KR102324411B1 - Method for making torsion box having assembled multi-spars and the torsion box made by the method - Google Patents

Abstract

It is an object of the present invention to provide a multi-spar integrated torsion box manufacturing method and a torsion box by the manufacturing method, which can improve productivity, quality and economic feasibility by breaking away from the autoclave prepreg molding method when manufacturing the torsion box. . In more detail, the shape of each element constituting the torsion box is formed by using a braiding process of weaving dry fibers, and various elements are put in an integrated jig and a resin material is injected into a complete one-piece using the RTM process. To provide a multi-spar integrated torsion box manufacturing method for manufacturing a torsion box, and a torsion box by the manufacturing method.

Description

Multi-spar integrated torsion box manufacturing method and torsion box according to the manufacturing method {Method for making torsion box having assembled multi-spars and the torsion box made by the method}

The present invention relates to a method for manufacturing a multi-spar integrated torsion box and a torsion box by the manufacturing method, and more particularly, to improve the productivity, quality and economic feasibility of a torsion box, which is a box-type structure that is inserted into an aircraft wing and transmits torsional rotational force. It's about making technology that allows you to improve.

A torsion box refers to a box-shaped structure of a closed cross-section that transmits torsional rotational force, and is generally inserted into an aircraft wing or the like. There are also torsion beams and torsion bars as structures for transmitting torsional rotational force. When a torsion beam is applied to an aircraft wing, a plurality of torsion beams are required because it is difficult to cope with stress with one beam. However, when a plurality of torsion beams are inserted, there is a problem in that stress is concentrated on the shell and ribs between the beams. Accordingly, a torsion box is a box-shaped structure including a plurality of torsion beams, but with a strong outer shell. That is, in general, a torsion box is composed of a skin, a spar, and a lip. Figure 1 shows an embodiment of a conventional torsion box, in the conventional torsion box 10, a pair of spars (1) extending long in the front and rear as shown are spaced apart, and the spars (1) ) has a structure in which a plurality of ribs 2 are arranged in a direction perpendicular to the extending direction (that is, in a direction extending across the spar 1). In addition, the skin 3 is disposed on the upper and lower surfaces of the structure composed of the spar 1 and the lip 2 as described above to appropriately distribute the stress. 1 is shown in a form in which the skin 3 of the upper surface is omitted in order to show the arrangement structure of the spar 1 and the lip 2 well.

As such, the conventional torsion box has a shape in which the spar 1 and the lip 2 are intricately intertwined, and thus resources such as considerable time, manpower, and cost tend to be wasted in the assembly process. Accordingly, a form in which the lip, which is a factor that increases the geometrical complexity of the torsion box, is removed is being considered, but the lip serves to support the torsion, which is the main role of the torsion box, so there is a fear that the rigidity may be reduced. Therefore, when the torsion box is manufactured in a shape with the lip removed, it is necessary to introduce a technology capable of manufacturing a spar that has higher rigidity than the spar included in the conventional torsion box and can stably and uniformly maintain quality during production. .

Meanwhile, as described above, the torsion box is inserted into an aircraft wing and the like, and is generally made of composite materials to increase strength while lightening the weight. Composite material refers to a material obtained by soaking a high-strength fiber material such as glass fiber or carbon fiber in resin and hardening it. In order to produce a desired shape from a composite material, in general, a method of molding a prepreg into a desired shape and curing the resin by heating and pressing using an autoclave is used. Here, the prepreg also refers to a fiber material impregnated with a resin material to form a gel, and when it is polymerized and heated, a laminated molded article is produced by softening and fusion bonding. European Patent Registration No. 2153949 ("MULTISPAR TORSION BOX MADE FROM COMPOSITE MATERIAL", 2016.10.19., hereinafter 'prior literature') discloses a technology for manufacturing a torsion box structure through prepreg molding using an autoclave as described above. . In the prior literature, in order to manufacture the various elements constituting the torsion box, several layers of prepreg are stacked to form a stack, and the shape of each element is formed through operations such as giving the stack a curve, and then the shaped stacks are Disclosed is a technology for realizing co-curing by fixing to an appropriate jig and molding at once using an autoclave.

However, when using the autoclave prepreg molding method as described above, there are several problems as follows. First, since the prepreg itself is a fairly expensive material, the cost of manufacturing a structure using the prepreg is very high. In addition, as disclosed in the prior literature, several elements constituting the torsion box are separately made and then combined to form an integral body. It becomes a factor in the non-uniformity of the product quality and the increase in the defect rate.

1. European Patent Registration No. 2153949 ("MULTISPAR TORSION BOX MADE FROM COMPOSITE MATERIAL", 2016.10.19.)

Therefore, the present invention has been devised to solve the problems of the prior art as described above, and an object of the present invention is to break away from the autoclave prepreg molding method when manufacturing a torsion box to improve productivity, quality and economy. To provide a multi-spar integrated torsion box manufacturing method and torsion box by the manufacturing method. In more detail, the shape of each element constituting the torsion box is formed by using a braiding process of weaving dry fibers, and various elements are put in an integrated jig and a resin material is injected into a complete one-piece using the RTM process. To provide a multi-spar integrated torsion box manufacturing method for manufacturing a torsion box, and a torsion box by the manufacturing method.

The multi-spar-integrated torsion box manufacturing method of the present invention for achieving the above object includes a plurality of spars 110 and a pair of skins 120 provided on upper and lower surfaces of the arrangement of the spars 110 A method of manufacturing the torsion box 100, comprising: a braiding step in which a dry fiber is woven by a braiding process to produce a raw material 150; A preform molding step in which the raw material 150 is accommodated in a molding mold and heated and pressed, whereby the preform 155 having the shape of the torsion box 100 is molded; a resin transfer molding (RTM) step in which the preform 155 is accommodated in a curing mold and the resin is injected and cured to produce the torsion box 100; may include.

In this case, in the torsion box manufacturing method, since the curing mold surrounds the entire preform 155 , the torsion box 100 can be manufactured integrally by the RTM step.

Also at this time, in the torsion box manufacturing method, since the molding mold is formed in a shape corresponding to each of the spar 110 or the skin 120, the spar 110 and the skin 120 by the preform molding step ) can be produced as a separate entity.

In addition, in the RTM step, in the mixture of the dry fiber and the resin, the ratio of the dry fiber may be within the range of 55% by volume to 70% by volume.

In addition, the torsion box manufacturing method, before the braiding step, a binder adding step of adding a binder to the dry fiber; may further include.

In this case, in the step of adding the binder, in the mixture of the dry fiber and the binder, the proportion of the binder may be within the range of 1 wt% to 5 wt% of the weight of the dry fiber.

In addition, the torsion box 100 of the present invention includes, in the torsion box 100 manufactured by the torsion box manufacturing method as described above, a plurality of spars 110 extending in one direction and disposed parallel to each other; a pair of skins 120 formed in a planar shape and provided on upper and lower surfaces of the arrangement of the spars 110; may include.

At this time, the spar 110 is formed in a planar shape perpendicular to the plane formed by the skin 120 and has a planar shape parallel to the plane formed by the body 111 and the skin 120 extending in one direction. The cross section of the spar 110 may be formed in a U-shape or a U-shape, including a connection part 112 connected to the upper and lower ends of the body part 111 .

In addition, the torsion box 100, a pair of the spar 110 is disposed on the front and rear outermost sides of the torsion box 100, between the outermost pair of the spar 110, at least The two spars 110 may be disposed.

In addition, the torsion box manufacturing jig 500 of the present invention, in the torsion box manufacturing jig 500 for integrally manufacturing the torsion box 100 as described above through the RTM process, as long as it is disposed on the outermost side A pair of anterior and posterior teeth 510 disposed on the front and rear outermost sides to form the front or rear outermost surfaces of the pair of spars 110; A plurality of spas ( 110) a plurality of inner fixtures 515 disposed between the pair of the front and rear fixtures 510 to form the front or rear side of them; a pair of upper and lower fixtures 520 disposed on the upper or lower surfaces of the front and rear fixtures 510 and the inner fixture 515 to form the outermost upper surface or lower surface of the skin 120; may include.

At this time, in the torsion box manufacturing jig 500, the body portion 111 of the spar 110 is formed by the front or rear side surfaces of the front and rear fixtures 510 and the inner fixture 515, The connection part 112 of the spar 110 may be formed by the grooves formed at the upper and lower front and rear ends of the front and rear fixtures 510 and the inner fixture 515 .

In addition, it is preferable that the inner jig 515 is provided with a plurality of ribs 511 spaced apart from each other in the extending direction inside the inner jig 515 to prevent deformation due to its own weight.

According to the present invention, when applying the conventional autoclave prepreg molding method, since the process of laminating each element in the process of integrating and integrating several elements is done manually, there is a problem of increasing the non-uniformity and defect rate of the produced product quality On the contrary, by introducing the braiding method, automated lamination is possible, so that all processes can be automated, resulting in various productivity improvements such as reducing the number of processes and ensuring uniformity of quality. In particular, according to the present invention, the torsion box structure can be manufactured at once by performing the RTM process through the integrated jig, thereby further improving the effect of reducing the number of processes.

In addition, according to the present invention, in the case of the conventional autoclave prepreg molding method, unlike the use of expensive prepreg, each element can be manufactured using a low-priced dry fiber, so the cost is much reduced compared to the prior art. It has the effect of improving economic efficiency.

In addition, according to the present invention, unlike the existing torsion box consisting of spar, lip, and skin, the torsion box is formed of a multi-spar structure with ribs removed, that is, the torsion box can be manufactured in a simpler shape than in the prior art. As a result, it is possible to obtain the effect of further improving the productivity, and also the effect of significantly reducing the weight compared to the existing one. In this case, it is of course possible to save weight and maintain rigidity through optimization techniques and structural analysis.

1 is an embodiment of a conventional torsion box.
Figure 2 is an embodiment of a torsion box manufactured by the manufacturing method of the present invention.
Figure 3 is a flow chart of the torsion box manufacturing method of the present invention.
4 is an embodiment of a composite woven fabric produced by a braiding process.
Figure 5 is a step diagram of the torsion box manufacturing method of the present invention.
6 is an embodiment of an integral jig used in the RTM process.
7 is a detailed view of the inner jig.
Figure 8 is an embodiment of the assembly method of the jig of Figure 6;

Hereinafter, a method for manufacturing a multi-spar integrated torsion box according to the present invention having the configuration as described above and a torsion box according to the manufacturing method will be described in detail with reference to the accompanying drawings.

Figure 2 shows an embodiment of the torsion box manufactured by the manufacturing method of the present invention. As shown, the torsion box 100 of the present invention is a form in which the lip is removed, that is, only the spa 110 and the skin 120, unlike the conventional torsion box consisting of a spar, a lip, and a skin. More specifically, the torsion box 100 of the present invention, as shown in FIG. 2(A), is formed in a planar shape with a plurality of spars 110 extending in one direction and arranged parallel to each other, and the spar 110 ) includes a pair of skins 120 provided on the upper and lower surfaces of the arrangement.

At this time, the spar 110, as shown in FIG. 2(B), is formed in a planar shape perpendicular to the plane formed by the skin 120 and includes a body part 111 extending in one direction and the skin. It is formed in a plane shape parallel to the plane formed by 120 and includes a connection part 112 connected to the upper and lower ends of the body part 111, and the cross section of the spar 110 may be made in a U-shape or a U-shape. . By allowing the connection part 112 to form a plane parallel to the skin 120 , the coupling force between the spar 110 and the skin 120 may be improved. More specifically, when the spar 110 is disposed on the outermost side, it may be better not to have a portion protruding further outward. desirable. Alternatively, when the spar 110 is disposed on the inside, it is preferable to be combined with the skin 120 in a balanced manner on both sides of the body 111. It is preferable to become

In addition, in the torsion box 100 of the present invention, as shown in FIG. 2 , a pair of the spar 110 is disposed on the front and rear outermost sides of the torsion box 100 , the outermost pair Between the spas 110 of the, at least two of the spas 110 may be arranged in a form. In the related art, as shown in FIG. 1 , a pair of spars are disposed at the front and rear outermost sides of the torsion box, and a plurality of ribs are disposed in a direction transverse to the spar. However, in the present invention, the lip is removed in order to reduce the complexity of the structure and reduce the weight. However, if the lip is only removed, the rigidity supporting the torsion that the lip is responsible for may be reduced. Accordingly, the inner spar is disposed between the front and rear spars to reinforce the rigidity, and at this time, the inner spar is arranged such that a plurality of at least two or more are arranged, thereby reducing the weight and sufficiently reinforcing the rigidity.

Hereinafter, a method of manufacturing the torsion box of the present invention as described above will be described in detail step by step.

3 is a flowchart of a method for manufacturing a torsion box of the present invention, FIG. 4 is an embodiment of a composite woven fabric manufactured by a braiding process, and FIG. 5 is a step diagram of a method for manufacturing a torsion box of the present invention. 3, the torsion box manufacturing method of the present invention basically includes a braiding step, a preform molding step, and an RTM step, and a binder adding step may be further performed before the braiding step.

In the braiding step, the dry fiber is woven by a braiding process to produce the raw material 150 . Braiding is one of several ways of weaving composite fibers, and is divided into two-dimensional and three-dimensional according to the desired shape. 3D braiding is a process in which multiple braiding layers can be implemented, and angle change, thickness change, curvature and diameter change are possible for each section. The braiding process is easy to automate, has high productivity, and has high reproducibility, so it is suitable for manufacturing the raw material 150 for manufacturing the preform 155 of the composite material. 4 shows an embodiment of a composite woven fabric produced by a braiding process, and as shown, the raw material 150 shows that fibers such as carbon fibers constituting the composite are woven to form a woven fabric. are giving

However, since the raw material 150 produced through the braiding step is made in the form of a dry fiber woven fabric, for example, if the mold surface is formed horizontally, the raw material 150 is well supported on the mold surface and is horizontally flat. However, if the mold surface is formed vertically, the raw material 150 may not be attached to the mold surface, and there is a risk that it may flow down or wrinkle occurs. In order to solve this problem, it is preferable that a binder adding step of adding a binder to the dry fiber is further performed before the braiding step. The binder is a resin material having adhesiveness, and as described above, the preform 155 made of the raw material 150 is added to adhere well to the mold surface so that the shape is not disturbed. However, in order to avoid an unwanted effect on the braiding process due to the binder, the proportion of the binder in the mixture of the dry fiber and the binder is preferably 5% or less by weight of the dry fiber. On the other hand, when too little binder is included, sufficient adhesive strength cannot be obtained. Therefore, it is preferable that the ratio of the binder in the mixture of the dry fiber and the binder be 1% by weight or more of the weight of the dry fiber. That is, in summary, in the mixture of the dry fiber and the binder in the binder addition step, it is preferable that the proportion of the binder is in the range of 1 wt% to 5 wt% of the dry fiber weight.

In the preform forming step, the raw material 150 is accommodated in the forming mold as shown in FIG. 5(A), and is heated and pressed as shown in FIG. A preform 155 of At this time, since the molding mold is formed in a shape corresponding to each of the spar 110 or the skin 120, the spar 110 and the skin 120 are produced as separate entities by the preform molding step. it is preferable That is, the shape of the torsion box 100 is not completely formed in the preform forming step, but the elements forming the torsion box 100, that is, the spar 110 and the skin 120 are separate entities. will be made The preform 155 thus made is taken out from the forming mold as shown in FIG. 5(C) and accommodated in a curing mold as shown in FIG. 5(D) for the next step.

In the resin transfer molding (RTM) step, after the preform 155 is accommodated in the curing mold, the resin is injected and cured as shown in FIGS. 5 (E) and 5 (F), whereby the torsion The production of the box 100 is completed. At this time, in the present invention, since the curing mold is formed to surround the entire preform 155 , the torsion box 100 is manufactured integrally by the RTM step. That is, in the preform molding step, the spar 110 and the skin 120 are not coupled to each other and are made in separate individual shapes, but in the RTM step, the spar 110 and the skin 120 are combined. By curing in the form of forming, the torsion box 100 can be manufactured integrally through the RTM step.

On the other hand, since the torsion box 100 of the present invention is a form in which the lip is removed from the conventional torsion box, a plurality of the spars 110 are arranged on the inside to supplement the rigidity of supporting the torsion. However, it is difficult to completely supplement the torsion support rigidity only with the geometrical structure, and therefore, it is preferable to form a higher ratio of fibers compared to the manufacturing of the conventional torsion box. On the other hand, if the ratio of the dry fibers is too high, the resin ratio is lowered, so that the adhesion between the dry fibers may be weakened. Considering these factors, in the mixture of the dry fiber and the resin in the RTM step, it is preferable that the ratio of the dry fiber is made within the range of 55% by volume to 70% by volume.

FIG. 6 shows an embodiment of an integrated jig used in the RTM process. Referring to FIG. 6 , four spars 110 spaced apart from each other and a pair of spars 110 disposed on the upper and lower surfaces of the arrangement It can be seen that the jig completely surrounds all the outer surfaces of the assembly made of the skins 120 of the jig. In this state, by injecting and curing the resin, the torsion box 100 can be smoothly manufactured as an integral body.

The configuration of the torsion box manufacturing jig 500 for integrally manufacturing the torsion box 100 of the present invention as shown in FIG. 6 through the RTM process will be described in more detail as follows. The torsion box manufacturing jig 500 is, as shown in FIG. 6 , a pair of front and rear fixtures 510 disposed on the front and rear outermost sides, and a plurality of disposed between the pair of front and rear fixtures 510 . The inner jig 515, the front and rear jigs 510, and a pair of upper and lower jigs 520 disposed on the upper surface or the lower surface of the inner jig 515 are included. At this time, the inner jig 515 includes an inner upper jig 515a and an inner lower jig 515b coupled in the vertical direction.

The torsion box manufacturing jig 500 made in this way, the front or rear outermost surface of the pair of spar 110 disposed on the outermost side is formed by the pair of front and rear jigs, and a plurality of the inner jigs The front or rear inner surface of the pair of spars 110 arranged on the outermost side by 515 and the front or rear side surfaces of the plurality of spars 110 arranged on the inner side are formed. More specifically, as shown in FIG. 6 , the body portion 111 of the spar 110 is formed by the front or rear side surfaces of the front and rear fixtures 510 and the inner fixture 515 , The connection part 112 of the spar 110 is formed by the grooves formed at the upper and lower front and rear ends of the front and rear fixtures 510 and the inner fixture 515 . In addition, the outermost upper surface or lower surface of the skin 120 is formed by the pair of upper and lower fixtures 520 .

Figure 7 is a detailed view of the inner jig, Figure 8 shows an embodiment of the assembly method of the jig of Figure 6, respectively. As shown in FIG. 8, the inner jig 515 is formed by combining the inner upper jig 515a and the inner lower jig 515b, and the inner side of the inner jig 515 is as shown in FIG. A plurality of ribs 511 spaced apart from each other in the extending direction are formed. By forming the inner jig 515 in this way, the deformation caused by the weight of the long-shaped jig can be effectively prevented. In addition, by separately forming the inner jig 515 into the inner upper jig 515a and the inner lower jig 515b, it becomes much easier to manufacture the shape of the rib 511 .

The present invention is not limited to the above-described embodiments, and the scope of application is varied, and anyone with ordinary knowledge in the field to which the present invention pertains without departing from the gist of the present invention as claimed in the claims It goes without saying that various modifications are possible.

100: torsion box
110: spa 120: skin
150: raw material 155: preform
500: jig for making torsion box
510: anterior and posterior jig 515: inner jig
515a: inner upper fixture 515b: inner lower fixture
511: rib 520: upper and lower fixture

Claims (12)

A plurality of spars 110 extending in one direction and disposed parallel to each other; a pair of skins 120 formed in a planar shape and provided on upper and lower surfaces of the arrangement of the spars 110; In the torsion box manufacturing method of manufacturing the torsion box 100 comprising a,
The spar 110 is formed in a plane shape perpendicular to the plane formed by the skin 120 and is formed in a plane shape parallel to the plane formed by the body part 111 and the skin 120 extending in one direction. and including a connection part 112 connected to the upper and lower ends of the body part 111, the cross section of the spar 110 is made in a U-shape or 工-shape,
The torsion box 100, a pair of the spar 110 is disposed on the front and rear outermost sides of the torsion box 100, between the outermost pair of the spar 110, at least two It is made in a form in which the spa 110 of the dog is disposed,
The torsion box manufacturing method is,
A pair of anterior and posterior jigs 510 disposed on the front and rear outermost sides to form the front or rear outermost surfaces of the pair of spar 110 disposed on the outermost side; A plurality of spas ( 110), a plurality of ribs 511 disposed between a pair of the anterior and posterior teeth 510 to form the front or rear side surfaces of the ribs 511 spaced apart from each other in the extension direction to prevent deformation due to their own weight are formed dog's inner jig (515); a pair of upper and lower fixtures 520 disposed on the upper or lower surfaces of the front and rear fixtures 510 and the inner fixture 515 to form the outermost upper surface or lower surface of the skin 120; includes,
The body portion 111 of the spar 110 is formed by the front or rear side surfaces of the front and rear fixtures 510 and the inner fixture 515 , and the front and rear fixtures 510 and the inner fixture 515 . A jig 500 for manufacturing a torsion box is used so that the connection part 112 of the spar 110 is formed by the grooves formed at the upper and lower front and rear ends,
A braiding step in which the dry fiber is woven by a braiding process to produce the raw material 150;
A preform molding step in which the raw material 150 is accommodated in a molding mold and heated and pressed, whereby the preform 155 having the shape of the torsion box 100 is molded;
A resin transfer molding (RTM) step in which the preform 155 is accommodated in a curing mold made of the jig 500 for manufacturing the torsion box, and the resin is injected and cured to produce the torsion box 100;
includes,
In the preform forming step, the forming mold is formed in a shape corresponding to each of the spar 110 or the skin 120, so that the spar 110 and the skin 120 are separated by the preform forming step. made as an object,
In the RTM step, the curing mold surrounds the entire preform 155, so that the torsion box 100 is integrally manufactured by the RTM step,
The step of the curing mold surrounding the entire preform 155,
disposing the spar 110 and the skin 120 produced by the preform forming step in the form of the torsion box 100;
forming the inner jig 515 by combining the inner upper jig 515a and the inner lower jig 515b in the vertical direction;
The inner fixture 515 is moved in the extension direction to be disposed between the plurality of spars 110, and the front and rear fixtures 510 are moved in the front-rear direction to move in the front-rear direction of the pair of spars 110 disposed on the outermost side. Disposed in the front or rear, the upper and lower fixtures 520 are moved in the vertical direction to be disposed on the outermost upper surface or lower surface of the skin 120
A torsion box manufacturing method comprising a.
delete delete According to claim 1, wherein the RTM step,
In the mixture of dry fiber and resin, the torsion box manufacturing method, characterized in that the ratio of the dry fiber is made within the range of 55% by volume to 70% by volume.
According to claim 1, wherein the torsion box manufacturing method,
Before the braiding step, a binder adding step of adding a binder to the dry fiber;
Torsion box manufacturing method, characterized in that it further comprises.
The method of claim 5, wherein the adding of the binder comprises:
A method of manufacturing a torsion box, characterized in that in the mixture of the dry fiber and the binder, the proportion of the binder is within the range of 1 wt% to 5 wt% of the dry fiber weight.
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