Composite piston, piston forming device and forming method
By inserting steel backing sleeves and prefabricated reinforcements into the pin seat holes of the internal combustion engine piston, and immersing the aluminum liquid into the prefabricated reinforcements during the molding process, forming a gradient structure with a decrease in thermal expansion coefficient, the problem of insufficient load-bearing capacity of the piston pin seat is solved, and the reliability and cost-effectiveness of the piston are improved.
Patent Information
- Application Number
- CN202311650993.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-04
- Publication Date
- 2025-06-06
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Under high explosive pressure, the pin seat load-bearing capacity of the existing internal combustion engine pistons is insufficient, resulting in cracking and failure of the copper sleeve and pin seat, increasing the major failure risk of the cylinder liner and cylinder block.
The composite piston design is adopted, and the aluminum piston body is equipped with pin seat holes, a steel backing sleeve and prefabricated reinforcement are embedded. The liquid aluminum is impregnated into the prefabricated reinforcement during the molding process, forming a gradient structure with a decrease in thermal expansion coefficient.
It improves the load-bearing capacity and reliability of the piston, reduces the stress risk caused by thermal expansion of the steel backing sleeve and aluminum piston body, and the cost is lower than that of traditional copper sleeves.
Smart Images
Figure CN120100598A_ABST
Abstract
Description
Technical Field
[0001] The present invention mainly relates to the technical field of internal combustion engine pistons, and in particular to a composite piston, a piston molding device and a molding method. Background Art
[0002] The piston is an important component of the internal combustion engine. Aluminum alloy pistons are widely used due to their light weight and small inertia. When the piston is working, the piston pin seat hole is subjected to a large alternating load. In order to prevent the pin seat from cracking and improve the bearing capacity of the pin seat, inlaying a copper sleeve in the pin seat hole has become an important process method, and the inlaying of copper sleeves in the pin seat hole of the aluminum matrix is relatively mature, but the aluminum piston pin seat and the copper sleeve are easy to deform. As the explosion pressure of the internal combustion engine further increases, higher requirements are placed on the bearing capacity of the pin seat. The risk of major failures such as damage to the cylinder liner and cylinder body due to cracking and failure of the copper sleeve and pin seat is further increased. Summary of the invention
[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a composite piston, a piston molding device and a molding method with strong load-bearing capacity, good reliability and low cost.
[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:
[0005] A composite piston comprises an aluminum piston body, wherein a pin seat hole is formed on the aluminum piston body, a steel back bushing is arranged in the pin seat hole, a prefabricated reinforcement part is embedded between the pin seat hole and the steel back bushing, and when the aluminum piston body is formed, aluminum liquid infiltrates into the prefabricated reinforcement part so that the thermal expansion coefficient from the aluminum piston body to the steel back bushing forms a gradual decrease.
[0006] As a further improvement of the above technical solution:
[0007] The prefabricated reinforcement comprises a metal frame, a prefabricated part and a positioning assembly. The prefabricated part is sleeved on the outer wall of the metal frame along the circumferential direction of the metal frame. A connecting seat is formed on the metal frame. The positioning assembly is fixed on the connecting seat and embedded in the aluminum piston body.
[0008] The preform is a ceramic fiber composed of aluminum borate fiber filaments or magnesium borate fiber filaments. When the aluminum piston body is formed, the aluminum liquid infiltrates into the ceramic fiber to form a ceramic-reinforced aluminum-based composite material.
[0009] The positioning assembly includes a positioning plate, connecting bolts and nuts. The positioning plate is embedded in the aluminum piston body and is tightly attached to the connecting seat. The connecting bolts penetrate the positioning plate and the connecting seat and are locked and fixed by nuts.
[0010] A forming device for a composite piston comprises a movable die, an extrusion-casting punch, a fixed die and an injection assembly. During forming, the movable die and the extrusion-casting punch move downward and enclose the fixed die to form a cavity matching the shape of the composite piston. The injection assembly is arranged below the fixed die and pressurizes aluminum fluid into the cavity to form the composite piston. The fixed die is provided with a reusable guide piece for facilitating separation of the material handle of the composite piston from the aluminum piston body after forming.
[0011] As a further improvement of the above technical solution:
[0012] The flow guide is embedded in the fixed mold, and a through hole is provided on the flow guide which is perpendicular to the parting surface of the cavity and serves as a central gate.
[0013] The injection assembly comprises a barrel, which is inside the fixed die and connected to the cavity through the through hole. An injection punch for injecting aluminum liquid from the through hole into the cavity is arranged inside the barrel.
[0014] The through hole is configured as a variable diameter structure with a small middle and large ends, a groove is formed in the middle of the through hole, and a clamping ring is installed in the groove to form a boundary flange between the material handle and the aluminum piston body after molding.
[0015] The extrusion casting punch and the guide piece are provided with inserting holes for positioning and installing the inlays of the composite piston.
[0016] A method for forming a composite piston, using the above-mentioned forming device for extrusion casting, comprises the following steps:
[0017] S1: preheat the movable die, extrusion casting punch and fixed die, then install the guide piece on the fixed die and spray the release agent;
[0018] S2: Position and install the insert through the extrusion punch and the socket on the guide piece;
[0019] S3: The movable mold and the extrusion casting punch move downward and close together with the fixed mold to form a cavity;
[0020] S4: Add aluminum liquid into the barrel, and inject the aluminum liquid from the through hole into the cavity through the injection punch, and pressurize at a low speed to form a composite piston casting;
[0021] S5: The movable die and the extrusion punch move up, and the injection punch pushes the material handle, the guide piece and the composite piston casting to move up together and separate from the fixed die;
[0022] S6: Drill and mill the material handle, cut off the connection between the material handle and the aluminum piston body at the clamping ring, and then separate the aluminum piston body, the material handle and the guide piece.
[0023] Compared with the prior art, the advantages of the present invention are:
[0024] Compared with the traditional aluminum alloy piston, the composite piston of the present invention has a steel back bushing arranged in the pin seat hole and a prefabricated reinforcement part embedded between the pin seat hole and the steel back bushing. In this structure, the cost of the steel back bushing is lower than that of the copper bushing and the bearing capacity is stronger. When the aluminum piston body is formed, aluminum liquid is infiltrated into the prefabricated reinforcement part, so that a gradient structure with a decreasing thermal expansion coefficient is formed between the aluminum piston body and the steel back bushing. This can effectively eliminate the stress stress risk caused by thermal expansion between the steel back bushing and the aluminum piston body during the operation of the piston and has good reliability.
[0025] The composite piston molding device of the present invention, during molding, the movable mold and the extrusion casting punch move downward to enclose a mold cavity with the fixed mold, and aluminum fluid is hydraulically injected into the mold cavity through the injection assembly to form a composite piston casting. Compared with the traditional molding device, a guide piece is provided on the fixed mold, and the guide piece is integrally formed with the composite piston casting during extrusion casting, and a material handle is formed between the injection assembly and the guide piece. Mechanical processing is used to separate the material handle, the aluminum piston body and the guide piece at the guide piece, which is easy to operate and the guide piece can be reused.
[0026] The molding method of the composite piston of the present invention comprises the following steps: after the mold is closed to form a cavity, aluminum liquid is injected from a barrel through a through hole into the cavity at a low speed by an injection punch, so that the aluminum liquid fills the cavity at a low speed, which can reduce the erosion of the surface of each inlaid component by the aluminum liquid and improve the molding quality of the composite piston. The pressure of the injection punch is transmitted to the aluminum liquid in the cavity through the through hole, and then pressure is applied to compensate for shrinkage, so that the composite piston casting forms a better dense metal structure. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 It is a structural schematic diagram of the composite piston of the present invention.
[0028] Figure 2 It is a schematic diagram of the structure of the prefabricated reinforcement member of the present invention.
[0029] Figure 3 It is a schematic diagram of the metal skeleton structure of the present invention.
[0030] Figure 4 It is a schematic diagram of the structure of the molding device of the present invention (before molding).
[0031] Figure 5 It is a schematic diagram of the structure of the molding device of the present invention (after molding).
[0032] Figure 6 It is a schematic diagram of the structure of the flow guide member of the present invention.
[0033] The symbols in the figure represent:
[0034] 1. Aluminum piston body; 11. Pin seat hole; 12. Material handle; 2. Prefabricated reinforcement; 21. Metal skeleton; 211. Connecting seat; 22. Prefabricated part; 23. Positioning assembly; 231. Positioning plate; 232. Connecting bolt; 233. Nut; 3. Steel backing bushing; 4. Moving mold; 5. Extrusion punch; 6. Fixed mold; 7. Injection assembly; 71. Material barrel; 72. Injection punch; 8. Cavity; 9. Guide piece; 91. Through hole; 92. Snap ring. DETAILED DESCRIPTION
[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0036] like Figures 1 to 3 As shown, the composite piston of this embodiment includes an aluminum piston body 1, a pin seat hole 11 is provided on the aluminum piston body 1, a steel back bushing 3 is provided in the pin seat hole 11, a prefabricated reinforcement 2 is embedded between the pin seat hole 11 and the steel back bushing 3, and when the aluminum piston body 1 is formed, its aluminum liquid infiltrates into the prefabricated reinforcement 2 so that the thermal expansion coefficient from the aluminum piston body 1 to the steel back bushing 3 forms a gradual and gradually decreasing type. Compared with the traditional aluminum alloy piston, the present invention arranges the steel back bushing 3 in the pin seat hole 11, and embeds the prefabricated reinforcement 2 between the pin seat hole 11 and the steel back bushing 3. In this structure, the cost of the steel back bushing 3 is lower than that of the copper sleeve, and the bearing capacity is stronger. When the aluminum piston body 1 is formed, the aluminum liquid infiltrates into the prefabricated reinforcement 2, so that the thermal expansion coefficient of the aluminum piston body 1 and the steel back bushing 3 The gradient structure of decreasing is formed, which can effectively resolve the stress risk caused by thermal expansion of the steel back bushing 3 and the aluminum piston body 1 during the operation of the piston, and has good reliability.
[0037] In this embodiment, a gradient structure with decreasing thermal conductivity is formed between the aluminum piston body 1 and the steel backing bushing 3, which can effectively reduce the temperature of the piston pin during the use of the piston and improve the lubrication condition of the piston pin.
[0038] In this embodiment, a gradient structure with increasing strength is formed between the aluminum piston body 1 and the steel backing bushing 3, which can effectively release the impact stress of the cylinder on the piston and improve the stress condition of the piston body.
[0039] In this embodiment, the prefabricated reinforcement 2 includes a metal skeleton 21, a prefabricated part 22 and a positioning assembly 23. The prefabricated part 22 is sleeved on the outer wall of the metal skeleton 21 along the circumferential direction of the metal skeleton 21. A connecting seat 211 is formed on the metal skeleton 21. The positioning assembly 23 is fixed on the connecting seat 211 and embedded in the aluminum piston body 1. In this structure, the metal skeleton 21 is an austenite structure, the prefabricated part 22 is coated on the circumferential outer wall of the metal skeleton 21, and the metal skeleton 21 is positioned and installed on the aluminum piston body 1 through the positioning assemblies 23 at both ends. It has a simple structure and is easy to position and install.
[0040] In this embodiment, the preform 22 is a ceramic fiber composed of aluminum borate fiber filaments, and the aluminum liquid infiltrates into the ceramic fiber to form a ceramic reinforced aluminum-based composite material when the aluminum piston body 1 is formed. In other embodiments, the preform 22 can also be set as a ceramic preform composed of magnesium borate fiber filaments, and the aluminum liquid infiltrates into the ceramic fiber to form a ceramic reinforced aluminum-based composite material when the aluminum piston body 1 is formed, thereby improving its strength and further improving the bearing capacity of the pin seat hole 11.
[0041] In this embodiment, the positioning assembly 23 includes a positioning plate 231, a connecting bolt 232 and a nut 233. The positioning plate 231 is embedded in the aluminum piston body 1 and is tightly attached to the connecting seat 211. The connecting bolt 232 is passed through the positioning plate 231 and the connecting seat 211 and is locked and fixed by the nut 233. The structure is simple, and the bolt connection is firm and convenient.
[0042] like Figures 4 to 6 As shown, the forming device of the composite piston of this embodiment includes a movable mold 4, an extrusion casting punch 5, a fixed mold 6 and an injection assembly 7. During molding, the movable mold 4 and the extrusion casting punch 5 move downward and enclose the fixed mold 6 to form a cavity 8 matching the shape of the composite piston. The injection assembly 7 is arranged below the fixed mold 6 and hydraulically injects aluminum into the cavity 8 to pressurize and form a composite piston. The fixed mold 6 is provided with a reusable guide member 9 for facilitating the separation of the material handle 12 of the composite piston from the aluminum piston body 1 after the composite piston is formed. During molding, the movable mold 4 and the extrusion casting punch 5 move downward to enclose the fixed mold 6 to form a cavity 8, and the aluminum fluid is hydraulically injected into the cavity 8 through the injection assembly 7 to form a composite piston casting. Compared with the traditional molding device, a guide member 9 is provided on the fixed mold 6. The guide member 9 is integrally formed with the composite piston casting during extrusion casting, and a material handle 12 is formed between the injection assembly 7 and the guide member 9. The material handle 12, the aluminum piston body 1 and the guide member 9 are separated at the guide member 9 by mechanical processing. The operation is convenient and the guide member 9 can be reused.
[0043] In this embodiment, the guide member 9 is embedded in the fixed mold 6, and a through hole 91 is provided on the guide member 9, which is perpendicular to the parting surface of the cavity 8 and serves as a central gate. In this structure, the through hole 91 is provided on the guide member 9 as the central gate, so that the filling distance of the aluminum liquid in the cavity 8 is short during extrusion casting, which facilitates the filling, slag removal, exhaust and sequential solidification of the cavity 8.
[0044] In this embodiment, the injection assembly 7 includes a barrel 71, which is in the fixed mold 6 and connected to the cavity 8 through the through hole 91. The barrel 71 is provided with an injection punch 72 for injecting the aluminum liquid from the through hole 91 into the cavity 8. In this structure, the injection punch 72 is pushed by a cylinder to inject the aluminum liquid in the barrel 71 from the through hole 91 into the cavity 8. The structure is simple, the pressure loss of the injection punch 72 is small, and the performance of the composite piston casting is balanced.
[0045] In this embodiment, the through hole 91 is set as a variable diameter structure with a small middle and large ends, a groove is formed in the middle of the through hole 91, and a snap ring 92 is installed in the groove to form a boundary flange between the material handle 12 and the aluminum piston body 1 after molding. In this structure, the through hole 91 is set as a variable diameter structure, a groove is formed in the middle and the snap ring 92 is installed, so that the snap ring 92 forms a boundary flange between the material handle 12 and the aluminum piston body 1. The snap ring 92 is a consumable part, and drilling and milling are directly performed at the snap ring 92, which is conducive to the separation of the guide member 9 and the aluminum piston body 1.
[0046] In this embodiment, the extrusion casting punch 5 and the guide member 9 are provided with insertion holes for positioning and installing each inlay of the composite piston. In this structure, the insertion holes are provided on the extrusion casting punch 5 and the guide member 9 to facilitate the positioning and installation of each inlay, and the inlay includes a core, an inlay ring, a throat prefabricated part and a prefabricated reinforcement part 2.
[0047] The forming method of the composite piston of this embodiment comprises the following steps:
[0048] S1: preheating the movable die 4, the extrusion punch 5, and the fixed die 6, then installing the guide piece 9 on the fixed die 6, and spraying a mold release agent;
[0049] S2: Positioning and installing the insert through the extrusion punch 5 and the socket on the guide member 9;
[0050] S3: The movable mold 4 and the extrusion punch 5 move downward and close together with the fixed mold 6 to form a cavity 8;
[0051] S4: adding aluminum liquid into the barrel 71, and injecting the aluminum liquid from the through hole 91 into the cavity 8 through the injection punch 72, and pressurizing at a low speed to form a composite piston casting;
[0052] S5: The movable die 4 and the extrusion punch 5 move upward, and the injection punch 72 pushes the material handle 12, the flow guide 9 and the composite piston casting to move upward together and separate from the fixed die 6;
[0053] S6: drilling and milling the material handle 12 to cut off the connection between the material handle 12 and the aluminum piston body 1 at the clamping ring 92, and then separate the aluminum piston body 1, the material handle 12 and the guide member 9.
[0054] After the mold is closed to form the cavity 8, the method uses the injection punch 72 to inject aluminum liquid from the barrel 71 through the through hole 91 into the cavity 8, and then pressurizes the composite piston casting at a low speed, so that the aluminum liquid fills the cavity 8 at a low speed, which can reduce the cracking caused by the erosion of the aluminum liquid on each embedded component and improve the molding quality of the composite piston. The pressure of the injection punch 72 is transmitted to the aluminum liquid in the cavity 8 through the through hole 91, and then pressurized to compensate for shrinkage, so that the composite piston casting forms a better dense metal structure.
[0055] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.
Claims
1. A composite piston, Features: The invention comprises an aluminum piston body (1), wherein a pin seat hole (11) is formed on the aluminum piston body (1), a steel back bushing (3) is arranged in the pin seat hole (11), a prefabricated reinforcement part (2) is embedded between the pin seat hole (11) and the steel back bushing (3), and when the aluminum piston body (1) is formed, aluminum liquid is infiltrated into the prefabricated reinforcement part (2) so that the thermal expansion coefficient from the aluminum piston body (1) to the steel back bushing (3) forms a gradual gradual decrease.
2. The composite piston according to claim 1, Features: The prefabricated reinforcement component (2) comprises a metal frame (21), a prefabricated component (22) and a positioning assembly (23); the prefabricated component (22) is sleeved on the outer wall of the metal frame (21) along the circumferential direction of the metal frame (21); a connecting seat (211) is formed on the metal frame (21); and the positioning assembly (23) is fixed on the connecting seat (211) and embedded in the aluminum piston body (1).
3. The composite piston according to claim 2, Features: The preform (22) is a ceramic fiber composed of aluminum borate fiber filaments or magnesium borate fiber filaments. When the aluminum piston body (1) is formed, aluminum liquid infiltrates into the ceramic fiber to form a ceramic-reinforced aluminum-based composite material.
4. The composite piston according to claim 2, Features: The positioning assembly (23) comprises a positioning plate (231), a connecting bolt (232) and a nut (233); the positioning plate (231) is embedded in the aluminum piston body (1) and is tightly attached to the connecting seat (211); the connecting bolt (232) passes through the positioning plate (231) and the connecting seat (211) and is locked and fixed by the nut (233).
5. A molding device for a composite piston according to any one of claims 1 to 4, Features: The invention comprises a movable die (4), an extrusion-casting punch (5), a fixed die (6) and an injection assembly (7). During molding, the movable die (4) and the extrusion-casting punch (5) move downwards and enclose the fixed die (6) to form a cavity (8) matching the shape of the composite piston. The injection assembly (7) is arranged below the fixed die (6) and injects aluminum fluid into the cavity (8) to form the composite piston under pressure. The fixed die (6) is provided with a reusable guide member (9) for facilitating the separation of the material handle (12) of the composite piston from the aluminum piston body (1) after molding.
6. The composite molding device according to claim 5, Features: The flow guide (9) is embedded in the fixed mold (6), and a through hole (91) is provided on the flow guide (9) which is perpendicular to the parting surface of the mold cavity (8) and serves as a central gate.
7. The composite molding device according to claim 6, Features: The injection assembly (7) comprises a barrel (71), wherein the barrel (71) is inside the fixed mold (6) and connected to the mold cavity (8) through the through hole (91), and an injection punch (72) is provided inside the barrel (71) for injecting aluminum liquid from the through hole (91) into the mold cavity (8).
8. The piston forming device according to claim 7, Features: The through hole (91) is configured as a variable diameter structure with a small center and large ends. A groove is formed in the middle of the through hole (91), and a clamping ring (92) is installed in the groove to form a boundary flange between the material handle (12) and the aluminum piston body (1) after molding.
9. The piston forming device according to claim 8, Features: The extrusion-casting punch (5) and the flow guide (9) are provided with insertion holes for positioning and installing the various inlays of the composite piston.
10. A method for forming a composite piston according to any one of claims 1 to 4, It is characterized in that The extrusion casting is carried out using the molding device according to any one of claims 5 to 9, comprising the following steps: S1: preheating the movable die (4), the extrusion punch (5), and the fixed die (6), then installing the guide piece (9) on the fixed die (6), and spraying a mold release agent; S2: Positioning and installing the insert through the insertion holes on the extrusion punch (5) and the guide member (9); S3: The movable mold (4) and the extrusion punch (5) move downward and close together with the fixed mold (6) to form a mold cavity (8); S4: adding aluminum liquid into the barrel (71), and injecting the aluminum liquid from the through hole (91) into the mold cavity (8) through the injection punch (72), and pressurizing at a low speed to form a composite piston casting; S5: the movable die (4) and the extrusion punch (5) move upward, and the injection punch (72) pushes the material handle (12), the flow guide (9) and the composite piston casting to move upward together and separate from the fixed die (6); S6: drilling and milling the material handle (12), cutting off the connection between the material handle (12) and the aluminum piston body (1) at the clamping ring (92), and then separating the aluminum piston body (1), the material handle (12) and the guide member (9).