KR101544343B1 - The manufacturing method of door pillar for car and the door pillar made by the method - Google Patents

Abstract

The present invention relates to a method for manufacturing a car door pillar and a door pillar made by the manufacturing method and, more specifically, to a method for manufacturing a car door pillar which performs an injection process not to need a painting work by using polymethacrylic acid methyl and a door pillar made by the method. The present invention provides the method for manufacturing the car door pillar, comprising a drying step; a mounting step; a heating step; a measuring step; an injection step; and a cooling step. In the drying step, the polymethacrylic acid methyl is dried. In the mounting step, the polymethacrylic acid methyl dried in the drying step is mounted in an injection cylinder. In the heating step, the cylinder where polymethacrylic acid methyl is mounted is heated in a longitudinal direction at several different temperature stages. In the measuring step, the polymethacrylic acid methyl is measured as much as an amount to be injected. In the injection step, the measured polymethacrylic aid methyl is injected in a mold at regular pressure. In the cooling step, the polymethacrylic acid methyl is cooled in a longitudinal direction from an inlet of the injection mold at several different temperature stages. The present invention injects the polymethacrylic acid methyl in the mold, divides the mold according to several stages, and performs a cooling process differently according to each of the stages to manufacture the door pillar, thereby not needing the painting process. Therefore, the present invention may eco-friendly manufacture the door pillar because of not discharging environment pollution materials as well as simplify the door pillar manufacturing processes.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a door pillar for a vehicle,

The present invention relates to a method for manufacturing a door pillar for an automobile and a door pillar made by the method. More particularly, the present invention relates to a method for manufacturing a door pillar for an automobile by injection molding using polymethyl methacrylate And a door pillar made by the method.

Conventional automobile doorpillar can be manufactured by forming the metal through roll forming and press process and then painting the product itself or by using a decorative door filler made by coating process after plastic injection molding on the door module And is produced by the method of attaching.

Therefore, the door pillar is required to be painted in part and the tape specification in others. At this time, tape is also used. Therefore, the coating process is essential when making all door pillar.

Korean Patent Publication No. 2008-0034314 Japanese Patent No. 3862075 Korean Patent No. 240981 Japanese Laid-Open Patent Application No. 2012-0006536

The coating process used in the production of door pillars for automobiles generates VOC (Volatile Organic Compounds) and consists of six complicated processes such as primer process. Volatile organic compounds (VOCs) are easily vaporized into the atmosphere because of high vapor pressure, and when they coexist with nitrogen oxides in the atmosphere, they generate photochemical reaction under the action of sunlight, causing photochemical smog of ozone and PAN (Peroxyacetyl nitrate).

Therefore, the conventional automobile door pillar is complicated in its process because the painting process is performed, resulting in not only high working efficiency but also environmental pollution.

The present invention is intended to solve the above problems. The present invention aims to provide a method for manufacturing a door pillar by injection molding with polymethyl methacrylate (PMMA), and to manufacture a door pillar by a non-coating process without a painting process, and a door pillar manufactured by the method.

A method for manufacturing a door pillar for an automobile according to an aspect of the present invention includes a drying step, a receiving step, a heating step, a metering step, an injection step, and a cooling step. The drying step is to dry methyl polymethacrylate. In the step of receiving, the polymethyl methacrylate dried in the drying step is put on the injection cylinder. In the heating step, the cylinder in which the polymethyl methacrylate is loaded is heated to several different temperatures along the length direction. The metering step meters the polymethyl methacrylate by an amount to be injected. The injection step injects the metered polymethyl methacrylate into a mold at a constant pressure. The cooling step is carried out by cooling the poly (methyl methacrylate) to a plurality of different temperatures along the longitudinal direction based on the injection port of the injection mold.

In the method for manufacturing a door pillar for an automobile, it is preferable that the heating step is performed at a low temperature and a high temperature in a multi-step manner in a direction farther from the injection port of the cylinder in the longitudinal direction. The cooling step may be performed in a multi-stage manner from a low temperature to a high temperature in a direction away from the injection port of the mold near the longitudinal direction. This makes it possible to reduce the gloss variation of the surface of the door pillar.

In the method for manufacturing a door pillar for an automobile, it is preferable that the injection step is divided into multiple stages from a high pressure to a low pressure so as to inject the polymethyl methacrylate into the mold in one direction in the longitudinal direction.

In the method for manufacturing the automotive door pillar, it is preferable that the cooling step is performed by introducing cooling water having different temperatures set to different temperatures in the mold in which the cooling lines are formed in multiple stages along the longitudinal direction, into the cooling line.

According to one aspect of the present invention, a door pillar for an automobile is formed by injecting polymethylmethacrylate into a mold, cooling the mold at a low temperature and a high temperature in a multi-stage manner in a direction farther from the injection port of the mold, do.

According to the present invention, since polymethylmethacrylate is injected into a metal mold, the metal mold is divided into several stages, and the door pillar is manufactured by cooling the metal molds at different stages. Thus, a paint having similar surface gloss performance A door pillar that does not require a process is manufactured. Accordingly, not only the manufacturing process of the door pillar can be simplified, but also the door pillar can be manufactured in an environmentally friendly manner without discharging environmental pollutants.

1 is a conceptual view of a method of manufacturing a door pillar for an automobile according to the present invention,
Fig. 2 is a perspective view of a door pillar manufactured by the method of Fig. 1,
Fig. 3 is a conceptual diagram of a vehicle to which the door pillar of Fig. 2 is applied,
Fig. 4 is a conceptual view of a mold apparatus for manufacturing the automotive door pillar of Fig. 1,
5 is a conceptual view of a mold of the mold apparatus of FIG.

1 to 5, a method of manufacturing a door pillar for an automobile according to the present invention will be described.

The manufacturing method of the door pillar for an automobile according to the present invention is characterized in that the manufacturing method of the automotive door pillar includes a drying step S11, a receiving step S13, a heating step S15, a metering step S17, an injection step S19, ).

The door pillar 10 according to the present invention is manufactured using polymethyl methacrylate (PMMA), and physical properties of the polymethyl methacrylate used are shown in Table 1 below. The door pillar 10 of the present embodiment is formed by injection molding using polymethyl methacrylate having the physical properties shown in Table 1.

Property Condition Unit Method Value Physical properties Refractive index
(Refractive Index) nd - ISO 489 1.49 Thermal property Melt Index
(Melt Flow Index) 239 / 3.8 g / 10 min ISO 1133 2.3 Vicat softening point
(VICAT Softening Point) B / 50 ℃ ISO 306 102 Heat distortion temperature
(Heat Deflection Temperature) 1.8 Mpa ℃ ISO 75 94 Coefficient of linear expansion
(Coefficient of Linear Expansion) - Mm / mm / ° C ASTM D696 7 x 10 ^-5 Mechanical property Sharp impact strength
(Charpy Impact Strength) Unnotched KJ / ㎡ ISO 179 1e / U 20 Rockwell hardness
(Rockwel Hardness) M scale M scale ASTM D785 100 The tensile strength
(Tensile Strength) 5 mm / min MPa ISO 527 74 Tensile elongation
(Tensile Elongation) 5 mm / min % ISO 527 4.5 General property importance - g / cm3 ISO 1183 1.18 Mold Shrinkage
(Mold shrinkage) - % ASTM D955 0.2 to 0.6 Absorption rate
(Water Absorption) 24hr % ASTM D570 0.4 Flammability
(Flammability) - - UL94 HB

In the drying step (S11), the material of polymethyl methacrylate (PMMA) is put in a dehumidifier and dried at about 80 to 95 DEG C for about 2 to 3 hours.

In the receiving step (S13), the polymethyl methacrylate dried in the drying step (S11) is put into the injection cylinder (13). At this time, the polymethyl methacrylate dried in the drying step (S11) is put into a hopper (11), dried once, and then put into the cylinder (13) in the hopper (11).

In the heating step S15, the cylinder 13 in which the polymethyl methacrylate is loaded is heated to different temperatures along the longitudinal direction. At this time, the cylinder 13 is heated at a low temperature and a high temperature in a multi-stage manner in a direction far from the vicinity of the injection port of the cylinder 13 along the longitudinal direction.

In the case of this embodiment, the cylinder 13 is divided into nozzle sections, N1 section, N2 section, N3 section, and N4 section from the nozzle along the longitudinal direction. The nozzle part is heated to 235 to 240 ° C, the N1 part to 230 to 235 ° C, the N2 part to 230 to 235 ° C, the N3 part to 225 to 230 ° C, and the N4 part to 215 to 220 ° C. Then, polymethyl methacrylate (PMMA) is melted in the cylinder 13.

The metering step S17 measures the amount of polymethyl methacrylate by an amount to be injected from the inside of the cylinder 13. The mold must be closed and weighed before weighing.

In the injection step S19, the metered polymethyl methacrylate is injected into the mold 15 at a constant pressure. At this time, if the injection is performed at a single pressure, the polymethyl methacrylate may not be formed into a desired shape. Thus, in the injection step S19, the poly (methyl methacrylate) is injected into the mold 15 by pressurizing the multi-step pressure. In the case of this embodiment, the pressure is applied in three stages. In this case, the first stage is a static pressure stage and is pressurized at a pressure of 1750 kg / cm2. In the second stage, a pressure of 1050 kg / cm2 is applied to maintain the constant pressure, and in the third stage, 450 kg / cm2 is applied as a back pressure stage. The pressure applied depends on the burr, humidity and seasonal conditions of the product.

At this time, the mold 15 is formed so that the injection port 16 is formed at one end so that polymethyl methacrylate can be injected in one direction along the longitudinal direction 1 toward the other end.

The cooling step (S21) cools the mold in which the polymethyl methacrylate is injected. The door filler is thin in thickness and relatively long in length. Therefore, when poly (methyl methacrylate) is injected into the mold 15, the temperature varies along the length direction of the mold 15. That is, the temperature near the injection port 16 of the mold in which the polymethyl methacrylate is injected is higher while the temperature is lower as the distance from the injection port 16 is increased. In the conventional case, the mold is cooled by using cooling water at the same temperature when the mold is cooled after injection into the mold. In this case, the temperature of the mold differs in the longitudinal direction, and since it is cooled by the cooling water of the same temperature, a flow mark (weld line, flow mark, etc.) and gloss difference occur in the injection molded product. So it was necessary to do painting after injection molding.

In the cooling step S21 of the present embodiment, the cooling water line 18, which can be separately supplied along the longitudinal direction, is provided in the metal mold 15, and cooling water set at different temperatures is supplied to the respective cooling water lines 18 The mold 15 is cooled. That is, by using a specially designed separate cooling controller, cooling water at a low temperature and a high temperature in a direction farther from the injection port 16 along the longitudinal direction 1 is supplied to each cooling water line 18, ). That is, since the temperature of the mold 15 in the vicinity of the injection port 16 is higher and the temperature of the mold 15 becomes lower as the distance from the injection port 16 increases, the cooling water controlled to a lower temperature is introduced into the injection port 16 of the mold 15 And cooled to a higher temperature controlled cooling water as it moves away from the injection port 16. [ In the case of the present embodiment, the mold is divided into three stages, cooling water of 45 ° C is used in the vicinity of the injection port 16, cooling water of 50 ° C is used in the vicinity thereof, ). Temperature control can vary depending on the situation, taking into account humidity, seasonal conditions, and so on. This can prevent the occurrence of differences in the coolant flow mark (weld line, flow mark, etc.) and surface gloss of the product, thereby omitting the painting operation.

When the cooling is completed, the mold is opened to take out the component.

Therefore, according to the present invention, unpatterned process can be realized, so that environmental pollution caused by a painting operation can be prevented, and a manufacturing process can be simplified to increase production efficiency.

10: door pillar 11: hopper
13: cylinder 15: mold
16:

Claims (5)

A drying step of drying methyl polymethacrylate,
An inlet step of loading the polymethyl methacrylate dried in the drying step into an injection cylinder,
A heating step of heating the cylinder in which the polymethyl methacrylate is placed to a plurality of different stages along the longitudinal direction,
A metering step of metering the polymethyl methacrylate by an amount to be injected,
An injection step of injecting the metered polymethyl methacrylate into a metal mold in one direction in the machine direction by dividing the metal mold into a plurality of stages from a high pressure to a low pressure,
And a cooling step of cooling the poly (methyl methacrylate) to a plurality of different stages along the longitudinal direction based on the injection port of the injection mold. The method according to claim 1,
Wherein the heating step is a step of heating the cylinder at a low temperature to a high temperature in a multi-step manner in a direction farther from the injection port of the cylinder in the longitudinal direction,
Wherein the cooling step cools the mold at a low temperature and a high temperature in a multi-step manner in a direction farther from the injection port of the mold in the longitudinal direction. 3. The method of claim 2,
Wherein the cooling step is carried out by introducing cooling water set at different temperatures into the mold, in which the cooling lines are individually formed in multiple stages along the longitudinal direction, into the cooling line. delete delete

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