Low-pressure casting equipment and casting method

Abstract

The invention belongs to the technical field of casting equipment, and particularly relates to low-pressure casting equipment and a casting method.The low-pressure casting equipment comprises an upper pressure chamber and a lower pressure chamber, a crucible is arranged in the lower pressure chamber, an electric heating furnace is arranged between the crucible and the lower pressure chamber, the interior of the crucible is heated through the electric heating furnace, and metal is heated and melted; a middle partition plate is connected between the upper pressing chamber and the lower pressing chamber, the upper pressing chamber and the lower pressing chamber are divided through the middle partition plate, a sand box located at the upper end of the middle partition plate is arranged in the upper pressing chamber, a cavity is formed in the sand box, metal is cast and formed by pouring molten metal into the cavity, and a sand core is connected to the center position in the sand box. Four vertical cylinders distributed in an equal circumference mode are connected between the sand core and the cavity, gap pouring gates are communicated between the vertical cylinders and the sand core, and conveying of molten metal is achieved through the gap pouring gates. And the practicability is high.

Description

Technical Field

[0001] The invention relates to the technical field of casting equipment, in particular to a low-pressure casting equipment and a casting method. Background Art

[0002] Differential pressure casting is a casting method derived from low-pressure casting. This casting method adds a cover to the casting shape, fills it with compressed air, and puts the casting mold under a certain gas pressure. When the alloy liquid fills the casting mold from bottom to top, the casting can crystallize and solidify under higher pressure, obtaining a casting with higher density.

[0003] The Chinese patent application number CN202410835954.8 discloses a large tank container differential pressure casting machine. The large tank container differential pressure casting machine of the present invention is a new large tank casting equipment derived from traditional differential pressure casting. It is an air intake and filling system for large-volume products. The quality of the castings produced by it has been greatly improved by testing and analyzing the castings. The present invention solves the problem that it is difficult to perform differential pressure casting on large metal casting products to improve product performance.

[0004] The Chinese patent application number CN202211514147.3 discloses a casting process for thin-walled metal castings. First, the casting process of the present invention is completed by using a precision casting silica sol ceramic mold shell in combination with Pipe resin sand molding, and using a differential pressure pouring method. By adopting differential pressure pouring that is easier to fill the mold, the phenomenon of insufficient pouring is reduced, and the pouring process is carried out under pressure, which is conducive to shrinkage compensation of castings and reduces defects such as shrinkage, shrinkage cavities, and pinholes; the mold shell does not need to be preheated to a high temperature (below 120°C), and can even be preheated without ensuring that the cavity is dry, and it can be achieved Rapid filling of the mold, faster solidification of the molten metal, and reduced defects such as pinholes and shrinkage. More importantly, after repeated verification, the thinnest wall thickness of the cast metal casting can reach less than 2.0 mm; compared with the traditional sand mold differential pressure casting cavity, because the prefabricated silica sol precision casting ceramic shell has high strength and good surface quality, the boost pressure is set to (1.6-2.25)P, which can still ensure the strength of the mold shell, without sand sticking and deformation, while the traditional differential pressure casting boost pressure can only reach 1.5P at most, ensuring the dimensional accuracy and surface finish of the casting, and reducing the risk of sand sticking and deformation caused by differential pressure casting. Second, the thin-walled metal parts produced by the casting process of the present invention not only ensure the dimensional accuracy and surface finish of the casting, but also can well ensure the pouring and filling capacity, and have good internal quality, without defects such as looseness, shrinkage holes and pinholes, which greatly improves the yield of thin-walled metal castings and greatly reduces production costs. However, the following problems still exist in actual applications, specifically: 1. In the differential pressure casting process of metal, bubbles will appear in the process of metal melting into solution. The bubbles will be mixed in the metal solution, causing the bubbles to flow with the metal solution, thus affecting the quality of the casting and causing pores or pinholes. 2. When melting metal in a crucible, impurities will be generated. Unfiltered metal solution will solidify after entering the cavity, which will affect the appearance of the product and even cause the product to be scrapped. 3. In the process of controlling the pressure difference, the solution is driven only by the change of pressure in the chamber, which requires a large pressure value. At the same time, the flow of the liquid will be unstable, causing fluctuations. At the same time, the metal solution refluxes by gravity, and the reflux speed is slow. At the same time, it will cause partial solidification during the reflux process, affecting the use of the entire equipment, and the equipment needs to be frequently unblocked and cleaned.

[0005] Therefore, the present invention provides a low pressure casting device and a casting method to solve the above problems. Summary of the invention

[0006] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a low-pressure casting equipment and a casting method, which effectively solves the problems of differential pressure casting of metal, bubble removal during the casting process, and ensuring the cleanliness of the casting solution and the smoothness of the reflux of the metal solution.

[0007] The present invention comprises an upper pressure chamber, a lower pressure chamber and a lifting device, wherein the upper pressure chamber is lifted by the lifting device, a crucible is arranged inside the lower pressure chamber, an electric heating furnace is arranged between the crucible and the lower pressure chamber, and the electric heating furnace is used to heat the inside of the crucible to heat and melt the metal; A middle partition is connected between the upper pressure chamber and the lower pressure chamber, and the upper pressure chamber and the lower pressure chamber are divided by the middle partition. A sand box located at the upper end of the middle partition is arranged in the upper pressure chamber, and a cavity is arranged inside the sand box. The casting of the metal is achieved by pouring molten metal into the cavity. A sand core is connected to the center of the sand box, and four vertical cylinders with equal circumferences are connected between the sand core and the cavity. A gap runner is connected between the vertical cylinder and the sand core, and the molten metal is transported through the gap runner. A liquid supply pipe is arranged inside the crucible, the lower end of the liquid supply pipe is arranged at the bottom of the crucible, the upper end of the liquid supply pipe is connected to a horizontal runner arranged at the lower part of the lower pressure chamber, and the horizontal runner is connected to the vertical tube; The upper pressure chamber and the lower pressure chamber are both connected to a pressure regulating structure, and the pressure of the upper pressure chamber and the lower pressure chamber is regulated by the pressure regulating structure to ensure the pressure difference between the upper pressure chamber and the lower pressure chamber; The lifting device comprises a sliding track placed on the ground, a sliding door frame is slidably connected to the sliding track, the lower end of the sliding door frame is threadedly connected to a sliding screw rod rotatably connected to the inside of the sliding track, both sides of the sliding door frame are slidably connected to lifting frames, the two lifting frames are symmetrically distributed, and a lifting bracket is fixedly connected to the lifting frame; The lifting bracket is threadedly connected to a lifting screw rotatably connected in the sliding track, and the two lifting screws are connected through a sprocket transmission mechanism, and one of the lifting screws is connected to a driving motor connected to the sliding door frame.

[0008] Preferably, the pressure regulating structure comprises two hydraulic cylinders connected with symmetrical gaps, each of the hydraulic cylinders being slidably connected with a sliding piston, an adjusting screw being coaxially fixedly connected between the two sliding pistons, a connecting frame being connected between the two hydraulic cylinders, an adjusting threaded sleeve being rotatably connected to the connecting frame, the adjusting threaded sleeve being threadedly connected to the adjusting screw, and the hydraulic cylinders being respectively connected with the upper pressure chamber and the lower pressure chamber.

[0009] Preferably, a vibration tube is coaxially fixedly connected inside the liquid supply tube, a willow-leaf-shaped vibration cavity is opened at the axis of the vibration tube, a vibration rod coaxially arranged with the vibration tube is rotatably connected inside the vibration cavity, a plurality of vibration ball rods are fixedly connected to the vibration rod, and during the rotation process of the vibration rod, the vibration tube is struck by the vibration ball rod to achieve vibration of the vibration tube; An adjusting chamber is provided at the axis center of the lower end of the vibration rod, and a spiral track is also provided inside the adjusting chamber. A lifting adjusting rod is coaxially connected to slide up and down inside the adjusting chamber, and a reciprocating threaded sleeve is coaxially threadedly connected to the lifting adjusting rod. The reciprocating threaded sleeve is coaxially fixedly connected to a rotating shaft sleeve rotatably connected to the bottom of the crucible, and the rotating shaft sleeve is connected to a driving device arranged inside the lower pressure chamber.

[0010] Preferably, a rotating frame is coaxially fixedly connected to the rotating sleeve, a plurality of stirring rods are fixedly connected to the rotating frame, and a plurality of stirring paddles distributed at equal intervals are rotatably connected to the stirring rods.

[0011] Preferably, a filter mesh is fixedly connected to the lower end of the liquid supply pipe, a rotating scraper is sleeved on the outer wall of the vibration rod, and the rotating scraper is in contact with the filter mesh; The upper end of the liquid supply pipe is connected to a transfer pipe, the inner diameter of the transfer pipe is larger than the inner diameter of the liquid supply pipe, the transfer pipe is thick in the middle and thin at both ends, a tapered pipe is connected between the transfer pipe and the cross runner, the upper end of the transfer pipe is fixedly connected to a tapered exhaust pipe, the inner wall of the upper side of the transfer pipe is provided with a transfer bin located directly below the tapered exhaust pipe, the lower end of the tapered exhaust pipe is fixedly connected to a one-way vent valve placed inside the transfer bin, the tapered exhaust pipe is connected to an external negative pressure device, so that the inside of the tapered exhaust pipe is in a negative pressure state; A conical sliding plug is coaxially slidably connected in the conical tube. The conical sliding plug and the conical tube are connected via a spring. Under the action of the spring, the conical sliding plug and the conical tube fit together to form a seal for the conical tube.

[0012] Preferably, the driving device includes a heat insulation plate placed at the lower end of the electric heating furnace, the outer edge of the heat insulation plate is in contact with the inner wall of the lower pressure chamber, the heat insulation plate and the bottom surface of the lower pressure chamber are clearance matched, the lower end of the heat insulation plate is fixedly connected to a driving motor, and the driving motor and the rotating shaft sleeve are connected through a transmission mechanism.

[0013] Preferably, a pressurizing sliding plate connected to the liquid supply pipe in an up-and-down sliding manner is disposed inside the crucible, and the outer wall surface of the pressurizing sliding plate is in contact with the inner wall surface of the crucible.

[0014] Preferably, an upper pressure supply chamber and a lower pressure supply chamber are opened inside the middle partition, the upper pressure supply chamber is located above the lower pressure supply chamber, the upper pressure supply chamber and the lower pressure supply chamber are respectively connected to the upper pressure chamber and the lower pressure chamber, the upper pressure supply chamber and the lower pressure supply chamber are both connected to pressure supply pipes, and the pressure supply pipes are respectively connected to the hydraulic cylinder through conduits.

[0015] Preferably, a conical hole is formed on the conical sliding plug, a reflux conical plug is slidably connected in the conical hole, and the reflux conical plug and the conical sliding plug are connected via a spring.

[0016] A casting process for low-pressure metal casting comprises the following steps, specifically: Step 1: firstly, placing a metal substance inside the crucible, and melting the metal substance by the electric heating furnace; Step 2: After the melting is completed, the pressure inside the upper pressure chamber and the lower pressure chamber is adjusted by the pressure regulating structure, and then the casting pressure is ensured to be 0.6Mpa, and the pressure difference between the upper pressure chamber and the lower pressure chamber is ensured to be about 50KPa; Step 3: Under the differential pressure state, the molten metal enters the transfer pipe through the liquid supply pipe, and at the same time, the vibration pipe vibrates to vibrate the molten metal entering the liquid supply pipe for exhaust treatment; Step 4: The molten metal flows into the tapered tube, the horizontal runner, and the vertical tube, and then pours the molten metal into the mold cavity through the slit runner; Step 5: After the injection is completed, the upper pressure chamber is subjected to pressure maintenance treatment; Step 6: After casting, the pressure regulating structure is reversed to increase the pressure in the upper pressure chamber and decrease the pressure in the lower pressure chamber, and the molten metal flows back into the crucible for next use.

[0017] The present invention improves the existing low-pressure casting equipment and has the following beneficial effects: 1. The problem of differential pressure casting and porosity defects of metals is effectively solved by setting the upper pressure chamber, the lower pressure chamber, the middle partition, the crucible, the liquid supply pipe, the vertical cylinder, the gap runner, the horizontal runner and the pressure regulating structure; 2. The problem of vibrating and exhausting the metal solution in the liquid supply pipe is effectively achieved by setting a vibration tube, a vibration rod, a vibration chamber, a vibration ball rod, a lifting and lowering adjustment rod, a spiral track, and a limit pin; 3. By setting up structures such as transfer pipe, tapered pipe, tapered exhaust pipe, transfer bin, one-way vent valve, tapered sliding plug, etc., the problem of preliminary exhaust of the metal solution at the upper end of the liquid supply pipe, extending the residence time of the metal solution in the transfer pipe, and facilitating the rising and discharge of gas is effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the differential pressure casting principle of the present invention.

[0019] Figure 2 It is a three-dimensional schematic diagram of the present invention.

[0020] Figure 3 It is a schematic diagram of the liquid supply pipe and its connecting parts of the present invention.

[0021] Figure 4 It is a cross-sectional schematic diagram of the liquid supply pipe and its connecting parts of the present invention.

[0022] Figure 5 It is a schematic cross-sectional view of the pressure regulating structure of the present invention.

[0023] Figure 6 It is a schematic diagram of the internal structure of the liquid supply pipe of the present invention.

[0024] Figure 7 For the present invention Figure 6 A partial enlarged schematic diagram in the middle.

[0025] Figure 8 This is a schematic diagram of the vibration tube and its internal structure of the present invention.

[0026] Fig. 9 It is a schematic diagram of the stirring rod and its connecting parts of the present invention.

[0027] Fig.10 It is a schematic diagram of the sliding door frame and its connecting parts of the present invention.

[0028] Figure numerals: 1, upper pressure chamber; 2, lower pressure chamber; 3, crucible; 4, electric heating furnace; 5, middle partition; 6, sand box; 7, cavity; 9, vertical cylinder; 10, gap pouring channel; 11, liquid supply pipe; 12, hydraulic cylinder; 13, sliding piston; 14, adjusting screw; 15, connecting frame; 16, adjusting threaded sleeve; 17, vibration tube; 18, vibration chamber; 19, vibration rod; 20, vibration ball rod; 21, adjustment chamber; 22, spiral track; 23, lifting adjustment rod; 24, reciprocating threaded sleeve; 25, rotating frame ; 26. Stirring rod; 28. Filter mesh; 29. ​​Rotating scraper; 30. Transfer pipe; 31. Conical pipe; 32. Conical exhaust pipe; 33. Transfer bin; 34. Conical sliding plug; 36. Pressurized sliding plate; 37. Upper supply and pressure chamber; 38. Lower supply and pressure chamber; 39. Supply and pressure pipe; 40. Conical hole; 41. Reflux conical plug; 42. Cross runner; 43. Rotating bushing; 44. Sliding track; 45. Sliding gate frame; 46. Sliding screw; 47. Lifting frame; 48. Lifting bracket; 49. Lifting screw. DETAILED DESCRIPTION

[0029] The above and other technical contents, features and effects of the present invention are described in detail below with reference to the attached Figures 1 to 10 The detailed description of the embodiments will clearly show that the structural contents mentioned in the following embodiments are all based on the drawings in the specification.

[0030] Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

[0031] The present invention comprises an upper pressure chamber 1, a lower pressure chamber 2 and a lifting device, the lifting device is used to lift the upper pressure chamber 1, a crucible 3 is arranged inside the lower pressure chamber 2, an electric heating furnace 4 is arranged between the crucible 3 and the lower pressure chamber 2, the electric heating furnace 4 is used to heat the inside of the crucible 3, the metal is heated and melted, and the metal is in a liquid state inside the crucible 3, an intermediate partition 5 is connected between the upper pressure chamber 1 and the lower pressure chamber 2, the upper pressure chamber 1 and the lower pressure chamber 2 are divided by the intermediate partition 5, so that there is a pressure difference between the upper pressure chamber 1 and the lower pressure chamber 2, and then the metal liquid inside the crucible 3 enters the upper pressure chamber 1 above the crucible 3, the upper pressure chamber 1 is built with a sand box 6 located at the upper end of the intermediate partition 5, the sand box 6 is provided with a cavity 7, the casting of the metal is achieved by pouring molten metal into the cavity 7, a sand core is connected to the center position of the sand box 6, the sand core and the Four vertical cylinders 9 with equal circumferences are connected between the mold cavities 7. A slit runner 10 is connected between the vertical cylinder 9 and the sand core. The slit runner 10 is used to transport the molten metal. The molten metal enters the slit runner 10 through the vertical cylinder 9. The molten metal is added to the mold cavity 7 through the slit runner 10, so that the molten metal fills the mold cavity 7 and casts the metal. The molten metal enters the cross runner 42 through the liquid supply pipe 11, and then flows into the slit runner 10 through the cross runner 42 to enter the mold cavity 7. During the filling and solidification process, the vertical cylinder 9 actually plays the role of a shrinkage feeding riser. On the one hand, it shortens the distance of the shrinkage feeding channel and increases the shrinkage feeding effect of the casting to a certain extent. On the other hand, it avoids the occurrence of local overheating inside the casting and the occurrence of loose defects. Through the reasonable placement of the vertical cylinder 9, the slit runner 10 and the configuration of the cold iron, a stable temperature field is formed in the casting during solidification, and sequential solidification from top to bottom is achieved.

[0032] A liquid supply pipe 11 is arranged inside the crucible 3, the lower end of the liquid supply pipe 11 is arranged at the bottom of the crucible 3, the upper end of the liquid supply pipe 11 is connected to a horizontal runner 42 arranged at the lower part of the lower pressure chamber 2, the horizontal runner 42 is connected to the vertical tube 9, the molten metal enters the gap runner 10 through the liquid supply pipe 11, the horizontal runner 42 and the vertical tube 9, and then fills the cavity 7 with the molten metal to complete the casting.

[0033] The upper pressure chamber 1 and the lower pressure chamber 2 are both connected to a pressure regulating structure, and the pressure of the upper pressure chamber 1 and the lower pressure chamber 2 are regulated by the pressure regulating structure so that the pressure of the upper pressure chamber 1 is lower than the pressure value of the lower pressure chamber 2. Under the pressure difference between the upper pressure chamber 1 and the lower pressure chamber 2, the molten metal inside the lower pressure chamber 2 enters the cavity 7 from the inside of the crucible 3 through the liquid supply pipe 11, the horizontal runner 42, the vertical tube 9 and the gap runner 10 under high pressure for pouring.

[0034] The lifting device includes a sliding track 44 placed on the ground, and a sliding gate frame 45 is slidably connected to the sliding track 44. The lower end of the sliding gate frame 45 is threadedly connected to a sliding screw 46 rotatably connected to the inside of the sliding track 44. The sliding screw 46 is connected to a sliding motor connected to the sliding track. The sliding motor drives the sliding screw 46. The sliding screw 46 rotates to adjust the position of the sliding gate frame 45. Both sides of the sliding gate frame 45 are connected to lifting frames 47 for sliding up and down. The two lifting frames 47 are symmetrically distributed. A lifting bracket 48 is fixedly connected to the lifting frame 47. The upper pressure chamber 1 is supported by the lifting bracket 48, and the upper pressure chamber 1 is driven to rise and fall synchronously while the lifting bracket 48 slides.

[0035] The lifting bracket 48 is threadedly connected to the lifting screw 49 rotatably connected in the sliding track 44, and the two lifting screws 49 are connected by a sprocket transmission mechanism. One of the lifting screws 49 is connected to the driving motor connected to the sliding door frame 45, and the driving motor is used to drive the lifting screw 49. The lifting screw 49 rotates to drive the lifting bracket 48 to rise and fall, thereby realizing the lifting and lowering adjustment of the upper pressure chamber 1.

[0036] The pressure regulating structure comprises two hydraulic cylinders 12 connected symmetrically with gaps, wherein the hydraulic cylinders 12 are both slidably connected with sliding pistons 13, and an adjusting screw 14 is coaxially fixedly connected between the two sliding pistons 13, and the axis of the adjusting screw 14 is provided with a limit rail, and the hydraulic cylinder 12 is both fixedly connected with a limit rod matched with the limit rail, and under the cooperation of the limit rail and the limit rod, the adjusting screw 14 is slidably connected with the hydraulic cylinder 12, and a connecting frame 15 is connected between the two hydraulic cylinders 12, and an adjusting threaded sleeve 16 is rotatably connected to the connecting frame 15, and the adjusting threaded sleeve 16 is threadedly connected with the adjusting screw 14, and the hydraulic cylinder 12 is respectively connected with the upper pressure chamber 1 and the lower pressure chamber 2, and the sliding of the adjusting screw 14 drives the two sliding pistons 13 to slide synchronously, thereby realizing the adjustment of the pressure of the upper pressure chamber 1 and the lower pressure chamber 2, ensuring that the upper pressure chamber 1 and the lower pressure chamber 2 are in a pressure difference state, and ensuring that the metal liquid can smoothly fill the cavity 7.

[0037] In the specific implementation of this embodiment, the metal is first placed inside the crucible 3, and the metal material is melted by the electric heating furnace 4. After the melting is completed, the pressure inside the upper pressure chamber 1 and the lower pressure chamber 2 is adjusted by the pressure regulating structure, and then the casting pressure is guaranteed to be 0.6Mpa, and at the same time, the pressure difference range of the upper pressure chamber 1 and the lower pressure chamber 2 is guaranteed to be about 50KPa. Under the differential pressure state, since the casting solidifies under very high pressure, the shrinkage compensation capacity is 4 to 5 times that of ordinary gravity casting, and a dense structure can be obtained. At the same time, after the casting is completed, the pressure of the lower pressure chamber 2 decreases while the pressure of the upper pressure chamber 1 increases, which causes the excess molten metal in the upper pressure chamber 1 to flow back to the inside of the crucible 3, thereby realizing the recovery of the molten metal.

[0038] In the process of conveying, pouring and casting the molten metal, if the molten metal contains bubbles, it will cause unqualified quality, low density, and even defective products. Therefore, in order to precipitate the bubbles in the molten metal, the present embodiment provides a structure for degassing the molten metal. Specifically, a vibration tube 17 is coaxially fixedly connected to the inside of the liquid supply pipe 11, and a willow-shaped vibration chamber 18 is opened at the axis of the vibration tube 17. A vibration rod 19 coaxially arranged with the vibration tube 17 is rotatably connected to the inside of the vibration chamber 18, and a plurality of vibration ball rods 20 are fixedly connected to the vibration rod 19. During the rotation process of the vibration rod 19, the vibration tube 17 is knocked by the vibration ball rod 20 to achieve the vibration of the vibration tube 17. During the vibration process of the vibration rod 19, the molten metal inside the liquid supply pipe 11 is vibrated, thereby accelerating the discharge of bubbles in the molten metal inside the liquid supply pipe 11, so that the bubbles are discharged and converged to the top of the liquid supply pipe 11.

[0039] The lower end axis of the vibration rod 19 is provided with an adjustment chamber 21, and a spiral track 22 is provided inside the adjustment chamber 21. A lifting adjustment rod 23 is coaxially connected to the adjustment chamber 21 for sliding up and down. A limit pin that matches the spiral track 22 is fixedly connected to the lifting adjustment rod 23. The lifting adjustment rod 23 is coaxially threadedly connected with a reciprocating thread sleeve 24. The lifting adjustment rod 23 is driven to slide reciprocatingly up and down during the rotation of the reciprocating thread sleeve 24. During the sliding up and down process of the lifting adjustment rod 23, the lifting adjustment rod 23 is moved by the cooperation of the limit pin and the spiral track 22. The rod 23 rotates back and forth, and during the reciprocating rotation process of the lifting and adjusting rod 23, the vibration rod 19 is driven to rotate back and forth, thereby achieving the knocking of the vibration rod 19, causing the vibration rod 19 to vibrate, the reciprocating threaded sleeve 24 and the rotating shaft sleeve 43 rotatably connected to the bottom of the crucible 3 are coaxially fixedly connected, the rotating shaft sleeve 43 is connected to the driving device disposed inside the lower pressure chamber, and the driving of the rotating shaft sleeve 43 is achieved through the driving device, and the rotation of the rotating shaft sleeve 43 realizes the driving of the reciprocating threaded sleeve 24, thereby achieving the driving of the lifting and adjusting rod 23.

[0040] In order to ensure the effective melting of the metal material and improve the uniformity of heating, large bubble exhaust treatment is first carried out inside the crucible 3. Therefore, a rotating frame 25 is coaxially fixedly connected to the rotating sleeve, and a plurality of stirring rods 26 are fixedly connected to the rotating frame 25. During the rotation of the rotating sleeve 43, the rotating frame 25 is driven to rotate synchronously. The rotation of the rotating frame 25 drives the stirring rods 26 to rotate synchronously. The stirring rods 26 are rotatably connected to a plurality of stirring paddles distributed at equal intervals. During the rotation of the stirring rod 26, the molten metal inside the crucible 3 is stirred, and deep stirring is carried out by the stirring paddle. While the heating is uniform, the bubbles inside the molten metal are discharged through the upper surface of the molten metal in time, thereby improving the casting quality.

[0041] Since the metal material is mixed with impurities during the heating and melting process, these impurities are insoluble and will cause stains or even defective products when the metal solution enters the mold cavity 7 for casting. Therefore, in order to ensure the cleanliness of the metal solution entering the mold cavity 7, a filter mesh 28 is fixedly connected to the lower end of the liquid supply pipe 11. The filter mesh 28 is used to filter the metal solution entering the liquid supply pipe 11, and the impurities are isolated outside the liquid supply pipe 11, ensuring that the metal solution entering the mold cavity 7 is clean. In order to ensure the cleanliness of the internal molten metal, the outer wall of the vibration rod 19 is provided with a rotating scraper 29, and the rotating scraper 29 is fixedly connected to the rotating shaft sleeve 43. When the rotating shaft sleeve 43 rotates, the rotating scraper 29 is driven to rotate synchronously. The rotating scraper 29 is in contact with the filter mesh 28. Through the rotation of the rotating scraper 29, the filter mesh 28 is cleaned to avoid the long-term accumulation of impurities, which causes the blockage of the filter mesh 28 and the poor liquid supply of the liquid supply pipe 11.

[0042] In order to achieve the preliminary collection of bubbles discharged during the vibration process inside the liquid supply pipe 11, and at the same time enable the bubbles to continue to rise and be effectively separated from the molten metal, the upper end of the liquid supply pipe 11 is connected to a transfer pipe 30, and the inner diameter of the transfer pipe 30 is larger than the inner diameter of the liquid supply pipe 11. When the inner diameter becomes larger, the flow rate of the transfer pipe 30 will slow down, extending the residence time of the molten metal in the transfer pipe 30, making it easier for the bubbles to converge in the transfer pipe 30 and at the same time converge on the upper side of the transfer pipe 30. A tapered pipe 31 is connected between the transfer pipe 30 and the cross runner 42, and the tapered pipe 31 is used to accelerate the molten metal after it is output from the transfer pipe 30. The upper end of 30 is fixedly connected with a conical exhaust pipe 32, and the conical exhaust pipe 32 is used to collect the bubbles after convergence. The inner wall of the upper side of the transfer pipe 30 is provided with a transfer bin 33 located directly below the conical exhaust pipe 32. The lower end of the conical exhaust pipe 32 is fixedly connected with a one-way air valve placed inside the transfer bin 33. The one-way air valve can only allow the gas to pass through, and the liquid will be blocked outside the one-way air valve. The conical exhaust pipe 32 is connected to an external negative pressure device, so that the inside of the conical exhaust pipe 32 is in a negative pressure state. Under the negative pressure state, the gas will preferentially enter the inside of the conical exhaust pipe 32. At the same time, even if the molten metal rises to the transfer bin 33, it will be blocked by the one-way air valve.

[0043] In order to ensure that the gas does not directly enter the interior of the conical tube 31 from the transfer tube 30, a conical sliding plug 34 is coaxially slidably connected inside the conical tube 31. The conical sliding plug 34 and the conical tube 31 are connected via a spring. Under the action of the spring, the conical sliding plug 34 and the conical tube 31 fit together to form a seal for the conical tube 31. When the pressure inside the transfer tube 30 is greater than the elastic force of the spring, the conical sliding plug 34 slides, and the molten metal in the transfer tube 30 enters the conical tube 31 and then flows into the riser, thereby ensuring the residence time of the molten metal in the transfer tube 30.

[0044] The driving device includes a heat insulation plate placed at the lower end of the electric heating furnace 4, and the heat insulation plate is used to isolate the driving device from the crucible 3 and the electric heating furnace 4 to ensure the working environment of the driving device. The outer edge of the heat insulation plate is in contact with the inner wall of the lower pressure chamber 2, and the heat insulation plate and the bottom surface of the lower pressure chamber 2 are gap-matched. The lower end of the heat insulation plate is fixedly connected with a driving motor, and the driving motor and the rotating shaft sleeve 43 are connected through a transmission mechanism, and the driving of the rotating shaft sleeve 43 is achieved by the rotation of the driving motor.

[0045] A pressurized sliding plate 36 is placed inside the crucible 3 and is connected to the liquid supply pipe 11 for sliding up and down movement. The outer wall of the pressurized sliding plate 36 fits the inner wall of the crucible 3. During the process of pressurizing the lower pressure chamber 2, the pressurized sliding plate 36 slides inside the crucible 3 during the pressurization process. Furthermore, during the sliding process of the pressurized sliding plate 36, the molten metal is continuously transported into the liquid supply pipe 11, thereby ensuring the stability of the molten metal transportation.

[0046] An upper pressure supply chamber 37 and a lower pressure supply chamber 38 are provided inside the middle partition 5. The upper pressure supply chamber 37 is located above the lower pressure supply chamber 38. The upper pressure supply chamber 37 and the lower pressure supply chamber 38 are respectively connected to the upper pressure chamber 1 and the lower pressure chamber 2. The upper pressure supply chamber 37 and the lower pressure supply chamber 38 are both connected to a pressure supply pipe 39. The pressure supply pipe 39 is respectively connected to the hydraulic cylinder 12 through a conduit. The sliding of the sliding piston 13 in the hydraulic cylinder 12 realizes the change of the pressure in the upper pressure chamber 37 and the lower pressure chamber 38, thereby realizing the change of the pressure in the upper pressure chamber 1 and the lower pressure chamber 2.

[0047] In order to ensure that the excess molten metal can effectively reflux after the casting is completed, a conical hole 40 is opened on the conical sliding plug 34, and a reflux conical plug 41 is slidably connected in the conical hole 40. The reflux conical plug 41 and the conical sliding plug 34 are connected by a spring. When the pressure in the lower pressure chamber 2 decreases and the pressure in the upper pressure chamber 1 increases, the molten metal refluxes. At the same time, under the pressure difference state, the reflux conical plug 41 slides to open the conical hole 40, which helps the reflux of the molten metal.

[0048] When the present invention is used in practice, firstly, a metal material is placed inside the crucible 3, and the metal material is melted by the electric heating furnace 4. After the melting is completed, the pressure inside the upper pressure chamber 1 and the lower pressure chamber 2 is adjusted by the pressure regulating structure, and then the casting pressure is ensured to be 0.6Mpa, and at the same time, the pressure difference range between the upper pressure chamber 1 and the lower pressure chamber 2 is ensured to be about 50KPa. Under the differential pressure state, the molten metal enters the transfer pipe 30 through the liquid supply pipe 11, and at the same time, the vibration tube 17 vibrates to vibrate the molten metal entering the liquid supply pipe 11, which is helpful for the convergence and discharge of bubbles. The molten metal inside the transfer pipe 30 flows through the conical pipe 31, the horizontal runner 42, and the vertical pipe, and then the molten metal is poured into the mold cavity 7 through the gap runner 10, and the pressure is maintained at the same time. After casting, the pressure regulating structure is reversed, so that the pressure of the upper pressure chamber 1 gradually increases, and the pressure of the lower pressure chamber 2 gradually decreases, and the molten metal flows back to the inside of the crucible 3 for the next use.

[0049] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A low pressure casting device, characterized in that: It comprises an upper pressure chamber (1), a lower pressure chamber (2), and a lifting device, wherein the upper pressure chamber (1) and the lower pressure chamber (2) are both connected to a pressure regulating structure, a crucible (3) is arranged inside the lower pressure chamber (2), and an electric heating furnace (4) is arranged between the crucible (3) and the lower pressure chamber (2); A middle partition (5) is connected between the upper pressure chamber (1) and the lower pressure chamber (2); a sand box (6) is built into the upper pressure chamber (1) and is located at the upper end of the middle partition (5); a mold cavity (7) is disposed inside the sand box (6); a sand core is connected to the center of the sand box (6); four vertical cylinders (9) with equal circumferences are connected between the sand core and the mold cavity (7); and a gap runner (10) is connected between the vertical cylinder (9) and the sand core; A liquid supply pipe (11) is arranged inside the crucible (3), the lower end of the liquid supply pipe (11) is arranged at the bottom of the crucible (3) and is connected to a horizontal runner (42) arranged at the lower part of the lower pressure chamber (2), and the horizontal runner (42) is connected to the vertical cylinder (9); The lifting device comprises a sliding track (44) placed on the ground, a sliding door frame (45) is slidably connected to the sliding track (44), the lower end of the sliding door frame (45) is threadedly connected to a sliding screw rod (46) rotatably connected to the inside of the sliding track (44), both sides of the sliding door frame (45) are slidably connected to a lifting frame (47), and a lifting bracket (48) is fixedly connected to the lifting frame (47); The lifting bracket (48) is threadedly connected to a lifting screw (49) rotatably connected to the sliding track (44), and the two lifting screws (49) are connected via a sprocket transmission mechanism, and one of the lifting screws (49) is externally connected to a driving source.

2. A low pressure casting device according to claim 1, characterized in that: The pressure regulating structure comprises two hydraulic cylinders (12) connected symmetrically with a gap, each of the hydraulic cylinders (12) being slidably connected with a sliding piston (13), an adjusting screw (14) being coaxially fixedly connected between the two sliding pistons (13), a connecting frame (15) being connected between the two hydraulic cylinders (12), an adjusting threaded sleeve (16) being rotatably connected to the connecting frame (15), the adjusting threaded sleeve (16) being threadedly connected to the adjusting screw (14), and the hydraulic cylinder (12) being respectively connected to the upper pressure chamber (1) and the lower pressure chamber (2).

3. A low pressure casting device according to claim 2, characterized in that: A vibration tube (17) is coaxially fixedly connected to the interior of the liquid supply tube (11); a willow-leaf-shaped vibration chamber (18) is provided at the axis of the vibration tube (17); a vibration rod (19) coaxially arranged with the vibration tube (17) is rotatably connected to the interior of the vibration chamber (18); a plurality of vibration ball rods (20) are fixedly connected to the vibration rod (19); during the rotation of the vibration rod (19), the vibration tube (17) is struck by the vibration ball rods (20), thereby achieving vibration of the vibration tube (17); The lower end axis of the vibration rod (19) is provided with an adjustment chamber (21), and a spiral track (22) is also provided inside the adjustment chamber (21). A lifting adjustment rod (23) is coaxially connected to the adjustment chamber (21) for vertical sliding movement, and a limit pin that matches the spiral track (22) is fixedly connected to the lifting adjustment rod (23). The lifting adjustment rod (23) is coaxially threadedly connected to a reciprocating threaded sleeve (24), and the reciprocating threaded sleeve (24) is coaxially and fixedly connected to a rotating shaft sleeve (43) rotatably connected to the bottom of the crucible (3), and the rotating shaft sleeve (43) is connected to a driving device disposed inside the lower pressure chamber (2).

4. A low pressure casting device according to claim 3, characterized in that: The rotating shaft sleeve (43) is coaxially fixedly connected to a rotating frame (25), a plurality of stirring rods (26) are fixedly connected to the rotating frame (25), and a plurality of stirring paddles distributed at equal intervals are rotatably connected to the stirring rods (26).

5. A low pressure casting device according to claim 4, characterized in that: The lower end of the liquid supply pipe (11) is fixedly connected with a filter mesh (28), the outer wall of the vibration rod (19) is sleeved with a rotating scraper (29), and the rotating scraper (29) is in contact with the filter mesh (28); The upper end of the liquid supply pipe (11) is connected to a transfer pipe (30), the inner diameter of the transfer pipe (30) is larger than the inner diameter of the liquid supply pipe (11), a conical pipe (31) is connected between the transfer pipe (30) and the cross runner (42), the upper end of the transfer pipe (30) is fixedly connected to a conical exhaust pipe (32), the inner wall of the upper side of the transfer pipe (30) is provided with a transfer bin (33) located directly below the conical exhaust pipe (32), the lower end of the conical exhaust pipe (32) is fixedly connected to a one-way vent valve disposed inside the transfer bin (33), the conical exhaust pipe (32) is connected to an external negative pressure device, so that the inside of the conical exhaust pipe (32) is in a negative pressure state; A conical sliding plug (34) is coaxially slidably connected inside the conical tube (31); the conical sliding plug (34) and the conical tube (31) are connected via a spring; under the action of the spring, the conical sliding plug (34) and the conical tube (31) fit together to form a seal for the conical tube (31).

6. A low pressure casting device according to claim 5, characterized in that: The driving device comprises a heat insulation plate disposed at the lower end of the electric heating furnace (4), the outer edge of the heat insulation plate being in contact with the inner wall of the lower pressure chamber (2), the heat insulation plate and the bottom surface of the lower pressure chamber (2) being in clearance fit, the lower end of the heat insulation plate being fixedly connected with a driving motor, and the driving motor and the rotating shaft sleeve (43) being connected via a transmission mechanism.

7. A low pressure casting device according to claim 6, characterized in that: A pressurizing sliding plate (36) is disposed inside the crucible (3) and is slidably connected to the liquid supply pipe (11) up and down. The outer wall surface of the pressurizing sliding plate (36) is in contact with the inner wall surface of the crucible (3).

8. A low pressure casting device according to claim 7, characterized in that: An upper pressure supply chamber (37) and a lower pressure supply chamber (38) are provided inside the middle partition (5); the upper pressure supply chamber (37) is located above the lower pressure supply chamber (38); the upper pressure supply chamber (37) and the lower pressure supply chamber (38) are respectively connected to the upper pressure chamber (1) and the lower pressure chamber (2); the upper pressure supply chamber (37) and the lower pressure supply chamber (38) are both connected to a pressure supply pipe (39); and the pressure supply pipe (39) is respectively connected to the hydraulic cylinder (12) through a conduit.

9. A low pressure casting device according to claim 8, characterized in that: The conical sliding plug (34) is provided with a conical hole (40), a reflux conical plug (41) is slidably connected in the conical hole (40), and the reflux conical plug (41) and the conical sliding plug (34) are connected via a spring.

10. A metal low-pressure casting method, characterized in that: Using the low pressure casting equipment according to claim 9 comprises the following steps, specifically: Step 1: firstly, placing a metal substance inside the crucible (3), and melting the metal substance by the electric heating furnace (4); Step 2: After the melting is completed, the pressure inside the upper pressure chamber (1) and the lower pressure chamber (2) is adjusted by the pressure regulating structure, and then the casting pressure is ensured to be 0.6Mpa, and at the same time, the pressure difference between the upper pressure chamber (1) and the lower pressure chamber (2) is ensured to be about 50KPa; Step three: under the differential pressure state, the molten metal enters the transfer pipe (30) through the liquid supply pipe (11), and at the same time, the vibration pipe (17) vibrates to vibrate the molten metal entering the liquid supply pipe (11) to perform exhaust treatment; Step 4: The molten metal flows toward the tapered tube (31), the horizontal runner (42), and the vertical tube, and then pours the molten metal into the mold cavity (7) through the slit runner (10); Step 5: After the liquid injection is completed, the upper pressure chamber (1) is subjected to pressure maintenance treatment; Step 6: After casting, the pressure regulating structure is reversed, so that the pressure in the upper pressure chamber (1) gradually increases, while the pressure in the lower pressure chamber (2) gradually decreases, and the molten metal flows back into the crucible (3) for next use.

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