Belt-Driven Linear Guides for Long-Stroke Conveyance: Minimizing Belt Stretch and Resonance
Belt-driven linear modules with steel-cord PU timing belts suffer elastic elongation and structural resonance when travel length exceeds 3000 mm. Uncontrolled tension causes 0.5% permanent creep after 1000 operation hours, raising positioning error to ±0.08 mm. This article outlines mechanical design and tension calibration methods to limit stretch below 0.1% and eliminate span resonance for servo positioning axes.
Creep & Permanent Set Control
- Polyurethane belt body produces permanent creep under continuous tension. Standard polyester cord belts reach 0.5% elongation after 1000 hours; steel reinforcement cords reduce permanent set down to ≤0.1% over 10,000 hours continuous duty.
- Download Detailed 3D CAD (.STEP) Models for Heavy-load Linear Drive & Long-travel Guide Rail System to run tension simulation before mechanical fabrication.
Setting Tension with Acoustic Frequency Meters to Avoid Premature Tooth Wear
- Isolate power and lock out the linear axis; input belt mass, width and free span length into the sonic tension meter.
- Pluck the midpoint of the belt span to generate free vibration; collect the natural frequency (Hz) via acoustic probe, 10~680Hz measurement range.
- Convert frequency value into static tension force; adjust tension bolts until the reading reaches the calculated target value.
- Re-test tension after 30 minutes of running-in; re-tighten to compensate initial tension loss.
| Parameter | HTD Curvilinear Profile | AT Trapezoidal Profile |
|---|---|---|
| Backlash | 0.03~0.05 mm (large clearance) | ≤0.015 mm (minimal tooth clearance) |
| Max Torque Transfer | High, gradual tooth meshing | 30% higher load capacity than HTD of same pitch |
| Tooth Wear Rate | Low impact noise, moderate wear | Higher meshing impact, longer service life under high cyclic load |
| Repeatability | ±0.03~0.05 mm | ±0.008~0.02 mm |
| Recommended Application | High-speed conveyance, low positioning requirement | Servo pick-and-place, relay assembly indexing axis |
