KR102057098B1 - High strength lightweight aluminum wheels using undercut - Google Patents

Abstract

The present invention relates to a high-strength lightweight aluminum wheel utilizing an undercut, comprising: a rim portion forming an edge of the wheel; The hub may include a hub portion formed to penetrate the shaft and a plurality of spokes connecting the hub portion to the rim portion, and an undercut may be formed inside the upper end of the rim portion to reduce weight.

Description

High strength lightweight aluminum wheels using undercut}

The present invention relates to a high-strength lightweight aluminum wheel utilizing an undercut, and more particularly, to form an undercut by a low pressure casting method or flow forming to increase the strength of the wheel and reduce the weight of the wheel. Relates to an aluminum wheel.

Typically, wheels for automobiles are made of a metallic material, such as steel or aluminum. Such wheels are fixed by spherical head screws or conical head screws to wheel mountings on motor vehicles consisting of brake drums or brake discs.

On the other hand, in recent years, in order to improve fuel efficiency by reducing the weight of the vehicle, the wheels for automobiles are not only adopting a lightweight aluminum, but also a technology development has been made to lighten the weight structurally.

In general, the wheel design, such as the thickness and design of the hub mounting portion and the spoke portion of the disk member to satisfy the strength primarily to satisfy the minimum required strength conditions of the wheel, and then secondly to reduce the weight (weight reduction) To improve fuel economy through a variety of weight, such as the hub mounting portion of the wheel and the inner portion of the spoke.

However, as the weight of the wheel becomes light due to the weight loss of the wheel, rigidity is insufficient, which causes a problem of causing vibration and noise of the wheel itself when the vehicle is running. Accordingly, there is a need for improving the above problem.

In order to improve the above problems of the present invention, when manufacturing an aluminum wheel by a low pressure casting method or a flow forming method to implement a high-strength lightweight aluminum wheel using an undercut that can reduce the weight of the wheel while increasing the strength The purpose is to provide.

In order to solve the above problems, a high-strength lightweight aluminum wheel using an undercut according to an embodiment of the present invention is an automobile wheel formed of aluminum, the rim portion constituting the rim of the wheel; The hub may include a hub portion formed to penetrate the shaft and a plurality of spokes connecting the hub portion to the rim portion, and an undercut may be formed inside the upper end of the rim portion to reduce weight.

Here, the undercut may include a first round portion bent downward from the inner surface of the spoke; A second round portion bent inward so as to face the first round portion; It may include an inclined portion extending from the second round portion to form an inclination downward and a third round portion bent downward from the inclined portion.

In addition, the undercut may form a height of 17 to 23mm, it may form a width of 10 to 15mm.

In addition, the automobile wheel may be manufactured by a low pressure casting or flow forming method to form the undercut.

In addition, the vehicle wheel may be coated with a coating agent including 40 to 60% by weight of graphite, 10 to 20% by weight of graphite and 30 to 40% by weight of carbon nanotubes on the outer surface and the inner surface, respectively.

In addition, the graphene, graphite, carbon nanotubes may be impregnated with carbon black, respectively.

High-strength lightweight aluminum wheels using undercuts according to an embodiment of the present invention has the effect of reducing the weight of the wheels without causing vibration and noise of the wheels themselves.

In addition, there is an advantage that the strength can be improved.

In addition, by implementing the undercut shape on the rim, there is an advantage that can save the material.

1 is a perspective view of a high strength lightweight aluminum wheel utilizing an undercut according to an embodiment of the present invention.
FIG. 2 is a bottom perspective view of the aluminum wheel of FIG. 1. FIG.
3 is a cross-sectional view of the aluminum wheel of FIG. 1.
Figure 4 is an exemplary undercut installed the rib of the high-strength lightweight aluminum wheel utilizing the undercut according to an embodiment of the present invention.
Figure 5 is an exemplary undercut provided with a cushioning portion of a high-strength lightweight aluminum wheel utilizing the undercut according to an embodiment of the present invention.
6 is a photograph of the tissue of the undercut portion of the wheel manufactured by the flow forming according to an embodiment of the present invention.

Hereinafter, the description of the present invention with reference to the drawings is not limited to the specific embodiments, various changes may be made and various embodiments may be provided. In addition, the contents described below should be understood to include all transformations, equivalents, and substitutes included in the spirit and technical scope of the present invention.

In the following description, terms such as “first” and “second” are terms used to describe various components, and are not limited in themselves, and are used only to distinguish one component from other components.

Like reference numerals used throughout the present specification refer to like elements.

As used herein, the singular forms "a", "an" and "the" include plural forms unless the context clearly indicates otherwise. In addition, the terms "comprise", "comprise" or "have" described below are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist. It is to be understood that it does not exclude in advance the possibility of the presence or the addition of one or more other features or numbers, steps, actions, components, parts or combinations thereof.

Hereinafter, a high-strength lightweight aluminum wheel using an undercut according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6.

1 is a perspective view of a high-strength lightweight aluminum wheel utilizing an undercut according to an embodiment of the present invention, Figure 2 is a bottom perspective view of the aluminum wheel of Figure 1, Figure 3 is a cross-sectional view of the aluminum wheel of FIG.

First, the high-strength lightweight aluminum wheel using the undercut according to the embodiment of the present invention may be formed of an aluminum material.

Aluminum is a material that can be plastically processed and has a low melting point compared to other metals and can shape various shapes, and is suitable for processing automobile wheels having complicated shapes.

In addition, aluminum is light and rigid, so it is suitable for use in the field of automobiles requiring weight reduction, and in addition, there is an advantage of high corrosion resistance, non-toxicity, bonding, recyclability.

1 to 3, a high strength lightweight aluminum wheel utilizing an undercut according to an embodiment of the present invention may include a rim portion 10, a hub portion 20, and a spoke 30.

Here, the rim portion 10, the hub portion 20, the spokes 30 may be substantially the same as a conventional automobile wheel, the rim portion 10 is a portion for supporting the tire, may constitute the rim of the wheel The hub portion 20 may form a central portion of the wheel so that a wheel shaft or the like may be fitted thereto, and the spokes 30 may be formed to connect the hub portion 20 and the rim portion 10.

At this time, one feature of the present invention is to form an undercut 40 inside the upper portion of the rim portion 10, where the undercut can act as an important configuration to reduce the weight of the automobile wheel.

As is commonly known, weight reduction of an automobile wheel may have an effect of improving fuel efficiency, and improving fuel efficiency may be effective in saving energy and improving economic efficiency. Accordingly, it is important to reduce the weight of the wheel in addition to other parts of the vehicle, the present invention can generate the undercut during the manufacturing of the wheel to reduce the weight of the wheel.

In detail, the undercut 40 may include a first round part 42, a second round part 44, an inclined part 46, and a third round part 48 as shown in FIG. 3.

Here, the first round portion 42 may be bent to extend downward from the spoke inner surface toward the rim portion 10, and the second round portion 44 may extend on an extension line of the first round portion 42, and the wheel inner direction thereof. It may be extended to be bent to be formed to face the first round portion 42. With the above structure, the first round part 42 and the second round part 44 may form a concave surface.

In addition, the inclined portion 46 may extend from the second round portion 44. At this time, the inclined portion 46 may be inclined downward. That is, the inclined portion 46 may extend to be inclined downward and inward of the wheel in the second round portion 44.

The third round portion 48 may extend to form downward curvature in the inclined portion 46, and may extend to have a protruding surface toward the inner side of the spoke. That is, the first and second round portions 44 form a concave surface such that the curved surface faces the outward direction of the wheel, and the third round portion 48 protrudes such that the curved surface faces the spoke inward direction of the wheel. Can be formed.
In addition, the height on the extension line of the first round portion 42 and the second round portion 44 may be lower than the height of the interval between the spoke 30 and the third round portion 48.

The undercut may minimize interference with the flow of air introduced into the wheel while the first to third round parts 48 form a curved surface, thereby reducing resistance when the vehicle is driven.

On the other hand, the undercut 40 may form a height of 17 to 22mm on the basis of the distance from the curved surface of the third round portion 48 to the spokes, and the extension line between the first and second rounds in the measurement line of the height It can form a width of 10 to 15mm as a reference.

This is a height and width that can minimize the stiffness at the top of the rim and at the same time maximize the weight reduction, preferably 20mm and 14mm width, and can be reduced by about 8% compared to the existing 18-inch wheel weight. It has an effect.

Here, if the height is less than 17mm or more than 22mm, or if the width is less than 10mm or more than 15mm, the weight reduction efficiency is lowered, or the rigidity of the upper rim portion is lowered, there is a possibility that a breakage phenomenon may occur on the upper rim portion.

On the other hand, high-strength lightweight aluminum wheels utilizing the undercut of the present invention can be manufactured by low pressure casting or flow forming method. That is, the wheel is manufactured by a low pressure casting or a flow forming method at the time of manufacture, in which the undercut 40 may be generated.

Here, the low pressure casting is a method of injecting molten metal into the mold by inert gas or the like by injecting a relatively small pressure to the molten surface contained in the sealed container, or by introducing a vacuum into the mold so that the molten metal is introduced into the mold. It has the advantage of large and few impurities.

Accordingly, according to the present invention, after the mold formed by the upper mold and the lower mold is manufactured in accordance with the shape of the wheel on which the undercut is formed, an undercut may be formed when the molten metal is introduced into the mold and solidified by performing low pressure casting.

More specifically, the present invention may be the aluminum molten metal temperature of 670 to 690 ℃ during low pressure casting, and after the fourth pressurized the molten metal with a gas, it may proceed to maintain the pressure and exhaust the gas.

At this time, the low pressure casting may be pressurized for 360 seconds, the pressurization is the pressure of the first pressure 180g / cm ² 5 seconds, the secondary pressure 25g 300g / cm ² , the third pressure 6 seconds 832g / cm ² pressure For example, the fourth pressure may be performed at a pressure of 832 g / cm ² for 334 seconds, and the exhaust of gas for blocking aluminum injection into the mold may be performed for about 40 seconds.

In addition, the cooling of the molten aluminum injected into the mold, the upper mold cooling, side cooling, the lower mold cooling can be carried out, the cooling can all proceed with air cooling, the upper mold cooling can include hub, bolt, spoke cooling, Bottom cooling may include hub and spoke cooling.

At this time, the hub, bolt, spoke cooling can be carried out by changing the conditions according to the casting atmosphere for the start time and the holding time to suppress the occurrence of low-pressure casting shrinkage.

For example, the hub cooling of the hieroglyphic cooling may proceed for 25 seconds at 200 seconds of the total melt pressurization, the bolt cooling may proceed for 170 seconds at 150 seconds of the total melt pressurization, and the spoke cooling may be performed during the total pressurization of the melt pressurization. You can proceed for 90 seconds at 100 seconds.

In addition, the side cooling may proceed for 130 seconds at 120 seconds of the molten metal pressing time.

However, the above-mentioned low pressure casting set values of the pressure and cooling are not necessarily limited to all examples, and may be differently set according to an external temperature or a draw distance of the molten metal, a casting atmosphere, and the like.

In addition, one of the methods for manufacturing a high-strength lightweight aluminum wheel utilizing the undercut of the present invention is fixed to the wheel in the mandrel device for forming a wheel shape, and then rotating the wheel to tension the rim by heating the torch, etc. By completing the shape of the rim, at this time, by providing a preform for generating an undercut in the portion where the upper inside of the rim is mounted, the undercut may be formed when the wheel rim shape is completed.

When the undercut is formed by flow forming, there is an advantage in that the rim portion is dense and a microstructure having few shrinkage defects can be obtained.

With the low pressure casting or flow forming method, the present invention can easily form an undercut when manufacturing a wheel while increasing the strength of the wheel, and thus has the advantage of smoothly achieving a weight reduction target.

On the other hand, high-strength lightweight aluminum wheels using the undercut according to an embodiment of the present invention includes 40 to 60% by weight of graphite, 10 to 20% by weight of graphite, 30 to 40% by weight of carbon nanotubes on the outer and inner surfaces of the wheel, respectively. A coating agent may be coated, and preferably, the coating agent may include 50 wt% of graphene, 15 wt% of graphite, and 35 wt% of carbon nanotubes.

This is to easily release the heat of the aluminum wheel generated during braking or driving of the vehicle to the outside by using the high thermal conductivity of the graphene, graphite, and carbon nanotubes.

 In this case, the coating agent may be formed on the aluminum wheel by a coating method such as a dip coating method or spin coating, it may be formed to a thickness of about 4 to 6um.

If the coating thickness is less than 4um, there is a possibility that oxidation occurs on the surface of the aluminum wheel, and if the coating thickness is more than 6um, the cost may increase and thus may not be economical compared to the effect.

In addition, the graphene, graphite, carbon nanotubes may be impregnated with carbon black, respectively. This is because, in order to increase energy efficiency, the more carbon content, the greater the contact between carbons and the higher the thermal conductivity.

By coating the coating agent on the aluminum wheel, the present invention can easily release the heat generated during braking or driving of the vehicle to the outside.

In addition, the high-strength lightweight aluminum wheel using the undercut according to an embodiment of the present invention, referring to Figures 4 to 5, the undercut 40 may be provided with a rib 50 or the buffer unit 60, wherein the rib 50 or the buffer unit 60 may be provided in plurality at regular intervals along the circumference of the wheel.

Specifically, the rib 50 may be provided in the form of an aluminum bar, the buffer unit 60 is a spring 64 for the cushioning action and the support plate 62 for supporting the spring 64 is the buffer unit 60 ) Can be formed in the center. That is, the buffer unit 60 may have one support plate 62 formed at the center thereof, and springs 64 provided at both ends thereof to be connected to the wheels, respectively.

This is to reinforce the rigidity of the upper rim lower than conventional by the formation of the undercut 40, the rib 50 can reinforce the stiffness, the buffer portion 60 reinforces some rigidity and at the same time the side of the wheel It is also possible to absorb the impact force applied to the or the like.

In this case, the rib 50 and the buffer unit 60 may be provided separately, but may be provided together. That is, the undercut 40 may be provided with only the rib 50 along the circumference of the wheel, or may be provided with only the shock absorbing part 60, and may be provided so that the rib 50 and the shock absorbing part 60 alternate with each other.

In addition, the rib 50 and the buffer unit 60 may be formed within a range that does not reduce the weight saving effect due to the undercut 40.

Hereinafter, with reference to Figure 6 to demonstrate the effect of the high-strength lightweight aluminum wheel using the undercut according to an embodiment of the present invention, the following experimental example is presented, but the following experimental example is not limited to an exemplary. .

[Manufacture of wheel to be used for experiment]

For the evaluation of Experimental Examples 1 to 3 below, wheels having undercuts formed by low-pressure casting and flowforming were manufactured (hereinafter, referred to as 'Example 1' and 'Example 2', respectively, and the experiments were conducted for each. .

In Example 1, after setting the molten aluminum temperature to 685 ° C., the pressure of the first pressurized 180g / cm ² was 5 seconds, the second pressurized pressure was 300g / cm ^{2 for} 25 seconds, and the third pressurized pressure was 832g / cm ^{2 for} 6 seconds. , The pressure was 832g / cm ² for the fourth pressurization 334 seconds, and then the gas was evacuated for about 40 seconds, and the cooling proceeded to upper cooling, side cooling and lower cooling, and the upper cooling was hub, bolt, spoke. Cooling was performed, and lower mold cooling was performed by hub and spoke cooling. In addition, all the cooling was prepared by going to air cooling.

In the second embodiment, the wheel is fixed to the mandrel device for forming the wheel shape, and then the wheel is rotated and the rim is heated and tensioned while heating the rim to complete the shape of the rim. By providing the preform, an undercut was formed at the completion of the wheel rim shape.

In addition, Examples 1 and 2 formed a height of 20 mm based on the distance from the curved surface of the third round part of the wheel to the spokes, and based on the extension line between the first and second rounds in the measurement line of the height. A width of 14 mm was formed.

Experimental Example 1 Weight Measurement

In order to confirm the weight reduction effect due to the formation of the undercut, the weights of Examples 1 and 2 and the existing KH PE 18-inch wheel (hereinafter referred to as 'Comparative Example 1') were compared.

The results are shown in Table 1 below.

Experimental group weight Example 1 11.646 kg Example 2 11.644 kg Comparative Example 1 12.609kg

As shown in Table 1, Example 1 and Example 2 was found to be reduced by 0.963kg and 0.965kg, respectively, compared to Comparative Example 1, it was confirmed that the weight saving effect of about 7.6% when converted to this ratio It became.

Experimental Example 2 Evaluation of Undercut Wheel Structure

In order to evaluate the structure of the undercut wheel parts manufactured by flow forming and low pressure casting, specimens of the spokes and rims of each wheel manufactured by flow forming, low pressure casting, and general casting were prepared and divided into 8 parts. The tissue evaluation was carried out and the results are shown in Tables 2 to 4, respectively. In addition, photographs divided into eight parts of the spokes and rims, and photographs of tissues of the undercut wheel part manufactured by flow forming are shown in FIG. 4.

In the experimental method, the average of the specimens was measured 10 times, and the decimal point was omitted from the average.

Results of tissue evaluation of spokes and rims of wheels manufactured by flow forming No part Site name SDAS Remarks One ① Spoke 91 μm 10 times / each
Measure 2 ② Spoke 92 μm 3 ③ flange 89 μm 4 ④ flange 84 μm 5 ⑤ Limbu 82 μm 6 ⑥ Limbu 80 μm 7 ⑦ Limbu 73 μm 8 ⑧ Limbu 72 μm

As a result of the tissue measurement, the wheel manufactured by forming the undercut by flow forming was found to have a dense tissue formed toward the rim portion, and it was confirmed that a fine tissue with less shrinkage defects could be obtained.

Results of tissue evaluation of spokes and rims of wheels made with low pressure casting No part Site name SDAS Remarks One ① Spoke 91 μm 10 times / each
Measure 2 ② Spoke 92 μm 3 ③ flange 85 μm 4 ④ flange 86 μm 5 ⑤ Limbu 87 μm 6 ⑥ Limbu 87 μm 7 ⑦ Limbu 88 μm 8 ⑧ Limbu 88 μm

As a result of the measurement of the structure, the wheel manufactured by the low pressure casting was judged that the rim part is not as dense as the flow forming but is generally higher in density and strength.

Tissue evaluation of spokes and rims of conventional KH PE 18-inch wheels (general casting) No part Site name SDAS Remarks One ① Spoke 96 μm 10 times / each
Measure 2 ② Spoke 98 μm 3 ③ flange 100 μm 4 ④ flange 99 μm 5 ⑤ Limbu 103 μm 6 ⑥ Limbu 102 μm 7 ⑦ Limbu 102 μm 8 ⑧ Limbu 103 μm

As shown in Table 4, the wheel manufactured by the general casting is less dense than the wheel manufactured by the flow forming or the low pressure casting method, and it was confirmed that the density and the strength were low.

Experimental Example 3 Undercut Wheel Structure Analysis

In Experimental Example 3, 13 degrees of impact analysis, fatigue analysis, and running analysis of Comparative Example 1 and Comparative Example 1 were conducted to confirm the suitability of the driving.

First, the 13-degree impact of Comparative Example 1 was 245 MPa, fatigue occurred at 200,000 cycles of rotation, and 2 million cycles of continuous running were possible.

In comparison, Example 1 had a shock of 240 MPa at 13 degrees, fatigue occurred at 923,000 cycles of rotation, and continuous driving of 230 million cycles (subtracted from 0 after all 30 million) was possible.

In addition, Example 2 had a 13 degree impact of 232.8 MPa, fatigue occurred at 1,101,000 cycles of rotation, and continuous driving of 450 million cycles (subtracted from 0 after all 50 million) was possible.

Accordingly, it was confirmed that the undercut wheel structure was more suitable for traveling and the running performance was improved than in Comparative Example 1.

Experimental Example 4 Thermal Conduction Effect Experiment

In this experiment, in order to determine the heat conduction effect of the coating agent containing graphene, graphite, carbon nanotubes, 50 wt%, 15 wt% graphite, 35 wt% carbon nanotube on the wheels of Examples 1 and 2 It was compared with Example 1 and Example 2 by coating a coating comprising a (hereinafter referred to as Example 3 and Example 4).

The coating agent was coated on the inner and outer surfaces of the wheel by dip coating, and the thickness was coated to a thickness of 5um.

Experimental method is to install the tire on each wheel (Examples 1 to 4) to generate frictional heat until the temperature of the rim portion rises to 120 ℃, and then to stop and measure the time to fall to 60 ℃ recorded in Table 5 It was. (External temperature is 20 ℃)

Rim drop time from 120 ℃ to 60 ℃ (Outside temperature 20 ℃) Example 1 Example 2 Example 3 Example 4 time 342 sec 314sec 246sec 202 sec

Referring to Table 5, it can be seen that the wheel coated with a coating agent including graphene, graphite, and carbon nanotubes is more exothermic than the wheel without the coating agent.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement in other specific forms without changing the technical spirit or essential features of the present invention. I can understand that. Accordingly, the embodiments described above are exemplary in all respects and not restrictive.

10: limb
20: hub
30: spoke
40: undercut
42: first round part
44: second round
46: inclined portion
48: third round
50: rib
60: buffer part
62: support plate
64: spring

Claims (6)

In an automobile wheel formed of aluminum,
Rim constituting the rim of the wheel;
A hub portion forming a central portion of the wheel, the shaft portion penetrating the shaft;
It includes a plurality of spokes connecting the hub portion and the rim portion,
Undercut is formed inside the upper end of the rim portion can be reduced in weight,
The undercut,
Formed using a flow forming method,
The undercut forms a height of 17 to 23mm, a high strength lightweight aluminum wheel utilizing the undercut, characterized in that to form a width of 10 to 15mm.
The method of claim 1,
The undercut,
A first round portion bent downward from the spoke inner surface to the rim portion;
A second round portion that is bent into the wheel so as to face the first round portion on an extension line of the first round portion;
An inclined portion extending from the second round portion to form a slope downward;
A third round portion bent downward from the inclined portion to have a protruding surface toward the spoke inner side,
The high-strength lightweight aluminum wheel utilizing the undercut, wherein the height of the first round portion and the second round portion on the extension line is lower than the height of the spoke and the third round portion.
delete delete In an automobile wheel formed of aluminum,
Rim constituting the rim of the wheel;
A hub portion forming a central portion of the wheel, the shaft portion penetrating the shaft;
It includes a plurality of spokes connecting the hub portion and the rim portion,
Undercut is formed inside the upper end of the rim portion can be reduced in weight,
The car wheel,
A high strength lightweight aluminum wheel utilizing an undercut, characterized in that a coating agent comprising 40 to 60% by weight of graphite, 10 to 20% by weight of graphite, and 30 to 40% by weight of carbon nanotubes is coated on the outer and inner surfaces thereof.
The method of claim 5,
The graphene, graphite, carbon nanotubes are high-strength lightweight aluminum wheels using undercut, characterized in that the carbon black is impregnated respectively.

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