The selection of hydraulic pumps directly impacts the performance of the hydraulic bending machines. We found, after a field study of 127 sheet-metal workshops, that 90% of failures were due to the improper selection of hydraulic pump. This article will analyze four types of hydraulic pump from an engineering perspective and provide selection advice.
1. Gear Pump: A Practical and Economical Basic Choice
Structure:
- Adopting the principle involute gear meshing
- Representative: External meshing gear pumps (such as HGP 300 series).
Advantages:
- Low production cost (about 1/3 the plunger pump).
- Volume power ratio up to 5kW/kg
- High anti-pollution capability (NAS 10 grade oils can still be used)
Performance Limitations:
- The working pressure is typically =20 MPa
- The flow pulsation can be as high as +-15%, which will affect the stability of the bending angle.
- Noise level is typically 75dB(A).
Improvement Plan:
- Installing a pressure compensator can increase volumetric efficiency up to 12 percent
- Double gear pump (flow fluctuations are reduced by +-7%)
Applicable Scenarios:
- Bending machines for small and medium tonnage (=100 tonnes)
- Low precision processing for rough materials
2. Screw Pump for Silent Operation
Technological Breakthrough
- Three-screw meshing (such as SNH Series)
- Axial hydraulic balance structure
The Following are Some of the Advantages You Can Enjoy:
- Flow Pulsation +-3 % (5 times better than Gear Pump)
- Excellent noise control (<=62dB(A))
- Maximum speed of 3000rpm
Project Measured Data
| Parameters | Gear pump | Screw pump |
|---|---|---|
| Volumetric efficiency | 89% | 93% |
| Pressure Pulsation | 1.2MPa | |
| Maintenance cycle | 2000h to 5000h |
Notes:
- Oil viscosity sensitive (ISO VG46 is recommended).
- Pre-filling the oil before starting to prevent dry friction
Applications:
- Precision bending within +-0.5deg.
- Conditions of continuous production (>8h/day).
III. Vane Pump: An Optimal Choice for Medium Pressure
Structural Innovation:
- Double-acting vane pump (such as PV2R series)
- Floating side plate design
Performance Characteristics:
- Working pressure range: 10-21 MPa
- Volume efficiency can reach up to 92%
- Response time to flow regulation 50ms
Test Results Compared:
The results of tests on a 160 ton bending machine are:
- Energy savings of 15% compared to gear pumps
- Oil temperature is 8 degrees lower than that of a plunger pumps
Maintenance Points
- Check blades regularly (replace every 4000h).
- Maintain oil temperature between 40-60°C (maximum working range).
Conditions of Employment:
- Large and medium bending machines (100 to 300 tons)
- Flexible production requires frequent speed changes
IV. Piston Pump: High-Pressure and Precision Configuration
Technical Benchmark:
- Axial piston pump with slant plate (such as A10VO)
- Pressure Compensation Variable Control
Outstanding Performance
- Work pressure can reach up to 35 MPa
- Volume efficiency>95%
- Accuracy of flow regulation +-1%
Cost Analysis:
- Purchase cost: 3-5 times the price of a gear pump
- Cost of life cycle: 40% less than gear pumps (calculated over 10 years).
Technical Frontier:
- Electronic proportional-variable technology (response times 20ms).
- Ceramic plunger (wear resistance increased by three times)
Conditions:
- Oil cleanliness NAS level 6 and above
- Equipped with temperature-control system (+-2 accuracy).
Users:
- Aerospace grade sheet metal processing
- Heavy duty bending machines exceeding 400 tons
V. Selection Decision Matrix
Select the pump according to your processing needs:
| Consideration factors | Gear pump | Screw pump | Vane pump | Plunger pump |
|---|---|---|---|---|
| Initial Cost | ★★★★ | ★★★ | ★★ | ★ |
| Processing accuracy | ★★ | ★★★ | ★★★★ | ★★★★★ |
| Maintenance is easy | ★★★★ | ★★★ | ★★ | ★ |
| Energy efficiency | ★★ | ★★★ | ★★★★ | ★★★★★ |
| High Pressure Adaptability | ★ | ★★ | ★★★ | ★★★★★ |
VI. Trends in Industry Development
Intelligent Upgrade:
- Smart pumps with IoT sensors, such as Haitong SmartPump
- Monitoring in real-time: flow fluctuations, bearing wear and efficiency attenuation
Energy-Saving Innovation:
- Combination of variable frequency motor and quantitative pump (energy savings 30%)
- Pressure adaptive control system
Material Revolution:
- Graphene coated piston (friction coefficient is reduced by 60%).
- Composite Material Pump Body (weight reduction by 40%)
Engineer Suggestion:
We recommend “20/80” for most sheet metal shops:
- Screw pump + gear pump solution for 80% of conventional processing
- 20% precision demand: plunger pump driven by servo motor
