JP2003112333A - Method of manufacturing structure for automobile parts and structure for automobile parts manufactured by the method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Even for a resin part requiring reinforcement by a closed panel having high strength and rigidity, the resin and the closed panel are securely connected at the time of molding without using a complicated mold, and closed by injection pressure. Provided is a method for manufacturing a lightweight and highly rigid structure for an automobile part, which can prevent the resin from being filled into the inside of the closed section panel while preventing plastic deformation of the section panel, and a structure for an automobile part manufactured by the method. I do. SOLUTION: This method is a method for manufacturing a structure for an automobile part, in which after setting a panel 1 having a closed cross section in a mold in advance, a resin 3 is injected and molded so as to cover at least a part of an outer surface of the panel 1. Then, a through hole 2 is provided on the side surface of the panel 1, the panel 1 is set in a mold, and a part of the resin 3 injected into the mold is caused to flow from the through hole 2 into the inside of the closed section of the panel 1. 1 from the end of the closed section to the inside of the closed section.
And the resin 3 is blocked by the nitrogen gas G on the inner peripheral edge of the through hole 2 and solidified by cooling to form the engagement projections 4. The resin 3 that has been solidified by cooling is joined to the panel 1 by the engagement projections 4.
The mold is taken out from the mold in a state of being connected by the engagement with the through hole 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a structure for automobile parts and a structure for automobile parts manufactured by the method.

[0002]

2. Description of the Related Art Regarding automobile parts, an example in which some or all of them are made of a resin material is increasing for the purpose of reducing the number of parts and weight reduction. Parts such as doors, trunk lids, radiator core supports, and cargo beds (beds), which require strength and rigidity, are often manufactured from resin materials. In this case, the resin materials used range widely from thermoplastic resin stampable sheets such as PP (polypropylene) and thermosetting resin stampable sheets to nylon resins.

In many cases, these resin parts are reinforced at necessary parts with metal panels in order to obtain required strength and rigidity. When joining metal panels, set the metal panel in advance in the molding die for resin parts, and inject the resin around the metal panels when molding resin parts, taking into consideration the number of man-hours and cost of parts. Insert molding is often used in which the components are integrally joined together.

[0004]

The structure of the metal panel to be set in the mold may have both an open cross section and a closed cross section as shown in JP-A-2-199400. The closed cross section is superior to the open cross section in the specific rigidity of bending and torsion (rigidity per unit mass), and is advantageous in terms of the reinforcing effect.
Since the cavity exists inside the closed cross section, when the molten resin is normally injected after the metallic panel is set in the mold, the metallic panel is plastically deformed by the injection pressure. Further, since the resin and the metal panel are not in mechanical connection but in surface contact with each other, there is an undeniable possibility that the metal panel may be peeled off or fallen off from the resin at the product stage.

Therefore, a method may be considered in which the injection pressure is dispersed by providing a through hole in the metal panel and introducing the molten resin also inside the closed cross section. In this case, the cavity of the metal panel having the closed cross section is considered. Then, the resin is filled in, and the weight reducing effect of the cavity is impaired. In order to avoid this, if a complicated die structure having a member for supporting the inner side of the closed cross section such as a slide core die is adopted, there is a problem that the die cost increases and the degree of freedom in the shape of parts is restricted.

The present invention has been made in view of the above-mentioned prior art, and even for resin parts requiring reinforcement by a closed cross-section panel in terms of strength and rigidity, the resin and the closed cross-section panel can be used without using a complicated mold. And a method of manufacturing a structure for an automobile component, which is lightweight and has high rigidity, because it is possible to prevent the resin from filling the inside of the closed cross-section panel while preventing the plastic deformation of the closed cross-section panel due to injection pressure, An object of the present invention is to provide a structure for automobile parts manufactured by the method.

[0007]

In order to achieve the object of the above paragraph, the invention of claim 1 covers a panel having a closed cross section in a mold and then covers at least a part of the outer surface of the panel. A method for manufacturing a structure for an automobile part, which comprises injecting and molding a resin as described above, wherein a through hole is provided in a side surface of the panel, the panel is set in the mold, and the resin is injected into the mold. A part of the gas is introduced into the closed cross section of the panel from the through hole, while a gas is injected into the closed cross section from the end of the closed cross section of the panel, and the gas causes the resin to flow at the inner peripheral edge of the through hole. Forming an engaging protrusion by blocking and cooling and solidifying the resin and the resin solidified by cooling,
It is characterized in that it is taken out from the mold in a state where the engaging projection and the through hole are engaged with each other to be coupled.

According to the invention of claim 1, 1) a part of the resin is made to flow into the inside of the closed cross section of the panel from the through hole to disperse the load of injection pressure, and from the end of the closed cross section of the panel to the inside of the closed cross section. By injecting a gas into the and supporting the closed cross section from the inside against the injection pressure of the gas, plastic deformation of the closed cross section panel can be prevented. 2) The resin is blocked by the gas at the inner peripheral edge of the through hole and is cooled and solidified to form an engaging projection, and the resin that has been solidified by cooling and the panel are joined by the engagement between the engaging projection and the through hole. Since it is removed from the mold in this state, it is possible to avoid an increase in weight due to resin filling inside the panel with closed cross section, and to use engaging protrusions and through holes without using fastening members such as bolts and nuts or complicated molds. By engaging with, the resin and the panel can be reliably coupled at the same time as molding. Due to the above, even for parts that require reinforcement with a closed cross-section panel for strength and rigidity, the resin and the closed cross-section panel can be reliably joined at the time of molding without using a complicated mold, and plastic deformation of the closed cross-section panel due to injection pressure can be prevented. At the same time, it is possible to avoid the resin filling into the inside of the panel having the closed cross section, and it is possible to obtain a lightweight and highly rigid structure for automobile parts.

According to a second aspect of the present invention, there is provided a method for manufacturing a structure for automobile parts according to the first aspect, wherein a part of the resin is introduced into the closed cross section of the panel from the through hole or at the same time. Immediately after the flow, the gas is injected into the closed cross section from the end of the closed cross section of the panel.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, a part of the resin is introduced into the closed cross section of the panel from the through hole at the same time or immediately after the inflow of the resin. Since gas is injected from the end of the closed cross section into the closed cross section, the resin is not obstructed by the pressure of the gas when flowing into the closed cross section of the panel, and the engagement protrusion does not have to increase the injection pressure of the resin so much. Can be formed, and the plastic deformation of the panel can be more reliably prevented.

According to a third aspect of the present invention, there is provided the method for manufacturing the automobile part structure according to the first aspect, wherein a part of the resin is flown into the closed cross section of the panel from the through hole. The gas is injected from the end of the closed cross section of the panel into the closed cross section of the panel at a pressure that allows the resin to flow in, and a part of the resin is caused to flow into the closed cross section of the panel from the through hole, or at the same time. Immediately after this, the pressure of the gas is increased.

According to the invention of claim 3, in addition to the effect of the invention of claim 1, before a part of the resin is made to flow into the inside of the closed cross section of the panel from the through hole, the pressure at which the resin is allowed to flow is set. Since the gas is injected from the end of the closed cross section of the panel into the closed cross section of the panel, the gas pressure is increased at the same time as or immediately after flowing a part of the resin into the closed cross section of the panel through the through hole. Before allowing a part of the above to flow into the closed cross section of the panel from the through hole, the gas pressure acts on the inner surface of the panel to support the closed cross section from the inside against the injection pressure of the resin. Thus, while preventing plastic deformation of the panel, at the same time as or immediately after flowing a part of the resin into the closed cross section of the panel from the through hole, the pressure of the gas is increased to block the inflowing resin. Stop and cool and solidify One of the engaging projection can be surely formed, can be avoided weight increase due to excessive resin filling the closed section internal panel.

The invention of claim 4 is the method of manufacturing a structure for automobile parts according to any one of claims 1 to 3, wherein the resin is injected from the inner peripheral edge of the through hole by the flow of the gas to be injected. It is characterized in that it is made to flow along the inner surface of the closed cross section of the panel and then cooled and solidified.

According to the invention of claim 4, in addition to the effects of the inventions of claims 1 to 3, the flow of the injected gas causes the resin to flow from the inner peripheral edge of the through hole along the inner surface of the closed cross section of the panel. Since it is cooled and solidified after that, an engaging projection extending sufficiently long from the inner peripheral edge of the through hole along the inner surface of the closed cross section of the panel can be formed, so that the cooled and solidified resin and the panel can be more reliably coupled.

The invention of claim 5 is the method of manufacturing a structure for automobile parts according to any one of claims 1 to 4, wherein the resin is a thermoplastic resin containing a filler, and the panel is a metal material. The resin wall thickness of the outer surface of the panel is 0.5 mm or more and 4.0 mm or less, and the panel wall thickness is 0.5 mm or more and 2.0 mm or less.

According to the invention of claim 5, in addition to the effects of the inventions of claims 1 to 4, the resin is a thermoplastic resin containing a filler, and the panel is manufactured using a metal material. The resin wall thickness on the outer surface of the panel is 0.5 mm or more and 4.0.
Since the panel thickness is 0.5 mm or less and the panel thickness is 0.5 mm or more and 2.0 mm or less, it is possible to obtain a lightweight and highly rigid structure for automobile parts, which has a favorable balance between resin and panel in terms of rigidity and mass. .

Here, if the resin wall thickness is less than 0.5 mm, the strength of the resin becomes small and cracks may occur from the engaging projections. If it exceeds 4.0 mm, the panel made of a metal material is molded. It becomes difficult to prevent plastic deformation of the steel and the weight reduction effect becomes poor. Further, when the thickness of the panel made of a metal material is less than 0.5 mm, the strength due to the combination with the resin,
The rigidity improvement effect becomes poor, and it is more costly than the case of designing a component with only a metal material panel or resin. If it exceeds 2.0 mm, a component with only a metal material panel is designed. It is disadvantageous in terms of cost and weight.

A sixth aspect of the present invention is the method for manufacturing a structure for automobile parts according to the first to fifth aspects, wherein the total area of the through holes is 0.3% or more of the side area of the panel. %
It is characterized by the following.

According to the invention of claim 6, in addition to the effects of the inventions of claims 1 to 5, the total area of the through holes is 0.3% or more and 20% or less of the side area of the panel. The resin and the panel can be more reliably coupled by the engagement of the fitting protrusion and the through hole, and the resin is cooled and solidified while being blocked by the gas at the inner peripheral edge of the through hole to form a continuous cavity inside the closed cross-section panel. It is possible to ensure the weight, and avoid an increase in weight due to excessive resin filling.

Here, if the total area of the through holes is less than 0.3% of the side area of the panel, the resin is removed from the through holes within the panel closed cross section, especially when a glass fiber reinforced thermoplastic resin is used. Does not flow smoothly, and it becomes difficult to obtain a sufficient size of the engagement protrusion, and it becomes difficult to secure the bonding strength between the resin and the panel. On the other hand, if it exceeds 20%, it becomes difficult to block the resin at the inner peripheral edge of the through hole, and the resin that has flowed into the closed cross section of the panel forms partition walls, which tends to cause an increase in weight due to excessive resin filling. .

The invention of claim 7 is the method of manufacturing a structure for automobile parts according to any one of claims 1 to 6, wherein the gas is
An inert gas that does not react with or mix with the resin and is not adsorbed by the resin, and the pressure of the gas immediately after flowing a part of the resin into the closed cross section of the panel from the through hole is 1 MPa or more. It is characterized by being 30 MPa or less.

According to the invention of claim 7, in addition to the effects of the inventions of claims 1 to 6, the gas is an inert gas which does not react with or mix with the resin and is not adsorbed by the resin. The pressure of the gas immediately after flowing the part from the through hole into the closed cross section of the panel is 1 MPa or more and 30 MPa or less, so that the engagement protrusion and the through hole are engaged without causing an increase in weight due to excessive resin filling. As a result, the resin and the panel can be reliably joined together at the same time as molding.

If the pressure of the gas immediately after flowing a part of the resin from the through hole into the inside of the closed cross section of the panel is less than 1 MPa, the force of damming the resin at the inner peripheral edge of the through hole becomes small and the panel The resin that has flowed into the closed cross section forms a partition wall, resulting in an increase in weight due to excessive resin filling. On the contrary, when the pressure of the gas exceeds 30 MPa, the resin prevents the resin from flowing into the closed cross section of the panel from the through hole, and the engagement protrusion is not formed in a sufficient size. The resin and the panel are likely to be insufficiently coupled due to the engagement between the resin and the through hole.

The invention of claim 8 is a structure for automobile parts, which is produced by the method for manufacturing a structure for automobile parts according to any one of claims 1 to 7.

According to the invention of claim 8, since it is a structure for automobile parts manufactured by the method for manufacturing a structure for automobile parts according to claims 1 to 7, the effects of the invention of claims 1 to 7 are obtained. With such a structure, even if reinforcement with a closed cross-section panel is required in terms of strength and rigidity, it can be obtained as a lightweight and highly rigid resin component.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION In each of the above inventions, the cross-sectional shape of the panel to be set in the mold includes a square shape, a circular shape, an elliptical shape and the like, but other various polygonal shapes are used. be able to.

As the resin used for injection molding, one kind of various thermoplastic resins such as PP (polypropylene) and PA (polyamide) may be used alone, or a mixture of plural kinds of resins may be used. If necessary, one or a mixture of a plurality of these resins is used as a base material and
It is also possible to use composite materials in which one or more reinforcing materials are combined. Examples of such a reinforcing material include glass fiber and a card.
Examples thereof include bon fibers, organic fibers, inorganic fillers such as talc, whiskers, and metallic fillers.

It is more preferable that the total area of the through holes provided on the side surface of the panel is 0.3% or more and 20% or less of the side area of the panel. The shape of the through hole is not particularly limited, and various shapes such as a circular shape and a polygonal shape can be used, but a circular shape having a diameter of 2 to 15 mm, or at least one side of 2-1.
A 5 mm polygon or the like is common.

Various gases can be used as the gas to be injected into the closed cross section from the end of the closed cross section of the panel.
An inert gas that does not react with or mix with the molten resin, such as carbon dioxide gas, air, helium, neon, or argon, is preferable in terms of safety and workability.

[0030]

EXAMPLES The details of the present invention will be described below with reference to specific examples. However, the scope of the present invention is not limited to the scope of the following examples.

(Example 1) As shown in FIG. 1, the wall thickness is 1 m.
m, a circular through hole 2 having a diameter of 5 mm is formed at a substantially central portion of each side surface of a panel 1 made of a cold-rolled steel plate (hereinafter, abbreviated as SPCC) having a hollow rectangular parallelepiped shape having a square closed cross section with a side length of 30 mm and a length of 300 mm. Nine holes were provided per surface at 30 mm intervals from the direction end, and the total area of the circular through holes 2 was about 2% of the side area of the panel 1. The resin wall thickness outside the panel 1 is 2.5
The panel 1 was set in a mold so that the thickness became mm, and the molten resin 3 (polypropylene resin containing 40% by mass of glass fiber) was injected to the outer surface of the panel 1 at an injection pressure of 11 MPa. Immediately after flowing a part of the resin 3 from the circular through hole 2 into the inside of the square cross section of the panel 1, specifically, the resin 3 is at one end of the SPCC panel 1, that is, from the gate corresponding position T to P shown in FIG. Flowing in the direction and reaching the position of about 10 cm in the length direction (about one third of the total length of the panel), at 25 ° C. from the opening of the end of the closed cross section of the panel 1 to the inside of the closed cross section,
After injecting 0 MPa of nitrogen gas G and causing the resin 3 to flow from the inner peripheral edge of the circular through hole 2 along the inner surface of the closed cross section of the panel 1 by the flow and pressure of the nitrogen gas G in the panel length direction, The engaging projections 4 were formed by blocking and cooling and solidifying. Then, the cooled and solidified resin 3 and the panel 1 were taken out from the mold in a state where the resin 3 and the panel 1 were coupled by the engagement of the engagement projections 4 and the circular through holes 2 to obtain a structure for automobile parts. In addition, L shows a parting line position.

The following three items were evaluated for the obtained structure for automobile parts.

(1) Fastening state of the panel and the resin The fastening state of the closed cross section of the panel 1 and the resin 3 was visually observed. The case where the resin 3 enters from all the through holes 2 to the inside of the closed cross section of the panel 1 and the engagement between the engaging protrusions 4 and the through holes 2 is formed ○, particularly, the engaging protrusions 4 are inside the circular through hole 2. ⊚ when extending 5 mm or more from the side edge along the inner surface of the panel 1 closed cross section, and x when neither of the above is satisfied 3
The grade was evaluated.

(2) Situation of Resin Filling Inside Panel Closed Section Since the resin 3 is excessively filled inside the panel 1 closed section, the effect of weight reduction is impaired. Therefore, the filling state of the resin 3 was visually observed. . The case where the resin 3 was not excessively filled and the cavity penetrated the inside of the panel closed cross section was evaluated as ◯, and the case where it was not (the case where the resin partition wall was formed) was evaluated as x, and the evaluation was performed in two stages.

(3) Maintenance of panel shape Whether or not the panel 1 was plastically deformed before the mold was set was visually observed by cutting the structure for automobile parts. The case where the shape before setting the mold was almost maintained was evaluated as ◯, and the case where the shape was significantly deformed was evaluated as x, and the evaluation was performed in two stages. The manufacturing method of the structure for automobile parts described above and the evaluation results thereof,
The results are summarized in Table 1 together with other examples and comparative examples.

(Examples 2 to 16) In comparison with Example 1, an automobile part structure was manufactured and evaluated in the same manner as in Example 1 except that the manufacturing conditions were changed to those shown in Table 1. did. However, in Examples 2, 4, 7, 8 and 10, the point at which the nitrogen gas G is injected is "1" because the resin is SP.
It means the time when the liquid crystal flows into the through hole 2 of the CC panel 1.
In Example 16, the point at which the nitrogen gas G is injected is indicated as "0", which means the time at which the resin 3 is injected from the gate into the mold, and the nitrogen gas G injection pressure is set to "1 → 30MP.
"a" means that a part of the resin 3 was 1 MPa before flowing into the closed cross section of the panel 1 from the through hole 2 and was increased to 30 MPa immediately after flowing into the closed cross section of the panel 1. To do. The method of manufacturing the structure for automobile parts and the evaluation results thereof are summarized in Table 1 as in Example 1.

Comparative Examples 1 to 9 For automobile parts in the same manner as in Example 1 except that the manufacturing conditions were changed to those shown in Table 2 for Example 1 as in Example 1 above. The structure was manufactured and evaluated. However, in Comparative Example 1, both the diameter and the interval of the through hole 2 are shown as “−”, which means that the through hole 2 is not provided at all. In Comparative Example 7, the nitrogen gas G injection pressure is shown as “1 → 35 MPa”,
This means that the pressure was set to 1 MPa before a part of the resin 3 was made to flow from the through hole 2 into the closed cross section of the panel 1, and was increased to 35 MPa immediately after being made to flow into the closed cross section of the panel 1. Further, in Comparative Examples 8 and 9, the point of time when the nitrogen gas G was injected is indicated as "3" because a few seconds have passed after a part of the resin 3 was flown into the square cross section of the panel 1 from the through hole 2 and Specifically, it means the time when the resin 3 reaches a position of about 15 cm in the length direction (about 1/2 of the total length of the panel) from one end of the SPCC panel 1 (the position T corresponding to the gate in FIG. 3). Table 2 shows the method of manufacturing the structure for automobile parts and the evaluation results thereof.

From Tables 1 and 2, it can be seen that the evaluation results are good in each Example within the scope of the present invention.

[0039]

[Table 1]

[0040]

[Table 2]

Although the nitrogen gas G may be injected before the resin 3 flows into the through hole 2 of the panel, for example, when the resin 3 is injected from the gate T into the mold, the through hole of the panel 1 may be used. It can be seen that it is suitable to be made to flow at the same time as it is made to flow into No. 2 or immediately after it is made to flow (at the time of reaching the position of about 10 cm in the length direction from one end of the SPCC panel in this example and the comparative example).

Furthermore, when the injection of the nitrogen gas G is before the resin 3 flows into the through hole 2 of the panel 1, the injection pressure of the nitrogen gas G is made sufficiently lower than the injection pressure of the resin 3 to allow the inflow. However, it is preferable to increase the injection pressure of the nitrogen gas G immediately after the inflow.

The area ratio of the through hole 2 to the side surface of the panel 1 is preferably 0.3 to 20%, and nitrogen gas immediately after a part of the resin 3 is flown into the closed cross section of the panel 1 from the through hole 2. It is understood that the pressure of G is preferably 1 to 30 MPa.

Particularly, the injection pressure of the nitrogen gas G immediately after flowing a part of the resin 3 into the closed cross section of the panel 1 from the through hole 2 is set to 20 to 30 MPa, and the resin 3 is passed through the through hole 2 by the flow of the nitrogen gas G. It is possible to form the engaging projections 4 extending from the inner peripheral edge of the through hole 2 along the inner surface of the closed cross section of the panel 1 sufficiently by flowing the fluid from the inner peripheral edge of the inner cross section of the panel 1 along the inner surface of the closed cross section of the panel 1. Thus, it can be seen that the resin 3 and the panel 1 that have been solidified by cooling can be more reliably bonded to the panel 1.

The scope of application of the present invention is not limited to the above-mentioned resin and gas (nitrogen gas). Further, in the above embodiment, the panel shape is a rectangular parallelepiped, and the through holes are provided on each side surface, but the panel shape may have a curved surface portion,
The surface on which the through hole is provided may be a part of the side surface. Regarding the time of gas injection, in this embodiment, the time when the resin 3 reaches about 10 cm in the longitudinal direction of the outer surface of the panel 1 is taken as an example immediately after the resin 3 flows into the through hole 2. However, the arrival position of the resin is It varies depending on the panel shape, the diameter of the through hole, the total area ratio of the through hole to the panel side area, the position of the through hole, etc., and is not limited to about 10 cm in this embodiment. Further, in the embodiment, the entire outer side surface of the panel 1 is covered with the resin 3, but a part of the outer side surface may be covered.

[0046]

As described above, according to the present invention, 1) a part of the resin is flown into the inside of the closed cross section of the panel from the through hole to disperse the load of injection pressure and to close the panel. By injecting gas into the closed cross section from the end of the cross section, the pressure of the gas opposes the injection pressure and supports the closed cross section from the inside.
It is possible to prevent plastic deformation of the closed cross section panel. 2)
In the state where the resin is blocked by the inner peripheral edge of the through hole by the gas and is cooled and solidified to form the engaging projection, and the resin which is cooled and solidified and the panel are coupled by the engagement of the engaging projection and the through hole. Since it is taken out from the mold, it is possible to avoid an increase in weight due to resin filling inside the closed cross-section panel, and to use the engaging projections and through holes without using fastening members such as bolts and nuts or complicated molds. By the engagement, the resin and the panel can be reliably coupled at the same time as the molding. Due to the above, even for parts that require reinforcement with a closed cross-section panel for strength and rigidity, the resin and the closed cross-section panel can be reliably joined at the time of molding without using a complicated mold, and plastic deformation of the closed cross-section panel due to injection pressure can be prevented. At the same time, it is possible to avoid the resin filling into the inside of the panel having the closed cross section, and it is possible to obtain a lightweight and highly rigid structure for automobile parts.

[Brief description of drawings]

FIG. 1 is a cross-sectional view taken along the line AA of FIG. 3, showing a method for manufacturing an automobile part structure according to an embodiment of the present invention.

FIG. 2 is likewise a sectional view taken along the line BB of FIG.

FIG. 3 is a perspective view of relevant parts showing a method for manufacturing an automobile part structure according to an embodiment of the present invention.

[Explanation of symbols]

1 Cold Rolled Steel Sheet Panel 2 Through Hole 3 Polypropylene Resin Blended with Glass Fiber 4 Engagement Protrusion G Nitrogen Gas L Parting Line Position P Flow Direction of Polypropylene Resin Blended with Glass Fiber T Gate Corresponding Position

Claims (8)

[Claims] 1. A method of manufacturing a structure for automobile parts, comprising: setting a panel having a closed cross-section in a mold in advance, and then injecting a resin so as to cover at least a part of an outer surface of the panel and molding the resin. A through hole is provided on a side surface of the panel, the panel is set in the mold, and a part of the resin injected into the mold is flown into the closed cross section of the panel through the through hole; A gas is injected from the end of the closed cross section of the panel into the closed cross section, and the resin blocks the resin at the inner peripheral edge of the through hole and cools and solidifies to form an engaging projection, and the resin solidified by cooling and A method of manufacturing a structure for an automobile part, wherein the panel is taken out from the mold in a state where the panel is joined by the engagement of the engaging projection and the through hole. 2. The method of manufacturing a structure for automobile parts according to claim 1, wherein a part of the resin is made to flow into the closed cross section of the panel from the through hole at the same time or immediately after being made to flow. A method for manufacturing a structure for automobile parts, comprising injecting the gas into the inside of the closed cross section from an end of the closed cross section of the panel. 3. The method for manufacturing a structure for automobile parts according to claim 1, further comprising: flowing a portion of the resin into the closed cross section of the panel from the through hole. Injecting the gas into the closed cross-section from the closed cross-section end of the panel at an allowable pressure, at the same time or immediately after flowing a part of the resin into the closed cross-section of the panel from the through hole, A method for manufacturing a structure for automobile parts, comprising increasing the pressure of the gas. 4. The method for manufacturing a structure for automobile parts according to claim 1, wherein the resin flows from the inner peripheral edge of the through hole to the inner surface of the closed cross section of the panel by the flow of the gas to be injected. A method for manufacturing a structure for an automobile part, comprising: flowing along a groove and then solidifying by cooling. 5. The method of manufacturing a structure for an automobile part according to claim 1, wherein the resin is a thermoplastic resin containing a filler, and the panel is manufactured using a metal material. In addition, the resin thickness of the outer surface of the panel is 0.5 mm or more and 4.0 m
m or less, and the panel thickness is 0.5 mm or more and 2.0 mm or less, a manufacturing method of a structure for automobile parts. 6. The method for manufacturing a structure for automobile parts according to claim 1, wherein a total area of the through holes is 0.3 of a side area of the panel.
% Or more and 20% or less, the manufacturing method of the structure for automobile parts characterized by the above-mentioned. 7. The method for manufacturing a structure for automobile parts according to claim 1, wherein the gas is an inert gas that does not react with or mix with the resin and is not adsorbed by the resin, The pressure of the gas immediately after flowing a part of the resin from the through hole into the closed cross section of the panel is 1 MPa or more 3
A method for manufacturing a structure for an automobile part, which is 0 MPa or less. 8. A structure for automobile parts manufactured by the method for manufacturing a structure for automobile parts according to claim 1.