Hydraulic Cylinders for Extra-heavy Port Cranes

For this project, the cylinder barrel is made of 27SiMn material with quenched and tempered treatment, featuring a maximum yield strength of 950 Mpa and a maximum tensile strength of 1100 Mpa. The piston rod is manufactured from 42CrMo material also with quenched and tempered treatment, and its surface is nickel-plated and chrome-plated, which can effectively resist the salt spray environment in ports. The seals are of the Swedish brand SKF, while the explosion-proof valves and check valves adopt the German brand HAWE Hydraulic.

Production Process of Piston Rod

1. Blanking: Reserve a total length allowance of 8mm and an outer diameter allowance of 10mm based on the net dimension.

2. Heat treatment: Quenched and tempered to a hardness of 270-295HB.

3. Rough turning: Roughly turn the outer diameter, reserve a finish machining allowance of 3mm for the total length and a grinding allowance of 1.2mm for the outer diameter.

4. Rough grinding: Roughly grind the outer diameter, reserve a finish grinding allowance of 0.6mm.

5. Finish turning: Take the roughly ground outer diameter as the datum, finish turn both left and right ends, and machine the length to the required dimension.

6. Finish grinding: Grind the outer diameter to the required dimension.

7. Polishing: Polish the outer diameter and ball head to ensure a surface roughness of Ra0.2.

8. Electroplating: Nickel-plate to a thickness of 0.03mm, followed by chrome-plating to a thickness of 0.04mm, with a total plating thickness of 0.07mm.

9. Re-polishing: Conduct secondary polishing to ensure no electroplating blowholes or defects on the outer surface.

10. Inspection: Re-inspect all dimensions before assembly.

Production Process of Cylinder Barrel

1. Blanking: Select 27SiMn cylinder barrel and reserve sufficient machining allowances for length, inner bore and outer diameter.

2. Heat treatment: Quench and temper the cylinder barrel to a hardness of 270-295HB.

3. Boring: Perform deep hole boring on the inner bore and reserve a honing allowance of 1mm.

4. Rough turning: Take the inner bore as the datum, roughly turn the outer diameter and machine the outer diameter to the required dimension.

5. Welding: Weld the flange part.

6. Finish turning: Finish turn the outer and inner bores of the flange part to ensure the inner bore is consistent with the cylinder barrel dimension.

7. Honing: Hone the inner bore to the dimension specified in the drawing.

8. Finish turning: Finish turn the cylinder barrel threads and welding bevels.

9. Welding: Weld the cylinder bottom components.

10. Flaw detection: Conduct ultrasonic and penetrant flaw detection on the cylinder bottom welds to ensure no internal or surface defects.

11. Inspection: Re-inspect all dimensions before assembly.