JP2003094489A - Mold for injection molding and method for molding air gag door using the mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for injection molding for molding an air bag door integrally with an instrument panel without causing the lack of a wall while keeping proper connection strength to a panel main body and a method for molding the air bag door using the mold. SOLUTION: In the mold for injection molding, the first and second mold bodies 3 and 4 for regulating a cavity to be filled with a resin material and a core 7 for forming a break part which is formed in the second mold body 4 and can move in relation to the first mold body 3 are provided, and the tip of the core 7 has a plurality of blades 7a protruding in the direction of the first mold body 3 from the second mold body 4 so that the depth of the break part formed by the core 7 is changed in the elongation direction of the break part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die for use in integrally molding an airbag door with an instrument panel, and an airbag door molding method using the same. .

[0002]

2. Description of the Related Art In recent years, high-speed moving vehicles such as automobiles have
An airbag system is often installed for the purpose of ensuring the safety of passengers. The airbag system, when a vehicle is impacted in a collision accident,
A device for absorbing the transmission of the impact to an occupant, which is generally a sensor that detects an impact on a vehicle and determines the degree of the impact and sends an operation signal, and a required signal based on the operation signal. It is composed of a gas generator that generates gas and an airbag that inflates and deploys by the gas from the gas generator to protect an occupant.
An airbag that inflates and deploys when the airbag system is activated is normally folded and stored at a predetermined position when the airbag system is not activated. For example, a passenger airbag in an automobile airbag system is housed inside an instrument panel. Therefore, the instrument panel in which the airbag is housed has an opening for allowing the airbag to bulge toward the occupant in the event of system operation emergency, and the opening for closing the system in normal operation. An airbag cover body or an airbag door for opening the opening when the system is operated is required.

FIG. 18 is a perspective view of an instrument panel 100 provided with an air bag door 101 formed by resin molding as a separate body by a conventional method, and FIG. 19 is a perspective view of the instrument panel 100 shown in FIG. It is a partial cross-section enlarged perspective view of the installation location of the airbag door 101. The cross-sectional shape shown in FIG. 19 is line XIX--
It corresponds to the cross-sectional shape along XIX.

In forming an air bag door on an instrument panel, the instrument panel 1 is conventionally used.
00 and the airbag door 101 are molded separately from each other and then mounted on the instrument panel 100 so that the airbag door 101 closes the airbag opening 102. However, when the airbag door 101 as a separate member is attached to the instrument panel 100, as shown in FIG. 19, the airbag door 101 and the panel body are separated from each other on the outer surface or the design surface of the instrument panel 100. A gap or step 103 is formed at the boundary of As shown in FIG. 18, such a gap or stepped portion 103 is not preferable because it affects the external appearance configuration of the instrument panel where aesthetics are emphasized. There is also a problem that dust easily collects in such a gap or step 103. In addition, in such a conventional configuration, an air bag door molding process independent of the molding of the panel body, a mold for the same, and the like are separately required, which makes the manufacturing process of the instrument panel complicated. Was there.

For example, JP-A-11-291069, JP-A-6-143327 and JP-A-2000.
Japanese Patent Laid-Open No. 108833 discloses a technique for integrally molding an airbag door and an instrument panel in order to solve the above-mentioned problems based on separate molding of an airbag door.

Specifically, according to Japanese Patent Laid-Open No. 11-291069, after the instrument panel body is injection-molded without providing an airbag opening, a predetermined portion corresponding to the airbag storage position on the back surface of the panel. By shaving the laser with a laser, a fractured portion is formed. Here, the rupture portion is formed to rupture when the airbag system receives an inflation force when the airbag system is activated, so that a predetermined portion of the instrument panel corresponding to the airbag storage position, that is, an airbag door can be ruptured. The vulnerable part. By forming such a broken portion in the instrument panel, the airbag door defined by the broken portion is formed integrally with the instrument panel.

On the other hand, according to JP-A-6-143327 and JP-A-2000-108833, the instrument panel mold is clamped so that a desired break is formed on the back side of the instrument panel. The fractured part forming core is arranged in advance in the void defined by, and the void is filled with the resin material in this state. Then, when the instrument panel is injection-molded, the airbag door defined by the break portion is integrally molded with the instrument panel.

[0008]

However, in the laser processing method described above, it is relatively difficult to finely adjust the thickness of the fractured portion formed on the instrument panel by laser irradiation, and in particular, the instrument having a single-layer structure is used. When laser processing is performed on the instrument panel, there is a possibility that the instrument panel may be penetrated by excessive laser irradiation. Moreover, if the laser processing method is adopted,
In addition to the injection molding process of the instrument panel, a complicated laser processing machine is required, resulting in a decrease in manufacturing efficiency of the instrument panel.

On the other hand, in the method of preliminarily disposing the fracture portion forming core at the time of injection of the resin material, the core has a fracture portion or a thin portion formed in the instrument panel, so that the core is smaller than other die portions. Since it is arranged so as to project into the void, it becomes an obstacle to the resin material flowing in the void. Then, it becomes difficult to supply a sufficient amount of resin to the region sandwiched between the cores or the enclosed region, that is, the airbag door forming region. As a result, there is a problem of so-called wall-thickness that a part or the whole of the airbag door integrally formed with the instrument panel becomes thinner than a desired wall thickness.

Further, in the technique of forming a fractured portion or a thin portion on an instrument panel using a core, the fractured portion usually has a uniform thickness, but the fractured portion has a wall thickness of 0.1, for example. When provided with a uniform thickness of up to 1.0 mm, it is difficult to properly secure the strength of the fractured part. For example, in the low temperature impact evaluation and instrument panel head impact evaluation, such a fractured portion tends to be easily fractured. As a result, in the instrument panel integrally formed with the airbag door, there may be a case where sufficient non-breakability cannot be ensured.

The present invention was devised under such circumstances, and an object thereof is to solve or reduce the above-mentioned problems, and to maintain an appropriate connection strength to a panel body. (EN) Provided are an injection molding die that can be used when integrally forming an airbag door that does not have a wall thickness in an instrument panel, and an airbag door molding method using the same. To aim.

[0012]

DISCLOSURE OF THE INVENTION According to a first aspect of the present invention, an injection mold is provided. The mold is provided on the first mold body and the second mold body for defining the space filled with the resin material, and the second mold body, and is movable back and forth with respect to the first mold body. And a core for forming a rupture portion, wherein the core changes from the second mold body to the first mold body so that the depth of the rupture portion formed by the core changes in the rupture portion extending direction. It is characterized by having a plurality of protruding blades protruding in the direction.

When the mold having such a structure is used, it is possible to avoid or sufficiently suppress the occurrence of wall thickness in the airbag door when the airbag door is integrally molded with the instrument panel, for example. . Specifically, in the injection molding using the mold according to the first aspect of the present invention as an instrument panel mold, in the resin material injection process, the core for forming the fractured part is retracted from the position where the fractured part is formed. It is possible to inject the resin material into the void portion in the state of the above position, and then to displace the fractured portion forming core to the fractured portion forming position during or after the filling of the resin material into the void portion. According to this, the fracture portion forming core does not or hardly disturbs the flow of the resin material in the void portion, and a sufficient amount of resin material is provided in the air bag door forming region defined by the fracture portion forming core in the void portion. Can be supplied. As a result, the occurrence of deficiency in the finished airbag door is avoided, and the airbag door having a desired wall thickness is integrally formed with the instrument panel.

Further, by using the mold according to the first aspect of the present invention, the airbag door can be integrally formed with the instrument panel while maintaining an appropriate connection strength. Specifically, since the core for forming the fracture portion provided in the second mold body has a plurality of blades protruding from the second mold body in the direction of the first mold body, In the break portion formed in the instrument panel by pushing the core, a relatively deep portion corresponding to the blade and a relatively not deep portion corresponding to the blade and the blade are formed. Become. With the mold according to the first aspect of the present invention,
By forming a ruptured portion having such an uneven shape, the airbag door can be ruptured when the airbag door swells and has a sufficient strength that it does not break in low temperature impact evaluation and instrument panel head impact evaluation. To
It can be molded integrally with the instrument panel.

Further, by using the mold according to the first aspect of the present invention, the airbag door can be integrally molded with the instrument panel with a good appearance. When the core for forming the fracture portion is displaced to the fracture portion forming position during or after the filling of the resin material as in the above injection molding,
The blade during compression presses the resin material, but the resin material that receives the compressive force can flow out not only in the side direction of the fractured portion but also between the blades along the fractured portion. Therefore, the uniformity of the density of the resin material is ensured before cooling. If the resin density is uniform, the resin material shrinks uniformly in the cooling process, and as a result, an instrument panel with a good appearance is produced without bulging on the design surface at the position where the break is formed. It becomes possible.

If the fractured part forming core has a tip shape with a uniform height instead of the plurality of projecting blades, the tip of the core and the first of the resin materials filled in the gap are formed. The resin material sandwiched between the mold body and the mold body is in a state of being pressed more than the resin existing in the other regions due to the displacement of the core to the break portion forming position. This is because the resin material is partially extruded toward the side of the fractured portion due to the indentation of the core, but the extent of extrusion is not sufficient. In the cooling step after the resin material injection step, when the resin material radiates heat and shrinks, the resin material in a compressed state between the tip of the core and the first mold body is a resin existing in another portion. Apparently in the thickness direction of the material rather than the material
It will shrink at a small shrinkage rate. That is, the resin material existing in other parts shrinks more in the cooling process. Therefore, in the final molded product obtained as a result of shrinking at different shrinkage rates in the member thickness direction, the fractured part or thin part that connects the panel body and the airbag door has a bulged shape on the design surface of the instrument panel, Will affect the aesthetics of. On the other hand, the mold according to the first aspect of the present invention is a molded product obtained after cooling is completed by eliminating or reducing the local compression state at the fractured portion, and thus the outside of the panel body and the airbag door is removed. It is possible to form a surface in which the surfaces are connected flush with each other.

According to a second aspect of the present invention, there is provided a method of integrally molding an airbag door on an instrument panel. This molding method includes a step of bringing a first mold body and a second mold body close to each other to perform mold clamping, and a first mold body and a second mold body.
In the step of injecting the resin material into the void defined by the mold body and in the process from the injection of the resin material to the solidification of the resin material, the second mold body is provided with the first mold body. The step of displacing the core for forming a fractured part that can move forward and backward toward the first mold body from the retracted position to the fractured part formation position, and the tip of the core has a fractured part formed by the core. Is characterized in that it has a plurality of blades protruding from the second mold body toward the first mold body so that the depth thereof changes in the extending direction of the fracture portion.

According to this structure, the airbag door can be integrally formed with the instrument panel by using the mold according to the first aspect of the present invention. Therefore, according to the second aspect of the present invention as well, the same effect as that described above with respect to the first aspect is achieved.

Resin materials used in the injection molding according to the present invention include styrene resins, polyolefin resins,
A thermoplastic resin such as a polyphenylene ether (PPE) resin can be used. Further, from the viewpoint of reinforcing the resin molded body, the resin material may include an inorganic filler such as glass fiber, carbon fiber, calcium carbonate, talc, or mica.

In the present invention, the core for forming the fractured part is
It has the desired edging shape for airbags,
The tip may be formed in a tapered shape, or may be formed with a flat surface substantially parallel to the void defining surface of the second mold body. Further, in the second aspect of the present invention, preferably, the retracted position of the core is the position where the tip of the core is on the same plane as the void defining surface of the second mold body or retracts from the void defining surface. As long as there is no deficiency in the airbag door of the finished product, it is the position retracted from the fracture formation position, and the tip of the core is located at the first mold body rather than the void defining surface. The position extending toward the core may be the retracted position of the core. When such a configuration is adopted, the length of the core extending from the void defining surface is preferably ½ or less, more preferably ⅕ or less of the thickness of the airbag door. Yes, and more preferably 1/10 or less. When a core having a flat surface substantially parallel to the void defining surface at its tip is used, the position where the flat surface is flush with the void defining surface of the second mold is referred to as the retracted position of the core. By doing so, it is possible to properly prevent the resin material from excessively flowing into the groove portion formed in the second mold body as the sliding portion of the core.

In a preferred embodiment, the core has a retracting blade continuous between the adjacent blades between the adjacent blades.
With such a configuration, in addition to the protruding blades, the retracted portion between the protruding blades can also function as a blade for forming a fractured portion.

In another preferred embodiment, the second mold body has a plurality of through holes that open at the void defining surface, and the protruding blade is slidably provided in the through holes. Preferably, the protruding blades and the through holes corresponding thereto are provided at a linear density of 3 to 10 pieces / cm. With such a configuration, the core is not directly pressed into the resin material existing in the portions corresponding to the blades in the fractured portion formation planned portion in the fractured portion forming step. Therefore, when the protruding blade of the core is pushed into the resin material, the pressed resin material is likely to be pushed out to the region between the protruding blades. As a result, before cooling, the compressed state of the resin material pushed into the blade is eliminated or further reduced, and in the molded product obtained after cooling is completed, the bulge at the position corresponding to the fracture part on the panel design surface is eliminated. Or will be reduced.

When the second mold body has such a through hole, the through hole is preferably a round hole shape. Correspondingly, the protruding blade is a round pin slidable in the round hole through hole. More preferably, such a round pin projecting blade is supported by a support plate connected to a cylinder for driving the core forward and backward, with play that is displaceable in a direction intersecting the forward and backward direction of the core. There is.

With such a structure, it is possible to easily insert the protruding blade into the through hole formed in the second mold body. Specifically, since the through-hole is a round hole, the projecting blade is a round pin, and the supporting plate supports the projecting blade with a play that allows displacement, the projecting blade is manufactured in a die. Strictly aligning the with respect to the through hole is not essential. When the round pin protruding blade attached to the supporting plate with play is inserted into the through hole of the second mold, if the tip of the round pin protruding blade enters the round hole through hole, On the other hand, even if the blade is displaced to some extent, the blade is displaced on the support plate in the direction intersecting the insertion direction within the range permitted by the play, and the blade is automatically aligned. As a result, it becomes easy to manufacture the mold according to the present invention. When performing airbag door integral molding that requires more blades and through holes,
The effect of facilitating the manufacture of such a mold is increased.

In the present invention, preferably, the first mold body is a fixed mold supported and fixed to a fixed mold mounting plate of the injection molding apparatus, and the second mold body is a movable mold mounting plate of the apparatus. It is a movable type that is supported and fixed to and is movable back and forth with respect to the fixed type. And, preferably, the fixed mold is provided with an injection hole which is open on the surface thereof and is continuous with the void, and in the resin material injection step, the resin material in a molten state prepared by an injection device is used. It is injected into the void through this injection hole.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a partial cross-sectional view of an injection molding apparatus equipped with an injection molding die A according to the first embodiment of the present invention. FIG. 1 shows the structure of the airbag door forming region S and its vicinity. Here, the airbag door forming region S is a region corresponding to a portion defined by the fractured portion in the completed instrument panel, that is, a portion functioning as an airbag door.

The injection molding die A is fixed to a fixed die 3 which is fixedly supported by a fixed die mounting plate 1 of an injection molding apparatus, and a movable die mounting plate 2 which can move back and forth with respect to the fixed die mounting plate 1. The movable mold 4 supported is provided. The fixed die 3 is provided with a heater-equipped core 5 at a position corresponding to the airbag door forming region S. The heater-equipped core 5 is fitted into the fixed mold 3 such that its exposed surface is flush with the void defining surface 3 a of the fixed mold 3. The movable die 4 is provided with an airbag door forming mechanism 6 at a position corresponding to the airbag door forming region S.

The airbag door forming mechanism 6 has a core 7 having a peripheral shape corresponding to a desired breaking portion, a core support plate 8 for fixedly supporting the core 7, and a vertical movement of the support plate 8. Hydraulic cylinder 9 of. In order to dispose the airbag door forming mechanism 6, the movable mold 4 has
The core through groove 10, the support plate accommodating chamber 11, and the cylinder accommodating chamber 12 are provided.

FIG. 2 is a sectional view taken along the line II--II in FIG. 1, in which the section in the extending direction of the core 7 is well shown.
As shown in FIG. 2, the core 7 has
A plurality of protruding blades 7a are provided along the extending direction, and a space between adjacent protruding blades 7a is a retracting blade 7b that is continuous with the protruding blade 7a. Therefore, the projecting blade 7a and the retracting blade 7b are provided with the core through groove 10 formed along the shape of the fracture portion to be formed.
To move in and out. In the present embodiment, the protruding blade 7a is
The cross section of the core 7 in the extending direction is rectangular, and the length in the extending direction is 0.5 to 5.0 mm.
As shown in FIG. 1, the projecting blade 7a is tapered in the cross section of the core 7, and its maximum width is 0.5.
It is set to ~ 2.0 mm. Further, the projecting blade 7a and the retracting blade 7b are designed to have the same length.

FIGS. 3 (a) to 3 (d) are partially enlarged sectional views in the core extending direction of another blade in the present invention. Figure 3
The blade 71a shown in (a) has a hexagonal shape,
The retracting blade 71b is designed to be shorter than the one. Figure 3
The protruding blades 72a shown in (b) are wavy and are provided at a constant pitch. The protruding blade 73a shown in FIG.
Have a triangular shape and are provided at a constant pitch. The blades 74a shown in FIG. 3D also have a triangular shape and are provided at a constant pitch. A retracting blade 74b is provided between the adjacent protruding blades 74a.

As shown in FIG. 1, the hydraulic cylinder 9 is fixed in the cylinder accommodating chamber 12 of the fixed die 4 and has a piston rod 9a which can extend and contract. Piston rod 9
a is connected to the support plate 8 in the support plate storage chamber 11. The support plate 8 is expanded and contracted by the piston rod 9a,
It moves up and down in the support plate accommodating chamber 11. When the core 7 supported and fixed to the support plate 8 moves up and down together with the support plate 8, the core 7 is slidable in the core through groove 10 formed corresponding to the shape of the core 7. The core 7 is positioned by the hydraulic cylinder 9 via the support plate 8. In the cross-sectional view of FIG. 1, two cores 7 are apparently shown, but they are connected outside the drawing to form an integral core 7. Further, in order to prevent the movement directions of the core 7 and the support plate 8 from being inclined from the piston expansion / contraction direction, the guide post 13 penetrating the support plate 8 in a direction parallel to the piston expansion / contraction direction is provided with the support plate storage chamber 11 It is fixed to.

Injection mold A shown in FIGS. 1 and 2.
Arranges a mold clamping step in a series of steps for integrally forming an airbag on an instrument panel. In the mold clamping step, the movable mold 4 is integrated with the movable mold mounting plate 2 to approach the fixed mold 3, and is fitted to the fixed mold 3 at a predetermined position (not shown). In a state where the movable die 4 is fitted to the fixed die 3, that is, a mold clamping state, a void portion 14 as a space filled with resin is formed between the two dies. In the present embodiment, the width W of the airbag door forming region S in the void portion 14 is set to 1 to 5 mm. In the mold clamping process,
The core 7 is positioned at the retracted position by the hydraulic cylinder 9 and is in a standby state. In the present embodiment, the retracted position refers to a position where the tip end of the core 7, that is, the upper end of the protruding blade 7a is retracted from the gap defining surface 4a of the movable die 4. At this time, the heater-equipped core 5 is provided with a temperature sensor (not shown) therein, and heats the airbag door forming region S and the mold in the vicinity thereof in a temperature range of 30 to 300 ° C.

FIG. 4 shows a resin material injection step which is performed following the mold clamping step. In this step, the resin material 15 in a molten state is filled in the void portion 14 formed in the mold clamping step. Specifically, the resin material 15 melted by a resin injection device (not shown) is injected from the injection device through an injection hole (not shown) formed in the fixed mold 3 so as to communicate with the void portion,
It is injected into the void 14 with a predetermined pressure. At this time, the core 7 is kept waiting in the retracted position. Therefore, when the resin material 15 passes through the airbag door forming region S in the void portion 14, the tip portion of the core 7, that is, the protruding blade 7a and the retracting blade 7b, does not hinder the flow of the resin material 15, and the airbag Sufficient resin material 15 is supplied to the door forming region S. The heater-equipped core 5 heats the molten resin material 15 that passes through or fills the airbag door forming region S within a temperature range of 100 to 300 ° C., and the resin material 15 is heated before the next fracture portion forming step. It plays a role in preventing solidification.

FIG. 5 shows a fractured part forming step performed after the resin material 15 is filled in the voids 14. In this step, the hydraulic cylinder 9 extends and drives the piston rod 9a to advance the support plate 8 and the core 7 supported and fixed to the support plate 8 from the retracted position to the fracture portion formation position. Here, the rupture portion forming position means a rupture portion which is a boundary between the main body of the instrument panel and the airbag door when the tip portion of the core 7 is pushed into the void portion 14 already filled with the resin material 15. It refers to the position where it is formed. In this step, the blades 7a in the process of pushing in press the resin material 15, but the resin material 15 that has received the pressure is not only in the side direction of the fractured portion but also between the upper blades 7a along the fractured portion. Can also be spilled. The degree of pressing by the retracting blade 7b between the protruding blades 7a is considerably smaller than that of the protruding blades 7a. Therefore, the uniformity of the density of the resin material is ensured before cooling. In the present embodiment, the core 7 at the breaking portion forming position
The distance between the tip of the blade 7a and the core with heater 5 is 0.1
1.5 mm, the tip of the retracting blade 7b and the core 5 with a heater
Is 1.0 to 5.0 mm.

After the core 7 is displaced to the breaking portion forming position, the heater-equipped core 5 stops the heating operation which has been continued until then. Then, the core 7 is made to stand by at the breaking portion forming position until the molten resin material 15 is solidified so as not to lose its shape, and the resin material 15 filled in the voids 14 is held under pressure. The period of this pressure-holding process may be set in advance in the device so that the device automatically moves to the next process after the lapse of the period, or it is provided in the heater-equipped core 5. The space 14 is formed by a temperature sensor (not shown).
The apparatus may be configured to detect the temperature of the resin material 15 filled in the container and automatically move to the next step when the resin material temperature drops to a predetermined temperature.

Further, in the present embodiment, the fracture portion forming step is started after the resin material 15 is completely filled in the void portion 14. However, even before the resin material 15 is completely filled, the void portion 14 is not filled with the resin material 15. After passing through the air bag door forming region S in the portion 14, the core 7 is made into the resin material 1 in the void portion 14.
You may push in to 5. Even if the fractured portion forming step is performed at such a timing, the resin material 15 has already been sufficiently supplied to the airbag door forming region S, so that the molded airbag door is free from wall thickness. Further, since the resin material 15 can flow into the voids 14 other than the region S by bypassing the core 7 displaced to the breaking portion forming position, the problem of lack of wall is avoided also in other regions of the instrument panel. To be done.

FIG. 6 shows a core retreating step which is performed subsequent to the pressure holding step of the fracture portion forming step. In this step, the hydraulic cylinder 9 drives the piston rod 9a in a shortened manner to retract the support plate 8 and the core 7 supported and fixed to the support plate 8 from the break portion forming position to the retracted position. After this step, the core 7 is made to stand by at the retracted position and cooled until the resin material 15 in the void portion 14 is sufficiently solidified.
In the cooling step, the resin material gradually shrinks at a uniform shrinkage rate, and in the final solidified state, the resin material is separated from the fixed mold 3 or the heater-equipped core 5. As the cooling means, natural cooling may be used, or the fixed die 3 and / or the movable die 4 may be provided with a cooling mechanism (not shown) such as an air cooling type or a water cooling type. After the cooling step, the movable mold mounting plate 2 is driven to separate the movable mold 4 from the fixed mold 3 to open the mold, and the molded instrument panel is taken out.

FIG. 7 shows the airbag door 3 integrally formed with the instrument panel 30 by the series of steps described above.
It is a partial cross-sectional perspective view of FIG. According to the present invention, by forming a groove on the back surface side of the instrument panel 30, a broken portion 32 having a shape shown by a broken line and thinner than other portions is formed. The region defined by the broken portion 32 is integrally formed with the instrument panel as the airbag door 31. The shape of the portion of the airbag door 31 not shown is assumed to be substantially symmetrical to the shape of the portion shown with the cross section as a plane of symmetry.

The airbag door 31 has a sufficient wall thickness that substantially corresponds to the void portion 14 at the time of injection molding, and a thin wall portion is not formed. Therefore, when a pressing force is applied from the airbag that is inflated and deployed during system operation, only the breakage portion 32 indicated by the broken line can be appropriately broken. Further, since the airbag door 31 is integrally formed with the instrument panel 30, no gap or step is formed on the design surface of the panel 30. Then, the breaking portion 3 that defines the airbag door 31.
No. 2 does not bulge on the outer surface or the design surface (the upper surface in the drawing) of the instrument panel 30, and on the design surface side, the airbag door 31 and the panel body are flush with each other. Therefore, the appearance of the instrument panel 30 is not affected or restricted by the presence of the airbag door 31, and the aesthetic appearance of the instrument panel 30 is not impaired.

FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 7, in which the sectional shape in the extending direction of the fractured portion 32 is well shown. The breakage portion 32 includes the first thin portion 32a and the second thin portion 32a.
It is composed of a thin portion 32b, and unevenness is provided in the member thickness. Such a concavo-convex shape substantially corresponds to the continuous repeating shape of the projecting blade 7a and the retracting blade 7b in the core 7.

The instrument panel 30 integrally formed with the airbag door 31 was subjected to low temperature impact evaluation. Specifically, after cooling the panel 30 at −30 ° C. for 3 hours or more, a 1 kg steel ball was dropped at the center of the airbag door 31 at the same temperature. When the steel ball drop height was gradually increased, cracks occurred at the steel ball drop point in the airbag door 31 for the first time at a predetermined height.
Did not break. That is, the breaking portion 32 did not break due to a strong impact on the portion other than the breaking portion 32 from the design surface side of the instrument panel. in this way,
It has been found that the airbag door 31 according to the present invention has sufficient connection strength to the panel body with respect to low temperature impact. The instrument panel 30 integrally formed with the airbag door 31 was also subjected to head impact evaluation. Specifically, the prescribed head model is 25 ±
It collided with the airbag door 31 at 0.5 km / h. As a result, the regulation and regulation values were cleared. Thus, it was found that the airbag door 31 according to the present invention has good structural strength with respect to head impact.

In the present embodiment, the rectangular airbag door 31 is formed by forming the broken portion having a rectangular shape, but by changing the shape of the broken portion 32 as appropriate, a circular shape or other shapes can be obtained. It is also possible to form a rectangular airbag door. In addition, the breaking portion 32 is formed in a U shape,
Further, the airbag door 31 may be configured to be able to be opened one side by forming a weak portion that does not break at the U-shaped open portion so that the weak portion serves as a hinge.

FIG. 9 is a partial sectional view of an injection molding apparatus equipped with an injection molding die B according to the second embodiment of the present invention. The injection molding die B includes an airbag door forming mechanism 6 including a core 16 having a shape different from that of the above-described embodiment. The core 16 has a shape for forming not only a breakage portion that defines the airbag door but also a breakage portion that allows the airbag door itself to be opened. That is, FIG.
Of the apparently three cores 16 in the sectional view of FIG. 2, two on both sides are for forming a rupture portion that defines the airbag door, and one in the center is a rupture that allows the airbag door to be opened. For forming a part. However,
In the present embodiment, these apparently three cores 16 are provided.
Are connected outside the figure to form an integral core 16. The movable die 4 is provided with core through grooves 10 ′ corresponding to the shape of the core 16. The core 16 is
It has a projecting blade and a retracting blade having the same shape as the core 7 described above (not shown). The other configurations are the same as those described above regarding the first embodiment.

FIG. 10 is a partial cross-sectional perspective view of the airbag door 41 integrally formed with the instrument panel 40 by using the injection molding die B shown in FIG. In the instrument panel 40, a broken portion 42a formed by the cores 16 apparently located at both ends in FIG.
And a fractured portion 42b formed by the core 16 apparently located at the center in FIG. The breakage portion 42a defines the airbag door 41. When the airbag door 41 receives a pressing force from the inflating airbag, the airbag door 41 is disengaged from the instrument panel 40 due to the breakage of the breakage portion 42a, and splits due to the breakage of the breakage portion 42b. If the fractured portion 42b is formed to be weaker than the fractured portion 42a by adjusting the groove depth, the fractured portion 42b is more likely to be fractured first when the airbag is inflated. Outcome is guaranteed. The shape of the part of the airbag door 41 not shown is
It is assumed that the cross section is a plane of symmetry and is substantially symmetrical to the shape of the illustrated portion.

The fractured portion 42a and the fractured portion 42b are not bulged on the design surface of the instrument panel 40, and on the design surface side, the airbag door 41 and the panel body are connected in a flush manner. Further, the airbag door 41 can show good results in the above-described low temperature impact evaluation and head impact evaluation.

FIG. 11 is a partial sectional view of an injection molding apparatus equipped with an injection molding die C according to the third embodiment of the present invention. FIG. 11 corresponds to FIG. 2 according to the first embodiment,
The cross section in the extending direction of the core is well represented. The configuration of the cross section in the transverse direction is the same as that in FIG. The fractured part forming mechanism 6 of this embodiment is different from the core 1 of the first embodiment.
Have 7. The core 17 has a plurality of blades 1 at a predetermined pitch.
7a. The protruding blade 17a has a tapered shape in both the cross section in the extending direction of the core 17 and the cross section in the transverse direction. The maximum length of the core 7 in the extending direction is 0.5 to 5.
The maximum width of the cross section in the transverse direction is 0.5 to 2.0 mm. The movable die 4 is provided with a plurality of through holes 18 that open at the gap defining surface 4 a, and the respective projecting blades 17 are slidably inserted into the through holes 18.

FIG. 12 shows the movable die 4 in this embodiment.
2 is a partially enlarged plan view of the vicinity of a through hole 18. FIG. The cross section taken along the line XI'-XI 'in FIG. 12 corresponds to the cross section of the core 17 shown in FIG. The through hole 18 is formed by fitting a fixed core 4c having a groove formed on its side surface into the opening of the mold body 4b opened in a range substantially corresponding to the airbag door forming region S. There is.
However, in the present invention, the through hole 18 is formed by punching the mold 4 itself without providing the above-described opening.
May be provided. The other configuration of the injection molding die C is the same as that described above with respect to the first embodiment.

When the airbag door is integrally molded with the instrument panel using the injection molding mold C, the core 17 is positioned at the retracted position by the hydraulic cylinder 9 in the mold clamping step, as shown in FIG. And is in a standby state. Specifically, the upper end of the protruding blade 17a is in a state of being retracted from the space defining surface 4a of the movable die 4. The resin material injection step is the same as that described above with respect to the first embodiment. In the fracture portion forming step, as shown in FIG.
The hydraulic cylinder 9 extends and drives the piston rod 9a so that the support plate 8 and the core 17 supported and fixed to the support plate 8 advance from the retracted position to the fracture forming position. In this step, the protruding blade 17a in the process of pushing in presses the resin material 15, but the resin material 15 that has been pressed is pressed.
In addition to the side direction of the fractured part, the blade 17 along the fractured part
It can also flow out to between a. The resin material 15 is not directly pressed by the core 17 between the protruding blades 17 a. Therefore, the uniformity of the density of the resin material is ensured before cooling. In the present embodiment, the distance between the tip of the blade 17a of the core 17 and the core with heater 5 at the breaking portion forming position is 0.1 to 1.5 mm. The subsequent core retreating step and cooling step are the same as those described above for the first embodiment.

According to the above steps using the injection molding die C, the airbag can be integrally molded with the instrument panel while exhibiting the same panel design surface as shown in FIG. That is, on the design surface, the airbag door and the panel body can be formed into a shape in which they are connected to each other in the same plane.

FIG. 14 is a cross-sectional view in the extending direction of the fractured portion 52 formed using the injection molding die C, which corresponds to FIG. 8 according to the first embodiment. In the present embodiment, the breaking portion 5
In No. 2, the thin portions 52a are continuously formed at a constant pitch, and unevenness is provided in the member thickness. Such a concavo-convex shape is provided in the core 17
It substantially corresponds to the continuous repeating shape of a. Then, the fractured portion 52 having such a configuration can show good results in the low temperature impact evaluation and the head impact evaluation.

FIG. 15 is a partial cross-sectional view of an injection molding apparatus equipped with an injection molding die D according to the fourth embodiment of the present invention. It corresponds to FIG. 2 according to the first embodiment, and the cross section in the extending direction of the core is well shown. The configuration of the cross section in the transverse direction is the same as that in FIG. The fractured part forming mechanism 6 of this embodiment has a core 19 and a support plate 20 different from those of the first embodiment. The core 19 has a plurality of blades 19a provided at a constant pitch. The protruding blade 19a is composed of a body portion 19a 'which is a tapered round pin and a collar portion 19a'', and the diameter of the body portion 19a' is 0.3 to 5.0 mm.
Is. The support plate 20 is composed of a base 20a and a lid 20b, and the lid 20b is provided with a round window portion 20b 'through which a body portion 19' of the blade 19 is inserted.

As shown in FIG. 16, the round window portion 20b 'is
It has a slightly larger diameter than the body portion 19a '. On the other hand, the base 20a and the lid 20b sandwich the collar portion 19a ″ from above and below, and the collar portion 19a ″ is not fixed to the base 20a or the lid 20b. In this way, the protruding blade 19a of the present embodiment is supported by the support plate 20 with play that allows sliding displacement in the direction indicated by the arrow P. Further, as shown in FIG. 15, the movable die 4 is provided with a plurality of round hole through holes 21 that open at the void defining surface 4 a, and each protruding blade 19 a slides with respect to the through hole 21. It is movably inserted.

FIG. 17 shows the movable mold 4 according to this embodiment.
2 is a partially enlarged plan view of the vicinity of a through hole 21. FIG. The cross section taken along the line XV'-XV 'in FIG. 17 corresponds to the cross section of the core 19 shown in FIG. The through hole 21 is fixed core 4 fitted into the opening of the mold body 4b opened in a range substantially corresponding to the airbag door forming region S.
It is provided at a constant pitch near the peripheral edge of c '. However, in the present invention, the through hole 21 may be provided by punching the die 4 itself without providing the above-described opening. The other configurations of the injection molding die D are the same as those described above with respect to the first embodiment.

The injection-molding die D of this embodiment having the above structure can be relatively easily manufactured. Specifically, the through hole 21 is a round hole, and the protruding blade 17a
Is a round pin, and the supporting plate 20 has a displaceable play to support the blades 19a, so that the blades 19a are precisely positioned with respect to the through holes 21 in the production of the mold 4. There is no need to match. When the projecting blade 19a having play and attached to the support plate 20 is inserted into the through hole 21 of the movable die 4, the tip of the round pin projecting blade 19a has a round hole through hole 21.
If the blades 19a are slightly displaced from the through-holes 21, the blades 19a are displaced on the support plate 20 in a direction intersecting the insertion direction within a range that allows play. , Because it is automatically aligned. as a result,
This makes it easy to manufacture the injection molding die D.

When the airbag door is integrally molded with the instrument panel using the injection molding mold D, the core 19 is positioned at the retracted position by the hydraulic cylinder 9 in the mold clamping step as shown in FIG. And is in a standby state. Specifically, the upper end of the protruding blade 19a is in a state of being retracted from the space defining surface 4a of the movable die 4. The subsequent resin material injection step, fractured part formation step, core retreat step, cooling step, etc. are the same as those described above for the first embodiment.

Also by the above-mentioned process using the injection molding die D, the airbag can be integrally molded with the instrument panel while exhibiting the same panel design surface as shown in FIG. That is, on the design side, the airbag door and the panel body are flush with each other. The fractured portion has a cross-sectional shape in the extending direction that is substantially the same as that of FIG. 14 according to the third embodiment. That is, the fractured portion formed by the injection-molding die D is composed of thin-walled portions that are continuous at a constant pitch, and has irregularities in the member thickness. Such a concavo-convex shape substantially corresponds to the continuous repeating shape of the round pin projecting blade 19a in the core 19. Then, the fractured portion having such a configuration can show good results in the low temperature impact evaluation and the head impact evaluation.

The embodiment of the present invention has been described above by taking the airbag door of the passenger seat airbag as an example.
The present invention can also be applied to the airbag door of a steering airbag.

[0059]

According to the present invention, when the airbag door is integrally formed with the instrument panel,
It is possible to form an airbag door that does not have a wall thickness while maintaining an appropriate connection strength to the panel body of the airbag door. Further, according to the present invention, the fractured portion that defines the airbag door is formed flush with other portions on the instrument panel design surface, and it is possible to maintain the aesthetic appearance of the instrument panel design surface.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an injection molding device equipped with an injection molding die according to a first embodiment of the present invention.

2 is a cross-sectional view taken along the line II-II of FIG.

FIG. 3 is a partially enlarged sectional view of another blade in the present invention.

FIG. 4 shows a resin material injection step in the airbag door molding method according to the present invention.

FIG. 5 shows a fracture portion forming step in the airbag door molding method according to the present invention.

FIG. 6 shows a core retreating step in the airbag door molding method according to the present invention.

FIG. 7 is a partial cross-sectional perspective view of the airbag door integrally formed with the instrument panel according to the present invention.

8 is a cross-sectional view taken along the line VIII-VIII of FIG.

FIG. 9 is a partial cross-sectional view of an injection molding die according to a second embodiment of the present invention.

10 is a partial cross-sectional perspective view of an airbag door integrally molded with an instrument panel using the injection molding die shown in FIG.

FIG. 11 is a cross-sectional view of the injection molding die according to the third exemplary embodiment of the present invention, which corresponds to line II-II in FIG. 1.

12 is a partially enlarged view of a gap defining surface of a movable die of the injection molding die shown in FIG.

FIG. 13 shows a fractured part forming step using the injection molding die shown in FIG. 11.

FIG. 14 is a cross-sectional view in the extension direction of a fractured portion formed using the injection molding die shown in FIG.

FIG. 15 is a cross-sectional view of the injection molding die according to the fourth exemplary embodiment of the present invention, which corresponds to line II-II in FIG. 1.

FIG. 16 is an enlarged view of a main part for explaining a manner of supporting the blade by the support plate according to the fourth embodiment.

FIG. 17 is a partially enlarged view of a gap defining surface of a movable die of the injection molding die shown in FIG.

FIG. 18 is a perspective view of an instrument panel having an airbag door formed as a separate body by a conventional method.

FIG. 19 is a partial cross-sectional perspective view of an airbag door installation location in the instrument panel shown in FIG. 18.

[Explanation of symbols]

A, B, C, D Injection mold S Airbag door forming area 3 fixed type 4 movable 4a Void defining surface 5 Core with heater 7, 16, 17, 19 cores 7a, 17a, 19a protruding blade 7b Retracting blade 8,20 Core support plate 10,10 'core through groove 13 Guide post 14 Void 15 Resin material 18,21 through holes 30,40,50,100 Instrument panel 31,41,51,101 Airbag door 32, 42a, 42b, 52 Broken portion

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuji Saito             2-1-1 Taoyuan, Ikeda-shi, Osaka Daiha             Tsu Industry Co., Ltd. (72) Inventor Shinya Takemura             2-1-1 Taoyuan, Ikeda-shi, Osaka Daiha             Tsu Industry Co., Ltd. (72) Inventor Kazuto Ishida             2-1-1 Taoyuan, Ikeda-shi, Osaka Daiha             Tsu Industry Co., Ltd. (72) Inventor Hirokichi Hirose             3-90 Noritake Shinmachi 3-chome, Nishi-ku, Nagoya, Aichi Prefecture             No. Tatematsu Mold Industry Co., Ltd. F term (reference) 3D044 BA01 BA07 BA11 BB01 BC01                       BC02 BC03 BC13                 3D054 AA14 BB09                 4F202 AH25 CA11 CB01 CK06 CK35                       CK54 CK84

Claims (7)

[Claims] 1. A first mold body and a second mold body for defining a void filled with a resin material, and a second mold body, which is provided on the second mold body and moves back and forth with respect to the first mold body. A movable fractured part forming core, wherein the core is formed from the second mold body so that the thickness of the fractured part formed by the core changes in the extending direction of the fractured part. The mold for injection molding according to claim 1, further comprising a plurality of blades protruding in the direction of the mold body. 2. The injection molding die according to claim 1, wherein the core has a retracting blade that is continuous with the protruding blade between the adjacent protruding blades. 3. The second mold body has a plurality of through holes that open at a void defining surface, and the projecting blade is provided slidably with respect to the through holes. The mold for injection molding according to. 4. The injection molding die according to claim 3, wherein the through hole has a round hole shape, and the protruding blade is a round pin. 5. The projecting blade is supported by a support plate connected to a cylinder for driving the core forward and backward, with play that is displaceable in a direction intersecting the forward and backward direction of the core. The mold for injection molding according to claim 4. 6. The mold for injection molding according to claim 1, wherein the protruding blade has a tapered shape. 7. A method for integrally forming an airbag door on an instrument panel, comprising a step of bringing a first mold body and a second mold body close to each other to perform mold clamping, and the first mold body. And a step of injecting a resin material into a space defined by the second mold body, and a step of injecting the resin material to solidifying the resin material, the resin material being provided in the second mold body. And a step of displacing a core for forming a fracture portion that can be moved forward and backward with respect to the first mold body from a retracted position toward a fracture portion formation position toward the first mold body, the core comprising: It is characterized by having a plurality of blades protruding from the second mold body in the direction of the first mold body so that the thickness of the fractured part formed by the core changes in the breaking part extension direction. , Airbag door molding method.