SU457538A1 - The way to pour under low pressure - Google Patents

Description

one

The invention relates to foundry, in particular, to methods for producing castings with internal cavities, mainly from non-ferrous alloys.

The greatest effect is achieved by the implementation of the method for the production of castings, especially large-sized ones, with shaped internal cavities having undercuts, which require for production the use of ceramic or sand cores that define the cavities.

A known method for producing low-pressure castings of ferrous alloys into a metal chill, which means that the melt is cast into the mold cavity through the hollow tube of ceramic material contained in it.

The melt fills the tube, and then through the holes in the tube enters the cavity of the mold. After the melt is poured into the tube and the mold cavity, the melt is cut in the mold cavity with the tube from the crucibles and the metal conduit by closing the valve on the metal conduit. The latter prevents the melt from chill from pouring into the crucible when pressure is removed in the furnace chamber. After cooling the melt in the mold and the tube, a casting with an internal cavity is formed, which is formed by a tube with a melt solidified in it.

After the casting is fully solidified, the metal tube is removed from the casting in a press.

However, the known method has a low yield of the product, especially for large-sized castings, low labor productivity associated with long-term solidification of a large mass of metal in the tube, inefficient use of the metal, as well as low reliability of the installation to implement the method to cut off the melt in the chill mold from the melt in the metal pipe operating in contact with the liquid metal.

The purpose of the invention is to expand the casting nomenclature and reduce the melt consumption, improve productivity and yield of material.

This is achieved by the fact that after filling the mold cavity with the melt from the cavity of the forming rod, the melt is drained by equalizing the gas pressure in the crucible and mold chamber.

FIG. 1 shows the proposed installation, a general view; in fig. 2 — node 1 in FIG. 1 (on an enlarged scale).

The device contains a sealed furnace 1, crucible 2 with melt, metal pipe 3, separation plate 4, hermetic filling chamber 5, right part of form 6, left part of form 7, upper part of form 8, hollow sand or ceramic forming rod 9, blind ends in form 10, vents 11, the inner cavity 12 of the rod, the cavity 13 of the form, through holes 14 in the rod with reverse β-valves, valve seat 15, valve flaps 16, pin 17, pin 18 fitting and air inlets and outlets 19.

For a case with back pressure, this method is carried out as follows.

After the gas pressure in chambers 1 and 5 takes the required and the same value, the pressure in chamber 1 rises (usually 0.2-1.0 kgf / cm), the melt under the action of pressure difference rises along the metal pipe 3, filling the cavity 12 hollow rod 9. Next, the melt enters through the through holes 14 in the rod 9 to the dampers 16 check valves. The flaps 16 are made of heat-resistant elastic material, for example, mica plates or steel, which, for example, using studs 17 and embed studs 18 along a part of the perimeter, are fixed in the body of the rod. Under the pressure of the melt, the shutters 16 are folded back, the melt passes into the cavity 13 of a linear form, and the blind profits 10. At the same time, the air leaves the cavity 13 through the vents 11.

The thickness, dimensions, sealing and elastic properties of the material of the dampers should be chosen so as to ensure their bending from the valve seat 15 under the pressure of the melt with excess pressure (P 0.2 -1.0 kgf / cm) and return to its original position after removal. this pressure. When the melt is filled with cavity 13 and profits 10, when the melt in cavities 12 and 13 is still in a liquid state, the gas pressure in chambers 1 and 5 equalizes, resulting in melting of cavity 12 of rod 9 into the crucible 2 .

After removing the difference in gas pressures of the valve 16, under the action of the weight of the molten metal in the mold and due to the elastic properties of the material of the plates, they return to their original position, pressing against the seats 15, and prevent the melt from pouring out of the cavity 13 of the mold.

Next comes the technological exposure to solidify the casting, after which the pressure in chambers 1 and 5 is reset to atmospheric, KaiMepa 5 opens, the mold is fed to the operations of disassembling and removing the casting. The hollow rod 9 is removed from the casting by conventional embossing.

Under conditions of pouring under pressure, the proposed method is carried out in a similar way, except that the casting mold is under atmospheric pressure during the casting process.

The dimensions of the blind profits 10 with this method are insignificant, their function is mainly reduced to compensating for some melt loss in the cavity 13, which is associated with the inertia of returning the dampers 16 to the position pressed to the saddle 15 after removing the pressure difference. Therefore, the role of blind profits in this case can play small closed containers, which are usually performed when casting with back pressure and under low pressure in the upper part of the mold, and at the same time play the role of gas vyporov.

The proposed method provides improved performance, since using it eliminates the need to wait until the melt hardens in the rod cavity, reduces the melt flow rate due to its reverse draining from the rod cavity, and also makes it possible to produce large-sized castings with internal cavities of any sizes and shapes with availability in the cavity of the undercuts.

Subject invention

A low pressure casting method that involves supplying melt from crucibles through a metal conduit to a mold through a hollow molding rod, characterized in that, in order to expand the casting range and reduce the melt flow, after filling the mold cavity with melt from the cavity of the molding rod, the melt is drained by equalizing pressure gas in the chamber with crucible and mold.

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