As the "backbone" of belt conveyors, idler rollers play a core role in bearing the weight of the conveyor belt and reducing operational friction. Their assembly quality directly determines the energy consumption level and operation & maintenance costs of the conveyor. The assembly process must adhere to the principles of "precision, cleanliness, and standardization," with focus on the following key precautions to ensure each idler roller meets industrial operation standards.
1. Before Assembly: Building a Solid Foundation for Quality
Pre-assembly preparations are crucial to avoiding subsequent failures, requiring strict control over three aspects: parts, tools, and environment.
Parts inspection requires "double checks": First, visual inspection – steel pipes must be free of cracks, rust, and burrs; bearing housing threads must be free of slipping and deformation; seals (O-rings, labyrinth seals) should be made of oil-resistant rubber to ensure good elasticity and no aging or cracking. Second, material and dimension verification – steel pipes must be seamless steel pipes (wall thickness deviation ≤ 0.5mm); bearings must be made of high-carbon steel (hardness ≥ HRC 60). Meanwhile, use vernier calipers and micrometers to check key fitting dimensions: the inner diameter of the steel pipe and outer diameter of the bearing housing must comply with the transition fit of H7/h6 (clearance: 0.01-0.03mm), and the shaft and bearing inner ring must form an interference fit (interference amount: 0.005-0.01mm) to prevent abnormal noise caused by improper clearance.
Parts cleaning requires "thoroughness without residue": All parts should be soaked in kerosene for 10-15 minutes, then cleaned with a soft-bristle brush to remove oil stains and iron filings from inner walls, threaded holes, and seal grooves. After cleaning, bearings must be immediately coated with lithium-based grease (filled to 1/3-1/2 of the bearing's internal space; excessive filling causes overheating, while insufficient filling leads to wear) and wrapped in dust-proof film for later use.
Tools and environment require "precision compliance": Torque wrenches and press-fitting machines must be calibrated quarterly (error ≤ ±2%); fixtures should be tested for positioning accuracy using a laser collimator to ensure the coaxiality error between the shaft and steel pipe is ≤ 0.1mm/m. The assembly area must maintain a constant temperature (15-25℃) and dryness (humidity ≤ 60%), with dust-proof mats laid on the ground to prevent dust and moisture from entering assembly gaps.
2. Core Assembly: Controlling the Precision of Operational Details
The assembly process must avoid "rough operations," with each step complying with technical specifications.
When press-fitting bearings, control the pressure (adjusted according to bearing model; e.g., the press-fitting force for 6205 bearings is 8-12kN) and speed (5-10mm per minute) of the press-fitting machine. Insufficient pressure leads to loose bearings, while excessive pressure damages the bearing inner ring. After press-fitting, rotate the bearing by hand to ensure no sticking sensation.
When installing seals, first apply a thin layer of grease to the seal groove, then slowly insert the O-ring into the groove (avoid twisting). Align the upper and lower seal teeth of the labyrinth seal to ensure uniform clearance (0.1-0.2mm), preventing powder leakage and water ingress during later operation.
When assembling the shaft and steel pipe, slowly insert the shaft into the center of the steel pipe, and use a dial indicator to real-time monitor the deviation between the shaft centerline and steel pipe axis. If eccentricity is found, adjust immediately to avoid radial vibration during operation. When tightening bearing housing bolts, use a torque wrench to apply the specified torque (e.g., the torque for M10 bolts is 25-30N·m), and tighten symmetric bolts evenly in 3 stages to prevent part deformation caused by uneven force.
3. After Assembly: Strict Inspection and Standardized Storage
Finished product inspection requires "comprehensiveness without dead ends," and non-conforming products are strictly prohibited from leaving the factory.
Basic inspections include: manual rotation of the idler roller (flexibility of rotation ≥ 3 cycles, no sticking or abnormal noise), radial runout measurement with a dial indicator (≤ 0.5mm), and axial endplay measurement with a feeler gauge (≤ 0.3mm). Seal performance must pass a water spray test (water pressure: 0.2MPa, spray duration: 10 minutes, no water seepage or leakage). A no-load operation test is also required (rotational speed: 1000r/min, continuous operation: 30 minutes, bearing temperature ≤ 40℃, no abnormal noise).
For non-conforming products, mark the problematic parts (e.g., "excessive radial runout," "seal water leakage"), disassemble them, re-verify part dimensions and assembly processes, and only conduct re-assembly after resolving the issues.
Finished products should be stacked by category, with timber blocks (height ≥ 10cm) placed at the bottom to prevent direct contact with the ground and subsequent moisture damage. Meanwhile, keep them away from heat sources and corrosive substances. For products stored for more than 3 months, recheck the grease condition to ensure stable performance when the idler rollers are put into use.
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