KR19990067941A - Process for obtaining non-ferrous metal castings by greensand mould casting - Google Patents

Abstract

The process according to the invention dries the cavity 3 of the green mold mold 1 in which the molten metal is cast to obtain each casting, before the mold filling step so as to remove moisture and avoid holes in the finished casting. The cavity 3 is dried. In order for the cavity in the mold 1 to dry, the mold has a recess 2 so that hot air is applied through the upper hood 4 of the drying station and a negative pressure or vacuum is applied to the bottom sink ( 6), hot air flows between the cavity 3 in the mold 1, moves towards the mold recess 2, removes moisture from the mold 1 and drains the water to the bottom sink ( Move toward 6).

According to another embodiment, the mold 1 ′ has a through recess 2 ′, which is provided in the sector of the installation where the appropriate mold 1 ′ is transferred from the mold chamber to the filling station. The recess 2 'is provided by the perforations 21 of each rod 20 which can be moved up and down.

Description

PROCESS FOR OBTAINING NON-FERROUS METAL CASTINGS BY GREENSAND MOULD CASTING}

The present invention relates to a process for obtaining a nonferrous metal casting, for example aluminum casting. The molten metal is cast in a green mold mold, which is based on drying the mold before casting the metal to remove moisture so that micropores do not form in the finished casting.

It is an object of the present invention to provide molds of the type of vertical green yarn having recesses, each mold cavity being subjected to hot air flow to be dried by vacuum. It is another object of the present invention to provide a method of drying a mold to quickly solidify the casting runaway and to quickly remove the mold, filling the mold and then preventing the casting runaway using a cooled plunger.

Another object of the present invention is to increase the production efficiency by providing a recess to quickly process the vacuum operation over the entire mold so that the molten metal fills all mold gaps or channels when cast into the mold. A recess to increase production efficiency will be provided when the mold is in the actual line moving from the filling station.

Casting of non-ferrous metal castings in green mold molds is inconvenient because the green mold carries a large amount of water, that is, 3.5% -4% of water together. This means that the finished casting has a number of holes in its outer face.

The outer surface in contact with the hot molten metal is overheated to cause evaporation in the mold, and aluminum absorbs hydrogen dissociated from the water, forming a large amount of micropores in the casting surface.

One way to improve the outer face of the resulting casting is to quickly solidify the molten metal in the mold. Several methods of rapidly cooling the molten metal are known, some of which are described below:

There is a method of casting molten metal in a metal mold, which cools quickly. However, this method is inconvenient because the cost of making the mold is too high and the production capacity is limited.

There is a method of making a mold from magnetic minerals, which allows the molten metal to cool and solidify rapidly and the casting to have a better microstructure. This method is described in PCT patent WO96 / 11761.

There is a method of making a mold from several parts made of different materials, one of which is made of a metal with high metal conductivity as a means of removing heat from the molten metal. This method is described in EP 0,557,374.

Recesses and cores made to reduce weight and cost are known in the basic industry, but green molds with recesses have been produced to make it easier to remove the moisture contained in the raw mold.

In addition, when the aluminum is cast, several experimental data show that it is convenient to maintain the natural humidity of the green mold mold, because moisture may be instantaneously generated during the casting process of the oxide surface film which protects the casting.

Nevertheless, due to the complexity of current casting structures made of aluminum, it is generally difficult to completely fill molten metal into the gaps of the mold. This filling process is enhanced by introducing a vacuum, which is very useful for providing a hole through the mold for this purpose.

The process described herein can sufficiently overcome the aforementioned drawbacks by drying the mold prior to the molten metal casting process to remove moisture present in the mold and to prevent the formation of holes in the outer side of the finished casting.

The process according to the invention thus consists of the following process:

Hot air flows through the mold to provide the green mold mold with a number of recesses that remove the green mold moisture.

A casting station includes a drying station, where the mold applies hot air to attract and move the moisture contained therein. The process of transferring water using hot air is directed towards the recess to remove water and the drying Since the station has an upper hood, a side plate and a lower discharge sink, the mold is placed in a fully enclosed chamber and allows negative pressure to be applied through the discharge device to generate hot air, on the inner wall of the cavity, Moisture in the mold is moved towards the recess and from the recess to the discharge device.

This process is dried in a chamber consisting of an upper hermetic plate (driven by a hydraulic cylinder), a side plate and a bottom gas exhaust system to create a vacuum in the chamber to remove air and gas present in the mold cavity before casting. Inserting the mold.

The process according to the invention involves the process of fitting a casting runaway, once the mold is filled, it is blocked by a plunger driven by a cylinder, which is fitted into the inner chamber and air or through the chamber to cool the end. As the liquid flows to solidify the casting runaway quickly, the mold is removed quickly and a new cycle is started, increasing the productivity of the machine.

When the aluminum is cast, the recess is provided through the mold so that the metal completely fills the mold space, and once the mold is placed in a line that carries it towards the filling and casting station to facilitate vacuum, the mold The recess is provided to be made, and the molten metal is cast by imparting a vacuum to promote filling of the mold.

In this case, the recesses formed in the mold are made to facilitate vacuum operation through the mold so that the molten metal completely fills all the gaps in the mold.

Another feature of the invention relates to an apparatus for providing a recess through a mold, which is built on a plurality of rods having sharp portions, which are driven by a motor to penetrate through the mold. Pass the bore out of the mold.

A device with a through hole has a central piston and a guide for proper utilization of the rod, which can be used to vertically move the above-described through hole, and a side piston is also provided to freely change the position of the rod relative to the mold. This allows the most ideal bore to be provided in size, and the bases in which each row of molds are supported and sliding have a longitudinal slot which allows the rods to pass through in all possible positions they occupy. Allow.

BRIEF DESCRIPTION OF THE DRAWINGS In order to more easily understand the features of the present invention, the drawings according to preferred embodiments are attached, which are purely illustrative:

1 shows a mold used in the process of the present invention.

2 shows the forward movement of the mold moving towards an area equipped with a drying station.

3 is a cross-sectional view taken along the line A-A of FIG.

4 shows a drying mold inserted in a filling station, which includes a top closure plate, a side plate and a vacuum and exhaust system lying on the bottom.

5 shows the mold in the filling step after the top and side plates shown in FIG. 4 separated from the mold are closed;

Fig. 6 is a view showing the entire casting mold and the mold blocked.

FIG. 7 shows that the mold is released after the casting ladle is depressurized and the casting bath cooling time has elapsed.

8 shows an installation in which a recess or a hole is formed through a mold, which is made before the metal is cast.

9 is a cross-sectional view taken along line B-B of FIG. 8;

FIG. 10 is a front view of a device in which a recess or hole is made through a mold in accordance with the embodiment shown in FIGS. 8 and 9;

* Sign Description

1 ... mold 2 ... recessed

3 ... internal cavity 4 ... upper hood

5 ... shroud 6 ... sink

7 ... top plate 8 ... side plate

9 ... exhaust system 10 ... charging channel

11 ... Casting Tongdo 12 ... Ladle

The process for obtaining the non-ferrous metal part is based on the dry production of the mold before casting the molten metal, as described above, so that the drying process removes moisture present in the mold and no micropores are formed in the finished casting. .

To achieve this, as shown in the figure, a mold 1 is required to form a plurality of recesses 2 for the entire mold, which recesses 2 use bottom plates with spikes acting as rods. Obtained. This recess 2 can be formed using side plates having spikes instead of bottom plates, in which case the recesses 2 of the mold 1 are arranged horizontally.

The mold enters the charger and is placed at the end of the row of molds, shown in FIG. 2, where a drying station is placed. The cavity 2 of the mold 1 allows hot air to flow from the internal cavity 3 of all the molds 1 towards the recess 2, and the drying station is precisely arranged to allow the hot air to flow, The station consists of a sealed side plate 5 and an upper hood 4 which hold the mold 1 free of leakage, and the drying station also includes a lower water storage and discharge sink 6, so that the hood 4 By blowing hot air and applying negative or vacuum pressure through the sink 6, heat is generated and moved from the internal cavity 3 of each mold 1 toward the recess 2, As the heat moves, the moisture contained in the mold is transferred to the drain sink 6. Since the method according to the invention dries the inner wall of the mold cavity 3, the outer face of the casting is processed better.

At the end of the drying process described above, the molds 11 are moved one by one to the filling station and as shown in FIG. 1, the molds are shown in the upper closure plate 7, the side plates 8 and driven in FIG. As such, it lies between the vacuum and gas exhaust system 9 lying on the floor. The mold 1 has a suitable filling channel 10 facing the casting runway 11, and as shown in FIG. 4, the casting ladle 12 leads to a molten metal tank equipped with an enclosed charge 13. After the plates 7 and 8 are firmly fixed and pressurized through the conduit 14, they are pressurized by pneumatic and electromagnetic pump systems, and the molten metal is cast against the mold 1 as shown in FIG. 5. Once the mold is filled, the casting runway 10 blocks the plunger 15 driven by the hydraulic and pneumatic cylinders 16, which plunger 15 defines the inner chamber 17. Air or liquid flows through this inner chamber, which allows the end 18 to cool, causing the casting runaway 10 to solidify quickly, so that the mold 1 can be removed quickly at the start of a new cycle.

When the casting runway 10 cooling time ends and the casting ladle 12 is depressurized, the plates 7, 8 are removed to pull the mold 1 out of the filling station to start a new cycle.

In another embodiment of the invention shown in FIGS. 8, 9 and 10, the recess 2 ′ passes through the mold 1 ′ and the mold 1 ′ from the mold chamber 29 in FIG. 8 is filled with molten metal. And a recess 2 'that passes through the casting station and passes through the hole, as is clearly shown in FIGS. 8 to 10 in the sector 18 of the station, which through recess or hole 2' Provided to facilitate vacuum operation throughout (1 '), the molten metal completely fills all spaces therein.

The through recesses 2 'are made of the device shown in Figs. 8 and 10 in Fig. 19, which are a number of rods 29, motors and respective pulleys and toothed belts with through points 21 at the unfixed ends. (23) a transmission, wherein the rod 21 drills each mold 1 'through the penetrating point 21, so that a through recess 2' is obtained, as shown in FIGS. In order to provide the through bore or recess, the rod 20 needs to be moved upwards while being driven by a central piston 24, which moves up and down with the aid of the guide device 25.

A transverse piston 26 is also provided, which allows the position of the rod 20 to be freely translated relative to the mold 1 'so that it can be provided in the most suitable position, depending on the morphological characteristics of the mold.

The base on which the mold 1 'is supported and on which the sliding motion of the mold takes place is provided with longitudinal slots 27 in each sector 18 which allow the rod 20 to pass through the various positions in which the slots are placed. .

As shown in Figs. 8 and 9, each mold 1 'is kept tightly closed by closing the top plate 7' and the side plate 8 ', and a vacuum collector 28 is provided, through which the vacuum is collected. This is applied to improve the casting of the molten metal in the mold and a vacuum is applied across the through recesses 2 'of each mold 1', thus filling all the gaps.

The process according to the present invention can sufficiently overcome the disadvantages of the prior art by drying the mold prior to the molten metal casting process to remove moisture present in the mold to prevent the formation of holes in the outer side of the finished casting. have.

Claims (3)

In the process for obtaining a non-ferrous metal casting by green mold casting, Providing a recess (2,2 ') in the green mold mold (1,1') to allow the flow of hot air to remove the raw mold moisture and create a vacuum to fill all mold gaps; Inserting the mold (1,1 ') into a drying station formed in a suitable filling device, consisting of a top plate (4) and a side plate (5) which keeps the plurality of molds (1,1') tightly sealed together; Impart a negative pressure or vacuum through the bottom sink 6 and blow hot air towards the mold recesses 2, 2 'between the cavities 3 in the molds 1, 1'. Moving, removing moisture and redirecting the removed moisture toward the bottom sink 6; After drying, the mold (1,1 ') is passed through a suitable filling station, consisting of a top closure plate (7,7'), side plates (8,8 ') and a vacuum and gas evacuation system (9) on the floor. process; Filling the mold by applying pressure to a suitable casting ladle 12, wherein gas contained in the internal cavity of the mold 1, 1 ′ is discharged through the bottom vacuum and gas exhaust system 9; -Filling the mold (1, 1 ') using the plunger 15 driven by the hydraulic cylinder (16) and then blocking the casting inlet (10), and cooling to pass to the mold (1,1') Gas or liquid is applied inside the chamber 17 formed in the plunger 15 to solidify the water supply 10; Depressurizing the casting ladle 12, keeping the water run 10 connected to the mold 1, 1 ′ blocked and venting gas; The top plate 7, 7 ′ and the side plate 8, from the filling station, after the cooling time of the casting runway 10 connected to the mold 1, 1 ′ has ended, in order to remove the mold and start a new cycle. 8 ') to obtain a non-ferrous metal casting by green mold casting, characterized in that the process consists of removing. 2. The sector 18 according to claim 1, wherein the recesses 2 ′ are suitably passed through the mold 1 ′ and the mold 1 ′ is transferred from each mold chamber 29 to the molten metal filling and casting station. Through-holes 2 'are provided at each of the unfixed ends of the rod 20, which are vertically moved by the piston 24 and driven by the motor 22 to pivot. A process for obtaining a non-ferrous metal casting by raw mold casting, characterized in that obtained by. 3. The position of the rod 20 is changed relative to the mold 1 ', and the longitudinal slots 27 allow the rod 20 to move through various positions in which the rod 20 is formed. A process for obtaining a non-ferrous metal casting by raw mold casting, characterized in that the mold (1 ') is provided on a supported and sliding base.