The unbalanced load and uneven distribution of the B2SH gearbox are mostly caused by installation errors, structural stress deformation, poor lubrication conditions and parts manufacturing accuracy deviations. The most effective rectification idea is to simultaneously optimize the bearing preload state, tooth surface meshing morphology, and overall machine system stiffness, and strictly ensure the installation coaxiality accuracy to achieve uniform distribution of tooth width loads. The specific adjustment methods are as follows:
1. Optimize bearing preload status and improve load distribution
The amount of bearing preload directly determines the rigidity of the shaft system and the accuracy of gear mesh alignment, and is the core factor for uniform load distribution.
Detect the amount of bearing movement: Use a dial indicator and a magnetic gauge base to gently push the shaft end to measure the axial movement value. The standard control range is 0.01–0.03mm. Repeat the measurement 2 to 3 times to ensure that the data is accurate and stable.
Preload adjustment: Control the preload size by increasing or decreasing the thickness of the gasket or turning the lock nut. Excessive preload will easily cause high temperature and early wear of the bearing; too small preload will cause shaft movement and gear eccentric load.
Measurement precautions: Ensure that the shaft end is clean and the meter base is vertically fitted to avoid measurement errors caused by external disturbance.
2. Improve installation accuracy and eliminate unbalanced loads caused by assembly deviations
Assembly errors are the main external cause of uneven load on gearboxes.
Strictly control coaxiality and parallelism: the coaxiality error at the docking position of the input and output shafts must be ≤0.05mm/100mm, and a laser alignment instrument is used for precise correction to eliminate meshing deflection and local tooth surface overload problems.
Reinforce the foundation and anchor structure: The anchor bolts are evenly locked in a diagonal cross sequence to ensure that the pre-tightening torque reaches the standard and avoid equipment vibration and box displacement. The installation base must be flat and stable to prevent foundation deformation from causing misalignment of the shaft system.
3. Implement tooth surface modification and drum design to compensate for stress deformation
Part manufacturing errors, operating elasticity, and thermal deformation will cause the gear contact area to shift, which can be optimized through active modification:
Tooth top trimming and tooth direction modification: perform slight trimming on the tooth top and tooth end to compensate for the meshing offset caused by thermal deformation and elastic deformation, and improve the gear contact accuracy to ISO level 6.
Optimization of drum-shaped teeth: a convex design is made in the middle of the tooth width direction to eliminate stress concentration on the tooth edge and allow the load to be evenly distributed along the tooth width. At the same time, the bearing span is reasonably planned to reduce gear deflection and improve support rigidity.
4. Strengthen the overall stiffness of the system and reduce deformation deflection
Improving the structural rigidity of the entire machine can significantly reduce load deflection caused by load deformation.
Optimized material selection: The gears are made of 20CrNi2MoA carburized steel, with a surface hardness up to HRC58–62, taking into account high hardness and core toughness, and excellent fatigue resistance; the box is made of HT300 cast iron, with optimized rib structure, and the overall rigidity is 18% higher than that of ordinary boxes.
Improve the stiffness of the shaft system and bearings: Use tapered roller bearings or double-row cylindrical roller bearings to enhance the shaft system"s resistance to deformation; the heat treatment hardness of the spindle is controlled at HRC48–55 to avoid deformation and instability of the shaft system during load operation.
