How to maintain signal stability in high-strength bending of drag chain cables?

2026-05-20 16:42:08

The reason why the robot specific drag chain cable can compromise and ensure that the signal is not lost, shaken, or drifted after millions of bends relies on the collaboration of the following four technical pillars:

Pillar 1: Scientific Setting of Minimum Bending Radius

Under dynamic conditions, the minimum bending radius of highly flexible drag chain cables is usually 5-7.5 times the outer diameter of the cable, and can be compressed to 3-4 times during static installation. Sum Wai strictly follows this principle when selecting cables, and reserves a safety margin of 10% -15% to avoid cables being in an "extreme bending" state for a long time and accelerating fatigue.

Pillar 2: Frequency coverage of shielding effectiveness

The electromagnetic environment of robot working environment is extremely complex - servo drives, frequency converters, switching power supplies, and welding equipment all generate a large amount of EMI. Unshielded or poorly shielded signal cables will pick up these noises and transmit distorted data to controllers and sensors.

The industry requires a shielding effectiveness of at least 60dB in the frequency range of 1MHz to 1GHz. High quality robot cables use a woven layer covered with aluminum foil structure to achieve 80-90dB. Sum Wai robot specific cables use a double-layer shielding of "aluminum foil+high-density tinned copper woven mesh" to achieve a shielding attenuation of ≥ 60dB in the frequency range of 30MHz-1GHz, and the encoder signal transmission error is controlled within 0.1%.

Pillar Three: Differential Twisting and Impedance Control

For high-speed real-time communication buses such as EtherCAT, Profinet, CANopen, etc., precise pitch control of differential signal line pairs is the key to ensuring stable characteristic impedance and reducing signal reflection. Sum Wai uses different twisting pitches for power lines and control/signal lines in the robot cable laying process to avoid mutual wear of different functional cores caused by vibration frequency differences during dynamic operation.

Pillar Four: Rigorous Verification of Electrical Performance

The reliability of robot cables is not "claimed", but "measured". The industry mainly follows the IEC 62890-3 (Industrial Robot Cables Part 3: Servo Robot Cables) and GB/T 39560-2020 (Robot Cables) standards, with core testing items including:

Anti torsion life test: ± 180 °/m torsion, no broken wires in the conductor and no damage to the insulation after 1 million cycles

Signal attenuation test: At 10MHz frequency, 100m attenuation ≤ 0.5dB

Shielding effectiveness test: In the frequency range of 30MHz-1GHz, the shielding effectiveness is ≥ 100dB

Surge voltage resistance test: 1.5kV AC voltage, no breakdown for 1 minute

Insulation resistance test: ≥ 100M Ω at 500VDC

In the robot cable specific standard 2PfG 2577 issued by T Ü V Rheinland in 2016, the threshold for passing the torsion test is set at least 5 million times. This number has become an internationally recognized industry benchmark, and high-end application scenarios have reached the forefront goal of 10 million or more times.