Open gravity counterbalanced filling and solidification device and method of filling and solidification using it

Abstract

The application provides an open anti-gravity mold-filling solidification device and a mold-filling solidification method using the same. The open anti-gravity mold-filling solidification device comprises a smelting furnace, a crucible, a furnace cover, a liquid lifting pipe, a mold-filling stopping contact, a mold top contact, a gradient contact, a forced pressure relief contact and an open mold. The open anti-gravity mold-filling solidification method using the open anti-gravity mold-filling solidification device comprises the following steps: step 1, equipment installation; step 2, air charging mold-filling; step 3, pressure relief mold-filling; and step 4, pressure maintaining solidification. The application can guarantee the alloy quality inside the mold cavity of a casting, realize stable mold-filling and bottom gate feeding in the solidification process of the casting, improve the casting quality, significantly improve the mold exhaust capacity, eliminate the back pressure of the mold cavity, guarantee the complete formation of the casting and avoid the gas from entering the alloy to form a gas hole defect. The application has high production efficiency, stability and safety.

Description

Technical Field

[0001] This invention relates to the structural design of anti-gravity casting equipment and the field of anti-gravity casting technology, and particularly to an open anti-gravity filling and solidification device and a filling and solidification method using it. Background Technology

[0002] Anti-gravity casting is a casting process developed in the 1950s. It involves using pressure to push metal from the crucible upwards through a riser tube, overcoming gravity and other resistances to fill the mold and obtain the casting. Depending on the pressure applied during the filling process, anti-gravity casting can be categorized into low-pressure casting, differential pressure casting, pressure-regulating casting, and vacuum casting. Anti-gravity casting technology allows for the extraction of pure molten alloy from the center of the crucible to smoothly fill the mold cavity, while simultaneously solidifying the mold under external force, thus improving casting quality.

[0003] Currently, anti-gravity casting technology is widely used in the research and mass production of high-end aluminum and magnesium alloy castings in the aerospace, aviation, and automotive industries. The traditional method involves using air pressure or a mechanical pump to propel the molten alloy from the center of the crucible along a riser pipe, entering the mold cavity and stopping the air intake at the top contact point to complete the filling. However, the viscosity of the molten alloy is significantly affected by the temperature field during the filling process. The molten alloy encounters considerable resistance when flowing through filters, thin-walled cavities, and complex structures, slowing its ascent. This results in a discrepancy between the pressure inside the melting furnace and the actual liquid level, leading to excessively high pressure inside the furnace after the molten alloy reaches the top contact point. If an open mold is used, a large amount of molten alloy will spray out from the riser, causing significant waste and seriously affecting equipment and personnel safety.

[0004] Therefore, all anti-gravity casting equipment used in China employs closed-cavity molds to prevent molten alloy from overflowing. However, this requires covering the top of the mold before pouring, increasing costs. Furthermore, during solidification, it's impossible to use a ladle to replenish the riser, and the top has a long flow distance and low temperature, resulting in low feeding efficiency. Simultaneously, the closed top severely restricts the mold's venting capacity. During pouring, when the high-temperature molten alloy comes into contact with the sand mold, the resin curing agent inside the mold decomposes, generating a large amount of gas that cannot be expelled in time. This leads to a rapid increase in cavity pressure, a decrease in the alloy's filling capacity, and the formation of cold shut defects in thin-walled, complex structural areas of the casting. Some gas even breaks through the alloy surface and enters the casting interior, forming porosity defects. In addition, the gases generated after the decomposition of resin and curing agent in the sand core are mostly flammable, causing a rapid increase in the concentration of flammable gases inside the cavity during pouring, posing a safety risk under high temperatures.

[0005] Therefore, there is a need for an open-type anti-gravity filling and solidification device and method to meet the requirements of complete forming and quality control of complex structural castings and to ensure production safety. Summary of the Invention

[0006] This invention provides an open anti-gravity filling and solidification apparatus and method, which mainly uses anti-gravity to continuously transport the molten alloy to the cavity of the open mold 9 until it reaches the top of the open riser 92. The molten alloy inside the cavity is kept suspended until solidification by means of air filling, pressure relief filling and suspension pressure holding.

[0007] The technical solution of this invention is as follows:

[0008] An open-type anti-gravity filling and solidification device, the key technology of which is: it includes a melting furnace 1, a crucible 2, a furnace cover 3, a riser pipe 4, a filling stop contact 5, a mold top contact 6, a gradient contact 7, a forced pressure relief contact 8, an open-type mold 9, and a control cabinet; wherein: the crucible 2 is placed inside the melting furnace 1, the furnace body is equipped with an air inlet valve 17 and an air outlet valve 18, the furnace cover 3 is installed above the melting furnace 1, the riser pipe 4 is installed on the furnace cover 3, and the open-type mold 9 is placed entirely above the riser pipe 4 and the furnace cover 3.

[0009] The preferred technical content to be protected in the aforementioned open-type anti-gravity filling and solidification device is:

[0010] The furnace cover 3 and the flange of the smelting furnace 1 have a sealing groove 11. Graphite packing or asbestos packing can be placed in the sealing groove 11 for sealing. The furnace cover 3 is designed with multiple liquid riser installation platforms 12. When no liquid riser 4 is placed, a steel circular plate 13 of equal area is used for sealing. The installation platform of the liquid riser 4 is designed with a trapezoidal steel flow-blocking ring 14 around it.

[0011] An asbestos gasket 15 is placed between the bottom of the flange of the riser pipe 4 and the center of the furnace cover 3, and bolts are used for connection and sealing; tightening the bolts seals the connection, which is a conventional connection method.

[0012] For large-capacity casting, 1 to 10 riser pipes 4 are used to simultaneously cast at multiple predetermined sprue points 91 below the mold 9.

[0013] The top of the mold 9 is not closed, and the risers 92 are all open. A fireproof layer 93 with a thickness of 100-500mm is placed on the top of all risers 92. The bottom of the mold 9 is designed with a flow-blocking groove 95, which is matched with the flow-blocking ring 14 of the furnace cover 3 to position and prevent the alloy liquid from flowing out from the bottom of the mold. An asbestos gasket 15 is placed between the near the direct pouring gate 91 of the mold 9 and the upper plane of the flange of the riser pipe 4. The mold 9 is sealed by its own weight or by placing a heavy object on top of the mold 9.

[0014] The filling stop contact 5, top contact 6, gradient contact 7, and forced pressure relief contact 8 are all wrapped with high-strength heat-resistant insulating ceramic tubes of boron nitride (BN) or alumina (Al2O3).

[0015] The ceramic tube is flush with the wall of mold 9, with the center contact extending 1-2 mm beyond the cross-section of the ceramic tube. The filling stop contact 5 is installed inside the open mold 9, and the mold top contact 6 is installed at the top of the riser 92 of the open mold 9. The gradient contact 7 and the forced pressure relief contact 8 are both installed in a gradient inside the fireproof layer 93. All solenoid valves and contacts in the entire device are connected to the equipment control cabinet. The ceramic tube ensures that the contacts will not conduct before contacting the molten alloy, avoiding incorrect signal transmission. After contacting the molten alloy and allowing it to solidify, the contacts can be easily removed and reused.

[0016] The filling stop contact 5 is installed at 1 / 5 to 1 / 2 of the height of the top riser 92 of the open mold 9. The mold top contact 6 is placed on top of the riser 92. 3 to 10 gradient contacts 7, numbered L1 to L2, are provided in the fireproof layer 93 above the riser 92. n The risers are arranged at equal heights in a gradient pattern, with a height interval H = 10-200mm. A forced pressure relief contact 8 is installed at the top of the fireproof layer 93. The innovation lies in achieving gradient pressure relief through the above operation, ensuring that the molten alloy remains stably within the height range of the fireproof layer 93 without overflowing. Ultimately, with the riser fully open, the molten alloy is allowed to fill and solidify smoothly in the form of anti-gravity.

[0017] The open anti-gravity filling and solidification method using the aforementioned open anti-gravity filling and solidification apparatus includes the following steps and contents in sequence:

[0018] Step 1, Equipment Installation: After the alloy melting is completed, cover the furnace cover 3 and tighten the bolts to seal it; according to the position of the direct sprue 91 of the open mold 9, open the steel circular plate 13 above the corresponding riser pipe 4 installation platform, insert the riser pipe 4 and tighten the flange bolts of the riser pipe 4 to ensure the sealing between the bottom surface of the riser pipe 4 flange and the installation platform; place a filter screen and an asbestos gasket 15 on the upper surface of the riser pipe 4 flange, align the bottom flow-blocking groove 95 of the open mold 9 with the center of the flow-blocking ring 14 of the furnace cover 3, place it above the furnace cover 3 and the riser pipe 4, and press the asbestos gasket 15 to achieve a seal; connect the filling stop contact 5, the mold top contact 6, the gradient contact 7, and the forced pressure relief contact 8 to the control silicon wire respectively;

[0019] Step 2, Air intake and filling: The control cabinet opens the air intake valve 17 to introduce compressed air into the melting furnace 1, pushing the molten alloy through the riser pipe 4 into the cavity of the open mold 9. When the molten alloy reaches the root of the riser 92, the filling stop contact 5 is closed, and the control cabinet closes the air intake valve 17 to stop the air intake.

[0020] Step 3, Depressurization and Molding: After the air intake stops, the air pressure inside the melting furnace 1 pushes the molten alloy to continue rising, eventually reaching the top of riser 92. Then, mold top contact 6 is connected, and the control cabinet controls the exhaust valve 18 to open. A depressurization is completed according to the set value P0. Here, P0 is based on empirical data obtained from experiments and needs to be manually set according to different casting structures, gating systems, and casting process parameters. If the molten alloy continues to rise into the fireproof layer 93, it will rise until the liquid surface above it enters the fireproof layer 93. Gradient contacts 71 to n are connected in sequence, and the control cabinet performs gradient depressurization according to the set gradient value P1. That is, when gradient contact 7n is connected, the automatic depressurization value is n×P1, until the molten alloy stops rising and hovers above mold top contact 6. The alloy is arranged at equal height intervals. The relationship between the set value P1 and the interval height H is P1 = 0.5 ~ 1ρgH}, which ensures that when the alloy liquid surface reaches the nth contact point, after the n×P1 pressure is released, the maximum downward distance that the alloy liquid surface may reach does not exceed n×H. That is, the liquid surface height will not be lower than the top height of the mold, thus ensuring the integrity of the casting filling.

[0021] Step 4, pressure holding and solidification: After the aluminum liquid is suspended, the control cabinet controls the intermittent opening and closing of the air inlet valve 17 to maintain a constant air pressure in the melting furnace 1, with an upward and downward fluctuation error within ±1KPa, until the alloy solidifies in the mold cavity of the casting mold 9; finally, an aluminum alloy casting solidified by open anti-gravity filling is obtained.

[0022] The relationship between the gradient contact 7 interval height H and the alloy liquid density ρ, gravitational acceleration g, and gradient pressure relief value P1 is P1 = (0.5~1.5)ρgH.

[0023] As a preferred embodiment, the filling stop contact 5, mold top contact 6, gradient contact 7, and forced pressure relief contact 8 can all be wrapped with a thin-walled, high-strength, heat-resistant, insulating ceramic tube with an inner diameter of 0.1–2 mm and placed in a fixed position on the metal mold 9. Only the contact tip 0.1–0.5 mm extends into the mold cavity and comes into contact with the molten alloy during the filling process. After filling is completed, the casting is removed from the side and the contact tip is cleaned, so that it can be reused, thus meeting the requirement of multiple reuse of contacts in the automated batch production process of metal molds.

[0024] In summary, the open-type anti-gravity filling and solidification device of the present invention includes a melting furnace 1, a crucible 2, a furnace cover 3, a riser pipe 4, a filling stop contact 5, a mold top contact 6, a gradient contact 7, a forced pressure relief contact 8, and an open-type casting mold 9. The technical approach adopted by the present invention is as follows: After the alloy melting is completed, compressed gas is introduced into the melting furnace 1 to transport the molten alloy along the riser pipe 4 into the casting mold 9. When the molten alloy level inside the casting mold 9 reaches the filling stop contact 5, the gas supply is stopped. Due to the pressure difference inside the furnace, the molten alloy continues to rise. After reaching the mold top contact 6, a certain amount of gas pressure is released from the furnace. If the molten alloy continues to rise, the gradient contact 7 lights up step by step, releasing the furnace pressure in stages according to different pressure relief values ​​until the molten alloy level stabilizes. Pressure is maintained until the casting solidifies. If the molten alloy continues to rise to the forced pressure relief contact 8, all gas pressure inside the furnace is forcibly released to ensure the safety of personnel and equipment.

[0025] The beneficial effects of this invention are as follows:

[0026] This invention enables anti-gravity filling and solidification using an open mold (9), which not only ensures the quality of the alloy entering the casting cavity but also achieves stable filling and bottom gate feeding during solidification, improving casting quality. Simultaneously, it significantly enhances the venting capacity of the mold (9), eliminating back pressure in the cavity, ensuring complete casting formation, and preventing gas from entering the alloy and causing porosity defects. The open anti-gravity filling and solidification method described in this invention is fully automated and unmanned, offering high production efficiency, stability, and safety. The open mold (9) can use either sand molds or metal molds, and automated batch production using metal molds is also possible.

[0027] The technical solution described in this invention utilizes an open mold 9 for anti-gravity filling and solidification, ensuring not only the quality of the alloy entering the casting cavity but also achieving stable filling and bottom gate feeding during solidification, thus improving casting quality. Simultaneously, it significantly enhances the venting capacity of the mold 9, eliminating back pressure in the cavity, ensuring complete casting formation, and preventing gas from entering the alloy and causing porosity defects. Open-type filling is suitable for sand molds, shell molds, and metal molds; all contacts can be reused repeatedly without reconnection; the entire process is fully automated and unmanned, offering high production efficiency, stability, and safety. Attached Figure Description

[0028] Figure 1 This is an overall structural diagram of the open-type anti-gravity filling and solidification device described in this invention;

[0029] Figure 2 This is a partial sectional view of open mold 9;

[0030] Figure 3 This is a magnified view of a portion of the contact installation area;

[0031] Figure 4This is a schematic diagram of the overall structure of smelting furnace 1;

[0032] Figure 5 This is a cross-sectional view of smelting furnace 1;

[0033] Figure 6 This is a partial cross-sectional view of region 4 of the riser tube. Detailed Implementation

[0034] The present invention will be further described below with reference to the embodiments and accompanying drawings, but is not limited thereto.

[0035] Example 1

[0036] An open-type antigravity filling and solidification device, such as Figures 1-6 As shown; it includes a smelting furnace 1, a crucible 2, a furnace cover 3, a riser pipe 4, a filling stop contact 5, a mold top contact 6, a gradient contact 7, a forced pressure relief contact 8, an open mold 9, and a control cabinet; wherein: the crucible 2 is placed inside the smelting furnace 1, the furnace body is equipped with an air inlet valve 17 and an air outlet valve 18, the furnace cover 3 is installed above the smelting furnace 1, the riser pipe 4 is installed on the furnace cover 3, and the open mold 9 is placed entirely above the riser pipe 4 and the furnace cover 3.

[0037] The furnace cover 3 and the flange of the smelting furnace 1 have a sealing groove 11. Graphite packing or asbestos packing can be placed in the sealing groove 11 for sealing. The furnace cover 3 is designed with multiple liquid riser installation platforms 12. When no liquid riser 4 is placed, a steel circular plate 13 of equal area is used for sealing. The installation platform of the liquid riser 4 is designed with a trapezoidal steel flow-blocking ring 14 around it.

[0038] An asbestos gasket 15 is placed between the bottom of the flange of the riser pipe 4 and the center of the furnace cover 3, and bolts are used for connection and sealing; tightening the bolts seals the connection, which is a conventional connection method.

[0039] For large-capacity casting, 1 to 10 riser pipes 4 are used to simultaneously cast at multiple predetermined sprue points 91 below the mold 9.

[0040] The top of the mold 9 is not closed, and the risers 92 are all open. A fireproof layer 93 with a thickness of 100-500mm is placed on the top of all risers 92. The bottom of the mold 9 is designed with a flow-blocking groove 95, which is matched with the flow-blocking ring 14 of the furnace cover 3 to position and prevent the alloy liquid from flowing out from the bottom of the mold. An asbestos gasket 15 is placed between the near the direct pouring gate 91 of the mold 9 and the upper plane of the flange of the riser pipe 4. The mold 9 is sealed by its own weight or by placing a heavy object on top of the mold 9.

[0041] The filling stop contact 5, top contact 6, gradient contact 7, and forced pressure relief contact 8 are all wrapped with high-strength heat-resistant insulating ceramic tubes of boron nitride (BN) or alumina (Al2O3).

[0042] The ceramic tube is flush with the wall of mold 9, with the center contact extending 1-2 mm beyond the cross-section of the ceramic tube. The filling stop contact 5 is installed inside the open mold 9, and the mold top contact 6 is installed at the top of the riser 92 of the open mold 9. The gradient contact 7 and the forced pressure relief contact 8 are both installed in a gradient inside the fireproof layer 93. All solenoid valves and contacts in the entire device are connected to the equipment control cabinet. The ceramic tube ensures that the contacts will not conduct before contacting the molten alloy, avoiding incorrect signal transmission. After contacting the molten alloy and allowing it to solidify, the contacts can be easily removed and reused.

[0043] The filling stop contact 5 is installed at 1 / 5 to 1 / 2 of the height of the top riser 92 of the open mold 9. The mold top contact 6 is placed on top of the riser 92. 3 to 10 gradient contacts 7, numbered L1 to L2, are provided in the fireproof layer 93 above the riser 92. n The risers are arranged at equal heights in a gradient pattern, with a height interval H = 10-200mm. A forced pressure relief contact 8 is installed at the top of the fireproof layer 93. The innovation lies in achieving gradient pressure relief through the above operation, ensuring that the molten alloy remains stably within the height range of the fireproof layer 93 without overflowing. Ultimately, with the riser fully open, the molten alloy is allowed to fill and solidify smoothly in the form of anti-gravity.

[0044] Example 2

[0045] The open anti-gravity filling and solidification method using the open anti-gravity filling and solidification apparatus described in Example 1 includes the following steps and contents in sequence:

[0046] Step 1, Equipment Installation: After the alloy melting is completed, cover the furnace cover 3 and tighten the bolts to seal it; according to the position of the direct sprue 91 of the open mold 9, open the steel circular plate 13 above the corresponding riser pipe 4 installation platform, insert the riser pipe 4 and tighten the flange bolts of the riser pipe 4 to ensure the sealing between the bottom surface of the riser pipe 4 flange and the installation platform; place a filter screen and an asbestos gasket 15 on the upper surface of the riser pipe 4 flange, align the bottom flow-blocking groove 95 of the open mold 9 with the center of the flow-blocking ring 14 of the furnace cover 3, place it above the furnace cover 3 and the riser pipe 4, and press the asbestos gasket 15 to achieve a seal; connect the filling stop contact 5, the mold top contact 6, the gradient contact 7, and the forced pressure relief contact 8 to the control silicon wire respectively;

[0047] Step 2, Air intake and filling: The control cabinet opens the air intake valve 17 to introduce compressed air into the melting furnace 1, pushing the molten alloy through the riser pipe 4 into the cavity of the open mold 9. When the molten alloy reaches the root of the riser 92, the filling stop contact 5 is closed, and the control cabinet closes the air intake valve 17 to stop the air intake.

[0048] Step 3, Depressurization and Molding: After the air intake stops, the air pressure inside the melting furnace 1 pushes the molten alloy to continue rising, eventually reaching the top of riser 92. Then, mold top contact 6 is connected, and the control cabinet controls the exhaust valve 18 to open. A depressurization is completed according to the set value P0. Here, P0 is based on empirical data obtained from experiments and needs to be manually set according to different casting structures, gating systems, and casting process parameters. If the molten alloy continues to rise into the fireproof layer 93, it will rise until the liquid surface above it enters the fireproof layer 93. Gradient contacts 71 to n are connected in sequence, and the control cabinet performs gradient depressurization according to the set gradient value P1. That is, when gradient contact 7n is connected, the automatic depressurization value is n×P1, until the molten alloy stops rising and hovers above mold top contact 6. The alloy is arranged at equal height intervals. The relationship between the set value P1 and the interval height H is P1 = 0.5 ~ 1ρgH}, which ensures that when the alloy liquid surface reaches the nth contact point, after the n×P1 pressure is released, the maximum downward distance that the alloy liquid surface may reach does not exceed n×H. That is, the liquid surface height will not be lower than the top height of the mold, thus ensuring the integrity of the casting filling.

[0049] Step 4, pressure holding and solidification: After the aluminum liquid is suspended, the control cabinet controls the intermittent opening and closing of the air inlet valve 17 to maintain a constant air pressure in the melting furnace 1, with an upward and downward fluctuation error within ±1KPa, until the alloy solidifies in the mold cavity of the casting mold 9; finally, an aluminum alloy casting solidified by open anti-gravity filling is obtained.

[0050] The relationship between the gradient contact 7 interval height H and the alloy liquid density ρ, gravitational acceleration g, and gradient pressure relief value P1 is P1 = (0.5~1.5)ρgH.

[0051] The filling stop contact 5, mold top contact 6, gradient contact 7, and forced pressure relief contact 8 can all be wrapped in a thin-walled, high-strength, heat-resistant, insulating ceramic tube with an inner diameter of 0.1–2 mm and placed in a fixed position on the metal mold 9. Only the contact tip 0.1–0.5 mm extends into the mold cavity and comes into contact with the molten alloy during the filling process. After filling is completed, the casting is removed from the side and the contact tip is cleaned, so that it can be reused, thus meeting the requirement of multiple reuse of contacts in the automated batch production process of metal molds.

[0052] Example 3

[0053] The anti-gravity filling and solidification process of a certain aerospace aluminum alloy casting; the specific process is as follows:

[0054] Step 1, Equipment Installation: After the alloy melting is completed, cover the furnace cover 3 and tighten the bolts to seal it. According to the position of the direct sprue 91 of the open mold 9, install the steel circular plate 13 above the installation platform for a total of 3 riser pipes 4 at the center and both ends. After inserting the riser pipes 4, tighten the flange bolts of the riser pipes 4 to ensure the seal between the bottom surface of the flange of the riser pipes 4 and the installation platform. Place the filter screen and asbestos gasket 15 on the upper surface of the flange of the riser pipes 4. After aligning the bottom flow-blocking groove 95 of the open mold 9 with the center of the flow-blocking ring 14 of the furnace cover 3, place it above the furnace cover 3 and the riser pipes 4, and press the asbestos gasket 15 to achieve a seal. Connect the filling stop contact 5, the mold top contact 6, the gradient contact 7, and the forced pressure relief contact 8 to the control cabinet wires respectively.

[0055] Step 2, Air intake and filling: The control cabinet opens the air intake valve 17 and introduces compressed air into the melting furnace 1 at a pressurization rate of 1.5 kPa / s. This pushes the molten alloy through the riser pipe 4 into the cavity of the open mold 9. When the molten alloy reaches the root of the riser 92, the filling stop contact 5 is closed, and the control cabinet closes the air intake valve 17 to stop the air intake.

[0056] Step 3, depressurization and filling: After the air intake stops, the air pressure in the melting furnace 1 pushes the molten alloy to continue rising. Eventually, the molten alloy continues to rise and reaches the top of riser 92. Then, the mold top contact 6 is connected, and the control cabinet controls the exhaust valve 18 to open, depressurizing by 4 kPa. If the molten alloy continues to rise into the fireproof layer 93, the gradient contacts 7 L1 to L5 are connected sequentially to adjacent gradient contacts 7 at 40 mm intervals. The control cabinet automatically depressurizes according to the gradient value of 0.5 kPa until the molten alloy stops rising and hovers above the mold top contact 6.

[0057] Step 4, pressure holding and solidification: After the aluminum liquid is suspended, the control cabinet controls the intermittent opening and closing of the air inlet valve 17 to maintain a constant air pressure in the melting furnace 1, with an upward and downward fluctuation error within ±1KPa, until the alloy solidifies in the cavity of the casting mold 9.

[0058] Example 4

[0059] This embodiment describes the anti-gravity filling and solidification process of a metal mold for an aluminum alloy crossbeam used in a vehicle.

[0060] The specific process is as follows:

[0061] Step 1, Equipment Installation: After the alloy melting is completed, cover the furnace cover 3 and tighten the bolts to seal it. According to the position of the direct sprue 91 of the open mold 9, install the steel circular plate 13 above the central riser pipe 4 on the installation platform. After inserting the riser pipe 4, tighten the flange bolts of the riser pipe 4 to ensure the sealing between the bottom surface of the riser pipe 4 flange and the installation platform. Place a filter screen and an asbestos gasket 15 on the upper surface of the riser pipe 4 flange. After aligning the bottom flow-blocking groove 95 of the open mold 9 with the center of the flow-blocking ring 14 of the furnace cover 3, place it above the furnace cover 3 and the riser pipe 4, and press the asbestos gasket 15 to achieve a seal. Wrap the filling stop contact 5, mold top contact 6, gradient contact 7, and forced pressure relief contact 8 with thin-walled high-strength heat-resistant insulating ceramic tubes with an inner diameter of 2mm, and place them in the fixed position of the metal mold 9, with only the contact ends 0.5mm extending into the mold cavity. Connect the filling stop contact 5, mold top contact 6, gradient contact 7, and forced pressure relief contact 8 to the control cabinet wires respectively.

[0062] Step 2, Air intake and filling: The control cabinet opens the air intake valve 17 and introduces compressed air into the melting furnace 1 at a pressurization rate of 1.5 kPa / s. This pushes the molten alloy through the riser pipe 4 into the cavity of the open mold 9. When the molten alloy reaches the root of the riser 92, the filling stop contact 5 is closed, and the control cabinet closes the air intake valve 17 to stop the air intake.

[0063] Step 3, depressurization and filling: After the air intake stops, the air pressure in the melting furnace 1 pushes the molten alloy to continue rising, eventually reaching the top of riser 92. Then, the mold top contact 6 is connected, and the control cabinet controls the exhaust valve 18 to open, depressurizing by 1.5 kPa. If the molten alloy continues to rise into the fireproof layer 93, the gradient contacts 7L1 to L3 are connected sequentially to adjacent gradient contacts 7 at 25 mm intervals. The control cabinet automatically depressurizes according to a gradient value of 0.3 kPa until the molten alloy stops rising and hovers above the mold top contact 6.

[0064] Step 4, Pressure Holding and Solidification: After the aluminum liquid is suspended, the control cabinet controls the intermittent opening and closing of the air inlet valve 17 to maintain a constant air pressure in the melting furnace 1, with an upward and downward fluctuation error within ±1KPa, until the alloy solidifies in the cavity of the casting mold 9. After solidification is completed, the metal mold is opened, the ejector rod pushes the casting out, and the robotic arm clamps and transfers it. After cleaning the mold and contact surface, the metal mold is closed, and the next round of pouring is carried out.

Claims

1. An open-type anti-gravity filling and solidification device, characterized in that: It includes a smelting furnace (1), a crucible (2), a furnace cover (3), a riser pipe (4), a filling stop contact (5), a mold top contact (6), a gradient contact (7), a forced pressure relief contact (8), and an open mold (9); wherein: the crucible (2) is placed inside the smelting furnace (1), the furnace body is equipped with an air inlet valve (17) and an exhaust valve (18), the furnace cover (3) is installed above the smelting furnace (1), the riser pipe (4) is installed on the furnace cover (3), and the open mold (9) is placed entirely above the riser pipe (4) and the furnace cover (3); the top of the mold (9) is not closed, and the risers (92) are all open; all solenoid valves and contacts of the entire device are connected to the equipment control cabinet; The filling stop contact (5) is installed at 1 / 5 to 1 / 2 of the height of the top riser (92) of the open mold (9). The top contact (6) is placed on the top of the riser (92). 3 to 10 gradient contacts (7) are set in the fireproof layer (93) above the riser (92), and are numbered L1 to L2 respectively. n The fireproof layer (93) is arranged in a gradient at the same height, with a height interval of H=10~200mm. A forced pressure relief contact (8) is set on the top of the fireproof layer (93). The furnace cover (3) and the flange of the smelting furnace (1) have a sealing groove (11). Graphite packing or asbestos packing can be placed in the sealing groove (11) for sealing. The furnace cover (3) is designed with multiple riser pipe installation platforms (12). When no riser pipe (4) is placed, a steel circular plate (13) of equal area is used for sealing. The riser pipe (4) installation platform is designed with a trapezoidal steel flow-blocking ring (14) around it. An asbestos gasket (15) is placed between the bottom of the flange of the riser pipe (4) and the center of the furnace cover (3), and bolts are used for connection and sealing. For large-capacity casting, 1 to 10 riser pipes (4) are used to simultaneously cast at multiple predetermined direct sprue (91) points below the mold (9).

2. The open-type anti-gravity filling and solidification device according to claim 1, characterized in that: A fireproof layer (93) with a thickness of 100~500mm is placed on the top of all risers (92). A flow-blocking groove (95) is designed at the bottom of the mold (9) to match and position the flow-blocking ring (14) of the furnace cover (3) and prevent the alloy liquid from flowing out from the bottom of the mold. An asbestos gasket (15) is placed between the near the direct pouring gate (91) of the mold (9) and the upper plane of the flange of the riser pipe (4). The mold (9) is sealed by its own weight or by placing a heavy object on top of the mold (9).

3. The open-type anti-gravity filling and solidification device according to claim 2, characterized in that: The filling stop contact (5), top contact (6), gradient contact (7), and forced pressure relief contact (8) are all wrapped with high-strength heat-resistant insulating ceramic tubes of boron nitride (BN) or alumina (Al2O3). The ceramic tube is flush with the wall of the mold (9), and the center contact point extends 1~2mm beyond the cross-section of the ceramic tube.

4. The open-type anti-gravity filling and solidification method using the open-type anti-gravity filling and solidification apparatus of claim 3, characterized in that: The specific process of this method includes the following steps and contents in sequence: (1) Equipment installation: After the alloy melting is completed, cover the furnace cover (3) and tighten the bolts to seal it; according to the position of the direct pouring gate (91) of the open mold (9), open the steel circular plate (13) above the corresponding riser pipe (4) installation platform, insert the riser pipe (4) and tighten the flange bolts of the riser pipe (4) to ensure the sealing between the bottom surface of the riser pipe (4) flange and the installation platform; place the filter screen and asbestos gasket (15) on the upper plane of the riser pipe (4) flange, align the bottom flow blocking groove (95) of the open mold (9) with the center of the flow blocking ring (14) of the furnace cover (3), place it above the furnace cover (3) and the riser pipe (4), press the asbestos gasket (15) to achieve sealing; connect the filling stop contact (5), mold top contact (6), gradient contact (7), and forced pressure relief contact (8) to the control silicon wire respectively; (2) Air intake and filling: The control cabinet controls the air intake valve (17) to open and introduce compressed air into the melting furnace (1), pushing the alloy liquid through the riser pipe (4) into the cavity of the open mold (9). When the alloy liquid reaches the root of the riser (92), the filling stop contact (5) is connected, and the control cabinet closes the air intake valve (17) to stop the air intake; (3) Depressurization and filling: After the gas intake stops, the gas pressure in the melting furnace (1) pushes the alloy liquid to continue to rise, and eventually the alloy liquid continues to rise. After reaching the top of the riser (92), the mold top contact (6) is connected, and the control cabinet controls the exhaust valve (18) to open; a depressurization is completed according to the set value P0; if the alloy liquid continues to rise and enters the fireproof layer (93), the gradient contacts (7) 1~n are connected in sequence, and the control cabinet performs gradient depressurization according to the set gradient value P1. That is, when the gradient contact (7) n is connected, the automatic depressurization value is n×P1 until the alloy liquid stops rising and hovers above the mold top contact (6); (4) Pressure holding and solidification: After the aluminum liquid is suspended, the control cabinet controls the intermittent opening and closing of the air inlet valve (17) to keep the air pressure in the melting furnace (1) constant, with an upward and downward fluctuation error within ±1KPa, until the alloy solidifies in the mold cavity (9).

5. The open-type anti-gravity filling and solidification method according to claim 4, characterized in that: The relationship between the gradient contact (7) interval height H and the alloy liquid density ρ, gravitational acceleration g and gradient pressure relief value P1 is P1 = (0.5~1)ρgH.

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