Efficient die-casting process for deep-cavity special-shaped magnesium alloy

Abstract

The invention relates to the technical field of magnesium alloy die-casting, and discloses a deep-cavity special-shaped magnesium alloy efficient die-casting process which comprises the following specific steps that a die is designed according to the shape and specification of a casting, and the die-casting die comprises a plurality of pouring systems with gradually-decreased cross sections and an overflow system provided with at least one overflow groove and an overflow channel; the cooling system is provided with an internal cooling water channel and an external cooling device; assembling a mold and adjusting parameters; pre-melting a magnesium alloy material into a liquid state, and injecting into the mold; a multi-stage injection technology is adopted for solution injection; the magnesium liquid in the mold is rapidly cooled and molded by adopting a rapid cooling system; demoulding the magnesium alloy part; the taken-out magnesium alloy part is subjected to surface treatment such as finishing, finish machining, paint spraying or spraying; and cleaning and inspecting. According to the method, system optimization is carried out, and the quality and efficiency of the complex deep-cavity special-shaped magnesium alloy casting are ensured; and the performance, the appearance and the consistency of the magnesium alloy part are improved, and the requirements of various high-end application fields are met.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium alloy die-casting, and more particularly to a high-efficiency die-casting process for deep-cavity special-shaped magnesium alloys. Background Art

[0002] Magnesium alloy is an alloy based on magnesium with a certain amount of other alloying elements added. It is one of the light metal materials. Due to its good casting performance and plastic processing performance, good electrical and thermal conductivity, good corrosion resistance and weldability, it can be used as a structural material. It is widely used in aerospace, aviation, transportation, construction, electromechanical, light chemical and daily necessities. In order to improve the performance of magnesium alloy, it is necessary to combine the use of die-casting molds and die-casting processes to die-cast magnesium alloys.

[0003] Due to the complex structure of deep cavities, special-shaped magnesium alloy die-castings can experience cold shuts during the filling process, resulting in partially incomplete castings and affecting product quality. Furthermore, the magnesium alloy melt easily adheres to the mold surface, preventing smooth demolding of the casting and impacting production efficiency. Therefore, an efficient deep-cavity special-shaped magnesium alloy die-casting process is urgently needed to address these issues. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a deep-cavity special-shaped magnesium alloy high-efficiency die-casting process to solve the problems raised in the background technology that due to the complex deep cavity structure, cold shut may occur during the filling process, resulting in partial incompleteness of the casting, affecting product quality, and the die-casting is prone to adhesion to the mold surface, resulting in the casting cannot be smoothly demolded, affecting production efficiency.

[0005] To achieve the above object, the technical solution of the present invention is as follows: A high-efficiency die-casting process for deep-cavity special-shaped magnesium alloys includes the following specific steps: S1) Mold Design: Based on the shape and specifications of the casting, the mold is designed using computer aided technology. The die casting mold includes a gating system with multiple decreasing cross-sections, an overflow system with at least one overflow trough and overflow channel, and a cooling system with internal cooling water channels and external cooling devices. S2) Mould production: According to the design drawings, high-precision processing equipment is used to make the mould, using steel materials, and the mould working precision reaches micron level; S3) Assembling the mold and adjusting parameters: The prepared mold is installed on the casting equipment and the equipment parameters are adjusted. The parameter adjustment includes using a programmable logic controller to control the injection speed in stages, with the first stage being fast filling, the second stage being slow filling, and the third stage being pressure holding. Real-time monitoring of pressure sensor data ensures that the injection pressure is maintained within ±5% of the set value during the pressure holding stage. S4) Magnesium liquid injection: The magnesium alloy material is pre-melted to a liquid state using precision measurement and temperature control equipment and injected into the mold. Before injection, a vacuum degassing device is used to reduce the gas content to below 0.1%. The melt is then filtered through a melt filtration system using a filter with at least 100 mesh to remove inclusions. S5) Casting Process: After the equipment parameters are adjusted, the magnesium alloy die-casting process is executed. By controlling the heating, liquid injection, rest time and rapid cooling of the magnesium alloy, high-quality castings are achieved. A multi-stage injection technique is used. The first-stage injection speed is set at 2-4 m / s to quickly fill the mold cavity; the second-stage injection speed is set at 1-2 m / s to reduce the contact time between the melt and the mold; the third-stage injection is used for pressure holding and solidification, with a pressure set at 60-80 MPa. S6) Mold cooling: A rapid cooling system is used to rapidly cool the magnesium liquid in the mold and to monitor the cooling time and temperature in real time; S7) Demolding of magnesium alloy parts: After the mold has cooled, the die-cast magnesium alloy parts are removed from the mold using a mechanical or pneumatic demoulding device. During the demoulding process, a specially formulated release agent is used. The release agent is a mixture of silicone oil, graphite, and boric acid in a weight ratio of 4:3:3. The application process is spraying. S8) Surface treatment: The removed magnesium alloy parts are subjected to surface treatment such as trimming, finishing, painting or spraying to meet the appearance and surface quality requirements of the parts; S9) Cleaning and inspection: After cleaning, the magnesium alloy die castings are inspected for dimensional accuracy, appearance quality and defects to determine whether the castings are qualified.

[0006] As a further improvement to the present invention, the pouring system is designed to be multi-stage progressive, specifically including at least three pouring channels with different cross-sectional areas, and the cross-sectional area of each channel decreases in sequence from large to small.

[0007] As a further improvement to the present invention, the overflow trough and the overflow channel are designed to be adjustable, including an adjustable overflow channel width and a replaceable overflow trough shape, and rapid adjustment is achieved through mechanical or hydraulic drive.

[0008] As a further improvement to the present invention, the external cooling device of the cooling system is water-cooled and equipped with a circulating water pump and a temperature controller, which can adjust the flow rate and temperature of the cooling water in real time according to the mold temperature.

[0009] As a further improvement to the present invention, the vacuum chamber of the vacuum degassing device is designed to be movable and is equipped with a sensor to monitor the vacuum degree.

[0010] As a further improvement to the present invention, the filter box of the melt filtration system is pressure-type, with a built-in filter screen and a pressure gauge, and the pressure gauge monitors the pressure changes during the filtration process in real time.

[0011] As a further improvement to the present invention, the third-stage holding pressure of the multi-stage injection technique is dynamically adjusted according to the wall thickness and structure of the casting.

[0012] As a further improvement to the present invention, the release agent coating process uses a precision spray device equipped with multiple nozzles, and the release agent is evenly coated on the mold surface in an atomized form.

[0013] As a further improvement of the present invention, a uniform anti-stick coating is coated on the surface of the mold. The coating material is silicon nitride or magnesium oxide, with a thickness of 5-10 microns, and is applied by plasma spraying technology.

[0014] As a further improvement of the present invention, the anti-stick coating is formed by plasma spraying technology. The spraying equipment includes a plasma gun, a powder feeding device and a control system. The silicon nitride or magnesium oxide powder is heated to a molten state in the plasma gun and then sprayed onto the mold surface to form a uniform coating.

[0015] The beneficial technical effects of the present invention are: The present invention systematically optimizes every step from mold design and manufacturing to magnesium alloy casting to ensure the quality and efficiency of complex deep-cavity special-shaped magnesium alloy castings. First, in the mold design step, the mold design is completed through computer assistance according to the shape and specifications of the casting, and a multi-stage progressive pouring system and an adjustable overflow system design are adopted to reduce turbulence and oxidation during the melt flow process; at the same time, the dual cooling system design of internal cooling water channels and external cooling devices is combined to improve the thermal balance and rapid cooling ability of the mold. This step effectively solves the problems of uneven melt filling and cold shut caused by the deep cavity structure.

[0016] Secondly, high-precision machining equipment is used during mold fabrication to ensure micron-level accuracy. A segmented injection technique is then used during subsequent equipment parameter adjustments. This involves a first-stage rapid filling to reduce turbulence; a second-stage decelerated filling to control temperature distribution; and a third-stage pressure-maintaining technique to ensure adequate filling. This method avoids the localized cold shut issues associated with traditional single-speed injection, improving filling efficiency within deep cavities and the overall integrity of the casting.

[0017] Vacuum degassing and filtration are implemented before magnesium liquid injection to reduce the likelihood of inclusions and porosity in the alloy. Multi-stage injection, combined with a rapid cooling system and real-time temperature monitoring, enables an efficient and controllable die-casting and cooling process.

[0018] A specific formula was designed and the release agent was applied by spraying to prevent melt adhesion, significantly improve demoulding performance and enhance demoulding efficiency.

[0019] The above process effectively avoids the defects of existing deep-cavity special-shaped die-casting, improves the performance, appearance and consistency of magnesium alloy parts, and is suitable for the needs of various high-end application fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall process of the present invention. DETAILED DESCRIPTION

[0021] In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0022] Combine Figure 1 , the present invention provides the following embodiments: A high-efficiency die-casting process for deep-cavity special-shaped magnesium alloys includes the following specific steps: Mold design: Based on the shape and specifications of the casting, computer-aided design (CAD) software is used for precise modeling. The model not only includes a complex cavity design suitable for deep cavity structures, but also a multi-stage progressive pouring system. The die-casting mold includes a pouring system with multiple decreasing cross-sections, an overflow system with at least one overflow trough and overflow channel, and a cooling system with internal cooling water channels and external cooling devices.

[0023] Mould production: According to the design drawings, high-precision processing equipment is used to make the mould, using steel as the material, and the mould working accuracy reaches the micron level.

[0024] Mold Assembly and Parameter Adjustment: The prepared mold is installed on the casting equipment, and equipment parameters are adjusted to ensure the highest precision of the magnesium alloy parts during the forging process. Parameter adjustment involves using a programmable logic controller (PLC) to control the injection speed in stages: the first stage is rapid filling, the second stage is decelerated filling, and the third stage is pressure holding. Real-time monitoring of pressure sensor data ensures that the injection pressure remains within ±5% of the set value during the pressure holding phase. The PLC control system in the parameter adjustment step monitors the injection speed and pressure in real time and automatically adjusts them using a built-in algorithm to ensure that the injection parameters match the casting process requirements.

[0025] Magnesium liquid injection: The magnesium alloy material is pre-melted into liquid form through precision measurement and temperature control equipment and injected into the mold. Before injection, a vacuum degassing device is used to reduce the gas content to below 0.1%, and the melt is filtered through a melt filtration system using a filter of at least 100 mesh to remove inclusions in the melt.

[0026] Casting Process: After adjusting the equipment parameters, the magnesium alloy die-casting process is executed. High-quality castings are achieved by controlling the heating, liquid injection, rest time, and rapid cooling of the magnesium alloy. A multi-stage injection technique is used, with the first-stage injection speed set at 2-4 m / s to quickly fill the mold cavity; the second-stage injection speed is set at 1-2 m / s to reduce the contact time between the melt and the mold; the third-stage injection is used for pressure holding and solidification, with a pressure set at 60-80 MPa.

[0027] Mold cooling: A rapid cooling system is used to quickly cool the magnesium liquid in the mold and shape it. The cooling process is optimized by real-time monitoring of cooling time and temperature.

[0028] Demolding magnesium alloy parts: After the mold cools, the die-cast magnesium alloy part is removed from the mold using a mechanical or pneumatic demolding device, while removing impurities such as gates and burrs. During the demolding process, a specially formulated release agent is applied. This release agent is a mixture of silicone oil, graphite, and boric acid in a weight ratio of 4:3:3. A spray application method ensures uniform distribution of the release agent. Furthermore, a uniform anti-stick coating of silicon nitride or magnesium oxide with a thickness of 5-10 microns is applied using plasma spray technology to ensure uniformity and adhesion.

[0029] Surface treatment: The removed magnesium alloy parts are subjected to surface treatments such as trimming, finishing, painting or spraying to meet the appearance and surface quality requirements of the parts.

[0030] Cleaning and inspection: After cleaning, the magnesium alloy die castings are inspected for dimensional accuracy, appearance quality and defects. The inspection determines whether the castings are qualified and ensures that the quality of the final product meets industrial standards.

[0031] As another preferred embodiment of the present invention, the pouring system is designed as a multi-stage progressive pouring system, specifically including at least three pouring channels with different cross-sectional areas, and the cross-sectional area of each channel decreases from large to small to guide the melt to flow smoothly, reduce turbulence and oxidation, and ensure the quality of the casting.

[0032] As another preferred embodiment of the present invention, the overflow trough and overflow channel are designed to be adjustable, including an adjustable overflow channel width and a replaceable overflow trough shape to adapt to the die-casting requirements of different castings, and to achieve rapid adjustment through mechanical or hydraulic drive.

[0033] As another preferred embodiment of the present invention, the external cooling device of the cooling system is water-cooled and equipped with a circulating water pump and a temperature controller, which can adjust the flow and temperature of the cooling water in real time according to the mold temperature to maintain the stability of the mold working temperature.

[0034] As another preferred embodiment of the present invention, the vacuum chamber of the vacuum degassing device is designed to be movable and equipped with a sensor to monitor the vacuum degree, so that the chamber can be moved above the magnesium alloy material at different positions to achieve comprehensive degassing.

[0035] As another preferred embodiment of the present invention, the filter box of the melt filtration system adopts a pressure type, with a built-in filter screen and a pressure gauge. The filter screen is designed to be quickly replaced to facilitate the removal of inclusions in the melt. At the same time, the pressure gauge is used to monitor the pressure changes during the filtration process.

[0036] As another preferred embodiment of the present invention, the third-stage holding pressure of the multi-stage injection technology is dynamically adjusted according to the wall thickness and structure of the casting, and real-time feedback and calculation are performed by pressure sensors and microprocessors to adapt to the pressure change requirements during the solidification process of the casting.

[0037] As another preferred embodiment of the present invention, the release agent coating process uses precision spray equipment equipped with multiple nozzles to ensure that the release agent is evenly coated on the mold surface in an atomized form to reduce adhesion between the casting and the mold.

[0038] As another preferred embodiment of the present invention, the mold surface is coated with a uniform anti-stick coating, the coating material is silicon nitride or magnesium oxide, the thickness is 5-10 microns, and it is applied by plasma spraying technology to ensure coating uniformity and adhesion.

[0039] Furthermore, the anti-stick coating is formed by plasma spraying technology. The spraying equipment includes a plasma gun, a powder feeding device and a control system. Silicon nitride or magnesium oxide powder is heated to a molten state in the plasma gun and then sprayed onto the mold surface. The formed coating is uniform and has good adhesion to the mold material.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-efficiency die-casting process for deep-cavity special-shaped magnesium alloys, characterized in that: The specific steps include: S1) Mold Design: Based on the shape and specifications of the casting, the mold is designed using computer aided technology. The die casting mold includes a gating system with multiple decreasing cross-sections, an overflow system with at least one overflow trough and overflow channel, and a cooling system with internal cooling water channels and external cooling devices. S2) Mould production: According to the design drawings, high-precision processing equipment is used to make the mould, using steel materials, and the mould working precision reaches micron level; S3) Assembling the mold and adjusting parameters: The prepared mold is installed on the casting equipment and the equipment parameters are adjusted. The parameter adjustment includes using a programmable logic controller to control the injection speed in stages, with the first stage being fast filling, the second stage being slow filling, and the third stage being pressure holding. Real-time monitoring of pressure sensor data ensures that the injection pressure is maintained within ±5% of the set value during the pressure holding stage. S4) Magnesium liquid injection: The magnesium alloy material is pre-melted to a liquid state using precision measurement and temperature control equipment and injected into the mold. Before injection, a vacuum degassing device is used to reduce the gas content to below 0.1%. The melt is then filtered through a melt filtration system using a filter with at least 100 mesh to remove inclusions. S5) Casting Process: After the equipment parameters are adjusted, the magnesium alloy die-casting process is executed. By controlling the heating, liquid injection, rest time and rapid cooling of the magnesium alloy, high-quality castings are achieved. A multi-stage injection technique is used. The first-stage injection speed is set at 2-4 m / s to quickly fill the mold cavity; the second-stage injection speed is set at 1-2 m / s to reduce the contact time between the melt and the mold; the third-stage injection is used for pressure holding and solidification, with a pressure set at 60-80 MPa. S6) Mold cooling: A rapid cooling system is used to rapidly cool the magnesium liquid in the mold and to monitor the cooling time and temperature in real time; S7) Demolding of magnesium alloy parts: After the mold has cooled, the die-cast magnesium alloy parts are removed from the mold using a mechanical or pneumatic demoulding device. During the demoulding process, a specially formulated release agent is used. The release agent is a mixture of silicone oil, graphite, and boric acid in a weight ratio of 4:3:

3. The application process is spraying. S8) Surface treatment: The removed magnesium alloy parts are subjected to surface treatment such as trimming, finishing, painting or spraying to meet the appearance and surface quality requirements of the parts; S9) Cleaning and inspection: After cleaning, the magnesium alloy die castings are inspected for dimensional accuracy, appearance quality and defects to determine whether the castings are qualified.

2. The deep cavity special-shaped magnesium alloy high-efficiency die-casting process according to claim 1 is characterized in that: In step S1, the pouring system is designed to be multi-stage progressive, specifically including at least three pouring channels with different cross-sectional areas, and the cross-sectional area of each channel decreases in sequence from large to small.

3. The deep cavity special-shaped magnesium alloy high-efficiency die-casting process according to claim 2, characterized in that: In step S1, the overflow trough and the overflow channel are designed to be adjustable, including an adjustable overflow channel width and a replaceable overflow trough shape, and rapid adjustment is achieved through mechanical or hydraulic drive.

4. The high-efficiency die-casting process for deep-cavity special-shaped magnesium alloys according to claim 1, characterized in that: The external cooling device of the cooling system in step S1 is water-cooled and equipped with a circulating water pump and a temperature controller, which can adjust the flow rate and temperature of the cooling water in real time according to the mold temperature.

5. The deep cavity special-shaped magnesium alloy high-efficiency die-casting process according to claim 1, characterized in that: The vacuum chamber of the vacuum degassing device is designed to be movable and is equipped with a sensor to monitor the vacuum degree.

6. The deep cavity special-shaped magnesium alloy high-efficiency die-casting process according to claim 5, characterized in that: The filter box of the melt filtration system adopts a pressure type, with a built-in filter screen and a pressure gauge, and the pressure gauge monitors the pressure changes during the filtration process in real time.

7. The high-efficiency die-casting process for deep-cavity special-shaped magnesium alloys according to claim 1, characterized in that: The third-stage holding pressure of the multi-stage injection technique is dynamically adjusted according to the wall thickness and structure of the casting.

8. The deep cavity special-shaped magnesium alloy high-efficiency die-casting process according to claim 7, characterized in that: The release agent coating process adopts a precision spraying device equipped with multiple nozzles, and the release agent is evenly coated on the mold surface in an atomized form.

9. The deep cavity special-shaped magnesium alloy high-efficiency die-casting process according to claim 1, characterized in that: A uniform anti-stick coating is applied on the surface of the mold. The coating material is silicon nitride or magnesium oxide with a thickness of 5-10 microns and is applied by plasma spraying technology.

10. The deep cavity special-shaped magnesium alloy high-efficiency die-casting process according to claim 9, characterized in that: The anti-stick coating is formed by plasma spraying technology. The spraying equipment includes a plasma gun, a powder feeding device and a control system. Silicon nitride or magnesium oxide powder is heated to a molten state in the plasma gun and then sprayed onto the mold surface to form a uniform coating.

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