Gating System and Casting Method for ZL205A Aluminum Alloy Hanger-Type Structural Parts

Abstract

The present invention discloses a gating system and a gating method for a ZL205A aluminum alloy hanger-like structural part. The first gating component and the second gating component of the gating system are arranged in parallel. The first gating component and the second gating component have the same structure and the corresponding structures are symmetrically arranged. Both the first gating component and the second gating component are connected to the casting cavity. Each of the two gating components includes a pouring basin, three sprue runners, three cross runners, and a plurality of slot runners. The tops of the three sprue runners are all connected to the pouring basin, and the bottoms are respectively connected to the three cross runners. The plurality of slot runners are vertically arranged on the three cross runners. The gating method includes steps of molding, closing the mold, and pouring. Before pouring, use a plug rod to block the through hole at the bottom of the pouring basin, pour in the aluminum alloy liquid. After the height of the aluminum alloy liquid reaches two-thirds of the height of the pouring basin, pull out the plug rod, and the aluminum alloy liquid fills the mold. The present invention solves the problems of undercasting, porosity, inclusion, and segregation of large and complex structural parts.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloy casting forming, and particularly relates to a gating system for a ZL205A aluminum alloy hanger-type structural part and a pouring method thereof. Background Art

[0002] ZL205A aluminum alloy is a high-strength and tough cast aluminum alloy independently developed by Beijing Institute of Aeronautical Materials. At present, it has realized structural weight reduction in the form of "replacing steel with aluminum" in multiple key model parts in the military fields such as aviation, aerospace, and ordnance. Due to the characteristics of the alloy chemical composition, the crystallization temperature range of ZL205A aluminum alloy is relatively wide, usually in the temperature range of 90 - 110°C, and it is in paste solidification. During the paste solidification process, defects such as shrinkage cavities and porosity are likely to occur, and the segregation and hot cracking tendencies are higher than those of cast aluminum-silicon alloys. Therefore, the application of ZL205A aluminum alloy in the field of casting and forming large and complex hanger-type structural parts has been restricted for a long time.

[0003] In the master's thesis "Simulation and Process Optimization of the Metal Mold Casting Process for Large ZL205A Parts" (Author: Yunpeng Dang, Northwestern Polytechnical University, 2022), the author pointed out that when the outer dimensions of the casting are relatively large, an excessive pouring height will cause unstable filling, and at the same time, the thermal balance factors during the solidification process are highlighted, and the disadvantages of the casting performance of ZL205A aluminum alloy are amplified, resulting in various defects in the casting and a significant reduction in the finished product rate. The technical solution of this thesis uses metal mold casting instead of sand mold casting, and adds a side-pouring - stepped gating system on the basis of the bottom-pouring gating system, and cast a large cabin structural part with a diameter of 331 mm, a length of 800 mm, and a thickness of 65 mm. The outline of the casting is clear and the structure is dense. However, the technical solution of this thesis uses a metal mold, which has a high cost and is only suitable for casting cylindrical / cylindrical castings with relatively small dimensions, relatively simple structures, and axisymmetric structures. Moreover, the gating system for casting complex structural parts with dimensions greater than 2.5 m is not involved in the thesis.

[0004] The invention patent with the publication number of CN106925722A discloses a gating system for producing extra-long and ultra-thin aluminum alloy castings, which includes a pouring basin, a runner, ingates and a cavity connected in sequence. The pouring basin is arranged at the central position in the length direction of the runner. There are multiple ingates arranged along the length direction of the runner, and the distance between two adjacent ingates is between 450 - 500 mm. The ingates are symmetrically arranged with respect to the pouring basin. The caliber of each ingate increases from the center of the length direction of the runner to both ends, and the arrangement density of the ingates increases from the center of the runner to both ends. The cross-sectional area of the runner increases from the center of the length direction to both ends. This technical solution can reduce the problems of underpouring, cold shut and incomplete pouring caused by heat loss during the pouring of extra-long and ultra-thin parts. It has successfully poured aluminum alloy castings with a length of 6 m and a thickness of 8 mm. However, this technical solution does not involve solutions to defects such as porosity and segregation of ZL205A aluminum alloy, nor does it involve the gating system for large and complex ZL205A aluminum alloy hanger-like structural parts.

[0005] The utility model patent with the authorization publication number of CN204052857U discloses a vertical gap gating system for an aircraft cabin body, which includes a cabin body part, a vertical seam, a vertical cylinder, a bottom plate part and a support column. The cabin body part is cylindrical. The vertical cylinders are evenly distributed around the outer side of the cabin body part. The vertical cylinders and the cabin body part are connected through vertical seams with the same length as the cabin body part. The lower end of the vertical cylinder is longer than the cabin body part. The bottom plate part is in the shape of a square rod, concentric with the cabin body part and distributed in the same way as the vertical cylinders, and is connected to the bottom of the vertical cylinder and covers the bottom end of the vertical cylinder. The support column is vertically arranged at the center of the bottom plate part and fixes the bottom plate part from the bottom of the bottom plate part. This technical solution is only applicable to pouring castings with relatively small sizes, relatively simple structures and axially symmetric structures such as cylindrical / cylindrical castings, and is not applicable to pouring complex structural parts with sizes larger than 2.5 m. Moreover, this technical solution does not involve solutions to defects such as porosity and segregation of ZL205A aluminum alloy.

[0006] In summary, the existing gating systems are only for pouring medium or small-sized cabin section castings of ZL205A aluminum alloy, and the gating systems are relatively single. Therefore, developing a gating system for large and complex ZL205A aluminum alloy structural parts is of great significance for expanding its application fields. Summary of the Invention

[0007] To solve the problems existing in the prior art, the present invention provides a gating system for ZL205A aluminum alloy hanger-like structural parts, which includes a first gating component and a second gating component. The first gating component and the second gating component are arranged in parallel. The first gating component and the second gating component have the same structure and the corresponding structures are symmetrically arranged. Both the first gating component and the second gating component are connected to the casting cavity.

[0008] Preferably, both the first pouring assembly and the second pouring assembly include a sprue box, three downsprue runners, three cross-risers, and a plurality of slot runners; the tops of the three downsprue runners are all connected to the sprue box, the bottoms of the three downsprue runners are respectively connected to one ends of the three cross-risers, and the plurality of slot runners are vertically arranged on the three cross-risers.

[0009] In any of the above solutions, preferably, ingates are arranged on the sides of two of the three cross-risers, the ingates are connected to the casting cavity, and slag traps are respectively arranged at the other ends of the three cross-risers; the sides of the plurality of slot runners are all connected to risers, and the bottoms of the risers are connected to the casting cavity.

[0010] In any of the above solutions, preferably, the sprue box is a cuboid structure with an open top and a through hole at the bottom; the length of the inner cavity of the sprue box is 400 - 600 mm, the width is 200 - 350 mm, the height is 300 - 400 mm, and the wall thickness of the sprue box is 4 - 6 mm; a circular through hole is opened at a position near the wide side at the bottom of the sprue box, and the diameter of the through hole is 40 - 50 mm; the sprue box is made of stainless steel material.

[0011] In the present invention, the vertical sections of the three downsprue runners of each pouring assembly are concentrated together, and the tops of the three downsprue runners are all connected to the through hole at the bottom of the sprue box. When necessary, seal the connection position between the tops of the three downsprue runners and the through hole to prevent the leakage of molten metal.

[0012] In any of the above solutions, preferably, the downsprue runner is an L-shaped square tube structure, and its vertical section and horizontal section are smoothly transitioned; the cross-section of the downsprue runner is rectangular, the length of its inner cavity is 25 - 35 mm, the width is 10 - 15 mm, and the wall thickness of the downsprue runner is 5 - 8 mm; the height of the vertical section is 500 - 700 mm, and the length of the horizontal section is 100 - 150 mm; the downsprue runner is made of ceramic material.

[0013] In the present invention, the structure with a smooth transition between the vertical section and the horizontal section of the downsprue runner can effectively avoid the formation of inclusion defects caused by the erosion or impact of high-temperature molten metal on the sand mold. Due to the large size, heavy weight, and long pouring time of the casting, the traditional sand mold runner is prone to collapse under the long-term erosion of high-temperature molten metal, and sand grains are carried into the casting by the molten metal to form inclusion defects. In addition, the pouring position of large castings is relatively high, and the high-temperature molten metal free-falls through the downsprue runner, generating a huge impact on the cross-riser, which is likely to cause the collapse of the sand mold, and sand grains are carried into the casting by the molten metal to form inclusion defects.

[0014] Preferably, in any of the above solutions, the cross-section of the runner is rectangular, with a length of 60 - 80 mm and a width of 40 - 60 mm.

[0015] Preferably, in any of the above solutions, the upper surface of the slag trap is provided with a serrated structure. In one serrated shape, the serrated edge close to the gating box is perpendicular to the upper surface of the slag trap, and the serrated edge far from the gating box is inclined to the upper surface of the slag trap. The included angle between the perpendicular serrated edge and the inclined serrated edge is 30 - 60°, and the height of the serrated structure is 30 - 40 mm; the length of the slag trap is 100 - 200 mm, the width is the same as that of the runner, and the total length of the runner and the slag trap is 1300 - 1400 mm.

[0016] In the present invention, at the beginning of pouring, the flow velocity of the metal liquid front is relatively large, and defects such as entrained air holes and inclusions are likely to be formed. A slag trap with a serrated structure is arranged at one end of the runner far from the gating box. The impure metal liquid at the front of the metal liquid can be effectively intercepted and collected by the serrated structure, preventing the impure metal liquid from flowing into the casting cavity, thereby improving the metallurgical quality of the casting. In the traditional casting process, a sprue well is usually arranged below the sprue, and slag collection and flow buffering are only carried out through the sprue well, which cannot effectively prevent the impure metal liquid from flowing into the casting cavity and generating defects.

[0017] Preferably, in any of the above solutions, the slot gate includes a vertical cylinder and a slot. The bottom of the vertical cylinder is connected to the runner, and the side of the vertical cylinder is connected to the riser and the casting cavity through the slot; the diameter of the vertical cylinder is 60 - 75 mm and the height is 500 - 700 mm; the cross-section of the slot is an isosceles trapezoid. The side of the isosceles trapezoid close to the vertical cylinder is the long side, and the side close to the riser is the short side. The perpendicular distance between the long side and the short side is the height of the isosceles trapezoid; the length of the long side of the isosceles trapezoid is 1.5 - 2 times the length of the short side, the length of the short side of the isosceles trapezoid is 1 - 1.5 times the wall thickness of the casting, and the height of the isosceles trapezoid is 50 - 60 mm; the distance between the centerlines of two adjacent slots connected to the same riser is 200 - 250 mm.

[0018] Preferably, in any of the above solutions, the top and bottom surfaces of the riser are both rectangular. The length of the top surface is 250 - 350 mm and the width is 80 - 100 mm. The length of the bottom surface is 200 - 300 mm and the width is 1 - 1.5 times the wall thickness of the casting. The height of the riser is 200 - 400 mm; the cross-section of the ingate is rectangular, with a length of 50 - 70 mm and a width of 15 - 20 mm.

[0019] Traditionally, during the process of filling the molten metal from bottom to top, as the flow length of the molten metal increases, the temperature loss increases. Finally, the molten metal in the filling riser often has a relatively low temperature. Especially in large and complex structural parts, the feeding effect of the riser becomes even worse. In the present invention, a flow-blocking structure is designed at the bottom of the slit gate. The flow-blocking structure is a notch formed at the position near the bottom of the cylinder where the side connecting the slit and the cylinder is located. The flow-blocking structure is used in conjunction with the inner gate. At the beginning of filling, the molten metal fills the bottom of the casting cavity through the inner gate. When the molten metal fills up to the height of the flow-blocking structure, since the sizes of the cylinder and the slit are larger than those of the inner gate and the flow resistance is smaller, the molten metal is more likely to fill the casting cavity through the cylinder and the slit, which can avoid overheating near the inner gate and reduce the tendency of porosity. In the later stage of filling, the flow-blocking structure can prevent the molten metal entering the cylinder from flowing laterally, which is beneficial for the high-temperature molten metal to flow along the cylinder towards the riser, promoting the feeding effect of the riser and improving the density and metallurgical quality of the casting.

[0020] The present invention also provides a pouring method for a ZL205A aluminum alloy hanger-like structural part, using the pouring system for the ZL205A aluminum alloy hanger-like structural part described in any one of the above, including the following steps:

[0021] Step 1: Molding. Coat the surface of the mold with a release agent, air dry it and then assemble the mold. Then use a sand mixer to mix sand for molding.

[0022] Step 2: Closing the mold. Stack and assemble the runner sand box, casting sand box and riser sand box from bottom to top in sequence. Then install the gate box at the top of the sprue, aligning the through hole at the bottom of the gate box with the sprue.

[0023] Step 3: Pouring. Use a plug rod to block the through hole at the bottom of the gate box, pour aluminum alloy liquid into the gate box. After the liquid level height of the aluminum alloy liquid reaches two-thirds of the height of the gate box, pull out the plug rod and the aluminum alloy liquid starts to fill. Continuously pour aluminum alloy liquid into the gate box and keep the liquid level height of the aluminum alloy liquid at two-thirds of the height of the gate box during the pouring process. After the aluminum alloy liquid fills the casting cavity, use a plug rod to block the through hole at the bottom of the gate box and the pouring ends.

[0024] In Step 1, the particle size of the original sand used for molding is 70 - 140 mesh, and scrubbed sand can be selected; the resin used for molding can be PEPSET resin.

[0025] In Step 2, the runner sand box is the bottom box, the casting sand box is the middle box, and the riser sand box is the upper box; before installing the gate box, it is necessary to coat a layer of heat-resistant coating on the inner wall of the gate box to prevent the aluminum alloy liquid from corroding the gate box, and it is also necessary to preheat the gate box to make the preheating temperature of the gate box reach 400 - 450 °C.

[0026] In Step 3, the pouring temperature of the aluminum alloy liquid is 720 - 740 °C.

[0027] Through a large number of experiments, it is proved that when the preheating temperature of the gating box is lower than 400 °C, the temperature of the molten metal in the gating box will be significantly reduced, resulting in a decrease in the actual pouring temperature, which is not conducive to the filling and feeding of the molten metal and is prone to defects such as underpouring and porosity; when the preheating temperature of the gating box is higher than 450 °C, it will rapidly cool down to below 450 °C in the air, causing energy waste and cost increase. In addition, when the liquid level height of the molten metal is lower than 2 / 3 of the height of the gating box, it is necessary to increase the flow rate of the liquid flowing into the gating box. Otherwise, the liquid level height of the molten metal in the gating box will gradually decrease, resulting in a decrease in the filling head and a reduction in the filling speed; when the liquid level height of the molten metal is higher than 2 / 3 of the height of the gating box, splashing is likely to occur, posing a safety hazard. In the present invention, parameters such as the size of the gating box, the preheating temperature of the gating box, and the liquid level height of the molten metal in the gating box need to work together to ensure that the molten metal fills the mold with a stable speed and a constant temperature.

[0028] The present invention is applicable to pouring large and complex hanger - type structural parts. "Large" means the length is not less than 2.5 m and the weight is not less than 500 kg; "complex" means the structure is complex, the wall thickness difference is large, and there is an airfoil structure that meets the aerodynamic design; "hanger - type structural parts" means structural parts composed of multiple load - bearing beams, and the load - bearing beams are connected by airfoil structures, usually externally placed on an aircraft for hanging or carrying items.

[0029] The pouring system and pouring method of the ZL205A aluminum alloy hanger - type structural parts of the present invention achieve the stable filling from bottom to top and the regional sequential solidification of large and complex ZL205A aluminum alloy hanger - type structural parts, solving problems such as undercasting, porosity, inclusion, segregation, and low cutting performance of large and complex structural parts; at the same time, it realizes the constant - temperature and constant - speed pouring and filling of ZL205A aluminum alloy liquid. Through the optimization of the slit runner, the feeding effect of the riser is improved, effectively eliminating porosity, segregation, and hot - cracking defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of a preferred embodiment of the pouring system of the ZL205A aluminum alloy hanger - type structural parts according to the present invention;

[0031] Figure 2 For Figure 1 The structural schematic diagram of the first pouring component in the shown embodiment;

[0032] Figure 3 For Figure 1 The top - view of the pouring system in the shown embodiment;

[0033] Figure 4 For Figure 1The bottom view of the gating system in the illustrated embodiment;

[0034] Figure 5 is Figure 1 The structural schematic diagram of the slit runner and the riser in the illustrated embodiment;

[0035] Figure 6 is Figure 1 The schematic diagram of the ZL205A aluminum alloy hanger - type structural part being cast in the illustrated embodiment;

[0036] Figure 7 is Figure 1 The metallographic photo of the specified area on the casting in the illustrated embodiment.

[0037] Description of the markings in the figure:

[0038] 1 - The first gating assembly, 101 - Sprue box, 102 - Sprue, 103 - Runner, 104 - Slit runner, 105 - Ingate, 106 - Skim bob, 107 - Riser, 108 - Through - hole, 109 - Standpipe, 110 - Slit;

[0039] 2 - The second gating assembly;

[0040] 3 - Specified area. Detailed implementation mode

[0041] In order to further understand the content of the present invention, the present invention will be elaborated in detail below in combination with specific embodiments.

[0042] Embodiment 1:

[0043] As Figure 1-5 shown, according to a preferred embodiment of the gating system of the ZL205A aluminum alloy hanger - type structural part of the present invention, it includes a first gating assembly 1 and a second gating assembly 2. The first gating assembly 1 and the second gating assembly 2 are arranged in parallel. The structures of the first gating assembly 1 and the second gating assembly 2 are the same and the corresponding structures are symmetrically arranged. Both the first gating assembly 1 and the second gating assembly 2 are connected to the casting cavity.

[0044] The structures of the two pouring components are the same, and only the structure of the first pouring component will be described herein. The first pouring component 1 includes a sprue box 101, three downsprue channels 102, three cross-sprue channels 103, and a plurality of slit gates 104; the tops of the three downsprue channels 102 are all connected to the sprue box 101, the bottoms of the three downsprue channels 102 are respectively connected to one ends of the three cross-sprue channels 103, and the plurality of slit gates 104 are vertically arranged on the three cross-sprue channels 103. Inner gates 105 are arranged on the sides of two of the three cross-sprue channels 103, the inner gates 105 are connected to the casting cavity, and slag traps 106 are respectively arranged at the other ends of the three cross-sprue channels 103; the sides of the plurality of slit gates 104 are all connected to risers 107, and the bottoms of the risers 107 are connected to the casting cavity.

[0045] The sprue box 101 has a cuboid structure with an open top and a through hole 108 opened at the bottom; the length of the inner cavity of the sprue box 101 is 500 mm, the width is 280 mm, the height is 350 mm, and the wall thickness of the sprue box 101 is 5 mm; a circular through hole 108 is opened at a position near the wide side at the bottom of the sprue box 101, and the diameter of the through hole 108 is 45 mm; the sprue box 101 is made of stainless steel material. In this embodiment, the vertical sections of the three downsprue channels of each pouring component are concentrated together, and the tops of the three downsprue channels are all connected to the through hole at the bottom of the sprue box. When necessary, sealing is performed at the connection position between the tops of the three downsprue channels and the through hole to prevent the metal liquid from leaking out.

[0046] The downsprue channel 102 has an L-shaped square tube structure, and its vertical section and horizontal section are smoothly transitioned; the cross-section of the downsprue channel 102 is rectangular, the length of its inner cavity is 30 mm, the width is 12 mm, and the wall thickness of the downsprue channel 102 is 6 mm; the height of the vertical section is 600 mm, and the length of the horizontal section is 125 mm; the downsprue channel 102 is made of ceramic material. In this embodiment, the structure with a smooth transition between the vertical section and the horizontal section of the downsprue channel can effectively avoid the inclusion defects caused by the high-temperature metal liquid scouring or impacting the sand mold.

[0047] The cross-section of the runner 103 is rectangular, with a length of 70 mm and a width of 50 mm. The upper surface of the slag trap 106 is provided with a sawtooth structure. In one sawtooth shape, the sawtooth edge close to the pouring box 101 is perpendicular to the upper surface of the slag trap 106, and the sawtooth edge far from the pouring box 101 is inclined to the upper surface of the slag trap 106. The included angle between the perpendicular sawtooth edge and the inclined sawtooth edge is 45°. The height of the sawtooth structure is 35 mm. The length of the slag trap 106 is 150 mm, and the width is the same as that of the runner 103. The total length of the runner 103 and the slag trap 106 is 1350 mm. In this embodiment, at the beginning of pouring, the flow velocity of the front of the molten metal is relatively large, and it is easy to form defects such as entrained air holes and inclusions. A slag trap with a sawtooth structure is arranged at the end of the runner far from the pouring box. The impure molten metal at the front of the molten metal can be effectively intercepted and collected by the sawtooth structure, preventing the impure molten metal from flowing into the casting cavity, thereby improving the metallurgical quality of the casting.

[0048] The slot runner 104 includes a vertical cylinder 109 and a slot 110. The bottom of the vertical cylinder 109 is connected to the runner 103, and the side surface of the vertical cylinder 109 is connected to the riser 107 and the casting cavity through the slot 110. The diameter of the vertical cylinder 109 is 68 mm and the height is 600 mm. The cross-section of the slot 110 is an isosceles trapezoid. The side close to the vertical cylinder 109 is the long side, and the side close to the riser 107 is the short side. The vertical distance between the long side and the short side is the height of the isosceles trapezoid. The length of the long side of the isosceles trapezoid is 1.7 times the length of the short side. The length of the short side of the isosceles trapezoid is 1.2 times the wall thickness of the casting. The height of the isosceles trapezoid is 55 mm. The distance between the centerlines of two adjacent slots connected to the same riser is 225 mm.

[0049] The top and bottom surfaces of the riser are both rectangular. The length of the top surface is 300 mm and the width is 90 mm. The length of the bottom surface is 250 mm and the width is 1.2 times the wall thickness of the casting. The height of the riser is 300 mm. The cross-section of the ingate is rectangular, with a length of 60 mm and a width of 18 mm.

[0050] In this embodiment, a flow-blocking structure is designed at the bottom of the slit gate. The flow-blocking structure is a notch formed at the position near the bottom of the vertical cylinder on the side where the slit is connected to the vertical cylinder. The flow-blocking structure is used in conjunction with the inner gate. At the beginning of filling, the molten metal fills the bottom of the casting cavity through the inner gate. When the molten metal fills to the height of the flow-blocking structure, since the sizes of the vertical cylinder and the slit are larger than those of the inner gate and the flow resistance is smaller, the molten metal is more likely to fill the casting cavity through the vertical cylinder and the slit, which can avoid overheating near the inner gate and reduce the tendency of porosity. In the later stage of filling, the flow-blocking structure can prevent the molten metal entering the vertical cylinder from flowing laterally, which is beneficial for the high-temperature molten metal to flow along the vertical cylinder towards the riser, promoting the feeding effect of the riser and improving the density and metallurgical quality of the casting.

[0051] The present invention also provides a pouring method for a ZL205A aluminum alloy hanger-type structural part, using the above-mentioned pouring system for the ZL205A aluminum alloy hanger-type structural part, including the following steps:

[0052] Step 1: Molding. Coat a layer of mold release agent on the surface of the mold, dry it and then assemble the mold. Then use a sand mixer to mix sand for molding.

[0053] Step 2: Closing the mold. Stack and assemble the runner sand box, casting sand box and riser sand box from bottom to top in sequence. Then install the gate box at the top of the sprue, aligning the through hole at the bottom of the gate box with the sprue.

[0054] Step 3: Pouring. Use a plug rod to block the through hole at the bottom of the gate box, pour aluminum alloy liquid into the gate box. After the liquid level height of the aluminum alloy liquid reaches two-thirds of the height of the gate box, pull out the plug rod, and the aluminum alloy liquid starts to fill. Continuously pour aluminum alloy liquid into the gate box, and during the pouring process, keep the liquid level height of the aluminum alloy liquid at two-thirds of the height of the gate box. After the aluminum alloy liquid fills the casting cavity, use a plug rod to block the through hole at the bottom of the gate box, and the pouring ends.

[0055] In Step 1, the particle size of the original sand used for molding is 70 - 140 mesh, and scrubbed sand is selected. The resin used for molding is PEPSET resin.

[0056] In Step 2, the runner sand box is the bottom box, the casting sand box is the middle box, and the riser sand box is the upper box. Before installing the gate box, a layer of heat-resistant coating needs to be coated on the inner wall of the gate box to prevent the aluminum alloy liquid from corroding the gate box, and the gate box also needs to be preheated to make the preheating temperature of the gate box reach 420 °C.

[0057] In Step 3, the pouring temperature of the aluminum alloy liquid is 730 °C.

[0058] Through a large number of tests in this embodiment, it is proved that when the preheating temperature of the gating box is lower than 400°C, the temperature of the molten metal in the gating box will be significantly reduced, resulting in a decrease in the actual pouring temperature, which is not conducive to the filling and feeding of the molten metal and is prone to defects such as underpouring and porosity; when the preheating temperature of the gating box is higher than 450°C, it will rapidly cool down to below 450°C in the air, causing energy waste and cost increase. In addition, when the liquid level height of the molten metal is lower than 2 / 3 of the height of the gating box, it is necessary to increase the liquid flow rate into the gating box. Otherwise, the liquid level height of the molten metal in the gating box will gradually decrease, resulting in a decrease in the filling head and a reduction in the filling speed; when the liquid level height of the molten metal is higher than 2 / 3 of the height of the gating box, splashing is likely to occur, posing a safety hazard.

[0059] The casting prepared by the gating system and pouring method of this embodiment is as Figure 6 shown. This casting is externally placed on an aircraft and is used to hang or carry a missile. The contour dimensions of this casting are: length 2560 mm, width 600 mm, height 450 mm, maximum wall thickness 45 mm, minimum wall thickness 5 mm. After X-ray inspection, the metallurgical quality inside this casting meets the requirements of Class I parts in HB963-2005. The cut performance of the specified area 3 on this casting reaches: tensile strength σ b = 480 MPa, elongation δ = 13%; the metallographic photo of the specified area 3 on this casting is as Figure 7 shown, indicating that the grains inside this casting are fine and the structure is uniform; when the maximum stress σ max = 120 MPa, loading type R = 0.1, specimen notch Kt = 1, loading frequency f = 100 Hz, the number of fatigue cycles is greater than 10 7 , indicating that this casting has good dynamic load-bearing capacity.

[0060] The gating system and pouring method of the ZL205A aluminum alloy hanger-type structural part in this embodiment achieve smooth filling from bottom to top and regional sequential solidification of large and complex ZL205A aluminum alloy hanger-type structural parts, solving problems such as undercasting, porosity, inclusion, segregation, and low cut performance of large and complex structural parts; at the same time, it realizes constant-temperature and constant-speed pouring and filling of ZL205A aluminum alloy liquid. By optimizing the slit runner, the feeding effect of the riser is improved, effectively eliminating porosity, segregation, and hot crack defects.

[0061] Embodiment 2:

[0062] According to another preferred embodiment of the gating system and pouring method of the ZL205A aluminum alloy hanger-type structural part of the present invention, the specific structure of its gating system, the specific steps of the pouring method, the design principle, and the beneficial effects are basically the same as those in Embodiment 1, except that:

[0063] For the gating system: The inner cavity of the sprue box has a length of 400 mm, a width of 200 mm, and a height of 300 mm. The wall thickness of the sprue box is 4 mm, and the diameter of the through hole at the bottom of the sprue box is 40 mm.

[0064] The cross-section of the sprue is rectangular, with an inner cavity length of 25 mm, a width of 10 mm. The wall thickness of the sprue is 5 mm, the height of the vertical section is 500 mm, and the length of the horizontal section is 100 mm.

[0065] The cross-section of the runner is rectangular, with a length of 60 mm and a width of 40 mm. The upper surface of the slag trap is provided with a serrated structure. In one serrated shape, the angle between the vertical serrated edge and the inclined serrated edge is 30°, and the height of the serrated structure is 30 mm. The length of the slag trap is 100 mm, and the width is the same as that of the runner. The total length of the runner and the slag trap is 1300 mm.

[0066] In the slot gate, the diameter of the vertical cylinder is 60 mm and the height is 500 mm. The cross-section of the slot is an isosceles trapezoid. The length of the long side of the isosceles trapezoid is 1.5 times the length of the short side. The length of the short side of the isosceles trapezoid is 1 times the wall thickness of the casting, and the height of the isosceles trapezoid is 50 mm. The distance between the centerlines of two adjacent slots connected to the same riser is 200 mm.

[0067] The top and bottom surfaces of the riser are both rectangular. The length of the top surface is 250 mm and the width is 80 mm. The length of the bottom surface is 200 mm and the width is 1 times the wall thickness of the casting. The height of the riser is 200 mm. The cross-section of the ingate is rectangular, with a length of 50 mm and a width of 15 mm.

[0068] For the pouring method: The particle size of the original sand used for molding is 70 - 140 mesh, and the resin used for molding is PETSET resin. Before installing the sprue box, the sprue box needs to be preheated so that the preheating temperature of the sprue box reaches 400 °C. The pouring temperature of the aluminum alloy liquid is 720 °C.

[0069] Example Three:

[0070] According to another preferred embodiment of the gating system and pouring method of the ZL205A aluminum alloy hanger - type structural parts of the present invention, the specific structure of the gating system, the specific steps of the pouring method, the design principle, and the beneficial effects are basically the same as those in Example One, except that:

[0071] For the gating system: The inner cavity of the sprue box has a length of 600 mm, a width of 350 mm, and a height of 400 mm. The wall thickness of the sprue box is 6 mm, and the diameter of the through hole at the bottom of the sprue box is 50 mm.

[0072] The cross-section of the sprue is rectangular, with the inner cavity having a length of 35 mm, a width of 15 mm, the wall thickness of the sprue being 8 mm, the height of the vertical section being 700 mm, and the length of the horizontal section being 150 mm.

[0073] The cross-section of the runner is rectangular, with a length of 80 mm and a width of 60 mm. The upper surface of the slag trap is provided with a serrated structure. In one serrated shape, the angle between the vertical serrated edge and the inclined serrated edge is 60°, and the height of the serrated structure is 40 mm; the length of the slag trap is 200 mm, and the width is the same as that of the runner. The total length of the runner and the slag trap is 1400 mm.

[0074] In the slot gate, the diameter of the vertical cylinder is 75 mm and the height is 700 mm. The cross-section of the slot is an isosceles trapezoid. The length of the long side of the isosceles trapezoid is twice the length of the short side. The length of the short side of the isosceles trapezoid is 1.5 times the wall thickness of the casting, and the height of the isosceles trapezoid is 60 mm; the distance between the centerlines of two adjacent slots connected to the same riser is 250 mm.

[0075] The top and bottom surfaces of the riser are both rectangular. The length of the top surface is 350 mm and the width is 100 mm. The length of the bottom surface is 300 mm and the width is 1.5 times the wall thickness of the casting. The height of the riser is 400 mm; the cross-section of the ingate is rectangular, with a length of 70 mm and a width of 20 mm.

[0076] For the pouring method: the particle size of the original sand used for molding is 70 - 140 mesh, and the resin used for molding is PETSET resin; before installing the gating box, the gating box needs to be preheated to a preheating temperature of 450 °C; the pouring temperature of the aluminum alloy liquid is 740 °C.

[0077] Special note: The technical solution of the present invention involves many parameters. It is necessary to comprehensively consider the synergistic effect between various parameters to obtain the beneficial effects and significant progress of the present invention. Moreover, the value ranges of each parameter in the technical solution are obtained through a large number of experiments. For each parameter and the combination of various parameters, the inventor has recorded a large amount of experimental data. Due to space limitations, the specific experimental data are not disclosed herein.

[0078] It is not difficult for those skilled in the art to understand that the gating system and pouring method of the ZL205A aluminum alloy hanger-like structural parts of the present invention include any combination of the above-mentioned invention content and specific implementation parts of the present invention specification and each part shown in the drawings. Due to space limitations and to make the specification concise, the various schemes formed by these combinations are not described one by one. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A gating system for a ZL205A aluminum alloy hanger-like structural part, characterized in that: It includes a first pouring assembly and a second pouring assembly. The first pouring assembly and the second pouring assembly are arranged in parallel. The structures of the first pouring assembly and the second pouring assembly are the same and the corresponding structures are symmetrically arranged. Both the first pouring assembly and the second pouring assembly are connected to the casting cavity. Both the first pouring assembly and the second pouring assembly include a sprue box, three downsprue channels, three cross-riser channels and a number of slit gates. The tops of the three downsprue channels are all connected to the sprue box. The bottoms of the three downsprue channels are respectively connected to one ends of the three cross-riser channels. The number of slit gates are vertically arranged on the three cross-riser channels. Two of the three cross-riser channels are provided with ingates on the sides. The ingates are connected to the casting cavity. The cross-section of the ingate is rectangular, with a length of 50 - 70 mm and a width of 15 - 20 mm. The other ends of the three cross-riser channels are respectively provided with slag traps. The upper surface of the slag trap is provided with a serrated structure. The sides of the number of slit gates are all connected to risers. The bottom of the riser is connected to the casting cavity. The three downsprue channels are of L-shaped square tube structure, and the vertical section and the horizontal section are smoothly transitioned. The slit gate includes a vertical cylinder and a slit. The bottom of the vertical cylinder is connected to the cross-riser channel. The side of the vertical cylinder is connected to the riser and the casting cavity through the slit. The diameter of the vertical cylinder is 60 - 75 mm and the height is 500 - 700 mm. The cross-section of the slit is an isosceles trapezoid. The side of the isosceles trapezoid close to the vertical cylinder is the long side, and the side close to the riser is the short side. The vertical distance between the long side and the short side is the height of the isosceles trapezoid. The length of the long side of the isosceles trapezoid is 1.5 - 2 times the length of the short side. The length of the short side of the isosceles trapezoid is 1 - 1.5 times the wall thickness of the casting. The height of the isosceles trapezoid is 50 - 60 mm. The distance between the center lines of two adjacent slits connected to the same riser is 200 - 250 mm. A flow-blocking structure is designed at the bottom of the slit gate. The flow-blocking structure is a notch formed at the position where the side of the slit connected to the vertical cylinder is close to the bottom of the vertical cylinder.

2. The gating system of the ZL205A aluminum alloy hanger-like structural member according to claim 1, characterized in that: The sprue box is a cuboid structure with an open top and a through hole at the bottom. The length of the inner cavity of the sprue box is 400 - 600 mm, the width is 200 - 350 mm, and the height is 300 - 400 mm. The wall thickness of the sprue box is 4 - 6 mm. A circular through hole is opened at the position close to the wide side at the bottom of the sprue box. The diameter of the through hole is 40 - 50 mm. The sprue box is made of stainless steel material.

3. The gating system of the ZL205A aluminum alloy hanger-type structural part according to claim 2, characterized in that: The cross-section of the downsprue channel is rectangular, with the length of the inner cavity being 25 - 35 mm and the width being 10 - 15 mm. The wall thickness of the downsprue channel is 5 - 8 mm. The height of the vertical section is 500 - 700 mm, and the length of the horizontal section is 100 - 150 mm. The downsprue channel is made of ceramic material.

4. The gating system of the ZL205A aluminum alloy hanger-like structural member according to claim 3, characterized in that: The cross-section of the cross-riser channel is rectangular, with a length of 60 - 80 mm and a width of 40 - 60 mm.

5. The gating system of the ZL205A aluminum alloy hanger-like structural part according to claim 4, characterized in that: The height of the sawtooth structure is 30 - 40 mm. In one sawtooth shape, the sawtooth edge close to the gating box is perpendicular to the upper surface of the slag trap, and the sawtooth edge far from the gating box is inclined to the upper surface of the slag trap. The included angle between the perpendicular sawtooth edge and the inclined sawtooth edge is 30 - 60°; the length of the slag trap is 100 - 200 mm, and the width is the same as that of the cross runner. The total length of the cross runner and the slag trap is 1300 - 1400 mm.

6. The gating system of the ZL205A aluminum alloy hanger-like structural member according to claim 5, characterized in that: The top and bottom surfaces of the riser are both rectangular. The length of the top surface is 250 - 350 mm, and the width is 80 - 100 mm. The length of the bottom surface is 200 - 300 mm, and the width is 1 - 1.5 times the wall thickness of the casting. The height of the riser is 200 - 400 mm.

7. A casting method for a hanger - type structural part made of ZL205A aluminum alloy, characterized in that: Using the gating system for the ZL205A aluminum alloy hanger - type structural part according to any one of claims 1 - 6, it includes the following steps. Step 1: Molding. Coat a layer of release agent on the surface of the mold, let it dry and then assemble the mold. Then use a sand mixer to mix sand for molding. Step 2: Closing the mold. Stack and assemble the runner sand box, casting sand box, and riser sand box from bottom to top in sequence. Then install the gating box at the top of the sprue, making the through - hole at the bottom of the gating box align with the sprue. Before installing the gating box, the gating box needs to be pre - heated to a pre - heating temperature of 400 - 450 °C. Step 3: Pouring. Use a plug rod to block the through - hole at the bottom of the gating box, pour aluminum alloy liquid into the gating box. After the liquid level of the aluminum alloy liquid reaches two - thirds of the height of the gating box, pull out the plug rod, and the aluminum alloy liquid starts to fill the mold cavity. Continuously pour aluminum alloy liquid into the gating box. During the pouring process, keep the liquid level of the aluminum alloy liquid at two - thirds of the height of the gating box. After the aluminum alloy liquid fills the casting cavity, use a plug rod to block the through - hole at the bottom of the gating box, and the pouring ends.

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