A lightweight automotive steering wheel magnesium alloy frame die-casting process

Abstract

This invention relates to the field of steering wheel frame die casting technology, specifically a lightweight automotive steering wheel magnesium alloy frame die casting process, including a mold closing mechanism, an injection mechanism, a mold mechanism, and an ejection mechanism. The mold mechanism has a cavity for machining the steering wheel, a gating mechanism for conveying molten magnesium alloy to the cavity, and venting mechanisms located on both sides of the gating opening. The mold mechanism also includes several temperature control modules for controlling the temperature at various points within the cavity. This invention significantly reduces the size and complexity of the die casting mold by dividing the steering wheel into three modules: the hub, the spokes, and the rim. This also reduces the mold manufacturing cost, enabling the production line to quickly respond to small-batch, diversified market demands. The rim is formed by extrusion and then shaped into the steering wheel rim shape using a dedicated mold, effectively reducing flow line defects and shrinkage cavities that occur during traditional die casting of rims.

Description

Technical Field

[0001] This invention relates to the field of steering wheel frame die casting technology, specifically a lightweight automotive steering wheel magnesium alloy frame die casting process. Background Technology

[0002] Magnesium, as the lightest metallic structural material, has excellent specific strength and good shock absorption performance. When applied to automobile steering wheels, it can reduce weight by more than 30%, while effectively reducing road and control system vibrations and improving driving safety. With the advancement of the automotive lightweighting trend, magnesium alloy steering wheel frames, as important lightweight components, have become a research hotspot in the automotive manufacturing industry.

[0003] The existing die-casting process for magnesium alloy steering wheels still faces a series of technical bottlenecks, restricting its large-scale promotion and application. The current mainstream production technology mainly adopts the traditional one-piece die-casting process. Although this process achieves the integral molding of the steering wheel frame, it has exposed many problems in practical applications. The steering wheel frame structure is complex and the wall thickness varies greatly. In the traditional die-casting process, the venting groove is prone to blockage, resulting in air entrapment. In addition, the traditional die-casting of the wheel rim is prone to flow line defects and shrinkage cavities. Furthermore, the turbulence in the gating system can lead to unstable delivery of magnesium alloy solution, which in turn affects the mechanical properties of the product. At the same time, the integral mold structure is complex, the manufacturing cycle is long, the cost is high, and it is difficult to adapt to the market demand for small batches and multiple varieties.

[0004] The high chemical reactivity of magnesium alloys also presents challenges to production safety, requiring the use of protective gases (such as...) during the smelting process. and The mixture of gases not only increases production costs but also brings environmental pressure because... The global warming potential is The corrosion resistance of magnesium alloys is 23,900 times that of magnesium alloys. At the same time, magnesium alloys have relatively poor corrosion resistance and require additional surface treatment processes, which further increases the manufacturing cost.

[0005] Therefore, the present invention provides a lightweight automotive steering wheel magnesium alloy frame die casting process that overcomes the shortcomings of existing magnesium alloy steering wheel frame die casting processes. Summary of the Invention

[0006] To address the issues of high cost and long manufacturing cycle caused by complex mold structures in existing technologies, a lightweight magnesium alloy skeleton die-casting process for automotive steering wheels has been designed.

[0007] The technical solution adopted by the present invention to solve its technical problem is: a lightweight automotive steering wheel magnesium alloy frame die casting process, including a mold closing mechanism, an injection mechanism, a mold mechanism and an ejection mechanism. The mold mechanism has a cavity for processing the steering wheel, a gating mechanism for conveying magnesium alloy solution to the cavity and an exhaust mechanism on both sides of the gating opening, and a number of temperature control modules for controlling the temperature at various points in the cavity.

[0008] The steps of the lightweight automotive steering wheel magnesium alloy frame die-casting process are as follows:

[0009] S1: Material Pretreatment: Trace amounts of rare earth elements, such as Ce and Nd, are added to the AM60 magnesium alloy, with the total addition not exceeding 0.5%, to refine the grain size and improve the alloy's high-temperature performance and corrosion resistance. Simultaneously, the magnesium alloy raw material is melted in a vacuum induction furnace to effectively prevent oxidation and combustion. The melting temperature is controlled within the range of 680-710℃, and the following methods are employed... and The mixed gas contains a small amount of HFC-134a, which significantly reduces the greenhouse effect potential;

[0010] S2: Preparation: The steering wheel is divided into three modules: spokes, hub, and rim. The rim is made of magnesium alloy extruded profiles by bending. The extruded profiles are bent into the shape of the steering wheel rim using a special mold and undergo local strengthening treatment to avoid the flow line defects and shrinkage problems commonly found in traditional die-cast rims. The spokes and hub are die-cast using a multi-cavity mold. Before the magnesium alloy melt is transferred to the holding furnace, a trace amount of grain refiner (Zr element, 0.1%-0.3%) is added and electromagnetic stirring is used to ensure uniform distribution, making the alloy solidification structure more uniform and improving the grain size by more than one level, thereby improving the mechanical properties and fatigue strength of the alloy.

[0011] S3: Start of operation: The mold closing mechanism drives the mold mechanism to close stably through the hydraulic system and maintains continuous pressure on the mold mechanism. The magnesium alloy solution is transported through the fully enclosed magnesium alloy liquid delivery system in the injection mechanism and is quantitatively delivered by an electromagnetic pump. The delivery error is controlled within ±2%. The delivery pipeline is equipped with an insulation layer and a heating device to ensure that the temperature fluctuation of the magnesium alloy solution does not exceed ±5℃. The exhaust mechanism is equipped with a miniature vacuum valve in the cavity area and actively removes the gas in the cavity through the external vacuum system, so that the cavity vacuum degree reaches 0.05-0.08MPa.

[0012] S4: Die Casting Operation: The die casting mechanism first adopts slow injection, with the punch advancing at a low speed, controlled at 0.2-0.3 m / s, to ensure that the magnesium alloy liquid enters the pressure chamber smoothly. When the magnesium alloy liquid reaches the inner gate, the punch speed is rapidly increased to 4-5 m / s, and in conjunction with the gating mechanism, the magnesium alloy liquid fills the cavity within 0.03-0.05 seconds. Immediately after filling, a high pressure of 100-120 MPa is applied and maintained for 2-3 seconds for stable pressure increase. The pressure increase time is dynamically adjusted by the intelligent control system according to the real-time monitoring of the casting temperature field to ensure that pressure is applied while there is still a liquid phase channel at the solidification front.

[0013] S5: Temperature-controlled ejection: The temperature control module inside the mold mechanism controls the temperature in different areas according to the structure of each part of the cavity. After the hub and spokes are die-cast in the cavity, the mold closing mechanism drives the mold mechanism to separate the internal cavity, and the ejection mechanism ejects the die-cast workpiece.

[0014] S6: Post-treatment work: The graded heat treatment includes solution treatment at 410±10℃, holding for 2-3 hours and then rapid water cooling to fully dissolve the strengthening phase. Then, aging treatment is carried out at 175±5℃ for 8-10 hours to uniformly precipitate the strengthening phase and improve the strength and hardness of the alloy. After heat treatment, vibration aging treatment is added. By setting a specific frequency and amplitude (30-50Hz, 0.3-0.5mm), the skeleton is made to resonate, thereby homogenizing the internal stress distribution.

[0015] S7: Assembly work: The wheel rim and spokes and spokes and hub adopt a composite connection method of local pressing + laser welding. Preliminary positioning is achieved through precise interference fit. Then, laser welding is performed in the connection area, with the weld depth controlled at 1.5-2.0mm. The weld is then subjected to micro-arc oxidation treatment to form a dense oxide film of 10-15μm on the surface.

[0016] Furthermore, the gating mechanism includes a main gating located inside the mold mechanism and connected at one end to the injection mechanism. The end of the main gating away from the injection mechanism is connected to a first branch gating and a second branch gating distributed in a fan shape. The end of the first branch gating away from the main gating is connected to several sets of first casting elements for conveying magnesium alloy solution to the cavity. The end of the second branch gating away from the main gating is connected to several sets of second casting elements for conveying magnesium alloy solution to the cavity.

[0017] Furthermore, the internal structure of the second branch gating is the same as that of the first branch gating. The size of the first branch gating is larger than that of the second branch gating, and the number of first castings is greater than that of the second castings. The first branch gating includes a gradually expanding section and a rectangular section that gradually transitions from the expanding section. The end of the rectangular section away from the expanding section is a tapering section. Several sets of guide grooves are opened on both sides inside the rectangular section. When conveying magnesium alloy solution, the design of the first and second branch gatings avoids the phenomenon of flow deviation. At the same time, the gradually expanding setting makes the solution flow velocity decrease linearly, and the rectangular section setting makes the flow velocity distribution more uniform. In addition, the tapering setting at the discharge end improves the directionality of the solution entering the first and second castings. Meanwhile, the guide grooves opened inside the rectangular section effectively suppress boundary eddies.

[0018] Furthermore, the mold mechanism includes an upper mold and a lower mold connected to the mold closing mechanism. After the upper mold and the lower mold are closed, a cavity is formed inside. The cavity includes a first mold cavity for die casting the wheel hub and a second mold cavity for die casting the wheel spokes. The number of second mold cavities is set according to the number of wheel spokes.

[0019] Furthermore, the first and second casting parts are located inside the upper mold and extend to the first and second mold cavities opened on one side. The exhaust mechanism is located inside the upper mold and distributed on both sides of the first and second casting parts. It is used to exhaust the gas inside the first and second mold cavities through a vacuum valve in conjunction with an external vacuum system. The ejection mechanism is located inside the lower mold and one end extends to the first and second mold cavities. It is used to eject the die-cast workpiece. Multiple temperature control modules are located at the bottom of the first and second mold cavities opened in the lower mold.

[0020] Furthermore, the bottom of the mold closing mechanism is fixedly connected to a base. The mold closing mechanism includes a first fixing member and a second fixing member fixedly installed on both sides of the base. Guide rods are respectively provided around the inner perimeter of the first fixing member and the second fixing member. Sliding members are slidably connected on the guide rods. A driving member is fixedly connected to the side of the first fixing member away from the sliding member. The output end of the driving member passes through the first fixing member to the outside of the sliding member.

[0021] Furthermore, the upper mold component is fixedly connected to the side of the second fixing component away from the injection mechanism, the lower mold component is fixedly connected to the side of the sliding component away from the driving component, and a protective component is provided on the outside of the mold closing mechanism.

[0022] Furthermore, the injection mechanism includes a liquid storage component and a driving injection part connected to the bottom of the liquid storage component. The driving injection part has a piston rod on the side near the second fixed component. An injection cavity is provided on the outer side of the end of the piston rod near the second fixed component. The side of the injection cavity away from the piston rod is located inside the second fixed component. One side of the driving injection part is fixedly connected to the second fixed component.

[0023] Furthermore, the outer side of the hub is provided with several sets of first slots, and the outer side of the rim is provided with several sets of second slots. The spokes press their two ends into the hub and rim respectively through the first and second slots.

[0024] The beneficial effects of this invention are:

[0025] (1) The lightweight automotive steering wheel magnesium alloy skeleton die casting process of the present invention divides the steering wheel into three modules: hub, spoke and rim, which greatly reduces the volume and complexity of the die casting mold, and at the same time reduces the manufacturing cost of the mold, enabling the production line to quickly respond to the market demand for small batches and diversification. The rim is formed by extrusion and then formed into the shape of the steering wheel rim by a special mold, which effectively reduces the flow line defects and shrinkage problems that occur in the traditional die casting of the rim.

[0026] The hub and spokes are die-cast using a multi-cavity mold, and are equipped with a fan-shaped gating system and a gradually expanding first and second branch gating system with rectangular sections. This ensures the smooth delivery and filling of the magnesium alloy solution. At the same time, the guide grooves inside the rectangular sections can decompose the turbulence generated by the gating boundary layer, maintain a stable flow rate, and further improve product quality. Then, the gas inside the cavity is actively discharged through a multi-stage vacuum exhaust system, which greatly reduces the generation of air entrapment defects, thereby effectively improving the mechanical properties of the product and increasing the product qualification rate.

[0027] (2) The lightweight automotive steering wheel magnesium alloy frame die-casting process described in this invention reduces the impact of traditional die-casting processes by using a new environmentally friendly protective gas formula. The use of protective gases reduces greenhouse gas emissions and energy consumption. Through innovation in heat treatment processes and optimization of die-casting processes, the fatigue life and mechanical properties of the steering wheel frame are improved while maintaining the lightweight advantages of magnesium alloys. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] Figure 1 This is a schematic diagram of the main structure of the present invention;

[0030] Figure 2 This is a schematic diagram of the main side structure of the present invention;

[0031] Figure 3 This is a front view of the main structure of the present invention;

[0032] Figure 4 For the present invention Figure 3 A partially enlarged sectional view at point A;

[0033] Figure 5 This is a schematic diagram of the mold closing mechanism of the present invention;

[0034] Figure 6 This is a schematic diagram of the injection mechanism of the present invention;

[0035] Figure 7 This is a schematic diagram of the mold mechanism structure of the present invention;

[0036] Figure 8 This is a schematic diagram of the upper mold structure of the present invention;

[0037] Figure 9 For the present invention Figure 8 A magnified view of section B;

[0038] Figure 10 For the present invention Figure 8 A magnified view of a portion at point C;

[0039] Figure 11 This is a schematic diagram of the lower mold component structure of the present invention;

[0040] Figure 12 For the present invention Figure 11 A magnified view of a portion at point D;

[0041] Figure 13 This is a schematic diagram of the gating mechanism and venting mechanism of the present invention;

[0042] Figure 14 This is a schematic diagram of the gating mechanism of the present invention;

[0043] Figure 15 This is a top view of the gating mechanism structure of the present invention;

[0044] Figure 16 This is a partial sectional view of the first branch gating system of the present invention;

[0045] Figure 17 This is a partial sectional view of the lower module of the present invention;

[0046] Figure 18 For the present invention Figure 17 A partially enlarged sectional view at point E;

[0047] Figure 19 This is a schematic diagram of the steering wheel frame structure referenced in this invention;

[0048] Figure 20 For the present invention Figure 19 A magnified view of a portion at point F;

[0049] Figure 21 For the present invention Figure 19 A magnified view of a portion of point G.

[0050] In the diagram: 1. Base; 2. Protective component; 3. Mold closing mechanism; 31. First fixing component; 32. Second fixing component; 33. Guide rod; 34. Sliding component; 35. Driving component; 4. Injection mechanism; 41. Liquid storage component; 42. Driving injection section; 43. Piston rod; 44. Injection cavity; 5. Mold mechanism; 51. Upper mold component; 52. Lower mold component; 53. First mold cavity; 54. Second mold cavity; 6. Sprue mechanism; 61. Main sprue; 62. First branch sprue; 621. Gradually expanding section; 622. Rectangular section; 623. Guide groove; 63. Second branch sprue; 64. First casting component; 65. Second casting component; 7. Venting mechanism; 8. Ejection mechanism; 9. Temperature control module; 11. Hub; 111. First slot; 12. Spoke; 13. Rim; 131. Second slot. Detailed Implementation

[0051] To make the technical means, technical features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0052] Example: Figure 1 - Figure 21 As shown, the lightweight automotive steering wheel magnesium alloy frame die casting process of the present invention includes a mold closing mechanism 3, an injection mechanism 4, a mold mechanism 5, and an ejection mechanism 8. The mold mechanism 5 has a cavity for processing the steering wheel. The mold mechanism 5 also has a gating mechanism 6 for conveying magnesium alloy solution into the cavity and an exhaust mechanism 7 located on both sides of the gating opening. The mold mechanism 5 also has several sets of temperature control modules 9 for controlling the temperature at various points in the cavity.

[0053] Specifically, the steering wheel frame is divided into three modules: hub 11, spokes 12, and rim 13. The hub 11 has several sets of first slots 111 on its outer side, and the rim 13 has several sets of second slots 131 on its outer side. The spokes 12 are pressed into the hub 11 and rim 13 through the first and second slots 111 and 131 respectively to form a complete steering wheel frame. This significantly reduces the size and complexity of the die-casting mold, while also reducing mold manufacturing costs. This allows the production line to quickly respond to small-batch, diversified market demands. The rim 13 is extruded and formed into the shape of a steering wheel rim 13 using a special mold, effectively reducing the flow line defects and shrinkage problems that occur in traditional die-casting of the rim 13. The spokes 12 are die-cast using a multi-cavity mold. The mold closing mechanism 3 drives the mold mechanism 5 to close stably through an internal hydraulic system and maintains continuous pressure on the mold mechanism 5. The magnesium alloy solution is transported through a fully enclosed magnesium alloy liquid delivery system in the injection mechanism 4 and is quantitatively delivered using an electromagnetic pump. The exhaust mechanism 7 is equipped with a miniature vacuum valve in the cavity area to actively remove gas from the cavity through an external vacuum system. The temperature control module 9 performs zoned temperature control according to the structure of each part of the cavity. After the hub 11 and spokes 12 are die-cast in the cavity, the mold closing mechanism 3 drives the mold mechanism 5 to separate the internal cavity. The ejection mechanism 8 ejects the die-cast workpiece through a hydraulic cylinder or mechanical linkage. This is existing technology and will not be described in detail.

[0054] In this embodiment, the gating mechanism 6 includes a main gating 61 located inside the mold mechanism 5 and connected at one end to the injection mechanism 4. The end of the main gating 61 away from the injection mechanism 4 is connected to a first branch gating 62 and a second branch gating 63 arranged in a fan shape. The end of the first branch gating 62 away from the main gating 61 is connected to several sets of first casting elements 64 for conveying magnesium alloy solution to the cavity. The end of the second branch gating 63 away from the main gating 61 is connected to several sets of second casting elements 65 for conveying magnesium alloy solution to the cavity. The first branch gating 62 includes a gradually expanding section 621 and a rectangular section 622 that gradually transitions from the gradually expanding section 621. The end of the rectangular section 622 away from the gradually expanding section 621 is a tapering section. Several sets of guide grooves 623 are opened on both sides inside the rectangular section 622.

[0055] Specifically, such as Figure 13 - Figure 16As shown, the internal structure of the second branch gating 63 is the same as that of the first branch gating 62. The size of the first branch gating 62 is larger than that of the second branch gating 63. The number of first casting elements 64 is greater than that of second casting elements 65. When conveying magnesium alloy solution, the design of the first branch gating 62 and the second branch gating 63 avoids the phenomenon of flow deviation. At the same time, the gradual expansion setting makes the solution flow rate decrease linearly. The rectangular section 622 makes the flow rate distribution more uniform. In addition, the gradual reduction setting of the discharge end improves the directionality of the solution entering the first casting element 64 and the second casting element 65. The magnesium alloy solution is conveyed into the cavity through the first casting element 64 and the second casting element 65.

[0056] Meanwhile, the guide channel 623 inside the rectangular section 622 effectively suppresses boundary eddies. When the magnesium alloy solution flows in the rectangular channel, the fluid inertial force is much greater than the viscous force, causing the laminar boundary layer to detach from the wall and form large-scale vortices, similar to the Karman vortex street phenomenon. By dividing the fluid through the guide channel 623, the large vortex is decomposed into multiple small vortices. The small vortices have lower kinetic energy and can be dissipated by the fluid viscosity more quickly, thereby ensuring the stable delivery of the magnesium alloy solution.

[0057] In this embodiment, the mold mechanism 5 includes an upper mold 51 and a lower mold 52 connected to the mold closing mechanism 3. After the upper mold 51 and the lower mold 52 are closed, a cavity is formed inside. The cavity includes a first mold cavity 53 for die casting the wheel hub 11 and a second mold cavity 54 for die casting the wheel spokes 12.

[0058] Specifically, such as Figure 7 - Figure 12 As shown, the number of second mold cavities 54 is set according to the number of spokes 12. In this embodiment, three sets are provided. The first casting part 64 has three sets, which respectively deliver magnesium alloy solution to the first mold cavity 53 and the two sets of second mold cavities 54. The second casting part 65 has two sets, which respectively deliver magnesium alloy solution to the first mold cavity 53 and the one set of second mold cavities 54. The second mold cavities 54 delivered by the first casting part 64 and the second casting part 65 are not in the same set.

[0059] The first casting part 64 and the second casting part 65 are located inside the upper mold part 51 and extend to the first mold cavity 53 and the second mold cavity 54 opened on one side. The exhaust mechanism 7 is set inside the upper mold part 51 through a pipe, and the exhaust end of the pipe extends into the first mold cavity 53 and the second mold cavity 54. It is distributed on both sides of the first casting part 64 and the second casting part 65, and is used to exhaust the gas inside the first mold cavity 53 and the second mold cavity 54 through a vacuum valve in conjunction with an external vacuum system. The ejection mechanism 8 is located inside the lower mold part 52 and one end extends into the first mold cavity 53 and the second mold cavity 54, and is used to eject the die-cast workpiece. Multiple temperature control modules 9 are located at the bottom of the first mold cavity 53 and the second mold cavity 54 opened in the lower mold part 52.

[0060] In this embodiment, the bottom of the mold clamping mechanism 3 is fixedly connected to the base 1. The mold clamping mechanism 3 includes a first fixing member 31 and a second fixing member 32 fixedly installed on both sides of the base 1. Guide rods 33 are respectively provided around the inner periphery of the first fixing member 31 and the second fixing member 32. Sliding members 34 are slidably connected to the guide rods 33. A driving member 35 is fixedly connected to the side of the first fixing member 31 away from the sliding member 34. The output end of the driving member 35 passes through the first fixing member 31 to the outside of the sliding member 34. The injection mechanism 4 includes a liquid storage member 41 and a driving injection part 42 connected to the bottom of the liquid storage member 41. A piston rod 43 is provided on the side of the driving injection part 42 near the second fixing member 32. An injection cavity 44 is provided on the outer side of the end of the piston rod 43 near the second fixing member 32. The side of the injection cavity 44 away from the piston rod 43 is located inside the second fixing member 32. One side of the driving injection part 42 is fixedly connected to the second fixing member 32.

[0061] Specifically, such as Figure 1 - Figure 6 As shown, the upper mold part 51 is fixedly connected to the side of the second fixing part 32 away from the injection mechanism 4, and the lower mold part 52 is fixedly connected to the side of the sliding part 34 away from the driving part 35. The driving part 35 can be used to drive the sliding part 34 to slide outside the guide rod 33, and at the same time drive the lower mold part 52 to move to the upper mold part 51 to perform mold closing work. The driving part 35 can be set as a hydraulic push rod drive, or it can be set as any other structure that can achieve the same effect. The mold closing mechanism 3 is provided with a protective part 2 on the outside to provide a certain shielding effect for the mold closing mechanism 3 and prevent workers from accidentally touching it. The liquid storage part 41 is used to store magnesium alloy solution and deliver it quantitatively through a solenoid valve. The driving injection part 42 drives the piston rod 43 through the hydraulic system to inject the magnesium alloy solution delivered to the injection chamber 44 into the gating mechanism 6. The mold closing mechanism 3 is existing technology, so it will not be described in detail. The base 1 provides overall support and stability and is made of high-strength steel.

[0062] A lightweight automotive steering wheel magnesium alloy frame die-casting process, the specific steps of which are as follows:

[0063] S1: Material Pretreatment: Trace amounts of rare earth elements are added to the AM60 magnesium alloy to refine the grain size and improve the alloy's high-temperature performance and corrosion resistance. Simultaneously, the magnesium alloy raw material is melted in a vacuum induction furnace to effectively prevent oxidation and combustion. The melting temperature is controlled within the range of 680-710℃, and the following methods are employed... and The mixed gas contains a small amount of HFC-134a, which significantly reduces the greenhouse effect potential;

[0064] S2: Preparation: The steering wheel is divided into three modules: spokes 12, hub 11 and rim 13. The rim 13 is made of magnesium alloy extruded profiles and bent. The extruded profiles are bent into the shape of steering wheel rim 13 by special molds and local reinforcement treatment is carried out. Spokes 12 and hub 11 are die-cast using multi-cavity molds.

[0065] S3: Start of operation: The mold closing mechanism 3 drives the mold mechanism 5 to close stably through the hydraulic system and maintains continuous pressure on the mold mechanism 5. The magnesium alloy solution is transported through the fully enclosed magnesium alloy liquid delivery system in the injection mechanism 4 and is quantitatively delivered by an electromagnetic pump. The delivery error is controlled within ±2%. The delivery pipeline is equipped with an insulation layer and a heating device to ensure that the temperature fluctuation of the magnesium alloy liquid does not exceed ±5℃. The exhaust mechanism 7 is equipped with a micro vacuum valve in the cavity area. The gas in the cavity is actively removed through the external vacuum system, so that the cavity vacuum degree reaches 0.05-0.08MPa, which greatly reduces the air entrapment defect.

[0066] S4: Die Casting Operation: The die casting mechanism first adopts slow injection, with the punch advancing at a low speed, controlled at 0.2-0.3 m / s, to ensure that the magnesium alloy liquid enters the pressure chamber smoothly. When the magnesium alloy liquid reaches the ingate, the punch speed is rapidly increased to 4-5 m / s, and in conjunction with the fan-shaped distribution and gradually expanding setting of the gating mechanism 6, the magnesium alloy liquid fills the cavity within 0.03-0.05 seconds. Immediately after filling, a high pressure of 100-120 MPa is applied and maintained for 2-3 seconds for stable pressure increase. The pressure increase time is dynamically adjusted by the intelligent control system according to the real-time monitoring of the casting temperature field, ensuring that pressure is applied while there is still a liquid phase channel at the solidification front.

[0067] S5: Temperature-controlled ejection: The temperature control module 9 inside the mold mechanism 5 performs zoned temperature control according to the structure of each part of the cavity. After the hub 11 and spoke 12 are die-cast in the cavity, the mold closing mechanism 3 drives the mold mechanism 5 to separate the internal cavity, and the ejection mechanism 8 ejects the die-cast workpiece.

[0068] S6: Post-treatment work: The graded heat treatment includes solution treatment at 410±10℃, holding for 2-3 hours and then rapid water cooling to fully dissolve the strengthening phase. Then, aging treatment is carried out at 175±5℃ for 8-10 hours to uniformly precipitate the strengthening phase and improve the strength and hardness of the alloy. After heat treatment, vibration aging treatment is added. By setting a specific frequency and amplitude (30-50Hz, 0.3-0.5mm), the skeleton is made to resonate, thereby homogenizing the internal stress distribution.

[0069] S7: Assembly work: The wheel rim 13 and wheel spoke 12 and wheel spoke 12 and wheel hub 11 adopt a composite connection method of local press-fit + laser welding. Preliminary positioning is achieved through precise interference fit. Then, laser welding is performed in the connection area, with the weld depth controlled at 1.5-2.0mm. The weld is then subjected to micro-arc oxidation treatment to form a dense oxide film of 10-15μm on the surface. The assembled steering wheel frame is subjected to X-ray flaw detection to detect defects such as internal porosity and shrinkage. Eddy current testing is used to check surface and near-surface cracks. The key dimensions are fully inspected by a three-dimensional measuring machine to ensure that the product meets the design requirements.

[0070] Modular mold design significantly reduces mold complexity and manufacturing costs, enabling production lines to quickly respond to small-batch, diversified market demands. Simultaneously, optimized production processes reduce protective gas consumption and energy usage, lowering the overall production cost per unit. Innovative heat treatment processes maintain the lightweight advantages of magnesium alloys while improving the fatigue life and mechanical properties of the steering wheel, resulting in a static torsional breaking torque exceeding the standard requirement of 300 N·m and an average fatigue life increased from the current 110,000 cycles to over 150,000 cycles. Mold manufacturing costs are reduced by approximately 35%.

[0071] Meanwhile, due to improved process stability, the scrap rate has significantly decreased, the first-pass yield has reached 95%, and the material utilization rate has increased from the traditional 75% to 88%. In terms of environmental protection, the use of a new protective gas formula... Usage is reduced by more than 80%, and greenhouse gas emissions per unit of product are reduced by about 70%.

[0072] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A lightweight automotive steering wheel magnesium alloy frame die-casting process, comprising a mold closing mechanism, an injection mechanism, a mold mechanism, and an ejection mechanism, characterized in that: The mold mechanism has a cavity for processing steering wheels, a gating mechanism for conveying magnesium alloy solution into the cavity, and an exhaust mechanism on both sides of the gating opening. The mold mechanism also has several temperature control modules for controlling the temperature at various points in the cavity. The steps of the lightweight automotive steering wheel magnesium alloy frame die-casting process are as follows: S1: Material pretreatment: Trace amounts of rare earth elements are added to AM60 magnesium alloy. The magnesium alloy raw material is smelted in a vacuum induction furnace. The smelting temperature is controlled within the range of 680-710℃. A mixture of N2 and CO2 gas is used, containing a small amount of HFC-134a. S2: Preparation: The steering wheel is divided into three modules: spokes, hub and rim. The rim is made of magnesium alloy extruded profiles by bending. The spokes and hub are die-cast using multi-cavity molds. S3: Start working: The mold closing mechanism drives the mold mechanism to close and maintain pressure. The magnesium alloy solution is transported through the fully enclosed magnesium alloy liquid delivery system in the injection mechanism and is quantitatively delivered by an electromagnetic pump. The exhaust mechanism is equipped with a micro vacuum valve in the cavity area to actively remove the gas in the cavity through the external vacuum system. S4: Die casting operation: The die casting mechanism first adopts slow injection, with the punch advancing at a low speed. When the magnesium alloy liquid reaches the inner gate, the punch speed is rapidly increased, so that the magnesium alloy liquid fills the cavity in a short time. After the filling is completed, high pressure is immediately applied and maintained to ensure stable pressure. S5: Temperature-controlled ejection: The temperature control module inside the mold mechanism controls the temperature in zones according to the cavity structure. After die casting, the mold is opened and the ejection mechanism ejects the workpiece. S6: Post-treatment work: Graded heat treatment includes solution treatment and aging treatment; S7: Assembly work: The wheel rim and spokes and the spokes and hub are locally pressed in and laser welded, and the welds are micro-arc oxidation treatment.

2. The lightweight automotive steering wheel magnesium alloy frame die-casting process according to claim 1, characterized in that: In the material pretreatment step, rare earth elements are added to refine the grains, improve the high-temperature performance and corrosion resistance of the alloy, vacuum melting effectively prevents oxidation and combustion, and the mixed gas significantly reduces the greenhouse effect potential. In the preparation steps, the extruded profile is bent into the shape of a steering wheel rim using a special mold and then subjected to localized reinforcement treatment; During the initial working steps, the conveying error is controlled within ±2%. The conveying pipeline is equipped with an insulation layer and a heating device to ensure that the temperature fluctuation of the magnesium alloy liquid does not exceed ±5℃. The exhaust gas makes the cavity vacuum degree reach 0.05-0.08MPa. In the die casting process, the slow injection speed is controlled at 0.2-0.3 m / s; after reaching the inner gate, the punch speed is rapidly increased to 4-5 m / s; the filling time is 0.03-0.05 seconds; the high pressure is 100-120 MPa, and it is maintained for 2-3 seconds for stable pressure increase. The pressure increase time is dynamically adjusted by the intelligent control system according to the real-time monitoring of the casting temperature field to ensure that pressure is applied while there is still a liquid phase channel at the solidification front. In the post-treatment process, the solution treatment temperature is 410±10℃, and after holding at this temperature for 2-3 hours, it is rapidly water-cooled; the aging treatment temperature is 175±5℃, and after holding at this temperature for 8-10 hours; after heat treatment, vibration aging treatment is added, by setting the frequency to 30-50Hz and the amplitude to 0.3-0.5mm, so that the skeleton can resonate and the internal stress distribution can be homogenized. During the assembly process, preliminary positioning is achieved through precise interference fit, and the laser welding depth is controlled at 1.5-2.0mm; micro-arc oxidation treatment forms a dense oxide film of 10-15μm on the weld surface.

3. The lightweight automotive steering wheel magnesium alloy frame die-casting process according to claim 1, characterized in that: The gating mechanism includes a main gating located inside the mold mechanism and connected at one end to the injection mechanism. The end of the main gating away from the injection mechanism is connected to a first branch gating and a second branch gating distributed in a fan shape. The end of the first branch gating away from the main gating is connected to several sets of first casting elements for conveying magnesium alloy solution to the cavity. The end of the second branch gating away from the main gating is connected to several sets of second casting elements for conveying magnesium alloy solution to the cavity.

4. The lightweight automotive steering wheel magnesium alloy frame die-casting process according to claim 3, characterized in that: The size of the first branch gating is larger than that of the second branch gating, the number of first casting parts is greater than that of the second casting parts, the first branch gating includes a gradually expanding section and a rectangular section formed by the gradual transition of the expanding section, the end of the rectangular section away from the expanding section is set as a contracting section, and several sets of guide grooves are opened on both sides inside the rectangular section.

5. The lightweight automotive steering wheel magnesium alloy frame die-casting process according to claim 3, characterized in that: The mold mechanism includes an upper mold and a lower mold connected to a mold closing mechanism. After the upper mold and the lower mold are closed, a cavity is formed inside. The cavity includes a first mold cavity for die-casting the wheel hub and a second mold cavity for die-casting the wheel spokes.

6. The lightweight automotive steering wheel magnesium alloy frame die-casting process according to claim 5, characterized in that: The first casting component and the second casting component are located inside the upper mold and extend to the first mold cavity and the second mold cavity opened on one side. The exhaust mechanism is located inside the upper mold and distributed on both sides of the first casting component and the second casting component. It is used to exhaust the gas inside the first mold cavity and the second mold cavity through the vacuum valve in conjunction with the external vacuum system. The ejection mechanism is located inside the lower mold and one end extends to the first mold cavity and the second mold cavity respectively. It is used to eject the die-cast workpiece. Multiple temperature control modules are located at the bottom of the first mold cavity and the second mold cavity opened in the lower mold.

7. The lightweight automotive steering wheel magnesium alloy frame die-casting process according to claim 5, characterized in that: The bottom of the mold closing mechanism is fixedly connected to a base. The mold closing mechanism includes a first fixing member and a second fixing member fixedly installed on both sides of the base. Guide rods are provided on the inner periphery of the first fixing member and the second fixing member respectively. Sliding members are slidably connected on the guide rods. A driving member is fixedly connected to the side of the first fixing member away from the sliding member. The output end of the driving member passes through the first fixing member to the outside of the sliding member.

8. The lightweight automotive steering wheel magnesium alloy frame die-casting process according to claim 6, characterized in that: The upper mold is fixedly connected to the side of the second fixing member away from the injection mechanism, the lower mold is fixedly connected to the side of the sliding member away from the driving member, and a protective member is provided on the outside of the mold closing mechanism.

9. The lightweight automotive steering wheel magnesium alloy frame die-casting process according to claim 8, characterized in that: The injection mechanism includes a liquid storage component and a driving injection part connected to the bottom of the liquid storage component. The driving injection part has a piston rod on the side near the second fixed component. An injection cavity is provided on the outer side of the end of the piston rod near the second fixed component. The side of the injection cavity away from the piston rod is located inside the second fixed component. One side of the driving injection part is fixedly connected to the second fixed component.

10. The lightweight automotive steering wheel magnesium alloy frame die-casting process according to claim 1, characterized in that: The outer side of the wheel hub has several sets of first slots, and the outer side of the wheel rim has several sets of second slots.

Images