Extrusion casting forming device of high-strength heat-resistant aluminum-silicon eutectic alloy piston and using method of extrusion casting forming device

Abstract

The invention discloses a squeeze casting forming device of a high-strength heat-resistant aluminum-silicon eutectic alloy piston and a using method of the squeeze casting forming device, and relates to a squeeze casting forming device of aluminum-silicon eutectic alloy and a using method of the squeeze casting forming device. The invention aims to solve the technical problems that the existing high-strength heat-resistant eutectic aluminum alloy large-size and large-wall-thickness-difference thin-wall piston is difficult to fill and difficult to demould during precision forming. The side wall and the bottom of the female die do not have pattern draft, molten aluminum splashing caused by the fact that the lower portion is large and the upper portion is small in the extrusion casting process is prevented, and a piston forming part can be completely demolded by spraying a large amount of aquadag on the female die. The side wall of the cavity is matched with the first working part of the male die, and the maximum gap is 0.03 mm, so that smooth filling and pressure maintaining in the extrusion casting forming process can be guaranteed. High-precision forming of the aluminum-silicon eutectic alloy piston with the large size and the large wall thickness difference is achieved, and the formed piston piece is prevented from being locked on the punch of the male die through different draft angles and lubricating strategies of the male die.

Description

Technical Field

[0001] The invention relates to an extrusion casting forming device for an aluminum-silicon eutectic alloy and a use method thereof. Background Art

[0002] The engine is a key component of the power source, and the piston is one of the key components that maintains the engine's continuous and stable power output. Its performance directly affects the engine's operating state. With the rapid development of industries such as gas machinery, automobiles, ships, aviation, and rail transportation in recent years, the demand for large-sized, high-performance engine pistons has been increasing. Aluminum alloys, with their advantages such as good thermal conductivity, low density, and high specific strength, are widely used in automobile engine casings and pistons in high-speed internal combustion engines. The lightweight nature of aluminum alloys not only aligns with energy conservation, emission reduction, and green development policies, but also demonstrates numerous advantages in application, such as reduced inertial forces and impact forces during reciprocating motion, as well as reduced wear.

[0003] The traditional forming methods of pistons are mainly gravity casting and die forging. These two piston forming methods still have certain limitations for forming large-sized pistons. Gravity casting can cause pistons to have structural defects such as porosity and shrinkage, affecting the quality, performance and service life of the product. The forming of forged pistons is often affected by the properties of the material itself, the forging range and the tonnage of the forging equipment. Squeeze casting is an advanced casting process that presses liquid or semi-solid metal melt directly into a metal mold and rapidly solidifies it under high pressure. This process combines the advantages of high-pressure die casting and plastic processing technology. It can reduce porosity and shrinkage defects while achieving metal finished products with dense structure and excellent mechanical properties.

[0004] Although aluminum alloy extrusion casting technology offers numerous advantages over traditional gravity casting and forging, it still faces some key technical challenges, such as controlling the mold-filling fluidity of the melt, uniform mold temperature distribution, controlling the tendency to thermal cracking, and regulating the strengthening phase structure. Furthermore, for parts with different alloy systems or uneven thicknesses, the extrusion casting process parameters (including mold temperature, casting pressure, and holding time) need to be precisely matched and optimized to achieve the stable production of large-scale piston parts. Therefore, further research and improvement are still needed regarding issues such as molding defect control, organizational performance optimization, and the integrated molding of complex structural parts during the aluminum alloy extrusion casting process to meet the needs of large-scale industrial applications. Summary of the Invention

[0005] The present invention aims to solve the technical problems of difficulty in filling and demolding during the precision forming of large-size and large-wall-thickness-difference thin-walled pistons made of high-strength and heat-resistant eutectic aluminum alloy, and to provide an extrusion casting forming device for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston and its use method.

[0006] The extrusion casting forming device of the high-strength and heat-resistant aluminum-silicon eutectic alloy piston of the present invention comprises a punch fixing plate 1, a punch 2, a die 3 and a push rod 5;

[0007] The center of the punch fixing plate 1 is a first stepped through hole 1-1 and the diameter of the upper portion is larger. The upper surface of the punch fixing plate 1 is flat and has a plurality of second stepped through holes 1-2 evenly arranged thereon.

[0008] The top of the punch 2 is a stepped boss 2-1, and the lower part of the stepped boss 2-1 is connected in sequence to a transition part 2-2, a first working part 2-4, and a second working part 2-6. The first fillet 2-3 where the lower surface of the stepped boss 2-1 intersects with the transition part 2-2 is R6; the second fillet 2-5 in the second working part 2-6 for forming the piston lug position is R3.

[0009] The punch 2 is arranged in the first stepped through hole 1-1 of the punch fixing plate 1, and the stepped boss 2-1 matches the first stepped through hole 1-1;

[0010] The inner cavity of the die 3 is in the form of concentric steps with a gradually decreasing diameter from top to bottom. The first step 3-2 with a larger diameter located at the top is used to form the piston top. The angle between the cavity sidewall 3-1 above the first step 3-2 and the first step 3-2 is 90°, and the cavity sidewall 3-1 and the first step 3-2 form the cavity. The inner diameter of the cavity sidewall 3-1 is 110 mm. The cavity sidewall 3-1 cooperates with the first working portion 2-4 of the punch 2 with a maximum clearance of 0.03 mm. The upper surface of the first working portion 2-4 is lower than the upper surface 3-4 of the die 3.

[0011] The ejector pin 5 is composed of an upper ejector head 5-1 and a lower connecting rod 5-2. The ejector pin 5 is located in the inner cavity of the die 3 and at the lower part of the punch 2. The lower surface of the ejector head 5-1 is stuck on the second step 3-5 of smaller diameter located at the lower part of the die 3.

[0012] The method for using the squeeze casting forming device of the high-strength and heat-resistant aluminum-silicon eutectic alloy piston of the present invention is as follows:

[0013] 1. Weigh the corresponding raw materials according to the elemental composition of the required high-strength and heat-resistant aluminum-silicon eutectic alloy piston. To prevent alloy loss caused by burning and slag removal, the raw materials should be weighed 1.2 to 1.3 times the weight of the alloy required for forming the piston.

[0014] The high-strength and heat-resistant aluminum-silicon eutectic alloy piston has the following elements by weight: Si: 12%; Cu: 4.5%; Ni: 2.0%; Mg: 0.8%; Zr: 0.2%; V: 0.2%; Er: 0.25%; Sc: 0.2-0.25%; Ti: 0.1%; Sr: 0.03%, with Al as the balance; the raw materials are pure aluminum and intermediate alloys of the remaining elements and aluminum;

[0015] Dry all weighed raw materials in a drying oven;

[0016] 2. Fix the punch fixing plate 1 to the upper movable beam of the 2000kN three-beam four-column squeeze casting equipment with bolts, and fix the die 3 to the lower fixed beam of the 2000kN three-beam four-column squeeze casting equipment;

[0017] 3. Start the extrusion casting equipment and move the upper movable crossbeam downward, so that the first working part 2-4 and the second working part 2-6 of the punch 2 enter the inner cavity of the die 3. When the distance between the bottom of the second working part 2-6 and the first step 3-2 is 20 mm, stop the descent of the punch 2. Heat the outside of the die 3 so that the temperature of the second working part 2-6 and the cavity side wall 3-1 are both heated to above 100°C. Then, the punch 2 is returned to the maximum height by the upper movable crossbeam. Graphite emulsion solution is sprayed on the outer walls of the first working part 2-4 and the second working part 2-6 of the punch 2, the first step 3-2 and the cavity side wall 3-1 of the die 3 by a spray gun. The amount of graphite emulsion solution sprayed in the die 3 is 50% more than that on the punch 2.

[0018] Fourth, the punch 2 is moved downward into the inner cavity of the die 3 by the upper movable crossbeam. When the distance between the bottom of the second working portion 2-6 and the first step 3-2 is 20 mm, the punch 2 is stopped from descending. The outside of the die 3 is heated until the temperature of the second working portion 2-6 reaches 120°C to 220°C and the temperature of the cavity sidewall 3-1 reaches 150°C to 250°C.

[0019] 5. Put all the raw materials dried in step 1 into a graphite clay crucible coated with ZnO for smelting. After all the raw materials are melted, stir them, and degas and remove slag by passing argon + ultrasonic vibration coupling, and then keep them warm for 30 minutes;

[0020] 6. The upper movable crossbeam drives the punch 2 back to the limit height, and then the molten metal in step 5 is poured into the cavity of the die 3 at a constant speed through the metering spoon. The upper movable crossbeam is quickly operated to allow the first working part 2-4 and the second working part 2-6 to enter the cavity of the die 3 for extrusion casting and pressure maintenance;

[0021] 7. After the pressure holding is completed, the upper movable crossbeam drives the punch 2 back to the limit height, and the lower ejector cylinder of the squeeze casting equipment moves upward to drive the ejector rod 5 to move upward, pushing the piston 4 out of the cavity of the die 3. The formed piston 4 is placed in warm water at 50℃~60℃ for water quenching, and then cooled to room temperature;

[0022] 8. The piston member 4 is placed in a high-temperature heat treatment furnace for T6 heat treatment, thereby completing the extrusion casting of the high-strength and heat-resistant eutectic aluminum alloy piston.

[0023] The technical solution of the present invention has the following three innovative features:

[0024] 1. Combination of side wall and lubricant: The angle between the cavity side wall 3-1 above the first step 3-2 and the first step 3-2 in the present invention is 90°, that is, there is no draft angle between the side wall and the bottom of the die 3, which prevents aluminum liquid from splashing due to the upper part being larger than the lower part during the extrusion casting process, and the piston formed part can be completely demolded by spraying a large amount of graphite emulsion on the die 3.

[0025] 2. Unilateral Gap: The cavity sidewall 3-1 of the present invention cooperates with the first working portion 2-4 of the punch 2 with a maximum gap of 0.03mm, ensuring smooth filling and pressure holding during the squeeze casting process. If the mold gap is larger than 0.03mm, the high specific pressure will cause the molten aluminum to splash out of the gap between the male and female molds under high pressure, making it difficult to form the piston component or causing injury.

[0026] 3. Lower than the die plane: In the present invention, the upper surface of the first working portion 2-4 is lower than the upper surface 3-4 of the die 3. If the first working portion 2-4 is too long, when the material comes out, the friction distance is long and the friction force is large, which will increase the draft force, cause greater damage to the mold, and reduce the service life of the mold.

[0027] The beneficial effects of the present invention are:

[0028] The present invention achieves high-precision forming of large-sized and large-thickness aluminum-silicon eutectic alloy pistons, resolving the problems of difficult filling and poor density in large-sized, thin-walled pistons. Furthermore, through different draft angles and lubrication strategies for the punch, the formed piston component is prevented from seizing at the punch tip, i.e., the second working portion 2-6. This allows the formed piston component 4 to remain smoothly within the cavity of the die 3, facilitating its complete removal via the ejector rod 5. Simultaneously, by controlling the temperature field between the punch and die, the mechanical properties of the piston crown and skirt at different locations are controlled and enhanced. This technology provides a new approach for forming large-sized and large-thickness thin-walled pistons made of eutectic aluminum-silicon alloys. Compared to traditional gravity casting, this technology significantly improves material utilization while ensuring stable mechanical properties. Compared to forged piston forming, it significantly reduces the tonnage of forming equipment and shortens piston production time. It has the potential for large-scale industrial application and meets the requirements of green, energy-saving, lightweight and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 3D schematic diagram of the bottom surface of the punch fixing plate 1 of the first embodiment;

[0030] Figure 2 This is a three-dimensional schematic diagram of the top of the punch fixing plate 1 of the first embodiment;

[0031] Figure 3 Schematic diagram of the three-dimensional structure of the male mold 2 of the first embodiment;

[0032] Figure 4 Schematic diagram of the three-dimensional structure of the die 3 of the first embodiment;

[0033] Figure 5 3D schematic diagram of the ejector pin 5 of the first embodiment;

[0034] Figure 6 Detailed description of the three-dimensional schematic diagram of the squeeze casting forming device of the high-strength and heat-resistant aluminum-silicon eutectic alloy piston in the first embodiment;

[0035] Figure 7 A three-dimensional cross-sectional schematic diagram of an extrusion casting forming apparatus for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston according to a first embodiment;

[0036] Figure 8 This is a schematic diagram of a piston member 4 prepared in a fifth embodiment;

[0037] Figure 9 A physical picture of the piston member 4 prepared for test one. DETAILED DESCRIPTION

[0038] Specific embodiment 1: This embodiment is an extrusion casting forming device for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston, such as Figure 1-Figure 7 As shown, it includes a punch fixing plate 1, a punch 2, a die 3 and a push rod 5;

[0039] The center of the punch fixing plate 1 is a first stepped through hole 1-1 and the diameter of the upper portion is larger. The upper surface of the punch fixing plate 1 is flat and has a plurality of second stepped through holes 1-2 evenly arranged thereon.

[0040] The top of the punch 2 is a stepped boss 2-1, and the lower part of the stepped boss 2-1 is connected in sequence to a transition part 2-2, a first working part 2-4, and a second working part 2-6. The first fillet 2-3 where the lower surface of the stepped boss 2-1 intersects with the transition part 2-2 is R6; the second fillet 2-5 in the second working part 2-6 for forming the piston lug position is R3.

[0041] The punch 2 is arranged in the first stepped through hole 1-1 of the punch fixing plate 1, and the stepped boss 2-1 matches the first stepped through hole 1-1;

[0042] The inner cavity of the die 3 is in the form of concentric steps with a gradually decreasing diameter from top to bottom. The first step 3-2 with a larger diameter located at the top is used to form the piston top. The angle between the cavity sidewall 3-1 above the first step 3-2 and the first step 3-2 is 90°, and the cavity sidewall 3-1 and the first step 3-2 form the cavity. The inner diameter of the cavity sidewall 3-1 is 110 mm. The cavity sidewall 3-1 cooperates with the first working portion 2-4 of the punch 2 with a maximum clearance of 0.03 mm. The upper surface of the first working portion 2-4 is lower than the upper surface 3-4 of the die 3.

[0043] The ejector pin 5 is composed of an upper ejector head 5-1 and a lower connecting rod 5-2. The ejector pin 5 is located in the inner cavity of the die 3 and at the lower part of the punch 2. The lower surface of the ejector head 5-1 is stuck on the second step 3-5 of smaller diameter located at the lower part of the die 3.

[0044] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the length of the first working portion 2-4 is greater than 50 mm. Other aspects are the same as specific embodiment 1.

[0045] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that a mold sleeve is further provided on the outside of the female mold 3, and a heating resistance wire is provided in the mold sleeve. Other aspects are the same as specific embodiment 1 or 2.

[0046] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the outer wall of the die 3 is a truncated cone structure with a larger diameter at the top and a slope of 3°. Other aspects are the same as specific embodiments 1 to 3.

[0047] Specific embodiment 5: The method of using the squeeze casting forming device of the high-strength and heat-resistant aluminum-silicon eutectic alloy piston in this embodiment and the specific embodiment 1 is as follows:

[0048] 1. Weigh the corresponding raw materials according to the elemental composition of the required high-strength and heat-resistant aluminum-silicon eutectic alloy piston. To prevent alloy loss caused by burning and slag removal, the raw materials should be weighed 1.2 to 1.3 times the weight of the alloy required for forming the piston.

[0049] The high-strength and heat-resistant aluminum-silicon eutectic alloy piston has the following elements by weight: Si: 12%; Cu: 4.5%; Ni: 2.0%; Mg: 0.8%; Zr: 0.2%; V: 0.2%; Er: 0.25%; Sc: 0.2-0.25%; Ti: 0.1%; Sr: 0.03%, with Al as the balance; the raw materials are pure aluminum and intermediate alloys of the remaining elements and aluminum;

[0050] Dry all weighed raw materials in a drying oven;

[0051] 2. Fix the punch fixing plate 1 to the upper movable beam of the 2000kN three-beam four-column squeeze casting equipment with bolts, and fix the die 3 to the lower fixed beam of the 2000kN three-beam four-column squeeze casting equipment;

[0052] 3. Start the extrusion casting equipment and move the upper movable crossbeam downward, so that the first working part 2-4 and the second working part 2-6 of the punch 2 enter the inner cavity of the die 3. When the distance between the bottom of the second working part 2-6 and the first step 3-2 is 20 mm, stop the descent of the punch 2. Heat the outside of the die 3 so that the temperature of the second working part 2-6 and the cavity side wall 3-1 are both heated to above 100°C. Then, the punch 2 is returned to the maximum height by the upper movable crossbeam. Graphite emulsion solution is sprayed on the outer walls of the first working part 2-4 and the second working part 2-6 of the punch 2, the first step 3-2 and the cavity side wall 3-1 of the die 3 by a spray gun. The amount of graphite emulsion solution sprayed in the die 3 is 50% more than that on the punch 2.

[0053] Fourth, the punch 2 is moved downward into the inner cavity of the die 3 by the upper movable crossbeam. When the distance between the bottom of the second working portion 2-6 and the first step 3-2 is 20 mm, the punch 2 is stopped from descending. The outside of the die 3 is heated until the temperature of the second working portion 2-6 reaches 120°C to 220°C and the temperature of the cavity sidewall 3-1 reaches 150°C to 250°C.

[0054] 5. Put all the raw materials dried in step 1 into a graphite clay crucible coated with ZnO for smelting. After all the raw materials are melted, stir them, and degas and remove slag by passing argon + ultrasonic vibration coupling, and then keep them warm for 30 minutes;

[0055] 6. The upper movable crossbeam drives the punch 2 back to the limit height, and then the molten metal in step 5 is poured into the cavity of the die 3 at a constant speed through the metering spoon. The upper movable crossbeam is quickly operated to allow the first working part 2-4 and the second working part 2-6 to enter the cavity of the die 3 for extrusion casting and pressure maintenance;

[0056] 7. After the pressure holding is completed, the upper movable crossbeam drives the punch 2 back to the limit height, and the lower ejector cylinder of the squeeze casting equipment moves upward to drive the ejector rod 5 to move upward, pushing the piston 4 out of the cavity of the die 3. The formed piston 4 is placed in warm water at 50℃~60℃ for water quenching, and then cooled to room temperature;

[0057] 8. The piston member 4 is placed in a high-temperature heat treatment furnace for T6 heat treatment, thereby completing the extrusion casting of the high-strength and heat-resistant eutectic aluminum alloy piston.

[0058] Specific embodiment 6: This embodiment differs from specific embodiment 5 in that the drying temperature in step 1 is 200° C. and the drying time is 1.5 h. Other aspects are the same as specific embodiment 5.

[0059] Specific embodiment 7: This embodiment differs from specific embodiment 6 in that the mass concentration of the graphite emulsion solution in step 3 is 5% to 10%. Other aspects are the same as specific embodiment 6.

[0060] Specific embodiment eight: This embodiment differs from specific embodiment seven in that the melting temperature in step five is 720° C. The rest is the same as specific embodiment seven.

[0061] Specific embodiment 9: This embodiment differs from specific embodiment 8 in that the casting temperature in step 6 is 720° C. The rest is the same as specific embodiment 8.

[0062] Specific embodiment 10: This embodiment differs from specific embodiment 9 in that the holding time in step 6 is 60 seconds and the pressure is maintained at 150 MPa to 200 MPa. Other aspects are the same as specific embodiment 9.

[0063] The technical solution of this embodiment has the following three innovative features:

[0064] 1. Combination of side wall and lubricant: The angle between the cavity side wall 3-1 above the first step 3-2 and the first step 3-2 in the present invention is 90°, that is, there is no draft angle between the side wall and the bottom of the die 3, which prevents aluminum liquid from splashing due to the upper part being larger than the lower part during the extrusion casting process, and the piston formed part can be completely demolded by spraying a large amount of graphite emulsion on the die 3.

[0065] 2. Unilateral Gap: The cavity sidewall 3-1 of the present invention cooperates with the first working portion 2-4 of the punch 2 with a maximum gap of 0.03mm, ensuring smooth filling and pressure holding during the squeeze casting process. If the mold gap is larger than 0.03mm, the high specific pressure will cause the molten aluminum to splash out of the gap between the male and female molds under high pressure, making it difficult to form the piston component or causing injury.

[0066] 3. Lower than the die plane: In the present invention, the upper surface of the first working portion 2-4 is lower than the upper surface 3-4 of the die 3. If the first working portion 2-4 is too long, when the material comes out, the friction distance is long and the friction force is large, which will increase the draft force, cause greater damage to the mold, and reduce the service life of the mold.

[0067] The beneficial effects of this embodiment are:

[0068] The present invention achieves high-precision forming of large-sized and large-thickness aluminum-silicon eutectic alloy pistons, resolving the problems of difficult filling and poor density in large-sized, thin-walled pistons. Furthermore, through different draft angles and lubrication strategies for the punch, the formed piston component is prevented from seizing at the punch tip, i.e., the second working portion 2-6. This allows the formed piston component 4 to remain smoothly within the cavity of the die 3, facilitating its complete removal via the ejector rod 5. Simultaneously, by controlling the temperature field between the punch and die, the mechanical properties of the piston crown and skirt at different locations are controlled and enhanced. This technology provides a new approach for forming large-sized and large-thickness thin-walled pistons made of eutectic aluminum-silicon alloys. Compared to traditional gravity casting, this technology significantly improves material utilization while ensuring stable mechanical properties. Compared to forged piston forming, it significantly reduces the tonnage of forming equipment and shortens piston production time. It has the potential for large-scale industrial application and meets the requirements of green, energy-saving, lightweight and sustainable development.

[0069] Test 1: This test is a high-strength and heat-resistant aluminum-silicon eutectic alloy piston extrusion casting device, such as Figures 1-8 As shown, it includes a punch fixing plate 1, a punch 2, a die 3 and a push rod 5;

[0070] The center of the punch fixing plate 1 is a first stepped through hole 1-1 and the diameter of the upper portion is larger. The upper surface of the punch fixing plate 1 is flat and has a plurality of second stepped through holes 1-2 evenly arranged thereon.

[0071] The top of the punch 2 is a stepped boss 2-1, and the lower part of the stepped boss 2-1 is connected in sequence to a transition part 2-2, a first working part 2-4, and a second working part 2-6. The first fillet 2-3 where the lower surface of the stepped boss 2-1 intersects with the transition part 2-2 is R6; the second fillet 2-5 of the second working part 2-6 for forming the piston lug position is R3; the length of the first working part 2-4 is 55 mm.

[0072] The punch 2 is arranged in the first stepped through hole 1-1 of the punch fixing plate 1, and the stepped boss 2-1 matches the first stepped through hole 1-1;

[0073] The inner cavity of the die 3 is in the form of concentric steps and its diameter gradually decreases from top to bottom. The first step 3-2 with a larger diameter located at the top is used to form the piston top; the angle between the cavity side wall 3-1 above the first step 3-2 and the first step 3-2 is 90°, and the cavity side wall 3-1 and the first step 3-2 form a cavity; the inner diameter of the cavity side wall 3-1 is 110mm; the cavity side wall 3-1 cooperates with the first working part 2-4 of the punch 2 with a maximum gap of 0.03mm, and the upper surface of the first working part 2-4 is lower than the upper surface 3-4 of the die 3; the outside of the die 3 is also provided with a die sleeve, and a heating resistance wire is provided in the die sleeve; the outer wall of the die 3 is a frustum structure with a larger diameter at the top and a slope of 3°;

[0074] The ejector pin 5 is composed of an upper ejector head 5-1 and a lower connecting rod 5-2. The ejector pin 5 is located in the inner cavity of the die 3 and at the lower part of the punch 2. The lower surface of the ejector head 5-1 is stuck on the second step 3-5 of smaller diameter located at the lower part of the die 3.

[0075] The method for using the above-mentioned extrusion casting forming device for the high-strength and heat-resistant aluminum-silicon eutectic alloy piston is as follows:

[0076] 1. Weigh the corresponding raw materials according to the elemental composition of the required high-strength and heat-resistant aluminum-silicon eutectic alloy piston. To prevent alloy loss caused by burning and slag removal, the raw materials should be weighed 1.2 times the weight of the alloy required for forming the piston.

[0077] The high-strength and heat-resistant aluminum-silicon eutectic alloy piston has the following elements by weight: Si: 12%; Cu: 4.5%; Ni: 2.0%; Mg: 0.8%; Zr: 0.2%; V: 0.2%; Er: 0.25%; Sc: 0.25%; Ti: 0.1%; Sr: 0.03%, with Al as the balance; the raw materials are pure aluminum and intermediate alloys of the remaining elements and aluminum;

[0078] All weighed raw materials were dried in a drying oven at a temperature of 200°C for 1.5 h.

[0079] 2. Fix the punch fixing plate 1 to the upper movable beam of the 2000kN three-beam four-column squeeze casting equipment with bolts, and fix the die 3 to the lower fixed beam of the 2000kN three-beam four-column squeeze casting equipment;

[0080] 3. Start the extrusion casting equipment and move the upper movable crossbeam downward so that the first working part 2-4 and the second working part 2-6 of the punch 2 enter the inner cavity of the die 3. When the distance between the bottom of the second working part 2-6 and the first step 3-2 is 20 mm, stop the descent of the punch 2. Heat the outside of the die 3 so that the temperature of the second working part 2-6 and the cavity side wall 3-1 are both heated to above 100° C. Then, return the punch 2 to the maximum height by the upper movable crossbeam. Use a spray gun to spray a graphite emulsion solution on the outer walls of the first working part 2-4 and the second working part 2-6 of the punch 2, the first step 3-2 and the cavity side wall 3-1 of the die 3. The amount of the graphite emulsion solution sprayed in the die 3 is 50% more than that on the punch 2. The mass concentration of the graphite emulsion solution is 5% to 10%.

[0081] Fourth, the punch 2 is moved downward into the inner cavity of the die 3 by the upper movable crossbeam. When the distance between the bottom of the second working portion 2-6 and the first step 3-2 is 20 mm, the punch 2 is stopped from descending. The outside of the die 3 is heated until the temperature of the second working portion 2-6 reaches 120°C and the temperature of the cavity sidewall 3-1 reaches 150°C.

[0082] 5. Place all the raw materials dried in step 1 into a graphite clay crucible coated with ZnO and smelt them at a melting temperature of 720°C; after all the raw materials are melted, stir them, and degas and remove slag by passing argon + ultrasonic vibration coupling, and then keep them warm for 30 minutes;

[0083] 6. The upper movable crossbeam drives the punch 2 back to its maximum height, and then the molten metal from step 5 is poured into the cavity of the die 3 at a constant speed using a dosing spoon. The pouring temperature is 720°C. The upper movable crossbeam is quickly operated to allow the first working part 2-4 and the second working part 2-6 to enter the cavity of the die 3 for extrusion casting and the pressure is maintained at 200 MPa for 60 seconds.

[0084] 7. After the pressure holding is completed, the upper movable crossbeam drives the punch 2 back to the limit height, and the lower ejector cylinder of the squeeze casting equipment moves upward to drive the ejector rod 5 to move upward, thereby ejecting the piston 4 from the cavity of the die 3. The formed piston 4 is placed in warm water at 60°C for water quenching, and then cooled to room temperature to obtain a cast product;

[0085] 8. placing the as-cast product into a high-temperature heat treatment furnace for T6 heat treatment, thereby completing the extrusion casting of the high-strength and heat-resistant eutectic aluminum alloy piston;

[0086] The T6 heat treatment process is as follows: solution treatment with furnace temperature rising, the solution temperature is 510℃, the time is 8h, after the solution treatment is completed, the piston is taken out for water quenching, and then the piston after solution treatment is placed in a hot treatment furnace at a temperature of 190℃ for artificial aging for 6h, and then taken out for air cooling, completing the extrusion casting of the high-strength and heat-resistant eutectic aluminum alloy piston. The actual picture of the prepared piston is as follows Figure 9 shown.

[0087] The as-cast product from step 7 had a room temperature tensile strength of 347 MPa, a yield strength of 255.3 MPa, and an elongation of 1.25%. After the T6 heat treatment in step 8, the piston component 4 had a maximum tensile strength of 153.8 MPa at 350°C. The formed piston had a maximum outer wall diameter of 110 mm, a maximum height of 84 mm, a piston crown thickness of 10.5 mm, a piston skirt thickness of 7.3 mm, and a maximum piston pin boss wall thickness of 36 mm.

Claims

1. A high-strength and heat-resistant aluminum-silicon eutectic alloy piston extrusion casting device, characterized in that The device comprises a punch fixing plate (1), a punch (2), a die (3) and a push rod (5); The center of the punch fixing plate (1) is a first stepped through hole (1-1) and the upper portion has a larger diameter; the upper surface of the punch fixing plate (1) is a plane and has a plurality of second stepped through holes (1-2) evenly arranged thereon; The top of the punch (2) is a stepped boss (2-1), and the lower portion of the stepped boss (2-1) is sequentially connected to a transition portion (2-2), a first working portion (2-4), and a second working portion (2-6); the first fillet (2-3) where the lower surface of the stepped boss (2-1) intersects with the transition portion (2-2) is R6; the second fillet (2-5) in the second working portion (2-6) for forming the piston lug position is R3; The punch (2) is arranged in the first stepped through hole (1-1) of the punch fixing plate (1), and the stepped boss (2-1) and the first stepped through hole (1-1) match each other; The inner cavity of the die (3) is in the form of concentric steps and its diameter gradually decreases from top to bottom. The first step (3-2) with a larger diameter located at the top is used to form the piston top; the angle between the cavity side wall (3-1) above the first step (3-2) and the first step (3-2) is 90°, and the cavity side wall (3-1) and the first step (3-2) form a cavity; the inner diameter of the cavity side wall (3-1) is 110 mm; the cavity side wall (3-1) cooperates with the first working part (2-4) of the punch (2) with a maximum gap of 0.03 mm, and the upper surface of the first working part (2-4) is lower than the upper surface (3-4) of the die (3); The ejector pin (5) is composed of an upper ejector head (5-1) and a lower connecting rod (5-2). The ejector pin (5) is located in the inner cavity of the die (3) and at the lower part of the punch (2). The lower surface of the ejector head (5-1) is stuck on a second step (3-5) with a smaller diameter located at the lower part of the die (3).

2. The extrusion casting forming device for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston according to claim 1 is characterized in that The length of the first working portion (2-4) is greater than 50 mm.

3. The extrusion casting forming device for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston according to claim 1, characterized in that The outside of the concave die (3) is also provided with a die sleeve, and a heating resistance wire is provided in the die sleeve.

4. The extrusion casting forming device for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston according to claim 1, characterized in that The outer wall of the die (3) is a frustum structure with a larger diameter at the top and a slope of 3°.

5. The method for using the extrusion casting forming device for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston according to claim 1, characterized in that The method of use is as follows:

1. Weigh the corresponding raw materials according to the elemental composition of the required high-strength and heat-resistant aluminum-silicon eutectic alloy piston. To prevent alloy loss caused by burning and slag removal, the raw materials should be weighed 1.2 to 1.3 times the weight of the alloy required for forming the piston. The high-strength and heat-resistant aluminum-silicon eutectic alloy piston has the following elements by weight: Si: 12%; Cu: 4.5%; Ni: 2.0%; Mg: 0.8%; Zr: 0.2%; V: 0.2%; Er: 0.25%; Sc: 0.2-0.25%; Ti: 0.1%; Sr: 0.03%, with Al as the balance; the raw materials are pure aluminum and intermediate alloys of the remaining elements and aluminum; Dry all weighed raw materials in a drying oven; 2. Fix the punch fixing plate (1) to the upper movable beam of the 2000kN three-beam four-column extrusion casting equipment by bolts, and fix the die (3) to the lower fixed beam of the 2000kN three-beam four-column extrusion casting equipment; 3. Start the extrusion casting equipment and move the upper movable crossbeam downward, so that the first working part (2-4) and the second working part (2-6) of the punch (2) enter the inner cavity of the die (3), and stop the descent of the punch (2) when the distance between the bottom of the second working part (2-6) and the first step (3-2) is 20 mm; heat the outside of the die (3) so that the temperature of the second working part (2-6) and the cavity side wall (3-1) are heated to above 100° C., and then return the punch (2) to the limit height by the upper movable crossbeam, and spray the graphite emulsion solution on the outer wall of the first working part (2-4) and the second working part (2-6) of the punch (2) and the first step (3-2) and the cavity side wall (3-1) of the die (3) by a spray gun, and the amount of the graphite emulsion solution sprayed in the die (3) is 50% more than that on the punch (2); Fourth, the punch (2) is moved downward into the inner cavity of the die (3) by the upper movable crossbeam, and the descent of the punch (2) is stopped when the distance between the bottom of the second working portion (2-6) and the first step (3-2) is 20 mm, and the outside of the die (3) is heated so that the temperature of the second working portion (2-6) reaches 120°C to 220°C and the temperature of the cavity side wall (3-1) reaches 150°C to 250°C; 5. Put all the raw materials dried in step 1 into a graphite clay crucible coated with ZnO for smelting. After all the raw materials are melted, stir them, and degas and remove slag by passing argon + ultrasonic vibration coupling, and then keep them warm for 30 minutes; 6. The upper movable crossbeam drives the punch (2) to return to the limit height, and then the molten metal in step 5 is poured into the cavity of the die (3) at a constant speed through the metering spoon. The upper movable crossbeam is quickly operated to allow the first working part (2-4) and the second working part (2-6) to enter the cavity of the die (3) for extrusion casting and pressure maintenance; 7. After the pressure holding is completed, the upper movable crossbeam drives the punch (2) back to the limit height, and the lower ejector cylinder of the extrusion casting equipment moves upward to drive the ejector rod (5) to move upward, so as to eject the piston (4) from the cavity of the die (3), and the formed piston (4) is placed in warm water at 50°C to 60°C for water quenching, and then cooled to room temperature; 8. The piston member (4) is placed in a high-temperature heat treatment furnace for T6 heat treatment, thereby completing the extrusion casting of the high-strength and heat-resistant eutectic aluminum alloy piston.

6. The method for using the squeeze casting forming device for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston according to claim 5, characterized in that The drying temperature in step 1 is 200° C. and the drying time is 1.5 h.

7. The method for using the squeeze casting forming device for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston according to claim 5, characterized in that The mass concentration of the graphite emulsion solution described in step 3 is 5% to 10%.

8. The method for using the squeeze casting forming device for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston according to claim 5, characterized in that The smelting temperature described in step 5 is 720°C.

9. The method for using the squeeze casting forming device for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston according to claim 5, characterized in that The casting temperature in step six is ​​720°C.

10. The method for using the squeeze casting forming device for a high-strength and heat-resistant aluminum-silicon eutectic alloy piston according to claim 5, characterized in that The holding time in step six is ​​60s, and the pressure is maintained at 150MPa~200MPa.

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