Hub rapid forming casting process

Abstract

The invention discloses a rapid molding casting process for a hub. The rapid molding casting process comprises the following steps: S1, manufacturing a sand core corresponding to a lateral through hole of a spoke in shape; s2, preheating a side die, an upper die, a bottom die and a sand core of the hub die; s3, the sand core is positioned and installed at the preset position of the inner cavity of the side mold; s4, the mold is closed to form a casting cavity containing the sand core; s5, molten metal is poured into the cavity, and the sand core is wrapped with the molten metal; s6, after pouring, key parts such as an upper lug of the hub are rapidly cooled, and meanwhile sectional type high pressure is applied to a cavity through a liquid storage hopper for feeding; and S7, the mold is opened after solidification, the hub blank with the lateral through hole structure is taken out, and finally the sand core is removed. According to the method, the complex lateral through holes are directly formed in the casting link, a large amount of subsequent milling machining is omitted, the production cost is greatly reduced, the production efficiency is improved, and the overall mechanical property of the hub is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of wheel hub processing technology, and more specifically to a rapid prototyping casting process for wheel hubs. Background Technology

[0002] Wheel hubs are key safety components and important aesthetic parts of automobiles. Modern automotive wheel hub designs increasingly emphasize lightweighting and aesthetics, with many high-end or sports wheels featuring complex three-dimensional hollow structures on the spokes to reduce weight, enhance heat dissipation, and improve visual appeal.

[0003] Currently, mainstream aluminum alloy wheel manufacturing processes face significant challenges for wheel hubs with complex lateral (non-axial) through holes. Traditional one-piece gravity casting or low-pressure casting processes cannot directly form the lateral suspended structure inside a closed mold. Therefore, the common practice in the industry is to first obtain a solid wheel hub blank or one with only simple axial holes through casting, and then use multi-axis CNC machine tools with expensive special forming tools to perform long-term milling on the spokes to gradually cut out the complex three-dimensional hollow through holes required by the design.

[0004] This "casting + CNC precision milling" process has significant drawbacks: 1) High cost: Specialized cutting tools are expensive and have high processing wear; CNC machining is time-consuming, resulting in high equipment occupancy and energy costs. 2) Low efficiency: Milling a complex hollowed-out wheel spoke takes a long time, restricting production cycle time. 3) Material waste: A large amount of cast aluminum alloy is cut into chips, resulting in low material utilization. 4) Potential impact on mechanical properties: The cutting process may cut off metal flow lines and generate micro-stress on the machined surface, which theoretically may adversely affect the fatigue performance of the wheel hub. Summary of the Invention

[0005] The problem to be solved by this invention is to provide a rapid prototyping casting process for wheel hubs, which innovatively combines the sand core casting concept with the advanced high-pressure sequential feeding casting process for wheel hubs. This process can directly form complex through holes on the side of the wheel spokes during the casting process, thereby eliminating or significantly reducing subsequent CNC machining steps and achieving the goals of cost reduction, efficiency improvement, and quality enhancement.

[0006] The technical solution provided by this invention to solve the above problems is: a rapid prototyping casting process for wheel hubs, comprising the following steps: S1. Sand core preparation: Based on the shape of the lateral through hole in the spoke section of the hub design drawing, prepare a sand core with the same shape as the through hole; S2. Preheating of mold and sand core: Heating the side mold, upper mold, bottom mold of the wheel hub mold and the sand core prepared in step S1; S3. Sand core positioning: The preheated sand core is precisely installed and fixed in the inner cavity of the side mold at the predetermined position where a through hole needs to be formed on the side of the wheel spoke; S4. Mold closing: The side mold with the sand core installed is closed with the upper mold and the bottom mold to form a casting cavity containing the sand core for forming a hub with lateral through holes; the upper mold is connected to a liquid storage tank for storing molten metal and pressurizing and feeding. S5. Pouring: Molten metal is poured from the gate into the casting cavity, the molten metal fills the casting cavity and encapsulates the sand core; S6. Sequential cooling and high-pressure feeding: After casting, the molten metal in the upper ear of the wheel hub in the casting cavity is rapidly cooled; at the same time, the molten metal stored in the storage tank is subjected to segmented high pressure through the gas pressurization system, which forces the molten metal in the storage tank to sequentially feed the casting cavity, giving priority to ensuring sufficient feeding of the upper ear of the wheel hub. S7. Mold Opening and Sand Removal: After the wheel hub has completely solidified, stop applying pressure, open the mold and remove the wheel hub casting blank with the side through hole structure. Finally, remove the sand core material inside the wheel hub casting to form the final side through hole.

[0007] Preferably, in step S2, the preheating temperature is controlled between 650°C and 710°C; the preheating temperature of the sand core is not lower than 300°C.

[0008] Preferably, in step S3, the sand core is positioned and fixed by a positioning pin, positioning groove or magnetic fixing device preset in the inner cavity of the side mold, so as to ensure that the sand core does not shift or float during the pouring process.

[0009] Preferably, in step S4, the liquid storage tank is independently temperature-controlled by a heating system to maintain its temperature at 650℃~710℃ before pouring.

[0010] Preferably, in step S5, the volume of the poured molten metal is equal to the sum of the volume of the casting cavity and the volume required for feeding, wherein the feeding volume accounts for 6% to 8% of the total molten metal volume.

[0011] Preferably, in step S6, the segmented high pressure is a six-stage pressurization, with a pressure range between 0.5 KGF / cm² and 6 KGF / cm², and a total pressurization time between 180 seconds and 210 seconds. The specific pressure and time curve is adjusted according to the wheel hub size and wall thickness.

[0012] Preferably, in step S6, the sequential cooling and shrinkage process specifically involves: first, rapidly cooling the upper lug of the hub while simultaneously performing high-pressure shrinkage; then, sequentially cooling and shrinking the rim, the spokes containing the lateral through-hole structure, the wheel disc, and the center of the wheel disc.

[0013] In step S7, the method for removing the sand core is one or more of mechanical vibration cleaning, high-pressure air blowing, or dissolution cleaning.

[0014] Preferably, the molten metal is aluminum alloy molten metal, and the pouring temperature is 700℃~720℃.

[0015] Compared with the prior art, the advantages of the present invention are: the present invention innovatively combines the sand core casting concept with the advanced high-pressure sequential feeding casting process for wheel hubs, which can directly form complex through holes on the side of the wheel spokes during the casting process, thereby eliminating or significantly reducing subsequent CNC machining processes and achieving the goals of cost reduction, efficiency improvement and quality enhancement. Attached Figure Description

[0016] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0017] Figure 1 This is a flowchart of the process flow of the present invention; Figure 2 This is a schematic diagram of the wheel hub of the present invention, wherein the red arrow points to a hollow structure; Figure 3 This is a schematic diagram of the side mold with a sand core installed according to the present invention. Detailed Implementation

[0018] The following will describe in detail the implementation of the present invention with reference to the accompanying drawings and embodiments, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0019] In the description of this invention, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature, and in the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0023] It should also be understood that the terminology used in this specification of embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. As used in this specification of embodiments of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0024] As shown in the accompanying drawings, a rapid prototyping casting process for wheel hubs includes the following steps: S1. Sand core preparation: Based on the shape of the lateral through hole in the spoke section of the hub design drawing, prepare a sand core with the same shape as the through hole; S2. Preheating of mold and sand core: Heating the side mold, upper mold, bottom mold of the wheel hub mold and the sand core prepared in step S1; S3. Sand core positioning: The preheated sand core is precisely installed and fixed in the inner cavity of the side mold at the predetermined position where a through hole needs to be formed on the side of the wheel spoke; S4. Mold closing: The side mold with the sand core installed is closed with the upper mold and the bottom mold to form a casting cavity containing the sand core for forming a hub with lateral through holes; the upper mold is connected to a liquid storage tank for storing molten metal and pressurizing and feeding. S5. Pouring: Molten metal is poured from the gate into the casting cavity, the molten metal fills the casting cavity and encapsulates the sand core; S6. Sequential cooling and high-pressure feeding: After casting, the molten metal in the upper ear of the wheel hub in the casting cavity is rapidly cooled; at the same time, the molten metal stored in the storage tank is subjected to segmented high pressure through the gas pressurization system, which forces the molten metal in the storage tank to sequentially feed the casting cavity, giving priority to ensuring sufficient feeding of the upper ear of the wheel hub. S7. Mold Opening and Sand Removal: After the wheel hub has completely solidified, stop applying pressure, open the mold and remove the wheel hub casting blank with the side through hole structure. Finally, remove the sand core material inside the wheel hub casting to form the final side through hole.

[0025] In step S2, the preheating temperature is controlled between 650°C and 710°C; the preheating temperature of the sand core is not lower than 300°C.

[0026] In step S3, the sand core is positioned and fixed by a positioning pin, positioning groove or magnetic fixing device preset in the inner cavity of the side mold, so as to ensure that the sand core does not shift or float during the pouring process.

[0027] In step S4, the liquid storage tank is independently temperature-controlled by a heating system to maintain its temperature at 650℃~710℃ before pouring.

[0028] In step S5, the volume of the poured molten metal is equal to the sum of the volume of the casting cavity and the volume required for feeding, wherein the feeding volume accounts for 6% to 8% of the total molten metal volume.

[0029] In step S6, the segmented high pressure is a six-stage pressurization, with a pressure range between 0.5 KGF / cm² and 6 KGF / cm², and a total pressurization time between 180 seconds and 210 seconds. The specific pressure and time curve is adjusted according to the wheel hub size and wall thickness.

[0030] In step S6, the sequential cooling and shrinkage process specifically involves: firstly, rapidly cooling the upper lug of the hub while simultaneously performing high-pressure shrinkage; then, sequentially cooling and shrinking the rim, the spokes containing the lateral through-hole structure, the wheel disc, and the center of the wheel disc.

[0031] In step S7, the method for removing the sand core is one or more of mechanical vibration cleaning, high-pressure air blowing, or dissolution cleaning.

[0032] The molten metal is aluminum alloy molten metal, and the pouring temperature is 700℃~720℃.

[0033] The above scheme has the following advantages: 1. Cost reduction: Most of the complex 3D hollowing processes are transferred from the subsequent CNC milling to the preceding casting process. This eliminates the need for expensive specialized forming tools and lengthy milling time, resulting in a significant reduction in production costs.

[0034] 2. Significantly improve production efficiency: The time to cast a blank with a through hole is almost the same as the time to cast a solid blank. Compared with the CNC machining time of several hours or even longer, the production cycle is shortened by an order of magnitude.

[0035] 3. Improved material utilization and product performance: Near-net-shape forming is achieved, reducing waste during aluminum alloy cutting. The through-hole surface formed by casting is a natural solidification surface of the metal, with complete streamlines and no cutting stress, which helps maintain the fatigue strength of the wheel hub.

[0036] 4. Ensuring the quality of the casting body: The system creatively combines sand core forming and high-pressure sequential feeding technologies. The high-pressure feeding process effectively overcomes the additional heat spots that may be introduced by the sand core, ensuring the internal density of key parts of the wheel hub (such as the upper lug) and the entire product, resulting in stable and reliable product quality.

[0037] 5. High design flexibility: By changing different sand cores, a series of wheel hub products with different spoke through hole shapes can be produced on the same set of basic molds, responding to the rapidly changing market demands.

[0038] The above description only illustrates the preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All modifications made within the scope of the independent claims of this invention are also within the scope of protection of this invention.

Claims

1. A rapid prototyping casting process for wheel hubs, characterized in that, Includes the following steps: S1. Sand core preparation: Based on the shape of the lateral through hole in the spoke section of the hub design drawing, prepare a sand core with the same shape as the through hole; S2. Preheating of mold and sand core: Heating the side mold, upper mold, bottom mold of the wheel hub mold and the sand core prepared in step S1; S3. Sand core positioning: The preheated sand core is precisely installed and fixed in the inner cavity of the side mold at the predetermined position where a through hole needs to be formed on the side of the wheel spoke; S4. Mold closing: The side mold with the sand core installed is closed with the upper mold and the bottom mold to form a casting cavity containing the sand core for forming a hub with lateral through holes; the upper mold is connected to a liquid storage tank for storing molten metal and pressurizing and feeding. S5. Pouring: Molten metal is poured from the gate into the casting cavity, the molten metal fills the casting cavity and encapsulates the sand core; S6. Sequential cooling and high-pressure feeding: After casting, the molten metal in the upper ear of the wheel hub in the casting cavity is rapidly cooled; at the same time, the molten metal stored in the storage tank is subjected to segmented high pressure through the gas pressurization system, which forces the molten metal in the storage tank to sequentially feed the casting cavity, giving priority to ensuring sufficient feeding of the upper ear of the wheel hub. S7. Mold Opening and Sand Removal: After the wheel hub has completely solidified, stop applying pressure, open the mold and remove the wheel hub casting blank with the side through hole structure. Finally, remove the sand core material inside the wheel hub casting to form the final side through hole.

2. The wheel hub rapid prototyping casting process according to claim 1, characterized in that, In step S2, the preheating temperature is controlled between 650℃ and 710℃; the preheating temperature of the sand core is not lower than 300℃.

3. The wheel hub rapid prototyping casting process according to claim 1, characterized in that, In step S3, the sand core is positioned and fixed by a positioning pin, positioning groove or magnetic fixing device preset in the inner cavity of the side mold, so as to ensure that the sand core does not shift or float during the pouring process.

4. The wheel hub rapid prototyping casting process according to claim 1, characterized in that, In step S4, the liquid storage tank is independently temperature-controlled by a heating system to maintain its temperature at 650℃~710℃ before pouring.

5. The wheel hub rapid prototyping casting process according to claim 1, characterized in that, In step S5, the volume of the poured molten metal is equal to the sum of the volume of the casting cavity and the volume required for feeding, wherein the feeding volume accounts for 6% to 8% of the total molten metal volume.

6. The wheel hub rapid prototyping casting process according to claim 1, characterized in that, In step S6, the segmented high pressure is a six-stage pressurization, with a pressure range between 0.5 KGF / cm² and 6 KGF / cm², and a total pressurization time between 180 seconds and 210 seconds. The specific pressure and time curve is adjusted according to the wheel hub size and wall thickness.

7. A rapid prototyping casting process for wheel hubs according to claim 1 or 6, characterized in that, In step S6, the sequential cooling and shrinkage process is as follows: first, the upper lug of the hub is rapidly cooled and simultaneously subjected to high-pressure shrinkage, and then the rim, spokes including the lateral through-hole structure, disc and disc center are cooled and shrunk sequentially.

8. The wheel hub rapid prototyping casting process according to claim 1, characterized in that, In step S7, the method for removing the sand core is one or more of mechanical vibration cleaning, high-pressure air blowing, or dissolution cleaning.

9. The wheel hub rapid prototyping casting process according to claim 1, characterized in that, The molten metal is aluminum alloy molten metal, and the pouring temperature is 700℃~720℃.

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