Ensuring the coaxiality between customized non-standard bearing seats and standard bearing seats after installation requires strict control from multiple aspects such as design, processing, assembly, and testing. The following are specific methods and key points:

1、 Coaxiality control during the design phase

1. Principle of Uniform Standards

Design basis: The non-standard bearing seat and the standard bearing seat need to use the same reference system (such as equipment centerline, bottom or end face) to ensure that the coaxiality tolerance reference indicated on the drawing is consistent.

Tolerance matching:

The tolerances of standard bearing seats (such as aperture and installation surface flatness) are known, and the corresponding dimensional tolerances of non-standard bearing seats need to be designed according to their accuracy levels to ensure that the fit clearance or interference fit meets the requirements.

For example, if the standard bearing seat aperture is Φ 100H7, the matching aperture of non-standard bearing seats also needs to be designed with the same accuracy to avoid the accumulation of matching errors.

2. Structural rigidity optimization

Non standard bearing seats need to be reinforced with ribs or optimized for wall thickness to avoid deformation after installation due to insufficient stiffness, which may affect coaxiality (such as cantilever bearing seats, special attention should be paid to the support structure).

The installation base is designed as a monolithic structure (rather than separate splicing) to reduce the risk of deformation at assembly joints.

2、 Precision control during the processing stage

1. Processing requirements for critical dimensions

Aperture accuracy: The bearing installation hole needs to be precision machined using a boring machine to ensure roundness and cylindricity tolerances (such as ≤ 0.005mm), and surface roughness Ra ≤ 1.6 μ m.

Flatness of installation surface: The bottom surface of the bearing seat or flange installation surface needs to be machined by a grinder, with a flatness tolerance of ≤ 0.02mm/m, to ensure a tight fit with the equipment base during installation and avoid warping.

Center height consistency: The center height (distance from the hole center to the bottom) of non-standard bearing seats and standard bearing seats must be strictly consistent, with a tolerance controlled within ± 0.05mm.

2. Coaxiality machining inspection

After processing, use a coordinate measuring machine (CMM) for inspection:

Measure the coaxiality of the bearing seat holes (e.g. coaxiality of each hole in a multi span bearing seat ≤ 0.01mm).

Compare the testing data of non-standard and standard bearing seats to ensure that the hole position deviation between the two is within the allowable range (such as ≤ 0.02mm).

3、 Coaxiality assurance during the assembly phase

1. Calibration of installation benchmark

Leveling of equipment base: Use a level to adjust the levelness of the equipment base (≤ 0.05mm/m) as the reference plane for installing the bearing seat.

Reference hole positioning: Using the standard bearing seat as a reference, determine the centerline through a core shaft (inspection rod) or laser collimator, and then install the non-standard bearing seat. Specific steps:

Fix the standard bearing seat on the base and insert it into the core shaft (with a diameter consistent with the inner diameter of the bearing).

Align the laser collimator with the centerline of the core axis as the assembly reference.

Adjust the position of the non-standard bearing seat so that the core shaft can smoothly penetrate its bearing hole and the radial clearance is uniform (error ≤ 0.02mm).

2. Pre tightening force control of bolts

The installation bolts need to be tightened in symmetrical order in stages (such as using diagonal tightening method) to avoid deformation of the bearing seat caused by local stress.

Use a torque wrench to control the preload force, ensuring that the preload force of each bolt on the same bearing seat is consistent (error ≤ 5%), to prevent hole displacement caused by uneven force.

3. Selection of cooperation methods

Transition fit or small interference fit: The bearing hole and outer ring are matched with H7/js6 or H7/k6 to avoid coaxiality deviation caused by clearance fit.

Positioning pin fixation: Install positioning pins (such as conical pins) between the bearing seat and the base to ensure that the position remains unchanged during repeated installation.

4、 Testing and adjustment methods

1. Coaxiality testing tool

Dial gauge detection:

Insert the core shaft into the bearing hole and support both ends with V-shaped blocks.

The dial gauge is fixed on the equipment rack, and the meter head contacts the surface of the core shaft. Rotate the core shaft once and read half of the difference in the dial gauge as the coaxiality error (target value ≤ 0.03mm).

Laser alignment instrument: used for coaxiality detection of multi bearing seats in long axis systems, with an accuracy of ± 0.001mm, and can display the offset and angle deviation of each bearing seat in real time.

2. Adjustment measures

If the coaxiality exceeds the tolerance, it can be adjusted through the following methods:

Gasket adjustment: Add stainless steel gaskets (thickness 0.01-0.1mm) to the bottom surface of the bearing seat and adjust the center height.

Grinding and repairing installation surface: Grind the installation surface of the bearing seat to correct flatness errors.

Re reaming: If the positioning pin hole deviates, the hole diameter can be enlarged and a new positioning pin can be used.

summary

The core of coaxiality control is unified reference, precision matching, and rigorous assembly. Through tolerance matching in the design phase, precision manufacturing in the machining phase, and benchmark calibration and inspection adjustment in the assembly phase, it can be ensured that the coaxiality between the non-standard bearing seat and the standard bearing seat meets the equipment operation requirements (usually ≤ 0.05mm). For high-precision equipment such as machine tools and steam turbines, it is recommended to entrust a professional team to assemble and keep inspection records for traceability.