Sand core for aluminum alloy closed inner cavity casting and casting process of sand core

Abstract

The invention belongs to the technical field of metal casting, and particularly relates to a sand core for an aluminum alloy closed inner cavity casting and a casting process of the sand core, a process boss is arranged on the sand core, the process boss is connected with an inner sand core, the process boss is an inverted trapezoidal cone, and the included angle beta between the two sides of the central section of the process boss and the upper surface of the sand core ranges from 25 degrees to 40 degrees; a sinking blind hole is formed in the surface of the sand core, the process boss is located in the center of the sinking blind hole, a via hole column is arranged at the bottom of the process boss and connected with the sinking blind hole, and the diameter of the via hole column is smaller than that of the root of the process boss. According to the sand core, a positioning mechanism can be arranged in a cavity sand core, the sand core can be fixed and prevented from floating in the pouring process, the sand core can be used as a sand outlet hole during sand removal of a casting, residual core sand in the cavity can be cleaned, a patch can be directly placed in a process hole when the process hole is subjected to repair welding, welding is convenient, the casting production cost and the technical difficulty are reduced, and the production efficiency is improved. Meanwhile, weld beading can be effectively prevented from falling into the inner cavity, and the process requirement is met.

Description

Technical Field

[0001] This invention belongs to the field of metal casting technology, and specifically relates to a sand core for aluminum alloy closed-cavity castings and its casting process. Background Art

[0002] Large, enclosed cavities are a common structure in aluminum alloy castings. These enclosed cavities are used to store liquids, gases, and other media, and must withstand significant pressure during operation. Castings such as integrally cast fuel tanks and motor housings for new energy vehicles have large-volume enclosed cavity structures, and these types of castings are widely used in aerospace, automotive, and other fields.

[0003] Currently, for casting large closed cavities, after casting, almost vertical process holes are formed on them, and then process hole patch blocks are welded onto the process holes. This has two drawbacks: first, the gap between the process hole patch block and the process hole is very small, making welding difficult and greatly affecting production efficiency and welding quality; second, the weld beads generated during welding are prone to falling into the cavity. In long-term use, the weld beads rub against the inner wall of the cavity under the action of water or air flow, which does not meet the usage requirements. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a sand core for aluminum alloy closed-cavity castings and its casting process, thereby solving the above-mentioned technical problems.

[0005] Technical solution: In order to achieve the above objectives, the present invention provides a sand core for aluminum alloy closed inner cavity castings. The sand core is provided with a process boss, which is connected to the inner sand core. The process boss is an inverted trapezoidal cone, and the included angle β between the two sides of its central section and the upper surface of the sand core is 25° to 40°. The surface of the sand core is provided with a sunken blind hole, and the process boss is located at the center of the sunken blind hole. The bottom of the process boss is provided with a through-hole column connected to the sunken blind hole, and the diameter of the through-hole column is smaller than the root diameter of the process boss.

[0006] Furthermore, the depth of the recessed blind hole is 2mm, the root diameter of the process boss is 30-50mm, and the diameter of the recessed blind hole is 10mm larger than the root diameter of the process boss.

[0007] A casting process for an aluminum alloy closed-cavity casting includes the following steps: S1 uses 3D printing to shape the sand core; S2, the completed sand core is assembled into the casting mold, and then the molten aluminum alloy liquid is poured into the mold. After solidification and cooling, through holes and process holes are formed on the casting due to the action of process bosses and through-hole pillars. S3, perform shell breaking process; S4, process hole patch block; S5, Place the processed process hole patch block into the process hole and weld it into the process hole.

[0008] Furthermore, the included angle α between the two sides of the center section of the process hole and the centerline is 25° to 40°, and the root diameter of the process hole is 40-60mm.

[0009] Furthermore, the casting has a wall thickness reinforcement section on the inner side opposite to the process hole, the wall thickness reinforcement section having a diameter of 50-70mm and a height of 2mm.

[0010] Furthermore, the process hole patch block is a trapezoidal cone, and the gap between the root edge of the process hole patch block and the root of the process hole is 1.5-2mm.

[0011] Furthermore, the shell breaking process in step S3 includes coarse shell breaking and fine cleaning. The coarse shell breaking includes using vibration to remove sand and pneumatic hammers to strike the sand core, prioritizing the removal of large sand shells on the outside of the sand core to expose the process hole location. For the sand core inside the process hole, a flexible tool is used for cleaning to avoid damaging the hole wall. The fine cleaning includes cleaning residual sand cores, which involves using mechanical or chemical cleaning to remove residual sand cores inside the process holes, followed by grinding to remove sand and burrs adhering to the casting surface.

[0012] Furthermore, the specific welding method in step S5 is as follows: the process hole patch block is placed in the process hole, and after spot welding or adhesive positioning, the installation accuracy of the patch block is checked using a right angle ruler and dial indicator, and then continuous fillet welds are performed.

[0013] As can be seen from the above technical solution, the present invention has the following beneficial effects: 1. The sand core structure in this invention can be equipped with a positioning mechanism to fix the sand core in the mold cavity, preventing it from floating during the casting process. It can also be used as a sand outlet during casting cleaning to remove residual core sand from the mold cavity. Furthermore, when repairing process holes, the process hole patch block can be placed directly inside the process hole. Since both the process hole and the process hole patch block have an inclination and are in opposite directions, welding is convenient, reducing casting production costs and technical difficulties. At the same time, the connection position between the process hole and the through hole has a boss, and the process hole patch block is welded to this boss, effectively preventing weld beads from falling into the inner cavity.

[0014] 2. The present invention sets a sunken blind hole on the sand core, and after casting, a wall thickness reinforcement part is formed on the casting. The wall thickness reinforcement part is located at the process hole position, which can effectively enhance the structural strength of this part and meet the requirement of withstanding greater pressure during operation. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the sand core described in this invention; Figure 2 This is a schematic diagram of the central cross-section of the sand core described in this invention; Figure 3 This is a schematic diagram of the structure of the casting described in this invention; Figure 4 This is a schematic diagram of the center cross-section of the casting described in this invention; Figure 5 This is a schematic diagram of the structure after the welding process hole patch is applied to the casting.

[0016] In the figure: 1-process boss, 2-sunken blind hole, 3-through hole post, 4-through hole, 5-process hole, 6-process hole patch block, 7-wall thickness reinforcement. Detailed Implementation

[0017] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0018] like Figure 1-5 As shown, a sand core for aluminum alloy closed-cavity castings is provided. The sand core has a process boss 1, which is connected to the inner sand core. The process boss 1 is an inverted trapezoidal cone, and the included angle β between the two sides of its central section and the upper surface of the sand core is 25° to 40°. The presence of the process boss 1 can form a tapered process hole 6 on it after the casting is formed. The specific degree of the included angle β can be reasonably selected according to the specifications of the aluminum alloy closed-cavity and the space required for subsequent welding. The surface of the sand core is provided with a sunken blind hole 2. The process boss 1 is located at the center of the sunken blind hole 2. The bottom of the process boss 1 is provided with a through-hole post 3 connected to the sunken blind hole 2. The diameter of the through-hole post 3 is smaller than the root diameter of the process boss 1. The sunken blind hole 2 increases the inner wall thickness of the process hole 6 on the casting by 2mm, thereby enhancing the structural strength of this part. The through-hole post forms a through hole 4 on the casting, which connects the process hole 6 and the inner cavity. Since the diameter of the process hole is larger than that of the through hole, a circular boss is formed at the junction of the two for welding the process hole patch block 6.

[0019] Specifically, the depth of the recessed blind hole 2 is 2mm, the root diameter of the process boss 1 is 30-50mm, and the diameter of the recessed blind hole 2 is 10mm larger than the root diameter of the process boss 1.

[0020] A casting process for an aluminum alloy closed-cavity casting includes the following steps: S1 uses 3D printing to shape the sand core; S2, the completed sand core is assembled into the casting mold, and then the molten aluminum alloy liquid is injected into the mold. After solidification and cooling, due to the action of the process boss 1 and the through hole column 3, through holes 4 and process holes 5 are formed on the casting. S3, perform shell breaking process; S4, process hole patch block 6 is processed; S5, place the processed process hole patch block 6 into the process hole 5 and weld it into the process hole 5.

[0021] Specifically, the included angle α between the two sides of the center section of the process hole 5 and the centerline is 25° to 40°, and the root diameter of the process hole 4 is 40-60mm. The included angle α is determined by the included angle β and the two angles are consistent.

[0022] Specifically, the casting has a wall thickness reinforcement 7 on the inner side opposite to the process hole 5. The diameter of the wall thickness reinforcement 7 is 50-70mm and the height is 2mm.

[0023] The process hole patch block 6 is a trapezoidal cone. The gap between the root edge of the process hole patch block 6 and the root of the process hole 5 is 1.5-2mm. A gap of 1.5-2mm is left between the process hole patch block 6 and the bottom of the process hole 5 to ensure weld penetration and control welding deformation.

[0024] Specifically, the shell breaking process in step S3 includes coarse shell breaking and fine cleaning. The coarse shell breaking includes using vibration to remove sand and pneumatic hammers to strike the sand core, prioritizing the removal of large pieces of sand shell on the outside of the sand core to expose the process hole location. For the sand core inside the process hole, a flexible tool is used for cleaning to avoid damaging the hole wall. The fine cleaning includes cleaning residual sand cores, which involves using mechanical or chemical cleaning to remove residual sand cores inside the process holes, followed by grinding to remove sand and burrs adhering to the casting surface.

[0025] A further optimized solution involves placing the process hole patch block 6 in the process hole 5, positioning it by spot welding or adhesive bonding, checking the installation accuracy of the patch block using a right-angle ruler and dial indicator, and then performing continuous fillet welds.

[0026] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A sand core for aluminum alloy closed-cavity castings, characterized in that, The sand core is provided with a process boss (1), which is connected to the inner sand core. The process boss (1) is an inverted trapezoidal cone, and the angle β between the two sides of its central section and the upper surface of the sand core is 25° to 40°. The surface of the sand core is provided with a sunken blind hole (2), and the process boss (1) is located at the center of the sunken blind hole (2). The bottom of the process boss (1) is provided with a through-hole column (3) connected to the sunken blind hole (2). The diameter of the through-hole column (3) is smaller than the root diameter of the process boss (1).

2. The sand core for aluminum alloy closed-cavity castings according to claim 1, characterized in that, The depth of the sunken blind hole (2) is 2mm, the root diameter of the process boss (1) is 30-50mm, and the diameter of the sunken blind hole (2) is 10mm larger than the root diameter of the process boss (1).

3. A casting process for an aluminum alloy closed-cavity casting, wherein the casting is performed using a sand core as described in any one of claims 1-2, characterized in that, Includes the following steps: S1 uses 3D printing to shape the sand core; S2, the completed sand core is assembled into the casting mold, and then the molten aluminum alloy liquid is injected into the mold. After solidification and cooling, through holes (4) and process holes (5) are formed on the casting due to the action of the process boss (1) and through hole column (3). S3, perform shell breaking process; S4, process hole patch block (6). S5, place the processed process hole patch block (6) in the process hole (5) and weld it in the process hole (5).

4. The casting process for an aluminum alloy closed-cavity casting according to claim 3, characterized in that, The included angle α between the two sides of the center section of the process hole (5) and the centerline is 25° to 40°, and the root diameter of the process hole (4) is 40-60mm.

5. The casting process for an aluminum alloy closed-cavity casting according to claim 3, characterized in that, The casting has a wall thickness reinforcement part (7) on the inner side opposite to the process hole (5). The diameter of the wall thickness reinforcement part (7) is 50-70mm and the height is 2mm.

6. The casting process for an aluminum alloy closed-cavity casting according to claim 3, characterized in that, The process hole patch block (6) is a trapezoidal cone, and the gap between the root edge of the process hole patch block (6) and the root of the process hole (5) is 1.5-2mm.

7. The casting process for an aluminum alloy closed-cavity casting according to claim 3, characterized in that, The shell breaking process in step S3 includes coarse shell breaking and fine cleaning. The coarse shell breaking includes using vibration to remove sand and pneumatic hammers to strike the sand core. Priority is given to cleaning large pieces of sand shell on the outside of the sand core to expose the process hole location. For the sand core inside the process hole, a flexible tool is used to clean it to avoid damaging the hole wall. The fine cleaning includes cleaning residual sand cores, which involves using mechanical or chemical cleaning to remove residual sand cores inside the process holes, followed by grinding to remove sand and burrs adhering to the casting surface.

8. The casting process for an aluminum alloy closed-cavity casting according to claim 3, characterized in that, The specific welding method in step S5 is as follows: place the process hole patch block (6) in the process hole (5), and after spot welding or adhesive positioning, use a right angle ruler and dial indicator to check the installation accuracy of the patch block, and then perform continuous fillet weld welding.

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