤0.5g·mm/kg (ISO 1940-1 standard).
Youdaoplaceholder0 Case : A certain automotive drive shaft processing line reduced the vibration amplitude of the main shaft from 0.1mm to 0.02mm through dynamic balance correction.
The rigidity of the transmission chain is enhanced by
Replace high-precision couplings (such as diaphragm couplings) to keep the radial error within ±0.01mm.
Adjust the belt tension to the manufacturer's recommended value (such as ±5% of the measurement value of the Gates synchronous belt tensiometer).
Youdaoplaceholder0 Structural reinforcement and vibration isolation
Install anti-vibration pads (such as rubber-metal composite vibration isolators) between the double spindle bases to reduce the transmission of environmental vibration (such as foundation vibration when nearby heavy equipment is in operation).
Optimize the column design, adopt light steel structure or corrugated plate reinforcing ribs (with large moment of inertia and small centroid moment), and increase the natural frequency to above 66Hz (avoiding the frequency range of the milling machine's driving force).
Youdaoplaceholder0 IV. Action suggestions
Youdaoplaceholder0 Prioritize the investigation of electrical parameters : Observe the vibration spectrum through the servo adjustment screen to confirm whether it is due to servo gain mismatch or high-frequency resonance.
Youdaoplaceholder0 step-by-step verification of mechanical status :
Manually rotate the main shaft to check the preload of the bearings and the meshing clearance of the gears.
The parallelism of the two main shaft axes was measured using a laser interferometer (error ≤0.01mm/1000mm).
Rapid deployment of : vibration prediction model; If mechanical adjustment is the main approach, the parameter setting process in the [Machine Tool Vibration Suppression Technology Manual] can be referred to.
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