CN-122007379-A - GIS large-size tank composite casting mold low-pressure casting device and method

CN122007379ACN 122007379 ACN122007379 ACN 122007379ACN-122007379-A

Abstract

The invention belongs to the technical field of low-pressure casting, in particular to a GIS large-size tank body composite casting low-pressure casting device and a GIS large-size tank body composite casting method, wherein the GIS large-size tank body is formed by connecting three cylindrical tank bodies, two sides of each cylindrical tank body are provided with a plurality of bosses, the top, the bottom and the end face of each cylindrical tank body are provided with flanges according to requirements, the rear end of the tank body is provided with a hemispherical part, the part inside the tank body is formed by the inner cavity sand core, and the outer surface of the tank body is compositely formed by adopting a mode of combining a metal outer mold system, an outer mold sand mold assembly and an outer mold metal movable insert assembly.

Inventors

ZHOU LIWEI
GUI JING
XU GONGJIE
WANG HONGWEI
ZHANG HUARUI

Assignees

诸城航大新材料技术有限公司

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (8)

1. A GIS large-size tank composite casting mold low-pressure casting device is characterized in that, The GIS large-size tank body is formed by connecting three cylindrical tank bodies, two sides of each cylindrical tank body are provided with a plurality of bosses, the top, the bottom and the end face of each cylindrical tank body are provided with flanges, each cylindrical tank body comprises a side flange, a top flange, a bottom first flange and a bottom second flange, the rear end of each cylindrical tank body is provided with a hemispherical part, The wall thickness of the GIS large-size tank body is not more than 15mm, the wall thickness of the flange is not more than 35mm, the wall thickness of the boss is not more than 50mm, and the transverse distance between the front end and the rear end of the GIS large-size tank body is not less than 1650mm; The low-pressure casting device adopts composite casting mold molding, the mold structure comprises a metal outer mold system, an outer mold sand mold assembly, an inner cavity sand core and an outer mold metal movable insert assembly, Wherein the inner surface of the GIS large-size tank body is formed by an inner cavity sand core, the outer surface of the GIS large-size tank body is formed by combining a metal outer mold system, an outer mold sand mold assembly and an outer mold metal movable insert assembly, The low-pressure casting device comprises a control system, wherein the control system designs a composite forming mode of the outer surface of the GIS large-size tank body according to the structural characteristics of each part on the GIS large-size tank body; The structure is characterized by comprising continuous distribution areas of the difficult-to-demolding blocks, minimum distances between adjacent difficult-to-demolding blocks, maximum distances between adjacent difficult-to-demolding blocks, sum of projection areas of all the difficult-to-demolding blocks on vertical surfaces in the demolding direction and area occupation ratio of the difficult-to-demolding blocks.
2. The low-pressure casting device for the composite casting mold of the large-size GIS tank body according to claim 1, wherein the outer mold sand mold assembly comprises an upper sand mold and a lower sand mold, the upper sand mold is adopted for molding at the top flange, and the lower sand mold is adopted for molding at the bottom first flange and the bottom second flange.
3. The GIS large-sized tank composite casting low-pressure casting device according to claim 2, wherein the outer mold metal insert assembly comprises a plurality of metal inserts, and the metal inserts are manufactured by H13 steel.
4. A GIS large-size tank composite casting low-pressure casting device according to claim 3, wherein the metal external mold system adopts split combination design, and comprises a bottom mold for providing casting bottom contour shaping, 2-4 hydraulically driven side molds for adapting the low-pressure casting device to the fetching track in the moving direction, and a top mold.
5. The low-pressure casting device for the composite casting mold of the large-size tank body of the GIS, according to claim 4, is characterized in that a pouring gate is arranged below the center position of the large-size tank body of the GIS, aluminum liquid rising in the pouring gate flows to transverse pouring gates on two sides through two diversion pouring gates, and the transverse pouring gates divert the aluminum liquid to the lower parts of three cylindrical tank body separation parts.
6. The low-pressure casting device for the composite casting mold of the large-size GIS tank according to claim 5, wherein after the aluminum liquid is split below the three cylindrical tank separating bodies, the aluminum liquid rises and enters the cavity through the ingate module.
7. The low-pressure casting device for the composite casting mold of the large-size tank body of the GIS, according to claim 6, is characterized in that a vacancy for sticking the metal chill is reserved on the inner cavity sand core at the connecting position of the three cylindrical split tank bodies.
8. A method for casting a composite casting mold of a large-size tank body of a GIS by using the low-pressure casting device of claim 7, comprising the steps of: 1) The liquid lifting stage is that aluminum liquid in the heat preservation furnace is conveyed to the pouring gate through the liquid lifting pipe under the pressure effect of compressed air; 2) The mold filling stage is to realize the dynamic adjustment of the mold filling pressure rising speed according to the liquid level height of the aluminum liquid, and complete the complete filling of the mold cavity; 3) In the crust formation stage, the pressure of compressed air is increased to solidify and crust the aluminum liquid on the molding surface; 4) The pressurizing stage is to continuously increase the pressure of compressed air, the pressure acts on the front edge of the solidification interface of the aluminum liquid, and the compactness of the material is improved; 5) Maintaining the pressure of compressed air to ensure the sequential solidification from the far end of the casting to the pouring gate, so as to realize feeding of the casting; 6) And the pressure relief stage is to release the pressure of the compressed air in the heat preservation furnace to the atmospheric pressure, and the residual aluminum liquid in the pouring gate and the liquid lifting pipe automatically flows back under the action of gravity.

Description

GIS large-size tank composite casting mold low-pressure casting device and method Technical Field The invention belongs to the technical field of low-pressure casting of large-size aluminum alloy structural parts, and particularly relates to a GIS large-size tank composite casting low-pressure casting device and method, which are particularly suitable for producing thin-wall cavity castings with high precision, high density and zero leakage requirements through composite casting of a metal outer mold sand mold metal insert. Background The large-size aluminum alloy shell structural member is widely applied to the fields of aerospace, ship manufacturing, power equipment and the like due to light weight, high strength and toughness and good corrosion resistance. The GIS (gas insulated metal enclosed switchgear) in the field of power equipment is a core high-voltage distribution device in a power system, and a tank part of the GIS is used as a key part for sealing, insulating and supporting an internal conductive element to directly determine the reliability, safety and service life of the GIS equipment. The large GIS tank body has remarkable specificity in structural design, material selection and preparation process due to the adaptation to the requirement of an ultra-high voltage of 110kV or above or an ultra-high voltage power system of 500 kV. The existing GIS tank production method comprises a casting method, a welding forming method, a spinning forming method and the like, wherein the welding method has strong adaptability, can be applied to tank body forming of various shapes and structures, has high material utilization rate, but has more welding seams (longitudinal seams and circumferential seams), insufficient sealing performance, high post-welding deformation control difficulty, residual stress, increased production cost, extremely high spinning forming dimensional accuracy, good inner wall surface quality and obvious advantages on thin wall design, is only applicable to cylindrical structures, has high equipment investment and needs to be improved due to the fact that the complex structures are welded. In the GIS tank casting production, the obtained casting has excellent air tightness, good structural integrity and strong impact resistance because of no weld joint due to integral molding, is suitable for integrated design with complex parts (flanges and lugs), and has very good prospect. However, the conventional sand mould gravity or sand mould low-pressure casting process of the GIS tank still has certain problems. The sand casting design is flexible, is suitable for complex cavity castings, but has poor air tightness due to high surface roughness (Ra >12.5 mu m) and lower dimensional accuracy (CT 9-CT 11 grade in general) and is difficult to meet the zero leakage requirement of SF6 equipment, while the pure metal mold casting can accelerate the solidification speed so as to refine the grain structure and improve the surface quality, is limited by the difficult problem of complex cavity demolding, and particularly cannot be effectively molded for deep cavity/negative angle structures and is difficult to be suitable for castings with complex cavities. Furthermore, the large-size casting of the GIS tank body has the characteristics of thin wall and large cavity, belongs to typical high-difficulty parts in casting production, has large height and length distance, extremely long aluminum liquid flow, and is extremely easy to solidify in advance due to too fast temperature drop once the casting system is unreasonable in design, so that insufficient casting or cold insulation is caused, defects such as air holes, shrinkage porosity, deformation, inclusion and the like are caused to occur in a chained manner, the reliability and the batch qualification rate (the average of industries is less than 85%) of the tank body are severely restricted, and the rejection rate can be up to 30-50% in serious cases. Disclosure of Invention Aiming at the severe requirements of GIS large-size tank castings on surface compactness and dimensional accuracy, the invention provides a composite casting scheme taking a metal outer die as a main body. The core breakthrough is that the nonmetallic forming area is reduced to the maximum extent, and through the actual production process condition and analysis, a general composite forming method is obtained, so that the forming area of the outer metal mold is increased to more than 70%, and the solidification compactness and the dimensional stability of the outer surface of the casting are obviously enhanced. The complete technical scheme of the invention comprises the following steps: a GIS large-size tank composite casting mold low-pressure casting device, The GIS large-size tank body is formed by connecting three cylindrical tank bodies, two sides of each cylindrical tank body are provided with a plurality of bosses, the top, the bottom and the end face of each cylindrical tan