A slit gating system and casting method for ZL205A alloy cylindrical castings

Abstract

This invention belongs to the field of aluminum alloy casting technology, and relates to a slit gating system and casting method for ZL205A alloy cylindrical castings. Based on the diameter of the cylindrical ZL205A alloy casting, this invention sets a certain number of slit gating channels on the outer side. The vertical cylinder of the slit gating channel sits on the gating plate connected to the cross-shaped annular horizontal gating channel. The anti-gravity casting gate is set at the cross intersection of the horizontal gating channel. An annular riser is set at the top of the corresponding cylindrical ZL205A alloy casting, and the riser is connected to all the slit gating channels. Chills are placed between two slit gating channels on the outer side of the corresponding cylindrical ZL205A alloy casting, and chills are also placed at the bottom of the bottom flange and the bottom of the top annular flange, forming a slit gating system. This invention comprehensively utilizes the stable filling of the mold by anti-gravity casting molten metal, sequential solidification and feeding under gravity, and improved mold collapsibility to control porosity, cracks, and segregation defects in the ZL205A alloy cylindrical casting.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy casting technology, and relates to a slit gating system and casting method for ZL205A alloy cylindrical castings. Background Technology

[0002] Cylindrical castings come in various forms, including straight cylinders and conical cylinders, with cross-sectional shapes such as circular, elliptical, oblong, and polygonal, as well as variable cross-section cylinders. The outer surface of a cylindrical casting is a smooth curved surface, while the inner surface features reinforcing ribs, bosses, and other structures. Both ends are thick flange mounting edges. A typical cylindrical casting structure is shown below. Figure 1 As shown.

[0003] High-quality cylindrical aluminum alloy castings are typically produced using resin sand casting or investment shell casting with anti-gravity pouring. The gating system employs a slit gating system, with chills and risers installed in thicker sections. Figure 2 (1: Chill, 2: Casting, 3: Vertical cylinder, 4: Gap, 5: Streamline, 6: Ingate, 7: Pour gate) As shown. For Al-Si casting alloys with excellent casting process properties, it is easy to cast cylindrical castings with excellent metallurgical quality and complete shape. In recent years, with the improvement of equipment performance, the alloy material has changed from Al-Si casting alloys to the high-strength ZL205A alloy. ZL205A alloy has a large solidification temperature range, a large solidification shrinkage coefficient, and contains Cu and Cd elements with high specific gravity, making it highly prone to defects such as porosity, hot cracking, and segregation. Using conventional slit gating systems and setting chills and risers in thick sections easily leads to defects such as porosity and segregation near the slit gating, failing to meet the metallurgical quality requirements of the casting. The aforementioned problems arise from two main causes. Firstly, the large, pasty zone formed during the solidification of ZL205A alloy makes feeding difficult, leading to porosity defects. Secondly, the solid core forming the inner cavity of the cylindrical casting exhibits poor yielding during solidification, resulting in a prolonged pasty zone and significant solidification shrinkage. The stress generated by the overall core's obstruction causes thermal cracking in this zone. Under the pressure of anti-gravity pouring, low-melting-point Cu and Cd-rich molten metal is forced into the cracked area during the later stages of solidification, leading to segregation after complete solidification. Porosity, cracks, and segregation defects all negatively impact casting performance. Therefore, castings with severe defects must be scrapped during acceptance, affecting the casting pass rate and cost. Summary of the Invention

[0004] Objective of this invention: To solve the above problems, this invention provides a method for designing an anti-gravity casting process for cylindrical ZL205A alloy castings.

[0005] The technical solution of this invention is as follows: A slit gating system for a cylindrical ZL205A alloy casting. Based on the diameter of the cylindrical ZL205A alloy casting, a certain number of slit gating channels are set on the outer side. The vertical cylinder of the slit gating channel sits on a gating plate connected to a cross-shaped annular horizontal gating channel. The anti-gravity casting gate is set at the cross intersection of the horizontal gating channel. An annular riser is set at the top of the corresponding cylindrical ZL205A alloy casting, and the riser is connected to all slit gating channels. Chills are set between two slit gating channels on the outer side of the corresponding cylindrical ZL205A alloy casting. Chills are also set at the bottom of the bottom flange and at the bottom of the top annular flange, forming a slit gating system.

[0006] The slotted gating system consists of slots and vertical cylinders, distributed on the outer surface of the cylindrical ZL205A alloy casting, or on the inner surface. When distributed on the inner surface, the slots may be discontinuous or evolve into other forms of ingates due to the reinforcing ribs and boss structures in the inner cavity. The arc length distance between adjacent vertical cylinders in the slotted gating system is 250-300 mm, the slot width δ is 1.2-1.5 times the casting wall thickness, the vertical cylinder diameter D is 3-4 times the slot width δ, and the distance from the center of the vertical cylinder to the casting surface is D / 2 + (20-30) mm.

[0007] The lower end of the vertical cylinder of the slit casting system is made into a necked structure, with the necked diameter d being 1 / 2 of the vertical cylinder diameter D, the necked height H being 40-60mm, and the necked section having a draft angle of 1°-3°; the connection between the necked section and the vertical cylinder is smooth.

[0008] The vertical tube sits on the stepped plate of the horizontal runner. The thickness of the stepped plate h is 15-20 mm, and the width A of the stepped plate is 10-15 mm larger than the necked diameter of the vertical tube on which it sits. The cross section of the annular horizontal runner with a cross is rectangular. The length L of the rectangle is equal to the diameter D of the vertical tube, and the width l is equal to 1.5-2 times the thickness h of the stepped plate.

[0009] The bottom width m of the annular riser is 6-10 mm smaller than the top width M of the casting, and it is located in the middle of the top of the casting. The riser height Hm is 60-80 mm, and the slope from bottom to top is 5°-10°. All the slotted runners are connected to the annular riser, and the slots are broken at the bottom of the annular riser by 30-40 mm.

[0010] The surface of the annular riser sand mold is insulated with insulating felt or insulating coating.

[0011] The upper end of the chill is annular, with a thickness of 0.5 to 0.7 times that of the chilled part. The lower end is also annular, but a gap with a radius of 20 to 30 mm is left at the slit gate. The thickness of the chill is 0.7 to 1 times that of the chilled part. When the flange width of the chilled part is less than the notch radius, the chill breaks at the notch, and the gap is 5 to 8 mm.

[0012] A chill is placed between two gaps on the outside of the casting. The horizontal cross-section of the chill is a fan-shaped ring with wedge-shaped sides, and the longitudinal cross-section is trapezoidal. The distance between the edge of the chill and the sprue is 20-30 mm. The inclination angle α on the longitudinal cross-section of the chill is 0.5°-1° depending on the actual wall thickness of the casting. The maximum thickness of the chill is 0.8-1 times the wall thickness of the casting.

[0013] The casting method for the slit gating system of the ZL205A alloy cylindrical casting includes the following steps:

[0014] 1) ZL205A alloy castings are made using a resin sand mold low-pressure casting method. The boss and the stepped surface of the resin sand core forming the inner cavity are tightly fitted. The wall thickness formed by the combination of the two cores is 40-50mm. A gap of about 5mm is maintained between the top surface of the boss and the bottom surface of the groove. During casting, the cavity between the cores is filled with loose sand.

[0015] 2) The pouring temperature of ZL205 alloy shall not be lower than 710℃; before pouring, calculate the filling pressure difference according to the mold height, and the filling pressure difference shall be equal to the mold height. The holding pressure difference shall be equal to the filling pressure difference. Thermocouples shall be installed at the step of the horizontal runner.

[0016] 3) After the casting and filling are completed, when the temperature of the molten metal at the step plate of the horizontal runner reaches the solidus line, the pressure is immediately released, and the casting is completely fed and solidified under the action of gravity.

[0017] When the core adopts a segmented structure, it is divided into 3 or 4 parts according to the core diameter, and the gap between the cores is 20-30mm.

[0018] The beneficial effects of this invention are as follows: This invention comprehensively utilizes anti-gravity pouring of molten metal to smoothly fill the mold, sequential solidification and feeding under gravity, and improved mold collapsibility to control porosity, cracks and segregation defects in ZL205A alloy cylindrical castings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a cylindrical casting structure. Wherein: a represents the outer shape of the cylindrical casting, b represents the internal structure of the cylindrical casting, c represents the outer shape of the irregularly shaped cylindrical casting, and d represents the internal structure of the irregularly shaped cylindrical casting.

[0020] Figure 2 This is a standard process design for cylindrical castings. Where: a represents the external chill, b represents the casting's external shape with the gating system and chill, c represents the casting's internal cavity with the gating system and chill, and d represents the gating system.

[0021] Figure 3This is a structural diagram of the slotted gating system of the present invention. Wherein: a is the overall view of the gating system, b is the horizontal cross-sectional view of the gating system, c is the longitudinal cross-sectional view of the gating system, and d is the structural diagram of the horizontal gating runner.

[0022] Figure 4 This diagram illustrates the riser and its connection to the slotted gating system in this invention. Specifically: a) is a schematic diagram of the connection between the slotted gating system and the riser; b) is a schematic diagram of the connection between the riser and the casting.

[0023] Figure 5 These are schematic diagrams of the top and bottom chills of the casting in this invention. Wherein: a is a schematic diagram of the top chill, and b is a schematic diagram of the bottom chill.

[0024] Figure 6 This is a schematic diagram of the chill structure on the outer surface of the casting according to the present invention. Wherein a is a distribution diagram of the chills on the outer surface, b is a horizontal cross-sectional view of the chills, and c is a longitudinal cross-sectional view of the chills.

[0025] Figure 7 This is a schematic diagram of the core blocks and assembly structure of the present invention. Wherein a is a schematic diagram of the assembly of the block core, b is a schematic diagram of the grooves and bosses on the edge of the core sand block, and c is a schematic diagram of the cooperation between the grooves and bosses.

[0026] Figure 8 This is a structural diagram of a missile hull. Where: a represents the external shape, and b represents the internal cavity structure.

[0027] Figure 9 This diagram shows the gating system and riser distribution of a certain type of missile hull. Specifically: a) is the external structural diagram, b) is the internal cavity structural diagram, and c) is the bottom horizontal gating channel.

[0028] Figure 10 This diagram shows the distribution of chills in a certain type of missile hull casting. Where: a represents the bottom chill, b represents the position of the bottom chill on the casting, and c represents the outer chill.

[0029] Figure 11 This is a schematic diagram of the upper chill of a certain type of missile hull. Where: a represents the upper chill, and b represents the position of the upper chill on the casting.

[0030] Figure 12 This is a horizontal cross-sectional view of a missile hull (distribution of external chills and dimensions of the slotted gating system). Wherein: a is the horizontal cross-sectional view of the external chills, and b is the horizontal cross-sectional dimension of the slotted gating system.

[0031] Figure 13 This is a dimensional drawing of the horizontal gating system and vertical tube of a certain type of missile hull.

[0032] Figure 14 This is a schematic diagram of the riser structure of a certain type of missile hull.

[0033] Figure 15This is a diagram showing the segmented structure of the sand core inside the hull of a certain type of missile.

[0034] Among them: 1 is the external chill, 2 is the casting, 3 is the vertical cylinder, 4 is the gap, 5 is the annular horizontal runner, 6 is the bottom-pouring ingate, 7 is the annular riser, 8 is the stepped plate, 9 is the vertical cylinder necking, 10 is the anti-gravity pouring gate, 11 is the upper flange chill, 12 is the lower flange chill, 13 is the core boss, 14 is the top surface of the core boss, 15 is the core groove, 16 is the bottom surface of the core groove, 17 is the stepped surface of the core sand block, 18 is the annular reinforcing rib of the casting cavity, and 19 is the mounting boss of the casting cavity. Detailed Implementation

[0035] Taking a cylindrical compartment casting as an example, the implementation process of the present invention will be described in detail.

[0036] A design method for a slit-type gating system for anti-gravity casting of resin sand molds (differential pressure casting for thicker walls, low-pressure casting for thinner walls, and vacuum pressure casting for very thin walls) is provided, such as... Figure 3 As shown, the detailed structure is as follows: Based on the diameter of the cylindrical ZL205A alloy casting, a certain number of slit gating channels are set on the outer side. The number of slit gating channels is based on experience, and the spacing is generally 250-300 for casting wall thickness of 10-20mm. The vertical cylinder of the slit gating channel sits on the gating plate connected to the cross-shaped annular horizontal gating channel. The anti-gravity casting gate is set at the cross intersection of the horizontal gating channel. An annular riser is set at the top of the corresponding cylindrical ZL205A alloy casting. The riser is connected to all slit gating channels. Chills are set between the two slit gating channels on the outer side of the corresponding cylindrical ZL205A alloy casting. Chills are set at the bottom of the bottom flange and at the bottom of the top annular flange, forming a slit gating system.

[0037] Slot gating system consists of Figure 3 The gating system consists of a central slit 4 and a vertical cylinder 3, distributed on the outer surface of the cylindrical casting, or it can be distributed on the inner surface. When distributed on the inner surface, due to the presence of reinforcing ribs, bosses, and other structures within the inner cavity, the slit may be discontinuous or evolve into other forms of internal gating. The arc length distance between adjacent vertical cylinders in the slit gating system is 250–300 mm, the slit width δ is 1.2–1.5 times the casting wall thickness, the vertical cylinder diameter D is 3–4 times the slit width δ, and the distance from the center of the vertical cylinder to the casting surface is D / 2 + (20–30) mm.

[0038] The lower end of the vertical column of the slotted gating system is designed with a necked structure, such as... Figure 3 As shown in Figure 9, the necking diameter d is half the diameter D of the vertical tube, and the necking height H is 40-60mm. To facilitate demolding during molding, the necking can be set with a draft angle of 1°-3°. The connection between the necking and the vertical tube is smooth.

[0039] The vertical tube sits on the stepped plate of the horizontal runner. The thickness of the stepped plate h is 15-20mm, and the width A of the stepped plate is 10-15mm larger than the diameter of the neck on which it sits. The cross section of the annular horizontal runner with a cross is rectangular. The length L of the rectangle is equal to the diameter D of the vertical tube, and the width l is equal to 1.5-2 times the thickness h of the stepped plate.

[0040] An annular riser is installed at the top, and the slit-type gating system is connected to the riser. The slit is interrupted at the bottom of the riser by a distance of 30-40mm. Figure 4 As shown in the dashed area, the bottom width m of the riser is 6-10 mm smaller than the top width M of the casting, and it is located in the middle of the top of the casting. The riser height Hm is 60-80 mm, and the slope from bottom to top is 5°-10°.

[0041] The surface of the riser sand mold is insulated with insulating felt or insulating coating to improve the feeding effect of the riser.

[0042] Chills are placed under the thick flange rings at the upper and lower ends of the casting, such as... Figure 5 As shown, the chill is made of ordinary carbon steel and is machined. The upper chill is ring-shaped, with a thickness of 0.5 to 0.7 times that of the part being chilled. Figure 5 The upper flange chill is shown as 11; the lower chill is shown as... Figure 5 As shown in the lower flange chill 12, the chill is also annular, but a gap with a radius of 20 to 30 mm is left near the slotted gate. The thickness of the chill is 0.7 to 1 times the thickness of the chilled part. When the flange width of the chilled part is smaller than the notch radius, the chill can be broken at the notch.

[0043] A chill is placed between two gaps on the outside of the casting. The horizontal cross-sectional shape of the chill is as follows: Figure 6 As shown in (b), the longitudinal cross-sectional shape is as follows: Figure 6 As shown in (c), the distance between the edge of the chill and the sprue is 20-30 mm. The inclination angle α on the longitudinal section of the chill is 0.5°-1° depending on the actual wall thickness of the casting. The maximum thickness of the chill is 0.8-1 times the wall thickness of the casting.

[0044] When casting, if the core adopts a modular structure, it is divided into 3 or 4 pieces according to the diameter, and the combined structure is as follows: Figure 7As shown in (a), the gap between the cores is 20-30mm; the core boss 13 and the core sand block step surface 17 of the core groove 15 are tightly fitted, and the wall thickness formed by the combination of the two cores is 40-50mm. A gap of 5mm-8mm should be maintained between the top surface 14 of the core boss and the core groove 15. The cavity between the cores is filled with loose sand. The pouring temperature of ZL205 alloy is not lower than 710℃; before pouring, the filling pressure difference is calculated according to the mold height. The filling pressure difference should be just enough to make the molten metal rise to the mold height, and the holding pressure difference is equal to the filling pressure difference; a thermocouple is installed at the step plate of the horizontal runner. After the pouring and filling are completed, when the temperature of the molten metal at the step plate of the horizontal runner reaches the solidus line, the pressure is immediately released, and the casting is completely fed and solidified under the action of gravity (and ambient pressure in differential pressure).

[0045] Example

[0046] The specific structure of a certain cabin casting is as follows: Figure 8 As shown, the external dimensions are Φ800×550mm, with a wall thickness of 14mm. The upper 140mm section is tapered, and the lower inner side has four 40mm thick casting mounting bosses 19. The inner cavity is equipped with annular reinforcing ribs 18. The inner flanges at the top and bottom are 20mm and 13mm thick, respectively. The material is ZL205A alloy, and the metallurgical quality requirements meet the HB963 Class I casting level.

[0047] The gating system design for this section is as follows: Figure 9 As shown. Based on the diameter of the hull casting, eight slotted gating cylinders 3 and slots 4 are installed on the outer side, and slotted gating cylinders 3 and slots 4 are respectively installed on four protrusions at the bottom on the inner side. The slotted gating cylinders sit on stepped plates 8 connected to the annular horizontal gating 5. The anti-gravity pouring inlet 10 is located at the cross intersection of the horizontal gating. An annular riser 7 is installed at the top of the casting, and the riser 7 is connected to the eight slotted gating systems.

[0048] like Figure 10 As shown, an external chill 1 is installed between the two slotted gating channels on the outer side of the section casting; a lower flange chill 12 is installed at the bottom of the bottom flange; and an upper flange chill 12 is also installed at the bottom of the top annular flange (as shown). Figure 11 .

[0049] The spacing between the slotted runners in the section is 270mm (arc length). Based on its wall thickness of 14mm, the width δ of the slotted runner is set to 20mm, the diameter D of the vertical cylinder is set to 60mm, and the distance from the center of the vertical cylinder to the outer wall is 55mm. Figure 12 As shown; the lower part of the vertical cylinder extends 80mm beyond the bottom surface of the casting, and the diameter of the lower 50mm section is changed to 30mm. The width of the sprue at the four bosses inside the compartment is set to 30mm, the diameter of the vertical cylinder is also Φ60mm, and the diameter of the lower 50mm section of the vertical cylinder is changed to 30mm, as shown. Figure 13 As shown.

[0050] The horizontal sprue is annular. The vertical cylinders of the eight slotted sprues on the outer side of the section and the four slotted sprues on the inner side of the section sit on stepped plates on the annular horizontal sprue. The stepped plates are 20mm thick and 50mm wide. The cross-sectional shape of all horizontal sprues is rectangular; the cross-sectional dimensions of the annular horizontal sprue are 56×40mm, and the cross-sectional dimensions of the cross-shaped horizontal sprue are 50×40mm. Figure 13 As shown.

[0051] The distribution of chills in the casting of this section is as follows Figure 10 Lower flange chill 12 Figure 11 Upper and middle flange chills 11 Figure 12 The outer chill is shown in Figure 1. The thickness of the outer chill gradually decreases from the bottom of the casting upwards, with a slope of 0.5°, and a bottom thickness of 13mm; the sides of the chill are wedge-shaped, as shown in Figure 1. Figure 12 As shown in Figure 1, the distance between the lateral edge of the chill and the sprue is approximately 25 mm. The thickness of the annular chill on the bottom surface of the casting is approximately the same as the thickness of the bottom flange, which is 13 mm. The notch on the chill is to avoid the area of ​​the sprue. The top chill is annular and its thickness is approximately 70% of the thickness of the upper flange (22 mm), which is 15 mm.

[0052] The annular riser at the top of the compartment is 200mm high, and the width at the riser root is 6mm smaller than the width of the annular flange being shrunken (3mm on each side). The gap connecting to the riser is broken at the riser root by 40mm. The inner surface of the riser cavity is covered with 3mm thick aluminum silicate fiber felt for riser insulation. Figure 14 As shown.

[0053] The sand core inside the compartment consists of three layers stacked together. However, each layer is constructed according to... Figure 15 It is divided into 4 parts as shown, and then assembled together for casting.

[0054] This section was cast using low-pressure casting, with the mold and core made of PEPSET self-hardening resin sand. The casting process parameters are shown in Table 1. The metallurgical quality of the castings cast using this process reached the level of HB963 Class I parts.

[0055] Table 1. Casting process parameters for compartment sections.

[0056]

Claims

1. A slit-type gating system for ZL205A alloy cylindrical castings, characterized in that, Based on the diameter of the ZL205A alloy cylindrical casting, a certain number of slotted runners are set on the outer side. Each slotted runner consists of a slot and a vertical tube. The lower end of the vertical tube of the slotted runner is made into a necked structure, with a necking diameter d equal to half the vertical tube diameter D, a necking height H of 40–60 mm, and a draft angle of 1°–3°. The connection between the neck and the vertical tube is smooth. The vertical tube of the slotted runner sits on a stepped plate connected to the cross-shaped annular horizontal runner. The thickness h of the stepped plate is 15–20 mm, and the width A of the stepped plate is 50 mm. The cross-shaped annular horizontal runner has a rectangular cross-section. The anti-gravity casting gate is located at the intersection of the horizontal runners, corresponding to the ZL205A alloy cylindrical casting. An annular riser is provided at the top of the casting, which is connected to all the sprue gates. A chill is placed between the two sprue gates on the outer side of the ZL205A alloy cylindrical casting. The horizontal cross-section of the chill is a fan ring with wedge-shaped sides and a trapezoidal longitudinal cross-section. The distance between the edge of the chill and the sprue gate is 20-30 mm. The inclination angle α on the longitudinal cross-section of the chill is 0.5°-1° according to the actual wall thickness of the ZL205A alloy cylindrical casting. The thickness of the chill is 0.8-1 times the wall thickness of the ZL205A alloy cylindrical casting. The thickness of the outer chill gradually decreases from the bottom of the ZL205A alloy cylindrical casting upwards. A chill is also provided at the bottom of the bottom flange and at the bottom of the top annular flange, forming a sprue gating system.

2. The slit gating system for ZL205A alloy cylindrical castings according to claim 1, characterized in that, The arc length spacing between adjacent vertical cylinders in the slotted gating system is 250-300 mm, the slot width δ is 1.2-1.5 times the casting wall thickness, the cylinder diameter D is 3-4 times the slot width δ, and the distance from the center of the cylinder to the casting surface is D / 2+(20-30) mm.

3. The slit gating system for ZL205A alloy cylindrical castings according to claim 1, characterized in that, The bottom width m of the annular riser is 6-10 mm smaller than the top width M of the casting, and it is located in the middle of the top of the ZL205A alloy cylindrical casting. The riser height Hm is 60-80 mm, the slope from bottom to top is 5°-10°, and the gap is broken at the bottom of the annular riser for 30-40 mm.

4. The slit gating system for ZL205A alloy cylindrical castings according to claim 1, characterized in that, The surface of the annular riser sand mold is insulated with insulating felt or insulating coating.

5. The slit gating system for ZL205A alloy cylindrical castings according to claim 1, characterized in that, The chills at the bottom of the top annular flange are annular, with a thickness of 0.5 to 0.7 times that of the part being chilled. The chills at the bottom of the bottom flange are also annular, but a notch with a radius of 20 to 30 mm is left at the slotted gate. The thickness of the chills is 0.7 to 1 times that of the part being chilled. When the flange width of the part being chilled is less than the radius of the notch, the chills break at the notch, with a gap of 5 to 8 mm.

6. A casting method for a slit gating system for ZL205A alloy cylindrical castings according to any one of claims 1-5, comprising the following steps: 1) The ZL205A alloy cylindrical casting adopts the resin sand mold low-pressure casting method. The resin sand core forming the inner cavity adopts a segmented structure, which is divided into 3 or 4 pieces according to the core diameter. The gap between the cores is 20-30mm. The bosses of two resin sand cores fit tightly with the stepped surfaces of the grooves. The wall thickness formed by the combination of two cores is 40-50mm. A gap of about 5mm is maintained between the top surface of the boss and the bottom surface of the groove. During casting, the cavity between the cores is filled with loose sand. 2) The pouring temperature of ZL205A alloy shall not be lower than 710℃; before pouring, calculate the filling pressure difference according to the mold height, and the filling pressure difference shall be equal to the mold height. The holding pressure difference shall be equal to the filling pressure difference. Thermocouples shall be installed at the step of the horizontal runner. 3) After the casting and filling are completed, when the temperature of the molten metal at the step plate of the horizontal runner reaches the solidification line, the pressure is immediately released, and the ZL205A alloy cylindrical casting is completely fed and solidified under the action of gravity.

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