What are the problems with abnormal noise from the transmission gears of a rotary drum granulator?
Abnormal noise from the transmission gears of a rotary drum granulator usually manifests as a periodic impact sound or a sharp friction sound when the large and small gears mesh. Based on industry maintenance experience, this problem is mainly caused by the following four categories:
Abnormal Gear Meshing Parameters
Improper gear clearance (including deviations of the tooth tip clearance and tooth flank clearance from the standard values) is the most common cause of abnormal noise. When the clearance is too large, the gear meshing produces an impact, producing a “clunking” impact sound; when the clearance is too small, the tooth surfaces squeeze and rub, producing a sharp whistling sound. In addition, foundation settlement can cause changes in the center distance between the two gears, disrupting the original meshing relationship.
Tooth Surface Wear
After long-term operation, pitting, wear, or fatigue spalling may occur on the tooth surface, resulting in poor contact during meshing and producing periodic abnormal noise. If only one gear is replaced, insufficient break-in between the old and new gears can also produce noise. When the pinion is severely worn on one side, try reversing its installation. If both sides are worn, replace the pinion.
Insufficient Lubrication: Insufficient lubrication on the gear surface leads to direct dry friction between the metal teeth, producing a sharp metallic friction sound.
Installation Accuracy Issues: Misalignment of the steel structure used to install the gear, or deformation of the steel structure causing excessive local stress on the gear contact surface, can cause abnormal noise and impact. The deviation between the pinion shaft centerline and the main body centerline should not exceed 0.15mm per meter.
Solutions: Immediately stop the machine and inspect for any abnormal noise, checking each of the above causes one by one. First, check the tip clearance and flank clearance, adjusting the pinion position to ensure the meshing clearance meets standards. Second, check the gear lubrication sump to ensure sufficient oil level and clean oil. If foundation settlement causes a change in center distance, readjust the cylinder height. For severely worn gears, replace the entire gear pair.
How often should grease be added? The lubrication cycle of a rotary drum granulator varies depending on the components, as follows:
| Lubrication Position | Lubrication Cycle | Lubricant Type |
|---|---|---|
| Open Transmission Gears (Big and Small Gears) | Once every quarter (3 months) | Special Equipment Grease / Three-in-one Grease |
| Bearing Seat | Apply or renew grease every 3 months | Dry Grease |
| Bearing Housing (During Normal Operation) | Add grease every 5 to 6 days | Yellow Dry Grease |
| Roller Belt Surface | Coat dry grease every 7 days | Dry Grease |
| Reducer | Fill gear oil before startup, then replace every 4 months | Gear Oil |
| Worm Gear Box and Bearings | Full cleaning and complete lubricant replacement after 1 year of use | Transmission Grease |
For gear transmission parts, ensure sufficient lubricating oil on the gear surfaces. This can be achieved through periodic dripping or oil bath lubrication. If the equipment is used frequently, the bearing lubrication cycle can be shortened to once every 1-2 days; if used infrequently, it can be extended to once a week.
Comprehensive Recommendation: Establish a lubrication record log and strictly adhere to the recommended cycles. Apply dry grease to the gears before starting the machine; if any abnormal gear response is observed during operation, immediately stop the machine for inspection. During annual overhaul, thoroughly clean the gearbox and replace all protective lubricant.
