| 摘要 |
PURPOSE:To facilitate the repair of the fittings and to economize the manpower and time of the exchange of fittings, by thermally spraying an Ni-base self-fluxing alloy on the contact surface between a plug and the plug-fixing fittings of a mandrel bar and by forming a thermally sprayed film layer on the above-mentioned contact surface. CONSTITUTION:When plug-fixing fittings 6 for attaching a plug 7 to a mandrel bar 5 are constituted of a plug-fixing part 9 and a connecting part 10 with the mandrel bar 5, the contact surface A between the plug-fixing part 9 and the plug 7 is locally worn. In order to repair this contact surface A, an Ni-base self-fluxing alloy (alloy in which Si and B are blended with Ni) is thermal sprayed to form a thermally sprayed film layer on the contact surface A. At this time, the thermally sprayed film layer is composed of an undercoat layer, an intermediate layer, and a top layer, and, as the undercoat layer and the top layer, Ni-base self-fluxing alloy layers are formed to about 100-700mu thickness, respectively, and a layer of Ni-base self-fluxing alloy with which hard grains of WC, etc., are blended is formed to 500-2,000mu thickness as the intermediate layer. By this method, respective operation efficiencies of mills can be improved and also rolling tool costs can be reduced. |
