CN110899661A

CN110899661A - Negative pressure up-suction casting device and using method thereof

Info

Publication number: CN110899661A
Application number: CN201811097285.XA
Authority: CN
Inventors: 陈友三
Original assignee: Tianjin New Wei San Industrial Co ltd
Current assignee: Tianjin New Wei San Industrial Co ltd
Priority date: 2018-09-17
Filing date: 2018-09-17
Publication date: 2020-03-24

Abstract

The invention provides a negative pressure updraught casting device and a using method thereof, wherein a flat plate with a suction pipe is covered at the top end of a casting furnace, the bottom end of the suction pipe extends into molten steel in the casting furnace, a casting mold is placed on the flat plate, a flow path system of the casting mold is communicated with the suction pipe, and then a cover body is covered above the casting mold and the flat plate; air in the cover body is extracted to suck the molten steel in the casting furnace, and the molten steel flows into the mold cavity of the casting mold. After the molten steel is filled in the die cavity, a driving component drives a cutting part to ensure that the cutting part substantially cuts off the molten steel in the flow path system; and then the negative pressure state of the air in the cover body is released, so that the molten steel in the flow path system flows back to the pouring furnace, and after the cover body, the driving assembly, the casting mold and the cutting piece are removed, the other casting mold can be repeatedly used for forming at least one casting.

Description

Negative pressure up-suction casting device and using method thereof

Technical Field

The invention relates to a negative pressure upward suction casting device and a using method thereof, in particular to a device which sucks molten steel into a casting mold by utilizing negative pressure and then cuts the molten steel to quickly remove the casting mold.

Background

The gravity pouring method of the existing steel casting factory is mainly characterized in that a melting furnace is used for melting steel to 1450-1700 ℃, high-temperature molten steel is filled in an iron ladle, then the molten steel is poured into a prefabricated casting mold, the molten steel flows into a mold cavity from a soup inlet (gate) through a pouring basin, a vertical pouring gate and a flow passage of a flow passage system under the action of gravity, and the molten steel is taken out of the casting mold after being cooled and solidified, and then the required casting can be obtained after proper cleaning and processing.

The gravity casting method described above is mostly used for casting in a direction of downward flow of steel. However, it has the following disadvantages based on the consideration of casting cost and casting quality: 1. for a casting with a thickness of less than 3.5mm, when molten steel is poured into a sand mold under the action of gravity, the molten steel needs to pass through a flow path system. Because the air in the die cavity is blocked, the flow speed of the molten steel is not too high, the flow speed is slower as the thickness of the molten steel is thicker, and the longer the flow path is, the molten steel is cooled, so if the temperature of the molten steel is not high and the fluidity is insufficient, the thin-meat forming of the casting is difficult, and a good product is not easy to cast. 2. When the melting temperature is increased to 1700 ℃, even higher temperature, the fluidity of molten steel can be increased to form thin castings, but when the melting temperature is increased, the power consumption is increased, the service life of the refractory material of the melting furnace is greatly shortened, the replacement frequency of the refractory material is increased, and thus, the replacement cost of the refractory material is increased and the productivity is reduced due to the replacement shutdown. Furthermore, when the melting temperature of the molten steel exceeds 1700 ℃, the refractory materials in the melting furnace are melted into the molten steel, so that the oxide impurities in the molten steel are increased, and the purity and the mechanical properties of the steel casting are affected. 3. In the pouring process, the molten steel can flow into the die cavity only by filling a flow path system comprising a pouring basin, a vertical pouring gate, a flow channel and the like, and the molten steel in the flow path system and the molten steel in the die cavity are cooled and solidified simultaneously. The molten steel is reserved in the flow path system and consumes more molten steel, so that the proportion of the casting to the total pouring molten steel (namely the step retention rate) cannot be effectively improved, the step retention rate cannot be effectively improved, the molten steel cannot be saved, the energy cannot be effectively saved, and the production cost is reduced.

In order to solve the above-mentioned drawbacks, the present inventors propose a negative pressure up-draft casting method, comprising the following steps: a. covering a flat plate with a suction pipe on the top end of a melting furnace, wherein molten steel is contained in the melting furnace, and the bottom end of the suction pipe extends into the molten steel; b. forming an air channel communicated with the mold cavity on the mold, and placing the mold on a flat plate to enable a flow path system of the mold to be communicated with the top end of the suction pipe; c. covering a cover body above the casting mould and the flat plate, extracting air in the cover body to reduce the air pressure in the cover body and the mould cavity, and upwards extracting molten steel in the melting furnace through a suction pipe to enable the molten steel to flow into the mould cavity; and d, standing for a period of time to solidify the soup inlet between the flow path system and the mold cavity, and then releasing the negative pressure state of the air in the cover body to enable the molten steel in the flow path system to reversely flow back into the melting furnace.

Disclosure of Invention

By means of the negative pressure suction pouring method, various problems that thin castings are difficult to form when the temperature of molten steel is not high, and the step retention rate cannot be improved due to the fact that excessive molten steel stays in a flow path system can be solved. However, in actual use, in order to quickly solidify the molten steel in the inlet, the molten steel in the channel system is returned back into the melting furnace in a reverse flow manner, the mold is separated from the flat plate, the molten steel in the mold is cooled continuously, and a new mold is placed on the flat plate again to perform the pouring operation again. Therefore, although the reduction of the aperture of the soup inlet can lead the molten steel in the aperture to be rapidly solidified, the molten steel sucked up by the suction pipe can not flow into the die cavity through the soup inlet in a large amount and rapidly, and the molten steel can not flow into the die cavity in a large amount and rapidly, for the casting with complex structure and thin meat of the turbocharger, the high-temperature molten steel which is just started can rapidly enter the die cavity, but the narrow soup inlet can limit the flow rate of the molten steel, so that the molten steel with good fluidity can not be cooled gradually and can not be completely filled into the die cavity after entering the die cavity due to the insufficient flow rate, and further the problems that the casting can not be molded smoothly and the qualification rate can not be effectively improved are caused. Accordingly, the present invention has been made in an effort to provide a structure and a method that are different from the prior art and improve the above-mentioned shortcomings.

An object of the present invention is to provide a negative pressure suction casting apparatus and a method for using the same, which can allow a large amount of high temperature molten steel to enter a mold cavity quickly, and can cut off the molten steel in a flow path system substantially by a cutting member after the mold cavity is filled with the molten steel, so as to meet the use requirement of a product with thin and fleshy castings, and achieve the effect of quick, repeated and multi-batch production.

In order to achieve the above object, the present invention provides a negative pressure updraught casting device for at least one casting mold to form at least one casting, wherein the casting mold is provided with at least one mold cavity and a flow path system which are communicated; a flat plate with a suction pipe is covered at the top end of a casting furnace; the casting mould is placed on the flat plate, an air channel communicated with the mould cavity is formed in the casting mould, and a flow path system of the casting mould is communicated with the top end of the suction pipe; a cover body covers the upper parts of the casting mould and the flat plate, and the cover body is connected with an air extractor for extracting air in the cover body; the main technical characteristics are as follows: a cutting member is disposed in the mold, and a driving assembly is disposed at one end of the cutting member for driving the cutting member so that the other end of the cutting member moves to substantially cut off the flow path system in the mold.

In practice, the mold is a sand mold, and the air passages in the mold are the spaces between the sand grains of the sand mold.

When the flow path system is implemented, the flow path system comprises a main flow path and at least one soup inlet flow path, the main flow path is communicated with the top end of the suction pipe, the soup inlet flow path is positioned between the main flow path and the mold cavity, and the other end of the cut-off piece is adjacent to the inside of the soup inlet flow path.

When the casting mold is implemented, a connecting pipe is arranged in the casting mold, the connecting pipe is connected in the main flow path in a shaft mode, the top end of the connecting pipe is communicated with the soup inlet flow path, and the bottom end of the connecting pipe is in butt joint communication with the top end of the suction pipe.

When the casting mold is implemented, the casting mold comprises an upper mold and a lower mold, wherein the bottom surface of the upper mold is provided with a bowl-shaped groove, the top end of the bowl-shaped groove extends upwards to form a vertical hole, and the vertical hole is upwards communicated with the external space of the upper mold; the other end of the cutting part is provided with a bowl-shaped part with a downward opening for being positioned in the bowl-shaped groove, and one end of the cutting part is provided with an upright post for being positioned in the upright hole; the driving component comprises a push rod and a driving piece which are mutually linked, and one end of the push rod is positioned in the vertical hole and used for pushing the cutting piece to move downwards.

When in use, one end of the push rod is separated from the cutting part and is not connected with the cutting part.

In practice, the negative-pressure updraught casting device further comprises at least two pressure plate assemblies, each pressure plate assembly comprises a pressure plate and a pushing piece, the pressure plates are positioned in the cover body, and one end of each pushing piece is connected with the pressure plate and used for pushing and pressing so as to enable the pressure plates to move downwards and be positioned.

The use method of the negative pressure updraught casting device comprises the following steps: a. covering a flat plate with a suction pipe on the top end of the casting furnace, and enabling the bottom end of the suction pipe to extend into molten steel in the casting furnace; b. placing the casting mould on the flat plate, and enabling a flow path system of the casting mould to be communicated with the top end of the suction pipe; covering the cover body above the casting mold and the flat plate; extracting air in the cover body to reduce the air pressure in the cover body and the die cavity so as to suck up the molten steel in the casting furnace through the suction pipe and make the molten steel flow into the die cavity; c. after the molten steel is filled in the die cavity, driving one end of the cutting piece by using the driving component, and enabling the other end of the cutting piece to move so as to substantially cut off the molten steel in the flow path system; then the negative pressure state of the air in the cover body is released, so that the molten steel in the flow path system reversely flows back into the casting furnace; d. removing the cover body and the driving assembly, and then moving the casting mold and the cut-off piece to enable the flat plate with the suction pipe to continuously cover the top end of the pouring furnace; repeating steps b to d to form at least one casting by using another mold.

When the cover body in the step b is covered above the casting mold and the flat plate, the at least one pushing piece pushes the at least one pressing plate, so that the at least one pressing plate simultaneously moves downwards and is pressed against the top surface of the casting mold to position the casting mold.

Therefore, the invention has the following advantages:

1. the molten steel is sucked into the die cavity in a negative pressure sucking-up mode, and the soup inlet flow path of the flow path system can be enlarged, so that the high-temperature molten steel can flow into each vacant position of the die cavity sufficiently and quickly to fill the die cavity, the thickness of the formed casting can be reduced to be less than 2.5mm, and for the casting with a complicated structure and thin thickness of a turbocharger, the use requirement can be met due to the thin thickness of the casting, and the qualification rate can be greatly improved.

2. The invention can release the negative pressure to lead the molten steel to flow back when the molten steel in the die cavity of the casting die is still in a molten state or in a small quantity of solidification state by using a cutting piece to substantially cut off the molten steel in the flow path system after the molten steel rapidly enters the die cavity and is filled in the die cavity, and the molten steel is continuously cooled after the casting die is removed, and then another casting die is placed on a flat plate to carry out casting operation again, therefore, the time for placing the same casting die on the flat plate can be greatly shortened, and the rapid, repeated and multi-batch production effect can be achieved.

3. The push rod of the driving assembly is separated from the cutting part and is not connected with the cutting part, and the bowl-shaped part at the bottom end of the cutting part is positioned in the bowl-shaped groove of the upper die, so that the cover body and the push rod can be removed simultaneously after a casting mold is cast, and the casting mold and the cutting part are moved simultaneously, so that repeated and multi-batch production operation is realized.

4. When the cover body covers the casting mould and the flat plate, the at least one pushing piece pushes the at least one pressing plate to enable the at least one pressing plate to move downwards and to be pressed against the top surface of the casting mould, so that the casting mould can be effectively positioned in the casting process to prevent high-temperature molten steel flowing upwards from leaking outwards to influence the product quality and even cause danger. Based on the structure of the pressing plate assembly, the upper die and the lower die of the casting die can be tightly attached to the flat plate, and the tight attachment and separation of the casting die and the flat plate can be quicker, more effective and simpler, so that the cost of manual operation is reduced.

For further understanding of the present invention, the following detailed description of the preferred embodiments will be provided in conjunction with the drawings and figures to illustrate the specific components of the present invention and the functions performed thereby.

Drawings

FIG. 1 is a schematic sectional view of the vacuum updraft casting apparatus according to the preferred embodiment of the present invention.

FIG. 2 is a schematic view of the present invention in a state of use when negative pressure is generated.

FIG. 3 is a schematic view showing a state in which the cutting member cuts off molten steel and the molten steel is returned to the casting furnace in a reverse flow manner according to the preferred embodiment of the present invention.

FIG. 4 is a schematic view of the preferred embodiment of the present invention in use after a casting operation has been completed and with the housing, drive assembly, mold and cut-off separated from the plate.

Description of reference numerals: a negative pressure updraught casting device 1; a casting mold 2; an air passage 21; an upper die 22; a bowl-shaped groove 221; the upright holes 222; a lower die 23; a washer 231; a mold cavity 24; a flow path system 25; a main flow path 251; a soup inlet flow path 252; a connecting pipe 26; a pouring furnace 3; a plate 4; a suction pipe 41; a cover body 5; an exhaust tube 51; an air extraction device 6; a platen assembly 7; a pressing plate 71; a pusher member 72; a cut-off member 8; a column 81; a bowl-shaped portion 82; a drive assembly 9; a push rod 91; a drive member 92.

Detailed Description

Referring to fig. 1, a vacuum updraught casting apparatus 1 according to a preferred embodiment of the present invention is provided for forming at least one casting by at least one casting mold 2, wherein the vacuum updraught casting apparatus 1 includes a pouring furnace 3, a plate 4, a casting mold 2, a cover 5, an air extractor 6, at least two platen assemblies 7, a cutting member 8 and a driving assembly 9.

An opening is formed at the top end of the pouring furnace 3, and a coil is wound on the outer periphery of the pouring furnace 3, so that the temperature of molten steel molten in the pouring furnace 3 is controlled after the coil is heated, and the melting temperature of the molten steel is controlled to be between 1500 and 1600 ℃. In practice, the casting furnace 3 may also heat the molten steel by other indirect or direct heating methods. The plate 4 is covered on the top opening of the casting furnace 3, the plate 4 has a hollow ceramic suction pipe 41 which penetrates up and down, the suction pipe 41 vertically penetrates the plate surface of the plate 4, and the top opening of the suction pipe 41 is approximately on the same horizontal plane with the top surface of the plate 3.

The casting mould 2 is a sand mould, and the gaps between the sand grains of the sand mould are used as air passages 21 of the casting mould 2 for generating air permeability. The casting mold 2 comprises an upper mold 22 and a lower mold 23, wherein the bottom surface of the upper mold 22 is provided with a bowl-shaped groove 221 which is concave upwards, the top end of the bowl-shaped groove 221 extends upwards to form a vertical hole 222, and the vertical hole 222 is communicated with the external space of the upper mold 22 upwards. In this embodiment, four mold cavities 24 and a flow path system 25 are disposed in the mold 2, and the four mold cavities 24 are connected to the outside of the mold 2 through the air passages 21 on the mold 2; the flow path system 25 comprises a main flow path 251 and four soup inlet flow paths 252, the main flow path 251 is a circular tube-shaped vertical hole in the lower die 23, the main flow path 251 is axially connected with a connecting pipe 26, the top end of the connecting pipe 26 is communicated with the four soup inlet flow paths 252, the four soup inlet flow paths 252 are respectively positioned between the top ends of the connecting pipes 26 and the four die cavities 24, and when the casting die 2 is placed on the top surface of the flat plate 4, the bottom ends of the connecting pipes 26 are in butt joint communication with the top ends of the suction pipes 41. In practice, the mold cavities 24 and the liquid inlet passages 252 may be present in one or more sets to form one or more castings at the same time. The lower mold 23 has an annular leakage-proof ceramic wool gasket 231 on the bottom surface thereof.

The cover 5 is a hollow container having an opening formed in the bottom surface thereof, and the cover 5 is fitted over the mold 2 and the plate 4 so that the mold 2 is accommodated between the top surface of the plate 4 and the inner wall of the cover 5. The enclosure 5 is connected to one end of an exhaust tube 51, and the other end of the exhaust tube 51 is connected to a vacuum pump as an exhaust device 6 for exhausting air from the enclosure 5.

In this embodiment, two of the pressing plate assemblies 7 are provided, the two pressing plate assemblies 7 are arranged in parallel, and any one of the pressing plate assemblies 7 includes a planar pressing plate 71 and a pushing member 72, the pressing plate 71 is positioned in the housing 5 in a manner of moving up and down, the top surface of the pressing plate 71 is connected to the bottom end of the pushing member 72, and the pushing member 72 is an air cylinder for pushing and pressing to move and position the pressing plate 71 downward. In practice, the pushing member 72 may be a hydraulic cylinder or a mechanical structure combining a stepping motor and a rack, and the pressing plate 71 may be moved up and down.

The top end of the cut-off part 8 is provided with a column 81, and the column 81 is inserted into the upright hole 222 of the upper die 22 and positioned in the upright hole 222; the bottom end of the cutting part 8 is provided with a bowl-shaped part 82 with a downward opening and a closed periphery, and the outer arc periphery of the bowl-shaped part 82 is tightly attached to the outer arc periphery of the bowl-shaped groove 221 of the upper die 22 so as to position the bowl-shaped part 82; when the shut-off member 8 is positioned inside the upper die 22, the bottom surface of the bowl-shaped portion 82 abuts the soup flow path 252.

The driving assembly 9 comprises a push rod 91 and a driving member 92 which are interlocked with each other, the upper half part of the push rod 91 is provided with a rack, the bottom end of the push rod 91 passes through the upright hole 222 of the upper die 22 and is positioned in the upright hole 222, and the bottom end of the push rod 91 is separated from and unconnected with the top end of the cutting member 8; the driving member 92 is a stepping motor with a gear, so that when the stepping motor rotates, the gear drives the push rod 91 to move downward, and then the bottom end of the push rod 91 pushes the upright 81 at the upper end of the cutting member 8, so that the cutting member 8 moves downward. In practice, the driving member 92 may be an oil cylinder or a pneumatic cylinder, and the push rod 91 may be moved downward.

Thus, the preferred embodiment of the method for using the negative pressure updraught casting device of the present invention comprises the following steps:

the flat plate 4 having the suction pipe 41 is fitted over the top end of the casting furnace 3, and the bottom end of the suction pipe 41 is inserted into the molten steel in the casting furnace 3.

As shown in fig. 2, the casting mold 2 is placed on the flat plate 4 such that the flow path system 25 of the casting mold 2 communicates with the tip end of the suction pipe 41; then the cover body 5 is covered above the casting mould 2 and the flat plate 4; air in the cover body 5 is extracted to reduce the air pressure in the cover body 5 and the die cavity 24, so that the molten steel in the casting furnace 3 is upwards sucked through the suction pipe 41, and the molten steel flows into the die cavity 24.

As shown in fig. 3, after the molten steel fills the cavity 24, the driving unit 9 drives the block 8 to move the other end of the block 8 to substantially cut off the molten steel in the flow path system 25; then, the negative pressure state of the air in the cover body 5 is released, and the molten steel in the flow path system 25 is made to flow back into the casting furnace 3.

As shown in fig. 4, the cover 5 and the driving assembly 9 are removed, and the casting mold 2 and the cutting member 8 are moved to allow the plate 4 with the suction pipe 41 to continuously cover the top end of the pouring furnace 3; and

repeating steps b to d to form at least one casting using another mold 2.

When the air in the cover body 5 is extracted by the air extractor 6, the air pressure in the cover body 5 and the die cavity 24 can be reduced due to the air permeability of the casting mold 2, the air pressure in the cover body 5 is the same as the air pressure in the die cavity 24, the flow path system 25, the connecting pipe 26 and the suction pipe 41, the high-temperature molten steel in the pouring furnace 3 is extracted by negative pressure, and the molten steel flows upwards through the suction pipe 41 and then flows into the die cavity 24 through the flow path system 25.

Referring to fig. 2, when the cover 5 in step b covers the mold 2 and the flat plate 4, two pushing members 72 are used to push the two pressing plates 71 respectively, so that the two pressing plates 71 move downward and press against the top surface of the mold 2 to position the mold 2, thereby preventing the high-temperature molten steel flowing upward from leaking outward. Since the gasket 231 is sandwiched between the bottom surface of the lower mold 23 and the top surface of the flat plate 4, the leakage of the high temperature molten steel from the gap between the bottom surface of the lower mold 23 and the top surface of the flat plate 4 can be prevented.

After the molten steel flows into the mold cavity 24 and fills the mold cavity 24, the driving unit 9 drives the block 8, so that the block 8 moves and the bowl-shaped portion 82 at the bottom end of the block 8 covers the top end of the connecting pipe 26, thereby substantially cutting off the molten steel communication between the main flow path 251 and the four liquid inlet flow paths 252, or directly covers the four liquid inlet flow paths 252, and similarly cutting off the molten steel in the flow path system 25. The above-mentioned substantial cutting off of the molten steel communication in the flow path system 25 means that the bottom end of the bowl-shaped portion 82 is completely sealed with the top end of the connection pipe 26, and may include a slight gap between the bottom end of the bowl-shaped portion 82 and the top end of the connection pipe 26, but most of the molten steel in the flow path system 25 may be cut off and only a slight amount of molten steel may leak out to be rapidly solidified.

After the molten steel in the flow path system 25 is cut off, the molten steel in the die cavity 24 can be still in a molten state or in a small amount of solidified state, at this time, the negative pressure state of the air in the cover body 5 can be released, and the molten steel in the flow path system 25 can flow back to the pouring furnace 3. And when the molten steel completely flows back into the pouring furnace 3, the cover body 5, the pressure plate assembly 7 and the driving assembly 9 are removed, the casting mold 2 and the cut-off piece 8 are separated from the flat plate 4, and a new casting mold 2 can be placed on the flat plate 4 again, and then the casting operation is carried out again to form at least one casting by using another casting mold 2.

Therefore, the invention has the following advantages:

In summary, the present invention can achieve the desired objective, and provides a negative pressure suction casting apparatus and a method of using the same, which not only can reduce the thickness of the castings, achieve rapid production, reduce the production cost, increase the production yield, and ensure the quality of the castings, but also have industrial application value.

Claims

1. A negative pressure updraught casting device is used for at least one casting mould to form at least one casting, and at least one mould cavity and a flow path system which are communicated are arranged in the casting mould; a flat plate system with a suction pipe covers the top end of a casting furnace; the casting mould is placed on the flat plate, an air channel communicated with the mould cavity is arranged on the casting mould, and a flow path system of the casting mould is communicated with the top end of the suction pipe; a cover body is covered above the casting mould and the flat plate, and the cover body is connected with an air extractor for extracting air in the cover body; the method is characterized in that:

a cutting part is arranged in the casting mould, and one end of the cutting part is provided with a driving component for driving the cutting part so that the other end of the cutting part moves to substantially cut off the flow path system in the casting mould.

2. The negative suction casting apparatus as claimed in claim 1, wherein the mold is a sand mold, and the air passages in the mold are gaps between sand grains of the sand mold.

3. The negative pressure updraught casting apparatus of claim 1 or 2, wherein the flow path system comprises a main flow path and at least one soup inlet flow path, the main flow path is in communication with the top end of the straw, the soup inlet flow path is located between the main flow path and the mold cavity, and the other end of the shut-off member is adjacent to the inside of the soup inlet flow path.

4. The negative pressure updraught casting apparatus as recited in claim 3, wherein the casting mold has a connection pipe formed therein, the connection pipe is connected to the main flow path, a top end of the connection pipe is connected to the hot water inlet flow path, and a bottom end of the connection pipe is connected to a top end of the suction pipe.

5. The negative pressure updraught casting apparatus as claimed in claim 1, wherein the mold comprises an upper mold and a lower mold, the upper mold having a bowl-shaped groove on a bottom surface thereof, a vertical hole extending upward from a top end of the bowl-shaped groove, the vertical hole communicating upward with an outer space of the upper mold; the other end of the cut-off piece is provided with a bowl-shaped part with a downward opening for being positioned in the bowl-shaped groove; the driving assembly comprises a push rod and a driving piece which are mutually linked, and one end of the push rod is positioned in the vertical hole and used for pushing the cutting piece to move downwards.

6. The negative pressure updraught casting apparatus of claim 5, wherein the one end of the push rod is separated from and unattached to the cutoff member.

7. The negative pressure updraught casting apparatus of claim 5 or 6 wherein the one end of the section is a post for location within the upstanding bore.

8. The negative-pressure updraught casting apparatus of claim 1, further comprising at least two platen assemblies, wherein the platen assemblies comprise a platen and a pushing member, the platen is located in the housing, and one end of the pushing member is connected to the platen for pushing and pressing to move the platen downward.

9. A method of using the negative pressure updraught casting apparatus of claim 1, comprising the steps of:

a. covering the flat plate with the suction pipe on the top end of the casting furnace, and enabling the bottom end of the suction pipe to extend into molten steel in the casting furnace;

b. placing the casting mold on the flat plate, so that the flow path system of the casting mold is communicated with the top end of the suction pipe; covering the cover body above the casting mold and the flat plate; extracting air in the cover body to reduce the air pressure in the cover body and the die cavity so as to suck up the molten steel in the pouring furnace through the suction pipe and make the molten steel flow into the die cavity;

c. after the molten steel is filled in the die cavity, driving one end of the cut-off piece by the driving component, and enabling the other end of the cut-off piece to move so as to cut off the molten steel in the flow path system substantially; then the negative pressure state of the air in the cover body is released, so that the molten steel in the flow path system reversely flows back into the pouring furnace;

d. removing the cover body and the driving assembly, and then moving the casting mold and the cut-off piece to enable the flat plate with the suction pipe to continuously cover the top end of the pouring furnace; and

e. repeating steps b-d to form at least one casting using another mold.

10. The negative pressure up-draft casting method according to claim 9, wherein when the cover body of step b is covered over the mold and the platen, at least one pushing member pushes at least one pressing plate to move the at least one pressing plate downward and press against the top surface of the mold to position the mold.