CN1190285C - Antigravitational vacuum method and apparatus for asting Mg allor or Al alloy with lost mould - Google Patents

Abstract

The present invention relates to a method and a device thereof for counter-gravity casting, which can solve the problems of high requirements to a casting mold, complicated pressure regulating method and easy oxidation when liquid alloy is poured in the existing counter-gravity casting. The method comprises the following steps: (1) a casting pattern of a lost mold is put in a bottom pouring type sand box, and molding sand is added to be compactly vibrated; (2) molten magnesium and aluminum alloy is sent into a pouring furnace, and protective gas is led in; (3) pressure controllable inert gas is led in the pouring furnace, the molten alloy enters the sand box under the action of the inert gas, the casting pattern of the lost mold is gasified, and pouring is realized. The device is composed of a pouring furnace, a pouring platform on a furnace cover, a sand box placed on the pouring platform and a pouring pipe communicating the pouring furnace with the sand box, wherein a crucible with a stainless steel lining is arranged in the pouring furnace; a heat-insulation heating coil is coated outside the pouring pipe; the pouring furnace cover has a passage for protective gas and pressure controllable inert gas. The present invention combines the advantages of techniques of vacuum lost mold casting and counter-gravity casting and is suitable for the large-scale production of high-precision complicated magnesium and aluminum alloy castings.

Description

Magnesium, aluminum alloy anti-gravity vacuum lost foam casting method and equipment

technical field

The invention belongs to the field of alloy precision casting, and in particular relates to an anti-gravity casting method and equipment thereof.

Background technique

At present, the precision casting method of magnesium alloy parts is relatively simple, and most of them are formed by pressure casting method under gravity (accounting for ~90%), while a few magnesium alloy castings formed by sand casting under gravity have poor precision and surface roughness. . There are relatively many precision casting methods for aluminum alloy parts. The commonly used ones are: metal mold casting, pressure casting and lost foam casting under gravity filling and solidification, and low pressure casting, differential pressure casting and melting casting under anti-gravity filling and solidification. Die suction casting, etc.

Casting under gravity is likely to cause casting defects such as under-casting, looseness, and oxidation inclusions in castings. The disappearance casting of aluminum alloy under gravity is also prone to defects such as pores and pinholes. Metal molds are used in metal mold casting, pressure casting, low pressure casting, and differential pressure casting. Metal molds have poor air permeability, are prone to defects such as lame gas and insufficient pouring, and when the filling pressure is high, such as die casting, they are also prone to defects such as entrained air; the structure of the metal mold makes the structure of the castings produced There are also certain limitations, and it is difficult to produce castings with complex inner cavity structures.

Anti-gravity casting is a method of pouring liquid metal against gravity using pressure difference. In order to overcome the limitations of common anti-gravity casting methods, that is: the mold is required to have good air permeability, the mold is required to have high strength, and some anti-gravity casting methods, such as investment suction casting and low-pressure casting, are used in metal The feeding pressure during solidification is not enough, Zeng Jianmin, Zhou Yaohe proposed a pressure regulating casting method (CN1034876A). However, the control of the pressure regulating casting method is relatively complicated, and it is not suitable for mass industrial production, and can only be used for the production of aluminum alloy castings.

In addition, magnesium and aluminum alloys in the liquid state are easily oxidized and inhaled when in contact with air, and a large number of oxide impurities and pores are easily formed in the casting. Magnesium and aluminum alloys usually need additional gas protection when melting and pouring.

Contents of the invention

The magnesium and aluminum alloy anti-gravity vacuum lost foam casting method and equipment proposed by the invention can solve the above-mentioned problems in magnesium and aluminum alloy precision casting.

A magnesium and aluminum alloy anti-gravity vacuum lost foam casting method of the present invention comprises the following steps: (1) putting the lost foam casting pattern in a bottom injection sand box, adding molding sand, and vibrating for compaction. (2) The melted and refined magnesium and aluminum alloy metal liquids are sent to the pouring furnace for heat preservation and waiting to be poured, and the protective gas is introduced into the pouring furnace. (3) An inert gas with controllable pressure is introduced into the pouring furnace, and under the action of the pressure, the magnesium and aluminum alloy metal liquid enters from the bottom of the sand box, vaporizes the lost foam casting pattern, and forms magnesium and aluminum alloy castings after cooling and solidification .

The anti-gravity lost foam casting method of magnesium and aluminum alloy according to claim 1, characterized in that the sand box is vacuumed while anti-gravity pouring and filling are realized, and the vacuum degree is -0.08-0.02 MPa.

The magnesium and aluminum alloy anti-gravity lost foam casting method according to claim 1 or 2, characterized in that the pressure of the inert gas for filling and pouring is adjusted within 0.01-0.5 MPa, and the pressure of the protective gas is varied within 0.005-0.05 MPa.

The magnesium and aluminum alloy anti-gravity lost foam casting method according to claim 1 or 2, characterized in that the protective gas can be CO ₂ , SO ₂ , Ar, SF ₆ or a mixed gas with SF ₆ and the aforementioned gases; The pressure-controllable inert gas is _CO2 or Ar.

The magnesium and aluminum alloy anti-gravity lost foam casting method according to claim 3, characterized in that the protective gas can be CO ₂ , SO ₂ , Ar, SF ₆ or a mixed gas with SF ₆ and the aforementioned gases; The pressure-controlled inert gas is _CO2 or Ar.

A magnesium and aluminum alloy anti-gravity vacuum lost foam casting equipment. The pouring furnace includes a crucible, a pouring table placed on the pouring furnace cover, and a sand box with an opening at the bottom placed on the pouring table. The pouring pipe is fixed on the pouring furnace cover and passes through the pouring table. The crucible and the sand box are connected, and it is characterized in that: (1) the crucible has a stainless steel furnace lining, and there is a thermal insulation layer between the stainless steel furnace lining and the pouring furnace wall; (3) The pouring furnace cover has passages through protective gas and inert gas with controllable pressure respectively.

The magnesium and aluminum alloy anti-gravity vacuum lost foam casting equipment as claimed in claim 4 is characterized in that: (1) the wall of the sand box has a vacuum pipe, (2) the upper end of the pouring pipe has a passage for the protective gas, (3) A liquid level sensor is installed on the pouring furnace cover.

The advantage of the present invention is that it skillfully combines vacuum lost foam casting and anti-gravity low-pressure casting with controllable air pressure, and combines the technical advantages of vacuum lost foam casting, anti-gravity casting and pressure-regulating casting, and can cast precise, thin-walled castings. , complex magnesium-aluminum-gold castings; the entire pouring and filling process is completed under the protection of inert gas and the reducing atmosphere after lost foam gasification, which is very suitable for the casting characteristics of magnesium and aluminum alloys; it is easy to realize the automation of the production process. The invention is suitable for mass production of magnesium and aluminum alloy castings.

The invention is suitable for mass industrialized production of complex, thin-walled, high-precision magnesium and aluminum alloy castings in industries such as automobiles, aviation, aerospace and the like.

Description of drawings

Fig. 1 is a schematic diagram of the casting equipment involved in the present invention.

Detailed ways

Example 1:

The melting furnace melts and refines the magnesium and aluminum alloy molten metal, and sends it into the pouring furnace through the siphon tube to keep warm and wait for pouring. The pouring furnace is filled with protective gas CO ₂ , the pressure is 0.02MPa, and the vibration is tight. The sand box is sent to the top of the pouring table through rails or car lifting equipment, and the position is waiting for pouring. The sand box is vacuumed, and then the inert gas CO ₂ with controllable pressure is introduced into the pouring furnace, the pressure is 0.2MPa, and the vacuum is pumped. The hourly vacuum degree is -0.04MPa, realizing anti-gravity vacuum casting.

Example 2:

The melting furnace melts and refines the magnesium and aluminum alloy molten metal, and sends it into the pouring furnace through the electromagnetic pump to moisturize and wait for pouring. The pouring furnace is filled with protective gas Ar, the pressure is 0.008MPa, and the sand box is vacuumed. The vacuum degree is -0.06MPa. The inert gas fed into the vibrating pressure is also Ar, with a pressure of 0.05 MPa, and the others are the same as in Example 1.

The equipment for anti-gravity vacuum casting is shown in Figure 1, where 1 is the lost foam casting pattern, 2 is the bottom injection sand box, 2 is the molding sand filled in it, 4 is the vacuum pipe for the sand box, and 5 is the mobile sand box 6 is the pouring table, which is placed on the furnace spring 8 of the pouring furnace 7, 9 is the crucible, 10 is the stainless steel lining, 11 is the heating coil, 12 is the heat insulation layer, 13 is the pouring pipe, and 14 is the heat preservation Heating coil, 15 is the channel for the protective gas, 16 is the channel for the controllable pressure inert gas, 17 is the liquid level sensor, which detects and controls the position of the molten magnesium and aluminum alloy in the crucible, 18 is the melting furnace, 19 for the siphon.

Claims (7)

1. a magnesium, aluminum alloy antigravity vacuum lost foam casting method, comprises the steps: (1) Put the lost foam casting pattern in a bottom injection sand box, add molding sand, and vibrate tightly. (2) The melted and refined magnesium and aluminum alloy metal liquids are sent to the pouring furnace for heat preservation and waiting to be poured, and the protective gas is introduced into the pouring furnace. (3) An inert gas with controllable pressure is introduced into the pouring furnace, and under the action of the pressure, the magnesium and aluminum alloy metal liquid enters from the bottom of the sand box, vaporizes the lost foam casting pattern, and forms magnesium and aluminum alloy castings after cooling and solidification . 2. The magnesium and aluminum alloy anti-gravity vacuum lost foam casting method according to claim 1, characterized in that the sand box is evacuated while the anti-gravity pouring and filling is realized, and the vacuum degree is -0.08～-0.02MPa. 3. The magnesium and aluminum alloy anti-gravity vacuum lost foam casting method according to claim 1 or 2, characterized in that the pressure of the inert gas for filling and pouring is adjusted within 0.01-0.5 MPa, and the pressure of the protective gas is 0.005-0.05 MPa internal changes. 4. The magnesium and aluminum alloy anti-gravity vacuum lost foam casting method according to claim 1 or 2, characterized in that the protective gas can be CO ₂ , SO ₂ , Ar, SF ₆ or a mixture of SF ₆ and the aforementioned gases Gas; the pressure-controllable inert gas is CO ₂ or Ar. 5. The magnesium and aluminum alloy anti-gravity vacuum lost foam casting method according to claim 3, characterized in that said protective gas can be CO ₂ , SO ₂ , Ar, SF ₆ or a mixed gas with SF ₆ and the aforementioned gases; The pressure-controllable inert gas is _CO2 or Ar. 6. A magnesium and aluminum alloy anti-gravity vacuum lost foam casting equipment. The pouring furnace includes a crucible, a pouring table placed on the pouring furnace cover, and a sand box with an opening at the bottom placed on the pouring table. The pouring pipe is fixed on the pouring furnace cover through the The pouring table connects the crucible and the sand box, and is characterized in that: (1) The crucible has a stainless steel furnace lining, and there is a thermal insulation layer between the stainless steel furnace lining and the pouring furnace wall, (2) The pouring tube located in the total value of the pouring table is covered with heat preservation and heating coils, (3) The pouring furnace cover has passages for protective gas and inert gas with controllable pressure respectively. 7. Magnesium, aluminum alloy antigravity vacuum lost foam casting equipment as claimed in claim 6, is characterized in that: (1) The wall of the sand box has a vacuum pipe, (2) The upper end of the pouring tube has a passage for the protective gas, (3) A liquid level sensor is installed on the pouring furnace cover.