A low pressure casting method for rapidly cooling a reinforced wheel spoke

Abstract

This invention provides a low-pressure casting method for rapidly cooling and strengthening wheel spokes, comprising the following steps: S1: casting the wheel spokes using a mold; S2: punching the overflow ring; S3: pre-processing the welding positions of the wheel spokes and rim, and machining the wheel spokes and rim to create the necessary welding surfaces; S4: assembling the wheel spokes and rim together; pouring molten aluminum into the mold, the molten aluminum solidifies from the ribs towards both ends, the solidification sequence being from the middle of the ribs to the rib ramp and center hole, and from the middle of the ribs to the rib tip, C-ring, outer flange, and overflow ring. This invention separately casts the wheel spokes and rim, ensuring the final solidification point of the wheel spokes is at the overflow ring. By circumferentially cutting the overflow ring and then welding the wheel spokes and rim, it overcomes the problem in existing technologies where the final solidification point is at the rib tip, resulting in hot spots and defects such as shrinkage cavities and segregation. Simultaneously, it significantly reduces the cooling time of the wheel spokes, resulting in smaller grains and increased elongation.

Description

Technical Field

[0001] This invention relates to the casting of wheel spokes, specifically a low-pressure casting method for rapidly cooling and strengthening wheel spokes. Background Technology

[0002] The manufacturing process of cast aluminum alloy wheels can be divided into gravity casting, low-pressure casting, extrusion casting, semi-solid casting, forging, spinning, and combinations of several processes. Among them, low-pressure casting, because it involves slowly pressing molten aluminum into the mold cavity from bottom to top under low pressure, results in a more stable filling process and is less prone to defects such as porosity and shrinkage cavities, making it widely used in the production of A356 aluminum alloy wheels. In recent years, against the backdrop of continuous improvement in the lightweighting of automobiles and the increasing demand for higher quality automobiles, the requirements for weight reduction and performance of A356 aluminum alloy wheels have become increasingly stringent.

[0003] Traditional aluminum alloy cast wheels typically follow a sequential solidification principle, where molten aluminum solidifies in the order of inner flange - outer flange - ribs - center hole. This solidification sequence effectively achieves wheel production and controls the number of defects in each area. However, this process has two problems: First, the spokes and center hole are relatively thin, requiring heat preservation to ensure they solidify last. This inevitably leads to a large secondary diameter spacing between the spokes and severe segregation. Second, under a single solidification direction, each area must be cooled sequentially, resulting in a long casting time.

[0004] Because the inner flange is far from the center gate, it usually solidifies first. If cooling starts from the ribs, the molten aluminum will eventually solidify last at the outer flange, resulting in macroscopic defects such as shrinkage cavities. Adding an overflow block directly to the outer flange to reduce shrinkage cavities would prevent the side cylinder from opening, while removing the side cylinder would prevent the upper mold from opening. Therefore, the solution of bidirectional rapid solidification starting from the ribs has never been adopted. Summary of the Invention

[0005] The purpose of this invention is to provide a low-pressure casting method for rapidly cooling and strengthening wheel spokes to solve the problems in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A low-pressure casting method for rapidly cooling and strengthening wheel spokes, the wheel spokes comprising a center hole, ribs, a C-ring, an outer flange, and an overflow ring, wherein the ribs comprise a rib middle portion, a rib tip, and a rib ramp; comprising the following steps:

[0008] S1: The spokes are cast using a mold;

[0009] S2: Punch the overflow ring;

[0010] S3: The welding positions of the spokes and rim are pre-processed, and the spokes and rim are machined to form the mating surfaces required for welding;

[0011] S4: Assemble the spokes and rim together;

[0012] The mold includes an upper mold assembly, a lower mold assembly, and a cooling system. The cooling system includes a water cooling plate and an air duct. A spoke cavity is formed between the upper mold assembly and the lower mold assembly. The upper mold assembly includes, in sequence along the direction of the central hole, an upper mold C-ring, an upper mold rib tip, a second upper mold ramp, a first upper mold ramp, an upper mold mounting surface, an upper mold PCD, and a split core.

[0013] The lower mold assembly, along the direction of the central hole, includes, in sequence, a lower mold rib tip, a lower mold rib center, a lower mold ramp, and a lower mold PCD;

[0014] The cooling system for the upper mold C-ring, upper mold rib tip, upper mold mounting surface, split core, lower mold rib tip, and lower mold ramp is a water-cooled plate.

[0015] The cooling system used in the second upper mold ramp, the first upper mold ramp, the upper mold PCD, and the lower mold rib is an air duct;

[0016] The molten aluminum is poured into the mold, and the molten aluminum solidifies from the ribs toward both ends. The solidification sequence is as follows: from the middle of the ribs to the rib slope and the central hole, and from the middle of the ribs to the rib tip, C-ring, outer flange and overflow ring.

[0017] Furthermore, the specific process of step S4 is to weld and position the spokes and rim, and weld the spoke mating surfaces and rim mating surfaces together so that the spokes and rim are connected together.

[0018] Furthermore, the spokes and rim are welded by friction stir welding, with an axial pressure of 2-3.5 KN, a stirring head speed of 1500-2000 rpm, and a welding speed of 300-400 mm / min.

[0019] Furthermore, the water flow rate of the water cooling pan is 14-16 L / min; the air flow rate of the air duct is 1800-2000 L / min.

[0020] Furthermore, the aluminum molten metal pouring process involves pressing molten aluminum at 700-710°C into the mold through the central hole, maintaining a pressure of 700 mbar, filling the mold in 30 seconds, and then maintaining the pressure for 200 seconds.

[0021] Furthermore, the spokes are adapted to 19-inch to 21-inch wheel hubs.

[0022] Furthermore, the spoke elongation is 8-12%.

[0023] The beneficial effects of this invention are as follows: By casting the spokes and rim separately, the final solidification point of the spokes is at the overflow ring. By circumferentially cutting the overflow ring and then welding the spokes and rim together, this overcomes the problem in existing technologies where the final solidification point is at the rib tip, resulting in hot spots and defects such as shrinkage cavities and segregation. Simultaneously, it significantly reduces the spoke cooling time from 370 seconds in existing technologies to 200 seconds, resulting in smaller spoke grains and an increased elongation of 8-12%.

[0024] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of the mold of the present invention.

[0026] Figure 2 This is a cross-sectional view of the spokes of the present invention.

[0027] Figure 3 This is an isometric view of the mold of the present invention.

[0028] Figure 4 This is a top view of the spokes of the present invention.

[0029] Reference numerals: 1-Upper die C-ring, 2-Upper die rib tip, 3-First upper die ramp, 4-Upper die mounting surface, 5-Upper die PCD, 6-Separating core, 7-Second upper die ramp, 8-Lower die PCD, 9-Lower die ramp, 10-Lower die rib center, 11-Lower die rib tip, 12-Overflow ring, 13-Outer flange, 14-Rib tip, 15-Rib center, 16-Rib ramp, 17-Center hole, 18-C-ring, 19-Upper die assembly, 20-Lower die assembly, 21-Spoke. Detailed Implementation

[0030] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate preferred embodiments of the application. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of this application more thorough and complete.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] It should be understood that when an element or layer is referred to as "on" or "adjacent to," it is considered appropriate. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are used merely to distinguish one element, component, area, layer, or portion from another. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion.

[0033] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below” or “under” the other element or feature will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0035] A low-pressure casting method for rapidly cooling and strengthening wheel spokes 21, the wheel spokes 21 including a center hole 17, ribs, a C-ring 18, an outer flange 13, and an overflow ring 12, wherein the ribs include a rib middle portion 15, a rib tip 14, and a rib ramp 16; comprising the following steps:

[0036] S1: The spokes 21 are cast using a mold;

[0037] S2: Punch the overflow ring 12;

[0038] S3: The welding positions of the spokes 21 and the rim are pre-processed, and the spokes 21 and the rim are machined to form the mating surfaces required for welding;

[0039] S4: Weld the spokes 21 and the rim together and weld the mating surfaces of the spokes 21 and the rim together to connect the spokes 21 and the rim.

[0040] The spokes 21 and the rim are welded by friction stir welding. The welding process involves an axial pressure of 2-3.5 kN, of which 3 kN is used in this embodiment. In other embodiments, any value of 2 kN, 3.5 kN, or 2-3.5 kN can be used. The stirring head speed is 1500-2000 rpm, of which 2000 rpm is used in this embodiment. The welding speed is 300-400 mm / min, of which 400 mm / min is used in this embodiment. In other embodiments, any value of 300-400 mm / min can be used to achieve the effect of the present invention.

[0041] The mold includes an upper mold assembly 19, a lower mold assembly 20, and a cooling system. The cooling system includes a water cooling plate and an air duct. A spoke 21 cavity is formed between the upper mold assembly 19 and the lower mold assembly 20. The upper mold assembly 19 includes, in sequence along the direction of the central hole 17, an upper mold C ring 1, an upper mold rib tip 2, a second upper mold ramp 7, a first upper mold ramp 3, an upper mold mounting surface 4, an upper mold PCD 5, and a split core 6.

[0042] The lower mold assembly 20, along the direction of the central hole 17, includes, in sequence, a lower mold rib tip 11, a lower mold rib center 10, a lower mold ramp 9, and a lower mold PCD8;

[0043] The cooling system for the upper mold C-ring 1, upper mold rib tip 2, upper mold mounting surface 4, split core 6, lower mold rib tip 11, and lower mold ramp 9 is a water-cooled plate.

[0044] The cooling system used in the second upper mold ramp 7, the first upper mold ramp 3, the upper mold PCD5 and the lower mold rib 10 is an air duct;

[0045] The aluminum liquid is poured into the mold. The process of pouring the aluminum liquid is as follows: the aluminum liquid at 705°C is pressed into the mold through the central hole 17, the pressure is maintained at 700 mbar, the mold is filled in 30 seconds, and then the pressure is maintained for 200 seconds.

[0046] The specific process parameters are as follows: at 30 seconds, open the water cooling plates of the upper mold rib tip 2 and the upper mold C ring 1, and close them after 60 seconds; at 50 seconds, open the water cooling plate of the lower mold rib tip 11, and close it after 50 seconds; at 60 seconds, open the air duct of the lower mold rib 10, and close it after 80 seconds; at 100 seconds, open the air duct of the second upper mold ramp 7, and close it after 150 seconds; at 120 seconds, open the air duct of the first upper mold ramp 3, and close it after 130 seconds; at 130 seconds, open the air ducts of the upper mold PCD5 and the lower mold PCD8, and close them after 130 seconds; at 150 seconds, open the water cooling plates of the upper mold mounting surface 4 and the lower mold ramp 9, and close them after 100 seconds; at 200 seconds, open the water cooling plate of the split core 6, and close it after 60 seconds.

[0047] The molten aluminum is poured into the mold, and the molten aluminum solidifies from the rib to both ends. The solidification sequence is as follows: from the middle of the rib 15 to the rib slope 16 and the central hole 17, and from the middle of the rib 15 to the rib tip 14, C-ring 18, outer flange 13 and overflow ring 12.

[0048] The water flow rate of the water cooling pan is 15L / min; the air flow rate of the air duct is 2000L / min.

[0049] The spoke 21 is adapted to a 19-inch wheel hub.

[0050] The spoke 21 has an elongation of 12%.

[0051] Working principle: This invention significantly shortens the solidification time of the spokes 21 by processing the rim and spokes 21 separately and then welding them together. By setting the upper mold C ring 1, upper mold rib tip 2, upper mold mounting surface 4, split core 6, lower mold rib tip 11 and lower mold ramp 9 as water cooling plates, and setting the second upper mold ramp 7, first upper mold ramp 3, upper mold PCD5 and lower mold rib as air ducts, the aluminum liquid finally solidifies at the overflow ring 12. Finally removing the overflow ring 12 overcomes the problem in the prior art where the final solidification point is at the rib tip 14, resulting in hot spots and defects such as shrinkage cavities and segregation.

[0052] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0053] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A low-pressure casting method for rapidly cooling and strengthening wheel spokes, the wheel spokes comprising a center hole, ribs, a C-ring, an outer flange, and an overflow ring, wherein the ribs comprise a rib middle portion, a rib tip, and a rib ramp; characterized in that, Includes the following steps: S1: The spokes are cast using a mold; S2: Punch the overflow ring; S3: Pre-process the welding positions of the spokes and rim, and machine the spokes and rim to form the mating surfaces required for welding; S4: Assemble the spokes and rim together; The mold includes an upper mold assembly, a lower mold assembly, and a cooling system. The cooling system includes a water cooling plate and an air duct. A spoke cavity is formed between the upper mold assembly and the lower mold assembly. The upper mold assembly includes, in sequence along the direction of the central hole, an upper mold C-ring, an upper mold rib tip, a second upper mold ramp, a first upper mold ramp, an upper mold mounting surface, an upper mold PCD, and a split core. The lower mold assembly, along the direction of the central hole, includes, in sequence, a lower mold rib tip, a lower mold rib center, a lower mold ramp, and a lower mold PCD; The cooling system for the upper mold C-ring, upper mold rib tip, upper mold mounting surface, split core, lower mold rib tip, and lower mold ramp is a water-cooled plate. The cooling system used in the second upper mold ramp, the first upper mold ramp, the upper mold PCD, and the lower mold rib is an air duct; The molten aluminum is poured into the mold, and the molten aluminum solidifies from the rib to both ends. The solidification sequence is as follows: from the middle of the rib to the rib slope and the central hole, and from the middle of the rib to the rib tip, C-ring, outer flange and overflow ring. The process of pouring molten aluminum is as follows: molten aluminum at 700-710℃ is pressed into the mold through the central hole, the pressure is maintained at 700mbar, the mold is filled in 30s, and then the pressure is maintained for 200s. The cooling and solidification process is as follows: at 30s, open the water-cooling plate of the upper mold rib tip and the upper mold C-ring, and close it after 60s; at 50s, open the water-cooling plate of the lower mold rib tip, and close it after 50s; at 60s, open the air duct in the lower mold rib, and close it after 80s; at 100s, open the air duct of the second upper mold ramp, and close it after 150s; at 120s, open the air duct of the first upper mold ramp, and close it after 130s; at 130s, open the air duct of the upper mold PCD and the lower mold PCD, and close it after 130s; at 150s, open the water-cooling plate of the upper mold mounting surface and the lower mold ramp, and close it after 100s; at 200s, open the water-cooling plate of the split core, and close it after 60s.

2. The low-pressure casting method for rapidly cooling and strengthening wheel spokes according to claim 1, characterized in that, The specific process of step S4 is to weld and position the spokes and rim, and weld the spoke mating surfaces and rim mating surfaces together so that the spokes and rim are connected together.

3. The low-pressure casting method for rapidly cooling and strengthening wheel spokes according to claim 2, characterized in that, The spokes and rims are welded by friction stir welding. The welding process involves an axial pressure of 2~3.5KN, a stirring head speed of 1500~2000rpm, and a welding speed of 300~400mm / min.

4. The low-pressure casting method for rapidly cooling and strengthening wheel spokes according to claim 1, characterized in that, The water flow rate of the water cooling pan is 14-16 L / min; the air flow rate of the air duct is 1800-2000 L / min.

5. The low-pressure casting method for rapidly cooling and strengthening wheel spokes according to claim 1, characterized in that, The spokes are designed to fit 19-inch to 21-inch wheel hubs.

6. The low-pressure casting method for rapidly cooling and strengthening wheel spokes according to claim 1, characterized in that, The spoke elongation rate is 8-12%.

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