KR20240119482A - Carbon fiber conveyor belt - Google Patents

Abstract

This invention was created as a result of research on “Deokjin Advanced Materials Development Strategy System Construction and Business Expansion Consulting,” which includes a unidirectional carbon fiber sheet in which carbon fibers are arranged in the longitudinal direction, and the unidirectional carbon fiber sheet. It has a carbon core composed of adhesive rubber bonded to the upper and lower surfaces of the. Therefore, the high elastic modulus of carbon fiber not only makes it possible to secure a low elongation of the conveyor belt, but also makes it lightweight. Additionally, by using a unidirectional carbon fiber sheet, higher physical properties can be secured in a conveyor belt where longitudinal tension acts as the main stress.

Description

Carbon fiber conveyor belt}

The present invention relates to carbon fiber conveyor belts.

Conveyor belts are used in a variety of transportation and logistics systems. In particular, in the case of conveyor belts used to transport heavy objects handled in power plants, rock mines, mines, etc., strong tensile strength and durability are required, so steel cord conveyor belts using steel cord as a reinforcement material are mainly used.

As shown in Figure 1, the steel cord conveyor belt has a steel core (40) with adhesive rubber (42) wrapped around a steel cord (41) made of carbon steel, and an upper cover rubber (20) and a lower cover rubber (30). It is formed as a structure sandwiched between them.

However, the existing steel cord conveyor belt has the disadvantage of high weight and weak adhesion between the steel cord 41 and the adhesive rubber 42, which causes fiber pulling out. In response to this, conveyor belts using nylon or polyester exist as prototypes, but they have the disadvantage of high elongation.

In addition, conveyor belts are generally produced continuously in roll form during production, but in order to be mounted on a conveyor, they are cut, installed on equipment, and then glued together again. However, steel cord conveyor belts have the disadvantage that this process is very complicated.

Korean registered utility model (20-0202844)

The purpose of the present invention is to provide a carbon fiber conveyor belt that can solve the above-mentioned problems.

The carbon fiber conveyor belt to achieve the above purpose is,

A carbon core composed of a unidirectional carbon fiber sheet (unidirectional carbon fabric) in which carbon fibers are arranged in the longitudinal direction, and adhesive rubber bonded to the upper and lower surfaces of the unidirectional carbon fiber sheet;

an upper cover rubber coupled to the upper surface of the carbon core; and

It is characterized in that it includes a lower cover rubber coupled to the lower surface of the carbon core.

This invention was created as a result of research on “Deokjin Advanced Materials Development Strategy System Construction and Business Expansion Consulting,” which includes a unidirectional carbon fiber sheet in which carbon fibers are arranged in the longitudinal direction, and the unidirectional carbon fiber sheet. It has a carbon core composed of adhesive rubber bonded to the upper and lower surfaces of the. Therefore, the high elastic modulus of carbon fiber not only makes it possible to secure a low elongation of the conveyor belt, but also makes it lightweight. Additionally, by using a unidirectional carbon fiber sheet, higher physical properties can be secured in a conveyor belt where longitudinal tension acts as the main stress.

The present invention implements a carbon core with target performance by laminating a plurality of unit unidirectional carbon fiber sheets and adhesive rubber. Because of this, each ply can be cut into a stepped shape, making it easy to perform stepped jointing when installing and repairing a conveyor belt. In addition, the thickness and strength of the carbon core can be freely adjusted depending on the number of stacks of unit unidirectional carbon fiber sheets and adhesive rubber, making custom manufacturing of conveyor belts easier.

Figure 1 is a diagram showing an existing steel cord conveyor belt.
Figure 2 is a diagram showing a carbon fiber conveyor belt according to the first embodiment of the present invention.
Figure 3 is a diagram showing a carbon fiber sheet, (a) shows a twill weave carbon fiber sheet, (b) shows a plain weave carbon fiber sheet, and (c) shows a stitched unidirectional carbon fiber.
Figure 4 is a diagram showing a twill woven carbon fiber sheet in which drafting occurred.
Figure 5 is a diagram showing the carbon core of a carbon fiber conveyor belt according to a second embodiment of the present invention.
Figure 6 is a diagram showing a representative volume element (RVE) model.
Figure 7 is a graph showing the strength according to the volume fraction (Vf) of the carbon core.
Figure 8 is a graph showing the stiffness according to the volume fraction (Vf) of the carbon core.
Figure 9 is a graph showing the thickness according to the volume fraction (Vf) of the carbon core.
Figure 10 is a graph showing density according to the volume fraction (Vf) of the carbon core.

Hereinafter, the carbon fiber conveyor belt according to the first embodiment of the present invention will be described in detail.

As shown in FIG. 2, the carbon fiber conveyor belt according to the first embodiment of the present invention is composed of a carbon core 10, an upper cover rubber 20, and a lower cover rubber 30.

[Carbon Core (10)]

The carbon core 10 is interposed between the upper cover rubber 20 and the lower cover rubber 30.

The carbon core 10 is composed of a unidirectional carbon fiber sheet 11 in which carbon fibers are arranged in the longitudinal direction, and adhesive rubber 12 surrounding the unidirectional carbon fiber sheet 11. The one-way carbon fiber sheet (11) functions as a reinforcing material, and the adhesive rubber (12) connects the one-way carbon fiber sheet (11) to the upper cover rubber (20) and the lower cover rubber (30). The adhesive rubber 12 is formed by curing a type 2 rubber adhesive with low viscosity. This is because type 1 rubber adhesive has high viscosity and has poor impregnability into the unidirectional carbon fiber sheet (11).

On the other hand, as shown in FIG. 3(a), a twill carbon fiber sheet in which carbon fiber is woven in a twill weave as a reinforcing material of the carbon core 10, and a plain weave in which carbon fiber is woven in a plain weave as shown in FIG. 3(b). A carbon fiber sheet, a unidirectional carbon fiber sheet 11 that has been stitched as shown in FIG. 3(c), can be used.

twill carbon fiber sheet

However, as shown in Figure 4, when using a twill carbon fiber sheet as a reinforcing material of the carbon core 10, the upper cover rubber 20, the carbon core 10, and the lower cover rubber 30 are stacked and then used as a heat plate. When compressed with a press and hardened, severe drafting of the carbon fiber sheet occurs due to the compression of the rubber. Therefore, there are limitations in using the twill carbon fiber sheet as a reinforcing material for the carbon core 10.

Plain weave carbon fiber sheet, unidirectional carbon fiber sheet

On the other hand, plain weave carbon fiber sheets have higher resistance to drafting than twill weave carbon fiber sheets, so they can be used as reinforcing materials for the carbon core 10. However, since longitudinal tension is the main stress in conveyor belts, one-way carbon fiber sheets (11) ) can be used as a reinforcing material for the carbon core 10 to secure higher mechanical properties. Therefore, it is preferable to use a unidirectional carbon fiber sheet 11 rather than a plain weave carbon fiber sheet as a reinforcing material for the carbon core 10. Here, the unidirectional carbon fibers constituting the unidirectional carbon fiber sheet 11 are stitched together with sewing thread to prevent drafting. In the first embodiment, there is one unidirectional carbon fiber sheet 11, and the carbon core 10 is made of a set number (3K, 5K, 8K, 12K, 15K, etc.) of unidirectional carbon fibers to meet the target tensile performance. It is composed.

[Upper cover rubber (20), lower cover rubber (30)]

The upper cover rubber (20) is coupled to the upper surface of the carbon core (10) by adhesive rubber (12). The lower cover rubber (30) is coupled to the lower surface of the carbon core (10) by adhesive rubber (12). The thickness of the upper cover rubber 20 and the lower cover rubber 30 is formed differently depending on the product to be transported.

Hereinafter, a carbon fiber conveyor belt according to a second embodiment of the present invention will be described in detail.

The carbon fiber conveyor belt according to the second embodiment of the present invention is different from the first embodiment in the configuration of the carbon core 10. Detailed description of the same configuration is omitted. The same symbol applies to the same configuration.

[Carbon Core (10)]

As shown in FIG. 5, in the second embodiment, the unidirectional carbon fiber sheet of the carbon core 10 is composed of a plurality of unit unidirectional carbon fiber sheets 11a.

In the first embodiment, the carbon core 10 is made of a single unidirectional carbon fiber sheet 11 made of 15K carbon fiber, while in the second embodiment, the carbon core 10 is made of a unit unidirectional carbon fiber sheet made of 3K carbon fiber. (11a) consists of 5 sheets or 3 sheets of unit unidirectional carbon fiber sheet (11a) formed of 5K carbon fiber. Therefore, thickness and strength can be adjusted in more diverse ways.

In the unit unidirectional carbon fiber sheet 11a, like the unidirectional carbon fiber sheet 11 of the first embodiment, carbon fibers are arranged in the longitudinal direction, and the carbon fibers are stitched together with sewing thread.

In the second embodiment, adhesive rubber 12 is laminated on the upper and lower surfaces of the unit unidirectional carbon fiber sheet 11a, and then a compressed and heated unit laminate (lamina) is first created. Then, the unit laminates are stacked to produce a carbon fiber conveyor belt.

The reason for this is as follows.

A hand that applies type 2 rubber adhesive to the upper surface of the unit unidirectional carbon fiber sheet (11a), stacks other unit unidirectional carbon fiber sheets (11a) on top of the type 2 rubber adhesive, repeats this, and presses them all at once to produce a carbon fiber conveyor belt. In the hand lay-up method, when pressed, the type 2 rubber adhesive easily comes out between the laminated unit unidirectional carbon fiber sheets (11a), and the thickness of the adhesive rubber (12) made by curing the type 2 rubber adhesive is It becomes thinner. When the thickness of the adhesive rubber 12 is reduced in this way, the interlayer bond between the unit unidirectional carbon fiber sheets 11a and the adhesive rubber 12 is low, so that interlayer separation easily occurs, or sufficient interlayer bond strength even if interlayer separation does not occur. is not secured. This is because the thicker the adhesive rubber 12 is, the higher the interlayer bonding strength is, but in the case of the hand lay-up method, the distance between layers is narrow and the interlayer bonding strength is lowered.

In the second embodiment, in order to solve this problem, a type 2 rubber adhesive is applied to the upper surface of the unit unidirectional carbon fiber sheet 11a, and the type 2 rubber adhesive is sufficiently impregnated and cured into the unit unidirectional carbon fiber sheet 11a. First, a unit laminate consisting of adhesive rubber (12) and unit unidirectional carbon fiber sheet (11a) is made.

When the unit laminates made in this way are stacked to the set conveyor belt thickness and pressed, the adhesive rubber 12 is slightly melted only on the surface where the unit laminates are in contact, and the unit laminates are bonded by the melted adhesive rubber 12. . In this case, the adhesive rubber 12 hardly escapes to the outside, so the thickness of the adhesive rubber 12 remains almost unchanged. Ultimately, in a carbon fiber conveyor belt composed of laminated unit laminates, the thickness of the adhesive rubber 12 is almost the same as the set thickness, and the interlayer bonding strength is maintained as is.

Comparative example

In general, the standard for steel cord conveyor belts is ST - XXXX, with the last number indicating the tensile force per unit length of the belt (N/mm).

In the case of ST 2500, the diameter of the cord is 6.8mm, the cord spacing is 15mm, the cord structure is 7x19, and the tensile force per unit area of the steel cord is calculated to be 367.6MPa.

The density of the steel core composed of steel cord derived by considering the volume of carbon steel and the volume of rubber is shown in the table below.

rubber carbon steel steel core Density (g/cm3) 1.3 8 3.69

<Density of steel core>

Experiment example

Multi-scale modeling analysis was performed using the commercial program Digimat to predict the mechanical properties of a carbon fiber conveyor belt using stitched unidirectional carbon fiber sheets as reinforcement.

As shown in Figure 6, the method of obtaining the physical properties was obtained after structural analysis by simulating the representative volume element (RVE), a representative unit group, through micro and meso modeling, and the representative volume fraction (Vf) was selected as 60%. , The physical properties of carbon fiber and rubber applied in the analysis are shown in Tables 2 and 3 below.

<Physical properties of carbon fiber>

<Physical properties of rubber>

As shown in Figures 7 and 8, when the volume fraction (Vf) obtained through analysis is 60%, the ultimate tensile strength of the carbon core is 2491.1 MPa and the stiffness is 138,397 MPa. The thickness of the laminate is 0.2 mm, which is close to the thickness of dry fabric.

As the thickness of the superelastic rubber increases, the shear strength increases. For general rubber bonding, an adhesive thickness of 50μm or more is recommended. For subsequent bonding, the carbon core must be cut into a stepped shape to facilitate bonding, so a certain thickness or more is required for each ply, and the thickness according to the volume fraction (Vf) is as shown in FIG. 9. The density of the carbon fiber is 1.7 g/cm3, and the density of the carbon core according to the volume fraction (Vf) is as shown in FIG. 10. The physical properties of the final carbon core are shown in Table 4 below.

1Ply Thickness
(mm) Volume fraction (Vf) tensile strength
(MPa) density
(g/cm3) 1.35 0.092 381.2 1.363

<Material properties of final carbon core>

Performance analysis results

In order to have the same tensile force as the existing ST 2500, the thickness of the carbon core is 6.56mm, and the number of plies of the carbon core at this time is 5. The performance comparison between the existing steel cord conveyor belt ST 2500 and the carbon fiber conveyor belt is shown in Table 5 below.

ST 2500 carbon fiber conveyor belt comparison Tensile force (N/mm) 2500 2573.1 103% core thickness 6.8 6.75 99.3% weight
(based on 100mmX100mm) 250.92 92 37%

<Comparison of steel core and carbon core>

10: carbon core
20: Upper cover rubber
30: Lower cover rubber
40: steel core

Claims (5)

A carbon core composed of a unidirectional carbon fiber sheet (unidirectional carbon fabric) in which carbon fibers are arranged in the longitudinal direction, and adhesive rubber bonded to the upper and lower surfaces of the unidirectional carbon fiber sheet;
an upper cover rubber coupled to the upper surface of the carbon core; and
A carbon fiber conveyor belt comprising a lower cover rubber coupled to the lower surface of the carbon core. According to paragraph 1,
The one-way carbon fiber sheet is a carbon fiber conveyor belt, characterized in that the carbon fibers are stitched together by sewing thread. According to paragraph 1,
A carbon fiber conveyor belt, characterized in that the carbon core includes a single unidirectional carbon fiber sheet. According to paragraph 1,
The one-way carbon fiber sheet is a carbon fiber conveyor belt, characterized in that it is composed of a plurality of unit one-way carbon fiber sheets. According to clause 4,
The unit unidirectional carbon fiber sheet is a carbon fiber conveyor belt, characterized in that the adhesive rubber is laminated on the upper and lower surfaces and then compressed and heated to form a lamina.