A composite extrusion casting die and preparation method of a non-overlapping blade aluminum alloy impeller

Abstract

A non-overlapping blade type aluminum alloy impeller composite extrusion casting mold and its preparation method, including male and female molds, the upper end of the male mold is connected with the upper pad and the upper connecting plate, the female mold is placed above the transition plate, the transition plate is connected with the lower pad and the lower connecting plate, the lower end of the male mold is provided with a sealing section matched with the female mold cavity, a bushing is embedded in the center hole position of the transition plate, a top plug is arranged in the bushing, a liquid storage chamber is formed between the upper end surface of the top plug and the bushing, the lower end of the top plug is connected with a top rod, and the top rod is connected with a hydraulic machine ejection cylinder. The non-overlapping blade type aluminum alloy impeller is manufactured by using the composite extrusion casting process, high mechanical pressure is applied to the liquid metal in the mold cavity by extrusion casting, so that the liquid metal is shaped and solidified, and the process is simple, the cost is low, the quality is reliable, and the performance is high. The mold structure is reasonable, the molding effect is good, the preparation method is easy to operate, the demolding is convenient, the mechanical properties of the prepared aluminum alloy impeller are high, and the use requirements of high-quality aluminum alloy impellers can be met.

Description

Technical Field

[0001] This invention belongs to the field of metal material processing technology, and relates to a composite extrusion casting mold and preparation method for a non-overlapping blade aluminum alloy impeller. Background Technology

[0002] As a core component of a turbine engine, the impeller's function is to compress or accelerate gas, thereby improving engine efficiency and reducing fuel consumption. Commonly used metal materials for impellers include cast iron, stainless steel, nickel-based alloys, titanium alloys, and aluminum alloys. The following are common manufacturing methods for producing aluminum alloy impellers: 1. Overall machining The integral machining of aluminum alloy impellers employs five-axis CNC machining, which utilizes advanced machine tools and computer technology to perform multi-axis rotation and precision machining of the blades and impeller via three rotary axes (X, Y, and Z) and two tilting axes (A and B). The main problems with this manufacturing method are as follows: (1) The blades have a long radial length and low stiffness, making them prone to deformation during processing.

[0003] (2) The space between adjacent blades is narrow, and the diameter of the cutting tool is small and easy to break when the blade is used for corner clearing.

[0004] (3) The impeller is a free-form surface, which is twisted and tends to tilt backward. It is very easy to cause interference during processing, and sometimes it is necessary to process in sections, making it difficult to ensure the consistency of the processed surface.

[0005] 2 Casting The main casting processes for aluminum alloy impellers are gravity casting and low-pressure casting. 1) Gravity casting Aluminum alloy impellers are mainly produced using investment casting and plaster casting. Gravity casting involves liquid metal filling and solidifying under atmospheric pressure, while aluminum alloy impellers have significant thickness variations. The blades are very thin (only 1mm~2mm at the outer edge) while the central part is much thicker (generally φ50mm~φ200mm). Therefore, the blades are difficult to form, and the central part is prone to casting defects such as shrinkage cavities and porosity, resulting in lower mechanical properties.

[0006] 2) Low-pressure casting Compared to gravity casting, low-pressure casting features slow mold filling and pressure crystallization, which improves the internal quality and mechanical properties of aluminum alloy impellers. The main problems with this manufacturing method are as follows: (1) In low-pressure casting, the aluminum alloy liquid enters the mold cavity from bottom to top through the gating system under the action of compressed air (or inert gas). Due to the fluctuation of the liquid surface during the filling process, the casting is prone to defects such as porosity and oxide inclusions.

[0007] (2) The pressure of low-pressure casting is relatively low, which cannot completely eliminate the problems of shrinkage and porosity in the central part of gravity casting, and cannot meet the manufacturing and use requirements of high-quality aluminum alloy impellers. Summary of the Invention

[0008] The first technical problem to be solved by the present invention is to provide a composite extrusion casting mold for a non-overlapping blade aluminum alloy impeller, which has the characteristics of reasonable structural design and good forming effect. It can apply high mechanical pressure to the liquid metal in the mold cavity to form and solidify it, and the quality is reliable.

[0009] The second technical problem to be solved by the present invention is to provide a method for preparing a non-overlapping blade aluminum alloy impeller, which adopts a composite extrusion casting process, and has the advantages of simple casting process and low cost, and reliable quality and high performance of forging.

[0010] The technical solution adopted by the present invention to solve the first technical problem mentioned above is as follows: a composite extrusion casting mold for a non-overlapping blade aluminum alloy impeller, characterized in that: it includes a male mold of the upper half of the mold and a female mold of the lower half of the mold, an upper pad plate and an upper connecting plate are connected sequentially above the male mold, the female mold is placed above a transition plate, the transition plate is connected sequentially to a lower pad plate and a lower connecting plate, the lower end of the male mold is provided with a sealing section that mates with the cavity of the female mold, the lower end of the male mold is provided with a guide post, the upper end of the female mold is provided with a guide sleeve corresponding to the guide post, a bushing is embedded below the cavity of the female mold and at the center hole of the transition plate, a top plug is provided inside the bushing, a liquid storage chamber is formed between the upper end face of the top plug and the inner wall of the bushing, the lower end of the top plug is connected to a push rod, and the lower end of the push rod is connected to the ejector cylinder of a hydraulic press.

[0011] As an improvement, the upper connecting plate is bolted to the lower part of the movable slider of the hydraulic press, and the upper connecting plate, the upper pad plate and the male mold are connected and fixed by screws. The transition plate is fixedly connected to the lower pad plate and the lower connecting plate in sequence by screws.

[0012] Furthermore, the lower end face of the male mold has a concave step on one side, and a round hole for installing the guide post is opened on the step surface. The guide post is fixed in the round hole of the male mold by a shoulder-pressure plate type. The upper end face of the female mold has a boss corresponding to the concave step of the male mold. An opening for inserting the guide sleeve is opened on the boss at the position corresponding to the guide post. The guide sleeve is set in the opening and fixed by a cylindrical pin. The guide section dimension of the guide post is larger than the sealing section dimension L+15mm of the male mold and the female mold.

[0013] Furthermore, the bushing is a circular sleeve structure that mates with the inner wall of the central hole of the transition plate. The height of the bushing is greater than that of the transition plate, and the upper end face of the bushing is flush with the transition plate. The lower end of the inner wall of the transition plate is provided with an annular groove, and the outer wall of the bushing is provided with a corresponding annular protrusion. The bushing is set in the central hole of the transition plate and positioned by the mating of the annular protrusion and the annular groove.

[0014] Furthermore, the diameter of the top plug matches the inner diameter of the bushing, the upper end of the push rod is provided with a reduced-diameter external threaded post, and the center position of the lower end face of the top plug is provided with a corresponding threaded hole. The top plug is fixed to the push rod by a threaded connection and can move up and down and be positioned by the push rod.

[0015] Finally, the outer sides of the male mold, female mold, and transition plate are respectively provided with pins. The male mold and female mold are connected by connecting pins on the male mold and female mold, or the female mold and transition plate are connected by connecting pins on the female mold and transition plate.

[0016] The technical solution adopted by this invention to solve the second technical problem mentioned above is: a method for preparing a non-overlapping blade aluminum alloy impeller, characterized in that: the impeller is prepared using the aforementioned composite extrusion casting mold, and the specific steps are as follows: 1) Lower the movable slide of the hydraulic press so that the upper half of the mold fits into the female mold placed above the transition plate, and put the connecting piece on the pin of the male mold and the pin of the female mold. 2) The movable slide of the rising hydraulic press lifts the upper half of the mold along with the female mold to a certain height; 3) Pour the molten aluminum alloy into the storage chamber formed by the top plug and bushing, and skim off the oxide scale on the surface of the molten aluminum alloy; 4) Lower the movable slide of the hydraulic press, and use the pressing force of the movable slide to press the upper half and lower half of the mold together; 5) Start the hydraulic press ejector cylinder, use the ejector plug to fill the cavity with molten aluminum alloy in the storage chamber and continue to apply high mechanical pressure to the molten aluminum alloy. 6) After holding the pressure for a certain period of time, remove the connecting piece between the upper half of the mold and the female mold, and put it on the pin of the female mold and the pin of the transition plate. 7) Raise the movable slide of the hydraulic press to a certain height to separate the casting from the male mold; 8) Use the ejector plug to apply a release force to the casting, causing the casting to separate from the mold; 9) Remove the casting and return the hydraulic press ejector cylinder to the lower dead center position.

[0017] Furthermore, the pouring temperature of the aluminum alloy liquid in step 3) is 680℃~710℃.

[0018] Furthermore, in step 5), the extrusion casting pressure is 60MPa~80MPa.

[0019] Furthermore, the pressure holding time in step 6) is 40s ± 10s.

[0020] Compared with existing technologies, the advantages of this invention are as follows: It designs a composite extrusion casting mold and employs a composite extrusion casting process to manufacture non-overlapping blade aluminum alloy impellers. Through extrusion casting, high mechanical pressure is applied to the liquid metal within the mold cavity, causing it to form and solidify. This method combines the advantages of simple casting processes and low cost with the reliable quality and high performance of forging. The mold structure of this invention is rationally designed, resulting in good forming effects. The preparation method is easy to operate, producing good forming results and convenient demolding. The formed aluminum alloy impeller products have high quality and high mechanical properties, meeting the requirements for high-quality aluminum alloy impellers and significantly enhancing product market competitiveness. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0023] like Figure 1 As shown, a composite extrusion casting mold for a non-overlapping blade aluminum alloy impeller includes an upper connecting plate 1, an upper pad plate 2, and a male mold 3 in the upper half of the mold, and a female mold 7, a transition plate 11, a lower pad plate 12, and a lower connecting plate 13 in the lower half of the mold. The upper connecting plate 1 is fixed to the lower part of the movable slider of the hydraulic press with bolts 18. The upper connecting plate 1 is sequentially fixed to the upper pad plate 2 and the male mold 3 with hexagonal screws. The female mold 7 is placed above the transition plate 11. The transition plate 11 is sequentially fixed to the lower pad plate 12 and the lower connecting plate 13 with hexagonal screws. The lower connecting plate 13 is fixed to the upper part of the hydraulic press worktable with bolts 18. The lower end of the male mold 3 is provided with a sealing section that mates with the cavity of the female mold 7. The lower end of the male mold 3 is provided with a guide post 4. The upper end of the female mold 7 is provided with a guide sleeve 5 corresponding to the guide post 4. A bushing 10 is embedded in the lower part of the cavity of the female mold 7 and at the center hole of the transition plate 11. A top plug 8 is provided inside the bushing 10. A liquid storage chamber is formed between the upper end face of the top plug 8 and the inner wall of the bushing 10. The lower end of the top plug 8 is connected to the ejector rod 9. The lower end of the ejector rod 9 is connected to the ejector cylinder of the hydraulic press.

[0024] The specific structure is as follows: The lower end face of the male mold 3 has a concave step on one side, and a round hole for the installation of the guide post 4 is opened on the step surface. The guide post 4 is fixed in the round hole of the male mold 3 by a shoulder-pressure plate type. The upper end face of the female mold 7 has a boss corresponding to the concave step of the male mold 3. The boss has an opening for the guide sleeve 5 to be inserted at the position corresponding to the guide post 4. The guide sleeve 5 is set in the opening and fixed by a cylindrical pin 6. The sealing section of the male mold 3 and the female mold 7 has a size of L, and the guiding section of the guide post 4 has a size greater than L + 15mm, so that the guide post 4 plays a guiding role before the male mold 3 enters the female mold 7.

[0025] The bushing 10 is a circular sleeve structure that mates with the inner wall of the central hole of the transition plate 11. The height of the bushing 10 is greater than that of the transition plate 11. The upper end face of the bushing 10 is flush with the transition plate 11. The lower end of the inner wall of the transition plate 11 is provided with an annular groove. The outer wall of the bushing 10 is provided with a corresponding annular protrusion. The bushing 10 is embedded in the central hole of the transition plate 11 and positioned by the engagement of the annular protrusion and the annular groove. The purpose of setting the bushing 10 is to facilitate the repair of the inner wall of the liquid storage chamber and the preheating of the aluminum alloy liquid. The diameter of the top plug 8 matches the inner diameter of the bushing 10. The upper end of the push rod 9 is provided with a reduced-diameter external threaded post. The center position of the lower end face of the top plug 8 is provided with a corresponding threaded hole. The top plug 8 is fixed to the push rod 9 by a threaded connection and can move up and down and be positioned by the push rod 9. The lower end of the push rod 9 is provided with a threaded connection section that connects to the hydraulic press ejector cylinder. When the upper end face of the top plug 8 and the bushing 10 form a liquid storage chamber of a certain volume, the position is positioned by the lower stop point of the hydraulic press ejector cylinder to avoid the top plug 8 and the push rod 9 being pulled apart if shoulder positioning is used.

[0026] The outer sides of the male mold 3, female mold 7 and transition plate 11 are respectively provided with pins 17, 15 and 14. The male mold 3 and female mold 7 can be connected by connecting pins 17 and 15 on the male mold 3 and female mold 7 as needed. Alternatively, the female mold 7 and transition plate 11 can be connected by connecting pins 15 and 14 on the female mold 7 and transition plate 11.

[0027] A method for preparing a non-overlapping blade aluminum alloy impeller, using the aforementioned composite extrusion casting mold, includes the following specific steps: 1) Lower the movable slider of the hydraulic press so that the upper half of the mold fits against the female mold 7 placed above the transition plate 11, and put the connecting piece 16 on the pin 17 of the male mold 3 and the pin 15 of the female mold 7. 2) The movable slide of the rising hydraulic press lifts the upper half of the mold along with the female mold 7 to a certain height; 3) Pour the molten aluminum alloy into the storage chamber formed by the top plug 8 and the bushing 10, and skim off the oxide scale on the surface of the molten aluminum alloy. 4) Lower the movable slide of the hydraulic press, and use the pressing force of the movable slide to press the upper half and lower half of the mold together; 5) Start the hydraulic press ejector cylinder, use the ejector plug 8 to fill the cavity with molten aluminum alloy in the storage chamber and continue to apply high mechanical pressure to the molten aluminum alloy. 6) After holding the pressure for a certain period of time, remove the connecting piece 16 that connects the upper half of the mold and the female mold 7, and put it on the pin 15 of the female mold 7 and the pin 14 of the transition plate 11. 7) Raise the movable slide of the hydraulic press to a certain height to separate the casting from the male mold 3; 8) Use the top plug 8 to apply a demolding force to the casting, so that the casting separates from the female mold 7; 9) Remove the casting and return the hydraulic press ejector cylinder to the lower dead center position.

[0028] The process parameters are: Mold temperature: 200℃~280℃ Pouring temperature: 680℃~710℃ (when using ZL101A alloy) Squeeze casting specific pressure: 60MPa~80MPa Pressure holding time: 40s.

[0029] The working principle of this invention is as follows: After the upper mold and the female mold are lifted to a certain height by the movable slide of the hydraulic press, molten aluminum alloy is poured into the reservoir chamber formed by the top plug and bushing. The movable slide of the hydraulic press is lowered, and the pressing force of the movable slide is used to press the male mold 3 and the female mold 7 together, so that the male mold 3 and the female mold 7 form a closed cavity. The ejection force of the ejector cylinder of the hydraulic press is used to push the top plug 8 through the ejector rod 9, so that the molten aluminum alloy in the reservoir chamber fills the cavity and continues to apply a high mechanical pressure to the molten aluminum alloy. After holding the pressure for a certain period of time, the upper mold is lifted by the movable slide of the hydraulic press, and the top plug 8 is used to apply a demolding force to the casting, so that the casting is separated from the female mold 7.

[0030] The innovative point of this invention is: (1) The lower surface and side surface of the aluminum alloy impeller blades are formed by the cavity on the female mold, so that the casting is stuck in the female mold when the male mold and female mold are separated.

[0031] (2) The liquid storage chamber adopts an inlaid bushing structure, which facilitates the repair of the inner wall of the liquid storage chamber and the use of aluminum alloy liquid for preheating.

[0032] (3) The sealing section of the male mold and the female mold is L, and the guiding section of the guide post is greater than (L+15) mm, which plays a guiding role before the male mold enters the female mold.

[0033] (4) The position of the upper end face of the top plug and the bushing when forming a liquid storage chamber of a certain volume is located by the lower dead point of the hydraulic press ejector cylinder to avoid the top plug and ejector rod being pulled off by the shoulder positioning.

[0034] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A composite extrusion casting mold for a non-overlapping blade aluminum alloy impeller, characterized in that: The mold includes a male mold (upper half) and a female mold (lower half). An upper pad and an upper connecting plate are connected to the upper part of the male mold in sequence. The female mold is placed on top of a transition plate. The transition plate is connected to a lower pad and a lower connecting plate in sequence. The lower end of the male mold has a sealing section that mates with the cavity of the female mold. The lower end of the male mold has a guide post. The upper end of the female mold has a guide sleeve corresponding to the guide post. A bushing is embedded in the lower part of the cavity of the female mold and at the center hole of the transition plate. A top plug is installed in the bushing. A liquid storage chamber is formed between the upper end face of the top plug and the inner wall of the bushing. The lower end of the top plug is connected to a push rod. The lower end of the push rod is connected to the ejector cylinder of the hydraulic press. The upper connecting plate is bolted to the lower part of the movable slider of the hydraulic press. The upper connecting plate, the upper pad plate and the male mold are connected and fixed by screws. The transition plate is connected to the lower pad plate and the lower connecting plate in sequence by screws. The lower end face of the male mold has a concave step on one side, and a round hole for installing the guide post is opened on the step surface. The guide post is fixed in the round hole of the male mold by a shoulder-pressure plate type. The upper end face of the female mold has a boss corresponding to the concave step of the male mold. The boss has an opening for the guide sleeve to be inserted at the position corresponding to the guide post. The guide sleeve is set in the opening and fixed by a cylindrical pin. The sealing section of the male mold and the female mold is L, and the guiding section of the guide post is greater than L + 15mm. The bushing is a circular sleeve structure that mates with the inner wall of the central hole of the transition plate. The height of the bushing is greater than that of the transition plate. The upper end face of the bushing is flush with the transition plate. The lower end of the inner wall of the transition plate is provided with an annular groove. The outer wall of the bushing is provided with a corresponding annular protrusion. The bushing is set in the central hole of the transition plate and positioned by the mating of the annular protrusion and the annular groove. The diameter of the top plug matches the inner diameter of the bushing. The upper end of the top rod is provided with a reduced-diameter external threaded post, and the center of the lower end face of the top plug is provided with a corresponding threaded hole. The top plug is fixed to the top rod by a threaded connection and can move up and down and be positioned by the top rod. The male mold, female mold, and transition plate are each provided with a pin on their outer side. The male mold and female mold are connected by connecting pins on the male mold and female mold, or the female mold and transition plate are connected by connecting pins on the female mold and transition plate.

2. A method for preparing a non-overlapping blade aluminum alloy impeller, characterized in that: The composite extrusion casting mold described in claim 1 is used for preparation, and the specific steps are as follows: 1) Lower the movable slide of the hydraulic press so that the upper half of the mold fits into the female mold placed above the transition plate, and put the connecting piece on the pin of the male mold and the pin of the female mold. 2) The movable slide of the rising hydraulic press lifts the upper half of the mold along with the female mold to a certain height; 3) Pour the molten aluminum alloy into the storage chamber formed by the top plug and bushing, and skim off the oxide scale on the surface of the molten aluminum alloy; 4) Lower the movable slide of the hydraulic press, and use the pressing force of the movable slide to press the upper half and lower half of the mold together; 5) Start the hydraulic press ejector cylinder, use the ejector plug to fill the cavity with molten aluminum alloy in the storage chamber and continue to apply high mechanical pressure to the molten aluminum alloy; the specific pressure of extrusion casting in step 5) is 60MPa~80MPa; 6) After holding the pressure for a certain period of time, remove the connecting piece between the upper half of the mold and the female mold, and put it on the pin of the female mold and the pin of the transition plate. 7) Raise the movable slide of the hydraulic press to a certain height to separate the casting from the male mold; 8) Use the ejector plug to apply a release force to the casting, causing the casting to separate from the mold; 9) Remove the casting and return the hydraulic press ejector cylinder to the lower dead center position.

3. The preparation method according to claim 2, characterized in that: The pouring temperature of the aluminum alloy liquid in step 3) is 680℃~710℃.

4. The preparation method according to claim 2, characterized in that: The pressure holding time in step 6) is 40s ± 10s.

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