Method of making a woven preform based on resin powder filling and the resulting preform

Abstract

The application provides a woven preform preparation method based on resin powder filling. In a three-dimensional weaving process, a hot plastic resin powder is heated to a semi-melted state by a resistance wire, so that the hot plastic resin powder is attached to the surface of a yarn bundle. After the preform is formed, hot pressing and curing can be directly performed. Compared with a traditional process, the resin impregnation process can be avoided, the production efficiency is improved, rapid forming is realized, the problems of uneven resin impregnation, large porosity and lack of glue caused by poor resin fluidity are avoided, the product quality of the woven composite material is improved, and the mechanical properties of the finished product are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material forming, in particular to a braided preform preparation method based on resin powder filling. BACKGROUND

[0002] The braiding technology of composite material is a composite preform forming process in which reinforcing fibers are braided together in a specific structure and direction. The automated braiding process has higher preform forming efficiency and near-net-shape advantages, and by controlling the orientation and density of the reinforcing fibers, better in-plane and interlaminar performance can be achieved, which has broad application prospects in the fields of aerospace, rail transportation and wind power generation.

[0003] The traditional braided composite material forming process first forms a fiber preform, and then uses resin transfer molding, resin film infiltration or autoclave curing process for curing and forming. These curing methods all need to first impregnate the preform with resin, which is complex and the forming quality is affected by the low flowability of the resin, which is prone to uneven resin distribution, large amount of pores and lack of glue.

[0004] Therefore, there is a need for a new technical solution to solve the above problems. SUMMARY

[0005] The present application provides a braided preform preparation method based on resin powder filling to solve the problem of complex process and uneven resin distribution, large amount of pores and lack of glue in the existing braided composite preform which needs to be impregnated with resin before curing and forming.

[0006] The present application also provides a preform obtained by the above braided preform preparation method based on resin powder filling.

[0007] To achieve the above-mentioned purpose, the braided preform preparation method based on resin powder filling provided by the present application has the following technical solutions:

[0008] A braided preform preparation method based on resin powder filling, comprising the following steps:

[0009] Step one, the yarn is drawn out from the braiding machine, and the yarn is wrapped in the thermoplastic resin powder;

[0010] Step two, start heating the thermoplastic resin powder to a semi-melted state;

[0011] Step three, start the braiding machine to complete one braiding step;

[0012] Step four, start the lifting mechanism to pull the formed fiber preform;

[0013] Step five, repeat steps three and four until the braided preform of a predetermined length is obtained.

[0014] Step six, take out the woven preform in step five has been shaped, put into the pressure mold and placed in the oven heat curing, demolding obtain fiber woven reinforced thermoplastic composite.

[0015] Further, in step one, a resin powder box is provided; the resin powder box is internally provided with a receiving cavity for accommodating resin powder, a water bath layer surrounding the receiving cavity, and a resistance wire located below the water bath layer, and a plurality of holes are opened at the bottom and top of the resin powder box to pass the yarn bundle.

[0016] Further, the resin powder box is arranged below the lifting mechanism for lifting the yarn, and the yarn passes through the resin powder box and is wrapped by the semi-melted thermoplastic resin powder in the resin powder box.

[0017] Further, the thermoplastic resin powder is one or more of thermoplastic phenolic resin powder, polyether ether ketone powder, and polyimide powder.

[0018] Further, the fiber woven fabric is prepared by a three-dimensional rotary braiding machine, the braided yarn is one or more of carbon fiber tows, glass fiber tows, and aramid fiber tows, the braiding angle is 15-45°, the cross-sectional size is 6mm x 6mm, and the density is 0.5g / cm 3 .

[0019] Further, when the resistance wire heats the thermoplastic resin powder in step two, the relationship between the temperature T of the thermoplastic resin powder and the time t satisfies the following condition:

[0020]

[0021] In the formula, T0 is the initial temperature, r is the heat transfer efficiency, m r is the mass of the resin powder, c r is the specific heat of the resin powder, V is the rated power of the resistance wire, and R is the resistance value of the resistance wire.

[0022] Further, when the resistance wire heats the thermoplastic resin powder in step two, the relationship between the heat Q required for the resin powder to melt and the temperature T satisfies the curve Q=F(T), which is obtained by calibrating and measuring the actual melting process of the corresponding resin.

[0023] Further, in step six, the specific operation of taking out the shaped preform and placing it in the pressure mold is as follows: the release cloth, the preform, the release cloth, the release film, and the flow guide net are placed in the pressure mold in sequence, the cover plate is pressed, and the oven is placed in the oven.

[0024] Further, the step six adopts a staged hot-pressing curing: the first stage is a melting treatment stage, the temperature is 80-120℃, the pressure is 10-50MPa, and the treatment time is 0.5-1h; the second stage is a mold pressing curing stage, the pressure in the oven is kept at 10-50MPa until the room temperature is recovered, so that the thermoplastic resin is cooled and cured.

[0025] Further, the thermoplastic resin powder has a particle size of 160-300 mesh, and the fiber braid is a two-dimensional braid and / or a three-dimensional braid.

[0026] Beneficial effects:

[0027] The composite material forming process of the present application heats the thermoplastic resin powder to a semi-melted state by resistance wire during the braiding process, so that the resin powder is attached to the surface of the yarn bundle, the resin powder is directly introduced into the fiber braid, and after the preform is formed, it can be directly introduced into the oven for staged heating and curing. This method has the advantages of near-net-shape of the composite material braiding process, compared with the traditional resin transfer molding, resin film infiltration or autoclave curing preform curing process, the production efficiency is improved, the resin impregnation process is avoided, the fiber braiding reinforced thermoplastic composite material rapid forming can be realized, the defects such as uneven impregnation, large amount of pores and lack of glue caused by poor resin flowability are reduced, and the quality of the braided composite product is improved. At the same time, compared with the traditional braiding process, the resin powder attached to the surface of the yarn bundle during the braiding process can reduce the fuzzing and breaking caused by the friction between the yarns, reduce the yarn friction damage during the braiding process, and improve the quality of the component forming. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a flow chart of the braided preform forming and curing based on resin powder filling in the present application;

[0029] Figure 2 It is a schematic diagram of the thermoplastic resin powder box in the present application;

[0030] Figure 3 It is a schematic diagram of the relationship between the heat Q required when the thermoplastic resin powder is melted and the temperature T, Q=F(T);

[0031] Figure 4 It is a schematic diagram of the three-dimensional rotary braiding machine used in the present application;

[0032] Figure 5 It is a schematic diagram of the braided preform curing and forming process based on resin powder filling in the present application. DETAILED DESCRIPTION

[0033] Example one

[0034] As shown in Figure 1 , the present embodiment provides a method for preparing a woven preform based on resin powder filling, comprising the following steps:

[0035] Step one, yarn is drawn out from the weaving machine and passes through a resin powder box containing thermoplastic resin powder fixed to the lifting mechanism. The thermoplastic resin powder box, as shown in Figure 2 , includes a resistance wire, a water bath layer, and a thermoplastic resin powder layer, with 80 circular holes of 2mm in diameter on the bottom surface, and porcelain eyes installed in the holes to reduce friction between the yarn and the plastic box. The resin powder box contains thermoplastic resin powder with a particle size of 160-300 mesh. After completing this step, the next step can be directly started, or the yarn tension, forming plane height, lifting mechanism feed amount, etc. can be adjusted to obtain a woven fabric with a specific structure.

[0036] Step two, start the resistance wire to heat the thermoplastic resin powder in the water bath to a semi-melted state, with a heating temperature of 70-80℃. In this embodiment, as shown in Figure 3 , the relationship between the heat Q required for the melting of the thermoplastic resin powder and the temperature T satisfies the curve Q=F(T), which is obtained by calibrating the actual melting process of the corresponding resin. At the same time, the relationship between the resin powder temperature T and the time t satisfies the following conditions:

[0037]

[0038] where T0 is the initial temperature, r is the heat transfer efficiency, m r is the mass of the resin powder, c r is the specific heat of the resin powder, V is the rated power of the resistance wire, and R is the resistance value of the resistance wire.

[0039] Step three, start the weaving machine and rotate the angle wheel and dial in sequence to drive the yarn interlacing motion to complete one weaving step. The three-dimensional rotary weaving machine structure used in this embodiment, as shown in Figure 4 , has a weaving angle of 15-45° for the formable woven fabric, a cross-sectional size of 6mm x 6mm, and a density of 0.5g / cm 3 . After completing this step, the next step can be directly started, or the formed preform can be densified using a densification device.

[0040] Step four, start the lifting mechanism to pull the formed preform structure, with a pulling speed of 2mm per weaving cycle, tension the yarn, and keep the forming plane at the same height.

[0041] Step five, repeat steps three and four to gradually and alternately form the fiber woven fabric until the desired length requirement is reached.

[0042] Step six, remove the preform obtained in step five, as shown inFigure 5 The thermoplastic composite material is obtained by the staged hot-pressing and curing of the woven fiber-reinforced thermoplastic composite material. The release cloth, the preform, the release cloth, the release film, and the flow guide net are sequentially placed in the pressure mold, the cover plate is pressed, and the mold is placed in the oven. First, the oven is heated to 80-120℃, the pressure is 10-50MPa, and the processing time is 0.5-1h, so that the thermoplastic resin powder is completely melted, then the mold is cured, the oven stops heating and keeps the pressure at 10-50MPa until it returns to room temperature, and finally the pressure mold is taken out and the woven fiber-reinforced thermoplastic composite material is obtained by demolding.

[0043] According to the performance requirements of the composite material, the thermoplastic resin powder can be one or more of thermoplastic phenolic resin powder, polyether ether ketone powder, and polyimide powder, the structure of the woven fabric can be one or more of two-dimensional woven fabric and three-dimensional woven fabric, and the woven yarn can be one or more of carbon fiber tows, glass fiber tows, and aramid fiber tows. According to the structural requirements of the composite material, the parameters such as the pitch, the weaving angle, and the weaving length of the woven fabric are determined.

[0044] Example Two

[0045] The preform prepared by the preparation method of the woven preform filled with resin powder in Example One is provided. The raw material yarns used to form the preform have been wrapped with resin powder, so the formed preform includes 40-50wt% of thermoplastic resin powder with a particle size of 160-300 mesh and 50-60wt% of fiber woven fabric, which is one or more of two-dimensional woven fabric and three-dimensional woven fabric.

[0046] The composite material forming process of the present application heats the thermoplastic resin powder to a semi-melted state by resistance wire during the weaving process, so that the resin powder is attached to the surface of the yarn bundle, and the resin powder is directly introduced into the fiber woven fabric. After the preform is formed, it can be directly placed in the oven for staged heating and curing. This method has the advantage of near-net-shape forming of the composite material weaving process. Compared with traditional preform curing processes such as resin transfer molding, resin film infiltration, or autoclave curing, the production efficiency is improved, and the resin impregnation process is avoided. The fiber woven reinforced thermoplastic composite material can be rapidly formed, the defects such as uneven impregnation, large amount of pores, and lack of glue caused by poor resin flowability can be reduced, and the quality of the woven composite product is improved. At the same time, compared with the traditional weaving process, the resin powder attached to the surface of the yarn bundle during the weaving process can reduce the fuzzing and breaking caused by the friction between the yarns, reduce the yarn friction damage during the weaving process, and improve the quality of the formed components.

Claims

1. A method for preparing a resin powder filled woven preform based on, characterized by, The method comprises the following steps: Step one, yarn is drawn out from the braiding machine and wrapped in thermoplastic resin powder; a resin powder box is provided; the resin powder box is provided with a receiving cavity for containing resin powder, a water bath layer surrounding the receiving cavity, and a resistance wire below the water bath layer, and a plurality of holes are opened at the bottom and top of the resin powder box for passing yarn bundles; the resin powder box is arranged below a lifting mechanism for lifting the yarn, and the yarn passes through the resin powder box and is wrapped in semi-melted thermoplastic resin powder in the resin powder box; Step two, start heating the thermoplastic resin powder to semi-melted state; Step three, start the braiding machine to complete one braiding step; Step four, start the lifting mechanism to pull the formed fiber preform; Step five, repeat steps three and four until the desired length of braided preform is obtained; Step six, take out the formed braided preform in step five, put it into a pressure mold and place it in an oven for hot pressing and curing, and demold to obtain a fiber braided reinforced thermoplastic composite material.

2. The method for preparing a woven preform based on resin powder filling according to claim 1, characterized in that, The thermoplastic resin powder is one or more of thermoplastic phenolic resin powder, polyether ether ketone powder, and polyimide powder.

3. The method according to claim 1 or 2, wherein The fiber braid is prepared by a three-dimensional rotation braiding machine, the braided yarn is one or more of carbon fiber tows, glass fiber tows and aramid fiber tows, the braiding angle is 15-45°, the cross-sectional size is 6mmx6mm, and the density is 0.5g / cm 3 .

4. The method for preparing a woven preform based on resin powder filling according to claim 1, characterized in that, The relationship between the temperature of the thermoplastic resin powder and time when the electric resistance wire is heated by water bath in the step two satisfies the following conditions: T t between the temperature of the thermoplastic resin powder and time​ ， wherein T 0 is the initial temperature, r is the heat transfer efficiency, m r is the resin powder mass, c r is the specific heat of the resin powder, V is the rated power of the resistance wire, R is the resistance value of the resistance wire.

5. The method of claim 1 or 4, wherein the resin powder filling based woven preform is prepared by the steps of: (a) preparing a woven fabric by weaving a plurality of fibers; (b) impregnating the woven fabric with a resin; (c) curing the resin; and (d) cutting the woven fabric into a predetermined shape. The amount of heat required to melt the resin powder in step two when the resistance wire is heated by water bath Q The relationship between temperature T and time satisfies the curve Q=F ( T ) obtained by calibrating the actual melting process of the corresponding resin.

6. The method for preparing a woven preform based on resin powder filling according to claim 1, characterized in that, The specific operation of taking out the formed preform and putting it into the pressure mold in step six is: placing release cloth, preform, release cloth, release film, and flow guide net in the pressure mold in sequence, pressing the cover plate and placing it in the oven.

7. The method for preparing a woven preform based on resin powder filling according to claim 1 or 6, characterized in that, In step six, the hot pressing and curing is carried out in stages: the first stage is a melting treatment stage, the temperature is 80-120℃, the pressure is 10-50MPa, and the treatment time is 0.5-1h; the second stage is a mold pressing and curing stage, the pressure in the oven is kept at 10-50MPa until room temperature is restored, and the thermoplastic resin is cooled and cured.

8. A preform obtained by the method of manufacturing a woven preform according to any one of claims 1 to 7, characterized in that, The method comprises 40-50% of thermoplastic resin powder and 50-60% of fiber braided material by mass percentage, the particle size of the thermoplastic resin powder is 160-300 mesh, and the fiber braided material is two-dimensional braided material and / or three-dimensional braided material.

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