KR102326467B1 - Manufacturing method of trailing arm and trailing arm manufactured using the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a trailing arm capable of improving rigidity while maintaining a small specific gravity using a composite material, and a trailing arm manufactured using the same.
A method of manufacturing a trailing arm according to an embodiment of the present invention is a method of manufacturing a trailing arm of a vehicle, wherein carbon fiber (CF): 25 to 45 wt%, carbon nanotube (CNT): 0.2 to 2.0 wt% and Preparing a composite material including the remaining polyamide-based resin; and molding the trailing arm by injecting the composite material.

Description

Manufacturing method of a trailing arm and a trailing arm manufactured using the same

The present invention relates to a method for manufacturing a trailing arm and a trailing arm manufactured using the same, and more particularly, to a method for manufacturing a trailing arm capable of improving rigidity while maintaining a small specific gravity using a composite material and the same It relates to a trailing arm manufactured using

In general, the suspension of a vehicle connects the axle to the vehicle body so that the vibration or shock on the road surface transmitted from the wheels of the vehicle is not directly transmitted to the vehicle body when the vehicle is running, thereby preventing damage to the vehicle body and improving the ride quality. It's a good device

Suspension systems of automobiles are largely classified into front suspension and rear suspension. Among them, the rear suspension uses a plurality of links to determine the position of the axle using a multi-link type suspension. This applies depending on the vehicle type.

A wheel carrier constituting a multi-link rear suspension is coupled to a wheel, and a trailing arm is coupled to the wheel carrier by a plurality of bolts and nuts.

The trailing arm is welded side by side on both sides of the torsion beam to form the suspension device. Therefore, an appropriate buckling load is required along with the torsion beam.

Conventionally, in order to achieve the physical properties required by the trailing arm, it is manufactured by press-molding a steel plate material. Accordingly, the specific gravity of the trailing arm is quite high and the degree of freedom to implement various shapes is low. .

Recently, in the automobile field, weight reduction of parts has been pursued in order to improve fuel efficiency.

Accordingly, research to replace the trailing arm made of steel with a plastic material is being actively conducted. Among plastics, polyamide resin is in the spotlight as an important substitute material for such research and development.

These polyamide resins have advantages such as excellent impact resistance, abrasion resistance, and chemical resistance, but have low limitations in their application to commercial products in terms of physical properties such as tensile strength or tensile elongation.

Therefore, in general, in order to improve the tensile strength and tensile elongation of the polyamide resin, a method of manufacturing a polyamide composite material by dispersing a reinforcing filler such as graphite, glass fiber, carbon fiber, etc. as an additive in the resin is widely used.

However, as the content of additives such as reinforcing fillers increases, the specific gravity increases and the weight of the parts increases. However, there is a problem in that the impact strength decreases.

The content described as the background art above is only for understanding the background of the present invention, and should not be taken as an acknowledgment that it corresponds to the prior art already known to those of ordinary skill in the art.

Laid-open Patent Publication No. 10-2017-0062264 (2017.06.07)

The present invention provides a method for manufacturing a trailing arm capable of improving rigidity while maintaining a small specific gravity using a composite material, and freely forming ribs of various shapes by molding through injection, and a trailing arm manufactured using the same provides

A method of manufacturing a trailing arm according to an embodiment of the present invention is a method of manufacturing a trailing arm of a vehicle, wherein carbon fiber (CF): 25 to 45 wt%, carbon nanotube (CNT): 0.2 to 2.0 wt% and Preparing a composite material including the remaining polyamide-based resin; and molding the trailing arm by injecting the composite material.

In the step of preparing the composite material, the composite material further comprises 3 to 8 wt% of rubber.

The rubber (Rubber) is characterized in that the PE-based rubber (Rubber).

The carbon fiber (CF) is characterized in that it is a short fiber.

On the other hand, the trailing arm according to an embodiment of the present invention is characterized in that it is manufactured according to the above-described manufacturing method.

The trailing arm is characterized in that the tensile strength is 240 MPa or more.

The trailing arm is characterized in that the tensile elongation is 2.5% or more.

The trailing arm is characterized in that the buckling load is 3,500 kgf or more.

The trailing arm is characterized in that a bush hole connected to the vehicle body is formed at a front end, a plurality of fastening holes for mounting a wheel carrier are formed at a rear end, and a plurality of ribs are formed in a predetermined pattern on both sides of the trailing arm.

The trailing arm is characterized in that a plurality of ribs formed on both sides are formed asymmetrically with each other.

According to an embodiment of the present invention, by preparing a composite material in which the mixing amount of carbon fibers and carbon nanotubes is limited in the polyamide-based resin and the type and mixing amount of rubber are limited, the specific gravity is kept small while maintaining tensile strength and tensile strength. The effect of producing a trailing arm with improved elongation can be expected.

In addition, as the trailing arm is manufactured by injection molding using a composite material, the effect of implementing a trailing arm of various shapes can be expected.

1 is a right perspective view and a left perspective view showing a trailing arm manufactured according to an embodiment of the present invention;
2 is a right side view and a left side view showing a trailing arm manufactured according to an embodiment of the present invention;
3 is a table showing the conditions of Comparative Examples and Examples,
4 is a test result for the buckling performance of the trailing arm according to Comparative Examples and Examples;
5 is a test result for durability performance of the trailing arm according to Comparative Examples and Examples.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and the scope of the invention to those of ordinary skill in the art will be completely It is provided to inform you.

A method of manufacturing a trailing arm according to an embodiment of the present invention comprises the steps of largely preparing a composite material; and molding the trailing arm by injecting the composite material.

The step of preparing the composite material is a step of preparing a composite material that replaces the steel plate used when manufacturing the trailing arm. Prepare a composite material in which fibers (CF) and carbon nanotubes (CNT) are mixed.

In other words, the composite material includes carbon fiber (CF): 25 to 45 wt%, carbon nanotube (CNT): 0.2 to 2.0 wt%, and the remainder of the polyamide-based resin.

The polyamide-based resin is a resin having excellent impact resistance, abrasion resistance, chemical resistance, and the like as a base rasin. However, since tensile strength and tensile elongation have low limits for application to vehicle parts, in the present invention, a polyamide composite is prepared by mixing carbon fibers (CF) and carbon nanotubes (CNT) in a predetermined amount with a polyamide-based resin. implemented.

In this embodiment, the polyamide-based resin is not limited to a specific material, and nylon 66 (PA66) is applied as an example.

Carbon Fiber (CF) is a reinforcing agent added to improve the tensile strength of the resin composition. Short fibers were used.

Carbon fiber was mixed in 25 ~ 45wt%. If the mixing amount of carbon fibers is less than 25 wt%, the improvement of tensile strength cannot be guaranteed, and when the mixing amount of carbon fibers is more than 45 wt%, there is a problem in that workability is deteriorated. Preferably, 35wt% of carbon fiber is mixed.

Carbon Nano Tube (CNT) is a reinforcing agent added together with carbon fibers to improve the tensile strength of the resin composition. The tubes (CNTs) were mixed.

Carbon nanotube (CNT) was mixed in 0.2 ~ 2.0wt%. In order to ensure the improvement of tensile strength according to the mixing of carbon nanotubes (CNT), preferably, the mixing amount of carbon nanotubes (CNT) is 0.5 to 1.4 wt%. However, as the mixing amount of the carbon nanotubes (CNT) increases, the appearance quality and workability deteriorate, so the mixing amount of the carbon nanotubes (CNT) is preferably 0.2 to 0.5 wt%.

On the other hand, the composite material may be further mixed with rubber (Rubber) to improve the tensile elongation.

At this time, it is preferable to mix 3 to 8 wt% of rubber. When the mixing amount of the rubber is less than 3 wt%, the effect of mixing the rubber is insignificant, and when the mixing amount of the rubber is more than 8 wt%, a phenomenon in which the physical properties are rather deteriorated may occur.

In particular, although there are several types of rubber, in this embodiment, it is preferable to limit the type of rubber in order to improve durability by improving tensile elongation while minimizing a decrease in tensile strength. In this embodiment, the rubber (Rubber) is limited to the PE-based rubber (Rubber).

Meanwhile, in the composite material, a coupling agent may be further mixed to improve interfacial adhesion between the polyamide-based resin, which is a base resin, and carbon fibers (CF) and carbon nanotubes (CNT).

At this time, it is preferable to mix 5 to 8 wt% of the coupling agent. When the mixing amount of the coupling agent is less than 5 wt%, the effect of mixing the coupling agent is insignificant, and when the mixing amount of the coupling agent is more than 8 wt%, a phenomenon in which physical properties are rather deteriorated may occur.

In particular, like rubber, there are several types of coupling agents, but in this embodiment, it is preferable to limit the types of coupling agents in order to increase durability by improving tensile elongation while maintaining or improving tensile strength. In this example, the coupling agent was limited to an amide-based coupling agent.

On the other hand, in the present embodiment, the composite material is a polyamide-based resin other than the mixing amount of carbon fibers (CF), carbon nanotubes (CNT), rubber, and a coupling agent (Coupling agent).

If the composite material is prepared in this way, the trailing arm is molded using the prepared composite material.

In the step of molding the trailing arm, the trailing arm is manufactured by injection molding using a composite material.

Since the trailing arm is manufactured using injection molding in this way, the shape of the trailing arm to be molded can be freely formed.

Meanwhile, FIG. 1 is a right perspective view and a left perspective view showing a trailing arm manufactured according to an embodiment of the present invention, and FIG. 2 is a right side view and a left side view showing a trailing arm manufactured according to an embodiment of the present invention. For example, as shown in FIGS. 1 and 2 , the trailing arm 10 has a bushing hole 11 connected to the vehicle body at the front end thereof, and a plurality of fastening holes 12 in which the wheel carrier is mounted at the rear end. ) is formed, and a plurality of ribs may be formed on both sides in a predetermined pattern.

At this time, it is preferable that the plurality of ribs 13a , 13b , 13c are formed asymmetrically on both sides of the trailing arm 10 .

For example, a rib pattern 13b having a structure that can prevent the bush from being separated can be formed around the bush hole 11, and the edge region of the trailing arm 10 has a structure for buffering vertical impact. A rib pattern 13a may be formed, and a rib pattern 13c having a structure capable of preventing torsion may be formed in the central region of the trailing arm.

In this case, each of the rib patterns 13a, 13b, and 13c may form ribs in various shapes and thicknesses.

In addition, the thickness of the bottom surface of the trailing arm on which the ribs are formed may be variously implemented for each region.

On the other hand, the trailing arm manufactured using the composite material preferably maintains a tensile strength of 240 MPa or more, a tensile elongation of 2.5% or more, and a buckling load of 3,500 kgf or more. .

To this end, in this embodiment, the types and mixing amounts of components to be mixed in the composite material are limited.

Hereinafter, the present invention will be described using Comparative Examples and Examples.

As shown in FIG. 3, a composite material was prepared while changing the type and mixing amount of each component, and the trailing arm was molded by injection molding using the prepared composite material.

A buckling performance test was performed on the thus-formed trailing arm, and the results are shown in FIG. 4 .

As can be seen from FIG. 4 , in Examples 1 and 2, it was confirmed that the buckling load was improved compared to Comparative Examples 1 and 2.

In addition, in terms of maximum displacement and required time, it was confirmed that Examples 1 and 2 increased the maximum displacement and required time compared to Comparative Examples 1 and 2.

This means that, when preparing a composite material, carbon fiber (CF), which is a short fiber, and carbon nanotube (CNT), which are short fibers, are used as reinforcing materials. It was found that it is more advantageous for the improvement of the buckling load.

Next, a durability test was performed on the trailing arm molded under the same conditions as in FIG. 3 , and the results are shown in FIG. 5 .

As can be seen from FIG. 5 , in Examples 1 and 2, the specific gravity was significantly lowered, and it was confirmed that the tensile elongation was significantly improved. It can be seen that by using carbon fibers (CF) and carbon nanotubes (CNT) rather than glass fibers (GF), weight reduction can be achieved by reducing the specific gravity.

In addition, it can be seen that the tensile elongation can be significantly improved when carbon nanotubes are mixed with short-fiber carbon fibers or carbon fibers of short fibers are mixed.

On the other hand, in the case of Comparative Example 1, it was confirmed that although the flexural strength was improved by mixing the carbon fibers of the long fibers, the tensile elongation was not realized at the desired level. In addition, Comparative Example 1 did not pass the limiting durability performance, so it was confirmed that there is a limit in manufacturing as a trailing arm.

And, in the case of Comparative Example 2, the flexural strength and impact strength were improved by mixing the glass fiber of the long fiber, but the tensile elongation was not realized at the desired level, and the specific gravity was particularly high. Therefore, it was confirmed that there is a limit to the weight reduction of the trailing arm when glass fiber is used as a reinforcement.

Although the present invention has been described with reference to the accompanying drawings and the above-described preferred embodiments, the present invention is not limited thereto, and is defined by the following claims. Accordingly, those of ordinary skill in the art can variously change and modify the present invention within the scope without departing from the spirit of the claims to be described later.

10: trailing arm 11: bush hole
12: fastening holes 13a, 13b, 13c: rib pattern

Claims (10)

A method of manufacturing a trailing arm for a vehicle, comprising:
Carbon fiber (CF): 25 to 45 wt%, carbon nanotube (CNT): preparing a composite material comprising 0.2 to 2.0 wt% and the remaining polyamide-based resin;
and molding the trailing arm by injecting the composite material,
In the step of preparing the composite material,
The carbon fiber (CF) is made of only short fibers,
The trailing arm injected in the step of molding the trailing arm has a tensile elongation of 2.5% or more and a buckling load of 3,600 kgf or more.
The method according to claim 1,
In the step of preparing the composite material,
The composite material is rubber (Rubber): Manufacturing method of a trailing arm further comprising 3 ~ 8wt%.
3. The method according to claim 2,
The method of manufacturing a trailing arm, characterized in that the rubber (Rubber) is a PE-based rubber (Rubber).
delete A trailing arm manufactured according to claim 1.
6. The method of claim 5,
The trailing arm is a trailing arm, characterized in that the tensile strength of 240 MPa or more.
delete delete 6. The method of claim 5,
The trailing arm is characterized in that a bush hole connected to the vehicle body is formed at a front end, a plurality of fastening holes for mounting a wheel carrier are formed at a rear end, and a plurality of ribs are formed in a predetermined pattern on both sides of the trailing arm. .
10. The method of claim 9,
The trailing arm is a trailing arm, characterized in that a plurality of ribs formed on both sides are formed asymmetrically with each other.

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