Optimization design method for casting magnesium alloy hub

Abstract

The invention discloses an optimization design method for casting a magnesium alloy hub. The optimization design method comprises the steps that an exhaust unit is arranged on the top face of a casting mold; the distance between a cross gate on the casting mold and the casting hub is increased to a preset size; a bottom die, a side die and an upper die of the casting die are made of metal materials, and a lower die of the casting die is a resin sand core; the casting temperature is controlled to be 770-780 DEG C, the casting liquid rising speed is controlled to be 80 mm / s, the liquid rising pressure is controlled to be 25 KPa, the exhaust unit is arranged on the top face of the casting mold, gas in the hub casting process can be smoothly exhausted out of the casting mold, and the defect of looseness caused by the too high casting temperature is avoided by changing the distance between the cross gate on the mold and the casting hub. By using the resin sand core, the hot crack defect of the hub in the cooling process is overcome, the control range of the mold temperature of a metal mold is widened, the melt cooling strength is enhanced, a compact grain structure is obtained, and the mechanical property is improved. The defects of hot cracking, shrinkage cavity and looseness in the prior art are overcome.

Description

Technical Field

[0001] The invention relates to the technical field of wheel hub casting, and in particular to an optimization design method for casting a magnesium alloy wheel hub. Background Art

[0002] The wheel hub is a metal component that supports the tire with its inner profile. It is cylindrical in shape and its center is mounted on an axle. It is also called a steel rim, wheel rim, etc. During the processing and production of the wheel hub, molten metal is usually poured into a mold and processed by extrusion casting.

[0003] The existing automobile wheel hubs are mainly aluminum alloy wheels. Due to their light weight, good heat dissipation and high dimensional accuracy, they have become the best choice for the development of lightweight and energy-saving automobiles. During the processing, the diameter of the aluminum alloy wheel hub can be adjusted according to the size of the specific vehicle, and the extrusion casting mold can be adjusted or replaced, so they are widely used. Therefore, the metal mold design, pressure casting and batch production of cast aluminum alloy wheels have entered a standardized and stabilized stage at this stage. However, within the specified cost range, the current casting process of the wheel hub still has defects such as heat, shrinkage cracks, and looseness at the hot joints of the wheel hub spokes and the rim. At the same time, it is impossible to mass-produce. In batch preparation, there are defects such as coarse grains of the cast wheel hub structure, poor mechanical properties, difficult discharge of gas during the casting process, and slow solidification rate. Summary of the invention

[0004] In order to solve some or all of the technical problems existing in the above-mentioned prior art, the present invention provides an optimized design method for casting a magnesium alloy wheel hub, a casting aluminum alloy automobile engine case, a metal mold outer mold and a resin sand core are combined to assemble into a case structure, and weight and pressure casting are used for production and manufacturing. In this way, the problem that the metal mold in the inner cavity of the case is difficult to demold is solved, and the production efficiency and performance of the product are improved.

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

[0006] The present invention provides an optimization design method for casting a magnesium alloy wheel hub, comprising:

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

[0008] Enlarge the distance between the runner on 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 set to metal materials, and the lower mold of the casting mold is set to a resin sand core;

[0010] The casting temperature is controlled at 770-780°C, 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 optimization design method for casting a magnesium alloy wheel hub, the exhaust unit includes an exhaust groove or an exhaust hole provided on the top surface of the casting mold.

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

[0013] Furthermore, in the above-mentioned optimization design method for casting a magnesium alloy wheel hub, the bottom mold, the side mold and the 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 optimization design method for casting a magnesium alloy wheel hub, increasing the distance between the runner on the casting mold and the casting wheel hub to a preset size includes setting the distance between the runner and the casting wheel hub to 20-45 mm.

[0015] Furthermore, in the above-mentioned optimization design method for casting magnesium alloy wheel hub, the tensile strength of the optimized cast magnesium alloy wheel hub is ≥250RM / MPa, the yield strength is ≥130RP0.2 / MPa, and the elongation after fracture is ≥6.

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

[0017] The optimization design method for casting magnesium alloy wheel hubs of the present invention, by arranging an exhaust unit on the top surface of the casting mold, allows the gas in the process of wheel hub casting to be smoothly discharged from the casting mold, and by changing the distance between the cross runner on the mold and the casting wheel hub, the defect of looseness caused by excessive casting temperature is avoided. By using resin sand cores, the thermal cracking defect of the wheel hub during cooling is solved and the control range of the metal mold temperature is widened, the melt cooling strength is enhanced, a denser grain structure is obtained, and the mechanical properties are improved. The above two casting molds of different materials are used in combination to achieve different effects. The melt is cooled and solidified quickly at the metal mold interface, and the melt is cooled and solidified slowly at the sand mold interface. The shrinkage compensation effect can be achieved through pressure transmission, and the thermal cracking, shrinkage cavity, and looseness defects are solved. The cost is low, and mass production can be achieved while ensuring cost requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the embodiments of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0019] Figure 1A schematic flow chart of an optimization design method for casting a magnesium alloy wheel hub according to an embodiment of the present invention;

[0020] Figure 2 A schematic diagram of a casting structure in an optimization design method for casting a magnesium alloy wheel hub provided in one embodiment of the present invention;

[0021] Figure 3 A schematic diagram of a sand core structure in an optimization design method for casting a magnesium alloy wheel hub provided in one embodiment of the present invention;

[0022] Figure 4 A schematic diagram of the structure of a metal mold in an optimization design method for casting a magnesium alloy wheel hub provided by an embodiment of the present invention;

[0023] Figure 5 A schematic structural diagram of a casting system design in an optimization design method for casting a magnesium alloy wheel hub provided in one embodiment of the present invention;

[0024] Figure 6 A schematic diagram of a sampling area for testing the mechanical properties of a sample in an optimization design method for a cast magnesium alloy wheel hub provided by an embodiment of the present invention;

[0025] Figure 7 A schematic diagram of detecting the first area of ​​a casting sample in an optimization design method for casting a magnesium alloy wheel hub provided by an embodiment of the present invention;

[0026] Figure 8 A schematic diagram of detecting the second area of ​​a casting sample in an optimization design method for casting a magnesium alloy wheel hub provided by an embodiment of the present invention;

[0027] Fig. 9 A schematic diagram of detecting the third area of ​​a casting sample in an optimization design method for casting a magnesium alloy wheel hub provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

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

[0030] As attached Figure 1-9 As shown, an embodiment of the present invention provides an optimization design method for casting a magnesium alloy wheel hub, the method comprising:

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

[0032] In this way, by setting an exhaust unit on the top surface of the casting mold, the gas in the process of wheel hub casting can be smoothly discharged from the casting mold, and by changing the distance between the cross runner on the mold and the casting wheel hub, the defect of looseness caused by excessive casting temperature is avoided. By using the above two casting molds of different materials, different effects are achieved. The melt is cooled and solidified quickly at the metal mold interface, and the melt is cooled and solidified slowly at the sand mold interface. The shrinkage compensation effect can be achieved through pressure transmission to solve the defects of thermal cracking, shrinkage holes and looseness.

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

[0034] The above is a further explanation of how to achieve different effects by using the above two different materials of casting molds. Specifically, due to the high cooling strength and heat storage capacity of the cast iron metal mold, it has been widely used in the quenching process of magnesium alloy castings. The above two different materials of casting molds are set because the density difference between the two materials can form a steeper cooling gradient. The resin sand core is a casting material mainly composed of silica sand. Its unique material property is insulation. It can play a role in heat preservation during the solidification process of the solution, enhancing the fluidity and shrinkage compensation strength of the solution. The combination of two different materials of casting molds, cast iron metal mold and resin sand core, achieves the purpose of sequential solidification, that is, the part of the casting away from the riser solidifies first, then the part close to the riser solidifies, and finally the riser itself solidifies, thereby playing a role in shrinkage compensation and preventing shrinkage cavities and shrinkage defects; at the same time, by setting two different materials of casting molds in the present invention to achieve the process of sequential solidification, it plays an effect of reducing casting stress and preventing the generation of hot cracks and cold cracks.

[0035] Specifically, in the optimization design method for casting a magnesium alloy wheel hub of the present invention, the exhaust unit includes providing an exhaust groove or an exhaust hole on the top surface of the casting mold.

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

[0037] In some optional implementations of the present embodiment, the exhaust unit on the top surface of the casting surface mold is set as an exhaust groove. Preferably, the size of the exhaust groove is set to 2×3 mm and is distributed at intervals of 30 mm. Such a setting allows the exhaust groove to quickly discharge gas during the casting process of the wheel hub, thereby avoiding the defects of looseness and cracking caused by excessive temperature due to large-scale accumulation of gas or untimely discharge during the casting process.

[0038] Specifically, in the optimization design method for casting magnesium alloy wheel hubs in the present invention, the bottom mold, side mold and upper mold of the casting mold are set to metal materials, including any one of magnesium alloy, aluminum alloy or magnesium-aluminum alloy, and magnesium alloy is most preferred.

[0039] Specifically, in the optimization design method for casting a magnesium alloy wheel hub in the present invention, in order to further accelerate the gas discharge during the casting process and avoid the looseness defect caused by excessively high gate temperature, the distance between the cross runner on the casting mold and the casting wheel hub is expanded to a preset size, including setting the distance between the cross 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, by adopting the optimization design method for casting magnesium alloy wheel hub of the present invention, the tensile strength of the optimized cast magnesium alloy wheel hub is ≥250RM / MPa, the yield strength is ≥130RP0.2 / MPa, and the elongation after fracture is ≥6.

[0041] Specifically, as an example, according to the composition and mechanical property requirements of GB / T 26654 "Specification for Magnesium Alloy Castings" and "Casting Magnesium Alloy for Automobile Wheels", taking ZM203 material as an example, the above-mentioned optimization design method for casting magnesium alloy wheel hubs of the present invention is adopted to cast magnesium alloy wheel hubs. The following Table 1 shows the components and contents of ZM203 material; Table 2 shows the allowable impurity content (%) of ZM203 alloy; Table 3 shows the mechanical property requirements of ZM203 magnesium alloy wheel hubs.

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

[0043]

[0044]

[0045] Table 2: Allowable impurity content of ZM203 alloy (%)

[0046]

[0047] Table 3: Mechanical performance requirements of ZM203 wheel hub

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

[0049] Specifically, the above-mentioned optimized design method for casting a magnesium alloy wheel hub of the present invention is used to cast a magnesium alloy wheel hub having the components and properties shown in Tables 1 to 3, including the following steps:

[0050] Based on the magnesium alloy sand casting technology, the blank of the cast magnesium alloy wheel hub is designed, the casting system is designed and trial-produced, and the process direction and plan are determined;

[0051] Specifically, the purpose of designing the cast magnesium alloy wheel hub blank is to make the wheel hub blank and the pouring system solidify sequentially, that is, the part of the casting away from the riser solidifies first, then the part close to the riser solidifies, and finally the riser itself solidifies, so as to compensate for shrinkage, prevent shrinkage holes and shrinkage defects, reduce casting stress, and prevent hot cracking and cold cracking. According to the present invention, the bottom mold, side mold, and upper mold of the casting mold are set to metal materials, and the lower mold of the casting mold is set to resin sand core. The process flow can be set to: core making-metal mold heating-assembly-melting and pouring-molding.

[0052] The casting process parameters are determined according to the designed process direction and scheme, and the determined process parameters are shown in Table 4 below;

[0053] Table 4: Process casting parameters of magnesium alloy wheels

[0054]

[0055] Casting the magnesium alloy wheel hub according to the designed process scheme and the determined process parameters, and testing the cast magnesium alloy wheel hub samples;

[0056] In some optional implementations of this embodiment, in order to facilitate the detection of the cast sample and make the detected 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; Figure 6 FIG. 1 is a schematic diagram of a sampling area for testing the mechanical properties of a sample in an optimization design method for a cast magnesium alloy wheel hub provided in an embodiment of the present invention; Figure 7-Figure 9 , which respectively represent schematic diagrams of detecting the first area, the second area and the third area of ​​the casting sample in the optimization design method for casting a magnesium alloy wheel hub provided by an embodiment of the present invention.

[0057] According to the designed scheme and process parameters, the designed scheme is further optimized according to the test results; including:

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

[0059] Change the distance between the runner and the casting to avoid the looseness defect caused by excessively high gate temperature. Figure 2-Figure 5 shown.

[0060] Specifically, the above-mentioned optimization design scheme at least includes a magnesium alloy metal mold design scheme: the bottom mold, side mold, and upper mold of the mold are made of metal molds, and the lower mold is made of resin sand core. Using these two different materials of casting molds can achieve different effects, and the melt is cooled and solidified quickly at the metal mold interface, and the melt is cooled and solidified slowly at the sand mold interface. The shrinkage compensation effect can be achieved through pressure transmission, and the defects of thermal cracking, shrinkage cavity, and looseness can be solved.

[0061] The process casting parameters are further determined according to the optimized design scheme, and 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 hub with the above improved process scheme and casting process parameters was tested. After using fluorescence to detect the surface quality and X-ray to detect the internal quality of the casting, the test results showed that it met the preset casting quality requirements. The results of the mechanical properties test are shown in Table 6 below.

[0065] Table 6: Mechanical properties of the wheel hubs cast using the optimized design method for casting magnesium alloy wheel hubs of the present invention

[0066]

[0067] It can be seen that the use of the above method of the present invention to cast a magnesium alloy wheel hub can prevent defects such as cracking in the cast wheel hub and can also meet the preset mechanical performance requirements.

[0068] In summary, the optimization design method for casting magnesium alloy wheel hubs of the present invention, by setting an exhaust unit on the top surface of the casting mold, allows the gas in the process of wheel hub casting to be smoothly discharged from the casting mold, and by changing the distance between the cross runner on the mold and the casting wheel hub, the defect of looseness caused by excessive casting temperature is avoided. By using resin sand cores, the thermal cracking defect of the wheel hub during cooling is solved and the control range of the metal mold temperature is widened, the melt cooling strength is enhanced, a denser grain structure is obtained, and the mechanical properties are improved. The above two casting molds of different materials are used in combination to achieve different effects. The melt is cooled and solidified quickly at the metal mold interface, and the melt is cooled and solidified slowly at the sand mold interface. The shrinkage compensation effect can be achieved through pressure transmission, and the thermal cracking, shrinkage cavity, and looseness defects are solved. The cost is low, and mass production can be achieved while ensuring cost requirements.

[0069] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In addition, "front", "back", "left", "right", "upper" and "lower" in this article are all referenced to the placement state 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, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optimization design method for casting a magnesium alloy wheel hub, characterized in that: include: An exhaust unit is provided on the top surface of the casting mold; Enlarge the distance between the runner on the casting mold and the casting hub to the preset size; The bottom mold, side mold and upper mold of the casting mold are set to metal materials, and the lower mold of the casting mold is set to a resin sand core; The casting temperature is controlled at 770-780°C, the casting liquid rising speed is controlled at 80mm / s, and the liquid rising pressure is controlled at 25KPa.

2. The optimization design method for casting a magnesium alloy wheel hub according to claim 1, characterized in that: The exhaust unit includes an exhaust groove or an exhaust hole provided on the top surface of the casting mold.

3. The optimization design method for casting a magnesium alloy wheel hub according to claim 2, characterized in that: The number of the exhaust grooves or exhaust holes is several, and the several exhaust grooves or exhaust holes are distributed at intervals on the top surface of the casting mold along the shape of the casting hub.

4. The optimization design method for casting a magnesium alloy wheel hub according to claim 1, characterized in that: The bottom mold, side mold and upper mold of the casting mold are set to metal materials including any one of magnesium alloy, aluminum alloy or magnesium-aluminum alloy.

5. The optimization design method for casting a magnesium alloy wheel hub according to claim 1, characterized in that: Enlarging the distance between the runner on the casting mold and the casting hub to a preset size includes setting the distance between the runner and the casting hub to 20-45 mm.

6. The optimization design method for casting a magnesium alloy wheel hub according to any one of claims 1 to 5, characterized in that: The tensile strength of the optimized cast magnesium alloy wheel is ≥250R M / MPa, yield strength ≥130R P0.2 / MPa, elongation after break ≥6.

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