Airbag Lid Manufacturing Method

Abstract

To provide a method for manufacturing an air bag lid, which forms a foamed urethane layer between a skin and an instrument panel core material to provide a soft feeling of an interior component of an automobile and disables even a small sink existent in the instrument panel core material to be confirmed from an appearance.SOLUTION: A tear line 8 torn during development of an air bag 17 is formed when an instrument panel core material 3 is formed in a mold of an injection molding machine. A lid body 10 in which an opening 11 is formed to face the tear line 8 is fitted to the backside of the instrument panel core material 3 through heat welding. The skin 12 and the instrument panel core material 3 having the tear line 8 formed and the lid body 10 heat-welded are set in a mold of a urethane foam molding machine. A urethane foaming agent is poured between the skin 12 and the instrument panel core material 3 to form a foamed urethane layer 13 through urethane foam molding, and the skin 12 and the instrument panel core material 3 are integrated.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an airbag lid in which an airbag is disposed inward to protect an occupant in a passenger seat of a vehicle.

Background Art

[0002] Techniques for forming a tear line that breaks when an airbag is deployed are disclosed in, for example, Patent Document 1.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, according to the technique described in Patent Document 1, since the outer part formed by reaction injection molding reproduces the design shape around the airbag only with this outer part, it needs to be made of a relatively rigid material, and there is a possibility that it cannot satisfy the demand for the soft feeling of the interior of automobiles in the market. In addition, although the tear line formed by the hard outer part is considered to have a relatively good appearance, in reality, slight sink marks occur, and further improvement is required from the viewpoint of improving the texture of the interior in recent years.

[0005] Therefore, in view of the above points, the present invention aims to provide a method for manufacturing an airbag lid that forms a foamed urethane layer between the skin and the instrument panel core material to obtain a soft feeling of automotive interior parts and that cannot be confirmed from the appearance even if there are slight sink marks in the instrument panel core material.

Means for Solving the Problems

[0006] Therefore, the present invention relates to a method for manufacturing an airbag lid in which an airbag is disposed inside to protect the passenger in the front seat of a vehicle, When forming the instrument panel core material in the mold of an injection molding machine, a tear line is formed on the back surface of the instrument panel core material that will rupture when the airbag deploys. The aforementioned movable mold with a blade is provided, which has a blade at its tip that is alternately formed with a portion that penetrates into the cavity of the injection molding machine to form a thin wall and a portion that does not penetrate and does not form a thin wall. At the same time as forming the core material of the instrument panel thus formed, a lid body having an opening that can face the tear line formed on the back surface of the instrument panel core material is attached by heat welding. The invention is characterized by setting the outer skin and the instrument panel core material, which has the tear lines formed and the lid body heat-welded, into a mold of a urethane foam molding machine, injecting a urethane foaming agent between the outer skin and the instrument panel core material to form a foamed urethane layer by urethane foam molding, thereby integrating the outer skin and the instrument panel core material. [Effects of the Invention]

[0008] According to the present invention, a foamed urethane layer is formed between the surface material and the instrument panel core material to obtain a soft feel for the interior parts of an automobile, and a method for manufacturing an air bag lid is provided in which even slight shrinkage in the instrument panel core material cannot be seen from the outside. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view of the main part of an injection molding machine in the clamped state. [Figure 2] This is an enlarged view of the main part of Figure 1. [Figure 3] This is a close-up view of the main part of the movable mold with blades in the direction of the arrow. [Figure 4] This is a cross-sectional view of an airbag lid. [Figure 5] This is an enlarged view of the main part of Figure 4. [Figure 6] This is a plan view of the lid body. [Modes for carrying out the invention]

[0010] The method for manufacturing an airbag lid according to the present invention will be described below with reference to Figures 1 to 6. More specifically, the method for manufacturing an airbag lid AL that is released when an airbag 17, which is installed inside a passenger seat of an automobile to protect the passenger occupant, is deployed will be described.

[0011] First, the instrument panel core material (core material that forms the framework of the instrument panel) 3 that constitutes the airbag lid AL is molded in the mold of an injection molding machine. First, based on Figures 1 to 3, we will explain the structure that forms the tear line 8 that ruptures when the airbag 17 is deployed.

[0012] Specifically, the operation of molding the instrument panel core material 3 within the mold of an injection molding machine will be described. Figure 1 is a cross-sectional view of the main part of the injection molding machine in the clamped state, and Figure 2 is an enlarged view of the main part of Figure 1. 1 is the fixed side mold of the injection molding machine, and 2 is the movable side mold. The instrument panel core material 3 is molded by injecting and filling the cavity 6 formed by both molds 1 and 2 in the clamped state with heated and molten synthetic resin material (for example, polypropylene resin material with filler).

[0013] 4 is a movable mold with a blade equipped with a thin blade 5 for forming a tear line 8 (which forms a thin wall) in the instrument panel core material 3. When the heated and molten synthetic resin material is injected and filled, the tip of the blade 5 protrudes into the cavity 6. After the injection and filling as described above, the movable mold with a blade 4 moves in the direction of the arrow (see Figure 3), moving the blade 5 out of the cavity 6, thereby forming the tear line 8, which is a narrow, thin wall section, on the back surface of the molded instrument panel core material 3, for example, with a width of 3 mm or more and 15 mm or less.

[0014] In this embodiment, five movable molds 4 with blades are used, but any number can be used depending on the shape of the opening 11 and the tear line 8, which will be described later. The blades 5 may be a single continuous blade for each movable mold 4 with blades, or multiple blades formed intermittently at intervals of several millimeters. In this way, a perforated tear line is formed, that is, alternating groove portions (several millimeters) that form thin walls and portions without grooves (several millimeters), resulting in a perforated tear line. Furthermore, the shape of the tip of the blade that forms the perforated tear line may be formed so that there are alternating portions that protrude into the cavity 6 to form thin walls and portions that do not protrude and do not form thin walls.

[0015] Generally, if the tear line has a large V-shaped cross-section, there is a risk of deformation when an external force is applied around the tear line. However, in this embodiment, since the tear line 8 is narrow, this problem does not occur.

[0016] Then, after molding, following the movement of the movable mold 4 with the blade, the movable side mold 2 is moved downward to open the mold and remove the molded instrument panel core material 3 from inside the cavity 6.

[0017] 10 is a lid body made of, for example, an orifine-type thermoplastic elastomer that constitutes the air bag lid AL, and the lid body 10, which has a plate portion 10A and a cylindrical portion 10B, is attached to the back surface of the instrument panel core material 3 formed as described above by vibration heat welding so that the tear line 8 can be seen from the opening 11 (slit portion), thereby integrating the instrument panel core material 3 and the lid body 10.

[0018] Then, as shown in FIGS. 4 and 5, the in - panel core material 3 with the skin 12 and the lid body 10 heat - welded thereto is set inside the mold of the urethane foam molding machine, and a urethane foaming agent is injected between the skin 12 and the in - panel core material 3 to form a foamed urethane layer 13 by urethane foam molding, thereby integrating the skin 12 and the in - panel core material 3. Therefore, the air - bag lid AL is composed of the in - panel core material 3, the lid body 10, the skin 12 within the range indicated by the arrow in FIG. 4, and the foamed urethane layer 13.

[0019] In this way, the skin 12 and the in - panel core material 3 are integrated through the foamed urethane layer 13, and an instrument panel 15, which is an interior part of an automobile, is formed. And since the foamed urethane layer 13 is formed between the skin 12 and the in - panel core material 3, a soft feeling of the interior part of the automobile is obtained, and even if there are slight sink marks on the in - panel core material 3, they cannot be confirmed from the appearance, so the appearance is not damaged.

[0020] This instrument panel 15 is provided at the front part of the vehicle compartment of the automobile over substantially the entire vehicle width in the vehicle width direction, and a front windshield glass is arranged above this instrument panel 15. And a part of this instrument panel 15, the air - bag lid AL, is provided with the air - bag 17 disposed inward to protect the passenger in the passenger seat of the vehicle of the automobile. An inflater 19 is arranged at the lower part of a case body 18 attached to the cylindrical parts 10B, 10B of the lid body 10, and the air - bag 17 is folded and stored at the upper part of the case body 18.

[0021] Next, referring to FIG. 6, the lid body 10 located below the in - panel core material 3 will be described. In the plate part 10A of the lid body 10, the area inside the cylindrical part 10B is a planned opening part 20. The planned opening part 20 has an elongated rectangular shape in the left - right (vehicle width direction). First hinge lines 21A, 21A shorter than this long side are formed on a pair of long sides of the planned opening part 20, and second hinge lines 22A, 22B shorter than this short side are formed on the other pair of short sides.

[0022] The opening 11 is provided in the planned opening section 20, allowing a view from below of the tear line 8 (shown by a dashed line), which is a narrow continuous groove formed on the back side of the instrument panel core material 3. This opening 11 consists of a horizontally elongated groove 11A that extends in the horizontal axis direction of the planned opening section 20 and equally divides the planned opening section 20 vertically, and two diagonal grooves 11B and 11C that extend from each end of the horizontally elongated groove 11A, spreading outwards toward the corners of the planned opening section 20.

[0023] At both ends of the horizontally elongated groove 11A of the opening 11, two diagonal grooves 11B are formed in succession. Therefore, as shown in Figure 6, which illustrates the positional relationship between the opening 11 of the lid body 10 and the tear line 8 of the instrument panel core material 3, the tear line 8 visible from the opening is also composed of five sides.

[0024] As shown in Figure 6, the opening section 20 has a pair of roughly trapezoidal first door sections 24A and 24B, and a pair of roughly triangular second door sections 25A and 25B. Each of the upper first door sections 24A is demarcated by the upper first hinge line 21A, the horizontal groove 11A, and the two upper diagonal groove sections 11B and 11C, while each of the lower first door sections 24B is demarcated by the lower first hinge line 21B, the horizontal groove 11A, and the two lower diagonal groove sections 11B and 11C.

[0025] Furthermore, each of the left second door sections 25A is defined by the left second hinge line 22A and the two left diagonal groove sections 11B, 11B, and each of the right second door sections 25B is defined by the right second hinge line 22B and the two right diagonal groove sections 11C, 11C.

[0026] In Figure 6, the tear line 8 is shown as a dashed line to indicate the positional relationship between the tear line 8 and the opening 11. This tear line 8 is formed on the back surface of the instrument panel core material 3 located above the lid body 10, and the opening 11, which overlooks this tear line 8, is provided in the lid body 10.

[0027] Next, the operation of the airbag lid AL will be explained. When the airbag 17 deploys during a vehicle collision and hits the opening portion 20 of the lid body 10, the pressure from the airbag 17 causes the base of the opening 11 of the lid body 10 to tear, and the tear line 8 on the back surface of the instrument panel core material 3 to tear. At the same time, the surface 12 and the foamed urethane layer 13 at the position corresponding to the tear line 8 also tear.

[0028] Furthermore, since the tear line 8 on the back surface of the instrument panel core material 3 is formed by the blade 5, which is a thin blade, it does not become a wide, large, thin-walled shape, and the stress concentration effect necessary for the deployment of the airbag 17 can be obtained without losing rigidity.

[0029] In this case, the first door sections 24A, 24B and the second door sections 25A, 25B rotate upward around the first hinge lines 21A, 21B and the second hinge lines 22A, 22B, causing the opening section 20 to open and the instrument panel core material 3, the surface material 12, and the foamed urethane layer 13 to tear, thereby allowing the airbag 17 to pass upward and inflate into the passenger compartment. Consequently, the airbag 17, once deployed and inflated into the passenger compartment, can protect the passenger in the front seat of the vehicle.

[0030] As described above, embodiments of the present invention have been explained, but based on the above description, various alternatives, modifications, or variations are possible for those skilled in the art, and the present invention encompasses the aforementioned various alternatives, modifications, or variations without departing from its spirit. [Explanation of symbols]

[0031] AL Airbag Lid 3. Instrument panel core material 4. Movable mold with blades 5 blades 8 Tier Lines 10 Lid Body 11 Opening 12 Epidermis 13. Polyurethane foam layer 17 Airbags

Claims

[Claim 1] In a method for manufacturing an airbag lid in which an airbag is installed inside to protect the passenger in the front seat of a vehicle, When forming the instrument panel core material in the mold of an injection molding machine, a tear line that will break when the airbag deploys is formed on the back surface of the instrument panel core material using a movable mold with a blade, which is a thin blade with alternating portions at its tip that protrude into the cavity of the injection molding machine to form a thin wall and portions that do not protrude and do not form a thin wall. A lid body having an opening that can face the tear line formed on the back surface of the instrument panel core material formed in this way is attached by heat welding. A method for manufacturing an air bag lid, characterized by setting the outer skin and the instrument panel core material, which has the tear lines formed and the lid body heat-welded, into a mold of a urethane foam molding machine, injecting a urethane foaming agent between the outer skin and the instrument panel core material to form a foamed urethane layer by urethane foam molding, thereby integrating the outer skin and the instrument panel core material.

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