Combined type water-cooled casting mould integrating directional casting blank solidification and selective area cooling

The invention relates to a combined type water-cooled casting mould integrating directional casting blank solidification and selective area cooling. By the adoption of the combined type water-cooled casting mould, from-bottom-to-top forced cooling and directional solidification of a casting blank are achieved, the situation that columnar crystals grow in the direction perpendicular to the wall of the mould and the situation that because the columnar crystals which grow in a non-directional manner are overdeveloped, the columnar crystals grow in the direction perpendicular to a base plate are avoided, the problems of central shrinkage porosity and V-shaped segregation are eliminated, a large-piece-weight cast-forged blank with grain being refined, grain size being uniform in ultrasonic testing and a solidification structure being compact, uniform and free of lacks is obtained, and the ultrasonic flow detection yield is improved; the upper half portion of a casting mould body is of a hollow heat-preservation structure; a cooling water channel and a base plate water cooler on the lower half portion of the casting mould body can conduct segmented selective cooling on different areas of the casting mould; establishment of a one-dimensional temperature field and the achievement of high cooling intensity are both considered; most of sensible heat and most of latent heat of the cast blank are conducted from the base plate, and therefore directional solidification is achieved; and a hot feeding riser is adopted, a molten glass layer, a heat generating agent layer and a covering layer which are arranged in the hot feeding riser enable a shrinkage cavity area to be mainly concentrated on the hot feeding riser, the solid height in the hot feeding riser is increased, and the ratios of a top crop and a back-end crop of the cast blank are reduced.