Production Details of Bridge Shock-Absorbing Bearings (Pot Bearings)

I. Processing of Core Components

Bearing Steel Pot: Low-alloy structural steel with strength grade Q355 or higher is adopted. The steel pot is formed through integral forging or thick steel plate stamping using a CNC lathe. After forming, non-destructive testing (such as UT ultrasonic testing) is required to ensure no internal defects like cracks or air holes exist. Subsequent precision turning is conducted to ensure the spherical error of the inner surface of the pot body does not exceed 0.05mm, and the inner wall roughness reaches Ra1.6μm, laying a foundation for subsequent sealing and pressure-bearing functions.

Pressure-Bearing Sliding Plates: They are divided into polytetrafluoroethylene (PTFE) sliding plates and stainless steel sliding plates. For PTFE sliding plates, pure PTFE material or modified materials reinforced with carbon fibers or glass fibers are used. They are formed by compression molding and then processed via CNC milling, ensuring the thickness deviation of the sliding plate is ±0.1mm and the surface flatness is ≤0.02mm/m. For stainless steel sliding plates, 304 or 316L stainless steel is selected, which undergoes cold rolling and polishing processes. The surface roughness of stainless steel sliding plates needs to reach Ra0.8μm, and passivation treatment is required to enhance corrosion resistance.

Shock-Absorbing Components:

For rubber shock-absorbing pot bearings, the rubber pads are made of a composite formula of natural rubber and nitrile rubber, processed through a vulcanization molding process. The vulcanization temperature is controlled at 150-160℃, and the vulcanization time is adjusted according to the thickness of the rubber pad (usually 8-15 minutes). It is necessary to ensure the rubber hardness reaches Shore A 60-70 degrees and the elastic recovery rate is ≥90%.

For lead-core shock-absorbing pot bearings, the lead cores are made of electrolytic lead with a purity of ≥99.99%, formed by extrusion. The diameter deviation of the lead core is ±0.2mm, and surface finish treatment is required to prevent impurities from affecting the shock-absorbing effect.

II. Assembly Process

Pretreatment: All metal components must undergo surface anti-rust treatment before assembly, usually through hot-dip galvanizing (zinc coating thickness ≥85μm) or electrostatic spraying (coating thickness 60-80μm). After treatment, a salt spray test (neutral salt spray test ≥500 hours) is required to verify corrosion resistance.

Assembly of Core Components: First, embed the PTFE sliding plate into the groove at the bottom of the steel pot, ensuring tight fit between the sliding plate and the steel pot with a gap ≤0.03mm. Then place the rubber shock-absorbing pad (or lead-core component) and adjust its position to keep it centered. Next, install the stainless steel sliding plate, ensuring full contact between its sliding surface and that of the PTFE sliding plate without deviation. Finally, cover the upper bearing plate and fix the relative positions of all components with locating pins.

Sealing Treatment: Nitrile rubber sealing rings or fluororubber sealing rings are used and embedded into the sealing groove between the steel pot and the upper bearing plate. The compression amount of the sealing ring should be controlled within 20%-30% to ensure no leakage occurs during the pressure-bearing and displacement process of the bearing, preventing dust and rainwater from entering the interior and affecting sliding performance.

III. Quality Inspection

Dimensional Accuracy Inspection: A coordinate measuring machine is used to inspect the overall dimensions of the bearing (such as height, diameter, and mounting hole position) to ensure compliance with the design drawing requirements. The tolerance of key dimensions is controlled within ±0.5mm.

Mechanical Performance Testing:

Vertical load-bearing capacity test: Load up to 1.5 times the rated load-bearing capacity and hold for 1 hour, ensuring no plastic deformation of the bearing.

Horizontal displacement performance test: Under the rated vertical load, the horizontal displacement should reach the design value, and the sliding friction coefficient should be ≤0.03.

Shock-absorbing performance test: By simulating seismic loads, test parameters such as the damping ratio and maximum horizontal reaction force of the bearing, which must comply with relevant standards (e.g., JT/T 391 Highway Bridge Pot Bearings).

Appearance and Sealing Performance Inspection: Visually inspect the bearing surface for no defects such as scratches, deformation, or coating peeling. Conduct a water pressure test (water injection pressure 0.3MPa, pressure holding for 30 minutes) or air tightness test to check the sealing performance and ensure no leakage.

IV. Packaging and Labeling

Packaging: The main body of the bearing is wrapped with a waterproof plastic film, and a wooden pallet or wooden box is used for external packaging to prevent collision and moisture during transportation. Vulnerable components (such as sealing parts and connecting parts) are packaged separately and provided together with the bearing.

Labeling: Product labels should clearly indicate the bearing model, specification, rated load-bearing capacity, production batch number, production date, manufacturer name, and contact information. Meanwhile, technical documents such as product qualification certificates, quality inspection reports, and installation instructions should be attached.