KR101272491B1 - Cooling rate control die-casting device and method - Google Patents

Abstract

The present invention relates to a die-casting apparatus for injecting molten metal into a mold to produce a casting in the shape of a mold. The present invention relates to a sleeve in which a molten metal is introduced and connected to a mold, and a plunger for supplying the molten metal at a predetermined pressure. Including but the sleeve includes a heater for controlling the temperature of the melt. In addition, the present invention relates to a die casting method for manufacturing a casting in the shape of the mold by injecting the molten metal inside the mold, the step of injecting the molten metal into the sleeve through a tube in a heating furnace, cooling the molten metal at a predetermined cooling rate And inserting the molten metal into the mold with the plunger. The present invention provides an apparatus and a method capable of producing an alloy having excellent properties without using an electromagnetic generator and an ultrasonic generator.

Description

Cooling rate control die-casting device and method

Embodiments of the present invention relate to a die casting apparatus and method for controlling the cooling rate.

A general die casting apparatus is a device used to obtain a metal product corresponding to a cavity of a mold by injecting molten metal into a die casting mold and allowing a predetermined time to cool in the cavity of the die.

The molten metal stays in the sleeve which is part of the diecasting apparatus before the molten metal is injected into the die casting mold. In addition, the molten metal is preserved in the ladle before the molten metal is introduced into the sleeve. In this case, in general, an electromagnetic field stirring or an ultrasonic wave generator is installed on the molten metal in the ladle and the sleeve to expose the molten metal to electromagnetic waves or ultrasonic waves. In this process, as the molten metal in the liquid state passes through the sleeve and the temperature drops, the molten metal in the liquid state gradually changes into a solid / semi-melted state in the solid-liquid coexistence state. At this time, nucleated primary dendrites are formed, which prevents the crystals from growing. In order to prevent the generation of primary dendrite, the generation of primary dendrite, which is formed first through electromagnetic fields or ultrasonic vibrations, is suppressed or broken, leading to the formation of finer and more uniform crystal nuclei.

However, the installation of the electromagnetic stirring device or the ultrasonic wave generator in the ladle, the sleeve as described above has a problem that the volume of the device becomes large. In addition, there is a possibility that a large space in the sleeve is not affected by electromagnetic fields or ultrasonic waves, turbulence occurs due to stirring, and air is contained in the slurry in a sealed manner.

Moreover, it is practically difficult to install the electromagnetic generator coil in the sleeve due to space constraints.

One embodiment of the present invention is a die casting apparatus or die casting method that can suppress the generation of primary dendrites without electromagnetic stirring or ultrasonic generator.

In order to achieve the above object, a die-casting apparatus for producing a casting in the shape of the mold by injecting the molten metal into the mold according to the present invention is a sleeve in which the molten metal is introduced and connected to the mold, the molten metal at a predetermined pressure in the mold. And a plunger, the device for supplying, wherein the sleeve comprises a heater for controlling the temperature of the melt.

In an embodiment, the sleeve includes a temperature controller, and the temperature controller controls the heater to maintain the melt temperature in the sleeve at a predetermined temperature or to cool at a predetermined cooling rate.

By way of example, the sleeve is made of stainless steel material.

The die casting method of manufacturing a casting in the shape of the mold by injecting the molten metal into the mold according to the present invention comprises the steps of (a) injecting the molten metal into the sleeve through a tube in a heat insulating furnace, (b) the molten metal at a predetermined cooling rate Cooling, and (c) inserting the melt into the mold with a plunger.

As an embodiment, the step (b) is the step of cooling the temperature of the molten metal in the sleeve at a rate of 0.02 ℃ / s at 550 ℃ ~ 600 ℃, the temperature of the molten metal in the sleeve before the step (b) is 550 ℃ ~ Maintaining 600 ° C.

As an embodiment, the step (b) is the step of cooling the temperature of the molten metal in the sleeve at a rate of 0.003 ℃ / s at 610 ℃ ~ 650 ℃, the temperature of the molten metal in the sleeve before the step (b) is 610 ℃ ~ Maintaining 650 ° C.

In an embodiment, the step (c) includes inserting the mold into the mold by applying a pressure with a plunger after the molten metal is held in the sleeve for 60 seconds to 1200 seconds.

The effect according to an embodiment of the present invention is to eliminate the need to install an electromagnetic stirring device, ultrasonic generator in the die casting device to reduce the volume of the device and to improve the complexity, to increase the productivity by reducing the time the molten metal stays in the ladle or sleeve It is possible to implement the process simplification.

1 is a diagram of a typical die casting apparatus.
Figure 2 is a schematic diagram of a die casting apparatus which is one embodiment of the present invention.
3 is a photograph of the surface of the alloy according to the first embodiment of the present invention.
4 is a photograph of the surface of the alloy according to a second embodiment of the present invention.
5 is a flowchart of a die casting method according to the first embodiment of the present invention.
6 is a flowchart of the die casting method of the second embodiment of the present invention.

The embodiments may be embodied in many different forms and should not be construed as limited to the aspects set forth herein. Rather, the above aspects make the embodiments more thorough and complete, and fully convey the scope of the embodiments to those skilled in the art. Although terms referring to first, second, etc. may be used herein to describe various components, it will be understood that the components are not limited to these terms. These terms are only used to distinguish one component from another.

It will be described below with reference to the drawings.

1 is a diagram of a typical die casting apparatus.

As shown in FIG. 1, a general die casting apparatus includes a heating furnace 30, an electromagnetic wave generator 50, a sleeve 10, a plunger 20, and a mold 40. The electromagnetic wave generating device 50 for electromagnetic stirring is disposed on the insulating furnace 30 in which the molten metal is stored so that the molten metal is exposed to electromagnetic waves. The molten metal in the heating furnace is sucked by the tube connected to the sleeve 10 so that a predetermined amount is moved to the sleeve 10. The molten metal moved to the sleeve 10 is pressed by the plunger 20 to move to the mold 40. The mold 40 has a cavity having a desired shape therein, so that the molten metal is infiltrated and the mold is cooled to produce a product to be manufactured.

An embodiment of the present invention relates to an apparatus for producing a metal alloy without applying an electromagnetic wave by the electromagnetic wave generator shown in FIG. 1 or applying ultrasonic waves by the ultrasonic wave generator as shown in FIG.

The reason for applying the electromagnetic wave is that as mentioned above, the liquid molten metal moves out of the heating furnace and moves to the sleeve through the connecting pipe, and the temperature of the molten metal is lowered while moving in the connecting pipe that cannot preserve the temperature of the molten metal. In addition, the molten metal that reaches the sleeve also prevents the formation of primary dendrite due to the temperature drop while passing through the sleeve.

The molten metal in the liquid state gradually changes to the reaction solid / semi-melted state in the solid-liquid coexistence state. When the temperature decreases, nucleated primary dendrites are formed. But as the molten metal solidifies, primary dendrite prevents other crystals from growing. Electromagnetic fields or ultrasonic waves are used to suppress the generation of primary dendrite and to induce the formation of uniform crystal nuclei by destroying the primary dendrite. In the case of an alloy in which primary dendrite is produced, non-uniform particles are formed upon melting by reheating, thereby impairing the properties of the alloy.

One embodiment of the present invention is a die casting apparatus for manufacturing a casting in the shape of the mold by injecting the molten metal into the mold, the apparatus for supplying the molten metal at a predetermined pressure to the sleeve, the mold is introduced and connected to the mold Including an plunger, wherein the sleeve includes a heater for controlling the temperature of the melt.

Figure 2 is a schematic diagram of a die casting apparatus which is one embodiment of the present invention.

As shown in FIG. 2, the die casting apparatus of one embodiment of the present invention does not include an electromagnetic wave generator or an ultrasonic wave generator for electromagnetic stirring. The molten metal in the heating path flows into the sleeve 100 through a connecting pipe.

The sleeve 100 may be manufactured to withstand high temperatures and strong pressures, and is preferably made of stainless steel. Typically, mechanical sleeves or mold sleeves may use SKD heat resistant steel to prevent deterioration damage by hot liquid metal.

The sleeve 100 includes a heater 120 for controlling the temperature of the molten metal. The heater 120 may allow the molten metal to maintain a set temperature or allow the molten metal to be cooled or heated at a predetermined speed. As shown in FIG. 2, the heater 120 may be arranged to surround the sleeve 100, and the sleeve 100 may include a thermostat (not shown), and the thermostat may adjust the heater 120 in the sleeve. Adjust the melt temperature to cool down to the preset cooling rate.

When the plunger 200 is a component of the pressurizing device and the liquid metal is supplied to the sleeve 100, the plunger 200 presses along the sleeve 100 to supply molten metal to the mold. Pressurization may be implemented through pneumatic or hydraulic cylinders. The mold may typically consist of two types, stationary and movable.

Hereinafter, an operation state of the die casting apparatus as an embodiment of the present invention shown in FIG. 2 will be described.

The molten metal stored in the thermal furnace 300 is introduced into the sleeve 100 by being pulled up. The molten metal in the sleeve 100 reaches a specific temperature by a preset temperature controller (not shown), and is cooled at a predetermined cooling rate from the preset specific temperature. The time for supporting the molten metal in the sleeve 100 can also be adjusted according to the characteristics of the alloy. After the supporting time passes, the plunge 200 compresses the molten metal in the sleeve 100 by a pneumatic or hydraulic cylinder and the molten metal is introduced into the mold.

The molten metal introduced into the mold 400 is cooled to form a metal alloy of a desired shape.

Finally, the prepared metal alloy is classified into grain size, average shape (Avg. Shape factor), and morphology (Morphology) to determine the superior and superior properties of the manufactured metal alloy. Especially in the crystal form, the alloy which cooled the molten metal by electromagnetic stirring or ultrasonic application does not produce a dendrite.

In order to prevent the dendrites from being generated, the dendrite is not generated in the crystal form by controlling the cooling rate of the molten metal in the sleeve as in the embodiment of the present invention in addition to electromagnetic stirring and ultrasonic application.

Cooling rate (° C / s) Support time Average grain size
(Μm) Mean shape factor Crystal form 0.02
(570 ℃) 60 104 0.56 Dendritic 300 142 0.63 Rosette 600 168 0.58 Rosette 1200 190 0.65 Rosette 0.003
(630 ℃) 60 31 * 0.10 Dendritic 300 36 * 0.08 Dendritic 600 137 0.65 Equiaxed 1200 162 0.53 Dendritic

* Is the dendrite arm

In one embodiment of the present invention by controlling the cooling rate was investigated the crystal form. In one embodiment of the present invention used a 5000 series A5052 alloy used in ships, vehicles, building materials, electrical / electronic components and in the first embodiment the molten metal is moved to the sleeve in the heating furnace after the initial temperature is 570 ℃ Cooled at 0.02 ° C./s. In addition, the second embodiment, the average grain size, average shape, and crystal form when the molten metal is cooled to 0.003 ° C / s at an initial temperature of 630 ° C after moving to the sleeve will be described.

Table 1 shows the experimental data according to an embodiment of the present invention.

The holding time means the time that the molten metal stays in the sleeve. The first embodiment is data when the initial temperature of the molten metal in the sleeve is 570 ° C, and stays in the sleeve for 60 seconds, 300 seconds, 600 seconds, and 1200 seconds while cooling to 0.02 ° C / s. Similarly, the second embodiment is data when the initial temperature is 630 ° C. and is 60 seconds, 300 seconds, 600 seconds, and 1200 seconds in the sleeve while cooling to 0.003 ° C./s.

The average grain size is the size at which crystals (nuclei) grow by observing the surface of the alloy. The smaller the average grain size, the finer the crystal structure, the more durable the alloy.

The average shape factor is a measure of the degree to which the grown crystal is circular. This is determined by determining whether the outer edge of the crystal becomes an arc that is part of a circle having a certain radius. The average shape factor is less than 0 and less than 1. The closer to 1, the closer to the circle shape.

The average shape factor is not a criterion that greatly affects the properties of the alloy, but the closer the value is to 1, the more desirable the alloy properties are.

3 is an actual photograph of the surface of the alloy according to the first embodiment of the present invention.

As shown in Fig. 3, the initial temperature of the molten metal was cooled to 0.02 ° C / s at 570 ° C, immersed in a sleeve for 60 seconds, 300 seconds, 600 seconds, and 1200 seconds, and then compressed by a plunger to insert the molten metal into a mold. The surface of the alloy has various forms.

The average grain size was 104 µm for 60 seconds, and the average shape factor was 0.56. Although the average grain size is relatively small, the strength of the alloy due to the fine particles is expected to be large, but it is not suitable to carry out the operation with a supporting time of 60 seconds because the crystal form corresponds to the dendrite. That is, as mentioned above, when dendrites are formed, the properties are poor when the alloy is reheated. As shown in the 60s photograph of FIG. 3, the crystal grains are fine but dendrites are formed.

The average grain size was 142 µm and the average shape factor was 0.63 when 300 seconds were supported. The average grain size is slightly larger, but it is somewhat closer to the threshold value of 100 μm and the average shape factor is also closer to the circular shape than that of 60 seconds. The dendrite is not formed as a crystal in the form of a rosette, and the characteristics of the alloy are improved than when the alloy is supported for 60 seconds. As can be seen from the 300s photograph of FIG. 3, the average grain size is larger than that of 60s, but no dendrite is seen in the crystal form.

In the case of 600 seconds and 1200 seconds, dendrite is not formed in the crystal form as in the case of 300 seconds, but it can be confirmed through the photograph of FIG. 3.

4 is an actual photograph of the surface of the alloy according to a second embodiment of the present invention.

As shown in Fig. 4, the initial temperature of the molten metal was cooled to 0.003 ° C / s at 60 °, 300 seconds, 600 seconds, and 1200 seconds, and then squeezed with a plunger to insert the molten metal into the mold. The surface of the alloy has various forms.

In 60 seconds, the average grain size is 31 rather than the average grain size, and the average grain size is expected to be quite large. The mean shape factor is 0.10, which is far from the circular shape. In addition, it is not suitable to perform the operation with a supporting time of 60 seconds because the crystal form corresponds to dendrites. Since dendrites are formed, the properties are poor when the alloy is reheated. As shown in the 60s photograph of Fig. 4, dendrites are formed.

In the case of 300 seconds supporting, the result is similar to that of 60 seconds, which is not suitable for the alloy.

In the case of 600 seconds, the average grain size was 137 µm, and the average shape factor was 0.65, which is close to a circle. In addition, the crystal form is an alloy having excellent properties corresponding to isotropic crystal (equiaxed).

In the case where 1200 seconds are supported, dendrites are formed in the crystal form, and the characteristics of the alloy are not good. The surface of each alloy can be seen in the photograph shown in FIG.

As a result, according to the first and second embodiments, the alloys having excellent characteristics in the average grain size, the average shape factor, and the crystal form, which are the main factors for determining the properties of the alloy, are identified without electromagnetic stirring or ultrasonic application. Obtained by adjusting the cooling rate at temperature.

In the first embodiment, when 300 seconds are supported for 600 seconds and 1200 seconds, in the second embodiment, when 600 seconds is supported, an alloy having excellent characteristics is produced.

Hereinafter, a die casting method for producing an alloy by controlling the cooling rate of the molten metal, which is an embodiment of the present invention, will be described.

The diecasting method, which is an embodiment of the present invention, includes injecting molten metal into a sleeve through a tube in a heating furnace, cooling the molten metal, and inserting the molten metal into a mold with a plunger. The step of cooling the molten metal prevents dendrite from forming in the crystal form.

The die casting method of the first embodiment of the present invention described above will be described.

5 is a flowchart of a die casting method according to the first embodiment of the present invention.

As shown in FIG. 5, the molten metal is injected into the sleeve from the heat-containing furnace having the molten metal by the die casting method. (S1000) The molten metal may be injected in various ways. In the first embodiment of the present invention, the initial temperature of the molten metal is maintained at a specific temperature between 550 ° C and 600 ° C. (S2100) In particular, the heater is adjusted so that the initial temperature of the molten metal in the sleeve is 570 ° C. When the initial temperature of the melt reaches a temperature between 550 ° C. and 600 ° C., the melt is cooled at a rate of 0.02 ° C./s. (S3100) Thereafter, the melt supporting time in the sleeve is maintained at 60 to 1200 seconds. In the embodiment of the present invention, the result of the embodiment supported for 60 seconds, 300 seconds, 600 seconds, 1200 seconds was obtained. When the supporting time of the set molten metal in the sleeve elapses, the molten metal is inserted into the mold by applying pressure to the molten metal with a plunger (S4000).

6 is a flowchart of a die casting method of the second embodiment of the present invention.

As shown in Fig. 6, in the second embodiment of the present invention, the molten metal is injected into the sleeve from the heating furnace with the molten metal. (S1000) The heater is operated to maintain the temperature of the molten metal in the sleeve at 610 ° C to 650 ° C. (S2200), the temperature of the molten metal in the sleeve was cooled at a rate of 0.003 ° C / s at 610 ° C ~ 650 ° C. (S3200)

By the method according to the first and second embodiments of the present invention, an alloy having an excellent shape without dendrite formation in the crystal form of the alloy was produced, and in particular, only a cooling rate was achieved without electromagnetic stirring or ultrasonic exposure. By adjusting only it is possible to produce an alloy having excellent properties.

The scope of the present invention is not limited to the above-described embodiments but may be implemented in various forms of embodiments within the scope of the appended claims. Without departing from the gist of the invention claimed in the claims, it is intended that any person skilled in the art to which the present invention pertains falls within the scope of the claims described in the present invention to various extents which can be modified.

100 sleeve 120 burner
200 plunge 300 thermal furnace
400 mold

Claims (9)

mold;
A sleeve into which molten metal is introduced and connected to the mold; And
A plunger for supplying molten metal to the mold,
The sleeve includes a heater for controlling the temperature of the molten metal,
Before the sleeve is melted with a 5000 series A5052 alloy melt is supplied to the mold:
The molten metal in which the 5000 series A5052 alloy was melted was unsupported for 300 seconds to 1200 seconds while cooling at a rate of 0.02 ° C./s at 550 ° C. to 600 ° C., or
Die casting apparatus for supporting 600 seconds while cooling the molten metal melted the 5000 series A5052 alloy at 610 ℃ to 650 ℃ at a rate of 0.003 ℃ / s.
The method of claim 1,
The sleeve includes a temperature controller, the temperature controller is characterized in that for controlling the heater to adjust the temperature of the molten metal in the sleeve to be cooled to a predetermined cooling rate.
The method of claim 1,
And the sleeve is made of stainless steel.
(a) injecting molten metal of the 5000 series A5052 alloy into a sleeve through a tube in a heating furnace;
(b) cooling the molten metal at a predetermined cooling rate without stirring; And
(c) When the molten metal is cooled without stirring at a rate of 0.02 ° C / s at 550 ° C to 600 ° C, the molten metal is supported in the sleeve for 300 seconds to 1200 seconds, and then the molten metal is inserted into a mold by a plunger. Or
When the molten metal is cooled at a rate of 0.003 ° C./s at 610 ° C. to 650 ° C. without stirring, after casting the molten metal in the sleeve for 600 seconds, die casting comprising inserting the molten metal into a mold with a plunger. Way.
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