Molding method

Abstract

To provide a molding method that is effective in improving a surface quality of a design surface of an interior panel for a vehicle equipped with an air bag door.SOLUTION: A molding method for molding an interior panel for a vehicle equipped with an airbag door includes: a cavity formation step S101 in which a cavity S is formed using a first mold 10, a second mold 20, and an insert 30 having a sharp part shaped to correspond to a fracture groove of the airbag door; a resin filling step S102 in which a resin material M is injected to fill the cavity S formed in the cavity formation step; and a gas injection step S103 in which a gas G is injected into the cavity S so as to release only a back side of the interior panel during a molding process of the interior panel by the resin filling step.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a molding method. [Background technology]

[0002] Patent Document 1 below discloses a method for molding an airbag door. This airbag door molding method is a method for molding an interior panel for a vehicle equipped with an airbag door. The interior panel is molded by injecting and filling a resin material into a gap (cavity) defined by a first mold body and a second mold body. A fracture groove is formed on the rear side of the interior panel by a fracture groove forming core. The airbag door of the interior panel breaks open at the fracture groove when the airbag inflates and deploys. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-1677 Summary of the Invention [Problem to be solved by the invention]

[0004] Some interior panels are known in which the surface is left as a design surface without being covered with a covering material such as a skin. When such interior panels are molded using the airbag door molding method described in Patent Document 1, a sudden change in thickness during molding can cause internal pressure differences within the thickness of the panel, resulting in distortion on the surface (design surface) of the interior panel, which can lead to a problem of reduced surface quality of the design surface of the interior panel. Therefore, when molding this type of interior panel, a molding technique that can prevent a reduction in the surface quality of the design surface of the interior panel is effective. While it is possible to use a method of forming a fracture groove in the interior panel by post-processing using a tool such as an end mill, this method is disadvantageous in that it requires costs for post-processing work and equipment.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to provide a molding method that is effective in improving the surface quality of the design surface of an interior panel for a vehicle equipped with an airbag door. [Means for solving the problem]

[0006] One aspect of the present invention is A molding method for molding an interior panel for a vehicle equipped with an airbag door, comprising: a cavity forming step of forming a cavity using a first mold, a second mold, and a core having a sharpened shape corresponding to the breaking groove of the airbag door; a resin filling step of injecting and filling a resin material into the cavity formed in the cavity forming step; a gas injection step of injecting gas into the cavity so as to release only the back surface side of the interior panel during the molding process of the interior panel by the resin filling step; a molding method comprising: is located. [Effects of the Invention]

[0007] In the molding method of the above aspect, first, in the cavity forming step, a cavity is formed in advance using a first mold, a second mold, and a core having a sharpened portion. Next, in the resin filling step, a resin material is injected and filled into the cavity. As a result, an interior panel having a shape corresponding to the shape of the cavity is molded from the resin material. At this time, a fracture groove having a shape corresponding to the sharpened portion of the core is formed on the back side of the interior panel.

[0008] During the gas injection process, gas is injected into the cavity during the molding process of the interior panel to release only the back side of the interior panel. Because only the back side of the interior panel is released and not the front side, distortion due to resin shrinkage is concentrated around the fracture groove, which is the thin-walled portion of the back side of the interior panel. This suppresses distortion on the front side of the interior panel and reduces transfer unevenness from the molding surface of the mold, preventing a decrease in the surface quality of the interior panel and ensuring the desired surface quality. As a result, the surface of the interior panel can be used as a design surface without being covered with a covering material such as a skin.

[0009] According to the above-described aspect, it is possible to provide a molding method that is effective in improving the surface quality of the decorative surface of an interior panel. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a view of an instrument panel of a vehicle according to a first embodiment, viewed from the cabin side. [Figure 2] FIG. 2 is a plan view of the interior panel of the first embodiment as viewed from the back side. [Figure 3] 3 is a cross-sectional view of the molding device of FIG. 2 taken along line III-III. [Figure 4] FIG. 3 is a plan view of a second mold that constitutes the molding apparatus of the first embodiment. [Figure 5] 5 is a cross-sectional view of the second mold of the molding device of FIG. 4 taken along line VV. [Figure 6] 6 is an enlarged cross-sectional view showing the periphery of a insert in the molding device of FIG. 5. [Figure 7] FIG. 2 is a flowchart of the interior panel molding method according to the first embodiment. [Figure 8] FIG. 8 is a cross-sectional view of the molding device in the first step of FIG. 7. [Figure 9] FIG. 8 is a cross-sectional view of the molding device in the second step of FIG. 7; [Figure 10] FIG. 8 is a cross-sectional view of the molding device in the third step of FIG. 7; [Figure 11] 11 is an enlarged cross-sectional view showing the periphery of the insert of the molding device of FIG. 10. [Figure 12]FIG. 12 is a cross-sectional view of a molding apparatus according to a second embodiment, corresponding to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the above aspects are described below.

[0012] In the molding method of the above-described aspect, when either the first mold or the second mold is used as a mother mold, the core is provided in a nest fitted into the mother mold, and a gap for gas injection communicating with the cavity is provided between the nest and the mother mold, and in the gas injection process, gas is preferably injected into the cavity through the gap so that the back side of the interior panel peels off from both the nest and the mother mold.

[0013] According to this molding method, in the gas injection step, gas can be injected into the cavity with a simple structure that utilizes a gap for gas injection provided between the insert and the matrix, and the back side of the interior panel can be peeled off from both the insert and the matrix. Furthermore, using the gap between the insert and the matrix is ​​effective for injecting gas into the back side of the interior panel, particularly around the fracture groove.

[0014] In the molding method of the above aspect, it is preferable that the master mold has a gas supply passage communicating with the gap, and that in the gas injection step, the gas is supplied to the gap from the gas supply passage of the master mold.

[0015] According to this molding method, the structure for supplying gas to the gap between the insert and the matrix can be simplified by providing the matrix itself with a gas supply path that communicates with the gap.

[0016] In the molding method of the above aspect, it is preferable that the gap has a constricted portion whose opening area on the cavity side is narrowed so as to allow the gas to flow but to prevent the resin material from flowing in from the cavity.

[0017] According to this molding method, a simple structure in which a constriction portion is provided in the gap makes it possible to prevent the resin material from flowing from the cavity into the gap while maintaining the injection of gas into the cavity.

[0018] Hereinafter, more specific embodiments of the above-mentioned aspects will be described with reference to the drawings.

[0019] In the drawings used to explain this specification, unless otherwise specified, the arrow UP indicates the upper side of the vehicle and the arrow IN indicates the inner side of the vehicle. Furthermore, with regard to the interior panel and its molding process, the first and second directions, which are perpendicular to each other and run along the surface of the airbag door, are indicated by the arrows X and Y, respectively, and the third direction, which is the thickness direction of the airbag door, is indicated by the arrow Z.

[0020] (Embodiment 1) 1 is a panel of the instrument panel that is disposed to face the passenger seat of the vehicle. In the following description, the surface of the interior panel 1 facing the passenger compartment 4 is defined as the front surface (design surface) 1a, and the surface opposite the passenger compartment 4 is defined as the back surface 1b.

[0021] 1. Structure of interior panel 1 As shown in FIG. 1, an interior panel 1 is an interior panel for a vehicle that includes an airbag door 2. The airbag door 2 is a door portion that opens toward the passenger compartment 4 when an airbag 5 is inflated and deployed, allowing the airbag 5 to inflate and deploy. This interior panel 1 is made of a hard resin material and is also called a "hard instrument panel." Although not shown, the airbag 5 is formed into a bag shape by sewing together multiple pieces of flexible base fabric, and is housed in a retainer provided on the back surface 1b of the interior panel 1 in a pre-folded state. This airbag 5 receives gas from an inflator and inflates, unfolding and deploying as it is released from its folded state.

[0022] 2, a plurality of breaking grooves 3 for opening the airbag door 2 are provided on the rear surface 1b side of the interior panel 1. The plurality of breaking grooves 3 form tear lines that tear open the area of ​​the interior panel 1 around the airbag door 2 due to the load generated when the airbag 5 inflates and deploys.

[0023] As shown in FIG. 3 , in this embodiment, no skin (not shown) is bonded to the surface 1a of the interior panel 1. Therefore, the surface 1a of the interior panel 1 is the design surface exposed to the vehicle interior 4. The portion of the interior panel 1 where the fracture groove 3 is provided is a thin-walled portion having a smaller plate thickness (dimension in the third direction Z) than other portions. The fracture groove 3 is configured as a V-groove having a substantially V-shape in which the groove width dimension of the groove cross section in the first direction X gradually increases from the bottom surface 3a toward the groove opening 3b. Forming the fracture groove 3 into a V-groove is effective in ensuring the fracture position accuracy of the airbag door 2 and also in ensuring the rigidity of the mold that imparts the V-groove shape to the airbag door 2. Meanwhile, the fracture groove 3 is not limited to a V-groove and may be changed to a rectangular groove or the like as needed.

[0024] 2. Structure of molding device 101 As shown in FIGS. 4 and 5, the molding apparatus 101 includes a first mold 10, a second mold 20, and a insert 30. The first mold 10 is a fixed mold, and the second mold 20 is a movable mold that is movable in the third direction Z relative to the first mold 10. The first mold 10 has a molding surface 11 for molding the front surface 1a of the interior panel 1, and the second mold 20 has a molding surface 21 for molding the back surface 1b of the interior panel 1 (see FIG. 5). The insert 30 is a core having a sharp portion 31 shaped to correspond to the breaking groove 3 of the airbag door 2. The second mold 20 is a mother mold into which the insert 30 is fitted. A cavity S (molding space) described below is formed by the two molds 10 and 20 and the insert 30. The number of molds forming the cavity S may be increased as necessary.

[0025] In this embodiment, the two inserts 30 each extend annularly in a plan view seen from the third direction Z, and the two inserts 30 are fitted into the second mold 20 at positions adjacent to each other (see FIG. 4). The inserts 30 include a portion extending in the first direction X and a portion extending in the second direction Y. Note that a structure in which the two inserts 30 are integrated may also be employed.

[0026] 5, the sharpened portion 31 of the insert 30 is provided so as to protrude from the molding surface 21 of the second mold 20. The second mold 20 is provided with a gas supply path 22 connected to a supply source of gas G (not shown). The gas supply path 22 communicates with the boundary portion between the insert 30 and the second mold 20. The type of gas G is not particularly limited, but it is preferable to use air as the gas G, as it can be easily obtained.

[0027] 6, a gap 23 for gas injection that communicates with the cavity S is provided at the boundary between the insert 30 and the second mold 20. The gap 23 is interposed between the gas supply path 22 and the cavity S, communicates with the gas supply path 22, and opens at the molding surface 21 of the second mold 20. Therefore, gas G that is supplied to the gas supply path 22 when the cavity S is formed flows through the gap 23 between the insert 30 and the second mold 20 to the molding surface 21 and is injected into the cavity S.

[0028] The gap 23 has a narrowed portion 23a on the molding surface 21 side of the second mold 20. The narrowed portion 23a is a portion where the opening area on the cavity S side is narrowed so as to allow the gas G to flow and to prevent the inflow of resin material from the cavity S. In other words, the gap 23 is configured so that the flow path cross-sectional area on the molding surface 21 of the second mold 20 is the smallest compared to the flow path cross-sectional area of ​​other portions.

[0029] According to this configuration, with the simple structure of providing the throttle portion 23a in the gap 23, it is possible to maintain the injection of the gas G into the cavity S while preventing the resin material from flowing from the cavity S into the gap 23. Note that instead of providing the throttle portion 23a in the gap 23, a separate structure for preventing the resin material from flowing into the gap 23 may be added.

[0030] 3. Molding method of interior panel 1 Next, a method for forming the interior panel 1 will be described with reference to Figures 7 to 11. The interior panel 1 is formed, for example, by using the forming device 101 configured as described above and sequentially performing steps S101 to S105 in the flowchart shown in Figure 7. If necessary, another step may be added to these steps, or at least one step may be divided into multiple steps.

[0031] The molding of the interior panel 1 is completed by filling the cavity S with molten resin material and then cooling and hardening it. Therefore, during the molding process of the interior panel 1, there exists a molded body that has a shape corresponding to the interior panel 1 but is not completely solidified. For convenience, hereinafter, the interior panel 1 after molding is complete, as well as the molded body during the molding process of the interior panel 1, will be described as the "interior panel 1."

[0032] The first step S101 in Fig. 7 is a cavity forming process in which a cavity S is formed using the first mold 10, the second mold 20, and the insert 30. In this first step S101, as shown in Fig. 8, the molds 10, 20 are clamped together to position their molding surfaces 11, 21 facing each other. This forms the cavity S for molding the interior panel 1. At this time, the sharpened portion 31 of the insert 30 is exposed to the cavity S.

[0033] The second step S102 in FIG. 7 is a resin filling step in which the cavity S formed in the first step S101 is filled with resin material M by injection. In this second step S102, as shown in FIG. 9, the resin material M is injected into the cavity S so as to fill the entire cavity S with the molten resin material M. After the entire cavity S is filled with the resin material M, a pressure-holding process is performed in which the gate (not shown) is sealed at a constant pressure to prevent the resin material M from flowing back from the gate. This results in the molding of the interior panel 1. At this time, the sharp tip 31 of the insert 30 forms the breaking groove 3 of the airbag door 2 on the rear surface 1b side of the interior panel 1 (see FIG. 4).

[0034] 7 is a gas injection step in which gas G is injected into the cavity S so as to release only the rear surface 1b of the interior panel 1 before it is cooled and hardened during the molding process of the interior panel 1 in the second step S102. In this third step S103, as shown in FIG. 10, gas G is supplied to the gas supply path 22 of the second mold 20 during the molding process of the interior panel 1. Then, as shown in FIG. 11, a gas flow of gas G in the flow direction D toward the cavity S is formed in the gap 23 communicating with the gas supply path 22. As a result, the gas G is injected into the cavity S upward toward the rear surface 1b of the interior panel 1.

[0035] The gas G injected into the cavity S acts directly on the back surface 1b of the interior panel 1, pushing up the interior panel 1. As a result, only the back surface 1b of the interior panel 1 is separated from both the second mold 20 and the insert 30, and an injection space Sa into which the gas G is injected is formed between the back surface 1b of the interior panel 1 and the molding surface 21. Meanwhile, the front surface 1a of the interior panel 1 is maintained in contact with the molding surface 11 of the first mold 10. The injection conditions for the gas G, such as the pressure and flow rate, are preferably set in advance to conditions that will produce the desired effect based on tests conducted in advance.

[0036] When only the back surface 1b side of the interior panel 1 is released from the mold, stress (strain force) F occurs within the thickness of the panel due to resin shrinkage of the interior panel 1. This stress F causes strain to concentrate on the back surface 1b side of the interior panel 1. In particular, the thin-walled portion around the fracture groove 3 is more susceptible to the influence of stress F than other areas. In contrast, the front surface 1a side of the interior panel 1 does not release from the mold, maintaining a state in which strain concentration is suppressed.

[0037] 7 is a cooling step for cooling the two molds 10, 20. In this fourth step S104, the molds 10, 20 may be cooled from the outside by a cooling device, or may be cooled by a refrigerant flowing through a refrigerant flow path formed inside the molds 10, 20, or the molds 10, 20 may be cooled naturally. According to this fourth step S104, the interior panel 1 is formed in the cavity S by cooling and hardening the resin material M.

[0038] The fifth step S105 in FIG. 7 is a removal step in which the molds 10 and 20 are opened and the interior panel 1 is removed from the cavity S.

[0039] 4. Effects According to the first embodiment, the following effects are achieved.

[0040] In the molding method of embodiment 1, first, in a first step (cavity forming step) S101, a cavity S is formed in advance using a first mold 10, a second mold 20, and a insert 30 having a sharpened portion 31. Next, in a second step (resin filling step) S102, a resin material M is injected and filled into the cavity S. As a result, an interior panel 1 having a shape corresponding to the shape of the cavity S is molded from the resin material M. At this time, a fracture groove 3 having a shape corresponding to the sharpened portion 31 of the insert 30 is provided on the rear surface 1b side of the interior panel 1.

[0041] In the third step (gas injection step) S103, gas is injected into the cavity S so as to release only the back surface 1b of the interior panel 1 during the molding process of the interior panel 1. At this time, only the back surface 1b of the interior panel 1 is released without releasing the front surface 1a of the interior panel 1, so distortion due to resin shrinkage is concentrated around the fracture groove 3, which is a thin portion of the back surface 1b of the interior panel 1. This suppresses distortion on the front surface 1a of the interior panel 1 and reduces transfer unevenness from the molding surface 11 of the first mold 10, preventing a decrease in the surface quality of the front surface 1a of the interior panel 1 and ensuring the desired surface quality. As a result, the front surface 1a of the interior panel 1 can be used as is as a design surface without being covered with a covering material such as a skin.

[0042] Therefore, according to the above-described first embodiment, it is possible to provide a molding method that is effective in improving the surface quality of the design surface of the interior panel 1.

[0043] The above molding method has the advantage that, compared to a method in which a fracture groove 3 is formed in the interior panel 1 by post-processing using a tool such as an end mill, no costs (equipment costs and energy costs) are incurred for the work and equipment required for post-processing.

[0044] According to the above molding method, in the third step (gas injection process) S103, gas G can be injected into the cavity S with a simple structure that utilizes the gap 23 for gas injection provided between the insert 30 and the second mold 20, and the back surface 1b side of the interior panel 1 can be peeled off from both the insert 30 and the second mold 20. Furthermore, using the gap 23 between the insert 30 and the second mold 20 is effective for injecting gas G into the back surface 1b side of the interior panel 1, particularly around the fracture groove 3. Furthermore, by providing the gas supply path 22 that communicates with the gap 23 in the second mold 20 itself, the structure for supplying gas G to the gap 23 can be simplified.

[0045] Hereinafter, other embodiments related to the above-described embodiment 1 will be described with reference to the drawings. In the other embodiments, the same elements as those in embodiment 1 are denoted by the same reference numerals, and the description of the same elements will be omitted.

[0046] (Embodiment 2) As shown in Figure 12, the molding apparatus 102 of embodiment 2 differs from the molding apparatus 101 of embodiment 1 in that the insert 30 has a gas injection path 24 for injecting gas. The gas injection path 24 is formed to penetrate the insert 30 along the third direction Z and communicates with the gas supply path 22. The gas injection path 24 is provided in place of the gap 23 of embodiment 1, communicates with the gas supply path 22, and opens at the molding surface 21 of the second mold 20. The gas injection path 24 also has a throttling portion 24a similar to the throttling portion 23a of the gap 23 (see Figure 11).

[0047] The other configurations and molding methods are the same as those in the first embodiment.

[0048] According to the second embodiment, it is possible to inject the gas G through the gas injection passage 24 provided in the insert 30 into a position close to the fracture groove 3 on the rear surface 1b side of the interior panel 1.

[0049] In addition, the same effects as those of the first embodiment are achieved.

[0050] In a modification of the second embodiment, the gap 23 and the gas injection path 24 may be used in combination to inject gas into the cavity S. Furthermore, instead of or in addition to the gap 23 and the gas injection path 24, a gas injection path may be formed penetrating the second mold 20 itself along the third direction Z, and this gas injection path may be used instead of or in addition to the gap 23 and the gas injection path 24.

[0051] The present invention is not limited to the exemplary embodiments described above, and various applications and modifications are possible without departing from the scope of the present invention. For example, the following embodiments can be implemented by applying the above embodiments.

[0052] In the above embodiment, an example is given of injecting gas into the cavity S through the gap 23 or gas injection path 24 formed using the second mold 20 or the nest 30, but instead, gas may be injected into the cavity S using a member other than the second mold 20 or the nest 30 (for example, a tubular member, etc.).

[0053] In the above embodiment, the second mold 20 is used as the matrix for the insert 30, but instead, the first mold 10 may be used as the matrix for the insert 30.

[0054] In the above embodiment, a molding method for an interior panel 1 provided in a portion facing the passenger seat of a vehicle has been exemplified, but this molding method can also be applied to a molding method for other interior panels equipped with airbag doors. [Explanation of symbols]

[0055] 1...interior panel, 1b...rear surface, 2...airbag door, 3...fracture groove, 10...first mold, 20...second mold (mother mold), 22...gas supply path, 23...gap, 23a...drawing portion, 30...insertion (core), 31...sharp portion, G...gas, S...cavity, S101...first step (cavity formation process), S102...second step (resin filling process), S103...third step (gas injection process)

Claims

1. A molding method for molding an interior panel for a vehicle equipped with an airbag door, comprising: a cavity forming step of forming a cavity using a first mold, a second mold, and a core having a sharp portion shaped to correspond to the breaking groove of the airbag door; a resin filling step of injecting and filling a resin material into the cavity formed in the cavity forming step; a gas injection step of injecting gas into the cavity so as to release only the back surface side of the interior panel during the molding process of the interior panel by the resin filling step; A molding method comprising the steps of:

2. when either the first mold or the second mold is used as a mother mold, the core is a nest fitted into the mother mold, and a gap for gas injection communicating with the cavity is provided between the nest and the mother mold; The molding method according to claim 1 , wherein in the gas injection step, gas is injected into the cavity through the gap so that the back surface side of the interior panel is peeled off from both the insert and the matrix.

3. a gas supply path communicating with the gap is provided in the matrix; The molding method according to claim 2 , wherein in the gas injection step, the gas is supplied to the gap from the gas supply passage of the matrix.

4. 4. The molding method according to claim 2, wherein the gap has a constricted portion whose opening area on the cavity side is constricted so as to allow the gas to flow but to prevent the resin material from flowing in from the cavity.

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