KR20050079395A - Advanced processing technology of grating in composite materials - Google Patents

Abstract

The present invention relates to a composite lattice molding method using pultrusion molding and Resin Transfer Molding (RTM) manufacturing methods and automatically weaving fibers. Composite lattice forming method according to the present invention, the first step of continuously inserting the composite hollow tube (G) into the grid groove 120 of the lower mold (100); A second step of automatically weaving the reinforcing fibers between the composite hollow tubes G; A third step of fastening the lower mold 100 passed through the second step with the upper mold 200 and injecting resin; After hardening the resin passed through the third step is configured to include a fourth step of cutting the composite hollow tube (G) by demolding the upper mold (200). And, in the second step, the pre-programmed weaving machine is configured to automatically weaving the reinforcing fibers, and when injecting the resin of the third step, injecting the resin by tilting the entire mold. Composite hollow tube (G) is characterized in that the hollow composite tube drawn out through the pull (Pultrusion) molding. According to the present invention as described above, there are significant advantages not only in technical aspects but also in economic aspects.

Description

Advanced processing technology of Grating in Composite materials}

The present invention relates to a composite molding method, and more particularly, to a composite lattice molding method using pultrusion molding and Resin Transfer Molding (RTM) manufacturing method and automatically weaving fibers. .

Fiber-reinforced composites are high-tech new materials that are rapidly being applied to the aerospace, aerospace, automotive, defense, and general industries, and must be the key materials to lead the high value-added industry in terms of materials engineering. In recent years, the application range of the reinforcing fiber and the base resin is improved, the development of new molding method, and the price of raw materials are being gradually expanded.

In addition, the grating structure by the molding technology of the composite material is mainly used for structures that are vertically loaded toward the ground, such as large structures for construction and civil engineering, air conditioning towers and ship flooring. Silver has a high specific strength and high strength composite material is preferred to have a high strength, high rigidity, and high physical properties.

Therefore, by developing a molding technology that can improve the productivity of high-precision, high-quality composite molded products, or by using a complementary to the conventional molding method to solve the productivity problem, which is the biggest challenge in the composite molding technology I'm trying to do that.

In addition, the conventional composite grating manufacturing method relies on hand labor to arrange reinforcing fibers impregnated with resin by hand, relying on manpower for production efficiency, manufacturing time, and high defect rate. A problem has occurred. Therefore, it is necessary to increase efficiency through the introduction and automation of a new molding method for the composite grating.

An object of the present invention for solving the above problems, the conventional low-efficient hand lay-up (Hand Lay-up) manufacturing method to replace the composite material (Pultrusion) molding and resin filling molding (RTM) manufacturing method, fiber It is to provide a composite grating molding method for automatically weaving (Weaving).

Composite grating molding method according to the present invention for achieving the above object comprises the first step of continuously inserting the composite hollow tube into the lattice groove of the lower mold; A second step of automatically weaving the reinforcing fibers between the composite hollow tubes; A third step of fastening the lower mold having passed through the second step with the upper mold and injecting a resin; It characterized in that it comprises a fourth step of cutting the composite hollow tube by demolding the upper mold after curing the resin passed through the third step.

The second step is characterized in that the pre-programmed weaving machine is configured to automatically weaving the reinforcing fibers.

The upper mold is formed with a resin inlet through which resin is injected into the lower end of one side, and a resin outlet through which excess resin is discharged to the outside of the other side of the upper end.

In addition, when the resin is injected in the third step, the entire mold is inclined to inject the resin.

And, the composite hollow tube is characterized in that the hollow composite tube drawn out through the pull (Pultrusion) molding.

On the other hand, the first step of automatically weaving (reinforcing) the reinforcing fibers in the lower mold having a grid-like protrusion, and the second step of fastening the lower mold passed through the first step with the upper mold and injecting resin; And a third step of removing the composite grating molded article by demolding the upper mold after curing the resin that has passed through the second step.

According to the composite grating molding method according to the present invention having such a configuration, there is a significant advantage in terms of economic as well as technical aspects.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention as described above will be described in detail.

1 is a perspective view of a lower mold and an insertion portion for inserting a pull-molded composite hollow tube according to the present invention in a perspective view, Figure 2 is a bottom mold of a pull-molded composite hollow tube according to the present invention A perspective view is shown showing the insertion in the. And, Figure 3 is a perspective view showing a state that the reinforcing fibers are reciprocating and automatically weaving (weaving) between the grid of the composite hollow tube inserted into the lower mold according to the present invention, Figure 4 is a reinforcing fiber according to the present invention After weaving (Weaving) is shown a perspective view showing the state of injecting the resin through the resin inlet by fastening the upper and lower molds.

In addition, Figure 5 is a perspective view of the finished product of the composite lattice product is completed by demolding the upper and lower molds after curing the resin according to the present invention by cutting the upper and lower molds to the required thickness in the thickness direction, Figure 6 is another embodiment according to the present invention According to an embodiment, there is shown a perspective view of the automatic weaving while reciprocating the reinforcing fibers between each lattice in the lower mold having a protruding portion in a lattice shape, and FIG. 7 shows a finished product produced by the lower mold of FIG. 6. A perspective view of is shown.

First of all, the technical fields used in the composite grating molding process are largely represented by the pull molding and the resin transfer molding (RTM), and the automatic fiber feeding for the fiber automation weaving. (Feeding) and tensile force control fields.

Pultrusion molding can produce products with constant cross-section in the longitudinal direction infinitely, which facilitates mass production. Focusing on the advantages of pultrusion, continuous production of composite tubes with rectangular hollow cross-sections is achieved by cutting longitudinally by the desired grating thickness and inserting them under the mold to obtain the same grating shape. .

The reason for using the pultrusion molding composite tube as described above is to facilitate the demoulding of the mold and the finished product after curing the resin, and to produce a plurality of composite grating products in one molding. In addition, the production of composite pultrusion tubes requires technical areas such as supply and arrangement of reinforcing fibers, resin impregnation, preforming, curing, and pulling, and theoretical analysis for optimal design.

In addition, pultrusion molding is a method of producing a product having a continuous shape by passing long fibers through a resin bath, impregnating resin, and then passing it through a heated die. This is a highly productive manufacturing method.

In the pultrusion molding process, resins are mainly thermosetting resins such as polyester, vinyl ester, and epoxy, and these thermosetting resins require heat in order for polymerization to occur. Before the reaction occurs, the monomer is in a monomer state, so the viscosity is low, and thus workability is good.

In order to minimize internal defects in the extrusion and to produce products with accurate and uniform fiber direction and excellent quality, the desired hardening is considered in consideration of variables such as the pulling force and speed of the die. It is necessary to select die temperature and pulling speed in consideration of reactivity.

In addition, the resin filling molding (RTM) can produce a complex three-dimensional structure having the anisotropic properties of the fiber-reinforced composite, and has the reliability and reproducible of the product is suitable for forming a composite grating. In addition, the mass grating composite shape can be manufactured at a low production cost, it is possible to implement a high-precision product. The technical field for the optimal molding of the resin filling molding (RTM) requires the calculation of the volume ratio of fibers and resins, resin flow analysis, mold design and manufacturing technology.

Resin filling molding (RTM) is a reinforcing fiber preform in a mold of a desired shape, resin is injected into the mold through an inlet, and then heated and molded. Resin filling molding (RTM) is molded by 20 ~ 50 psi, which is relatively lower than other resin injection molding, so the initial investment of equipment and equipment such as mold manufacturing and injection machine is inexpensive. have. In addition, both inside and outside surfaces of the finished parts are good, gel coating is possible, and the amount and direction of the internal reinforcement can be easily controlled, and the installation for insertion with other parts is easy.

In addition, the resin filling molding (RTM) has to take into account the flow characteristics of the resin and the wettability of the internal reinforcing material from the design process of the mold, and thus, the FEM analysis for the resin flow analysis and the permeability of the reinforcing material used. It is accompanied by research, and since various variables in the molding process, the incidence of voids and the strength of the product vary greatly, so a systematic study is required.

Reinforcing materials used in resin filling molding (RTM) include continuous fiber mats and chopped fiber mats, which can be used to fit the shape of molds in order to shorten the lamination time and maintain complex reinforcement directions of complex shapes. Sometimes preforms are used to cut and mold.

In general, the preform is put into the binder (binder) during the manufacture to maintain its shape. For the selection of stiffeners, the bulk factor, deformation by resin flow, and resin impregnation should be considered. After the reinforcement lamination is finished, the mold is closed and clamped, using a press or a C-clamp.

The resin used in the resin filling molding (RTM) can increase the resin injection speed only when the viscosity is low, and the curing time can be shortened only when a fast curing reaction occurs after the gel time. In general, it can be said that resins that are tough and have no crack shape are suitable for resin filling molding (RTM). Chemical resistance, mechanical properties, fire resistance, electrical properties, and environmental resistance may be selected as the selection criteria for resin filling molding (RTM) resins. For example, even when high strength and moderate chemical resistance are required, isophthalic polyester ) And when high corrosion resistance is added, vinyl ester resin is selected.

Additives of the resin used in the resin filling molding (RTM) include a mixing release agent, a filler such as clay or calcium carbonate, a pigment for color, and the like. The required strength, surface accuracy, and required viscosity of the part are included. (Viscosity), impregnation, price, etc. should be taken into consideration and selected, and in order to be optimal for molding operation with resin filled molding (RTM) resin, the viscosity due to resin temperature, curing agent ratio, and filler amount ( Viscosity) should be considered.

In addition, the resin is cured when heat is applied after the resin is filled, and it is easy to pull out of the mold only after curing by releasing the gel until the gel, and the shape of the part can be properly maintained. Gel time is dependent on molding temperature, resin used, curing agent ratio, accelerator amount and other additives, typically 5 to 45 minutes. In addition, ejection pins may be used in mass production during release operations.

Meanwhile, an automatic feeding device and a tension control device are required for automatic weaving of a fiber reinforced between a pultrusion molding composite tube or a mold grating protrusion. Since the conventional water-based lamination was the main cause of the decrease in production rate, it is essential to design and manufacture an automated fiber weaving and a tension control device to prevent the sagging of the fiber between the grids.

To feed fibers automatically requires three-axis control motor design and computational programming to control the position, travel, and tension of fiber feeding. That is, the load, torque, and moment for friction and external load are calculated and the optimized motor is installed. In addition, computerized programming is entered so that motors designed and mounted for automated weaving can be precisely controlled in the X, Y, and Z axes. In addition, it calculates the power and load required for the automatic opening and closing of the mold and demolding, and selects and mounts a power source such as a motor and a hydraulic cylinder.

Next, the process of the composite lattice forming method with reference to the drawings according to the present invention.

The lower hollow mold, which has a substantially rectangular cross section (which may vary depending on the shape of the grid to be designed), is formed by a pultrusion molding method, and then cut to a predetermined height to cut the grating groove 120 in advance. Insert in (100). Then, weaving the reinforcing fibers reciprocating in each direction between the inserted composite hollow tube (G). At this time, an automatic fiber weaving machine (not shown) automatically weaves the reinforcing fiber, which operates automatically by preprogramming the shape of the grid and the distance between the grids.

When the weaving of the reinforcing fiber is finished, the upper mold 200 is fastened to the lower mold 100 and resin filling molding (RTM) is performed. One side lower end of the upper mold 200 has a resin inlet 140 for injecting resin during resin filling molding (RTM), and a resin outlet (not shown) at the upper end of the other side. Therefore, when the resin is injected, the entire mold to which the upper and lower molds 100 and 200 are fastened is inclined at a predetermined angle, for example, 30 degrees, and injected into the resin injection hole 140 at a relatively low position.

When the resin is injected into the resin inlet 140 at a relatively low position, the resin is gradually filled in the mold cavity and filled with the resin, and the surplus resin is discharged through the resin outlet formed at the relatively high position. . When the surplus resin is discharged to the resin outlet, it means that the filling of the resin in the mold is completed. The resin injection is stopped and the mold is heated to cure the resin for a predetermined time.

Then, after curing is completed, the upper and lower molds 100 and 200 are demolded to cut the composite lattice to the required lattice thickness to produce the finished product 160.

Meanwhile, a method of producing the composite grating with the lower mold as shown in FIG. 6 will also be possible. That is, the lower mold 300 having the lattice protrusions 320 protruding at regular intervals in a substantially rectangular lattice shape is produced, and the automatic fiber weaving machine reinforces the fiber according to the computationally programmed path between the lattice protrusions. Automatic Weaving

Then, the upper mold 200 is fastened and the mold is inclined by injecting resin from the bottom by injecting the resin in a resin filling molding (RTM) method. Then, the resin is cured and demolded to obtain a composite lattice finished product 340.

The scope of the present invention is not limited to the above-exemplified embodiments, and many other modifications based on the present invention may be made by those skilled in the art within the above technical scope.

According to the present invention as described above, to replace the conventional composite lattice products produced by the hand-lay (Hand Lay-up) with the new molding method Pultrusion molding and resin filling molding (RTM) manufacturing method, the reinforcing fiber is automatically Weaving was changed to the manufacturing method.

Therefore, the technical aspect is expected to improve productivity, such as increased production efficiency, shorter manufacturing time, and lower defective rate, compared to the conventional hand lay-up. Is expected.

1 is a perspective view showing the lower mold and the insertion portion for inserting the pull-molded composite hollow tube according to the present invention.

Figure 2 is a perspective view showing a state of inserting the pull-molded composite hollow tube according to the present invention into the lower mold.

Figure 3 is a perspective view showing a state in which the reinforcing fibers are reciprocating and automatically weaving between each lattice of the composite hollow tube inserted into the lower mold according to the present invention.

Figure 4 is a perspective view showing a state in which the upper and lower molds are fastened after weaving the reinforcing fiber weaving according to the present invention to inject the resin through the resin inlet.

Figure 5 is a perspective view of the finished composite grating cut to the thickness required for the thickness direction by demolding after curing the resin according to the present invention.

Figure 6 is a perspective view showing the appearance of the automatic weaving (reciprocating) the reinforcing fibers between each lattice in the lower mold with a protruding portion in the grid form according to the present invention.

7 is a perspective view of the finished product produced by the lower mold of FIG.

Explanation of symbols on the main parts of the drawings

100, 300. ..... Lower mold 120. ..... Grid groove

140. ..... Resin inlet 160, 340. ..... Finished product

200. ..... Upper mold 320. ..... lattice projection

G. ..... Composite Hollow Tube

Claims (6)

A first step of continuously inserting the composite hollow tube into the lattice groove of the lower mold; A second step of automatically weaving the reinforcing fibers between the composite hollow tubes; A third step of fastening the lower mold having passed through the second step with the upper mold and injecting a resin; And a fourth step of cutting the composite hollow tube by demolding the upper mold after curing the resin passed through the third step. The method of claim 1, wherein the second step, Composite lattice forming method characterized in that the pre-programmed weaving machine is configured to automatically weaving the reinforcing fibers. The method of claim 1, wherein the upper mold, And a resin inlet through which resin is injected into a lower end of one side, and a resin outlet through which excess resin is discharged to the outside of an upper end of the other side. The method of claim 1, wherein the resin is injected by tilting the entire mold when the resin is injected in the third step. The method of claim 1, wherein the composite hollow tube is a composite lattice forming method, characterized in that the hollow composite tube drawn by pultrusion molding. A first step of automatically weaving the reinforcing fibers in a lower mold having a shape protruding into a lattice shape, A second step of fastening the lower mold that has passed through the first step with the upper mold and injecting resin; And a third step of removing the composite grating molded article by demolding the upper mold after curing the resin that has passed through the second step.