The settlement and cracking of the base of the NGW-L11-5.6 planetary reducer is generally caused by inadequate base material selection, construction technology, installation accuracy, and daily maintenance and control. It will cause shafting coaxiality deviation, increase equipment vibration, accelerate the loss of transmission components, and affect the stable operation and service life of the entire machine. To effectively prevent foundation settlement and cracking, it is necessary to implement management and control throughout the entire process of foundation design, construction, installation and commissioning, and operation and maintenance monitoring. Specific measures are as follows:
1. Base design and construction stage
Material selection
The concrete grade of the concrete base shall not be lower than C20, and the thickness of the base shall be ≥200mm. After the pouring is completed, maintenance should be carried out. The maintenance should be no less than 7 days in summer and no less than 14 days in winter. The surface of the base should be subjected to secondary calendering, and the surface roughness Ra≤6.3μm. The steel structure base is recommended to use Q235B steel plate with a thickness of ≥16mm. After welding, stress relief treatment is performed. The top surface of the base is milled and leveled, and the plane accuracy is ≤0.05mm/m.
Subsidence prevention and control
The soil layer of the base foundation must be compacted or laid with gravel cushion to prevent uneven settlement caused by insufficient foundation bearing capacity. Under heavy load conditions, settlement observation points are pre-embedded in the base to continuously monitor settlement changes. The allowable settlement deviation is ≤0.1mm/m.
2. Installation and debugging stage
Flatness control
A laser level with an accuracy of 0.02mm/m is used to detect the flatness of the base in a grid. The flatness error is ≤0.1mm/m in the reference state; high-precision working conditions require the error to be controlled within 0.05mm/m. Use adjustable gaskets with specifications of 0.1mm, 0.2mm, and 0.5mm to compensate for the low-lying position of the base. The number of gaskets in each group shall not exceed 3 pieces, and the total thickness of the gaskets shall be ≥ 20mm.
Bolt tightening requirements
The anchor bolts are tightened in three steps in a diagonal sequence: initially to 50% of the rated torque, then to 80% of the rated torque, and finally to 100% of the rated torque to avoid deformation of the base caused by force on one side.
3. Long-term maintenance and monitoring
Regular inspection
Retest the torque of the anchor bolts every 3 months to prevent loosening of the bolts and movement of the base. Use a laser alignment instrument to verify the coaxiality of the shaft system every year. The coaxiality error is ≤0.03mm/m to avoid fatigue damage to the base caused by the continued effect of eccentric loads.
Exception handling
Once base settlement or cracking defects are found, the concrete base can be repaired by regrouting; the steel structure base can be processed by top surface milling. When the settlement exceeds the allowable range, the correction base can be raised with the help of a jack, and then epoxy resin grouting material can be poured to complete the fine adjustment.
4. Key things to note
After the equipment runs without load for 2 hours, retest the flatness of the base. At this time, the allowable deviation can be relaxed to 1.2 times the original standard, that is, ≤0.12mm/m. After the base adjustment is completed, review the coaxiality of the input and output shafts of the reducer and the supporting load equipment. The coaxiality error is ≤0.03mm/m.
Implementing the above complete set of control measures can effectively reduce the risk of base settlement and cracking and extend the service life of the planetary reducer.
