KR20210077345A - Method for manufacturing car door impact beam with high strength and lightweight - Google Patents

Abstract

The present invention relates to a method of manufacturing a vehicle door impact beam, in which the vehicle door impact beam is molded by using functional fibers and resins having excellent strength to have a lower specific gravity than a metal and high strength, so that an external impact is absorbed and buffered. According to the present invention, the method of manufacturing the vehicle door impact beam includes: preparing a mixed solution in which graphene oxide is dispersed in a thermoplastic resin; impregnating a plurality of fibers in the mixed solution, and arranging the mixed solution in one direction to form the mixed solution in a sheet shape; preparing a sheet laminate having a surface on which an elastic resin layer is formed by staking sheets in a vertical direction, forming an uppermost layer and a lowermost layer, which are stacked, by using resin powder or a resin film to have a predetermined thickness, and melting the resin powder or the resin film through thermocompression bonding using a heated flat press; and molding the sheet laminate by inserting the sheet laminate in a mold.

Description

Method for manufacturing car door impact beam with high strength and lightweight

The present invention is a method of manufacturing a door impact beam for a vehicle, and more specifically, it is molded using functional fibers and resins having excellent strength, so that the specific gravity is lower than that of metal and high strength, as well as for vehicles capable of absorbing and buffering external shocks It relates to a method of manufacturing a door impact beam.

In an automobile, a door impact beam having a certain rigidity is installed inside the door in the longitudinal direction of the vehicle body between the door outer panel and the door inner panel to protect the occupants and the vehicle body from external impact in the event of an accident.

The door impact beam has high strength that can sufficiently absorb external shocks applied from the side direction of the vehicle, but also needs to be lightweight so as not to impair fuel efficiency, and various technologies are being developed to implement this.

Korean Patent Publication No. 10-2011-0114208 "Door impact beam and manufacturing method therefor" is disclosed as a manufacturing technology of a door impact beam. The patented technology cuts a steel pipe and induction heating to 880 ~ 960 ℃, During molding, cooling water is supplied to the inside of the steel pipe, and the molded steel pipe inner surface is in direct contact with the cooling water. In this manufacturing method, a hollow is formed to realize light weight, and to compensate for strength, the steel material is subjected to hot forming and rapid cooling to improve strength.

As another example, Korean Patent Laid-Open Publication No. 10-2012-0102314, "High-strength hot forming door beam having a tensile strength of 2000 MPa and a method for manufacturing the same" is disclosed. 2000 MPa by using alloy steel with carbon (C), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr), molybdenum (Mo) and boron (B) for the steel pipe material that undergoes the process The door impact beam having the above high strength is being manufactured.

However, such a technique has a limit in realizing weight reduction by using steel, and requires a lot of energy as the metal material needs to be heat-treated at a high temperature.

Republic of Korea Patent Publication No. 10-2011-0114208 (Door impact beam and manufacturing method thereof) Korean Patent Laid-Open Publication No. 10-2012-0102314 (High-strength hot-formed door beam having 2,000 MPa tensile strength and manufacturing method thereof)

Accordingly, an object of the present invention is to provide a method of manufacturing a door impact beam for a vehicle that is lightweight and economically producible because it does not require much energy while sufficiently exhibiting excellent strength.

In order to solve the above problems, the present invention comprises the steps of preparing a mixed solution in which graphene oxide is dispersed in a thermoplastic resin, impregnating a plurality of fibers in the mixed solution, arranging in one direction to form a sheet, and a sheet; is laminated in a vertical direction, and the uppermost and lowermost layers are formed to a predetermined thickness with resin powder or resin film, and then thermocompressed with a heated flat press to melt the powder or resin film to form an elastic resin layer on the surface. It includes a step of manufacturing the sheet laminate, and the step of putting the sheet laminate into a mold to mold it.

In addition, in the present invention, the mixed solution consists of 89.5 to 94.9 wt% of a thermoplastic resin, 0.1 to 0.5 wt% of graphene oxide, and 5 to 10 wt% of an organic solvent.

Further, in the present invention, the elastic resin layer is formed by 10 to 20% of the thickness of the sheet laminate.

The present invention relates to the processing of metal materials while exhibiting excellent lightness and strength by impregnating an excellent functional fiber with a lower specific gravity and strength than metal into a resin, forming a sheet, and stacking a plurality of these to form a vehicle door impact beam. Less energy may be required to reduce production costs, and the surface is made of a soft resin material to absorb and buffer external shocks more effectively.

1 is a flowchart of a method for manufacturing a door impact beam for a vehicle according to the present invention.
Figure 2 is a view schematically showing the process of the vehicle door impact beam manufacturing method according to the present invention.
3 is a cross-sectional view of the sheet laminate manufactured in the present invention.
4 is a test report of strength and tensile modulus of an embodiment of the present invention.

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

This embodiment is provided to more completely explain the present invention to those with ordinary knowledge in the art, and in principle, in explaining the embodiment, the related art function or known configuration is already in the art. If it is determined that the technical features of the present invention may be unnecessarily obscured as is obvious to those skilled in the art, the detailed description thereof will be omitted.

1 is a flowchart of a method for manufacturing a door impact beam for a vehicle according to the present invention, and FIG. 2 is a view schematically illustrating a process thereof. Referring to FIG. 1 , the present invention comprises the steps of preparing a mixed solution in which graphene oxide is dispersed in a thermoplastic resin (S110), impregnating a plurality of fibers 10 in the mixed solution and arranging them in one direction to form a sheet 20 Forming with (S120), stacking a plurality of sheets 20 to prepare a sheet laminate 30 having an elastic resin layer formed on the surface (S130), and forming the sheet laminate 30 into a mold 50 A door impact beam for a vehicle is manufactured through a step (S140) of molding by putting it in the .

The mixed solution prepared in step S110 is impregnated into the fibers 10 to be described later to improve the strength of the fibers 10 and combine the plurality of fibers 10 to be oriented in one direction, thermoplastic resin, graphene oxide and organic solvent. are mixed to form a predetermined viscosity.

The thermoplastic resin is heated and cooled above the glass transition temperature as the base of the mixed solution to improve the strength of the door impact beam formed by bonding a plurality of fibers 10 in one direction. Thermoplastic resins include polyester (PET), polypropylene (PP), polyethylene (PE), acrylic butadiene styrene (ABS), polycarbonate (PC), nylon (Nylon), polyvinyl chloride (PVC), and polystyrene (PS). , polyurethane (PU), polymethyl methacrylate (PMMA), polylactic acid (PLA), Teflon (polytetrafluoroethylene), and may include at least one selected from the group consisting of combinations thereof. The thermoplastic resin is added in an amount of 60 to 80% by weight based on the total weight of the mixed solution. If it is less than 60% by weight, the bonding force between the fibers 10 is weakened and graphene oxide to be described later is difficult to disperse, and when it exceeds 80% by weight, the flexibility is lowered. There is a disadvantage that the brittleness becomes stronger.

Graphene oxide is dispersed in the thermoplastic resin as a fine powder having a diameter of approximately 1 μm to 50 μm and is added to further improve the strength of the fiber 10 . Graphene oxide is added in an amount of 0.1 to 0.5% by weight based on the total weight of the mixed solution. If it is less than 0.1% by weight, it is difficult to expect a strength-increasing effect, and if it exceeds 0.5% by weight, the viscosity of the mixed solution is lowered.

The organic solvent is for uniformly dispersing the graphene oxide powder in the thermoplastic resin. It may be a mixed solvent of two or more selected from tall acetate, dipropylene glycol methyl ether (DPM), cellosolve acetate, butyl cellosolve acetate, butanol, and octanol. The organic solvent is added in an amount of 5 to 10% by weight based on the total weight of the mixed solution, and sonication, roll mill, bead mill or ball mill process may be performed for uniform dispersion of the graphene oxide powder.

The mixture thus composed is composed of a viscosity of 20 cps to 100 cps to effectively impregnate the fiber 10. If the viscosity of the mixture is less than 20 cps, it is difficult to adhere to the fiber 10, and if it exceeds 100 cps, the sheet 20 is formed. Gaps may be formed, which may lower strength and deteriorate workability.

Step S120 is a step of impregnating a plurality of fibers 10 in the mixed solution prepared in step S110 to form a sheet 20, where the fibers 10 are high-strength functional fibers 10 with improved strength than general synthetic fibers, Glass fiber, carbon fiber, aramid fiber, ultra-high molecular weight polyethylene fiber (UHMWPE Fiber), or a composite yarn fiber containing two or more of these fibers may be used. After withdrawing a plurality of strands from the krill on which the high-strength functional fiber 10 is wound, in the same direction, the mixed solution contained in the liquid bath is applied to the fiber 10 using a roller, wound and dried by heating to form a sheet 20 can be manufactured with Such a sheet 20 may be manufactured by laminating a film formed of a mixed solution on a plurality of fibers 10 and heating and pressing.

Step S130 is a step of manufacturing the sheet laminate 30 by laminating a plurality of unidirectional sheets 20 prepared in the previous step and forming an elastic resin layer 31 on the surface. The unidirectional sheets 20 stacked in plurality are stacked so that the arrangement directions coincide, and at this time, a resin powder or a resin film made of a thermoplastic resin or a thermosetting resin is laminated to a predetermined thickness on the uppermost layer and the lowermost layer of the stacked sheet 20. do.

In this way, a plurality of sheets 20 having a resin powder or resin film laminated on the surface are thermocompressed by a heated flat plate press 40, wherein the heated temperature is used to form the sheet 20 with the resin powder or resin film. It is heated above the glass transition temperature of the thermoplastic resin. Through the thermal bonding of the sheet 20, the thermoplastic resin of the mixed solution forming the sheet 20 is melted to bond the other sheets 20 stacked next to each other, and at the same time, the resin powder or resin film is melted to the surface. The sheet laminate 30 on which the elastic resin layer 31 is formed is manufactured. A cross-sectional view of the sheet laminate 30 is shown in FIG. 3 , and the elastic resin layer 31 on the surface of the sheet laminate 30 is made of a soft resin material to effectively absorb and buffer external impacts from the surface. , for this purpose, the resin powder or resin film is formed by 10 to 20% of the thickness of the sheet laminate 30 .

Step S140 is a step of molding the vehicle door impact beam by putting the sheet laminate 30 manufactured in the previous step into the mold 50 . The mold 50 consists of a pair of upper and lower portions each having a concave portion and a protruding portion formed therein according to the shape of the door impact beam, and is pressed by a press to form the door impact beam. In this case, when the elastic resin layer 31 formed on the surface of the sheet laminate 30 when the mold 50 is formed is made of a thermoplastic resin, a hot mold is used, and when it is made of a thermosetting resin, a cold mold can be used.

In the interior of the vehicle door impact beam manufactured in this way, a plurality of sheets 20 in which the functional fibers 10 having excellent strength are arranged in one direction are laminated to express excellent strength, while the surface of the sheet laminate 30 is soft. It is made of a resin material and can absorb and buffer external shocks.

Examples and comparative examples of the present invention prepared in this way will be described in comparison below.

<Example>

A multi-stranded glass fiber is applied using a roller to a mixed solution composed of 89.9% by weight of polyethylene resin, 0.1% by weight of graphene oxide powder, and 10% by weight of carbitol acetate, and then wound in a sheet shape on a winding roll and heated to 160℃ and dried to prepare a sheet form. After laminating the 15 sheets prepared on the epoxy resin film spread on the bottom plate, the epoxy resin film is laminated again on the top layer and compressed with the top plate, but the top plate and the bottom plate are heated to 180° C. A laminate 30 was prepared. The manufactured sheet laminate 30 was put into and pressed into a pair of molds 50 to manufacture three door side beams for a vehicle.

The strength (tensile strength, shear strength, compressive strength) and tensile modulus of the three thus prepared Examples were measured as follows.

One. Tensile strength measurement

The tensile strength and tensile modulus of Examples were measured according to ASTM D3039, and as shown in the test report of FIG. 4, the tensile strength was 1,100 to 1,170 Mpa, and the tensile modulus was measured to be 73 to 78 GPa.

2. Shear strength measurement

The tensile strength and tensile modulus of Examples were measured according to ASTM D3518, and as shown in the test report of FIG. 4, the shear strength was measured to be 65 to 69 MPa.

3. Compressive strength measurement

Tensile strength and tensile modulus of Example were measured according to ASTM D3518, and as shown in the test report of FIG. 4, the compressive strength was measured to be 750 to 1,075 MPa.

As described above, in the interior of the door side beam for a vehicle manufactured according to the present invention, a plurality of sheets in which fibers having a lower specific gravity than metal are arranged in one direction are stacked so that not only excellent strength (tensile strength, shear strength, and compressive strength) but also the surface Due to the formed elastic resin layer, it is possible to effectively absorb and buffer external shocks due to excellent tensile modulus.

The present invention described above is not limited to the described embodiments, and it is apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention. Accordingly, it should be said that such variations or modifications fall within the scope of the claims of the present invention.

10: fiber 20: sheet
30: sheet laminate 31: elastic resin layer
40: flat plate press 50: mold

Claims (3)

A method for manufacturing a door impact beam for a vehicle, the method comprising:
preparing a mixed solution in which graphene oxide is dispersed in a thermoplastic resin;
impregnating a plurality of fibers in the mixed solution, arranging in one direction to form a sheet;
The sheets are laminated in a vertical direction, and the laminated top and bottom layers are formed to a predetermined thickness with resin powder or resin film, and then thermocompressed by a heated flat press to melt the powder or resin film to form an elastic resin layer on the surface. manufacturing the formed sheet laminate; and
A method of manufacturing a door impact beam for a vehicle, comprising: inserting the sheet laminate into a mold and molding the sheet. According to claim 1,
The mixture is
89.5 to 94.9 wt% of a thermoplastic resin, 0.1 to 0.5 wt% of graphene oxide, and 5 to 10 wt% of an organic solvent. 3. The method of claim 2,
The method of manufacturing a door impact beam for a vehicle, characterized in that the elastic resin layer is formed in 10 to 20% of the thickness of the sheet laminate.

Images