CN115256924B - A 3D printing method for fiber composite materials with controllable fiber distribution - Google Patents

Abstract

The present invention relates to a 3D printing method for fiber composite materials with controllable fiber distribution. The method comprises: arranging a splitting filament in a through-hole nozzle, the splitting filament is located in a vertical outlet section or a contraction outlet section, and the two ends are respectively arranged on the inner wall surface of the nozzle outlet or the contraction inner wall surface to obtain a splitting nozzle; adjusting the position of the splitting nozzle so that at the zero time of printing, the splitting filament forms a certain angle with the horizontal or vertical direction of the printing plane; feeding resin material and fiber bundles into the splitting nozzle, and introducing the fiber bundles into different partitions respectively, and the resin filaments are fed through gears to perform 3D printing. The method designs the distribution of fiber bundles in the deposited filament by controlling the number and type of fiber bundles introduced into different zones and the horizontal angle of the splitting filament relative to the printing plane, thereby realizing 3D printing of low-porosity composite materials with controllable fiber distribution.

Description

A 3D printing method for fiber composite materials with controllable fiber distribution

Technical Field

The present invention belongs to the technical field of 3D printing, and in particular relates to a 3D printing method for fiber composite materials with controllable fiber distribution.

Background Art

Continuous fiber reinforced composite materials are a kind of popular composite materials that are lightweight but comparable to traditional metal and alloy materials in strength, stiffness and other properties. Currently, they have achieved many successful applications in the fields of aerospace, automobiles, transportation, industrial equipment, sports, etc. The advantages of fused filament fabrication (FFF) 3D printing technology, such as low cost and personalized manufacturing, have further promoted the application of fiber reinforced composite materials in a wider range of scenarios.

Compared with 3D printing of pre-impregnated continuous fiber reinforced composite materials, 3D printing of in-situ composite impregnation continuous fiber reinforced composite materials eliminates the step of using pre-impregnation equipment to pre-impregnate fiber bundles, and has the huge advantages of low cost and instant control of fiber content. However, the disadvantages of the general single-hole nozzles currently on the market are also obvious: first, the resin in the nozzle is often viscous, and the pressure of the melt on the fiber bundle continues to decrease from the wire inlet to the nozzle outlet. It is difficult for the molten resin to completely impregnate a small volume of fiber bundles. When the fiber content increases, the aggregation between the fibers will be more unfavorable for the resin to impregnate the fiber bundle, resulting in more pores in the composite material, which will significantly reduce the performance of the material; second, when different types of fiber bundles are used for mixed printing to achieve differentiated performance, different types of fiber bundles will be entangled with each other, making it difficult to achieve a controllable design of differentiated material performance.

Summary of the invention

The technical problem to be solved by the present invention is to provide a 3D printing method for fiber composite materials with controllable fiber distribution. The present invention partitions the nozzle outlet by using splitting wires to achieve splitting feeding and splitting deposition of fibers, thereby achieving the purpose of reducing material porosity and controlling the controllable deposition of different bundles of fibers.

The present invention provides a 3D printing method for fiber composite materials with controllable fiber distribution, comprising:

(1) a beam splitting filament is arranged in the through-hole nozzle, the beam splitting filament is located in the vertical outlet section or the contraction outlet section, and the two ends are arranged on the inner wall surface of the nozzle outlet or the contraction inner wall surface, thereby obtaining a beam splitting nozzle;

(2) According to the fiber bundle distribution required by the material and the preset printing path, the position of the beam splitting nozzle in step (1) is adjusted so that at the zero printing time, the beam splitting filaments form a certain angle with the horizontal or vertical direction of the printing plane;

(3) The resin material and the fiber bundle are fed into the beam splitting nozzle in step (2), and the fiber bundles are respectively introduced into different partitions. The resin filaments are fed through gears for 3D printing to obtain fiber-reinforced resin composite filaments.

Preferably, the splitting wire in step (1) is rigid or flexible. When the splitting wire is rigid, the outer end of the splitting wire can be welded to the inner wall surface of the nozzle outlet or the contraction inner wall surface, or be clamped on a smooth concave track etched on the inner wall surface of the nozzle outlet or the contraction inner wall surface. For the latter, when the printing path changes, the splitting wire 7 will automatically adjust its position due to the fiber tension; when the splitting wire is flexible, it can be inserted into the hole on the inner wall surface of the nozzle outlet for fixation.

Preferably, the splitting wire in step (1) is made of metal or non-metal, the metal is steel wire or iron wire, and the non-metal is aramid fiber. The splitting wire needs to have good heat resistance, smooth surface, uniform thickness, and certain strength, and the finer the better.

Preferably, in step (1), there are one or more splitting wires, and the outer ends of the splitting wires can be located on the same or different planes in the vertical direction.

Preferably, the through-hole nozzle in step (1) comprises an external thread, a nozzle outer wall surface, a vertical inner wall surface, a contraction inner wall surface and an outlet inner wall surface; the beam splitting wire is located in the nozzle to divide the nozzle outlet into zones.

Preferably, in step (2), the angle between the splitting wire and the printing plane in the transverse direction is 0°, 30°, 45° or 60°.

Preferably, the fiber bundles in step (3) are low-filament-count continuous fibers of the same or different types and with the same or different filament counts.

Preferably, the resin material in step (3) is polylactic acid, nylon, ABS, polycarbonate or PEEK.

Preferably, the fiber bundle in step (3) comprises one or more of glass fiber, carbon fiber and aramid fiber.

The process principle of fused filament fabrication (FFF) 3D printing technology is: a consumable with a certain diameter (such as 1.75mm or 2.85mm) enters the high-temperature printing nozzle at a certain speed under the action of the wire feeding gear, where it is heated and melted. Under the extrusion force of the continuously entering wire, the molten resin is extruded through a nozzle with a certain aperture (such as specifications of 0.4mm, 0.5mm, 0.8mm, 1.0mm, 1.5mm, etc.), and deposited on a deposition bed at a lower temperature to be cooled and solidified. While extruding the resin, the nozzle moves along a certain path. After each layer of deposition is completed, the nozzle will rise to a layer height to deposit the next layer, and thus a three-dimensional entity is obtained by stacking layers.

Beneficial Effects

In the prior art, in the process of in-situ composite impregnation 3D printing of continuous fiber composite materials using conventional single-hole nozzles, there are problems such as incomplete impregnation of high-volume fiber bundles with resin, and disordered and uncontrollable fiber distribution during the printing of high-filament fiber bundles or mixed fiber bundles. The present invention sets a splitting wire at the nozzle outlet, divides the outlet into zones, and improves the incomplete impregnation of the fiber bundle with resin by feeding the fibers in zones. The distribution of fibers in the deposited wire is designed by controlling the number and type of fiber bundles introduced into different zones and the lateral angle of the splitting wire relative to the printing plane, thereby realizing 3D printing of low-porosity composite materials with controllable fiber deposition. The presence of the splitting wire can increase the contact area between the resin and the fiber bundle, and the fiber bundles are thinner after being split. Within a limited time and travel length, it is easier for the resin to be impregnated into the inside of the fiber bundle, thereby improving the composite situation of the two.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a cross-sectional view of a conventional single-hole nozzle (taking a round-hole nozzle as an example).

FIG. 2 is a cross-sectional view of the beam splitting nozzle of the present invention (based on a round hole nozzle).

FIG3 is a bottom view of the 3D printing nozzle of the present invention (based on a circular hole nozzle, taking a dual-zone nozzle as an example).

FIG. 4 is a bottom view of the 3D printing nozzle of the present invention (based on a circular hole nozzle, taking a three-zone nozzle as an example).

FIG5 is a bottom view of the 3D printing nozzle of the present invention (based on a circular hole nozzle, taking a four-zone nozzle as an example).

FIG6 is a bottom view of the 3D printing nozzle of the present invention (based on a circular hole nozzle, taking a five-zone nozzle as an example).

FIG. 7 is a bottom view of the 3D printing nozzle of the present invention (based on a circular hole nozzle, taking a six-zone nozzle as an example).

In the figure: 1 is the external thread, 2 is the outer wall surface of the nozzle, 3 is the vertical inner wall surface, 4 is the contraction inner wall surface, 5 is the outlet inner wall surface, 6 is the nozzle outlet edge, and 7 is the splitting wire.

DETAILED DESCRIPTION

The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

Example 1

A 3D printing method for fiber composite materials with controllable fiber distribution, comprising:

(1) A thin steel wire beam splitter is arranged in the through-hole nozzle, the beam splitter is located in the vertical outlet section, and both ends are welded to the same height of the inner wall surface of the nozzle outlet, thereby obtaining a beam splitter nozzle;

(2) The printing path is preset to be a concentric printing path for each layer, and the nozzle position is adjusted so that at the zero printing time, the splitting filament is at a 0° angle to the horizontal direction of the printing plane;

(3) Fiber bundle A (200D Kevlar aramid fiber) and fiber bundle B (1K carbon fiber) are introduced into two zones respectively. ABS resin filaments are fed by gears. When the print head moves in the horizontal direction, fiber bundle A and fiber bundle B will be distributed on both sides of the horizontal printing path. When the print head moves in the longitudinal direction, the front and rear positions of the two zones relative to the print head will cause the two bundles of fibers to be stacked. In addition, due to the separation effect of the splitting wire and the penetration effect of the molten resin, the molten resin will be impregnated into the inside of fiber bundle A and fiber bundle B and between the two bundles of fibers, that is, a low-porosity composite material with fiber bundle A and fiber bundle B distributed on both sides in the horizontal direction and stacked in the longitudinal direction is obtained.

The splitting nozzle in step (1) comprises a conventional circular through-hole nozzle, and the inner flow channel comprises a vertical section, a contraction section and an outlet section. The fine steel wire splitting wire has its two ends embedded in the inner wall of the outlet, thereby dividing the nozzle outlet into two areas along the plane symmetry axis of the nozzle outlet end, and the two fiber bundles can be extruded through the two areas respectively.

Example 2

Since the splitting wire is in a high-temperature nozzle, it should have good heat resistance. Since it needs to withstand the tension of the fiber and the pressure of the resin, it needs to have a certain strength. It also needs to have a smooth surface and uniform thickness to minimize damage to the fiber and interference with the extruded resin. Aramid fiber can be used, and the rest is the same as in Example 1 to obtain a composite material.

Example 3

A smooth concave track is etched on the inner wall of the outlet in step (1), and the outer end of the rigid splitting wire is clamped in it, so that when the printing path changes, the splitting wire will automatically rotate to a position parallel to the printing path due to the fiber tension. For the splitting dual-zone nozzle, two bundles of fibers can always be deposited on both sides of the printing path. The rest is the same as Example 1, and a composite material is obtained.

Example 4

There can be two or more splitting filaments (as shown in Figures 3 to 5). In order to minimize the impact on resin extrusion, the outer ends of the splitting filaments with different orientations can be distributed on different planes in the vertical direction, which can also achieve the partitioning effect. The rest is the same as in Example 1 to obtain a composite material.

Claims (9)

1. A fiber composite 3D printing method with controllable fiber distribution, comprising:

(1) The method comprises the steps that a beam splitting wire is arranged in a through hole nozzle, the beam splitting wire is positioned in a vertical outlet section or a shrinkage outlet section, and two ends of the beam splitting wire are respectively arranged on the inner wall surface or the shrinkage inner wall surface of an outlet of the nozzle, so that the beam splitting nozzle is obtained;

(2) According to the fiber bundle distribution required by the material and a preset printing path, the position of the beam splitting nozzle in the step (1) is adjusted, so that the beam splitting wires form a certain angle with the transverse direction or the longitudinal direction of a printing plane at the time of printing zero;

(3) And (3) feeding the resin material and the fiber bundles into the beam splitting nozzle in the step (2), respectively introducing the fiber bundles into different partitions, feeding the resin filaments through a gear, and performing 3D printing to obtain the composite filaments of the fiber reinforced resin.

2. The method according to claim 1, wherein the split filaments in the step (1) are rigid or flexible, and when the split filaments are rigid, the outer ends of the split filaments are welded on the inner wall surface or the shrinkage inner wall surface of the nozzle outlet or are clamped on smooth concave tracks etched on the inner wall surface or the shrinkage inner wall surface of the nozzle outlet; when the beam splitting filaments are flexible, the beam splitting filaments penetrate into holes on the inner wall surface of the outlet to be fixed.

3. The method of claim 1, wherein the split filaments in step (1) are made of metal or nonmetal, the metal is steel wire or iron wire, and the nonmetal is aramid fiber.

4. The method according to claim 1, wherein the number of the split filaments in the step (1) is 1 or several, and the outer ends of the split filaments are located on the same or different planes in the vertical direction.

5. The method of claim 1, wherein the through-hole nozzle in step (1) comprises an external thread, a nozzle external wall surface, a vertical internal wall surface, a converging internal wall surface, and an outlet internal wall surface; the beam splitting filaments are positioned in the nozzle and divide the outlet of the nozzle into sections.

6. The method of claim 1, wherein the angle of the split filaments in step (2) is 0 °, 30 °, 45 ° or 60 ° with respect to the transverse direction of the print plane.

7. The method according to claim 1, wherein the fiber bundles in the step (3) are low-filament-number continuous fiber bundles of the same kind or different kinds and having the same or different filament numbers.

8. The method of claim 1, wherein the resin material in step (3) is polylactic acid, nylon, ABS, polycarbonate or PEEK.

9. The method of claim 1, wherein the fiber bundles in step (3) comprise one or more of glass fibers, carbon fibers, and aramid fibers.