Pultrusion method for fiber with variable section size and shape

Abstract

The invention discloses a pultrusion method for fibers with variable section sizes and shapes. The method comprises the following steps: firstly, dividing a fiber laying layer into a reserved fiber laying layer and a removed fiber laying layer, and adding an isolation material layer between the reserved fiber laying layer and the removed fiber laying layer; then, simultaneously infiltrating resin under the condition of keeping mutual layers unchanged, then synchronously entering the inner cavity of the mold, and heating and curing to form a common body; and after the whole body is taken out of the mold, the removed fiber laying layer and the isolation material are peeled off together along the isolation material, so that the pultrusion profile with the required section size is obtained. On the basis of an existing pultrusion process technology, a complete fiber laying layer is designed according to the section size and shape of a mold, an isolation material layer is added between the removed fiber laying layer and the reserved fiber laying layer for isolation, after the three materials are jointly cured and formed in the pultrusion mold, an unneeded surface layer material is removed between the isolation materials, and the fiber laying layer and the fiber laying layer are separated from each other. Therefore, the purpose of adjusting the product size is achieved.

Description

Technical Field

[0001] The invention relates to a fiber extrusion and drawing forming process technology, in particular to a fiber extrusion and drawing forming method with variable cross-sectional size and shape. Background Art

[0002] The basic process of existing fiber pultrusion technology mainly includes six parts: yarn arrangement, resin dipping, pre-forming, mold curing, pulling, and cutting. Among them, (1) yarn arrangement is to place the fibers on the yarn rack in a certain order and pass them through the pre-set yarn feeding plate (2) resin dipping is to immerse the fibers in resin so that the fibers are fully impregnated (3) pre-forming is to pre-shape the fibers impregnated with resin according to the cross-sectional size and shape of the product (4) mold curing is to heat the mold to solidify the resin and fiber to form a community (5) pulling is to pull the solidified pultruded profile out of the mold (6) cutting is to cut the pultruded profile into a certain length.

[0003] The existing fiber pultrusion molding process technology generally adopts two methods to obtain pultruded profiles with different cross-sectional dimensions and shapes: (1) For profiles with similar cross-sectional dimensions and shapes to those of existing molds, the existing molds are used for pultrusion molding, and then mechanical cutting and grinding are used to obtain the desired pultruded profiles. The cutting and grinding method can easily lead to damage to the fiber layer, affecting the mechanical properties of the profile. At the same time, dust adheres to the surface of the composite material, affecting the bonding strength or spraying effect of the profile. (2) For profiles with significantly different cross-sectional dimensions and shapes from those of existing molds, it is necessary to purchase pultrusion molds with different cross-sectional dimensions and shapes, which increases the cost of mold procurement. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and propose a fiber pultrusion molding method with variable cross-sectional size and shape. The interlayer peeling method is adopted to achieve the change of the cross-sectional size and shape of the pultruded profile without changing the mold. Pultruded profiles with different cross-sections can be prepared without changing the pultrusion mold, thereby achieving the purpose of adjusting the product size.

[0005] The technical solution for achieving the purpose of the invention is: a fiber pultrusion method with a variable cross-sectional size and shape, the steps of which are: Firstly, the fiber ply is divided into a retained fiber ply and a removed fiber ply, and an isolation material layer is added between the retained fiber ply and the removed fiber ply; Then, the fibers are simultaneously infiltrated with resin while retaining the fiber layer and the isolation material layer and removing the fiber layer to keep the layers unchanged; then, the fibers are simultaneously introduced into the mold cavity and cured into a common body under the mold heating temperature; After the pultrusion material comes out of the mold, the fiber layer and the insulation material are peeled off together along the insulation material to obtain a pultruded profile with the required cross-sectional size.

[0006] The isolation material layer uses an isolation material whose bonding property with the resin is lower than that of the fiber and the resin, and generally uses a release cloth, such as PA66. The fiber material for removing the fiber layer generally uses low-cost raw and auxiliary materials, which can effectively reduce product costs.

[0007] Based on the existing pultrusion process technology, the present invention designs a complete fiber layer according to the cross-sectional size and shape of the mold, adds an isolation material layer between the removed fiber layer and the retained fiber layer for isolation, and after the three materials are solidified and formed together in the pultrusion mold, the unnecessary surface material is removed between the isolation materials. It not only protects the fiber layer on the surface of the profile, but also makes it easy to remove the surface material and retain the intact cross-sectional size of the profile, so as to achieve the purpose of adjusting the product size. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram of the fiber extrusion and pultrusion process flow; Figure 2 It is a cross-sectional view of the extruded profile (before and after peeling). DETAILED DESCRIPTION

[0009] The present invention will be further described in detail below in conjunction with the embodiments and drawings. Example

[0010] As shown in the figure, take a circular tube as an example.

[0011] According to product requirements, it is determined that the fiber ply needs to be retained. In this embodiment, the retained fiber ply 1 is a layer of carbon fiber.

[0012] The number and thickness of the fiber ply 3 to be removed are determined according to the size of the mold cavity and the thickness of the retained fiber ply. In this embodiment, the number of fiber ply to be removed is determined to be one layer according to the size of the mold cavity, and glass fiber is selected as the removed fiber.

[0013] An isolation material layer 2 is arranged between the retained fiber layer and the removed fiber layer, and the isolation material needs to be a release cloth PA66 material.

[0014] Under the action of the composite traction mechanism, the fibers impregnated with resin and the isolation materials enter the mold cavity simultaneously while maintaining the layer relationship unchanged, and solidify into a whole under the heating temperature of the mold. Among them, the resin is epoxy resin. The isolation material and the resin are non-sticky or low-sticky in the heated and solidified state, so the bonding index between the isolation material and the resin is lower than the bonding index between the fibers of the retained fiber layer and the resin.

[0015] After the composite material leaves the mold, the unnecessary fiber ply and the insulation material are peeled off together along the insulation material. During the production process, if the cross-sectional dimensions of the profile need to be changed, it can be achieved by adjusting the position of the insulation material in the ply.

[0016] In this embodiment, the existing round tube mold has a core rod diameter of 30mm and an outer diameter of 50mm. The round tube profile produced by pultrusion using this mold has an inner diameter of 30mm and a wall thickness of 10mm. If you need to obtain a pultruded round tube profile with an inner diameter of 30mm and a wall thickness of 5mm, the present invention can be used without changing the mold. The steps are as follows: Material accounting: The fiber volume content is 65%. The fiber usage in each area is designed as follows: The inner diameter is 30mm, the wall thickness is 5mm, and in order to retain the ply, carbon fiber is used, with 402 fibers; The inner diameter is 40mm and the wall thickness is 5mm. In order to remove the fiber ply, glass fiber is used, and the number of fibers used is 248.

[0017] 2. Mould threading: (1) According to the circular threading process of the pultruded profile, 193 fibers are passed through the die; (2) The isolation material (release cloth) is circularly wrapped around the outside of the 193 fibers and passes through the mold; (3) According to the circular threading process of the pultruded profile, 248 fibers are passed through the mold on the outside of the isolation material.

[0018] 3. Round tube pultrusion manufacturing: (1) The mold is heated to the resin curing process temperature; (2) The fiber is impregnated with resin in the resin tank; (3) The traction machine pulls out the fibers and isolation material (release cloth) from the mold; (4) As the traction machine continues to run, the fiber impregnated with resin is cured by heating the mold. After exiting the mold, a pultruded round tube with an inner diameter of 30 mm and a wall thickness of 10 mm is obtained.

[0019] 4. Remove the outer fiberglass layer: (1) Use a cutting machine to cut to the isolation layer, cut several times along the axial direction of the pultruded tube, remove the outer layer and divide the ply into several layers; (2) Peeling off the removal layer by mechanical beating; (3) The demoulding cloth is cut open along the axial direction with a blade and peeled off. The remaining profile is the required pultruded round tube with an inner diameter of 30 mm and a wall thickness of 5 mm.

Claims

1. A fiber pultrusion method with a variable cross-sectional size and shape, the steps of which are: Firstly, the fiber ply is divided into a retained fiber ply and a removed fiber ply, and an isolation material layer is added between the retained fiber ply and the removed fiber ply; Then, the fiber layers, the insulating material layers and the removed fiber layers are simultaneously infiltrated with resin while the positions of the layers remain unchanged; the fiber layers, the insulating material layers and the removed fiber layers are then simultaneously introduced into the mold cavity and heated and cured into a common body; After the pultrusion material comes out of the mold, the fiber layer and the insulation material are peeled off together along the insulation material to obtain a pultruded profile with the required cross-sectional size.

2. The fiber pultrusion method with variable cross-sectional dimensions according to claim 1, characterized in that: The insulating material used in the insulating material layer has a lower bonding property with the resin than the bonding property between the fibers and the resin.

3. The fiber pultrusion method with variable cross-sectional dimensions according to claim 1 or 2, characterized in that: The isolation material layer is made of release cloth.

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