A method and device for negative pressure die casting of heat-resistant steel exhaust manifold

Abstract

The present invention discloses a heat-resistant steel exhaust manifold negative pressure die-casting method, which solves the problems of low casting yield and process yield of the existing gravity casting process. The method is to place a sand mold into a casting box, then evacuate the casting box to form a negative pressure environment, and finally pressurize molten steel into the casting mold to obtain a heat-resistant steel exhaust manifold casting. The heat-resistant steel exhaust manifold negative pressure die-casting method of the present invention effectively improves the casting yield and process yield. The present invention also discloses a heat-resistant steel exhaust manifold negative pressure die-casting device. The heat-resistant steel exhaust manifold negative pressure die-casting device of the present invention effectively reduces production costs while improving the casting yield and process yield, and is easy to centrally treat exhaust gas, thereby achieving the purpose of environmentally friendly production.

Description

Technical Field

[0001] The invention relates to a heat-resistant steel exhaust manifold die-casting process, and more particularly to a heat-resistant steel exhaust manifold negative pressure die-casting method and device. Background Art

[0002] In recent years, the automotive industry has experienced rapid growth, and energy and environmental issues have become increasingly prominent. Automotive engines face greater challenges in energy conservation and environmental protection. As a key component in automotive engines, the quality of the exhaust manifold directly impacts the engine's service life and emissions performance. Currently, exhaust manifold castings are primarily made of silicon-molybdenum ductile iron (SMI) and high-nickel cast iron (NiFe). As engine performance improves, exhaust temperatures have reached over 900°C. These SMI and NiFe no longer meet the emission performance requirements. Austenitic heat-resistant cast steel, however, offers excellent heat resistance (up to 1050°C), fatigue resistance, and corrosion resistance, fully adapting to engine combustion efficiency and reducing harmful gas emissions. Therefore, austenitic heat-resistant cast steel has become the material of choice for high-performance exhaust manifolds.

[0003] The engine exhaust manifold, an important automotive component, is a typical thin-walled complex casting. Due to factors such as the poor fluidity of austenitic heat-resistant cast steel and the special structure of the exhaust manifold, the application of austenitic heat-resistant cast steel in exhaust manifolds presents enormous process difficulties. Heat-resistant steel has large solidification shrinkage, poor fluidity of molten steel, and poor casting process performance. Castings are prone to casting defects such as pores, slag inclusions, shrinkage cavities, and shrinkage. At present, most austenitic heat-resistant cast steel exhaust manifolds use traditional gravity casting methods, with pouring temperatures above 1600°C. The risers that require shrinkage compensation are numerous and large, the casting yield is as low as below 70-80%, the process yield is as low as 20-30%, the production cost is high, and even when the pouring temperature reaches 1700°C, it is difficult to form the exhaust manifold with a thin wall of 3-4mm. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art, and one of its purposes is to provide a negative pressure die casting method for a heat-resistant steel exhaust manifold, which effectively improves the casting yield and process output rate.

[0005] The second purpose is to provide a heat-resistant steel exhaust manifold negative pressure die-casting device, which can effectively reduce production costs while improving the casting yield and process yield, and facilitate centralized treatment of exhaust gas to achieve the goal of environmentally friendly production.

[0006] The first technical solution of the present invention is as follows: a heat-resistant steel exhaust manifold negative pressure die casting method, the method is to place a sand mold in a casting box, then evacuate the casting box to form a negative pressure environment, and finally pressurize molten steel into the casting mold to obtain a heat-resistant steel exhaust manifold casting.

[0007] As a further improvement, the method comprises the following steps:

[0008] S1 Shell and core making: Use shell mold to make sand mold on hot core box machine and assemble it to get casting mold;

[0009] S2: Place the sand mold into the casting box, then fill the casting box on the back of the mold with steel shots and vibrate them, then install the pouring cup at the bottom of the casting box to connect the pouring cup with the mold in the sand mold;

[0010] S3 Casting box transfer: Move the casting box to the top of the furnace body so that the pouring cup is aligned with the casting mouth of the furnace body;

[0011] S4 Negative pressure exhaust: Use the exhaust device to exhaust the casting box to form a negative pressure environment inside the casting box;

[0012] S5 pressure filling: The molten steel in the furnace is pressed into the mold through the casting mouth and pouring cup by the inflation device to complete the filling;

[0013] S6 solidification pressure relief: maintain pressure on the mold for a period of time during solidification, and then release the pressure on the molten steel;

[0014] S7 box transfer cooling: move the casting box to the cooling station for cooling;

[0015] S8 Sand cleaning: Clean the sand and cut the steel shots to obtain heat-resistant steel exhaust manifold castings.

[0016] Furthermore, in the S4, the negative pressure value in the casting box is 0.02MPa~0.04MPa; in the S6, the solidification holding time of the casting mold is 1min~2min, and the solidification holding pressure is 0.1MPa~0.4MPa; in the S7, the cooling time of the casting box is 35min~45min.

[0017] Furthermore, in the above-mentioned S5, the speed at which the steel is hydraulically poured into the mold is set according to the pouring time and pouring weight, and the formula is as follows:

[0018] v=m / t

[0019] Among them, v is the steel pressure injection speed, m is the casting weight, and t is the pouring time.

[0020] The second technical solution of the present invention is as follows: a heat-resistant steel exhaust manifold negative pressure die-casting device, including a sand mold, in which a casting mold of an exhaust manifold casting is formed, and also including a furnace body and a casting box, the sand mold is installed in the casting box, the casting box is connected to a vacuum device, a pouring cup connected to the casting mold is provided on the periphery of the casting box, one end of the furnace body is provided with a casting mouth connected to the molten steel in the furnace body, the pouring cup is clamped on the casting mouth, and the other end of the furnace body is connected to the inflation device.

[0021] As a further improvement, steel shots are filled between the sand mold and the casting box.

[0022] Furthermore, the exhaust device includes a pressure cover and an exhaust pipe, the pressure cover is pressed on the top of the casting box, one end of the exhaust pipe is connected to the casting box, and the other end is connected to the exhaust pump, and the exhaust pipe is provided with an exhaust valve.

[0023] Furthermore, a liquid outlet communicating with the casting mouth is provided at one end of the furnace body, a liquid inlet is provided at the other end, and a heating coil is provided around the periphery of the furnace body.

[0024] Furthermore, a furnace seat is provided on the periphery of the liquid inlet, a detachable furnace cover is provided on the top of the furnace seat, and a sealing ring is provided between the furnace seat and the furnace cover.

[0025] Furthermore, the inflation device includes an air intake pipe and an exhaust pipe, the two ends of the air intake pipe are respectively connected to the liquid inlet and the inflation pump, the air intake pipe is provided with an air intake valve, one end of the exhaust pipe is connected to the liquid inlet, and the exhaust pipe is provided with an exhaust valve.

[0026] Beneficial effects

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. The negative pressure die casting method for the heat-resistant steel exhaust manifold of the present invention combines the characteristics of low-pressure casting and vacuum suction casting, realizes negative pressure casting in the mold casting box, reduces the resistance to filling and the formation of surface gas, solidifies the metal under pressure, has better tissue density, accelerates the surface solidification time, reduces the temperature gradient between the metal liquids, realizes simultaneous solidification or sequential solidification, improves shrinkage feeding efficiency, effectively solves the shrinkage defects inside the casting, prevents internal leakage of the casting, ensures the quality of the casting, can cast thin-walled 3mm-4mm castings, the casting yield can reach more than 90%, and the process yield can reach more than 50%, greatly reducing production costs and effectively improving the casting yield and process yield.

[0029] 2. The heat-resistant steel exhaust manifold negative pressure die-casting device of the present invention adopts a modular design, and its furnace body can match horizontal and vertical casting according to product and process requirements. After the solidification and shrinkage compensation of the casting is completed, the pressure is released, and the molten steel in the sprue flows back, leaving only a very small ingredient neck for shrinkage compensation, thereby achieving the purpose of greatly improving the process output rate and reducing the scrap rate, and ensuring the rise and fall of the molten steel, so that the molten steel can rise smoothly in the filling stage, strengthen the shrinkage compensation of the molten steel in the solidification and pressure holding stage, and quickly fall back in the sprue during the pressure release stage. At the same time, there is less waste gas and it is easy to combine with the dust removal system, so it is easy to centrally treat the waste gas, thereby achieving the purpose of environmentally friendly production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1It is a structural schematic diagram of the present invention;

[0031] Figure 2 This is an enlarged schematic diagram of the structure of the pouring cup in the present invention;

[0032] Figure 3 It is an enlarged schematic diagram of the structure of the casting nozzle in the present invention.

[0033] Among them: 1-sand mold, 2-casting mold, 3-furnace body, 4-casting box, 5-pouring cup, 6-casting mouth, 7-steel shot, 8-pressing cover, 9-exhaust pipe, 10-exhaust valve, 11-liquid outlet, 12-liquid inlet, 13-heating coil, 14-furnace base, 15-furnace cover, 16-inlet pipe, 17-exhaust pipe, 18-inlet valve, 19-exhaust valve, 20-sprue, 21-metal liquid channel, 22-hydraulic cylinder, 23-conical hole, 24-conical body. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the specific embodiments in the accompanying drawings.

[0035] See Figure 1-3 The present invention provides a negative pressure die casting method for a heat-resistant steel exhaust manifold. The method comprises placing a sand mold into a casting box, evacuating the casting box to create a negative pressure environment, and finally pressurizing molten steel into the mold to obtain a heat-resistant steel exhaust manifold casting. The method comprises the following steps:

[0036] S1 Shell and Core Making: Using shell molds, sand molds are made on a hot core box machine and assembled to form a casting mold. Specifically, the air sand mold consists of an outer shell and an inner runner core. There are two outer shells. After being made, they are painted and dried according to process requirements. The inner runner core is then installed into the outer shell. Casting adhesive is applied around the outer shell and assembled to form a casting mold.

[0037] S2: Place the sand mold into the casting box, then fill the casting box on the back of the mold with steel shots and vibrate them, then install the pouring cup at the bottom of the casting box to connect the pouring cup with the mold in the sand mold;

[0038] S3 casting box transfer: Move the casting box to the top of the furnace body so that the pouring cup is aligned with the casting mouth of the furnace body. The casting box is moved to the furnace body through an assembly line and snapped onto the casting mouth of the furnace body. The assembly line can be a crane, which makes operation more convenient and keeps workers away from the furnace body, ensuring work safety.

[0039] S4 Negative pressure exhaust: Use the exhaust device to exhaust the casting box to form a negative pressure environment inside the casting box;

[0040] S5 pressure filling: The molten steel in the furnace is pressed into the mold through the casting mouth and pouring cup by the inflation device to complete the filling. The temperature of the molten steel is 1520-1540 degrees Celsius.

[0041] S6 solidification pressure relief: The mold is solidified and pressure is maintained for a period of time, and then the pressure on the molten steel is released, and the molten steel can fall back into the furnace body to prepare for the next die casting;

[0042] S7 box transfer cooling: the casting box is moved to the cooling station for cooling. The casting box is also moved through the assembly line.

[0043] S8 Sand cleaning: Clean the sand and cut the steel shots to obtain heat-resistant steel exhaust manifold castings.

[0044] The negative pressure die casting method for a heat-resistant steel exhaust manifold of the present invention combines the characteristics of low-pressure casting and vacuum suction casting, realizes negative pressure casting in a mold casting box, reduces the resistance to filling and the formation of surface gas, solidifies the metal under pressure, has better tissue density, accelerates the surface solidification time, reduces the temperature gradient between the molten metals, realizes simultaneous solidification or sequential solidification, improves shrinkage feeding efficiency, effectively solves shrinkage defects inside the casting, prevents internal leakage of the casting, ensures the quality of the casting, can cast thin-walled 3mm-4mm castings, the casting yield can reach more than 90%, and the process yield can reach more than 50%. The molten metal solidifies under system pressure, and the product yield is more than 10% higher than that of the traditional process, greatly reducing production costs and effectively improving the casting yield and process yield.

[0045] Preferably, in S4, the negative pressure value in the casting box is 0.02MPa~0.04MPa. During the liquid metal filling process, the resin sand will generate a large amount of gas, which needs to be discharged outward. If it is not discharged in time, there will be air suffocation, and defects such as cold shut and insufficient pouring of the casting will occur; at the same time, during the solidification process, the resin sand will also generate a large amount of gas. If it is not discharged in time, subcutaneous pores and other defects will easily form on the surface of the casting. The die-casting method of this embodiment forms a negative pressure environment in the casting box, thereby facilitating the formation of negative pressure on the casting, so that the gas generated during the die-casting filling process is discharged in time, preventing the problems of air suffocation, cold shut and insufficient pouring in the casting, effectively improving the casting yield and ensuring the quality of the casting; in S6, the solidification holding time of the casting is 1min~2min, and the solidification holding pressure is 0.1MPa~0.4MPa, so that the casting can be solidified and formed; in S7, the cooling time of the casting box is 35min~45min, so that the casting can be further cooled, which is convenient for subsequent workers to unpack and demold.

[0046] Preferably, in S5, the speed at which the steel is hydraulically injected into the mold is set based on the pouring time and the pouring weight, using the following formula: v = m / t, where v is the speed at which the steel is hydraulically injected, m is the weight of the casting, and t is the pouring time. By adjusting the appropriate casting temperature, pressure parameters, and pouring speed, the ability of the molten metal to fill the mold and feed shrinkage is improved, effectively solving common problems such as cold shuts, under-pouring, and air holes in the casting of heat-resistant steels and stainless steels.

[0047] A heat-resistant steel exhaust manifold negative pressure die-casting device includes a sand mold 1, a casting mold 2 for an exhaust manifold casting is formed in the sand mold 1, and the die-casting device also includes a furnace body 3 and a casting box 4, wherein the casting box 4 is a box with an open top, the sand mold 1 is installed in the casting box 4, the casting box 4 is connected to a vacuum device, a pouring cup 5 connected to the casting mold 2 is provided on the periphery of the casting box 4, a casting nozzle 6 connected to the molten steel in the furnace body 3 is provided at one end of the furnace body 3, the casting nozzle 6 is sleeved on the liquid outlet 11, and the two are fixedly connected, the pouring cup 5 is clamped on the casting nozzle 6, and the other end of the furnace body 3 is connected to the inflation device.

[0048] Preferably, steel shots 7 are filled between the sand mold 1 and the casting box 4 to support the sand mold 1. At the same time, the gaps between the steel shots 7 are large, which facilitates the subsequent gas circulation for exhaust and provides a space for exhaust gas during the die-casting process.

[0049] The die-casting device of the present invention supports the sand mold 1 by filling steel shots 7 between the casting box 4 and the sand mold 1, and provides an exhaust device on the top of the casting box 4. Before die-casting, the exhaust device can be used to exhaust air in the casting box 4 to form a negative pressure environment in the casting box 4, thereby facilitating the formation of negative pressure on the casting mold 2, so that the gas generated during the die-casting filling process is discharged in time, preventing problems such as air holding, cold shut of the casting, and insufficient pouring in the casting mold 2, effectively improving the casting yield rate, and ensuring the quality of the casting.

[0050] Preferably, the exhaust device includes a pressure cover 8 and an exhaust pipe 9, wherein the pressure cover 8 is pressed on the top of the casting box 4. Specifically, the pressure cover 8 can be driven up and down by a hydraulic cylinder and pressed on the top of the casting box 4, which is more convenient to operate. One end of the exhaust pipe 9 is connected to the casting box 4, and the other end is connected to the exhaust pump. Specifically, a plurality of air holes are opened on the pressure cover 8 directly above the sand mold 1, and a manifold is installed on the pressure cover 8 above the air holes. The exhaust pipe 9 is connected to the manifold. When exhausting, exhaust can be achieved at different positions of the casting box 4. While quickly completing the exhaust, the air flow pressure outside the sand mold 1 is relatively uniform and balanced. An exhaust valve 10 is provided on the exhaust pipe 9 to facilitate the control of exhaust.

[0051] Preferably, a runner 20 is provided at one end of the sand mold 1 near the pouring cup 5, connecting the pouring cup 5 with the casting mold 2, so as to facilitate the hydraulic pressure of the steel into the casting mold 2. The runner 20 is a cavity with narrow ends at the upper and lower ends and a wide middle, which can keep more heat in the molten steel at this position and prevent it from solidifying. Then, the die-casting pressure at the bottom of the pouring cup 5 is used to supplement the solidification and shrinkage of the casting, thereby further improving the quality of the casting.

[0052] Preferably, a molten metal channel 21 is provided in the pouring cup 5, and the molten metal channel 21 can connect the casting mouth 6 of the furnace body 3 with the runner 20, so as to press the steel liquid into the mold 2. The molten metal channel 21 is a conical cavity that is narrow at the top and wide at the bottom, and the cross-sectional area ratio of the upper end and the lower end of the molten metal channel 21 is 1:4, which is convenient for controlling the solidification time.

[0053] Preferably, a tapered hole 23 is provided in the lower end of the pouring cup 5 , and correspondingly, a tapered body 24 is provided on the outer wall of the casting mouth 6 , which is inserted into the tapered hole 23 to facilitate the pouring cup 5 to be engaged with the casting mouth 6 of the furnace body 3 .

[0054] Preferably, the pouring cup 5 is connected to the casting box 4 by screws, which is convenient for disassembly and maintenance.

[0055] Preferably, a liquid outlet 11 connected to the casting mouth 6 is provided at one end of the furnace body 3, and a liquid inlet 12 is provided at the other end. The liquid outlet 11 and the liquid inlet 12 are both connected to the furnace body 3. A heating coil 13 is provided on the periphery of the furnace body 3. The molten steel in the furnace body 3 is heated by the heating coil 13 so that the molten steel can be maintained at 1520-1540 degrees Celsius to reduce riser shrinkage.

[0056] In this embodiment, by separately arranging a liquid inlet 12 and a liquid outlet 11 on the furnace body 3, the positions for adding and discharging the molten steel are separated, so that the positions for adding the molten steel and the positions for the molten steel to flow out each have independent channels. Impurities in the newly added molten steel cannot pass through the bottom of the furnace body 3 to the liquid outlet 11, effectively preventing the problem of impurities affecting die casting, realizing impurity separation, improving the purity of the molten iron, and ensuring the quality of the casting.

[0057] Preferably, a furnace seat 14 is provided around the liquid inlet 12, and a detachable furnace cover 15 is provided on the top of the furnace seat 14. The inflation device is installed on the furnace cover 15, which makes it convenient to open the furnace cover 15 to add molten steel. A sealing ring is provided between the furnace seat 14 and the furnace cover 15 to further improve the sealing performance.

[0058] Preferably, the inflation device includes an air inlet pipe 16 and an exhaust pipe 17, wherein the two ends of the air inlet pipe 16 are respectively connected to the liquid inlet 12 and the inflation pump, and the air inlet pipe 16 is provided with an air inlet valve 18. One end of the exhaust pipe 17 is connected to the liquid inlet 12, and the exhaust pipe 17 is provided with an exhaust valve 19. During die casting, the exhaust valve 19 is closed, the air inlet valve 18 is opened, and the inflation pump injects high-pressure gas into the furnace body 3, squeezing the molten steel out of the liquid outlet 11 to fill the mold; when the filling is completed and the pressure is maintained, the air inlet valve 18 is closed again and the exhaust valve 19 is opened. At this time, the molten steel returns to its original position under the action of gravity, preparing for the next filling.

[0059] Preferably, a hydraulic cylinder 22 is installed above the liquid inlet 12 through a bracket, and the output end of the hydraulic cylinder 22 is connected to the furnace cover 15. The furnace cover 15 is driven to rise and fall by the hydraulic cylinder 22, which is easy to operate, safe and reliable.

[0060] Preferably, the cross-sectional area of ​​the liquid inlet 12 is larger than that of the liquid outlet 11 , and the furnace body 3 is U-shaped, with the liquid inlet 12 and the liquid outlet 11 located at both ends of the opening of the U-shaped furnace body 3 .

[0061] In this embodiment, by setting the cross-sectional area of ​​the liquid inlet 12 to be larger than the cross-sectional area of ​​the liquid outlet 11, and setting the furnace body 3 to be U-shaped, it is convenient to quickly add molten steel, and the rise and fall of the molten steel is ensured, so that the molten steel can rise smoothly in the filling stage, the molten steel is strengthened and compensated for shrinkage in the solidification and pressure holding stage, and the molten steel in the straight runner falls quickly in the pressure relief stage; at the same time, the area of ​​the liquid outlet 11 is relatively small, and impurities are easy to remove. Generally, there are very few impurities after the first mold is cleaned, which effectively improves work efficiency; and by setting the inflation device at the liquid inlet 12 with a larger cross-sectional area, under the same pressure, the liquid discharge speed of the molten steel can be effectively increased, thereby improving the die-casting efficiency.

[0062] Preferably, the bottom of the furnace cover 15 and the top of the furnace base 14 are both conical, and a conical matching structure is adopted between the furnace cover 15 and the furnace base 14 to facilitate the furnace cover 15 to be snapped onto the furnace base 14.

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention. These modifications and improvements will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A negative pressure die casting method for a heat-resistant steel exhaust manifold, characterized in that: The method comprises placing a sand mold into a casting box, then evacuating the casting box to form a negative pressure environment, and finally pressing molten steel into the casting mold to obtain a heat-resistant steel exhaust manifold casting. The method comprises the following steps: S1 Shell and core making: Use shell mold to make sand mold on hot core box machine and assemble it to get casting mold; S2 Casting box: Place the sand mold into the casting box, then fill the casting box on the back of the mold with steel shots and vibrate them, then install the pouring cup at the bottom of the casting box to connect the pouring cup with the casting in the sand mold; S3 Casting box transfer: Move the casting box to the top of the furnace body so that the pouring cup is aligned with the casting mouth of the furnace body; S4 Negative pressure exhaust: Use the exhaust device to exhaust the casting box to form a negative pressure environment inside the casting box; S5 pressure filling: The molten steel in the furnace is pressed into the mold through the casting mouth and pouring cup by the inflation device to complete the filling; S6 solidification pressure relief: maintain pressure on the mold for a period of time during solidification, and then release the pressure on the molten steel; S7 box transfer cooling: move the casting box to the cooling station for cooling; S8 sand cleaning: clean the sand and cut the steel shot to obtain heat-resistant steel exhaust manifold castings; In the above-mentioned S4, the negative pressure in the casting box is 0.02MPa to 0.04MPa; In the above-mentioned S5, the speed of the steel liquid being hydraulically injected into the mold is set according to the pouring time and the pouring weight, and the formula is as follows: v = m / t, wherein v is the speed of the steel liquid being hydraulically injected, m is the weight of the casting, and t is the pouring time; the temperature of the molten steel is maintained at 1520-1540 degrees Celsius during the filling process; In the above-mentioned S6, the solidification holding time of the casting mold is 1 min to 2 min, and the solidification holding pressure is 0.1 MPa to 0.4 MPa; In the step S7, the cooling time of the casting box is 35 to 45 minutes; It can cast thin-walled castings of 3mm-4mm.

2. A device for implementing the negative pressure die casting method of heat-resistant steel exhaust manifold according to claim 1, comprising a sand mold (1), wherein a casting mold (2) of the exhaust manifold casting is formed in the sand mold (1), characterized in that: It also includes a furnace body (3) and a casting box (4), wherein the sand mold (1) is installed in the casting box (4), the casting box (4) is connected to the exhaust device, the outer periphery of the casting box (4) is provided with a pouring cup (5) connected to the casting mold (2), one end of the furnace body (3) is provided with a casting mouth (6) connected to the molten steel in the furnace body (3), the pouring cup (5) is clamped on the casting mouth (6), the other end of the furnace body (3) is connected to the inflation device, one end of the furnace body (3) is provided with a liquid outlet (11) connected to the casting mouth (6), and the other end is provided with a liquid inlet (12), the outer periphery of the furnace body (3) is provided with a heating coil (13), which is close to the inner surface of the sand mold (1). A runner (20) is provided near one end of the pouring cup (5) for connecting the pouring cup (5) with the casting mold (2), and the runner (20) is a cavity with narrow ends at the upper and lower ends and wide in the middle. A molten metal channel (21) is provided in the pouring cup (5), and the molten metal channel (21) is a tapered cavity with narrow upper end and wide lower end, and the cross-sectional area ratio of the upper end to the lower end of the molten metal channel (21) is 1:4; a tapered hole (23) is provided in the lower end of the pouring cup (5), and correspondingly, a tapered body (24) is provided on the outer wall of the casting mouth (6), and the tapered body (24) is inserted into the tapered hole (23). The pouring cup (5) is engaged with the casting mouth (6) of the furnace body (3); in addition, steel shots are filled between the sand mold and the casting box.

3. The heat-resistant steel exhaust manifold negative pressure die-casting device according to claim 2, characterized in that: The exhaust device includes a pressure cover (8) and an exhaust pipe (9), wherein the pressure cover (8) is pressed onto the top of the casting box (4), one end of the exhaust pipe (9) is connected to the casting box (4), and the other end is connected to the exhaust pump, and an exhaust valve (10) is provided on the exhaust pipe (9).

4. The heat-resistant steel exhaust manifold negative pressure die-casting device according to claim 2, characterized in that: The molten steel in the furnace body (3) is heated by the heating coil (13) so that the temperature of the molten steel is maintained at 1520-1540 degrees Celsius.

5. The heat-resistant steel exhaust manifold negative pressure die-casting device according to claim 2, characterized in that: A furnace seat (14) is provided on the periphery of the liquid inlet (12), a detachable furnace cover (15) is provided on the top of the furnace seat (14), and a sealing ring is provided between the furnace seat (14) and the furnace cover (15).

6. The heat-resistant steel exhaust manifold negative pressure die-casting device according to claim 2, characterized in that: The inflation device comprises an air intake pipe (16) and an exhaust pipe (17), wherein both ends of the air intake pipe (16) are respectively connected to the liquid inlet (12) and the inflation pump, and an air intake valve (18) is provided on the air intake pipe (16). One end of the exhaust pipe (17) is connected to the liquid inlet (12), and an exhaust valve (19) is provided on the exhaust pipe (17).

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