Hydraulic Gear Pump Production Process
StepⅠ. Raw material selection and pretreatment
Material standards:
Gear material: 20CrMnTi alloy steel (hardness 58-62HRC) or powder metallurgy gear (density ≥7.2g/cm³), material composition report (in compliance with GB/T 3077 standard) is required;
Pump body material: gray cast iron HT250 (tensile strength ≥250MPa) or aluminum alloy ADC12 (pressure resistance ≥200Bar).
Pretreatment process:
Gear blank forging: multi-directional die forging process to eliminate internal pores;
Pump body casting: lost foam precision casting, surface roughness Ra≤3.2μm, flow channel size tolerance ±0.1mm.
Step Ⅱ. Gear precision machining
Tooth profile machining:
Gear hobbing: Use CNC gear hobbing machine, module range 1-8, tooth profile error ≤0.005mm;
Gear grinding: Use KAPP CNC profile grinder, tooth surface roughness Ra ≤0.4μm, tooth direction error ≤0.003mm.
End surface treatment:
Double end surface grinding (flatness ≤0.002mm) to ensure the consistency of gear axial clearance.
Step Ⅲ. Pump body processing and flow channel optimization
Key processes:
Bearing hole processing: five-axis linkage machining center (accuracy ±0.005mm), coaxiality ≤0.01mm;
Inlet and outlet molding: high-pressure water jet cutting to avoid thermal deformation, port fillet R0.2mm to optimize turbulence.
Surface treatment:
Inner cavity electrolytic polishing (roughness Ra ≤0.8μm) to reduce hydraulic oil flow resistance.
Step Ⅳ. Heat treatment and strengthening process
Gear carburizing and quenching:
Carburizing layer depth 0.8-1.2mm, surface hardness ≥60HRC, core hardness 35-40HRC;
Vacuum quenching furnace treatment, deformation <0.02mm.
Pump body aging treatment:
Aluminum alloy pump body T6 heat treatment (solid solution + artificial aging) to eliminate residual stress.
Step Ⅴ. Precision assembly and clearance control
Key assembly parameters:
Gear side clearance: 0.03-0.05mm (high-pressure pump) or 0.05-0.08mm (medium and low-pressure pump), calibrated using a laser gap meter;
Bearing preload: Angular contact bearing preload is set to 50-80N·m to avoid overheating or loosening.
Sealing technology:
Shaft seal uses polytetrafluoroethylene + spring energy storage ring, pressure resistance ≥300Bar, life ≥10,000 hours.
Step Ⅵ. Full performance test and verification
Factory test items:
Test type Standard and method Qualified indicators
Pressure pulsation test At rated speed, 250Bar continuous operation for 30 minutes Pulsation value ≤±2%
Volume efficiency test Input/output flow ratio (ISO 4402 standard) ≥92% (high-pressure pump) or ≥88% (low-pressure pump)
Noise test Semi-anechoic chamber measurement, no-load condition (GB/T 29529) ≤70dB(A) @1500rpm
Durability test Overload 10% pressure (such as 275Bar) continuous operation for 500 hours Efficiency drop ≤3%, no leakage
Step Ⅶ. Quality traceability and packaging
Traceability system:
Each pump is engraved with a unique QR code, which is associated with material batches, processing parameters, and test data;
Supports customers to query complete production files online.
Protective packaging:
The inner cavity is injected with anti-rust oil (VCI vapor phase anti-rust technology), and the outer layer is reinforced with vacuum aluminum film + wooden box to adapt to -40℃~70℃ shipping environment.
