| 摘要 |
PROBLEM TO BE SOLVED: To suppress peeling of and damage to a spray-coating membrane by locally enhancing adhesion of the spray-coating membrane, especially, at an easy-to-flaw place on an outer surface of a cast ion pipe easily at low cost.SOLUTION: A blast processing apparatus 1 for a cast iron pipe includes a first booth 11 which covers a cast iron pipe D entirely and a second booth 21 which covers the cast iron pipe D partially. A first rough surface is formed on an outer surface of the cast iron pipe D substantially entirely with first hard particles projected from a first projection machine 12. Further, a second rough surface having larger average roughness than the first rough surface is formed at an axially intermediate part of the outer surface of the cast iron pipe D with second hard particles which are projected from a second projection machine 22 and sharper than the first hard particles. The cast iron pipe D is further subjected to spray coating processing and mortar lining processing and a press roller is strongly pressed against the axially intermediate part in the mortar lining processing so as to prevent flotation. The second rough surface is formed at the place that the press roller comes into contact with so as to improve adhesion force of a spray coating membrane, so that the spray coating membrane is suppressed from peeling or damaging. |
