| 摘要 |
PROBLEM TO BE SOLVED: To improve surface gloss by pressing polishing nonwoven fabric to the inner surface of a pipe by a ferromagnetic body magnetized by a magnetic field of a magnet, supplying a nitric acid solution in the pipe, and relatively moving the magnet or the pipe. SOLUTION: An electromagnet 8 is arranged outside a pipe 1 as a material to be polished, and a block-like ferromagnetic body 4 to which a polishing non-woven fabric is stuck is inserted in the pipe 1. By the ferromagnetic body 4 magnetized by a magnetic field of the electromagnet 8, the polishing non- woven fabric is pressed to the inner surface of the pipe 1. Secondly, a solution of about 3% nitric acid is supplied into the pipe 1, and the pipe 1 is rotated to relatively move the pipe 1 to the ferromagnetic body 4. Thus, inner surface polishing is performed for the pipe 1. Scratch in the circumferential direction of the pipe is found in the polished surface, but it is a smooth surface which has favorable surface gloss and the surface roughness Ry of about 0.1 μm. |
