RU169603U1 - Smelting and casting crucible for vacuum furnace - Google Patents

Abstract

The utility model relates to the field of foundry, namely to designs of melting and casting crucibles, and can be used in vacuum induction melting and casting plants for the production of castings from heat-resistant steels and alloys based on nickel (and cobalt) for portioned casting and melting. the result of this technical solution is to improve the quality of the castings obtained by preventing clogging with slag and other non-metallic inclusions present in liquid metal and sinking into the mold during its pouring, as well as extending the life of the lid and the crucible itself. The technical result is achieved by the fact that in the melting and pouring crucible containing the body, on which the lid is mounted in the form of a flat segment with an arrow equal to 0.7- 1.3 from the outer radius of the crucible, in which a through rectangular or oval drain hole is made, the inner surface of which is made tangent to the inner surface of the crucible, a ceramic plug is installed in the drain hole, which is removed Xia of holes of the crucible is tilted to drain the melt on an angle at which the free surface of the melt is at a level above the lower section of the drain opening by an amount not less than the diameter of a circle inscribed into the drain hole.

Description

The utility model relates to the field of foundry, namely, to designs of melting and casting crucibles, and can be used in vacuum induction melting and casting plants for the production of castings from heat-resistant steels and alloys based on nickel (and cobalt) during batch casting and melting.

Known crucible for casting parts from heat-resistant steels and alloys, containing a housing in the upper part of which there is a drain hole (utility model patent No. 119081 from 11.28.2011, IPC F27B 14/10, publ. 10.08.2012 bul. No. 22).

The disadvantage of this design is the increased length of the path of the melt during its flow through the drain cavity, associated with the presence of an extension in the crucible in its upper part, which leads to kneading of slag in the flow of the melt being poured and thereby pollution of the castings.

Also known is a melting and pouring crucible containing a housing on which the lid is mounted (Copyright certificate No. 92376 of 09/18/1950, IPC B22D 35/00, F27B 14/10, publ. 01.01.1951).

The disadvantages of this device are the small area of the open mirror of the melt (in the lid there are two small windows - a loading window for a charge and an unloading window for a flux), which makes it difficult to control the process of melting and pouring metal; as well as in the manufacture of a crucible and a lid of this design from refractory materials (for example, mullite corundum) for melting and pouring of heat-resistant steels and alloys, the walls of the crucible will be destroyed due to the expansion of the lid material during its radiant heating during the melting process (while the crucible is cooled from the inductor).

The closest is a melting and pouring crucible containing a housing on which the lid is mounted. The cover is made in the form of a plate in the form of a segment, the radius of which is equal to the outer radius of the upper part of the housing, while the width of the cover is 0.7-1.3 from the external radius of the upper part of the housing, and a through drain hole is made in the cover. The through hole is made in a rectangular or oval shape (Patent RU No. 148383, IPC7 F27B 14/10, publ. 10.12.2014).

The disadvantage of this design is that when pouring the melt into the mold in the initial period of time, the elements of the slag can penetrate the casting with the formation of defects in it. To prevent this phenomenon, it is advisable to perform additional cleaning of the melt from non-metallic inclusions by installing a ceramic plug in the drain hole.

The advantage of the utility model is to improve the quality of the resulting castings due to the reliable cleaning of metal from slag. In this case, the slag located on the free surface of the metal adheres to the walls of the crucible, the lid, but does not penetrate the castings.

The technical result of the indicated technical solution is to improve the quality of the obtained castings by preventing clogging with slag and other non-metallic inclusions present in the liquid metal and penetrating the mold during its pouring, as well as extending the life of the lid and the crucible itself.

The technical result is achieved by the fact that the melting and pouring crucible containing the body, on which the lid is installed in the form of a flat segment with an arrow equal to 0.7-1.3 from the outer radius of the crucible, in which a through rectangular or oval drain hole is made, the inner surface which is made along the tangent to the inner surface of the crucible, a ceramic plug is installed in the drain hole, which is removed from the hole by tilting the crucible to drain the melt at an angle at which the free surface of the melt at a level above the lower section of the drain hole by an amount not less than the diameter of the circle inscribed in the drain hole.

New is that a ceramic plug is additionally installed in the drain hole of the lid. When the crucible is rotated to drain by an angle α, the stopper delays the start of pouring molten metal into the mold for a time during which the free surface of the melt exceeds the drain hole by an amount h, not less than the diameter of the circle d inscribed in the hole. At the indicated time, the plug is removed from the hole and non-metallic inclusions located on the free surface of the melt do not penetrate into the filled mold during the filling of the casting. At the stage when the melt is drained from the crucible, the gate and the casting bowl are filled, this portion of the melt may contain non-metallic inclusions, but this does not affect the quality of the castings.

In FIG. 1 - shows a melting and casting crucible.

In FIG. 2 - melting and casting crucible in the process of pouring the melt into the mold.

The melting and pouring crucible (Fig. 1) contains a housing 1, which contains molten metal 2, and slag 3 accumulates on the free surface of the melt 3. On the crucible there is a lid 4 with a drain hole 5, into which the plug 6 is inserted, on the plug hook 7 is made.

When you turn (Fig. 2) the body 1 of the melting and pouring crucible to drain the melt 2 into a mold, starting from an angle of inclination α, at each moment of time must correspond to a predetermined pressure head H of the liquid metal above the drain hole 5. The value of H must be greater than h⋅ sinα, where h = d is the diameter of the circle inscribed in the drain hole. Thus, when the crucible is rotated to drain the melt into the mold at an angle α at which Н> h⋅sinα, the plug is removed from the drain hole in the direction of arrow A, for example, using hook 7 on plug 6, which is connected in the set position of the crucible (for turning the crucible at an angle α) with a stop placed in the working space of the vacuum furnace.

The pressure N corresponds to the flow rate Q of the liquid from the crucible in the ratio:

;

where s is the area of the drain hole,

φ is the discharge coefficient of the drain hole, its value is 0.6-0.7;

g is the acceleration of gravity.

The value of Q is defined as the technological parameter of pouring a specific form.

When using the melting and pouring crucible of the claimed design and installing the lid 2 after preparing the melt for pouring, the crucible is rotated to drain to ensure a predetermined pressure H in the crucible. In this case, the slag 3 is delayed, since it has a density 1.5-2 times lower than the metal, and it wetts the walls of the crucible body 1 and the lid 4 well, the melt 2 clean of slag 3 is poured into the mold. Cork 6 is necessary, since at the initial moment of pouring, slag may enter the castings.

Experimental melts using a crucible of the claimed design showed the absence of defects: slag blockage and oxide captivity during X-ray control and lumontrol of the obtained castings.

Due to the fact that residual slag inclusions are delayed in the crucible of the claimed design, an improvement in the quality of the resulting castings is achieved.

Claims (1)

A melting and casting crucible for a vacuum furnace, comprising a body and a lid in the form of a flat segment with a drain hole mounted on it, characterized in that it is equipped with a ceramic stopper installed in the drain hole of the lid, which can be removed in a predetermined position of the crucible when it is turned on the angle at which the surface of the melt in the crucible exceeds the level of the lower section of the drain hole in the lid by at least a diameter of a circle inscribed in the drain hole.

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