RU2055686C1 - Method and apparatus for pressure die casting - Google Patents

Abstract

FIELD: casting production. SUBSTANCE: method of pressure die casting, comprising steps of holding a doze of metal by an electromagnetic field and feeding metal to a working cavity by displacing the metal doze from the a pressing chamber, also includes steps of moving the pressing chamber before the feed of metal to the working cavity, when the pressing chamber embraces the metal doze, hold by the electromagnetic field. Apparatus for performing the method, including a press-mold, an inductor, the pressing chamber and a pressing piston, where the press mold and the pressing piston may be members of the press-mold, the pressing chamber may be moved in such a way, that to embrace the metal doze, being hold by the electromagnetic field of the inductor. The invention allows to lower time period of heat exchange between the metal doze and the pressing chamber. EFFECT: enhanced efficiency of the method with use of the apparatus. 5 cl, 4 dwg

Description

 The invention relates to foundry, in particular to injection molding.

 Known injection molding, according to which liquid metal is poured into the pressing chamber, and from the pressing chamber, the pressing piston is fed into the forming cavity [1] The disadvantage of the casting method is the long contact interaction of the molten metal with the pressing chamber. It leads to cooling of the melt, limits the operating time of the pressing chamber due to heating of the pressing chamber of thermal stresses, cracking and high-pressure mesh, and also makes it difficult to obtain castings with a melting temperature exceeding the melting temperature of the material of the pressing chamber.

 There is also known a method for producing castings, containing electromagnetic confinement of the melt in the form of a column at the end of the counter piston, which, after the end of melting, is fed into the pressing chamber with an acceleration equal to the acceleration of gravity [2] The disadvantages of the method are the long heat exchange between the dose of the metal and the pressing chamber, since time feeding a dose of metal into the pressing chamber is determined by the acceleration of gravity; the need for a counter piston and a device that will ensure the movement of the counter piston with an acceleration equal to the acceleration of gravity; the danger of contact of a free-falling column of molten metal with the walls of the pressing chamber due to the transformation of the column into a ball due to surface tension forces.

 The purpose of the invention is the reduction of heat transfer time between a dose of molten metal and a pressing chamber.

 This is achieved by the fact that in the injection molding method, in which the dose of the metal is held by the electromagnetic field and the metal is supplied to the forming cavity by displacing its dose from the pressing chamber, the pressing chamber is moved before the metal is fed into the forming cavity, with the coverage of the dose of metal held by the electromagnetic field .

 This is also achieved by the fact that in the device for implementing the injection molding method comprising a mold, an inductor, a pressing chamber and a pressing piston, where the pressing chamber and the pressing piston may be mold elements, the pressing chamber is movable for her coverage of the dose of metal held by the electromagnetic field of the inductor.

 When applying the present invention, the heat transfer time between the dose of the metal and the pressing chamber is reduced by replacing the supply of metal to the pressing chamber with a free-falling dose with an acceleration equal to the acceleration of gravity, moving the pressing chamber with the coverage of the metal dose held by the electromagnetic field. The supply of metal with a free-fall dose requires a time equal to the square root of the quotient of dividing the double movement by the acceleration of gravity. For example, when moving 0.25 m, the time is ≈0.2 s. The time it takes for a metal dose to be moved by a pressing chamber has no physical limitations and can practically amount to hundredths of a second.

 Variants of devices for implementing the method are shown in figures 1-4.

 The device comprises a mold, consisting of half-molds 1, 2, a pressing chamber 3, a piston 4. An inductor 5 is located between the mold and the piston.

 In FIG. 1, 2, an embodiment of a device is shown where the pressing chamber and inductor are attached to the mold. Figure 1, the dose of metal is placed on the pressing piston and partially fixed by the electromagnetic field. Figure 2 the position of the elements after feeding the metal into the mold. By joint movement of the mold, the pressing chamber and the inductor, the dose of metal was covered by the pressing chamber, their further movement is limited by the forming elements of the mold, the pressing chamber and the pressing piston, and the dose of metal is fed into the forming cavity of the mold. The pressing piston in the described embodiment may be stationary.

 Figure 3, 4 shows a variant of the device in which the pressing chamber, inductor and mold are made with the possibility of mutually independent movements. FIG. 3 dose of metal placed on the pressing piston and partially fixed by the electromagnetic field. Figure 4 the position of the elements after feeding the metal into the mold. The initial movement of the pressing chamber produced coverage of the metal, followed by the movement of the pressing piston, the metal is fed into the forming cavity.

 In the implementation of the proposed method and device, the heat transfer time between the dose of the metal and the pressing chamber is hundredths of a second and it is significantly less than the heat transfer time compared to supplying the metal to the pressing chamber with a free-falling dose.

Claims (4)

 1. A method of injection molding, including holding a dose of metal by an electromagnetic field and supplying metal to the mold cavity of the mold by displacing the dose of metal from the pressing chamber, characterized in that the pressing chamber is moved before the metal is fed into the mold cavity to cover the dose of metal held by the electromagnetic by the field.  2. A device for injection molding, containing a mold, an inductor for holding a metal dose by an electromagnetic field, a pressing chamber and a pressing piston, characterized in that the pressing chamber is movable so that it can cover a metal dose held by the electromagnetic field.  3. The device according to p. 2, characterized in that the pressing chamber is attached to the mold with the possibility of joint movement with it.  4. The device according to claim 2, characterized in that the pressing chamber is configured to move independently of the mold.

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