| 摘要 |
<p><PICT:0820890/III/1> A method of lining a hollow article comprises inserting within the article a core adapted to form a cavity or cavities between it and the inside surface of the article, introducing liquid plastic lining material, while preventing air from being entrapped, causing the material to set, removing the core and reheating and cooling the lining material to toughen it. As shown, the core is in three parts: (i) a baseplate 5 carrying a mandrel 6; (ii) a part 7, also comprising a plate and projecting mandrel; (iii) a part 9 similar in construction to the part 7. All three core parts are bolted at the marginal areas of their plate portions to flanges 4, 2 and 3 of the body 1 to be lined. The end face of the mandrel of the part 7 fits closely against that of the mandrel 6 and the end of the mandrel of the part 9 is formed to fit round part of the circumference of the mandrel 6. The clearance around the core is such that space is left for the plastic material between it and the inside surfaces of the body 1, part of the surface of the mounting flanges and the inside surfaces of their interconnecting conduits. The surfaces of the core are covered with whiting to render the plastic material non-adhesive thereto. The body 1 to be lined is sandblasted and cleaned and immersed in an air-drying primer, e.g. a mixture of vinyl and phenolic resin. A pump 12 forces liquid plastic material, e.g. a vinyl compound, to a header 13 which distributes it by radiating conduits 15, each with a valve 16, to openings in the plate 5 approximately in line with the space between the mandrel 6 and the body 1. Vents 17 are also arranged approximately in line with the upper end of the cavity to allow air to escape. The part 9 has vents 18. When plastic material issues from the vents the pump 12 is stopped, the valves 16 closed and the vents plugged. The entire unit is then placed in an oven and the temperature rapidly raised and kept at a high value, then reduced to, and maintained at, a lower value, this control of the curing temperature resulting in better adhesion of the lining material. Relief openings 19 allow for expansion during curing. The unit is aircooled, the core parts removed, and the sprue trimmed off. Roughness of the lining, due to uneven detachment from the core, is removed by reheating, the lining being shrouded from the direct heat of the oven by metal plates. This additional curing also toughens the plastic material. The outside of the body 1 may be coated with similar plastic material by spraying.</p> |
