KR102414563B1 - Method for manufacturing of composite structure including z-pin and composite structure thereby the same that - Google Patents

Abstract

The present invention relates to a method for forming a composite structure including a Z pin and a composite structure manufactured using the same, comprising: a mold preparation step of preparing a mold; a mold processing step of machining an insertion groove so that the Z-pin patch can be embedded in the upper surface of the mold; Z-pin patch insertion step of inserting the Z-pin patch into the insertion groove; a fiber sheet lamination step of laminating a fiber sheet on the upper surface of the mold; A vacuum step of arranging vacuum system materials to create a vacuum inside the mold; a resin injection step of injecting a resin after the vacuum step; After the resin injection step, a demolding step of demolding the cured fiber sheet from the mold and a Z-pin comprising a patch removing step of removing a patch portion of the Z-peening patch attached to the composite structure A molding method may be provided.

Description

A method for forming a composite structure including a Z-pin and a composite structure manufactured using the same

The present invention relates to a method for forming a composite structure including a Z-pin and a composite structure manufactured using the same. By molding in a state in which the Z-pin is inserted in the thickness direction of the composite structure, the strength can be improved by reinforcing the interlayer performance of the composite structure. It relates to a method for forming a composite structure including a Z-pin capable of being able to, and a composite structure manufactured using the same.

In general, fiber-reinforced composite materials, which are commonly used in lightweight structures such as transportation equipment and aerospace structural members, are manufactured by laminating a unidirectional or woven reinforcing fiber layer and injecting a resin in a vacuum to harden it.

Since the laminate-molded composite structure does not have a separate reinforcing material in the thickness direction, an interlayer separation phenomenon in which the reinforcing fiber layer and the layer are easily separated by an external impact or the like occurs.

Since such interlayer separation lowers the strength of the structure, a solution to prevent this is required.

In order to solve the above problems, the present invention relates to a method for forming a composite structure including a Z pin and a composite structure manufactured using the same, and to increase the strength by applying the Z pin to the existing VARTM process to solve the delamination phenomenon , to provide a method for forming a composite structure including a Z-pin to improve process efficiency and productivity, and a composite structure manufactured using the same.

In order to solve the above problems, a method for forming a composite structure including a Z pin according to an embodiment of the present invention comprises: a mold preparation step of preparing a mold; a mold processing step of machining an insertion groove so that the Z-pin patch can be embedded in the upper surface of the mold; Z-pin patch insertion step of inserting the Z-pin patch into the insertion groove; a fiber sheet lamination step of laminating a fiber sheet on the upper surface of the mold; A vacuum step of arranging vacuum system materials to create a vacuum inside the mold; a resin injection step of injecting a resin after the vacuum step; After the resin injection step, a demolding step of demolding the cured composite structure from the mold and a Z-pin including a patch removing step of removing a patch portion of the Z-pin patch attached to the composite structure.

In addition, the Z-pin patch may include a patch formed of a rubber material and a Z-pin including a plurality of Z-pins inserted into the patch.

In addition, the patch includes a patch hole formed so that the Z-pin can be easily separated from the patch in the patch removal step, and the patch hole has both sides so as to reduce a contact area between the patch and the Z-pin. It is characterized in that the hole is formed in a symmetrical zigzag shape.

In addition, after the patch removal step, further comprising a bonding step of bonding an additional member to the composite structure, wherein the bonding step, in a state in which the composite structure and the additional member are temporarily assembled, the fiber sheet is attached to the Z pin of the composite structure It is characterized in that the part and the additional member are laminated so as to surround the connected part, and the resin is injected into the fiber sheet and then cured and joined.

In addition, after the Z-pin patch insertion step, in order to increase the adhesion between the Z-pin and the fiber sheet, the method may further include an adhesive application step of applying an adhesive to the Z-pin.

In addition, the adhesive may include 100 to 110 parts by weight of an epoxy resin, 40 to 90 parts by weight of a curing agent, 0.1 to 10 parts by weight of an amine-based accelerator, and 0.2 to 7 parts by weight of a silane coupling agent.

In addition, the curing agent includes an acid anhydride curing agent and a condensate of formaldehyde and phenol, and the acid anhydride curing agent is phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexa It is characterized in that at least one member selected from the group consisting of hydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, and methylhexahydrophthalic anhydride.

In addition, it is possible to provide a composite structure manufactured by a method for forming a composite structure including a Z pin.

The composite structure molding method including the Z-pin according to the embodiment of the present invention as described above and the composite structure manufactured using the same are basically applied to the method of inserting the Z-pin in the thickness direction of the composite structure, thereby improving the interlayer separation performance. has a reinforcing effect.

In addition, when connecting the composite structure and the additional member, there is an advantage in that the strength of the bonding portion can be supplemented by bonding using a Z pin.

1 is a flowchart of a method for forming a composite structure including a Z pin according to an embodiment of the present invention.
2 (a) to (f) are exemplary views showing the forming step of the method for forming a composite structure including a Z pin according to an embodiment of the present invention.
3 is an exemplary view of a composite structure manufactured by a method for forming a composite structure including a Z pin according to an embodiment of the present invention.
4 (a), (b) is an exemplary view showing a state in which a patch hole is formed in the patch of the composite structure molding method including the Z-pin according to an embodiment of the present invention.
5 is an exemplary view showing a vessel to which the bonding step of the method for forming a composite structure including a Z pin according to an embodiment of the present invention is applied.
Figure 6 (a) to (c) is an exemplary view showing the bonding step of the composite structure molding method including the Z pin according to an embodiment of the present invention.

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

In the following description, terms such as 1st, 2nd, etc. are terms used to describe various components, meanings are not limited thereto, and are used only for the purpose of distinguishing one component from other components.

Like reference numbers used throughout this specification refer to like elements.

As used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise. In addition, terms such as "comprises", "comprises" or "have" described below are intended to designate the existence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification. It should be construed as not precluding the possibility of addition or existence of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

In addition, in the description with reference to the accompanying drawings, the same components are given the same reference numerals regardless of the reference numerals, and the overlapping description thereof will be omitted. In describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings 1 to 6 .

1 is a flowchart of a method for forming a composite structure including a Z pin according to an embodiment of the present invention, and FIGS. 2 (a) to (f) are a method for forming a composite structure including a Z pin according to an embodiment of the present invention. It is an exemplary view showing the forming step of, Figure 3 is an exemplary view of a composite structure manufactured by a method for forming a composite structure including a Z-pin according to an embodiment of the present invention, Figure 4 (a), (b) is It is an exemplary view showing a state in which a patch hole is formed in a patch of a method for forming a composite structure including a Z pin according to an embodiment of the present invention, and FIG. 5 is a method for forming a composite structure including a Z pin according to an embodiment of the present invention. It is an exemplary view showing a vessel to which the bonding step of .

1 to 3, the method for forming a composite structure including a Z pin according to an embodiment of the present invention includes a mold preparation step (S10), a mold processing step (S20), a Z pin patch insertion step (S30), a fiber sheet It may include a lamination step (S40), a vacuum step (S50), a resin injection step (S60), a demolding step (S70) and a patch removal step (S80).

Specifically, the present invention is characterized in that by adding a molding step including the Z pin (3) to the LRTM process or VARTM process for manufacturing the existing composite structure, strength and durability are strengthened.

Prior to describing the method for forming a composite structure including a Z-pin according to an embodiment of the present invention, a Z-pin patch will be described.

The Z-pin patch not only reinforces the delamination performance of the composite structure in the present invention, but also supplements the strength of the joint when connecting the composite structure and additional members. The Z-pin 3 is inserted into the patch 2 can be formed in the form.

In more detail, the Z pin 3 may be formed in a pin shape and inserted into the patch 2 , and a plurality of Z pins may be provided and densely inserted into the patch 2 .

In this case, a plurality of protrusions may be formed on the outer surface of the Z pin 3 , and the shape of the protrusions may be formed in various ways. Accordingly, the Z pin 3 can prevent peeling after insertion as the contact area with the material to be connected increases, and can provide an effect of increasing the bonding force to the connecting portion.

The patch 2 may be formed of a material into which a pin can be inserted, such as rubber, polyurethane, silicone, etc., and is most preferably formed of rubber, but is not limited thereto.

Also, referring to FIG. 4 , the patch 2 may include a patch hole 8 so that the Z pin 3 can be easily separated from the patch 2 .

The patch hole 8 is a hole formed so that the Z-pin can be easily separated by reducing the contact area between the patch 2 and the Z-pin, and may be formed in various shapes.

Most preferably, the patch hole 8 may be formed in a zigzag shape in which both sides are symmetrical as shown in FIG. 4 , but is not limited thereto.

The Z-pin patch formed in this way is the most important configuration in the present invention, and a method of forming a composite structure including the same will be described.

First, the mold preparation step ( S10 ) is a step of preparing the mold 1 to form the composite structure, and a customized mold 1 may be prepared according to the shape of the structure. At this time, it is most preferable to prepare an open mold for the mold 1, but the present invention is not limited thereto.

Referring to Figure 2 (a), the mold processing step (S20) is a step of processing the insertion groove 7 so that the Z-pin patch can be inserted into the upper surface of the mold (1). By forming the insertion groove 7 in the mold 1 through the mold processing step S20, molding in which the composite structure and the Z-pin 3 are integrated can be made.

At this time, the mold processing step (S20) is preferably processed to a size suitable for the shape of the Z-pin patch so that the Z-pin patch can be inserted, but is not limited thereto.

In addition, in the mold processing step (S20), the height of the insertion groove 7 is the same as the height of the patch 2 or is preferably processed higher than the patch 2, and most preferably, the height of the insertion groove 7 is It is to be processed 0 to 5 mm higher than the height of the patch (2).

At this time, when the height of the insertion groove 7 is processed lower than the height of the patch 2, the fiber sheet 4 to be laminated on the upper surface of the Z-pin patch later is due to the patch 2 positioned higher than the insertion groove 7 It is undesirable because the curvature may cause a concave groove to be formed on the surface of the composite structure. On the other hand, when the height of the insertion groove 7 is processed to be higher than the height of the patch 2 by more than 5 mm, the fiber sheet 4 is bent due to the patch 2 positioned lower than the insertion groove 7 This is not preferable because protrusions of a convex shape may be formed on the surface of the composite structure.

Referring to Figure 2 (b), the Z-pin patch insertion step (S30) is a step of inserting the Z-pin patch into the insertion groove (7).

By inserting the Z-pin patch into the insertion groove 7 as described above and forming the composite structure, a form in which the Z-pin is inserted into the composite structure can be manufactured.

The fiber sheet lamination step (S40) consisting of the following is a step of laminating the fiber sheet 4 on the upper surface of the mold 1 after the Z-pin patch is inserted.

In this case, the fiber sheet 4 may be formed of various fibers, and most preferably formed of carbon fibers or glass fibers, but is not limited thereto.

In addition, in the fiber sheet lamination step (S40), when the fiber sheet 4 is laminated on the upper surface of the mold 1, the fiber sheet 4 is inserted into the Z pin 3 exposed on the upper surface of the mold 1 to be laminated. let it be

The vacuum step (S50) is a step of making the inside of the mold 1 a vacuum by arranging the vacuum system materials.

The vacuum system material in the present invention generally refers to the vacuum system material used in the RTM process, and may include a sealant tape, a vacuum bag, and a vacuum pump.

More specifically, in the vacuum step ( S50 ), the mold 1 may be sealed using a sealant tape and a vacuum bag, and then the inside of the mold 1 may be evacuated using a vacuum pump.

The resin injection step (S60) is a step of injecting the resin 5 in a vacuum inside the mold 1, and the resin used in the present invention is preferably a thermosetting resin.

In this case, as the thermosetting resin, a thermosetting resin such as an epoxy resin or polyester may be used, and an epoxy resin is most preferably used, but is not limited thereto.

Referring to FIG. 2E , the demolding step S70 is a step of demolding the cured composite structure from the mold 1 after the resin 5 is injected.

Through the demolding step (S70), it is possible to manufacture a composite structure in a state in which the Z-pin patch is inserted.

Finally, referring to FIG. 2(f), the patch removal step (S80) is a step of removing the patch 2 from the Z-pin patch attached to the composite structure.

The composite structure after the patch removal step (S80) can be used with only the Z pin 3 inserted, and has the advantage of being able to connect to other composite structures through the Z pin 3 .

5 to 6 , the method for forming a composite structure including a Z pin according to an embodiment of the present invention includes a bonding step of bonding the additional member 20 to the composite structure 10 after the patch removing step (S80) may include more.

The bonding step is a step performed when assembling the composite structure 10 and the additional member 20 , and the additional member 20 is combined with the composite structure 10 as well as the structure formed in the same manner as the composite structure 10 . It may be a variety of types of structures to be used, but is not limited thereto.

Referring to FIG. 5A , the bonding step may be performed in a state in which the composite structure 10 and the additional member 20 are temporarily assembled. More specifically, referring to FIG. 5 (b), the bonding step is to laminate the fiber sheet 4 to surround the portion where the Z pin 3 of the composite structure 10 and the additional member 20 are connected. A fibrous sheet (4) allows the composite structure (10) and the additional member (20) to be connected. Thereafter, referring to FIG. 5C , the bonding step may be finished by injecting the resin 5 into the fiber sheet 4 and then curing it.

At this time, it is most preferable to use a hand layup method that can be easily performed manually without additional equipment in the bonding step in the process of injecting the resin 5 into the fiber sheet 4 .

In the hand layup method, the fiber sheet 4 is manually stacked layer by layer and then the resin is applied, or the fiber sheet 4 and the resin 5 are alternately applied to inject the resin 5 into the fiber sheet 4 and then defoaming. It is a curing process after

In this way, in the bonding step, the composite structure 10 can increase the strength of the bonding portion of the additional member 20 through the process as described above, and it can be made to be in a more rigid state.

The method for forming a composite structure including a Z pin according to an embodiment of the present invention may further include a coating step after the Z pin patch insertion step.

The application step is a step of applying an adhesive to the Z pin 3 in order to increase the adhesion between the Z pin 3 and the fiber sheet 4, and may be applied in various ways such as a spray method, an immersion method, and the like, but is not limited thereto. .

Here, the adhesive may include 100 to 110 parts by weight of an epoxy resin, 40 to 90 parts by weight of a curing agent, 0.1 to 10 parts by weight of an amine-based accelerator, and 0.2 to 7 parts by weight of a silane coupling agent.

Epoxy resin is added to the adhesive to have adhesive performance, and when it is less than 100 parts by weight, the adhesive performance of the adhesive decreases, and when it exceeds 110 parts by weight, the viscosity is high and compatibility is lowered.

The epoxy resin may include at least one of a bisphenol A-type epoxy resin, a bisphenol F-type epoxy resin, a bisphenol S-type epoxy resin, a naphthalene-based epoxy resin, and an epoxy resin having a benzoazine structure.

A curing agent is added so that the epoxy resin can be cured. If it is less than 40 parts by weight, there is a problem that curing does not proceed completely. This is not preferable because it may cause deterioration of physical properties.

In addition, the curing agent may include an acid anhydride-based curing agent and a condensate of formaldehyde and phenol.

Here, the acid anhydride-based curing agent is phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, and methylhexahydride It may be at least one selected from the group consisting of loftalic anhydride.

In this case, it is preferable to use a mixture of two or more types of the acid anhydride-based curing agent rather than using it alone.

In this case, the condensate of formaldehyde and phenol is preferably used in an amount of 15 to 25 parts by weight, most preferably 20 parts by weight, based on 100 parts by weight of the acid anhydride-based curing agent. If the amount of the condensate of formaldehyde and phenol exceeds 25 parts by weight, the curing time is too short, and the compatibility decreases due to an increase in viscosity, which may indicate deterioration of physical properties. There is a problem that is not enough.

The amine-based accelerator can increase the curing speed of the adhesive, and when it exceeds 10 parts by weight, the pot life is too short, and physical properties may deteriorate due to the influence of by-products during the reaction. It is not preferable because there is a problem that it does not work.

The silane coupling agent is for enhancing the adhesion of the adhesive, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N- (2-aminoethyl)-3-aminopropyltris(2-ethylethoxy)silane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl)ethyltrimethoxysilane, (3-glycidoxypropyl)methyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, N-phenylaminopropyltrimethoxysilane, bis [3-(trisethoxysilyl)propyl]tetrasulfide, 3-mercaptopropylmethyldimethoxysilane, or 3-mercaptopropyltrimethoxysilane.

When the amount of the silane coupling agent is less than 0.2 parts by weight, the adhesion enhancing effect is insignificant, and when it exceeds 7 parts by weight, there is a problem in that the adhesive strength of the adhesive is lowered.

The adhesive prepared in this way not only has excellent adhesion, but also has an ultra-high heat resistance with a glass transition temperature of 170° C. or higher, and has the advantage of exhibiting excellent mechanical properties, so that it can be used in various fields.

In addition, in the present invention, in order to facilitate the adjustment of the viscosity of the adhesive, it further comprises a diluent commonly used in the industry, or, if necessary, a coloring pigment, a solvent, a plasticizer, a thickener, an antifoaming agent, a leveling agent, a filler, etc. It can also be used by adding.

It is possible to provide a composite structure manufactured by the molding method as described above.

Such a composite structure basically has the effect of reinforcing the delamination performance by applying the method of inserting the Z-pin in the thickness direction of the composite structure.

In addition, when connecting the composite structure and the additional member, there is an advantage in that the strength of the bonding portion can be supplemented by bonding using a Z pin.

Hereinafter, experimental examples carried out are presented to aid understanding, and are merely illustrative of the present invention, and the scope of the present invention is not limited to the following experimental examples.

[Example 1]

105 parts by weight of an epoxy resin (bisphenol A type epoxy resin), 50 parts by weight of a curing agent, 0.3 parts by weight of an amine accelerator, and 0.5 parts by weight of a silane coupling agent (N-(2-aminoethyl)-3-aminopropyl methyldimethoxysilane) An adhesive was prepared by mixing.

At this time, the curing agent was mixed with 100 parts by weight of an acid anhydride-based curing agent (phthalic anhydride) and 20 parts by weight of a condensate of formaldehyde and phenol.

[Example 2]

An acid anhydride-based curing agent was prepared in the same manner as in Example 1, except that phthalic anhydride, maleic anhydride, and trimellitic anhydride were mixed in a ratio of 1:1:1.

[Comparative Example 1]

It was prepared in the same manner as in Example 1, except that the curing agent was 110 parts by weight.

[Comparative Example 2]

It was prepared in the same manner as in Example 1, except that the silane coupling agent was 0.1 parts by weight.

[Comparative Example 3]

It was prepared in the same manner as in Example 1 except that the amine-based accelerator was 15 parts by weight.

[Experimental Example 1] Specimen preparation

Examples 1 to 2 and Comparative Examples 1 to 3 were blended together, stirred at 40 to 60° C., and then dried under reduced pressure at room temperature in a vacuum oven at room temperature to remove residual organic solvents and bubbles in the adhesive.

After the adhesive was filled in a mold, a specimen was prepared under curing conditions of 110° C. for 1 hour and 180° C. for 2 hours in a convection oven.

[Experimental Example 2] Glass transition temperature and breakthrough toughness measurement

For each specimen prepared in Experimental Example 1, the glass transition temperature was measured by a differential calorimetry (DSC; DSC 200, NETZSCH, Germany) method, and also, a universal test machine (UTM; LR5K, Lloyd Instruments Ltd.) , United Kingdom) was used to measure fracture toughness, and the results are summarized in Table 1.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Glass transition temperature (℃) 186 187 185 128 179 Fracture toughness (MPa·m ^½ ) 2.7 2.8 2.3 2.7 2.3

As shown in Table 1, Examples 1 and 2 were confirmed to be excellent in all items.

In the case of Comparative Example 1, it was confirmed that the fracture toughness value was lowered than in Example 1 as the weight ratio of the curing agent exceeded the standard, and in Comparative Example 2, the glass transition temperature was decreased as the weight ratio of the silane coupling agent was lower than the standard. lowering could be observed. In the case of Comparative Example 3, it was confirmed that the fracture toughness value was lowered because the amine-based accelerator exceeded the standard.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto. is within the scope of the right.

1: mold
2: patch
3: Z pin
4: Fiber sheet
5: Resin
7: Insertion groove
8: patch hole
10: Composite structures
20: no additional

Claims (8)

Mold preparation step of preparing the mold;
a mold processing step of forming an insertion groove so that the Z-pin patch can be embedded in the upper surface of the mold;
a Z-pin patch insertion step of inserting the Z-pin patch into the insertion groove;
a fiber sheet lamination step of laminating a fiber sheet on the upper surface of the mold;
A vacuum step of arranging vacuum system materials to create a vacuum inside the mold;
a resin injection step of injecting a resin after the vacuum step;
After the resin injection step, demolding step of demolding the cured composite structure from the mold;
A patch removal step of removing the patch portion of the Z-pin patch attached to the composite structure, and
a bonding step of bonding an additional member to the composite structure;
The bonding step is
In a state in which the composite structure and the additional member are temporarily assembled, a fiber sheet is laminated to surround the portion where the Z-pin part of the composite structure and the additional member are connected, and a resin is injected into the fiber sheet in a handlay-up method, then A method of forming a composite structure, characterized in that it is cured and joined.
According to claim 1,
The Z pin patch,
Patches made of rubber material and
A method of forming a composite structure comprising a Z-pin including a plurality of Z-pins inserted into the patch.
3. The method of claim 2,
The patch is
and a patch hole formed so that the Z pin can be easily separated from the patch in the patch removal step,
The patch hole is
A method for forming a composite structure, characterized in that the hole is formed in a zigzag shape in which both sides are symmetrical to reduce the contact area between the patch and the Z-pin.
delete 3. The method of claim 2,
After the Z-pin patch insertion step,
Further comprising an adhesive application step of applying an adhesive to the Z-pin to increase the adhesion between the Z-pin and the fiber sheet,
The adhesive is
100 to 110 parts by weight of an epoxy resin, 40 to 90 parts by weight of a curing agent, 0.1 to 10 parts by weight of an amine-based accelerator, and 0.2 to 7 parts by weight of a silane coupling agent,
The curing agent,
In 100 parts by weight of an acid anhydride-based curing agent, a method of forming a composite structure comprising 15 to 25 parts by weight of a condensate of formaldehyde and phenol.
delete 6. The method of claim 5,
The acid anhydride-based curing agent,
selected from the group consisting of phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, and methylhexahydrophthalic anhydride A method for molding a composite structure, characterized in that at least one type is used.
A composite structure manufactured by the method of any one of claims 1 to 3, 5 and 7.

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