A diesel engine piston and a mold, a casting method and a diesel engine piston casting machine thereof

Abstract

The present application relates to the field of casting, in particular to a diesel engine piston, a mold, a casting method and a diesel engine piston casting machine. The present application provides a casting method of a diesel engine piston, comprising: pouring aluminum liquid into a diesel engine piston mold, cooling in the order of inner mold, pin core, outer mold and mold cover, and obtaining a diesel engine piston. The casting method makes full use of the casting structure and combined phase types of the commonly used piston material Al-12Si-5Cu-2Ni-1Mg aluminum-silicon eutectic alloy of the current diesel engine aluminum piston, optimizes the casting equipment and mold, realizes the form and distribution of the internal casting structure of the material, improves the high-temperature fatigue cracking resistance of the diesel engine piston, and reduces the manufacturing cost of the high-index diesel engine piston. Experiments show that the present application successfully obtains a low-cost diesel engine piston with a combustion chamber throat that can be used well at a high temperature of nearly 400 DEG C, high reliability and long service life.

Description

Technical Field

[0001] This invention relates to the field of casting, specifically to a diesel engine piston, its mold, casting method, and diesel engine piston casting machine. Background Technology

[0002] The piston is one of the key components of a diesel engine, and its working environment is very special. It, together with the cylinder head, forms the combustion chamber. The combustion chamber is a small, sealed space with a special structural shape. The intake air is squeezed into the narrow space of the combustion chamber by the piston, and mixes thoroughly with the well-atomized fuel injected under high pressure to form a flammable fuel-air mixture. Under the action of high temperature and high pressure, it spontaneously combusts, forming a high-temperature and high-pressure gas that expands rapidly, generating a huge thrust to drive the piston to reciprocate and do work. This converts the chemical energy of the fuel into the mechanical energy of the piston, which in turn drives the connecting rod to drive the crankshaft to rotate, thereby enabling the diesel engine to continuously output power.

[0003] Currently, with the rapid development of diesel engine technology and continuous improvement in performance indicators, the combustion pressure of diesel engines has reached 22 MPa. As a core component of diesel engines, the throat temperature of the piston's combustion chamber has gradually increased from 350℃ to nearly 400℃. At this temperature, aluminum-silicon eutectic alloys, currently the mainstream material for diesel engine pistons, soften significantly and are highly susceptible to failure modes such as high-temperature fatigue cracking, greatly reducing the reliability and service life of the piston.

[0004] To improve the reliability and service life of diesel engine pistons and meet the requirements of diesel engine technology development, while maintaining the characteristics of low density and light weight of aluminum alloy materials, domestic and foreign piston companies have successively developed an extruded cast aluminum alloy piston with ceramic fiber preforms embedded in key parts such as the combustion chamber throat of the diesel engine piston, also known as a combustion chamber throat ceramic fiber reinforced aluminum piston.

[0005] The manufacturing process of this piston is as follows: ① The high-temperature baked ceramic fiber preform is placed in a predetermined position within the cavity of the casting mold; ② The mold is closed, the extrusion casting machine is turned on, and molten aluminum is poured into the mold cavity; ③ Under the action of the extrusion casting machine, the mold begins to transfer pressure to the high-temperature molten aluminum, forcing the molten aluminum to complete the filling and solidify in the gaps of the ceramic fiber preform, thereby achieving a good metallurgical bond between the molten aluminum and the ceramic fiber preform; ④ After solidification, the mold is opened, the part is removed, and quenching is performed to complete the manufacturing of the ceramic fiber reinforced aluminum piston blank; ⑤ Finally, the finished ceramic fiber reinforced aluminum piston for the combustion chamber throat is manufactured through heat treatment, machining, and surface treatment. The combustion chamber throat ceramic fiber reinforced aluminum piston product manufactured by the above extrusion casting method incorporates high-temperature resistant, spatially interwoven ceramic fibers in the highest temperature areas of the piston, such as the combustion chamber throat. Under temperatures approaching 400℃, this effectively inhibits the damage caused by the softening of the aluminum matrix, improves the high-temperature fatigue crack resistance of the diesel engine piston, and enhances the piston's reliability and service life.

[0006] The ceramic fiber reinforced aluminum piston for the combustion chamber throat produced by the above-mentioned extrusion casting method can greatly improve the high-temperature fatigue crack resistance of diesel engine pistons and improve the reliability and service life of pistons. However, its biggest drawback is that the manufacturing process is complex and the manufacturing cost is extremely high, which is nearly three times that of ordinary metal mold gravity casting diesel engine pistons. Summary of the Invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a diesel engine piston and its mold, casting method and diesel engine piston casting machine. The method provided by the present invention can produce a high-temperature resistant and long-life diesel engine piston. The method is simple and low in cost.

[0008] This invention provides a method for casting a diesel engine piston, comprising: pouring molten aluminum into a diesel engine piston mold, and cooling it in the order of inner mold, pin, outer mold and mold cover to obtain a diesel engine piston.

[0009] Since current diesel engine aluminum pistons are typically made by gravity casting using Al-12Si-5Cu-2Ni-1Mg aluminum-silicon eutectic alloy, this invention employs a rapid cooling casting method. It also optimizes the structure and function of the gravity casting mold and casting equipment, primarily by increasing the mold's cooling capacity, improving the solidification rate of molten aluminum in the mold cavity, and cooling according to a specific cooling sequence to ensure the realization of this rapid cooling casting method.

[0010] In some embodiments of the present invention, molten aluminum is poured into a diesel engine piston mold, the temperature of which is 720°C to 780°C, preferably 740°C to 760°C. In some embodiments of the present invention, cooling is performed in the order of inner mold, pin, outer mold, and mold cover, using cooling water at a temperature of 20°C to 25°C, preferably 22°C; the pressure of the cooling water is 6MPa to 8MPa, preferably 8MPa; and the flow rate of the cooling water is 4L / min to 8L / min, preferably 6L / min. In some embodiments of the present invention, during the cooling process, the temperature of the inner mold does not exceed 250°C, the temperature of the outer mold does not exceed 280°C, the temperature of the pin does not exceed 200°C, and the temperature of the mold cover does not exceed 120°C.

[0011] The present invention cools the inner mold, pin core, outer mold and mold cover in sequence. Specifically, the inner cavity of the cooling piston blank, the pin hole of the cooling piston blank, the outer circle of the cooling piston head, the combustion chamber of the cooling piston blank head, the throat of the combustion chamber of the cooling piston blank head and the gate of the cooling piston blank in the diesel engine piston mold are cooled in sequence.

[0012] The cooling piston blank inner cavity of the diesel engine piston mold of the present invention includes a first cooling piston blank inner cavity, a second cooling piston blank inner cavity, and a third cooling piston blank inner cavity. The first, second, and third inner cavities constitute the entire cooling piston blank inner cavity. The three cavities are not isolated from each other, but are separated by a distance. The first inner cavity is located in the middle of the entire cavity, and the second and third inner cavities are located side by side on the outer sides of the first inner cavity. The distance between the second and first inner cavities and the distance between the third and first inner cavities are equal or unequal, preferably equal. When cooling the cooling piston blank inner cavity in the mold, the first inner cavity is cooled first, and then the second and third inner cavities are cooled simultaneously.

[0013] The cooling piston blank pin hole portion in the diesel engine piston mold of the present invention includes a first cooling piston blank pin hole portion and a second cooling piston blank pin hole portion; the first pin hole portion and the second pin hole portion form the whole of the cooling piston blank pin hole, and the two are not isolated from each other, but only have a distance difference between them; when cooling the cooling piston blank pin hole portion in the mold, specifically the first pin hole portion and the second pin hole portion are cooled simultaneously.

[0014] The cooling piston head outer circle portion in the diesel engine piston mold of the present invention includes a first cooling piston head outer circle portion and a second cooling piston head outer circle portion; the first outer circle portion and the second outer circle portion form the whole of the cooling piston head outer circle, and the two are not isolated from each other, but only have a distance difference between them; when cooling the cooling piston head outer circle portion in the mold, specifically the first outer circle portion and the second outer circle portion are cooled simultaneously.

[0015] The diesel engine piston mold of the present invention includes a first part and a second part of the cooling piston blank head combustion chamber. The first part and the second part of the combustion chamber form the whole of the cooling piston blank head combustion chamber. They are not isolated from each other, but are separated by a distance. The first part of the combustion chamber is outside the second part of the combustion chamber and mainly cools the part of the piston head near the edge. The second part of the combustion chamber is located between the first part of the combustion chamber and the throat part of the combustion chamber, preferably in the middle. When cooling the cooling piston blank head combustion chamber in the mold, the first part and the second part of the combustion chamber are cooled simultaneously.

[0016] The combustion chamber throat portion of the cooling piston blank head in the diesel engine piston mold of the present invention is actually part of the combustion chamber portion of the aforementioned cooling piston blank head; after cooling the first and second combustion chamber portions, the combustion chamber throat portion of the cooling piston blank head is specifically cooled.

[0017] The cooling piston blank gate portion in the diesel engine piston mold of the present invention includes a first cooling piston blank gate portion and a second cooling piston blank gate portion; the first gate portion and the second gate portion constitute the entire cooling piston blank gate, and the two are not isolated from each other, but are separated by a distance; when cooling the cooling piston blank gate portion in the mold, specifically the first gate portion and the second gate portion are cooled simultaneously.

[0018] In some embodiments of the present invention, cooling is performed in the order of inner mold, pin, outer mold, and mold cover. Specifically, the first part of the inner cavity of the cooling piston blank is cooled for 80-90 seconds; after a 5-10 second delay, the second and third parts of the inner cavity of the cooling piston blank are cooled for 30-40 seconds; after a 10-15 second delay, the pin hole of the cooling piston blank is cooled for 70-75 seconds; and after a 20-25 second delay, the outer part of the cooling piston head is cooled. The circular portion is cooled for 60-65 seconds; after a 20-30 second delay, the first part of the combustion chamber at the head of the cooling piston blank is cooled for 60-65 seconds; after a 30-35 second delay, the second part of the combustion chamber at the head of the cooling piston blank is cooled for 55-60 seconds; after a 35-40 second delay, the throat part of the combustion chamber at the head of the cooling piston blank is cooled for 50-55 seconds; after a 55-65 second delay, the gate part of the cooling piston blank is cooled for 20-30 seconds. This invention allows for fine-tuning of the water cooling time based on the temperature of each part of the mold, namely the inner mold, pin, outer mold, and mold cover. If the mold temperature is high, the water cooling time is appropriately extended; if the mold temperature is low, the water cooling time is appropriately shortened.

[0019] After cooling the combustion chamber throat area of ​​the piston blank head, the solidification rate of the combustion chamber throat area begins to increase. By controlling the solidification time and the temperature of the combustion chamber throat area, the material properties of the combustion chamber throat area of ​​the final piston can be improved. In some embodiments of the present invention, the solidification time of the combustion chamber throat area is less than 40 seconds; the temperature of the combustion chamber throat area is below 500°C.

[0020] The present invention further includes mold opening and quenching after cooling. Mold opening is the waiting step before quenching; the faster the mold opening, the better, depending on the equipment capacity, generally less than 10 seconds. Quenching is performed using water above 45°C, and the quenching transfer time is less than 10 seconds. The diesel engine piston casting method provided by this invention is applicable to casting cylinder diameters ranging from... For diesel engine pistons, the preferred cylinder diameter range is [range missing].

[0021] In some embodiments of the present invention, the diesel engine piston obtained by the above casting method has a cylinder diameter ranging from [specific range]. Between, the preferred cylinder diameter range is In one embodiment, the matrix structure of the combustion chamber throat portion of the diesel engine piston obtained by the above casting method includes bulk primary Si with a grain size of less than 30 μm, rod-shaped or short rod-shaped eutectic Si, α-Al dendrites, elongated skeletal intermetallic compounds, bulk skeletal intermetallic compounds, and skeletal intermetallic compounds; the intermetallic compounds include Al2Cu, Al7Cu4Ni, Al3CuNi, and Al5Cu2Mg8Si6.

[0022] The present invention also provides a diesel engine piston mold, comprising a mold body and a cooling water channel disposed in the mold body, the cooling water channel comprising:

[0023] Cooling water channels for cooling the first part of the inner cavity of the piston blank; cooling water channels for cooling the second part of the inner cavity of the piston blank; cooling water channels for cooling the third part of the inner cavity of the piston blank; cooling water channels for cooling the pin hole of the piston blank; cooling water channels for cooling the outer circle of the piston head; cooling water channels for cooling the first part of the combustion chamber of the piston head; cooling water channels for cooling the second part of the combustion chamber of the piston head; cooling water channels for cooling the throat of the combustion chamber of the piston head; and cooling water channels for cooling the gate of the piston blank.

[0024] The positional relationship between the cooling water channels for cooling the first, second, and third portions of the piston blank inner cavity, as described in this invention, is as follows: the first, second, and third cooling water channels are all arranged side-by-side along the long axis of the piston blank inner cavity, wherein the second and third cooling water channels are arranged at equal distances from the first cooling water channel. The distances between the two sides of the unequal distance and the first cooling water passage in the inner cavity can be equal or adjusted to be unequal according to the actual situation, preferably equal; the positional relationship between the cooling water passage for cooling the first part of the combustion chamber of the piston blank head and the cooling water passage for cooling the second part of the combustion chamber of the piston blank head is as follows: the first cooling water passage of the combustion chamber is outside the second cooling water passage of the combustion chamber, mainly cooling the part of the piston head near the edge; the second cooling water passage of the combustion chamber is located between the first cooling water passage of the combustion chamber and the cooling water passage of the combustion chamber throat, preferably in the middle position. The cylinder diameter range of the diesel engine piston mold of the present invention is within Between, the preferred cylinder diameter range is

[0025] This invention also provides a diesel engine piston casting machine, including a casting machine body and the aforementioned diesel engine piston mold. The diesel engine piston casting machine of this invention increases the number of cooling water channels from the existing 6 channels to more than 12 channels, corresponding to the cooling water channels of the aforementioned diesel engine piston mold; in fact, compared with the existing mold, the cooling water channels of the aforementioned diesel engine piston mold are also increased from 6 channels to more than 12 channels. This increases the cooling capacity of the mold and the casting machine, improves the solidification rate of the aluminum liquid in the mold cavity, and enables cooling to be carried out according to a specific cooling sequence during actual operation, thereby ensuring the realization of the casting method described in this invention.

[0026] This invention provides a casting method for diesel engine pistons, comprising: pouring molten aluminum into a diesel engine piston mold, and cooling it in the order of inner mold, pin, outer mold, and mold cover to obtain the diesel engine piston. The method provided by this invention can produce high-temperature resistant, long-life diesel engine pistons; the method is simple and low-cost. The casting method described in this invention fully utilizes the casting microstructure and chemical phase types of Al-12Si-5Cu-2Ni-1Mg aluminum-silicon eutectic alloy, a commonly used piston material for diesel engine aluminum pistons. By optimizing casting equipment and molds, the morphology and distribution of the casting microstructure within the material are realized. In particular, the high-temperature intermetallic compounds (Al7Cu4Ni, Al3CuNi, and Al5Cu2Mg8Si6) that are continuously distributed in a spatial network within the alloy matrix play a role similar to the spatially interwoven ceramic fibers in ceramic fiber reinforced pistons. This effectively inhibits the damage caused by the softening of the aluminum matrix, improves the high-temperature fatigue crack resistance of diesel engine pistons, enhances the reliability and service life of pistons, and reduces the manufacturing cost of such high-performance diesel engine pistons. The cost of diesel engine pistons manufactured by this rapid cooling casting method is comparable to that of current diesel engine pistons and is about one-third the cost of extrusion-cast combustion chamber ceramic fiber reinforced diesel engine pistons. Experiments show that, without changing the piston matrix material, this invention successfully obtained a low-cost diesel engine piston with high reliability and long service life, which can be used well at high temperatures of nearly 400°C, using the currently mainstream metal mold gravity casting method. Attached Figure Description

[0027] Figure 1 This is a front view of the diesel piston casting machine used in Example 1;

[0028] Figure 2 This is a top view of the diesel piston casting machine used in Example 1;

[0029] Figure 3 This is a rear view of the diesel piston casting machine used in Example 1;

[0030] Figure 4 This is a schematic diagram of a metal mold.

[0031] Figure 5 Schematic diagram of the cooling area at the throat of the combustion chamber;

[0032] Figure 6 This is one of the metallographic structures of the throat region of the diesel engine piston combustion chamber obtained in Example 1;

[0033] Figure 7 The second image shows the metallographic structure of the throat region of the diesel engine piston combustion chamber obtained in Example 1.

[0034] Figure 8 The graph shows the fatigue failure cycle test results of the piston casting produced by the casting method of this invention. Detailed Implementation

[0035] This invention discloses a diesel engine piston, its mold, casting method, and a diesel engine piston casting machine. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0036] This invention more than doubles the cooling water routes of the current diesel engine piston casting machine and metal mold from the original 6 routes to more than 12 routes. Figures 1-3 As shown, Figure 1 This is a front view of the diesel piston casting machine used in Example 1; Figure 2 This is a top view of the diesel piston casting machine used in Example 1; Figure 3 This is a rear view of the diesel piston casting machine used in Example 1; Figures 1-3 In This refers to the cooling water channels for various parts of the metal mold corresponding to the diesel engine piston casting machine. Figure 4 This is a schematic diagram of a metal mold. Figure 4 In These are the various parts of the metal mold, where ① to ③ are the inner cavity of the cooling piston blank in the metal mold, ④ to ⑤ are the pin holes of the cooling piston blank, ⑥ to ⑦ are the head combustion chamber of the cooling piston blank, ⑧ is the throat of the head combustion chamber of the cooling piston blank, and ⑨ to ⑩ are the outer circle of the cooling piston head. The gate area is used to cool the piston blank.

[0037] This invention involves pouring molten aluminum into a metal mold and casting it using a diesel engine piston casting machine, wherein the temperature of the poured molten aluminum is controlled at 760±10℃. Water is supplied to each cooling water channel of the diesel engine piston casting machine to cool each part of the metal mold. The water cooling sequence for each part of the metal mold is: inner mold → pin → outer mold → mold cover, specifically:

[0038] The present invention will be further described below with reference to the embodiments:

[0039] Example 1

[0040] Molten aluminum is poured into the aforementioned metal mold, and a Φ120mm~Φ130mm aluminum piston is cast using the aforementioned diesel engine piston casting machine. After the molten aluminum is poured, water is supplied to the casting machine's cooling water channel ① for 90 seconds; after a 10-second delay, water is supplied to the casting machine's cooling water channels ② and ③ for 40 seconds; after a 15-second delay, water is supplied to the casting machine's cooling water channels ④ and ⑤ for 75 seconds; after a 25-second delay, water is supplied to the casting machine's cooling water channels ⑨ and ⑩ for 65 seconds; after a 30-second delay, water is supplied to the casting machine's cooling water channel ⑥ for 65 seconds; after a 35-second delay, water is supplied to the casting machine's cooling water channel ⑦ for 60 seconds; after a 40-second delay, water is supplied to the casting machine's cooling water channel ⑧ for 55 seconds; after a 65-second delay, water is supplied to the casting machine's cooling water channel ⑨ for 65 seconds. and cooling water circuit Water flow for 30 seconds.

[0041] In this embodiment, the cooling water temperature is 22℃, the cooling water pressure is controlled at 8MPa, and the cooling water flow rate of each cooling water path is controlled at 6L / min. Throughout the solidification process in this embodiment, the inner mold temperature does not exceed 250℃, the outer mold temperature does not exceed 280℃, the pin core mold temperature does not exceed 200℃, and the mold cover temperature does not exceed 120℃. The water cooling time for each part is finely adjusted according to the temperature of each part of the mold; if the mold temperature is high, the water cooling time is appropriately extended; if the mold temperature is low, the water cooling time is appropriately shortened. During the entire solidification process of the blank, the solidification time of the combustion chamber throat area (⑧ the cooling area) is <40 seconds, and the temperature does not exceed 500℃. Figure 5 As shown, Figure 5 This is a schematic diagram of the cooling area at the throat of the combustion chamber.

[0042] After water cooling is completed, the mold is opened (solidified), and the mold opening time is ≤10 seconds; then quenching is performed, with the quenching water temperature ≥45℃ and the quenching transfer time <10 seconds; finally, the diesel engine piston of the present invention is obtained.

[0043] Example 2

[0044] The matrix microstructure of the diesel engine piston obtained in Example 1 mainly comprises bulk primary Si ≤30 μm, rod-shaped or short rod-shaped eutectic Si, α-Al dendrites, and elongated, bulk, and skeletal intermetallic compounds. The main intermetallic compounds are Al2Cu, Al7Cu4Ni, Al3CuNi, and Al5Cu2Mg8Si6. These intermetallic compounds, when observed under a backscattered electron microscope, show the following characteristics: Figures 6-7 As shown, Figure 6 This is one of the metallographic structures of the throat region of the diesel engine piston combustion chamber obtained in Example 1. Figure 7 Figure 2 shows the metallographic structure of the combustion chamber throat region of the diesel engine piston obtained in Example 1; it is distributed continuously in a large-area spatial network within the alloy matrix. These intermetallic compounds (Al7Cu4Ni, Al3CuNi, and Al5Cu2Mg8Si6) distributed continuously in the alloy matrix in a spatial network exhibit strong thermal stability below 400℃, effectively inhibiting grain boundary slippage at high temperatures, similar to the effect of interwoven ceramic fibers in a ceramic fiber reinforced piston. This effectively inhibits the damage caused by the softening of the aluminum matrix, improves the high-temperature fatigue crack resistance of the diesel engine piston, and enhances the piston's reliability and service life. Within a temperature oscillation range of 100℃ to 350℃, under fully axially constrained conditions, samples of the piston casting produced by the casting method of this invention were subjected to fatigue failure cycle tests. Figure 8 As shown, Figure 8 The figure shows the fatigue failure cycle test results of the piston casting produced by the casting method of this invention. The results indicate that the fatigue failure cycle count of the piston casting produced by the casting method of this invention is approximately 1.4 times that of the casting produced by conventional casting methods. The diesel engine piston obtained in Example 1 meets the reliability and life requirements for a diesel engine piston made of aluminum-silicon eutectic alloy using a metal mold with a combustion pressure ≤22MPa and a combustion chamber throat temperature close to 400℃.

[0045] Therefore, this invention, based on the current diesel engine combustion pressure below 22MPa, improves the high-temperature fatigue performance of the alloy material by using a rapid cooling casting method combined with changes in the internal structure of the alloy material without changing the aluminum-silicon eutectic alloy material of the diesel engine piston. This results in a high-performance diesel engine piston that meets the requirements for improving current diesel engine combustion pressure and other strengthening indicators, thereby improving the piston's reliability and service life.

[0046] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for casting a diesel engine piston, based on a diesel engine piston mold, the diesel engine piston mold comprising a mold body and cooling water channels disposed in the mold body, the cooling water channels comprising: The first cooling water passage in the inner cavity is used to cool the first part of the inner cavity of the piston blank; The second cooling water passage in the inner cavity is used to cool the second part of the inner cavity of the piston blank. The third cooling water passage in the inner cavity is used to cool the third part of the piston blank's inner cavity; Cooling water passage for the pin hole of the piston blank; The outer circumference cooling water passage is used to cool the outer circumference of the piston head. The first cooling water passage for the combustion chamber is used to cool the first part of the combustion chamber at the head of the piston blank. The second cooling water passage for the combustion chamber is used to cool the second part of the combustion chamber at the head of the piston blank; The throat cooling water passage is used to cool the throat area of ​​the combustion chamber at the head of the piston blank. and A gate cooling water channel for cooling the gate area of ​​the piston blank; The positional relationship between the first, second, and third cooling water passages in the inner cavity is as follows: the first, second, and third cooling water passages are all arranged side by side along the long axis of the inner cavity of the piston blank, wherein the second and third cooling water passages in the inner cavity are arranged on both sides of the first cooling water passage in the inner cavity at equal or unequal distances. The positional relationship between the first cooling water passage and the second cooling water passage of the combustion chamber is as follows: the first cooling water passage of the combustion chamber is outside the second cooling water passage of the combustion chamber; the second cooling water passage of the combustion chamber is located between the first cooling water passage of the combustion chamber and the throat cooling water passage of the combustion chamber. The casting method is characterized by comprising: The molten aluminum is poured into a diesel engine piston mold and cooled in the order of inner mold, pin, outer mold and mold cover to obtain the diesel engine piston. Cooling is performed in the following order: inner mold, pin, outer mold, and mold cover. The inner cavity of the cooling piston blank, the pin hole of the cooling piston blank, the outer circle of the cooling piston head, the combustion chamber of the cooling piston blank head, the throat of the combustion chamber of the cooling piston blank head, and the gate of the cooling piston blank in the diesel engine piston mold are cooled sequentially. Cool the first part of the inner cavity of the cooling piston blank for 80-90 seconds; After a delay of 5 to 10 seconds, cool the second part of the inner cavity of the cooling piston blank and the third part of the inner cavity of the cooling piston blank for 30 to 40 seconds. After a delay of 10 to 15 seconds, cool the pin hole area of ​​the cooling piston blank for 70 to 75 seconds. After a delay of 20-25 seconds, cool the outer diameter of the cooling piston head for 60-65 seconds. After a delay of 20 to 30 seconds, the first part of the combustion chamber at the head of the cooling piston blank is cooled for 60 to 65 seconds. After a delay of 30-35 seconds, the second part of the combustion chamber at the head of the cooling piston blank is cooled for 55-60 seconds. After a delay of 35 to 40 seconds, the throat area of ​​the combustion chamber at the head of the cooling piston blank is cooled for 50 to 55 seconds. After a delay of 55-65 seconds, the gate area of ​​the cooling piston blank is cooled for 20-30 seconds. The solidification time at the throat of the combustion chamber is less than 40 seconds; The temperature at the throat of the combustion chamber is below 500°C.

2. The method according to claim 1, characterized in that, During the cooling process, the temperature of the inner mold does not exceed 250°C, the temperature of the outer mold does not exceed 280°C, the temperature of the pin does not exceed 200°C, and the temperature of the mold cover does not exceed 120°C.

3. The method according to claim 1, characterized in that, The temperature of the molten aluminum is 720℃~780℃.

4. The method according to claim 1, characterized in that, The cooling is performed using cooling water, and the temperature of the cooling water is 20℃~25℃. The pressure of the cooling water is 6 MPa to 8 MPa; The flow rate of the cooling water is 4 L / min to 8 L / min.

5. The method according to claim 1, characterized in that, After cooling, the process also includes mold opening and quenching, with the mold opening time being less than 10 seconds. The quenching is performed using water at a temperature above 45°C, and the quenching transfer time is less than 10 seconds.

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