Short crystallizer for casting hollow aluminum ingots

Abstract

The invention discloses a short crystallizer for casting hollow aluminum ingots. The short crystallizer comprises a crystallizer housing, wherein a triangular support is clamped inside an annular groove of the housing and can rotate on the housing; an internal sleeve and an liner are fixedly arranged inside the housing; a core is placed inside the liner; a water inlet is formed above the core, is connected with a core water inlet pipe and is arranged on the triangular support; a water outlet and a water outlet hole are formed below the core; and an aluminum liquid inlet is formed between the core and the liner. The short crystallizer is characterized in that the core (4) is internally hollow and conical, and the height of the core is 80mm-120mm; the height of the upper part of the core (4) is 65%-70% of that of the core, and the conical degree of the upper part of the core (4) is 1: (30-50); the height of the lower part of the core (4) is 30%-35% of that of the core, and the conical degree of the lower part of the core (4) is 1: (15-17); the internal sleeve is made of aluminum alloy; and the liner is made of copper and can be pulled out from the internal sleeve to be and replaced. By shortening the length of the crystallizer, the crystal grains of the hollow ingots are relatively thin, and the surface quality of finished tubes is good; and through the improvement that the upper and lower parts of the core of the crystallizer have two different conical degrees, the remelting and cracking of crystal membranes are avoided.

Description

technical field [0001] The invention relates to the technical field of aluminum processing, in particular to a short crystallizer for casting aluminum hollow ingots. Background technique [0002] At present, there are three main production methods of billet tubes for aluminum alloy seamless aluminum tubes: 1. Solid ingot piercing hot extrusion method; 2. Hollow ingot hot extrusion method; 3. Thin-walled hollow ingot three-roll hot rolling method. Among the three production methods, the first solid ingot piercing extrusion is mainly suitable for the production of soft aluminum alloy pipes, and generally aluminum alloy seamless pipes with small inner diameters; for alloy pipes with high strength and large-scale pipes, solid ingot piercing Extrusion cannot be produced, and the scope of application is very small. Generally, the other two production methods are hollow ingot hot extrusion method and thin-walled hollow ingot three-roll hot rolling method. [0003] Aluminum alloy h...

AI Technical Summary

Problems solved by technology

[0007] In the current hollow ingot casting production process, due to the friction between the shell and the core and the heating of the aluminum liquid, the crystalline film is remelted or thinned, and the strength decreases, which is easy to cause cracks and runaway phenomena on the inner and outer surfaces. And it often occurs; during the solidification process, due to the shrinkage of the liquid state into a solid state, the core must be processed into a conical shape to prevent the solidified hollow ingot from being hugged on the core. After the core appears taper, due to the effect of secondary cooling, crystallization Inside the crystallizer, there is a temperature gradient and solidification shrinkage from top to bottom, and the size of the inner hole gradually becomes smaller. The core used is a single taper, and when the length of the crystallizer core is constant, the taper of the core is too small, which is easy to wrap the core. , the taper is too large, a layer of insulating air gap will be formed between the hollow ingot and the core, which hinders further cooling, and the continuous replenishment of molten aluminum will cause remelting of the crystalline film, resulting in leakage, and the leaked molten aluminum will meet twice Water cooling, forming segregation nodules, attached to the inner surface of the hollow ingot

[0008] For the mold core used for casting hollow ingots, during the solidification process, since most of the metal crystallizes in the crystallizer, accompanied by the remelting and recrystallization process, the crystal grains have sufficient time to grow, the crystal grains are coarse, and the processing performance is relatively poor. Difference

[0009] To sum up, if casting hollow ingots with the mold core length and single taper required by the existing production process, the obtained hollow ingots have surface cracks and more segregation nodules, and the grain size is also poor due to the crystallization of metal in the mold , in the follow-up production, in addition to machining the hollow ingot, some parts also need to scrape the extruded billet tube, which is difficult to meet the high requirements of the structure and performance of the product, the consumption is large, the quality is difficult to control, and the yield is low

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