Casting method of movable and fixed vortex casting pieces of compressor

Abstract

The invention provides a casting method of movable and fixed vortex casting pieces of a compressor, aiming at solving the technical problem that the movable and fixed vortex casting pieces generate loosing and shrinkage at the hot joint in the casting process. The casting method comprises the following steps: embedding a conformal cold iron into the hot joint of the casting piece at the corresponding position of a core box, then carrying out sand shooting and manufacturing a sand core with the conformal cold iron; and placing the sand core with the conformal cold iron into a casting mold, combining a dead head feeding technique and casting the casting piece. The shape of the conformal cold iron is manufactured into a vortex shape or an arc shape according to the shapes of a vortex sand core teeth and the position of the hot joint of the vortex casting piece. One end of the conformal cold iron is provided with a columnar positioning lag; and the core box is provided with a positioning hole matched with the positioning lag. The sand core is internally provided with the conformal cold iron which is directly applied on the hot joint, thus having fast cooling speed and leading the hot joint position to obtain maximum subcooled temperature in the vortex casting piece. The casting method can effectively solve the defects of loosing and shrinkage of the root part of the vortex teeth.

Description

Technical field [0001] The invention relates to a casting method, in particular to a casting method of scroll castings. Background technique [0002] Hot joint refers to the node or area where the casting solidifies more slowly than the surrounding metal during the solidification process. After the casting solidifies, shrinkage porosity and shrinkage cavities are easily formed at the hot joint. At present, the common methods to solve the casting shrinkage porosity and shrinkage are: 1. The feeder is used alone. The main function of the feeder is to compensate for the liquid shrinkage of the molten metal in the cavity and the shrinkage during the solidification of the casting to obtain a dense casting without shrinkage. The thinnest casting is when it is cooled in the mold. When the thickest part is solidified first, its shrinkage can be compensated by the thicker part nearby; when the thicker part is solidified, it can be compensated by the thickest part; when the thickest part i...

AI Technical Summary

Problems solved by technology

[0002] The hot spot refers to the node or area where the casting is solidified slower than the surrounding metal during the solidification process. After the casting is solidified, shrinkage porosity and shrinkage cavity are easily formed at the hot spot. At present, the common methods to solve the shrinkage porosity and shrinkage cavity of the casting are: 1. The feeding riser is used alone. The main function of the riser is to compensate the liquid shrinkage of the molten metal in the cavity and the shrinkage of the casting during solidification, so as to obtain a dense casting without shrinkage cavity. When the casting is cooled in the mold, the thinnest The part of the body solidifies first, and its shrinkage can be compensated by the thicker part nearby; when the thicker part solidifies, it can be compensated by the thickest part; when the thickest part solidifies, if no external compensation is obtained, a large shrinkage will form there In this case, the role of the riser is to compensate for the last solidified part of the casting, so the riser is placed above or on the side of the thickest part of the casting, and its solidification is required to be later than the thickest part of the casting, the riser Feeding has a good feeding effect on concentrated hot spots near the center of the vortex, but for vortex castings, due to the limitation of feeding distance and feeding channel modulus, the feeding effect on concentrated hot spots near the center of the vortex is poor. The chemical composition and pouring temperature have relatively strict requirements, the process range is narrow, and the stability is poor. When the vortex castings adopt this process, the proportion of shrinkage porosity and shrinkage defects is high, and the production cannot be stable.

2. The special pig iron with less shrinkage and stable performance is used together with a fixed proportion of steel scrap and recycled materials to produce it. This special pig iron has the characteristics of small solidification and shrinkage, and the result of graphitization and expansion offsets the shrinkage and shrinkage defects caused by shrinkage. However, the price of this special pig iron is very high, and it is facing the danger of resource depletion due to overexploitation

However, the cold iron is indirectly chilled relative to the root of the scroll, and the distance is limited. When the thickness of the back of the scroll is greater than the chilling distance of the cold iron, there will still be shrinkage at the tooth root

This method can only be done on a horizontal line, and cannot be produced on a high-speed and efficient vertical line automatic molding line. For the special structure of the vortex back, it becomes very difficult to lower the cooling iron

During production, both the sand core and the cooling iron are put into the mold, which will inevitably cause the phenomenon of molding equipment waiting for others, and reduce the production efficiency

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