RU2708035C1 - Method of casting in vacuum-film form - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to metallurgy and can be used in production of castings in molds produced by vacuum-film forming. Casting mold (1) is made from loose molding material by vacuum-film forming, protective elements are placed to protect synthetic film (2) from damages in mold gates (3). Protective elements used are gas-permeable removable head pieces consisting of protective screen (4) and fastening part (5).

EFFECT: higher quality of casting obtained in vacuum-film molds, including in located in close proximity to each other, in particular, on conveyor, improved technological effectiveness of casting method due to reduced labor input and material consumption.

5 cl, 3 dwg

Description

The invention relates to foundry and can be used in the manufacture of castings in foundry molds obtained by the method of vacuum-film molding, located in close proximity to each other, in particular, on the conveyor.

It is known to manufacture castings using accessories for vacuum molding on a conveyor, in which a synthetic film or other gas-tight sand-sealing material is applied to the casting model, a flask is placed on the model plate, sand is poured, the seal is sealed and the half mold is obtained, and the mold is assembled from the half mold, collected in a single unit up to several dozen molds for accumulation under the melt pouring and cooling to form a sufficient fraction of the solid phase in volume and the hard crust on the surface of the casting , which allows further cooling when disconnecting the form from the vacuum system (see RU 2044592 C1, publ. 09/27/1995).

It is known to manufacture castings in vacuum-film molds on a conveyor with a vacuum system, in which a model is wrapped with a synthetic film on a model plate, paired flasks are placed, sand is flushed into the flasks, the molds are evacuated, the half-molds are assembled into a mold and fed for filling (see RU 2020025 C1 , published on September 30, 1994).

In known technical solutions, the proximity of the placement of the molds to each other when casting on the conveyor increases the likelihood of damage and melting of the synthetic film on the surface of the adjacent mold. From the influence of molten metal in the event of splashes of metal from the funnel, profits, bursts of the poured form from the counter-side to the surface of the yet not poured neighboring form, the synthetic film is easily destroyed, which leads to its partial depressurization and local collapses in the form sent for pouring.

There is also a known method for producing castings in vacuum-film forms, adopted as the closest analogue, which includes sealing with a synthetic film of a mold, evacuating the mold and pouring the metal; in this case, after pouring the mold with metal over the cavity of the cast-off and funnel spouts and on the adjacent surface of the counter, lay bags made of synthetic film, filled with molding sand. For large forms, when it is not convenient to place sand bags immediately after pouring, they are placed before pouring the metal into the mold, and in order to give strength to the sand filler, the bag is evacuated (see RU 2014939 C1, publ. 30.06.1994).

The technical problem inherent in this technical solution is to reduce the quality of the obtained casting, to be protected from splashes of molten metal on the surface of neighboring molds during pouring, followed by the application of a bag, the complexity of the method, increased labor intensity and material consumption. In case of damage to the bag, the sand, spilling out of the bag, comes into contact with liquid metal, which contributes to the formation of blockages, leading to a decrease in the quality of the casting. If splashes of molten metal get on the surface of neighboring forms, they are depressurized due to damage to the synthetic film. The use of bags for sealing areas of the mold around the funnel and closures requires the preliminary manufacture of bags made of synthetic film, filling them with sand, vacuum, which complicates the technology of casting, increases the complexity and consumption of materials.

The technical result of the invention is to improve the quality of castings obtained in vacuum-film casting molds, including those located in close proximity, to improve the manufacturability of the method of producing castings by reducing the complexity and material consumption.

The specified technical result is achieved by the fact that the mold is made of loose molding material by the method of vacuum-film molding, protective elements are placed to protect against damage to the synthetic film, the metal is poured into the mold, the casting is extracted, unlike the closest analogue, as protective elements gas-permeable removable heads consisting of a protective screen and a fixing part are placed over the mold supports.

In a preferred form of implementation, the protective screens of the removable heads are made of mesh material, or of a sheet with holes to ensure gas permeability.

In a preferred embodiment, the fastening parts of the removable heads are made in the form of at least two separate legs with gaps between them.

In a preferred form of implementation, the protective shields of the removable heads are performed by exceeding over the cross-sectional area the supports in their upper part by (10-50)%.

In a preferred embodiment, the removable heads are dismantled after completion of casting, or during extraction of the casting.

Equipping mold castings with removable heads is easy to use, labor-consuming technological operation. Structurally removable heads, consisting of a protective screen and a mounting part, are simple parts of reduced material consumption. The implementation of removable heads gas-permeable provides an unhindered exit of gases, which allows the discharge to perform its function of venting the mold cavity, and at the same time serve as a reliable barrier against liquid metal sprays ejected from the discharge during the pouring process. As a result, the integrity of the synthetic film of the casting mold and the waiting casting of the adjacent casting mold during conveyor filling, as well as when placing the molds on the parade ground in close proximity to each other, is maintained.

The implementation of the invention is illustrated by graphic materials, where:

in FIG. 1 shows the connection of a removable head with a mold in the place of an outlet, a longitudinal section;

in FIG. 2 shows a removable head, top view;

in FIG. 3 shows a removable head, axonometric projection.

In the mold 1, covered with a synthetic film 2, a protective element in the form of a removable head is installed above the outlet cavity (ventilation channel) 3 (Fig. 1). The removable head consists of a protective shield 4 and a mounting part 5 with fastening elements 5.1. The fixing part 5 is made in the form of at least two disparate legs with gaps between them for unhindered passage of gases; fasteners 5.1 can be made in the form of hooks. Between themselves, the protective screen 4 and the fastening part 5 can be connected by a detachable connection, in particular, a bolt, or one-piece connection, in particular, by welding.

In the upper part of the outlet 3, the seats 3.1 are made for positioning the fastening elements 5.1 therein. The seats 3.1 are covered with a synthetic film 2 to ensure the tightness of the mold 1.

Depending on the size of the castings and the design of the flasks, the protective screens of the removable heads are fixed above the supports at a height of 5-300 mm.

The protective screen 4 can be made of mesh, that is, of a mesh material, or of a sheet without holes, or of a sheet in which evenly spaced holes 4.1 are made (Fig. 2). The diameter of the holes 4.1 is not more than 10 mm for a reliable barrier against flying metal spray. When using a mesh or hole screen, the metal consumption is further reduced, its permeability to flue gases is further improved, which can be important with a low overall height of the structure.

Preferably, the shield 4 is circular. For guaranteed protection against the spread of splashes of liquid metal, the protective screen 4 is performed with an excess of outlet 3 by the external cross-sectional area by (10-50)%. The manufacture of a protective screen 4 in excess of the specified range is impractical and leads to an increase in material consumption. Performing an excess of less than 10% increases the likelihood of metal splatter flying beyond the protective shield 4.

The proposed invention works as follows.

The mold 1 is made by the vacuum-film molding method, for which the mold 1 is covered with a synthetic film 2, after which the loose molding material of the mold 1 is evacuated.

In the finished casting mold 1, a protective element is installed over each spout. The protective element can be made in the form of a removable head, consisting of a protective shield 4 and a fastening part 5 made of metal. The fastening elements 5.1 are positioned inside the seats 3.1 of the outlet 3 and thereby fix the removable head over the cavity of the outlet 3.

In the process of subsequent pouring of metal into the mold and as it is filled, molten metal sprays carried away by the air stream (shown by the arrow in Fig. 2) from the working cavity of mold 1 into the channels of the strips 3 can be ejected from the strips 3. From metal splashes nearby standing, waiting to be filled, assembled foundry molds reliably protect removable heads.

The need to find protective elements on the mold disappears after pouring is completed. The removable heads are dismantled some time after the completion of pouring, or during the extraction of the casting.

Claims (5)

1. A method of obtaining a casting in a vacuum-film form, including the manufacture of a mold from a loose molding material by the method of vacuum-film molding, the placement of protective elements to protect against damage to the synthetic film, pouring metal into the mold, removing the casting, characterized in that in quality of protective elements in the mold supports are placed gas-permeable removable heads, consisting of a protective screen and a mounting part. 2. The method according to p. 1, characterized in that the protective screens of the removable heads are made of a sheet, or of a sheet with holes, or of mesh material. 3. The method according to p. 1, characterized in that the fastening parts of the removable heads are made in the form of at least two separate legs with gaps between them. 4. The method according to p. 1, characterized in that the protective screens of the removable heads perform exceeding the cross-sectional area of the protrusions in their upper part by 10-50%. 5. The method according to p. 1, characterized in that the removable heads are dismantled after completion of the casting of the metal or during extraction of the casting.

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