Optimized design method for casting magnesium alloy wheel

Abstract

The application discloses an optimized design method for casting magnesium alloy wheels, comprising the following steps: setting an exhaust unit on the top surface of a casting mold; expanding the distance between the upper cross gate of the casting mold and the wheel hub to a preset size; setting the bottom mold, side mold and upper mold of the casting mold into metal materials, and setting the lower mold of the casting mold into a resin sand core; controlling the pouring temperature to be 770-780 DEG C, and controlling the liquid rising speed to be 80 mm / s and the liquid rising pressure to be 25 KPa; the exhaust unit set on the top surface of the casting mold enables the gas in the wheel hub casting process to be smoothly discharged from the mold, and the distance between the upper cross gate of the mold and the wheel hub is changed, so that the loose defects caused by the excessively high pouring temperature are avoided; the resin sand core is used to solve the hot cracking defects of the wheel hub in the cooling process, widen the mold temperature control range of the metal mold, enhance the melt cooling strength, obtain a relatively dense grain structure, and improve the mechanical properties; and the hot cracking, shrinkage cavity and loose defects in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of wheel casting technology, and in particular to an optimized design method for casting magnesium alloy wheels. Background Technology

[0002] A wheel hub is a cylindrical metal component that supports the tire's inner contour and is mounted on the axle. It is also called a steel rim or wheel rim. In the manufacturing process of wheel hubs, molten metal is usually poured into a mold and processed by extrusion casting.

[0003] Currently, automotive wheels are primarily made of aluminum alloy. Due to their light weight, good heat dissipation, and high dimensional accuracy, they have become the best choice for meeting the requirements of lightweight and energy-saving automotive development. During processing, the diameter of the aluminum alloy wheel is adjusted according to the specific vehicle dimensions, allowing for the adjustment or replacement of the extrusion casting mold, leading to its widespread use. Therefore, the design of metal molds, pressure casting, and mass production of cast aluminum alloy wheels have entered a standardized and stable stage. However, within the specified cost range, the current wheel casting process still suffers from defects such as heat generation, shrinkage cracking, and porosity at the hot joints of the wheel spokes and rim. Furthermore, mass production is not feasible, as batch production results in wheels with coarse grains, poor mechanical properties, difficulty in venting gases during casting, and slow solidification rates. Summary of the Invention

[0004] To address some or all of the technical problems existing in the prior art, this invention provides an optimized design method for casting magnesium alloy wheel hubs and casting aluminum alloy automotive engine housings. The method combines a metal outer mold and a resin sand core to assemble the housing structure, and manufactures it using weight and pressure casting. This method solves the problem of difficult demolding of the metal mold inside the housing, and improves the production efficiency and performance of the product.

[0005] The technical solution of the present invention is as follows:

[0006] This invention provides an optimized design method for cast magnesium alloy wheel hubs, comprising:

[0007] An exhaust unit is installed on the top surface of the casting mold;

[0008] Increase the distance between the upper runner of the casting mold and the casting hub to the preset size;

[0009] The bottom mold, side mold, and upper mold of the casting mold are made of metal, and the lower mold of the casting mold is made of resin sand core.

[0010] The casting temperature is controlled at 770-780℃, the casting liquid rising speed is controlled at 80mm / s, and the liquid rising pressure is controlled at 25KPa.

[0011] Furthermore, in the above-mentioned optimized design method for casting magnesium alloy wheels, the exhaust unit includes an exhaust groove or exhaust hole provided on the top surface of the casting mold.

[0012] Furthermore, in the above-mentioned optimized design method for casting magnesium alloy wheel hubs, the number of exhaust grooves or exhaust holes is several, and the several exhaust grooves or exhaust holes are distributed at intervals along the shape of the casting wheel hub on the top surface of the casting mold.

[0013] Furthermore, in the above-mentioned optimized design method for casting magnesium alloy wheels, the bottom mold, side mold, and upper mold of the casting mold are set to be any one of magnesium alloy, aluminum alloy, or magnesium-aluminum alloy.

[0014] Furthermore, in the above-mentioned optimized design method for casting magnesium alloy wheels, increasing the distance between the sprue on the casting mold and the casting wheel to a preset size includes setting the distance between the sprue and the casting wheel to 20-45mm.

[0015] Furthermore, in the above-mentioned optimized design method for cast magnesium alloy wheels, the optimized cast magnesium alloy wheel has a tensile strength ≥250RM / MPa, a yield strength ≥130RP0.2 / MPa, and an elongation after fracture ≥6.

[0016] The main advantages of the technical solution of this invention are as follows:

[0017] This invention provides an optimized design method for casting magnesium alloy wheels. By incorporating an exhaust unit on the top surface of the casting mold, gas can be smoothly expelled from the mold during the wheel casting process. By altering the distance between the upper sprue and the cast wheel hub, defects caused by excessively high casting temperatures, such as porosity, are avoided. The use of resin sand cores solves the problem of hot cracking during cooling and broadens the control range of the metal mold temperature, enhancing melt cooling intensity, resulting in a denser grain structure and improved mechanical properties. By combining two different mold materials, different effects are achieved: rapid cooling and solidification of the melt at the metal mold interface, and slower cooling and solidification at the sand mold interface. Pressure transmission can achieve a feeding effect, resolving hot cracking, shrinkage cavities, and porosity defects. Furthermore, the method is low-cost, ensuring cost compliance while enabling mass production. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and constitute a part of this invention, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0019] Figure 1This is a flowchart illustrating an optimized design method for casting magnesium alloy wheels according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the casting structure in an optimized design method for casting magnesium alloy wheel hubs provided in an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the sand core structure in an optimized design method for casting magnesium alloy wheel hubs according to an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of the metal mold structure in an optimized design method for casting magnesium alloy wheels according to an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram of the casting system design in an optimized design method for casting magnesium alloy wheels according to an embodiment of the present invention.

[0024] Figure 6 This is a schematic diagram of the sampling area during the mechanical property testing of a sample in an optimized design method for cast magnesium alloy wheel hubs provided in an embodiment of the present invention.

[0025] Figure 7 This is a schematic diagram of the detection of the first region of a casting sample in an optimized design method for casting magnesium alloy wheel hubs according to an embodiment of the present invention.

[0026] Figure 8 This is a schematic diagram of the second region detection of a casting sample in an optimized design method for casting magnesium alloy wheel hubs according to an embodiment of the present invention.

[0027] Figure 9 This is a schematic diagram of the third region detection of a casting sample in an optimized design method for casting magnesium alloy wheel hubs according to an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] The technical solutions provided by the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0030] As attached Figure 1-9 As shown in the figure, an embodiment of the present invention provides an optimized design method for cast magnesium alloy wheel hubs, the method comprising:

[0031] An exhaust unit is installed on the top surface of the casting mold; the distance between the upper horizontal runner of the casting mold and the casting hub is increased to the preset size; the bottom mold, side mold, and upper mold of the casting mold are made of metal materials, and the lower mold of the casting mold is made of resin sand core; the casting temperature is controlled at 770-780℃, the casting liquid rising speed is controlled at 80mm / s, and the liquid rising pressure is controlled at 25KPa.

[0032] This design, with an exhaust unit on the top surface of the casting mold, allows gas to escape smoothly during the wheel hub casting process. By changing the distance between the upper sprue of the mold and the cast wheel hub, defects caused by excessively high casting temperatures, such as porosity, are avoided. Using two different mold materials achieves different effects: the metal mold interface allows for rapid cooling and solidification of the melt, while the sand mold interface allows for slower cooling and solidification. Pressure transmission can then be used to achieve a feeding effect, resolving defects such as hot cracking, shrinkage cavities, and porosity.

[0033] Specifically, the metal materials of the bottom mold, side mold, and upper mold of the casting mold can be steel, cast iron, aluminum or aluminum alloy, magnesium or magnesium alloy, and magnesium-aluminum alloy, etc.

[0034] To further explain how the different effects are achieved by using molds made of two different materials, specifically, cast iron metal molds are widely used in the quenching process of magnesium alloy castings due to their high cooling intensity and strong heat storage capacity. The use of two different materials in the molds is due to the density difference between the two materials, which creates a steeper cooling gradient. Resin sand cores, made primarily of silica sand, possess unique thermal insulation properties, providing heat preservation during molten metal solidification and enhancing the fluidity and feeding strength of the molten metal. The combination of cast iron metal molds and resin sand cores achieves sequential solidification, meaning that the parts of the casting furthest from the riser solidify first, then the parts closer to the riser solidify, and finally the riser itself solidifies, thus providing feeding and preventing shrinkage cavities and porosity defects. Simultaneously, by using two different materials in the molds to achieve sequential solidification, the invention reduces casting stress and prevents hot and cold cracks.

[0035] Specifically, in the optimized design method for casting magnesium alloy wheels of the present invention, the exhaust unit includes an exhaust groove or exhaust hole provided on the top surface of the casting mold.

[0036] Preferably, in the optimized design method for casting magnesium alloy wheel hubs of the present invention, the number of venting grooves or venting holes is several, and the several venting grooves or venting holes are distributed at intervals along the shape of the casting wheel hub on the top surface of the casting mold.

[0037] In some optional implementations of this embodiment, the venting unit on the top surface of the casting mold is set as a venting groove. Preferably, the size of the venting groove is set to 2×3mm and distributed at intervals of 30mm. This setting enables the rapid discharge of gas during the casting process of the wheel hub through the action of the venting groove, avoiding defects such as loosening and cracking caused by excessive temperature due to the large accumulation of gas or untimely discharge during the casting process.

[0038] Specifically, in the optimized design method for casting magnesium alloy wheels according to the present invention, the bottom mold, side mold, and upper mold of the casting mold are made of metal materials, including any one of magnesium alloy, aluminum alloy, or magnesium-aluminum alloy. Magnesium alloy is the most preferred.

[0039] Specifically, in the optimized design method for casting magnesium alloy wheels in this invention, in order to further accelerate the gas discharge during the casting process and avoid porosity defects caused by excessively high gate temperature, the distance between the horizontal runner on the casting mold and the casting wheel hub is increased to a preset size. This includes setting the distance between the horizontal runner and the casting wheel hub to 15-60mm, preferably setting the distance between the two to 20-50mm, and most preferably setting the distance between the two to 20-45mm.

[0040] Specifically, using the optimized design method of the present invention for casting magnesium alloy wheels, the optimized cast magnesium alloy wheel has a tensile strength ≥250RM / MPa, a yield strength ≥130RP0.2 / MPa, and an elongation after fracture ≥6.

[0041] Specifically, as an example, based on the composition and mechanical property requirements of GB / T 26654 "Specification for Magnesium Alloy Castings" and "Cast Magnesium Alloys for Automobile Wheels", taking ZM203 material as an example, the above-mentioned optimized design method for casting magnesium alloy wheel hubs of the present invention is used to cast magnesium alloy wheel hubs. Table 1 below shows the composition and content of ZM203 material; Table 2 shows the allowable content (%) of impurities in ZM203 alloy; Table 3 shows the mechanical property requirements of ZM203 magnesium alloy wheel hubs.

[0042] Table 1: Components and content of ZM203 material

[0043]

[0044]

[0045] Table 2: Permissible Impurity Content (%) in ZM203 Alloy

[0046]

[0047] Table 3: Mechanical Performance Requirements of ZM203 Wheel Hubs

[0048] project <![CDATA[Tensile strength σ b , MPa]]> <![CDATA[Yield strength σ 0.2 , MPa]]> Elongation δ5, % Brinell hardness / HBW Ontology sampling ≥220 ≥130 ≥5 ≥65

[0049] Specifically, the method for optimizing the design of magnesium alloy wheels according to the present invention includes the following steps:

[0050] Based on magnesium alloy sand casting technology, the casting magnesium alloy wheel hub blank is designed, the gating system is designed and trial-produced, and the process direction and scheme are determined.

[0051] Specifically, the purpose of the above-mentioned design for the cast magnesium alloy wheel hub blank is to enable the wheel hub blank and the gating system to solidify sequentially, that is, to make the part of the casting away from the riser solidify first, then the part near the riser solidify, and finally the riser itself solidifies, thereby achieving the effects of feeding, preventing shrinkage cavities and porosity defects, reducing casting stress, and preventing hot cracks and cold cracks. According to the technical means of the present invention, the bottom mold, side mold and upper mold of the casting mold are made of metal materials, and the lower mold of the casting mold is made of resin sand core, etc., the process flow can be set as: core making - metal mold heating - assembly - melting and pouring - demolding.

[0052] The casting process parameters are determined based on the designed process direction and scheme. The determined process parameters are shown in Table 4 below.

[0053] Table 4: Casting parameters for magnesium alloy wheels

[0054]

[0055] Magnesium alloy wheels are cast according to the designed process scheme and determined process parameters, and the cast magnesium alloy wheel samples are tested.

[0056] In some optional implementations of this embodiment, to facilitate the inspection of the cast sample and to make the inspected structure more accurate, fluorescence can be used to detect the surface quality, and X-rays can be used to detect the internal quality of the casting; such as Figure 6 The diagram shown illustrates the sampling area for testing the mechanical properties of a sample in an optimized design method for cast magnesium alloy wheel hubs according to an embodiment of the present invention. Figures 7-9 The diagrams shown illustrate the detection of the first, second, and third regions of a cast sample in an optimized design method for casting magnesium alloy wheel hubs according to an embodiment of the present invention.

[0057] Based on the test results, the designed scheme and process parameters are further optimized; including:

[0058] Optimize the venting system on the top surface of the casting to allow gas to be smoothly discharged from the mold.

[0059] The distance between the sprue and the casting is adjusted to prevent porosity defects caused by excessively high gate temperatures. The optimized mold structure is as follows: Figures 2-5 As shown.

[0060] Specifically, the aforementioned optimized design scheme includes at least a magnesium alloy metal mold design: the bottom mold, side mold, and upper mold are made of metal molds, while the lower mold uses a resin sand core. Using these two different materials achieves different effects: the metal mold interface allows for rapid cooling and solidification of the melt, while the sand mold interface allows for slower cooling and solidification of the melt. Pressure transmission can then be used to achieve a feeding effect, resolving defects such as hot cracking, shrinkage cavities, and porosity.

[0061] The process casting parameters were further determined for the optimized design scheme. The determined process casting parameters are shown in Table 5 below.

[0062] Table 5: Process casting parameters of the optimized design scheme

[0063]

[0064] The wheel hubs with the above-mentioned improved process scheme and casting process parameters were inspected. After using fluorescence to detect the surface quality and X-ray to detect the internal quality of the casting, the test results showed that they met the preset casting quality requirements. The results of the mechanical property test are shown in Table 6 below.

[0065] Table 6: Mechanical properties of cast magnesium alloy wheels tested using the optimized design method of this invention.

[0066]

[0067] Therefore, it can be seen that casting magnesium alloy wheels using the above-mentioned method of the present invention can prevent defects such as cracking from occurring in the cast wheels, and can simultaneously meet the preset mechanical performance requirements.

[0068] In summary, the optimized design method for casting magnesium alloy wheels of the present invention, by setting an exhaust unit on the top surface of the casting mold, allows gas to be smoothly discharged from the mold during the wheel casting process. By changing the distance between the horizontal runner on the mold and the cast wheel hub, the porosity defect caused by excessively high casting temperature is avoided. By using resin sand cores, the hot cracking defect during the cooling process of the wheel hub is solved, and the control range of the metal mold temperature is broadened, enhancing the cooling intensity of the melt, obtaining a denser grain structure, and improving mechanical properties. By combining the above two different mold materials, different effects are achieved: rapid cooling and solidification of the melt at the metal mold interface, and slow cooling and solidification of the melt at the sand mold interface. Pressure transmission can achieve a feeding effect, solving hot cracking, shrinkage cavities, and porosity defects, while maintaining low cost and enabling mass production while meeting cost requirements.

[0069] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Additionally, the terms "front," "back," "left," "right," "upper," and "lower" in this document refer to the placement shown in the accompanying drawings.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optimized design method for cast magnesium alloy wheel hubs, characterized in that, include: An exhaust unit is installed on the top surface of the casting mold; The venting unit includes venting grooves provided on the top surface of the casting mold; The number of exhaust grooves is several, and the size of the exhaust grooves is set to 2×3mm. The exhaust grooves are distributed at intervals of 30mm along the shape of the casting hub on the top surface of the casting mold. This allows the gas to be quickly discharged during the casting process through the exhaust grooves, avoiding the defects of loosening and cracking caused by excessive temperature due to the large accumulation of gas or untimely discharge during the casting process. Increase the distance between the upper runner of the casting mold and the casting hub to the preset size; Set the distance between the runner and the cast wheel hub to 20-45mm. The bottom mold, side mold, and upper mold of the casting mold are made of metal, and the lower mold of the casting mold is made of resin sand core. By using magnesium alloy for the bottom mold, side mold, and top mold of the casting mold, the heat preservation effect can be achieved during the solidification process of the melt, which enhances the fluidity and feeding strength of the melt and achieves the purpose of sequential solidification. This allows the parts of the casting away from the riser to solidify first, then the parts closer to the riser to solidify, and finally the riser itself to solidify. This provides feeding and prevents shrinkage cavities and porosity defects. At the same time, by using two molds made of different materials to achieve the sequential solidification process, the casting stress can be reduced and hot cracks and cold cracks can be prevented. The casting temperature is controlled at 770-780℃, the casting liquid rising speed is controlled at 80mm / s, and the liquid rising pressure is controlled at 25KPa.

2. The optimized design method for cast magnesium alloy wheel hubs according to claim 1, characterized in that, The optimized design of the cast magnesium alloy wheel hub has a tensile strength ≥250 R. M / MPa, yield strength ≥130 R P0.2 / MPa, elongation after fracture ≥6.

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