KR101199606B1 - Three dimensional lattice truss structures and manufacturing method of the same - Google Patents

Abstract

The present invention relates to a three-dimensional grating truss structure and a method of manufacturing the same, in the three-dimensional grating truss structure composed of a continuous wire group, intersecting with azimuth angle of 90 degrees in space to form a two-dimensional truss network of the net structure At every intersection, including a plurality of spiral wire groups that are arranged in multiple stages and a separate spiral wire group that intersects in a direction perpendicular to the two-dimensional truss network at a half pitch point between the intersection of the plurality of wire groups and an adjacent intersection point A three-dimensional grating truss structure comprising a spiral wire group in two directions perpendicular to each other and a manufacturing method of the three-dimensional grating truss structure, by minimizing the bending between each wire and the interference between the wires by weight New form of 3D grid with high strength, rigidity and large surface area Russ provides structure and method for manufacturing them at a low cost / mass.

Description

THREE DIMENSIONAL LATTICE TRUSS STRUCTURES AND MANUFACTURING METHOD OF THE SAME

The present invention relates to a three-dimensional grating truss structure and a method of manufacturing the same, in particular, by reducing the number of wires encountered at the intersection point to minimize the bending of the wires and the interference between the wires to control the density of the wire in a certain space, The present invention relates to a three-dimensional grating truss structure capable of improving thermal and aerodynamic characteristics and a method of manufacturing the same.

Conventionally, metal foams have been mainly used as lightweight structural materials. Such a foamed metal is generally produced by a method of generating bubbles inside a metal in a liquid or semi-solid state (closed type) or by casting with an open foamed resin such as a sponge as a mold (open type). However, since the foamed metal has an irregular internal shape, there is an inevitably weak part. Accordingly, mechanical properties such as strength and stiffness are relatively poor, thereby limiting the practical use for engineering applications.

Accordingly, recently, an open lightweight structure having a periodic truss structure has been developed as a material for replacing a foamed metal. This open lightweight structure is excellent in mechanical properties because it consists of a truss structure designed to have the optimum strength and stiffness through precise mathematical / mechanical calculations.

Here, the most common type of truss structure is an octet truss (R. Buckminster Fuller, 1961, US Patent 2,986,241) in which a tetrahedron and an octahedron are combined. Octet truss is an excellent triangle in terms of strength and stiffness because each element of the truss form an equilateral triangle.

In addition, Kagome truss (S.Hyun, AM Karlsson, S. Torquato, AGEvans, 2003. Int. J. of Solids and Structures, Vol. 40, pp.6989-6998) ) Was announced. In this case, when the truss is composed of an elongated member having the same cross section, if the length of the entire member constituting the structure is the same, the length of the truss element constituting the kagome truss is equal to 1/2 of the truss element constituting the octet truss. Because of this, buckling, which is the main fracture phenomenon of the truss structure, is more effectively suppressed, and even if buckling occurs, the collapse process is much more stable. For reference, FIG. 1 illustrates a three-dimensional kagome truss multilayer structure.

On the other hand, the following methods are known as a method for producing a truss-shaped porous lightweight structure.

First, a method of making a truss structure out of a resin and casting a metal using the mold (S. Chiras, DR Mumm, N. Wicks, AG Evans, JW Hutchinson, K. Dharmasena, HNG Wadley, S. Fichter, 2002) , International Journal of Solids and Structures, Vol. 39, pp. 4093-4115).

Second, a method of forming a truss intermediate layer by periodically drilling a thin metal plate and bending it to form a truss intermediate layer and attaching a face plate to the upper and lower portions respectively (DJ Sypeck and HNG Wadley, 2002, Advanced Engineering Materials, Vol. 4, pp.759 ~ 764) (hereinafter referred to as 'Notice Technology 2'). In this case, when making a multilayer structure of two or more layers, a method of attaching a truss intermediate layer made by bending as described above on the upper face plate and attaching the face plate on it is used.

Third, a method of weaving a wire mesh in the form of two perpendicular wires, and laminating and joining them (DJ Sypeck and HGN Wadley, 2001, J. Mater. Res., Vol. 16, pp.890 ~ 897) , 'Known technology 3').

However, the known technology 1 is expensive because of the complicated manufacturing process, and can be manufactured only in the case of a metal having excellent castability, so that the application range is narrow, and the result is that the cast structure has many defects and strength. There is a tendency to be lacking. In addition, the well-known technique 2 has a lot of material loss in the process of punching a thin metal plate, and there is no particular problem when the truss intermediate layer is composed of one, but when the multiple truss intermediate layers are to be laminated, the joining cost increases and the strength increases. There are disadvantages in that. Meanwhile, even in the case of the known technology 3, the formed truss is not an ideal structure such as a tetrahedron or a pyramid, and thus is inferior in mechanical strength. It is disadvantageous in terms of cost and strength.

2 is a view showing a structure manufactured using the known technology 3.

More specifically, the known technology 3 is known to reduce the manufacturing cost, but as shown in Figure 2 simply combine the wires of the two directions as weaving fibers, such as the above-mentioned three-dimensional octet truss or three-dimensional kagome truss It is not an ideal structure that is optimized for mechanical or electrical properties, such as, there are too many parts to be joined is disadvantageous in terms of cost or strength.

Therefore, two of the inventors, including Kang Gi-joo, have an ideal kagome truss or octet truss by intersecting a continuous group of wires in six directions having an azimuth angle of 60 degrees or 120 degrees in space to solve the problems of the above-described known techniques. A three-dimensional porous lightweight structure having a similar shape and a method of manufacturing the same have been developed, and the details thereof are disclosed in Korean Patent No. 0708483 filed by the applicant.

In addition, the inventors of the present invention can more efficiently manufacture a three-dimensional porous lightweight structure, a three-dimensional porous lightweight structure woven from a spiral wire that is assembled by first forming a continuous wire spirally, then rotating and inserting the same, and manufacturing the same. A method has been proposed, the contents of which are disclosed in published patent application No. 2006-0130539 filed by the applicant.

3 is a view showing a structure assembled with a spiral wire similar in shape to the three-dimensional kagome truss of FIG. 1 in the patent application.

The three-dimensional multilayer truss structure composed of spiral wires having a shape similar to that of the kagome truss shown in FIG. 3 has various advantages over the prior art, such as excellent mechanical properties and mass production by a continuous process.

However, when the above-mentioned three-dimensional multilayer truss structure is manufactured in the form of a generally used rectangular parallelepiped, the shape of the unit cell existing at the edge is not intact, which is not good in appearance and disadvantages in terms of mechanical strength, as well as interference between wires. Due to this there is a limit to increasing the placement density of the wire.

Therefore, the inventors have proposed a method of manufacturing a new three-dimensional porous lightweight structure that can be manufactured with a spiral wire, but has a different form from the kagome truss in Patent Application No. 10-2009-0080085. For reference, FIGS. 4 to 8 show an ideal shape of the truss structure similarly implemented using wires in the patent application, and FIGS. 9 to 13 show a shape similar to the multilayer truss structure of FIGS. 4 to 8. An example of assembling with a spiral wire is shown.

FIG. 14 is a view illustrating a unit cell constituting the multilayer truss structure of FIGS. 1 and 4 to 8, and FIG. 15 is a unit cell of a multi-layer truss structure assembled with spiral wires of FIGS. 3 and 9 to 13. Figure is a diagram.

However, the three-dimensional multilayer truss structure assembled with the spiral wires proposed in the above-described Patent Publication Nos. 2006-0130539 and 10-2009-0080085, as shown in Figs. 14 and 15, the points where the wires intersect. In the three, four or six wires are contacted with a constant azimuth angle. As such, the structure where a large number of wires meet at the intersection of the wires has to be preformed to have a large helical radius in order to assemble the spiral wires. There is a downside to falling.

The present inventors can recognize the above-mentioned problems and assemble a spiral wire, but have a structure where only two wires meet at a wire intersection point, thereby making a new three-dimensional grating truss that can be manufactured as a spiral wire having a smaller spiral radius. The present invention has been achieved as a structure and a method of manufacturing the same.

The present invention has been devised to solve the above-mentioned problems, and has a high strength and rigidity compared to the weight formed in a constant shape by assembling a series of three-way continuous spiral wires having azimuth angles of 90 degrees in space, and having a high surface area. It is an object of the present invention to provide a large new truss-shaped three-dimensional grating truss structure and a method for producing (manufacturing) it at low cost / bulk.

In addition, another object of the present invention is to provide a new three-dimensional grating truss structure and its manufacturing method which can be manufactured from a spirally shaped wire and having a different form from the existing truss.

It is still another object of the present invention to manufacture a three-dimensional lattice truss structure and its fabrication, which is not only excellent in shape of a unit cell present at the edges when manufactured in a rectangular parallelepiped form, but also of excellent aesthetic and mechanical strength, as well as an increase in wire placement density. To provide a way.

Another object of the present invention is formed by a method of directly assembling three-dimensionally in a continuous process using a spiral wire, rather than simply weaving a wire in the form of a net, only two wires at both points of intersection It is to provide a three-dimensional grating truss structure having a small cross point by contact and excellent in mechanical properties, thermal and aerodynamic properties, and a method of manufacturing the same.

As a means for solving the above technical problem,

The present invention is a three-dimensional grating truss structure consisting of a continuous wire group, a plurality of wire groups connected to each other (or intersected) to form a two-dimensional truss network and arranged in multiple stages and the connection point (or intersection point of the plurality of wire groups) Or a separate group of wires connected (or crossing) in a direction perpendicular to the two-dimensional truss network at an intermediate point between the connection point (or intersection point) and an adjacent connection point (or intersection point). It provides a three-dimensional grating truss structure.

In this case, at least one or more wire groups of the plurality of wire groups or the separate wire group may be formed of spiral wires.

In this case, the pitch or diameter of the plurality of wire groups and the separate wire group may be different.

In this case, the intersections of the plurality of wire groups and the separate wire groups may be fixed by any one of the joining means including resin bonding, welding, soldering, brazing or strapping by thin lines.

In addition, the present invention, in the three-dimensional grating truss structure composed of a continuous wire group, a plurality of spiral wire group and multi-stage arranged in a two-dimensional truss net of the network structure intersected with azimuth angle of 90 degrees to each other in space A spiral wire group in two directions perpendicular to each other at all intersections, including a separate spiral wire group that intersects in a direction perpendicular to the two-dimensional truss net at the half pitch point between the intersection of the multiple wire groups and the adjacent intersection points A three-dimensional grating truss structure is provided that is configured to intersect.

In addition, the present invention provides a method for manufacturing a three-dimensional grating truss structure, comprising the steps of: (a) arranging the first wire group in parallel at regular intervals, and (b) the first wire group in the first wire group. Forming a two-dimensional truss network by rotationally inserting a second group of wires having an azimuth angle of about 90 degrees with (a) and repeating steps (a) and (b). Forming, and (d) arranging a plurality of two-dimensional truss networks provided in the step (c) at regular intervals, and (e) an intersection point of the first wire group and the second wire group, or the intersection point. And inserting a third group of wires in a direction perpendicular to the two-dimensional truss net at an intermediate point between the adjacent intersection points and the adjacent intersection points. The.

In this case, the at least one other wire group may be composed of spiral wires.

In this case, the step (d) may further include the step of regularly parallelly moving the two-dimensional truss network in the plane by an interval less than the pitch of the two-dimensional truss network.

In this case, the manufacturing method of the three-dimensional grating truss structure is any one of the joining means including a resin bonding, welding, soldering, brazing, or the binding by a thin line at the intersection of each wire group after the step (e). The fixing may further include using.

According to the present invention, a plurality of wires of a predetermined length that are spirally prepared are prepared, and then arranged in parallel on the rectangular frame with a predetermined distance in a first axial direction parallel to one side of the frame, and then an azimuth angle of 90 degrees thereon. Placed at the same intervals as above in the second axial direction parallel to the other side of the frame having a net-shaped two-dimensional structure having a square hole, parallel to the two-dimensional structure at regular intervals in the direction perpendicular to the plane Of the three-dimensional grating truss structure composed of continuous wires by assembling by rotating the spiral wires in a third axial direction perpendicular to the first axis and the second axial direction to produce a three-dimensional grating truss structure. Manufacturing can be facilitated, thereby enabling mass production at low cost.

In addition, only two wires are contacted at each of the intersection points of the wires constituting the three-dimensional grating truss structure according to the present invention so that the size of the intersection points is small, thereby minimizing the bending and interference between the wires. Free control of the density of wires in the space gives a wide choice of mechanical, thermal and aerodynamic properties.

In addition, the three-dimensional lattice truss structure according to the present invention is a continuous wire is manufactured in a spiral shape while maintaining a shape close to the intended truss structure to improve the adhesion performance between the wires itself as a form assembled without a separate external support Since it can hold | maintain, a manufacturing process becomes simple, and a desired mechanical property can be obtained by fixing a wire cross point by methods, such as welding, brazing, soldering, liquid, or the binding by a thin wire.

1 shows a three-dimensional kagome truss multilayer structure,
2 is a view showing a structure manufactured using the known technology 3,
3 is a view showing a structure assembled with a spiral wire similar in shape to the three-dimensional kagome truss of FIG.
4 to 8 are views showing an ideal shape of the truss structure implemented using wires in Patent Application No. 10-2009-0080085, respectively,
9 to 13 illustrate an example of assembling a spiral wire similar to the multilayered truss structure of FIGS. 4 to 8, respectively.
14 is a view illustrating a unit cell constituting the multilayer truss structure of FIGS. 1 and 4 to 8;
FIG. 15 is a view illustrating unit cells of a multi-layered truss structure assembled with the spiral wires of FIGS. 3 and 9 to 13;
16 shows a three-dimensional grating truss structure according to the first embodiment of the present invention;
17 is a projection of FIG. 16;
18 illustrates a three-dimensional grating truss structure according to a second embodiment of the present invention;
19 is a projection view of FIG. 18,
20 is a view showing unit cells of a three-dimensional grating truss structure according to the first and second embodiments of the present invention;
21 is a view showing a three-dimensional grating truss structure according to a third embodiment of the present invention;
22 illustrates a three-dimensional grating truss structure according to a fourth embodiment of the present invention;
23 is a view showing a three-dimensional grating truss structure according to a fifth embodiment of the present invention;
24 illustrates a three-dimensional grating truss structure according to a sixth embodiment of the present invention;
25 illustrates a three-dimensional grating truss structure according to a seventh embodiment of the present invention;
26 to 28 illustrate a method of manufacturing a three-dimensional grating truss structure according to a preferred embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

First, the three-dimensional lattice truss structure according to the present invention is connected to each other (intersected) to form a two-dimensional truss network and a plurality of wire groups arranged in a multi-stage, and separate (connected) perpendicular to each of the plurality of wire groups The basic configuration of the wire group, the shape of the two-dimensional truss network or the shape or connection (intersection) position of the wire group is characterized as a configuration of the bar with reference to the various embodiments of the present invention below Explain.

First Embodiment

FIG. 16 is a view showing a three-dimensional grating truss structure according to the first embodiment of the present invention, and FIG. 17 is a projection view of FIG.

As shown in FIG. 16, the three-dimensional grating truss structure 100 according to the first embodiment of the present invention includes a first wire 110, a second wire 120, and a first wire connected to each other with an azimuth angle of 90 degrees. It consists of three wires 130. In this case, the third wire 130 is formed at an intermediate point between the connection point L of the first wire 110 and the second wire 120 and an adjacent connection point L '.

In the case of the three-dimensional grating truss structure 100, as can be clearly seen in the enlarged view of FIG. 16, the truss elements in two directions meet at right angles at all points to which truss elements are connected, The shapes projected from three coordinate axes perpendicular to each other are the same.

Second Example

18 is a view showing a three-dimensional grating truss structure according to a second embodiment of the present invention, Figure 19 is a projection of FIG.

As shown in FIG. 18, the three-dimensional grating truss structure 200 according to the second embodiment of the present invention has a structure similar to that of the first embodiment, but includes a first wire 210 and a second wire. 220 and the third wire 230 is made of a spiral configuration is characterized in that cross each other.

In the case of the three-dimensional grating truss structure 200, as shown in the enlarged view of FIG. 18, spiral wires in two directions perpendicular to each other cross each other at all positions corresponding to the intersection points of the truss elements of the first embodiment. In addition, as shown in FIG. 19, the shape projected from the three coordinate axes is also the same.

20 is a view showing unit cells of a three-dimensional grating truss structure according to the first and second embodiments of the present invention.

As shown in FIG. 20, it can be seen that the unit cells U1 and U2 of the above-described three-dimensional grating truss structures 100 and 200 are intact. The shape of the unit cell is not limited to this embodiment, but the same applies to other embodiments described later.

Third Example

21 illustrates a three-dimensional grating truss structure according to the third embodiment of the present invention.

As shown in FIG. 21, the three-dimensional grating truss structure 300 according to the third embodiment of the present invention is a modification of the above-described second embodiment, and the first wire 310 and the second wire 320 are The third wire 330 is straight and helical.

Fourth Example

22 illustrates a three-dimensional grating truss structure according to the fourth embodiment of the present invention.

As shown in FIG. 22, the three-dimensional grating truss structure 400 according to the fourth embodiment of the present invention is a modification of the above-described first or second embodiment and includes a first wire 410 in three directions. The pitch and diameter of the second wire 420 and the third wire 430 are different from each other.

Fifth Embodiment

FIG. 23 illustrates a three-dimensional grating truss structure according to the fifth embodiment of the present invention. FIG.

As shown in FIG. 23, the three-dimensional grating truss structure 500 according to the fifth embodiment of the present invention is a modification of the above-described third embodiment, in which the third wire 530 is connected to the first wire 510. The configuration is characterized in that the intersection of the intersection (I) (I '), not the intermediate point between the intersection (I) and the intersection (I') of the second wire (520).

Sixth embodiment

24 illustrates a three-dimensional grating truss structure according to the sixth embodiment of the present invention.

As shown in FIG. 24, the three-dimensional lattice truss structure 600 according to the sixth embodiment of the present invention is connected to form an azimuth angle of 60 degrees or 120 degrees to form a two-dimensional Kagome truss-shaped network. 1 wire 610, the second wire 620 and the third wire 630, and the fourth wire 640 of the spiral perpendicular to each of the wires (610, 620, 630). The fourth wire 640 intersects the intersection point I (I ') of the respective wires 610, 620 and 630 or an intermediate point between the intersection point I and the intersection point I'. It is a general configuration. In this case, the first wire 610, the second wire 620, and the third wire 630 may be helically formed as shown in the lower part of FIG. 24.

7th Example

25 illustrates a three-dimensional grating truss structure according to the seventh embodiment of the present invention.

As shown in FIG. 25, the three-dimensional grating truss structure 700 according to the seventh embodiment of the present invention includes a first wire 710 and a second wire 720 connected to each other to form a plurality of triangular holes. And a third wire 730 and a spiral fourth wire 740 perpendicular to the wires 710, 720, and 730. In this case, the fourth wire 740 may intersect at the intersection point I (I ') of the wires 710, 720 and 730 or an intermediate point between the intersection point I and the intersection point I'. Can be. In this case, the shape of the first wire 710, the second wire 720 and the third wire 730 is not limited to a straight shape, it is formed in a spiral as shown in the lower portion of FIG. It is also possible.

On the other hand, the shape of the two-dimensional truss network in the present invention is not limited to the form of the sixth embodiment and the seventh embodiment described above, it should be understood that it can be modified to other truss form or various known forms.

The three-dimensional grating truss structure and various embodiments of the present invention have been described above with reference to the drawings. Hereinafter, a method of manufacturing a three-dimensional grating truss structure according to a preferred embodiment of the present invention will be described with reference to the drawings.

26 to 28 illustrate a method of manufacturing a three-dimensional grating truss structure according to a preferred embodiment of the present invention.

First, as shown in FIG. 26, the spirally processed first wire group 10 is arranged at a predetermined interval in parallel in one axis (first axis) direction. In this case, the bent shape of each wire constituting the first wire group 10 is opposite to the adjacent wires.

Subsequently, the second wire group 20 is rotationally inserted in the direction of another axis (second axis) having an azimuth angle of 90 degrees with the first axis. After repeating this process, a plurality of two-dimensional truss nets are fabricated and arranged at regular intervals in a direction perpendicular to the first and second axes (third axis) as shown in FIG. 27. In this case, the two-dimensional truss net is parallel to the upper and lower adjacent two-dimensional truss net in the first axis and the second axis direction by half pitch, respectively.

Finally, as shown in Fig. 28, the spiral third wire 30 is inserted into the spiral in the third axial direction. In this case, the exact position at which the third wire 30 is inserted is an intermediate point between the intersection of the first wire 10 and the second wire 20.

The three-dimensional grating truss structure assembled through the above process can maintain its own shape without a separate support, but when it is desired to increase the strength, the intersection point of the wire includes resin bonding, welding, soldering, or binding by a thin wire. It is also possible to fasten and fix by various joining means.

Preferred embodiments of the present invention have been described in detail above with reference to the drawings. The description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention.

Therefore, the scope of the present invention is represented by the following claims rather than the detailed description, and all changes or modifications derived from the meaning, scope, and equivalent concepts of the claims are included in the scope of the present invention. Should be interpreted as

10: first wire 20: second wire
30: third wire 100: three-dimensional grating truss structure
110: first wire 120: second wire
130: third wire 200: three-dimensional grating truss structure
210: first wire 220: second wire
230: third wire 300: three-dimensional grating truss structure
310: first wire 320: second wire
330 third wire 400 three-dimensional grating truss structure
410: first wire 420: second wire
430: third wire 500: three-dimensional grating truss structure
510: first wire 520: second wire
530: third wire 600: three-dimensional grating truss structure
610: first wire 620: second wire
630: third wire 640: fourth wire
700: three-dimensional grating truss structure 710: first wire
720: second wire 730: third wire
740: 4th wire L, L ': connection point
I, I ': intersection point U1, U2: unit cell

Claims (9)

In the three-dimensional grating truss structure composed of a continuous wire group,
A plurality of wire groups connected (or crossing) with each other to form a two-dimensional truss network and arranged in multiple stages; And
A separate wire connected (or crossing) in a direction perpendicular to the two-dimensional truss network at an intermediate point between a connection point (or intersection point) of the plurality of wire groups and a connection point (or intersection point) adjacent to the connection point (or intersection point). Three-dimensional grating truss structure, characterized in that it comprises a group. The method of claim 1,
At least one wire group of the plurality of wire groups or the separate wire group is a three-dimensional grating truss structure, characterized in that composed of a spiral wire. The method of claim 1,
3D grating truss structure, characterized in that the pitch or diameter of the plurality of wire groups and the separate wire group is different. The method of claim 1,
The intersection of the plurality of wire groups and the separate wire group is fixed by any one of the joining means including resin bonding, welding, soldering, brazing or strapping by thin wires. In the three-dimensional grating truss structure composed of a continuous wire group,
A plurality of spiral wire groups that are arranged in a multi-stage configuration in a two-dimensional truss network of a net structure by crossing each other with an azimuth angle of 90 degrees in space; And
A separate spiral wire group crossing in a direction perpendicular to the two-dimensional truss network at a half pitch point between an intersection point of the plurality of wire groups and an adjacent intersection point; the spiral wires in two directions perpendicular to each other at all intersection points; A three-dimensional grating truss structure, characterized in that the group is configured to intersect. In the method of manufacturing a three-dimensional grating truss structure,
(a) arranging the first group of wires in parallel at regular intervals;
(b) forming a two-dimensional truss network by rotationally inserting the second wire group into the first wire group, the second wire group having an azimuth angle of 90 degrees with the first wire group;
(c) repeating steps (a) and (b) to form a plurality of two-dimensional truss networks;
(d) arranging a plurality of two-dimensional truss networks provided in the step (c) at regular intervals; And
(e) rotating inserting a third wire group in a direction perpendicular to the two-dimensional truss net at an intermediate point between an intersection point of the first wire group and the second wire group and an intersection point adjacent to the intersection point;
Method for producing a three-dimensional grating truss structure, characterized in that it comprises a. The method according to claim 6,
The at least one wire group selected from the first wire group, the second wire group or the third wire group is composed of a spiral wire. The method according to claim 6,
The step (d) further comprises the step of regularly parallelly moving the two-dimensional truss network in the plane by an interval less than the pitch of the two-dimensional truss network. The method according to claim 6,
The manufacturing method of the three-dimensional grating truss structure,
Manufacturing the three-dimensional grating truss structure further comprising the step of fixing the intersection points of the respective wire groups after the step (e) using any one of the joining means including resin bonding, welding, soldering and brazing. Way.

Images