| 摘要 |
In the continuous prodn. of the grid plates for Pb accumulators by mixing Pb oxide dust (Pb + PbO) to a paste successively with water and H2SO4, cooling and pressing into the grid spaces, the dust is ground before mixing to increase and equalise its surface activity and the paste is pressed through a die of a suitable size and shape in the form of a thin, wide, cohesive strip, whilst the grid is passed to or under this strip, which is pressed into the spaces. The paste pref. is extruded through a wide slit die and pressed into the grid spaces by rolling. The water used for mixing can also contain additives needed for negative grid plates, e.g. BaSO4, C black, lignin derivs. and/or storage stabilisers. The mixt. can be stabilised by adding high-mol. water-soluble polyethylene oxide, pref. in a amt. of 0.05-0.5%, before adding the water. Grinding and mixing are carried out in a 2-shaft mixer-kneader-extruder, with 2 adjacent worm shafts, turning in the same direction, in an 8-shaped twin-screw housing. This continuous pasting process gives good homogeneity and uniformity in wt. and dimensions, so that the plates have reproducible physical and chemical properties. The proces is simple and suitable for mass prodn. and the closed construction reduces the lead dust level in the factory. |
