KR100438037B1 - manufacturing process for seat back frame by injection molding and seat back frame produced by manufacturing process by this injection molding - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing a seat back frame of an automobile in which a polymer compound based on PA6 / GF, which is a thermoplastic resin of an automobile, is used as an injection molding method, and a seatback frame made by this process.

Reinforced sub metal insert molding is possible during injection, and the material for injection PA6 / GF is 30-50%, and the fiber fiber type is short fiber. Recycling rates of 15 to 30% allow the production of in-line recycle, seat back frame to seat back frame. Main physical properties include tensile strength over 1,500kg / ㎠, tensile modulus over 60,000kg / ㎠, flexural strength over 2,900kg / ㎠, flexural modulus over 80,000kg / ㎠, specific gravity 1.30 ~ 1.40g / ㎠, heat The deformation temperature is over 210 ℃ (kg / ㎠), so it is possible to meet the injection molding of the car seatback frame and the cargo securing test (inertia load performance).

In the detailed injection molding process, raw materials manufacturers store raw materials in hoppers or silos, melt them through a heating cylinder of an injection molding machine, and inject them into molds by clamping force. It consists of a series of optimized injection processes that take out after cooling in a closed mold.

The advantages of this method are that the process is very short, the investment cost is minimized, the design freedom of the molded product is high, and the material cost is rather high, but the weight of the product is reduced by more than 15% by lightening the product design and the mold design optimization of the performance reinforced rib pattern structure. It is an excellent manufacturing method that enables mass production of uniform products.

Description

Manufacturing process for seat back frame by injection molding and seat back frame produced by manufacturing process by this injection molding}

The present invention relates to a manufacturing process of a seat back frame using injection molding and a seat back frame made by the process, and more particularly, a polymer compound mainly based on thermoplastic resin PA6 / GF (polyamide 6 / glass fiber). The present invention relates to a manufacturing process of a seatback frame using injection molding for producing a seatback frame of an automobile by injection molding, and a seatback frame made by this process.

It is well known that the seat back frame of an automobile typically requires rigidity (CARGO SECURING, etc.) and steel has been commonly used.

This steel has been produced by the roll forming process and welding, and it is partially replaced by reinforced plastic as part of the weight reduction of the body to improve fuel efficiency. However, the problem of cost, weight reduction and performance dissatisfaction in the manufacturing process is still a challenge. There has been a constant demand for the development of materials and methods to replace them.

Existing GMT plastic seatback frame manufacturing method is a process of pressing GMT (Glass Mat reinforced Thermoplastic) sheet (Press) to commercialize, G / F MAT (Glass Fiber Weave Mat) and polypropylene (PP) ), Which consists of heating the reinforced polypropylene sheet obtained by extruding and compression molding to pressurize the final product processing with a large press equipment, and several post-processing such as JIG product cooling, punching, drilling, Due to the complexity of the process, problems such as increased manufacturing costs, excessive investment costs, uneven quality and in-line recycling are not possible.

3 is a plastic press process for producing a conventional GMT seatback frame.

GMT sheet cutting process and heating in oven to press molding in press machine. This is followed by a process of cooling the product, followed by a complex process of finishing the final product by punching or drilling.

Looking at the main physical properties of the materials used for the existing glass mat reinforced thermoplastic (GMT), the content of glass fiber (GF) is 30-60%, and the recycling (RECYCLE) is offline (not in-line). Off-line) production, tensile strength is more than 1,500kg / ㎠, tensile modulus is more than 55,000kg / ㎠, flexural strength is more than 1,500kg ㎠, flexural modulus is more than 60,000kg / ㎠, specific gravity 1.15-1.20g / Cm 3, and the heat distortion temperature is 150 ° C or more, it can be seen that it is relatively lower than PA6 / GF over 200 ℃.

In order to satisfy the performance and quality as a seat back frame for automobiles, various conditions of optimization must be secured.

First, in terms of raw materials, tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength and heat deformation temperature should be secured as materials of the seat back frame.

Second, the optimized design of DESIGN PATTERN of reinforcing rib (RIB) should be made to satisfy the product weight (10-30% weight reduction) and product rigidity.

Third, the computer aided engineering (CAE) design verification to satisfy the crew load and CARGO SECURITY regulations among the required performance of the seat back frame for automobiles should be optimized.

Fourth, the molding conditions (cylinder temperature, injection pressure, injection time, mold temperature, cooling conditions) should be optimized to prevent post deformation of the product after injection molding (sink, distortion, shrinkage, etc.)

Fifth, the windage design and manufacturing technology of the mold to prevent post deformation of the product should be secured.

Therefore, it is a high-strength material that is kneaded by adding glass-fiber to nylon, which has good impact resistance and tensile elasticity, and injection molding of PA6 / GF, which has a higher specific gravity than GMT, to take advantage of design freedom. It is possible to lighten through optimization and is suitable for use in functional parts with excellent physical properties. With this optimal injection method, it is possible to secure economical effects of improving fuel economy and reducing production costs, as well as high functional quality of products satisfying excellent moldability and legal performance, and in-line recycling. .

Therefore, the present invention was invented in view of the above, and is to produce a seat back frame for automobiles by injection molding process instead of steel or GMT press process, which is a conventional manufacturing method. It is an object of the present invention to provide a process for producing a seatback frame using injection molding and a seatback frame made by the process.

1 is a seat back frame manufacturing process using the injection molding of the present invention,

2 is a schematic view showing a seat back frame made according to the manufacturing process of FIG.

Figure 3 is a manufacturing process of the seat back frame using the prior art GMT PLASTICS press molding.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

An object of the present invention is to provide a process for manufacturing an automobile seatback frame by injection molding with a thermoplastic resin and a seatback frame made by the process.

The seat back frame of automobiles has been press-molded with steel or G / F reinforced plastics because mechanical strength is usually required.However, the simplification of the parts process, the reduction of cost and investment cost, and the weight reduction are technical challenges. Can be.

Therefore, in order to injection molding the seat back frame of an automobile, it is necessary to select a suitable material that satisfies the function and performance of the product, to satisfy the weight and performance, and to design a CAE and a three-dimensional product for the design that satisfies the product's functionality and rigidity. It can be divided into product design stage, mold design for mold manufacturing, mold manufacturing stage consisting of N / C processing or finishing work, and molding condition optimization stage for minimizing post-strain and residual stress.

First, the basic thickness and reinforcement rib (RIB) design dimensions of the seatback frame made by the manufacturing process according to the present invention are as follows.

The product thickness of the seat back frame and the reinforcement rib (RIB) structure are the most important factors directly related to the performance and product weight, and should be optimized through CAE (Computer Aided Engineering), which is the base of the final seat back frame product. The thickness is 2.0-3.2mm, the structure of the rib (RIB) is 1.5-3.0mm thick and 15.0-35.0mm height (see Fig. 2).

The seat back frame product design and mold fabrication process are as follows.

It is divided into the product design stage and the mold fabrication stage to optimize the selection of materials to satisfy the function and performance of the product, and to satisfy the weight and performance, and the design through the minimum weight and performance optimization CAE.

The work order is summarized in the following order: initial CAE-product schematic design-performance analysis and model fixing-product detail design-mold and injection analysis-mold design-mold manufacturing.

On the other hand, the characteristics of the mold design technology applied at the time of manufacturing the seatback frame injection mold of the present invention are as follows.

When designing the mold, it is important to control the thickness of the product when needed. Windage design (reverse design against the deformation direction of the molded part) is applied to prevent deformation of the product shape.

At this time, the deformation consideration amount can be optimized by the mold CAE result value and the experience value through the starting mold, which is usually 2.0-6.0 mm.

Here, the manufacturing process of the seat back frame using the injection molding according to the present invention with reference to Figure 1 as follows.

The present invention is a very simple process of storing the raw material of the injection molding material in the hopper or silo, heating and melting it through the heating cylinder of the injection molding machine, injecting it into the mold at a predetermined injection pressure, and completing the molding by appropriate holding pressure and cooling to take out the product. The process time is very short and the product productivity is excellent. The injection molding machine has a clamping force of 850-1600 tons, which is determined by the projected area of the product and the average pressure of the resin.

Therefore, the manufacturing process of the present invention comprises the steps of drying through a silo or hopper that can store the injection resin in a predetermined unit amount; After drying, heating and melting the same through a cylinder heater and a screw of the 850-1800ton injection machine; Injection molding the molten resin into a mold manufactured in a 1 to 2 cavity shape, and then cooling and taking out the product in the mold; It consists of the inspection phase of the product.

At this time, in the drying step, the raw material drying conditions of the injection resin should be dried for more than 3 hours at 80-110 ℃ in the case of dehumidifying dryer, 90-120 ℃ for hot air dryer at least 4 hours.

In addition, in the heat melting step, the cylinder and nozzle temperature of the injection machine should be 200-280 ℃.

In a preferred embodiment, the mold used in the injection molding and cooling step is a hot-runner (HOT-RUNNER) type of mold, the conditions during injection / molding are as follows.

1) The mold temperature is within 40-90 ℃,

2) The hot runner temperature is 220-280 ℃,

3) Molding pressure of mold is controlled to 100-130㎏f / ㎠,

4) holding pressure is between 50-90㎏f / ㎠,

5) The clamping pressure of the mold is 140-180㎏f / ㎠,

6) Injection time is adjusted to 1st 5-12 seconds, 2nd 2-8 seconds,

7) Cooling time is between 30 and 100 seconds

On the other hand, the raw material of the injection resin is PA6 / GF as the main material content of short fiber type glass fiber (GF: glassfiber) is 30-55%, the tensile strength is more than 1,500kg / ㎠, tensile modulus as mechanical properties Silver 60,000kg / cm 2 or more, flexural strength is 2,900kg / cm 2 or more, flexural modulus is 80,000kg / cm 2 or more, specific gravity is 1.30 to 1.40g / cm 3, and heat deformation temperature is preferably 200 ° C. or more.

In particular, the regeneration rate of the raw resin for injection is 15 to 30%, which enables in-line production, and defective products are crushed or re-extruded through sprues or gates. Mix and reload.

At this time, the regeneration (RECYCLE) process is composed of injection-grinding-new material mixing-injection molding or injection-grinding-re-extrusion-new material mixing-injection molding.

Accordingly, the pulverized material and the re-extruded resin has a glass fiber (GF) content within 25-50%, mechanical properties of tensile strength of 1,300kg / ㎠ or more, tensile modulus of 50,000kg / cm 2 or more, and bending strength of 2,500kg × cm 2 or more, flexural modulus is 70,000kg / cm 2 or more, specific gravity 1.30 to 1.40g / cm 3, and heat deformation temperature is 180 ° C. or more.

The final product of the seat back frame manufactured according to the manufacturing process of the seat back frame using the injection molding of the present invention has a base thickness of 2.0 to 3.2 mm and a rib (RIB) structure as shown in FIG. Is manufactured to a thickness of 1.5-3.0 mm and a height of 15.0-35.0 mm.

As described above, the manufacturing process of the seat back frame through the injection molding of the present invention is a high-performance material in which the material itself is kneaded by adding glass fiber to nylon having good impact resistance or tensile modulus, and thus has excellent physical properties. Since the process is shorter because there is no need for post-processing, the productivity of the product is improved compared to the GMT, and the product's performance and regulation are satisfied by optimizing the design of the product's reinforcement rib (RIB) structure.

In particular, the design freedom is high and the thickness of the product can be reduced and the minimum RIB can be reinforced, thereby reducing the weight of the product. The excellent in-line recycling enables the production of environment-friendly products. It is effective.

Claims (8)

Drying the resin for injection through a silo or a hopper capable of storing a predetermined unit amount; After drying, heating and melting the same through a cylinder heater and a screw of the 850-1800ton injection machine; Injection molding the molten resin into a mold manufactured in a 1 to 2 cavity shape, and then cooling and taking out the product in the mold; Including the inspection phase of the product, In the drying step, the raw material drying conditions of the injection resin is a sheet back frame using the injection molding, characterized in that for more than 3 hours at 80-110 ℃ in the dehumidification dryer, 90-120 ℃ in the case of hot air dryer Manufacturing process. delete The method of claim 1, In the heating melting step, the cylinder and nozzle temperature of the injection machine is 200-280 ℃ manufacturing process of the seat back frame using the injection molding, characterized in that. The method of claim 1, The mold used in the injection molding and cooling step is a hot-runner mold. Injection / molding conditions 1) The mold temperature is within 40-90 ℃, 2) hot-runner temperature is 220-280 ℃, 3) Molding pressure of the mold is controlled to 100-130㎏f / ㎠, 4) The packing pressure should be made between 50-90㎏f / ㎠, 5) The clamping pressure of the mold is 140-180㎏f / ㎠, 6) The injection time should be adjusted to the first 5-12 seconds, the second 2-8 seconds, 7) Cooling time is between 30 and 100 seconds Manufacturing process of the seat back frame using the injection molding, characterized in that. The method of claim 1, The raw material of the injection resin is: PA6 / GF is the main material, and the content of short fiber type glass fiber (GF: glassfiber) is 30-55%, and the tensile strength is over 1,500kg / ㎠, the tensile modulus is over 60,000kg / ㎠, and the flexural strength. Is 2,900kg / cm 2 or more, flexural modulus is 80,000kg / cm 2 or more, specific gravity is 1.30 to 1.40g / cm 3, heat deformation temperature is 200 ℃ or more manufacturing process of the seat back frame using injection molding. The method according to claim 1 or 5, Regeneration rate of the raw material for injection resin is 15-30%, which enables in-line production, and defective products are mixed with new materials through crushing or re-extrusion through sprue, gate, etc. Process for producing a seat back frame using injection molding, characterized in that the input. The method of claim 6, The pulverized material and the re-extruded resin has a content of glass fiber (GF) within 25-50%, mechanical properties of 1,300kg / ㎠ or more in tensile strength, tensile modulus of 50,000kg / ㎠ or more, and flexural strength of 2,500kg × 2 cm or more, flexural modulus is 70,000 kg / cm 2 or more, specific gravity is 1.30 to 1.40 g / cm 3, and heat deformation temperature is 180 ° C. or more. The base thickness of the seat back frame product manufactured by injection molding using injection molding is 2.0 to 3.2 mm, and the rib structure has a thickness of 1.5 to 3.0 mm and a height of 15.0 to 35.0 mm. The seat back frame made by the manufacturing process of the seat back frame using injection molding.