Die-casting process of flywheel housing

Abstract

This invention relates to the field of die casting technology, specifically disclosing a die casting process for flywheel housings. The process includes, in sequence, die mold closing – injecting molten metal to fill the cavity – holding pressure – cooling – die mold opening. Cooling chamber one and cooling chamber two are added to the outer core mold corresponding to the straight section of the mounting boss on the die casting mold. Cooling chamber one and cooling chamber two are located on both sides of the straight section of the mounting boss and are both connected to a cooling circulation pipeline. During cooling, flowing coolant is introduced into cooling chamber one and cooling chamber two. This solution addresses the problem of low tensile strength in the straight section of the mounting boss, which fails to meet performance requirements in current flywheel housing production using aluminum alloy die casting.

Description

Technical Field

[0001] This invention relates to the field of die casting technology, and specifically to the die casting process for flywheel housings. Background Technology

[0002] The flywheel housing is the intermediate structure that connects the engine and the transmission, as shown in the attached diagram. Figure 1 As shown, the flywheel housing is basin-shaped. The bottom of the flywheel housing has an irregularly shaped large flat surface because it needs to be connected to the engine block. There is an irregularly shaped ring-shaped mounting boss on the large flat surface, which is used to mate with the end face of the engine block. The top of the flywheel housing is ring-shaped, and the top surface of the basin is used to mate with the end face of the transmission housing.

[0003] With the increasing demand for lightweight engines, transmissions, and related components, flywheel housings have shifted from being made of cast iron to aluminum alloy. High-pressure casting is a preferred method for achieving rapid flywheel housing prototyping. However, high-pressure casting of aluminum alloy flywheel housings results in uneven wall thickness, leading to excessive porosity in certain areas. In particular, the mounting protrusions, which protrude directly from the bottom of the housing, have relatively weak tensile strength, causing the product's tensile strength to fail to meet performance requirements.

[0004] To improve the above problems, multiple cooling pipes are installed on the outer core mold near the mounting protrusion. The cooling pipes are parallel to the bottom of the flywheel housing. Although the tensile strength is improved, the tensile strength of the straight section of the mounting protrusion that is directly opposite the crankshaft mounting hole is unstable. The tensile strength often falls below the product performance requirements, and the pass rate of flywheel housing die casting is only 60%-70%. Summary of the Invention

[0005] The present invention aims to provide a die-casting process for flywheel housings to solve the problem that the tensile strength of the flat section of the mounting protrusion is too low and cannot meet the performance requirements when using the current aluminum alloy die-casting process to produce flywheel housings.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The die-casting process of the flywheel housing includes, in sequence, the die-casting mold closing, the injection of molten metal to fill the cavity, the holding pressure, the cooling, and the die-casting mold opening. Cooling cavity one and cooling cavity two are added to the outer core mold corresponding to the straight section of the mounting boss on the die-casting mold. Cooling cavity one and cooling cavity two are located on both sides of the straight section of the mounting boss. During cooling, flowing coolant is introduced into cooling cavity one and cooling cavity two.

[0008] The principle and advantages of this solution are as follows: According to the inventor's research, the straight section of the mounting boss is located on the annular end face of the crankshaft mounting hole. Since the end face of the crankshaft mounting hole itself bulges outwards from the flywheel housing, the straight section of the mounting boss added to the end face of the crankshaft mounting hole becomes the thickest part of the flywheel housing. At the location of the straight section of the mounting boss, the product wall thickness exceeds 21mm, while the average wall thickness of the entire flywheel housing is only 6mm. This extreme unevenness in wall thickness leads to more porosity and shrinkage cavities in the straight section of the mounting boss. This solution improves the cooling system of the die-casting mold, making the mounting boss... The straight section of the flywheel housing has cooling chambers on both sides, and these chambers are located close to the mounting boss. This allows the thicker wall sections to cool more easily during cooling because the coolant in the cooling chambers is closer to the surface of the mounting boss. This reduces the temperature difference between the thicker wall sections and other parts of the product during cooling, significantly reducing the probability of porosity or shrinkage cavities at the mounting boss location. It also improves the tensile strength of the flywheel housing, increasing the die-casting yield from 60-70% to over 90%. The tensile strength of the flywheel housing has increased from less than 200 MPa before the improvement to over 230 MPa across the board.

[0009] Furthermore, in this solution, the cooling chamber is connected to the cooling circulation pipeline of the die-casting mold, so that when the flywheel housing is die-cast, there is no need to modify the control requirements of the circulating coolant. This ensures the simplicity of the control of the die-casting mold cooling system and avoids the problem of other parts of the product being unqualified due to coolant adjustment.

[0010] Preferably, as an improvement, the number of cooling chamber one and cooling chamber two is determined according to the structure on both sides of the straight section of the mounting boss. The straight section of the mounting boss is connected with radial reinforcing ribs extending to the outer edge of the flywheel housing. Cooling chamber one or cooling chamber two is located between adjacent radial reinforcing ribs, and the cross-section of cooling chamber one or cooling chamber two is elongated.

[0011] Beneficial effects: By placing cooling chamber one and cooling chamber two between adjacent radial reinforcing ribs and making the cross-sections of cooling chamber one and cooling chamber two elongated, the specific surface area of ​​the cooling chambers is large, which is beneficial for the outer core mold to cool faster at the position corresponding to the wall thickness of the mounting boss.

[0012] Preferably, as an improvement, the outer core mold of the die-casting mold is also provided with a cooling column that can pass through the mounting boss. The cooling column is provided with a blind hole, and a spot cooling pipe is inserted into the blind hole. The spot cooling pipe is connected to the cooling circulation pipe on the die-casting mold, and the cooling column is inserted into the designed hole on the flywheel housing mounting boss.

[0013] Beneficial effects: When using this solution, the cooling column with a cooling pipe can penetrate the mounting boss, which is equivalent to forming a connecting hole for connecting with the engine block at the position of the mounting boss after the flywheel housing is formed. This reduces the allowance for machining the connecting hole separately in subsequent processes. At the same time, the setting of the cooling column allows the mounting boss to be cooled from the center position, which means that the middle part of the wall thickness, which is originally the most difficult to cool, can be cooled at the same time as other parts of the product, further improving the uniformity of cooling in all parts of the product.

[0014] Preferably, as an improvement, the cooling column is T-shaped, with the blind hole opening end of the cooling column located at the head of the T-shape. The outer core mold is provided with two-stage stepped holes. The larger hole of the stepped hole is used to accommodate the head of the cooling column and serves as a limiting hole to restrict the rotation of the cooling column. The middle section of the stepped hole is clearance-fitted with the T-shaped leg of the cooling column, and the end section of the stepped hole is in close contact with the leg of the T-shaped cooling column. The bottom of the blind hole is located outside the stepped hole.

[0015] Beneficial effects: By setting the cooling column in a T-shape, when the head of the cooling column is not installed on the large hole, only the leg part of the cooling column contacts the smallest diameter section of the stepped hole, while the rest does not contact the stepped hole of the outer core mold. This reduces the installation difficulty of the cooling column. At the same time, after the cooling column is installed in place, the large hole with a limiting function prevents the cooling column from rotating, and the limiting hole also limits the position of the head of the cooling column, ensuring that both the head and tail of the cooling column are limited by the stepped hole. This ensures both the ease of disassembly and assembly of the cooling column and the stability of its installation.

[0016] Preferably, as an improvement, the point cooling pipe includes an outer pipe and an inner pipe. The point cooling pipe is fixed to the blind hole through the outer pipe. The outer diameter of the inner pipe is smaller than the inner diameter of the outer pipe. The outer pipe is used for water outlet, and the inner pipe is used for water inlet. Both the outer pipe and the inner pipe are connected to the cooling circulation pipeline on the die-casting mold.

[0017] Preferably, as an improvement, the inner tube is inserted into the bottom of the blind hole, and the outlet end of the outer tube is located at the end away from the bottom of the blind hole.

[0018] Beneficial effects: This design allows the inner tube of the cooling pipe to be closer to the bottom of the blind hole, enabling the coolant to quickly enter the blind hole and remain there for a period of time before exiting from the end furthest from the blind hole. This helps to extend the residence time of the coolant and improve the cooling effect.

[0019] Preferably, as an improvement, during injection, the inlet of the molten metal is located on the side of the flat section where the boss is installed in the die-casting mold cavity, and the casting flow channel adopts a multi-support point feeding method with the main channel and multiple branch channels cooperating to feed from the bottom of the flywheel housing circumferentially.

[0020] Beneficial effects: The optimized design of the casting runner in this solution allows molten metal to be fed simultaneously from multiple positions around the bottom of the basin, ensuring rapid forming of the large flat bottom of the basin and the flywheel shell sidewalls extending from the bottom to the top. This ensures that the forming time of the flywheel shell top is roughly the same as the time for the large flat bottom to be fully formed, reducing the possibility of insufficient material and defects after the flywheel shell is formed. Furthermore, by placing the inlet of the casting runner near the straight section of the mounting boss, the straight section of the mounting boss can be filled preferentially, avoiding the problem of more gas trapped in the molten metal during later filling, which would reduce the compressive strength of the straight section of the mounting boss.

[0021] Furthermore, since the straight section of the mounting boss is located on the end face of the crankshaft mounting hole, and the crankshaft mounting hole directly bears the force from the crankshaft rotation, the tensile strength requirement for the straight section of the mounting boss is higher than that for other parts of the mounting boss. In this process, the straight section of the mounting boss is filled first during the die casting process, which helps to improve the strength of the mounting boss in this area.

[0022] Preferably, as an improvement, the die-casting mold has a bottom slag pocket space on the outer core mold that is in close contact with the mounting boss, and the bottom slag pocket space is located on the outer side of the bottom end of the flywheel housing away from the feed inlet; the die-casting mold has a top slag pocket space on the inner core mold that is in close contact with the top of the flywheel housing, and the top slag pocket space includes a far-end top slag pocket space and a near-end top slag pocket space. The far-end top slag pocket space is located on the outer side of the top of the flywheel housing away from the feed inlet, and the near-end top slag pocket space is located on the same side of the flywheel housing as the feed inlet.

[0023] Beneficial Effects: This solution, through the design of the slag pocket space at the bottom of the basin and the slag pocket space at the far top of the basin, ensures that all gas carried in the molten metal can be discharged from the end furthest from the feed inlet, guaranteeing the quality of the flywheel shell molding. Furthermore, by setting a near-end slag pocket space at the top of the flywheel shell basin near the feed inlet, any gas not discharged from the top of the flywheel shell basin near the feed inlet can also be quickly discharged from the near-end slag pocket space, significantly reducing the probability of gas remaining on the product and greatly improving the tensile strength of the entire flywheel shell product.

[0024] Preferably, as an improvement, the die-casting mold has a herringbone-shaped guide groove on the parting surface between the outer core mold and the inner core mold at the crankshaft mounting hole position of the flywheel housing. The herringbone structure of the guide groove forms an inlet and two outlets, with the inlet connecting to the straight section of the mounting boss of the flywheel housing.

[0025] Beneficial effects: The herringbone-shaped guide channel allows the molten metal to move quickly towards the end away from the feed inlet. At the same time, it cooperates with the feed of other branch channels to move towards the side away from the feed inlet, ensuring that the molten metal can fill the cavity evenly. In addition, the herringbone-shaped guide channel is located in the crankshaft mounting hole of the flywheel housing, which can also prevent the gas contained in the molten metal from staying on the wall of the crankshaft mounting hole and not being able to be discharged, further improving the quality of the flywheel housing. After the flywheel housing is formed, the tensile strength of the product is increased by 30-70 MPa.

[0026] Preferably, as an improvement, the casting runner of the die-casting mold includes two main runners and multiple branch runners connected to the main runners. The two main runners are connected to the feed inlet and surround the outer periphery of the flywheel housing. The branch runners are connected to the cavity where the bottom of the flywheel housing is located. The feed inlet of the casting runner is located on the side where the straight section of the boss is installed in the cavity. The main runners are also provided with an extension section on the branch runners that connect to the farthest end.

[0027] Beneficial effects: By setting up the extension section, on the one hand, the molten metal injected to the end of the main channel is buffered, and on the other hand, it is equivalent to the slag bag space, which reduces the probability of gas entering the product and is conducive to improving the tensile strength of the product. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the flywheel housing according to an embodiment of the present invention.

[0029] Figure 2 This is a simplified cross-sectional view of a die-casting mold for forming a flywheel housing according to an embodiment of the present invention.

[0030] Figure 3 This is a three-dimensional structural diagram of the die-casting mold according to an embodiment of the present invention.

[0031] Figure 4 for Figure 3 Enlarged schematic diagram of part A in the diagram.

[0032] Figure 5 for Figure 3 Top view.

[0033] Figure 6 for Figure 3 Top sectional view.

[0034] Figure 7 for Figure 5 BB section view (with flywheel housing).

[0035] Figure 8 for Figure 5 CC section view (without flywheel housing).

[0036] Figure 9 for Figure 8 Enlarged schematic diagram of part D in the diagram.

[0037] Figure 10 This is a bottom view of the outer core mold according to an embodiment of the present invention.

[0038] Figure 11 This is a top view of the inner core mold according to an embodiment of the present invention. Detailed Implementation

[0039] The following detailed description illustrates the specific implementation method:

[0040] The reference numerals in the accompanying drawings include: outer core mold 10, cooling block 1, cooling cavity 11, stepped hole 12, limiting hole 13, sealing block 2, cooling column 3, point cooling pipe 4, inner pipe 41, outer pipe 42, horizontal cooling pipe 5, main channel 6, extension section 61, branch channel 7, bottom slag bag space 8, inner core mold 20, far-end top slag bag space 21, near-end top slag bag space 22, guide channel 23, side core mold 30, bottom forming space 40, top forming space 50, side wall forming space 60, flywheel housing 100, straight section 101, radial reinforcing rib 102, crankshaft mounting hole 103, and feed port 70.

[0041] Example

[0042] Combination Figures 1-3 , Figures 7-8 The die-casting process for the flywheel housing requires a die-casting mold, which includes an outer core mold 10, an inner core mold 20, and multiple side core molds 30 for forming the flywheel housing 100. The outer core mold 10 and the side core molds 30 are located on the outside of the flywheel housing 100. The inner core mold 20 can be inserted into the basin-shaped space of the flywheel housing 100. The outer core mold 10 and the inner core mold 20 can be spaced far apart or close together. One of the outer core mold 10 and the inner core mold 20 is mounted on a fixed template, while the other is mounted on a moving template. The multiple side core molds 30 surround the flywheel housing 100. On the outer wall of the flywheel housing 100, the side core mold 30 moves in the radial direction of the flywheel housing 100. The side core mold 30 is installed on the moving template or the fixed template. The gaps between the multiple side core molds 30 and the inner core mold 20 form the side wall forming space 60 and the top forming space 50 of the flywheel housing 100. The gap between the outer core mold 10 and the inner core mold 20 forms the bottom forming space 40 of the flywheel housing 100. The top forming space 50, the side wall forming space 60 and the bottom forming space 40 constitute the cavity for producing the flywheel housing 100.

[0043] Combination Figures 3 to 7The outer core mold 10 of the die-casting mold, which is closely attached to the end face of the mounting boss, has a cooling block 1 machined on it, which is directly opposite the straight section 101 of the mounting boss. Multiple strip grooves are machined on the cooling block 1, and a sealing block 2 is inserted into each strip groove. The cavity between the bottom of the sealing block 2 and the bottom of the strip groove is the cooling chamber 11. The sealing block 2 has two holes, one for water inlet and the other for water outlet, facilitating the entry and exit of coolant. The cooling chamber 11 includes a first cooling chamber and a second cooling chamber, located on both sides of the straight section 101 of the mounting boss. The minimum distance between the first and second cooling chambers and the surface of the mounting boss is less than 10mm (6-8mm in this embodiment). In this embodiment, the holes on the sealing blocks 2 are connected to the cooling circulation pipes on the die-casting mold, so that the cooling chamber 11 and other cooling circulation pipes of the die-casting mold can be cooled simultaneously.

[0044] The number of cooling chamber one and cooling chamber two is determined based on the structure on both sides of the mounting boss straight section 101. In this embodiment, radial reinforcing ribs 102 extending to the outer edge of the flywheel housing 100 are connected to the mounting boss straight section 101 of the flywheel housing 100. Cooling chambers 11 are located between adjacent radial reinforcing ribs 102. In this embodiment, there are four radial reinforcing ribs 102, and three cooling chambers 11 are located on the side of the radial reinforcing ribs 102 (similarly, there are also three strip grooves and sealing blocks 2 on this side). This allows the cooling chambers 11 to cool the mounting boss straight section 101 at the wall thickness position while also facilitating the cooling of the surrounding radial reinforcing ribs 102.

[0045] Combination Figure 8 and Figure 9 The cooling block 1 is also equipped with a cooling column 3 that can penetrate the straight section 101 of the mounting boss. The cooling column 3 has blind holes machined in it, and a cooling pipe 4 is inserted into the blind holes. The cooling pipe 4 is connected to the cooling circulation pipeline on the die-casting mold. The cooling column 3 is inserted into the designed hole on the mounting boss of the flywheel housing 100. The cooling pipe 4 increases the cooling effect on the straight section 101 of the mounting boss.

[0046] Specifically, the cooling column 3 is T-shaped, and the blind hole opening end of the cooling column 3 is located at the head of the T-shape. The cooling block 1 is machined with two-stage stepped holes 12. The larger hole of the stepped hole 12 is used to accommodate the head of the cooling column 3. The larger hole is a limiting hole 13 used to limit the rotation of the cooling column 3. In this embodiment, the limiting hole 13 is machined with a limiting plane that can limit the rotation of the cooling column 3. At the same time, the limiting plane ensures the installation direction of the cooling column 3. The middle section of the stepped hole 12 is clearance-fitted with the T-shaped leg of the cooling column 3, and the end section of the stepped hole 12 is in close contact with the leg of the T-shaped cooling column 3. The bottom of the blind hole is located outside the stepped hole 12.

[0047] The ignition cooling pipe 4 includes an outer pipe 42 and an inner pipe 41. The inner pipe 41 is fixed inside the outer pipe 42. The ignition cooling pipe 4 is fixed to the blind hole through the outer pipe 42. The outer pipe 42 is threadedly connected to the blind hole. The outer diameter of the inner pipe 41 is smaller than the inner diameter of the outer pipe 42. The outer pipe 42 is used for water outlet, and the inner pipe 41 is used for water inlet. Both the outer pipe 42 and the inner pipe 41 are connected to the cooling circulation pipeline on the die-casting mold. The inner pipe 41 is inserted to the bottom of the blind hole, and the water outlet end of the outer pipe 42 is located at the top of the inner pipe 41.

[0048] Combination Figure 6 The outer core mold 10 is also equipped with multiple horizontal cooling pipes 5. All horizontal cooling pipes 5 are connected to the cooling circulation pipeline. The multiple horizontal cooling pipes 5 are used to cool and reduce the temperature of the large flat surface at the bottom of the flywheel housing 100.

[0049] Combination Figure 7 , Figure 8 and Figure 10 The die-casting mold's casting runner includes two main runners 6 and multiple branch runners 7 connected to the main runners 6. The two main runners 6 are connected to the molten metal inlet 70 and surround the outer periphery of the flywheel housing 100. The branch runners 7 are connected to the cavity where the bottom of the flywheel housing 100 is located (i.e., the bottom forming space 40). The inlet 70 of the casting runner is located on the side where the straight section 101 of the mounting boss is located in the cavity, to facilitate the use of a multi-point simultaneous feeding method with the main runners 6 and multiple branch runners 7 during injection. The main runners 6 also have an extension section 61 machined on the branch runner 7 connecting to the farthest end. In this embodiment, the main runners 6 and branch runners 7 are machined on the parting surface of the outer core mold 10.

[0050] Combination Figure 7 , Figure 8 and Figure 11 The die-casting mold has multiple bottom slag pocket spaces 8 machined on the outer core mold 10, which is closely attached to the mounting boss. The bottom slag pocket spaces 8 are located on the outer side of the bottom end of the flywheel housing 100 away from the feed inlet 70. Adjacent bottom slag pocket spaces 8 are connected by air passages machined on the outer core mold 10. The die-casting mold has top slag pocket spaces machined on the inner core mold 20, which is closely attached to the top of the flywheel housing 100. The top slag pocket spaces include a distal top slag pocket space 21 and a proximal top slag pocket space 22. The distal top slag pocket space 21 is located on the outer side of the top of the flywheel housing 100 away from the feed inlet 70. The proximal top slag pocket space 22 is located on the same side of the flywheel housing 100 as the feed inlet 70. Adjacent bottom slag pocket spaces 8 are connected by air passages machined on the inner core mold 20.

[0051] The die-casting mold has a herringbone-shaped guide groove 23 on the parting surface between the outer core mold 10 and the inner core mold 20 at the crankshaft mounting hole 103 position of the flywheel housing 100. In this embodiment, the guide groove 23 is machined on the inner core mold 20. The herringbone structure of the guide groove 23 forms an inlet and two outlets. The inlet is connected to the cavity position where the straight section 101 of the mounting boss of the flywheel housing 100 is located. The two outlets include a large outlet and a small outlet. The large outlet faces the end of the mounting boss away from the straight section 101, so that more molten metal can move towards the non-straight section 101 end of the mounting boss.

[0052] The die-casting process for flywheel housings includes the following steps:

[0053] S1. Die-casting mold closing: The moving mold moves closer to the fixed mold, the distance between the outer core mold 10 and the inner core mold 20 gradually shortens, and the side core mold 30 gradually moves closer to the inner core mold 20 until the bottom forming space 40 of the flywheel shell 100 is formed between the outer core mold 10 and the inner core mold 20, and the side wall forming space 60 and the top forming space 50 of the flywheel shell 100 are formed between the side core mold 30 and the inner core mold 20. The top forming space 50, the side wall forming space 60 and the bottom forming space 40 constitute the cavity for producing the flywheel shell 100.

[0054] S2. Molten metal is injected into the mold cavity: Molten metal (such as aluminum liquid) is injected into the feed port 70 under high pressure. The molten metal flows from the feed port 70 through the main channel 6 and multiple branch channels 7 and is fed from the bottom of the flywheel housing 100 circumferentially in a multi-point simultaneous casting manner. During the process of filling the mold cavity, the straight section 101 with the mounting boss is filled before the other sections with the mounting boss. After filling the mold cavity, the molten metal flows to each slag pot space (bottom slag pot space 8, near-end top slag pot space 22, far-end top slag pot space 21).

[0055] S3, Pressure Holding.

[0056] S4. Cooling: Coolant is continuously supplied to the cooling circulation pipe. The coolant flows through the horizontal cooling water pipe, the cooling chamber 11 and the blind holes on the cooling column 3, so that different positions of the flywheel housing 100 can be cooled simultaneously and evenly. In this embodiment, the coolant inlet temperature is required to be 30°C and the temperature difference between the inlet and outlet water should not exceed 5°C.

[0057] S5. After cooling, open the mold and remove the flywheel housing 100 with slag.

[0058] The flywheel housing 100 produced using the aforementioned die-casting mold and die-casting process has a significantly improved tensile strength, increasing from less than 200 MPa to over 230 MPa. After multiple tests, the tensile strength has increased by 30-70 MPa. The product qualification rate has increased from less than 70% to over 95%, greatly improving the yield of the flywheel housing 100 made of aluminum alloy high-pressure casting, ensuring production efficiency and reducing production costs.

[0059] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A die-casting process for a flywheel housing, comprising, in sequence, die-casting mold closing, injection of molten metal to fill the cavity, pressure holding, cooling, and die-casting mold opening, characterized in that: A cooling block is machined on the outer core mold of the die-casting mold, which is close to the end face of the mounting boss. The cooling block has multiple strip grooves, and each strip groove is filled with a sealing block. The cavity between the bottom of the sealing block and the bottom of the strip groove is the cooling cavity. The sealing block has two holes, one for water inlet and the other for water outlet. The cooling cavity includes cooling cavity one and cooling cavity two, which are located on both sides of the straight section of the mounting boss. During cooling, coolant is introduced into cooling cavity one and cooling cavity two. During injection, the inlet of the molten metal is located on the side of the flat section where the boss is installed in the die-casting mold cavity. The casting runner adopts a multi-support point feeding method with the main runner and multiple branch runners working together to feed the metal from the bottom of the flywheel housing circumferentially. The die-casting mold has a bottom slag pocket space on the outer core mold that is close to the mounting boss. The bottom slag pocket space is located on the outer side of the bottom end of the flywheel housing away from the feed inlet. The die-casting mold has a top slag pocket space on the inner core mold that is close to the top of the flywheel housing. The top slag pocket space includes a far-end top slag pocket space and a near-end top slag pocket space. The far-end top slag pocket space is located on the outer side of the top of the flywheel housing away from the feed inlet. The near-end top slag pocket space is located on the same side of the flywheel housing as the feed inlet. The die-casting mold has a herringbone-shaped guide groove on the parting surface between the outer core mold and the inner core mold at the crankshaft mounting hole position of the flywheel housing. The herringbone structure of the guide groove forms an inlet and two outlets. The inlet connects to the straight section of the mounting boss of the flywheel housing, and the two outlets include a large outlet and a small outlet. The large outlet faces the end of the mounting boss away from the straight section.

2. The die-casting process for the flywheel housing according to claim 1, characterized in that: The number of cooling chamber one and cooling chamber two is determined according to the structure on both sides of the straight section of the mounting boss. The straight section of the mounting boss is connected with radial reinforcing ribs extending to the outer edge of the flywheel housing. Cooling chamber one or cooling chamber two is located between adjacent radial reinforcing ribs. The cross-section of cooling chamber one or cooling chamber two is long strip.

3. The die-casting process for the flywheel housing according to claim 2, characterized in that: The outer core mold of the die-casting mold is also provided with a cooling column that can pass through the mounting boss. The cooling column has a blind hole, and a cooling pipe is inserted into the blind hole. The cooling pipe is connected to the cooling circulation pipe on the die-casting mold. The cooling column is inserted into the designed hole on the flywheel housing mounting boss.

4. The die-casting process for the flywheel housing according to claim 3, characterized in that: The cooling column is T-shaped, with the blind hole opening end of the cooling column located at the head of the T-shape. The outer core mold has two levels of stepped holes. The larger hole of the stepped hole is used to accommodate the head of the cooling column and is a limiting hole to restrict the rotation of the cooling column. The middle section of the stepped hole is clearance-fitted with the T-shaped leg of the cooling column, and the end section of the stepped hole is in close contact with the leg of the T-shaped cooling column. The bottom of the blind hole is located outside the stepped hole.

5. The die-casting process for the flywheel housing according to claim 3, characterized in that: The point cooling pipe includes an outer pipe and an inner pipe. The point cooling pipe is fixed to the blind hole through the outer pipe. The outer diameter of the inner pipe is smaller than the inner diameter of the outer pipe. The outer pipe is used for water outlet and the inner pipe is used for water inlet. Both the outer pipe and the inner pipe are connected to the cooling circulation pipeline on the die-casting mold.

6. The die-casting process for the flywheel housing according to claim 5, characterized in that: The inner tube is inserted into the bottom of the blind hole, and the outlet end of the outer tube is located at the end away from the bottom of the blind hole.

7. The die-casting process for the flywheel housing according to claim 1, characterized in that: The casting runner of the die-casting mold includes two main runners and multiple branch runners connected to the main runners. The two main runners are connected to the feed inlet and surround the outer periphery of the flywheel housing. The branch runners are connected to the cavity where the bottom of the flywheel housing is located. The feed inlet of the casting runner is located on the side where the straight section of the boss is installed in the cavity. The main runner is also provided with an extension section on the branch runner that connects to the farthest end.

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