SU1321517A1 - Method of die-casting with controllable pressure - Google Patents

Abstract

The invention relates to foundry, in particular, to pressure-controlled casting, mainly aluminum alloys. The aim of the invention is to increase the yield of and the expansion of the casting range. The melt with the mixed aluminum powder under the action of gas pressure fills the form consisting of a matrix and movable inserts 8 and 9. After filling the mold, the movable inserts 8 and 9 are cyclically moved apart and returned to the initial position, which ensures the melt movement before the growing crust and its modification fragments of growing crystals. After solidification of the casting, it is crimped by applying to the movable inserts 8 and 9 a force exceeding the yield strength of the cast material. 1 hp f-ly, 2 il .- CO e el |

Description

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The invention relates to a foundry, in particular to casting under controlled pressure, mainly aluminum alloys.

The purpose of the invention is to follow the yield and expand the casting range.

FIG. 1 shows the installation, general view; in fig. 2 - the form at the time of implementation of the plastic deformation of the casting, section.

The method is carried out as follows.

The molten metal 1 is poured into the crucible 2, installed in the autoclave 3. The latter is closed with a lid 4, in which the metal conduit 5 is installed with a heater 6, the Foundry mold consists of a matrix and movable inserts 8 and 9.

In the initial position, the movable inserts 8 and 9 are set symmetrically to the axis of the metal conductor at a distance corresponding to the wall thickness of the casting Sf ,. In autoclave 3, gas pressure is created, under the action of which the melt fills the mold. Immediately after filling the mold, the movable inserts 8 and 9 are diluted, providing an additional influx of metal, modifying the effect of which on the structure is manifested in that it blurs the forming crystals and dissolves them in the total mass of the metal. Then inserts 8 and 9 are returned to their initial position, displacing excess metal into the crucible. The operation of expanding and bringing together the movable inserts can be carried out several times,

After the casting is solidified, the gas pressure is removed and the casting is pushed out of the mold cavity. The speed of movement of the metal relative to the crystallized crust and the multiplicity of repetition of the cycles of filling and displacing excess metal are coordinated with the linear growth rate of the crystals, until the thickness of the crystallized crusts on the opposite inserts reaches half the wall thickness of the casting. In addition, before pushing the casting out of the mold, pressure is applied to it from the side of the movable inserts, exceeding the yield point of the casting material, which provides calibration due to local plastic deformations over the top and bottom of the casting.

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An example. Casting is made of aluminum alloy Al 1 with dimensions 260x120x40 mm. In the alloy, to give the casting special properties, 2-3 wt.% Of aluminum powder is kneaded, on the surface of which there is a film of refractory oxide Al20. The primed composition is poured into a ladle and thermostatically controlled at a certain temperature in an autoclave 3 (Fig. 1). - The autoclave is sealed with a crunch 4 and a constant pressure from the range of 1.2-1 is supplied to the melt mirror. In order to avoid solidification of the metal in the metal pipe 5, a special heater 6 is provided. Under the influence of gas pressure, the melt fills the cavity of the mold. The crystallization of the casting starts from the walls of the movable inserts, as well as from the matrix. At the same time, in castings of a complex configuration with variable wall thickness, shrinkage shells and friability may occur, an adverse coarse-crystalline structure is formed. Therefore, immediately after filling in the mold, the movable inserts 8 and 9, which are connected to the corresponding mechanisms, for example, the hydroprocess, are diluted by distance S, 28, i.e. 80 mm, thus providing additional metal flow. Then inserts 8 and 9 are returned to their original position, displacing excess metal into the crucible. Empirically or by calculation it is established that the average speed of the inserts, whose initial temperature is 250 ° C, and the melt temperature 640 ° C, should be 10 mm / s. At the end of one cycle, the crystal is 1 Sj, / 2 20 mm. The gas pressure is removed from the melt, the natural level of the melt is restored in the metal pipe, and the casting by force of the press is moved in the matrix from right to left and before pushing out of the cavity of the matrix, force P | 140 x XY N (Fig. 2), which provides calibration of the casting, due to local plastic deformation at contact pressures P | 4.5 x xy pa

The resulting casting has a metal utilization factor close to unity. Technological allowances and metal overlaps are minimal. The casting is distinguished by a uniform fine grain313215

clear structure. Defects in the form of porosity, loosening, shells are absent.

Claims (2)

1. The method of pouring under regulated 15, pressure, including filling the form of /////////////////// Л H - / V ///////. Compiled by V. Mayorov Editor A. Kozoriz Tehred M. Morgental Proofreader Order 2702/7 Circulation 740 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 174 we melt, suction under gas pressure, melt modifying in the mold, relieving the gas pressure and casting extraction, characterized in that, in order to increase the yield of the suitable and expand the casting range, the melt modification is carried out by cyclic dilution of the half-form and return them to the original position. 2. The method according to p. 1 . u and u with distinguish that before extracting castings from the mold to it apply a pressure exceeding the limit of the current of the casting material. Ph 0 7 ///////.