| 摘要 |
PURPOSE:To secure the sealability by forming a nitride film of the prescribed surface roughness on the sliding surface with the oil seal of a metallic parts. CONSTITUTION:An opening on the right of a case 16 is closed by a cover 17. The cover 17 consists of a lid part 17a and a boss part 17b. A piston 20 is inserted in an advancing/retracting manner into first and second chambers 19a, 19b of a cylinder. The nitriding is executed on the sliding surface of the cover 17 and the piston 20 to form the nitride film 30. The surface roughness of the nitride film 30 below is Rz4, preferably below Rz3.2. The cover 17 and the piston 20 are made of cast iron. The nitriding is executed on the sliding surface with the oil seal. This treatment improves the corrosion resistance, reduces the surface roughness, and avoids damages of the oil seal. |
