KR20050120175A - A method of construction of three dimensional cellular light materials and the continuous manufacture - Google Patents

Abstract

The present invention relates to a method for producing a porous lightweight structural material having a three-dimensional truss structure using a wire. Wires in six directions having a 60-degree or 120-degree angle to each other in three-dimensional space are stacked to cross each other without bending to form a truss. After lamination, the intersection point of the wire may be joined by welding, brazing, soldering, resin bonding, etc., if necessary, to produce a structural material having high strength and rigidity in light weight. The three-dimensional fiber-reinforced composite material can be manufactured by filling the empty space inside with a solid such as a porous material, a resin, or a metal.

Description

A method of construction of three dimensional cellular light materials and the continuous manufacture

The present invention relates to a method for producing a porous, lightweight, high structural strength and rigidity. In many fields of engineering efforts to provide effective structures such as the present invention have continued. Examples thereof include metal foams. It is used to generate air bubbles inside the metal in the liquid or semi-solid state, or to cast with open foamed resin such as sponge as a mold, but it is not widely used due to inferior mechanical properties such as strength and stiffness compared to the price. .

As a substitute material for the foamed metal, there is an open lightweight structural member having a periodic truss structure. The mechanical properties are excellent because the truss structure is designed to have the best strength and stiffness through precise calculation. The simplest and most effective three-dimensional truss is a combination of six elements in the shape of a tetrahedron. The truss can be combined into unit cells to form large structures. As the truss structure, an octet truss having a combination of a tetrahedron and an octahedron is most common. 1 shows the shape of a single layer octet truss together with a unit cell.

 As a method for producing a porous lightweight structural material having a truss structure, several methods are known. (Reference: HHG Wadley et al., "Fabrication and structural performance of periodic cellular metal sandwich structure", Composite Science Technology, Vol. 63, pp.2331-2343, 2003) It is a method of manufacturing by casting. Second, it is a method of attaching a face plate to the top and bottom after forming a truss intermediate layer by forming a net form by periodically drilling holes in a thin plate. In the case of a multi-layered structure of two or more layers, a method of attaching a face plate on top of a truss intermediate layer made by bending over the top face plate is used. Third, weaving wire mesh in the form of two vertical wires and laminating and joining them. 2 shows a third method. This method is known to minimize manufacturing costs, but it is not an ideal structure such as octets and kagome trusses mentioned above because it is simply combined with two wires as weaving, and it is disadvantageous in terms of cost and strength because there are too many parts to be joined. Do.

Korean Patent Application No. 10-2003-0078507 has proposed a method for constructing a truss structure similar to an octet truss by three-dimensional weaving wires in six directions. 3 shows the form. Since it is easy to obtain high-strength materials in the form of wire, such as piano wire or fiber reinforced composite material, it is promising as a method of manufacturing a three-dimensional truss lightweight structural material having high strength. However, since 6-axis three-dimensional looms are not yet developed for the production of this structure, mass production is difficult to realize. It is also disadvantageous in terms of strength rather than ideal straight truss elements because each wire is bent as weave.

U.S. Patent No. 5076330 (December 31, 1991) proposed a method of making a three-dimensional composite material by intersecting and stacking four directions of fiber-reinforced resin sticks having a constant angle to each other in space. This method is advantageous in terms of strength because the bars are simply stacked in a certain order without bending, and the production apparatus is relatively simple. However, this method is intended to produce three-dimensional fiber-reinforced composites with no voids inside and cannot be used to produce porous lightweight structural materials. In addition, each component of the product does not have the same ideal structure as an octet truss, so it does not have the strength and stiffness as much as an octet truss.

In general, fiber-reinforced composite materials are manufactured in the form of thin two-dimensional plates (lamina), and when thick materials are required, they are laminated and used. However, in this case, the separation between the layers occurs and the strength is reduced, so we use the method of weaving the fibers in three dimensions from the beginning and later compounding with a matrix such as resin and metal. 4 shows a three-dimensional woven fiber. Instead of fibers, a porous, lightweight structural member can be made through three-dimensional weaving using materials with high stiffness, such as metal wires. However, since it is not the ideal truss structure mentioned above, the mechanical strength is low and the physical properties vary depending on the direction. In addition, the mechanical properties of the composite material made of three-dimensional woven fiber is bad for the same reason.

The ideal lightweight structural material has a high strength and stiffness (non-strength and non-stiffness) per unit weight, a simple device for manufacturing it, and low production cost due to no loss of raw materials. The present invention is a method for manufacturing such a lightweight structural member to form a three-dimensional truss by stacking the wires in a predetermined order in three directions on a plane, six directions in space to form a three-dimensional truss to complete the porous lightweight structural member by joining each intersection.

This allows mass production of structural materials close to ideal octet trusses at low cost. It is also possible to create quasi-isotropic three-dimensional fiber-reinforced composites, which are filled with resins or metals, with a much higher strength than conventional products and almost constant physical properties regardless of the direction.

The present invention relates to a method of manufacturing a multilayer (bulk) octet truss. 5 is a stereogram of an ideal multilayer octet truss. To illustrate the exact shape, the Cartesian coordinate axes are also shown. The z axis is parallel to the diagonal truss element ending back and forth the hatched lozenge on the bottom plane. The x-axis is parallel to the diagonal a-a 'traversing its marmot. The y axis is perpendicular to the x-z plane. 6, 7 and 8 are projection views of the object of FIG. 5 as viewed from the z-axis, the x-axis, and the y-axis, respectively. Fig. 9 shows a tetrahedron constituting an octet truss.

The present invention suggests that a quasi octet truss similar to the above can be produced by simply repeating lamination without bending the wire. Detailed description of the lamination process is as follows. FIG. 10 illustrates a plate corresponding to the x-z plane of FIG. 5. The plates consist of three groups of wires (parallel wires) that cross each other at 60 or 120 degrees, indicated by (10), (20) and (30) in the figure, respectively. Fig. 11 shows four such plates stacked in parallel, and is written in order of plate A, plate B, and plate C from the top layer. 12 is viewed from the y-axis. Compared with FIG. 10, the plates A, B, and C are all composed of the wire groups of (10), (20), and (30), but the wires forming the plates are the same. It can be seen that plate A is repeated after plates A, B, and C by being moved in parallel by 1/3 of the length of each side of the triangle. FIG. 13 is a shape in which the (40) wire group, which is the fourth direction penetrating through the plates A, B, and C, is additionally inserted in FIG. 11. The wire groups (10), (20) and (30) in each plate are arranged in the triangular direction of the base of the tetrahedron, whereas the (40) wire group is one of the three inclined sides of the tetrahedron forming 54.7 degrees with the plate. FIG. 14 is a view of FIG. 12 from the x-axis. In the same manner, when the (50) and (60) wire groups are inserted in the remaining two inclined sides, the quasi-octet truss as shown in FIG. 15 is formed. 16, 17, and 18 are projection views of the quasi-octet truss of FIG. 15 as viewed from the x-axis, z-axis, and y-axis, respectively. Fig. 19 shows a quasi- tetrahedron forming a quasi-octate truss. Even if the order of input of the wire groups 40, 50, and 60 is changed, a quasi-octet truss similar to the above can be configured. In this case, the shape of the intersection portion of the wire is somewhat different. Comparing quasi-octet trusses from FIGS. 15 to 19 with the ideal octet trusses from FIGS. 5 to 9, the overall shape is very similar except for the intersection of the three wires. After lamination, each wire crossing point is completed by fixing in the form of liquid or spray resin bonding, brazing, soldering, welding, etc. As the material of the wire, metal, fiber, synthetic resin, fiber reinforced synthetic resin and the like can be used. Depending on the thickness of the wire and the length of the truss elements, structures from as small as a few tenths of millimeters to several tens of meters can be made.

20 is an example of a mechanical device capable of realizing the above-described manufacturing process in detail to produce a continuously given octet truss in the form of a hexagonal column. Structures that support mechanical devices, power transmission and control devices are omitted. 21 to 23 are projection views of FIG. 20 as viewed from the z-axis, the x-axis, and the y-axis, respectively. The whole production process is largely divided into process 1 and process 2. Process 1 is a process for making plates A, B, and C by inserting the wire groups 10, 20, and 30, and process 2 is a process for inputting the wire groups 40, 50, and 60. to be.

The mechanical devices corresponding to the process 1 are located in the lower part of FIG. 20, the inserter assembly 110 of the wire group 10, the inserter assembly 120 of the wire group 20, and the inserter of the wire group 30. It is composed of the assemblies 130 and are spaced 120 degrees apart from each other. Mechanisms corresponding to the process 2 are located in the upper part of FIG. 20, the inserter assembly 140 of the wire group 40, the inserter assembly 150 of the wire group 50, and the inserter assembly of the wire group 60. It consists of 160, and is arrange | positioned at 120 degree spaces mutually.

24 shows a schematic three-dimensional view of the inserter assembly 110 of the plate holder 100 and the wire group 10 serving as an edge for supporting both ends of the wires belonging to the plates A, B, C. It consists of a device that inserts wires and a device that supplies wires from there to the outside. 25 is a projection view of the device for inserting the wire in more detail in the y axis, and FIG. 26 illustrates a specific example in which a device for cutting and supplying wire is added to the cross-sectional view of FIG. 25. The wire guide 111 and the push rod guide ( 112, wire push rod assembly 113, wire push rod 114, wire reservoir 115, stored wire 116, wire cutting holder 117, wire cutter 118, wire feeder 119, It consists of the wire 0 which is not yet cut | disconnected. First, when the holder 100 of the plate A is supplied from the bottom to make the plate A, the wire guide 111 is approached close to the holder 100 by the push rod guide 112, by the wire push rod 114 The wire group 10 is inserted into the position where the wire group 10 should be located through the hole drilled in the edge of the holder 100. When the push rod 114 is returned to its original position after insertion, the wire stored in the reservoir 115 is positioned in its own position in the guide 111 by its own weight. It's like a bullet loaded from a magazine into a chamber. At the same time, the wire 0, which has not yet been cut, is inserted into the cutting holder 117 by the feeder 119 and then cut into the appropriate length by the cutter 118, and the wire is newly inserted into the cutting holder 117. It is pushed into the storage 115 and stored.

In this manner, the inserter assembly 120 of the wire group 20 and the inserter assembly 130 of the wire group 30 are operated in the stacking order of the wire group to complete the plate A. 27 shows the arrangement of the plate holder 100 and the three wire insertion device. Each wire inserter is spaced a certain distance from the plate holder so as not to interfere with each other. The completed plate A and holder 100 are conveyed upwards (y axis direction) by h and a new holder for plate B is fed from the bottom. The vertical transport distance h of the plate is the height of the tetrahedron forming the truss of FIG. 19, which is 0.943 times the spacing w between parallel wires in the plate. The process of making plate B is the same as in plate A, but as shown in Fig. 12, the position where the wire group is inserted should be moved by one third of the distance w between the wires. The finished plate B and the holder are transferred upwards by h and again a new holder for plate C is fed from the bottom. Similarly, the position at which the wire group of plate C is inserted must again be moved by one third of w. This process is repeated to make the plates A, B, C, A ... in order and transferred sequentially to the top while maintaining the distance h between the plates.

When the height H of the plates manufactured and stacked by the process l becomes 1.141 times or more than the diameter W of the plate, the process 2 of injecting the inclined wire groups 40, 50 and 60 is started. FIG. 28 is a projection view of the inclined wire inserter assembly 140 at the top of FIG. 20 from the y axis and FIG. 29 adds a wire cutting and feeding device to its cross sectional view. First, the wire group 40 is inserted from the wire inserter assembly 140 by the wire push rod 143. The wire group 40 enters through the rim hole of the upper plate holder 100 and slides while leaning obliquely at the wire crossing points in the pre-made plate so that the end thereof is inserted into the opposite rim of the plate holder which is positioned up to H below. When the push rod 143 is returned to its position after the Y group 40 is inserted, the wire stored in the wire storage 144 is lowered by its own weight and positioned in the guide 141. At the same time, the wire 0, which has not yet been cut, is inserted by the feeder 148 into the cutting holder 146 by a suitable length and then cut by the cutter 148, and the wire is newly inserted into the cutting holder 146 again. Is pushed into the reservoir 144 and stored. In this manner, the wire group 50 inserter assembly 150 and the wire group 60 inserter assembly 160 operate according to the stacking order. Then, when the plate A and the holder 100 is moved upward by a height h by the conveying device, the plate B and the holder 100 are raised, and the wire group 40, 50, which is inclined again through the above process 2, 60 is inserted. At the same time, process 1 proceeds under the device.

In this way, each time the new plate and holder 100 is raised from the bottom, the process 1 and 2 are repeated repeatedly. The shape of the plate holder 100 is not limited to the hexagon, but may be changed as necessary, and the order of input of the inclined wire group is not only 40, 50, and 60, but also 50, 40, and 60. It can be changed as needed.

The present invention makes it possible to produce porous lightweight structural materials in a continuous process. Conventional manufacturing methods are disadvantageous in terms of cost because the production process is discontinuous using a method of first forming a part corresponding to each layer and then laminating and bonding or casting one by one. In the method of weaving the wire in three dimensions, the wire is bent and the strength decreases. However, in the present invention, it is possible to continuously produce a three-dimensional truss form through a consistent process by simply stacking the wire without bending it, thereby mass production and low cost To make it possible. It also has a structure similar to that of an ideal octet, which is excellent in strength and stiffness.

Three-dimensional fiber-reinforced composites can be made by filling resin or metal into the voids of the finished three-dimensional truss structure. This composite material is a quasi-isotropic material, and since its physical properties are almost uniform regardless of the direction, it can be cut into any shape such as metal and the like.

1 is a shape of a single layer octet truss and a unit cell

Figure 2 is a shape of the porous structural material prepared by laminating a two-dimensional woven wire mesh

3 is a shape of the porous structural material fabricated by three-dimensional weaving wire

4 is an example of a three-dimensional woven fiber

5 is a stereoscopic view of an ideal octet truss

FIG. 6 is a perspective view of FIG. 5 as viewed from the z axis. FIG.

FIG. 7 is a projection view of FIG. 5 from the x-axis

8 is a projection of FIG. 5 as viewed from the y axis

9 is a tetrahedron constituting the ideal octet of FIG.

10 is a shape in which a plate formed by stacking wire groups 10, 20, and 30 in three directions crossing each other at 60 degrees or 120 degrees is placed on a z-x plane.

FIG. 11 is a view in which four plates similar to those of FIG. 10 are stacked in a y-axis direction at regular intervals.

12 is a projection of FIG. 11 as viewed from the y axis.

FIG. 13 is a view in which a wire group 40 penetrating the plates is added to FIG. 11.

FIG. 14 is a projection view of FIG. 13 as viewed from the z axis. FIG.

FIG. 15 is a quasi-octet truss shape formed by stacking wire groups 10 to 60 in six directions crossing each other at 60 degrees or 120 degrees.

FIG. 16 is a perspective view of FIG. 15 as seen from the z axis

FIG. 17 is a projection view from the x-axis of FIG. 15

FIG. 18 is a projection view from the y axis of FIG. 15

19 is a shape of a quasi- tetrahedron constituting the quasi-octet truss of FIG.

20 is an isometric view of a mechanism for making a quasi-octet truss.

FIG. 21 is a perspective view of FIG. 20 as viewed from z-axis

FIG. 22 is a projection view of FIG. 20 from an x-axis

FIG. 23 is a projection view of FIG. 20 from the y axis

24 is a three-dimensional view showing a portion of the plate holder 100 and the wire inserter assembly 110 supporting both ends of the wires belonging to the plates A, B, C.

FIG. 25 is a projection view of the wire insertion device of FIG. 24 as seen from the y axis.

FIG. 26 is a view illustrating a wire cutting and feeding device added to the cross-sectional view taken along line F-F 'of FIG.

FIG. 27 is a projection view of the plate holder 100 and the layout of the three wire inserter assemblies 110, 120, and 130 viewed from the y-axis.

FIG. 28 is a projection view of the inserter assembly 140 of the wire group 40 of FIG. 20 seen from the y axis.

FIG. 29 is a view illustrating a wire cutting and feeding device added to the line G-G 'of FIG. 28;

Claims (4)

Method for producing a structure and its apparatus according to the terms and conditions of the present invention in manufacturing a three-dimensional truss and a light weight structural member using six directions of wire The method of claim 1 wherein the mechanism is constructed such that the cross section of the completed truss column is hexagonal. The method of claim 1, wherein the intersection of the wires is bonded to the finished truss structure by a liquid, spray-type adhesive, brazing, soldering, or the like, to fabricate the fixed structure. The method of manufacturing a three-dimensional fiber-reinforced composite material according to claim 3, wherein the hollow space of the truss structure is made to penetrate resin or metal after making the structure.