JP3645599B2 - Manufacturing method of door panel and foam composite - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a foam composite formed by forming a foam layer in a hollow molded body obtained by blow molding a thermoplastic resin, and a method for producing the same.
[0002]
[Prior art]
According to recent statistics, side collisions account for about half of automobile collisions. In the event of a side collision, the outer panel of the door part is greatly deformed inward due to the impact of the collision, and the occupant is struck hard against the trim board. Sometimes died.
[0003]
Therefore, in order to protect the occupant in the case of a side collision, as shown in FIG. A foam pad material 56 is fixed between the inner panel 54 and the trim board 55 with an adhesive or the like to reduce the impact energy received by the occupant.
[0004]
[Problems to be solved by the invention]
However, since the guard bar 53 is made of a steel plate, the weight is large, which increases the weight of the entire vehicle and reduces fuel consumption.
Further, it is necessary to perform troublesome mounting work such as welding the guard bar 53 to the outer panel 52 and welding the pad material 55 between the inner panel 54 and the trim board 55, thereby increasing the manufacturing time and manufacturing cost of the door portion 51. I was letting.
[0005]
The present invention has been made in view of such conventional problems, and reduces the weight of the guard bar to improve fuel consumption, and eliminates the troublesome mounting work of the guard bar and the pad material, thereby manufacturing the door portion. The objective is to reduce time and manufacturing costs.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 is a door panel made of a foam composite formed by forming a plurality of foam layers having different properties in a hollow molded body obtained by blow molding a thermoplastic resin , The foam layer comprises a reinforcing foam layer as a guard bar and a cushioning foam layer as a pad material .
[0007]
According to the second aspect of the present invention, a parison made of a thermoplastic resin suspended in a molding die is blow-molded to form a hollow molded body, and the hollow molded body is cooled before solidifying. In the method for producing a foamed composite in which thermoplastic pre-expanded particles are filled and heated and fused to form a foamed layer, the hollow molded body is divided into a plurality of regions by a service blow pipe , and the types are classified into the divided regions. The present invention provides a method for producing a foam composite comprising filling different thermoplastic pre-expanded particles to form a plurality of foam layers having different properties.
[0008]
【Example】
First, the door panel of the present invention, that is, the inner panel 2 integrated with the trim board of the door portion 1 of the automobile will be described.
[0009]
As shown in FIG. 1, FIG. 2 and FIG. 3, the door panel 3 of the present invention includes a reinforcing foam layer 5 in which a thermoplastic pre-foamed particle is heat-fused into a hollow molded body in which a thermoplastic resin is blow-molded, and a cushioning material. The foaming layers 6 and 7 are formed, the reinforcing foaming layer 5 has a role as a guard bar, and the cushioning foaming layers 6 and 7 have a role as a pad material.
[0010]
The reinforcing foam layer 5 is designed to prevent the outer panel 8 from being easily deformed by increasing the specific gravity, and the buffer foam layers 6, 7 are designed to absorb the buffer by reducing the specific gravity. It is designed to fully reduce the impact energy.
[0011]
By making the guard bar made of foam, the weight can be reduced, fuel efficiency can be improved, and the role of the guard bar and pad material is fulfilled in the integrally molded body, so a troublesome mounting process is unnecessary, and the door part Manufacturing time and manufacturing cost can be reduced.
[0012]
Next, the case where the door panel of this invention is manufactured using the manufacturing apparatus shown in FIG. 4 is demonstrated about the manufacturing method of the foam composite of this invention .
[0013]
First, the parison 11 made of a thermoplastic resin is suspended between the molding dies 9 and 10, and the molding dies 9 and 10 are closed as shown in FIG. Insert into the parison 11.
[0014]
Here, polyethylene, polypropylene, ABS, or the like can be used as the thermoplastic resin, but polypropylene (softening point 110 ° C.) was used in this example.
[0015]
Next, the air supply valves 14 and 15 are opened, and air with a pressure of 6 kg / cm ² G is blown into the parison 11 from the pipes 16 and 17 through the service blow pipes 12 and 13 for 10 seconds, as shown in FIG. As shown, the hollow molded body 4 is formed by blow molding.
[0016]
Here, since the space | interval of the service blow pipes 12 and 13 and the inner wall face of the hollow molded object 4 is made very narrow, the service blow pipes 12 and 13 are three inside 18, 19 and 20 in the hollow molded object 4. It plays a role of dividing into areas.
[0017]
And while the temperature of the hollow molded object 4 exists in the state of 140 to 200 degreeC more than a softening point, as shown to FIG.5 (C), the said inside in the hollow molded object 4 with the filling guns 21,22,23 is shown. Pre-expanded particles 24, 25, and 26 are filled in the regions 18, 19, and 20, respectively.
[0018]
Here, the thermoplastic pre-expanded particles 24, 25, and 26 are not particularly limited, but the strength of the foamed composite increases as the hollow molded body and the foamed layer are fused. It is preferable to use the same type as the thermoplastic resin. When the thermoplastic resin is polyethylene, polyethylene or styrene-modified polyethylene polymer resin pre-expanded particles, and when polypropylene is polypropylene pre-expanded particles, In the case of ABS, it is preferable to use polystyrene or ABS pre-expanded particles, but in this example, polypropylene pre-expanded particles were used.
[0019]
Further, the region 18 has pre-expanded particles 24 with a specific gravity of 0.1 to 0.05, here 0.1, and the regions 19 and 20 have pre-expanded with a specific gravity of 0.033 to 0.015, here 0.02. Particles 25 and 26 were filled.
[0020]
Then, the steam supply valves 27 and 28 are opened, and 3.5 kg / cm ² G steam is blown into the hollow molded body 4 from the pipes 16 and 17 through the service blow pipes 12 and 13 for 20 seconds. ), The pre-expanded particles 24, 25, and 26 are heated and fused together to form the reinforcing foam layer 5 and the buffer foam layers 6 and 7 in the hollow molded body 4.
[0021]
Finally, the drain discharge valves 29 and 30 are opened, the steam condensate in the hollow molded body 4 is vacuum-sucked and discharged through the service blow pipes 12 and 13, and through the molds 9 and 10. The foam composite 3 is cooled, the service blow pipes 12 and 13 are extracted from the molding dies 9 and 10, the molding dies 9 and 10 are opened, and the foam composite 3 is taken out.
[0022]
In the present embodiment, the automobile door panel of the present invention has been described. Furthermore, manufacturing an automobile door panel by the method for manufacturing a foam composite of the present invention has been described. However, the foam composite manufacturing method of the present invention has a plurality of functions as an integrally molded product other than the door panel of the present invention, and automobiles such as bumpers, seat backs, flip plates, spoilers, fenders and the like that are desired to be reduced in weight. Of course, it may be used for manufacturing parts.
[0023]
In addition, the same thermoplastic pre-expanded particles were used, but corresponding to the above applications, pre-expanded particles with different materials, particle sizes, expansion ratios, colors, etc. were filled in each region in the hollow molded body. May be.
[0024]
Next, since the bending strength can be a stiffness indicator of the foamed composite, the bending strength when the specific gravity of the foamed layer in the hollow molded body was changed in various ways was measured by the following measurement sample and measurement method.
[0025]
[Measurement sample]
Dimensions: Length 430 x width 250 x thickness 30 mm (hollow molded body thickness 2.5 mm)
Material:
・ Hollow molding: Low density polyethylene (LL polyethylene manufactured by Nippon Oil)
-Foam layer: Styrene-modified polyethylene (trade name; Ellenpole manufactured by Mitsubishi Chemical BSF)
〔Measuring method〕
In accordance with JIS A-9511, the measurement sample was pressed at a span of 300 mm and a pressing speed of 10 mm / min.
[0026]
The measurement results are as shown in FIG. 6, and as is clear from FIG. 6, it can be seen that the bending strength increases proportionally as the specific gravity of the foamed layer increases.
Therefore, if such a graph relating to bending strength is prepared in advance, it becomes easy to appropriately select pre-expanded particles to be used for forming the reinforcing foam layer or the buffer foam layer.
[0027]
【The invention's effect】
According to the door panel made of the composite foam of the present invention, for example, the guard bar is made of foam, so that the weight can be reduced and the fuel consumption can be improved. Therefore, troublesome mounting work is unnecessary, and the manufacturing time and manufacturing cost of the door portion can be reduced.
[0028]
In addition, according to the method for producing a composite foam of the present invention, various composite foams can be easily formed as an integral molded body including a door panel made of a composite foam as an integral molded body that serves as a guard bar and a pad material. Can be manufactured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a composite foam of the present invention applied to a door panel of an automobile.
FIG. 2 is a cut perspective view showing a structure of a door portion of an automobile when the composite foam of the present invention is applied.
FIG. 3 is a longitudinal sectional view showing a structure of a door portion of an automobile when the composite foam of the present invention is applied.
FIG. 4 is an explanatory view showing an example of a composite foam production apparatus of the present invention.
FIG. 5 is an explanatory view showing a method for producing a composite foam of the present invention, wherein (A) is when the mold is closed, (B) is when a hollow molded body is formed, (C) is when pre-expanded particles are filled, (D ) Is a diagram showing each step in forming the foamed layer.
FIG. 6 is a diagram showing the relationship between the specific gravity of a foam layer in a hollow molded body and the bending strength.
FIG. 7 is a cut perspective view showing a structure of a door portion of a conventional automobile.
[Explanation of symbols]
3 door panel 4 hollow molded body 5 foam layer for reinforcement 6 foam layer for buffer 9 molding die 10 molding die 11 parison 12 useful blow pipe 13 useful blow pipe 24 pre-foamed particle 25 pre-foamed particle 26 pre-foamed particle

Claims (2)

A door panel made of a foam composite formed by forming a plurality of foam layers having different properties in a hollow molded body obtained by blow molding a thermoplastic resin , wherein the foam layer is a reinforcing foam layer as a guard bar and a pad material. A door panel characterized by comprising a foaming layer for cushioning. Blow molding a parison made of a thermoplastic resin suspended in a molding die to form a hollow molded body, and before the hollow molded body is cooled and solidified, the hollow molded body is filled with thermoplastic pre-expanded particles, In the method of manufacturing a foamed composite that forms a foamed layer by heat fusion, the hollow molded body is divided into a plurality of regions by a service blow pipe and filled with different types of thermoplastic pre-expanded particles. And forming a plurality of foamed layers having different properties.

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